Inspection and Preventive Maintenance Procedures

Inspection and Preventive Maintenance Procedures
IPM Procedures
Inspection and Preventive Maintenance
Procedures
Procedure
Anesthesia Unit Vaporizers . . . .
Anesthesia Unit Ventilators . . . .
Anesthesia Units . . . . . . . . . .
Apnea Monitors . . . . . . . . . . .
Argon Surgical Lasers . . . . . . .
Aspirators . . . . . . . . . . . . . .
Autotransfusion Units . . . . . . .
Beds, Electric . . . . . . . . . . . .
Blood Pressure Monitors, Electronic
Indirect . . . . . . . . . . . . . .
Blood Pressure Monitors, Invasive
Blood/Solution Warmers . . . . . .
Capnometers and Multiple Medical
Gas Monitors . . . . . . . . . . .
Carbon Dioxide Surgical Lasers . .
Cardiac Resuscitators
. . . . . . .
Centrifuges . . . . . . . . . . . . .
Circulating-Fluid Pumps . . . . . .
Conductive Furniture and Floors .
Critical Care Ventilators . . . . . .
Cryosurgical Units . . . . . . . . .
Defibrillator/Monitors
. . . . . . .
Defibrillators . . . . . . . . . . . .
ECG Monitors . . . . . . . . . . . .
Electrical Receptacles
. . . . . . .
Electrocardiographs
. . . . . . . .
Electrosurgical Units . . . . . . . .
Frequency-Doubled Nd:YAG
Surgical Lasers
. . . . . . . . .
General Devices . . . . . . . . . . .
Heart-Lung Bypass Units . . . . .
Heated Humidifiers . . . . . . . . .
Hemodialysis Units . . . . . . . . .
Ho:YAG Surgical Lasers . . . . . .
Hypo/Hyperthermia Units . . . . .
257941
456-0595
A NONPROFIT AGENCY
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No.
Procedure
436-0595
461-0595
400-0595
420-0595
462-0595
433-0595
449-0595
402-0595
Infant Incubators . . . . . . . . . . .
Infusion Devices
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Intra-Aortic Balloon Pumps . . . . .
Isolated Power Systems
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Laparoscopic Insufflators . . . . . . .
Mammography Units . . . . . . . . .
Medical Gas/Vacuum Systems . . . .
Mobile C-arms
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Mobile X-ray Units . . . . . . . . . .
Nd:YAG Surgical Lasers . . . . . . .
Oxygen-Air Proportioners
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Oxygen Analyzers . . . . . . . . . . .
Pacemakers, External Invasive
. . .
Pacemakers, External Noninvasive .
Peritoneal Dialysis Units . . . . . . .
Phototherapy Units . . . . . . . . . .
Physical Therapy Ultrasound Units .
Pneumatic Tourniquets . . . . . . . .
Portable Ventilators
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Pressure Transducers
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Pulmonary Resuscitators,
Gas-Powered . . . . . . . . . . . .
Pulmonary Resuscitators, Manual . .
Pulse Oximeters
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Radiant Warmers . . . . . . . . . . .
Radiographic Units, General-Purpose
Radiographic/Fluoroscopic Units,
General-Purpose . . . . . . . . . .
Smoke Evacuators
. . . . . . . . . .
Sphygmomanometers . . . . . . . . .
Suction Regulators . . . . . . . . . .
Temperature Monitors . . . . . . . .
Traction Units . . . . . . . . . . . . .
Transcutaneous O2/CO2 Monitors . .
Ultrasound Scanners . . . . . . . . .
. . . 454-0595
. . . 434-0595
. . . 445-0595
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450-0595
446-0595
421-0595
456-0595
412-0595
441-0595
458-0595
457-0595
408-0595
407-0595
409-0595
437-0595
410-0595
411-0595
464-0595
438-0595
430-0595
431-0595
413-0595
465-0595
414-0595
5200 Butler Pike, Plymouth Meeting, PA 19462-1298, USA
Telephone +1 (610) 825-6000 ● Fax +1 (610) 834-1275
●
E-mail [email protected]
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415-0595
416-0595
432-0595
439-0595
466-0595
467-0595
440-0595
463-0595
468-0595
447-0595
444-0595
417-0595
418-0595
460-0595
455-0595
469-0595
470-0595
443-0595
471-0595
435-0595
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448-0595
422-0595
451-0595
419-0595
472-0595
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473-0595
452-0595
424-0595
459-0595
425-0595
427-0595
453-0595
474-0595
Procedure/Checklist 436-0595
Anesthesia Unit Vaporizers
Used For:
Anesthesia Unit Vaporizers [10-144]
Also Called: By trade names (e.g., Fluotec 5, Vapor 19.1, Tec 6), which are registered trademarks and should
be used only when referring to the specific devices
Commonly Used In: Operating rooms, emergency rooms, delivery rooms, trauma rooms, and any areas
requiring the administration of an inhalation agent (with anesthesia units)
Scope: Applies to the various anesthesia vaporizers used to deliver a known concentration of vaporized liquid
anesthetic
Risk Level: ECRI Recommended, High; Hospital Assessment,
Type
ECRI-Recommended
Interval*
Interval Used
By Hospital
Major
6 months
months
.
hours
Minor
NA
months
.
hours
Time Required
* Additional periodic calibration and preventive maintenance is normally required annually or biannually (see
manufacturer’s recommendation). Only qualified personnel trained and experienced in this function should
perform this additional servicing.
Overview
An anesthesia unit vaporizer is used to vaporize a
liquid anesthetic agent and deliver a controlled
amount to the patient.
According to the American Society for Testing and
Materials (ASTM) standard ASTM F1161-88, anesthetic
agent vaporizers are required to be concentration calibrated (i.e., a calibrated knob controls the output concentration). Older vaporizers, such as the Copper
Kettle and the Vernitrol, do not have a single control
for selecting the concentration of anesthetic vapor.
Where possible, these units should be removed from
service. Contemporary concentration-calibrated vaporizers are of two types: variable bypass and heated
blender.
Conventional (variable-bypass) vaporizers. In a
variable-bypass vaporizer, the total background gas
flow that enters the unit is split into two streams. The
009006
436-0595
A NONPROFIT AGENCY
smaller stream, which acts as the carrier gas, passes
through the vaporizing chamber containing the anesthetic agent and becomes saturated with agent vapor;
the remainder of the gas bypasses this chamber. A
wick may be used in the vaporizing chamber to provide
increased surface area for efficient evaporation of the
drug and saturation of the carrier gas. The saturated
carrier gas leaves the chamber and mixes with the
bypass gas. One adjustment is made to set the desired
concentration. This adjustment simultaneously balances the carrier and bypass flows to produce the blend
required for the set concentration. The mixture exits
the vaporizer and is delivered from the anesthesia
machine as the fresh gas to be inspired by the patient.
Evaporation of the liquid agent contained in the
chamber is driven by heat absorbed from the walls of
the vaporizer; consequently, when evaporation is occurring, the vaporizer and its contents cool. Because
the equilibrium vapor pressure of an agent changes
5200 Butler Pike, Plymouth Meeting, PA 19462-1298, USA
Telephone +1 (610) 825-6000 ● Fax +1 (610) 834-1275
●
E-mail [email protected]
Inspection and Preventive Maintenance System
pass vaporizer. As a result, the variable-bypass design
was abandoned for desflurane, and Ohmeda developed
a new vaporizer, the Tec 6, based on a heated-blender
design. Figure 2 shows a schematic of this vaporizer.
A version of the Tec 6 (also manufactured by Ohmeda) has been adapted for Drager machines and is
compatible with the Drager triple-exclusion interlock
system. As of this writing, neither Drager nor Siemens has developed its own desflurane vaporizer.
Figure 1. Schematic illustrating the basic elements of a
vaiable-bypass vaporizer
with temperature, a temperature-sensitive mechanism is used to automatically adjust the carrier and
bypass flows to compensate for temperature changes.
Figure 1 presents a schematic of a variable-bypass
vaporizer.
Desflurane (heated-blender) vaporizers. Desflurane, a volatile inhalation anesthetic marketed by
Ohmeda Pharmaceutical Products Division under the
trade name Suprane, has characteristics that differ
markedly from those currently in use — enflurane, halothane, and isoflurane; for example, its low solubility
allows rapid induction of and emergence from anesthesia. Thus, by increasing the speed of recovery, desflurane
has the potential to shorten hospital stays (although this
has not yet been consistently demonstrated).
The boiling point of desflurane — 22.9°C at 760 mm
Hg — is just above room temperature; therefore, small
increases in ambient temperature or decreases in atmospheric pressure can cause it to boil. Also, because of
desflurane’s high minimum alveolar concentration, or
MAC (i.e., its low potency), evaporation of sufficient
agent to achieve a given anesthetic effect would require
much more heat absorption from the vaporizer than
occurs with other agents. Furthermore, the change in
vapor pressure of desflurane per change in temperature
is as much as three times that for the other volatile
agents at sea-level atmospheric pressure. These profound effects of temperature and ambient pressure on
the vapor pressure of desflurane make stabilizing the
delivered concentration at a set point extremely difficult
in a passive mechanical system, such as a variable-by-
2
A desflurane vaporizer requires electrical power to
heat the agent to a thermostatically controlled 39°C,
producing a stable, saturated vapor pressure of
1,500 mm Hg. No wick is used, and no carrier gas
enters the sump chamber. Instead, a stream of vapor
under pressure flows out of the sump; this stream
blends with the background gas stream, which originates from the anesthesia machine’s flowmeters, to
achieve the desired concentration.
The background gas stream passes through a fixedflow resistor, producing a back pressure upstream of
this resistor that is proportional to the background gas
flow. The desired desflurane concentration is set on the
dial of the adjustable metering valve in the vapor
stream; this setting produces a predetermined aperture. The pressure in the vapor upstream of the aperture and the back pressure in the background gas
stream are continually sensed by a differential pressure transducer. The transducer controls a pressureregulating valve in the vapor stream between the sump
Figure 2. Schematic illustrating the basic elements of the
Ohmeda Tec 6 vaporizer
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Anesthesia Unit Vaporizers
and the adjustable metering valve. The pressure-regulating valve permits only that flow from the sump
necessary to cause the pressure upstream of the adjustable metering valve to equal the back pressure in
the background gas stream. In this way, the ratio of
the adjustable metering valve’s resistance to the resistance of the fixed-flow resistor determines the ratio of
the flows in each stream, and therefore, the concentration of vapor in the blended output. If the flow from the
anesthesia machine’s flowmeters through the vaporizer is altered, the flow of vapor from the sump is
automatically adjusted so that the pressures at the two
monitored points remain equal, the flow ratio does not
change, and the output concentration continues to
match its setting.
The control circuits and heating elements in the
vaporizer are turned on by the act of connecting the
vaporizer to electrical power. The unit then heats to
and remains at operating temperature as long as it
receives power, whether it is delivering agent or is in
the standby mode. Consequently, it is warm to the
touch while plugged into a live socket.
Citations from Health Devices
Avoiding anesthesia mishaps through pre-use checks,
1982 May; 11:210-3.
Water in halothane vaporizers [Hazard], 1985 Aug;
14:326.
Anesthesia units with a flowmeter-controlled vaporizer [Hazard], 1986 Dec; 15:336.
Do not fill a vaporizer with an inhalation agent
unless you are qualified to do so. Always use a scavenging system or appropriate ventilation when inspecting vaporizers. For personal safety, when
inspecting vaporizers alone, notify other personnel of
your location. Be sure that filler ports are tightly
capped before passing gas through the vaporizer.
Procedure
Before beginning an inspection, carefully read this
procedure and the manufacturer’s instruction and service manuals; be sure that you understand how to operate the equipment and the significance of each control
and indicator. Also determine whether any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer.
Note: This procedure should be done simultaneously
with Anesthesia Units Procedure/Checklist 400,
where leak testing of the vaporizer has been included
with the anesthesia unit.
Each vaporizer should have a separate control
number. Inspection documentation for up to three
vaporizers (on one anesthesia unit) can be included on
one inspection form (record each control number), but
some hospitals may prefer to use a separate form for
each vaporizer.
Be sure that the anesthesia system is level and
secure. Check that all hoses and fittings are tight.
1. Qualitative tests
1.1
Pre-use anesthesia check fails to find faults [Hazard],
1988 Sep; 17:274-6.
Chassis/Housing. Examine the exterior of the
unit for cleanliness and general physical condition. Be sure that housings are intact, that all
assembly hardware is present and tight, and
that there are no signs of spilled liquids or other
serious abuse.
1.2
Desflurane (Suprane): Considerations for introducing the new inhalation anesthetic agent into clinical
practice [Guidance article], 1994 Apr; 23:131-42.
Mount/Fasteners. Check security of mounts or
support mechanisms. Verify that the vaporizer
is firmly mounted on the anesthesia unit.
1.4
AC Plug. If the unit is so equipped, examine the
AC power plug for damage. Attempt to wiggle
the blades to determine that they are secure.
Shake the plug and listen for rattles that could
indicate loose screws. If any damage is suspected, open the plug and inspect it.
1.5
Line Cord. Inspect the cord, if so equipped, for
signs of damage. If damaged, replace the entire
cord, or if the damage is near one end, cut out the
defective portion. Be sure to wire a new power cord
or plug with the same polarity as the old one.
Vaporizer leak with Mapleson breathing circuits [Hazard], 1986 Dec; 15:344-5.
Concentration calibrated vaporizers [Hazard], 1987
Mar-Apr; 16:112-3.
Test apparatus and supplies
Halogenated anesthetics analyzer
Hoses and adapters
Special precautions
As a general precaution, a vaporizer containing an
anesthetic agent should not be tipped. If such tipping
occurs, notify the user and follow the manufacturer’s
recommended procedures for airing or drying the unit.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
3
Inspection and Preventive Maintenance System
1.6
Strain Reliefs. Examine the strain reliefs at
both ends of the line cord, if so equipped. Be sure
that they hold the cord securely.
1.7
Circuit Breaker/Fuse. If the device has a
switch-type circuit breaker, check that it moves
freely. If the device is protected by an external
fuse, check its value and type against that
marked on the chassis, and ensure that a spare
fuse is provided.
1.8
Tubes/Hoses. Check the condition of all tubing
and hoses. Be sure that they are not cracked,
kinked, or dirty.
1.10 Fittings/Connectors. Examine all gas and liquid fittings and connectors for general condition.
Be sure all fittings are tight.
1.13 Controls. Before moving any controls, check
their positions. If any of them appear inordinate
or are left in the on position, consider the possibility of inappropriate clinical use or of incipient
device failure.
Examine all controls for physical condition,
secure mounting, and correct motion. Where a
control should operate against fixed-limit stops,
check for proper alignment, as well as positive
stopping. During the course of the inspection, be
sure to check that each control performs its
proper function. Return all controls to the off
position following the test.
1.16 Fluid Levels. Check all fluid levels. If the fluid
level is zero, we recommend that you have a
qualified user fill the sump with anesthetic
agent to continue the inspection.
1.17 Battery. Inspect the physical condition of the
battery and battery connectors, if so equipped
and readily accessible. Operate the battery-powered functions of the unit for several minutes to
check that the battery has an adequate charge.
Check remaining battery capacity by activating
the battery test function or measuring the output voltage. If it is necessary to replace a battery,
label it with the date.
1.18 Indicators/Displays. During the course of the
inspection, confirm the operation of all indicators and visual displays on the unit, if so
equipped.
1.20 Alarms/Interlocks. Operate the device in such
a way as to activate each audible and visual
alarm, if so equipped. If the device has an alarmsilence feature, check the method of reset (i.e.,
4
manual or automatic) against the manufacturer’s specifications. Check that the vaporizer
interlock allows activation of only one vaporizer
at a time.
1.21 Audible Signals. Operate the device in such a
way as to activate any audible signals. Confirm
appropriate volume, as well as the operation of
a volume control, if so equipped.
1.22 Labeling. Check that all necessary placards, labels, conversion charts, and instruction cards
are present and legible.
1.24 Site Glass, O-Rings, Keyed Filler Mechanism. Examine the physical condition of the site glass,
O-rings, and keyed filler mechanism, if so
equipped.
2. Quantitative tests
2.1
Grounding Resistance. If the unit is electrically
powered, use an ohmmeter, electrical safety analyzer, or multimeter with good resolution of fractional ohms to measure and record the
resistance between the grounding pin of the
power cord and exposed (unpainted and not anodized) metal of the chassis. We recommend a
maximum of 0.5 Ω
2.2
Leakage Current. For electrically powered
units, measure chassis leakage current to the
chassis of the device with the grounding conductor of plug-connected equipment temporarily
opened. Operate the device in all normal modes,
including On, Standby, and Off, and record the
maximum leakage current. Leakage current
should not exceed 300 µA.
2.10 Concentration Check. Data for up to three vaporizers can be recorded as Items 2.10, 2.11, and
2.12. Record the type and control number of the
vaporizer being tested under each item.
2.11 See Item 2.10
2.12 See Item 2.10
Because there are various types of halogenated anesthetic analyzers, follow the manufacturer’s procedure for setup and use of the
analyzer.
Vaporizers should usually be tested with an
oxygen flow of 4 to 5 L/min (nitrous oxide may
affect the readings of some vapor analyzers).
Test the vaporizers at low, medium, and high
concentration settings in the normal clinical use
range (e.g., 0.5%, 1.0%, and 3.0% for halothane).
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Anesthesia Unit Vaporizers
At one concentration setting (e.g., 1.0% for halothane, 10% for desflurane), test the vaporizer
at another flow (e.g., 1 L/min). We recommend
that the concentration be ±0.3% vapor or ±10%
of the measured value, whichever is greater. If
errors in concentration are observed, allow the
vaporizer to operate for a minute or two and
recheck the unit. Some units may require a
short stabilization period.
3. Preventive maintenance
3.1
Clean the exterior.
3.2
Replace the battery, if so equipped (battery
should be replaced at least once annually).
4. Acceptance tests
Conduct major inspection tests for incoming vaporizers and, if a vaporizer is position sensitive, any time
it is demounted from an anesthesia unit.
Before returning to use
Return all controls to the off position, level and
secure the unit, and tighten all fittings and tubing.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
5
Procedure Checklist 461-0595
Anesthesia Unit Ventilators
Used For:
Anesthesia Unit Ventilators [10-145]
Commonly Used In: Delivery rooms and operating rooms
Scope: Applies to ventilators used to deliver inhalation anesthetic agents during surgical procedures that
require general anesthesia
Risk Level: ECRI Recommended, High; Hospital Assessment,
Type
ECRI-Recommended
Interval
Interval Used
By Hospital
Major
6 months*
months
.
hours
Minor
NA
months
.
hours
Time Required
* Inspection and preventive maintenance intervals should be scheduled according to the manufacturer’s
recommendations. However, units should have a major inspection at least every six months. Pre-use checks
should be performed before each case by the anesthetist who will be operating the equipment.
Overview
Patients undergoing surgery under general anesthesia
are routinely paralyzed with muscle relaxants to stabilize the surgical field. Consequently, they are unable
to breathe on their own and must be mechanically
ventilated either manually by the anesthetist, who
squeezes a reservoir bag in the breathing circuit, or
automatically by an anesthesia ventilator. A switch
valve allows the choice of the method by which ventilation is to be supported. The anesthesia ventilator is
typically turned on and off independently of the switching between manual and automatic ventilation.
Anesthesia ventilators use positive pressure to inflate a patient’s lungs and deliver a prescribed mixture
of gases and vapors to them. This mixture is produced
by the anesthesia machine. The ventilator can be built
into the anesthesia machine or can be a stand-alone
unit connected to the machine by gas tubing and,
perhaps, sensor cables. Some anesthesia ventilators
have built-in displays and alarms; others rely on the
sensors, displays, and alarms of the anesthesia machine to monitor their performance.
238369
461-0595
A NONPROFIT AGENCY
In general, an anesthesia ventilator is less sophisticated than a critical care ventilator, having only a
control mode of operation, with time cycling. (However,
there is at least one ICU-type ventilator that can be
used to administer inhalation anesthetics.) A pressure
limit prevents exposure of the lungs to excessive pressure. Several other breathing waveshape parameters
(e.g., inspiratory:expiratory [I:E] ratio, tidal volume,
minute volume, flow) are settable by the operator and
controlled by the ventilator. Ventilators designed
solely for anesthetic administration typically do not
have compressors.
During extended procedures and procedures involving open breathing circuit configurations, a humidifier
may be included in the breathing circuit. Otherwise, a
circle system with an absorber, along with one-way
inspiratory and expiratory valves, is used, typically
without a humidifier. The ventilator’s pressure-relief
and limit valve(s) should be connected to a waste gas
scavenging system.
Citations from Health Devices
Anesthesia systems [Evaluation], 1988 Jan; 17:3.
5200 Butler Pike, Plymouth Meeting, PA 19462-1298, USA
Telephone +1 (610) 825-6000 ● Fax +1 (610) 834-1275
●
E-mail [email protected]
Inspection and Preventive Maintenance System
Who should service anesthesia equipment [User Experience NetworkTM], 1988 Feb; 17:70.
use by outside vendors can be produced to ensure that
those items agreed upon are performed by the vendor.
Barotrauma from anesthesia ventilators [Hazard],
1988 Nov; 17:354.
The following framework should be supplemented
by the manufacturer’s recommended preventive maintenance procedures for mechanical ventilators.
Damage to elastic components from Loctite [Hazard],
1989 Jul-Aug; 18:288.
Risk of barotrauma and/or lack of ventilation with
ventilatorless anesthesia machines [Hazard], 1994
Jan-Feb; 23:54.
1. Qualitative tests
1.1
Chassis/Housing. Examine the exterior of the
unit for cleanliness and general physical condition.
Be sure that plastic housings are intact, that all
hardware is present and tight, and that there are
no signs of spilled liquids or other serious abuse.
1.2
Mount/Fasteners. Check that ventilators
mounted in anesthesia machines are properly
installed. If the device is mounted on a stand or
cart, examine the condition of the mount. If it is
attached to a wall or rests on a shelf, check the
security of this attachment. Check the mounting
security of all components.
1.3
Casters/Brakes. If the device moves on casters,
check their condition. Verify that they turn and
swivel, as appropriate, and look for accumulations of lint and thread around the casters.
Check the operation of brakes and swivel locks,
if the unit is so equipped.
1.4
AC Plug. Examine the AC power plug for damage, if so equipped. Attempt to wiggle the blades
to check that they are secure. Shake the plug and
listen for rattles that could indicate loose screws.
If any damage is suspected, open the plug and
inspect it.
1.5
Line Cord. Inspect the cord for signs of damage,
if so equipped. If damaged, replace the entire
cord or, if the damage is near one end, cut out the
defective portion. Be sure to wire a new power
cord or plug with the correct polarity. Also check
line cords of battery chargers.
1.6
Strain Reliefs. Examine the strain reliefs at
both ends of the line cord, if so equipped. Be sure
that they hold the cord securely.
1.7
Circuit Breaker/Fuse. If the device has a switchtype circuit breaker, check that it moves freely. If
the device is protected by an external fuse, check
its value and type against that marked on the
chassis, and ensure that a spare is provided.
1.8
Tubes/Hoses. Check the condition of all tubing
and hoses. Be sure that they are not cracked,
kinked, or dirty. Check that they are connected
to the correct locations.
Test apparatus and supplies
Lung simulator with adjustable compliance or ventilator tester
Pressure gauge or meter with 2 cm H2O resolution
from -20 to +120 cm H2O
Various breathing circuit adapters
Leakage current meter or electrical safety analyzer
Ground resistance ohmmeter
Additional items as required for specific manufacturers’ procedures
Procedure
Before beginning an inspection, carefully read this
procedure and the manufacturer’s instruction and
service manuals; be sure that you understand how to
operate the equipment, the significance of each control
and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive
maintenance procedures or frequencies are recommended by the manufacturer.
Manufacturers’ recommended procedures for inspection and preventive maintenance of mechanical
anesthesia ventilators vary in both methods and required accuracy. In addition, ventilator controls can
vary greatly among manufacturers and models. This
procedure provides the basic framework for complete
ventilator inspection and preventive maintenance.
Manufacturers’ recommended procedures should be
added where appropriate. References to specific pages
of the manufacturer’s manual should be added to the
checklist. (The checklist includes blank spaces for the
insertion of these reference numbers.)
IPM Task ManagerTM, the software component of the
Inspection and Preventive Maintenance System, enables easy production of customized procedures and
checklists for specific ventilator models and clinical
needs. Items performed by outside vendors can be
excluded from the checklist; a separate checklist for
2
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Anesthesia Unit Ventilators
1.9
Cables. Inspect any cables (e.g., for sensors) and
their strain reliefs for general condition. Carefully examine cables to detect breaks in the insulation and to ensure that they are securely
gripped in the connectors at each end, which will
prevent rotation or other strain. Where appropriate, verify that there are no intermittent
faults by flexing cables near each end and looking for erratic operation or by using an ohmmeter.
1.10 Fittings/Connectors. Examine all gas fittings
and connectors for general condition. Gas fittings should be tight and should not leak. Verify
that keyed connectors (e.g., pin-indexed gas connectors) are used where appropriate, that all
pins are in place and secure, and that keying is
correct. Connectors to hospital central piped
medical gas systems should have the appropriate DISS or quick-connect fitting to eliminate the
need for adapters.
1.12 Filters. Check the condition of gas filters, if included in the unit. Check for corrosion residue
indicative of liquid, gaseous, or solid particle
contaminants in the gas supply; if found, notify
appropriate personnel. Clean or replace if appropriate, and indicate this on Lines 3.1 and 3.4 of
the inspection form.
1.13 Controls/Switches. Before changing any controls or alarm limits, check their positions. If any
settings appear inordinate (e.g., alarm limits at
the ends of their range), consider the possibility
of inappropriate clinical use or of incipient device
failure. Record the settings of those controls that
should be returned to their original positions
following the inspection.
Examine all controls and switches for physical
condition, secure mounting, and correct motion.
Check that control knobs have not slipped on
their shafts. Where a control should operate
against fixed-limit stops, check for proper alignment, as well as positive stopping. Check membrane switches for damage (e.g., from
fingernails, pens). During the inspection, be sure
to check that each control and switch performs
its proper function.
1.17 Battery/Charger. Inspect the physical condition
of batteries and battery connectors, if so equipped
and if readily accessible. Check operation of
battery-operated power-loss alarms, if so
equipped. Operate the unit on battery power for
several minutes to check that the battery is
charged and can hold a charge. (The inspection
can be carried out on battery power to help
confirm adequate battery capacity.) Check battery condition by activating the battery test function or measuring the output voltage; for
lead-acid batteries, measure the specific gravity
and check the fluid level. Check the condition of
the battery charger and, to the extent possible,
confirm that it does, in fact, charge the battery.
Be sure that the battery is recharged or charging
when the inspection is complete. When it is necessary to replace a battery, label it with the date.
1.18 Indicators/Displays. During the course of the
inspection, confirm the operation of all lights,
indicators, meters, gauges, and visual displays
on the unit and charger (if so equipped). Be sure
that all segments of a digital display function.
Record the reading of an hour meter, if present.
1.20 Alarms/Interlocks. Induce alarm conditions to activate audible and visual alarms. Check that any
associated interlocks function. If the unit has an
alarm-silence feature, check the method of reset
(i.e., manual, automatic) against the manufacturer’s specifications. It may not be possible to
check out all alarms at this time since some may
require special conditions that must be established
according to the manufacturer’s recommendations; include these in Item 2.4. Verify that any
remote alarm indicator (e.g., within the mainframe anesthesia unit) functions properly.
1.22 Labeling. Check that all necessary placards, labels, and instruction cards are present and legible.
1.23 Accessories. Confirm the presence and condition
of accessories. Check the condition of reusable
Bain circuit and adapters, if available.
1.24 Bellows. Check the physical condition and
proper operation of the bellows.
2. Quantitative tests
2.1
1.15 Fan. Check physical condition and proper operation, if so equipped. Clean and lubricate if
required, according to the manufacturer’s instructions, and note this on Lines 3.1 and 3.2 of
the form.
Grounding Resistance. Using an ohmmeter, electrical safety analyzer, or multimeter with good
resolution of fractional ohms, measure and record
the resistance between the grounding pin of the
power cord and exposed (unpainted and not anodized) metal on the chassis of the ventilator or of
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
3
Inspection and Preventive Maintenance System
the system in which the ventilator is mounted.
We recommend a maximum of 0.5 Ω. If the
ventilator is a component within an anesthesia
unit, grounding and leakage current measurements can be referenced to that unit.
2.2
Leakage Current. Measure chassis leakage current to ground with the grounding conductor of
plug-connected equipment temporarily opened.
Operate the device in all normal modes, including on, standby, and off, and record the maximum leakage current.
Volume (e.g., tidal volume, minute volume,
apnea)
Fraction of inspired oxygen (FIO2; see Oxygen
Analyzers Procedure/Checklist 417)
Alarm settings (e.g., high PIP, low MAP, low
pressure, low FIO2) should be inspected for
proper and accurate activation.
2.5
Pneumatic lines (including air filters). Verify
that appropriate gas-specific connectors are
used. Check gas filters, if so equipped and
accessible.
Measure chassis leakage current with all accessories normally powered from the same line
cord connected and turned on and off. This includes other equipment that is plugged into the
primary device’s accessory receptacles, as well as
equipment plugged into a multiple-outlet strip
(“Waber strip”) so that all are grounded through
a single line or extension cord.
Gas cylinders (and gauges and regulators, if so
equipped). Verify that these are present, securely mounted, and in good condition and
that there is an adequate gas supply. Verify
that one and only one washer is used to seal
the tank to its yoke. Verify that all index pins
are present and protruding to the proper
length to engage the hole in the tank valve
stem and in the correct positions for the gas to
be supplied through the yoke.
Chassis leakage current to ground should not
exceed 300 µA.
2.3
2.4
Modes and Settings. Anesthesia ventilators are
usually equipped only with a control mode. However, specialized units may have additional
modes such as assist/control and pressure support. Adjustable positive end-expiratory pressure (PEEP) may also be available. The function
of these modes should be inspected and verified
for proper operation. Check the operation and
accuracy of ventilation controls, which may include tidal volume, breath rate, inspiratory time,
expiratory time, I:E ratio, pressure limit, or flow.
Typically, these tests are performed by attaching
the ventilator to a lung simulator or ventilator
tester and comparing measured values to settings on the ventilator. The manufacturer should
recommend the appropriate ventilator settings
(e.g., tidal volume, rate, inspiratory time) to verify proper operation and accuracy (generally
within 10%).
Monitors and Alarms. The following breathing
circuit parameters may be monitored by the ventilator or by the system in which the ventilator
is mounted. They should be inspected for accuracy (generally within 10%) according to the
manufacturer’s specifications:
2.6
Patient Circuit.
Breathing circuit (including filters). Verify that
these components are compatible with the ventilator according to the manufacturer’s recommendations (see Health Devices 1988 Apr;
17:109). Check for leaks, the absence of obstructions, and proper flow direction in the breathing
circuit, ensuring the proper assembly and function of fittings, adapters, the CO2 absorber, inspiratory and expiratory valves and PEEP
valves, the APL valve, the scavenger, and other
components. With the ventilator connected to
the anesthesia system, check for leaks in the
entire system, including the breathing circuit.
This does not have to be duplicated if done as
part of the Anesthesia Units procedure (see
Procedure/Checklist 400).
Humidifiers. See Heated Humidifiers Procedure/Checklist 431.
Inspiratory time
Pressure-Relief Mechanism. Check the proper
operation of the pressure-relief mechanism by
occluding the breathing circuit and measuring
the resulting peak pressure on the pressure
gauge. Verify that pressure is vented in the
breathing circuit.
Airway pressure (e.g., PIP, PEEP, MAP, apnea)
Absorber. See Anesthesia
dure/Checklist 400.
Breathing rate
4
Gas Supply.
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©1995 ECRI. All Rights Reserved.
Units
Proce-
Anesthesia Unit Ventilators
3. Preventive maintenance
Before returning to use
3.1
Clean the exterior and interior, if needed.
3.3
Calibrate according to manufacturer’s instructions.
3.4
Replace components according to the manufacturer’s instructions.
Ensure that all controls are set properly. Set alarms
loud enough to alert personnel in the area in which the
device will be used. Other controls should be in their
normal pre-use positions.
4. Acceptance tests
Conduct major inspection tests for this procedure
and the appropriate tests in the General Devices Procedure/Checklist 438.
Attach a Caution tag in a prominent position so that
the user will be aware that control settings may have
been changed.
Recharge battery-powered devices, or equip them
with fresh batteries, if needed.
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©1995 ECRI. All Rights Reserved.
5
Procedure/Checklist 400-0595
Anesthesia Units
Used For:
Anesthesia Units [10-134]
Also Called: Anesthesia machines, anesthesia workstations
Commonly Used In: Operating rooms, emergency departments, trauma rooms, delivery rooms, any areas
where anesthetic agents are used
Scope: Applies to anesthesia units; includes leak testing of vaporizers and should be used in conjunction with
Anesthesia Unit Vaporizers Procedure/Checklist 436 (in the very rare case where an anesthesia unit may still
use flammable anesthetic agents, refer to Conductive Furniture and Floors Procedure/Form 441); does not
apply to oxygen monitors with an alarm, spirometers, other monitors, or ventilators that might be part of the
breathing system (see Anesthesia Unit Ventilators Procedure/Checklist 461)
Risk Level: ECRI Recommended, High; Hospital Assessment,
Type
ECRI-Recommended
Interval
Major
6 months
months
.
hours
Minor
NA
months
.
hours
Overview
Most surgical procedures are performed while the patient is under general anesthesia. Usually, the patient
is anesthetized by a narcotic or barbiturate injection
followed by administration of an inspired gas mixture
of oxygen, nitrous oxide, and the vapor of a volatile
liquid anesthetic, typically a halogenated hydrocarbon. The anesthesia unit administers this mixture of
anesthetic gases and life-sustaining oxygen, varying
the proportions to control the patient’s level of consciousness. If respiratory assist is necessary (e.g., in
cases of muscular blockade), a ventilator may be connected to the patient breathing system to force the gas
mixture into the patient’s lungs.
Improperly modified or inadequately maintained
anesthesia units have injured and killed patients
and hospital personnel. Gas leaks can adversely
affect the accuracy of gas delivery to the patient, as
well as add anesthetic agents to the OR atmosphere.
Trace levels of anesthetics have been implicated as
009005
400-0595
A NONPROFIT AGENCY
Interval Used
By Hospital
Time Required
a health hazard to chronically exposed OR personnel
and unborn children. Inadvertent switching of gas
supplies, failure of an alarm to respond to an excessively low oxygen pressure, and misconnected or improperly calibrated flowmeters have also caused
anesthesia-related accidents.
Because mishandling and mistakes can have severe
consequences, life-support devices such as anesthesia
units should be operated and inspected only by qualified personnel who have a thorough knowledge of the
units and their functions. If you are unsure of any
aspect of the procedure, consult the manufacturer before inspecting an anesthesia unit.
The anesthesia unit consists of four systems: the gas
supply system, the gas control system, the vaporizers,
and the breathing system.
Gas supply. This system delivers a variety of gases
to the patient. Cylinders containing oxygen and other
gases at high pressure (see Table 1) are connected to
the high-pressure system of the anesthesia unit by
5200 Butler Pike, Plymouth Meeting, PA 19462-1298, USA
Telephone +1 (610) 825-6000 ● Fax +1 (610) 834-1275
●
E-mail [email protected]
Inspection and Preventive Maintenance System
TABLE 1. Gases Used in Anesthesia Machines
Gas
Chemical
Formula
Color Code:
U.S.
Color Code:
International
Service Pressure,
psi 21°C, Full Cylinder
Oxygen
Carbon Dioxide
Nitrous Oxide
Helium
Air
O2
CO2
N2O
He
Green
Gray
Blue
Brown
Yellow
White
Gray
Blue
Brown
White and Black
1,800-2,400*
838
745
1,600-2,000*
1,800
* Depends on cylinder size.
yoke fittings that comply with the Compressed Gas
Association (CGA) pin-index safety system (see Figure
1). Unique placements of pins and mating holes on the
pin-index fittings prevent connection of a gas cylinder
to the wrong inlet. Inside the unit, each high-pressure
gas flows through a filter, a check valve (for one-way
flow), and a regulator that reduces the pressure to
approximately 45 psi.
Because oxygen and nitrous oxide are used in relatively large quantities, they are usually drawn from
the hospital’s central gas supplies, which are more
convenient and economical than compressed-gas cylinders. However, cylinders of these gases are also
normally attached to the anesthesia unit as a reserve
source if the central supply fails or if central supply
outlets are not available.
Centrally supplied gases are delivered directly to the
intermediate-pressure gas control system at approximately 50 psi through low-pressure hoses and connectors. These connectors may not comply with a universal
standard safety system, but each is designed to prevent
mismating the gas supply and the machine inlet.
Some units may provide an oxygen power outlet to
drive auxiliary devices (e.g., a ventilator).
Gas control. This system regulates gas flow rates so
that the gases can be mixed and delivered under accurate, constantly metered control. The operator must
be able to adjust the ratios or make rapid gross changes
in flow rates without inducing system interactions that
cause temporary delivery of undesirable mixtures.
The flow of each gas is controlled by a valve and
indicated by a glass-tube flowmeter. After gases pass
the control valve and enter the low-pressure system,
they can be administered to the patient.
Gas
Index Pins
CGA Connector
Number
Oxygen
Nitrous Oxide
O2 - CO2 (CO2<7%)
O2 - CO2 (CO2>7%)
O2 - HE (He > 80%)
O2 - HE (He < 80%)
Air
2-5
3-5
2-6
1-6
4-6
2-4
1-5
870
910
880
940
930
890
950
Figure 1. Pin-index safety system
2
A fail-safe provision in many anesthesia units protects the patient against a fall in pressure of life-sustaining oxygen. If the oxygen pressure drops below
about 25 to 30 psi, some units shut off the flow of all
other gases, while others reduce all gas flow rates in
proportion to the drop in oxygen pressure. Newer
anesthesia machines have additional safety systems
that provide a minimum percent of oxygen (around
25%) and/or deliver a minimum flow of oxygen (usually
150 to 250 mL/min) (see Item 2.11).
Vaporizers. These devices add the vapor of a volatile
liquid anesthetic (e.g., halothane, isoflurane, enflurane,
sevoflurane, desflurane) to the gas mixture, when desired, and aid in controlling the vapor concentration.
According to the American Society for Testing and
Materials (ASTM) standard ASTM F1161-88, anesthetic agent vaporizers are required to be concentration calibrated (i.e., a calibrated knob controls the
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©1995 ECRI. All Rights Reserved.
Anesthesia Units
output concentration). Older vaporizers, such as the
Copper Kettle and the Vernitrol, do not have a single
control for selecting the concentration of anesthetic
vapor. Where possible, these units should be removed
from service. Contemporary concentration-calibrated
vaporizers are of two types: variable bypass and heated
blender.
The variable-bypass (conventional) vaporizer is
used for most volatile agents (e.g., halothane, isoflurane, enflurane, sevoflurane). The total background
gas flow that enters the unit is split into two streams.
The smaller stream, which acts as the carrier gas,
passes through the vaporizing chamber containing the
anesthetic agent and becomes saturated with agent
vapor; the remainder of the gas bypasses this chamber.
A wick may be used in the vaporizing chamber to
provide increased surface area for efficient evaporation of the drug and saturation of the carrier gas. The
saturated carrier gas leaves the chamber and mixes
with the bypass gas. One adjustment is made to set the
desired concentration. This adjustment simultaneously balances the carrier and bypass flows to produce
the blend required for the set concentration. The mixture exits the vaporizer and is delivered from the
anesthesia machine as the fresh gas to be inspired by
the patient.
A heated-blender vaporizer is used only for desflurane. It requires electrical power to heat the agent
to a thermostatically controlled 39°C, producing a
stable, saturated vapor pressure of 1,500 mm Hg. No
wick is used, and no carrier gas enters the sump
chamber. Instead, a stream of vapor under pressure
flows out of the sump; this stream blends with the
background gas stream, which originates from the
anesthesia machine’s flowmeters, to achieve the desired concentration.
(Desflurane, a volatile inhalation anesthetic marketed by Ohmeda Pharmaceutical Products Division
under the trade name Suprane, and sevoflurane,
marketed by Abbott under the trade name Ultane,
have characteristics that differ markedly from those
currently in use — enflurane, halothane, and isoflurane. For example, their low solubilities allow rapid
induction of and emergence from anesthesia. Thus,
by increasing the speed of recovery, desflurane and
sevoflurane have the potential to shorten hospital
stays, although this has not yet been consistently
demonstrated.)
Breathing system. Although it is designed primarily for sustained, efficient gas delivery to the patient,
the breathing system may also remove carbon dioxide
and provide mechanical or manual ventilation of a
patient who cannot breathe spontaneously, as well as
positive end-expiratory pressure (PEEP), if required.
The breathing system typically includes a scavenging
system to remove waste gases.
Two types of breathing systems are used to deliver
the anesthetic mixture from the unit to the patient,
although they may assume a variety of configurations.
The T-piece or open system may be a nonrebreathing system consisting of a reservoir bag and a gas-delivery hose connected through a nonrebreathing
(one-way) valve to the face mask or endotracheal tube.
The patient breathes the anesthetic mixture directly
from the machine, and exhaled gas is vented out of the
system. T-piece systems that do not include the nonrebreathing valve may allow partial rebreathing, depending on the inflow of fresh gas.
The circle or closed system is a continuous loop in
which check valves allow gas to flow in only one direction. The patient inhales from and exhales into the
system. Fresh gases from the anesthesia machine
enter at one point, mix with previously exhaled gases,
and pass to the patient, who inhales the mixture.
Newly exhaled gases are channeled to a carbon dioxide
absorber, which removes almost all the carbon dioxide
produced by body metabolism and routes the scrubbed
gases back toward the patient. En route, the scrubbed
gases become mixed with fresh machine gases.
A scavenging system should be included to remove
waste gas from the vent port of a T-piece breathing
system or from the adjustable pressure-limiting (APL)
valve and relief valve of a ventilator of a circle system
to reduce the quantity of gas that escapes into the
operating room. Such a scavenging system is necessary because trace levels of anesthetics are believed to
cause an increased incidence of spontaneous abortion,
congenital anomalies in offspring, and neoplastic disease and may affect the mental and physical abilities
of exposed personnel. The breathing system should be
checked before each use for leaking gases. It is also
recommended that the concentration of waste anesthetic gas in the operating room be surveyed quarterly.
The scavenging system must include pressure-relief
mechanisms so that abnormal pressures cannot develop in the scavenging system and interfere with
operation of the breathing system.
Anesthesia units either come with physiological
monitors integrated into the unit or provide shelving
to support such monitors. Most also provide mounting
for a suction regulator and canister and other accessories, along with storage for drugs, supplies, and related
paraphernalia.
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Inspection and Preventive Maintenance System
Citations from Health Devices
Anesthesia units with a flowmeter-controlled vaporizer [Hazard], 1986 Dec; 15:336-7.
Vaporizer leak with Mapleson breathing systems
[Hazard], 1986 Dec; 15:344-5.
have a minimum pressure of 745 psi for nitrous
oxide and 1,000 psi for oxygen
Nondisposable corrugated breathing hose (disposable tubing may not provide reliable connections)
Test lung (reservoir bag with 3 or 5 L capacity)
Sphygmomanometer bulb with tubing and adapter
Concentration calibrated vaporizers [Hazard], 1987
Mar-Apr; 16:112-3.
Pre-use testing prevents “helpful” reconstruction of
anesthesia components [Hazard], 1987 May;
16:178-9.
Anesthesia systems [Evaluation], 1988 Jan; 17:3-34.
Who should service anesthesia equipment [User Experience NetworkTM], 1988 Feb; 17:70-1.
Pre-use anesthesia check fails to find faults [Hazard],
1988 Sep; 17:274-6. (Contains pre-use checklist for
anesthesia units.)
Anesthesia systems [Evaluation Update], 1988 Dec;
17:366-7.
Anesthesia units and breathing systems [Standard],
1989 Oct; 18:363.
Monitoring and anesthesia systems: integration and a
new option, 1991 Mar-Apr; 20:131-2.
Use of inadequate (old) anesthesia scavenger interfaces [Hazard], 1993 Dec; 22:592.
Anesthesia systems [Evaluation]. To be published in
1996.
Test apparatus and supplies
Pressure gauge or meter, -10 to +80 cm H2O (accuracy ±5 cm H2O at 30 cm H2O)
Flowmeters with ranges of approximately 0.1 to 1.0
L/min and 1 to 10 L/min, ±2% accuracy, calibrated
separately for each of the gases used with the anesthesia machine, and one flowmeter for 10 to 100
L/min (±10% of reading)
Stopwatch or watch with a second hand
Hoses and adapters for connecting pressure gauges
or meters and flowmeters to equipment being inspected
Cylinder of each type of gas used with the unit
being inspected; each cylinder on a unit that is
ready for use should be more than half full if the
gas is normally stored in gaseous form (e.g., oxygen) and should contain some liquid if the gas is
normally liquefied for storage; cylinders should
4
Leak-detecting solution
Conductive lubricant for conductive casters (e.g.,
Dow No. 41, graphited oil)
Trichloroethylene cleaning solvent or solvent recommended by the manufacturer (be sure to review
the manufacturer’s Material Safety Data Sheet and
see the special precautions below)
Lubricant as specified by manufacturer
Special precautions
ECRI is aware of a number of incidents in which
improperly serviced ventilation or anesthesia equipment was implicated in patient injury or death. Do not
perform any procedures, adjustments, repairs, or
modifications unless you thoroughly understand the
device and have verified the appropriateness of the
intended actions. Resolve any questions or uncertainties with the manufacturer, the anesthetist, or ECRI
before placing a unit into use.
To avoid the adverse effects of exposure to anesthetic gases, all testing should be done with an operating scavenging system in place or an alternative means
to vent excess gases from the vicinity of inspecting
personnel. If a flammable anesthetic is used, be sure
all traces of the gas are cleared away before performing
any electrical tests. Check that all valves, including
the gas cylinder stem valves, are turned off at the
beginning of the inspection. Turn all valves off again
when the inspection is complete.
When testing cyclopropane flowmeters, observe
noted procedures to avoid a buildup of explosive levels
of cyclopropane.
Trichloroethylene is a common solvent particularly
recommended for cleaning oxygen fittings because it
does not leave a residue that is flammable in high-concentration oxygen. However, this solvent reacts with
the soda lime used in carbon dioxide absorbers to form
several poisonous gases, including phosgene. Although concentrations may not be lethal, the presence
of these gases to any degree is highly undesirable.
To prevent the generation of these gases, make sure
that equipment recently cleaned with trichloroethylene is completely dry before using. When clean-
Inspection and Preventive Maintenance System
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Anesthesia Units
ing parts of the anesthesia unit with this solvent, first
disconnect the line to the carbon dioxide absorber.
After cleaning, allow time for the solvent to evaporate.
When the parts appear dry, take the added precaution
of briefly flushing them with a high oxygen flow rate.
1.6
Strain Reliefs. Examine the strain reliefs at
both ends of the line cord. Be sure that they hold
the cord securely.
1.7
Circuit Breaker/Fuse. If the device has a
switch-type circuit breaker, check that it moves
freely. If the device is protected by an external
fuse, check its value and type against that
marked on the chassis, and ensure that a spare
is provided.
1.8
Tubes/Hoses. Check the condition of all tubing
and hoses. Be sure that they are not cracked,
kinked, or dirty.
1.9
Cables. Inspect the cables (e.g., sensor, electrode) and their strain reliefs for general condition. Examine cables carefully to detect breaks
in the insulation and to ensure that they are
gripped securely in the connectors of each end to
prevent rotation or other strain.
Procedure
Before beginning an inspection, carefully read this
procedure and the manufacturer’s instruction and
service manuals; be sure that you understand how to
operate the equipment, the significance of each control
and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive
maintenance procedures or frequencies are recommended by the manufacturer.
1. Qualitative tests
1.1
Chassis/Housing. Examine the exterior of the
unit for cleanliness and general physical condition. Be sure that plastic housings are intact,
that all assembly hardware is present and tight,
and that there are no signs of spilled liquids or
other serious abuse.
1.2
Mount. Check any shelves, brackets, or supporting structures. Check the security of the
attachments.
1.3
Casters/Brakes. If the device moves on casters,
check their condition. Look for accumulations of
lint and thread around the casters, and be sure
that they turn and swivel as appropriate. Check
the operation of brakes and swivel locks, if the
unit is so equipped. Check that gas hoses do not
lie on the floor or loop near the casters.
1.4
AC Plug/Receptacles. Examine the AC power
plug for damage. Attempt to wiggle the blades
to determine that they are secure. Shake the
plug and listen for rattles that could indicate
loose screws. If any damage is suspected, open
the plug and inspect it.
If the device has electrical receptacles for accessories, insert an AC plug into each and check
that it is held firmly. If accessories are plugged
and unplugged often, consider a full inspection
of the receptacle.
1.5
Line Cord. Inspect the cord for signs of damage.
If damaged, replace the entire cord or, if the
damage is near one end, cut out the defective
portion. Be sure to wire a new power cord or plug
with the correct polarity. Also check line cords of
battery chargers.
1.10 Fittings/Connectors. Examine all gas and liquid fittings and connectors, as well as all electrical cable connectors and sockets, for general
condition. Electrical contact pins or surfaces
should be straight, clean, and bright. Check that
pins used with the pin-index safety system comply (location and length of protrusion) and are
intact. Check the yoke clamping screw and
make sure empty yokes have plugs. Check that
appropriate keyed or indexed fittings are being
used with corresponding gases.
1.12 Filters. Check the condition of all compressedgas filters. Clean or replace as needed, and indicate this on Line 3.1 or 3.4 of the inspection form.
1.13 Controls/Switches. Before moving any controls
and alarm limits, check their positions. If any of
them appear inordinate (e.g., a pressure alarm
control at maximum, alarm limits at the ends of
their range), consider the possibility of inappropriate clinical use or of incipient device failure.
Record the settings of those controls that should
be returned to their original positions following
the inspection.
Examine all controls and switches for physical
condition, secure mounting, and correct motion.
Where a control should operate against fixedlimit stops, check for proper alignment, as well
as positive stopping. During the course of the
inspection, be sure to check that each control and
switch performs its proper function.
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5
Inspection and Preventive Maintenance System
Check that the concentration dial on each
vaporizer moves freely and that only one vaporizer can be on at a time. Observe the float motion
as its flow control valve is turned on. The valve
should turn smoothly with only slight drag.
Each valve should have a definite shutoff position at which the float should be motionless at
its zero level. Check for free play in the control
valve by pushing, pulling, and gently rocking the
stem from side to side without rotation. The stem
should feel firm, and the flowmeter float should
not move. The control valve knob should require
turning through at least 90° to change the flow
rate from 10% to 100% of full scale. (Note: All
recent anesthesia units should now have different sized and shaped knobs for oxygen and nitrous oxide to aid in differentiating between the
two controls.)
1.17 Battery/Charger. Inspect the physical condition of batteries and battery connectors, if readily accessible. Check the battery-operated
power-loss alarms on AC and pneumatic devices,
if so equipped. Operate the unit on battery power
for several minutes to check that the battery has
an adequate charge. Check remaining battery
capacity by activating battery test function or
measuring the output voltage. If appropriate,
check the condition of the battery charger and,
to the extent possible, confirm that it does, in
fact, charge the battery. When it is necessary to
replace a battery, label it with the date.
1.18 Indicators/Displays. During the course of the
inspection, confirm the operation of all lights,
indicators, meters, gauges, and visual displays
on the unit and charger, if so equipped. Be sure
that all segments of a digital display function.
1.19 Directional Valves. Check that directional
valves are free from cracks and chips and fit
smoothly against the valve seats. Check for free
movement by shaking or lightly squeezing the
hose connecting the two valves. The valves
should flutter up and down and should not stick
to their seats.
Check for the possibility of reverse flow
through directional valves by removing the
breathing hoses from the absorber and attaching a thin disposable reservoir bag to the exhalation port. Attach a piece of hose to the bag
mount, set the control for manual mode, close
the APL valve, and occlude the inspiratory port
with the palm of your hand. Then, connect a test
lung to the hose and generate about 5 cm H2O
6
of pressure on the pressure gauge. Watch for any
inflation of the flattened bag as a sign of expiratory valve leakage.
Reconnect the bag to the bag mount and the
hose to the inhalation port. With your hand occluding the expiratory port, use a test lung to
again generate about 5 cm H2O of pressure and
check for inspiratory valve leakage by watching
for any inflation of the bag.
1.20 Alarms/Interlocks. Operate the device in such a
way as to activate each audible and visual alarm.
Check that any associated interlocks function
(particularly the vaporizer interlocks, which
should allow activation of only one vaporizer at a
time). If the device has an alarm-silence feature,
check the method of reset (i.e., manual or automatic) against the manufacturer’s specifications.
1.21 Audible Signals. Operate the device in such a
way as to activate all audible signals. Confirm
appropriate volume, as well as the operation of
a volume control, if so equipped. Check that the
audible signals are appropriate for the test conditions used.
1.22 Labeling. Check that all necessary placards, labels, conversion charts, and instruction cards
are present and legible. Check for proper color
coding for corresponding parts (e.g., green for
oxygen, blue for nitrous oxide).
1.23 Accessories. Verify accuracy and function of any
accessories (e.g., spirometer, sphygmomanometer gauge). (Inspect ventilators, vaporizers, and
oxygen monitors separately using the appropriate procedures, and record on separate forms.)
1.24 Fail-Safe Oxygen Valves and Alarms. Close all
control valves. Open all cylinder stem valves
and external gas source valves. Connect gas
scavenging or other evacuation system to common gas outlet. Turn on the main gas control,
and open the flow control valves until the flowmeter for each gas reads midscale. Then disconnect or turn off all oxygen sources. The flow of
other gases should fall or stop as the oxygen flow
decreases to half its previous level. All gas flow
should cease when the oxygen flow reaches zero.
(Cyclopropane flow rate normally falls more
slowly than the others.)
In addition to the automatic shutoff or reduction of gas flow, audible or visual alarms signifying low oxygen pressure should have been
activated, if the unit is so equipped. Silence the
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Anesthesia Units
Measure chassis leakage current with all accessories normally powered from the same line
cord connected and turned on and off. This includes other equipment that is plugged into the
primary device’s accessory receptacles, as well as
equipment plugged into a multiple-outlet strip
(“Waber strip”) so that all are grounded through
a single line or extension cord.
alarm by raising the oxygen pressure above the
preset alarm limit. If the unit has an alarm that
does not respond, check for exhausted batteries
or other source of the malfunction.
1.25 Common Outlet Back-Pressure Check Valve.
Most anesthesia units manufactured after 1968
with mounted bubble-through vaporizers have a
check valve in the gas delivery system to prevent
pressures at the outlet (e.g., produced by a ventilator) from being transmitted to other parts of
the unit where they could affect the accuracy of
gas delivery and the concentration of anesthetic
gases.
To test this check valve, attach the -10 to +80
cm H2O pressure gauge or meter to the common
gas outlet. Turn off all vaporizers, either filled
or empty. Adjust the oxygen flow control valve to
maintain an outlet pressure of 30 cm H2O. Turn
on the vaporizer flow, and readjust, if necessary,
to maintain 30 cm H2O. Carefully open the
vaporizer filler cap (to prevent a sudden flow of
oxygen into the vaporizer) and observe the outlet
gauge pressure. A sudden pressure drop suggests a leaky check valve. If the check valve is
missing or defective, replace it or alert appropriate personnel to replace the valve to avoid a
possible hazardous buildup of vapor. Note: This
test may not be possible on newer machines that
always maintain a minimum flow of oxygen. On
such devices, follow the manufacturer’s instructions for testing the common outlet back-pressure check valve.
Leakage current should not exceed 300 µA.
2.3
Cycle the flush control slowly several times; it
should move smoothly and not have a tendency
to stick. Check that the oxygen flow returns to
2 L/min within 2 sec each time the flush valve is
closed.
2.4
High-Pressure Leaks. Close all flow control
valves on the machine. Open all cylinder stem
valves one full turn, noting any motion of the
flowmeter floats. Float movement indicates a
leaky flowmeter valve. Record pressure gauge or
meter readings, verifying that they are close to
the service pressure values listed in Table 1.
Close the cylinder stem valves. The pressure
drop over 30 sec should be negligible. Excess
pressure drop indicates an unacceptable leak
that should be located and repaired.
2.5
Intermediate Pressure System. Close all flow
control valves on the anesthesia unit. Connect
the hoses to the external pipeline gas source and
test the supply line hoses with leak-detecting
solution. Note the pressure on the pipeline/central gas supply pressure gauge. (Most machines
should have such a gauge. If not, contact the
manufacturer for instructions for testing the intermediate pressure system.) Disconnect the gas
supply line hose from the machine, and check
that the pressure drop in 30 sec is negligible.
Excessive pressure drop indicates an unacceptable leak that should be located and repaired.
2.6
Low-Pressure Leaks. Attach the -10 to +80 cm
H2O pressure gauge or meter to the unit’s common
2. Quantitative tests
2.1
Grounding Resistance. Use an ohmmeter, electrical safety analyzer, or multimeter with good
resolution of fractional ohms to measure and
record the resistance between the grounding pin
of the power cord and exposed (unpainted and
not anodized) metal on the chassis. We recommend a maximum of 0.5 Ω.
If the device has an accessory outlet, check its
grounding to the main power cord.
2.2
Leakage Current. Measure chassis and patient
lead leakage current to the chassis of the device
with the grounding conductor of plug-connected
equipment temporarily opened. Operate the device in all normal modes, including on, standby,
and off, with all monitors and accessories connected to the unit’s accessory power receptacle(s),
and record the maximum leakage current.
Oxygen Flush Valve. Attach the 100 L/min flowmeter to the common outlet. Set the oxygen flow
rate to a 2 L/min indication on the machine’s
oxygen flowmeter and actuate the oxygen flush
control. The rate should rise to between 35 and
75 L/min. The machine flowmeter indication
should remain near 2 L/min unless the manufacturer’s specification shows otherwise. If it falls
more than 1 L/min, check for an inadequate
oxygen supply, a partially occluded oxygen line
in the machine, or a dirty oxygen inlet filter.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
7
Inspection and Preventive Maintenance System
steady 30 cm H2O, indicated on both the test
gauge or meter and the pressure gauge in the
breathing system, and verify that both gauges
have the same readings. The oxygen flow rate
should be less than 150 mL/min above the leak
measured in Item 2.6.
gas outlet and pressurize the outlet section, including vaporizers, to approximately 30 cm H2O
by opening the oxygen flow control valve slightly
(this is about three times the average working
pressure). Now reduce the flow rate to 30
mL/min. (Connect a flowmeter to the common
gas outlet if necessary.) If the gauge or meter
pressure continues to rise, the leak rate is less
than 30 mL/min at 30 cm H2O (10 mL/min at 10
cm H2O), which is acceptable. If the pressure
falls, the leakage rate is excessive. Locate the
leak by shutting off all vaporizers and repeating
the test with each vaporizer added in turn.
For anesthesia units for which low flow rates
cannot be generated (units that deliver minimum flows of oxygen), the low-pressure system
can be tested in combination with the breathing
system. Connect the -10 to +80 cm H2O pressure
gauge or meter to a piece of breathing system
tubing that is connected to the inspiratory and
expiratory valve outlets. Occlude the outlet to
the manual reservoir bag and close the APL
valve. Turn on the minimum flow of oxygen.
The pressure gauge or meter should read at least
30 cm H2O. A reading of less than 30 indicates
an unacceptable leak that should be corrected.
Proceed to Item 2.7 to identify whether the
breathing system is the major source of the leak.
Alternatively, follow the manufacturer’s recommendations for testing for low-pressure leaks.
2.7
Open the moisture-relief valve. (Note: Due to
dust and moisture, some of these valves on older
units will not turn and might break when force
is applied.) The pressure should drop immediately. If the pressure does not drop, clean the
valve of dried soda lime, repeat the pressurization, and open the relief valve again.
2.8
Breathing System. Check the carbon dioxide absorber housing for cracks or broken edges in the
glass or plastic canister and in the check valve
domes.
Remove the canister from its holder, without
inverting it, and inspect the gaskets for any
absorbent dust and wear. Remove any dust from
the bottom of the absorber. If the amount of dust
seems excessive or if the canister appears seriously pitted, check for dust in the inspiratory
valve and piping, and report the condition to
department personnel.
Check the absorber-elevating mechanism and
clamps for proper operation.
For anesthesia systems without minimum
oxygen flows, connect a breathing hose from the
patient inspiration valve to the patient expiration
valve of the absorber. Close the pressure-limiting valve. Remove the reservoir bag, and replace
it with a -10 to +80 cm H2O pressure gauge or
meter. Pressurize the system with oxygen to a
8
For anesthesia systems with minimum oxygen flow, turn the anesthesia machine off and
connect the -10 to +80 cm H2O pressure gauge or
meter to a piece of breathing system tubing that
is connected to the inspiratory and expiratory
valve outlets. Close the APL valve. Remove the
manual reservoir bag. In its place, connect a
stopper with a fitting for a sphygmomanometer
squeeze bulb. Use the bulb to pressurize the
breathing system to 50 cm H2O. It should take
at least 30 sec for the pressure to drop from 50
to 30 cm H2O. Less time indicates a leak in the
breathing system that should be corrected.
APL Valve. Leave the setup as in Item 2.7 but
remove the pressure gauge or meter, replacing it
with the breathing bag, and restore the normal
pressure-limiting valve setting.
If the APL valve is not the bleeding type,
squeeze the bag and verify that the valve holds
pressure until a specific level is exceeded, and
that it then opens. Check that the opening pressure is adjustable from approximately 1 to at
least 30 cm H2O. Other valves, such as the
Georgia and Drager valves, may operate in a
completely different manner and at a higher
pressure and should be tested according to the
manufacturer’s specified procedure.
2.9
Scavenging System. Insert the pressure gauge or
meter between the APL valve or exhaust port and
the scavenging system intake. Leave the setup as
in Item 2.8, with the APL valve closed or in its
minimum-flow condition. With the scavenging
system operating at maximum suction, the pressure gauge or meter reading should be between
-0.5 and 0 cm H2O. Partially open the APL valve,
and set a 10 L/min oxygen flow rate. With the
scavenging system at the minimum vacuum, the
gauge reading should be near ambient.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Anesthesia Units
stipulated by the manufacturer (usually 100 to
250mL/min).
Repeat the last measurement with the APL
valve fully open while occluding the vacuum hose
and activating the flush valve for 5 sec. The
pressure should remain at less than 10 cm H2O.
2.10 Flowmeters. The following procedure applies to
each flowmeter on the anesthesia unit. Record
the data on Line 2.10 (i.e., oxygen, nitrous oxide,
and air). If other flowmeters are provided (e.g.,
helium, carbon dioxide), make similar checks
and enter data on the back of the form.
Examine flowmeters for signs of damage or
abuse (e.g., internal nicks, scratches, cracks,
condensation, debris).
For each flowmeter, observe the float motion
as the associated valve is turned. The float
should rise and fall freely as the flow is raised or
lowered. At maximum flow, the float should still
be visible at the top of the flow tube.
Connect one of the calibrated flowmeters to
the common gas outlet with its discharge directed into the scavenging or other gas evacuation system. Level the flowmeter. For each gas
in turn, set the flow rates at a high and low
setting for each flowmeter that lies within the
range of the calibrated flowmeter. Record the
readings of both the machine and the calibrated
flowmeters. Repeat the tests with the second
calibrated flowmeter and the second group of
flow rates.
The readings on the unit’s flowmeters should
agree with those on the calibrated flowmeters to
within 10% of set values or the manufacturer’s
specifications. If the error is excessive, check for
damaged, inverted, or interchanged flowmeter
tubes, condensation, or damaged floats.
2.11 Minimum Oxygen Flow and Percent. The following procedure applies to those systems that provide a minimum flow of oxygen or a minimum
percent of oxygen.
Close the valve to the anesthesia unit’s oxygen flowmeter. Connect the 0.1 to 1.0 L/min
oxygen flowmeter to the common gas outlet.
The flowmeter should read the minimum flow
Set the flow of oxygen to around 200 mL/min.
Turn off the flow of nitrous oxide. Using an
oxygen monitor, verify that at least the minimum percent of oxygen (stipulated by the manufacturer) is delivered as the flow of nitrous oxide
is increased.
2.12 PEEP Valve. Set up the breathing system with
a test lung. Use the -10 to +80 cm H2O pressure
gauge or meter to measure the airway pressure
at the test lung. Manually ventilate the test lung
with the PEEP valve set to deliver 0 cm H2O
water pressure. The end-exhalation pressure in
the breathing system should be less than 1 cm
H2O, although this depends on the fresh gas flow
and APL valve setting.
If the PEEP valve is calibrated, set it to deliver
5 and 10 cm H2O water pressure. The pressure
in the breathing system at the end of exhalation
should be within 1.5 cm H2O of the set value.
3. Preventive maintenance
3.1
Clean any excess leak-detection solution from
the exterior and interior of the unit; clean all
compressed-gas filters, if needed.
3.2
Lubricate per the manufacturer’s specifications.
3.4
Replace compressed-gas filters and alarm batteries, if needed.
4. Acceptance tests
Conduct major inspection tests for this procedure
and the appropriate tests in the General Devices Procedure/Checklist 438.
Before returning to use
Depressurize external gas supply; return all flowmeters to zero position; turn all vaporizers to off position; and reconnect all tubing (e.g., main common gas
outlet tubing). Return all controls to pre-use settings.
Attach a Caution tag in a prominent position so the
user is aware that control settings may have been
changed.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
9
Procedure/Checklist 420-0595
Apnea Monitors
Used For:
Apnea Monitors [12-575]
Apnea Monitors, Recording [17-885]
Impedance Pneumograph Monitors [12-621]
Respiration Monitors [12-662]
Also Called: Cardiorespiratory monitors, apnea alarms and respiration monitors, ventilatory effort monitors,
apnea detectors
Commonly Used In: Pediatric departments, homes, critical care units, nurseries, delivery rooms, ambulances
Scope: Applies to apnea monitors, which alarm if a patient stops breathing, and respiration rate monitors,
which display the patient’s breathing rate and alarm when previously selected high or low limits are exceeded;
applies to adult and infant monitoring units or modules, as well as impedance-, motion-, thermistor-, and
airway-pressure-type monitors; does not apply to other types of monitors with respiration monitoring functions
(e.g., capnometers, pulse oximeters); some apnea monitors also include other monitoring capabilities (e.g.,
ECG and blood pressure), which should be checked using the appropriate procedure/checklist unless the
function is very limited (e.g., heart rate alarm without other ECG features)
Risk Level: ECRI Recommended, High; Hospital Assessment,
Type
ECRI-Recommended
Interval
Interval Used
By Hospital
Major
12 months
months
.
hours
Minor
3 months *
months
.
hours
Time Required
* Minor interval applies only to units used for home care.
Overview
Our evaluations of infant apnea monitors have
stressed that apnea monitoring is still an imperfect
science. An ECRI poster (Poster HD 602-980) warned
of the susceptibility of these monitors to artifact and
provided succinct reminders and hints for clinical personnel. An additional poster (Poster HD 625-290) and
warning notice (Health Devices 1990 Apr; 19:142-5)
provide guidance for apnea monitors used in the home.
When inspecting these monitors, in addition to
making a qualitative and quantitative inspection of
the monitor itself, be alert to indications of incorrect
equipment usage and misapplication. Confirm that
users are aware of proper monitoring techniques and
the monitor’s limitations. See the device’s operating
009007
420-0595
A NONPROFIT AGENCY
manual and the Health Devices evaluations cited below
for specific information.
Some apnea monitors have documentation capabilities that typically can record two or more channels of
patient event data ranging from several hours to several months, depending on the amount and format of
data and the parameters stored. Recorded data are
available in two categories: patient (respiratory rate,
heart rate) and equipment (power on/off, low battery).
Patient data can be recorded and printed as either
tabular data or waveforms. These data can be used to
ensure that the monitor is being used properly, to
distinguish true from false alarms, and to troubleshoot
equipment problems.
5200 Butler Pike, Plymouth Meeting, PA 19462-1298, USA
Telephone +1 (610) 825-6000 ● Fax +1 (610) 834-1275
●
E-mail [email protected]
Inspection and Preventive Maintenance System
Activation of memory waveform recording can be
automatic or continuous. Automatic activation is triggered when an event occurs that exceeds preset monitor limits. In the continuous mode, all data from the
selected channels are recorded for a specific duration.
The data stored in the memory can be managed one of
three ways. Some units overwrite the old data with
more recent events; others keep the data that satisfy
specific criteria based on the duration of the events;
and some documentation monitors stop storing data
when the memory is filled.
to 5,000 Ω, variable respiration resistance change
amplitude from 0.1 to 1 Ω, and an apnea function;
simulators with fewer capabilities may be used for
inspection, but additional equipment may be required
to supplement missing functions
ECG simulator with variable rate may be required
(may be part of the respiration simulator or may be
a separate unit)
Memory interface and documentation hardware
and software (where applicable)
Citations from Health Devices
Procedure
Infant apnea monitors [Evaluation], 1980 Aug-Sep;
9:247-83.
Before beginning an inspection, carefully read this
procedure and the manufacturer’s instruction and
service manuals; be sure that you understand how to
operate the equipment, the significance of each control
and indicator, and the alarm capabilities. If the monitor
has memory and documentation capabilities, make sure
the memory contents have been successfully downloaded
and documented. Also, determine whether any special
inspection or preventive maintenance procedures or
frequencies are recommended by the manufacturer.
Connection of electrode lead wires to line power [Hazard], 1987 Feb; 16:44-6.
Infant apnea monitors [Evaluation], 1987 Mar-Apr;
16:79-88.
Infant home apnea monitors [Evaluation update],
1987 Dec; 16:385-7.
Infant home apnea monitors: Essential safety features and practices, 1990 Apr; 19:142-5.
Infant home apnea documentation monitors [Evaluation], 1992 Oct; 21(10):342-79.
Air-Shields System V Model HRRM71-2 heart rate and
respiration monitor [User Experience NetworkTM],
1992 Oct; 21(10):383.
Risk of electric shock from patient monitoring cables
and electrode lead wires [Hazard], 1993 May-Jun;
22(5-6):301-3.
Infant home apnea documentation monitors [Evaluation update], 1993 Dec; 22(12):564-5.
Infant home apnea monitors: Essential safety features
and practices [Hazard update], 1993 Dec;
22(12):598-601.
Do not test the monitor while it is in use. If a
substitute monitor is not available, ask the nursing
staff whether the patient can be temporarily removed
from the unit. It may be necessary for someone to
watch the patient in the interim. Alternatively, arrange to be notified when the monitor is available.
1. Qualitative tests
When performing IPM on apnea monitors with memory and documentation capabilities, a log identifying the
order, type, and duration of patient and equipment
alarms and events should be recorded (e.g., using the
IPM checklist). At the end of the procedure, the memory
contents should be compared to the log contents.
1.1
Chassis/Housing. Examine the exterior of the
unit for cleanliness and general physical condition. Be sure that plastic housings are intact,
that necessary assembly hardware is present
and tight, and that there are no signs of spilled
liquids or other serious abuse. If there are signs
of fluid spills, inspect the interior of the monitor
for intrusion of fluids into electronic circuitry.
The monitor top should not be used as a storage
area for other material (e.g., formula).
1.2
Mount. If the unit is mounted on a stand or cart,
check the mount’s condition. Be sure that all
fasteners are tight and that the mount is sturdy.
Apnea monitors should not be placed on top of
incubators where they can be easily dislodged
Loose-lead alarms resulting from dried-out disposable
electrodes [User Experience NetworkTM], 1994 Jul;
23(7):309-10.
Test apparatus and supplies
Leakage current meter or electrical safety analyzer
Ground resistance ohmmeter
Stopwatch or watch with a second hand
Respiration simulator (needed for impedance-type
monitors only) that includes controls to vary the
respiration rate, variable base impedance from 100
2
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Apnea Monitors
or obscure the view of an infant. A wall-supported shelf or bracket dedicated to the monitor
is recommended.
1.4
1.5
AC Plug/Receptacles. Examine the AC power
plug for damage. Attempt to wiggle the blades
to determine that they are secure. Shake the
plug and listen for rattles that could indicate
loose screws. If any damage is suspected, open
the plug and inspect it. If the device has electrical receptacles for accessories, insert an AC plug
into each and check that it is held firmly. If
accessories are plugged and unplugged often,
consider a full inspection of the receptacle.
Line Cord. Inspect the cord for signs of damage.
If damaged, either replace the entire cord or, if
the damage is near one end, cut out the defective
portion. Be sure to wire the new power cord or
plug with the same polarity as the old one. Also,
check battery charger line cords.
1.6
Strain Reliefs. Examine the strain reliefs at both
ends of the line cord. Be sure that they hold the
cord securely. If the line cord is detachable (by
the user), affix the cord to the unit so that it
cannot be removed by the operator. (See Health
Devices 1993 May-Jun; 22[5-6]:301-3.)
1.7
Circuit Breaker/Fuse. If the device has a
switch-type circuit breaker, check that it moves
freely. If the device is protected by an external
fuse, check its value and type against that
marked on the chassis, and ensure that a spare
fuse is provided.
1.9
Cables. Inspect the cables (e.g., patient sensor,
remote alarm) and their strain reliefs for general
condition. Examine cables carefully to detect
breaks in the insulation and to ensure that they
are gripped securely in the connectors of each
end to prevent rotation or other strain. Electrode leads and cables are often fragile and may
lack adequate strain relief; intermittent contact
can provide false indications.
The lead-electrode connector should be of the
type that cannot be inadvertently plugged into a
115 VAC outlet or power cord. Attach a pair of
electrodes to the patient cable and hold the RA and
LA electrodes face to face. Connect the patient
cable to the monitor, turn the unit on at maximum
sensitivity, and jiggle the leads. If either breaths
or lead faults are indicated, suspect damaged cables or weak contact with the electrodes.
For monitors using belts, bands, a thermistor,
a mattress pad, or other sensor, connect the
sensor to the monitor, turn on the monitor, and
jiggle the sensor cable, being careful not to disturb the sensor in such a way as to simulate a
breath. Observe the monitor for artifacts that
would indicate a defective cable or connector.
1.10 Fittings/Connectors. Examine all fittings and
connectors, including electrical cable connectors,
for general condition. Electrical contact pins or
surfaces should be straight, clean, and bright.
1.11 Electrodes/Transducers. Confirm that any necessary electrodes and/or transducers are on hand
and check their physical condition. If disposable
electrodes are used, be sure an adequate supply
is on hand.
Verify that the insulation on thermistor sensors is intact. Check that air mattresses are free
of leaks and that the tubing that connects the
segments of the mattress to the manifold fits
well, without the use of tape. Keep spare tubing
on hand to make necessary repairs. Carefully
examine sensor belts, bands, or pads (magnetic,
capacitive, or pressure transducer) for intact insulation. If there are cracks or defects in the
insulation, remove the sensor from service.
1.13 Controls/Switches. Before moving any controls
and alarm limits, check their positions. If any
appear inordinate (e.g., a gain control at maximum, alarm limits at the ends of their range),
consider the possibility of inappropriate clinical
use or of incipient device failure. Investigate
questionable control settings on a home care
monitor. Consult with the patient’s physician to
determine correct settings. The parents should
receive additional training if required. Record
the settings of those controls that should be
returned to their original positions following the
inspection. Examine all controls and switches
for physical condition, secure mounting, and correct motion. Where a control should operate
against fixed-limit stops, check for proper alignment, as well as positive stopping. Check membrane switches for membrane damage (e.g., from
fingernails, pens). During the course of the inspection, be sure to check that each control and
switch performs its proper function.
1.17 Battery/Charger. Inspect the physical condition of batteries and battery connectors, if readily accessible.
Check operation of
battery-operated power-loss alarms, if so
Inspection and Preventive Maintenance System
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3
Inspection and Preventive Maintenance System
dized) metal on the chassis with an ohmmeter,
electrical safety analyzer, or multimeter with
good resolution of fractional ohms. We recommend a maximum of 0.5 Ω.
equipped. Operate the unit on battery power for
several minutes to check that the battery is
charged and can hold a charge. Check the condition of the battery charger and, to the extent possible, confirm that it does, in fact, charge the
battery. When it is necessary to replace a battery,
label it with the date.
1.18 Indicators/Displays. During the course of the
inspection, confirm the operation of all lights,
indicators, and visual displays on the unit and
charger, if so equipped. Be sure that all segments of a digital display function.
If the device has an accessory outlet, check its
grounding to the main power cord.
2.2
Leakage Current. Measure chassis leakage current with the grounding conductor of plug-connected equipment temporarily opened. Operate
the device in all normal modes, including on,
standby, and off.
1.19 User Calibration. Confirm that the calibration
or test function operates.
Chassis leakage current to ground should not
exceed 300 µA.
1.20 Alarms/Interlocks. Operate the device in such
a way as to activate each audible and visual
alarm. Check that any associated interlocks
function. If the device has an alarm-silence feature, check the method of reset (i.e., manual or
automatic) against the manufacturer’s specifications. Some apnea alarms that reset automatically when breathing resumes have a separate
indication that an apneic episode has occurred;
this reminds clinical personnel that the patient
needs closer attention. To verify that this indicator functions properly, halt simulated respiration until the apnea alarm sounds, then resume
the simulated respiration. Check that the reset
control functions. If the unit is used with a
remote alarm indicator, verify its function.
If a bedside or central station monitor is
grounded through system interconnections in
addition to power line grounding and is only used
in this configuration, then do not disconnect the
monitor from the system to measure leakage
current during routine inspections. Verifying
low grounding resistance is adequate.
1.21 Audible Signals. Operate the device to activate
any audible signals. Confirm appropriate volume, as well as the operation of the volume
control, if so equipped.
1.22 Labeling. Check that all necessary placards, labels, and instruction cards are present and legible.
1.23 Accessories. Verify that electrode gel, if used, is
available.
1.24 CRT Display. If the unit includes a display of
respiration waveform, check it for focus, slope,
bow, baseline, position, burn spots, and 60 Hz
interference or other noise. Verify that the display amplitude increases as the impedance
change setting of the simulator is increased.
2. Quantitative tests
2.1
4
Grounding Resistance. Measure and record the
resistance between the grounding pin of the
power cord and exposed (unpainted and not ano-
2.3
Open Electrode Indicator. This check is for impedance-type monitors only. Connect the monitor to the respiration simulator. Vary the base
impedance and determine the resistance value
at which the unit first indicates an electrode
fault. This is usually in the range of 1,000 to
2,000 Ω.
2.4
Sensitivity.
Impedance-type monitors. If the monitor has a
manual sensitivity control, set it at maximum
sensitivity. Connect the respiration simulator
and, if adjustable, set it for a base impedance
of 500 Ω, resistance change of 1 Ω, and breathing rate of 30 bpm (15 bpm for an adult monitor). Verify that the monitor detects each
resistance change. Decrease the resistance
change on the simulator and record the minimum value for which breaths are reliably
detected. Most monitors will detect resistance changes of 0.1 to 0.3 Ω at maximum
sensitivity.
Increase the rate to 100 bpm and verify that
the sensitivity does not change abnormally.
Discrepancies between similar monitors or
from previous readings greater than 25% suggest significant deterioration of the monitor
and should be investigated.
With the monitor set at maximum sensitivity, verify that breaths are not detected when
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Apnea Monitors
2.5
the simulator is set to 0 bpm or turned off.
Some simulators, when turned off, may present a high base resistance to the monitor that
can cause extraneous noise pickup.
activated when the indication falls below 22
bpm. Some monitors have fixed alarm delays;
check the instruction manual to determine
whether this feature is present.
Other types. Only qualitative tests of sensitivity
can be made with other types of sensors.
Simulate breaths in the appropriate manner
for each monitor, and observe that the sensitivity varies with the control setting. In some
cases, sensitivity will vary with the simulated
respiration rate. Confirm the absence of artifacts at maximum sensitivity.
Next, simulate a rate of about 60 bpm, reset
any alarms, then increase the simulated rate to
80 bpm or higher, and verify the operation of the
high-rate alarm.
ECG Features. If the unit includes ECG and
heart rate monitoring, perform trace quality and
additional testing as part of a separate ECG
Monitors procedure. If the unit has limited ECG
features — such as a heart rate alarm — but no
additional ECG functions, test these as part of
this procedure. If more extensive ECG tests are
required, see ECG Monitors Procedure/Checklist 409.
2.10 Apnea Alarm Delay Time. Check the apnea
alarm delay by stopping simulated respirations.
Time the delay between cessation of respiration
and apnea alarm. Measured times should agree
with indicated times within 20%. Check all
times, if discrete times are available. If the
control is continuously variable, check both
shortest and longest times. Check the alarm-silence function, if so equipped.
2.11 Ratemeter Accuracy. Using the respiration
simulator, check the rate display on respiration
rate monitors at low rate (about 15 bpm for adult
units and 30 bpm for infant units) and high rate
(100 bpm). Read the ratemeter when it reaches
equilibrium. Indicated rates should be accurate
to within 10%.
If the ratemeter is digital, vary the simulated
rate to check for malfunctioning digits. A display
of “8” in the tens and units position will check all
elements of a segmented or dot display; a “1” and
“0” in the hundreds place is all that is needed there.
2.12 Rate Alarm Accuracy. Set the low and high respiration rate alarms at 22 and 78 bpm, respectively. Simulate a respiration rate of about 30
bpm, set the apnea delay to at least 10 sec, and
reset any alarms that may have been triggered
during setup. Slow down the simulated respiration rate to about 20 bpm. Observe the ratemeter, and verify that the low-rate alarm is
3. Preventive maintenance
3.1
Clean the exterior of the unit with a damp cloth,
if needed.
4. Acceptance tests
In addition to other considerations, every apnea
monitor must include a heartbeat detector (or other
backup mechanism to the primary apnea detection
function). If battery-powered, the unit must indicate
whether it is operating on battery power or is being
powered (and charged) from line power. For home use,
monitors must also include a power-loss alarm (nonbattery-operated unit) and a remote alarm. (See Health
Devices 1990 Apr; 19:142-5 for further information.)
Conduct major inspection tests for this procedure
and the appropriate tests in the General Devices Procedure/Checklist 438. In addition, perform the following tests.
4.1
Sensitivity. Testing is similar to that described
in Item 2.4; however, record the actual sensitivity at high and low breathing rates (at low,
medium, and high sensitivity on manual units).
Also, record the maximum sensitivity at a base
impedance of 100 Ω.
4.2
Coincidence Circuit. Some monitors include coincidence circuitry designed to compare breathing and heart rate signals or data and to reject
detected breaths that may, in fact, be erroneously detected QRS complexes. If possible, verify operation of coincidence circuitry during
incoming inspection.
Before returning to use
Remind clinical personnel of the limitations of the
monitor and be sure that they understand the operating
principles of that particular unit, since a hospital may
own more than one type of apnea monitor. Also, make
sure that the audible alarm volume, including remote
alarm if needed, is set so that it can be clearly heard. If
the monitor is being used at home, make sure that the
controls are set correctly for the patient application.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
5
Procedure/Checklist 462-0595
Argon Surgical Lasers
Used For:
Lasers, Surgical, Argon [16-941]
Also Called: Argon lasers, blue/green lasers, surgical lasers, bronchopulmonary lasers, gastroenterology
lasers, high-power ophthalmic lasers, photocoagulator lasers
Commonly Used In: Operating rooms, short procedure areas, endoscopy laboratories, ophthalmic operating rooms
Scope: Applies to general-purpose argon surgical lasers that include contact and/or noncontact flexible
fiberoptic delivery systems (either reusable or disposable), emit blue-green visible light energy at 514 and 488
nm, and can provide sufficient power output to coagulate and vaporize tissue; applies to low- and high-power
argon surgical lasers that are typically used for general surgery, gastroenterology, bronchopulmonary,
neurosurgery, gynecology, and ENT surgery procedures; does not apply to ophthalmic argon lasers, which are
typically low power (e.g., below 2 W); however, many of the tests listed herein can be used or modified for
these other lasers
Risk Level: ECRI-recommended, High; Hospital assessment,
Type
ECRI-Recommended
Interval
Major
12 months
months
.
hours
Minor
6 months
months
.
hours
Overview
Argon lasers are normally checked before each use by
the laser’s power-on self-test and by user examination
of the aiming beam and the delivery system to be used.
This minimizes the need for frequent additional periodic testing.
Manufacturers or outside service vendors often
maintain lasers for hospitals. The extent and frequency of inspection by hospital personnel should be
coordinated with these outside services.
Failure of an argon surgical laser can cause patient
or staff injury, abrupt interruption of a surgical procedure, or damage to the laser system. These lasers must
be meticulously maintained in order to ensure proper
and safe operation.
230380
462-0595
A NONPROFIT AGENCY
Interval Used
By Hospital
Time Required
Argon surgical lasers affect tissue by delivering
blue-green visible light energy at a sufficient power
density to cause vaporization and/or coagulation. The
488/514 nm argon energy is preferentially absorbed by
pigmented tissue and hemoglobin and is typically absorbed within 3 mm of the tissue surface. Argon surgical laser fibers are most often used in contact with or
close to tissue to cause coagulation and vaporization.
Moving the fiber tip away from the tissue to lower the
power density causes less tissue to be vaporized and
coagulated.
General-purpose argon surgical lasers have a laser
tube containing an argon gas mixture that is caused to
emit light energy by an electric field. This energy
leaves the laser tube through a partially reflecting
mirror and is typically directed into a flexible optical
fiber that transmits the laser energy to the tissue. The
fiber may be used with additional devices (e.g., through
5200 Butler Pike, Plymouth Meeting, PA 19462-1298, USA
Telephone +1 (610) 825-6000 ● Fax +1 (610) 834-1275
●
E-mail [email protected]
Inspection and Preventive Maintenance System
an endoscope), with a headpiece and lens, and/or with
a laser handpiece or a laser micromanipulator (used to
interface the laser with the surgical microscope).
These attachments may focus the energy into a small
spot size at a known working distance and/or a specific
beam direction to accomplish special tasks (e.g., energy
can be emitted from the surgeon’s headpiece through
a handheld lens and focused on the patient’s retina).
In addition, argon lasers can emit a single pulse or a
train of pulses.
Like most lasers, argon lasers are inefficient in
converting electrical energy into laser energy. As a
result, excess heat is generated in the laser cavity,
requiring a cooling system. Most argon lasers use
water/air cooling systems that are self-contained, connected to a freestanding chiller system, or connected
to a water supply and drain.
Citations from Health Devices
Laser use and safety [Guidance article], 1992 Sep;
21(9):306-10.
Surgical lasers [Evaluation], 1991 Jul-Aug; 20(78):239-316.
Test apparatus and supplies
Leakage current meter or electrical safety analyzer
Ground resistance ohmmeter
New, unused fiber delivery system
Black Delrin block 1⁄2″ or more thick, 1″ or more wide,
about 3″ to 4″ long; tongue depressors; or firebrick
Laser radiometer (power meter)
Laser safety signs
Laser safety eyewear specifically designed for use
with argon surgical lasers and of sufficient optical
density to protect the wearer’s eye from laser injury
Vise with padded jaws or ring stand with padded
clamp
Pressure gauges and coolant system tee fitting
Outlet test fixture (optional)
Insulating gloves, high voltage (optional)
Grounding strap (optional)
Calibrated flowmeter
Special precautions
Inspecting and maintaining lasers is a dangerous as
well as necessary process, and far greater care is
required than with most devices. Personnel who inspect or service lasers should receive special training
2
from the manufacturer or from a qualified alternative
training source.
Laser energy can cause serious injury, particularly
when the internal interlock is overridden or in any
other situation in which the energy does not diverge
significantly over long distances. Under some circumstances, the beam may not diverge significantly, even
a full room length or more away from the laser (and
can harm tissue or burn material even at this distance). Therefore, exercise great care whenever a laser
beam is accessible. Area security and use of personnel
protective devices and practices should be consistent
with hospitalwide laser safety procedures and/or
should be approved by the laser safety committee.
In addition, windows should be covered with nonreflective material to prevent transmission of laser energy to other areas.
Wear appropriate laser safety eyewear at all times
whenever the laser is in the Operating mode. WARNING: Do not stare directly into the aiming system beam
or the therapeutic laser beam, even when wearing laser
safety eyewear. Avoid placing the laser beam path at
eye level (i.e., kneeling, sitting, or standing).
Do not perform these procedures when a patient is
present or clinical staff is working, and do not aim the
laser across a path that a person might normally use
as a thoroughfare. Furthermore, at minimum, post
doors to the room with appropriate laser safety signs
stating that the laser is in use and that it is unsafe to
enter the room without authorization by the service
person performing the procedure. A second person
should be present, especially during procedures of recognized risk, to summon help in case of an accident.
The laser should remain in the off position when not
in use. When in use, it should be in the standby/disabled mode. Do not switch it to the operating mode
until the procedure is about to begin and the laser and
its delivery system are properly positioned. If the procedure must be interrupted, disconnect the laser from
line voltage, and remove the laser operation key and
store it in a controlled location.
Do not use the laser in the presence of flammable
anesthetics or other volatile substances or materials
(e.g., alcohol), or in oxygen-rich atmospheres, because
of the serious risk of explosion and fire. Remove from
the working area or cover with flame-resistant opaque
material all reflective surfaces likely to be contacted
by the laser beam. Whenever possible, use a firebrick
or other nonflammable material behind the target material (e.g., black Delrin) when the laser is to be activated.
Target materials will ignite when exposed to high laser
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Argon Surgical Lasers
and ensure that they have been turned off
after the last use. Examine the exterior of the
unit for cleanliness and general physical condition. Be sure that all housings are intact and
properly aligned, that assembly hardware is
present and tight, that any retractable parts
slide easily and lock in place if so constructed,
that there are no signs of spilled liquids or
other evidence of abuse, and that there are no
obvious signs of water or oil leakage.
energies; use short durations when practical. A CO2
fire extinguisher should be readily available.
Some surgical lasers use high voltages (e.g., 20 kV),
which can be lethal. Capacitors may store charges long
after the device has been disconnected from line voltage. Consult the manufacturer’s recommended procedures for servicing high-voltage laser circuits, and
avoid contact with any portion of the high-voltage
circuit until you are certain that the charge has been
drained. In such instances, a good ground must be
present; preferably, use a redundant ground strap if
you must enter the laser cabinet. When possible, disconnect the laser from line voltage before entering the
laser cabinet, and use insulated gloves for those procedures in which contact with a high-voltage source is
possible (and the gloves are not otherwise contraindicated). Ensure that equipment intended to be used to
measure, drain, or insulate high voltages carries the
appropriate insulation rating (e.g., above 20 kV).
Shutters. If manual shutters for the aiming system or the therapeutic lasers are accessible,
ensure that they operate smoothly and correctly. Be sure to leave the shutter in the
proper position for normal operation.
1.2
Where possible, perform tests with the unit turned
off. Because of the presence of high voltage, perform
the Grounding Resistance test (Item 2.1) before any
other test that requires operation of the laser.
Mounts/Holders. Check that the mounts securely contain any gas cylinders that may be in
use. Be sure that mounts or holders intended to
secure the fiber to the fiber support (to protect
the fiber when in use) are present, in good working order, and being used. Similarly, check
mounts or holders for other devices (e.g., external power meters, footswitches).
WARNING: Do not use an anesthesia or other similar bag that may have a mold-release agent (e.g., starch,
talc) on its inside surface because the agent could
contaminate the gas recirculation system of the laser
and ultimately contaminate a patient wound during a
subsequent procedure.
1.3
Report any laser accident immediately to the laser
safety officer or equivalent, as well as to the hospital
risk manager.
Casters/Brakes. Verify that the casters roll and
swivel freely. Check the operation of brakes and
swivel locks.
1.4
AC Plug/Receptacle. Examine the AC power
plug for damage. Wiggle the blades to determine whether they are secure. Shake the plug,
and listen for rattles that could indicate loose
screws. If damage is suspected, open the plug
and inspect it.
1.5
Line Cords. Inspect line cords for signs of damage. If a cord is damaged, replace the entire cord,
or, if the damage is near one end, cut out the
defective portion. Be sure to wire a new power
cord or plug with the correct polarity.
1.6
Strain Reliefs. Examine the strain reliefs at
both ends of the line cord. Be sure that they grip
the cord securely.
1.7
Circuit Breakers/Fuses. If the device has a
switch-type circuit breaker, check that it moves
freely. If the device is protected by an external
fuse(s), check its value and type against what is
marked on the chassis or noted in the instruction
If the device is mounted on a stand or a cart,
examine the condition of the mount. Verify that
the mounting apparatus is secure and that all
hardware is firmly in place.
Procedure
Before beginning the inspection, carefully read this
procedure and the manufacturer’s operator instructions and service manual; be sure that you understand
how to operate the equipment, the significance of each
control and indicator, and precautions needed to ensure safety and avoid equipment damage. Also, determine whether any special inspection or preventive
maintenance procedures or frequencies are recommended by the manufacturer.
1. Qualitative tests
1.1
Chassis/Housing.
General. Verify that the key has not been left in
the laser. (Remove it if it has been, and inform
users of the importance of storing the key in a
controlled location.) Examine any external
gas tanks that may be in use with the laser,
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
3
Inspection and Preventive Maintenance System
service manual. Ensure that a spare is provided
or readily available.
1.8
Tubes/Hoses. Check the condition of all cooling-system hoses and any other hoses or tubing
the laser may have (e.g., drain, gas). Check that
they are of the correct type; that they have not
become cracked and do not show other signs of
significant abuse; that they are connected correctly and positioned so that they will not leak,
kink, trail on the floor, or be caught in moving
parts; and that they are secured adequately to
any connectors.
1.9
Cables. Inspect all cables and their channels or
strain reliefs for general physical condition. Examine cables carefully to detect breaks in insulation and to ensure that they are gripped
securely in the connectors at each end to prevent
strain on the cable.
1.10 Fittings/Connectors. Examine all optical (e.g.,
fiber), gas, liquid, and electrical fittings and connectors for general physical condition. Gas and
liquid fittings should be tight and should not
leak. Electrical contacts should be straight,
clean, and bright.
There should be no visible dirt or residue in
the optical path of the laser aperture. Ensure
that any mechanism to close off the laser aperture (fiber port) is clean, operates smoothly, and
is in use.
If external gas tanks or wall-supply outlets
can be used, gas-specific connectors should be
present. Be sure that no pins are missing from
yokes and that the keying and indexing of connectors for each gas to be used is correct. A laser
that connects to a central piped medical gas
system or to a freestanding medical gas system
should have the matching DISS or quick-connect
fitting for the gas that it is to be used with. Verify
that suitable unique connectors are supplied so
that adapters are not required.
1.12 Filters. Check the condition of all liquid and air
filters. Some argon surgical lasers require deionized water, and most require special filtration.
Measuring the pressure drop across a liquid
filter can be helpful in determining whether the
filter should be replaced. Clean or replace filters
according to the manufacturer’s recommendations (e.g., replace if the pressure drop is >5 psi),
and indicate this in the preventive maintenance
section of the inspection form. Clean or replace
air filters that are obviously dirty.
4
1.13 Controls/Switches.
General. Before moving any controls, check and
record their positions. If any position appears
inordinate, consider the possibility of inappropriate use or of incipient device failure. Examine all controls and switches for physical
condition, secure mounting, and correct motion. If a control has fixed-limit stops, check
for proper alignment as well as positive stopping. Check membrane switches for tape residue and for membrane damage (e.g., from
fingernails, pens, or surgical instruments). If
you find such evidence, notify users to avoid
using tape and sharp instruments. During the
inspection, be sure that each control and
switch works properly.
Remote. Examine the exterior of the control for
cleanliness and general physical condition. Be
sure that housings are intact, that assembly
hardware is present and tight, and that there
are no signs of spilled liquids or other serious
abuse. If the remote control is attached by
cable to the laser, ensure that the cable and
any connectors are in good condition. Examine
all controls and switches for general physical
condition, secure mounting, correct motion,
and intended range of settings. Where a control should operate against fixed-limit stops,
check for proper alignment as well as positive
stopping. During the course of the inspection,
be sure to check that each control and switch
performs properly.
Footswitch. Examine the footswitch for general
physical condition, including evidence of
spilled liquids. Footswitches for lasers include
an internal switch that activates according to
the depth of pedal depression. It is usually
possible to feel the vibration caused by closure
of the switch, even through a shoe. Check that
the internal switch is operating and that the
footswitch does not stick in the on position.
Some footswitches include two internal
switches; in this case, verify the operation of
both. Some footswitches also include a switch
to operate the liquid- or gas-cooling system.
Check to be sure that this switch operates
reliably.
During the procedure, check to be sure that
the laser activates consistently when the footswitch is depressed and that the fiber-coolant
system operates properly when the fiber-coolant switch is activated and deactivated. Flex
the cable at the entry to the switch, and, using
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Argon Surgical Lasers
information expected. Ensure that user prompts
occur in the proper sequence. Store some sample
information, and verify that it is correct. If a
feature to manually reset this information is
available, ensure that it works.
an ohmmeter, check for internal wire breaks
that cause intermittent operation. Confirm
that strain reliefs are secure.
Examine the male and female connectors
for attaching the footswitch to the laser
cabinet to be sure that no pins are bent and
that no other damage is present. Ensure
that the connector secures acceptably to the
laser cabinet.
1.15 Motors/Pumps/Fans/Compressors. Check the
physical condition and proper operation of these
components, if present. If lubrication is required,
note this in the preventive maintenance section
of the form.
1.16 Fluid Levels. Check all fluid (e.g., coolant) levels. Refill or change the fluid according to the
manufacturer’s recommendations, and note this
in the preventive maintenance section of the
inspection form. If an external water supply is in
use, ensure that the water pressure is properly
regulated and at the appropriate pressure and
that the supply and drain system is properly
configured (e.g., filters are oriented for proper
flow, drain hoses are positioned in a sink or
drain).
1.17 Battery. Inspect the physical condition of batteries and battery connectors, if readily accessible.
If a remote control or display is battery powered,
check or replace the battery (periodic prophylactic battery replacement is often preferred to risking battery failure during use). When it is
necessary to replace a battery, label it with the
date.
1.18 Indicators/Displays. During the course of the
inspection, verify proper operation of all lights,
indicators, meters, gauges, and visual displays
on the unit and remote control. Ensure that all
segments of a digital display function. Note any
error messages displayed during the power-on
self-test.
1.19 Laser Delivery System Calibration. Some argon
surgical lasers include a user-accessible calibration port or power meter that allows output calibration and/or testing of the laser fiber. This
feature is provided because transmission of laser
energy through a fiber may change as a result of
fiber use. Based on the measurement from the
calibration power meter, the laser may automatically recalibrate itself and/or adjust displays so
that the power indicated to be delivered to the
patient will be correct; or it may require the user
to do this manually. Verify that this feature is
functioning by using the manufacturer’s recommended calibration procedure to test one delivery system (e.g., fiber, handpiece) that the
manufacturer indicates can be acceptably calibrated using these procedures. A good-quality
(e.g., >85% transmissibility, undamaged sheath)
fiber or handpiece should be used for this test.
1.20 Alarms/Interlocks. Operate the device in a
manner that will activate the self-check feature,
if present, and verify that all visual and audible
alarms activate according to the manufacturer’s
documentation. If no self-check feature is present, operate the laser in a manner that will
activate each audible and visual alarm; be sure
to test only those alarms that will not cause
damage to the laser or present an unnecessary
risk of laser beam exposure to the user or bystanders.
If a door or window interlock is used, ensure
that it deactivates the laser properly. (Do not
disassemble major parts of the laser to test internal interlocks.) After deactivating the laser
and reclosing the door or window, check to be
sure that the laser will restart. Be sure to check
the interlocks in all locations where the laser is
used. (For some lasers, the function of the interlocks can be checked using an ohmmeter.)
If primary and remote-control indicators and
displays can be used at the same time or if control
can be switched from one to the other during the
course of a procedure, verify that the same information (e.g., settings, displays) is indicated on
both control panels during laser operation.
If display screens or digital displays are provided for user prompts or for viewing accumulated
information (e.g., pulse or accumulated energy
counter), ensure that each display provides the
If the laser is equipped with an emergency
“kill” switch, test this feature to be sure that it
deactivates the laser and that the laser will
subsequently restart.
1.21
Audible Signals. Operate the device to activate
any audible signals (e.g., laser emission, setting
change). Check for proper operation, and verify
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
5
Inspection and Preventive Maintenance System
that the signal can be heard in the environment
in which the laser will be used.
recommendations for the procedures and
cleaning agents to use to clean lenses.
1.22 Labeling. Check that all placards, labels, and
instruction cards noted during acceptance testing are present and legible. Check to see that an
instruction manual is kept with the laser or is
readily available.
Ensure that major subcomponents of the
handpiece, when assembled, are secure. Ensure that the mechanisms used to connect the
handpiece(s) to the fiber are in good working
order and that they reliably secure each handpiece to the fiber.
1.23 Accessories.
General. Verify that all necessary accessories
are available and in good physical condition.
Set up reusable accessories with the laser to
ensure compatibility and proper functioning.
Checking all fibers or accessories during a
single inspection and preventive maintenance procedure is unnecessary as long as
accessories are routinely checked by the person(s) responsible for laser setup and operation. In addition, many of the accessories are
sterile and would require resterilization before use, making the laser potentially unavailable. Be sure to check with the person
responsible for scheduling the use of the laser
before beginning the procedure.
Fibers. For the test fiber or before each use,
examine the connector, cable, and tip of each
fiber that may be used, as well as the fiber
support, for cleanliness and general physical
condition. Be sure that all hardware (e.g.,
laser gas tubing channels) is present, in good
condition, and firmly attached. Ensure that
the connector properly seats into the laser
aperture of the laser cabinet. Examine the
distal end of fibers to ensure that any connecting mechanisms (e.g., threads) are in proper
working order.
If a fiber appears to be dirty or damaged,
remove it from service. If a fiber is reusable,
notify the person(s) responsible for fiber repair. The fiber should be repaired and/or
cleaned according to the manufacturer’s recommendations. Verify fiber performance.
Handpieces. Examine each handpiece component (e.g., body, tips, lenses) for cleanliness
and general physical condition. Examine individually only those components that are
intended for removal during normal use and
storage. (Do not remove other parts that are
press-fit or attached by screws, bolts, or
snap-rings.) If lenses are detachable, be sure
not to touch the lens surface; handle lenses
by the edges only. Consult the manufacturer’s
6
Microscope micromanipulator. Examine the microscope micromanipulator for cleanliness
and general physical condition. Be sure to
handle it by the main body; do not hold it by
the joystick, and do not touch the reflecting
lenses in the body. Inspect micromanipulators
provided by both the laser manufacturer and
the laser accessory manufacturer.
Ensure that the reflecting lenses are intact
and clean. Consult the manufacturer’s recommendations for the procedures and cleaning
agents to use to clean reflecting lenses.
Examine the joystick to ensure that it is
firmly attached and that it freely moves the
reflecting lens. If a finger rest is present,
ensure that it is firmly attached and properly
oriented.
If a zoom focus feature is present, be sure
that it turns easily and does not slip. Examine
each objective lens to ensure that it is intact
and clean. Do not touch the lens surface. Consult the manufacturer’s recommendations for
the procedures and cleaning agents to use to
clean the objective lenses. Carefully insert
each lens into the micromanipulator, and ensure that it fits snugly.
Inspect the mechanism used to attach the
micromanipulator to the microscope to ensure
that all parts are present and that it is in good
working order. Connect the micromanipulator to the microscope to check for a secure
connection.
Safety filters. Verify operation of safety filters
in the microscope and endoscope delivery
systems.
1.24 Aiming Beam. Argon lasers typically use an attenuated therapeutic beam as the aiming beam.
Activate the aiming beam (without the therapeutic beam), and verify that it produces a round,
uniformly bright spot, with no halo. For handpieces that provide adjustable spot sizes, verify
that the spot size changes as expected and still
remains uniform.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Argon Surgical Lasers
on the chassis should not exceed 300 µA; in no
case should it exceed 500 µA. Where it is greater
than 300 µA, ensure that appropriate grounding
is present.
1.25 Laser Aperture.
WARNING: Make this inspection with the laser powered off. Remove and inspect the protective window (e.g., blast shield) behind the laser
aperture. It should be clean and undamaged;
replace if needed. There should be no visible dirt
or residue in the optical path of the laser aperture.
2.3
1.26 Gas Regulators. Examine any gas regulators for
cleanliness and general physical condition. Ensure that the gauges on the regulators are not
broken. During the procedure, ensure that the
regulator and the gauge operate as expected.
Verify that the correct gas is attached to each
regulator. Be sure that a key or wrench to facilitate changing the gas supply is with the unit or
readily available.
Place and secure the laser fiber, handpiece, or
micromanipulator with the aiming system focused on the black Delrin or a tongue depressor.
With the laser set to about 10 W and the exposure set at a minimum duration, activate the
laser and create a burn. Carefully move the
Delrin to expose a clean area, maintaining the
same distance. Adjust the exposure setting in
increments of 0.1 sec or the next longest duration, and activate the laser at each setting. Continue this process until you have tested all
exposure settings, except continuous, and have
developed a series of burns. Compare the burns
to verify that progressively larger burns occurred as the exposure duration increased.
If the laser includes a gas recirculation system, ensure proper operation by allowing it to
control the gas supply into and out of a sealed
plastic bag.
WARNING: Do not use an anesthesia or other
similar bag that may have a mold-release agent
(e.g., starch, talc) on its inside surface because the
agent could contaminate the gas recirculation
system of the laser and ultimately contaminate a
patient wound during a subsequent procedure.
2.4
If proper operation is questionable, consider
using a calibrated flowmeter to measure actual
gas flow.
2. Quantitative tests
2.1
2.2
Grounding Resistance. Use an ohmmeter, electrical safety analyzer, or multimeter with good
resolution of fractional ohms to measure and
record the resistance between the grounding pin
on the power cord and exposed (unpainted and
not anodized) metal on the chassis, accessory
outlet, ground pins, and footswitch. We recommend a maximum of 0.5 Ω. (If the footswitch is
of low voltage, grounding is not required.)
Repeat Pulse. If the unit includes a repeat pulse
feature, which repeats the pulse at a fixed or
adjustable rate, test this feature with the laser
set at the minimum, median, and maximum
repeat pulse settings, if adjustable. Some laser
power meters can react quickly enough to be
used to test this feature of the laser. If you are
using such a power meter, test the laser to be
sure that the correct power is repeatedly delivered over the correct time period.
If your laser power meter cannot be used for
this test, use the following alternative test
method. Set the laser to about 10 W and a 0.1
sec exposure duration with the fiber, handpiece,
or micromanipulator attached, and verify that
the repeat pulse feature operates as expected by
moving the Delrin or the colored tongue depressor slightly between each pulse. Be extremely
careful to keep hands out of the laser beam path.
If the number or duration between repeat pulses
is adjustable, test that setting changes made
throughout the range result in the expected
performance.
Leakage Current.
WARNING: Do not reverse power conductors
for this or any other test. Improper attachment of
conductors may damage the laser.
With the laser attached to a grounded powerdistribution system, measure the leakage current
between the chassis and ground with the unit
grounded and ungrounded. The leakage current
Exposure Duration. Some laser power meters
can measure pulse duration. If the power meter
can react to pulse duration (this is the preferred
circumstance), test the laser at each setting.
However, if the laser power meter does not measure pulse duration, use the following less preferable alternative.
2.5
Footswitch Exposure Control. Set the output
time for about 5 sec, activate the unit, and re-
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
7
Inspection and Preventive Maintenance System
lease the footswitch after about 1 sec. Verify that
the beam turns off when the footswitch is released.
2.10 Power Output. Select one delivery system (e.g.,
fiber, handpiece, micromanipulator), and perform the manufacturer’s recommended user calibration procedure. Secure the delivery system at
the appropriate distance from the detector of the
laser power meter to meet spot-size requirements specified in the instructions for the meter.
(Do not focus the beam to a small spot on the
power meter. Some power meters require that
the unfocused or a defocused laser beam be projected into the power meter to cover the majority
of the absorber surface. If the laser beam is
focused on the detector of such meters, the meter
may be damaged.)
WARNING: Accessing the unfocused laser
beam may require defeating internal interlocks.
Because of the heightened risk associated with an
unfocused, nondiverging laser beam, exercise
great care if the interlocks are to be defeated.
With the laser set at low (e.g., 10% of full
scale), medium (e.g., 50% of full scale), and maximum output, activate the laser for a sufficient
period to acquire acceptable readings. (Power
meters use different time constants to acquire an
acceptable reading, and you must know and meticulously follow them.) Compare the reading
with the power display of the laser; the measured
and displayed values should all be within 10% of
one another. In addition, compare the reading
obtained with the reading taken on incoming
acceptance testing, at the last preventive maintenance procedure, or after the last service procedure. If the laser includes a low-power (e.g.,
mW) feature, test it in a similar fashion with a
power meter of appropriate resolution in the
low-power range.
3.3
Calibrate/adjust any components (e.g., printer)
according to the manufacturer recommendations. Only appropriately trained personnel
should attempt laser adjustments. Ensure that
all hoses and tubes are tight.
3.4
Replace filters if needed. Check all fluid levels
and supplement or replace fluids if needed.
4. Acceptance Testing
Conduct major inspection tests for this procedure
and the appropriate tests in the General Devices Procedure/Checklist 438.
WARNING: Lasers may be damaged by switching
between normal and reverse polarity while the device is
on. If reverse-polarity leakage current measurements
are made, turn off the unit being tested before switching
polarity. Also, lasers powered by three-phase electrical
systems may be damaged if proper electrical phase
connections are not made initially and maintained
thereafter. Thus, do not switch conductor connections
or wiring configurations for any tests, including leakage current measurement. Do not conduct electrical
leakage current tests with reversed-polarity wiring.
Also test the ability of the laser to deliver laser
energy as expected in all configurations and with all
provided laser accessories. In addition, perform the
following tests.
4.1
Areas of Use. Visit the area(s) in which the laser
is to be used and ensure that laser signs,
eyewear, and window coverings are available
and being used and that safety interlocks for
doors or windows, if present, are functioning
properly.
4.2
Casters/Mounts/Holders. Ensure that the assembly is stable and that the unit will not tip
over when pushed or when a caster is jammed on
an obstacle (e.g., a line cord, threshold), as may
occur during transport. If the device is designed
to rest on a shelf, ensure that it has nonslip legs
or supports.
4.3
Labeling. Examine the unit and note the presence, location, and content of all labels. Labeling
information is typically found in the laser’s operator manual.
4.4
Electrical Wiring Configuration. Ensure that
the branch circuits and the outlets for the laser
are properly wired and rated for use with the
laser. Examine the receptacles at each location
where the laser is to be used to ensure that the
proper electrical configuration (e.g., proper
3. Preventive maintenance
Verify that all daily preventive maintenance procedures recommended by the manufacturer are carried
out.
3.1
3.2
8
Clean the exterior. Clean accessible optical components (e.g., blast shield, microscope lenses), if
necessary, using techniques and cleaning solutions recommended by the manufacturer.
Lubricate any motor, pump, fan, compressor or
printer components as recommended by the
manufacturer.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Argon Surgical Lasers
neutral and ground connections, proper phase
rotation) has been installed. Verify proper wiring and connect the laser to each receptacle and
confirm that the laser operates properly, specifically confirming that motors are operating in the
proper direction.
4.5
AC Plug. Verify that the plug is acceptable for
use with the maximum current and voltage
specifications for operating the laser. (Consult
National Electrical Manufacturers Association
[NEMA] configurations for general-purpose nonlocking and locking connectors if in doubt.)
4.6
Pulse Duration. Verify that progressive increases in pulse duration throughout its range of
adjustment result in progressively larger burns.
4.7
Repeat Pulse. If the unit includes a Repeat Pulse
feature, test this feature as described in Item 2.4,
but over the full range of available settings.
4.8
Power Range. Using the technique described in
the Power Output test (Item 2.10), test the power
output accuracy at several low, medium, and
high settings.
4.9
Laser Delivery System Calibration. Use the
manufacturer’s recommended calibration procedure to test each new reusable delivery system
(e.g., fiber, handpiece) that the manufacturer
indicates can be acceptably calibrated using
these procedures. Note the fiber transmission for
each delivery system tested if this information is
provided by the laser. Or, you can calculate it
using the following formula:
% Transmission =
Delivered power
× 100%
Power entering the fiber
Delivery systems with less than the manufacturer-recommended transmission (typically
>80%) should be returned to the manufacturer.
Before returning to use
Be sure to return controls to their starting position,
and place a Caution tag in a prominent position so that
the next user will be careful to verify control settings,
setup, and function before using the unit.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
9
Procedure/Checklist 433-0595
Aspirators
Used For:
Aspirators [10-208]
Aspirators, Emergency [15-016]
Aspirators, Low-Volume [10-215]
Aspirators, Surgical [10-217]
Aspirators, Thoracic [10-218]
Aspirators, Tracheal [10-219]
Aspirators, Uterine [10-222]
Pumps, Breast [10-485]
Also Called: Portable suction units, gastric aspirators (low-volume aspirators), pleural aspirators (thoracic
aspirators), Gomco (a registered trademark of Allied Healthcare Products, Inc. to be used only when referring
to that device)
Commonly Used In: Ambulances, critical care units, emergency departments, operating rooms; tracheal
aspirators also found on “code carts” and low-volume (or intermittent) aspirators frequently used in
medical-surgical units
Scope: Applies to virtually all electric-powered portable and mobile suction sources; does not apply to suction
regulators (see Procedure/Checklist 459)
Risk Level: ECRI Recommended, High for Emergency and Tracheal Aspirators, Medium for Surgical, Thoracic,
and Uterine Aspirators, Low for Low-volume Aspirators and Breast Pumps; Hospital Assessment,
for Breast Pumps,
for Emergency Aspirators,
for
for Surgical Aspirators,
for Thoracic AspiraLow-volume Aspirators,
tors,
for Tracheal Aspirators,
for Uterine Aspirators
Type
ECRI-Recommended
Interval
Interval Used
By Hospital
Major
12 months
months
.
hours
Minor
6 months*
months
.
hours
Time Required
* Emergency and tracheal aspirators only.
Emergency, surgical, and tracheal (high-vacuum)
aspirators, 0 to 200 mm Hg
Overview
Aspirators are among the most common types of clinical
equipment in use within the hospital; some (e.g., emergency and tracheal) are critical for life support. Aspirators are categorized by their vacuum levels as follows:
Thoracic aspirators, 0 to 45 mm Hg
Low-volume aspirators, 0 to 150 mm Hg
009008
433-0595
A NONPROFIT AGENCY
Multipurpose high-vacuum aspirators, 0 mm Hg to
>400 mm Hg
Low-volume aspirators typically operate intermittently, cycling between atmosphere and 120 mm Hg. In
hospitals with central vacuum systems, suction regulators are commonly used as an alternative to aspirators.
5200 Butler Pike, Plymouth Meeting, PA 19462-1298, USA
Telephone +1 (610) 825-6000 ● Fax +1 (610) 834-1275
●
E-mail [email protected]
Inspection and Preventive Maintenance System
Suction, or aspiration, is used to remove obstructing
secretions, blood, or vomitus from a patient’s airway to
keep air passages to the lungs open and to allow
spontaneous or mechanical ventilation. Suctioning can
be either oropharyngeal (to prepare for emergency
intubation or to remove secretions from the upper
airway above the glottis) or tracheal (to remove obstructions from the trachea of an intubated patient).
In emergency medical services (EMS) use (in ambulances and in the field), portable aspirators are usually
used for oropharyngeal suctioning. However, more and
more emergency medical technicians (EMTs) and
paramedics are being trained in intubation and advanced airway maintenance in which, after suctioning,
a rescuer intubates the clear airway with an endotracheal tube. Since the cuff of that tube interferes with
the natural evacuation of mucus, tracheal aspiration
is also used to remove obstructions after intubation.
Tracheal aspiration may also be required during interhospital (nonemergency) transport of intubated patients.
Portable emergency aspirators are used by EMS
personnel outside the hospital and on bedside stands
in the hospital. They draw power for charging their
batteries from an AC line, an ambulance DC-to-AC
inverter, or the ambulance’s 12 VDC electrical system.
Data gathered during ECRI surveys of hospitals
indicate that even serious performance degradation in
suction apparatus is often not apparent to clinical
personnel. This emphasizes the need for periodic inspection. Critical performance parameters for suction
apparatus are vacuum, vacuum rise, and, in some
types, free airflow. A supply of clean catheters, suction
tips, and tubing should be stored near the aspirator or
kept readily available.
Citations from Health Devices
Suction canisters [Evaluation], 1983 Apr; 12:127-49.
Portable emergency aspirators [Evaluation], 1991 Feb;
20:55-72.
Should vacuum pump effluent be treated? [User Experience NetworkTM], 1994 Jul; 23:310.
Flowmeter, 10 to 50 L/min, ±5%
Tubing and adapters for connecting vacuum gauge
or pressure meter and flowmeter (a T fitting is
needed)
Disposable suction canister (if applicable)
Special precautions
Aspirators may be contaminated with contagious
microorganisms from contaminated aspirant. Keep
your face away from the exhaust port of the unit.
Never place your mouth on any part of the regulator to
blow or suck as a qualitative test of operation or to blow
dirt out of a part. Wash hands thoroughly after inspection, especially if any accessories were disassembled.
When it is necessary to disassemble an aspirator for
repair, wear latex gloves, wrap cellophane or another
nonpermeable barrier around the handles of all tools, and
work on a surface that can be easily disinfected. Dispose
of gloves and tool handle wrappings as infectious waste.
Procedure
Before beginning an inspection, carefully read this
procedure and the manufacturer’s instruction and service manuals; be sure that you understand how to operate the equipment and the significance of each control
and indicator. Also determine whether any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer.
It is vital to identify the type and/or application of
the aspirator to be inspected in order to define the
performance criteria for the inspection. This is often
difficult because most devices bear only a model or
catalog number. Obtain this information from the
manufacturer’s literature, previous inspection forms,
or clinical personnel. Once the type of aspirator has
been identified or when new units are purchased, enter
this information on the equipment control or inventory
record so that it can be determined quickly from the
control number on the device in future inspections.
1. Qualitative tests
1.1
Chassis/Housing. Examine the exterior of the
unit for cleanliness and general physical condition. Be sure that housings are intact, that all
assembly hardware is present and tight, and that
there are no signs of spilled liquids or other abuse.
1.2
Mount. If the device is mounted on a stand or
cart, examine the condition of the mount.
1.3
Casters/Brakes. If the device moves on casters,
check their condition. Look for accumulations of
Test apparatus and supplies
Ground resistance ohmmeter with resolution of 0.1 Ω
Leakage current meter or electrical safety analyzer
Stopwatch or watch with a second hand
Vacuum gauge, 0 to 760 mm Hg, ±3%, or pressure
meter with equivalent capabilities
2
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Aspirators
lint and thread around the casters, and be sure
that they both turn and swivel, as appropriate.
Check the operation of brakes and swivel locks,
if the unit is so equipped.
1.4
AC Plug. Examine the AC power plug for damage. Attempt to wiggle the blades to determine
that they are secure. Shake the plug and listen
for rattles that could indicate loose screws.
1.5
Line Cord. Inspect the cord for signs of damage.
If damaged, replace the entire cord or, if the
damage is near one end, cut out the defective
portion. Be sure to wire a new power cord or plug
with the same polarity as the old one. Also check
line cords of battery chargers.
1.6
Strain Reliefs. Examine the strain reliefs at
both ends of the line cord. Be sure that they hold
the cord securely.
1.7
Circuit Breaker/Fuse. If the device has a
switch-type circuit breaker, check that it moves
freely. If the device is protected by an external
fuse, check its value and type against that
marked on the chassis, and ensure that a spare
fuse is provided.
1.8
Tubes/Hoses. Check the condition of all tubing
and hoses. Be sure that they are not cracked,
kinked, or dirty. Replace if needed and indicate
this on Line 3.4 of the inspection form.
1.10 Fittings/Connectors. Examine all fittings and
connectors for general condition. Replace if
needed and indicate this on Line 3.4 of the form.
1.12 Filters. Check the condition of all liquid and
pneumatic (air) filters. Replace if needed and
indicate this on Line 3.4 of the form.
1.13 Controls/Switches. Before moving any controls,
check their positions. If any of them appear inordinate, consider the possibility of inappropriate clinical use or of incipient device failure. Record the
settings of those controls that should be returned to
their original positions following the inspection.
Examine all controls and switches for physical
condition, secure mounting, and correct motion.
Where a control should operate against fixedlimit stops, check for proper alignment, as well as
for positive stopping. Check membrane switches
for membrane damage (e.g., from fingernails,
pens). During the course of the inspection, be sure
to check that each control and switch performs its
proper function.
If the device has an adjustable suction level,
verify that the control is usable over the full range
of vacuum settings. Although generally adjustable over a much wider range, tracheal aspirators
should normally be operated at about 150 mm Hg
during tracheal aspiration. Therefore, confirm
that the unit is easily adjusted to this vacuum
level (with the patient port occluded).
1.15 Motor/Pump. Confirm physical condition and
proper operation. Lubricate if required, and
note this on Line 3.2 of the form (but do not
check 3.2 until you have completed all necessary
lubrication).
1.17 Battery/Charger. Inspect the physical condition
of batteries and battery connectors, if readily accessible. Check operation of battery-operated
power-loss alarms, if so equipped. Operate the unit
on battery power for several minutes to check that
the battery is charged and can hold a charge.
Check remaining battery capacity by activating
the battery test function or measuring the output
voltage. Check the condition of the battery charger
and, to the extent possible, confirm that it does, in
fact, charge the battery. When it is necessary to
replace a battery, label it with the date.
1.18 Indicators/Displays. During the course of the inspection, confirm the operation of all lights, indicators, meters, gauges, and visual displays on the unit
and charger if so equipped. Inspect the vacuum
gauge for cracks and scale visibility. Make sure the
indicator resets on zero without vacuum applied.
1.22 Labeling. Check that all necessary placards, labels, conversion charts, and instruction cards
are present and legible.
1.23 Accessories. Verify that clean canisters, suction
catheters, suction tips, and tubing are available.
1.24 Overflow Protection. To verify operation of the
overflow protection on units so equipped, liquid
must be aspirated into the collection bottle until
the protective device is activated. (Observe while
doing so that liquid will not be aspirated into the
pump if the mechanism fails.) Place a bucket of
water on the floor adjacent to the device being
tested, connect a short length of hose to the patient
fitting on the machine, and suction the water into
the collection bottle. In units with relatively low
flow rates (e.g., low-volume aspirators used for
gastric suction), this test is expedited by pouring
water directly into the collection bottle until it is
nearly full, then reassembling the system and
suctioning the remainder from the bucket. In
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
3
Inspection and Preventive Maintenance System
devices where overflow protection is provided by
a hollow plastic ball (e.g., a table tennis ball), the
ball will not function reliably if it is dented or
cracked or has solids adhering to it. Conduct this
test only on units with reusable suction canisters
or overflow mechanisms. Do not test completely
disposable systems.
2. Quantitative tests
2.1
Grounding Resistance. Using an ohmmeter,
electrical safety analyzer, or multimeter with
good resolution of fractional ohms, measure and
record the resistance between the grounding pin
of the power cord and exposed (unpainted and
not anodized) metal on the chassis. We recommend a maximum of 0.5 Ω.
2.2
Leakage Current. Measure chassis leakage current to ground with the grounding conductor of
plug-connected equipment temporarily opened.
Record the maximum leakage current with the
unit off and on. Leakage current should not
exceed 300 µA.
2.3
Maximum Flow. Measure the maximum free
airflow with the flowmeter and compare it with
recommended values in the table. (This measurement need not be made on low-volume suction machines, since their flows are generally
very low.) Set the unit for maximum suction.
Test the aspirator with the collection bottle(s) or
canister(s) in place, but without patient catheters. Use a short piece of large-diameter tubing
from the flowmeter to the device, with the correct
size adapters inserted at the aspirator end. Any
restrictions (e.g., internal adapters) will tend to
reduce the free airflow.
2.4
2.5
4
Rate of Vacuum Rise. This test is necessary only
on tracheal, emergency, and intrauterine aspirators, where rapid vacuum rise is essential. Connect
the vacuum gauge or pressure meter to one side of
a T fitting and attach the T to the canister or
collection bottle patient connector. Turn the unit
on and set the unit for maximum suction. Occlude
the open port of the T with a finger while using a
stopwatch or watch with a second hand to measure
the time required to reach maximum vacuum.
Refer to the Aspirator Performance Values table to
determine acceptable rise time values.
Maximum Vacuum. Connect the vacuum gauge
or pressure meter to the canister or collection
bottle patient connector. Turn on the aspirator,
adjust it to provide maximum vacuum, and record
Aspirator Performance Values
These performance values represent best current opinion on clinical
need and typical aspirator capability, not optimal design criteria. Discuss units unable to meet these criteria with clinical staff and schedule them for replacement or repair.
Type
Emergency
Low Volume
Surgical
Thoracic
Tracheal
Uterine
Breast Pump
Maximum
Vacuum
(mm Hg)
Rise Time
(sec/mm Hg)
Maximum
Free Flow
(L/min)
>400
>40
>400
>40
>400
>400
>200
<4/300
<30/30
<4/300
<4/30
<4/300
<3/300
<2/150
25
NA
25
20
25
30
NA
this value. If a unit does not provide the expected maximum vacuum (see the Aspirator Performance Values table above), look for air leaks,
especially in the collection bottle caps and hoses.
Some low-volume aspirators have “low” and
“high” settings; record the vacuum attained for
each, measuring the low level first. Thermal
intermittent aspirators (e.g., Gomco Models
764/5, 200/2000) do not reach maximum vacuum
during the first few cycles, and it is necessary to
wait 5 to 10 min until maximum vacuum is
reached.
2.6
Vacuum Gauge Accuracy. Check the accuracy of
the vacuum gauges on units so equipped at a
vacuum level typical for primary usage. To
make this measurement, connect the vacuum
gauge or pressure meter to the fitting on the
collection bottle intended for the patient catheter
or tubing. Turn the unit on and adjust it to the
desired vacuum reading on the machine’s gauge.
Record this reading and that of the test gauge or
meter. Readings should be within 10%.
3. Preventive maintenance
3.1
Clean the exterior and interior, if needed.
3.2
Lubricate the motor and pump, if needed.
3.4
Replace filter(s), hoses/tubing, fittings/connectors, if needed.
4. Acceptance tests
Conduct major inspection tests for this procedure
and the appropriate tests in the General Devices Procedure/Checklist 438.
Before Returning to Use
Recharge battery-powered devices, or equip them
with fresh batteries, if needed.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Procedure/Checklist 449-0595
Autotransfusion Units
Used For:
Autotransfusion Units, Blood Processing [17-537]
Also Called: Cell Saver (a registered trademark of Haemonetics Corp. to be used only when referring to
that device)
Commonly Used In: Operating rooms
Scope: Applies to machines used for intraoperative separation and cleaning of red blood cells recovered from
surgical sites
Risk Level: ECRI Recommended, High; Hospital Assessment,
Type
ECRI-Recommended
Interval
Major
6 months
months
.
hours
Minor
NA
months
.
hours
Overview
Autotransfusion, or autologous transfusion, is the
process of reinfusing a patient’s own blood rather than
relying on banked stores of homologous blood. Several
types of intraoperative autotransfusion devices are
available today. The simpler systems consist of collection canisters or cardiotomy reservoirs that are filled
through suction tubing originating at the operative
site. These systems generally include a means of infusing proportioned quantities of anticoagulant as
blood is aspirated, and a filtration system to remove
clotted blood and other debris that may be aspirated
with the blood. Processing systems use a centrifuge to
separate, wash, and pack the red blood cells (RBCs)
extracted from salvaged whole blood.
This procedure applies to blood processing systems
that employ a centrifuge to separate RBCs from whole
blood aspirated from the surgical site. Currently marketed units perform essentially the same procedures
in separating cells from whole blood; differences
among the units are related primarily to the degree of
machine automation. Prices of the units reflect that
degree of automation.
084750
449-0595
A NONPROFIT AGENCY
Interval Used
By Hospital
Time Required
During autotransfusion with these machines, blood
that pools in the operative site is aspirated and simultaneously mixed with an anticoagulant, then deposited
in a cardiotomy reservoir. After coarse filtration, the
blood is either pumped or drained into the spinning
centrifuge bowl. The lighter plasma separates from
the RBCs and is discarded in a waste bag. Automated
systems monitor the level of RBCs in the bowl with
optical sensors and stop the centrifuge once the cells
have filled the bowl. In manual operation, the operator
must determine when the centrifuge bowl is full and
initiate the next phase of processing, generally the
RBC wash.
During the RBC wash, cellular debris from ruptured
cells, clots, and other contaminants are removed. RBC
washing is accomplished by introducing normal saline
into the full, spinning centrifuge bowl. Because saline
is less dense than the RBCs, it disperses the cells and
rises up through them, carrying debris out and into the
waste bag. Automated systems will deliver a predetermined volume of saline during the wash phase; manual
systems require that the operator monitor the clarity
of the waste leaving the centrifuge bowl. When the
waste fluid is clear, the wash phase is terminated.
5200 Butler Pike, Plymouth Meeting, PA 19462-1298, USA
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Inspection and Preventive Maintenance System
The final stage of processing involves pumping the
packed and washed cells into an infusion bag. The
filled infusion bag is hung with an infusion line and a
microaggregate filter to reinfuse the cells into the
patient. The infusion bags are generally provided
(without infusion lines or filters) with the disposable
centrifuge bowls and tubing sets for each autotransfusion machine.
While intraoperative autologous transfusion may be
safer than donor transfusion, which carries the risk of
cross infection and transfusion reactions, autologous
transfusion is not without risk. Some rare complications currently associated with autotransfusion include air embolism, kidney dysfunction, and
disseminated intravascular coagulation. Of these complications, the latter two are thought to be related to
blood damage that occurs during the processing. Excessive centrifuge speed, overheating of the blood, and
excessive vacuum applied during aspiration can cause
RBC damage. Air embolism has generally been associated with the use of pressure infusors for reinfusion
of recovered cells or infusion occurring concurrently
with processing. Some autotransfusion machines are
equipped with air-in-line detectors that are designed
to detect air in the reinfusion line returning packed
cells to the patient. (For more details about the risks
associated with autotransfusion, refer to the Health
Devices articles cited below.)
Citations from Health Devices
Air embolism from autotransfusion units [Hazard],
1986 Jul; 15:210-2.
Automated intraoperative processing autotransfusion
machines [Evaluation], 1988 Aug; 17:219-42.
Autotransfusion machines [Evaluation update], 1988
Dec; 17:371.
Hemolysis and renal dysfunction associated with
autotransfusion, 1990 Jan; 19:25-7.
Test apparatus and supplies
Leakage current meter or electrical safety analyzer
Ground resistance ohmmeter
Leak-detect solution
Citrate solution to anticoagulate 2 L of blood, such
as 80 g sodium citrate in 200 mL normal saline or
CPD (citrate phosphate dextrose) anticoagulant solution (consult with pharmacy to determine correct
concentration)
2 L of whole, fresh pig or cow blood anticoagulated
with citrate (because of the risk of bloodborne pathogens, human blood should not be used for the procedures; animal blood may be obtained from a local
slaughterhouse)
Special precautions
Although the disposable components of the
autotransfusion machines are intended to contain
blood during processing, blood may be spilled on the
machine housing or components during processing.
When working on external components (including the
centrifuge well) and the machine housing where blood
may have been spilled, it is prudent to wear examination gloves. If a unit is contaminated with blood,
especially if the blood is still liquid, it should be decontaminated (preferably by a machine operator or central
supply personnel). Verify that the centrifuge well is
clean before working on the unit. In addition to gloves,
wear a gown and eye protection while the machine is
cleaned. (See Infection Control in the “IPM Safety”
article behind the Guidance Tab in this binder for
additional precautions and suggestions.)
Procedure
Before beginning the inspection, carefully read this
procedure and the manufacturer’s instruction and
service manuals; be sure that you understand how to
operate the equipment, the significance of each control
and indicator, and the alarm capabilities. Also, determine if any special inspection or preventive maintenance procedures or frequencies are recommended by
the manufacturer. For software-driven units, note the
software revision number on Line 1.19 (System SelfTest) of the inspection form.
1.1
Stopwatch or watch with a second hand
Bucket with capacity of at least 1 L
Set of disposables for autotransfusion unit
2
The following may be necessary during acceptance
testing:
1. Qualitative tests
1,000 mL graduated cylinder
Stroboscopic tachometer
Vacuum gauge, 0 to 600 mm Hg, or pressure meter
with equivalent capabilities
Chassis/Housing. Examine the exterior of the
unit for cleanliness and general physical condition. Be sure that plastic housings are intact,
that all hardware is present and tight, and that
there are no signs of spilled liquids or other
serious abuse. (See Special Precautions.)
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Autotransfusion Units
1.3
1.4
Casters/Brakes. If the device moves on casters,
check their condition. Verify that they turn and
swivel, as appropriate, and look for accumulations of lint and thread around the casters.
Check the operation of brakes and swivel locks,
if the unit is so equipped. Conductivity checks,
where appropriate, are usually done more efficiently as part of a check of all equipment and
furniture of an area. (See Procedure/Inspection
Form 441.)
AC Plug/Receptacles. Examine the AC power
plug for damage. Attempt to wiggle the blades
to check that they are secure. Shake the plug
and listen for rattles that could indicate loose
screws. If any damage is suspected, open the
plug and inspect it.
If the device has electrical receptacles for accessories, verify presence of line power, insert an
AC plug into each, and check that it is held firmly.
If accessories are plugged and unplugged often,
consider a full inspection of the receptacles.
1.5
Line Cord. Inspect the cord for signs of damage.
If damaged, replace the entire cord or, if the
damage is near one end, cut out the defective
portion. Be sure to wire a new power cord or plug
with correct polarity.
1.6
Strain Reliefs. Examine the strain reliefs at
both ends of the line cord. Be sure that they hold
the cord securely. If the line cord is detachable
(by the user), affix the cord to the unit so that it
cannot be removed by the operator. (See Health
Devices 1993 May-Jun; 22[5-6]:301-3.)
1.7
Circuit Breaker/Fuse. If the device has a
switch-type circuit breaker, check that it moves
freely. If the device is protected by an external
fuse, check its value and type against that
marked on the chassis and ensure that a spare
is provided.
1.8
Tubes/Hoses. Check the condition of all tubing
and hoses in the unit. Be sure that they are not
cracked, kinked, or dirty.
1.9
Cables. Inspect any cables and their strain reliefs for general condition. Carefully examine
cables to detect breaks in the insulation and to
ensure that they are gripped securely in the
connectors at each end to prevent rotation or
other strain. Verify that there are no intermittent faults by flexing electrical cables near each
end and looking for erratic operation or by using
an ohmmeter.
1.10 Fittings/Connectors. Examine all gas and liquid fittings and connectors, as well as electrical
cable connectors, for general condition. Electrical contact pins or surfaces should be straight,
clean, and bright. Verify that connections are
secure. Gas fittings should be tight and should
not leak. (If in doubt, check fittings using a
leak-detect solution.)
1.12 Filters. Check the condition of all air filters.
Clean or replace as appropriate and indicate this
on Lines 3.1 or 3.4 of the inspection form.
1.13 Controls/Switches. Before changing any controls or alarm limits, check their positions. If
any settings appear inordinate, consider the possibility of inappropriate clinical use or of incipient device failure. Record the settings of those
controls that should be returned to their original
positions following the inspection. Some units
may store modifications of standard processing
procedures in memory even when the power is
shut off; consult the operator’s manual if there is
any question about the effect of changing controls if they are not set back to their original
positions. (If in doubt, have the machine operator review settings before using the unit.)
Examine all controls and switches for physical
condition, secure mounting, and correct motion.
Check that control knobs have not slipped on
their shafts. Where a control should operate
against fixed-limit stops, check for proper alignment, as well as positive stopping. Check membrane switches for membrane damage (e.g., from
fingernails, pens). During the course of the inspection, be sure to check that each control and
switch performs its proper function.
1.15 Motor/Pump/Fan/Compressor. Check the physical condition and proper operation of these
components. Clean and lubricate as required,
and note this on Lines 3.1 and 3.2 of the inspection form. (However, do not check these items
until all necessary cleaning and lubrication is
completed.) Inspect brushes (if present) of
pump, centrifuge, and compressor motors for
wear. If worn, replace. If drive belts are present,
check them for wear and replace if needed.
1.18 Indicators/Displays. During the course of the
inspection, confirm the operation of all lights,
indicators, meters, gauges, and visual displays
on the unit and charger (if so equipped). Be sure
that all segments of a digital display function
(see Item 1.19).
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
3
Inspection and Preventive Maintenance System
Using the disposable autotransfusion set (or
tubing of the same size and hardness), verify that
the clamp valves work by installing the tubing
in the valves so that at least 3 ft of tubing is
available on one side of the valve. With the 3 ft
section of tubing held in a vertical position and
the clamp valve closed, fill the tubing with water
to verify that water will not leak through the
valve.
1.19 System Self-Test. Many automated autotransfusion units have a software-based self-check feature that performs several diagnostic tests when
the machine is powered up. Record the software
version on the inspection form when the program
is started. Verification of proper display and
indicator function may also be checked during the
self-check.
1.20 Alarms. Autotransfusion machines may have
alarms, depending on the degree of automation
of the unit. Some alarm conditions that should
be checked (where appropriate) include full
waste bag, empty wash reservoir, and open centrifuge cover. Induce alarm conditions to activate
audible and visual alarms. Full waste bag
alarms (present on some units) may be triggered
by the weight of the bag or by the system’s
volume-accounting system, which keeps track of
how much fluid has been pumped into the waste
bag. Empty reservoir alarms are typically triggered when the air-in-line detector senses that
no fluid is in the line during the washing phase
of processing. (Testing this alarm will also verify
that the air-in-line detector is functioning.)
Some autotransfusion machines may have centrifuge-cover interlocks that prevent the opening
of the cover while the centrifuge is spinning; they
may not alarm to warn that the cover is open.
Consult the operator’s manual or the manufacturer to determine if the unit being tested has an
alarm to detect an open centrifuge cover. (None
of the tests in this section will require blood;
water or saline may be used if fluid is required.)
Next, trigger the valve to open by operating
the unit (consult manufacturer if it is not clear
how to trigger valves to open). If clamps do not
open or open sluggishly, consult the service manual or have the manufacturer repair or clean the
valve.
1.25 Centrifuge Chuck. Inspect centrifuge chuck for
wear or damage. Inspect entire centrifuge well
for presence of debris. Install a centrifuge bowl
in the chuck according to the operator’s manual,
verify that the bowl is firmly seated and that,
when the centrifuge is spinning, the bowl remains fairly quiet. If the chuck employs O-rings
to secure the bowl, inspect the O-rings for wear
or nicks; replace as necessary.
2. Quantitative tests
2.1
1.21 Audible Signals. Operate the device to activate
any audible signals. Confirm appropriate volume, as well as the operation of a volume control,
if so equipped. If audible alarms have been silenced or the volume set too low, alert clinical
staff to the importance of keeping alarms at the
appropriate level.
1.22 Labeling. Check that all necessary placards, labels, conversion charts, and instruction cards
are present and legible.
Grounding Resistance. Using an ohmmeter,
electrical safety analyzer, or multimeter with
good resolution of fractional ohms, measure and
record the resistance between the grounding pin
of the power cord and exposed (unpainted and
not anodized) metal on the chassis. We recommend a maximum of 0.5 Ω. If the system is
modular or composed of separate components,
verify grounding of the mainframe and each
module or component. If the device is double
insulated, grounding resistance need not be
measured; indicate “DI” instead of the ground
resistance value.
If the device has an accessory receptacle,
check its grounding to the main power cord.
1.23 Accessories. Confirm the presence and condition
of accessories, such as tools, separate air-in-line
sensors, and cardiotomy reservoir clamps.
Leakage Current. Measure chassis leakage current to ground with the grounding conductor of
plug-connected equipment temporarily opened.
Operate the device in all normal modes, including on, standby, and off, and record the maximum leakage current.
1.24 Clamp Valves. Inspect clamp valves on each
unit, if so equipped, to determine if they are clean
and in good condition. If material has accumulated on the clamps, clean as needed.
Measure chassis leakage current with all accessories normally powered from the same line
cord connected and turned on and off. This includes other equipment that is plugged into the
4
2.2
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Autotransfusion Units
2.3
primary device’s accessory receptacles, as well as
equipment plugged into a multiple-strip outlet
(“Waber strip”), so that all are grounded through
a single line or extension cord.
3.2
Lubricate per manufacturer’s instructions.
3.4
Replace motor brushes, drive belts, and centrifuge bowl O-rings, as appropriate.
Chassis leakage current to ground should not
exceed 300 µA.
4. Acceptance tests
Roller Pumps. Check the rollers on pumps to
make sure that they are running smoothly and
that there are no unusual noises from bearings
or other indications of excessive bearing wear.
Using tubing of the correct size and hardness
in the pump, immerse both ends of the tubing in
a bucket of saline solution or water at atmospheric pressure and turn on the pump. (This
may require triggering of some sensors for the
more automated units; contact the manufacturer
if it is not clear how to get the pump to run.) To
check pump accuracy, set it to deliver 500 and
1,000 mL/min, and collect the volume for a convenient time interval in a calibrated 1,000 mL
graduated cylinder. Flows should be accurate to
within 5% of the setting or the manufacturer’s
specifications.
2.4
2.5
Vacuum Pump. Check the accuracy of vacuum
pump regulation on units equipped with vacuum
pumps by connecting a length of tubing to the
vacuum port and to a vacuum gauge. Vacuum
levels should be within 50 mm Hg of the displayed value at full vacuum.
Centrifuge Speed. Measure centrifuge speed
with a stroboscope tachometer illuminating the
centrifuge bowl chuck while the centrifuge is
spinning. A piece of tape may be applied to the
chuck to facilitate speed determination. Centrifuge speed should be within 10% of the specified
speed or within the range specified by the manufacturer. If centrifuge speed is outside of acceptable specification, contact the manufacturer to
inquire about adjustment.
3. Preventive maintenance
3.1
Clean exterior and clamps, as needed.
Conduct major inspection tests for this procedure
and the appropriate tests in the General Devices Procedure/Checklist 438. In addition, consider performing the following test.
4.1
Cycle Function. If a manufacturer-recommended procedure is available, verify that the
blood-level detection system (in automated
units) and the rest of the autotransfusion unit
functions properly through one or more complete
cycles. For the manufacturer-recommended test
protocol, contact your representative. If the
manufacturer does not provide a way to perform
this test, use pig or cow blood to confirm complete
functioning; other solutions will not activate sensors. Since there is no history of problems reported for new units, testing with animal blood
is optional. If the autotransfusion machine is
new to your clinical staff, and you will be testing
with blood, consider including this testing as
part of in-service instruction.
To test with animal blood, install the disposable components, then suction fresh citrated
blood into the collection reservoir. Blood should
be collected in a solution of 8 g of sodium citrate
dissolved in 200 mL of normal saline for every 2
L of blood required. Generally, 2 L of blood is
more than adequate for testing. Operate the unit
according to the operator’s manual, verifying that
the system will detect the packed RBC level.
Before returning to use
Make sure that all controls are set properly. Set
alarms loud enough to alert personnel in the area in
which the device will be used. Other controls should
be in their normal pre-use positions.
Attach a Caution tag in a prominent position to alert
users that control settings may have been changed.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
5
Procedure/Checklist 402-0595
Beds, Electric
Used For:
Beds, Air-Fluidized [16-889]
Beds, Birthing [15-732]
Beds, Circle Electric [10-345]
Beds, Electric [10-347]
Beds, Electric, Obese [15-760]
Beds, Flotation Therapy [10-348]
Beds, Low-Air-Loss [17-593]
Beds, Rocking [10-363]
Beds, Tilt [16-991]
Tables, Examination/Treatment [13-958]
Commonly Used In: Most patient care areas
Scope: Applies to electrically operated patient beds, treatment tables (not including OR tables), flotation
therapy beds, turning frames, and a variety of specialty electric beds designed for prevention or treatment
of pressure sores (decubitus ulcers) or burns, with additional tests for special features of these units
Risk Level: ECRI Recommended, Low for most Electric Beds, Medium for Special Care Beds; Hospital
Assessment,
for most Electric Beds,
for Special Care Beds
Type
ECRI-Recommended
Interval
Interval Used
By Hospital
Major
12 months
months
.
hours
Minor
NA*
months
.
hours
Time Required
* Special care beds — including rocking beds (also called kinetic treatment tables), turning frames, circle beds,
and air-fluidized and low-air-loss flotation therapy beds — should receive a minor inspection at least every six
months, in addition to the annual major inspection (see Health Devices 1988 Jan; 17:3).
Overview
Electrically operated beds are in widespread use in
most hospitals. Properly used and maintained, they
can provide long service, save much nursing staff time,
and afford the patient comfort and convenience.
Periodic inspection of electric beds is necessary,
primarily because of their potential electrical risks.
Electric motors tend to have leakage currents that
increase with age and use, and the line cord, plugs, and
control units on beds are often subject to abuse by
patients and personnel. Periodic inspection of all beds,
nonelectric as well as electric, can often detect impending failures at a stage where correction is relatively
009032
402-0595
A NONPROFIT AGENCY
simple (e.g., bed rails can be checked and repaired
before they fail to restrain a patient; a missing IV pole
can be replaced before it is urgently needed).
Inspection of electric beds must be correlated with
bed occupancy and coordinated with nursing personnel
or the admissions office. If a bed is occupied at the time
its inspection is due and the patient cannot leave the
bed for the few minutes required for the inspection,
request that the floor nurse advise the maintenance
department when the inspection can be performed.
In most hospitals, responsibility for inspection and
preventive maintenance of electric beds rests with the
plant or facilities engineering department, rather than
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Inspection and Preventive Maintenance System
with clinical engineering. However, because these beds
are also medical devices, it is important that the documentation of their inspection be thorough and consistent with that of the clinical engineering department.
(e.g., walkaway down) that could result in potentially
serious crushing injuries.
Citations from Health Devices
Before beginning an inspection, carefully read this
procedure and the manufacturer’s instruction and
service manuals; be sure that you understand how to
operate the equipment and the significance of each
control and indicator. Also determine whether any
special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer.
Electrical safety of electrical beds, 1978 Apr-May;
7:152-3.
Water mattresses on electric beds [Consultant’s Corner], 1978 Sep; 7:290.
Electric beds in pediatric areas [Consultant’s Corner],
1982 Sep; 11:302.
Procedure
Electric beds — A status report, 1983 May; 12:177.
1. Qualitative tests
Electric beds and the pediatric patient [Hazard], 1983
Jun; 12:203-7.
1.1
Frame. Examine the bed frame for cleanliness
and general physical condition. Be sure that all
assembly hardware is present and tight. Verify
smooth and secure operation of siderails. Check
mechanical integrity and degradation (weld
cracks, loose fasteners, caster security, stripped
threads), especially on special care beds.
1.3
Casters/Brakes. If the bed moves on casters,
check their condition. Look for accumulations of
lint and thread around the casters, and be sure
that they turn and swivel, as appropriate. Check
the operation of brakes and swivel locks, if the
bed is so equipped.
1.4
AC Plug. Electric bed plugs are especially subject to physical abuse. Therefore, carefully examine the plug and use Hospital Grade plugs on
all electric beds. Examine the AC power plug for
damage. Attempt to wiggle the blades to determine that they are secure. Shake the plug and
listen for rattles that could indicate loose screws.
If any damage is suspected, open the plug and
inspect it.
1.5
Line Cord. Inspect the cord for signs of damage.
If damaged, replace the entire cord or, if the
damage is near one end, cut out the defective
portion. Be sure to wire a new power cord or plug
with the same polarity as the old one.
1.6
Strain Reliefs. Examine the strain reliefs at
both ends of the line cord. Be sure that they hold
the cord securely.
1.7
Circuit Breaker/Fuse. If the unit has a switchtype circuit breaker, check that it moves freely.
If the device is protected by an external fuse,
check its value and type against that marked on
the chassis, and ensure that a spare is provided.
Hill-Rom electric beds [User Experience NetworkTM],
1986 Jun; 15:177.
Electric beds [Evaluation], 1986 Nov; 15:299-316. (See
also Erratum, 1987 Jan; 16:33.)
Amedco electric hospital beds [Hazard], 1986 Nov;
15:317-8.
Electric beds can kill children [Hazard update], 1987
Mar-Apr; 16:109-10.
Electrical safety of electric beds [User Experience NetworkTM], 1987 Mar-Apr; 16:118.
Special care beds require special attention [Hazard],
1988 Mar; 17:101-2.
Electric beds can kill children [Hazard update], 1989
Sep; 18:323-5.
Electric beds: Do not use in psychiatric wards [Hazard], 1991 Dec; 19:495-6.
Test apparatus and supplies
Leakage current meter or electrical safety analyzer
Ground resistance ohmmeter
Lubricants (20-weight low-detergent oil, graphited
oil, grease)
Special precautions
Keep fingers and clothing away from all moving
parts during inspection. Perform parts inspection,
cleaning, and lubrication with the power cord unplugged. Never get underneath a bed while the controls are being operated. Some controls will cause
continued motion even after the switch is released
2
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Beds, Electric
1.9
turer that they meet the requirements for protection against tampering set forth in UL 544,
Section 23C4. For older beds, check with the
manufacturer to determine the modification procedure to disable the feature. This recommendation is based on incidents in which children have
been fatally crushed (see Health Devices, 1987
Mar-Apr; 16:109-10 and 1989 Sep; 18:323-5).
Walkaway down capability can be included on
four-poster beds.
Cables. Inspect the cables (e.g., pendants, interconnecting) and their strain reliefs for general
condition. Examine cables carefully to detect
breaks in the insulation and to ensure that they
are gripped securely in the connectors of each
end to prevent rotation or other strain.
1.10 Fittings/Connectors. Examine all electrical cable connectors for general condition, as well as
all gas and liquid fittings and connectors, if present (e.g., in special care beds). Electrical contact
pins or surfaces should be straight, clean, and
bright.
1.13 Controls/Switches. Before moving any controls,
check their positions. Examine all controls and
switches, both patient and nurse actuated, for
physical condition, secure mounting, and correct
motion. Check membrane switches for membrane damage (e.g., from fingernails or pens).
1.15 Motors/Mechanisms. Inspect for general cleanliness, condition, and freedom from accumulated
dirt and lint. Follow manufacturer’s recommendations for lubrication (but do not check Line 3.2
on the inspection form until all necessary lubrication has been completed).
1.22 Labeling. Check that all necessary placards, labels, and instruction cards are present and legible.
1.23 Accessories. Note the general condition of the
bed and mattress. If the bed should be equipped
with an IV pole or a manual handcrank (e.g.,
stored behind the headboard), verify its presence
and condition. The IV pole’s elevating latch or
thumbscrew should function easily. Inspect IV
sockets for cleanliness, alignment, and mechanical integrity.
1.24 Function and Limits of Nurse Controls/Lockouts. Operate each of the controls in both directions to the full extent of its limits. Note any
unusual sounds or other deviations from normal
performance of the controls themselves, the motors, or the limits. Verify operation of patient
lockout switches.
Pedestal-style electric beds should not have a
walkaway down feature unless the bed has ULlisted controls. The bed should descend only as
long as the down button is pressed; motion
should stop as soon as the button is released.
This applies to all areas of the hospital. If in
doubt about new beds, verify with the manufac-
1.25 Function and Limits of Patient Controls. Operate each of the controls in both directions to the
full extent of its limits. Note any unusual sounds
or other deviations from normal performance of
the controls themselves, the motors, or the limits.
2. Quantitative tests
2.1
Grounding Resistance. Using an ohmmeter,
electrical safety analyzer, or multimeter with
good resolution of fractional ohms, measure and
record the resistance between the grounding pin
of the power cord and exposed (unpainted and
not anodized) metal on the chassis. We recommend a maximum of 0.5 Ω.
2.2
Leakage Current. Measure chassis leakage current to the chassis of the unit with the grounding
conductor of plug-connected equipment temporarily opened. Operate the device in all normal
modes, including on, standby, and off, and record
the maximum leakage current. Leakage current
from the bed frame should not exceed 300 µA.
This limit applies whether the bed is used in a
general or special care area.
2.3
Supplemental Tests. Check any special features
of the particular model for condition and operation.
3. Preventive maintenance
3.1
Clean the exterior and interior (e.g., motors,
mechanisms).
3.2
Lubricate motors, mechanisms.
4. Acceptance tests
Conduct major inspection tests for this procedure
and the appropriate tests in the General Devices Procedure/Checklist 438.
Before returning to use
Place the bed in its lowest position.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
3
Procedure/Checklist 454-0595
Blood Pressure Monitors, Electronic Indirect
Used For:
Sphygmomanometers, Electronic [16-157]
Sphygmomanometers, Electronic, Automatic [16-173]
Sphygmomanometers, Electronic, Manual [16-174]
Also Called: Noninvasive blood pressure (NIBP) units
Commonly Used In: All patient care areas
Scope: Applies to electronic noninvasive blood pressure monitors with either automatic or manual inflation;
does not include manual sphygmomanometers (see Procedure/Checklist 424) or invasive blood pressure
monitors or transducers (see Procedure/Checklist 434 or 435, respectively); can be used on physiologic
monitoring systems and vital signs monitors that include NIBP measurement
Risk Level: ECRI Recommended, Medium; Hospital Assessment,
Type
ECRI-Recommended
Interval
Major
12 months
months
.
hours
Minor
NA
months
.
hours
Overview
Electronic sphygmomanometers noninvasively measure and display a patient’s arterial blood pressure.
The use of these devices may help to overcome some of
the problems associated with manual sphygmomanometry, such as variations in user techniques and
hearing acuity and the difficulty of obtaining measurements on hypotensive patients. In addition, many
automatic blood pressure units can be programmed for
readings at regular intervals and will sound an alarm
if a patient’s blood pressure exceeds preset limits.
Some units can display heart rates based on the blood
pressure waveform.
Arterial blood pressure measurement is an essential indicator of physiologic condition. As one of the
most frequently used diagnostic tests, it is critical to
the ongoing management of patients under anesthesia
or undergoing drug and other therapies to determine
the need for blood, a volume substitute (e.g., plasma
expander), or a change in medication. Although invasive techniques for measuring blood pressure may
084753
454-0595
A NONPROFIT AGENCY
Interval Used
By Hospital
Time Required
provide greater accuracy and permit continuous measurement during cardiac and respiratory cycles, noninvasive techniques are most often used because of their
low risk and simplicity, and they have proven sufficiently accurate for many clinical applications.
Two primary methods of determining blood pressure are used with noninvasive electronic blood pressure monitors. The auscultatory method uses a
transducer under the occluding cuff to detect arterial
sounds (Korotkoff sounds) as cuff pressure is gradually
lowered from above the systolic pressure. This enables
the system to directly determine both systolic and
diastolic values but not mean arterial pressure (MAP).
Some of these units display a MAP that is calculated
from the systolic and diastolic values using an empirically derived algorithm. Hypotensive patients and
patients about to go into shock can be very difficult to
monitor with this method because the Korotkoff
sounds are difficult to detect at low pressures.
The oscillometric method of determining arterial
blood pressure does not require a transducer under the
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Inspection and Preventive Maintenance System
occluding cuff and is the most common method used.
This method detects volume displacements that originate within the artery (as cuff pressure is reduced) and
that are sensed as pressure oscillations in the occluding cuff. The point of maximal oscillation corresponds
to the MAP. Systolic and diastolic pressures may be
determined by special measurement techniques or
clinically tested algorithms. This method may be more
reliable than auscultation on hypotensive patients and
patients who are likely to become hypotensive.
Physiologic monitoring and the standard of care, 1991
Mar-Apr; 20:79-80.
A third method, the differential sensor technique, is
a composite of the two techniques described above.
This method typically uses a dual-head sensor that is
located under the occluding cuff. One side of the sensor
is positioned above the artery and detects the signal
generated by the Korotkoff sounds and the oscillometric pressure wave. The opposite side of the transducer
detects only the oscillometric signal. By subtracting
these two signals, this method filters out extraneous
signals from the Korotkoff sounds, isolating the signal
that identifies the systolic and diastolic pressures.
The oscillometric method is used to measure MAP,
even when Korotkoff sounds may be too weak to measure systolic and diastolic pressures.
Y connector compatible with cuff tubing connectors
There are several oscillometric NIBP simulators on
the market, costing approximately $4,000 to $5,000.
These devices attempt to simulate the dynamic signals
that the occlusive cuff would sense if placed on a patient’s
arm. The devices also have a test mode that can provide
an easier means of performing the static accuracy test,
leak test, and overpressure test. If the simulator does not
use the NIBP monitor’s patient cuff (i.e., the simulator
has an internal bladder), then the leak test will need to
be repeated with the patient cuff in place.
Simulators also provide a means of evaluating the
dynamic performance of the NIBP monitor. However,
while they are useful in looking at long-term trends of
device performance, they are not necessarily useful in
evaluating device accuracy. Since NIBP monitors calculate their readings based on an algorithm, and the simulators use a similar algorithm to generate their signals,
if the two algorithms are not exactly matched, then what
the simulator states the pressure should be may differ
from the pressure that the monitor indicates. It is also
necessary to take several readings at each setting and
average them; this average, over time, should remain
constant for each individual NIBP monitor.
Physiologic patient monitors [Evaluation], 1991 MarApr; 20:81-136.
Test apparatus and supplies
Leakage current meter or electrical safety analyzer
Ground resistance ohmmeter
Calibrated pressure gauge or meter (0 to 300 mm Hg)
Cylindrical object to simulate an arm (e.g., can or
pipe) with a 3 in to 4 in outer diameter
Stopwatch or watch with a second hand
NIBP simulator
Procedure
Before beginning an inspection, carefully read this
procedure and the manufacturer’s instruction and
service manuals; be sure that you understand how to
operate the equipment, the significance of each control
and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive
maintenance procedures or frequencies are recommended by the manufacturer.
1. Qualitative tests
1.1
Chassis/Housing. Examine the exterior of the
unit for cleanliness and general physical condition.
Be sure that plastic housings are intact, that all
hardware is present and tight, and that there are
no signs of spilled liquids or other serious abuse.
1.2
Mount/Fasteners. If the device is mounted on a
stand or cart, examine the condition of the
mount. If it is attached to a wall or rests on a
shelf, check the security of this attachment.
1.3
Casters/Brakes. If the device is mounted on a
cart or stand, check the condition of its casters.
Verify that they turn and swivel, as appropriate,
and look for accumulations of lint and thread
around the casters. Check the operation of brakes
and swivel locks, if the unit is so equipped.
1.4
AC Plug. Examine the AC power plug for damage.
Attempt to wiggle the blades to check that they are
secure. Shake the plug and listen for rattles that
could indicate loose screws. If any damage is suspected, open the plug and inspect it.
1.5
Line Cord. Inspect the cord for signs of damage.
If damaged, replace the entire cord or, if the
damage is near one end, cut out the defective
Citations from Health Devices
Automatic sphygmomanometers [Evaluation], 1986
Jul; 15:187-208. (See also 1986 Aug; 15:247 and
1986 Nov; 15:317.)
2
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Blood Pressure Monitors, Electronic Indirect
portion. Be sure to wire a new power cord or plug
with correct polarity. Also check line cords of
battery chargers.
1.6
Strain Reliefs. Examine the strain reliefs at
both ends of the line cord. Be sure that they hold
the cord securely.
1.7
Circuit Breaker/Fuse. If the device has a switchtype circuit breaker, check that it moves freely. If
the device is protected by an external fuse, check
its value and type against that marked on the
chassis and ensure that a spare is provided.
1.8
Tubes/Hoses/Bulbs. Check the condition of all
tubing, all hoses, the cuff, and the bulb (if present). Be sure that they are not cracked, kinked,
or dirty. Replace loose or cracked tubing.
1.10 Fittings/Connectors. Examine all fittings and
connectors for general condition. Fittings
should be tight (or within manufacturer’s specifications) and should not leak. If keyed connectors are used, make sure that the keying is
correct.
1.11 Transducers (non-oscillometric units). Confirm
that any necessary transducers are on hand and
check their physical condition.
1.13 Controls/Switches. Before changing any controls or alarm limits, check their positions. If
any settings appear inordinate (e.g., alarm limits
at the ends of their range), consider the possibility of inappropriate clinical use or incipient device failure. Record the settings of those controls
that should be returned to their original positions following the inspection.
Examine all controls and switches for physical
condition, secure mounting, and correct motion.
Check that control knobs have not slipped on
their shafts. Where a control should operate
against fixed-limit stops, check for proper alignment, as well as positive stopping. Check membrane switches for membrane damage (e.g., from
fingernails, pens). During the course of the inspection, be sure to check that each control and
switch performs its proper function.
1.15 Pump. Check the physical condition and proper
operation of this component.
1.17 Battery. Inspect the physical condition of batteries and battery connectors, if readily accessible.
Check operation of battery-operated power-loss
alarms, if so equipped. Operate the unit on battery power for several minutes to check that the
battery is charged and can hold a charge. (The
inspection can be carried out on battery power to
help confirm adequate battery capacity.) Check
battery condition by activating the battery test
function or measuring the output voltage. Confirm the operation of a charging indicator. Be
sure that the battery is recharged or charging
when the inspection is complete. If it is necessary
to replace a battery, label it with the date.
1.18 Indicators/Displays. During the course of the
inspection, confirm the operation of all lights,
indicators, meters, gauges, and visual displays
on the unit. Be sure that all segments of a digital
display function.
1.19 User Calibration. Verify that the calibration
function operates.
1.20 Alarms. Induce alarm conditions to activate
audible and visual alarms. Check that any associated interlocks (e.g., auto deflate) function. If
the unit has an alarm-silence feature, check the
method of reset (i.e., manual or automatic)
against the manufacturer’s specifications. It
may not be possible to check out all alarms at
this time, since some may require abnormal operating conditions that will be simulated later in
this procedure.
1.21 Audible Signals. Operate the device to activate
any audible signals. Confirm appropriate volume, as well as the operation of a volume control,
if so equipped. If audible alarms have been silenced or the volume set too low, alert clinical
staff to the importance of keeping alarms at the
appropriate level.
1.22 Labeling. Check that all necessary placards, labels, conversion charts, and instruction cards
are present and legible.
1.23 Accessories. Use of an improperly sized cuff can
cause significant errors in measuring blood pressure. Clinical personnel should be instructed
never to substitute an improper cuff. Verify that
appropriate cuff sizes either are stored with the
unit or are readily available (e.g., at a nearby
nursing station). These should correspond to
physical characteristics of the patients on whom
the instrument is likely to be used (e.g., smaller
cuffs in a pediatric area).
All cuffs should be clean and in good condition
with no torn stitching. Look for signs of degradation or cracking of the bladder. Check that
Velcro closures hold firmly.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
3
Inspection and Preventive Maintenance System
If the unit has a printer/recorder, check to see
that it operates when it is supposed to, that the
paper folds smoothly, and that the printout is
accurate and legible.
1.24 Deflation Switch. Confirm the operation of the
control that enables manual deflation.
1.25 Operation on Volunteer. Apply the cuff to yourself or a volunteer, activate the unit, and verify
that it cycles through the measurement correctly. Perform Item 2.4 at the same time (for
major inspection).
2. Quantitative tests
2.1
2.2
Grounding Resistance. Using an ohmmeter,
electrical safety analyzer, or multimeter with
good resolution of fractional ohms, measure and
record the resistance between the grounding pin
of the power cord and exposed (unpainted and
not anodized) metal on the chassis. We recommend a maximum of 0.5 Ω. If the system is
modular or composed of separate components,
verify grounding of the mainframe and each
module or component. If the device is double
insulated, grounding resistance need not be
measured; indicate “DI” instead of the ground
resistance value.
Leakage Current. Measure chassis leakage current to ground with the grounding conductor of
plug-connected equipment temporarily opened.
Operate the device in all normal modes, including on, standby, and off, and record the maximum leakage current.
Chassis leakage current to ground should not
exceed 300 µA.
2.3
Air Leakage. Wrap the cuff around a simulated
limb. Inflate the cuff (use the calibration function) to about the maximum scale indication.
Read the indicator after 1 min to determine the
rate of pressure loss in mm Hg/min. This rate
should not exceed 15 mm Hg/min. If it does,
recheck all fittings and repeat the test.
If a unit does not allow testing this way, an
alternative leakage measurement can be used.
Wrap the cuff around a simulated limb. Connect
the blood pressure set to a calibrated gauge or
meter as shown in Figure 1. The deflation rate
should be 2 to 6 mm Hg/sec, unless the device has
an algorithm that interpolates the reading between pulses. If the rate is faster, check all
fittings and repeat the test.
4
Figure 1. Test setup.
2.4
Heart Rate. Connect the cuff to yourself or a
volunteer. Displayed heart rate should correspond to manually palpated rate within 10%.
2.10 Pressure Accuracy. Connect the blood pressure
set to a pressure gauge or meter as shown in
Figure 1. Inflate the system to around 200 mm
Hg with either the squeeze bulb or the unit’s
calibration mode. The readings on the unit and
the standard gauge should not differ by more
than 3 mm Hg. Repeat the test for a pressure
around 120 mm Hg and 80 mm Hg.
3. Preventive maintenance
3.1
Clean as needed.
3.2
Lubricate per manufacturer’s instructions.
3.3
Calibrate per manufacturer’s instructions.
3.4
Replace tubing, hoses, connectors, cuffs, and batteries if needed.
4. Acceptance tests
Conduct major inspection tests for this procedure
and the appropriate tests in the General Devices Procedure/Checklist 438. In addition, perform the following test.
4.1
Accuracy on Volunteer. Check the unit’s performance by comparing measurements made by
a nurse to the blood pressure readings with the
unit. The nurse’s reading and the unit’s reading
should not differ by more than 10% mm Hg.
Differences in readings may be due to technique,
cuff location (i.e., right or left arm), and time (if not
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Blood Pressure Monitors, Electronic Indirect
taken simultaneously). If significant differences
are obtained on repetitive tries, consider having
another qualified person obtain the manual
reading before contacting the manufacturer.
4.2
Auto Deflate Function. Using the simulated
limb setup in Figure 1, inflate the cuff to the
point of auto deflation activation. It should deflate at a point no higher than 330 mm Hg.
Before returning to use
Make sure that all controls are set properly. Set
alarms loud enough to alert personnel in the area in
which the device will be used. Other controls should
be in their normal pre-use positions.
Recharge battery-powered devices or equip with
fresh batteries if needed.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
5
Procedure/Checklist 434-0595
Blood Pressure Monitors, Invasive
Used For:
Pressure Monitors, Blood, General/Invasive [16-764]
Manometer Sets, Venous, Central/Peripheral [10-776]
Commonly Used In: Special care units, emergency department, operating rooms, cardiac catheterization
laboratories; often included as a component of physiological monitoring systems
Scope: Applies to invasive blood pressure monitors and is adaptable to other physiologic pressure monitors
(e.g., uterine pressure monitors used in conjunction with fetal heart monitors) that use the same measurement
principles; does not apply to noninvasive, indirect manual blood pressure measuring units (see Procedure/Checklist 424) or electronic indirect blood pressure monitors (see Procedure/Checklist 454); blood
pressure transducers are covered in Procedure/Checklist 435
Risk Level: ECRI Recommended, High; Hospital Assessment,
ECRI-Recommended
Type Interval
Interval Used
By Hospital
Time Required
Major
12 months
months
.
hours
Minor
NA
months
.
hours
Electrical isolation of blood pressure channels [User
Experience NetworkTM], 1986 Dec; 15:331.
Overview
Monitoring blood pressure in addition to the ECG
provides a more comprehensive view of cardiovascular
status than the ECG alone can provide. However,
invasive blood pressure monitoring requires more skill
and involves greater risk. Blood pressure monitors are
used to monitor systolic, diastolic, or mean arterial
pressures, central venous pressures, and pulmonary
artery wedge pressures.
Citations from Health Devices
Blood pressure readings — Cuff versus monitor [Consultant’s Corner], 1977 Jul; 6:236.
Air embolism during calibration of invasive blood pressure monitoring systems [Hazard], 1982 Nov; 12:22-5.
Alternative in-use calibration techniques, 1982 Nov;
12:24.
Patient monitoring systems [Evaluation], 1985 MarApr; 14:143.
009009
434-0595
A NONPROFIT AGENCY
Test apparatus and supplies
Leakage current meter or electrical safety analyzer
Ground resistance ohmmeter
Transducer simulator
Transducer connector (without transducer attached) or small-diameter probe for leakage current
meter to gain access to terminals on monitor (acceptance testing only)
Procedure
Before beginning the inspection, carefully read this
procedure and the manufacturer’s instruction and
service manuals; be sure you understand how to operate the equipment, the significance of each control and
indicator, and the alarm capabilities. Also determine
whether any special inspection and preventive maintenance procedures or frequencies are recommended
by the manufacturer.
5200 Butler Pike, Plymouth Meeting, PA 19462-1298, USA
Telephone +1 (610) 825-6000 ● Fax +1 (610) 834-1275
●
E-mail [email protected]
Inspection and Preventive Maintenance System
This procedure is applicable to a stand-alone blood
pressure monitor or a pressure module or a section of a
multiple-parameter physiologic patient monitor. You
need not perform Items 1.2 through 1.7 each time a
different monitoring function of a multiple parameter
monitor is inspected; these tests are usually performed
during the ECG Monitors inspection (see Procedure/Checklist 409) and are recorded on that form.
For efficiency, test all the monitors in one area with a
transducer simulator (these devices were evaluated in
Health Devices 1980 Jan; 9:59) or one transducer that is
known to be accurate; then test all the transducers in
that area (see Procedure/Checklist 435) using one monitor.
When filling in the identifying information at the
top of the form, include the control or serial number of
the transducer used to test the monitor (unless a
simulator is used).
Testing the accuracy of blood pressure monitors
and transducers presents a practical problem. Clinical requirements for blood pressure measurements
call for an accuracy of ±5% for arterial pressure ranges
and ±2 mm Hg for venous or pulmonary pressure
measurements. Since the criteria apply to the measurement system, both the monitor and the transducer
must be more accurate than this. Therefore, we recommend using a pressure simulator for testing pressure monitors. The simulator can be used to test
monitor accuracy alone, without the need to maintain
a well-calibrated pressure transducer. Moreover, the
cost of a basic static pressure simulator is less than
the cost of a pressure transducer. Also, a transducer
alone cannot be used to establish the accuracy of the
monitor. As long as the transducer-monitor combination is accurate to within 5% or ±2 mm Hg of a given
static pressure, the monitor and transducer can be
considered acceptably accurate. We have found that
most pressure monitor and transducer problems result in either complete failure of the unit or relatively
large errors.
1. Qualitative tests
1.1
1.2
2
Chassis/Housing. Examine the exterior of the
unit for cleanliness and general physical condition. Be sure that plastic housings are intact,
that necessary assembly hardware is present
and tight, and that there are no signs of spilled
liquids or other serious abuse.
Mount. If the device is mounted on a stand or
cart, examine the condition of the mount. If it is
attached to a wall or rests on a shelf, check the
security of this attachment.
1.4
AC Plug. Examine the AC power plug for damage.
Attempt to wiggle the blades to determine that
they are secure. Shake the plug and listen for
rattles that could indicate loose screws. If any
damage is suspected, open the plug and inspect it.
1.5
Line Cord. Inspect the cord for signs of damage.
If damaged, replace the entire cord or, if the
damage is near one end, cut out the defective
portion. Be sure to wire a new power cord or plug
with the same polarity as the old one.
1.6
Strain Reliefs. Examine the strain reliefs at
both ends of the line cord. Be sure that they hold
the cord securely.
1.7
Circuit Breaker/Fuse. If the device has a switchtype circuit breaker, check that it moves freely.
If the device is protected by an external fuse,
check its value and type against that marked on
the chassis, and ensure that a spare is provided.
1.9
Cables. Inspect the cables (e.g., reusable cables
for disposable transducers) and their strain reliefs for general condition. Examine cables carefully to detect breaks in the insulation and to
ensure that they are gripped securely in the
connectors of each end to prevent rotation or
other strain.
1.10 Fittings/Connectors. Verify that the connector
for the transducer cable is secure, clean, and lacks
any signs of damage (e.g., cracks, bent connector
pins, excessively worn pin receptacles).
1.11 Transducers. If they are normally stored with
the unit, confirm that transducers are on hand,
and check their physical condition.
1.13 Controls/Switches. Before moving any controls
and alarm limits, check their positions. If any of
them appear inordinate (e.g., a gain control at
maximum, alarm limits at the ends of their range),
consider the possibility of inappropriate clinical
use or of incipient device failure. Record the settings of those controls that should be returned to
their original positions following the inspection.
Examine all controls and switches for physical
condition, secure mounting, and correct motion.
Where a control should operate against fixedlimit stops, check for proper alignment, as well
as positive stopping. Check membrane switches
for membrane damage (e.g., from fingernails,
pens). During the course of the inspection, be
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Blood Pressure Monitors, Invasive
Because some monitors do not compute the
true mean, the indicated mean value may vary
depending on the waveform and monitor used.
sure to check that each control and switch performs its proper function.
1.18 Indicators/Displays. During the inspection,
confirm the operation of all lights, indicators,
meters, gauges, and visual displays. Be sure
that all segments of the digital display function.
2. Quantitative tests
2.1
1.19 User Calibration. Verify that the zero-adjustment and any calibration controls function properly.
Zero the monitor with a transducer or
transducer simulator attached, making sure
that the zero adjustment is not at an extreme
setting. Confirm that the calibration function
operates and that the calibration or gain adjustment, if user adjustable, provides an adequate
range on both sides of the correct adjustment
point.
Some monitors have a calibration resistor inside the transducer cable connector. With such
units, the monitor’s calibration function will not
operate with a transducer simulator, which does
not usually include this calibration resistor. Use
the transducer intended for use with the monitor
for this test.
1.20 Alarms. Operate the device in such a way as to
activate each audible and visual alarm. If the
monitor has an alarm-silence feature, check the
method of reset (i.e., manual or automatic) against
the manufacturer’s specifications. Although it
may not be possible to verify the operation of all
alarms at this time (e.g., high blood pressure), it is
important to understand all of the alarm capabilities and remember to check them at the appropriate time during the procedure.
1.24 Pressure Modes. Verify that the monitor correctly indicates systolic, diastolic, and mean arterial pressures by switching the transducer
simulator between two pressure settings and
noting that the indicated pressure in the systolic
mode is highest, the mean pressure lower, and
the diastolic pressure lowest. The pulse pressure, if available, should be the difference between the systolic and diastolic pressures. (A
more quantitative and reproducible test can be
performed if a transducer simulator with a dynamic pressure waveform output is available.
However, the qualitative test is adequate, and
we do not recommend purchasing a dynamic
simulator solely for this purpose.)
Grounding Resistance. Using an ohmmeter,
electrical safety analyzer, or multimeter with
good resolution of fractional ohms, measure and
record the resistance between the grounding pin
of the power cord and exposed (unpainted and
nonanodized) metal on the chassis. We recommend a maximum resistance of 0.5 Ω. If the
system is modular, verify grounding of the mainframe and each module.
If the device has an accessory outlet, check its
grounding to the main power cord.
2.2
Leakage Current. Measure the leakage current
from the monitor chassis with the grounding
conductor temporarily opened. Check the monitor while on and off and record the maximum
leakage current. Chassis leakage current to
ground should not exceed 300 µA.
2.10 Accuracy, High (Arterial) Pressure Range. This
test checks the monitor’s accuracy and linearity.
The most convenient method for testing the
monitor’s accuracy is with a transducer simulator that contains a resistive network. Plug the
transducer simulator into the monitor and zero
it. Test pressures are 100 mm Hg and maximum
(or 200 mm Hg) for the systolic, diastolic, and
mean arterial modes. Normally, the monitor will
read approximately the same in each mode. Record values from only one mode (the least accurate), and indicate on the form which mode was
recorded. When using a pressure simulator, the
pressure monitor should measure to within 2%
of a given static pressure (or 1 mm Hg at pressures below 50 mm Hg).
Although considerably less convenient, an accurate pressure transducer, a 0 to 300 mm Hg
pressure gauge or meter, a sphygmomanometer
squeeze bulb, a Y connector, and tubing may be
substituted for the transducer simulator. Connect the stem of the Y connector to the
transducer and the Y connector arms to the
sphygmomanometer squeeze bulb and pressure
gauge (see Figure 1). The monitor should be
zeroed as it normally is during clinical use (with
the transducer open to atmospheric pressure).
Be sure that the dome is properly attached to the
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
3
Inspection and Preventive Maintenance System
respectively), and test for the actual alarm values by varying the applied or simulated pressure. Record the actual values on the form.
Alternatively, set appropriate applied or simulated pressures and raise and lower the high and
low alarm settings, respectively, until the alarm
activates. The unit should alarm within 5% of
the set value.
Many monitors have an alarm delay (up to
about 11 sec), which must be taken into account
when conducting this test. If the alarm delay is
excessive, compare it to the manufacturer’s
specification and arrange for adjustment or repair, if appropriate.
Figure 1. Pressure accuracy test
3. Preventive maintenance
transducer, especially if a disposable dome is
used. Test the monitor as described previously.
3.1
The overall accuracy of the transducer monitor system should be within 5% of a given static
pressure (or 2 mm Hg at pressures below 50 mm
Hg). If the error is excessive, determine whether
it is introduced by the transducer, monitor, or
both by using another transducer (or pressure
simulator) to test the monitor or another monitor
to test the transducer.
Conduct major inspection tests for this procedure
and the appropriate tests in the General Devices Procedure/Checklist 438. Determine whether the unit is
of an isolated input design to decide on appropriate
leakage current limits from each transducer connector
terminal to ground. If not labeled on the front panel,
check with the manufacturer to see if the monitor is
rated for this type of isolation test before proceeding.
2.11 Accuracy, Low Pressure Range. Repeat the pressure accuracy test, as described in Item 2.10, for
the venous and pulmonary ranges. Be sure the
monitor is accurately zeroed in each range before
taking measurements. Suggested test pressures
are 10 mm Hg and maximum (or 20 mm Hg).
Accuracy should be within 1 mm Hg if a blood
pressure transducer is used or 2 mm Hg if a
transducer is used.
Perform the isolation test only if your monitor is
designed with patient input isolation from ground.
Some blood pressure monitors rely upon isolation at
the transducer, rather than having isolated electronic
circuitry; performing this test on such a monitor may
damage the unit. If it is of isolated design, measure the
currents to each transducer connector terminal.
2.12 Alarm Accuracy. Set the alarm at appropriate
low and high settings (e.g., 100 and 180 mm Hg,
Return alarms and other controls to their preinspection settings.
4
Clean the exterior.
4. Acceptance tests
Before returning to use
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Procedure/Checklist 445-0595
Blood/Solution Warmers
Used For:
Warmers, Blood/Solution [10-447]
Also Called: Blood warmers, fluid warmers, solution warmers
Commonly Used In: Operating rooms, anesthesia departments, emergency departments, critical care areas,
blood banks
Scope: Applies to all types of warmers that heat blood or solutions in-line as they pass from the fluid bag or
infusion device to the patient; does not apply to unregulated water bath warmers (i.e., those with little or no
control over bath temperature) typically used for warming and/or thawing blood products in the clinical
laboratory or to pretransfusion microwave (radio-frequency) warmers
Risk Level: ECRI Recommended, Medium; Hospital Assessment,
Type
ECRI-Recommended
Interval
Major
12 months
months
.
hours
Minor
NA
months
.
hours
Overview
Blood/solution warmers are typically categorized by the
method of in-line heat transfer they use to warm incoming solutions. Types of heat exchangers include countercurrent fluid flow, dry heat, forced air, microwave,
and regulated water bath technologies. Countercurrent
devices pump heated water around the blood or solution
in a direction opposite to its flow. Dry heat warmers use
a disposable cassette, pouch, or tubing set positioned
against one or two heated metal surfaces. Forced air
units utilize convective warming by pumping heated air
around a disposable tubing set. Microwave devices control blood or solution temperature through the use of
noninvasive radiometric sensing, allowing immediate
power adjustment. Regulated water bath units typically consist of a disposable bag or coiled tubing immersed in a controlled temperature bath.
Blood/solution warmers are generally used in the
operating room by the anesthesia staff. Clinicians
disagree on when a blood/solution warmer should be
used for patient thermoregulation. Only under certain
016703
445-0595
A NONPROFIT AGENCY
Interval Used
By Hospital
Time Required
circumstances, such as during massive (generally accepted to be five units or more) and/or rapid transfusion, is it widely agreed that blood/solution warmers
should be used. In these applications, effective
blood/solution warmer operation is crucial.
Should a temperature controller malfunction and
allow the blood to overheat, damaged or lysed red blood
cells can be delivered to the patient. Although overtemperature alarms are considered a necessary feature,
some units lack them. Hospitals should replace such
units with units equipped with alarms. Failure of the
heater to adequately warm blood could significantly
lower body temperature and further compromise the
patient. Thus, periodic inspection of these units is
particularly important to detect a malfunction likely
to escape the user’s attention.
Manufacturers should provide fluid output temperature data as a function of flow rate through a
disposable set. Clinicians use such information in considering the actual contribution of a blood/solution
warmer to patient thermoregulation. Although not
required as a routine inspection procedure, assess-
5200 Butler Pike, Plymouth Meeting, PA 19462-1298, USA
Telephone +1 (610) 825-6000 ● Fax +1 (610) 834-1275
●
E-mail [email protected]
Inspection and Preventive Maintenance System
ment of this performance characteristic is covered in
an acceptance test (Item 4.2). Data from this testing
should be used in evaluating a unit for purchase.
Citations from Health Devices
Blood warmers [Evaluation], 1984 Jul; 13:191-219.
Test apparatus and supplies
Ground resistance ohmmeter
Leakage current meter or electrical safety analyzer
A mercury-in-glass calibration thermometer or electronic thermometer accurate to at least ±0.2°C over
the range of 30° to 45°C
Blood/solution warmer disposable set
Wire or jumper leads
Silicone heat sink compound or other thermally
conductive medium (use on thermometer or temperature probe for better contact with heat exchanger in dry heat warmers)
Hot (50° to 60°C) and room temperature water
General-purpose infusion pump and infusion set
Fluid container (0.5 to 1.0 L) filled with refrigerated
(4° to 6°C) saline
Special precautions
Caution: Treat blood warmers as contaminated devices. Follow manufacturer-recommended decontamination procedures; also see “IPM Safety,” behind the
Guidance Tab of this binder, for infection control guidelines.
Many warmers have special temperature measurement ports or accessories to assist biomedical personnel in determining heat exchanger temperature and
alarm settings. However, even when properly used,
these options may not correctly reflect the actual heat
exchanger temperature, and the measurements obtained by these methods will not necessarily agree
with the unit’s displayed temperatures. When using
these options during quantitative inspections to determine display accuracy and alarm settings, check the
service manual for correct thermometer or temperature probe placement and for allowable differences
between measured and expected readings. Use a silicone heat sink compound to improve the contact between the thermometer or temperature probe and the
measured surface. Be sure to remove the compound as
soon as measurements are completed. If you find a
slightly larger difference than expected between your
measurements and the temperature values provided
by the manufacturer, do not immediately remove the
2
unit from use; this may be due to test error or subtle
differences in test methods. Contact the manufacturer
to determine whether such a difference (e.g., >0.5°C
beyond service manual limits) is acceptable.
Testing alarms and thermostatic settings may require disassembly of the unit and temporary modification of the wiring. We hesitate to recommend such
action as part of a routine inspection procedure because unskilled personnel may inadvertently damage
the unit; however, there may be no other way to determine whether the backup thermostat or overtemperature alarms are functional. Unfortunately, for some
units, temporarily bypassing the primary thermostat
or similar control is the only way to determine whether
backup or safety thermostats are functioning properly.
Personnel responsible for inspecting blood/solution
warmers must recognize their own limitations and,
where appropriate, seek qualified help when performing this test. Return the unit to its normal operating
condition immediately after completing the test. Perform the operating temperature test (Item 2.10 or 2.11)
after the temperature protection test (Item 2.3) to help
ensure that the device has been correctly returned to
its proper operating condition.
Procedure
Before beginning an inspection, carefully read this
procedure and the manufacturer’s instruction and
service manuals; be sure that you understand how to
operate the equipment, the significance of each control
and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive
maintenance procedures or frequencies are recommended by the manufacturer.
1. Qualitative tests
1.1
Chassis/Housing. Examine the exterior of the
unit for cleanliness and general physical condition. Be sure that plastic housings are intact and
are not cracked, that necessary assembly hardware is present and tight, and that there are no
signs of spilled liquids or other serious abuse.
Check that all doors, hinges, and closure mechanisms work properly. Examine the interior surfaces where the disposable set will contact the
heat exchange medium. Remove any corrosion,
debris, or fungal buildup that may interfere with
the temperature-sensing mechanism or heating
of fluid in the disposable set.
1.2
IV Pole Mount. Examine mounting clamps,
bolts, and other mechanisms for cracks and a
secure fit. Verify that a water bath warmer is
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Blood/Solution Warmers
each control and switch performs its proper function. If the switch has a protective boot to guard
against fluid infiltration, make sure that the boot
is intact and protects the switch.
reasonably stable when filled with water and
mounted on the IV pole.
1.3
1.4
1.5
Base Supports. If the warmer has a freestanding capability, check that all rubber feet or other
supports are securely in place. Remount or
reglue any loose supports to ensure stability and
adequate clearance for any components (e.g.,
overtemperature alarms, reset features) that
may be located on the base of the warmer.
AC Plug. Examine the AC power plug for damage. Attempt to wiggle the blades and determine
whether they are secure. Check for fluid infiltration in the plug. Shake the plug and listen for
rattles that could indicate loose screws. If any
damage is suspected, open the plug and inspect
it fully.
Line Cord. Inspect the cord for signs of damage.
If damaged, replace the entire cord or, if the
damage is near one end, cut out the defective
portion. Be sure to wire a new power cord or plug
with the correct polarity. After any modifications, make sure that the line cord is long enough
to preclude the need for an extension cord.
1.6
Strain Reliefs. Examine the strain reliefs at
both ends of the line cord; be sure that they hold
the cord securely and that they have not become
dislodged from the chassis of the unit.
1.7
Circuit Breaker/Fuse. If the warmer has a
switch-type circuit breaker, check that it moves
freely. If the warmer is protected by a fuse,
check its value and type (as well as those of any
spares provided) against that marked on the
chassis or in the instruction manual.
1.11 Temperature Sensor (water bath units). The
temperature sensor of a water bath unit may be
located at the base of the water well. Inspect its
sheath or surface for corrosion and mechanical
integrity. Many units provide some form of protection or grid to isolate the disposable set from
the temperature sensor and/or heaters. Confirm
that the grid is in place and fits properly. Replace the grid if it is excessively corroded.
1.13 Controls/Switches. Examine all controls and
switches for physical condition, secure mounting, and correct motion. Where a control should
operate against fixed-limit stops, check for
proper alignment, as well as positive stopping.
Check membrane switches for membrane damage (e.g., from fingernails, pens). During the
course of the inspection, be sure to check that
1.14 Heater(s). If the heater component is readily
available for visual inspection without disassembly, examine its physical condition (e.g., corrosion of its sheath, deteriorated insulation).
Operate the warmer to ensure that it does heat
up and that the display follows a reasonable
pattern of increasing temperature. If the unit
has an indicator light to show that the heater is
operating, check that it functions normally.
1.18 Indicators/Displays. During the course of the
inspection, confirm the operation of all lights,
indicators, meters, gauges, and visual displays
on the unit. Be sure that all segments of a digital
display function.
1.20 Alarms. Many warmers have an alarm-test feature that activates their audible and visual
alarms. If so equipped, operate the warmer, actuate this feature, and ensure operation of the
high-temperature alarm. Otherwise, circulate
hot water (50° to 60°C) through an installed disposable set, and verify that the alarm activates
and that the heater cycles off. Most water bath
units do not have an alarm-test feature, but the
overtemperature alarm can be easily triggered by
filling the well with hot water (50° to 60°C).
1.21 Audible Signals. Operate the device to activate
any audible signals. Confirm the adequacy of
alarm volume.
1.22 Labeling. Check that all necessary placards, labels, conversion charts, and instruction cards
are present and legible.
1.24 Alignment Features for Disposable Sets. Check
for loose or missing pins, blocked channels, or
missing guides that may hinder placement of the
disposable set. Using the manufacturer’s instructions, position the disposable set and check
that it is secure.
2. Quantitative tests
2.1
Grounding Resistance. Using an ohmmeter,
electrical safety analyzer, or multimeter with
good resolution of fractional ohms, measure and
record the resistance between the grounding pin
of the power cord and exposed bare (not painted
or anodized) metal on the chassis. We recommend a maximum of 0.5 Ω.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
3
Inspection and Preventive Maintenance System
2.2
2.3
Leakage Current. Measure chassis leakage current to ground with correct and reversed polarity
wiring and with the grounding conductor temporarily opened. Operate the device in all normal
modes, including on (while the heater cycles on
and off) and off, and record the maximum leakage current. Leakage current should not exceed
300 µA.
High-Temperature Protection. Determine the
warmer’s various means of protection against
overheating blood. If the manufacturer has provided a detailed method by which backup controllers and alarms can be tested, follow this
procedure. Otherwise, obtain schematics and/or
instructions to bypass the primary temperature
control (see Special Precautions).
If there are no procedures available, first bypass the primary temperature control in the
warmer (by shorting or opening it, as appropriate) and turn on the warmer so that the heater is
controlled by the backup mechanism. Follow the
manufacturer’s recommended procedure for setting up the blood/solution warmer. With the thermometer or temperature probe in place within
the heat exchanger, confirm that alarms go off at
intended set points and that power to the heater
is cut off at the intended settings. At no time
should heat exchanger temperatures exceed 42°C.
The difference between the values for alarm set
points and backup control as given by the manufacturer and those observed on the blood warmer
temperature display should not exceed 0.5°C.
The difference may be greater for some units with
alarms and backup control based on a thermostat
with a lag. In these cases, check that the unit is
not alarming at a point different from the point
observed in acceptance testing, measure the actual heat exchanger temperature in several locations, and ensure that it does not exceed 42°C
upon activation of the alarm.
Caution: Remove any bypasses installed for this
test. If any recalibration is carried out involving
sealed potentiometer or thermostat screws, reseal
them. When reassembling the unit, reseal the
back or bottom plates or panels into place with
silicone compound to prevent fluid infiltration.
2.10 Display Accuracy and Temperature Control.
Most temperature displays on blood warmers
indicate heat exchanger temperature, not the
exiting temperature of blood or fluid. Therefore,
in most units, it is necessary to measure only the
heat exchanger temperature and compare it
4
with the displayed temperature to ascertain
proper functioning of the display temperature
sensors.
(Applying power to some warmers when they
lack a fluid flow through the unit’s disposable set
may result in temperature overshoot and alarms
that make assessing temperature sensor accuracy difficult. If, after reading the service manual, you find it necessary to establish a cold fluid
flow through the disposable set before proceeding, perform Item 2.11 to determine display accuracy and temperature control.)
To determine display accuracy and temperature control, position the thermometer or temperature probe against or within the unit’s heat
exchange medium (some units require special
accessories or have built-in ports for this purpose). If possible, position probes at three separate points within the heat exchanger and, if
necessary, use a silicone heat sink compound to
establish better thermal contact. (Remember to
remove this compound and thermometer or temperature probe from the unit when finished.) The
heat exchanger should be at room temperature
before proceeding. Turn the unit on and compare
the unit’s displayed temperature with the probe
temperature(s) as the unit heats up and reaches
a steady state. These temperatures should be
within 1.0°C during warm-up and within 0.5°C
during steady state. Observe the unit for 5 min
at steady state for proper maintenance of heat
exchanger temperature. Allow a total of 15 to 20
min to observe temperatures, because some
warmers require 10 to 12 min to warm up and
reach a stable heat exchanger temperature.
2.11 Temperature Controller Performance. (This procedure need not be followed if Item 2.10 can be
successfully used to determine accuracy and temperature control.) Position the temperature probe
against or within the heat exchanger, using any
special adapters or ports designated for this purpose but insulated from the disposable set. Use
refrigerated (4° to 6°C) saline and maintain a flow
of 500 mL/hr through the unit with an infusion
pump. During heat exchanger warm-up, compare
the temperature displayed on the warmer with the
thermometer at three separate points. If the probe
has been successfully insulated from sensing the
temperature of the cold fluid, the display and the
heat exchanger temperature measurements
should be within 1.0°C. Allow the warmer to
stabilize for 5 min, and compare probe tempera-
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Blood/Solution Warmers
ture with the displayed temperature; the discrepancy should be within 0.5°C. Check that the
operating range of the warmer, as determined
from the display, conforms to values specified by
the manufacturer.
3. Preventive maintenance
3.1
Clean the unit’s exterior and heating plates or
bath. Clean debris from door hinges. The interior of water bath units should be rinsed and
dried after each use.
3.3
Calibrate if needed.
4. Acceptance tests
Conduct major inspection tests for this procedure
and the appropriate tests in the General Devices Procedure/Checklist 438. In addition, perform the following tests.
4.1
Patient Lead Leakage Current. Prime the disposable set with saline, and allow a drip flow
through the warmer. Measure the patient lead
leakage current from a steel-hub hypodermic
needle on the distal connector of the administration set to ground with correct polarity but with
an open grounding pin. Operate the device in all
modes, including on (while the heater cycles on
and off) and off. Patient lead leakage current
should not exceed 100 µA.
4.2
Fluid Temperature. (This procedure is optional,
but may be particularly useful in evaluating a
unit for purchase. It can be used to provide fluid
output temperature data as a function of fluid
flow.)
To assess the warmer’s heating capability, select its maximum temperature setting and allow
the unit to stabilize. Monitor and record ambient
temperature (i.e., 18° to 22°C) for future comparison of results. Use a thermometer or temperature
probe to measure the outflow temperature of
refrigerated (4° to 6°C) saline at various flow
rates corresponding to intended clinical applications or the manufacturer’s recommendations for
use. Fluid temperature measurement should be
at the end of the manufacturer’s disposable set or
at the outlet of any extension tubing required to
accurately simulate a clinical setting. Ideally, the
unit should deliver fluids at 37° to 42°C at the
highest flow setting that clinicians expect to use
with this unit. If the unit’s heat exchanger exceeds 42°C, also measure the output fluid temperature as close to the heat exchanger as
possible to verify that it does not exceed 42°C, as
well. Record all output fluid temperatures and
the corresponding flows for future reference.
Before returning to use
Verify that any control circuits that were bypassed
or deactivated for testing purposes have been returned
to their normal operating conditions.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
5
Procedure/Checklist 450-0595
Capnometers and Multiple Medical Gas
Monitors
Used For:
Carbon Dioxide Monitors, Exhaled Gas [16-938]
Multiple Medical Gas Monitors [17-443]
Multiple Medical Gas Monitors, Respired [17-444]
Multiple Medical Gas Monitors, Respired/Anesthetic [17-445]
Also Called: Capnographs, end-tidal CO2 monitors
Commonly Used In: Operating rooms, critical care units, emergency departments; portable units may be
used by EMS
Scope: Applies to monitors that analyze concentrations of respired and/or anesthetic gases, and that may
also be equipped with additional capabilities, such as pulse oximetry or airway pressure and minute and tidal
volume monitoring (inspection of the pulse oximetry capability is covered in Pulse Oximeters Procedure/Checklist 451)
Risk Level: ECRI Recommended, High; Hospital Assessment,
Type
ECRI-Recommended
Interval
Interval Used
By Hospital
Major
12 months*
months
.
hours
Minor
NA
months
.
hours
Time Required
* Some manufacturers may recommend calibration at a semiannual or monthly interval.
Overview
Carbon dioxide (CO2) monitors (e.g., capnometers) use
infrared spectrometry to measure CO2 concentrations.
Currently, CO2 monitors are used primarily in the
operating room to monitor patients during anesthesia;
the devices alert physicians to inadequate ventilation
(i.e., minute volume that is too low), patient circuit
disconnections, and airway leaks. CO2 monitoring can
also detect ventilator failure and the inadvertent
placement of the endotracheal tube in the esophagus.
Interest in applying CO2 monitoring to intensive
care mechanical ventilation is increasing, primarily to
evaluate the effects of changing ventilation modes, of
bronchodilator treatment effectiveness, and of the patient’s ability to breathe spontaneously after ventilator
support is discontinued.
084776
450-0595
A NONPROFIT AGENCY
Capnometers, which are battery powered and lightweight, are suitable for emergency medicine (e.g.,
prehospital use, emergency departments, crash carts)
and patient transport. These units are used clinically
to detect esophageal intubation, monitor for and detect complete loss of ventilation or apnea, and assess
respiration.
Multiple medical gas monitors (MMGMs) incorporate
monitoring of several gases, including CO2, along with
other parameters such as pulse oximetry, respiration
rate, and airway pressure. Information provided by
MMGMs is easier to review, and an MMGM’s cost is
lower than the combined cost of the monitors it replaces.
Two types of MMGMs are available. Respired-gas
MMGMs are used in critical care areas to monitor
ventilation of mechanically ventilated patients and to
5200 Butler Pike, Plymouth Meeting, PA 19462-1298, USA
Telephone +1 (610) 825-6000 ● Fax +1 (610) 834-1275
●
E-mail [email protected]
Inspection and Preventive Maintenance System
assess the adequacy of their parenteral nutrient intake
by tracking their metabolic rate. MMGMs that monitor
respired and anesthetic gases are intended for use in
the OR and can indicate malfunctions or disconnections in the gas delivery system and abnormalities in
the uptake, removal, and delivery of gases.
mount. If it is attached to a wall or rests on a
shelf, check the security of this attachment.
1.4
AC Plug. Examine the AC power plug for damage.
Attempt to wiggle the blades to check that they are
secure. Shake the plug and listen for rattles that
could indicate loose screws. If any damage is suspected, open the plug and inspect it.
1.5
Line Cord. Inspect the cord for signs of damage.
If damaged, replace the entire cord, or if the
damage is near one end, cut out the defective
portion. Be sure to wire a new power cord or plug
with the correct polarity.
1.6
Strain Reliefs. Examine the strain reliefs at
both ends of the line cord. Be sure that they hold
the cord securely. If the line cord is detachable
(by the user), affix the cord to the unit so that it
cannot be removed by the operator. (See Health
Devices 1993 May-Jun; 22:301-3.)
1.7
Circuit Breaker/Fuse. If the device has a switchtype circuit breaker, check that it moves freely.
If the device is protected by an external fuse,
check its value and type against that marked on
the chassis, and ensure that a spare is provided.
1.9
Cables. Inspect any cables and their strain reliefs for general condition. Carefully examine
cables to detect breaks in the insulation and to
ensure that they are gripped securely in the
connectors at each end to prevent rotation or
other strain. Verify that there are no intermittent faults by flexing electrical cables near each
end and looking for erratic operation or by using
an ohmmeter.
Citations from Health Devices
Carbon dioxide monitors [Evaluation], 1986 Sep-Oct;
15:255-85. (See also 1986 Nov; 15:316.)
Marquette Series 7000 capnometer [Update], 1987
Feb; 16:56.
Hewlett-Packard Model 47210A capnometers [User
Experience NetworkTM], 1987 Jun; 16:219. (See also
1987 Jul; 16:251.)
Multiple medical gas monitors, respired/anesthetic
[Evaluation], 1990 Feb; 20:43-54.
Test apparatus and supplies
Leakage current meter or electrical safety analyzer
Ground resistance ohmmeter
Calibration gas
Stopwatch or watch with a second hand
Flowmeter (0 to 1 L/min air)
Special precautions
Exposure to waste anesthetic gas can be hazardous.
Gases containing inhalated anesthetics (e.g., N2O, halogenated agents) should be scavenged.
Procedure
Before beginning an inspection, carefully read this
procedure and the manufacturer’s instruction and
service manuals; be sure that you understand how to
operate the equipment, the significance of each control
and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive
maintenance procedures or frequencies are recommended by the manufacturer.
1. Qualitative tests
1.1
1.2
2
Chassis/Housing. Examine the exterior of the
unit for cleanliness and general physical condition.
Be sure that plastic housings are intact, that all
hardware is present and tight, and that there are
no signs of spilled liquids or other serious abuse.
Mount/Fasteners. If the device is mounted on a
stand or cart, examine the condition of the
1.10 Fittings/Connectors. Examine gas sample inlet
and exhaust port connectors, as well as electrical
cable connectors, for general condition. Electrical contact pins or surfaces should be straight,
clean, and bright. Verify that sensors and sampling lines are firmly gripped in their appropriate connectors. Fittings should be tight and
should not leak.
1.11 Sensors/Sampling Lines. Examine these for
general condition. If disposable sampling lines are
used, verify that an adequate supply is available.
1.12 Filters. Check the condition of all gas (air) filters. Clean or replace if appropriate, and indicate
this on Line 3.1 or 3.4 of the inspection form.
1.13 Controls/Switches. Before changing any controls or alarm limits, check their positions. If any
settings appear inordinate (e.g., a gain control at
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Capnometers and Multiple Medical Gas Monitors
maximum, alarm limits at the ends of their
range), consider the possibility of inappropriate
clinical use or of incipient device failure. Record
the settings of those controls that should be
returned to their original positions following the
inspection.
Examine all controls and switches for physical
condition, secure mounting, and correct motion.
Check that control knobs have not slipped on
their shafts. Where a control should operate
against fixed-limit stops, check for proper alignment, as well as positive stopping. Check membrane switches for membrane damage (e.g., from
fingernails, pens). During the course of the inspection, be sure to check that each control and
switch performs its proper function.
displays a respiration rate and that the CO2
waveform indicates the breaths.
1.19 User Calibration. Verify that the calibration
function operates.
1.20 Alarms. Induce each alarm condition with each
procedure below, and verify that the unit activates an audible and visual alarm for each alarm
limit that has been exceeded. If the unit has an
alarm-silence feature, check the method of reset
(i.e., manual or automatic) against the manufacturer’s specifications. Verify that reset silenced
alarms reactivate within the manufacturer’s
specified time. It may not be possible to check out
all alarms at this time, since some may require
abnormal operating conditions that will be simulated later in this procedure.
1.15 Pump. Check the physical condition and proper
operation of the pump. Clean and lubricate if
required, and note this on Lines 3.1 and 3.2 of
the inspection form. (However, do not check
these items until all necessary cleaning and lubrication are completed.)
1.17 Battery/Charger. Inspect the physical condition of batteries and battery connectors, if readily accessible.
Check operation of
battery-operated power-loss alarms, if so
equipped. Operate the unit on battery power for
several minutes to check that the battery is
charged and can hold a charge. (The inspection
can be carried out on battery power to help
confirm adequate battery capacity.) Check battery condition by activating the battery test function or measuring the output voltage. Check the
condition of the battery charger, and to the extent possible, confirm that it does in fact charge
the battery. Be sure that the battery is recharged or charging when the inspection is complete. When it is necessary to replace a battery,
label it with the date.
1.18 Indicators/Displays. During the course of the
inspection, confirm the operation of all lights,
indicators, meters, gauges, and visual displays
on the unit and charger (if so equipped). Be sure
that all segments of a digital display function
and that the unit displays waveforms and trending information. Observe a signal on a CRT display, if present, and check its quality (e.g.,
distortion, focus, 60 Hz noise).
Connect a clean airway adapter and sampling
line to the unit, and blow several breaths into the
adapter before stopping. Verify that the monitor
Gas concentration alarms. Set the gas alarm
limits so that the concentration in the calibration gas will exceed the limits (i.e., set the
high-concentration alarm limits below the
calibration gas concentrations and the lowconcentration alarm limits above the calibration gas concentrations). Deliver the
calibration gas to the monitor. Verify that
visual and audible high-concentration and
low-concentration alarms activate.
Occlusion alarm. Block the sampling line, and
observe the alarm.
Other alarms. If the unit indicates any other
alarm condition, induce the alarm, and verify
that the alarm condition is indicated by the unit.
1.21 Audible Signals. Operate the device to activate
any audible signals. Confirm appropriate volume, as well as the operation of a volume control,
if so equipped. If audible alarms have been silenced or the volume set too low, alert clinical
staff to the importance of keeping alarms at the
appropriate level.
1.22 Labeling. Check that all necessary placards, labels, conversion charts, and instruction cards
are present and legible.
1.23 Accessories. Confirm the presence and condition
of breathing circuit adapters and sampling lines
and, when applicable, water traps and filters.
2. Quantitative tests
2.1
Grounding Resistance. Using an ohmmeter,
electrical safety analyzer, or multimeter with
good resolution of fractional ohms, measure and
record the resistance between the grounding pin
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
3
Inspection and Preventive Maintenance System
of the power cord and exposed (unpainted and
not anodized) metal on the chassis. We recommend a maximum of 0.5 Ω. If the system is
modular or composed of separate components,
verify grounding of the mainframe and each
module or component. If the device is double
insulated, grounding resistance need not be
measured; indicate “DI” instead of the ground
resistance value.
2.2
Leakage Current. Measure chassis leakage current to ground with the grounding conductor of
plug-connected equipment temporarily opened.
Operate the device in all normal modes, including on, standby, and off, and record the maximum leakage current.
Measure chassis leakage current with all accessories normally powered from the same line
cord connected and turned on and off. This includes other equipment that is plugged into the
primary device’s accessory receptacles, as well as
equipment plugged into a multiple-outlet strip
(“Waber strip”) so that all are grounded through
a single line or extension cord.
Chassis leakage current to ground should not
exceed 300 µA.
2.3
Oxygen (O2) Concentration Display Accuracy.
Deliver calibration gas containing O2 to the unit,
and record the delivered and displayed O2 concentrations on the inspection form. The display
should be within 2 vol% or within 5%, whichever
is greater, of the delivered concentration. If the
gas concentration display is inaccurate, calibrate
the unit.
Note: Vol% refers to the absolute value versus % of value. For example, a 5% (of value) error
at 40 vol% of O2 is the same as a 2 vol% error.
2.4
2.5
4
Carbon Dioxide (CO2) Concentration Display Accuracy. Deliver calibration gas containing CO2
to the unit, and record the delivered and displayed CO2 concentrations on the inspection
form. The display should be within 0.4 vol% (±3
mm Hg) or within 10%, whichever is greater, of
the delivered concentration. If the gas concentration display is inaccurate, calibrate the unit.
Halogenated Agent Concentration Display Accuracy. Select an agent on the monitor, and deliver
calibration gas containing that agent to the unit.
Record the delivered and displayed agent concentrations on the inspection form. The display
should be within 0.25 vol% of the delivered concentration. If the gas concentration display is
inaccurate, calibrate the unit.
2.6
Nitrous Oxide (N2O) Concentration Display Accuracy. Deliver calibration gas containing N2O
to the unit, and record the delivered and displayed N2O concentrations on the inspection
form. The display should be within 5 vol% or
within 10%, whichever is greater, of the delivered concentration. If the gas concentration display is inaccurate, calibrate the unit.
2.7
Sampling Flow Accuracy. Attach a flowmeter to
the sampling inlet, and verify the sampling flow
at the highest flow setting. The flow rate should
be within the manufacturer’s specified range. If
the manufacturer’s information is unavailable,
the flow should be within 20% of the flow setting.
Calibrate the unit per the manufacturer’s instructions, if the flow is inaccurate.
3. Preventive maintenance
3.1
Clean if needed, including the internal sampling
line if specified by the manufacturer.
3.2
Lubricate pump if required.
3.3
Calibrate if required per the manufacturer’s instructions.
3.4
Replace O2 cell, air filters, water traps, and the
CO2 absorber, if needed. Record the replacement date on the O2 cell label before installing it
in the monitor.
4. Acceptance tests
Conduct major inspection tests for this procedure
and the appropriate tests in the General Devices Procedure/Checklist 438.
Before returning to use
Make sure that all controls are set properly. Set
alarms loud enough to alert personnel in the area in
which the device will be used. Other controls should
be in their normal pre-use positions.
Recharge battery-powered devices or equip them
with fresh batteries if needed.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Procedure/Checklist 446-0595
Carbon Dioxide Surgical Lasers
Used For:
Lasers, Surgical, Carbon Dioxide [16-942]
Also Called: CO2 lasers, surgical lasers, gynecology lasers, ENT lasers, neurosurgical lasers
Commonly Used In: Operating rooms, short procedure areas, physicians’ offices
Scope: Applies to general-purpose CO2 surgical lasers that include an articulating arm, emit mid-infrared energy
at 10,600 nm, and provide sufficient power output to vaporize tissue; also applies to low- and high-power CO2
surgical lasers that are typically used for general surgery, gynecology, ENT, neurosurgery, podiatry, and dermatology
procedures; does not apply to handheld CO2 lasers, other infrared lasers, Nd:YAG and argon lasers, and ophthalmic
lasers; however, many of the tests listed herein can be used or modified for these other lasers
Risk Level: ECRI Recommended, High; Hospital Assessment,
Type
ECRI-Recommended
Interval
Major
12 months
months
.
hours
Minor
6 months
months
.
hours
Overview
CO2 lasers are normally checked before each use by the
laser’s power-on self-test and by user examination of
the aiming beam and calibration of the system with the
delivery system to be used. This minimizes the need
for frequent additional periodic testing.
Failure of a CO2 surgical laser can cause patient or
staff injury, an abrupt interruption of a surgical procedure, or damage to the laser system. CO2 surgical
lasers must be meticulously maintained to ensure
proper and safe operation.
CO2 surgical lasers affect tissue by focusing invisible, far-infrared energy at a sufficient power density to
cause vaporization. This energy heats the water in the
cells to the boiling point, which in turn vaporizes the
tissue. The wavelength is readily absorbed by water
and has little scatter in tissue. It cannot be transmitted
through liquids (e.g., water, blood). CO2 surgical lasers
are considered good cutting instruments.
042241
446-0595
A NONPROFIT AGENCY
Interval Used
By Hospital
Time Required
General-purpose CO2 surgical lasers have a flowinggas laser tube or a sealed or semisealed gas tube.
Energy leaving the laser tube through a partially reflecting mirror is typically directed into an articulating
arm. This arm contains a series of hollow tubes connected by knuckles at the ends to allow 360° rotation,
with mirrors in the knuckles to redirect the energy
down the next tube. A laser handpiece or a laser
micromanipulator (used to interface the laser with the
surgical microscope) is usually attached to the last
tube of the articulating arm; these attachments focus
the energy into a small spot size at a known working
distance. Because the mid-infrared energy emitted by
the CO2 laser is invisible, a second, nontherapeutic
aiming helium-neon (He-Ne) laser emitting visible red
light simultaneously traverses the articulating arm
and is focused coincident (i.e., at the same point) with
the CO2 laser beam. Some newer lasers have orange or
yellow aiming beams.
Like most lasers, CO2 lasers are somewhat inefficient in converting electrical energy from their standard 115 VAC source into laser energy of 0 to 100 W.
5200 Butler Pike, Plymouth Meeting, PA 19462-1298, USA
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Inspection and Preventive Maintenance System
As a result, excess heat is generated in the laser tube,
requiring a cooling system. Some CO2 lasers use air
cooling, although most use a combination water/air cooling system. Flowing-gas tube lasers require regulation of
the pressure and flow of special gas mixtures. Hence,
either an internal or external gas regulation system must
be included. Flowing and semisealed lasers typically use
a vacuum pump to maintain tube pressure.
Citations from Health Devices
Lasers in medicine: An introduction, 1984 Jun; 13:15178.
Lasers as investigational devices: Appendix A, 1984
Jun; 13:167-9.
Lasers: Model policy and procedures statement: Appendix B, 1984 Jun; 13:169-71.
Sharplan 733 carbon dioxide surgical lasers [User Experience NetworkTM], 1984 Sep; 13:291.
Surgilase CO2 lasers [Hazard], 1987 May; 16:176.
Lack of pin-indexing on laser gas supplies [Hazard],
1987 Jun; 16:216.
Lack of pin-indexing on laser gas supplies [Hazard
update], 1987 Aug; 16:286.
Power requirements for Coherent Excelase 55 CO2
laser [User Experience NetworkTM], 1989 Oct;
18:365.
Surgical lasers [Evaluation], 1991 Jul-Aug; 20:239-316.
Loose caster screws on Sharplan lasers, 1992 Feb;
21:79.
Test apparatus and supplies
Leakage current meter or electrical safety analyzer
Ground resistance ohmmeter
Black Delrin block ≥1⁄2″ thick, ≥1″ wide, about 3″ to
4″ long; or firebrick
Laser beam imaging media (e.g., thermal imaging
paper, thermal imaging plates; wood tongue depressors may be an acceptable alternative)
Laser radiometer (power meter)
Laser safety signs
Laser safety eyewear specifically designed for use
with CO2 surgical lasers and of sufficient optical
density to protect the wearer’s eyes from laser injury
Vise with padded jaws or ring stand with padded
clamp
Outlet test fixture (optional)
2
Insulating gloves, high voltage (optional)
Grounding strap (optional)
Special precautions
Inspecting and maintaining lasers is a dangerous as
well as necessary process, and far greater care is
required than with most devices. Personnel who inspect or service lasers should receive special training
from the manufacturer or from a qualified alternative
training source.
Laser energy can cause serious injury, particularly
when the internal interlock is overridden or in any
other situation in which the energy does not diverge
significantly over long distances. Under some circumstances, the beam may not diverge significantly, even
a full room length or more away from the laser (and
can harm tissue or burn material even at this distance). Therefore, exercise great care whenever a laser
beam is accessible. Area security and use of personnel
protective devices and practices should be consistent
with hospitalwide laser safety procedures and/or
should be approved by the laser safety committee.
Wear appropriate laser safety eyewear at all times
whenever the laser is in the Operating mode. WARNING: Laser safety eyewear may not protect the wearer
from the aiming system light. Do not stare directly into
the aiming system beam or the therapeutic laser beam,
even when wearing laser safety eyewear. Avoid placing
the laser beam path at eye level (i.e., when kneeling,
sitting, or standing). (Window covers are not necessary
with carbon dioxide lasers.)
Do not perform these procedures when a patient is
present or when clinical staff is working, and do not aim
the laser across a path that a person might normally
use as a thoroughfare. Furthermore, at minimum, post
doors to the room with appropriate laser safety signs
stating that the laser is in use and that it is unsafe to
enter the room without authorization by the service
person performing the procedure. A second person
should be present, especially during procedures of recognized risk, to summon help in case of an accident.
The laser should remain in the Off position when
not in use. When in use, it should be in the
Standby/Disabled mode. Do not switch it to the Operating mode until the procedure is about to begin and
the laser and its delivery system are properly positioned. If the procedure must be interrupted, disconnect the laser from line voltage, and remove the laser
operation key and store it in a controlled location.
Do not use the laser in the presence of flammable
anesthetics or other volatile substances or materials
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©1995 ECRI. All Rights Reserved.
Carbon Dioxide Surgical Lasers
and ensure that they have been turned off
after the last use. Examine the exterior of the
unit for cleanliness and general physical condition. Be sure that all housings are intact
and properly aligned, that assembly hardware is present and tight, that any retractable
parts slide easily and lock in place if so constructed, that there are no signs of spilled
liquids or other evidence of abuse, and that
there are no obvious signs of water or oil
leakage.
(e.g., alcohol) or in an oxygen-enriched atmosphere
because of the serious risk of explosion and fire. Remove from the working area or cover with flame-resistant opaque material all reflective surfaces likely to be
contacted by the laser beam. Whenever possible, use
a firebrick or other nonflammable material behind the
target material (e.g., black Delrin) when the laser is to
be activated. A CO2 fire extinguisher should be readily
available.
Some surgical lasers use high voltages (e.g., 20 kV),
which can be lethal. Capacitors may store charges
long after the device has been disconnected from line
voltage. Consult the manufacturer’s recommended
procedures for servicing high-voltage laser circuits,
and avoid contact with any portion of the high-voltage
circuit until you are certain that the charge has been
drained. In such instances, a good ground must be
present; preferably, use a redundant ground strap if
you must enter the laser cabinet. When possible, disconnect the laser from line voltage before entering the
laser cabinet, and use insulated gloves for those procedures in which contact with a high-voltage source is
possible (and the gloves are not otherwise contraindicated). Ensure that equipment intended to be used to
measure, drain, or insulate high voltages carries the
appropriate insulation rating (e.g., above 20 kV).
Articulating arm. Examine the exterior of the
articulating arm for cleanliness and general
physical condition. Be sure that all hardware
(e.g., laser gas tubing channels) is present, in
good condition, and firmly attached. Ensure
that the arm is properly counterbalanced and
maintains its position without any motion after it has been moved and released. Ensure
that each knuckle of the arm moves easily in
each direction. Examine the distal end of the
articulating arm to ensure that the mechanism (e.g., threads or quick-connect fitting) is
in proper working order.
Shutters. If manual shutters for the aiming or
therapeutic laser are accessible, ensure that
they operate smoothly and correctly. Be sure
to leave the shutter in the proper position for
normal operation.
Where possible, perform tests with the unit turned
off. Because of the presence of high voltage, perform
the Grounding Resistance Test (Item 2.1) before any
other item that requires operation of the laser.
Telescoping columns. Examine the exterior of
the telescoping column for cleanliness and
general physical condition. Ensure that the
column can be adjusted through its full range.
If lubrication is required, note this on Line 3.2
of the inspection form.
Report any laser accident immediately to the laser
safety officer or equivalent, as well as to the hospital
risk manager.
Procedure
Before beginning an inspection, carefully read this
procedure and the manufacturer’s instruction and
service manuals; be sure that you understand how to
operate the equipment, the significance of each control
and indicator, and precautions needed to ensure safety
and to avoid equipment damage. Also, determine
whether any special inspection or preventive maintenance procedures or frequencies are recommended by
the manufacturer.
1.2
1. Qualitative tests
1.1
If the device is mounted on a stand or a cart,
examine the condition of the mount. Verify that
the mounting apparatus is secure and that all
hardware is firmly in place.
Chassis/Housing.
General. Verify that the key has not been left in
the laser. (Remove it if it has, and inform
users of the importance of storing the key in a
controlled location.) Examine any external
gas tanks that may be in use with the laser,
Mounts/Holders. Check that the mounts securely contain the gas cylinders. Be sure that
mounts or holders intended to secure the articulating arm to the chassis (to protect the arm
when the unit is not in use) are present, in good
working order, and being used. Similarly, check
mounts or holders for other devices (e.g., external power meters, footswitch).
1.3
Casters/Brakes. Verify that the casters roll and
swivel freely. Check the operation of brakes and
swivel locks.
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Inspection and Preventive Maintenance System
1.4
AC Plug/Receptacle. Examine the AC power
plug for damage. Wiggle the blades to determine
if they are secure. Shake the plug, and listen for
rattles that could indicate loose screws. If you
suspect damage, open the plug and inspect it.
1.5
Line Cords. Inspect line cords for signs of damage. If a cord is damaged, replace the entire cord
or, if the damage is very near one end, cut out
the defective portion. Be sure to wire a new
power cord or plug with the correct polarity.
1.6
Strain Reliefs. Examine the strain reliefs at
both ends of the line cord. Be sure that they grip
the cord securely.
1.7
Circuit Breakers/Fuses. If the device has a
switch-type circuit breaker, check that it moves
freely. If the device is protected by an external
fuse(s), check its value and type against what is
marked on the chassis or noted in the instruction
or service manual. Ensure that a spare is provided or readily available.
1.8
Tubes/Hoses. Check the condition of all coolingsystem hoses and any other hoses or tubing the
laser may have (e.g., drain, gas). Check that they
are of the correct type; that they have not become
cracked and do not show other signs of significant abuse; that they are connected correctly and
positioned so they will not leak, kink, trail on the
floor, or be caught in moving parts; and that they
are secured adequately to any connectors.
used with. Verify that suitable connectors are
supplied so that adapters are not required.
1.12 Filters. Check the condition of all liquid and air
filters. Clean or replace filters according to the
manufacturer’s recommendations (e.g., replace
if the pressure drop is >5 psi), and indicate this
in the preventive maintenance section of the
inspection form. Clean or replace air filters and
radiators that are obviously dirty.
1.13 Controls/Switches.
1.9
Cables. Inspect all cables and their channels or
strain reliefs for general physical condition. Examine cables carefully to detect breaks in insulation and to ensure that they are gripped
securely in the connectors at each end to prevent
strain on the cable.
1.10 Fittings/Connectors. Examine all gas and liquid fittings and connectors, as well as all electrical connectors, for general physical condition.
Gas and liquid fittings should be tight and not
leak. Electrical contacts should be straight,
clean, and bright. Pin indexed gas connectors
should be present. Ensure that no pins are missing and that the keying and indexing for each gas
to be used is correct.
If other hospital equipment will be attached
to the connector, be sure that the connectors
match. Lasers that connect to the central piped
medical gas system or to a freestanding medical
gas system should have the matching DISS or
quick-connect fitting for the gas that it is to be
4
General. Before moving any controls, check and
record their positions. If any position appears
unusual, consider the possibility of inappropriate use or of incipient device failure. Examine all controls and switches for physical
condition, secure mounting, and correct motion. If a control has fixed-limit stops, check
for proper alignment, as well as positive stopping. Check membrane switches for tape residue and for membrane damage (e.g., from
fingernails, pens, or surgical instruments). If
you find such evidence, notify users to avoid
using tape and sharp instruments. During the
inspection, be sure that each control and
switch works properly.
Remote. Examine the exterior of the control for
cleanliness and general physical condition.
Be sure that plastic housings are intact, that
assembly hardware is present and tight, and
that there are no signs of spilled fluids or other
serious abuse. If the remote control is attached by cable to the laser, ensure that the
cable and any connectors are in good condition. Examine all controls and switches for
general physical condition, secure mounting,
correct motion, and intended range of settings. Where a control should operate against
fixed-limit stops, check for proper alignment,
as well as positive stopping. During the
course of the inspection, be sure to check that
each control and switch performs properly.
Footswitch. Examine the footswitch for general
physical condition, including evidence of
spilled fluids. Footswitches for lasers include
internal switches that activate according to
the depth of pedal depression. It is usually
possible to feel the vibration caused by closure of the switch, even through a shoe.
Check that the internal switch is operating
and that the footswitch does not stick in the
On position. Some footswitches include two
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©1995 ECRI. All Rights Reserved.
Carbon Dioxide Surgical Lasers
internal switches; in this case, verify the operation of both.
During the procedure, check to be sure that
the laser activates consistently when the footswitch is depressed. Flex the cable at the
entry to the switch, and using an ohmmeter,
check for internal wire breaks that might
cause intermittent operation. During the procedure, check to be sure that the laser activates consistently when the footswitch is
depressed. Confirm that strain reliefs are secure.
Examine the male and female connectors for attaching the footswitch to the laser cabinet to be sure that no pins are bent
and that no other damage is present. Ensure that the connector secures acceptably
to the laser cabinet.
1.15 Motors/Pumps/Fans/Compressors. Check the
physical condition and proper operation of these
components. If lubrication is required, note this
in the preventive maintenance section of the
form. Clean any obvious dust from these
components.
1.16 Fluid Levels. Check all fluid (e.g., coolant) levels. Refill or change the fluid according to the
manufacturer’s recommendations, and note this
in the preventive maintenance section of the
form.
1.17 Battery. If the remote control is battery powered, check or replace the battery (periodic prophylactic battery replacement is often preferred
to risking battery failure during use). When it is
necessary to replace a battery, label it with the
date.
1.18 Indicators/Displays. During the course of the
inspection, verify proper operation of all lights,
indicators, meters, gauges, and visual displays
on the unit and the remote control. Ensure that
all segments of a digital display function. Note
any messages displayed during the power-on
self-test.
If primary and remote-control indicators and
displays can be used at the same time or if control
can be switched from one to the other during a
procedure, operate the laser in a way that will
verify that the same information (e.g., settings,
displays) is indicated on both controls.
If display screens or digital displays are provided for user prompts or for viewing accumulated
information (e.g., pulse or accumulated energy
counter), ensure that each display provides the
information expected. Ensure that user prompts
occur in the proper sequence. Store some sample
information, and verify that it is correct. If a
feature to manually reset this information is
available, ensure that it works.
1.20 Alarms/Interlocks. Operate the device in a
manner that will activate the self-check feature,
if present, and verify that all visual and audible
alarms activate according to the manufacturer’s
documentation. If no self-check feature is present, operate the laser in a manner that will
activate each audible and visual alarm; be sure
to test only those alarms that will not cause
damage to the laser or present an unnecessary
risk of laser beam exposure to yourself or bystanders.
If a door or window interlock is used, ensure
that it properly deactivates the laser. (Do not
disassemble major parts of the laser to test internal interlocks.) After deactivating the laser
and reclosing the door or window, check to be
sure that the laser will restart. Be sure to check
the interlocks in all locations where the laser is
used. (For some lasers, the function of the interlocks can be checked using an ohmmeter.)
If the laser is equipped with an emergency
“kill” switch, test this feature to be sure that it
deactivates the laser and that the laser will
subsequently restart.
1.21 Audible Signals. Operate the device to activate
any audible signals (e.g., laser emission, setting
change). Check for proper operation, and verify
that the signal can be heard in the environment
in which the laser will be used.
1.22 Labeling. Check that all placards, labels, and
instruction cards noted during acceptance testing (see Item 4.3) are present and legible. Check
to see that an instruction manual is kept with
the laser or is readily available.
1.23 Accessories.
General. Verify that all necessary accessories are
available and in good physical condition. Set
up each accessory with the laser to ensure
compatibility and proper functioning.
Checking all accessories during a single
inspection and preventive maintenance procedure is unnecessary as long as accessories
are routinely checked by the person(s) respon-
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Inspection and Preventive Maintenance System
are soluble in water. Carefully insert each
lens into the micromanipulator, and ensure
that it fits snugly.
sible for laser setup and operation. In addition, many of the accessories are sterile and
would require resterilization before use, making the laser potentially unavailable. Be sure
to check with the person responsible for
scheduling the use of the laser before beginning the procedure.
Handpieces. Examine each handpiece component (e.g., body, tips, lenses) for cleanliness
and general physical condition. Examine individually only those components that are intended for removal during normal use and
storage. (Do not remove other parts that are
press-fit or attached by screws, bolts, or snaprings.) If lenses are detachable, be sure not to
touch the lens surface; handle lenses by the
edges only. Consult the manufacturer’s recommendations for the procedures and cleaning agents to use to clean lenses. Avoid
exposing the lenses to water, since most CO2
lens materials are soluble in water.
Ensure that major subcomponents of the
handpiece, when assembled, are secure. Ensure that the mechanisms used to connect the
handpiece(s) to the articulating arm are in
good working order and that they reliably
secure each handpiece to the arm.
Microscope micromanipulator. Examine the microscope micromanipulator for cleanliness
and general physical condition. Be sure to
handle it by the main body; do not hold it by
the joystick, and do not touch the reflecting
lenses in the body. Inspect micromanipulators
provided by both the laser manufacturer and
the laser accessory manufacturers.
Ensure that the reflecting lenses are intact
and clean. Consult the manufacturer’s recommendations for the procedures and cleaning
agents to use to clean reflecting surfaces and
lenses.
Inspect the mechanism used to attach the
micromanipulator to the microscope to ensure
that all parts are present and that it is in good
working order. Connect the micromanipulator to
the microscope to check for a secure connection.
Inspect the mechanism used to attach the
micromanipulator to the articulating arm to
ensure that it is in good working order. Connect the micromanipulator to the articulating
arm to check for a secure connection.
1.24 Aiming Beam. Activate the aiming beam (without the therapeutic beam), and verify that it
produces a round, uniformly bright spot with no
halo. For handpieces that provide adjustable
spot sizes, verify that the spot size changes as
expected and still remains uniform. Check that
the intensity control, if present, does change the
brightness of the aiming beam. Similarly, check
pulsing controls to verify that the aiming beam
can be pulsed. If several color choices are available for the aiming beam, verify that each color
is present and working properly.
1.25 Gas Regulators. Examine the gas regulators (if
external to the cabinet) for cleanliness and general physical condition. Ensure that the gauges
on the regulators are not broken. While performing the preventive maintenance items, ensure that the regulator and the gauge operate as
expected. Verify that the correct gas is attached
to each regulator. Be sure that a key or wrench
to facilitate changing the gas supply is with the
unit or readily accessible.
2. Quantitative tests
2.1
Grounding Resistance. Use an ohmmeter, electrical safety analyzer, or multimeter with good
resolution of fractional ohms to measure and
record the resistance between the grounding pin
on the power cord and exposed (unpainted and
not anodized) metal on the chassis, accessory
outlet, ground pins, and footswitch. We recommend a maximum of 0.5 Ω. (If the footswitch is
of low voltage, grounding is not required.)
2.2
Leakage Current.
Examine the joystick to ensure that it is
firmly attached and that it freely moves the
reflecting lens. If a finger rest is present, ensure
that it is firmly attached and properly oriented.
If a zoom focus feature is present, be sure
that it turns easily and does not slip. Examine
each objective lens to ensure that it is intact
and clean. Do not touch the lens surface. Consult the manufacturer’s recommendations for
the procedures and cleaning agents to use to
clean the objective lenses. Avoid exposing the
lenses to water, since most CO2 lens materials
6
WARNING: Do not reverse power conductors
for this or any other test. Improper attachment
of conductors may damage the laser.
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©1995 ECRI. All Rights Reserved.
Carbon Dioxide Surgical Lasers
Repeat Pulse settings, if adjustable. Some laser
power meters can react quickly enough to be
used to test this feature of the laser. If you are
using such a power meter, test the laser to be
sure that the correct power is repeatedly delivered over the correct time period.
With the laser attached to a grounded powerdistribution system, measure the leakage current between the chassis and ground with the
unit grounded and ungrounded. The leakage
current on the chassis should not exceed 300 µA;
in no case should it exceed 500 µA. Where it is
greater than 300 µA, ensure that appropriate
grounding is present.
2.3
Exposure Duration. Some laser power meters
can measure pulse duration. If the power meters
can react to pulse duration (this is the preferred
circumstance), test the laser at each setting.
However, if the laser power meter does not measure pulse duration, use the following less preferable alternative.
Place and secure the laser handpiece with the
aiming beam focused on the target material (e.g.,
black Delrin, a tongue depressor). With the laser
set to about 5 W and the exposure setting at its
minimum duration, activate the laser and create
a burn. Carefully move the target material to
expose a clean area, maintaining the same distance. Adjust the exposure setting in increments
of 0.1 sec or the next longest duration, and activate the laser at each setting. Continue this
process until you have tested all exposure settings, except continuous, and developed a series
of burns. Compare the burns to verify that progressively larger burns occurred as the exposure
duration increased (see Fig. 1).
2.4
If your laser power meter cannot be used for
this test, use the following alternative test
method. Set the laser to about 5 W and a 0.1 sec
exposure duration with the fiber, handpiece, or
micromanipulator attached, and verify that the
Repeat Pulse feature operates as expected by
moving the target material slightly between
each pulse. Be extremely careful to keep hands
out of the laser beam path. You should obtain a
series of burn spots of similar density and size as
long as you maintain the same handpiece-totongue-depressor distance and angle relationships for each exposure and as long as the laser
is operating properly. If the number or duration
between repeat pulses is adjustable, test that
setting changes made throughout the range result in the expected performance.
Repeat Pulse. If the unit includes a Repeat Pulse
feature, which repeats the pulse at a fixed or
adjustable rate, test this feature with the laser
set at the minimum, median, and maximum
Figure 1. Tongue depressor with laser burns produced
during progressive exposure durations
2.5
Footswitch Exposure Control. Set the output
time for about 5 sec, activate the unit, and release the footswitch after about 1 sec. Verify that
the beam turns off when the footswitch is released.
2.6
Therapeutic and Aiming Beam Coincidence. CO2
surgical lasers include a He-Ne aiming laser and a
CO2 therapeutic laser. These two lasers should
create a spot at the same location. (It may be
convenient to perform this test in conjunction with
Item 2.7, since all reusable accessories will need to
be checked for both coincidence and pattern.)
First check beam coincidence and pattern
with the microscope manipulator, since this will
be more sensitive to misalignment and distortion
problems. To check concentricity of the two lasers, position the micromanipulator so the lasing
beam is perpendicular to the face of the wooden
tongue depressor and focused to its smallest spot
on the depressor. Circle the spot created by the
aiming laser. With the laser set at about 5 W
and an exposure duration of about 0.5 sec, activate the therapeutic laser, and compare the burn
created by the therapeutic laser on the tongue
depressor with the circled area. The burn and
the circled area should overlap (although not
necessarily be of the same size), and the center
of the burn and the center of the circle should be
in virtually the same location (see Fig. 2). The
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©1995 ECRI. All Rights Reserved.
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Inspection and Preventive Maintenance System
dirty mirror can disturb the beam pattern significantly and can affect the clinical performance
of the laser.
It is possible for the aiming and therapeutic
lasers to appear to be concentric and to develop
an even burn, despite a poor beam pattern; errors in mirror adjustment or dirt on the mirrors
can qualitatively seem to cancel each other. (In
this case, the maximum power [see Item 2.10]
that can be developed usually drops. Comparing
the results of this item’s testing with those of
Item 2.10 can help to pinpoint the source of the
problem.)
Figure 2. Circled He-Ne aiming beam spot (shaded) and
therapeutic laser spot (dark), demonstrating concentric
alignment (left) and poor alignment (right)
more the centers of the burn and circle diverge,
the poorer the alignment, and the greater the
risk that a surgeon will inadvertently irradiate
unintended tissue.
Lasers using mirrors in articulating arms are
subject to beam wander, in which concentricity
of the aiming and therapeutic laser may change
as the physical orientation of the articulating
arm (e.g., the angle or degree of rotation of one
arm section in relation to another section or the
chassis) changes. Hence, repeat this test with
the articulating arm in several physical configurations. If the aiming and therapeutic lasers
diverge significantly during any test, the system
requires complete alignment. (Alignment is very
difficult and should be performed only by qualified personnel.)
Repeat this testing with each reusable accessory, including handpieces, laser laparoscopes,
and laser bronchoscopes. Handpieces can be positioned and secured in the vise or ring stand. It
is not necessary to test the effect of manipulating
the articulating arm for each accessory. If a
problem is found in beam alignment or pattern
without a corresponding problem with the micromanipulator, the source of the problem is probably in the accessory.
2.7
8
Laser Beam Pattern. The spot created by a
therapeutic laser beam perpendicular to the target should be circular, and the energy throughout the spot should be fairly uniform. Laser beam
pattern is a measure of how well the mirrors of
the laser tube, articulating arm, and handpiece
are aligned and performing. A misaligned or
Beam pattern can be roughly assessed by
evaluating the uniformity of a burn on a tongue
depressor (as described in Item 2.6) or laser
thermal imaging paper or by using thermal imaging plates.
The surface of the thermal imaging plate is
exposed to an ultraviolet light, and the surface
fluoresces. When the therapeutic laser impacts
the surface, the thermal energy creates a beam
pattern that appears as a brown spot. Thermal
imaging plates may provide an indication of
beam pattern but do not provide a permanent
record for later comparison, may be difficult to
view with the aiming beam on, and may be easily
damaged if accidentally overexposed. The plates
are designed to respond to different power densities of CO2 laser energy. To minimize the risk
of damaging a plate’s surface, always start with
the least sensitive surface. Also, do not focus the
beam on the surface.
Position the target beyond the point of focus
to expand the spot, thereby decreasing the power
density in the spot. The beam must be perpendicular to the target surface. When using laser
paper, the laser should be set at about 5 W and
operated in the Pulsed mode at a 0.1 sec exposure
setting or the nearest available setting. The burn
(or spot on an imaging plate) should be fairly
consistent in darkness throughout and circular
in shape (see Fig. 3).
Some laser delivery systems (e.g., micromanipulators) provide features that allow the user
to change the spot size. Measuring absolute spot
size from a laser is difficult, results are not
always comparable, and the cost of equipment
exceeds the expected benefits to an inspection
program. However, measuring relative change
in spot size caused, for example, by changing
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©1995 ECRI. All Rights Reserved.
Carbon Dioxide Surgical Lasers
Because of the heightened risk associated with an
unfocused, nondiverging laser beam, exercise
great care if the interlocks are to be defeated.
With the laser set at a low (e.g., 10% of full scale),
medium (e.g., 50% of full scale), and maximum
output, activate the laser for a sufficient period to
acquire acceptable readings. (Power meters use
different time constants to acquire an acceptable
reading, and you must know and meticulously
follow the power meter’s instructions for use.)
Compare the reading obtained with the power
display of the laser; the measured and displayed
values should all be within 10% of one another. In
addition, compare the reading with the reading
taken on incoming acceptance testing, at the last
preventive maintenance procedure, or after the
last service procedure; a significant change in output may indicate the need for service. If the laser
includes a low-power (e.g., mW) feature, test it in
a similar fashion with a power meter of appropriate low-power resolution.
Figure 3. Acceptable therapeutic beam pattern (left) and
unacceptable (right)
lenses or the aperture setting on micromanipulators is worthwhile and can be accomplished
without undue cost.
You can evaluate the change in relative spot
size using either of the test methods detailed
above (i.e., using a thermal imaging plate or
laser paper). If you use different lenses to
change the spot size, expose the thermal imaging
plate or laser paper to the focused beam created
when using each lens, and compare the relative
spot size, spot shape, and beam uniformity of the
images or imprints. If you use fixed points or
continuously variable aperture control to change
the spot size, expose the thermal imaging plate
or laser paper to the focused beam created when
the aperture control is set at its minimum, median, and maximum aperture settings. Compare
relative spot size, spot shape, and beam uniformity.
2.10 Power Output. Place and secure the laser handpiece or aperture of the articulating arm at the
appropriate distance from the laser power meter to meet spot-size requirements specified in
the instructions with the meter. (Some power
meters require that the aperture of the articulating arm be inserted into or placed in direct
contact with the power meter. If the handpiece
is used on these meters, the meter may be damaged by the high power density caused by the
focused beam.)
WARNING: Accessing the unfocused laser
beam may require defeating internal interlocks.
3. Preventive maintenance
Verify that all daily preventive maintenance procedures recommended by the manufacturer are carried
out.
3.1
Clean the exterior. Clean accessible optical components (e.g., microscope lenses) if necessary,
using techniques and cleaning solutions recommended by the manufacturer.
3.2
Lubricate the telescoping column and any motor, pump, fan, compressor, or printer components with the lubricant recommended by the
manufacturer.
3.3
Calibrate/adjust any components (e.g., printer)
according to manufacturer recommendations.
Only appropriately trained personnel should attempt laser adjustments. Ensure that all hoses
and tubes are tight.
3.4
Replace filters, if needed. Check all fluid levels
and supplement or replace fluids if needed.
4. Acceptance tests
Conduct major inspection tests for this procedure
and the appropriate tests in the General Devices Procedure/Checklist 438.
WARNING: Lasers may be damaged by switching
between normal and reverse polarity while the device is
on. If reverse-polarity leakage current measurements
are made, turn off the unit being tested before switching
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Inspection and Preventive Maintenance System
polarity. Also, lasers powered by three-phase electrical
systems may be damaged if proper electrical phase
connections are not made initially and maintained
thereafter. Thus, do not switch conductor connections
or wiring configurations for any tests, including leakage current measurement. Do not conduct electrical
leakage current tests with reversed-polarity wiring.
proper electrical configuration (e.g., proper neutral and ground connections, proper phase rotation) has been installed. Connect the laser to
each receptacle and confirm that the laser operates properly, specifically confirming that motors are operating in the proper direction.
4.5
AC Plug. Verify that the plug is acceptable for
use with the maximum current and voltage
specifications for operating the laser. (Consult
National Electrical Manufacturers Association
[NEMA] configurations for general-purpose nonlocking connectors if in doubt.)
4.6
Pulse Duration. If the laser includes an enhanced pulse feature and the pulse duration is
adjustable, verify that progressive increases in
pulse duration throughout its range of adjustment result in progressively larger burns.
4.7
Repeat Pulse. If the laser includes a Repeat
Pulse feature, test this feature as described in
Item 2.4, but over the full range of available
settings.
4.8
Power Range. Test the power output accuracy,
using the technique described in Item 2.10, at
several low, medium, and high settings. If the
laser includes an enhanced pulse feature, verify
that adjusting the power setting incrementally
through its full range produces the expected
effect on a tongue depressor. For all tests using
high continuous-wave or Superpulse, it is particularly important to use a firebrick behind the
tongue depressor for added safety.
The handpiece (which could conceivably come into
contact with a patient’s heart) should meet the criteria
for isolated input devices.
Also test the ability of the laser to deliver laser
energy as expected in all configurations and with all
provided laser accessories. In addition, perform the
following tests.
4.1
4.2
Areas of Use. Visit the area(s) in which the laser
is to be used, and ensure that laser signs, laser
safety eyewear, and window coverings are available and being used and that safety interlocks
for doors or windows, if present, are functioning
properly.
Casters/Mounts/Holders. Ensure that the assembly is stable and that the unit will not tip
over when pushed or when a caster is jammed on
an obstacle (e.g., a line cord threshold), as may
occur during transport. If the device is designed
to rest on a shelf, ensure that it has nonslip legs
or supports.
4.3
Labeling. Examine the unit and note the presence, location, and content of all labels. Labeling
information is typically found in the laser’s operator manual.
4.4
Electrical Wiring Configuration. Ensure that
the branch circuits and the outlets for the laser
are properly wired and rated for use with the
laser. Examine the receptacles at each location
where the laser is to be used to ensure that the
10
Before returning to use
Be sure to return controls to their starting position,
and place a Caution tag in a prominent position so that
the next user will be careful to verify control settings,
setup, and function before using the unit.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Procedure/Checklist 421-0595
Cardiac Resuscitators
Used For:
Resuscitators, Cardiac [13-361]
Also Called: External cardiac compressor, Thumper (registered trademark of Michigan Instruments, Inc., to
be used only when referring to that device)
Commonly Used In: Emergency departments, critical care areas, ambulances
Scope: Applies to cardiac resuscitators; does not apply to cardiac presses that are not pneumatically powered
Risk Level: ECRI Recommended, High; Hospital Assessment,
Type
ECRI-Recommended
Interval
Interval Used
By Hospital
Major
12 months*
months
.
hours
Minor
NA
months
.
hours
Time Required
*An interval of 6 months should be considered if a resuscitator is frequently used and/or located in an ambulance.
Overview
Test apparatus and supplies
Pneumatically powered cardiac resuscitators are used
during emergency cardiopulmonary resuscitation
(CPR) as an alternative to manual cardiac compression. They can provide consistent cardiac compression,
with adequate sternal depression and rhythmic compression rates, as well as oxygen-enriched ventilation.
By eliminating the need to rotate personnel for the
fatiguing task of cardiac compression, these devices
reduce the number of people required to maintain
support of the patient.
Use of pneumatically powered cardiac resuscitators does not eliminate the need to train hospital and
ambulance personnel in effective airway maintenance, manual external cardiac compression, and
mouth-to-mouth breathing. In all cases, the patient
must be maintained by manual techniques until the
cardiac resuscitator is available, applied, and placed
in operation.
Citations from Health Devices
External cardiac compressors [Evaluation], 1973 Apr;
2:136-50.
009010
421-0595
A NONPROFIT AGENCY
Pressure gauge or meter with a range of at least
0 to 80 cm H2O
Spirometer or gasometer
Beam balance patient floor scale
Stopwatch or watch with a second hand
Ruler
Special precautions
Never oil any part of an oxygen-powered cardiac
compressor. Oil in the presence of oxygen is a dangerous fire and explosion hazard.
Procedure
Before beginning an inspection, carefully read this
procedure and the manufacturer’s instruction and service manuals; be sure that you understand how to operate the equipment and the significance of each control
and indicator. Also determine whether any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer.
5200 Butler Pike, Plymouth Meeting, PA 19462-1298, USA
Telephone +1 (610) 825-6000 ● Fax +1 (610) 834-1275
●
E-mail [email protected]
Inspection and Preventive Maintenance System
make it more versatile for a wider range of
patients.
1. Qualitative tests
1.1
Chassis/Housing. Examine the exterior of the
unit for cleanliness and general physical condition. Be sure that plastic housings are intact,
that all assembly hardware is present and tight,
and that there are no signs of spilled liquids or
other serious abuse.
1.2
Mount. If the device is mounted on a stand or
cart, examine the condition of the mount.
1.8
Tubes/Hoses. Check the condition of all tubing
and hoses. Be sure that they are not cracked,
kinked, or dirty.
1.10 Fittings/Connectors. Confirm that appropriate
quick-connect fittings are being used with corresponding gases. Observe that pin-index safety
system pins are present and intact.
1.13 Controls/Switches. Before moving any controls,
check their positions. If any of them appear
inordinate, consider the possibility of inappropriate clinical use or of incipient device failure.
Record the settings of those controls that should
be returned to their original positions following
the inspection.
Examine all controls and switches for physical
condition, secure mounting, and correct motion.
Where a control should operate against fixedlimit stops, check for proper alignment as well as
positive stopping. During the course of the inspection, be sure to check that each control and
switch performs its proper function.
1.18 Indicators/Displays. During the course of the
inspection, confirm the operation of all indicators, gauges, and visual displays on the unit.
Use only transparent masks with resuscitators. If opaque masks are in use, order
transparent replacements but do not remove
opaque masks from use until replacements
are available and the change has been discussed with users.
Inspect the masks for signs of deterioration.
Reinflate inflatable rims if they are collapsed,
and check for leaks or damage by immersing the
mask in water. Replace if necessary.
1.24 Ventilation Hose Fitting. Verify that the ventilation hose terminates at the patient end in a
standard 15/22 mm coupling to allow connection
to a standard ventilator mask and tracheal or
tracheostomy tube. If it does not, an adapter
should be provided.
2. Quantitative tests
2.3
Compression Rate with Ventilation. Using a
stopwatch or watch with a second hand, count the
number of compressions over a 1 min period. If
the unit includes a ventilator, count the number
of compressions per minute with it operating. The
compression rate, unless otherwise specified by
the manufacturer, should be in accordance with
AHA/ARC two-person CPR standards (i.e., 60 to
80/min).
2.4
Piston Displacement. With the unit not operating, check that the compression piston moves
freely in and out of its cylinder. The maximum
displacement should not exceed 5 cm (2 in).
2.5
Compression Force. Position the compression
piston on the weighing platform of a conventional patient floor scale by tilting the scale back
and sliding the compressor base plate under the
platform. If the scale is at a significant angle
from its original position, use blocks or other
objects to level it again.
1.22 Labeling. Check that all necessary placards, labels, conversion charts, and instruction cards
are present and legible.
1.23 Accessories. List the accessories that are to be
stored with each resuscitator. Check that the
items on the accessories list are found with the
resuscitator at each inspection. Examine all accessories for cleanliness and mechanical integrity.
Cylinders. If an oxygen cylinder is stored with
the resuscitator, check the amount of oxygen
it contains. Maintain a full cylinder with the
unit. A cylinder wrench should be chained to
the regulator and yoke assembly.
Masks. An assortment of masks (e.g., adult, infant) should be stored with the resuscitator to
2
Connect the compressor to its normal oxygen
source. Set the scale to 45 kg (100 lb) and adjust
the compression force control to its maximum
point. Activate the compressor. It should raise
the balance beam.
2.6
Ventilator Regulation. Determine if the ventilation gauge measures pressure (cm H2O) or volume (cc). If the gauge measures pressure,
connect the ventilator output to a pressure gauge
or meter or a water manometer and compare the
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Cardiac Resuscitators
measured ventilation pressure to that indicated
on the gauge at 30 and 50 cm H2O. If the gauge
measures volume, connect the ventilator output
to a spirometer or gasometer. Compare the
measured ventilation volume to that indicated
on the unit’s gauge at the 1 L setting. The
difference between measured and indicated values should not exceed 20%. (Such high errors
are tolerable in short-term emergency equipment but would not be acceptable in other ventilators.)
2.7
2.8
Inspiratory Pressure. Connect the patient end of
the ventilator tubing to a pressure gauge or
meter. Adjust the ventilator control to its maximum setting and measure the maximum ventilatory pressure. It should not exceed 60 cm H2O.
This test confirms operation of the inspiratory
pressure-relief valve.
Ventilator Volume Output. Connect the output
of the ventilator to a spirometer or gasometer.
Adjust the ventilator control to its maximum
setting and measure the maximum inspiratory
volume. It should be at least 1.5 L.
2.9
Compression/Ventilation Ratio. With the compressor and ventilator operating, count the
number of piston thrusts between each ventilation. There should be five compressions per
ventilation.
3. Preventive maintenance
3.1
Clean the exterior.
4. Acceptance tests
Conduct major inspection tests for this procedure.
Before returning to use
Make sure controls are set at normal positions and
oxygen cylinders are turned off. Place a Caution tag
in a prominent position so that the next user will be
careful to verify control settings, setup, and function
before use.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
3
Procedure/Checklist 456-0595
Centrifuges
Used For:
Centrifuges [10-778]
Centrifuges, Blood Bank [15-115]
Centrifuges, Cell Washing, Automatic [16-815]
Centrifuges, Cytological [16-765]
Centrifuges, Floor [15-116]
Centrifuges, Floor, Nonrefrigerated [17-177]
Centrifuges, Microhematocrit [10-779]
Centrifuges, Refrigerated [15-117]
Centrifuges, Tabletop [10-780]
Microcentrifuges [17-452]
Ultracentrifuges [15-193]
Commonly Used In: General clinical laboratories, as well as specific laboratory departments (e.g., blood
bank, hematology, clinical chemistry)
Scope: Applies to all types of centrifuges
Risk Level: ECRI Recommended, Medium; Hospital Assessment,
Type
ECRI-Recommended
Interval
Major
12 months
months
.
hours
Minor
NA
months
.
hours
Overview
Centrifuges use centrifugal force to separate suspended
particles from a liquid or to separate liquids of various
densities. These liquids can include body fluids (blood,
serum, urine), commercial reagents, or combinations of
the two with other additives. Centrifugation is used for
most sample preparations in a clinical laboratory.
There are three general classifications of centrifuges:
low speed (≤6,000 rpm), high speed (6,000 to 25,000 rpm),
and ultraspeed (25,000 to 110,000 rpm). These three types
of centrifuges are available as tabletop and/or floor models,
and some are refrigerated units. Microhematocrit centrifuges are specialized centrifuges used in a hematology
department to determine an accurate packed cell volume
of red blood cells. The speed of a microhematocrit centrifuge ranges from 7,000 to 15,000 rpm.
236945
456-0595
A NONPROFIT AGENCY
Interval Used
By Hospital
Time Required
Certain hazards are associated with the operation of
centrifuges. Sample tubes may break; breakage is most
likely to occur if manufacturers’ instructions, such as
using correct tube sizes and locations and using cushions,
are not followed. Rotors may detach or fail, possibly
because of a loose retaining nut or imbalanced tube
placement; rotor or tube failures may result in operator
exposure to physical or infectious hazards. Aerosols may
be created from the samples. Or the operator may be
harmed while attempting to slow down or stop the rotor
by hand. Therefore, the lid should never be opened while
the rotor is spinning, and safety inner protective lids
should be used when available.
Hazards also exist when the centrifuge is not in
operation; for example, broken glass, possibly contaminated with blood, may be found inside the centrifuge
during cleaning or IPM.
5200 Butler Pike, Plymouth Meeting, PA 19462-1298, USA
Telephone +1 (610) 825-6000 ● Fax +1 (610) 834-1275
●
E-mail [email protected]
Inspection and Preventive Maintenance System
In addition to careful adherence to use and maintenance instructions, equipment with appropriate safeguards should be used. As a minimum, units should
have a lid and a latch that will prevent the lid from
opening in the event of a failure while the rotor is
spinning. A safety interlock, which permits the lid to
be opened only after the rotor has stopped (or reached
a very low speed), is preferred, and all new units should
have this feature.
Laboratory personnel are required by the College of
American Pathologists (CAP) to do the following:
Clean and properly maintain all centrifuges. (Note:
Contact the manufacturer for guidance if the operator’s manual does not specify cleaning or disinfecting agents. Prolonged contact with some
disinfection solutions [e.g., 10% sodium hypochlorite] may damage the rotor and other centrifuge
components; ensure that such solutions are removed by rinsing well with water.)
Check and record timer accuracy monthly.
Check and record speed (rpm) accuracy monthly
(critical use) or quarterly.
Check and record built-in tachometer monthly.
(Note: Operators should refer to CAP’s Laboratory
Instrument Evaluation Verification & Maintenance
Manual, 4th edition, 1989.)
Citations from Health Devices
Tabletop centrifuges [User Experience NetworkTM],
1987 Feb; 16(2):55.
IEC DPR-6000 refrigerated centrifuges [User Experience NetworkTM], 1987 Jul; 16(7):255.
Missing roll pin from Beckman Spinchron centrifuge
rotor [User Experience NetworkTM], 1992 May;
21(5):182.
Risks from centrifuges [Hazard], 1992 Aug; 21(8):290.
Improper sealing of Baxter Megafuge C1725-2 centrifuges [Hazard], 1992 Sep; 21(9):331.
Centrifuges [Hazard summary], 1992 Dec; 21(12):459.
Centrifuges [Hazard report summary], 1995 Apr; 24:
158-9.
Test Apparatus and Supplies
Wrench to tighten the rotor nut
Leakage current meter or electrical safety analyzer
Ground resistance ohmmeter
Stopwatch or watch with a second hand
2
Electronic thermometer accurate to 0.5°C (for
refrigerated units only)
Tachometer or phototachometer
Special Precautions
Check with laboratory personnel before performing
any maintenance or shipping centrifuges to the manufacturer for repair. Laboratory personnel should have
properly decontaminated the centrifuge. A centrifuge
should be vacuumed out before any testing is started.
(Broken glass, which may be contaminated with blood,
is sometimes found inside. In addition, visible blood
may be located on or in the centrifuge.)
Be careful not to touch a spinning rotor if an interlock fails or if you are operating the unit with the lid
open. NEVER attempt to stop a moving rotor with your
hands or with a tool or object.
Ensure that the centrifuge tubes are properly balanced and that the speed and tube length are in accordance with the tube and centrifuge manufacturers’
recommendations. Use proper-sized tubes for the rotor. If using a swinging-bucket rotor, ensure that the
tubes are placed in accordance with the manufacturer’s instructions; long tubes (e.g., 100 mm) placed
in the corner tube holders closest to the rotor shaft will
probably break when the rotor buckets swing out.
ALWAYS follow universal precautions when centrifuging blood or body fluids. These precautions include
wearing gloves, face protection (e.g., shields), gowns or
laboratory coats, and plastic aprons, and are described
in detail in the National Committee for Clinical Laboratory Standards (NCCLS) Document M29-T2, Vol. 11,
No. 14, Protection of Laboratory Workers from Infectious Disease Transmitted by Blood, Body Fluids, and
Tissue (tentative guideline),* as well as in the Occupational Safety and Health Administration’s (OSHA)
bloodborne pathogens standard.**
Procedure
Before beginning an inspection, carefully read this
procedure and the manufacturer’s instruction and
service manuals; be sure that you understand how to
operate the equipment, the significance of each control
and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive
maintenance procedures or frequencies are recommended by the manufacturer.
* This document can be obtained from the NCCLS, 771 E. Lancaster
Ave., Villanova PA 19085; (610) 525-2435.
** Occupational exposure to bloodborne pathogens. Fed Regist 1991
Dec 6; 56(235):64004-182.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Centrifuges
1.1
Chassis/Housing. Examine the exterior of the
unit for cleanliness and general physical condition. Be sure that plastic housings are intact,
that all hardware is present and tight, and that
there are no signs of spilled liquids or other
serious abuse.
1.2
Mount/Fasteners. If the device is mounted on a
stand, examine its condition. If it rests on a shelf,
check the security of the shelf. If units have
suction-type feet, check the integrity of the feet.
1.4
AC Plug. Examine the AC power plug for damage.
Attempt to wiggle the blades to check that they are
secure. Shake the plug and listen for rattles that
could indicate loose screws. If any damage is suspected, open the plug and inspect it.
1.15 Motor/Rotor/Pump. Check the physical condition and proper operation of these components.
Check the brushes, commutator, and bearings of
the motor. Check the condition of gaskets, seals,
and mounts. Check the rotor for balance and the
condition of trunnion bearings, and check the
rotor attachment for tightness and excessive
wear. (Note: If using an ultraspeed centrifuge,
follow the manufacturer’s derating schedule for
the rotor. It should be outlined in the operator’s
manual.) Clean and lubricate components as required, and note this on Lines 3.1 and 3.2 of the
inspection form (however, do not check these
items until all necessary cleaning and lubrication are completed). If a unit has a vacuum or
diffusion pump, check its condition, and perform
appropriate maintenance according to the
manufacturer’s specifications.
1.5
Line Cord. Inspect the cord for signs of damage.
If damaged, replace the entire cord or, if the
damage is near one end, cut out the defective
portion. Be sure to wire a new power cord or plug
with the correct polarity.
1.18 Indicators/Displays. During the course of the
inspection, confirm the operation of all lights,
indicators, meters, gauges, and visual displays
on the unit. Be sure that all segments of a digital
display illuminate and function properly.
1.6
Strain Reliefs. Examine the strain reliefs at
both ends of the line cord. Be sure that they hold
the cord securely. If the line cord is detachable
(by the user), attach the cord to the unit so that
it cannot be easily removed. (See Health Devices
1993 May-Jun; 22[5-6]:301-3.)
1.7
Circuit Breaker/Fuse. If the device has a
switch-type circuit breaker, check that it moves
freely. If the device is protected by an external
fuse, check its value and type against those
marked on the chassis and ensure that a spare
is provided.
1.20 Alarms/Interlocks. Induce alarm conditions,
and verify that alarms are activated. Refrigerated units should indicate whether the unit is at
the appropriate temperature. Check the lid
latching mechanism for wear, and verify that it
holds the lid securely. A lid interlock should
either shut off the motor when the lid is opened
or keep the lid latched until the rotor has
stopped. The centrifuge should not start with the
lid open. If the lid can be opened with the rotor
spinning at high speed, check for appropriate
labeling on or near the centrifuge, warning the
operator not to open the centrifuge lid during
operation. If the lid can be opened while the
centrifuge rotor spins at a low speed, the buckets
or rotor should have an inner protective lid.
Replace or modify any centrifuges that lack a
latch. Do not use centrifuges that lack a lid; if a
lid is retrofitted, it should have a safety latch.
1. Qualitative tests
1.13 Controls/Switches. Before changing any controls, consider the possibility of inappropriate
clinical use or of incipient device failure. Record
the settings of those controls that should be
returned to their original positions following the
inspection.
Examine all controls and switches for physical
condition, secure mounting, and correct motion.
Check that control knobs have not slipped on
their shafts. Where a control should operate
against fixed-limit stops, check for proper alignment, as well as positive stopping. Check membrane switches for membrane damage (e.g., from
fingernails, pens). During the course of the inspection, be sure to check that each control and
switch performs its proper function.
1.21 Audible Signals. Operate the device to activate
any audible signals. Confirm appropriate volume, as well as the operation of a volume control,
if so equipped.
1.22 Labeling. Check that all necessary placards, labels, conversion charts, and instruction cards
are present and legible.
1.23 Accessories. Confirm the presence and condition
of accessories (e.g., sample buckets, sample
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
3
Inspection and Preventive Maintenance System
holders). Check for the proper type of accessory
(e.g., proper-sized tubes for the buckets used).
Check that every tube holder has a cushion. If
protective lids for the buckets or the rotor (inner
safety lid) are available for that model centrifuge, verify that they are kept with the centrifuges and are routinely used; also ensure that
the protective lids form a tight seal and positively lock onto the bucket.
1.24 Brake. Check the action of the mechanical or
electrical brake. When the brake is applied (e.g.,
by pushing the STOP button), the centrifuge
should decelerate smoothly.
2. Quantitative tests
2.1
2.2
Grounding Resistance. Using an ohmmeter,
electrical safety analyzer, or multimeter with
good resolution of fractional ohms, measure and
record the resistance between the grounding pin
of the power cord and exposed (unpainted and not
anodized) metal on the chassis. We recommend a
maximum of 0.5 Ω. If the device is double insulated, grounding resistance need not be measured; indicate “DI” instead of the ground
resistance value.
Leakage Current. Measure chassis leakage current to ground with the grounding conductor of
plug-connected equipment temporarily opened.
Operate the device in all normal modes, including on, standby, and off, and record the maximum leakage current. If the unit has heating
and cooling modes, set the thermostats so that
each operates while taking measurements.
Chassis leakage current to ground should not
exceed 500 µA.
2.10 Temperature Accuracy. Check the temperature
control on refrigerated centrifuges using an electronic thermometer. Place the electronic thermometer probe in the centrifuge bowl near the
automatic temperature control sensor. (Refer to
the manufacturer’s specifications to determine
where the temperature control sensor is located.)
Close the centrifuge, sealing the gasket around
the thermometer cable. Compare the temperature control with the electronic thermometer at
each setting or at the settings being used. The
readings should not differ by more than ±3°C.
2.11 Timer Accuracy. Check the timer against a stopwatch or watch with a second hand. A centrifuge
4
should not vary by more than ±10%. Depending
on various state regulations, this value may need
to be recorded on the inspection tag.
2.12 Accuracy of Speed Setting. Determine the range
of speeds at which the centrifuge is used and a
typical load (e.g., number of filled containers). Set
the centrifuge to two or three speeds, and measure the different speeds using a tachometer. If a
unit has an opaque cover, refer to the manufacturer’s service manual to check the speed accuracy. (Note: A vibrating reed-type tachometer
may be used with most centrifuges with opaque
covers.) The measured speed should not vary by
more than ±10% of the displayed speed. (Note: If
brushes have been changed, check speed settings
after brushes are properly replaced.)
3. Preventive maintenance
3.1
Clean exterior (interior if appropriate).
3.2
Lubricate per manufacturer’s instructions.
3.4
Replace brushes, brake, gaskets, seals, and vacuum pump, if needed. (For the proper procedure
for replacing brushes, refer to the manufacturer’s manual and to the CAP Laboratory Instrument Evaluation Verification & Maintenance
Manual.)
4. Acceptance tests
Conduct major inspection tests for this procedure
and the appropriate tests in the General Devices Procedure/Checklist 438. All new centrifuges should have
a lid and a safety interlock that prevents the lid from
being opened while the rotor is spinning at high
speeds. Purchase only those centrifuges on which the
rotor stops completely before the lid can be opened
and/or, for units that operate at a low speed, those that
have a protective lid for the buckets or an inner safety
lid for the rotor. Give preference to those centrifuges
that have protective lids for the buckets or rotor. If the
units being purchased allow the lid to be opened while
the rotor is spinning at low speeds, protective lids
should be included.
Before Returning to Use
Make sure controls are set in their normal pre-use
positions.
Attach a caution tag in a prominent position to alert
the user that control settings may have been changed.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Procedure/Checklist 412-0595
Circulating-Fluid Pumps
Used For:
Pumps, Circulating-Fluid, Localized Heat [17-647]
Also Called: Heating pads; K-Module, a registered trademark of Baxter to be used only when referring to
that device; T-Pump, a registered trademark of Gaymar Industries Inc. to be used only when referring to that
device
Commonly Used In: Most patient care areas
Scope: Applies to circulating-fluid heating pad pumps
Risk Level: ECRI Recommended, Low; Hospital Assessment,
Type
ECRI-Recommended
Interval
Interval Used
By Hospital
Major
12 months
months
.
hours
Minor
NA
months
.
hours
Time Required
Overview
Citations from Health Devices
Circulating-fluid pumps and pads are used for applying long-term mild heating to the skin.
Circulating-fluid pumps and heating pads [Evaluation], 1989 May; 18:154-73.
A fluid pump consists of a reservoir that holds a
supply of distilled water; a heater, mounted in the
reservoir, that warms the fluid; a pump that circulates
the fluid to the heating pad; a controller that maintains the fluid temperature; and safety devices that
deactivate the unit if the fluid temperature exceeds
the maximum allowable temperature limit. The
pump circulates the distilled water through a plastic
pad; the pad is placed under or on the skin to allow
conductive heat flow.
Heating pads are available in three types: all-plastic single-patient-use, some of which can be reused;
covered single-patient-use, which have a layer of fabric bonded to their surface; and all-plastic reusable,
made from thick plastic sheets to resist wear and
improve durability (these come with a repair kit).
Pads are constructed from two plastic sheets that are
heat-sealed together; each manufacturer uses a
unique flow pattern.
009064
412-0595
A NONPROFIT AGENCY
Circulating-fluid pumps and heating pads [Evaluation
Update], 1989 Dec; 18:418.
Circulating-fluid pumps: Do not use for ECMO [Hazard], 1992 Jan; 21:39.
Test apparatus and supplies
Ground resistance ohmmeter
Leakage current meter or electrical safety analyzer
Shunt thermometer with appropriate connectors to
install in series with the pump and heating pad to
check the temperature of the circulating fluid (temperature calibration assemblies may be available
from manufacturers of circulating-fluid pumps and
may be used in place of the temperature-measuring
procedure described in Item 2.4)
Flowmeter (0 to 20 gallons per hour [gph] range)
with water
Heating pad
5200 Butler Pike, Plymouth Meeting, PA 19462-1298, USA
Telephone +1 (610) 825-6000 ● Fax +1 (610) 834-1275
●
E-mail [email protected]
Inspection and Preventive Maintenance System
portion. Be sure to wire a new power cord or plug
with the correct polarity.
Special precautions
Some testing requires disabling temperature control
circuits; to avoid damage to the unit, this testing should
be performed only by qualified personnel familiar with
unit design. Although we hesitate recommending such
wiring modifications as part of a routine inspection
procedure because unskilled personnel may inadvertently damage the unit, there may be no other way to
determine whether the backup thermostat or overtemperature alarms are functional. Personnel responsible
for inspecting heating pads must recognize their own
limitations and, where appropriate, seek qualified help
when performing this test. Return the unit to its normal
operating condition immediately after completing the
test. Performing the operating temperature test (Item
2.4) after the high-temperature protection test (Item
2.3) will help ensure that the device has been correctly
returned to its proper operating condition.
Procedure
Before beginning an inspection, carefully read this
procedure and the manufacturer’s instruction and
service manuals; be sure that you understand how to
operate the equipment, the significance of each control
and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive
maintenance procedures or frequencies are recommended by the manufacturer.
1. Qualitative tests
1.1
Chassis/Housing. Examine the exterior of the
unit for cleanliness and general physical condition. Be sure that plastic housings are intact,
that necessary assembly hardware is present
and tight, and that there are no signs of spilled
liquids or other serious abuse.
1.2
Mount/Fasteners. If the device is mounted on a
stand or bracket, examine the condition of the
mount. Verify that the mounting apparatus is
secure and that all hardware is firmly in place.
Check for weld cracks. Ensure that the assembly is stable.
1.4
AC Plug. Examine the AC power plug for damage. Attempt to wiggle the blades to determine
that they are secure. Shake the plug and listen
for rattles that could indicate loose screws. If
any damage is suspected, open the plug and
inspect it.
1.5
2
Line Cord. Inspect the cord for signs of damage.
If damaged, replace the entire cord, or, if the
damage is near one end, cut out the defective
1.6
Strain Reliefs. Examine the strain reliefs at
both ends of the line cord. Be sure that they hold
the cord securely.
1.7
Circuit Breaker/Fuse. If the device has a
switch-type circuit breaker, check that it moves
freely. If the device is protected by an external
fuse, check its value and type against that
marked on the chassis, and ensure that a spare
is provided.
1.8
Tubes/Hoses. Check the condition of all tubing
and hoses. Be sure that they are not cracked,
kinked, or dirty.
1.10 Fittings/Connectors. Examine liquid fittings
and connectors, as well as all electrical cable
connectors, for general condition.
1.13 Controls/Switches. Before moving any controls,
check their positions. If any of them appear
inordinate (e.g., a temperature control at maximum), consider the possibility of inappropriate
clinical use or of incipient device failure. Record
the settings of those controls that should be
returned to their original positions following the
inspection.
Examine all controls and switches for physical
condition, secure mounting, and correct motion.
Where a control should operate against fixedlimit stops, check for proper alignment, as well
as positive stopping. Check membrane switches
for membrane damage (e.g., from fingernails,
pens). During the course of the inspection, be
sure to check that each control and switch performs its proper function.
1.14 Heater. Operate it to be sure that its controls
function properly (e.g., that a variable temperature control does, in fact, determine the amount
of heating; that On/Off controls work). Verify
that the pad warms up when the unit is operated
to ensure that the heater and the pump are
functioning.
1.15 Motor/Pump/Fan. Check physical condition
and for proper operation.
1.16 Fluid Levels. Check all fluid levels. Replenish
any fluids that are low.
1.18 Indicators/Displays. During the course of the
inspection, confirm the operation of all lights,
indicators, or visual displays on the unit.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Circulating-Fluid Pumps
Determine from the manufacturer’s literature
how backup thermostats can be tested. Connect
the shunt thermometer in series with the input
line to the heating pad. Record the maximum
water temperature for each backup thermostat,
and note any alarms or indicators. Maximum
temperatures should be within the manufacturer’s specified range, but should not exceed
43°C. Remove any bypasses installed for this test.
1.20 Alarms. Many units have low-water-level and
high-temperature alarms. Operate the unit in
such a way as to activate the low-water-level
alarm and any other audible and visual alarms
(e.g., tilt). Verification of the high-temperature
alarm requires abnormal operating conditions
that will be simulated in Item 2.3.
1.22 Labeling. Check that all necessary placards, labels, and instruction cards are present and legible.
1.23 Accessories. Verify that the pad is clean, free of
leaks, and stored without sharp folds or creases.
Also verify the presence and operation of a key
for adjusting fluid temperature.
2. Quantitative tests
2.1
2.2
2.3
Grounding Resistance. Using an ohmmeter,
electrical safety analyzer, or multimeter with
good resolution of fractional ohms, measure and
record the resistance between the grounding pin
of the power cord and exposed (unpainted and
not anodized) metal on the chassis. We recommend a maximum of 0.5 Ω.
Leakage Current. Measure chassis leakage current to the chassis of the device with the grounding conductor temporarily opened. Operate the
device in all normal modes, including on (with
the heater operating) and off, and record the
maximum leakage current. Leakage current
should not exceed 300 µA.
High-Temperature Protection. Circulating-fluid
pumps should have high-temperature protection
(backup thermostats) to limit the water temperature if the main temperature control fails.
2.4
Operating Temperature. Operate the pump at
37°C and at maximum control settings with the
thermometer shunt still installed as in Item 2.3.
Actual water temperature should be within 1°C
of the set temperatures.
2.5
Flow. Remove the temperature shunt, and place
a flowmeter (0 to 20 gph range) in series with the
input line to the heating pad. Record the flow
rate. The flow should exceed the minimum flow
specified by the manufacturer.
3. Preventive maintenance
3.1
Clean the exterior.
3.4
Flush/fill the reservoir, if needed.
4. Acceptance tests
Conduct major inspection tests for this procedure
and the appropriate tests in the General Devices Procedure/Checklist 438.
Before returning to use
Verify that any control circuits that were bypassed
or deactivated for testing purposes have been returned
to their normal operating condition.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
3
Procedure/Form 441-0595
Conductive Furniture and Floors
Used For:
Flooring, Conductive [15-832]
Used In: Operating rooms, other flammable anesthetizing locations
Scope: Complies with the requirements for periodic testing of conductive casters on equipment and furniture
used in flammable anesthetizing locations and conductive flooring installed in these areas
Type
ECRI-Recommended
Interval
Interval Used
By Hospital
Major
1 month*
months
.
hours
Minor
NA
months
.
hours
Time Required
*
This procedure is not required in areas where flammable anesthetics are no longer used and where the floors
have been treated to make them nonconductive.
Overview
Some inhalation anesthetics (e.g., cyclopropane, diethyl ether, ethyl chloride, ethylene) are flammable
and pose a considerable fire and explosion risk when
mixed with air, oxygen, and nitrous oxide. The most
likely ignition source for these gas mixtures in the
operating room or other flammable anesthetizing locations is a spark caused by an electrostatic (static electricity) discharge. Other possible sources of ignition
include heating or sparking in electrically powered
devices, electrosurgical or electrocautery equipment,
and percussion sparks.
Conductive floors and electrical interconnection of
all furniture and devices with conductive surfaces
minimize the risk of electrostatic charge accumulation
and resultant spark. NFPA 99, Standard for Health
Care Facilities, 1993 Edition, Section 12-4.1.3, contains requirements calling for all furniture and devices
located in a flammable anesthetizing location to have
conductive casters (or equivalent means) to ensure
continuity with the conductive flooring.
010828
441-0595
A NONPROFIT AGENCY
Unlike the requirements for grounding medical devices to ensure safety from electrical shock, low resistance is not required for conductivity established for
the purpose of electrostatic control. Rather, it is sometimes preferable to ensure that a certain minimum
level of resistance be maintained to minimize electric
shock hazards. For example, conductive flooring for
this purpose is required to offer an average resistance
of at least 25,000 Ω and less than 1 MΩ.
Flammable anesthetics were once a necessary part
of surgery; however, nonflammable inhalation anesthetics are now available and are used in most cases.
Flammable anesthetics are used only for rare circumstances (e.g., where a flammable anesthetic is claimed
to offer some pharmacologic advantage or a physician
is familiar with a flammable anesthetic and unwilling
to change technique).
In areas designated and posted for the use of only
nonflammable anesthetics, antistatic precautions are
not required. Equipment or furniture with conductive
casters can be used in nonflammable anesthetizing
locations, but conductivity need not be maintained or
5200 Butler Pike, Plymouth Meeting, PA 19462-1298, USA
Telephone +1 (610) 825-6000 ● Fax +1 (610) 834-1275 ● E-mail [email protected]
Inspection and Preventive Maintenance System
measured. Conductive floors in nonflammable anesthetizing locations, unless they are treated to make
them nonconductive, must be inspected to ensure that
each of the five floor-resistance measurements in each
room yields a reading of 10,000 Ω or more to minimize
electric shock risk from an excessively conductive floor.
No further testing is required once this criterion is met.
ECRI recommends treating or replacing floors to make
them nonconductive, especially if the power supply is
changed from isolated to grounded.
Test apparatus and supplies
High-voltage megohmmeter intended for this type
of application, which has an open-circuit voltage of
500 VDC and meets the requirements of NFPA 99
Two 5 lb, 21⁄2″ diameter circular electrodes that
meet the requirements of NFPA 99
Metal plate and insulating plate or sheet (for caster
conductivity tests)
Special precautions
The megohmmeter used for this testing is capable
of shocking personnel. Never touch the leads or equipment under test when the ohmmeter is activated.
Procedure
Equipment/Furniture. Inspect leg tips, casters, or
other conductive devices on furniture and equipment
to ensure that they are free of wax, lint, or other
materials that interfere with conductivity.
Lubricate casters if needed with dry graphite or
graphited oil. Avoid excessive lubrication, since this
can cause accumulations of oil and grime on caster
wheels and sides.
Test conductive casters, chains, or other mechanisms
by placing one caster on a metal plate that is insulated
from the floor. The resistance between the metal plate
2
and metal frame or chassis should not exceed
250,000 Ω. Only one caster need meet this requirement
to ensure continuity and to conform with NFPA 99;
however, we recommend testing all casters during initial
acceptance testing of the device or furniture.
For convenience, perform routine periodic tests of
furniture and equipment conductivity by placing one
of the 5 lb electrodes on the conductive floor and another on the furniture or equipment. Unplug the device (and remove any nonpermanent grounding
straps). The resistance should not exceed 5 MΩ; if it
does, perform the entire inspection procedure. Indicate
on the form whether floor-to-frame or caster-to-frame
tests were performed. It is not necessary to record the
resistance value, but space is provided on the form if
it is desired in the event of a failure.
Conductive floors. Make sure that the floor is clean
and dry. Place the electrodes 3 ft apart on the floor,
and measure and record the resistance between the
two electrodes and from one electrode to a ground point
(e.g., grounding jack, grounded exposed metal in the
room). Measure the resistance at five different locations in the room, and average each set of five readings.
Each of the five individual floor resistance readings
should be no greater than 5 MΩ and no less than
10,000 Ω, and the average should be no greater than
1 MΩ and at least 25,000 Ω. Each measurement from
the floor to a ground point should be at least 10,000 Ω,
and the average resistance should be at least 25,000
Ω.
Conductive flooring is not required in nonflammable anesthetizing locations. However, if a conductive
floor is present, test as above. No individual reading
should be less than 10,000 Ω. If the floor does not meet
this criterion, test the floor conductivity every month
until the condition is corrected. No further testing is
required once the criterion is met.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Conductive Furniture and Floors
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
3
Procedure/Checklist 458-0595
Critical Care Ventilators
Used For:
Ventilators, Intensive Care [17-429]
Ventilators, Intensive Care, Neonatal/Pediatric [14-361]
Ventilators, Pressure-Cycled [14-360]
Ventilators, Transport [18-098]
Also Called: Respirators
Commonly Used In: Critical care units, general medical/surgical units, emergency departments
Scope: Applies to all ventilators except jet ventilators, negative-pressure ventilators, portable ventilators
(see Procedure/Checklist 471), and anesthesia unit ventilators (see Procedure/Checklist 461)
Risk Level: ECRI Recommended, High; Hospital Assessment,
Type
ECRI-Recommended
Interval
Interval Used
By Hospital
Major
6 months*
months
.
hours
Minor
NA
months
.
hours
Time Required
* Inspection and preventive maintenance intervals should be scheduled according to the manufacturer’s
recommendations, which may be related to hours of use. However, units should have a major inspection at
least every six months. Pre-use checks should be performed by a respiratory therapist or respiratory equipment
technician.
Overview
Mechanical ventilators are used to compensate for
deficiencies in normal breathing. A ventilator may aid
or augment spontaneous breathing or may completely
regulate a prescribed breathing pattern for patients
who cannot breathe for themselves. Most modern ventilators use positive-pressure inflation of the lungs to
accomplish these functions.
Ventilators are classified according to the method in
which ventilation is accomplished. Most adult ventilators are volume cycled, in that they are set to deliver a
predefined volume of gas to the patient. Most infant
ventilators are time cycled, in that they are set to
deliver gas for a predefined inspiratory time. A pressure-cycled ventilator delivers gas until a predefined
pressure is reached. Volume- and time-cycled ventilators also have a pressure-limit control to prevent the
232575
458-0595
A NONPROFIT AGENCY
attainment of dangerous pressures in the patient’s
lungs.
The ventilator provides direct control of the patient’s
ventilatory variables, as well as other variables (e.g., the
concentration of inspired oxygen), and the limits on certain
variables for safe operation. All these controls allow the
clinician to provide better patient management, even for
patients with serious respiratory impairments.
A mechanical ventilator is composed of four basic
subsystems: the ventilator and its controls; monitors
and alarms; gas supply; and patient circuit (which
includes the breathing circuit and may include a humidifier and nebulizer). Each subsystem requires its own
inspection and preventive maintenance procedures.
Many microprocessor-controlled ventilators have
self-diagnostic programs. When the ventilator’s
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Telephone +1 (610) 825-6000 ● Fax +1 (610) 834-1275
●
E-mail [email protected]
Inspection and Preventive Maintenance System
hardware (e.g., solenoid valves, transducers) is
checked by its own software, manual inspection items
can be eliminated.
Citations from Health Devices
Inadequate pressure relief in infant ventilators [Hazard], 1983 Apr; 12:150-1.
Leaving ventilator-dependent patients unattended
[Hazard], 1986 Apr; 15:102-3.
Infant ventilators [Evaluation], 1986 Aug; 15:219-46.
Remote alarms for ventilators and other life-support
equipment, 1986 Dec; 15:323-4.
IPM Task ManagerTM, the software component of the
Inspection and Preventive Maintenance System, enables easy production of customized procedures and
checklists for specific ventilator models and clinical
needs. Items performed by outside vendors can be
excluded from the checklist; a separate checklist for
use by outside vendors can be produced to ensure that
those items agreed upon are performed by the vendor.
The following framework should be supplemented
by the manufacturer’s recommended preventive maintenance procedures for mechanical ventilators.
1. Qualitative tests
1.1
Chassis/Housing. Examine the exterior of the
unit for cleanliness and general physical condition. Be sure that plastic housings are intact,
that all hardware is present and tight, and that
there are no signs of spilled liquids or other
serious abuse.
1.2
Mount/Fasteners. If the device is mounted on a
stand or cart, examine the condition of the
mount. If it is attached to a wall or rests on a
shelf, check the security of this attachment.
Check the mounting security of all components
or attached monitors.
1.3
Casters/Brakes. If the device moves on casters,
check their condition. Verify that they turn and
swivel, as appropriate, and look for accumulations of lint and thread around the casters.
Check the operation of brakes and swivel locks,
if the unit is so equipped.
1.4
AC Plug. Examine the AC power plug for damage. Attempt to wiggle the blades to check that
they are secure. Shake the plug and listen for
rattles that could indicate loose screws. If any
damage is suspected, open the plug and inspect it.
1.5
Line Cord. Inspect the cord for signs of damage.
If damaged, replace the entire cord or, if the
damage is near one end, cut out the defective
portion. Be sure to wire a new power cord or plug
with the correct polarity. Also, check line cords
of battery chargers.
1.6
Strain Reliefs. Examine the strain reliefs at
both ends of the line cord. Be sure that they hold
the cord securely. If the line cord is detachable
(by the user), affix the cord to the unit so that it
cannot be removed by the operator. (See Health
Devices 1993 May-Jun; 22:301-3.)
1.7
Circuit Breaker/Fuse. If the device has a
switch-type circuit breaker, check that it moves
Microprocessor-controlled third-generation critical
care ventilators [Evaluation], 1989 Feb; 18:59-83.
Test apparatus and supplies
Lung simulator with adjustable compliance or ventilator tester
Pressure gauge or meter with 2 cm H2O resolution
from -20 to +120 cm H2O
Various breathing circuit adapters
Leakage current meter or electrical safety analyzer
Ground resistance ohmmeter
Additional items as required for specific manufacturers’ procedures
Procedure
Before beginning an inspection, carefully read this
procedure and the manufacturer’s instruction and
service manuals; be sure that you understand how to
operate the equipment, the significance of each control
and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive
maintenance procedures or frequencies are recommended by the manufacturer.
Manufacturers’ recommended procedures for inspection and preventive maintenance of mechanical ventilators vary in both methods and required accuracy. In
addition, ventilation modes, controls, and algorithms for
calculated variables vary greatly according to manufacturer and model. This procedure provides the basic
framework for complete ventilator inspection and preventive maintenance. Manufacturers’ recommended
procedures should be added where appropriate. References to specific pages of the manufacturer’s manual
should be added to the checklist. (The checklist includes
blank spaces for the insertion of these page references.)
2
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Critical Care Ventilators
freely. If the device is protected by an external
fuse, check its value and type against that
marked on the chassis and ensure that a spare
is provided.
1.8
Tubes/Hoses. Check the condition of all tubing
and hoses. Be sure that they are not cracked,
kinked, or dirty.
1.9
Cables. Inspect any cables and their strain reliefs for general condition. Carefully examine
cables to detect breaks in the insulation and to
ensure that they are securely gripped in the
connectors at each end, which will prevent rotation or other strain. Where appropriate, verify
that there are no intermittent faults by flexing
cables near each end and looking for erratic
operation or by using an ohmmeter.
1.10 Fittings/Connectors. Examine all gas fittings
and connectors for general condition. Gas fittings should be tight and should not leak. Verify
that keyed connectors (e.g., pin-indexed gas connectors) are used where appropriate, that all
pins are in place and secure, and that keying is
correct. Connectors to hospital central piped
medical gas systems should have the appropriate DISS or quick-connect fitting to eliminate the
need for adapters.
1.12 Filters. Check the condition of gas filters. Check
for corrosion residue indicative of liquid, gaseous, or solid particle contaminants in the gas
supply; advise appropriate personnel if found.
Clean or replace if appropriate, and indicate this
on Lines 3.1 and 3.4 of the inspection form.
1.13 Controls/Switches. Before changing any controls or alarm limits, check their positions. If any
settings appear inordinate (e.g., alarm limits at
the ends of their range), consider the possibility
of inappropriate clinical use or of incipient device
failure. Investigate questionable control settings
on a home care unit. Consult with the patient’s
physician to determine correct settings. The patient or caregiver should receive additional
training, if required. Record the settings of those
controls that should be returned to their original
positions following the inspection.
Examine all controls and switches for physical
condition, secure mounting, and correct motion.
Check that control knobs have not slipped on
their shafts. Where a control should operate
against fixed-limit stops, check for proper alignment, as well as positive stopping. Check membrane switches for damage (e.g., from
fingernails, pens). During the inspection, be sure
to check that each control and switch performs
its proper function.
1.14 Heater (for heated portions of the breathing circuit). Check the physical condition and proper
operation of the heater.
1.15 Fan/Compressor. Check the physical condition
and proper operation of these components.
Check for automatic activation of the compressor
when the piped gas supply pressure falls below
operating pressure. Clean or replace fan and/or
compressor filters and lubricate as required, according to the manufacturer’s instructions, and
note this on Lines 3.1 and 3.2 of the form.
1.17 Battery/Charger. Inspect the physical condition of batteries and battery connectors if readily
accessible. Check operation of battery-operated
power-loss alarms, if so equipped. Operate the
unit on battery power for several minutes to
check that the battery is charged and can hold a
charge. (The inspection can be carried out on
battery power to help confirm adequate battery
capacity.) Check battery condition by activating
the battery test function or measuring the output
voltage; for lead-acid batteries, measure the specific gravity and check the fluid level. Check the
condition of the battery charger and, to the extent possible, confirm that it does, in fact, charge
the battery. Be sure that the battery is recharged
or charging when the inspection is complete.
When it is necessary to replace a battery, label
it with the date.
1.18 Indicators/Displays. Confirm the operation of all
lights, indicators, meters, gauges, and visual displays on the unit and charger (if so equipped). Be
sure that all segments of a digital display function.
Record reading of an hour meter, if present.
1.20 Alarms/Interlocks. Induce alarm conditions to
activate audible and visual alarms. Verify alarm
messages on displays. Check that any associated
interlocks function. If the unit has an alarm-silence feature, check the method of reset (i.e.,
manual or automatic) against the manufacturer’s
specifications. It may not be possible to check out
all alarms at this time, since some may require
special conditions that must be established according to the manufacturer’s recommendations;
include these in Item 2.4. Verify that the remote
alarm indicator functions properly.
1.21 Audible Signals. Operate the device to activate
any audible signals. Confirm appropriate volume,
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
3
Inspection and Preventive Maintenance System
may include tidal volume, respiration rate, inspiratory time, expiratory time, inspiratory:expiratory (I:E) ratio, flow, and waveshape, among
others. Typically, these tests are performed by
attaching the ventilator to a lung simulator or
ventilator tester and comparing measured values of pressure, flow, and/or volume and time to
settings on the ventilator. The manufacturer
should recommend the appropriate ventilator
settings (e.g., tidal volume, rate, inspiratory
time) at which to verify proper operation and
accuracy (generally within 10%). Check the accuracy of flowmeters on infant ventilators.
as well as the operation of a volume control, if
so equipped. If audible alarms have been silenced or the volume set too low, alert clinical
staff to the importance of keeping alarms at the
appropriate level.
1.22 Labeling. Check that all necessary placards, labels, and instruction cards are present and legible.
1.23 Accessories. Confirm the presence and condition
of accessories, including the humidifier and the
nebulizer (see Procedure/Checklist 431 for
heated humidifiers).
2.4
2. Quantitative tests
2.1
2.2
Grounding Resistance. Using an ohmmeter, electrical safety analyzer, or multimeter with good
resolution of fractional ohms, measure and record
the resistance between the grounding pin of the
power cord and exposed (unpainted and not anodized) metal on the chassis. We recommend a
maximum of 0.5 Ω. If the system is modular or
composed of separate components, verify
grounding of the mainframe and each module or
component.
2.3
4
Breathing rate
Inspiratory time
Peak inspiratory pressure (PIP)
Peak or mean inspiratory flow
PEEP
Mean airway pressure (MAP)
Volume (both tidal and minute volume)
Leakage Current. Measure chassis leakage current to ground with the grounding conductor of
plug-connected equipment temporarily opened.
Operate the device in all normal modes, including on, standby, and off, and record the maximum leakage current.
Measure chassis leakage current with all accessories normally powered from the same line
cord connected and turned on and off. This includes other equipment that is plugged into the
primary device’s accessory receptacles, as well as
equipment plugged into a multiple-outlet strip
(“Waber strip”) so that all are grounded through
a single line or extension cord.
Monitors and Alarms. The following parameters are commonly monitored and should be inspected for accuracy (generally within 10%)
according to the manufacturer’s specifications:
Fraction of inspired oxygen (FIO2); see Oxygen Analyzers Procedure/Checklist 417
Temperature of inspired air
Other monitors
Alarm settings (e.g., high PIP, low MAP, low
pressure, low FIO2) should be inspected for
proper and accurate activation.
2.5
Gas Supply.
Oxygen-air proportioner. See Procedure/Checklist 444.
Compressor. Test according to the manufacturer’s recommendations.
Chassis leakage current to ground should not
exceed 300 µA.
Pneumatic lines (including air filters). Verify that
appropriate gas-specific connectors are used.
Modes and Settings. The following modes are
commonly found on most ventilators: control,
assist/control, intermittent mandatory ventilation/synchronized intermittent mandatory ventilation (IMV/SIMV), pressure support, and
continuous positive airway pressure/positive
end-exhalation pressure (CPAP/PEEP). The
function of these modes should be inspected and
verified for proper operation. Check the operation and accuracy of ventilation controls, which
Gas cylinders, gauges, and regulators (for transport ventilators). Verify that these components
are present, securely mounted, and in good condition and that there is adequate gas supply.
2.6
Patient Circuit.
Breathing circuit (including filters). Verify that
these components are compatible with the
ventilator according to the manufacturer’s
recommendations (see Health Devices 1988
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Critical Care Ventilators
Apr; 17:109). Check for leaks in the breathing
circuit, ensuring that fittings, adapters, and
other components (e.g., exhalation valves,
H-valves, PEEP valves, water traps, nebulizers) are properly assembled and functioning correctly.
Humidifiers. See Heated Humidifiers Procedure/Checklist 431.
Pressure-relief Mechanism. Check the proper
operation of the pressure-relief mechanism by
occluding the breathing circuit and measuring
the resulting peak pressure on the pressure
gauge. Verify that pressure is vented in the
breathing circuit.
3. Preventive maintenance
3.4
Replace components according to the manufacturer’s instructions.
4. Acceptance tests
Conduct major inspection tests for this procedure
and the appropriate tests in the General Devices Procedure/Checklist 438.
Before returning to use
Ensure that all controls are set properly. Set alarms
loud enough to alert personnel in the area in which the
device will be used. Other controls should be in their
normal pre-use positions. If the unit is being used at
home, ensure that controls are set correctly before it is
returned to the patient.
3.1
Clean the exterior, interior, and components if
needed.
Attach a Caution tag in a prominent position so that
the user will be aware that control settings may have
been changed.
3.3
Calibrate according to the manufacturer’s instructions.
Recharge battery-powered devices, or equip them
with fresh batteries, if needed.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
5
Procedure/Checklist 457-0595
Cryosurgical Units
Used For:
Cryometers [11-066]
Cryosurgical Units [11-067]
Cryosurgical Units, Ophthalmic [11-068]
Also Called: CSUs
Commonly Used In: Operating rooms; OB/GYN, urology, proctology, and dermatology professional offices;
surgical clinics
Scope: Applies to all cryosurgical units, except disposable ophthalmic cryoextractors; portions of this
procedure are applicable to tissue-temperature and tissue-impedance cryometers that may be integral to a
CSU
Risk Level: ECRI Recommended, Medium; Hospital Assessment,
Type
ECRI-Recommended
Interval
Major
12 months
months
.
hours
Minor
NA
months
.
hours
Overview
Cryosurgical units (CSUs) apply a gaseous or liquid
refrigerant (cryogen) to freeze target tissue either
through direct application of liquid cryogen (open-system CSUs) or indirectly through contact with a cryogen-cooled probe (closed-system CSUs). Cryosurgically
treated tissue is usually allowed to become necrotic and
slough off. The advantages of cryosurgery for tissue
destruction include ease of use, the need for little or no
anesthesia, the avoidance of hemorrhage, and relatively few postoperative complications.
Cryosurgery is used in dermatology, oral surgery,
gynecology, urology, ophthalmology, otolaryngology, and
proctology. Although some CSUs and their probe tips are
designed for use within only one specialty (e.g., ophthalmology, gynecology), most units have a wide range of
applications and associated interchangeable tips.
The two types of CSUs — those that use liquid nitrogen and those that use N2O or CO2 — have significantly different freezing capabilities. Liquid nitrogen
units can attain temperatures as low as -196°C and are
085109
457-0595
A NONPROFIT AGENCY
Interval Used
By Hospital
Time Required
suitable for both benign and malignant tumors. N2O
and CO2 units are most suitable for benign and inflammatory diseases, although they have been used successfully to treat small malignancies; the lowest
probe-tip temperatures they can attain are -89° and
-79°C, respectively.
Liquid nitrogen CSUs deliver the cryogen to the tip
as a liquid, where its rapid vaporization cools the
probe. In closed-system N2O units and CO2 units,
cooling occurs through the Joule-Thompson effect, in
which a compressed gas (often at or near room temperature) is allowed to expand suddenly through a
small aperture inside the probe tip, causing a considerable drop in gas temperature and liquefaction of
some of the cryogen. The vaporization of the liquefied
cryogen from the interior of the tip, combined with the
drop in gas temperature caused by expansion, lowers
the tip temperature to near the boiling point of the
cryogen.
Cryogen flows through an insulated probe shaft,
cooling the tip, and exhausts back through the probe
(closed-system design) or is applied directly to the
5200 Butler Pike, Plymouth Meeting, PA 19462-1298, USA
Telephone +1 (610) 825-6000 ● Fax +1 (610) 834-1275
●
E-mail [email protected]
Inspection and Preventive Maintenance System
target tissue (open-system design). CSUs using N2O or
CO2 are not usually suitable for use as open systems
because cryogen “snow” builds up on target tissue and
insulates the lesion from the cryogen spray. Liquid
nitrogen CSUs can be either open or closed.
Most closed-system CSUs have active defrosting of the
probe tip to allow its safe and rapid removal from the
target tissue. Active defrosting warms the probe from
within and allows the tip to be removed safely and
quickly, usually within seconds; it can be achieved using
an electric heater within the probe tip, exhaust occlusion
(resulting in gas pressure buildup in the tip that causes
the cryogen to heat up), or gas flooding of the tip with
low-pressure cryogen at room temperature.
CSUs are available in three basic configurations: console, stand-alone, and handheld. Consoles are freestanding units that typically contain the cryogen gas cylinders,
pressure regulators, indicators, and operating controls.
Stand-alone units are freestanding cryogen tanks on
carts without controls or displays. Handheld units are
lightweight, portable CSUs that use liquid nitrogen as
the cryogen. Gun-type and pencil-shaped probes attach
to both console and stand-alone units.
To ensure that the unit is freezing properly, the
probe tips on many console CSUs contain a cryometer
(usually incorporating a thermocouple) to measure
probe-tip temperature. This reading, however, does
not directly reflect the cryolesion temperature and is
not used as the definitive indicator of the depth and
temperature of the frozen tissue. Some console CSUs
also have a tissue-temperature cryometer; hypodermic
thermocouples are used to monitor the target-tissue
temperature. Alternatively, the unit may be equipped
with an impedance cryometer, which uses hypodermic
needle electrodes to assess the extent of freeze.
Questions have arisen over whether it is advisable,
practical, or safe for a hospital to repair its own cryosurgical equipment. We do not recommend such a
practice; the units operate at very high pressures, and
undetected probe damage can result in explosion and
serious patient injury. Furthermore, the equipment
needed to safely service and inspect CSUs is expensive.
However, clinical engineering staff should perform
annual routine general equipment inspections to detect any impending problem or improper scavenging of
exhausted N2O.
Scavenging exhausted N2O from CSUs is essential.
N2O is both teratogenic and mutagenic; the reported
long-term hazards of exposure to this and other anesthetic gases include increased rate of spontaneous abortion, increased incidence of hepatic and renal disorders,
2
and cancer. Because exposure of clinical engineering
personnel to the gas will be only occasional, a more acute
concern for their safety during the inspection is to guard
against temporary N2O intoxication.
Most older N2O CSUs expose personnel to levels
well in excess of the 25 parts per million time-weighted
average concentration limit of N2O gas recommended
by the National Institute of Occupational Safety and
Health (NIOSH). In addition, the flow of gas from
CSUs is much higher than that from anesthesia machines, so the total quantity of N2O used during a
cryosurgical procedure or inspection is substantial and
potentially very dangerous. We recommend switching
to CO2 as the cryogen. Alternatively, the hospital must
scavenge all N2O from CSUs and vent it to the outside,
away from air-intake ducts; N2O should never be
vented into a sink, drain trap, or the piped medical/surgical suction system. Users should contact the manufacturer of their unit and request information on
scavenging the N2O exhaust; the manufacturer or a
local supplier can probably order the proper size and
type of exhaust hose for equipment with an N2O scavenging port. An N2O CSU should not be used or tested
unless its exhaust is properly scavenged.
If an N2O CSU is used in an OR with 100% outside air
ventilation, one end of the exhaust hose should be placed
1 to 2 ft into the room air exhaust vent (permanent
installation of a short length of exhaust hose through the
vent grill is advisable if vents are inconveniently located
[e.g., near the ceiling]), and the exposed hose end should
be equipped with a connector appropriate for attachment
to the exhaust hose. If the OR has a dedicated system for
venting scavenged anesthetic gases with a flow capacity
100 L/min (3.5 ft3/min), the N2O exhaust can be vented
through this system rather than the return air system if
it is more convenient. For treatment rooms in clinics and
offices (and for ORs where the N2O cannot be vented as
discussed above), N2O can be vented to the outside through
a window or small hole drilled in the window frame or the
wall of the room where the equipment is used.
CO2 should be used for CSUs if scavenged N2O
cannot be safely or conveniently vented or if N2O
cannot be scavenged because of the design of the CSU.
Facilities that can operate with either N2O or CO2
should strongly consider using CO2 — even if scavenging is possible — because it is intrinsically safer. N2O
units that cannot be scavenged or converted for use
with CO2 should be removed from use and only CO2
units purchased. If an unscavenged N2O CSU must be
used while awaiting proper scavenging modifications
or before switching to a CO2 CSU, it should be used in
an extremely well-ventilated area, such as a hospital
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Cryosurgical Units
operating room. Pregnant staff members should never
be present during use or testing of an unscavenged
N2O CSU.
Citations from Health Devices
Nitrous oxide exhausted from cryosurgical units [Hazard], 1979 Oct; 8:293.
Update: Nitrous oxide exhausted from cryosurgical
units, 1980 May; 9:180.
Siphon gas cylinders and cryosurgical units [Hazard],
1980 May; 9:187.
Personnel exposure to waste anesthetic gases, 1983
May; 12:169-77.
Frigitronics Model CCS-100 cryosurgical cart [User
Experience NetworkTM], 1986 Jan; 15:24.
Should hospitals repair cryosurgical units? [User Experience NetworkTM], 1986 Dec; 15:332-3.
N2O cryosurgical units must be scavenged [Hazard
update], 1987 Dec; 16:407-9.
Surgical devices omitted from equipment control programs [Hazard], 1989 Feb; 18:86.
States, liquid N2O tanks are usually blue with a silver
neck; gaseous N2O tanks are entirely blue. All cylinders should be tested before they are connected to the
CSU. First, make sure that the valve is not pointed
toward anyone. Then, open the valve one half to one
full turn for 2 to 4 sec; no mist should be seen. If a
continuous mist is observed, the cylinder contains a
siphon and should be used only with CSUs specified
for liquid N2O use.
Procedure
Before beginning an inspection, carefully read this
procedure and the manufacturer’s instruction and
service manuals; be sure that you understand how to
operate the equipment, the significance of each control
and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive
maintenance procedures or frequencies are recommended by the manufacturer.
Although many CSUs are gas powered, we have
included tests for electrical safety and special functions for use on those units that are so equipped.
1. Qualitative tests
1.1
Chassis/Housing. Examine the exterior of the
unit for cleanliness and general physical condition. Be sure that plastic housings are intact,
that all hardware is present and tight, and that
there are no signs of spilled liquids or other
serious abuse.
1.2
Mount/Fasteners. If the device is mounted on a
stand or cart, examine the condition of the
mount. If it is attached to a wall or rests on a
shelf, check the security of this attachment. Gas
cylinder mounts should securely fasten the cylinders to the CSU stand or console.
1.3
Casters/Brakes. If the device moves on casters,
check their condition. Verify that they turn and
swivel, as appropriate, and look for accumulations of lint and thread around the casters.
Check the operation of brakes and swivel locks,
if the unit is so equipped.
1.4
AC Plug/Receptacles. Examine the AC power
plug for damage. Attempt to wiggle the blades to
check that they are secure. Shake the plug and
listen for rattles that could indicate loose screws.
If any damage is suspected, open the plug and
inspect it.
Test apparatus and supplies
Leakage current meter or electrical safety analyzer
Ground resistance ohmmeter
10× loupe
Stopwatch or watch with a second hand
Cup filled with tap water (temperature not critical)
Special precautions
Liquid nitrogen must be handled with care to prevent
operator injury. Read and follow the precautions and
warnings for handling liquid nitrogen presented in the
equipment manual for any CSU using this cryogen.
All N2O CSUs must have their exhaust safely scavenged during inspections to prevent acute physical and
psychological impairment and possible long-term adverse health effects to the inspector.
Siphon-type gas cylinders used with liquid N2O
CSUs can be mistakenly installed on a CSU designed
for gaseous N2O use if the cylinders are mislabeled or
if medical personnel are unaware that siphon cylinders
should not be used with gas units. Very few N2O CSUs
are designed to accept siphon cylinders of liquid N2O.
If a siphon cylinder is fitted to a gas unit, liquid N2O
can leak from the fittings or seals of the cryoprobe,
resulting in patient or operator injury. In the United
If the device has electrical receptacles for accessories, verify presence of line power; insert an AC
plug into each and check that it is held firmly. If
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
3
Inspection and Preventive Maintenance System
accessories are plugged and unplugged often,
consider a full inspection of the receptacles.
1.5
1.6
1.7
Line Cord. Inspect the cord for signs of damage.
If damaged, replace the entire cord or, if the
damage is near one end, cut out the defective
portion. Be sure to wire a new power cord or plug
with the correct polarity. Also check line cords of
battery chargers.
Strain Reliefs. Examine the strain reliefs at
both ends of the line cord. Be sure that they hold
the cord securely. If the line cord is detachable
(by the user), we recommend that the cord be
affixed to the unit so that it cannot be removed
by the operator. (See Health Devices 1993 MayJun; 22[5-6]:301-3.)
Circuit Breaker/Fuse. If the device has a
switch-type circuit breaker, check that it moves
freely. If the device is protected by an external
fuse, check its value and type against that
marked on the chassis, and ensure that a spare
is provided.
1.8
Tubes/Hoses. Check the condition of all tubing
and hoses. Be sure that they are not cracked,
kinked, or dirty.
1.9
Cables. Inspect any cables (e.g., sensor, electrode, remote control) and their strain reliefs for
general condition. Carefully examine cables to
detect breaks in the insulation and to ensure that
they are gripped securely in the connectors at
each end to prevent rotation or other strain. Verify that there are no intermittent faults by flexing
electrical cables near each end and looking for
erratic operation or by using an ohmmeter.
1.10 Fittings/Connectors. Examine all gas and liquid fittings and connectors, as well as electrical
cable connectors, for general condition. Electrical contact pins or surfaces should be straight,
clean, and bright. Verify that leads and hoses
are firmly gripped in their appropriate connectors. Gas and liquid fittings should be tight and
should not leak; listen for audible leaks and look
for dripping cryogen. Complaints of excessive
gas usage indicate that the CSU may have a leak
between the cryogen gas cylinder and the console/regulator.
Pin-indexed gas cylinder yokes should be present. Make sure that no keying pins are missing
and that the keying is correct for the gas that is
used. If a yoke has no keying pins — which some
manufacturers have omitted, in violation of ac-
4
cepted safety standards — immediately replace
the yoke with one correctly keyed for that gas.
Destroy and discard the unkeyed yoke.
1.11 Probes and Probe Tips. Confirm that appropriate probes and probe tips are on hand and check
their physical condition. For ophthalmic probe
tips, use a 10× loupe to inspect them. They
should not have any cracks, abrasion, corrosion,
kinks, dents, or evidence of bending. The presence of such damage suggests that these delicate
probes have been bent or crushed and must be
replaced.
Operate the unit for about 30 sec with each tip
immersed in water (water temperature is not
critical) and check to make sure that ice forms
on the tip. During each tip test, make sure that
there is no leakage of cryogen (seen as bubbles
in the water) from the probe/tip connector. Examine the probe shaft thermal insulation for
cracks or signs of degradation.
1.12 Filters. Check the condition of all liquid and gas
(air) filters. Clean or replace as appropriate and
indicate this on Lines 3.1 and 3.4 of the inspection form.
1.13 Controls/Switches. Before changing any controls or alarm limits, check their positions. If
any settings appear inordinate, consider the possibility of inappropriate clinical use or of incipient device failure. Record the settings of those
controls that should be returned to their original
positions following the inspection. Also, make
sure that users turn off the gas cylinder valves
between uses. This will minimize the chance of
high-pressure leaks.
Examine all controls and switches for physical
condition, secure mounting, and correct motion.
Check that control knobs have not slipped on
their shafts. Where a control should operate
against fixed-limit stops, check for proper alignment, as well as positive stopping. Check membrane switches for membrane damage (e.g., from
fingernails, pens). During the course of the inspection, be sure to check that each control and
switch performs its proper function.
1.17 Battery/Charger. Inspect the physical condition of batteries and battery connectors if readily
accessible, including battery-operated cryometers.
Check the condition of the battery charger, if present, and, to the extent possible, confirm that it
does in fact charge the battery. When it is necessary to replace a battery, label it with the date.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Cryosurgical Units
1.18 Indicators/Displays. During the course of the
inspection, confirm the operation of all lights,
indicators, meters, gauges, and visual displays
on the unit. Check that gas pressure gauges and
flowmeters read zero when the gas is not turned
on. Be sure that all segments of a digital display
function. Record reading of an hour meter, if
present.
If the CSU console has an accessory receptacle, check its grounding to the main power cord.
2.2
1.19 User Calibration. Verify that the self-test function operates and indicates normal operation, if
so equipped.
1.20 Alarms. Induce alarm conditions to activate
audible and visual alarms. Check that any associated interlocks function. If the unit has an
alarm-silence feature, check the method of reset
(e.g., manual or automatic) against the manufacturer’s specifications. It may not be possible to
check all alarms at this time, since some may
require abnormal operating conditions that will
be simulated later in this procedure.
Measure chassis leakage current with all accessories normally powered from the same line
cord connected and turned on and off.
Chassis leakage current to ground should not
exceed 300 µA.
2.3
Probe-Tip Cryometer. Repeat the defrost control
test described in Item 1.24. The ice ball should
release from the probe tip when the tip temperature readout indicates 0°C, ±1°C.
2.4
Tissue-Temperature Cryometer. Touch a tissuetemperature probe to the probe tip and immerse
them both in water. Activate the CSU at its
maximum freezing power (if adjustable) for approximately 3 min. The tissue-temperature
probe and probe tip will freeze within the ice ball.
The tissue temperature and probe-tip temperature should be within 5°C of each other.
2.5
Elapsed-Time Meter/Timer. Where present,
verify the accuracy of a timing mechanism with
a stopwatch or watch with a second hand for 5
min. The error should not exceed 10 sec.
1.21 Audible Signals. Operate the device to activate
any audible signals. Confirm appropriate volume, as well as the operation of a volume control,
if so equipped.
1.22 Labeling. Check that all necessary placards, labels, conversion charts, and instruction cards
are present and legible.
1.24 Defrost Control. Verify that the defrost feature
operates. An ice ball on a tip should dislodge
within approximately 30 sec after activation of
the defrost mode.
1.25 Scavenger. For N2O CSUs, verify the presence
of a scavenging attachment and hose. An N2O
CSU should not be used or tested unless its
exhaust is properly scavenged.
2. Quantitative tests
2.1
Grounding Resistance. Using an ohmmeter,
electrical safety analyzer, or multimeter with
good resolution of fractional ohms, measure and
record the resistance between the grounding pin
of the power cord and exposed (unpainted and
not anodized) metal on the chassis. We recommend a maximum of 0.5 Ω. If the system is
modular or composed of separate components,
verify grounding of the mainframe and each
module or component. If the device is double
insulated, grounding resistance need not be
measured; indicate “DI” instead of the ground
resistance value.
Leakage Current. Measure chassis leakage current to ground with the grounding conductor of
plug-connected equipment temporarily opened.
Operate the device in all normal modes, including on, standby, and off, and record the maximum leakage current.
3. Preventive maintenance
3.1
Clean exterior (interior if appropriate).
3.3
Calibrate cryometer, if needed.
3.4
Replace probe-tip O-rings, if needed.
4. Acceptance tests
Conduct major inspection tests for this procedure
and the appropriate tests in the General Devices Procedure/Checklist 438.
Before returning to use
Make sure that all controls are set properly. Set
alarms loud enough to alert personnel in the area in
which the device will be used. Other controls should
be in their normal pre-use positions. Be sure that the
inspection did not deplete the cryogen supply to a level
that disables the unit. Turn off the cryogen gas cylinder valves after completing the inspection.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
5
Procedure/Checklist 408-0595
Defibrillator/Monitors
Used For:
Defibrillator/Monitors, Line-Powered [15-029]
Defibrillator/Monitor/Pacemakers [17-882]
Commonly Used In: Coronary and special care areas, emergency departments, operating rooms, resuscitation carts, ambulances, patient care areas
Scope: Applies to battery- and line-powered defibrillator/monitors; does not apply to defibrillators or ECG
monitors (see Defibrillators Procedure/Checklist 407 and ECG Monitors Procedure/Checklist 409); see
Pacemakers, External Noninvasive Procedure 460 for units with this accessory
Risk Level: ECRI Recommended, High; Hospital Assessment,
Type
ECRI-Recommended
Interval
Major
12 months
months
.
hours
Minor
6 months
months
.
hours
Defibrillator/monitors combine the functions of an
ECG monitor and defibrillator into a single unit, which
allows the operator to quickly assess and monitor the
ECG and apply a defibrillating pulse, if appropriate.
Most units are battery-powered so that they can be
used during transport within a hospital or in an ambulance or carried into the field.
Defibrillator/monitors are critical resuscitation instruments. Their failure to perform effectively may
result in the death of a patient undergoing resuscitation or cause further cardiac damage or even death in
a patient undergoing elective cardioversion or emergency cardioversion of a life-threatening arrhythmia.
Failure to successfully defibrillate a patient may
occur for a number of reasons, including inadequate
predefibrillation cardiopulmonary resuscitation
(CPR) technique, operator error (e.g., poor paddle
application), or depleted or defective batteries (the
most common cause of defibrillator failure with battery-powered units). There is no time to troubleshoot
or correct even minor difficulties during emergencies,
A NONPROFIT AGENCY
Time Required
since every minute of delay significantly decreases the
probability of a successful resuscitation attempt.
Overview
009020
408-0595
Interval Used
By Hospital
In addition to periodic inspections, clinical staff
should perform visual inspections and ensure that
batteries are charging at the beginning of each work
shift and after each use of the device. They should also
perform discharge testing at least once a week. A User
Checklist for Defibrillators/Monitors/Pacemakers is
included in Health Devices 1993 May-Jun; 22:291-2.
Citations from Health Devices
User error and defibrillator discharge failures [Hazard], 1986 Dec; 15:340.
Deteriorating insulation on internal defibrillator paddles [Hazard], 1987 Feb; 16:46.
Defibrillator paddle resistance (continuity) testing
[User Experience NetworkTM], 1987 Feb; 16:55.
Battery-powered defibrillator/monitors [Evaluation],
1987 Jun; 16:183-216. (See also 1987 Jul; 16:251.)
Mains (AC Line) power switches on battery-powered
equipment [Hazard], 1987 Sep-Oct; 16:345.
5200 Butler Pike, Plymouth Meeting, PA 19462-1298, USA
Telephone +1 (610) 825-6000 ● Fax +1 (610) 834-1275 ● E-mail [email protected]
Inspection and Preventive Maintenance System
Battery-powered defibrillator/monitors [Evaluation
Update], 1987 Dec; 16:389.
Misuse of “Quick Look” defibrillator paddles [Hazard],
1988 Feb; 17:68.
Lifepak 8 defibrillator/monitors [Hazard], 1988 Aug;
17:244.
Lifepak 8 defibrillator/monitors [Hazard Update],
1988 Sep; 17:273.
Physio-Control Lifepak 6 and 6s defibrillator/monitors
[Hazard], 1988 Aug; 17:245.
Overheating of replacement batteries in Physio-Control
Lifepak 6, 6s, and 7 defibrillator/monitors [Hazard
Update], 1992 Jun-Jul; 21:250.
Defibrillator/monitors and external noninvasive pacemakers [Evaluation], 1993 May-Jun; 22:212-94.
Defibrillator/monitors and external noninvasive pacemakers [Evaluation Update], 1993 Dec; 22:579-82.
Misalignment of mating cable and defib cassette connectors on Physio-Control Lifepak 8 defibrillator/monitor [Hazard], 1993 Dec; 22:595-7.
Physio-Control develops Mains Power switch cover
[Hazard Update], 1988 Nov; 17:356.
Sparking during discharge testing on Physio-Control
Lifepak 9 defibrillator/monitors [User Experience
NetworkTM], 1994 Mar; 23:98-9.
Battery pins on Lifepak 5 defibrillator/monitors [Hazard], 1989 Feb; 18:84.
Fires from defibrillation during oxygen administration
[Hazard], 1994 Jul; 23:307-9.
Porta Fib III defibrillator/monitor paddles [Hazard],
1989 May; 18:175.
Difficulty synchronizing with Zoll PD 1200 defibrillator/monitor/pacemaker [User Experience NetworkTM], 1994 Aug-Sep; 23:374-5.
Mismatch of CCP R2 181-239 cables and HP43100
defibrillators [Hazard], 1989 Jun; 18:233.
Maintenance and user errors with the Physio-Control
Lifepak 8 [User Experience NetworkTM], 1990 Feb;
19:59.
Replacement batteries for the Physio-Control Lifepak
6 and 7 [User Experience NetworkTM], 1990 Feb;
19:61.
Disposable difibrillator pads and electrodes [Evaluation], 1990 Feb; 19:33-56.
Hewlett-Packard defibrillator/monitors and Darox R2
electrodes [User Experience NetworkTM], 1990 Jul;
19:246.
Alarm lockup on ZMI PD 1200 defibrillator/monitors
[Hazard], 1990 Aug; 19:293-4.
Spontaneous charging of Hewlett-Packard 43100A defibrillator/monitor used with anterior/posterior paddle set during monopolar electrosurgery [Hazard],
1994 Oct-Nov; 23:455-6.
Test apparatus and supplies
Defibrillator analyzer
ECG simulator (calibrated output amplitudes and
rates are required for some tests)
Ground resistance ohmmeter
Leakage current meter or electrical safety analyzer
Stopwatch or watch with a second hand
The following equipment is necessary during acceptance testing only:
Function generator
Heart-rate alarms on ZMI ZOLL PD 1200 pacemaker/defibrillators [Hazard], 1990 Dec; 19:455-6.
Attenuator
Physio-Control Lifepak 10 defibrillator/monitor Sync
mode [User Experience NetworkTM], 1991 Jan;
20:30-1.
Transparent metric scale
ECG artifact and defibrillator/monitors [User Experience NetworkTM], 1991 Mar-Apr; 20:141.
Internal defibrillator paddles [User Experience NetworkTM], 1991 Dec; 20:497-8.
Use of Physio-Control Lifepak 8 defibrillator/monitors
with optional QUIK-PACE pacing cassette [User
Experience NetworkTM], 1992 May; 21:183.
2
Oscilloscope
Isolation test supply (included in some electrical
safety analyzers)
Special precautions
CAUTION: The high voltage present on defibrillator
paddles during discharge is extremely dangerous and
possibly lethal. Never perform tests alone. A second
person must be present to summon help and/or apply
CPR in the event of an emergency. Never hold or
contact the conductive electrode portion of the paddles
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Defibrillator/Monitors
unless you have confirmed that the defibrillator is
disarmed (not charged) and preferably off.
1.4
Testing input isolation requires the use of a line
voltage source. Although this source should include a
current-limiting resistor, use caution to avoid contact
with any portion of the circuit while it is energized.
If the device is mounted on a cart that has
electrical receptacles for additional equipment,
insert an AC plug into each, and check that it
holds firmly. Inspect resuscitation cart receptacles, including testing for wiring (e.g., using an
outlet tester) and tension of all three connections. Also inspect the resuscitation cart plug for
damage as described above.
A defibrillator/monitor must always be available in
the event of an emergency during the inspection.
Thus, perform the inspection in the vicinity of the
unit’s usual storage location, or ensure that a unit that
the clinical staff is familiar with is available as a
substitute.
Inspection testing may deplete the battery of battery-powered units. Ensure that a replacement unit
or a fully charged battery is available before you begin
testing. Do not test all the units in an area at one time,
since this will leave the staff inadequately equipped to
handle emergencies.
1.5
Line Cord. Inspect the cord (including resuscitation cart line cord, if appropriate) for signs of
damage. If damaged, replace the entire cord, or
if the damage is near one end, cut out the defective portion. Be sure to wire a new power cord
or plug with the same polarity as the old one.
Check line cords of battery chargers.
1.6
Strain Reliefs. Examine the strain reliefs at
both ends of the line cord. Be sure that they hold
the cord securely.
1.7
Circuit Breaker/Fuse. If the device has a
switch-type circuit breaker, check that it moves
freely. If the device is protected by an external
fuse, check its value and type against that
marked on the chassis, and ensure that a spare
is provided.
1.9
Cables. Inspect the cables of internal and external paddles, disposable defibrillation electrodes
(if applicable), and ECG electrodes for their
strain reliefs and general condition. Examine
cables carefully to detect breaks in the insulation
and to ensure that they are gripped securely in
the connectors at each end to prevent rotation or
other strain. Verify that an ECG can be displayed with either paddles or ECG leads used as
input. Wiggle, bend, and pull the cable to check
that continuity is not affected.
Procedure
Before beginning an inspection, carefully read this
procedure and the manufacturer’s instruction and
service manuals; be sure that you understand how to
operate the equipment, the significance of each control
and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive
maintenance procedures or frequencies are recommended by the manufacturer.
Defibrillator energies may be specified in either
joules (J) or watt-seconds; these are equivalent units
(i.e., 1 J = 1 watt-second).
1. Qualitative tests
1.1
Chassis/Housing. Examine the exterior of the
unit for cleanliness and general physical condition. Be sure that plastic housings are intact,
that all assembly hardware is present and tight,
and that there are no signs of spilled liquids or
other serious abuse.
1.2
Mount. If the device is mounted on a stand or
cart, examine the condition of the mount. If it is
attached to a wall or rests on a shelf, check the
security of this attachment.
1.3
Casters/Brakes. If the device moves on casters,
check their condition. Look for accumulation of
lint and thread around the casters, and be sure
that they turn and swivel, as appropriate. Check
the operation of brakes and swivel locks, if the
unit is so equipped.
AC Plug. Examine the AC power plug for damage. Attempt to wiggle the blades to determine
that they are secure. Shake the plug and listen
for rattles that could indicate loose screws. If
any damage is suspected, open the plug and
inspect it.
1.10 Fittings/Connectors. Examine all cable connectors for general condition. Electrical contact
pins or surfaces should be straight and clean.
Verify that leads and electrodes are firmly
gripped in their appropriate connectors. During
major inspections, disconnect the paddle connectors and look for misaligned pins, damaged receptacles, and carbon deposits from arcing.
Inspection and Preventive Maintenance System
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Inspection and Preventive Maintenance System
1.11 Paddles/Electrodes. Confirm that special paddles (e.g., pediatric, internal) and electrodes
(e.g., disposable difibrillation electrodes) are
available, if appropriate. Examine all paddles
for physical condition and cleanliness. Alert
clinical personnel responsible for the instrument
to the presence of dried electrode gel, physiologic
fluids, or debris on the paddle surface or handles.
Dirty electrodes prevent good electrical contact
and can cause burns. Electrode gel or other
debris on the insulating portion of the paddle can
cause operator shocks. Clean the paddles, if
needed, including the electrode surface and handle seams, and make sure that they are completely dry before proceeding with any further
testing.
Confirm that an adequate supply of ECG electrodes and disposable defibrillation electrodes (if
used) are available and that they are stored
properly and are within their expiration dates.
1.13 Controls/Switches. Examine all controls and
switches for physical condition, secure mounting, and correct motion. Where a control should
operate against fixed-limit stops, check for
proper alignment as well as positive stopping.
Check membrane switches for membrane damage (e.g., from fingernails, pens). During the
course of the inspection, check that each control
and switch performs its proper function.
If the unit has redundant control functions
(e.g., a charge button on the front panel and on
a paddle), ensure that both controls function
properly. Verify that activating just one paddle
discharge button will not cause the unit to discharge. A front-panel discharge button should
control only internal paddles (or disposable defibrillator electrodes, on some units) and should
not cause discharge when external paddles are
connected.
1.17 Battery/Charger. Inspect the physical condition of batteries and battery connectors, if readily accessible. Verify that the charger of
battery-operated units is plugged into a live AC
outlet and that the charger is attached to the
defibrillator (i.e., charger cable is attached, unit
is firmly seated into charging stand or mount,
instrument end of line cord is attached, and
charging light is on). For units with removeable
batteries that are charged in a separate charger,
verify that the batteries are properly installed
and that the charging, or ready, light is on.
4
If the monitor can be separated from the defibrillator, make sure that it is securely connected
to the defibrillator. Inform clinical personnel of
any deficiencies so that problems can be avoided
in the future.
Perform the inspection with the unit on battery power to check that monitor and defibrillator batteries are charged and can hold a charge.
Check battery capacity by activating the battery
test function or measuring the battery-powered
operating time. When it is necessary to replace
a battery, label it with the date.
Some batteries require periodic deep discharges and recharging to maintain maximum
battery capacity. If the manufacturer recommends this procedure, verify that it is being
performed on schedule.
1.18 Indicators/Displays. During the course of the
inspection, confirm the operation of all lights,
indicators, meters, and visual displays on the
unit and charger. Be sure that all segments of a
digital display function.
Observe a simulated ECG signal on the display, and verify compliance with the following
criteria:
The baseline should stay in focus across the
display.
The baseline should be horizontal and should
not be noticeably sloped or bowed.
The pulses from an ECG simulator should be
regularly spaced (uneven spacing indicates a
sweep nonlinearity).
All portions of a simulated ECG waveform
should be clear and visible, including the
P-wave and QRS.
When the vertical position of the baseline is
varied by adjusting the vertical position control, the baseline should move throughout
most of the vertical height of the display.
There should be no distortion in the baseline
as it is moved up or down on the screen. In
monitors that incorporate a self-centering
baseline and therefore lack a position control,
the baseline should be correctly positioned.
Ambient light should not affect the visibility of
the trace. (If monitors are located so that ambient light reflects from the face of the display,
making the ECG difficult to see, control the
ambient light or use a filter over the display.)
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©1995 ECRI. All Rights Reserved.
Defibrillator/Monitors
alarm-silence feature, check the method of reset
(i.e., manual or automatic) against the manufacturer’s specifications.
1.21 Audible Signals. Operate the device to activate
any audible signals (e.g., charge tone). Confirm
appropriate volume, as well as the operation of
a volume control.
1.22 Labeling. Check that all necessary placards, labels, and instruction cards are present and legible.
Figure 1. The calibration pulse or step response leading
edge should have square corners (left). Slight rounding
(middle) or small overshoot is acceptable. Excessive
rounding or overshoot (right) indicates the need for
adjustment.
“Burn spots” should not be visible on the cathode-ray tube. (The phosphor may “burn” if the
intensity is set too high. The cathode-ray tube
face will be discolored if this condition exists.)
Sixty-hertz or other noise (interference)
should not be superimposed on the baseline
with the ECG simulator attached. Baseline
interference may be apparent as a thick baseline at high gain settings, but should be invisible throughout the lower two-thirds of the
gain control range.
1.23 Accessories (gel, pads, or electrodes). Verify that
defibrillator gel, disposable defibrillator pads, or
disposable defibrillator electrodes are stored
with the unit and are within their expiration
dates. Confirm that defibrillator gel is being
used, not skin lubricant or ultrasound or TENS
gel. Notify appropriate clinical personnel if any
accessories are missing.
1.24 Internal Discharge of Stored Energy. To protect
personnel from accidental shock, it should be
possible to discharge the stored energy safely in
the event that the operator decides not to use the
defibrillator after it has been charged. Verify
that the unit rapidly releases the stored energy
when the power is turned off. If the unit also has
a front-panel button for this purpose, verify its
operation.
1.19 1 mV Step Response. Depress and hold the 1 mV
calibration button (or apply an external 1 mV
pulse) for about 3 sec. The trace should exhibit a
sharp, square-cornered leading edge that is neither rounded nor spiked (up to 10% spike or
overshoot is acceptable but will usually not be
observed in a unit that is functioning optimally;
see Figure 1). After 1 to 2 sec, the pulse should
have decayed to no more than half its original
amplitude (see Figure 2).
With the gain set to yield about 20 mm deflection for a 1 mV input (×2 or 0.5 mV/div), compare
the amplitude of the internal calibration pulse
and an external 1 mV signal (from a calibrated
ECG simulator). At a 20 mm deflection, they
should be within about 2 mm (10%) of each other.
1.20 Alarms. Operate the device in such a way as to
activate each audible and visual alarm (e.g.,
heart rate alarm, if so equipped). Check for adequate alarm tone volume and any associated
features (e.g., automatic direct writer activation,
display freeze function). If the device has an
Figure 2. Sag time is measured to the half-amplitude
point. The upper trace indicates a low-frequency response of about 0.05 Hz. The lower trace indicates a
low-frequency response of between 0.07 and 0.09 Hz.
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Inspection and Preventive Maintenance System
continuity checks. The resistance from the paddle
or electrode connector to the appropriate pin of the
connector should not exceed 0.15 Ω.
1.25 Special Features.
Synchronizer (major inspection only). If the unit
has a synchronization mode, verify that the
unit will not discharge while in this mode
when no ECG signal is present and that it will
discharge when a simulated ECG is applied.
Recorder. If the unit has a recorder, confirm that
it operates smoothly, that the paper feeds
evenly and does not stray from side to side,
and that the trace is of good quality (i.e., dark
and thin) at all paper speeds. Perform the 1
mV step response test (Item 1.19) on the recorder.
2.4
Rate Calibration. Using a simulated ECG with
rates of 60 and 120 pulses per minute, verify that
the heart rate indicator displays a rate within
5% or 5 bpm, whichever is greater, of the set rate
(55 to 65 bpm, 119 to 126 bpm). Verify that the
QRS visual and audible indicators are functioning.
2.5
Rate Alarm. The setup remains the same as for
the previous test. Verify that the alarm activates
when the input rate is set just below or above
typical low and high rate alarm settings (e.g., 40
and 120 bpm, respectively). The difference between the rate displayed on the rate indicator
and that at which the alarm activates should not
exceed 5% or 5 bpm, whichever is greater.
2.6
Internal Paddle Energy Limit. When used with
internal paddles for application of the defibrillator output directly to the heart, the energy
should not exceed 50 J. Test this feature on any
unit that is located where it may be used with
internal paddles or that may be moved to such a
location. Connect the internal paddles, charge
the defibrillator to maximum energy, and discharge it into the defibrillator analyzer. Verify
that the output does not exceed 50 J.
2. Quantitative tests
2.1
2.2
2.3
6
Grounding Resistance. Using an ohmmeter,
electrical safety analyzer, or multimeter with
good resolution of fractional ohms, measure
and record the resistance between the grounding pin of the power cord (if so equipped) and
exposed (unpainted and not anodized) metal on
the defibrillator chassis. Repeat this test for
the charger, if applicable. We recommend a
maximum of 0.5 Ω.
Chassis Leakage Current. Measure chassis
leakage current to ground with the grounding
conductor of plug-connected equipment temporarily opened and the unit off, on, charging, and
charged. Record the maximum leakage current.
Chassis leakage current to ground should not
exceed 300 µA.
Paddle Continuity. Paddle continuity is typically checked by verifying the presence of an
ECG signal obtained through the paddles (Item
1.9). However, if additional paddles or disposable
defibrillation electrodes are available for use
with the defibrillator (e.g., internal or pediatric
paddles), these must be checked. Either attach
the paddles or electrode cable to the unit (e.g., in
conjunction with Item 2.6) and verify continuity
with an ECG signal, or use an ohmmeter to verify
continuity from each paddle or electrode connector to the appropriate pin of the connector. Wiggle, bend, and pull the cable, especially near the
paddle and connector, to check that continuity is
not affected. (Current may jump across a small
break in the paddle lead and may not be detected
during defibrillator output tests. A continuity
test will detect such a defect before it gets worse.)
This check should also be done for the reusable
cable used with disposable defibrillation electrodes.
Internal paddles may require more frequent
2.10 Output Energy. During major inspections,
measure output energy at minimum, intermediate, and maximum energy settings. If the defibrillator is commonly used for cardioversion, a
50 J level is satisfactory for the intermediate
range.
At each energy level, record the control setting, indicated energy (on the unit’s energy meter), and delivered energy (measured by a
defibrillator analyzer) after discharging the defibrillator into the analyzer as soon as it is
charged.
At its maximum setting, the unit should be
able to deliver at least 250 J. The output energy
should be within 4 J at low settings (below 25 J)
or 15% of the set energy (and indicated energy if
so equipped) at higher energies.
If the output of a defibrillator is unusually low
at very low control settings, check for a break in
the cables or a defective connector.
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Defibrillator/Monitors
same day unless provisions are made for backup
units or spare charged batteries. Batteries may
take considerable time to recharge, and a fully
charged unit must be available for emergencies.
During minor inspections, verify output at
only one energy level. Use the defibrillator’s internal test load, if so equipped. Typically, this
provides either a numeric or a pass/fail indicator
to verify that energy was delivered.
2.11 Energy After 60 Sec. Deterioration of the energy
storage capacitors in some defibrillators results
in charge leakage after the charging circuit has
been de-energized. In these units, it is possible
for the available energy to decrease if the unit is
not discharged at the earliest possible moment.
The following test will identify this deficiency.
3. Preventive maintenance
3.1
Clean the exterior, paddles, rollers, and platen.
3.2
Lubricate the chart recorder paper drive per the
manufacturer’s recommendations, if required.
3.4
Replace the battery if any of the test procedures
indicate it is weak or defective, even after charging for 12 hr or more.
Charge the defibrillator to its maximum setting, but do not discharge for 1 min. The delivered energy should be at least 85% of that
obtained when the unit is discharged immediately (as in Item 2.10) and should meet manufacturer specifications for charge leakage. (Note
that some units are designed to intentionally
bleed or discharge the capacitor charge if the
defibrillator is not discharged within a set time
period. These units should meet manufacturer
specifications.)
2.12 Charge Time and Max Energy (10th Charge). In
resuscitation attempts, it is not uncommon for
the operator to call for multiple defibrillation
shocks in rapid succession. Battery-powered defibrillators may not have sufficient energy left in
their batteries to deliver 10 shocks. These deficiencies are best discovered during periodic inspections, rather than during clinical use.
Charge battery-powered units to maximum
energy and discharge 10 times through the analyzer (verify that the analyzer load will not be
damaged by repeated discharge). On the 10th
cycle, record the charging time (i.e., the time for
the meter to equilibrate or for the ready light to
come on) and the delivered energy. To avoid
excessive battery depletion, stop the test and
record the number of discharges and the values
measured if the charging time exceeds 15 sec
before the 10th discharge. Also stop the test if
the battery-condition meter indicates a weak
battery or, on some defibrillators, if the internal
circuitry terminates the charge early.
The time to charge to maximum energy should
not exceed 15 sec. The output energy should
remain within 4 J or 15% of the selected energy
throughout the test.
CAUTION: Do not perform this test on all
battery-operated defibrillators in an area on the
Some users have also reported that periodic
prophylactic battery replacement, either annually or every other year, increases reliability and
decreases service calls. In this case, mark the
date of the battery replacement on the battery or
unit and check it during each inspection. Perform the inspection after battery replacement
and a suitable charge period.
Some units have more than one battery (e.g.,
one for the monitor and one for the defibrillator,
batteries that can be switched by the user). Be
sure that all batteries are checked, maintained,
and replaced as required.
4. Acceptance tests
Conduct major inspection tests for this procedure
and the appropriate tests in the General Devices Procedure/Checklist 438.
CAUTION: Do not measure paddle leakage current
with the unit charged or charging or during discharge.
Most ECG monitors should meet the requirements
for isolated input devices for ECG lead-to-ground, interlead, and input isolation tests. Interlead testing
should include both ECG-to-ECG and ECG-paddle
tests. AAMI DF-2-1989, Standard for Cardiac Defibrillator Devices, calls for applying isolated input risk
current tests (source, sink, and interlead) to defibrillator paddles, but with limits of 100 µA for external
paddles and 50 µA for internal paddles.
In addition, perform the following tests.
4.1
Synchronizer Operation. Check the synchronizers of units so equipped. The thoroughness of
this test will depend upon the availability of test
equipment.
Set the defibrillator to deliver low output energy (50 J or less). Use an ECG signal to trigger
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
7
Inspection and Preventive Maintenance System
the synchronizer and fire the defibrillator into a
50 Ω load (e.g., a defibrillator analyzer). Confirm
that, with the ECG simulator off, the defibrillator does not discharge. With a signal applied,
confirm that the synchronizer marker or other
indicator is functioning properly.
Use a dual-channel oscilloscope to note the time
delay between the peak of a QRS pulse (from an
ECG simulator) and the defibrillator pulse (from a
defibrillator analyzer). Use the ECG signal to trigger the oscilloscope’s sweep. Some defibrillator
analyzers have synchronizer test functions. With
an ECG amplitude sufficient to activate the
marker or indicator and the discharge buttons
depressed, the defibrillator should discharge in
60 msec or less following the R-wave peak. Most
units will trigger on the first QRS pulse after the
buttons are depressed, although some units are
designed to delay until the second or third QRS to
avoid unintentional discharges.
4.2
Internal Paddle Energy Limit. During acceptance testing, perform Item 2.6 on all units
equipped with this feature, regardless of intended location for the device.
4.3
Integral Output Tester. Check the operation and
accuracy of any integral defibrillator test load, if
so equipped.
4.4
Common Mode Rejection Ratio (CMRR). The
ECG monitor includes a differential amplifier so
that it can display the voltage difference between
two electrodes (the RA and LA in Lead 1) while
using a third (RL) as a reference. If the same, or
common, voltage is applied to RA and LA simultaneously, there should be no output from the
differential amplifier because the voltage difference between the two inputs is zero. The extent
to which a differential amplifier produces no
output when the same signal is applied to both
inputs is called its common mode rejection ratio.
Common mode rejection is needed in monitors
because of the presence of stray signals, common
to all input leads primarily at power-line frequency
(60 Hz). While these signals are too minute to be
hazardous, they can interfere with the ECG display of a monitor with a low CMRR at 60 Hz.
The CMRR is defined as:
CMMR =
Differential mode deflection factor, or DMD (mm ⁄ mV)
Common mode deflection factor, or CMD (mm ⁄ mV)
Calculate the common mode deflection factor by
dividing the resultant deflection (in mm) by the
8
Figure 3. Signal input test setup.
input signal (in mV). The CMRR may then be
calculated as the differential mode deflection factor divided by the common mode deflection factor.
A deflection factor is the change in trace position corresponding to a given input voltage to
the monitor. Use an unbalanced CMRR measurement that has a 5,000 Ω resistor in series
with one of the input leads to the monitor. This
simulates unequal impedances in the electrode/skin interface of the monitor electrodes, as
commonly exists in practice.
Since most common mode voltage in the hospital is at 60 Hz, it is most significant to measure
the CMRR at or near that frequency. (A frequency of 55 Hz is often used to minimize interference from power-line frequency noise.) Using
the test setup shown in Figure 3, apply a sinusoid
test signal of 1 mV peak-to-peak at about 60 Hz
to the monitor. Turn up the monitor gain so that
the deflection is at least 20 mm. Measure the
deflection in millimeters, and record it on the
inspection form as the differential mode deflection factor. Since the input signal for this measurement was 1 mV, the differential mode
deflection factor expressed in mm/mV is numerically equal to the resultant deflection in millimeters. Do not vary the gain of the monitor or the
signal frequency for the remainder of this test.
Record the frequency on the form.
Use the test setup shown in Figure 4 for the
second part of this measurement. Note that
there is only one connection from the output of
the attenuator to the patient leads. The other
output terminal is grounded. It is essential that
all instruments used in this test be connected to
a common ground to minimize noise.
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©1995 ECRI. All Rights Reserved.
Defibrillator/Monitors
correction should be made in calculating paper
speed. The paper speed should be accurate to
within 2% (although 5% is allowed by some organizations). At a chart speed of 25 mm/sec and
a pulse interval of 1,000 msec (60 bpm on an ECG
simulator), the distance between the first and
last of 5 successive peaks should be 100 ±2 mm;
at a chart speed of 50 mm/sec, the distance between
the first and last of 5 successive peaks should be
200 ±4 mm.
4.8
Alarm Delay. In addition to checking rate alarm
accuracy (Item 2.5), use the same test setup to
determine alarm delay. First, set the high rate
alarm to 100 bpm and the ECG simulator to 60
bpm. Quickly change the simulator rate to 120
bpm, and use a stopwatch or watch with a second
hand to measure the time until the alarm
sounds. Check the low rate alarm similarly (set
alarm for 40 bpm, change rate from 60 to 30
bpm). Generally, alarm delays should not exceed about 10 sec.
4.9
Repeated Discharge and Operating Time.Verify
that the battery meets hospital or manufacturer
specifications for number of defibrillation shocks
and monitor operating time. Units should meet
requirements with all functions operating (including alarms sounding) unless otherwise specified.
Figure 4. Common mode rejection ratio test setup.
Increase the amplitude of the sinusoid signal
(up to 10 V peak-to-peak) until some measurable
deflection is observed on the monitor.
If the unit has an ungrounded or plastic case,
measure the CMRR with the unit resting on a
grounded metal plate. CMRR should meet the
manufacturer’s specification and be at least 10,000:1.
4.5
4.6
4.7
Gain. Apply a 2 mV signal at a gain setting of
10 mV/mm (or ×1) and measure the displayed
amplitude with a transparent scale. Verify that
the displayed signal size changes appropriately
(within 10%) as the gain setting is changed. For
example, if a 2 mV signal produces a 20 mm
deflection at a ×1 gain, the deflection should be
36 to 44 mm at ×2. Test both the monitor display
and recorder.
Perform Item 2.12 on line-powered units to
verify that each unit is able to provide at least 10
sequential defibrillation shocks.
Before returning to use
QRS Sensitivity. If the monitor includes a QRS
indicator or beeper or a heart rate meter, verify
that the QRS detector circuit is functioning properly. Connect an ECG simulator with variable
output to the monitor, and set it for a rate of
60 bpm. Vary the output amplitude over a
range of 0.5 to 5 mV (use the monitor, display to
estimate amplitude if the simulator does not
have a calibrated output). The monitor should
reliably detect all beats and should not doublecount. It should not detect QRS amplitudes of
less than 0.15 mV. If the unit has a manual
sensitivity control, check that it is functioning
properly as evidenced by the need to change the
setting during this test.
Return the energy select control to its normal setting. Before connecting the charger on battery-powered
units, check the battery condition to verify that there
is adequate battery charge. If there is not, or if doubt
exists, ensure that a suitable replacement defibrillator
is available, and allow the unit just inspected to charge
in an out-of-the-way location (i.e., where it will not be
taken for use by clinical personnel). Battery-powered
units should be connected to the charger, with the
charger plugged into a wall outlet and the charging
light on. For units with removable batteries that are
charged in a separate charger, replace the battery used
during testing with a fully charged battery, and place
the used battery in the charger for proper charging.
Paper Speed. On units with a chart recorder, use
an ECG simulator set to 60 bpm or a signal or pulse
generator set to 1 Hz that has been set or calibrated
with a counter. If the interval between pulses is
not within 10 msec of 1,000 msec, an appropriate
Conduct a performance verification check, including pressing all the front-panel function buttons, to
verify that the unit is in a standard service mode.
Performance-verification procedures are often included in the service manual.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
9
Procedure/Checklist 407-0595
Defibrillators
Used For:
Defibrillators, Battery-Powered [11-134]
Defibrillators, Line-Powered [11-137]
Also Called: Cardioverters
Commonly Used In: Coronary and special care areas, emergency departments, operating rooms, resuscitation carts, patient care areas, emergency medical vehicles
Scope: Applies to battery- and line-powered defibrillators used with external and internal paddles and/or
disposable defibrillation electrodes; does not apply to units that have both defibrillation and monitoring
functions (see Defibrillator/Monitors Procedure/Checklist 408)
Risk Level: ECRI Recommended, High; Hospital Assessment,
Type
ECRI-Recommended
Interval
Major
12 months
months
.
hours
Minor
6 months
months
.
hours
Overview
Defibrillators are critical resuscitation instruments.
Their failure to perform effectively may result in the
death of a patient undergoing resuscitation or cause
further cardiac damage or even death in a patient
undergoing elective cardioversion or emergency
cardioversion of a life-threatening arrhythmia.
Failure to successfully defibrillate a patient may
occur for a number of reasons, including inadequate
predefibrillation cardiopulmonary resuscitation (CPR)
technique, operator error (e.g., poor paddle application), or depleted or defective batteries (the most common cause of defibrillator failure with battery-powered
units). There is no time to troubleshoot or correct even
minor difficulties during emergencies, since every minute of delay significantly decreases the probability of
a successful resuscitation attempt.
In addition to periodic inspection, clinical staff
should perform inspections and ensure that batterypowered units are charging at the beginning of each
work shift and after each use of the device. They should
009021
407-0595
A NONPROFIT AGENCY
Interval Used
By Hospital
Time Required
also perform discharge testing at least once a week. A
User Checklist for Defibrillator/Monitor/Pacemakers
is included in Health Devices 1993 May-Jun; 22:291-2.
Citations from Health Devices
Daily checks of defibrillators [Consultant’s Corner],
1983 Mar; 12:120-1.
Line-powered defibrillators [Evaluation], 1983 Oct;
12:291-314.
Defibrillating patients connected to electrocardiographs [Evaluation], 1984 Aug; 13:254.
User error and defibrillator discharge failures [Hazard], 1986 Dec; 15:340.
Deteriorating insulation on internal defibrillator paddles [Hazard], 1987 Feb; 16:46.
Defibrillator paddle resistance (continuity) testing
[User Experience NetworkTM], 1987 Feb; 16:55.
Disposable defibrillator pads and electrodes [Evaluation], 1990 Feb; 19:33-56.
5200 Butler Pike, Plymouth Meeting, PA 19462-1298, USA
Telephone +1 (610) 825-6000 ● Fax +1 (610) 834-1275
●
E-mail [email protected]
Inspection and Preventive Maintenance System
Hewlett-Packard defibrillator/monitors and Darox R2
electrodes [User Experience NetworkTM], 1990 Jul;
19:246.
ECG artifact and defibrillator/monitors [User Experience NetworkTM], 1991 Mar-Apr; 20:141.
Internal defibrillator paddles [User Experience NetworkTM], 1991 Dec; 20:497-8.
Use of Physio-Control Lifepak 8 defibrillator/monitors
with optional QUIK-PACE pacing cassette [User
Experience NetworkTM], 1992 May; 21:183.
Overheating of replacement batteries in Physio-Control Lifepak 6, 6s, and 7 defibrillator/monitors [Hazard Update], 1992 Jun-Jul; 21:250.
Defibrillator/monitors and external noninvasive pacemakers [Evaluation], 1993 May-Jun; 22:212-94.
Defibrillator/monitors and external noninvasive pacemakers [Evaluation Update], 1993 Dec; 22:579-82.
Misalignment of mating cable and defib cassette connectors on Physio-Control Lifepak 8 defibrillator/monitor [Hazard], 1993 Dec; 22:595-7.
Fires from defibrillation during oxygen administration
[Hazard], 1994 Jul; 23:307-9.
Spontaneous charging of Hewlett-Packard 43100A defibrillator/monitor used with anterior/posterior paddle set during monopolar electrosurgery [Hazard],
1994 Oct-Nov; 23:455-6.
Test apparatus and supplies
you have confirmed that the defibrillator is disarmed
(not charged) and preferably off.
Testing input isolation requires the use of a line
voltage source. Although this source should include a
current-limiting resistor, use caution to avoid contact
with any portions of the circuit while it is energized.
A defibrillator must be available in the event that
an emergency occurs during the inspection. Thus,
perform the inspection in the vicinity of the unit’s
usual storage location, or ensure that a similar unit
that the clinical staff is familiar with is available as a
substitute.
Battery depletion may occur as a result of the inspection testing of battery-powered units. Ensure that
a replacement unit or a fully charged battery is available before you begin testing. Do not test all batterypowered units in an area at the same time, since this
will leave the staff inadequately equipped to handle
emergencies until the batteries recharge.
Procedure
Before beginning an inspection, carefully read this
procedure and the manufacturer’s instruction and service manuals; be sure that you understand how to operate the equipment and the significance of each control
and indicator. Also determine whether any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer.
Defibrillator energies may be specified in either
joules (J) or watt-seconds; these are equivalent units
(i.e., 1 J = 1 watt-second).
Defibrillator analyzer
Ground resistance ohmmeter
1. Qualitative tests
Leakage current meter or electrical safety analyzer
1.1
Chassis/Housing. Examine the exterior of the
unit for cleanliness and general physical condition. Be sure that plastic housings are intact,
that all assembly hardware is present and tight,
and that there are no signs of spilled liquids or
other serious abuse.
1.2
Mount. If the device is mounted on a stand or
cart, examine the condition of the mount. If it is
attached to a wall or rests on a shelf, check the
security of this attachment.
1.3
Casters/Brakes. Check the condition of cart
casters. Look for accumulations of lint and
thread around the casters, and be sure that they
turn and swivel, as appropriate. Check the operation of brakes and swivel locks, if the cart is
so equipped.
Stopwatch or watch with a second hand
ECG simulator and ECG monitor (only for units
with synchronization capability)
Oscilloscope (acceptance testing only)
Isolation test supply (included in some electrical
safety analyzers; acceptance testing only)
Special precautions
CAUTION: The high voltage present on defibrillator
paddles during discharge is extremely dangerous and
possibly lethal. Never perform testing alone. A second
person must be present to summon help and/or apply
CPR in the event of an emergency. Never hold or contact
the conductive electrode portion of the paddles unless
2
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Defibrillators
1.4
AC Plug. Examine the AC power plug for damage. Attempt to wiggle the blades to determine
that they are secure. Shake the plug and listen
for rattles that could indicate loose screws. If
any damage is suspected, open the plug and
inspect it.
If the device is mounted on a cart that has
electrical receptacles for additional equipment,
insert an AC plug into each and check that it is
held firmly. Inspect resuscitation cart receptacles, including testing for wiring (e.g., using an
outlet tester) and tension of all three connections. Also inspect the resuscitation cart plug for
damage as described above.
1.5
Line Cord. Inspect the cord (including resuscitation cart line cord, if appropriate) for signs of
damage. If damaged, replace the entire cord or,
if the damage is near one end, cut out the defective portion. Be sure to wire a new power cord or
plug with the correct polarity. Check line cords
of battery chargers.
1.6
Strain Reliefs. Examine the strain reliefs at
both ends of the line cord. Be sure that they hold
the cord securely.
1.7
Circuit Breaker/Fuse. If the device has a switchtype circuit breaker, check that it moves freely. If
the device is protected by an external fuse, check
its value and type against that marked on the
chassis, and ensure that a spare is provided.
1.9
Cables. Inspect the cables of internal and external paddles, disposable defibrillation electrodes
(if applicable), and synchronizer cables for their
strain reliefs and general condition. Examine
cables carefully to detect breaks in the insulation
and to ensure that they are gripped securely in
the connectors at each end to prevent rotation or
other strain.
1.10 Fittings/Connectors. Examine all cable connectors for general condition. Electrical contact
pins or surfaces should be straight and clean.
Verify that leads and electrodes are firmly
gripped in their appropriate connectors. During
major inspections, disconnect the paddle connectors and look for misaligned pins, damaged receptacles, and carbon deposits from arcing.
1.11 Paddles/Electrodes. Confirm that special paddles (e.g., pediatric, internal) and electrodes
(e.g., disposable defibrillation electrodes) are
available if appropriate for the area of use. Examine all paddles for physical condition and
cleanliness. Alert clinical personnel responsible
for the instrument to the presence of dried electrode gel, physiologic fluids, or debris on the
paddle surface or handles. Dirty electrodes prevent good electrical contact and often cause
burns. Electrode gel or other debris on the insulating portion of the paddle can cause operator
shocks. Clean the paddles if needed, including
electrode surfaces and handle seams, and ensure
that they are completely dry before proceeding
with any testing.
Confirm that an adequate supply of ECG electrodes and disposable defibrillation electrodes (if
used) are available and that they are stored
properly and are within their expiration dates.
1.13 Controls/Switches. Examine all controls and
switches for physical condition, secure mounting, and correct motion. Where a control should
operate against fixed-limit stops, check for
proper alignment, as well as positive stopping.
Check membrane switches for membrane damage (e.g., from fingernails, pens). During the
course of the inspection, check that each control
and switch performs its proper function.
If the unit has redundant control functions
(e.g., a charge button on the front panel and on
a paddle), ensure that both controls function
properly. Verify that activating just one paddle
discharge button will not discharge the unit
(both buttons must be pressed simultaneously to
discharge). A front-panel discharge button
should control only internal paddles (or disposable defibrillator electrodes on some units) and
should not cause discharge when external paddles are connected.
1.17 Battery/Charger. Inspect the physical condition of batteries and battery connectors, if readily accessible. Verify that the charger of
battery-operated units is plugged into a live AC
outlet and that the charger is attached to the
defibrillator (i.e, charger cable is attached, unit
is firmly seated into charging stand or mount,
instrument end of line cord is attached, and
charging light is on). For units with removable
batteries that are charged in a separate charger,
verify that the batteries are properly installed
and that the charging, or ready, light is on.
Inform clinical personnel of any deficiencies or
improper use.
Perform the inspection with the unit on battery
power to check that the defibrillator batteries are
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
3
Inspection and Preventive Maintenance System
charged and can hold a charge. Check battery
capacity by activating the battery test function
or measuring the battery-powered operating
time. When it is necessary to replace a battery,
label it with the date.
exposed (unpainted and not anodized) metal on
the defibrillator chassis (and charger if applicable). We recommend a maximum of 0.5 Ω.
2.2
Chassis Leakage Current. Measure chassis
leakage current to ground with the grounding
conductor of plug-connected equipment temporarily opened and the unit off, on, charging, and
charged. Record the maximum leakage current.
Leakage current from chassis to ground should
not exceed 300 µA.
2.3
Paddle Continuity. Use an ohmmeter to verify
continuity from each paddle (internal and external) to the appropriate pin of the paddle connector. Wiggle, bend, and pull the cable, especially
near the paddle and connector, to check that
continuity is not affected. (Current may jump
across a small break in the paddle lead and may
not be detected during defibrillator output tests.
An ohmmeter test will detect such a discontinuity
before it gets worse.) This check should also be
done for the reusable cable used with disposable
defibrillation electrodes. Internal paddles may
require more frequent continuity checks. The
resistance from the paddle to the appropriate pin
of the paddle connector should not exceed 0.15 Ω.
2.4
Energy After 60 Sec. Deterioration of the energy
storage capacitors in some defibrillators results
in charge leakage after the charging circuit had
been deenergized. In these units, it is possible
for the available energy to decrease if the unit is
not discharged at the earliest possible moment.
Use the following test to identify this deficiency.
Some batteries require periodic deep discharges and recharging to maintain maximum
capacity. If the manufacturer recommends this
procedure, verify that it is being performed on
schedule.
1.18 Indicators/Displays. During the course of the
inspection, confirm the operation of all lights,
indicators, meters, gauges, and visual displays
on the unit and charger, if so equipped. Be sure
that all segments of a digital display function.
1.21 Audible Signals. Operate the device to activate
any audible signals (e.g., charge tone). Confirm
appropriate volume, as well as the operation of
a volume control.
1.22 Labeling. Check that all necessary placards, labels, and instruction cards are present and legible.
1.23 Accessories (gel, pads, or electrodes). Verify that
defibrillator gel, disposable defibrillator pads, or
disposable defibrillator electrodes are stored
with the unit and that they are within their
expiration dates. Confirm that defibrillator gel
is being used, not skin lubricant or ultrasound or
TENS gel. Notify appropriate clinical personnel
if any accessories are missing.
1.24 Internal Discharge of Stored Energy. To protect
personnel from accidental shock, it should be
possible to discharge the stored energy safely in
the event that the operator decides not to use the
defibrillator after it has been charged. Verify
that the unit releases the stored energy when the
power is turned off. If the unit has a front-panel
button for this purpose, verify proper operation.
Charge the defibrillator to its maximum setting, but do not discharge it for 1 min. The
delivered energy should be at least 85% of that
obtained when the unit is discharged immediately (as in Item 2.10) and should meet manufacturer specifications for charge leakage.
(Some units are designed to intentionally bleed
or discharge the capacitor charge if the defibrillator is not discharged within a set time period.
These units should meet the manufacturer’s
specifications.)
1.25 Synchronizer. If the unit has a synchronization
mode, verify that the unit will not discharge
while in this mode when no ECG signal is present and that it will discharge when a simulated
ECG signal is applied.
2.5
2. Quantitative tests
2.1
4
Grounding Resistance. Using an ohmmeter,
electrical safety analyzer, or multimeter with
good resolution of fractional ohms, measure and
record the resistance between the grounding pin
of the power cord (or charger power cord) and
Internal Paddle Energy Limit. Defibrillator output, when used with internal paddles, should not
exceed 50 J. Test this feature on any unit that is
located where it may be used with internal paddles or that is portable and may be moved to such
a location. Connect the internal paddles, charge
the unit to maximum energy, and discharge it
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Defibrillators
The time to charge to maximum energy should
not exceed 15 sec. The output energy should
remain within 4 J or 15% of the selected energy
throughout the test.
into the defibrillator analyzer. Verify that the
output does not exceed 50 J.
2.10 Output Energy. During major inspections,
measure output energy at minimum, intermediate, and maximum energy settings. If the defibrillator is commonly used for cardioversion, a
50 J level would be satisfactory for the intermediate range.
At each energy level, record the control setting, indicated energy (on the unit’s energy meter), and delivered energy (measured by an
analyzer) after discharging the defibrillator into
the analyzer as soon as it is charged.
CAUTION: Do not perform this test on all
battery-operated defibrillators in an area on the
same day unless provisions are made for backup
units or spare charged batteries. Batteries may
take considerable time to recharge, and a fully
charged unit must be available for emergencies.
3. Preventive maintenance
3.1
Clean the exterior and paddles.
3.4
Replace the battery if any of the test procedures
indicate a weak or defective battery, even after
charging for 12 hr or more.
At its maximum setting, the unit should be
able to deliver at least 250 J. The output energy
should be within 4 J at low settings (below 25 J)
or 15% of the set energy (and the indicated energy, if so equipped) at higher energies.
Some users have also reported that periodic
prophylactic battery replacement, either annually or every other year, increases reliability and
decreases service calls. In such a case, mark the
date of the battery replacement on the battery or
unit and check it during each inspection. Perform the inspection after battery replacement
and a suitable charge period.
If the output is unusally low at very low control settings, check for a break in the cables or a
defective connector.
During minor inspections, verify output at
only one energy level. Use the defibrillator’s
internal test load, if so equipped. Typically, this
provides a numeric or a pass/fail indicator to
verify that energy was delivered.
Since some units have more than one battery,
be sure that all batteries are checked, maintained, and replaced as required.
4. Acceptance tests
2.11 Charge Time and Max Energy (10th Charge). In
resuscitation attempts, it is not uncommon for
the operator to call for multiple defibrillation
shocks in rapid succession. Battery-powered defibrillators may not have sufficient energy left in
their batteries to deliver 10 shocks. These deficiencies are best discovered during periodic inspections, rather than during clinical use.
Charge battery-powered units to maximum
energy and discharge 10 times through the analyzer (but first verify that the analyzer load will
not be damaged by repeated discharge). On the
10th cycle, record the charging time (i.e., the
time it takes the meter to equilibrate or the ready
light to come on) and the delivered energy. To
avoid excessive battery depletion, stop the test
and record the number of discharges and the
values measured if the charging time exceeds 15
sec before the 10th discharge. Also stop the test
if the battery-condition meter indicates a weak
battery or, on some defibrillators, if the internal
circuitry terminates the charge early.
Conduct major inspection tests for this procedure
and the appropriate tests in the General Devices Procedure/Checklist 438.
CAUTION: Do not measure paddle leakage current
with the unit charged or charging or during discharge.
AAMI DF-2-1989, Standard for Cardiac Defibrillator Devices, calls for applying isolated input risk current tests (source, sink, and interlead) to defibrillator
paddles, but with limits of 100 µA for external paddles
and 50 µA for internal paddles.
In addition, perform the following tests.
4.1
Synchronizer Operation. Check the synchronizers of units so equipped. An independent monitor
must be used in conjunction with the defibrillator to allow synchronized operation (although
this can be done, AAMI does not recommend it).
The thoroughness of this test will depend upon
the availability of test equipment. Connect the
monitor that will be used clinically to the defibrillator. Supply an ECG signal from an ECG
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
5
Inspection and Preventive Maintenance System
simulator to the monitor to trigger the discharge
of the defibrillator into a 50 Ω load (e.g., a defibrillator analyzer). Set the defibrillator to deliver low output energy (50 J or less). Confirm
that, with the ECG simulator off, the defibrillator does not discharge. With a signal applied,
confirm that the synchronizer marker or other
indicator is functioning properly.
Use a dual-channel oscilloscope to note the
time delay between the peak of a QRS pulse
(from an ECG simulator) and the defibrillator
pulse (from a defibrillator analyzer). Use the
ECG signal to trigger the oscilloscope’s sweep.
Some defibrillator analyzers have synchronizer
test functions. With an ECG amplitude sufficient
to activate the marker or indicator, the defibrillator should discharge within 60 msec or less
following the peak of the R wave, after the discharge buttons are depressed. The monitor
should provide its synchronizing signal within
35 msec of the R wave peak. The delay time
between the application of the most recent synchronizing signal from the monitor and the discharge should not exceed 25 msec. Thus, the
overall delay from the defibrillator and monitor
should not exceed 60 msec.
Most units will trigger on the first QRS after
depressing buttons, although some units are designed to delay until the second or third QRS to
avoid unintentional discharges.
6
4.2
Internal Paddle Energy Limit. During acceptance testing, perform Item 2.5 on all units
equipped with this feature, regardless of the
location intended for the device.
4.3
Repeated Discharge. Verify that the battery
meets hospital or manufacturer specifications
for the number of defibrillator shocks that can be
delivered. Perform Item 2.11 on line-powered
units to verify that the unit is able to provide at
least 10 sequential defibrillation discharges.
4.4
Integral Output Tester. Check the operation and
accuracy of any integral defibrillator test load, if
so equipped.
Before returning to use
Return the energy-select control to its normal setting. Before connecting the charger on battery-powered units, check the battery condition to verify that
there is an adequate battery charge. If there is not, or
if doubt exists, ensure that a suitable replacement
defibrillator is available, and allow the unit just inspected to charge in an out-of-the-way location (i.e.,
where it will not be taken for use by clinical personnel).
Otherwise, connect battery-powered units to the
charger, plug the charger into a wall outlet, and verify
that the charging light is on.
For units with removable batteries that are charged
in a separate charger, replace the battery used during
testing with a fully charged battery and place the used
battery in the charger for proper charging.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Procedure/Checklist 409-0595
ECG Monitors
Used For:
ECG Monitors [12-599]
Also Called: Cardiac monitors
Commonly Used In: Operating rooms, emergency rooms, critical care units as part of a physiologic
monitoring system, other special care areas, cardiac catheterization laboratories
Scope: Primarily applies to stand-alone ECG monitors (line or battery powered); appropriate for use in
conjunction with other procedures when inspecting physiologic monitoring systems that include multiple
physiologic parameters; adaptable for use with ECG telemetry systems and systems with central stations; also
applies to rate meters and direct writers for monitors with these features; does not apply to ECG arrhythmia
monitors or to monitors in defibrillator/monitor units (use Defibrillator/Monitors Procedure/Checklist 408)
Risk Level: ECRI Recommended, High; Hospital Assessment,
Type
ECRI-Recommended
Interval
Interval Used
By Hospital
Major
12 months*
months
.
hours
Minor
NA
months
.
hours
Time Required
*
This procedure is generally not required for a permanently installed system if the hospital routinely performs
a visual inspection of the area, paying reasonable attention to the monitors.
Overview
ECG monitors are routinely used on patients with
known or suspected cardiac arrhythmias. The monitors display the patient’s electrocardiogram so that
those attending the patient may continuously observe
the electrical activity of the heart. Since the monitor is
used only to observe the patient’s basic cardiac
rhythm, it need not meet the accuracy and fidelity
criteria expected of an electrocardiograph.
Citations from Health Devices
Artifacts from piezoelectric voltages [Consultant’s Corner], 1982 Nov; 12:27.
Patient monitoring systems [Evaluation], 1985 MarApr; 14:143.
GIGO: A compendium of ECG monitoring problems,
1985 Mar-Apr; 14:158.
009026
409-0595
A NONPROFIT AGENCY
Physiologic patient monitors [Evaluation], 1991 MarApr; 20:81.
ECG artifact in the OR [User Experience NetworkTM],
1991 Mar-Apr; 20:140.
Thermal injuries and patient monitoring during MRI
studies [Hazard], 1991 Sep; 20:362.
Physiologic patient monitors [Evaluation update],
1992 Mar-Apr; 21:123-8.
Risk of electric shock from patient monitoring cables
and electrode lead wires [Hazard], 1993 May-Jun;
22:301.
Test apparatus and supplies
ECG simulator (calibrated output amplitudes and
rates may be required for some tests)
Leakage current meter or electrical safety analyzer
5200 Butler Pike, Plymouth Meeting, PA 19462-1298, USA
Telephone +1 (610) 825-6000 ● Fax +1 (610) 834-1275
●
E-mail [email protected]
Inspection and Preventive Maintenance System
Ground resistance ohmmeter
The following equipment is necessary during acceptance testing only:
Signal generator
Attenuator
Oscilloscope
Transparent metric scale
Stopwatch or watch with a second hand
Special precautions
Testing monitor isolation requires the use of a line
voltage source. Although this source should include a
current-limiting resistor, use caution to avoid contact
with any portions of the energized circuit.
Inspection testing may deplete the battery of battery-powered units. Ensure that a replacement unit or
a fully charged battery is available before you begin
testing. Do not test all the units in an area at one time,
since this will leave the staff inadequately equipped.
Some monitors or monitoring systems provide multilead ECG signal processing and display (simultaneous display of two ECG leads). Conduct display quality
and performance tests on each channel. On singlechannel units that have lead switching, except where
otherwise indicated, all tests can be performed in one
lead, using the appropriate electrode leads (e.g., lead
I, using LA and RA as inputs).
When a monitor is part of a system with a remote or
central station display, use a separate inspection form
to record results for each display. Verify interactive
functions from each bedside (e.g., central station alarm
sounds, chart recorder activates when heart rate exceeds set limits). Test displays for each bedside separately, but test common elements (e.g., quality of
central chart recorder tracing) from only one bedside.
This is most easily accomplished with two people.
1. Qualitative tests
1.1
Chassis/Housing. Examine the exterior of the
unit for cleanliness and general physical condition. Be sure that plastic housings are intact,
that all assembly hardware is present and tight,
and that there are no signs of spilled liquids or
other serious abuse.
1.2
Mount. If the device is mounted on a stand or
cart, examine the condition of the mount. If it is
attached to a wall or rests on a shelf, check the
security of this attachment.
1.3
Casters/Brakes. If the device moves on casters,
check their condition. Look for accumulations of
lint and thread around the casters, and be sure
that they turn and swivel, as appropriate. Check
the operation of brakes and swivel locks, if the
unit is so equipped. Conductivity checks, where
appropriate, are usually done more efficiently as
part of a check of all equipment and furniture of
an area (see Procedure/Form 441, Conductive
Furniture and Floors).
1.4
AC Plug. Examine the AC power plug for damage. Attempt to wiggle the blades to determine
that they are secure. Shake the plug and listen
for rattles that could indicate loose screws. If
any damage is suspected, open the plug and
inspect it.
1.5
Line Cord. Inspect the cord for signs of damage.
If damaged, replace the entire cord or, if the
damage is near one end, cut out the defective
portion. Be sure to wire a new power cord or plug
with the same polarity as the old one. Also check
line cords of battery chargers.
Procedure
Before beginning an inspection, carefully read this
procedure and the manufacturer’s instruction and
service manuals; be sure that you understand how to
operate the equipment, the significance of each control
and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive
maintenance procedures or frequencies are recommended by the manufacturer.
Enter cross-referenced data related to the ECG
monitor at the top of the inspection form. Since the
monitor may be installed in a mainframe along with
other removable modules (e.g., blood pressure unit,
body temperature unit, recorder), assign a separate
control number to the mainframe and to each discrete
module. Enter the mainframe control number in the
Control No. space of the inspection form to identify the
entire device. This will help you locate the whole monitor or an individual module if follow-up action is
needed. Enter all module control numbers in the System Components box on the form, and indicate which
are covered on separate forms.
If the device is configured (i.e., different functions
are not in removable modules but are contained within
a single integral housing), assign only one control
number. In the System Components box, list any functions that will be inspected but recorded on separate
inspection forms (e.g., blood pressure), and note the
use of other forms.
2
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
ECG Monitors
1.6
Strain Reliefs. Examine the strain reliefs at
both ends of the line cord. Be sure that they hold
the cord securely.
1.7
Circuit Breaker/Fuse. If the device has a
switch-type circuit breaker, check that it moves
freely. If the device is protected by an external
fuse, check its value and type against that
marked on the chassis, and ensure that a spare
is provided.
1.9
Cables. Inspect the patient cable and leads and
their strain reliefs for general condition. Examine cables carefully to detect breaks in the insulation and to ensure that they are gripped
securely in the connectors of each end to prevent
rotation or other strain. Connect the unit to an
ECG simulator and verify that an adequate trace
is received at each patient lead selection. Flex
the patient cable near each end to verify that
there are no intermittent faults.
1.10 Fittings/Connectors. Examine all cable connectors for general condition. Electrical contact
pins or surfaces should be straight and clean.
Verify that leads and electrodes are firmly
gripped in their appropriate connectors.
1.11 Electrodes. Confirm that an adequate supply of
electrodes is on hand, and check the electrodes’
physical condition.
1.17 Battery/Charger. Inspect the physical condition of batteries and battery connectors, if readily accessible.
Check operation of
battery-operated power-loss alarms, if so
equipped.
Perform the inspection with the unit on battery power or operate the unit on battery power
for several minutes to check that the batteries
are charged and can hold a charge. Check battery
capacity by activating the battery test function
or measuring the output voltage. When it is
necessary to replace a battery, label it with the
date. Check the condition of the battery charger
and, to the extent possible, confirm that it does,
in fact, charge the battery.
Some batteries require periodic deep discharges
and recharging to maintain maximum battery capacity. If this is recommended by the manufacturer, verify that it is being performed on schedule.
1.18 Indicators/Displays. During the course of the inspection, confirm the operation of all lights, indicators, meters, and visual displays on the unit and
the charger (if appropriate). Be sure that all segments of a digital display function. Observe a
simulated ECG signal on a CRT display, and verify
compliance with the following criteria:
The baseline should stay in focus across the
display.
1.13 Controls/Switches. Before moving any controls
and alarm limits, check their positions. If any of
them appear inordinate (e.g., a gain control at
maximum, alarm limits at the ends of their range),
consider the possibility of inappropriate clinical
use or of incipient device failure. Record the settings of those controls that should be returned to
their original positions following the inspection.
The baseline should be horizontal and should
not be noticeably sloped or bowed.
Examine all controls and switches for physical
condition, secure mounting, and correct motion.
Check that control knobs have not slipped on
their shafts. Where a control should operate
against fixed-limit stops, check for proper alignment, as well as positive stopping. Check membrane switches for membrane damage (e.g., from
fingernails, pens). During the course of the inspection, check that each control and switch performs its proper function.
When the vertical position of the baseline is
varied by adjusting the vertical position control, the baseline should move throughout
most of the vertical height of the display.
There should be no distortion in the baseline
as it is moved up or down on the screen. In
monitors that incorporate a self-centering
baseline (and thus lack a position control), the
baseline should be correctly positioned.
Check alignment of touchscreen sensors. Verify that functions are activated when the center
of the desired function box is touched.
The pulses from an ECG simulator should be
regularly spaced (uneven spacing indicates a
sweep nonlinearity).
All portions of a simulated ECG waveform
should be clear and visible, including the Pwave and QRS.
Ambient light should not affect the visibility
of the trace. (If monitors are located so that
ambient light reflects from the face of the
display, making the ECG difficult to see, con-
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
3
Inspection and Preventive Maintenance System
step response test (Item 1.19) on the direct
writer.
trol the light or use a filter over the display
faceplate.)
“Burn spots” should not be visible on the cathode ray tube. (If the intensity is set too high,
the phosphor may “burn”; the cathode-ray
tube face will be discolored if this condition
exists.)
2. Quantitative tests
2.1
Grounding Resistance. Using an ohmmeter,
electrical safety analyzer, or multimeter with
good resolution of fractional ohms, measure and
record the resistance between the grounding pin
of the power cord and exposed (unpainted and
not anodized) metal on the defibrillator chassis
(and charger chassis if appropriate). We recommend a maximum of 0.5 Ω. If the system is
modular, verify grounding of the mainframe and
each module.
2.2
Chassis Leakage Current. Measure chassis
leakage current to ground with the grounding
conductor of plug-connected equipment temporarily opened. Operate the device in all normal
modes, including on, standby, and off, and record
the maximum leakage current. Chassis leakage
current to ground should not exceed 300 µA.
60 Hz or other noise (interference) should not
be superimposed on the baseline with the
ECG simulator attached. Baseline interference may be apparent as a thick baseline at
high gain settings but should not be visible
throughout the lower two-thirds of the gain
control range.
1.19 1 mV Step Response. Depress and hold the 1 mV
calibration button for about 3 sec (or apply an
external 1 mV pulse if the unit does not have a
calibration pulse). The trace should exhibit a
sharp square-cornered leading edge that is neither rounded nor spiked (any spike should be less
than 10%). After 1 sec, the pulse should have
decayed no more than half its original amplitude
(see Figure 1). With the gain set to yield about
20 mm deflection for a 1 mV input (×2 or 1/2
mV/div), compare the amplitude of the internal
calibration pulse and an external 1 mV signal
(from a calibrated ECG simulator). At a 20 mm
deflection, they should be within 2 mm (±10%) of
each other.
1.20 Alarms. Operate the device in such a way as to
activate each audible and visual alarm. Check
for adequate alarm tone volume and any associated features, such as automatic direct
writer activation or display freeze function. If
the device has an alarm-silence feature, check
that the unit resets automatically or that the
manual reset functions. Check bed-to-bed and
bed-to-central station alarm networking
(where appropriate).
If a bedside or central station monitor is
grounded through system interconnections in
addition to power-line grounding (and is used
only in this configuration), do not disconnect the
monitor from the system to measure chassis
leakage current during routine inspections.
Verifying low grounding resistance is adequate.
2.10 Rate Calibration. Using simulated ECG rates of
60 and 120 pulses per minute, verify that the
heart rate indicator displays a rate within 5% or
5 bpm, whichever is greater, of the set rate (55
to 65 bpm, 119 to 126 bpm). Verify that the QRS
visual and audible indicators are functioning.
1.21 Audible Signals. Operate the device to activate
any audible signals. Confirm appropriate volume, as well as the operation of a volume control.
1.22 Labeling. Check that all necessary placards, labels, and instruction cards are present and legible.
1.24 Direct Writer. If the unit has a direct writer,
confirm that it operates smoothly, that the paper
feeds evenly and does not stray from side to side,
and that the trace is of good quality (i.e., dark
and thin) at all paper speeds. Perform the 1 mV
4
Figure 1. The calibration pulse or step response leading
edge should have square corners (left). Slight rounding
(middle) or small overshoot is acceptable. Excessive
rounding or overshoot (right) indicates the need for
adjustment.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
ECG Monitors
2.11 Rate Alarm. Use the same setup as for the previous test. For typical low- and high-rate alarm
settings of 40 and 120 bpm, respectively, verify
that the alarm activates when the input rate is
set just below or above the respective rate alarm
settings. The difference between the rate displayed on the rate indicator and that at which
the alarm is activated should not exceed 5% or 5
bpm, whichever is greater.
Common mode rejection is needed in monitors
because of the presence of stray signals common
to all input leads primarily at power-line frequency (60 Hz). While these signals are too minute to be hazardous, they can interfere with
the ECG display of a monitor with a low CMRR
at 60 Hz.
The CMRR is defined as:
CMRR =
3. Preventive maintenance
3.1
Clean the exterior, rollers, and platen, if needed.
3.2
Lubricate the chart recorder paper drive per the
manufacturer’s recommendations, if required.
3.4
Replace filters and batteries, if required. Some
units have air filters that accompany the cooling
fan. These filters should be checked and replaced
if needed.
If any of the test procedures indicate a weak
or defective battery, even after charging for 12
hr or more, replace the battery. Some users have
also reported that periodic, prophylactic battery
replacement, either annually or every other
year, increases reliability and decreases service
calls. If the battery is replaced, mark the date of
the replacement on the battery or unit. Perform
the inspection after battery replacement and a
suitable charge period.
4. Acceptance tests
Conduct major inspection tests for this procedure
and the appropriate tests in the General Devices Procedure/Checklist 438. Most ECG monitors should meet
the requirements for isolated input devices for ECG
lead-to-ground, interlead, and input isolation tests.
Differential mode deflection factor or DMD (MM / mV)
Common mode deflection factor or CMD (MM / mV)
A deflection factor is the change in trace position corresponding to a given input voltage to the
monitor. Use an unbalanced CMRR measurement that includes a 5,000 Ω resistor in series
with one of the input leads to the monitor, to
simulate unequal impedances in the electrode/skin interface of the monitor electrodes, as
commonly occurs in practice.
Since most common mode voltage in the hospital is at 60 Hz, it is most significant to measure
the CMRR at or near that frequency. Using the
test setup shown in Figure 2, apply a sinusoid
test signal of 1 mV peak-to-peak at about 60 Hz
to the monitor. A frequency of 55 Hz is often
used to minimize interference from line frequency noise. Turn the monitor gain so that the
deflection is at least 20 mm. Measure the deflection (mm), and record it on the inspection form
as the differential mode deflection factor. Since
the input signal for this measurement is 1 mV,
the differential mode deflection factor expressed
in mm/mV is numerically equal to the resultant
deflection in mm. Do not vary the gain of the
monitor or the signal frequency for the remainder of this test. Record the frequency on the
inspection form.
In addition, perform the following tests.
4.1
Common Mode Rejection Ratio (CMRR). The
ECG monitor includes a differential amplifier so
that it can display the voltage difference between
two electrodes (the RA and LA in lead 1) while
using a third electrode (RL) as a reference. If the
same, or common, voltage is applied to RA and
LA simultaneously, there should be no output
from the differential amplifier because the voltage difference between the two inputs is zero.
The extent to which a differential amplifier produces no output when the same signal is applied
to both inputs is called its common mode rejection ratio.
Figure 2. Signal input test setup.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
5
Inspection and Preventive Maintenance System
Connect an ECG simulator with variable output
to the monitor and set it for a rate of 60 bpm.
Vary the output amplitude over a range of 0.5 to
5 mV (use the monitor display to estimate amplitude if the simulator does not have a calibrated
output). The monitor should reliably detect all
beats and should not double-count. It should not
detect QRS amplitudes of less than 0.15 mV. If
the unit has a manual sensitivity control, check
that it is functioning properly as evidenced by
the need to change the setting during this test.
Use the test setup shown in Figure 3 for the
second part of this measurement. Note that
there is only one connection from the output of
the attenuator to the patient leads. The other
output terminal is grounded. It is essential that
all instruments used in this test be connected to
4.4
Paper Speed. Use an ECG simulator set to 60
bpm or a signal or pulse generator that has been
set to 1 Hz with a calibrated counter. If the
interval between pulses is not within 10 msec of
1,000 msec, an appropriate correction should be
made in calculating paper speed. Paper speed
should be accurate to within 2%. At a chart speed
of 25 mm/sec and a pulse interval of 1,000 msec
(60 bpm on an ECG simulator), the distance
between the first and last of five successive peaks
should be 100 ±2 mm; at a chart speed of 50
mm/sec, the distance between the first and the
last of five successive peaks should be 200 ±4 mm.
4.5
Alarm Delay. In addition to checking rate
alarm accuracy (Item 2.11), use the same test
setup to determine alarm delay. First, set the
high-rate alarm to 100 bpm and the ECG simulator to 60 bpm. Quickly change the simulator
rate to 120 bpm and use a stopwatch or a watch
with a second hand to measure the time until the
alarm sounds. Check the low-rate alarm similarly (set alarm for 40 bpm, change rate from 60
to 30 bpm). Generally, alarm delays should not
exceed 10 sec.
4.6
Battery Operating Time. If the unit can operate
on battery power, verify that it meets hospital or
manufacturer specifications for operating time.
Units should meet requirements with all functions operating (including alarms sounding) unless otherwise specified by the manufacturer.
Figure 3. Common mode rejection ratio test setup.
a common ground to minimize noise.
Increase the amplitude of the sinusoid signal
(10 V peak-to-peak) until some measurable deflection is observed on the monitor. Calculate the
common mode deflection factor by dividing the
resultant deflection (in mm) by the input signal
(in mV). The CMRR can then be calculated as the
differential mode deflection factor divided by the
common mode deflection factor.
If the unit has an ungrounded or plastic case,
measure the CMRR with the unit resting on a
grounded metal plate. CMRR should meet the
manufacturer’s specification and be at least
10,000:1.
4.2
4.3
6
Gain. Apply a 2 mV signal at a gain setting of
10 mV/mm (or ×1) and measure the displayed
amplitude with a transparent scale. Verify that
the displayed signal size changes appropriately
(within 10%) as the gain setting is changed. For
example, if a 2 mV signal produces a 20 mm
deflection (at a ×1 gain), the deflection should be
36 to 44 mm at ×2. Test both the monitor display
and recorder.
QRS Sensitivity. If the monitor has a QRS indicator or beeper or a heart rate meter, verify that
the QRS detector circuit is functioning properly.
Before returning to use
Return controls and alarm limits to their original
positions, and make sure that the unit is not left in a
service mode. Check the battery condition meter indicator on battery-powered units to verify that there is
adequate charge.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Procedure/Form 437-0595
Electrical Receptacles
Used For:
Receptacles, Hospital Grade [15-859]
Also Called: Electrical outlets
Scope: Applies to three-wire parallel-blade grounding-type electrical receptacles used in grounded electrical
distribution systems throughout the hospital; does not apply to explosion-proof or other special types of
receptacles (for information on testing of isolated power systems, see Procedure/Form 439)
Risk Level: ECRI Recommended, Low; Hospital Assessment,
ECRI-Recommended Interval: See Overview below for NFPA requirements and ECRI recommendations
Overview
A defective or deteriorating electrical system exposes
patients and staff to the risk of electrical shock and
potential interruption of power required to operate
medical equipment. A periodic inspection program
designed to detect and correct deficiencies at each
receptacle is required to reduce these risks.
NFPA 99, 1993 Edition, specifies that receptacles in
general care areas be tested every 12 months and that
those in critical care areas and designated wet locations
be tested every 6 months. (See the Patient Care Areas
box for explanations of the italicized terms used in the
NFPA standard.) NFPA permits extending the intervals if documented performance data justify longer
intervals. Initially, inspections should be conducted at
the specified 12- and 6-month intervals. The data obtained during these initial inspections should then be
examined and used to determine appropriate intervals.
Although there is no formal guideline on an acceptable
number of defects, ECRI believes that the testing interval can be extended if fewer than 2% of the receptacles
in an area require replacement or other corrective action.
A recent study by ECRI of more than 800,000 receptacles
inspected between 1987 and 1994 indicates that more
than 13% failed to meet one or more of the criteria in this
procedure. However, little is known about the history of
these receptacles. Annual testing should be adequate in
areas where receptacles receive frequent use; other areas
may require even less frequent testing. (Note that NFPA
094735
437-0595
A NONPROFIT AGENCY
99 requires semiannual testing in wet areas in existing
facilities that are not supplied with special protective
systems, such as ground fault circuit interrupters
[GFCIs] or isolated power.)
NFPA 99, Section 3.5.2.1, specifies that voltage and
impedance tests be performed to measure the effectiveness or quality of the grounding system. This section
specifies that these tests be performed before acceptance
on all new construction and when the electrical system
has been altered or replaced. Sections 3.5.2.2 and
3.6.2.3.1 require that the physical integrity, polarity,
retention force of the grounding blade, and continuity of
the grounding circuit of each receptacle be verified every
12 months in general care and wet locations and every 6
months in critical care areas. The ECRI procedures
given in the sections on Ground Potentials and Grounding Resistance below cover both of these requirements.
A power plug and receptacle combination should:
Provide a safe, reliable means of connecting and
disconnecting an electrically powered device
Permit only devices intended for use with that supply to be connected
Allow only one orientation of plug contacts in the
receptacle
Have low electrical contact resistance between the
plug and the receptacle
Withstand normal use and reasonable mechanical
abuse
5200 Butler Pike, Plymouth Meeting, PA 19462-1298, USA
Telephone +1 (610) 825-6000 ● Fax +1 (610) 834-1275
●
E-mail [email protected]
Inspection and Preventive Maintenance System
Patient Care Areas
In specifying testing requirements for electrical
receptacles, NFPA refers to general care areas,
critical care areas, and wet locations; these terms
are explained below.
General care areas are patient bedrooms, examining rooms, treatment rooms, clinics, and
similar areas in which it is intended that the
patient shall come into contact with ordinary
appliances, such as a nurse call system, electric
beds, examining lamps, a telephone, and entertainment devices. In such areas, it may also be
intended that patients be connected to electromedical devices (e.g., heating pads, electrocardiographs, drainage pumps, monitors, otoscopes,
ophthalmoscopes, peripheral intravenous lines).
Critical care areas are those special care units,
intensive care units, coronary care units, angiography laboratories, cardiac catheterization laboratories, delivery rooms, operating rooms, and
similar areas in which patients are intended to be
subjected to invasive procedures and connected to
line-operated electromedical devices.
Wet locations are patient care areas that are
normally subject to wet conditions while patients
are present; this includes standing fluids on the
floor or drenching of the work area, either of
which condition is intimate to the patient or staff.
Routine housekeeping procedures and incidental
spillage of liquids do not define a wet location.
(Note: Areas that may typically be designated as
wet locations include hydrotherapy areas, dialysis units, and certain wet laboratories. Operating
rooms, even though there may be significant
amounts of spilled fluids, are generally not considered wet areas.)
Ensure that the grounding pin on the plug cap is the
first to engage and the last to disengage in the
receptacle at all angles of entry and withdrawal
Provide strain relief for the power cord where it
enters the plug cap
Several plug and receptacle configurations are
available for specific applications. The two-pole,
three-wire, parallel-blade grounding-type receptacle
is most familiar because of its widespread use. This
configuration can be made to satisfy the requirements for a reliable plug-receptacle combination.
Other receptacle configurations, which generally
2
have higher current or voltage ratings, are used in
hospitals for housekeeping equipment, food carts, and
mobile x-ray units. Explosion-proof plugs and receptacles are required in operating rooms where flammable
anesthetics are used and in other areas where arcing
when inserting or removing a plug could ignite flammable gases.
Only two conductors are required to operate a 120 V
device, and two-wire parallel-blade plugs and receptacles
have been in common use for many years. One of these
conductors is connected to earth ground near the point
where the power enters the building. This conductor,
colored white, is commonly called the neutral wire but is
frequently referred to in codes as the grounded conductor. The other conductor, carrying power to the receptacles, is called the hot conductor and is usually colored
black. Its voltage is approximately 120 V with respect to
the neutral conductor or ground reference.
The third conductor in a three-wire power cord for
conventional equipment does not carry normal load
current. At the equipment end of the cord, it connects
to the chassis and exposed metal. When the plug is
inserted into a properly installed three-slot grounding
receptacle, the third wire is connected to ground. This
grounding wire (not to be confused with grounded
connector), usually green, is intended to carry normally small leakage currents, as well as large fault
currents resulting from shorts, from the hot conductor
to the chassis. By connecting the equipment chassis to
ground, this third wire protects people touching the
chassis against electric shocks. Because load current
does not normally flow through it, the green wire will
be closer to ground potential than the neutral wire.
The grounding slot of the receptacle is attached to the
yoke with which the receptacle mounts in its box, and the
box is grounded through the metal conduit through
which the wires run. The receptacle ground terminal can
also be grounded by a separate grounding conductor
connected to the grounding point in the electrical distribution system panel board. The separate wire, or pulled
ground, is a more reliable means of grounding, because
the conduit is made of a material that can corrode and
has mechanical joints that can loosen. Current electrical
codes for new construction require that the ground terminals of all receptacles in patient care areas be connected to ground by a separate insulated copper
conductor. An exception to the code allows existing construction that does not use a separate grounding conductor to continue in use provided it meets the specified
grounding performance requirements.
The common three-slot, parallel-blade, groundingtype receptacle is intended for branch circuits rated at
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Electrical Receptacles
15 A, which is adequate for most 120 V devices. Receptacles and plugs of a slightly different configuration
are available for branch circuits and equipment that
require between 15 and 20 A. The 20 A receptacle is
designed to accept both the 20 A and 15 A plugs, but
the 20 A plug cannot be used in a 15 A receptacle.
The conventional three-prong plug and three-slot
receptacle are polarized so that they will mate in only
one direction. Assuming that the receptacle and
equipment are wired correctly, the polarization ensures that the hot, neutral, and ground wires in the
power cord connect to their counterparts in the receptacle. The conventional two-slot receptacle provides
for polarization by the difference in the size of the
receptacle slots (the hot wire slot is smaller than the
neutral slot). Thus, equipment requiring polarization
is equipped with plugs that have blades of different
sizes.
Citations from Health Devices
Ground fault circuit interrupters [Evaluation], 1973
Mar; 2:112-5.
Hospital Grade duplex receptacles [Evaluation], 1978
Nov; 8:3-18.
OR renovations and the use of isolated power and
explosion-proof plugs [User Experience NetworkTM],
1992 Sep; 21:334.
Electrical outlets in anesthesizing locations, 1993 AugSep; 22:420.
Test apparatus and supplies
Three-lamp receptacle wiring polarity tester
AC voltmeter, range 100 to 140 V
Low-resistance ohmmeter, resolution to 0.01 Ω in
the 0 to 0.2 Ω range
Leakage current meter or voltmeter capable of
measuring 20 to 500 MV
Receptacle tension tester
Leads and adapters to connect receptacle and other
ground points
GFCI tester (electrical safety analyzer or isolated
power tester)
Defective receptacle tags
Test equipment that combines the function of the
above test devices or that automates the testing described in this procedure is available and may be
substituted.
Special precautions
Testing in occupied areas must not pose a hazard to
patients. Devices used to determine ground quality or
grounding impedance apply power to the grounding
circuit. To minimize risks to the patient and equipment in the testing area and potentially in other areas
served by the same circuit, the output of the testing
devices should be limited to 500 mV RMS (1.4 V peak
to peak) or 1.4 VDC even under open-circuit conditions.
Receptacles should be tested with all equipment
unplugged. Consult clinical personnel before disconnecting patients from devices or unplugging equipment and before turning off a branch circuit breaker
to correct defective receptacles. Do not attempt to
unplug life support and critical monitoring devices
that are in use; return when the bed is unoccupied or
occupied by a patient better able to withstand the
transfer of devices to alternate power sources.
Procedure
Before beginning the receptacle inspections, determine the extent to which inspecting personnel should
correct deficiencies on the spot. Certainly, such minor
defects as a loose screw on the cover plate should be
corrected. Inspecting personnel might also carry a supply of new receptacles and cover plates and replace and
retest defective receptacles as identified. Alternatively,
inspectors can identify defective receptacles with “Defective — Do Not Use” tags; qualified personnel can follow
up by correcting defective receptacles and retesting.
Because the Universal Inspection Form does not
apply, use the special Electrical Receptacles Form 437
included with this procedure.
Identify the area to be tested; this may be a room,
special care area, corridor, or an area with many receptacles (e.g., coronary care unit, isolated power system). If
failures occur, note these on the form and identify the
location of the receptacle. Using a standard method for
numbering the receptacles in an area will prove helpful.
One way is to enter the area and start to the left of the
door, proceeding clockwise around the area. If a defective
receptacle is not repaired or replaced at the time of
inspection, put a “Defective — Do Not Use” tag on it.
Exception reporting can save time when using the
form. If no defects are encountered in an area or room,
indicate the area, room, and outlet on the form, write OK
in the “Status” box and check off the “Exception Reporting Used” box. You need only record measurements that
fall outside the criteria for any test in the appropriate box
on the form. If you are planning to adjust the inspection
intervals, record the total number of outlets inspected
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3
Inspection and Preventive Maintenance System
(use the margin) so that the percentage of defective
receptacles can be determined.
Inspect every receptacle in the area with all equipment unplugged from the receptacle under test. Caution: Consult clinical personnel before unplugging any
equipment.
If deficiencies are found, identify the defective outlet
on the form and indicate the need for corrective action
in the “Comments” column. If the space provided on
the form is inadequate, write “See note” in the block
and use the back of the form. Be sure to include the
receptacle number on all such notes. If more than one
form is needed for an area, number each sheet, and
attach them together.
To save time, you may want to perform all of the
tests, except Ground Potentials and Grounding Resistance, on each individual receptacle in a room or area,
then proceed with the remaining tests on all receptacles.
Mechanical condition
Visually inspect the receptacle and cover plate for
physical damage and security of physical mounting of the
receptacle and outlet box. Replace the receptacle if its
face is badly chipped or broken. Replace the cover plate
if it is cracked. Correct any defects in physical mounting.
If any sensation of heat is noted when touching the
surface of the receptacle or when unplugging connected equipment, investigate further. Heating within
the receptacle can be caused by several deficiencies,
including high resistance at the receptacle contact due
to wear, damage, or loose wiring, especially if improper
techniques have been used with aluminum wiring.
Rarely will a receptacle develop internal leakage. Before condemning the receptacle, rule out any defect in
the equipment that causes it to draw excessive current
or poor connections in the plug cap.
Wiring polarity
Check each receptacle for wiring errors with a threelamp polarity tester. This tester will indicate loss from
hot, neutral, or ground wires and whether hot and
neutral or hot and ground wires have been interchanged. It does not detect neutral/ground reversal
and does not verify that grounding is adequate to carry
fault currents. Correct any wiring errors. Look for
flickering of the tester’s lights as it is inserted, jiggled
moderately in place, and withdrawn. Such flickering
may indicate poor contacts and should be investigated.
4
Line voltage
The following line voltage tests are not required by
NFPA 99. We have included them as optional tests.
These tests should be performed following new construction, renovations, or major repairs to the electrical distribution system to ensure that voltage taps are
set correctly on distribution transformers. Repeating
the tests after typical loads are applied or in existing
facilities may indicate poor wiring or inadequate system capacity. The tests may also be helpful in diagnosing suspected problems and indicating whether a
more extensive investigation of the electrical distribution system is necessary.
Use an AC voltmeter to measure the hot-to-neutral
voltages at representative receptacles in an area or in
the branch circuit panel board. The hot-to-neutral
voltage should normally be within the 115 to 125 V
range. It should not fall below 100 V with heavy loads
on the circuit or rise above 130 V during no-load
conditions. A significant difference in line voltages to
receptacles taken under typical load conditions indicates overloaded circuits or faulty wiring and requires
further investigation. An optional means of testing for
adequate wiring is to measure the line voltage with
and without a load connected to the other half of the
duplex receptacle being tested.
Measure the AC voltage between the neutral and
ground connections. A reading of above 4 V indicates
possible miswiring of the neutral and/or ground systems or excessive resistance in the wiring.
Ground potentials
The purpose of this test is to determine whether
voltage differences exist between points that should be
at ground potential. These voltage differences could
be caused by high ground-to-ground resistances and/or
heavy currents flowing through the ground system.
For new construction, NFPA 99 requires that the
voltage limit between a reference point and grounding
contact of each receptacle in the patient vicinity not
exceed 20 mV. In existing construction, the voltage
should not exceed 500 mV in general care areas and 40
mV in critical care areas. However, voltages in modern
construction are usually less than 10 mV; voltages
exceeding 20 mV may indicate a deteriorating condition and should be investigated. It should be understood that these limits are not precise, and differences
of less than 20% should be considered insignificant.
Measure ground potentials with a voltmeter or leakage current meter. Leakage current readings can be
converted to millivolts if the leakage current meter’s
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©1995 ECRI. All Rights Reserved.
Electrical Receptacles
impedance is known. (Most leakage current meters
have a 1,000 Ω impedance at line frequency; the reading in µA is then numerically equivalent to the voltage
in mV.) Connect one lead of the meter to a reference
ground point that is known to be securely grounded. It
is usually most convenient to use the ground contact
of one receptacle, but a ground plug or structural
member can also be used. Do not use the cover plate
screw because this may not be adequately grounded.
Connect the other lead to the ground contact of each
receptacle in turn. To save time, measure ground
potentials on an entire room or area at one time, rather
than while performing other tests on each receptacle.
Ground potentials will not be constant with time but
will depend on what equipment is connected and operating at the time of measurement. A high ground
potential measurement at a receptacle grounding contact may indicate that the ground and the neutral
conductor in the receptacle wiring are reversed. The
three-lamp testers will not detect such reversal (which,
in fact, will often be undetected during ground potential measurements, since the outlet ground contact will
usually be grounded through the conduit).
Neutral-to-ground resistance
The safety provided by a good ground system can be
compromised if the neutral wires of the receptacles are
not properly connected to the grounding system at an
appropriate location. For example, if a device plugged
into a receptacle with high neutral-to-ground resistance develops a hot-wire-to-chassis short circuit, then
120 V would exist as a shock hazard to anyone touching
that chassis. If the neutral-to-ground resistance were
low, then the heavy currents flowing from the
grounded chassis back to the neutral wire would trip
the receptacle’s circuit breaker. ECRI suggests a minimum of 1.0 Ω between the neutral and ground contact
of each receptacle.
Grounding resistance
The three-lamp testers used to check receptacle
wiring as part of the basic inspection will indicate the
complete lack of ground. However, a ground whose
resistance is as high as several thousand ohms may be
considered acceptable by these testers. The purpose of
the grounding resistance test is to determine whether
the grounding circuit resistance is low enough to serve
its intended function.
Originally, the ground contact in a receptacle was
designed to prevent the chassis of connected equipment from becoming energized in the event of a lineto-chassis fault. In this application, the ground must
carry sufficient current to quickly blow the branch fuse
or circuit breaker. More recently, the grounding system has been called upon to drain leakage current and
fault currents not large enough to blow a fuse or
breaker and to protect hospital patients against microshock under these conditions. In this application,
the grounding system resistance must be low enough
to prevent dangerous voltages when anticipated leakage or fault currents flow through it.
To avoid risk to patients in the area in which testing
is being conducted and in areas distant from the testing site, any device used to determine ground quality
or grounding resistance on occupied patient care areas
must limit the output to 500 mV RMS (1.4 V peak to
peak) or 1.4 VDC. Several test devices are available
using different measurement methodologies. Any of
these special-purpose devices or an ohmmeter with
resolution to 0.01 Ω may be used. For periodic measurement in existing construction, the measurement
current can be either AC or DC.
Select a ground reference point (such as that used
for the ground potential test), and measure the resistance between each receptacle ground contact and the
reference. The resistance should not exceed 0.2 Ω and,
in new construction, should not exceed 0.1 Ω.
Action required as a result of ground potential and
grounding resistance failures may not be restricted to
replacement of a receptacle but may involve the entire
area’s wiring and grounding. The need for corrective
action should be discussed with the plant engineer or
other responsible person.
When performing ground potential and resistance
tests on new construction and renovations, note the
appropriate criteria for new construction included in
those test methods. NFPA 99 requires the use of an
AC measuring source for postconstruction impedance
measurement (but allows the use of AC or DC devices
on existing construction).
Contact tension
Contact tension — the force with which the spring
contacts of the receptacle grip the blades of the plug —
affects the performance of the plug/receptacle combination both electrically and mechanically. If contact
tension is insufficient, reliable, low-resistance electrical connections cannot be assured. High resistance in
the hot and neutral connections can cause internal
heating of the receptacle. Plugs with bent blades may
not make electrical contact at all. This will be easily
recognized with the hot and neutral blades, since the
equipment will not function. However, loss of contact
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5
Inspection and Preventive Maintenance System
on the ground will not be obvious and will compromise
the safety of the equipment.
In addition, the contact tension must be sufficient
to prevent the plug from inadvertently coming out of
the receptacle. On the other hand, contact tension
should not be so great that the plug cannot be easily
inserted or withdrawn. Also, in the event that someone trips over a line cord, the plug should withdraw
from the outlet, rather than the equipment being
pulled down or the line cord severing.
It has been shown that good electrical contact requires a lower gripping force than is needed to grasp
the plug firmly. Thus, a mechanical test of tension is
sufficient.
Measure contact tension on each receptacle while
withdrawing the tester straight and smoothly from the
outlet. Retention force on the ground prong must be 4
oz or more. We recommend measuring the retention
force on the hot and neutral prongs, although this is
not required. A retention force of 4 oz is also adequate
for the hot and neutral prongs, and forces of 2 to 4 oz
are satisfactory if the plug brand in use tends to
stabilize at this value and does not continue to deteriorate. (See the Contact Tension Testers box.)
Contact tension testers are available in many
configurations and brands. Inaccurate probe
sizes and surface finishes, measurement inaccuracies, and poor repeatability can cause erroneous results. Also, many testers are not rugged
enough to survive transport in a tool box.
We offer the following suggestions for purchase and use of these devices:
Check for an appropriate test range of up to at
least 8 oz. Make sure that the tester has a
specified accuracy or is accurate to within 10%.
Ask the manufacturer about probe sizes and
finishes. They should be made of tool steel or a
metal of equivalent hardness. Though directed
at manufacturers, UL and ANSI values may
serve as guidelines for hospitals:
— Ground probe — cylindrical, 0.4674 to
0.4826 cm (0.184 to 0.190 in) diameter, 8 µ
in finish (UL).
— Power probe — 0.1397 to 0.1651 cm (0.055
to 0.065 in) thick (ANSI).
GFCIs
A GFCI is a device designed to interrupt the electrical circuit to the load when a fault current to ground
exceeds some predetermined value that is less than
that required to operate the overcurrent protective
device (fuse or circuit breaker) of the supply circuit.
The device is usually installed as part of the electrical
wiring supplying power to a receptacle. In many cases,
it is an integral component of the power receptacle.
The GFCI continuously senses the difference in
current flow between the hot and neutral wire of the
receptacle circuit. Normally, this difference is quite
small. However, under fault conditions, current returns to the source by a path other than the neutral
wire, thus causing the difference to increase. When
the GFCI senses that this difference is greater than
some critical value (usually 6 mA), it interrupts the
circuit to the receptacle.
GFCIs are used for added protection against
macroshock hazards in areas where the risk of these
hazards is increased due to environmental conditions,
such as the presence of water. The use of GFCIs is an
acceptable method of reducing macroshock hazards in
areas designated as wet locations. NFPA 99 specifies
that GFCIs used in wet locations be tested at least
every 12 months. The GFCI test procedure is included
6
Contact Tension Testers
Before each receptacle inspection, calibrate
the tester to ensure accuracy. Suspend a
known weight from the tester, check its scale
reading, and adjust if necessary.
When using the tester, be sure the probes are
clean and dry. Inadvertent lubrication can significantly affect readings. Carry alcohol wipes
and clean the probes periodically.
as an additional test that applies only to receptacles
protected by a GFCI.
NFPA specifies that a device or component that
causes 6 mA of current to flow to ground shall be
momentarily connected between the energized conductor of the power distribution circuit being protected
and ground to verify that the GFCI does indeed interrupt the power. Many GFCIs have a built-in test circuit
and reset button. We believe this is an adequate test
for routine testing. If such a circuit is not built into the
receptacle or for a more accurate validation, many
electrical safety analyzers and isolated power test devices have a built-in test for GFCIs, and simple GFCI
test devices are available commercially.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Procedure/Checklist 410-0595
Electrocardiographs
Used For:
Electrocardiographs, Interpretive [16-231]
Electrocardiographs, Multichannel [11-411]
Electrocardiographs, Single-Channel [11-413]
Also Called: EKG units, ECG units, EKG machines
Commonly Used In: Electrocardiography departments, emergency departments, and most patient care
areas
Scope: Applies to single-channel and multichannel electrocardiographs typically used for recording an
electrocardiogram on paper; may also be adapted for some systems that digitally store data and later provide
hard-copy tracings; not suitable for verifying performance of automated diagnostic functions; does not apply
to strip-chart recorders or direct writers, which should be inspected with the ECG monitor or the
defibrillator/monitor they are used in conjunction with (use ECG Monitors Procedure/Checklist 409 and
Defibrillator/Monitors Procedure/Checklist 408, respectively)
Risk Level: ECRI Recommended, Medium; Hospital Assessment,
Type
ECRI-Recommended
Interval
Major
12 months
months
.
hours
Minor
NA
months
.
hours
Overview
An electrocardiograph detects the electrical activity of
the heart and produces a graphic record, an electrocardiogram (ECG), of voltage versus time. Each portion of
the ECG is directly related to an electrical cardiac
event, and variations or abnormalities seen in the ECG
can often be traced to a particular site in the heart.
Each ECG trace, which is derived from the electrical
activity detected by two or more electrodes placed at
certain points on the patient’s skin surface, is called a
lead. A full-lead ECG records 12 leads derived from 10
electrode locations.
By using a high-fidelity recording of multiple leads,
it is possible to accurately examine and quantify
rhythm and waveform morphology. Voltage levels and
timing between events are measured with calipers or
automatically by the electrocardiograph. Comparing
009028
410-0595
A NONPROFIT AGENCY
Interval Used
By Hospital
Time Required
the various lead signals provides a more specific and
accurate diagnosis than would be possible with a single-lead recording.
Several standards and guidelines include performance criteria to ensure that recording errors do not
interfere with accurate interpretation of the ECG.
While verification that an electrocardiograph meets
these criteria is an important part of a prepurchase
evaluation program and should be included as part of
acceptance testing, experience indicates that most of
these characteristics do not change on modern electrocardiographs unless there is a major (and usually
obvious) equipment failure. Therefore, the inspection
procedure has been designed to reduce the amount of
testing required.
Portable and mobile electrocardiographs deserve
special attention; rough handling may change circuit
5200 Butler Pike, Plymouth Meeting, PA 19462-1298, USA
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Inspection and Preventive Maintenance System
characteristics and adversely affect recording or
safety. Mishandling frequently damages the delicate
writing stylus, galvanometer, chart drive or paper
feed, and power cords and plugs.
Citations from Health Devices
Single-channel electrocardiographs [Evaluation],
1973-74 Dec-Jan; 3:31-56.
Three-channel electrocardiographs [Evaluation], 1984
Aug; 13:235.
Defibrillating patients connected to electrocardiographs, 1984 Aug; 13:254.
Signal-averaging ECGs: An update, 1990 Sep; 19:328-30.
12-lead multichannel interpretive electrocardiographs
[Evaluation], 1991 Oct; 20:367-408.
Test apparatus and supplies
Some older electrocardiographs may fail to meet
current criteria for performance and safety. While
units that show deteriorating performance or safety
should be repaired or replaced, those that meet their
original design specifications may still be suitable for
use. When evaluating these units, take into account
clinical needs, realistic levels of safety, and funding
priorities. Because this Procedure/Checklist covers
electrocardiographs used in their conventional application and not as components of larger systems, auxiliary inputs or outputs of the writer are not tested here.
If these are used, test them for performance characteristics that pertain to the specific application. Encourage ECG technicians to check their instruments
at the start of each shift and to ensure that the units
are clean when returned.
1. Qualitative tests
1.1
Chassis/Housing. Examine the exterior of the
unit for cleanliness and general physical condition. Be sure that plastic housings are intact,
that necessary assembly hardware is present
and tight, and that there are no signs of spilled
liquids or other serious abuse.
1.2
Mount. If the device is mounted on a stand or
cart, examine the condition of the mount. If it is
attached to a wall or rests on a shelf, check the
security of this attachment.
1.3
Casters/Brakes. If the device moves on casters,
check their condition. Look for accumulations of
lint and thread around the casters, and be sure
that they turn and swivel, as appropriate. Check
the operation of brakes and swivel locks, if the
unit is so equipped.
1.4
AC Plug. Examine the AC power plug for damage. Attempt to wiggle the blades to determine
that they are secure. Shake the plug and listen
for rattles that could indicate loose screws. If
any damage is suspected, open the plug and
inspect it.
1.5
Line Cord. Inspect the cord for signs of damage.
If damaged, replace the entire cord or, if the
damage is near one end, cut out the defective
portion. Be sure to wire a new power cord or plug
with the same polarity as the old one. Also check
line cords of battery chargers, if applicable.
1.6
Strain Reliefs. Examine the strain reliefs at
both ends of the line cord. Be sure that they hold
the cord securely.
ECG simulator with calibrated output amplitudes
and rates
Ground resistance ohmmeter
Leakage current meter or electrical safety analyzer
Contact cleaner and lubricant
Counter (optional)
The following equipment is necessary during acceptance testing only:
Function generator
Attenuator
Oscilloscope
Transparent metric scale
Isolation test supply (included in some electrical
safety analyzers)
Special precautions
Testing input isolation requires the use of a linevoltage source. Although this source should include a
current-limiting resistor, use caution to avoid contact
with any portions of the energized circuit.
Procedure
Before beginning an inspection, carefully read this
procedure and the manufacturer’s instruction and service manuals; be sure that you understand how to operate the equipment and the significance of each control
and indicator. Also determine whether any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer.
2
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Electrocardiographs
1.7
1.9
Circuit Breaker/Fuse. If the device has a
switch-type circuit breaker, check that it moves
freely. If the device is protected by an external
fuse, check its value and type against that
marked on the chassis, and ensure that a spare
is provided.
Cables. Inspect the cables and leads for their
strain reliefs and general condition. Examine
cables carefully to detect breaks in the insulation
and to ensure that they are gripped securely in
the connectors of each end to prevent rotation or
other strain.
Connect the unit to an ECG simulator, and
verify that an adequate trace is received at each
patient lead selection. (Checking all leads in
some units will require either a 12-lead simulator or connection and disconnection of every
lead.) Flex the patient cable near each end to
verify that there are no intermittent faults.
battery-operated power-loss alarms, if so
equipped.
Perform the inspection with the unit on battery power or operate the unit on battery power
for several minutes to check that the battery is
charged and can hold a charge. Check battery
capacity by activating the battery test function
or measuring the battery-powered operating
time. When it is necessary to replace a battery,
label it with the date.
Check the condition of the battery charger,
and to the extent possible, confirm that it does,
in fact, charge the battery.
Some batteries require periodic deep discharges and recharging to maintain maximum
battery capacity. If this is recommended by the
manufacturer, verify that it is being performed
on schedule.
1.10 Fittings/Connectors. Examine all cable connectors for general condition. Electrical contact
pins or surfaces should be straight and clean.
Leads and electrodes should be firmly gripped in
their appropriate connectors.
1.18 Indicators/Displays. During the course of the
inspection, confirm the operation of all lights,
indicators, and visual displays on the unit and
charger, if so equipped. Be sure that all segments of a digital display function.
1.11 Electrodes. Confirm that an adequate supply of
ECG electrodes is available, and check their
physical condition and that they are within their
expiration dates.
1.19 1 mV Step Response. Depress and hold the 1 mV
calibration button (or apply an external 1 mV
pulse) for about 3 sec. The trace should exhibit a
sharp, square-cornered leading edge that is neither rounded nor spiked. (Up to 10% spike or
overshoot is acceptable but will usually not be
observed in a unit that is functioning optimally;
see Figure 1.) After 2 sec (50 mm of paper at a
speed of 25 mm/sec), the pulse should have de-
1.13 Controls/Switches. Before moving any controls,
check their positions. If any appear inordinate
(e.g., a filter switch in the monitor mode rather
than the diagnostic mode), consider the possibility of inappropriate clinical use or of incipient
device failure. Record the settings of those controls that should be returned to their original
positions following the inspection.
Examine all controls and switches for physical
condition, secure mounting, and correct motion.
Check that control knobs have not slipped on
their shafts. Where a control should operate
against fixed-limit stops, check for proper alignment, as well as positive stopping. Check membrane switches for membrane damage (e.g., from
fingernails, pens). During the course of the inspection, be sure to check that each control and
switch performs its proper function.
1.17 Battery/Charger. Inspect the physical condition of batteries and battery connectors, if readily accessible.
Check operation of
Figure 1. The calibration pulse or step response leading
edge should have square corners (left). Slight rounding
(middle) or small overshoot is acceptable. Excessive
rounding or overshoot (right) indicates the need for
adjustment.
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3
Inspection and Preventive Maintenance System
need to be set near either extreme to obtain a
satisfactory setting.
All portions of a simulated ECG waveform
should be clearly visible, including the P wave
and QRS.
There should be no 60 Hz noise when the lead
selector switch is set to the lead 0 or standard
position and the chart motor is activated.
Figure 2. Sag time is measured to the half-amplitude
point. The upper trace indicates a low-frequency response of about 0.05 Hz. The lower trace indicates a
low-frequency response of between 0.07 and 0.09 Hz.
cayed to no more than half its original amplitude
(see Figure 2 on page 4).
1.25 Paper Transport. Verify that the paper moves
smoothly and without hesitation at all paper
speeds. Problems might be caused by the transport mechanism or by a roll of paper that is
wound too tightly. The paper should not drift
sideways in the transport mechanism. If a formatted output is used (i.e., unit prints a single
formatted sheet for each electrocardiogram),
verify that all alphanumerics and tracings appear in the correct location and that the paper
starts and stops at the correct points.
2. Quantitative tests
2.1
Grounding Resistance. Using an ohmmeter,
electrical safety analyzer, or multimeter with
good resolution of fractional ohms, measure and
record the resistance between the grounding pin
of the power cord and exposed (unpainted and
not anodized) metal on the chassis. We recommend a maximum of 0.5 Ω.
2.2
Chassis Leakage Current. Measure chassis
leakage current to ground with the grounding
conductor of plug-connected equipment temporarily opened. Operate the device in all normal
modes, including on, standby, and off, and record
the maximum leakage current. Chassis leakage
current to ground should not exceed 300 µA.
2.3
Calibration. This test determines the accuracy
of both the sensitivity control and the internal 1
mV calibration signal and requires the use of an
external source of known amplitude (e.g., calibrated ECG simulator). If this calibration source
is battery powered, check its output with a precision voltmeter or similar instrument to confirm
that the output is not affected by changing battery voltage. An ECG simulator can be used,
even if its output is not precisely 1 or 2 mV,
provided its amplitude is accurately known and
appropriate corrections are made in interpreting
the results.
1.22 Labeling. Check that all necessary placards, labels, and instruction cards are present and legible.
1.23 Accessories. Verify that an adequate supply of
electrodes and paper and a fuse are stored with
the device or in the nursing unit for those electrocardiographs that remain in a fixed location.
A spare patient cable and stylus (or pen) may be
kept with units on crash carts.
1.24 Trace Quality. Observe the tracing with the unit
in the standard lead select position (no input)
and in lead I with a simulated ECG signal applied. Verify compliance with the following criteria:
The baseline should have constant thickness;
it should be horizontal and not drift vertically.
It should be possible to move the baseline from
the lower to the upper border of the chart
paper with the vertical position control, except
on those units where mechanical stops prevent such travel.
The baseline should remain within 1 mm of its
initial position upon pushing the reset control.
If so equipped, the operator-adjustable stylus
heat control should function and should not
4
With sensitivity at 20 mm/mV, record a 1 mV
pulse from the external reference generator and
one from the internal 1 mV calibration signal of
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Electrocardiographs
the writer. For an externally generated pulse of
exactly 1 mV, the tracing should be between 19
and 21 mm. Deviation greater than this can
often be corrected with the variable gain control
(a screwdriver adjustment in many units). If the
internally generated pulse and a 1 mV external
pulse produce tracings of heights that differ by
more than 0.5 mm, the internal calibrator is not
within the recommended 5% accuracy.
Next, record 1 mV pulses, either from the
internal calibrator or the reference generator, at
sensitivity settings of 2.5, 5, 10, and 20 mm/mV.
At each setting, the trace should double in height
(within 5%). Because of the difficulty in resolving
small errors, investigate any deviation of more
than 0.5 mm.
2.6
Linearity. Apply a calibrated 2 mV input to the
writer. Record the deflection at 10 mm/mV. It
should be twice the deflection (within 5%) observed for a 1 mV signal.
2.7
Paper Speed. Use an ECG simulator set to 60
bpm or a signal or pulse generator set to 1 Hz
that has been set or calibrated with a counter. If
the interval between pulses is not within 10 msec
at a pulse interval of 1,000 msec, an appropriate
correction should be made in calculating paper
speed. The speed should be accurate to within
2%. At a chart speed of 25 mm/sec and a pulse
interval of 1,000 msec (60 bpm on an ECG simulator), the distance between the first and last of
five successive peaks should be 100 ±2 mm; at a
chart speed of 50 mm/sec, the distance between
the first and last of five successive peaks should
be 200 ±4 mm.
3. Preventive maintenance
3.1
Clean the exterior (including front panel controls), all rollers, paper guides, and knife edges,
if needed.
3.2
Lubricate the recorder mechanism and paper
drive per the manufacturer’s specifications.
3.3
Calibrate damping and stylus, if required.
3.4
Replace filters and batteries, if required. Some
units have air filters that accompany the cooling
fan. Check and replace these filters, if needed.
If any of the test procedures indicate a weak or
defective battery, even after charging for 12 or
more hours, replace the battery.
4. Acceptance tests
Conduct major inspection tests for this procedure
and the appropriate tests in the General Devices Procedure/Checklist 438. Electrocardiographs should
meet the requirements for isolated input devices for
ECG lead-to-ground, interlead, and input isolation
tests. In addition, perform the following tests.
4.1
Frequency Response. Use the test setup shown
in Figure 3. Set the function generator and attenuator for a sinusoidal output of 2 Hz with a
peak-to-peak amplitude of 1 mV. Set the electrocardiograph gain to 10 mm/mV to obtain a peakto-peak deflection of 1 cm. (The deflection
amplitude is not critical. If your signal generator output is not easily adjusted, set the output
for any convenient peak-to-peak display and note
the height.) Measure between the extreme top
and bottom of the trace. Increase the output
frequency from the sinusoidal generator until the
display drops to 0.7 cm peak-to-peak, or 0.7 times
the 2 Hz deflection. (The waveform may be
slightly distorted.) Record this frequency as the
upper 3 dB point. When changing the output
frequency of the function generator, measure the
output amplitude peak-to-peak with the oscilloscope (DC response) to ensure that a constantamplitude sinusoid, 1 mV peak-to-peak, is
delivered to the electrocardiograph throughout
the bandwidth.
The low-frequency response point can be determined in a similar way by decreasing the frequency from 2 Hz until the display again drops to
0.7 cm peak-to-peak, or 0.7 times the 2 Hz deflection. However, it is much simpler to determine the
low-frequency response point using the step response test (see Item 1.19), Figure 2, and the
Figure 3. Signal input test setup.
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5
Inspection and Preventive Maintenance System
Relationship Between Sag and Low-Frequency
Response
Distance to
Half Amplitude
10 mm
20
30
40
50
55
60
80
Lower 3 dB
Frequency
0.27 Hz
0.13
0.092
0.069
0.055
0.050
0.046
0.034
Relationship Between Sag and Low-Frequency
Response table on page 6. While the technique
may not accurately predict the low-frequency
response of all units, it does provide an equally
(if not more) clinically relevant response test.
Some units have selectable frequency response modes. In the Filter In mode, low- and
high-frequency components of the electrocardiogram are attenuated. This mode can be used to
reduce baseline wander and high-frequency
noise, but because small distortions of the ECG
can occur, it should not be used when recording
diagnostic ECGs. The diagnostic response mode
provides an expanded bandwidth, as recommended by the American Heart Association.
This should produce a display that reproduces
more of the low- and high-frequency qualities of
the electrocardiogram than the Filter In (or monitor) mode. The electrocardiograph should normally be operated in the diagnostic mode.
The manufacturer’s specification for each frequency response mode should be used as a reference. The diagnostic mode bandwidth should be
at least 0.67 to 100 Hz.
Some units include a notch filter to minimize 60
Hz noise. On such units, confirm the notch filter’s
operation by sweeping past 60 Hz on the signal
generator and looking for a sharp dip in the response. If the response increases as the frequency
is increased past the notch filter frequency, then
the upper 3 dB point may be above the notch
filter frequency rather than occurring where the
filter begins to attenuate.
4.2
6
Common Mode Rejection Ratio (CMRR). The
electrocardiograph includes a differential amplifier so that it can display the voltage difference
between two electrodes (the RA and LA in Lead
1) while using a third (RL) as a reference. If the
same, or common, voltage is applied to RA and
LA simultaneously, there should be no output
from the differential amplifier because the voltage difference between the two inputs is zero.
The extent to which a differential amplifier produces no output when the same signal is applied
to both inputs is called its common mode rejection ratio.
Common mode rejection is needed because of
the presence of stray signals common to all input
leads primarily at power-line frequency (60 Hz).
While these signals are too minute to be hazardous, they can interfere with the ECG recording
on a unit with a low CMRR at 60 Hz.
The common mode rejection ratio is defined as:
CMMR =
Differential mode deflection factor, or DMD (mm ⁄ mV)
Common mode deflection factor, or CMD (mm ⁄ mV)
A deflection factor is the change in trace position corresponding to a given input voltage. Use
an unbalanced CMRR measurement that includes a 5,000 Ω resistor in series with one of
the input leads. This simulates the unequal impedances that usually exist in the electrode/skin
interfaces.
Since most common-mode voltage in the hospital is at 60 Hz, it is most significant to measure
the CMRR at or near that frequency. (A frequency of 55 Hz is often used to minimize interference from line-power frequency noise.) Using
the test setup shown in Figure 3, apply a sinusoid
test signal of 1 mV peak-to-peak at about 60 Hz
to the electrocardiograph. Set the gain to 20
mm/mV, measure the deflection in mm, and record it on the inspection form as the differential
mode deflection factor. Since the input signal for
this measurement was 1 mV, the differential
mode deflection factor expressed in mm/mV is
Figure 4. Common mode rejection ratio test setup.
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Electrocardiographs
Using the internal calibration button, generate a pulse with the baseline set at the bottom
margin of the chart, another with the baseline
at the middle of the chart, and a third with the
baseline as close to the top margin of the paper
as possible while still allowing the pulse to
remain on the ruled chart. The height of the
calibration pulse should not vary more than
0.5 mm with baseline position.
numerically equal to the resultant deflection in
mm. Do not change the gain setting or the signal
frequency for the remainder of this test. Record
the frequency.
Use the test setup shown in Figure 4 for the
second part of this measurement. Note that
there is only one connection from the output of
the attenuator to the patient leads. The other
output terminal is grounded. It is essential that
all instruments used in this test be connected to
a common ground to minimize noise.
Increase the amplitude of the sinusoid signal
(up to 10 V peak-to-peak) until some measurable
deflection is observed on the recorder. Calculate
the common mode deflection factor by dividing
the resultant deflection (in mm) by the input
signal (in mV). The CMRR may then be calculated as the differential mode deflection factor
divided by the common mode deflection factor.
If the unit has an ungrounded or plastic case,
measure the CMRR with the unit resting on a
grounded metal plate. CMRR should meet the
manufacturer’s specification and be at least
10,000:1.
4.3
Display range. The monitor should be able to
faithfully display signals of up to 5 mV. Using
the test setup shown in Figure 3 (signal generator set to about 2 Hz) or an ECG simulator
with an appropriate output range, apply a
5 mV peak-to-peak signal, and observe the
trace using gain and position settings that
keep the trace on the recording paper rulings.
Note any distortion or clipping of the signal.
4.4
Crosstalk. Verify that activation of time and
event markers does not cause a deflection on the
ECG trace. Check for channel crosstalk on multichannel electrocardiographs by attaching an
ECG simulator to one lead pair while the others
are shorted together. There should be no visible
trace deflection in any of the channel tracings
except the one with the simulated ECG.
Linearity. In addition to the linearity test described in Item 2.6, test the effect of baseline
position on linearity and linear input range.
Before returning to use
Baseline position. Vary the centering or position
control to change baseline position, if possible.
Set all controls to their original settings, and recharge the battery, if needed.
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©1995 ECRI. All Rights Reserved.
7
Procedure/Checklist 411-0595
Electrosurgical Units
Used For:
Electrosurgical Units [11-490]
Electrosurgical Units, General-Purpose [16-137]
Electrosurgical Units, Specialty [16-138]
Also Called: ESUs, electrocautery units (although this term more appropriately refers to a different type of
surgical device), Bovie (a registered trademark of MDT Diagnostic Co. to be used only when referring to that
device)
Commonly Used In: Operating rooms, outpatient surgical units
Scope: Applies to units that perform surgical functions (e.g., cutting, coagulation) by using high-frequency
electrical currents that pass through the body (units may include other functions such as insufflation); does not
apply to electrocautery units that use an electrical current to heat a tip for surgical effects
Risk Level: ECRI Recommended, High; Hospital Assessment,
Type
ECRI-Recommended
Interval
Major
12 months
months
.
hours
Minor
6 months
months
.
hours
Overview
Surgical use of high-frequency current dates back to
the early 1900s. Tesla and Oudin coil resonators in
conjunction with spark gaps produced high voltages at
very low currents, which were used to destroy superficial tissue with a spray of sparks from the active
electrode (fulguration). No return connection was provided between the patient and the electrosurgical unit.
Vacuum tubes were later introduced and provided
continuous sinusoidal wave generation. Circuits could
then be designed to produce lower voltages but higher
currents. However, the higher currents required a
reliable conductive path to complete the circuit, and
the dispersive electrode (also called the butt, safety,
patient, or ground plate, or return or indifferent electrode) was introduced.
Most currently marketed units are solid-state devices that permit size reduction and the generation of
a variety of waveforms without the use of a spark gap.
094428
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Interval Used
By Hospital
Time Required
They also incorporate microprocessor-controlled circuitry to monitor unit performance, adjust power settings, and, in some units, interrogate the quality of
contact of the return electrode.
Undamped, continuous sinusoidal currents (about
0.2 to 3.0 MHz) cut tissue with a cutting electrode or
loop with minimal coagulation. The intense heat explodes and volatilizes tissue cells. This type of current
can also be used to coagulate with large surface electrodes or hemostats. Damped waves and current
bursts coagulate, fulgurate, and desiccate with minimal cutting by generating heat in a wider region of
tissue immediately surrounding the active electrode.
The dry, fibrous residue left by the rapid dehydration
of cells blocks vessels and prevents bleeding. A combination of damped and undamped waveforms cuts and
coagulates simultaneously.
In electrosurgery, the heat that destroys tissue is
not produced by a heated wire as in electrocautery, but
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Inspection and Preventive Maintenance System
by conversion of the high-frequency electrical energy
in the tissue. Current density and duration determine
the amount of heat generated and tissue destroyed at
and near the electric arc. Active electrodes have small
tips to increase the current density at the surgical site.
Electrodes used specifically for cutting have small
points or edges to concentrate the electrosurgical current; coagulation electrodes have larger surface areas.
Both characteristics can be combined into a single
electrode (a blade type) so that electrodes need not be
changed during shifts between cutting and coagulation. Since no tissue heating is desired elsewhere, the
dispersive electrode must contact a much larger area
of the patient’s skin to reduce the return current density to harmless levels.
Periodic inspection is not a substitute for routine
pre-use verification of electrosurgical unit safety features and current use practices. Reusable active electrodes and accessories, such as bipolar and laparoscopic
forceps and leads, should be inspected periodically, but
they are not usually readily available with the electrosurgical unit. Where practical, users or processing personnel should routinely inspect these items.
Citations from Health Devices
Electrosurgical units [Evaluation], 1977 Jan-Feb;
6:59-86. (See also: 1977 Jun; 6:194.)
Ellman International Manufacturing Surgitron and
Surgitron FFPF [Hazard], 1986 Aug; 15:248.
ESU burns from poor return electrode site preparation
[Hazard], 1987 Jan; 16:35.
Electrosurgical units [Evaluation], 1987 Sep-Oct;
16:291-333.
Return electrode monitors: Assessing your needs [Risk
analysis], 1987 Sep-Oct; 16:335-7.
Controlling the risks of electrosurgery [Risk analysis],
1987 Sep-Oct; 16:337-9.
Bovie CSV: Still accepted? 1987 Sep-Oct; 16:340-1.
Do ESU output characteristics affect instrument performance? 1987 Sep-Oct; 16:341-2.
Pacemakers and electrosurgery: What precautions are
needed? 1987 Sep-Oct; 16:342.
Electrosurgical units [Evaluation update], 1988 Dec;
17:363-5.
Update: Controlling the risks of electrosurgery [Risk
analysis], 1989 Dec; 18:430-2.
Electrosurgery checklist, 1989 Dec; 18:432.
Electrosurgical unit safety, 1977 Mar; 6:119-21.
Update: ESU return electrode contact quality monitors
[Risk analysis], 1989 Dec; 18:433-6.
Fires during surgery of the head and neck area
[Hazard], 1979 Dec; 9:50.
Argon beam coagulation systems [Evaluation], 1990
Sep; 19:299-320.
Fires during surgery of the head and neck area
[Hazard update], 1980 Jan; 9:82.
Argon beam coagulation systems [Evaluation update],
1990 Dec; 19:444-5.
Adapters and cables for electrosurgical dispersive
electrodes [Hazard], 1981 Jan; 10:74-5.
Stryker Surgical microsurgical drills: Activation by
ESUs [Hazard], 1991 Oct; 20:409-10.
Adapters and cables for disposable electrosurgical dispersive electrodes [Hazard update], 1981 Feb;
10:99.
Stryker Surgical microsurgical drills: Activation by
ESUs [Hazard update], 1991 Nov; 20:446.
Using two ESUs on one patient [Consultant’s Corner],
1982 Sep; 11:301-2.
Stryker Surgical microsurgical drills: Activation by
ESUs [Hazard update], 1991 Dec; 20:496-7.
ESU return electrode contact quality monitors [Evaluation], 1985 Feb; 14:115.
Birtcher 4400 electrosurgical units and 6400 argon
beam coagulation systems [Hazard], 1992 Jun-Jul;
21:249-50.
Electrosurgical unit activation tone control [Hazard],
1985 Nov; 14:407.
Burns and fires from electrosurgical active electrodes
[Hazard update], 1993 Aug-Sep; 22:421-2.
Isolated incidents: Electrosurgical units [User Experience NetworkTM], 1986 May; 15:143.
ESU burns from poor dispersive electrode site preparation [Hazard], 1993 Aug-Sep; 22:422-3.
Hand-switched electrosurgical active electrode pencils
[Evaluation], 1986 Jun; 15:151.
Burns and fires from electrosurgical active electrodes
[Hazard update correction], 1993 Oct; 22:502.
2
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Electrosurgical Units
Use of an incompatible footswitch with Aspen Excalibur, Birtcher 5000, and Valleylab Force electrosurgical units [Hazard], 1993 Dec; 22:593-4.
Never activate the unit with the active and dispersive electrodes connected together (short-circuited),
since this may damage the unit.
Electrosurgical units with accessory outputs [User Experience NetworkTM], 1993 Dec; 22:601-2.
Procedure
Fatal gas embolism caused by overpressurization during laparoscopic use of argon enhanced coagulation
[Hazard], 1994 Jun; 23:257-9.
Risk of electrosurgical burns at needle electrode sites
[Hazard], 1994 Aug-Sep; 23:373-4.
Monopolar electrosurgical safety during laparoscopy
[Guidance article], 1995 Jan; 24:6-27.
Misconnection of bipolar electrosurgical electrodes
[Hazard], 1995 Jan; 24:34-5.
Test apparatus and supplies
Leakage current meter or electrical safety analyzer
Ground resistance ohmmeter
High-resistance (20 MΩ) ohmmeter
Connectors, adapters, active electrode and/or return
electrode, as required; open-circuited dispersive
electrode connector may be required
Electrosurgical unit analyzer
Before beginning an inspection, carefully read this
procedure and the manufacturer’s instruction and
service manuals; be sure that you understand how to
operate the equipment, the significance of each control
and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive
maintenance procedures or frequencies are recommended by the manufacturer.
Use an electrosurgical unit analyzer with appropriate load resistances for measuring electrosurgical unit
output. A number of methods for testing electrosurgical output have been suggested, including the use of
light-bulb loads, sparking the active electrode to the
return electrode, and cutting a slice of beef placed on
the return electrode. However, none of these provide
quantitative performance data, and some methods
may damage the electrosurgical unit.
When measuring output (e.g., Items 2.3 and 2.10),
do not use excessive lead lengths or coil the leads
because either may affect measurement accuracy.
1. Qualitative tests
1.1
Chassis/Housing. Examine the exterior of the
unit for cleanliness and general physical condition. Be sure that plastic housings are intact,
that assembly hardware is present and tight,
and that there are no signs of spilled liquids or
other serious abuse.
1.2
Mount. If the device is mounted on a stand or
cart, examine the condition of the mount. If it is
attached to a wall or rests on a shelf, check the
security of this attachment.
1.3
Casters/Brakes. If the device moves on casters,
check their condition. Look for accumulations of
lint and thread around the casters, and be sure
that they turn and swivel, as appropriate. Check
the operation of brakes and swivel locks, if the
unit is so equipped.
1.4
AC Plug/Receptacles. Examine the AC power
plug for damage. Attempt to wiggle the blades
to determine that they are secure. Shake the
plug and listen for rattles that could indicate
loose screws. If any damage is suspected, open
the plug and inspect it. If the device has electrical receptacles for accessories, insert an AC plug
into each, and check that it is held firmly. If
Oscilloscope and high-voltage probe (acceptance
testing only)
Special precautions
Electrosurgical units deliver high voltage and high
power that can cause serious electrical burns. Be sure
that all connections are secure and well insulated
before performing any power output test. Do not contact either the active or dispersive electrode while the
unit is activated (under some circumstances, burns can
occur even from contact with the dispersive electrode).
When making connections and whenever testing is not
being performed, make sure the unit is off or in the
standby mode.
Never operate any electrosurgical unit for prolonged
periods during testing, especially at maximum control
settings. Electrosurgical units can be damaged by such
operation.
Hazardous high voltages are present inside electrosurgical units. Do not open the electrosurgical
units for inspection or adjustment unless you are
qualified to do so.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
3
Inspection and Preventive Maintenance System
accessories are plugged and unplugged often,
consider a full inspection of the receptacle.
1.5
Line Cord. Inspect the cord for signs of damage.
If damaged, replace the entire cord, or, if the
damage is near one end, cut out the defective
portion. Be sure to wire a new power cord or plug
with the same polarity as the old one.
1.6
Strain Reliefs. Examine the strain reliefs at
both ends of the line cord. Be sure that they hold
the cord securely.
1.7
1.9
Circuit Breaker/Fuse. If the device has a
switch-type circuit breaker, check that it moves
freely. If the device is protected by an external
fuse, check its value and type against that
marked on the chassis, and ensure that a spare
is provided.
Cables. Inspect the cables (e.g., footswitch) and
their strain reliefs for general condition. Examine cables carefully to detect breaks in the insulation and to ensure that they are gripped
securely in the connectors at each end to prevent
rotation or other strain.
1.10 Fittings/Connectors. Examine electrical connectors for general condition. Electrical contact pins
or surfaces should be straight, clean, and bright.
1.11 Dispersive Electrodes. Inspect reusable dispersive electrode cables carefully for any breaks in
the insulation and other obvious damage. Examine the electrosurgical unit and return electrode connectors for signs of damage. Confirm
that their strain reliefs are secure. Check that
several dispersive electrodes and dispersive electrode cables (separate or preattached) are stored
with the electrosurgical unit. (If reusable dispersive electrodes are in use, replace them with
single-use dispersive electrodes with preattached adhesive. Using disposable dispersive
electrodes with preattached adhesive is much
less likely to result in patient burns.)
1.12 Filters. Check the condition of all filters. Clean
or replace if needed, and indicate this on Line 3.1
or 3.4 of the inspection form.
1.13 Controls/Switches. Before moving any controls,
check their positions. If any of them appear
inordinate (e.g., a control set at maximum output), consider the possibility of inappropriate
clinical use or of incipient device failure. Record
the settings of those controls that should be
returned to their original positions following the
4
inspection. Examine all controls and switches
for physical condition, secure mounting, and correct motion. Where a control should operate
against fixed-limit stops, check for proper alignment, as well as positive stopping. Check membrane switches for membrane damage (e.g., from
fingernails, pens). During the course of the inspection, be sure to check that each control and
switch performs its proper function.
1.18 Indicators/Displays. During the course of the
inspection, confirm the operation of all lights,
indicators, meters, gauges, and visual displays
on the unit. Be sure that all segments of a digital
display function.
1.20 Dispersive Cable Continuity Monitor. Confirm
that this sentry triggers an audible (and on some
units, a visual) alarm if continuity of the return
cable is interrupted. The electrosurgical unit
should be locked out of activation in this alarm
mode.
To test the cable continuity monitor, turn all
output controls to minimum, disconnect any active electrodes, connect a complete cable and
dispersive electrode assembly to the electrosurgical unit, and turn the unit on but do not operate
it. Suspend the dispersive electrode in the air so
that it does not touch any metal surface or object
that might provide a ground pathway back to the
electrosurgical unit. Do not touch the electrode.
The alarm should not sound.
A loose panel connection to the dispersive
cable often causes the return cable continuity
monitor’s alarm to sound, which may annoy the
OR staff. Wiggle the dispersive cable connection
at the unit. If this cable motion sets off the
alarm, suspect a weak connector, and arrange
for repairs.
Unplug or unscrew the cable connector from
the dispersive electrode. The unit should alarm
immediately and should resist activation. If this
does not occur, the return cable may be shorted
or the alarm itself may be defective. To determine the cause, unplug the dispersive electrode
cord from the electrosurgical unit. If the alarm
does not activate, it is defective and needs repair.
If the alarm activates, the dispersive cable is
defective and should be replaced.
If the dispersive electrode is permanently attached to the dispersive cable and the electrosurgical unit is designed to automatically disable
the buzzer alarm when the dispersive cable is
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Electrosurgical Units
Dispersive electrode grounding resistance.
Measure the resistance between the dispersive
electrode and the ground pin of the power cord.
This measurement should indicate an open
circuit (exceeding 20 MΩ or largest reading of
the ohmmeter) for isolated-output units or
grounded units equipped with a capacitor between the dispersive electrode and ground; the
latter are called ground-referenced units. A
value less than 20 MΩ for ground-referenced
units suggests a defective capacitor between
the dispersive electrode and ground inside the
electrosurgical unit. An initial low resistance
that drifts up to a value over 20 MΩ is acceptable; this phenomenon is due to a charging
capacitor. There should be a short circuit (approximately 0.15 Ω) for grounded-output units
without a capacitor. ECRI recommends that
units with the dispersive electrode connected
directly to ground be replaced with isolatedoutput or ground-referenced units.
unplugged, use an open-circuited connector to
test the alarm.
1.21 Audible Signals. Operate the device to activate
any audible signals (e.g., activation indicator,
dispersive cable continuity monitor). Confirm
appropriate volume, as well as the operation of
a volume control. Serious injury has been associated with warning signals (e.g., activation indicator) whose volume controls had been set so
that the signals were not audible. If volume
controls have been set too low, discuss this problem with users so that clinical practices can be
corrected. Units that lack audible activation indicators should be removed from service. Units
with audible activation indicators that can be set
to inaudible levels should also be removed from
service or modified by the manufacturer so that
the alarm cannot be set to an inaudible level.
1.22 Labeling. Check that all necessary placards,
labels, and instruction cards are present and
legible.
1.23 Accessories.
Footswitch. Examine the footswitch for general
condition, including evidence of spilled fluids.
Check for any tendency of the footswitch to
stick in the On position. Activate the switch
in both the Cut and Coagulation modes and
flex the cable at the entry to the switch to
check for internal wire breaks that may cause
intermittent device operation.
1.24 Special Protective Features. Test alternative
protective features according to instructions
from the manufacturer’s literature. These include features intended to monitor the integrity
of the patient circuit (e.g., dispersive electrode
contact quality monitors), ensure absence of inadvertent ground contacts (e.g., return fault
monitors), or minimize injury from active electrode insulation failures or capacitive coupling
(e.g., monopolar electrode shielding devices).
These features can be either integral to the electrosurgical unit or add-on devices.
2. Quantitative tests
2.1
Grounding Resistance. Measure and record the
resistance between the grounding pin of the
power cord and exposed (unpainted and not anodized) metal on the chassis, accessory outlet,
ground pins, and footswitch. We recommend a
maximum of 0.5 Ω.
2.2
Chassis Leakage Current. While electrosurgical
units are generally operated from isolated power
systems in the operating room, power line frequency and leakage current measurements must
be made with the unit connected to a grounded
(conventional) power supply to obtain valid readings. This is most readily accomplished by removing the electrosurgical unit from the operating
suite to an area with grounded power distribution.
An adapter cord will be needed if the unit is
equipped with a specialized operating room plug.
Before measuring the leakage currents, turn
all the unit’s power controls to zero. Connect a
return electrode if the unit cannot be activated
without one. Connect one lead of the leakage
current meter to ground, and position the meter
away from the electrosurgical unit. With the
other lead of the leakage current meter in the
vicinity of the electrosurgical unit but not in
contact, activate the unit in its various operating
modes, keeping the output at the minimum settings. Any significant reading on the leakage
current meter indicates that the meter is susceptible to high-frequency interference and cannot
be used when the electrosurgical unit is activated. A 0.1-microfarad capacitor connected
across the leakage current meter terminals may
reduce this interference and will not unduly affect the line frequency leakage current readings.
CAUTION: Never measure 60 Hz leakage currents from the active electrode while the unit is
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
5
Inspection and Preventive Maintenance System
activated. Also, when testing an isolated output
electrosurgical unit, do not measure currents from
the return electrode when the unit is activated.
These measurements can expose you to high voltage and can damage the leakage current meter.
Measure chassis leakage current to ground
with the grounding conductor of plug-connected
equipment temporarily opened. Measure with
the unit off, on (standby), and activated in each
mode (e.g., Cut 1, Cut 2) with power controls set
at minimum. Record the value for the mode that
yields the highest leakage current. Leakage currents from the chassis should not exceed 300 µA.
2.3
ate the unit for long periods or at maximum
control settings, since this will stress the unit.
2.10 Output Current/Power. Connect the output current or power meter to the active and dispersive
connections on the electrosurgical unit. On units
with a return electrode continuity monitor, use
a dispersive electrode or an appropriately wired
adapter.
Output power should be tested according to
the manufacturer’s recommendations. If the
electrosurgical analyzer in use does not have the
load resistance suggested by the manufacturer,
it can still be used, but output powers may be
different from those given in the service manual
(some manuals may indicate how output varies
with load resistance). Record the load resistance
of the output meter on the inspection form.
Output Isolation. This test is intended for isolated output units to determine whether the
isolation has been degraded. Do not perform this
test on units with directly grounded dispersive
electrodes or with dispersive electrodes connected to ground through a capacitor. Consult
the unit’s manual if you are uncertain whether
it is an isolated output device. The isolation test
is normally conducted after the output power
measurement (Item 2.10).
Test the unit at the manufacturer’s recommended output settings or at a typical clinical
setting (or at a dial setting about one-third of
maximum and at maximum). Using all the operating modes available on the electrosurgical unit,
record the output current or power from the meter.
Confirm that power is delivered to secondary monopolar terminals. Also measure output at bipolar
terminals. The output should increase smoothly
from zero or nearly zero to maximum. Do not
operate the unit at high control settings for prolonged periods, since this places an unrealistic and
unnecessary strain on both the electrosurgical unit
and the tester. It will not be possible to read
low-current values precisely. Compare output
power to the manufacturer’s specifications. Erratic output power in spark-gap units suggests
that spark gaps may need maintenance or adjustment. This should be done only by qualified, experienced personnel. Use Lines 2.11 and 2.12 of the
inspection form as needed for additional output
power measurements.
If the tester has an Isolation Test mode, follow
the tester’s instructions. Otherwise, connect the
output current/power meter between the active
cable and a ground (e.g., the chassis of the unit).
The dispersive cable and dispersive electrode of
the electrosurgical unit must not be in contact
with ground. If the unit has no dispersive circuit
monitor, unplug the dispersive cable from the
unit. If the unit has a dispersive sentry, suspend
the dispersive electrode in the air by hanging the
dispersive cable over a hook.
CAUTION: To avoid the possibility of burns,
do not touch the electrode.
With the unit in the Pure Cut or Cut 1 mode,
increase the controls gradually to one of the
moderate levels used in the output power test
and record the power to ground. The extent of
output reduction, compared with the output recorded in Item 2.10, is an indication of the degree
of isolation.
Isolation % = 1 –
P ower (W ) of isolation test (Item 2.3)
x 100%
Output power (W ) at the sam e setting (Item 2.10)
3.1
Clean the exterior and interior, if needed.
3.4
Replace the filter.
4. Acceptance tests
x 100%
Conduct major inspection tests for this procedure
and the appropriate tests in the General Devices Procedure/Checklist 438.
Isolation should meet the manufacturer’s
specifications or be ≥80%. As before, do not oper-
CAUTION: Never measure 60 Hz leakage currents
from the active electrode while the unit is activated.
Also, when testing an isolated output electrosurgical
or = 1 –
6
3. Preventive maintenance
Current2 (amps) of isolation test (Item 2.3)
Output current2 (amps) of same setting (Item 2.10)
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Electrosurgical Units
unit, do not measure currents from the return electrode
when the unit is activated. These measurements can
expose you to high voltage and can damage the leakage
current meter. Leakage current from the active and
return electrode should not exceed 50 µA. In addition,
perform the following tests.
4.1
Waveform Analysis. If a manufacturer has provided output waveform characteristics (e.g., frequency, waveform repetition or burst rate,
waveform on-off time), these may be studied and
documented by using an oscilloscope connected
to the appropriate jack on the output power/current meter. This test is optional. A high-voltage
probe should be used for these measurements to
prevent damage to the oscilloscope and to view
the full waveforms.
4.2
Output Isolation (for isolated output units only).
In addition to the test described in Item 2.3, make
a similar power measurement from dispersive
electrode to ground, preferably with a handswitched active handle connected to the unit.
This will ensure that excessive power is not available from the dispersive electrode. Set the unit
to Pure Cut, maximum output. Power exceeding
5 W suggests a fault or design deficiency.
Before returning to use
Ensure that the volume of audible activation indicators can be clearly heard, turn off the main power
switch, rotate the power control knobs to zero, neatly
coil and store all cables, and store all accessories.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
7
Procedure/Checklist 464-0595
Frequency-Doubled Nd:YAG Surgical Lasers
Used For:
Lasers, Surgical, Nd:YAG, Frequency-Doubled [17-729]
Also Called: KTP lasers, 532 lasers, green lasers, surgical lasers, endoscopic lasers
Commonly Used In: Operating rooms, short procedure areas, endoscopy laboratories
Scope: Applies to general-purpose frequency-doubled Nd:YAG surgical lasers that include contact and/or
noncontact flexible fiberoptic delivery systems (either reusable or disposable), emit visible green light energy
at 532 nm, and can provide sufficient power output to coagulate and vaporize tissue; applies to low- and
high-power frequency-doubled Nd:YAG surgical lasers that are typically used for general surgery, gastroenterology, bronchopulmonary, neurosurgery, gynecology, and ENT surgery procedures; does not apply to
frequency-doubled Nd:YAG lasers used solely for ophthalmic surgery; also does not apply to other ophthalmic
lasers or to CO2 lasers, Nd:YAG lasers, argon lasers, or other surgical lasers; however, many of the tests listed
herein can be used or modified for these other lasers
Risk Level: ECRI Recommended, High; Hospital Assessment,
Type
ECRI-Recommended
Interval
Major
12 months
months
.
hours
Minor
6 months
months
.
hours
Overview
Frequency-doubled Nd:YAG surgical lasers are normally checked before each use by the laser’s power-on
self-test and by user examination of the aiming beam
and the delivery system to be used. This minimizes the
need for frequent additional periodic testing.
Manufacturers or outside service vendors often
maintain lasers for hospitals. The extent and frequency of inspection by hospital personnel should be
coordinated with these outside services.
Failure of a frequency-doubled Nd:YAG surgical
laser can cause patient or staff injury, abrupt interruption of a surgical procedure, or damage to the laser
system. These lasers must be meticulously maintained
to ensure proper and safe operation.
Frequency-doubled Nd:YAG surgical lasers affect
tissue by delivering green visible light energy at a
230376
464-0595
A NONPROFIT AGENCY
Interval Used
By Hospital
Time Required
sufficient power density to cause vaporization and/or
coagulation. The 532 nm light energy is preferentially
absorbed by hemoglobin and is typically absorbed
within 3 mm of the tissue surface. Frequency-doubled
Nd:YAG surgical laser fibers are most often used in
contact with or close to tissue to cause coagulation or
vaporization. Moving the fiber tip away from the tissue
lowers the power density, causing less tissue to be
vaporized or coagulated.
General-purpose frequency-doubled Nd:YAG surgical lasers direct the beam of an Nd:YAG laser through
a crystal that halves the 1,064 nm wavelength (i.e.,
doubles the frequency) to 532 nm. (The Nd:YAG laser
uses an yttrium-aluminum-garnet [YAG] crystalline
rod that is doped with neodymium [Nd].) Energy exiting
the crystal is typically directed into a flexible optical
fiber that transmits the laser energy to the tissue. The
fiber may be used with additional devices (e.g., through
an endoscope) and/or with a laser handpiece or a laser
5200 Butler Pike, Plymouth Meeting, PA 19462-1298, USA
Telephone +1 (610) 825-6000 ● Fax +1 (610) 834-1275
●
E-mail [email protected]
Inspection and Preventive Maintenance System
micromanipulator (used to interface the laser with the
surgical microscope). These attachments can focus the
energy into a small spot size at a known working
distance and/or a specific beam direction to accomplish
special tasks. In addition, frequency-doubled Nd:YAG
lasers can emit a train of pulses or a single pulse.
of sufficient optical density to protect the wearer’s
eyes from laser energy
Like most lasers, frequency-doubled Nd:YAG lasers
are inefficient in converting electrical energy into laser
energy. As a result, excess heat is generated in the
laser cavity and doubling crystal, requiring a cooling
system. Most frequency-doubled Nd:YAG lasers use
water/air cooling systems that are self-contained, connected to a freestanding chiller system, or connected
to a water supply and drain.
Outlet test fixture (optional)
With frequency-doubled Nd:YAG surgical lasers,
unlike those lasers that use mirror delivery systems
(e.g., articulating arms on CO2 lasers), it is not necessary to periodically verify coincidence of the aiming
and therapeutic beam or to assess the therapeutic
beam pattern (e.g., TEM00) within the beam or spot.
Since the therapeutic and aiming laser beams are
transmitted through a single optical fiber, these two
beams are coincident as they exit the fiber. Any beam
pattern distortion at the fiber entrance would be eliminated as the laser beams travel through the fiber
because of internal reflections within the fiber. Misalignment of the beam at the fiber entrance would
result in decreased power output or loss or distortion
of the aiming beam. In a well-aligned system, any
significant problem with the therapeutic beam pattern
introduced by an accessory would be apparent by examining the visible aiming beam.
Citations from Health Devices
Laser use and safety [Guidance article], 1992 Sep;
21(9):306-10.
Surgical lasers [Evaluation], 1991 Jul-Aug; 20(78):239-316.
Test apparatus and supplies
Leakage current meter or electrical safety analyzer
Vise with padded jaws or ring stand with padded
clamp
Pressure gauges and coolant system tee fitting
Insulating gloves, high voltage (optional)
Grounding strap (optional)
Calibrated flowmeter
Special precautions
Inspecting and maintaining lasers is a dangerous as
well as necessary process, and far greater care is
required than with most devices. Personnel who inspect or service lasers should receive special training
from the manufacturer or from a qualified alternative
training source.
Laser energy can cause serious injury, particularly
when the internal interlock is overridden or in any
other situation in which the energy does not diverge
significantly over long distances. Under some circumstances, the beam may not diverge significantly, even
a full room length or more away from the laser (and
can harm tissue or burn material even at this distance). Therefore, exercise great care whenever a laser
beam is accessible. Area security and use of personnel
protective devices and practices should be consistent
with hospitalwide laser safety procedures and/or
should be approved by the laser safety committee.
In addition, windows should be covered with nonreflective material to prevent transmission of laser energy to other areas.
Wear appropriate laser safety eyewear at all times
whenever the laser is in the Operating mode. WARNING: Do not stare directly into the aiming system beam
or the therapeutic laser, even when wearing laser safety
eyewear. Avoid placing the laser beam path at eye level
(i.e., when kneeling, sitting, or standing).
Ground resistance ohmmeter
New, unused fiber delivery system
Black Delrin block 1⁄2″ or more thick, 1″ or more
wide, about 3″ to 4″ long; tongue depressors; or
firebrick
Laser radiometer (power meter)
Laser safety signs
Laser safety eyewear specifically designed for use
with frequency-doubled Nd:YAG surgical lasers and
2
Do not perform these procedures when a patient is
present or clinical staff is working, and do not aim the
laser across a path that a person might normally use
as a thoroughfare. Furthermore, at minimum, post
doors to the room with appropriate laser safety signs
stating that the laser is in use and that it is unsafe to
enter the room without authorization by the service
person performing the procedure. A second person
should be present, especially during procedures of recognized risk, to summon help in case of an accident.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Frequency-Doubled Nd:YAG Surgical Lasers
The laser should remain in the Off position when
not in use. When in use, it should be in the
Standby/Disabled mode. Do not switch it to the Operating mode until the procedure is about to begin and
the laser and its delivery system are properly positioned. If the procedure must be interrupted, disconnect the laser from line voltage, and remove the laser
operation key and store it in a controlled location.
Do not use the laser in the presence of flammable
anesthetics or other volatile substances or materials
(e.g., alcohol), or in oxygen-enriched atmospheres, because of the serious risk of explosion and fire. Remove
from the working area or cover with flame-resistant
opaque material all reflective surfaces likely to be
contacted by the laser beam. Whenever possible, use a
firebrick or other nonflammable material behind the
target material (e.g., black Delrin) when the laser is to
be activated. Target materials will ignite when exposed to high laser energies; use short durations when
practical. A CO2 fire extinguisher should be readily
available.
Some surgical lasers use high voltages (e.g., 20 kV),
which can be lethal. Capacitors may store charges long
after the device has been disconnected from line voltage. Consult the manufacturer’s recommended procedures for servicing high-voltage laser circuits, and
avoid contact with any portion of the high-voltage
circuit until you are certain that the charge has been
drained. In such instances, a good ground must be
present; preferably, use a redundant ground strap if
you must enter the laser cabinet. When possible, disconnect the laser from line voltage before entering the
laser cabinet, and use insulated gloves for those procedures in which contact with a high-voltage source is
possible (and the gloves are not otherwise contraindicated). Ensure that equipment intended to be used to
measure, drain, or insulate high voltages carries the
appropriate insulation rating (e.g., above 20 kV).
Procedure
Before beginning the inspection, carefully read this
procedure and the manufacturer’s operator instructions and service manual; be sure that you understand
how to operate the equipment, the significance of each
control and indicator, and precautions needed to ensure safety and avoid equipment damage. Also, determine whether any special inspection or preventive
maintenance procedures or frequencies are recommended by the manufacturer.
1. Qualitative tests
1.1
General. Verify that the key has not been left in
the laser. (Remove it if it has been, and inform
users of the importance of storing the key in a
controlled location.) Examine the exterior of
the unit for cleanliness and general physical
condition. Be sure that all housings are intact
and properly aligned, that assembly hardware is present and tight, that any retractable
parts slide easily and lock in place if so constructed, that there are no signs of spilled
liquids or other evidence of abuse, and that
there are no obvious signs of water or oil
leakage.
Shutters. If manual shutters for the aiming system or the therapeutic laser are accessible,
ensure that they operate smoothly and correctly. Be sure to leave the shutter in the
proper position for normal operation.
1.2
Where possible, perform tests with the unit turned
off. Because of the presence of high voltage, perform
the Grounding Resistance test (Item 2.1) before any
other test that requires operation of the laser.
WARNING: Do not use an anesthesia or other similar bag that may have a mold-release agent (e.g., starch,
talc) on its inside surface because the agent could
contaminate the gas recirculation system of the laser
and ultimately contaminate a patient wound during a
subsequent procedure.
Report any laser accident immediately to the laser
safety officer or equivalent, as well as to the hospital
risk manager.
Chassis/Housing.
Mounts/Holders. Check that the mounts securely contain any gas cylinders that may be in
use. Be sure that mounts or holders intended to
secure the fiber to the fiber support (to protect
the fiber when in use) are present, in good working order, and being used. Similarly, check
mounts or holders for other devices (e.g., external power meters, footswitches).
If the device is mounted on a stand or a cart,
examine the condition of the mount. Verify that
the mounting apparatus is secure and that all
hardware is firmly in place.
1.3
Casters/Brakes. Verify that the casters roll and
swivel freely. Check the operation of brakes and
swivel locks.
1.4
AC Plug/Receptacle. Examine the AC power plug
for damage. Wiggle the blades to determine
whether they are secure. Shake the plug, and
listen for rattles that could indicate loose screws.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
3
Inspection and Preventive Maintenance System
If damage is suspected, open the plug and inspect
it.
1.5
Line Cords. Inspect line cords for signs of damage. If a cord is damaged, replace the entire cord,
or, if the damage is near one end, cut out the
defective portion. Be sure to wire a new power
cord or plug with same polarity as the old one.
1.6
Strain Reliefs. Examine the strain reliefs at
both ends of the line cord. Be sure that they grip
the cord securely.
1.7
Circuit Breakers/Fuses. If the device has a
switch-type circuit breaker, check that it moves
freely. If the device is protected by an external
fuse(s), check its value and type against what is
marked on the chassis or noted in the instruction
or service manual. Ensure that a spare is provided or readily available.
1.8
Tubes/Hoses. Check the condition of all coolingsystem hoses and any other hoses or tubing the
laser may have (e.g., drain, gas). Check that they
are of the correct type; that they have not become
cracked and do not show other signs of significant abuse; that they are connected correctly
and positioned so that they will not leak, kink,
trail on the floor, or be caught in moving parts;
and that they are secured adequately to any
connectors.
1.9
Cables. Inspect all cables and their channels or
strain reliefs for general physical condition. Examine cables carefully to detect breaks in insulation and to ensure that they are gripped
securely in the connectors at each end to prevent
strain on the cable.
1.10 Fittings/Connectors. Examine all optical (e.g.,
fiber), liquid, and electrical fittings and connectors for general physical condition. Liquid fittings
should be tight and should not leak. Electrical
contacts should be straight, clean, and bright.
There should be no visible dirt or residue in
the optical path of the laser aperture. Ensure
that any mechanism to close off the laser aperture (fiber port) is clean, operates smoothly, and
is in use.
1.12 Filters. Check the condition of all liquid and air
filters. Some frequency-doubled Nd:YAG surgical lasers require deionized water, and most
require special filtration. Measuring the pressure drop across a liquid filter can be helpful in
determining whether the filter should be re-
4
placed. Clean or replace filters according to the
manufacturer’s recommendations (e.g., replace
if the pressure drop is >5 psi), and indicate this
in the preventive maintenance section of the
inspection form. Clean or replace air filters and
radiators that are obviously dirty.
1.13 Controls/Switches.
General. Before moving any controls, check and
record their positions. If any position appears
unusual, consider the possibility of inappropriate use or of incipient device failure. Examine all controls and switches for physical
condition, secure mounting, and correct motion. If a control has fixed-limit stops, check
for proper alignment, as well as positive stopping. Check membrane switches for tape residue and for membrane damage (e.g., from
fingernails, pens, surgical instruments). If
you find such evidence, notify users to avoid
using tape and sharp instruments. During the
inspection, be sure that each control and
switch works properly.
Remote. Examine the exterior of the control for
cleanliness and general physical condition. Be
sure that housings are intact, that assembly
hardware is present and tight, and that there
are no signs of spilled liquids or other serious
abuse. If the remote control is attached by
cable to the laser, ensure that the cable and
any connectors are in good condition. Examine
all controls and switches for general physical
condition, secure mounting, correct motion,
and intended range of settings. Where a control should operate against fixed-limit stops,
check for proper alignment as well as positive
stopping. During the inspection, be sure to
check that each control and switch performs
properly.
Footswitch. Examine the footswitch for general
physical condition, including evidence of
spilled liquids. Footswitches for lasers include
an internal switch that activates according to
the depth of pedal depression. It is usually
possible to feel the vibration caused by closure
of the switch, even through a shoe. Check that
the internal switch is operating and that the
footswitch does not stick in the on position.
Some footswitches include two internal
switches; in this case, verify the operation of
both. Some footswitches also include a switch
to operate the liquid- or gas-cooling system.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Frequency-Doubled Nd:YAG Surgical Lasers
Check to be sure that this switch operates
reliably.
(e.g., settings, displays) is indicated on both control panels.
During the procedure, check to be sure
that the laser activates consistently when the
footswitch is depressed and that the fiber-coolant system operates properly when the fibercoolant switch is activated and deactivated.
Flex the cable at the entry to the switch, and,
using an ohmmeter, check for internal wire
breaks that cause intermittent operation.
Confirm that strain reliefs are secure.
If display screens or digital displays are provided for user prompts or for viewing accumulated information (e.g., pulse or accumulated
energy counter), ensure that each display provides the information expected. Ensure that user
prompts occur in the proper sequence. Store
some sample information, and verify that it is
correct. If a feature to manually reset this information is available, ensure that it works.
Examine the male and female connectors for
attaching the footswitch to the laser cabinet to
be sure that no pins are bent and that no other
damage is present. Ensure that the connector
secures acceptably to the laser cabinet.
1.19 Laser Delivery System Calibration. Some frequency-doubled Nd:YAG surgical lasers include
a user-accessible calibration port or power meter
that allows output calibration and/or testing of
the laser fiber. This feature is provided because
transmission of laser energy through a fiber may
change as a result of fiber use. Based on the
measurement from the calibration power meter,
the laser may automatically recalibrate itself
and/or adjust displays so that the power indicated to be delivered to the patient will be correct, or it may require the user to do this
manually. Verify that this feature is functioning
by using the manufacturer’s recommended calibration procedure to test one delivery system
(e.g., fiber, handpiece) that the manufacturer
indicates can be acceptably calibrated using
these procedures. A good-quality (e.g., >85%
transmissibility, undamaged sheath) fiber or
handpiece should be used for this test.
1.15 Motors/Pumps/Fans/Compressors. Check the
physical condition and proper operation of these
components, if present. If lubrication is required,
note this in the preventive maintenance section
of the form. Clean any obvious dust from these
components.
1.16 Fluid Levels. Check all fluid (e.g., coolant) levels.
Refill or change the fluid according to the manufacturer’s recommendations, and note this on the
preventive maintenance section of the inspection
form. If an external water supply is in use, ensure
that the water pressure is properly regulated and
at the appropriate pressure and that the supply
and drain system is properly configured (e.g.,
filters are oriented for proper flow, drain hoses
are positioned in a sink or drain).
1.17 Battery. Inspect the physical condition of batteries
and battery connectors, if readily accessible. If a
remote control or display is battery powered, check
or replace the battery (periodic prophylactic battery replacement is often preferred to risking battery failure during use). When it is necessary to
replace a battery, label it with the date.
1.18 Indicators/Displays. During the inspection,
verify proper operation of all lights, indicators,
meters, gauges, and visual displays on the unit
and remote control. Ensure that all segments of
a digital display function. Note any error messages displayed during the power-on self-test.
If primary and remote-control indicators and
displays can be used at the same time or if control
can be switched from one to the other during a
procedure, verify that the same information
1.20 Alarms/Interlocks. Operate the device in a
manner that will activate the self-check feature, if present, and verify that all visual and
audible alarms activate according to the manufacturer’s documentation. If no self-check feature is present, operate the laser in a manner
that will activate each audible and visual
alarm; be sure to test only those alarms that
will not cause damage to the laser or present
an unnecessary risk of laser beam exposure to
yourself or bystanders.
If a door or window interlock is used, ensure
that it deactivates the laser properly. (Do not
disassemble major parts of the laser to test internal interlocks.) After deactivating the laser
and reclosing the door or window, check to be
sure that the laser will restart. Be sure to check
the interlocks in all locations where the laser is
used. (For some lasers, the function of the interlocks can be checked using an ohmmeter.)
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
5
Inspection and Preventive Maintenance System
If the laser is equipped with an emergency
“kill” switch, test this feature to be sure that it
deactivates the laser and that the laser will
subsequently restart.
1.21 Audible Signals. Operate the device to activate
any audible signals (e.g., laser emission, setting
change). Check for proper operation, and verify
that the signal can be heard in the environment
in which the laser will be used.
1.22 Labeling. Check that all placards, labels, and
instruction cards noted during acceptance testing are present and legible. Check to see that an
instruction manual is kept with the laser or is
readily available.
1.23 Accessories.
General. Verify that all necessary accessories are available and in good physical condition. Set up reusable accessories with
the laser to ensure compatibility and proper
functioning.
Checking all fibers or accessories during a
single inspection and preventive maintenance procedure is unnecessary as long as
accessories are routinely checked by the person(s) responsible for laser setup and operation. In addition, many of the accessories are
sterile and would require resterilization before use, making the laser potentially unavailable. Be sure to check with the person
responsible for scheduling the use of the laser
before beginning the procedure.
Fibers. For the test fiber and before each use,
examine the connector, cable, and tip of each
fiber to be used, as well as the fiber support,
for cleanliness and general physical condition.
Ensure that the connector properly seats into
the laser aperture in the laser cabinet. Examine the distal end of fibers to ensure that any
connecting mechanisms (e.g., threads) are in
proper working order.
If a fiber appears to be dirty or damaged,
remove it from service. If a fiber is reusable,
notify the person(s) responsible for fiber repair. The fiber should be repaired and/or
cleaned according to the manufacturer’s recommendations. Verify fiber performance.
Handpieces. Examine each handpiece component (e.g., body, tips, lenses) for cleanliness
and general physical condition. Examine
individually only those components that
are intended for removal during normal
6
use and storage. (Do not remove other parts
thatarepress-fitorattachedbyscrews,bolts,
or snap-rings.) If lenses are detachable, be
sure not to touch the lens surface; handle
lenses by the edges only. Consult the manufacturer’s recommendations for the procedures and cleaning agents to use to clean
lenses.
Ensure that major subcomponents of the
handpiece, when assembled, are secure. Ensure that the mechanisms used to connect the
handpiece(s) to the fiber are in good working
order and that they reliably secure each handpiece to the fiber.
Microscope micromanipulator. Examine the microscope micromanipulator for cleanliness
and general physical condition. Be sure to
handle it by the main body; do not hold it by
the joystick, and do not touch the reflecting
lenses in the body. Inspect micromanipulators
provided by both the laser manufacturer and
the laser accessory manufacturer.
Ensure that the reflecting surfaces and
lenses are intact and clean. Consult the
manufacturer’s recommendations for the procedures and cleaning agents to use to clean
reflecting surfaces and lenses.
Examine the joystick to ensure that it is
firmly attached and that it freely moves the
reflecting lens. If a finger rest is present,
ensure that it is firmly attached and properly
oriented.
If a zoom focus feature is present, be sure
that it turns easily and does not slip. Examine
each objective lens to ensure that it is intact
and clean. Do not touch the lens surface. Consult the manufacturer’s recommendations for
the procedures and cleaning agents to use to
clean the objective lenses. Carefully insert
each lens into the micromanipulator, and ensure that it fits snugly.
Inspect the mechanism used to attach the
micromanipulator to the microscope to ensure
that all parts are present and that it is in good
working order. Connect the micromanipulator to the microscope to check for a secure
connection.
Safety filters. Verify operation of safety filters
in the microscope and endoscope delivery
systems.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Frequency-Doubled Nd:YAG Surgical Lasers
clean area, maintaining the same distance. Adjust the exposure setting in increments of 0.1 sec
or the next longest duration, and activate the
laser at each setting. Continue this process until
you have tested all exposure settings, except
continuous, and have developed a series of
burns. Compare the burns to verify that progressively larger burns occurred as the exposure
duration increased.
1.24 Aiming Beam. Frequency-doubled Nd:YAG surgical lasers typically use an attenuated therapeutic beam as the aiming beam. Activate the
aiming beam (without the therapeutic beam),
and verify that it produces a round, uniformly
bright spot, with no halo.
1.25 Laser Aperture.
WARNING: Make this inspection with the laser
powered off. Remove and inspect the protective
window (e.g., blast shield) behind the laser aperture. It should be clean and undamaged; replace
if needed. There should be no visible dirt or
residue in the optical path of the laser aperture.
2.4
2. Quantitative tests
2.1
2.2
Grounding Resistance. Use an ohmmeter, electrical safety analyzer, or multimeter with good
resolution of fractional ohms to measure and
record the resistance between the grounding pin
on the power cord and exposed (unpainted and
not anodized) metal on the chassis, accessory
outlet, ground pins, and footswitch. We recommend a maximum of 0.5 Ω. (If the footswitch is
of low voltage, grounding is not required.)
If your laser power meter cannot be used for
this test, use the following alternative test
method. Set the laser to about 10 W and a 0.1 sec
exposure duration with the fiber, handpiece, or
micromanipulator attached, and verify that the
Repeat Pulse feature operates as expected by
moving the target material slightly between
each pulse. Be extremely careful to keep hands
out of the laser beam path. If the number or
duration between repeat pulses is adjustable,
test that setting changes made throughout the
range result in the expected performance.
Leakage Current.
WARNING: Do not reverse power conductors
for this or any other test. Improper attachment of
conductors may damage the laser.
With the laser attached to a grounded powerdistribution system, measure the leakage current between the chassis and ground with the
unit grounded and ungrounded. The leakage current on the chassis should not exceed 300 µA; in
no case should it exceed 500 µA. Where it is
greater than 300 µA, ensure that appropriate
grounding is present.
2.3
Exposure Duration. Some laser power meters
can measure pulse duration. If the power meter
can react to pulse duration (this is the preferred
circumstance), test the laser at each setting.
However, if the laser power meter does not measure pulse duration, use the following less preferable alternative.
Place and secure the laser fiber, handpiece, or
micromanipulator with the aiming system focused on the target material (e.g., black Delrin
or a tongue depressor). With the laser set to
about 10 W and the exposure set at minimum
duration, activate the laser and create a burn.
Carefully move the target material to expose a
Repeat Pulse. If the unit includes a Repeat Pulse
feature, which repeats the pulse at a fixed or
adjustable rate, test this feature with the laser
set at the minimum, median, and maximum
Repeat Pulse settings, if adjustable. Some laser
power meters can react quickly enough to be
used to test this feature of the laser. If you are
using such a power meter, test the laser to be
sure that the correct power is repeatedly delivered over the correct time period.
2.5
Footswitch Exposure Control. Set the output
time for about 5 sec, activate the unit, and release the footswitch after about 1 sec. Verify that
the beam turns off when the footswitch is released.
2.10 Power Output. Select one delivery system (e.g.,
fiber, micromanipulator), and perform the
manufacturer’s recommended user calibration
procedure. Secure the delivery system at the
appropriate distance from the detector of the
laser power meter to meet spot-size requirements specified in the instructions for the meter.
(Do not focus the beam to a small spot on the
power meter. Some power meters require that
the unfocused or a defocused laser beam be projected into the power meter to cover the majority
of the absorber surface. If the laser beam is
focused on the receiver of such meters, the meter
may be damaged.)
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
7
Inspection and Preventive Maintenance System
WARNING: Accessing the unfocused laser
beam may require defeating internal interlocks.
Because of the heightened risk associated with an
unfocused, nondiverging laser beam, exercise
great care if the interlocks are to be defeated.
With the laser set at low (e.g., 10% of full
scale), medium (e.g., 50% of full scale), and maximum output, activate the laser for a sufficient
period to acquire acceptable readings. (Power
meters use different time constants to acquire an
acceptable reading, and you must know and meticulously follow them.) Compare the reading
with the power display of the laser; the measured
and displayed values should all be within 10% of
one another. In addition, compare the reading
obtained with the reading taken on incoming
acceptance testing, at the last preventive maintenance procedure, or after the last service procedure. If the laser includes a low-power (e.g.,
mW) feature, test it in a similar fashion with a
power meter of appropriate resolution in the
low-power range.
polarity. Also, lasers powered by three-phase electrical
systems may be damaged if proper electrical phase
connections are not made initially and maintained
thereafter. Thus, do not switch conductor connections
or wiring configurations for any tests, including leakage current measurement. Do not conduct electrical
leakage current tests with reversed-polarity wiring.
Also test the ability of the laser to deliver laser
energy as expected in all configurations and with all
provided laser accessories. In addition, perform the
following tests.
4.1
Areas of Use. Visit the area(s) in which the laser
is to be used and ensure that laser signs,
eyewear, and window coverings are available
and being used and that safety interlocks for
doors or windows, if present, are functioning
properly.
4.2
Casters/Mounts/Holders. Ensure that the assembly is stable and that the unit will not tip over
when pushed or when a caster is jammed on an
obstacle (e.g., a line cord, threshold), as may occur
during transport. If the device is designed to rest
on a shelf, ensure that it has nonslip legs or
supports.
4.3
Labeling. Examine the unit and note the presence, location, and content of all labels. Labeling
information is typically found in the laser’s Operator Manual.
4.4
Electrical Wiring Configuration. Ensure that
the branch circuits and the outlets for the laser
are properly wired and rated for use with the
laser. Examine the receptacles at each location
where the laser is to be used to ensure that the
proper electrical configuration (e.g., proper neutral and ground connections, proper phase rotation) has been installed. Connect the laser to
each receptacle and confirm that the laser operates properly, specifically confirming that motors are operating in the proper direction.
4.5
AC Plug. Verify that the plug is acceptable for
use with the maximum current and voltage
specifications for operating the laser. (Consult
National Electrical Manufacturers Association
[NEMA] configurations for general-purpose nonlocking and locking connectors if in doubt.)
4.6
Pulse Duration. Verify that progressive increases
in pulse duration throughout its range of adjustment result in progressively larger burns.
3. Preventive maintenance
Verify that all daily preventive maintenance procedures recommended by the manufacturer are carried
out.
3.1
Clean the exterior. Clean accessible optical components (e.g., blast shield, microscope lenses), if
necessary, using techniques and cleaning solutions recommended by the manufacturer.
3.2
Lubricate any motor, pump, fan, compressor, or
printer components as recommended by the
manufacturer.
3.3
Calibrate/adjust any components (e.g., printer)
according to the manufacturer’s recommendations. Only appropriately trained personnel
should attempt laser adjustments. Ensure that
all hoses and tubes are tight.
3.4
Replace filters as needed. Check all fluid levels
and supplement or replace fluids as needed.
4. Acceptance Testing
Conduct major inspection tests for this procedure
and the appropriate tests in the General Devices Procedure/Checklist 438.
WARNING: Lasers may be damaged by switching
between normal and reverse polarity while the device is
on. If reverse-polarity leakage current measurements
are made, turn off the unit being tested before switching
8
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Frequency-Doubled Nd:YAG Surgical Lasers
4.7
4.8
4.9
Repeat Pulse. If the unit includes a Repeat Pulse
feature, test this feature as described in Item 2.4,
but over the full range of available settings.
Power Range. Using the technique described in
Item 2.10, test the power output accuracy at
several low, medium, and high settings.
Laser Delivery System Calibration. Use the
manufacturer’s recommended calibration procedure to test each new reusable delivery system
(e.g., fiber, handpiece) that the manufacturer
indicates can be acceptably calibrated using
these procedures. Note the fiber transmission for
each delivery system tested if this information is
provided by the laser. Or, you can calculate it
using the following formula:
% Transmission =
Delivered power
× 100%
Power entering the fiber
Delivery systems with less than the manufacturer-recommended transmission (typically
>85%) should be returned to the manufacturer.
Before returning to use
Be sure to return controls to their starting position
and place a Caution tag in a prominent position so that
the next user will be careful to verify control settings,
setup, and function before using the unit.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
9
Procedure/Checklist 438-0595
General Devices
Commonly Used In: Patient and nonpatient areas
Risk Level and Inspection intervals depend on device and circumstances
Type
Interval
Time Required
Major
months
.
hours
Minor
months
.
hours
Overview
This procedure provides guidance for inspection of any
device for which no specific procedure is applicable; it
also provides more detailed instructions for some tasks
commonly encountered in other procedures, along with
general acceptance tests for all devices. It can be used
as is for many simpler devices. Other devices will
require additional performance checks derived from
manufacturer-supplied information and the clinical
engineer’s or technician’s understanding of the device
and its clinical application.
Test apparatus and supplies
Leakage current meter or electrical safety analyzer
Ground resistance ohmmeter with a resolution of
about 0.1 Ω to around 0.5 Ω
Hydrometer
it, even if it entails doing part of one test early and the
rest of it later. However, do not check the Pass or Fail
column until the item has been completed. To the
extent possible, perform preventive maintenance
tasks first; the inspection will reveal any deficiencies
that may have been introduced by improper or inadequate maintenance. If the inspection indicates the
need for maintenance, reconfirm the functioning and
accuracy of the affected portions of the device following
the repair.
Before beginning any inspection, carefully read this
procedure and the manufacturer’s instruction and
service manuals; be sure that you understand how to
operate the equipment, the significance of each control
and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive
maintenance procedures are recommended by the
manufacturer. Skip items that are not relevant to the
device being inspected. Modify or add items if needed.
Special precautions
If there is evidence of blood or body fluid contamination, submit the device for cleaning and decontamination before inspecting it.
1. Qualitative tests
1.1
Chassis/Housing. Examine the exterior of the
unit for cleanliness and general physical condition. Ensure that plastic housings are intact, that
all assembly hardware (e.g., screws, fasteners) is
present and tight, and that there are no signs of
spilled liquids (e.g., stains, dried patches), physical damage, or other serious abuse.
1.2
Mount/Fasteners. If the device is mounted on
the wall or on a stand, IV pole, or cart, examine
the condition of the mount. Verify that the
See the article on IPM Safety, behind the Guidance
Tab of this binder, for additional precautions and
guidelines.
Procedure
Do not feel constrained to follow the order of items
in this or the device-specific procedures and checklists.
If a different order is more convenient, feel free to adopt
095674
438-0595
A NONPROFIT AGENCY
5200 Butler Pike, Plymouth Meeting, PA 19462-1298, USA
Telephone +1 (610) 825-6000 ● Fax +1 (610) 834-1275
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Inspection and Preventive Maintenance System
and that the clinical engineering (or other appropriate) department should be notified when a
fuse blows so that it can investigate the cause
and provide another spare fuse.
mounting apparatus is secure and that all hardware is firmly in place. Check for weld cracks.
Ensure that the assembly is stable.
1.3
1.4
Casters/Brakes. If the device moves on casters,
check their condition. Check that the casters roll
and swivel freely. Check the operation of brakes
and swivel locks. Conductivity checks, if necessary, are generally conducted as part of a check
of all furniture or devices within an area (see
Conductive Furniture and Floors Procedure/Form 441).
AC Plug/Receptacles. Examine the AC power
plug for damage. Attempt to wiggle the blades to
determine if they are secure. Shake nonmolded
plugs and listen for rattles that could indicate
loose screws. If damage is suspected, open the
plug and inspect it.
If the device has electrical accessory outlets,
inspect them for damage and insert an AC plug
into each to check that it is held firmly. If the
outlets are used for critical devices (e.g., outlets
on a resuscitation cart) or devices are plugged
and unplugged frequently, consider more extensive testing. Use a tension tester to measure the
tension of each contact. With the device plugged
in, use an outlet test fixture to verify that the
accessory outlet is energized and correctly wired.
See Electrical Receptacles Procedure/Form 437
for more information.
1.5
Line Cord. Inspect all line cords, including the
battery charger line cord, for signs of damage or
inappropriate repairs (e.g., taped sections). If replacement is necessary, be sure to wire the new
power cord or plug with the correct polarity. (Reversed hot and neutral wiring may pose a hazard
to service personnel since the on/off switch may not
open the hot line in the off position.)
1.6
Strain Reliefs. Examine the strain reliefs at
both ends of the line cord. Be sure that they hold
the cord securely.
1.7
Circuit Breaker/Fuse. If the device has a
switch-type circuit breaker, check that it moves
freely. If the device is protected by an external
fuse, check its current rating and type against
that marked on the chassis.
If there is a spare fuse holder, verify that a
fuse of the same rating and type is provided. If
the spare fuse is missing, advise clinical personnel that a spare fuse is provided primarily to
expedite a rapid return of the device to operation
2
1.8
Tubes/Hoses. Check the condition of all tubing
and hoses. Check that they are correctly connected and positioned so they will not kink, be
caught by moving parts, interfere with the operator, or be damaged during operation.
1.9
Cables. Inspect any cables (e.g., sensor, electrode, remote control) and their strain reliefs for
general condition. Carefully examine cables to
detect breaks in the insulation and to ensure
that they are securely gripped in the connectors
at each end, which will prevent rotation or other
strain. Where appropriate, verify that there are
no intermittent faults by flexing electrical cables
near each end and looking for erratic operation
or by using an ohmmeter.
1.10 Fittings/Connectors. Examine all gas and liquid fittings and connectors, as well as all electrical cable connectors, for general condition.
Electrical contacts should be straight, clean, and
bright. Gas and liquid fittings should be tight
and should not leak. Cracked or brittle O-rings
should be replaced. If keyed connectors are used
(e.g., pin-indexed gas connectors), ensure that no
pins are missing and that the keying is correct.
Keying pins should be securely seated in “blind”
holes so that they cannot be forced in farther.
1.11 Electrodes/Transducers. Verify that all electrodes, transducers, and probes are available,
including spares and optional units and — especially for emergency and resuscitation devices —
an adequate supply of disposables. Check that
appropriate transducers and probes are being
used; the use of incorrect probes (e.g., those from
another manufacturer) has caused patient injury and erroneous results. Examine the physical condition of reusable units.
1.12 Filters. Check the condition of all liquid and
gas (air) filters. Clean or replace as appropriate, and indicate this on Line 3.1 or 3.4 of the
inspection form.
1.13 Controls/Switches. Before moving any controls
and alarm limits, check their positions. If any of
them appear inordinate (e.g., a gain control at
maximum, alarm limits at the ends of their
range), consider the possibility of inappropriate
clinical use or incipient device failure. Record
the settings of those controls that should be
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
General Devices
returned to their original positions following the
inspection.
Check the condition of the battery charger, and
verify that battery charge indicators function.
Check parameters that may be set on “hidden”
user or service menus, including special modes
and alarm on/off, volume, and default values.
1.18 Indicators/Displays. During the course of the
inspection, verify the operation of any lights,
indicators, meters, gauges, and visual displays on
the unit and charger. Ensure that all segments of
a digital display function. Observe a signal on a
waveform display, and note any problems (e.g.,
distortion, poor focus, 60 Hz interference).
Examine all controls and switches for physical
condition, secure mounting, and correct motion.
Check that control knobs have not slipped on
their shafts. If a control has fixed-limit stops,
check for proper alignment, as well as positive
stopping. Check membrane switches for membrane damage (e.g., from fingernails, pens). During the course of the inspection, ensure that each
control and switch performs its proper function.
1.14 Heater. Examine the heater for damage (e.g.,
corrosion of its sheath, deteriorated insulation).
To the extent possible, operate the heater to
verify that its controls function properly (e.g.,
that a variable temperature control does, in fact,
control heater power).
1.15 Motor/Pump/Fan/Compressor. Check the physical condition and proper operation of these components. Check mechanical alignment and proper
adjustment of any pulleys, gears, belts, chains, etc.
Look for any signs of improper or excessive wear,
such as metal filings. Lubricate if required, and
note this on Line 3.2 of the form. (However, do not
check the line until all lubrication is completed.)
1.16 Fluid Levels. Check all fluid levels, including
those in lead-acid batteries.
1.17 Battery/Charger. Inspect the physical condition of all batteries and battery connectors if
readily accessible. Disposable carbon zinc batteries may leak and must be inspected. We are
not aware of significant leakage problems with
most other battery types.
Check operation of battery-maintained memory and battery-operated power-loss alarms, if so
equipped.
Operate the unit on battery power for several
minutes to verify that the battery is charged and
can hold a charge. Activate the battery test function (if so equipped), or measure the output voltage with the unit on to assess battery capacity.
(The inspection can be carried out on battery
power to help confirm adequate battery capacity.) Measure the specific gravity of lead-acid
batteries. When it is necessary to replace a battery, label it with the date.
1.19 Calibration/Self-Test. Verify that the calibration function operates. (Where a quantitative
check is required, add it to the quantitative section.) Activate self-test or service-mode functions
that allow simple performance verification.
1.20 Alarms/Interlocks. Induce alarm conditions to
activate audible and visual alarms. Check that
all associated interlocks or features function (e.g.,
an infusion pump initiates KVO rate upon
alarm). If the device has an alarm-silence feature,
check the method of reset (i.e., manual or automatic) against the manufacturer’s specifications.
Verify that alarms are loud, distinctive,
and/or bright enough to be noticed in the environment in which the device will normally be
used. If a remote alarm-indicator is required,
verify that it is available and functioning. Audible alarm-volume controls should not allow the
alarm to be turned off or lowered to an indiscernible volume.
Check alarm parameters that may be set on
hidden menus (see Item 1.13).
If inspections repeatedly reveal that alarms
have been turned off or silenced or that the
volume has been adjusted too low, inappropriate
use is indicated, and user in-service training is
required.
1.21 Audible Signals. Operate the device to activate
any audible signals (e.g., QRS beeper). Check for
proper operation of the volume control, and verify that the signal can be easily heard in the area
in which the device will be used.
1.22 Labeling. Check that all necessary placards, labels, conversion charts, and instruction cards
are present, legible, and easy to understand.
1.23 Accessories. Verify that all necessary accessories are available and in good condition. A copy
of the instruction manual should be readily
available to the user.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
3
Inspection and Preventive Maintenance System
connecting cord. The instrument is not usually
grounded. Assuming that the device has met
incoming inspection requirements, grounding is
not required.
2. Quantitative tests
Most quantitative tests are device specific. Appropriate tests are listed in the individual procedures or
should be derived from device specifications and an
understanding of the device’s clinical application and
design. However, the following electrical safety tests
are common to all line-powered devices. (Refer to the
article on Electrical Safety, behind the Guidance Tab
of this binder, for the rationale, recommended intervals, and additional discussion of electrical safety testing requirements.)
2.1
Ground Resistance. Using an ohmmeter, electrical safety analyzer, or multimeter with good
resolution of fractional ohms, measure and record the resistance between the grounding pin of
the power cord and exposed metal on the chassis.
Conductive portions of the chassis or housing
that may become energized must be grounded.
Metal trim, nameplates, and handles that are
unlikely to be exposed to current-carrying components of the device need not be grounded.
Since poor test lead contact can increase
ground resistance measurements, ensure that
both test leads are in firm contact with a portion
of the ground prong or chassis that is clean and
shiny (e.g., unpainted and not anodized). Also
check that the ohmmeter reads zero when the
leads are shorted together.
Verify that all modules or cable-connected
parts of a system are grounded. If the device has
an accessory outlet, check its grounding to the
main power cord.
Although a stable grounding resistance as
high as 0.5 Ω is acceptable, an increase in
grounding resistance from one inspection to another may indicate a loosening connection. Open
the unit or plug, look for the cause of the increase
(e.g., a loose or corroded connection), and repair
it.
Double-insulated devices may or may not be
grounded. ECRI believes that either design is
satisfactory. Do not measure grounding resistance of double-insulated devices unless designed
to be grounded; just indicate “DI” on the inspection form. Some double-insulated devices may
have a three-prong plug, but the grounding prong
may be unconnected; this poses no safety risk.
Some devices are powered (or recharged) by
an AC adapter that plugs into a wall outlet and
carries a low voltage to the instrument by a
4
2.2
Chassis Leakage Current. With the polarity of
the power line normal and the equipment ground
wire disconnected, measure chassis leakage current with the device operating in all normal
modes, including on, standby, and off. If the unit
has heating and cooling modes, set the thermostats so that each operates while readings are
taken. Record the maximum leakage current; it
should not exceed 300 µA for equipment used in
patient care areas or 500 µA for devices in nonpatient care locations (e.g., nurses’ station, clinical laboratory).
The measurements should be made with all
accessories that are normally powered from the
same line cord connected and turned on. This
applies to devices that are plugged into accessory
outlets on the device and to devices that are
plugged into a multiple-outlet strip (“Waber
strip”) so that the devices are grounded through
a single line or extension cord.
Leakage current must be measured with the
device powered by a conventional (grounded)
power system, even if it is normally used in an
area with isolated power. If the device has a
special plug (e.g., explosion proof), a corresponding adapter is required.
During routine inspections, it is necessary to
test leakage current only in the correct-polarity,
ungrounded mode. If testing in the reversed-polarity mode, remember that some devices, especially those incorporating a microprocessor,
motor, or compressor, may be damaged by
switching polarity while the device is on. To
avoid damage, turn off the unit until the motor
stops or for at least 10 sec before switching
polarity. Routine lead leakage current measurements are also not required.
Interference from stray radio-frequency (RF)
fields or currents produced by some high-frequency devices (e.g., electrosurgical units, diathermy units) may cause erroneous leakage
current readings. Two signs of such interference
are readings obtained with the leakage current
probe held near (but not contacting) the device
and needle deflection that does not change accordingly as the meter scales are changed. In the
event of interference, try a different leakage
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
General Devices
current meter, place a small capacitor (0.1 µf)
across the leakage current meter input terminals, or measure leakage currents with the RF
generator off.
Inspect/clean interior. Opening the housing for
internal cleaning is unnecessary and not recommended for many devices. Where appropriate (e.g., units with ventilation fans
without air filters, units with evidence of
spilled fluids that may have entered the unit,
some units with high DC voltages), inspect the
interior of the unit and look for accumulations
of dirt, dust, spilled fluids, foreign objects,
excessive lubrication, and signs of mechanical
wear. Clean as necessary. Refer to the Preventive Maintenance and Cleaning article, behind the Guidance Tab of this binder, for
guidelines on the selection of cleaning solvents and appropriate techniques.
Though confirmation of grounding integrity
provides reasonable assurance of safety for devices with permanent redundant grounding
(e.g., a bedside monitor grounded through the
line cord and its central station connection),
NFPA 99 calls for measurement of chassis leakage current with the redundant ground intact.
2.2.
(Alternative) Ground Voltage (For Installed Equipment). Chassis leakage current of permanently
wired equipment cannot be readily measured after
installation is completed. Though confirmation of
grounding integrity provides reasonable assurance of safety, NFPA 99 calls for voltage measurements for installed devices in the patient vicinity.
Using a voltmeter, electrical safety analyzer, or
multimeter with appropriate resolution, measure
and record the voltage between a reference
grounding point (e.g., the grounding pin of an
electrical receptacle or some other known ground)
and exposed (i.e., unpainted and not anodized)
metal on the chassis. A voltage reading of 500 mV
is acceptable for general care areas, and 40 mV is
acceptable in critical care areas.
3.2
Lubricate. Lubricate mechanical components
such as motors, bearings, chains, wheels, hinges,
latches, etc. that have friction points. Excessive
or inappropriate lubrication can cause damage;
refer to the manufacturer’s literature for lubrication requirements. Refer to the Preventive
Maintenance and Cleaning article, behind the
Guidance Tab of this binder, for additional information on lubrication.
3.3
Calibrate/Adjust.
Electrical components. Perform calibration and
adjustments as recommended by the manufacturer or indicated by inspection results.
3. Preventive maintenance
Mechanical components. Verify the integrity
and proper operation of all mechanical components and hardware. Inspect for loose
and worn components, and tighten as necessary. Align and tighten external control
knobs, switches, and indicators. Ensure the
proper operation of mechanical brakes and
interlocks.
Most preventive maintenance tasks are device specific. Appropriate tasks are called out in the individual
procedures or should be derived from device specifications and an understanding of the device’s clinical
application and design. However, the following items
should be considered and incorporated as appropriate.
3.1
Clean.
Exterior and accessories. Cleaning the exterior
of the equipment is normally the responsibility of the user; however, some users grow
complacent or accustomed to the appearance
of the equipment. Thus, a periodic extra effort
may be required to maintain the appearance
and prevent operational problems. Refer to
the article on Preventive Maintenance and
Cleaning, behind the Guidance Tab of this
binder, for guidelines on the appropriate
cleaning solvents and techniques.
Clean filters as appropriate (most filters are
disposable and should be replaced as needed).
Flush fluid lines and reservoirs as necessary.
3.4
Replace. Replace liquid, gas, and ventilation
(air) filters; deteriorating, cracked, or dry-rotted
tubing; motor brushes; missing spare fuses; Orings; and other components as needed or at
intervals recommended by the manufacturer.
4. Acceptance tests
Upon initial receipt of a device or following repair,
make a thorough visual inspection. Add the following
supplemental items to the qualitative and quantitative
tests that would be conducted during a major inspection. In addition, conduct appropriate specific tests as
indicated in the individual inspection procedures and
as required to verify purchase order and manufacturer
specifications.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
5
Inspection and Preventive Maintenance System
A.1 Qualitative acceptance tests
A.1.1 Chassis/Housing. Check for shipping damage;
report any damage to the manufacturer, shipper, or service organization, and arrange for
repair or replacement.
Check that the unit is suitably constructed to
withstand normal hospital use and abuse. For
instance, a unit with venting on the top of the
housing or poorly protected or sealed controls
and indicators may be prone to fluid entry. (Such
design deficiencies should usually be recognized
during prepurchase evaluation. However, if any
are evident, discuss corrective action with the
manufacturer. If not correctable, warn users or
take other preventive measures.)
A.1.2 Mount. Ensure that the assembly and weight
distribution is stable and that the unit will not
tip over when pushed or when a caster is
jammed on an obstacle (e.g., line cord threshold), as may occur during transport. If the device is designed to rest on a shelf, ensure that
it has nonslip legs or supports.
Inspect wall-mounted devices at the time of
installation to verify that the mounting technique
is appropriate for the weight of the device. Attaching the unit to wallboard (e.g., with Molly bolts)
is unacceptable except for very light devices. Generally, objects should not be mounted over a patient. The device should be mounted in a position
and height where it can be easily viewed, adjusted, and used by clinical personnel and where
it will not be bumped or hinder access to the
patient for routine or emergency care. If the unit
has a heating element, keep hoses, wires, and
cables away from the unit and place the unit so
that patients, staff, and visitors are protected
against contact with hot surfaces.
A.1.3 Casters/Brakes. Verify that the correct casters
have been supplied with the unit (e.g., size,
correct swivel). (ECRI recommends 5 in [12.7
cm] diameter casters for mobile devices to reduce shock to the unit and to minimize the effort
required to roll the unit across elevator thresholds and other uneven surfaces.) Verify brake
operation.
A.1.4 AC Plug/Receptacles. Verify that the plug is
Hospital Grade (identifiable by a green dot
and/or labeling). (A plug of good quality, even if
not Hospital Grade, may be left on a device that
is plugged and unplugged infrequently. Rightangle plugs are unacceptable for devices that are
6
moved frequently. A good quality two-prong
plug is acceptable for double-insulated devices.)
If a special plug is required (e.g., explosion
proof), it should be of suitable type and quality.
Replace the plug or have the supplier replace it
if it is not Hospital Grade or otherwise suitable.
Hospital Grade molded plugs are acceptable.
If the device has electrical accessory outlets,
use an outlet test fixture, and with the device
plugged in, verify that the accessory outlet is
energized and correctly wired.
A.1.5 Line Cord. Ensure that the line cord is long
enough for the unit’s intended application; an
extension cord should not be required. (A length
of 10 ft [3 m] is suitable for most applications,
although 18 ft [5.5 m] has been suggested for
operating room equipment.)
The cord should be of suitable quality and
current-carrying capacity. Hard Service (SO,
ST, or STO), Junior Hard Service (SJO, SJT, or
SJTO), or an equivalent-quality cord should be
used.
If the line cord is operator detachable, affix
the cord to the unit so that it cannot be removed
by the operator, or at least label the cord prominently (e.g., 120 V), especially for devices that
are used in the vicinity of monitors that use
patient leads. (Electrode lead wires have been
inserted into line-cord connectors; see Health
Devices 1993 May-Jun; 22:301-3.)
A.1.7 Circuit Breaker/Fuse. If the device is protected
by an external fuse, verify that the fuse type is
labeled and that all fuses and spares are the
proper current rating and type. If the value and
type are not labeled, check the manual for the
proper current rating and type and permanently mark this information on the unit housing near the fuse holder. If no spare fuse is
provided, consider attaching a fuse clip and
spare fuse, particularly for high-risk devices.
Especially for critical or life-support devices,
verify that accessory outlets have independent
overcurrent protection (fuse or circuit breaker)
so that a short in a device plugged into the
accessory outlet or an accessory overload will
not disable the primary device. If this is not
available, then consider labeling the primary
device to clearly indicate where the unit’s fuse
or circuit breaker is located, and/or install a
fused Hospital Grade (or similar quality) plug
on any commonly used accessories that are not
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
General Devices
already provided with suitable overcurrent
protection.
A.1.10 Fittings/Connectors. Verify that other hospital
equipment or systems to which the device is to be
connected have the matching connectors. Devices
that connect to the central piped medical gas
system should have the matching DISS or quickconnect fitting for the appropriate gas. Verify
that suitable connectors are supplied with the
device so that adapters are not required.
A.1.13 Controls/Switches. Verify that software setup
parameters accessible through hidden or service
menus are correctly set for the appropriate application and are consistent for all units. Instruction
and service manuals may contain instructions
regarding such modes. If they do not, contact the
manufacturer. Discuss appropriate settings with
the department head and users. If alarm capabilities are included, see Item A.1.20.
A.1.17 Battery/Charger. To determine operating
time, charge the battery overnight (or install
fresh batteries), then operate the device on battery power with all commonly used functions
activated. For critical care monitors and therapeutic devices, it may be desirable to disconnect
the battery and determine if the device still
operates on line power.
A.1.20 Alarms. Verify that critical alarms cannot be
turned off, silenced, or defeated without adequate warning to the operator or automatic
alarm reactivation after a short delay (see
Health Devices 1987 Feb; 16:39-44 and 1989
Dec; 18:426-7.) Such deficiencies should usually
be recognized during prepurchase evaluation.
However, if any are found, review the justification for purchasing this device and discuss corrective action with the manufacturer. (Alarm
features may be optional or programmable.) If
no remedy is available, a user training program
should be instituted to reduce the risk of incorrect use. A warning label on the device or a
poster in the area of use may be appropriate.
A.1.23 Accessories. Verify that all necessary features
and accessories (e.g., transducers) have been
supplied with the unit. At least one copy each
(two are generally preferred) of the instruction
and service manuals, including schematics,
should be shipped with the unit and filed in the
central equipment file. A copy of the instruction
manual should be kept with the unit and read
by all operators before the device is put in use.
A.2 Quantitative acceptance tests
A.2.2 Chassis Leakage Current.
Note: Some devices (especially devices incorporating a microprocessor, motor, or compressor)
may be damaged by switching polarity while the
device is on. If you perform reverse polarity testing, turn off the unit until the motor stops or for at
least 10 sec before switching polarity.
Measure chassis leakage current as described in Item 2.2. Reversed polarity testing
is not required, although some hospitals perform this measurement; it may be advisable on
a device of questionable quality or on devices
used in the home.
Be alert for leakage current of the device in
the off mode that is greater than about 30 µA
and is greater than or equal to the leakage
current in the on mode. Although this may be
normal and proper for the device, it may indicate that the on/off switch is incorrectly wired
in the neutral (instead of the hot) line. Incorrect switch wiring poses a risk to service personnel who believe that the power is
disconnected when the switch is off. Check the
wiring, or contact the manufacturer.
Inspect AC adapters used to power (or recharge) certain devices for UL (or other testing
laboratory) listing and to verify that it is labeled
to identify the device with which it is to be used.
ECRI recommends testing of adapters, particularly those that are not listed, by measuring the
leakage current from each secondary (low voltage) connection to ground. The leakage current
should not exceed the limits for the device chassis leakage current to ground (300 µA in patient
care areas, 500 µA in nonpatient care areas).
See the article on Electrical Safety, behind the
Guidance Tab of this binder, for further details
and a discussion of the use of these devices in
hospitals.
Measure chassis leakage current of permanently installed (hardwired) equipment during
installation only. Before connecting the equipment to ground, measure the leakage current
from chassis to ground. The ungrounded leakage current should be less than 5 mA.
■ ■ ■
Experience has not demonstrated the need for lead
leakage and input isolation testing (Items 4.1 through
4.3) on a routine basis. NFPA 99 specifically excludes
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
7
Inspection and Preventive Maintenance System
the need for periodic lead leakage current testing. We
recommend that these tests be performed only during
acceptance testing or following input circuitry repairs.
4.1
Lead-to-Ground Leakage Current. Measure
leakage current from patient leads (or other applied parts, such as probes) to ground on any
electrical device that has leads that are intentionally attached to or held against the patient
or on any device that has a conductive invasive
connection. Perform the test with the device on
and with the ground wire intact and open, in all
normal operating modes.
If the device is of nonisolated design and is not
intended to be connected to the heart by a conductive lead or fluid-filled catheter, leakage current should be 100 µA or less, measured from all
the leads connected together to ground.
If the device has isolated patient connections
(see the article on Electrical Safety, behind the
Guidance Tab of this binder, for a discussion of
isolation), it should be labeled “Isolated” on the
front panel by the manufacturer or have the IEC
symbol signifying isolation (a heart within a
square). These units are designed to be safe for
use when connected to a conductive lead or fluidfilled catheter that is within, or in contact with,
the heart. Normally, only one lead of the device
will be in contact with the heart (or create a
conductive path to the heart); individually test
each lead that may be connected to confirm that
leakage current to ground is 10 µA or less with
the unit ground intact and 50 µA or less with the
ground open (the open ground limit is a change
introduced in the 1990 version of NFPA 99).
If the device housing is not grounded, measure
leakage current from each lead to the housing.
4.2
Interlead Leakage Current. Measure the leakage
current between leads on devices with multiple
patient leads or contacts. Measure between each
lead (except ground). Perform the test with the
device on and with the ground wire both intact and
open, in all normal operating modes. For nonisolated connections, the leakage current should not
exceed 50 µA (grounded or ungrounded). For isolated input connections, the leakage current
should not exceed 10 µA with the device ground
intact or 50 µA with the ground open.
4.3
Lead Input Isolation. This test should be performed only during acceptance testing or following input circuit repairs.
8
WARNING: Testing input isolation requires
the use of a line voltage source. Perform this test
only with an electrical safety analyzer or other
setup that allows safe application of the voltage
to the patient leads. Be sure that a current-limiting resistor is included in the setup, but continue
to be careful not to contact any exposed leads,
since it is still possible to receive a shock.
Apply 120 VAC (line voltage applied through
a current-limiting resistor) to each isolated patient connection individually, and measure the
resulting current (sink current) with the unit
turned on and operating and the power cord
grounding connector intact. The current should
not exceed 50 µA at the patient end of the cable.
Before returning to use
Ensure that all controls are set properly. Set alarms
loud enough to attract attention in the area in which
the device will be used. Other controls should be in
their normal pre-use positions.
Attach a Caution tag in a prominent position on
life-support equipment or any other device where the
user must be aware that control settings may have
been changed.
With battery-powered devices, either recharge the
battery or equip the device with fresh batteries. When
a new battery is installed, label it with the date.
General Devices Checklist Template
The checklist associated with this procedure is a
template that can be used to develop checklists and
accompanying procedures for any device. The General
Devices procedure is the foundation for the template
and will provide many of the IPM ingredients common
to line- or battery-powered devices. The first step in
using the template is to place a check mark in the
Major column for each item that applies to the device.
The second step is to determine the specific IPM
elements that will ensure the safe and effective operation of the device. This task focuses on identifying
unique accessories and any parameters requiring
measurement (e.g., temperature, pressure, flow). At
this point, the author of a new IPM procedure must
specify performance criteria, methods for assessing
the criteria, and the frequency for conducting the
major and, if needed, minor IPM procedures. IPM
Task ManagerTM, the software component of the IPM
System, can then be used to prepare a final procedure
and device-specific checklist.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Procedure/Checklist 430-0595
Heart-Lung Bypass Units
Used For:
Heart-Lung Bypass Units [11-969]
Pumps, Extracorporeal Perfusion [13-203]
Also Called: Cardiopulmonary perfusion equipment, heart-lung machines, heart-lung pumps, bypass machines
Commonly Used In: Operating rooms for cardiac surgery
Risk Level: ECRI Recommended, High; Hospital Assessment,
Type
ECRI-Recommended
Interval
Interval Used
By Hospital
Major
*
months
.
hours
Minor
NA
months
.
hours
Time Required
* Heart-lung machines and accessories should be inspected after every 100 hours of use or quarterly, whichever
comes first, barring specific hospital circumstances or manufacturer recommendations to the contrary. The
perfusionist should check pump occlusion before each procedure.
Overview
Cardiopulmonary perfusion equipment, commonly referred to as heart-lung machines, provides cardiopulmonary support for a patient during open-heart
surgery, permitting cardiovascular surgeons to isolate
the heart from the circulatory system to perform cardiac repairs or valve replacements. The great vessels
returning to (venae cavae) and leaving (aorta) the
heart are cannulated, allowing an external circuit to
provide circulation and oxygenation while the heart
and lungs are bypassed. (For more detailed information on the procedure, see: Reed CC, Stafford T. Cardiopulmonary bypass. 2nd ed. Houston: Texas Medical
Press, 1985.)
Cardiopulmonary perfusion systems usually consist
of blood pumps; control and monitoring devices; and a
disposable oxygenator, cardiotomy reservoir, tubing
set, and filters.
Blood pumps. Blood pumps propel blood through the
extracorporeal circuit and return extravascular blood to
the circulating volume using suction (e.g., autotransfusion, intracardiac suction). The arterial pump propels
blood through the oxygenator to the patient and may
009070
430-0595
A NONPROFIT AGENCY
operate at up to 6 L/min, depending on patient requirements. A backup arterial pump is usually provided.
Venous blood normally requires no pumping because
it flows by means of gravity to a reservoir. Membrane
oxygenators (the most common variety; bubble oxygenators are rarely used today) require that the arterial pump be positioned between the venous reservoir
and the oxygenator and that it actively pump blood
from the reservoir to the oxygenator. Because continuous operation is imperative, the arterial pump must be
connected to a battery pack, as well as to the emergency power system. As an additional precaution, a
hand crank should be kept with each pump in the event
of a power failure.
Control and monitoring devices. A number of accessories are needed for controlling and monitoring perfusion. Blood temperature in the extracorporeal
circuit is regulated to produce hypothermia or normothermia. Oxygenators typically incorporate a heat
exchanger, and water must be delivered to the exchanger at a specified temperature. A mixer valve
regulates hot and cold water delivered to the heat
exchanger; it usually has a thermometer and water
pressure relief valves to prevent overpressurizing the
5200 Butler Pike, Plymouth Meeting, PA 19462-1298, USA
Telephone +1 (610) 825-6000 ● Fax +1 (610) 834-1275
●
E-mail [email protected]
Inspection and Preventive Maintenance System
exchanger part of the oxygenator. A separate electrically powered heater/cooler may be used instead of a
mixer to provide temperature-regulated water to the
heat exchanger.
Oxygen is delivered to venous blood from tanks or a
central oxygen supply. A flowmeter and bacteriologic
filter are usually incorporated in the oxygen circuit.
Blood oxygen and carbon dioxide concentrations are
usually monitored by blood gas determinations from
drawn samples, but they may be monitored using an
in-line differential oxygen monitor. An oxygen saturation meter may be used to assess oxygenation. Other
devices may be used to provide blood chemistry information throughout the perfusion.
Temperature monitors may be used, with probes
placed at various points on the patient or in the extracorporeal blood circuit.
Level detectors may be used to monitor the level of
blood in the reservoirs. These detectors are often
equipped with audible and visual alarms and may also
stop the arterial blood pump to avoid pumping air into
the patient in the event of a low blood level in a
reservoir or to avoid too much blood volume in the
extracorporeal circuit in the event of a high blood level.
A special valve may be incorporated in the arterial
tubing to prevent infusion of large amounts of air. Air
bubble detectors give audible and visual alarms and
may also stop the arterial blood pump if air is detected
in the arterial line.
Pressure monitors record left atrial, pulmonary artery, and arterial pressures. These monitors, which
may be included in the console, the drive pressure
transducers, or the monitors, may be slaved to other
pressure monitoring equipment.
Blood contact with foreign surfaces requires that the
coagulation (clotting) mechanism of the blood be controlled to a point where coagulation is inhibited, but in
a reversible manner. Heparin is the anticoagulant
used in perfusion, and its level must be monitored
throughout the perfusion to prevent clot formation or
overheparinization.
Oxygenator, cardiotomy reservoir, filters, and tubing set. These disposable components form the extracorporeal blood circuit. The perfusionist usually lays
out the circuit, which is made up as a sterile custom
pack by a manufacturer.
Blood taken from the venae cavae normally flows by
gravity (a venous clamp may be used to regulate flow)
to a venous reservoir and is then pumped through the
oxygenator. After leaving the oxygenator, blood flows
2
to the patient, usually after passing through a bloodline filter in the arterial line. A shunt around the
blood-line filter permits continued flow if a clogged
filter must be changed. Some perfusionists incorporate a filter in this shunt line as well, since releasing
clamps to change filters may cause unloading of the
filtrates.
Suction pumps recover blood at the surgical site and
return it to the circulating volume. Intracardiac suction returns extravascular blood to the cardiotomy
reservoir, where it is filtered and then drained or
pumped to the venous side of the oxygenator. Suction
for ventricular vents may also be controlled by suction
pumps. Blood from the cardiotomy reservoir may be
passed through an additional blood-line filter before
returning to the oxygenator.
Citations from Health Devices
Heart-lung bypass machines, 1973 Apr; 2:152.
Sarns air bubble detector system [Evaluation], 1981
Jan; 10:55.
Delta automatic shutoff valve [Evaluation], 1981 Jan;
10:62.
Improper bulb replacement causes Sarns model 7000
MDX heart-lung bypass pump failure [Hazard],
1987 Jun; 16:218-9.
Test apparatus and supplies
Ground resistance ohmmeter
Leakage current meter or electrical safety analyzer
Equipment for inspecting blood pressure monitors
and pressure transducers, as specified in Blood
Pressure Monitors, Invasive Procedure/Checklist
434 and Pressure Transducers Procedure/Checklist
435, respectively
Thermometer accurate to at least 0.5°C over a range
of 15° to 43°C (a temperature-monitoring device
made of a thermometer sealed into one leg of a Y or
T connector, such as is used for the inspection of
hypo/hyperthermia units, may also be used)
Stopwatch or watch with a second hand
Hydrometer
Oxygen flowmeter with 1 to 10 L/min range and 2%
accuracy
Graduated cylinder with at least 1 L capacity (a
fluid flowmeter with 0 to 10 L/min range and 5%
accuracy may be used)
Large bucket (5 L) for collecting fluid when checking
high flow settings
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Heart-Lung Bypass Units
that it is held firmly. If accessories are plugged
and unplugged often, consider a full inspection
of the receptacle.
Disposable supplies, such as tubing and assorted
fittings for connecting tubing and test equipment
Conductive lubricant, such as Dow #41 graphited oil
or the equivalent, for conductive casters
1.5
Line Cord. Inspect the cord for signs of damage.
If damaged, replace the entire cord, or if the
damage is near one end, cut out the defective
portion. Ensure that the line cord is of sufficient
length to preclude the use of extension cords. Be
sure to wire a new power cord or plug with the
same polarity as the old one. Also check line
cords of battery chargers.
1.6
Strain Reliefs. Examine the strain reliefs at
both ends of the line cord and all accessory cords.
Be sure that they hold the cord securely.
1.7
Circuit Breaker/Fuse. If the device has a
switch-type circuit breaker, check that it moves
freely. If the device is protected by an external
fuse, check its value and type against that
marked on the chassis, and ensure that a spare
is provided.
1.8
Tubes/Hoses. Check the condition of all tubing
and hoses in the water mixer. Be sure that they
are not cracked, kinked, or dirty. Check for
evidence of leaking.
1.9
Cables. Inspect the cables of the level sensor and
bubble detector and oxygen, temperature, and
pressure monitors, if so equipped, and their
strain reliefs for general condition. Examine
cables carefully to detect breaks in the insulation
and to ensure that they are gripped securely in
the connectors at each end to prevent rotation or
other strain.
Torque measurement device for checking pump (if
required)
Procedure
Before beginning an inspection, carefully read this
procedure and the manufacturer’s instruction and
service manuals; be sure that you understand how to
operate the equipment, the significance of each control
and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive
maintenance procedures or frequencies are recommended by the manufacturer.
Because some inspection items require multiple
data points and several pumps need to be checked,
enter additional data on the reverse side of the inspection form.
1. Qualitative tests
1.1
Chassis/Housing. Examine the exterior of the
unit for cleanliness and general physical condition. Be sure that plastic housings are intact,
that necessary assembly hardware is present
and tight, and that there are no signs of spilled
liquids or other serious abuse.
1.2
Mount/Fasteners. Examine each pump module
and any other accessories mounted to the cart or
console for security of attachment. Check the
integrity of all special mounting hardware for
oxygenators and cardiotomy reservoirs.
1.3
Casters/Brakes. If the device moves on casters,
check their condition. Look for accumulations of
lint and thread around the casters, and be sure
that they turn and swivel, as appropriate. Check
the operation of brakes and swivel locks, if the
unit is so equipped. Conductivity checks, where
appropriate, are usually done more effectively as
part of a check of all equipment and furniture of
an area.
1.4
AC Plug/Receptacles. Examine the AC power
plug for damage. Attempt to wiggle the blades
to determine that they are secure. Shake the
plug and listen for rattles that could indicate
loose screws. If any damage is suspected, open
the plug and inspect it.
If the device has electrical receptacles for accessories, insert an AC plug into each, and check
1.10 Fittings/Connectors. Check the general condition of all gas and liquid fittings and connectors,
such as those on the oxygen flowmeter and water
mixer, as well as all electrical cable connectors.
Electrical contact pins or surfaces should be
straight, clean, and bright.
1.11 Electrodes/Transducers. Confirm that necessary electrodes and/or transducers are on hand,
and check their physical condition.
1.13 Controls/Switches. Before moving any controls
and alarm limits, check their positions. If any of
them appear inordinate, consider the possibility
of inappropriate clinical use or of incipient device
failure. Record the settings of those controls
that should be returned to their original positions following the inspection.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
3
Inspection and Preventive Maintenance System
indicators, meters, gauges, and visual displays on
the unit and the charger, if so equipped. Be sure
that all segments of a digital display function.
Examine all controls and switches for physical
condition, secure mounting, and correct motion.
Where a control should operate against fixedlimit stops, check for proper alignment, as well
as positive stopping. Check membrane switches
for membrane damage (e.g., from fingernails,
pens). During the course of the inspection, be
sure to check that each control and switch performs its proper function.
1.14 Heater/Mixer. If the unit uses a heater for temperature control, examine the heater for physical
condition (e.g., verify that a variable temperature control does, in fact, determine the amount
of heating; verify that on/off controls work).
If the unit uses a mixer valve for temperature
control, examine the valve for proper operation.
If a high-temperature cutoff is incorporated in
the valve, check its function. Be sure that hot
and cold connectors are adequately placarded to
prevent cross connection.
1.15 Motors/Pumps. Confirm the physical condition
and proper operation of all pump heads and their
associated motors and transmissions. Eccentricity of rollers, belt tension, and occlusion mechanisms should be within the manufacturer’s
specifications. Lubricate bearings if required,
and note this on Line 3.2 of the inspection form.
Ensure that an emergency hand crank is attached to the unit and that the hand crank will
turn the pump when power is disconnected.
1.16 Fluid Levels. Check all fluid levels, including
those in lead-acid batteries. Replenish if low.
1.17 Battery/Charger. Inspect the physical condition of batteries and battery connectors, if readily accessible.
Check operation of
battery-operated power-loss alarms, if so
equipped. Operate the unit on battery power for
several minutes to check that the battery is
charged and can hold a charge. Check remaining battery capacity by activating battery test
function or by measuring the output voltage; for
lead-acid batteries, measure the specific gravity.
For sealed lead-acid batteries, it may be necessary to perform a capacity test by running the
equipment until the batteries are depleted.
Check the condition of the battery charger and,
to the extent possible, confirm that it does, in
fact, charge the battery. When it is necessary to
replace a battery, label it with the date.
1.18 Indicators/Displays. During the course of the
inspection, confirm the operation of all lights,
4
Examine the oxygen flowmeter for signs of
damage or abuse, such as internal nicks,
scratches, cracks, condensation, or debris. The
valves on some machines do not have a fixed-end
stop; take care not to overtighten. Check for free
play in the control valve by pushing, pulling, and
rocking the stem from side to side with rotation.
The stem should feel firm, and the flowmeter
float should not move.
1.20 Alarms/Interlocks. Operate the device in such a
way as to activate each audible and visual alarm.
Check that any associated interlocks function.
Check that, once the alarm condition has been
corrected, the pumps will start and function properly. If the device has an alarm-silence feature,
check the method of reset (e.g., manual or automatic) against the manufacturer’s specifications.
1.21 Audible Signals. Operate the device to activate
any audible signals. Confirm appropriate volume, as well as the operation of a volume control.
1.22 Labeling. Check that all necessary placards, labels, conversion charts, and instruction cards
are present and legible.
1.23 Accessories. Confirm the presence and condition
of such accessories as a level sensor and an
oxygenator light. If a venous line clamp is used,
check that it operates smoothly.
1.24 Water Supply. If the water supply used for temperature control has gauges, check for appropriate water pressure and temperature. Verify that
incoming water temperature and pressure controllers or limitation devices are in place, and if
possible, verify that they are functioning. (A
pressure-relief valve should be used to prevent
overpressurizing the oxygenator.)
2. Quantitative tests
2.1
Grounding Resistance. Using an ohmmeter,
electrical safety analyzer, or multimeter with
good resolution of fractional ohms, measure and
record the resistance between the grounding pin
of the power cord and exposed (unpainted and
not anodized) metal on the chassis. We recommend a maximum of 0.5 Ω. If the device has an
accessory outlet, check its grounding to the main
power cord.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Heart-Lung Bypass Units
2.2
Leakage Current. Measure chassis leakage current to ground with the grounding conductor of
plug-connected equipment temporarily opened.
(Be sure that connections at the inlet or outlet
ports or conductive casters on a conductive floor
do not establish alternate ground paths.) Operate the device in all normal modes, including on,
standby, and off, and record the maximum leakage current. If the unit has heating and cooling
modes, be sure that thermostats permit each
mode to operate while taking readings.
Measure chassis leakage current with all accessories normally powered from the same line
cord connected and turned on and off. This includes other equipment that is plugged into the
primary device’s accessory receptacles, as well as
equipment plugged into a multiple-outlet strip
(“Waber strip”) so that all are grounded through
a single line or extension cord.
Chassis leakage current should not exceed
300 µA.
2.3
Pressure Monitors/Transducers. Perform the
blood pressure monitor (Procedure/Checklist
434) and pressure transducer (Procedure/Checklist 435) inspection and preventive maintenance
procedures on the respective components. Use
separate inspection forms, but record the system’s pass/fail determination on the heart-lung
bypass units inspection form.
2.4
Thermometer Accuracy. To check the accuracy
of thermometers in heater/coolers or water mixers, connect the outflow of the heater or mixer to
the temperature-monitoring device. For heater/
coolers, connect the in-line temperature-monitoring device, allow the unit to stabilize for 15
min, and compare temperatures. When checking water mixers, connect the outflow of the
temperature-monitoring device to a drain, and
compare temperatures. Thermometers should
agree within 1°C. Check at low, medium, and
high points in the temperature range (29°, 34°,
and 38°C).
2.5
Temperature Alarms. For units incorporating
high-temperature alarms, keep the temperature-monitoring device where it was for the previous test. For heater/coolers, place hot water in
the reservoir, and record the alarm value. For
mixers, alter the water mixture, and record the
alarm value. Alarms should occur at 42° ±1°C or
within manufacturer’s specifications. Examine
any associated interlocks (e.g., stop flow, turn off
heater) or alarms at this time.
2.9
Blood Pump Occlusion. In order to operate correctly, the pump rollers must occlude the tubing
throughout its travel across the backplate.
Check tube occlusion with a section of tubing
installed in the pump and filled with water to a
height of about 76 cm (30 in) above the pump.
Leave the other end of the pump open and empty.
Any drop in level should be less than 1 cm/min
or within the manufacturer’s specifications.
Check occlusion at various roller positions on the
back plate.
2.10 Blood Pumps. Check the rollers on each pump to
ensure that they are running smoothly and that
there are no unusual noises from the bearings or
other indications of excessive bearing wear. If the
manufacturer provides torque specifications for
the pump, check this with torque measuring tools.
With correct-size tubing in the pump, immerse both ends of the tubing in a tank of saline
solution or water at atmospheric pressure, and
turn on the pump. For greater accuracy, attach
a cannula to the outflow side of the pump to
simulate back pressure. To check the pump accuracy at a mid-range flow setting, set it to
deliver 3 L/min, and collect the volume for a
convenient time interval in a graduated cylinder
(a fluid flowmeter may also be used). Also check
operation at low and high flow settings. At
higher settings, it may be necessary to collect
fluid in a large bucket and measure out volume
in the graduated cylinder. Flows should be accurate to within 5% of the setting or the manufacturer’s specifications.
For centrifugal pumps, used on some units,
operate with saline and measure flow rate by
pumping saline from a “reservoir” into the
graduated cylinder. Compare this flow rate with
the electronically determined rate, and make
sure it is within 5%.
When checking blood pump flow on pumps
without direct flow setting indication, it may be
useful to draw a graph of flow setting versus dial
setting and placard it on the pump. Be sure to
indicate tubing size and brand on the graph.
2.11 Oxygen Flowmeter. Check the accuracy of the
flowmeter by connecting it in series with the calibrated flowmeter. Set it to deliver a known flow,
and compare this flow to that of the calibrated
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
5
Inspection and Preventive Maintenance System
meter. Check low, medium, and high ranges. The
valve should turn smoothly, with only slight drag,
and the float should rise and fall freely as the flow
is raised or lowered. Accuracy of the machine
flowmeters should agree within 5% of full scale or
the manufacturer’s specifications. Also check other
flowmeters (e.g., CO2), if so equipped.
2.12 Temperature Monitors. Check the accuracy of
all probes with the temperature monitor. Test
the accuracy of thermometers in a water bath
of known temperature or with a patient probe
simulator. Accuracy should be checked at
20°C, 37°C, and 39°C. Check thermometers
intended for wide temperature range application (e.g., hypothermia monitoring) at temperatures near the high and low extremes of
the range. Thermometers should be accurate
within 0.5°C or within the manufacturer’s
specifications. It may be necessary to allow for
errors in the measuring system.
3. Preventive maintenance
3.1
6
Clean the exterior.
3.2
Lubricate casters and motors.
3.3
Calibrate if required.
4. Acceptance tests
Conduct major inspection tests for this procedure
and the appropriate tests in the General Devices Procedure/Checklist 438.
It may be useful to indicate with luminous tape or
paint the direction that the hand crank should be
turned for normal pump rotation in the event of power
failure.
Before returning to use
Ensure that controls are set at normal positions and
that alarm volumes (if adjustable) are set loud enough
to be heard in the clinical setting. Place a Caution tag
in a prominent position so that the next user will be
careful to verify control settings, setup, and function
before using the unit.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Procedure/Checklist 431-0595
Heated Humidifiers
Used For:
Humidifiers, Heated [12-050]
Commonly Used In: Respiratory care area, critical care areas, recovery rooms, nurseries, operating rooms
Scope: Applies to servo-controlled units, units used in combination with separate temperature controllers
(servo control), and non-servo-controlled units
Risk Level: ECRI Recommended, High; Hospital Assessment,
Type
ECRI-Recommended
Interval
Major
12 months
months
.
hours
Minor
NA
months
.
hours
Overview
During normal inspiration, the mouth, nose, and
pharynx warm and humidify air. However, during
long-term ventilatory support or anesthesia when
the patient is intubated with an oral or nasal tracheal tube or tracheostomy tube, this natural humidification process is bypassed; dry, cool gases are
delivered directly to the trachea and lungs, thus
increasing heat and moisture demand on the lower
respiratory tract. As water is vaporized to increase
inspired water vapor concentration and the inspired
gas is warmed by convection, tracheal mucosa loses
heat and moisture. As the mucosa dries and its
temperature drops, secretions thicken and ciliary
activity is reduced, and the ability to clear mucus
and debris is diminished. The formation of thick
mucus plugs can result in atelectasis (i.e., collapse
of the alveoli) or obstruction of the airway.
Using an artificial means to heat and humidify
inspired gases minimizes the complications associated
with artificial airways. Usually, an electrically
heated, water-filled humidifier is applied to the inspiratory gas line. The humidifier simultaneously supplies heat and humidity when the gas passes over a
009073
431-0595
A NONPROFIT AGENCY
Interval Used
By Hospital
Time Required
heated wet surface; efficient design ensures saturation
of the gas mixture leaving the humidifier. The gas
cools as it flows to the patient, producing rainout
(condensation), and is inspired saturated and at a
reduced temperature.
The simplest units heat water by means of a thermostatically controlled heat transfer surface in contact
with a body of water, which in turn heats the gas
stream. Controlling the temperature of the heater
prevents excessive water and gas temperatures. Most
units have a control for varying the gas temperature;
servo-controlled units use a temperature sensor in the
patient circuit for more reliable temperature control of
the gas delivery to the patient.
There is a risk of hyperthermia and respiratory
tract burns if the inspired gas exceeds 40°C for an
extended period of time. Increases in temperature and
exposure time correspondingly increase this risk.
Thus, we recommend monitoring inspiratory air temperature during every heated humidifier application,
and we prefer units that regulate the temperature by
means of a patient circuit probe, rather than reading
water or heater surface temperature.
5200 Butler Pike, Plymouth Meeting, PA 19462-1298, USA
Telephone +1 (610) 825-6000 ● Fax +1 (610) 834-1275
●
E-mail [email protected]
Inspection and Preventive Maintenance System
Citations from Health Devices
Heated humidifiers [Evaluation], 1987 Jul; 16:223-50.
Heated humidifiers can burn infants during CPAP
[Hazard], 1987 Dec; 16:404.
Heated wires can melt disposable breathing circuits
[Hazard], 1989 May; 18:174.
and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive
maintenance procedures or frequencies are recommended by the manufacturer. Test the humidifier,
temperature monitor, and alarm together.
1. Qualitative tests
1.1
Chassis/Housing. Examine the exterior of the
unit for cleanliness and general physical condition. Check that plastic housings are intact with
no cracks or poor seals that spilled fluid can
penetrate, that necessary assembly hardware is
present and tight, and that there are no signs of
spilled liquids or other serious abuse. Check for
discoloration, peeling, melted plastic, or swelling
that may indicate overheating.
1.2
Mount/Fasteners. Examine the mounting security of the humidifier and associated accessories.
1.4
AC Plug. Examine the AC power plug for signs
of damage. Attempt to wiggle the blades to determine that they are secure. Shake the plug
and listen for rattles that could indicate loose
screws. If any damage is suspected, open the
plug and inspect it.
1.5
Line Cord. Inspect the line cord for signs of
damage. If damaged, either replace the entire
cord or, if damage is near one end, cut out the
defective portion. Be sure to wire the new power
cord or plug with the same polarity as the old
one. Ensure that the line cord is sufficiently long
to preclude the need for extension cords.
1.6
Strain Reliefs. Examine the strain reliefs at
both ends of the line cord. Be sure that they hold
the cord securely.
1.7
Circuit Breaker/Fuse. If the unit has a switchtype circuit breaker, check that it moves freely. If
the unit is protected by an external fuse, check its
value and type against that marked on the chassis,
and ensure that a spare fuse is provided. If there
is no provision for a spare fuse, consider installing
a simple spring clip or old fuse holder. If the unit
has a separate fuse for the heated circuit, be sure
to check it (its type and rating are critical).
1.8
Tubes/Hoses. Check the condition of all tubing
and hoses in the unit. Be sure that they are not
cracked, kinked, brittle, or dirty. Check for any
evidence of leaking.
1.9
Cables. Inspect the controller and temperature
sensor cables, if any, as well as their strain reliefs,
for general condition. Check reusable heated
Test apparatus and supplies
Thermometer (bimetallic or electronic) accurate to
at least 0.5°C over a range of 30° to 45°C
T-adapter for positioning a thermometer in series
with the patient inspiratory temperature sensor of
the humidifier
Leakage current meter or electrical safety analyzer
Ground resistance ohmmeter
Source of medical compressed air or oxygen capable
of providing a flow rate of approximately 10 L/min
Distilled water for filling the humidifier
Patient circuit or tubing for use with the humidifier
Pressure gauges or meters with ranges of 0 to 30 cm
H2O and 0 to 100 cm H2O (such as those provided
by a pneumatic tester) with adapters for various
humidifiers to be inspected (acceptance testing only)
Large syringe or sphygmomanometer bulb and
adapter that can be connected to the humidifier
input for pressurizing it to 30 cm H2O (acceptance
testing only)
Special precautions
When inspecting heated humidifiers (and other
thermostatically controlled equipment), verify that the
unit is not operating on its backup or secondary
thermostat. If the normal (primary) thermostat fails
in the on condition, the secondary thermostat will limit
the temperature to protect the heater from burning
out, but the heater may still generate a temperature
excessive for the patient. Thus, if output temperature
is high and the control thermostat does not appear to
adjust it properly, the unit may be operating on its
backup thermostat. Most units do not have an alarm
to alert the user to this condition.
CAUTION: Heater surfaces may be hot.
Procedure
Before beginning an inspection, carefully read this
procedure and the manufacturer’s instruction and
service manuals; be sure that you understand how to
operate the equipment, the significance of each control
2
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Heated Humidifiers
wires for cracks, kinks, and brittleness. Verify
that the wires are compatible with this unit.
1.10 Fittings/Connectors. Examine all gas and liquid fittings and connectors (e.g., patient circuit,
water supply, electrical cable connectors) for
general condition.
1.11 Transducers/Temperature Sensor. Check that
the patient inspiratory temperature sensor is
present and properly fitted into the center of its
adapter for use in the patient circuit.
1.13 Controls/Switches. Before moving any controls
and alarm limits, check their positions. If any of
them appear inordinate (e.g., temperature control at maximum, alarm limits at the ends of
their range), consider the possibility of inappropriate clinical use or of incipient device failure.
Record the settings of those controls that should
be returned to their original positions following
the inspection.
Examine all controls and switches for physical
condition, secure mounting, and correct motion.
Where a control should operate against fixedlimit stops, check for proper alignment, as well
as positive stopping. Check membrane switches
for membrane damage (e.g., from fingernails,
pens). During the course of the inspection, be
sure to check that each control and switch performs its proper function.
1.22 Labeling. Check that all necessary placards, labels, flow rate and temperature calibration
charts, and instruction cards are present and
legible.
1.23 Accessories. Confirm the presence and condition
of such accessories as separate controllers, temperature sensors, and water supplies. Make
sure all necessary parts are present (e.g., valve
flaps, removable stoppers).
1.24 Flow/Output. With distilled water in the humidifier, connect it to a source of medical compressed air and its output to the patient circuit
tubing. Set the unit for a mid-range temperature
and the gas source for 10 L/min, and turn on the
humidifier and gas source. Confirm that the gas
flow in a bubble-type unit actually bubbles up
through the water. Also check that gas is being
humidified after the unit has warmed up, as
evidenced by condensation in the output hose.
(During major procedures, perform Items 2.1
and 2.2 before this test, so that it will be possible
to proceed directly to 2.10 after this test.)
2. Quantitative tests
Perform the following tests (except Item 2.1) with
distilled water added to the unit before applying power
to the heater.
2.1
Grounding Resistance. Measure and record the
resistance between the grounding pin of the
power cord and all exposed metal on the unit
(including heater sheath or surface) except
small external trim pieces. Tug and flex both
ends of the line cord and any connected accessory cords while making the measurement. We
recommend that the resistance not exceed 0.5 Ω.
Grounding resistance and leakage current
measurements are not required if the unit is
constructed primarily of plastic and has no exposed metal surfaces.
2.2
Leakage Current. Measure chassis leakage current with the grounding connection temporarily
opened. Obtain measurements with the unit off
and on and with the unit on and the heater cycle
on and off, and record the maximum leakage
current. Leakage current should not exceed
300 µA. (Since only water vapor and condensate
reach the patient through the inspiratory hose,
special measurements of leakage current from
the water reservoir are not required. However, if
the water supply is readily accessible for leakage
current measurement, this will provide further
1.14 Heater. Examine the heater or heat transfer
surface for physical condition (e.g., corrosion or
pitting of its sheath, deteriorated insulation).
1.16 Fluid Levels. Check that the maximum fluid
level is marked and clearly visible.
1.18 Indicators/Displays. During the course of the
inspection, confirm the operation of all lights,
indicators, and visual displays. If the unit has a
digital temperature display, be sure that all its
segments function.
1.20 Alarms. Operate the unit in such a way as to
activate audible and visual alarms. High-temperature alarms may need to be checked during Item
2.11. If the unit has a probe-disconnect alarm,
verify that it is activated and that the heater is
turned off when the probe is disconnected.
1.21 Audible Signals. Operate the unit to activate
any audible signals. Confirm appropriate volume, as well as the operation of a volume control,
if so equipped.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
3
Inspection and Preventive Maintenance System
assurance of heater insulation integrity, especially if the sheath or heater surface is not of a
grounded design.)
2.3
Low-Temperature Alarms. Verify the functions
and the accuracy of low-temperature alarms and
indicators. Some units alarm if they detect
room-temperature gas (although this may not
occur until after several minutes of operation on
some units); other units have a user-selectable
low-temperature alarm.
3. Preventive maintenance
3.1
4. Acceptance tests
Conduct major inspection tests for this procedure
and the appropriate tests in the General Devices Procedure/Checklist 438. In addition, perform the following tests.
4.1
Pressure Drop. With a T-adapter in the humidifier input, connect the 0 to 10 cm H2O pressure
gauge or meter to measure the input pressure to
the unit. Measure the pressure drop with 10
L/min gas flow exhausting to the atmosphere.
The pressure drop should be less than 5 cm H2O
for bubble-type humidifiers and much less for
other units. (This measurement can be performed while the humidifier is warming up for
the output temperature tests.) This test need not
be performed on units that use disposable humidity chambers or units that allow complete
visual inspection of the flow path, since the absence of any constriction can be verified.
4.2
Leaks. Attach the syringe or sphygmomanometer bulb and 0 to 100 cm H2O pressure gauge or
meter to the input and the output to seal the
humidifier. Pressurize it to 30 cm H2O and observe the pressure drop over 1 min. The pressure drop multiplied by the unit’s internal
compliance (specified by the manufacturer)
should not exceed 6 mL. For example, if the
unit’s internal compliance is 0.4 mL/cm H2O and
the pressure drop over 1 min is 10 cm H2O, the
leakage is 4 mL and within the 6 mL limit.
2.10 Output Temperature. Connect the humidifier
input to a medical compressed-air source and the
output to the patient circuit or tubing. Attach the
test thermometer adapters and the humidifier’s
temperature sensor at the patient Y as close to
each other as the adapters will permit.
Set the temperature controller to low or mid
range (35° to 40°C), set the gas source for 10
L/min, and turn on the humidifier and the gas
source. When the thermometer equilibrates,
record the output temperature and the temperature indicated by the unit’s temperature
monitor or controller. Also, record the controller or thermostat setting. Repeat the test at the
maximum temperature setting. Verify that
the output temperature changes when the setting is changed to maximum. If it does not, the
primary temperature control may not be functioning, and the unit may be operating on its
backup thermostat.
Temperature monitor and temperature settings
(if so equipped) should be accurate within 1°C for
servo-controlled units (other units are not calibrated). The maximum temperature of any unit
should not be higher than that specified by the
manufacturer. (We believe that the maximum
obtainable temperature should not exceed 40°C.
However, many units are capable of delivering
gases at considerably higher temperatures.)
2.11 High-Temperature Alarms. Using the same
setup as in 2.10, verify that the high-temperature alarm activates whenever the output gas
temperature exceeds the alarm set point by more
than 1°C. If the unit has an adjustable high-temperature alarm, verify alarm function at a low
and high alarm setting.
4
Clean the exterior and heat transfer surface with
a damp cloth. (Be sure that the heat transfer
surface is cool.)
To determine nonspecified internal compliance, occlude one end of the humidifier, inject 50
mL of air through the open humidifier port with
a syringe, and measure the increase in pressure
in cm H2O. The internal compliance equals 50
mL divided by the pressure increase. Record this
value for future use.
Before returning to use
Adjust the temperature setting to minimum or normal. Empty or remove the water reservoir. If the unit
is equipped with an adjustable alarm volume, ensure
that the volume is appropriate for a clinical setting.
Return the unit for processing (e.g., cleaning, sterilizing) to prepare it for patient use.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Procedure/Checklist 413-0595
Hemodialysis Units
Used For:
Dialysate Delivery Systems, Multipatient [11-211]
Dialysate Delivery Systems, Single-Patient [11-213]
Hemodialysis Units [11-218]
Also Called: Dialysis machines, dialysis units, artificial kidney machines, hemodialyzers (which more appropriately applies to the dialyzer component of the machine)
Commonly Used In: Hemodialysis departments, critical care units, freestanding hemodialysis treatment
centers, patient homes
Scope: Primarily applies to single-patient hemodialysis units, although portions may be applied to central
hemodialysis systems; also see Peritoneal Dialysis Units Procedure/Checklist 455
Risk Level: ECRI Recommended, High; Hospital Assessment,
Type
ECRI-Recommended
Interval*
Interval Used
By Hospital
Major
12 months
months
.
hours
Minor
3 months
months
.
hours
Time Required
* Temperature, conductivity, and pH (if applicable) monitors should be checked by the operator before each
dialysis.
Overview
Hemodialysis is used to remove accumulated waste
products, organic salts, and water from the blood of a
patient with impaired kidney function or to remove
toxins in cases of blood poisoning. Hemodialysis units
consist of an extracorporeal blood delivery unit (blood
circuit), a dialysate delivery unit (dialysate circuit), a
dialyzer, and monitoring units.
Blood circuit. In the blood circuit, blood is taken
from an artery, circulated through the dialyzer by a
blood pump, cleansed, and returned to a vein. Usually,
one or two needles inserted in an arteriovenous (A-V)
fistula (the linking of an artery and vein) in the patient’s arm provide access to the circulatory system.
The single-needle technique halves the number of
punctures but requires either a Y connection and a
controller to alternate withdrawal and infusion of
009068
413-0595
A NONPROFIT AGENCY
blood, or a special single-needle access catheter. Heparin is infused into the arterial (inflow) side of the blood
circuit to prevent clotting.
Blood pressure sensors on the venous side of the
dialyzer (and sometimes also on the arterial side) may
alarm and stop the blood pump when pressure is
outside preset limits. Most units have an air-bubble
and/or foam detector or blood-level detector, which
clamps the venous blood line and stops the blood pump
if air is detected in the venous line to prevent infusing
air emboli into the patient. Newer units may combine
air-bubble, foam, and blood-level detectors in one
monitor unit.
Dialyzer. In the dialyzer, a semipermeable membrane separates the blood from the dialysate solution.
Substances from the blood pass through the membrane
into the dialysate solution by diffusion, ultrafiltration,
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Telephone +1 (610) 825-6000 ● Fax +1 (610) 834-1275
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E-mail [email protected]
Inspection and Preventive Maintenance System
and osmosis. The dialysate solution initially contains
none of the waste substances to be removed from the
blood. The resulting concentration gradients across
the membrane promote selective diffusion from the blood
to the dialysate solution. Substances that should remain
in the blood are present in equivalent concentrations in
the dialysate solution. The dialysate solution has a lower
hydrostatic pressure than the blood to promote removal
of excess water from the blood by ultrafiltration.
Dialysate circuit. Dialysate solution, a mixture of
treated (purified) water and concentrated dialysate, is
pumped through the dialyzer at a prescribed temperature, concentration, and flow rate. Dialysate solution is
prepared continuously in some machines by a proportioning system that meters and mixes precise proportions of concentrated dialysate and treated water (a
common ratio is 1 part dialysate to 34 parts water). This
proportioning system may be a fixed ratio (i.e., proportioning a known volume of concentrate and water) or may
be servocontrolled, using a control sensor to regulate the
flow of dialysate concentrate. A built-in conductivity
meter continuously monitors the solution before it
reaches the dialyzer. Newer machines may have special
proportioning and monitoring systems for different types
of dialysate (e.g., variable bicarbonate, variable sodium).
The dialysate solution for other machines is prepared
by the simple “batch” method, but enough solution for the
entire procedure must be mixed before the start of dialysis. Portable conductivity meters are used to check batch
mixtures of dialysate solution. The formulation of the
dialysate solution is prescribed by the physician and may
be varied to meet each patient’s needs.
The dialysate circuit may be housed in a single-patient unit or divided between a central unit and a
number of bedside stations. A central unit may allow
the bedside apparatus to be smaller and less costly
than single-patient units. However, a central unit
does not permit individual prescription of dialysate
solution concentration.
Depending on the unit used, monitoring devices in
the dialysate circuit may sense dialysate temperature,
conductivity, flow rate, negative pressure, ultrafiltration rate, and blood circuit leaks. Some monitors and
alarms include fail-safe controls that interrupt the
dialysis procedure to prevent injury.
For more detailed information on dialysis, consult
the Health Devices citations, particularly the 1980
evaluation of hemodialysis machines and the improper
dialysate hazard, as well as Review of Hemodialysis for
Nurses and Dialysis Personnel (Gutch CF, Stoner MH,
Corea AL. 5th ed. St. Louis, MO: C.V. Mosby, 1993).
2
Citations from Health Devices
Single-patient hemodialysis machines [Evaluation],
1980 Feb-Mar; 9:87-130.
Update: Gambro dialysis unit, 1980 Apr; 9:162.
Reusing dialyzers and tubing sets: Pros and cons, 1980
Nov; 10:22-4.
Improper dialysate [Hazard], 1983 Oct; 12:315-8.
Electrical safety of subclavian catheters used in
hemodialysis, 1983 Nov; 13:18-20.
Peritoneal dialysis compared with hemodialysis, 1986
Feb-Mar; 15:34-5.
Hemodialysis water purification [User Experience
NetworkTM], 1988 Aug; 17:247.
Cobe Centry 2 and Centry 2Rx hemodialysis units
[Hazard], 1988 Oct; 17:313-4.
Air embolism associated with hemodialysis [Hazard],
1989 Nov; 18:406-7.
Technical overview: Hemodialysis machines, 1991
Jun; 20:187.
Test apparatus and supplies
Ground resistance ohmmeter
Leakage current meter
Thermometer accurate to at least 0.1°C over a range
of at least 30° to 45°C; a temperature monitoring
device made of a thermometer sealed into one leg of
a Y or T connector may also be used (similar fixtures
are used for hypothermia unit testing, although a
separate fixture should be used for dialysis testing
to avoid possible contamination)
Stopwatch or watch with a second hand
Syringe of the type used in the heparin pump
Syringe (at least 30 cc) to generate pressure of 300
mm Hg
Pressure gauge or meter capable of reading vacuum
and pressure over a range of about -600 to +400 mm
Hg; accuracy should be at least 5 mm Hg over the
-100 to +100 mm Hg range and 5% over the remainder; necessary range depends on type of hemodialysis unit being inspected
Graduated cylinder with a 1,000 mL capacity for
checking flowmeter and blood pump
Conductivity meter, accurate to at least 1% or standard solution to check concentration monitor
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Hemodialysis Units
Expendable supplies for the device being inspected,
including isolators or fluid barriers for pressure
gauges or meters, blood lines, syringes, clamps, dialyzers, and dialysate solution (some of these supplies
are expensive; to reduce costs, a single set of expendable supplies can be used repeatedly for inspections,
except for units dedicated for isolation patients or that
are suspected of having been used on patients with
hepatitis or AIDS; expendables used with such units
should be properly disposed of after use)
Some components covered by the following procedure (e.g., blood pump) are not built into certain older
models of dialysis machines but are accessories that
must be supplied by the user. Note the serial numbers
of these components on the inspection form.
Assorted fittings for connecting tubing and gauges
1. Qualitative tests
Vacuum cleaner
1.1
For some hemodialysis units, especially the more
sophisticated ones, it will be impossible to perform
quantitative checks on all monitoring and alarm circuits. Refer to the service manual for suggestions when
the procedures described below cannot be carried out
in a straightforward manner.
Chassis/Housing. Examine the exterior of the
unit for cleanliness and general physical condition. Be sure that plastic housings are intact,
that all assembly hardware is present and tight,
and that there are no signs of spilled liquids or
other serious abuse. Dialysate has a high salt
concentration that will corrode and tarnish.
1.2
Mount. If the device is mounted on a stand or
cart, examine the condition of the mount. If it is
attached to a wall or rests on a shelf, check the
security of this attachment.
Dialysis-grade water should be used for all inspection and preventive maintenance procedures.
1.3
Casters/Brakes. If the device moves on casters,
check their condition. Look for accumulations of
lint and thread around the casters, and be sure
that they turn and swivel, as appropriate. Check
the operation of brakes and swivel locks, if the
unit is so equipped.
1.4
AC Plug/Receptacles. Examine the AC power
plug for damage from abuse. Attempt to wiggle
the blades to determine that they are secure.
Shake the plug and listen for rattles that could
indicate loose screws. If any damage is suspected, open the plug and inspect it.
Record the time elapsed indicated on the hour meter, if so equipped. This will help indicate appropriateness of preventive maintenance frequency and what
preventive maintenance procedures to do.
pH meter or standard test solutions if unit under
test has pH monitor
Special precautions
CAUTION: For protection against HBV and HIV,
wear rubber gloves, a long-sleeved gown, and safety
glasses or goggles when disassembling or testing dialysis units. Contact the infection control practitioner
responsible for the hemodialysis unit to review institutional policies and procedures regarding protection
from HIV and HBV. Treat machines as though they
were contaminated, and consider maintaining separate, dedicated tool sets for servicing. To minimize the
chance of oral contamination, do not eat or smoke in
the test area. (For more information on infection control during IPM activities, see the article in this binder
titled “IPM Safety.”)
Hospital Grade plugs are strongly recommended for hemodialysis units. Base selection of
plugs on their resistance to fluid infiltration;
Hospital Grade plugs molded onto the line cord
might be considered.
Since there may be water on the floor of maintenance areas, consider using ground fault circuit interrupters for electric shock protection in areas where this
equipment will be tested and serviced.
If the device has electrical receptacles for accessories, insert an AC plug into each and check
that it is held firmly. If accessories are frequently
plugged and unplugged, consider a full inspection
of the receptacle. Check for corrosion.
Procedure
Before beginning an inspection, carefully read this
procedure and the manufacturer’s instruction and
service manuals; be sure that you understand how to
operate the equipment, the significance of each control
and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive
maintenance procedures or frequencies are recommended by the manufacturer.
1.5
Line Cord. Inspect the cord for signs of damage.
If damaged, replace the entire cord or, if the
damage is near one end, cut out the defective
portion. Be sure to wire a new power cord or plug
with the same polarity as the old one. Also check
line cords of battery chargers.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
3
Inspection and Preventive Maintenance System
1.6
Strain Reliefs. Examine the strain reliefs at
both ends of the line cord. Be sure that they hold
the cord securely.
1.7
Circuit Breaker/Fuse. If the device has a
switch-type circuit breaker, check that it moves
freely. If the device is protected by an external
fuse, check its value and type against that
marked on the chassis and ensure that a spare
is provided.
1.8
1.9
Tubes/Hoses. It may be necessary to disassemble the unit to examine all tubing and connectors
to ensure that they fit correctly. The tubing
should not be kinked or mounted near rotating
components, sharp edges, and fastener ends. If
deaerators are used, check them for proper fluid
levels and venting. Check that all seals, grommets, gaskets, and couplings are in good condition and are correctly installed. Tubing and fluid
connectors should not show signs of aging, fatigue, or stress (e.g., discoloration, cracks);
should not contain foreign material; and should
not leak. Look for signs of leaks (e.g., corrosion
or dried dialysate near a connector). Make repairs if any of the above defects are present.
Ensure that all fluid path components are securely mounted to the unit.
Cables. Inspect the cables (e.g., sensor) and
their strain reliefs for general condition. Examine cables carefully to detect breaks in the insulation and to ensure that they are gripped
securely in the connectors at each end to prevent
rotation or other strain.
1.10 Fittings/Connectors. Examine all gas and liquid fittings and connectors, as well as all electrical cable connectors, for general condition.
Electrical contact pins or surfaces should be
straight, clean, and bright. Color-coded or special connectors may be used to avoid inappropriate connections (e.g., a “bicarbonate” dialysate
concentrate to a “sodium” concentrate circuit).
Verify that these safeguards have not been ignored or violated by the use of adapters.
1.11 Transducers. Confirm that any necessary
transducers are on hand, and check their physical condition.
1.12 Filters. Check the condition of all liquid and gas
(air) filters. Clean or replace and indicate this on
Line 3.1 or 3.4 of the inspection form.
1.13 Controls/Switches. Before moving any controls
and alarm limits, check their positions. If any of
4
them appear inordinate (e.g., a conductivity or
flow control at maximum, alarm limits at the
ends of their range), consider the possibility of
inappropriate clinical use or incipient device failure. Record the settings of those controls that
should be returned to their original positions
following the inspection.
Examine all controls and switches for physical
condition, secure mounting, and correct motion.
Where a control should operate against fixedlimit stops, check for proper alignment, as well
as positive stopping. Check membrane switches
for membrane damage (e.g., from fingernails,
pens). During the course of the inspection, check
that each control and switch performs its proper
function.
1.14 Heater. Examine the heater for physical condition (e.g., corrosion of its sheath, deteriorated
insulation). Operate it to ensure that its controls
function properly (e.g., that a variable temperature control does, in fact, determine the amount
of heating; that on/off controls work).
1.15 Motor/Pump/Fan. Check all pumps (e.g., dialysate, recirculating, drain, proportioning, blood,
heparin) for proper operation. Make sure they
deliver fluid properly and are not excessively hot
to the touch while operating. Motors should have
smooth and free-running bearings and should not
be excessively noisy. Check for leaks around pump
seals and coupling, and make sure that pump
heads and motors are clean. Clean and lubricate
pumps, fans, motors, and other moving parts according to manufacturer’s recommendations, and
note this on Lines 3.1 and 3.2 of the form.
On batch-type units, make sure the drain
screen of the dialysate delivery pump is intact
and clean. Replace it if damaged.
1.16 Fluid Levels. Check all fluid levels. Test the
water-loss alarm by momentarily turning off the
water while the unit is running.
1.17 Battery. Inspect the physical condition of batteries and battery connectors, if readily accessible.
Check operation of battery-operated power-loss
alarms, if so equipped. The power-loss alarm
should sound if the plug is pulled out during
operation or when the unit is off and is then
turned on. Check power-loss alarm batteries.
When it is necessary to replace a battery, label
it with the date.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Hemodialysis Units
1.18 Indicators/Displays. During the course of the
inspection, confirm the operation of all lights,
indicators, flowmeters, temperature/pressure
gauges or meters, and visual displays or indicators on the unit and charger, if so equipped.
Ensure that all segments of any digital displays
function.
2.2
1.20 Alarms/Interlocks. Operate the device in such
a way as to activate each audible and visual
alarm. Check that any associated interlocks
function. If the device has an alarm-silence feature, check that it silences the alarm only for the
period of time specified by the manufacturer.
Measure chassis leakage current with all accessories normally powered from the same line
cord connected and turned on and off. This includes other equipment that is plugged into the
primary device’s accessory receptacles, as well as
equipment plugged into a multiple-outlet strip
(“Waber strip”) so that all are grounded through
a single line or extension cord.
Verify that venous line clamps apply enough
force to completely occlude the line.
1.21 Audible Signals. Operate the device to activate
all audible signals. Confirm appropriate volume,
as well as the operation of a volume control.
Hemodialysis is sometimes performed
through a subclavian catheter. Ideally, any
hemodialysis machine connected to a subclavian
catheter should have an isolated patient connection due to the risk of microshock from accidental
migration of the catheter tip into the heart.
However, most units are not designed for this
application; thus, we have not included a test of
fluid path isolation. For subclavian hemodialysis, we recommend using hemodialysis units
with leakage current levels below 50 µA or modified units with redundant grounding or an isolation transformer.
1.22 Labeling. Check that all necessary placards, labels, conversion charts, and instruction cards
are present and legible.
1.23 Accessories. Verify that an emergency hand
crank for the blood pump is supplied with the unit.
1.24 Deaeration. It is difficult to quantitatively assess
deaeration ability in dialysis machines. One of
the primary components of the deaeration system
is the deaeration (vacuum) pump; deterioration of
its performance can adversely affect deaeration.
To check vacuum pumps used in deaeration systems, we suggest measuring the vacuum generated by the pump with a pressure gauge or meter.
Consult the manufacturer for the best measuring point and acceptable vacuum levels or for
other recommended tests.
2.3
2. Quantitative Tests
2.1
Grounding Resistance. Using an ohmmeter,
electrical safety analyzer, or multimeter with
good resolution of fractional ohms, measure and
record the resistance between the grounding pin
of the power cord and exposed (unpainted and not
anodized) metal on the chassis. Verify that a low
resistance exists from the ground pin to various
points on the unit, including all accessory modules, to ensure that interconnections are adequate. We recommend a maximum of 0.5 Ω.
If the device has an accessory outlet, check its
grounding to the main power cord.
Leakage Current. Measure chassis and patient
lead leakage current to ground with the grounding conductor temporarily opened. Operate the
device in all normal modes, including on,
standby, and off, and record the maximum leakage current. Obtain a reading with the heater
cycled on and with it cycled off. Chassis leakage
current should not exceed 300 µA.
Air/Foam (Blood-Level) Detector. Check this detector for proper operation. Ensure that all visual
and audible alarm indicators operate properly.
Clean sensors according to manufacturer’s recommendations, and follow the suggested test procedure. Other interlocked functions (e.g., venous
line clamp, shutoffs, bypasses) should operate
properly when an alarm is indicated. Check sensitivity based on manufacturer’s information, and
verify proper operating range. If the unit has an
alarm-test switch, check that it works correctly,
but be aware that it does not test the sensor.
Some blood-level, air, or foam detectors may
require opaque fluid in the lines in order to
function. Check the manufacturer’s recommendations for testing these units.
2.4
Blood-Leak Detector. Check this detector for
proper operation. Ensure that all visual and audible alarm indicators operate properly. Clean sensors according to manufacturer’s recommendations, and follow the suggested test procedure.
Other interlocked functions (e.g., venous line
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
5
Inspection and Preventive Maintenance System
perature, and compare alarm temperatures
with the manufacturer’s specifications. (On
units where this cannot be done, it may be
possible to test temperature alarms qualitatively by infusing a bolus of hot or cold water
into the dialysate line.) Verify proper function
of high-temperature indicators and any other
interlocked function (e.g., dialysate bypass).
Return the temperature control to the normal
operating temperature.
clamp, shutoffs, bypasses) should operate properly when an alarm is indicated. Check sensitivity based on manufacturer’s information, and
verify proper operating range. If the unit has an
alarm-test switch, check that it works correctly,
but be aware that it does not test the sensor.
On some units, the blood-leak alarm can be
tested by injecting air or milk past the photocell
detector. Check the manufacturer’s recommendations for testing these units.
2.5
2.6
Temperature.
Accuracy. Set the temperature to 37°C on units
with a temperature control. Set the flow rate
to 500 mL/min or according to manufacturer’s
recommendations. Record the reading of the
unit’s temperature indicator and that indicated by the precision thermometer (actual
temperature) after the unit equilibrates. On
units with a coil dialyzer, measure the temperature of the dialysate in the canister. For
units with parallel-flow or hollow-fiber capillary dialyzers, connect the temperature monitoring device to the dialysate line at the
entrance to the dialyzer (a T connection allows
dialysate to keep flowing during the measurement).
When the heaters are initially turned on,
the temperature in some units may overshoot
the desired setting and trigger a high-temperature alarm. Allow 15 min for temperature
stabilization. Remember that dialysate cools
between the heater and the dialyzer; some
units may compensate for this cooling by increasing the temperature of the dialysate in
the unit above the set temperature. The temperature control and/or indicator should be
accurate within 0.5°C or within the manufacturer’s specifications.
6
Conductivity.
CAUTION: Incorrect dialysate conductivity
may be fatal (see Health Devices 1983 Oct; 12:315).
Accuracy. Examine and clean the conductivity
probe, and ensure that the monitor is
mounted correctly according to the manufacturer’s recommendations.
Although conductivity readings can be most
accurately verified by laboratory tests, this is
inconvenient on a routine basis. Comparison
to a conductivity meter or standard solutions
is an acceptable alternative. The conductivity
meter used for this test should have an accuracy of at least 1% and should be checked
frequently against a standard solution. Monitors are calibrated in milliequivalents/L of
chloride (although they measure total ionic
concentration), percent deviation, or milliohms/cm. If the unit is calibrated in percent
deviation, be aware that this corresponds to
only one concentration of dialysate. If physicians at your hospital prescribe other concentrations, check for appropriate deviation
readings.
Alarms. Keep the precision thermometer in the
same position as it was for the previous test.
Test low-temperature alarms by turning the
heaters off and allowing the dialysate to cool
or by adjusting the limits to cause an alarm.
Record the temperature at which the alarm
occurs. Verify the operation of the low-temperature alarm and any other interlocked
functions.
While the unit is running at normal operating temperature, use the manufacturer’s
recommended method to take samples. Be
sure to flush the conductivity meter several
times with the solution to be tested before
taking readings, and take the average conductivity of three samples. If the conductivity monitor error is greater than the
manufacturer’s specification, verify that it is
not due to temperature effects before adjusting the conductivity meter. A fill line
should be marked on the batch tank. If not,
establish the line and mark it on the tank.
Test the high-temperature alarm functions
by setting the temperature control to a value
higher than the alarm limits or by the overshoot when the heaters are initially turned on
(see Accuracy). Record the actual alarm tem-
Alarms. Verify that low- and high-conductivity
alarm indicators function properly. See the instruction or service manual on how to conduct
this test, or test the high-conductivity alarm by
infusing a bolus of dialysate into the water line
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Hemodialysis Units
and test the low alarms by disconnecting the
dialysate supply. Verify that all other interlocked alarms function properly.
2.7
Blood Circuit Pressure.
Monitor. Check the accuracy of blood circuit
pressure monitors by connecting an accurate
pressure gauge or meter and the existing pressure monitor to a T or Y connector (see Sphygmomanometers Procedure/Checklist 424).
Connect the sphygmomanometer bulb to the
remaining port of the connector, increase the
pressure, and read the pressure on both the
monitor and the test gauge or meter. The monitor should be tested at three different pressures to ensure that it is accurate over the
entire range. The monitor should be accurate
within 10 mm Hg or 10% of the reading, whichever is greater, or within manufacturer’s specifications. If there is more than one monitor,
repeat the test for the other monitors.
Alarms. With the pressure gauge or meter still
connected, verify that the appropriate audible
and visual alarms function when the low and
high blood pressure alarm limits are reached.
Confirm that other interlocked functions operate properly. Record the values at which
the alarms occur, and check that they are
within the manufacturer’s specifications.
2.8
2.9
Heparin Pump. Check heparin pump accuracy
with a saline-, water-, or heparin-filled syringe
of the type actually used with the unit. Set the
pump to a rate typical of actual use, and operate
it for a measured time interval. Calculate the
delivery rate from the syringe graduations. Accuracy should be within 10%. Check that the
pump alarms and turns off when the plunger
reaches the end of its travel.
Blood Pump Occlusion. Check tube occlusion by
connecting a T fitting to the outflow end of the
tubing. On one side of the T connect a pressure
gauge or meter. Occlude the tubing segment
with one roller of the pump, and pressurize the
tubing to 300 mm Hg with a syringe attached to
the remaining port of the T or Y fitting. Any drop
in pressure should be within the manufacturer’s
specifications. Repeat this procedure for the
other roller.
2.10 Blood Pump Flow Rate. Check rollers to make
sure that they function smoothly and that there
are no unusual noises from the bearings or other
indications of excessive bearing wear. With cor-
rect size tubing in the pump, immerse both ends
of the tubing in a tank of saline solution or water
and start the pump. Check the accuracy of the
pump at a mid-range flow rate by setting it to
deliver 200 to 250 mL/min and collecting the
volume in a 1,000 mL graduated cylinder for a
specified interval. Also check operation at low
and high flow settings. Flows should be accurate
to within 10% or the manufacturer’s specifications.
On pumps without direct reading of flow rate,
it may be useful to draw a graph of flow rate
versus dial setting and placard it on the pump.
Indicate tubing size and brand on the graph.
Ensure that an emergency hand crank is attached to the unit. Disconnect the power and
verify that the hand crank will turn the pump.
2.11 Dialysate Flow Rate. Check that all markings
are legible. Check the accuracy of the flowmeter
by setting it to deliver a known flow rate
(vol/min) and collect the dialysate flow via the
drain line in a 1,000 mL graduated cylinder for
a specified period. Machines with fixed flow
rates or single-pass converters may be checked
similarly. Check dialysate flow rate at low (minimum), medium, and high (maximum) flow settings. Flowmeter accuracy should be within 10%
or within the manufacturer’s specifications.
2.12 Negative Pressure.
Monitor. Check the negative pressure monitor at
low, medium, or high levels with a vacuum
gauge or pressure meter and a Y or T connector
(some units have a sampling port in the dialysate line that can be used). The reading
should be accurate within 10 mm Hg or within
the manufacturer’s specifications. Refer to the
manufacturer’s manual to determine where to
place the gauge or meter for this test. The
position of the gauge or meter relative to the
dialyzer is important, since elevation errors
are approximately 20 mm Hg/ft. To prevent
contamination, use a standard transducer
protector (isolator) when making these measurements.
Alarms. Verify that the appropriate audible and
visual alarms function when the dialysate
pressure exceeds the preset high and low limits. Verify that other interlocked functions
operate properly.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
7
Inspection and Preventive Maintenance System
2.13 Additional Features. Test additional features
(e.g., ultrafiltration [UFR], variable sodium and
bicarbonate features, pH meters, single-needle
controllers) according to the manufacturer’s
specifications. If quantitative testing of UFR meters is not possible, confirm that they are functioning. Testing of the ultrafiltration control is
essential for high-flux machines. Test the pH
monitor in a manner similar to Item 2.6. The
variable sodium and bicarbonate features may
be inconvenient to test, but both of these parameters of prepared dialysate may be compared to
values obtained by a laboratory blood gas/electrolyte analyzer. (Use reverse side of inspection
form to record test results.)
3. Preventive maintenance
3.1
8
Clean the exterior and interior of the unit. Vacuum air vents and cooling fans, if so equipped.
Clean or replace fan filters. Clean flowmeters, if
required, according to the manufacturer’s instructions.
3.2
Lubricate where appropriate. Lubricate motor
and pump heads according to the manufacturer’s specifications.
3.4
Replace any tubing segments or other items according to the manufacturer’s recommendations.
Replace lights if necessary.
4. Acceptance tests
Conduct major inspection tests for this procedure
and the appropriate tests in the General Devices Procedure/Checklist 438.
Before returning to use
Disinfect the device as recommended by the manufacturer. Make sure controls are set at normal positions and alarm volumes, if adjustable, are set loud
enough to be heard in the clinical use area.
Place a Caution tag in a prominent position so that
the next user will be careful to verify control settings,
setup, and function before use.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Procedure/Checklist 465-0595
Ho:YAG Surgical Lasers
Used For:
Lasers, Surgical, Holmium:YAG [16-943]
Also Called: Ho:YAG lasers, YAG lasers (incorrectly), holmium lasers, surgical lasers, arthroscopic lasers,
urology lasers, angioplasty lasers, thulium:YAG lasers, orthopedic lasers
Commonly Used In: Operating rooms, short procedure areas, cystoscopy rooms, catheterization laboratories, endoscopy laboratories, orthopedic operating rooms
Scope: Applies to general-purpose holmium:YAG surgical lasers that include contact and/or noncontact
flexible fiberoptic delivery systems (either reusable or disposable), emit near-infrared energy at 2,100 nm, and
can provide sufficient power output to coagulate and vaporize tissue; applies to low- and high-power
holmium:YAG surgical lasers that are typically used for general surgery, orthopedic surgery, urology, cardiovascular surgery, gastroenterology, bronchopulmonary, neurosurgery, gynecology, and ENT surgery procedures; does not apply to holmium:YAG lasers used solely for ophthalmic surgery; also does not apply to other
ophthalmic lasers or to CO2 lasers, Nd:YAG lasers, argon lasers, or other surgical lasers; however, many of
the tests listed herein can be used or modified for these other lasers
Risk Level: ECRI-recommended, High; Hospital assessment,
Type
ECRI-Recommended
Interval Used
Major
12 months
months
.
hours
Minor
6 months
months
.
hours
Overview
Ho:YAG lasers are normally checked before each use
by the laser’s power-on self-test and by user examination of the aiming beam and the delivery system to be
used. This minimizes the need for frequent additional
periodic testing. Manufacturers or outside service vendors often maintain lasers for hospitals. The extent
and frequency of inspection by hospital personnel
should be coordinated with these outside services.
Failure of a Ho:YAG surgical laser can cause patient
or staff injury, abrupt interruption of a surgical procedure, or damage to the laser system. These lasers must
be meticulously maintained to ensure proper and safe
operation.
Ho:YAG surgical lasers affect tissue by delivering
invisible, mid-infrared energy at a sufficient power
232619
465-0595
A NONPROFIT AGENCY
Interval
By Hospital
Time Required
density to cause vaporization and/or coagulation. The
2,100 nm, mid-infrared Ho:YAG energy is preferentially absorbed by water and is typically absorbed
within 0.5 mm of the tissue surface. Ho:YAG surgical
laser fibers are most often used in contact with or close
to tissue to cause vaporization. Moving the fiber tip
away from the tissue lowers the power density, causing
less tissue to be vaporized and allowing some coagulation effect.
In addition, Ho:YAG lasers emit a train of energy
pulses; both the energy per pulse and pulse rate are
user settable. Cutting hard tissue may require high
energy per pulse, while a smooth cut may require a fast
pulse rate. However, the range of energy per pulse and
the number of pulse rate combinations are limited by
the laser’s power capability. The output power of the
laser is the product of the energy per pulse times the
5200 Butler Pike, Plymouth Meeting, PA 19462-1298, USA
Telephone +1 (610) 825-6000 ● Fax +1 (610) 834-1275
●
E-mail [email protected]
Inspection and Preventive Maintenance System
pulse rate — for example, 0.5 J × 10 Hz and 1.0 J × 5
Hz are both 5 watts. A 5-watt laser may allow both of
these settings, but not 1.0 J and 10 Hz, which would
require a 10-watt laser. This differs from most other
lasers, which deliver a range of power through a variable energy and fixed pulse rate that is faster than
Ho:YAG’s.
beam pattern introduced by an accessory would be
apparent by examining the visible aiming beam.
Citations from Health Devices
Laser use and safety [Guidance article], 1992 Sep;
21:306-10.
General-purpose Ho:YAG surgical lasers have a laser cavity that houses an yttrium-aluminum-garnet
(YAG) crystalline rod doped with holmium (Ho). (In
most Ho:YAG lasers, the YAG crystal is also doped
with thulium [Tm] and chromium [Cr], which improve
the laser’s efficiency.) Energy leaving the laser tube
through a partially reflecting mirror is typically directed into a flexible optical fiber that transmits the
laser energy to the tissue. The fiber may be used with
additional devices (e.g., through an endoscope), with
special tips, and/or with a laser handpiece or a laser
micromanipulator (used to interface the laser with the
surgical microscope). These attachments can be used
to focus the energy into a small spot size at a known
working distance and or a specific beam direction to
accomplish a special task (e.g., focused energy emission at a right angle to the fiber for sclerostomy).
Ho:YAG surgical lasers [Evaluation], 1995 Mar; 24:92122.
Because the mid-infrared energy emitted by the
Ho:YAG laser is invisible, a second, nontherapeutic
aiming helium-neon (He-Ne) laser or laser diode,
which emits visible light (typically red), simultaneously traverses the fiber and is coincident (i.e., travels
the same path) with the Ho:YAG laser beam.
Vise with padded jaws or ring stand with padded
clamp
Like most lasers, Ho:YAG lasers are inefficient in
converting electrical energy into laser energy. As a
result, excess heat is generated in the laser cavity,
requiring a cooling system. Most Ho:YAG lasers use
water/air cooling systems that are self-contained, connected to a freestanding chiller system, or connected
to a water supply and drain.
Grounding strap (optional)
With Ho:YAG lasers, unlike those lasers that use
mirror delivery systems (e.g., articulating arms on CO2
lasers), it is not necessary to periodically verify coincidence of the aiming and therapeutic beam or to assess
the therapeutic beam pattern (e.g., TEM00) within the
beam or spot. Since the therapeutic and aiming laser
beams are transmitted through a single optical fiber,
these two beams are coincident as they exit the fiber.
Any beam pattern distortion at the fiber entrance
would be eliminated as the laser beams travel through
the fiber because of internal reflections within the
fiber. Misalignment of the beam at the fiber entrance
would result in decreased power output or loss or
distortion of the aiming beam. In a well-aligned system, any significant problem with the therapeutic
2
Test apparatus and supplies
Leakage current meter or electrical safety analyzer
Ground resistance ohmmeter
New, unused fiber delivery system
Black Delrin block 1⁄2″ or more thick, 1″ or more wide,
about 3″ to 4″ long; tongue depressors; or firebrick
Laser radiometer (power meter)
Laser safety signs
Laser safety eyewear specifically designed for use
with Ho:YAG surgical lasers and of sufficient optical
density to protect the wearer’s eye from laser injury
Pressure gauges and coolant system tee fitting
Outlet test fixture (optional)
Insulating gloves, high voltage (optional)
Special precautions
Inspecting and maintaining lasers is a dangerous as
well as necessary process, and far greater care is
required than with most devices. Personnel who inspect or service lasers should receive special training
from the manufacturer or from a qualified alternative
training source.
Laser energy can cause serious injury, particularly
when the internal interlock is overridden or in any
other situation in which the energy does not diverge
significantly over long distances. Under some circumstances, the beam may not diverge significantly, even
a full room length or more away from the laser (and
can harm tissue or burn material even at this distance). Therefore, exercise great care whenever a laser
beam is accessible. Area security and use of personnel
protective devices and practices should be consistent
with hospitalwide laser safety procedures and/or
should be approved by the laser safety committee.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Ho:YAG Surgical Lasers
In addition, windows should be covered with nonreflective material to prevent transmission of laser energy to other areas.
Users should wear appropriate laser safety eyewear
at all times whenever the laser is in the Operating
mode. WARNING: Laser safety eyewear does not protect the wearer from the aiming system light. Do not
stare directly into the aiming system beam or the therapeutic laser, even when wearing laser safety eyewear.
Avoid placing the laser beam path at eye level (i.e.,
when kneeling, sitting, or standing).
Do not perform these procedures when a patient is
present or clinical staff is working, and do not aim the
laser across a path that a person might normally use
as a thoroughfare. Furthermore, at minimum, post
doors to the room with appropriate laser safety signs
stating that the laser is in use and that it is unsafe to
enter the room without authorization by the service
person performing the procedure. A second person
should be present, especially during procedures of recognized risk, to summon help in case of an accident.
The laser should remain in the Off position when
not in use. When in use, it should be in the
Standby/Disabled mode. Do not switch it to the Operating mode until the procedure is about to begin and
the laser and its delivery system are properly positioned. If the procedure must be interrupted, disconnect the laser from line voltage, and remove the laser
operation key and store it in a controlled location.
enter the laser cabinet. When possible, disconnect the
laser from line voltage before entering the laser cabinet, and use insulated gloves for those procedures in
which contact with a high-voltage source is possible
(and the gloves are not otherwise contraindicated).
Ensure that equipment intended to be used to measure, drain, or insulate high voltages carries the appropriate insulation rating (e.g., above 20 kV).
Where possible, perform tests with the unit turned
off. Because of the presence of high voltage, perform
the Grounding Resistance test (Item 2.1) before any
other test that requires operation of the laser.
Report any laser accident immediately to the laser
safety officer or equivalent, as well as to the hospital
risk manager.
Procedure
Before beginning the inspection, carefully read this
procedure and the manufacturer’s operator instructions and service manual; be sure that you understand
how to operate the equipment, the significance of each
control and indicator, and precautions needed to ensure safety and avoid equipment damage. Also, determine whether any special inspection or preventive
maintenance procedures or frequencies are recommended by the manufacturer.
1. Qualitative tests
1.1
General. Verify that the key has not been left in
the laser. (Remove it if it has been, and inform
users of the importance of storing the key in a
controlled location.) Examine the exterior of
the unit for cleanliness and general physical
condition. Be sure that all housings are intact
and properly aligned, that assembly hardware is present and tight, that any retractable
parts slide easily and lock in place if so constructed, that there are no signs of spilled
liquids or other evidence of abuse, and that
there are no obvious signs of water or oil
leakage.
Do not use the laser in the presence of flammable
anesthetics or other volatile substances or materials
(e.g., alcohol), or in oxygen-enriched atmospheres, because of the serious risk of explosion and fire. Remove
from the working area or cover with flame-resistant
opaque material all reflective surfaces likely to be
contacted by the laser beam. Whenever possible, use a
firebrick or other nonflammable material behind the
target material (e.g., black Delrin) when the laser is to
be activated. Target materials will ignite when exposed to high laser energies; use short durations when
practical. A CO2 fire extinguisher should be readily
available.
Some surgical lasers use high voltages (e.g., 20 kV),
which can be lethal. Capacitors may store charges long
after the device has been disconnected from line voltage. Consult the manufacturer’s recommended procedures for servicing high-voltage laser circuits, and
avoid contact with any portion of the high-voltage
circuit until you are certain that the charge has been
drained. In such cases, a good ground must be present;
preferably, use a redundant ground strap if you must
Chassis/Housing.
Shutters. If manual shutters for the aiming system or the therapeutic laser are accessible,
ensure that they operate smoothly and correctly. Be sure to leave the shutter in the
proper position for normal operation.
1.2
Mounts/Holders. Check that mounts or holders
intended to secure the fiber to the fiber support
(to protect the fiber when in use) are present, in
good working order, and being used. Similarly,
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
3
Inspection and Preventive Maintenance System
1.3
check mounts or holders for other devices
(e.g., external power meters, footswitch).
Electrical contacts should be straight, clean, and
bright.
If the device is mounted on a stand or a cart,
examine the condition of the mount. Verify that
the mounting apparatus is secure and that all
hardware is firmly in place.
There should be no visible dirt or residue in
the optical path of the laser aperture. Ensure
that any mechanism to close off the laser aperture (fiber port) is clean, operates smoothly, and
is in use.
Casters/Brakes. Check that the casters roll and
swivel freely. Check the operation of brakes and
swivel locks.
1.4
AC Plug/Receptacle. Examine the AC power
plug for damage. Wiggle the blades to determine whether they are secure. Shake the plug,
and listen for rattles that could indicate loose
screws. If you suspect damage, open the plug
and inspect it.
1.5
Line Cords. Inspect line cords for signs of damage. If a cord is damaged, replace the entire cord
or, if the damage is near one end, cut out the
defective portion. Be sure to wire a new power
cord or plug with the correct polarity.
1.6
Strain Reliefs. Examine the strain reliefs at
both ends of the line cord. Be sure that they grip
the cord securely.
1.7
Circuit Breakers/Fuses. If the device has a
switch-type circuit breaker, check that it moves
freely. If the device is protected by an external
fuse(s), check its value and type against what is
marked on the chassis or noted in the instruction
or service manual. Ensure that a spare is provided or readily available.
1.8
Tubes/Hoses. Check the condition of all coolingsystem hoses and any other hoses or tubing the
laser may have (e.g., drain). Check that they are
of the correct type; that they have not become
cracked and do not show other signs of significant
abuse; that they are connected correctly and positioned so that they will not leak, kink, trail on
the floor, or be caught in moving parts; and that
they are secured adequately to any connectors.
1.9
Cables. Inspect all cables and their channels or
strain reliefs for general physical condition. Examine cables carefully to detect breaks in insulation and to ensure that they are gripped
securely in the connectors at each end to prevent
strain on the cable.
1.10 Fittings/Connectors. Examine all optical (e.g.,
fiber), liquid, and electrical fittings and connectors for general physical condition. Liquid fittings should be tight and should not leak.
4
1.12 Filters. Check the condition of all liquid and air
filters. Some Ho:YAG surgical lasers require
deionized water, and most require special filtration. Measuring the pressure drop across a liquid
filter can be helpful in determining whether the
filter should be replaced. Clean or replace filters
according to the manufacturer’s recommendations (e.g., replace if the pressure drop is >5 psi),
and indicate this in the preventive maintenance
section of the inspection form. Clean or replace
air filters and radiators that are obviously dirty.
1.13 Controls/Switches.
General. Before moving any controls, check and
record their positions. If any position appears
inordinate, consider the possibility of inappropriate use or of incipient device failure. Examine all controls and switches for physical
condition, secure mounting, and correct motion. If a control has fixed-limit stops, check
for proper alignment as well as positive stopping. Check membrane switches for tape residue and for membrane damage (e.g., from
fingernails, pens, surgical instruments). If
you find such evidence, notify users to avoid
using tape and sharp instruments. During the
inspection, be sure that each control and
switch works properly.
Remote. Examine the exterior of the control for
cleanliness and general physical condition. Be
sure that housings are intact, that assembly
hardware is present and tight, and that there
are no signs of spilled liquids or other serious
abuse. If the remote control is attached by
cable to the laser, ensure that the cable and
any connectors are in good condition. Examine
all controls and switches for general physical
condition, secure mounting, correct motion,
and intended range of settings. Where a control should operate against fixed-limit stops,
check for proper alignment as well as positive
stopping. During the course of the inspection,
be sure to check that each control and switch
performs properly.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Ho:YAG Surgical Lasers
Footswitch. Examine the footswitch for general
physical condition, including evidence of
spilled liquids. Footswitches for lasers include
an internal switch that activates according to
the depth of pedal depression. It is usually
possible to feel the vibration caused by closure
of the switch, even through a shoe. Check that
the internal switch is operating and that the
footswitch does not stick in the On position.
Some footswitches include two internal
switches; in this case, verify the operation of
both.
During the procedure, check to be sure that
the laser activates consistently when the footswitch is depressed. Flex the cable at the
entry to the switch, and using an ohmmeter,
check for internal wire breaks that cause intermittent operation. Confirm that strain reliefs are secure.
Examine the male and female connectors
for attaching the footswitch to the laser cabinet to be sure that no pins are bent and that
no other damage is present. Ensure that the
connector secures acceptably to the laser
cabinet.
1.15 Motors/Pumps/Fans/Compressors. Check the
physical condition and proper operation of these
components, if present. If lubrication is required,
note this in the preventive maintenance section
of the inspection form. Clean any obvious dust
from these components.
1.16 Fluid Levels. Check all fluid (e.g., coolant) levels. Refill or change the fluid according to the
manufacturer’s recommendations, and note this
in the preventive maintenance section of the
inspection form.
1.17 Battery. Inspect the physical condition of batteries and battery connectors, if readily accessible.
If a remote control or display is battery powered,
check or replace the battery (periodic prophylactic battery replacement is often preferred to risking battery failure during use). When it is
necessary to replace a battery, label it with the
date.
1.18 Indicators/Displays. During the course of the
inspection, verify proper operation of all lights,
indicators, meters, gauges, and visual displays
on the unit and remote control. Ensure that all
segments of a digital display function. Note any
error messages displayed during the power-on
self-test.
If primary and remote-control indicators and
displays can be used at the same time or if control
can be switched from one to the other during the
course of a procedure, verify that the same information (e.g., settings, displays) is indicated on
both control panels during laser operation.
If display screens or digital displays are provided for user prompts or for viewing accumulated information (e.g., pulse or accumulated
energy counter), ensure that each display provides the information expected. Ensure that user
prompts occur in the proper sequence. Store
some sample information, and verify that it is
correct. If a feature to manually reset this information is available, ensure that it works.
1.19 Laser Delivery System Calibration. Some holmium:YAG surgical lasers include a user-accessible calibration port or power meter that allows
output calibration and/or testing of the laser
fiber. This feature is provided because transmission of laser energy through a fiber may change
as a result of fiber use. Based on the measurement from the calibration power meter, the laser
may automatically recalibrate itself and/or adjust the displays so that the power indicated to
be delivered to the patient will be correct, or it
may require the user to do this manually. Verify
that this feature is functioning by using the
manufacturer’s recommended calibration procedure to test one delivery system (e.g., fiber, handpiece) that the manufacturer indicates can be
acceptably calibrated using these procedures. A
good-quality (e.g., >85% transmissibility, undamaged sheath) fiber or handpiece should be
used for this test.
1.20 Alarms/Interlocks. Operate the device in a
manner that will activate the self-check feature,
if present, and verify that all visual and audible
alarms activate according to the manufacturer’s
documentation. If no self-check feature is present, operate the laser in a manner that will
activate each audible and visual alarm; be sure
to test only those alarms that will not cause
damage to the laser or present an unnecessary
risk of laser beam exposure to yourself or bystanders.
If a door or window interlock is used, ensure
that it deactivates the laser properly. (Do not
disassemble major parts of the laser to test internal interlocks.) After deactivating the laser
and reclosing the door or window, check to be
sure that the laser will restart. Be sure to check
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
5
Inspection and Preventive Maintenance System
the interlocks in all locations where the laser is
used. (For some lasers, the function of the interlocks can be checked using an ohmmeter.)
If the laser is equipped with an emergency
“kill” switch, test this feature to be sure that it
deactivates the laser and that the laser will
subsequently restart.
1.21 Audible Signals. Operate the device to activate
any audible signals (e.g., laser emission, setting
change). Check for proper operation, and verify
that the signal can be heard in the environment
in which the laser will be used.
1.22 Labeling. Check that all placards, labels, and
instruction cards noted during acceptance testing (see Item 4.3) are present and legible. Check
to see that an instruction manual is kept with
the laser or is readily available.
1.23 Accessories.
General. Verify that all necessary accessories
are available and in good physical condition.
Set up reusable accessories with the laser to
ensure compatibility and proper functioning.
Checking all fibers or accessories during a
single inspection and preventive maintenance procedure is unnecessary as long as
accessories are routinely checked by the person(s) responsible for laser setup and operation. In addition, many of the accessories are
sterile and require resterilization before use,
making the laser potentially unavailable. Be
sure to check with the person responsible for
scheduling the use of the laser before beginning the procedure.
Fibers. For the test fiber or before each use,
examine the connector, cable, and tip of each
fiber to be used, as well as the fiber support,
for cleanliness and general physical condition. Be sure that all hardware (e.g., coolant
channels) is present, in good condition, and
firmly attached. Ensure that the connector
properly seats into the laser aperture of the
laser cabinet. Examine the distal end of fibers
to ensure that any connecting mechanisms
(e.g., threads) are in proper working order.
If a fiber appears to be dirty or damaged,
remove it from service. If a fiber is reusable,
notify the person(s) responsible for fiber repair. The fiber should be repaired and/or
cleaned according to the manufacturer’s recommendations. Verify fiber performance.
6
Handpieces. Examine each handpiece component (e.g., body, tips, lenses) for cleanliness
and general physical condition. Examine individually only those components that are intended for removal during normal use and
storage. (Do not remove other parts that are
press-fit or attached by screws, bolts, or snaprings.) If lenses are detachable, be sure not to
touch the lens surface; handle lenses by the
edges only. Consult the manufacturer’s recommendations for the procedures and cleaning agents to use to clean lenses.
Ensure that major subcomponents of the
handpiece, when assembled, are secure. Ensure that the mechanisms used to connect the
handpiece(s) to the fiber are in good working
order and that they reliably secure each handpiece to the fiber.
Microscope micromanipulator. Examine the
microscope micromanipulator for cleanliness and general physical condition. Be sure
to handle it by the main body; do not hold it
by the joystick, and do not touch the reflecting surfaces or lenses in the body. Inspect
micromanipulators provided by both the laser manufacturer and the laser accessory
manufacturer.
Ensure that the reflecting surfaces and
lenses are intact and clean. Consult the
manufacturer’s recommendations for the procedures and cleaning agents to use to clean
reflecting surfaces and lenses.
Examine the joystick to ensure that it is
firmly attached and that it freely moves the
reflecting lens. If a finger rest is present,
ensure that it is firmly attached and properly
oriented.
If a zoom focus feature is present, be sure
that it turns easily and does not slip. Examine
each objective lens to ensure that it is intact
and clean. Do not touch the lens surface. Consult the manufacturer’s recommendations for
the procedures and cleaning agents to use to
clean the objective lenses. Carefully insert
each lens into the micromanipulator, and ensure that it fits snugly.
Inspect the mechanism used to attach the
micromanipulator to the microscope to ensure
that all parts are present and that it is in good
working order. Connect the micromanipulator to the microscope to check for a secure
connection.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Ho:YAG Surgical Lasers
Safety filters. Verify operation of safety filters
in the microscope and endoscope delivery
systems.
However, if the laser power meter does not measure pulse duration, use the following less preferable alternative.
1.24 Aiming Beam. Activate the aiming beam (without the therapeutic beam), and verify that it
produces a round, uniformly bright spot, with no
halo. For handpieces that provide adjustable
spot sizes, verify that the spot size changes as
expected and still remains uniform. Check that
the intensity control, if present, does change the
brightness of the aiming beam. Similarly, check
pulsing controls to verify that the aiming beam
can be pulsed. If several color choices are available for the aiming beam, verify that each color
is present and working properly.
Place and secure the laser fiber, handpiece, or
micromanipulator with the aiming system focused on the target material (e.g., black Delrin
or a tongue depressor). With the laser set to
about 10 W and the exposure set at minimum
duration, activate the laser and create a burn.
Carefully move the target material to expose a
clean area, maintaining the same distance. Adjust the exposure setting in increments of 0.1 sec
or the next longest duration, and activate the
laser at each setting. Continue this process until
you have tested all exposure settings, except
continuous, and have developed a series of
burns. Compare the burns to verify that progressively larger burns occurred as the exposure
duration increased.
1.25 Laser Aperture.
WARNING: Make this inspection with the laser powered off. Remove and inspect the protective window (e.g., blast shield) behind the laser
aperture. It should be clean and undamaged;
clean or replace if needed. There should be no
visible dirt or residue in the optical path of the
laser aperture.
2.4
2. Quantitative tests
2.1
2.2
Grounding Resistance. Use an ohmmeter, electrical safety analyzer, or multimeter with good
resolution of fractional ohms to measure and
record the resistance between the grounding pin
on the power cord and exposed (unpainted and
not anodized) metal on the chassis, accessory
outlet, ground pins, and footswitch. We recommend a maximum of 0.5 Ω. (If the footswitch is
of low voltage, grounding is not required.)
If your laser power meter cannot be used for
this test, use the following alternative test
method. Set the laser to about 10 W and a 0.1 sec
exposure duration with the fiber, handpiece, or
micromanipulator attached, and verify that the
repeat pulse feature operates as expected by
moving the target material slightly between
each pulse. Be extremely careful to keep hands
out of the laser beam path. If the number or
duration between repeat pulses is adjustable,
test that setting changes made throughout the
range result in the expected performance.
Leakage Current.
WARNING: Do not reverse power conductors
for this or any other test. Improper attachment of
conductors may damage the laser.
With the laser attached to a grounded powerdistribution system, measure the leakage current between the chassis and ground with the
unit grounded and ungrounded. The leakage current on the chassis should not exceed 300 µA; in
no case should it exceed 500 µA. Where it is
greater than 300 µA, ensure that appropriate
grounding is present.
2.3
Exposure Duration. Some laser power meters
can measure pulse duration. If the power meter
can react to pulse duration (this is the preferred
circumstance), test the laser at each setting.
Repeat Pulse. If the unit includes a Repeat Pulse
feature, which repeats the pulse at a fixed or
adjustable rate, test this feature with the laser
set at the minimum, median, and maximum
repeat pulse settings, if adjustable. Some laser
power meters can react quickly enough to be
used to test this feature of the laser. If you are
using such a power meter, test the laser to be
sure that the correct power is repeatedly delivered over the correct time period.
2.5
Footswitch Exposure Control. Set the output
time for about 5 sec, activate the unit, and
release the footswitch after about 1 sec. Verify
that the beam turns off when the footswitch is
released.
2.6
Pulse Rate. This test can be done in conjunction
with power output measurements with some
power meters. Should your power meter be incapable of measuring pulse rates, output from a
high-speed IR photodiode circuit and oscilloscope
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
7
Inspection and Preventive Maintenance System
can be used to measure the number of pulses per
second. Alternately, low-power illumination of
thermal paper in a chart recorder will create
marks on the paper that can be compared to the
laser pulse rate.
With the laser set at minimum and maximum
pulse rates and at one mid-range setting between
the minimum and maximum pulse rates, activate
the laser at its minimum power setting for a
sufficient period to acquire acceptable readings.
Compare the reading with the pulse rate display
of the laser; the measured and displayed values
should all be within 10% of one another. In addition, compare the reading obtained with the reading taken on incoming acceptance testing, at the
last preventive maintenance procedure, or after
the last service procedure.
2.10 Power Output. Select one delivery system (e.g.,
fiber, handpiece, micromanipulator), and perform the manufacturer’s recommended user calibration procedure. Secure the delivery system at
the appropriate distance from the detector of the
laser power meter to meet spot-size requirements specified in the instructions for the meter.
(Do not focus the beam to a small spot on the
power meter. Some power meters require that
the unfocused or a defocused laser beam be projected into the detector to cover the majority of
the absorber surface. If the laser beam is focused
on the detector, it may be damaged.)
WARNING: Accessing the unfocused laser
beam may require defeating internal interlocks.
Because of the heightened risk associated with an
unfocused, nondiverging laser beam, exercise
great care if the interlocks are to be defeated.
With the laser set at low (e.g., 10% of full scale),
medium (e.g., 50% of full scale), and maximum
output, activate the laser for a sufficient period
to acquire acceptable readings. (Power meters
use different time constants to acquire an acceptable reading, and you must know and meticulously follow the power meter’s instructions for
use.) Compare the reading with the power display of the laser; the measured and displayed
values should all be within 10% of one another.
In addition, compare the reading obtained with
the reading taken on incoming acceptance testing, at the last preventive maintenance procedure, or after the last service procedure. If the
laser includes a low-power (e.g., mW) feature,
test it in a similar fashion with a power meter of
appropriate resolution in the low-power range.
8
3. Preventive maintenance
Verify that all daily preventive maintenance procedures recommended by the manufacturer are carried
out.
3.1
Clean the exterior. Clean accessible optical components (e.g., blast shield, microscope lenses), if
necessary, using techniques and cleaning solutions recommended by the manufacturer.
3.2
Lubricate any motor, pump, fan, compressor, or
printer components as recommended by the
manufacturer.
3.3
Calibrate/adjust any components (e.g., printer)
according to the manufacturer’s recommendations. Only appropriately trained personnel
should attempt laser adjustments. Ensure that
all hoses and tubes are tight.
3.4
Replace filters if needed. Check all fluid levels,
and supplement or replace fluids if needed.
4. Acceptance Tests
Conduct major inspection tests for this procedure
and the appropriate tests in the General Devices Procedure/Checklist 438.
WARNING: Lasers may be damaged by switching
between normal and reverse polarity while the device is
on. If reverse-polarity leakage current measurements
are made, turn off the unit being tested before switching
polarity. Also, lasers powered by three-phase electrical
systems may be damaged if proper electrical phase
connections are not made initially and maintained
thereafter. Thus, do not switch conductor connections
or wiring configuration for any tests, including leakage
current measurement. Do not conduct electrical leakage
current tests with reversed-polarity wiring.
Also test the ability of the laser to deliver laser
energy as expected in all configurations and with all
provided laser accessories. In addition, perform the
following tests.
4.1
Areas of Use. Visit the area(s) in which the laser
is to be used, and ensure that laser signs,
eyewear, and window coverings are available
and being used and that safety interlocks for
doors or windows, if present, are functioning
properly.
4.2
Casters/Mounts/Holders. Ensure that the assembly is stable and that the unit will not tip
over when pushed or when a caster is jammed on
an obstacle (e.g., a line cord, threshold), as may
occur during transport. If the device is designed
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Ho:YAG Surgical Lasers
to rest on a shelf, ensure that it has nonslip legs
or supports.
4.3
4.4
4.5
4.6
Labeling. Examine the unit and note the presence, location, and content of all labels. Labeling
information is typically found in the laser’s operator manual.
Electrical Wiring Configuration. Ensure that
the branch circuits and the outlets for the laser
are properly wired and rated for use with the
laser. Examine the receptacles at each location
where the laser is to be used to ensure that the
proper electrical configuration (e.g., proper neutral and ground connections, proper phase rotation) has been installed. Connect the laser to
each receptacle and confirm that the laser operates properly, specifically confirming that motors are operating in the proper direction.
4.7
Repeat Pulse. If the unit includes a Repeat Pulse
feature, test this feature as described in Item 2.4,
but over the full range of available settings.
4.8
Power Range. Using the technique described
in the Power Output test, test the power output
accuracy at several low, medium, and high
settings.
4.9
Laser Delivery System Calibration. Use the
manufacturer’s recommended calibration procedure to test each new reusable delivery system
(e.g., fiber, handpiece) that the manufacturer
indicates can be acceptably calibrated using
these procedures. Note the fiber transmission for
each delivery system tested if this information is
provided by the laser. Or you can calculate it
using the following formula:
% Transmission =
Delivered power
× 100%
Power entering the fiber
AC Plug. Verify that the plug is acceptable for
use with the maximum current and voltage
specifications for operating the laser. (Consult
National Electrical Manufacturers Association
[NEMA] configurations for general-purpose nonlocking and locking connectors if in doubt.)
Before returning to use
Pulse Duration. Verify that progressive increases in pulse duration throughout its range of
adjustment result in progressively larger burns.
Be sure to return controls to their starting position,
and place a Caution tag in a prominent position so that
the next user will be careful to verify control settings,
setup, and function before using the unit.
Delivery systems with less than the manufacturer-recommended transmission (typically
>80%) should be returned to the manufacturer.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
9
Procedure/Checklist 414-0595
Hypo/Hyperthermia Units
Used For:
Hyperthermia Units, Circulating-Fluid [17-648]
Hypothermia Units [12-078]
Hypo/Hyperthermia Units, Central [12-074]
Hypo/Hyperthermia Units, Mobile, General-Purpose [12-075]
Hypo/Hyperthermia Units, Mobile, Heart-Lung Bypass [17-206]
Also Called: Hypothermia units, hyperthermia units, heating pads, heater/cooler units
Commonly Used In: Special care units, operating rooms, general medical/surgical areas, emergency departments
Scope: Applies to mobile units that provide both heating and cooling; adaptable for devices that provide heat
only and for central hypo/hyperthermia units; does not apply to smaller circulating-fluid pump/heating pad units,
which should be inspected using Circulating-Fluid Pumps Procedure/Checklist 412
Risk Level: ECRI Recommended, High; Hospital Assessment,
Type
ECRI-Recommended
Interval
Interval Used
By Hospital
Major
12 months*
months
.
hours
Minor
NA
months
.
hours
Time Required
*Flush and refill reservoir, if necessary, at a six-month interval.
Overview
Hypo/hyperthermia units are used primarily to raise
the body temperature of victims of accidental hypothermia, maintain normal temperature (normothermia) in patients during and after surgery, lower the
body temperature for certain surgical procedures, and
lower and stabilize the body temperature of febrile
patients. The utility of hypo/hyperthermia units for
some of these applications has been questioned.
Hypo/hyperthermia units can typically operate in
the following two modes:
Manual. The operator selects the temperature of
fluid to be delivered to the blanket for heating or
cooling the patient. The selected and actual fluid temperatures are displayed. Some units also monitor
patient temperature.
009075
414-0595
A NONPROFIT AGENCY
Automatic (servo). The operator selects the desired
patient temperature. The machine senses the actual
patient temperature through a rectal, skin, or esophageal temperature probe and delivers heated or cooled
fluid accordingly. The machine displays actual and
selected patient and fluid temperatures in this mode.
(See Health Devices 1988 Nov; 17:320-46 for additional
information on applications and operation of hypo/
hyperthermia units.)
Hypo/hyperthermia units are relatively complex
devices. They are among the heaviest and bulkiest
pieces of mobile hospital equipment and are often
subjected to rough handling. The water or antifreeze
solutions used in them can corrode interior parts if the
units are treated carelessly. All too often, patients
being heated or cooled by units that use an automatic
control mode are not observed as carefully as those
whose temperature is being controlled manually.
5200 Butler Pike, Plymouth Meeting, PA 19462-1298, USA
Telephone +1 (610) 825-6000 ● Fax +1 (610) 834-1275
●
E-mail [email protected]
Inspection and Preventive Maintenance System
Thus, accurate and reliable operation of hypo/ hyperthermia units, particularly in the automatic mode, is
crucial.
Such a device does not normally limit water temperature to a clinically safe level, but it should not be
deactivated since unit damage can result.
Hypo/hyperthermia units have been implicated
in a number of cases of patient injury or death.
Investigation of these incidents reveals that some
could have been avoided with adequate inspection
and maintenance.
Some of the items in this procedure differ from most
other procedures in that they may require opening the
unit and temporarily modifying the wiring. We hesitate to recommend such wiring modifications as part
of a routine inspection procedure because unskilled
personnel may inadvertently damage the unit; however, there is no other way to determine whether the
backup thermostats are functional. Personnel responsible for inspecting hypo/hyperthermia units who lack
the technical expertise to perform this test must recognize their own limitations and seek qualified help.
Performing the fluid temperature indicator test (Item
2.10) after the high- and low-temperature protection
tests (Items 2.3 and 2.4) will help ensure that the
device has been correctly returned to its proper operating condition.
Citations from Health Devices
Hypo/hyperthermia machines and blankets [Evaluation], 1988 Nov; 17:320-46.
Test apparatus and supplies
Ground resistance ohmmeter
Leakage current meter or electrical safety analyzer
Calibration thermometer, accurate to at least
±0.3°C over the range of the hypo/hyperthermia
unit’s electronic thermometer, and cups of hot and
cold water (a temperature probe simulator suitable
for use with the hypo/hyperthermia unit to be inspected may be used instead of the thermometer and
the cups of water, but the water and the thermometer will be required to check temperature probes)
Temperature-monitoring device that consists of an
accurate dial thermometer to check the temperature of the circulating fluid, some clear tubing, and
appropriate connectors for installing the device in
series with the blanket. (These devices, sometimes
referred to as shunt thermometers, are available
from some hypo/hyperthermia unit manufacturers,
or they can be constructed; see User-constructed
Test Equipment behind the Test Equipment and
Supplies Tab.)
Hydrometer with scales suitable for the type of
antifreeze used in the unit (required only if the unit
circulates an alcohol or ethylene glycol solution
through the blanket); inexpensive antifreeze testers
are available from automotive parts suppliers.
Procedure
Before beginning an inspection, carefully read this
procedure and the manufacturer’s instruction and
service manuals; be sure that you understand how to
operate the equipment, the significance of each control
and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive
maintenance procedures or frequencies are recommended by the manufacturer.
1. Qualitative tests
1.1
Chassis/Housing. Examine the exterior of the
unit for overall condition. The chassis should be
clean and free of rust and corrosion. Exterior
screws should be tight.
1.2
Mount. If the unit is mounted on a stand or cart,
examine the condition of the mount.
1.3
Casters/Brakes. If the unit moves on casters,
check their condition. Look for accumulations of
lint and thread around the casters, and be sure
that they turn and swivel, as appropriate. Check
the operation of brakes and swivel locks, if the
unit is so equipped.
1.4
AC Plug. Examine the AC power plug for damage. Attempt to wiggle the blades to determine
that they are secure. Shake the plug, and listen
for rattles that could indicate loose screws. If
any damage is suspected, open the plug and
inspect it.
1.5
Line Cord. Inspect the cord for signs of damage.
If damaged, replace the entire cord or, if the
Short-circuited patient temperature probe plug (required only if the unit has an automatic control
mode and circulates an alcohol or ethylene glycol
solution through the blanket)
Cup of saline solution and strip of aluminum foil for
measuring probe leakage current (acceptance testing only)
Special precautions
Some units have undertemperature and/or
overtemperature protection to avoid damage to the
heating element compressor or other parts of the unit.
2
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Hypo/Hyperthermia Units
damage is near one end, cut out the defective
portion. Be sure to wire a new power cord or plug
with the correct polarity.
function properly (e.g., that a variable temperature control does, in fact, determine the amount
of heating; that on/off controls function).
1.6
Strain Reliefs. Examine the strain reliefs at
both ends of the line cord. Be sure that they hold
the cord securely.
1.7
Circuit Breaker/Fuse. If the unit has a switchtype circuit breaker, check that it moves freely.
If the unit is protected by an external fuse, check
its value and type (as well as those of any spares
provided) against that marked on the chassis.
1.15 Motor/Pump/Fan/Compressor. Check the
physical condition, and verify proper operation
of these components. Lubricate them if required, and note this on Line 3.2 of the form
(but do not check 3.2 until you have completed
all necessary lubrication).
1.8
Tubes/Hoses. Check the condition of all tubing
and hoses. Be sure that they are not cracked,
kinked, or dirty.
1.10 Fittings/Connectors. Attach a blanket to each
pair of connectors on the unit to ensure that the
unit operates smoothly and does not leak. Examine all fittings and connectors, as well as all
electrical cable connectors, for general condition.
Electrical contact pins or surfaces should be
straight, clean, and bright.
1.11 Probes. Confirm that patient temperature
probes are on hand, and check that they are
clean and are not cracked, brittle, or otherwise
deteriorated.
1.12 Filters. Check the condition of the fluid filters,
if so equipped. Clean or replace them as needed,
and indicate this on Line 3.1 or 3.4 of the inspection form.
1.13 Controls/Switches. Before moving any controls
or alarm limits, check their positions. If any of
them appear inordinate (e.g., a temperature control that is at the end of its range), consider the
possibility of inappropriate clinical use or of incipient device failure. Record the settings of
those controls that should be returned to their
original positions following the inspection.
Examine all controls and switches for physical
condition, secure mounting, and correct motion.
Where a control should operate against fixedlimit stops, check for proper alignment, as well
as positive stopping. Check membrane switches
for membrane damage (e.g., from fingernails or
pens). During the course of the inspection, be
sure to check that each control and switch performs its proper function.
1.14 Heater. Examine the heater for physical condition (e.g., corrosion of its sheath, deteriorated
insulation). Operate it to verify that its controls
1.16 Fluid Levels. Check the circulating fluid level in
the reservoir with a blanket connected, and add
fluid as needed. Consult the operator’s manual
to determine the proper level. If fluid is needed,
add distilled water or the manufacturer’s recommended alcohol-and-water or antifreeze-andwater mixture. If the unit uses distilled water,
add a disinfectant according to the manufacturer’s instructions. If it uses antifreeze, check
its specific gravity with a hydrometer, with the
fluid at about room temperature.
1.18 Indicators/Displays. During the course of the
inspection, confirm the operation of all lights,
indicators, meters, gauges, and visual displays
on the unit and charger, if so equipped. Be sure
that all segments of a digital display function.
1.20 Alarms. Operate the unit in such a way as to
activate each audible and visual alarm. Check
that any associated interlocks function. If the
unit has an alarm-silence feature, check the
method of reset (e.g., manual or automatic)
against the manufacturer’s specifications. It will
not be possible to check out all alarms at this
time, since some of them require abnormal operating conditions that will be simulated later in
Items 2.3 and 2.4.
1.21 Audible Signals. Operate the unit to activate
any audible signals. Confirm appropriate volume, as well as the operation of the volume
control, if so equipped.
1.22 Labeling. Check that all necessary placards, labels, conversion charts, and instruction cards
are present and legible.
1.23 Accessories.
Blankets. Check each reusable blanket for leaks,
connector operation, and general cleanliness.
Since blankets do not usually have serial
numbers on them and may be interchanged
between units, it is not possible to associate the
blanket inspection with any one unit. Nevertheless, the hospital should know how many
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
3
Inspection and Preventive Maintenance System
the maximum reading of the temperature-monitoring device, and note any overheating or hightemperature alarms. If the unit has a secondary
backup device, bypass the primary high-temperature backup and repeat the test. The maximum temperature(s) should agree with the
manufacturer’s specification for the primary
(and secondary) backup device, but should not
exceed43°C.
reusable blankets it owns and should inspect
each one regularly. Check for leaks with the
blanket connected to an operating hypo/hyperthermia unit because this produces the
highest pressure within the blanket tubing.
Blankets that pass inspection should be
tagged “Inspected,” with the date and inspector’s initials noted. Roll, rather than fold,
stored blankets to prolong their life.
Caution: Remove any bypasses installed for
this test.
2. Quantitative tests
2.1
Grounding Resistance. Using an ohmmeter,
electrical safety analyzer, or multimeter with
good resolution of fractional ohms, measure and
record the resistance between the grounding pin
of the power cord and exposed (unpainted and
not anodized) metal on the chassis. If a redundant ground is provided, either as a second plug
or an alligator clip, check its resistance to the
chassis. We recommend a maximum of 0.5 Ω.
If the device has an accessory outlet, check its
grounding to the main power cord.
2.2
Leakage Current. Measure the maximum leakage current between the chassis and ground with
the ground wire temporarily opened and any
redundant ground removed. Check the following operating modes with the grounding conductor interrupted: off, manual cooling, manual
heating, and circulate only. Record the highest
leakage current; it should not exceed 300 µA.
2.3
High-Temperature Protection. This test confirms the operation of the high-temperature
backup (and secondary backup, if present) and
should be performed on all units regardless of
the type of circulating fluid. Identify the backup
thermostats or other devices. If the unit does not
have an automatic mode, consult the manufacturer to determine how to test backup protection.
If the unit has an automatic mode with two
backup high-temperature cutoffs, check both.
Install a jumper across the thermostat;
check the service manual for information on
how to do this. Operate the hypo/hyperthermia unit in the automatic mode with a temperature-monitoring device connected in series
with the input line to the blanket. Set the
control temperature to room air, and expose
the patient temperature probe to a value above
room ambient temperature. The hypo/ hyperthermia unit should heat the circulating fluid
until it is limited by the backup cutoff. Record
4
Repeat the test with the patient temperature
probe unplugged. The temperature should go no
higher than before; some units will indicate the
failure with a Probe Open alarm, and the unit
will not operate.
2.4
Low-Temperature Protection. This test is similar to Item 2.3, except that it confirms the operation of the primary low-temperature backup (and
secondary backup, if present) and should be performed only if the unit circulates alcohol or ethylene glycol through the blanket and has an
automatic control mode. Low-temperature
backup cutoffs are intended to protect the patient against excessive cooling if the temperature-control circuitry or probe fails. Before
performing this test, obtain a schematic of the
hypo/hyperthermia unit and determine whether
the unit has low-temperature backup protection
(a thermostat or other cutoff).
Install a jumper across the main thermostat.
Check the service manual for information on how
to do this. Operate the hypo/hyperthermia unit
in the automatic mode with a temperature-monitoring device connected in series with the input
line to a blanket. Set the control temperature to
its lowest value, and expose the patient temperature probe to room air. The hypo/hyperthermia
unit should cool the circulating fluid until it is
limited by the backup cutoff. Record the lowest
temperature indicated by the temperaturemonitoring device, and note any alarms. If the
unit has a secondary low-temperature backup,
bypass the primary low-temperature backups
and repeat the test. The recorded temperature(s)
should agree with the manufacturer’s specification for the primary backup (and secondary
backup) device (usually ≥1°C).
Repeat the test with a shorted patient temperature probe plug substituted for the probe
itself. Observe the operation of a Probe Shorted
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Hypo/Hyperthermia Units
cup of 41°C water used in the last test, and
operate the unit in the automatic mode with the
temperature-monitoring device in the input line
to a blanket and the control point set to 37°C.
The temperature of the circulating fluid should
drop to the low level recorded in Item 2.10. Next,
transfer the patient temperature probe to the
cup of cooler water saved from the previous test
(it is not necessary to recheck the temperature
of that water), and observe both the temperature
indicator and the Heat and Cool indicators (if so
equipped) on the unit. Note the reading on the
patient temperature indicator when the unit
switches from cooling to heating. It should be
within 0.5°C of the 37°C set-point temperature.
If the unit lacks indicators for the heating and
cooling modes, listen for a change in sound as the
cooling compressor stops. The circulating fluid
temperature should equilibrate at the high value
recorded in Item 2.10. This test can also be
performed using a patient temperature probe
simulator, if available.
alarm, if so equipped. If the machine operates at
all, the minimum fluid temperature should be
limited by the primary backup cutoff.
Caution: Remove any bypasses installed for
this test.
2.10 Fluid Temperature Indicator. Operate the unit
in the manual mode with the temperature-monitoring device in the input line to the blanket.
Select the lowest blanket temperature setting,
and wait until the temperature stabilizes (this
should take 3 to 10 min). Record the setting of
the control knob, the reading of the fluid temperature indicator, and the reading of the temperature-monitoring device; it should not drop
below 1°C. The first two should be within 1°C of
the temperature-monitoring device. Repeat this
test with the manual control set at its highest
temperature; it should not exceed 43°C.
2.11 Patient Temperature Indicator and Probe. This
test applies only to units with an automatic mode
of operation. Fill a cup with tap water at about
30°C, as measured with the calibration thermometer. Be sure that the thermometer is immersed to an adequate depth to provide an
accurate reading. Place the calibration thermometer and the unit’s patient temperature
probe in the water near each other. Record the
two readings on the form. (It may be necessary to
operate the unit in order to read the thermometer.) Repeat the test with cups of water at temperatures of about 37°C and 41°C. The
temperatures, in all cases, should be within 1°C.
Repeat this test with each probe. Save the warmest and coldest cups of water for the next test.
A patient temperature probe simulator, if
available, is more convenient for determining the
accuracy of the patient temperature indicator.
However, because the simulator tests only the
circuitry and not the probe itself, probe accuracy
must also be verified. A convenient test method
is to dip all probes simultaneously into one bodytemperature water bath, allow them to equilibrate, and successively plug each into the same
pretested temperature unit or module. All
probes should give the same temperature reading. (Some variation is normal because the water
temperature varies slightly with location in the
bath and the water gradually cools with time.)
2.12 Automatic Controller Switching. This test applies only to units with an automatic mode. Keep
the patient temperature probe immersed in the
3. Preventive maintenance
3.1
Clean the exterior, interior, and fluid filter, if
necessary. Remove dirt that has accumulated in
vents and cooling fans within the unit with a
vacuum cleaner or compressed air hose. This will
usually require removal of a chassis panel.
3.2
Lubricate the circulating pump, if required.
3.3
Calibrate, if needed.
3.4
Flush/refill the reservoir and replace the fluid
filter, if necessary.
4. Acceptance tests
Conduct major inspection tests for this procedure
and the appropriate tests in the General Devices Procedure/Checklist 438. In addition, perform the following tests.
4.1
Probe Leakage Current. If the unit has a patient
temperature probe, measure leakage current
from all available probes in every operating
mode. Wrap the probe loosely with aluminum foil,
clip the lead from the leakage current meter to
the foil, and immerse the probe and foil in a salt
water solution (normal saline or about a teaspoon
of table salt per cup of water). Leakage current
greater than 100 µA suggests a damaged probe.
Alternatively, measure probe circuit leakage
current directly from each probe electrical lead
contact (using an appropriate plug) on units that
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
5
Inspection and Preventive Maintenance System
do not use ground-referenced probe circuits. If
the leakage current to ground from each lead of
the connector is less than 100 µA in each operating mode, then it is unnecessary to check leakage
current from the probe itself. (An appropriate
resistance to simulate the thermistor may be
required on some units that have protective circuits to turn off heater power in the event of a
probe malfunction.) However, thoroughly examine the probe for defects (Item 1.11).
4.2
Hysteresis. This test will determine the difference between the set-point temperature and the
reset temperature of the high-temperature
thermostat. This test need be performed only in
the manual mode. If a problem is found in this
mode, it would consequently also be present in
the automatic mode.
Connect a blanket and/or test hose shunt to the
unit. (Some units require that fluid circulate while
the unit is operating.) Allow the unit to warm up
for at least 15 min in the manual mode with the
water temperature set to 40°C. After warm-up,
set the water temperature selector to its highest
setting. The Heat light should come on, indicating
6
that the water is being warmed. Watch the
water temperature indicator and the Heat light,
and record the water temperature reading at
which the Heat light goes out. This is the setpoint temperature of the primary high-temperature thermostat. This temperature should agree
with the manufacturer’s specification.
Allow the unit to continue running in the
manual mode with the water temperature selector set to its highest setting. The water temperature will begin to slowly drop. Observe the water
temperature indicator, and record the temperature at which the Heat light comes back on; this
is the reset temperature of the thermostat. The
difference between the set-point temperature
and the reset temperature is the hysteresis. The
maximum hysteresis should be 3°C. Thus, the
reset temperature range will typically be 39° to
41°C.
Before returning to use
Verify that any control circuits that were bypassed
or deactivated for testing purposes have been returned
to their normal operating conditions.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Procedure/Checklist 415-0595
Infant Incubators
Used For:
Incubators, Infant, Mobile [17-432]
Incubators, Infant, Transport [12-114]
Commonly Used In: Delivery rooms, neonatal ICUs, nurseries, ambulances, and aircraft
Scope: Does not apply to radiant warmers or transport radiant warmers (see Procedure/Checklist 419)
Risk Level: ECRI Recommended, High; Hospital Assessment,
Type
ECRI-Recommended
Interval
Interval Used
By Hospital
Major
12 months
months
.
hours
Minor
NA*
months
.
hours
Time Required
* Minor intervals for transport incubators should be every 3 months.
Overview
Infant and transport incubators provide warmth to
help an infant maintain a normal body temperature
and are often essential for an infant’s survival. Most
incubators warm the infant by a forced or natural flow
of heated air. One type, no longer in production, supplements air convection with radiant infrared energy
from heated bassinet and hood walls.
Infant incubators are designed primarily for in-hospital use at specific locations, operate on AC line power
in a temperature-controlled indoor environment, and
rest on relatively high movable stands. Transport
incubators provide thermal support during transfer
within the hospital or by car, ambulance, or aircraft to
another hospital. Transport incubators are both portable and mobile; operate from a variety of power
sources, including self-contained batteries; have
stands that are relatively low or adjustable in height
to fit into vehicles with restricted overhead clearance;
and may be required to operate in ambient conditions
much colder than those found in a hospital.
Deaths and injuries to neonates have occurred in
incubators. Reports include thermostat failures that
caused incubator overheating and infant hyperthermia, malfunctions or design defects that produced fires
009078
415-0595
A NONPROFIT AGENCY
and presented electrical shock hazards, and poor
transport incubator performance or power failure due
to improperly maintained batteries or unreliable battery-charge-level indicators. Because incubators are
bulky and mobile, they routinely receive rough handling (especially transport units) that may degrade
performance and physical condition. Periodic inspection may reveal hazardous deficiencies that could
harm patients.
Citations from Health Devices
Mercury contamination in incubators and elsewhere,
1981 Dec; 11:65-8.
Transport incubators [Evaluation], 1982 May; 11:
179-91.
Infant incubators [Evaluation], 1982 May; 11:191-9.
Update: Transport incubators, 1982 Sep; 11:301.
Air-Shields C-300-1, C300-2, and TI-100 infant incubators [Hazard], 1986 Jul; 15:212-3.
Air-Shields Vickers C100 and C200 infant incubators
[Hazard], 1987 Jul; 16:253-4.
Air-Shields C-86, C-100, and C-200 infant incubators
[Hazard], 1987 Nov; 16:376-7.
5200 Butler Pike, Plymouth Meeting, PA 19462-1298, USA
Telephone +1 (610) 825-6000 ● Fax +1 (610) 834-1275
●
E-mail [email protected]
Inspection and Preventive Maintenance System
Air-Shields Vickers C-86 infant incubators [Hazard],
1988 Oct; 17:314-5.
Mallinckrodt incuTemp 4 skin temperature probes and
Air-Shields Vickers C-100 incubators [Hazard],
1990 Jul; 19:245.
Thermometer holders detaching from hoods of Ohmeda Air-Vac transport incubators, 1994 Oct-Nov;
23:457-8.
Test apparatus and supplies
Ground resistance ohmmeter
Leakage current meter or electrical safety analyzer
Patient-probe simulator capable of simulating a
range of temperatures as well as open- and shortcircuited probe conditions (for incubators that use
patient temperature probes)
Plastic 6 to 8 oz cup
Source of varied-temperature water; a temperature
simulator will simplify some device tests, but at
least one cup of water will be needed to verify probe
accuracy and probe leakage current
operate the equipment, the significance of each control
and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive
maintenance procedures or frequencies are recommended by the manufacturer.
If it is necessary to inspect several incubators that
have patient probes, it may be convenient to use a
patient-probe simulator to test indicator accuracy and
temperature control effectiveness of all probes simultaneously. The procedure is essentially the same as
that used in Temperature Monitors Procedure/Checklist 425. It may be necessary to use different connectors to accommodate the probes of the incubators being
inspected.
If an incubator to be inspected is in use, ask clinical
personnel if they can use a temporary substitute, or
request that they notify you when the incubator is free
for inspection.
1. Qualitative tests
1.1
Calibrated glass or electronic thermometer accurate
to within 0.1°C in the clinical range
Oxygen source and flowmeter
Hot-air gun or hair dryer
For transport incubators with lead-acid batteries:
hydrometer to measure specific gravity of the batteries; float markings should cover the range from
1.240 to 1.280 to within 0.001 accuracy (available
from any scientific apparatus supplier) (Note: automotive hydrometers that indicate only GOOD or
BAD without numerical specific gravity indications
are not suitable.)
The hood condition is important for proper
control of the infant’s environment. Ensure that
the hood is free of cracks, warping, or other signs
of deterioration. Determine whether any parts
are missing or incorrectly assembled. Examine
all ports for proper alignment and sealing.
Consult the instruction manual for a general
exploded diagram of the incubator; remove the
hood, bed, baffle, main deck, and other parts and
thoroughly inspect the interior for foreign objects,
deterioration, or misassembly of internal components that could interfere with performance. Look
for contamination of the air supply and blocked air
and/or humidity passages caused by improper
placement of the humidity tray or gaskets.
Special precautions
Examine all mercury-in-glass thermometers and
high-temperature thermostats. If broken, replace and
clean the unit carefully using appropriate precautions
for mercury spills (see Health Devices 1981 Dec; 11:65
and the “IPM Safety” article behind the Guidance Tab
in this binder). ECRI recommends replacing all mercury-containing components in infant incubators.
Examine the humidity apparatus for deterioration, contamination, and missing or incorrectly assembled parts.
CAUTION: Mercury and its vapors are toxic. Do not
allow mercury to contact an open cut.
1.2
Procedure
Before beginning an inspection, carefully read this
procedure and the manufacturer’s instruction and
service manuals; be sure that you understand how to
2
Chassis/Housing. Examine the overall exterior
condition of the chassis. Check that the control
unit is clean, that all labels and markings are
legible, and that no adhesive tape or tape residue
is present. Remove any tape. Check all rubber
or plastic gaskets in the incubator for signs of
deterioration (e.g., cracks).
Mount/Fasteners. Check that all screws, nuts,
and fasteners are tight. Sometimes a loose screw
may not be easy to detect visually. Use a screwdriver and systematically try to tighten every
screw on the hood.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Infant Incubators
Operate iris-type port closures to ensure
proper function. Examine the iris diaphragms
and port sleeves for tears. A torn or otherwise
damaged iris reduces the integrity of the closedchamber system. Consult the manual to determine if the irises are disposable types that should
be discarded after each incubator use. You need
not replace torn disposable irises, since they will
be routinely replaced when the interior is sterilized for the next incubator application. Verify
with clinical personnel that this practice is enforced and that disposable irises are not reused.
1.3
1.4
Casters/Brakes. If the device moves on casters,
check their condition. Remove accumulations of
lint and thread from around the casters, and be
sure that they turn and swivel, as appropriate.
Check the operation of brakes and swivel locks
if the unit is so equipped. Conductivity checks,
where appropriate, are usually done more efficiently as part of a check of all equipment and
furniture in an area.
AC Plug/Receptacles. Examine the AC power
plug for damage. Attempt to wiggle the blades to
determine that they are secure. Shake the plug
and listen for rattles that could indicate loose
screws. If any damage is suspected, open the
plug and inspect it.
If the device has electrical receptacles for accessories, insert an AC plug into each and check
that it is held firmly. If accessories are plugged
and unplugged often, consider a full inspection
of the receptacle.
1.5
Line Cord. Inspect the cord for signs of damage.
If damaged, replace the entire cord or, if the
damage is near one end, cut out the defective
portion. Be sure to wire a new power cord or plug
with the same polarity as the old one. Check line
cords of battery chargers.
1.6
Strain Reliefs. Examine the strain reliefs at
both ends of the line cord. Be sure that they hold
the cord securely.
1.7
Circuit Breaker/Fuse. If the device has a circuit
breaker, check that it operates freely. If the
device is protected by an external fuse, check its
value and type against that marked on the chassis, and ensure that a spare is provided.
1.8
Tubes/Hoses. Check the condition of all tubing
and hoses. Be sure that they are not cracked,
kinked, or dirty. Inspect all oxygen orifices to
make sure that they are clear and free of foreign
matter.
1.9
Cables. Inspect the cables (e.g., sensor, electrode, remote control) and their strain reliefs for
general condition. Examine cables carefully to
detect breaks in the insulation and to ensure
that they are gripped securely in the connectors
of each end to prevent rotation or other strain.
1.10 Fittings/Connectors. Examine all electrical cable connectors for general condition. Electrical
contact pins or surfaces should be straight,
clean, and bright.
1.11 Probes. Examine all patient probes to ensure
that they are clean and are not cracked, brittle,
or otherwise deteriorated. If the hospital has
more than one type of infant incubator, ensure
that probe labels clearly identify the associated
units. Improperly interchanged probes of different types or from different manufacturers may
adversely affect temperature control.
1.12 Filters. Inspect the air filter for signs of clogging; if the filter looks dirty, replace it and note
this on Line 3.4 of the inspection form. Check the
air-filter assembly to ensure that airflow is unimpeded. Clogged or improperly installed filters
can raise the oxygen concentration above safe
levels. Change filters regularly according to the
manufacturer’s recommendations, and record
the date you install a new filter.
Attach an oxygen source with a flowmeter to
each oxygen port and use your hand to feel that
gas is flowing into the chamber. Vary the oxygen
flow and check that manufacturer-specified
maximum and minimum flow rates can be
achieved.
1.13 Controls/Switches. Before moving any controls
and alarm limits, check their positions. If any of
them appear inordinate (e.g., a temperature control turned to the end of its range), consider the
possibility of inappropriate clinical use or incipient device failure. Record the settings of those
controls that should be returned to their original
positions following the inspection.
Examine all controls and switches for physical
condition, secure mounting, and correct motion.
Where a control should operate against fixedlimit stops, check for proper alignment, as well
as positive stopping. Check membrane switches
for membrane damage (e.g., from fingernails,
pens). During the course of the inspection, be
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
3
Inspection and Preventive Maintenance System
sure to check that each control and switch performs its proper function.
1.14 Heater. Disassemble the heating unit enough to
expose the heating element. Examine the element for severe discoloration or foreign deposits.
Heating elements normally change color with
use, but dark, distinct surface spotting may indicate that material has come into contact with
the element, possibly after falling through the
air duct. Foreign matter touching the hot surface
could cause a fire or the generation of noxious
fumes. If you find such discoloration, examine
the control unit compartment for signs of overheating (e.g., darkening, blistering). If screw
terminals connect the heating element to the
control circuitry, check that they are tight.
Operate the heater to verify that heater controls function properly (e.g., that a variable temperature control does, in fact, cycle the heater off
and on as the set point is varied).
1.15 Motor/Fan. Inspect the fan blades for deterioration or damage, such as melting (if plastic),
warping, or lost blades. Ensure that the fan is
securely attached to its drive shaft and that the
coupling is present and intact. Check that clearance between the fan and its housing is adequate
by looking for signs of rubbing. In some cases,
an improperly inserted control module and
heater assembly in the incubator base has bent
and disabled the fan, preventing air circulation
and causing overheating.
Check the service manual to determine if the
fan motor requires lubrication. Oil as recommended and note on Line 3.2 of the inspection
form. Check the sound level inside the incubator;
noisy operation may indicate that the fan motor
or housing assembly needs service.
In some incubators, the fan is visible at the
back of the control module if the module is removed. If possible, expose the fan and operate
it, and watch for wobbling or excessive vibration.
If possible, spin the fan with your finger (with the
power off) and make sure that it turns smoothly.
1.16 Fluid Levels. Check all fluid levels, including
those in lead-acid batteries.
1.17 Battery/Charger. Inspect the physical condition of batteries and battery connectors if readily
accessible. Check operation of battery-operated
power-loss alarms if so equipped. Each battery
should have an identification number and an
4
accurate log of operating time, recharges, service, and inspections to permit early detection of
deteriorating performance. Operate the unit on
battery power for several minutes to check that
the battery is charged and can hold a charge.
Check remaining battery capacity by activating
the battery test function. Check the condition of
the battery charger, and to the extent possible,
confirm that it does, in fact, charge the battery.
When it is necessary to replace a battery, label
it with the date.
A liquid-electrolyte lead-acid battery located
in the same case as the charging circuitry can
cause problems unless the battery is kept clean.
Wash off acid and other materials that may
collect on top of the battery. If there is electrolyte
or a yellow-white powder on the battery, check
for contaminating deposits on components of the
charging circuit; these may cause rapid deterioration. Wipe components clean, or replace the
charging circuit if it appears corroded. Check for
obstructions in the vent caps and associated
venting system. If necessary, clear the venting
system with a stiff wire, or blow out the tubes
through a straw inserted into the vent hole.
1.18 Indicators/Displays. During the course of the
inspection, confirm the operation of all lights,
indicators, meters, gauges, and visual displays
on the unit and charger, if so equipped. Verify
that all segments of a digital display function.
1.19 User Calibration/Self Test. Verify operation of
these features, where applicable.
1.20 Alarms. Operate the device in such a way as to
activate each audible and visual alarm. Check
that any associated interlocks function.
Check the action of the disconnected-probe
alarm, if the unit is so equipped. Also, if it has
alarms for open- or short-circuited patient temperature probes, test these with open- and shortcircuited probe plugs. If the device has an
alarm-silence feature, check the method of reset
(i.e., manual or automatic) against the manufacturer’s specifications.
1.21 Audible Signals. Operate the device to activate
any audible signals. Confirm appropriate volume, as well as operation of volume controls.
1.22 Labeling. Check that labels clearly and concisely identify the functions of all controls,
switches, and connectors. Because incubators
may administer supplemental oxygen, they
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Infant Incubators
should carry a WARNING — FIRE HAZARD
placard, since textiles, oils, and other combustibles ignite easily and burn intensely in oxygenenriched air. Exposing an infant to high oxygen
concentrations may cause retrolental fibroplasia
and possible blindness. Thus, incubator labeling
should also include the following: WARNING:
EXPOSING INFANTS TO ELEVATED OXYGEN CONCENTRATIONS MAY CAUSE
BLINDNESS.
If the device has an accessory outlet, check its
grounding to the main power cord.
2.2
1.23 Accessories.
Hood thermometer. Check the hood thermometer for cracked glass and separation of the
liquid column. If the liquid column has separated, it might be possible to consolidate it by
removing the thermometer and carefully dipping it in hot water. If the thermometer has
an expanded space at the top, the liquid will
pool in the small reserve chamber. When the
gap in the column disappears into the pool,
cool the thermometer and recheck it for column separations. Repeat the process if necessary. If the thermometer does not have
reserve space at the top, the heated liquid will
expand until it completely fills the thermometer, after which pressure will build up. The
pressure may eliminate the column separation, but it may also break the thermometer.
Even with a reserve space, overheating the
thermometer may break it. In either case, do
not heat the thermometer too fast or to too
high a temperature while attempting to consolidate the column. Replace the thermometer
if it is cracked.
Mattress. If the mattress position is adjustable,
check the ease of motion and security of the
locking mechanism. Examine the mattress for
cleanliness. If the unit is to be used in the
presence of flammable anesthetics, check that
a conductive mattress cover is being used.
2. Quantitative tests
2.1
Grounding Resistance. Using an ohmmeter,
electrical safety analyzer, or multimeter with
good resolution of fractional ohms, measure and
record the resistance between the grounding pin
of the power cord and exposed (unpainted and
not anodized) metal on the chassis. We recommend a maximum of 0.5 Ω. If the system is
modular, verify grounding of the mainframe and
each module.
Leakage Current. Measure the leakage current
to ground from the incubator chassis and, if the
unit has a battery charger, from the charger
chassis in all operating modes, including off, and
during battery operation. Measure while all accessories (e.g., examining and phototherapy
lamps) are operating. Chassis leakage should
not exceed 300 µA. (Note that the chassis leakage of transport incubators may vary with the
state of battery charge.)
Measure chassis leakage current with all accessories normally powered from the same line
cord connected and turned on and off. This includes other equipment that is plugged into the
primary device’s accessory receptacles, as well as
equipment plugged into a multiple-outlet strip
(“Waber strip”), so that all are grounded through
a single line or extension cord.
2.3
Temperature Control. Check the action of the
primary and safety thermostats with the incubator fully assembled. Although this is time-consuming, it is essential, since proper thermostatic
operation depends on the presence of normal
airflow patterns. Test the thermostats according to the manufacturer’s instructions, and record on the form the temperature at which the
safety or backup thermostat turns off the heater.
If the manufacturer does not provide instructions, use the following methods, which test both
manual and automatic temperature controls.
In the manual mode, the primary thermostat
cycles the heater on and off or provides proportional heating to maintain a constant hood temperature. The operator can adjust the
temperature by changing a setting. In the automatic mode, a patient probe senses the infant’s
skin temperature, and electronic circuits control
the heater to keep the skin temperature constant
at a clinically desirable level.
To test manual controls, position the calibrated glass or electronic thermometer 10 cm
(4 in) above the center of the mattress, close the
hood, set the temperature control to mid range,
allow the incubator to warm up to thermal equilibrium, and record the hood thermometer reading and the true mid-hood air temperature in
Item 2.7. Then, alternately raise and lower the
temperature setting. If the primary thermostat
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
5
Inspection and Preventive Maintenance System
is because the safety thermostat is often at some
distance from the mid-hood area, downstream in
the airflow, so that its temperature lags behind
the mid-hood air temperature. Also, avoid blowing hot air directly at the thermometers. If a
blower is used, deliver intermittent bursts of
heat and pause for thermal stabilization. Reconnect the primary thermostat that had been disabled in the above procedure (consult the
operator’s manual to determine the necessary
procedure).
is operating properly, the heater will turn on and
off, respectively.
To check automatic controls, first test the
accuracy of the patient-probe temperature indicator. Place the probe and a calibrated thermometer into a cup of water preheated to
approximately 35°C. Stir to reduce temperature
gradients, allow the temperature readings to
stabilize, and record the patient-probe temperature indication and the true bath temperature in
Item 2.8. If the two readings do not agree within
0.3°C, the probe may be defective. Substitute a
probe known to be accurate, and repeat the test.
If the two readings still disagree, the measuring
circuit or meter is defective and requires recalibration or repair.
2.6
Confirm the operation of the temperature control circuit by alternately dipping the probe into
cold and hot water, well below and above the
skin-temperature set point, respectively. The
heater should activate when the probe is cold and
turn off when the probe is hot.
2.4
Skin-Temperature Alarms. If the incubator is
equipped with high and low skin-temperature
alarms, verify that these alarms function. Adjust
the skin temperature set point to 36°C. Place the
sensor in the incubator and allow the temperature to stabilize. Remove the sensor from the
incubator, and verify that the low skin-temperature alarm activates.
To verify the high skin-temperature alarm,
place the sensor in a water bath set at 36°C and
gradually increase the water bath temperature.
Note the point at which the high alarm responds.
2.5
6
Safety Thermostat To test the operation of the
safety thermostat and the high-temperature
alarm, disable the primary thermostat or disconnect it from the control circuit (consult the manual to determine the necessary procedure) so
that the heater remains on continuously. In
some cases, this can be achieved by turning the
temperature control to its maximum setting. It
is possible to speed up the air-temperature rise
by supplementing the incubator heater output
with a hot-air gun or hair dryer. Record the hood
thermometer indication and the true mid-hood
air temperature at which the safety thermostat
and high-temperature alarm respond. Be careful
not to heat the hood air too rapidly with the
hot-air blower, or the mid-hood air temperature
at the alarm point will be erroneously high. This
Air-Temperature Alarms. If the incubator is
equipped with high and low air-temperature
alarms other than those that are controlled by a
secondary temperature controller, verify that
the alarms are functional. Adjust the air-temperature set point to 36°C and allow the air
temperature to stabilize. Verify that the low
air-temperature alarm (if so equipped) activates
when the incubator hood is opened.
To verify the high air-temperature alarm, set
the air-temperature set point to 36°C and slowly
increase the air temperature with an external
heat source (e.g., hair dryer or heat gun). Note
when the high alarm responds.
2.7
Hood Air Temperature. The mid-hood air temperature and hood thermometer readings taken
in Item 2.3 should agree within 1°C.
2.8
Patient Probe. The patient-probe temperature
indication and true water bath temperature, also
recorded during performance of Item 2.3, should
agree within 0.3°C.
2.9
Portable Power Supply (transport incubators
only). The portable power supply usually consists of a rechargeable battery, a recharging circuit, and associated wiring and connectors. It is
essential to keep all parts in good condition to
ensure the safe, effective operation of the transport incubator.
Battery types vary, and each requires a different inspection and preventive maintenance procedure. Types commonly used are lead-acid with
a liquid or sealed gelled-electrolyte, nickel-cadmium, and alkaline batteries. Sealed batteries
require less maintenance than types to which
fluid must occasionally be added to compensate
for evaporation.
Measure the specific gravity of lead-acid batteries with a hydrometer, but not while the battery is charging. If the battery is charging at
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Infant Incubators
inspection time, disconnect the charger and wait
at least 15 min before testing the battery. Before
taking a reading, rapidly fill and empty the hydrometer several times to thoroughly mix the electrolyte, taking care to avoid splashing or spilling.
The specific gravity of a fully charged battery
should be 1.265. (It may be necessary to check the
electrolyte level and measure the specific gravity
of lead-acid batteries as frequently as every two
weeks, depending on use and age of battery.)
If the liquid level is low, add distilled or
demineralized water to bring the level to the split
ring in each cell. Do not overfill. Excess water
may boil over and damage the battery case and
nearby charging circuits. If the battery has been
on a constant trickle charge and the specific
gravity is too low and battery voltage is lower
than 12.6 V, then the battery is defective or the
charger circuit is at fault. The charging circuit
may need readjustment.
If the incubator uses nickel-cadmium or
gelled-electrolyte lead-acid batteries, turn the
heater on after the batteries are fully charged,
and measure the voltage under load initially and
after 15 min of operation. Record the two values.
If the voltage decreases more than 10% during
this period, replace the battery.
3. Preventive maintenance
3.1
Clean the exterior and interior.
3.2
Lubricate the fan assembly if required.
3.3
Calibrate if needed.
3.4
Replace filter and battery if needed.
4. Acceptance tests
Conduct major inspection tests for this procedure
and the appropriate tests in the General Devices Procedure/Checklist 438.
Before returning to use
Set all controls to their normal positions.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
7
Procedure/Checklist 416-0595
Infusion Devices
Used For:
Infusion Controllers [11-010]
Infusion Pumps, Ambulatory [16-491]
Infusion Pumps, General-Purpose [13-215]
Infusion Pumps, Micro [16-722]
Infusion Pumps, Multichannel [17-634]
Infusion Pumps, Patient-Controlled Analgesic [16-924]
Infusion Pumps, Syringe [13-217]
Pumps, Enteral Feeding [13-209]
Commonly Used In: All patient care areas, homes
Scope: Applies to most types of electromechanical devices that regulate the delivery of fluids to a patient,
including general-purpose infusion pumps, multichannel pumps, microinfusion pumps, patient-controlled
analgesic (PCA) pumps, syringe pumps, ambulatory pumps, enteral feeding pumps, infusion controllers
Risk Level: ECRI Recommended, High; Hospital Assessment,
Type
ECRI-Recommended
Interval
Major
12 months
months
.
hours
Minor
NA
months
.
hours
Overview
Infusion devices are often used when accurate delivery
rates are required over long periods of time. Generalpurpose infusion pumps and controllers are used for
many of the same applications and have similar alarm
features. However, infusion pumps infuse under pressure, whereas controllers regulate a gravity infusion.
Most general-purpose infusion pumps have a flow
range of 1 to 999 mL/hr, while most controllers regulate
flow in a range of 3 to 300 mL/hr. Multichannel infusion
devices consist of two or more general-purpose pumps
and/or controllers within one chassis. Microinfusion
pumps are similar to general-purpose pumps but have
greater flow resolution and lower flow settings; they are
commonly used in neonatal critical care areas. PCA
pumps deliver pain medication on patient demand by
handswitch activation; they are programmed for drug
concentration and dose volume, lockout interval, and
maximum dose. Syringe pumps are typically used to
009060
416-0595
A NONPROFIT AGENCY
Interval Used
By Hospital
Time Required
infuse small volumes at rates less than 100 mL/hr by
depressing the plunger or sliding the barrel of a conventional syringe installed in the pump. Ambulatory
pumps are small and do not rely on line power or
gravity for operation. They are commonly used to infuse antibiotics, analgesics, chemotherapeutic agents,
and total parenteral nutrition solutions. Enteral feeding pumps are typically used to deliver enteral solution
or food mixtures to a patient’s stomach or small intestine through an enteral feeding tube.
Citations from Health Devices
Enteral feeding pumps [Evaluation], 1984 Nov; 13:9-30.
Infusion controllers [Evaluation], 1985 May; 14:219-56.
Undetected upstream occlusions in volumetric infusion pumps [Hazard], 1986 Jun; 15:182-4.
Syringe infusion pumps [Evaluation], 1987 Jan; 16:3-32.
5200 Butler Pike, Plymouth Meeting, PA 19462-1298, USA
Telephone +1 (610) 825-6000 ● Fax +1 (610) 834-1275
●
E-mail [email protected]
Inspection and Preventive Maintenance System
Ambulatory insulin infusion pumps [Evaluation], 1987
Nov; 16:351-76.
1. Qualitative tests
1.1
Chassis/Housing. Examine the unit for overall
condition. The chassis should be clean and free
from IV or enteral solution residue, especially
near moving parts (e.g., thumbwheel switches,
pump or controller mechanisms). Also check for
dried solution deposits on accessible air-in-line
sensors, pressure sensing mechanisms, and infusion set/cassette locking mechanisms. Check
that labels and markings are legible.
1.2
Mount. Screws and brackets that attach the
unit to an IV pole should be secure and functioning. If the device is mounted on a stand or cart,
examine the condition of the mount. Also examine the pole, stand, or cart.
1.3
Casters/Brakes. If the unit is mounted on a
dedicated IV pole, stand, or cart that moves on
casters, check their condition. Look for accumulations of lint and thread around the casters and
be sure that they turn and swivel, as appropriate. Check the operation of brakes and swivel
locks, if the unit is so equipped.
1.4
AC Plug/Receptacles. Examine the AC power
plug for damage. Attempt to wiggle the blades
to determine that they are secure. Shake the
plug and listen for rattles that could indicate
loose screws. If any damage is suspected, open
the plug and inspect it.
Patient-controlled analgesic pumps [Evaluation], 1988
May; 17:137-66.
General-purpose infusion pumps [Evaluation], 1989
Mar-Apr; 18:92-133.
Ambulatory infusion pumps [Evaluation], 1991 Sep;
20:324-58.
IV free-flow — still a cause for alarm [Perspectives],
1992 Sep; 21:323-8.
ECRI responds to FDA Public Health Advisory on IV
free-flow [Hazard], 1994 Jun; 23:256-7.
Test apparatus and supplies
General:
Ground resistance ohmmeter
Leakage current meter or electrical safety analyzer
At least one IV tubing set, cassette, syringe, and/or
other disposable specified for the pump or controller
being inspected
Fluid container of outdated (i.e., clinically unusable)
IV solution or degassed water
IV pole
Pressure meter (0 to 50 psi)
If the device or its IV pole has electrical receptacles for accessories, inspect them by inserting
an AC plug into each and checking that it is held
firmly. If accessories are plugged and unplugged
often, consider a full inspection of the receptacle.
U-100 insulin syringe and needle
For determining flow accuracy at settings ≥1 mL/hr:
50 mL graduated cylinder with 1 mL graduations
and stopwatch or watch with a second hand, or
Infusion pump analyzer
1.5
Line Cord. Inspect the cord for signs of damage.
If damaged, either replace the entire cord or, if
the damage is near one end, cut out the defective
portion. Be sure to wire the new power cord or
plug with the correct polarity.
1.6
Strain Reliefs. Examine the strain reliefs at
both ends of the line cord. Be sure that they hold
the cord securely.
1.7
Circuit Breaker/Fuse. If the unit has a switchtype circuit breaker, check that it moves freely.
If the unit is protected by an external fuse, check
its value and type against that marked on the
chassis, and ensure that a spare fuse is provided.
1.9
Cables. Inspect drop sensors and remote air-inline detector cables for general condition. Examine cables carefully to detect breaks in the
For determining flow accuracy at settings <1 mL/hr:
Electronic balance with a 200 g range and resolution
to 0.1 mg and small beaker, or
10 mL pipette with 0.1 mL graduations and vertical
mounting stand
Procedure
Before beginning an inspection, carefully read this
procedure and the manufacturer’s instruction and
service manuals; be sure that you understand how to
operate the equipment, the significance of each control
and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive
maintenance procedures or frequencies are recommended by the manufacturer.
2
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Infusion Devices
insulation. Ensure that they are gripped securely in the connectors at each end to prevent
rotation or other strain.
1.10 Fittings/Connectors. Examine any electrical cable connectors (e.g., drop sensor, nurse call) for
general condition. Electrical contact pins or surfaces should be straight and clean. Check any
spill-protection connector caps for signs of damage.
1.13 Controls/Switches. Before moving any control
switches, dials, or knobs, check their positions.
If any appear inordinate (e.g., volume-infused
counter or audible alarm level at the end of its
range), consider the possibility of inappropriate
clinical use or of incipient device failure. Record
the settings of those controls (e.g., occlusion pressure limits) that should be returned to their
original positions following the inspection. Examine all controls and switches for physical condition, secure mounting, and correct motion.
Where a control should operate against fixedlimit stops, check for proper alignment, as well
as positive stopping. Check membrane switches
for membrane damage (e.g., from fingernails,
pens). During the course of the inspection, be
sure to check that each control and switch performs its proper function.
1.17 Battery. Inspect the physical condition of batteries and battery connectors, if readily accessible.
Operate the unit on battery power during its
entire inspection to check that the battery has
been charged and can hold a charge. If a low-battery alarm occurs, check to ensure that it is
properly displayed and then continue the inspection using line power. Note how long the unit has
been operating and the conditions under which
the low-battery alarm occurred. Fully charge the
battery before returning the unit to use. When it
is necessary to replace a battery, label it with the
date.
1.18 Indicators/Displays. During the course of the
inspection, confirm the operation of all lights,
indicators, meters, gauges, visual displays, and
display backlighting, if so equipped. Be sure
that all segments of a digital display function.
(Many infusion devices automatically check indicator and display function when turned on or
during a manually activated self-test.)
1.20 Alarms. Many of the alarm capabilities of infusion pumps and controllers can be checked qualitatively. The following procedures include tests
for the most common alarm conditions. Check
the instruction manual to see how the alarm
should work. When an alarm occurs, check to see
that both audible and visual alarms are activated and that flow stops or is reduced to a
keep-vein-open rate (e.g., <5 mL/hr). Confirm
appropriate alarm volume, as well as the operation of any volume control.
Set up the infusion device according to the
manufacturer’s instructions, using an IV pole, a
container of outdated IV solution or degassed
water, and the specified IV set. Be sure that the
set is properly primed and that bubbles are removed.
Air-in-line. In some units, this alarm is the
same as the empty-container alarm. Test its
function by introducing a small air bubble into
the system by righting the fluid container
briefly or by injecting air into an injection port
of the IV tubing with a syringe between the
container and the air-in-line detector. (Sensitivity to air volumes of less than 50 µL is likely
to result in nuisance alarms; most devices will
trigger an alarm for greater than 100 µL air;
50 and 100 µL volumes can be approximated
by 5 and 10 units, respectively, from a U-100
insulin syringe.)
Empty container. Simulate an empty fluid container while the device is infusing. The simulation method will depend on the type of
sensor that is used in the alarm system. For
most units, turning the fluid container upright will cut off the supply, empty the tubing
leading from the container, and trigger the
alarm. For units that rely on a drop sensor or
an empty container detector to determine
fluid depletion, simply remove the sensor detector from the drop chamber.
Occlusion. See Item 2.11.
Infusion complete. If the total volume to be infused can be preset, set it to a low volume (e.g.,
10 mL), and operate the pump at a high-flow
setting.
Open door/misloaded infusion set. Check this
alarm during setup and operation.
Nurse call. Some pumps have a relay contact
closure that activates a nurse-call system
when an alarm condition occurs. This requires a special cable that connects the pump
to the nurse-call system. If the unit has this
capability and it is used in any clinical location, connect the cable, and simulate one or
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
3
Inspection and Preventive Maintenance System
more of the above alarm conditions to determine whether they activate the nurse call.
Alternatively, use an ohmmeter to check that
a change in resistance (either low to high or
high to low) occurs between the two conductors of the cable when an alarm condition is
created.
1.21 Audible Signals. Operate the device (e.g., press
rate switches) to activate any audible signals.
Confirm appropriate volume, as well as the operation of the volume control, if so equipped.
1.22 Labeling. Check that all necessary placards, labels, conversion charts, and instruction cards
are present and legible.
1.23 Accessories. Check the condition of external airin-line and drop sensors, if so equipped. Clean
sensors according to the manufacturer’s instructions. After cleaning the drop sensor, confirm
operation by passing a pen or finger between the
sensor while watching for activation of the drop
indicator, if present.
1.24 Flow-Stop Mechanism(s). Turn the power off
with the infusion set primed and loaded in the
device. With all tubing clamps open and the fluid
container two feet or more above the device,
verify that no fluid flows out of the set.
If the device incorporates a mechanism that
automatically closes the set or requires the set to
be manually closed before it is removed from the
device, verify the operation of this mechanism.
1.25 Lockout Interval. (This test applies only to PCA
pumps.) Program the unit for its minimum lockout interval (typically 1 to 5 min). Activate a
dose, and then verify that a second dose cannot
be activated until the programmed lockout time
has elapsed.
2. Quantitative tests
2.1
Grounding Resistance. Measure and record the
resistance between the grounding pin of the
power cord and exposed (unpainted and not anodized) metal on the chassis with an ohmmeter,
electrical safety analyzer, or multimeter with
good resolution of fractional ohms. We recommend a maximum of 0.5 Ω.
If the device or its IV pole has an accessory
outlet, check its grounding to the main power
cord.
4
2.2
Leakage Current. Measure leakage current between the chassis and ground with the grounding conductor temporarily opened. Measure
chassis leakage current with all accessories normally powered from the same line cord connected
and turned on and off. This includes other equipment that is plugged into the primary device’s
accessory receptacles, as well as equipment
plugged into a multiple-outlet strip (“Waber
strip”) so that all are grounded through a single
line or extension cord.
Chassis leakage current to ground should not
exceed 300 µA.
2.10 Flow Accuracy. It may be desirable to record the
type of tubing, pump chamber or syringe brand
and size (where user selectable), solution used,
and any other test variables to facilitate the
comparison of results with those obtained during
future inspections.
Flow settings ≥1 mL/hr: Use an infusion pump
analyzer or collect the output in a graduated
cylinder. Determine the flow accuracy at two
or more typical clinical flow settings (e.g., 10
and 100 mL/hr). (Choose the correct fluid code
when testing volumetric controllers.) Use a
stopwatch or a watch with a second hand to
time the delivery into the graduated cylinder
until at least 10 mL is collected. Record the
time interval and volume collected, and calculate the delivery rate in mL/hr.
Flow settings <1 mL/hr: If an electronic balance is available, gravimetrically determine
device accuracy by weighing a small beaker
(covered with a film of plastic wrap to minimize evaporative losses) before and after collecting a mass of at least 1.5 g. Convert the
mass to volume (1 g H2O = 1 mL; 1 g/mL can
be used for most other test solutions [e.g.,
normal saline], although the mass per unit
volume of some fluids may differ significantly). Divide the calculated volume by the
collection time in hours (e.g., 1.5 mL ÷ 15 hr
= 0.1 mL/hr). Follow this procedure to determine bolus volume accuracy of PCA pumps;
for pumps programmed in volume units (e.g.,
mL), collect and determine the average value
of three 1.5 mL boluses; for pumps programmed in mass units (e.g., mg), select a
concentration of 1.0 mg/mL and a 1.5 mg
bolus, and then collect and determine the
average value of three boluses.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Infusion Devices
alarm pressure(s). The maximum pressure of
newer pumps is typically 20 psi or less.
If an electronic balance is not available, use a
small length of rubber hose to connect the infusion
set to the base of a vertically mounted, graduated
5 mL pipette (resolution to 0.1 mL). Divide the
collected volume (1.5 mL, minimum) by the collection time to calculate the infusion rate.
Connect the distal end of the primed administration set to a pressure meter, and start the
infusion. Test alarm pressures at two commonly
used flow settings (e.g., 10 and 100 mL/hr). If the
pressures are outside the unit’s specifications,
consult the service manual for making the necessary corrections. For units that have adjustable occlusion alarm pressures, test at high and
low settings.
To calculate flow error, use the following
formula:
% Error =
Actual rate − Desired rate
× 100%
Desired rate
Exercise extreme care during measuring to
ensure accurate test results. Although most intravenous infusion pumps are specified to deliver within 5% of the flow setting, 10% is
acceptable for most applications; for critical applications, the error should not exceed 5%. (Note:
Negative and positive flow error represents underdelivery and overdelivery, respectively.) Expect greater delivery errors (up to 15%) with
enteral feeding pumps. Infusion controllers are
typically specified to deliver within 10% of the
flow setting or drop rate. Be sure that infusion
devices are used appropriately (e.g., infusion
controllers should not be used for critical intravenous infusions).
If the unit is designed to count drops and the
delivery rate can be set only in drops/min, do not
attempt to convert to mL/hr. Converting drops to
milliliters is complex and only grossly assesses
the device’s ability to deliver fluid volumes. Instead, operate the device for 3 to 5 min at a
midrange rate setting, and then count the drops
falling into the drip chamber for 2 min. Operate
the device for several more minutes, and repeat
the count. Calculate the number of drops per
minute for each trial, and average the two rates
if they are different. (Slight variations may be
due to the control circuitry correcting for errors.)
2.11 Maximum Pressure/Occlusion Alarms. (Exclude
infusion controllers from these tests because of
their inherently low operating pressures.) Determine the unit’s specified downstream occlusion
If the device delivers from an external fluid
container, verify upstream occlusion detection
by activating infusion with the tubing clamped
just below the container. (Some pumps do not
have this capability; see Health Devices 1986
Jun; 15:182-4.)
3. Preventive maintenance
3.1
Clean the exterior and the interior of the unit, if
required. Pay particular attention to solution
deposits on mechanical infusion control mechanisms, drop and air-in-line detectors, and occlusion or pressure-sensing mechanisms.
3.3
Calibrate per the manufacturer’s specifications.
3.4
Replace the battery, if necessary.
4. Acceptance tests
Conduct major inspection tests for this procedure
and the appropriate tests in the General Devices Procedure/Checklist 438. In addition, perform the following test.
4.1
Flow Accuracy. Determine flow accuracy at
minimum and maximum flow settings, following
the procedures in Item 2.10.
Before returning to use
Ensure that the unit’s battery is fully charged and
that the case is properly reassembled to minimize the
risk of fluid entry.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
5
Procedure/Checklist 432-0595
Intra-Aortic Balloon Pumps
Used For:
Circulatory Assist Units, Intra-Aortic Balloon [10-846]
Also Called: IABPs, counterpulsation units
Commonly Used In: Critical care units, catheterization labs, operating rooms
Scope: Applies to all intra-aortic balloon pumps; ECG and pressure monitors in these units should be inspected
using the appropriate Inspection and Preventive Maintenance Procedures
Risk Level: ECRI Recommended, High; Hospital Assessment,
Type
ECRI-Recommended
Interval
Interval Used
By Hospital
Major
6 months
months
.
hours
Minor
NA
months
.
hours
Time Required
Intra-aortic balloon pumps [Evaluation], 1987 May;
16:135-76. (See also 1987 Jun; 16:216.)
Overview
An intra-aortic balloon is placed in the descending
aorta and controlled by a complex electromechanical
system in an attempt to lower the pressure the heart
has to work against and to provide better coronary and
systemic perfusion.
Inaccurate blood pressure readings on IABP patients
[Hazard], 1989 Mar-Apr; 18:138.
Test apparatus and supplies
Intra-aortic balloon pumps have been used for several types of heart disease. Their most frequent and
successful use has been with cardiac surgery, applied
as a preoperative, intraoperative, or postoperative aid
to open-heart surgery; for patients with unstable angina who are not responding to medication and who
may be helped by revascularization surgery; as a precaution before revascularization surgery after arteriography has indicated a coronary lesion; in high-risk
patients (patients with left main coronary artery occlusion or poor left ventricular function); and for weaning
patients with low cardiac output from cardiopulmonary bypass.
Aortic simulator (see the “Test Equipment” section
of this binder)
Citations from Health Devices
Leak-detecting solution
Intra-aortic balloon pumps [Evaluation], 1981 Nov;
11:3-39.
Transducer connector (may be required to gain access
to monitor terminals) (acceptance inspection only)
093755
432-0595
A NONPROFIT AGENCY
Transducer simulator (or pressure transducer and
accurate pressure source); these devices were evaluated in Health Devices 1980 Jan; 9:59
ECG simulator
Leakage current meter or electrical safety analyzer
Ground resistance ohmmeter
Expendable supplies such as a stopcock and syringe
and other tubing and fittings for connecting test
equipment
5200 Butler Pike, Plymouth Meeting, PA 19462-1298, USA
Telephone +1 (610) 825-6000 ● Fax +1 (610) 834-1275
●
E-mail [email protected]
Inspection and Preventive Maintenance System
Isolation test supply; this feature may be included
in some electrical safety analyzers (acceptance inspection only)
accessories are plugged and unplugged often,
consider a full inspection of the receptacle.
1.5
Line Cord. Inspect the cord for signs of damage.
If damaged, replace the entire cord, or if the
damage is near one end, cut out the defective
portion. Be sure to wire a new power cord or plug
with the same polarity as the old one. Also check
line cords of battery chargers.
1.6
Strain Reliefs. Examine the strain reliefs at
both ends of the line cord. Be sure that they hold
the cord securely.
1.7
Circuit Breaker/Fuse. If the device has a
switch-type circuit breaker, check that it moves
freely. If the device is protected by an external
fuse, check its value and type against that
marked on the chassis, and ensure that a spare
fuse is provided.
1.8
Tubes/Hoses/Moisture. Check the condition of
all tubing in the unit. Be sure that tubing is not
cracked, kinked, or dirty. Check that tubing is
secured away from any elements that may become hot and that it has proper strain relief.
Clean or replace as necessary.
Procedure
Before beginning an inspection, carefully read this
procedure and the manufacturer’s instruction and
service manuals; be sure that you understand how to
operate the equipment, the significance of each control
and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive
maintenance procedures or frequencies are recommended by the manufacturer.
Since available intra-aortic balloon pumps differ
considerably and are relatively complicated life-support devices, be familiar with the operation of the unit
to be inspected. Inspection test methodology and criteria may vary from unit to unit; customize this procedure as required. For specific instructions on how to
perform tests or inspections, consult the operator’s
manuals or manufacturers. Record the hour meter
reading and (when applicable) note the software version before beginning the inspection.
1. Qualitative tests
1.1
Chassis/Housing. Examine the exterior of the
unit for cleanliness and general physical condition. Be sure that plastic housings are intact,
that all assembly hardware is present and tight,
and that there are no signs of spilled liquids or
other serious abuse.
1.2
Mount/Fasteners. If unit components (e.g.,
ECG, blood pressure monitors) are independent
modules on the console, check mounting of modules to ensure that they are securely attached.
1.3
Casters/Brakes. If the device moves on casters,
check their condition. Look for accumulations of
lint and thread around the casters, and be sure
that they turn and swivel, as appropriate. Check
the operation of brakes and swivel locks, if the unit
is so equipped. Conductivity checks, where appropriate, are usually done more efficiently as part of
a check of all equipment and furniture in an area.
1.4
2
AC Plug/Receptacles. Examine the AC power
plug for damage. Attempt to wiggle the blades
to determine that they are secure. Shake the
plug and listen for rattles that could indicate
loose screws. If any damage is suspected, open
the plug and inspect it. If the device has electrical
receptacles for accessories, insert an AC plug
into each and check that it is held firmly. If
Be sure no moisture has accumulated in the
pneumatic pathway. Inspect the patient isolation system, where applicable, for moisture. If
the isolation system is not transparent, briefly
operate the balloon pump with the tubing attached to determine if there is moisture in the
unit. See the operator’s manual for specific instructions on how to clear moisture. If moisture
is in the tubing, either dry it or replace the
tubing. After clearing moisture, inform IABP
users that moisture has accumulated during use
and instruct them to clear the system of moisture
after each use.
1.9
Cables. Inspect ECG electrode and pressure
transducer cables and any interconnecting cables between modules for neat and secure routing, condition, and strain reliefs. If additional
cables are provided for slaving pressure or ECG
signals to other units, check their function and
condition. Spare ECG and pressure cables
should be kept with the unit. Check cable (ECG
and blood pressure ports) on consoles to ensure
that connectors are in good condition (e.g., no
bent pins or cracked connectors).
1.10 Fittings/Connectors. Check the condition of all
gas manifolds, fittings, and connectors in the
pneumatic pathway. Examine all gauges and
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Intra-Aortic Balloon Pumps
valves for general condition. If leaks are suspected, check tubing and high-pressure regulator connections for leaks using a leak-detecting
solution. If pneumatic systems pass near electronic portions of the units, be careful not to spill
or drip the solution on electronic components.
may prove to be cost-effective, since it eliminates
most battery failures and the problems of unscheduled battery replacement. This is particularly true for transport models.) Where
appropriate, check the specific gravity of leadacid batteries.
1.11 Electrodes/Transducers. Verify that ECG electrodes and pressure transducers and disposable
domes, if used, are on hand and in good physical
condition.
Operate the unit on battery power for several
minutes to check that the battery is charged and
can hold a charge. Check that charging lights or
battery status meters are operative. Verify
automatic switchover to battery power, if provided. Check the condition of the battery
charger, and to the extent possible, confirm that
it charges the battery. When not in use, always
leave the unit plugged in so that batteries may
charge. The unit should be placarded LEAVE
PLUGGED IN AT ALL TIMES.
1.12 Filters. Check the condition of air filters in the
pneumatic pathway associated with the compressor or vacuum pump and filters associated
with fans for cooling electronic components.
Clean or replace as required and indicate this on
Lines 3.1 and 3.4 of the form.
1.13 Controls/Switches. Before moving any controls
and alarm limits, check their positions. If any of
them appear inordinate, consider the possibility of
inappropriate clinical use or incipient device failure. Record the settings of those controls that
should be returned to their original positions following the inspection. Examine all controls and
switches for physical condition, secure mounting,
and correct motion. Where a control should operate against fixed-limit stops, check for proper
alignment, as well as positive stopping. Check
membrane switches for membrane damage (e.g.,
from fingernails, pens). During the course of the
inspection, be sure to check that each control and
switch performs its proper function.
1.15 Motor/Pump/Fan. Inspect and confirm the
physical condition and proper operation of vacuum and pressure pumps, drive solenoids, and
cooling fans. Replace pump diaphragms, valves,
or gaskets, lubricate as required, and note this
on Lines 3.2 and 3.4 of the inspection form.
1.16 Fluid Levels. Check fluid levels in lead-acid batteries where appropriate. Check the fluid level
in the dome and syringe of the Mansfield (now
Boston Scientific) unit, and refill with distilled
or sterile water, if necessary. (The dome should
be full when the syringe is empty.)
1.17 Battery/Charger. Inspect the physical condition of batteries and battery connectors, if readily accessible.
Check operation of
battery-operated power-loss alarms, if so
equipped. Check the battery date code, if provided, for expiration. (Depending on how heavily your hospital relies on rechargeable batteries
for IABP operation, annual battery replacement
To further assess rechargeable battery capacity, most of the inspection procedure can be
performed with the unit operating on battery
power. Before operating the unit on battery
power for a prolonged period, be sure there is
adequate time for recharging or that an alternate unit is available.
If required, replace the batteries during the
inspection procedure (unless the operator’s manual requires more frequent replacement). When
it is necessary to replace a battery, label it with
the date.
1.18 Indicators/Displays. During the course of the
inspection, confirm the operation of all lights,
indicators, meters, gauges, and visual displays.
If the unit has digital displays, be sure that all
segments of the display function properly. Examine all regulators and pressure gauges or
meters for signs of damage or abuse.
1.19 User Calibration. Confirm that the ECG and
pressure monitors’ calibration functions operate
properly.
1.20 Alarms/Interlocks. Operate the device in such
a way as to activate audible and visual alarms
(e.g., heart rate, leak detectors, trigger loss, vacuum or pressure loss, trigger change, balloon
disconnect). Check the function of any associated
interlocks (e.g., balloon deflation).
1.21 Audible Signals. Operate the device to activate
any audible signals. Confirm appropriate volume, as well as operation of the volume control,
if so equipped. If audible alarms have been si-
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
3
Inspection and Preventive Maintenance System
that the diameter of the orifice through the Tpiece is not significantly smaller than the catheter diameter; otherwise, the back pressure
created by the restriction may trigger alarms on
some units. The test method will vary with the
model being tested. The following describes tests
appropriate for units currently in common use.
lenced, alert clinical personnel to the importance
of keeping alarms at the appropriate level.
1.22 Labeling. Check that all necessary placards, labels, timing adjustment charts, and instruction
cards are present and legible.
1.23 Accessories. Confirm the presence and condition
of safety chambers, patient isolator, and magnet
(i.e., for Mansfield [now Boston Scientific] “Telewire” transmitter).
Aries and Datascope pumps. Operate in Auto
mode. (Operation of the Aries in Manual and
the Datascope 90 in Manual-fill mode will
disable leak alarms.)
1.24 Gas Supplies. Check pressure of gas tanks;
make sure that the location of spares is placarded on the unit. If helium pressure is below
250 psi or if the IABPs indicate that the gas is
low, replace the gas tanks with full tanks and
arrange to have them refilled. If CO2 is used
with your unit, tanks should be replaced if the
pressure is below 850 psi. (Since CO2 maintains
a constant pressure of 850 psi at room temperature until all the liquid is converted to gas, a
pressure of less than 850 indicates that replacement is required.) Recheck the pressure after a
new tank is installed to verify that it is full and
that the gauge or meter is functioning properly.
Datascope and Mansfield (now Boston Scientific)
pumps. Withdraw gas in 1 cc increments until
a leak alarm sounds. Typically, 11 to 12 cc of
gas must be withdrawn before the units will
alarm. The Aries leak alarm circuitry is designed to trigger if the system detects a gas
leak rate exceeding 3 cc per min. Test the unit
by withdrawing gas at a rate of approximately
4 cc per min to verify that the alarm is operating. (At leak rates of 3 cc per min or less, the
Aries will automatically compensate for the
gas loss by repriming the system with helium.
Kontron IABPs are also designed to detect
leakage by leak rate; contact Kontron or consult the operator’s manual to determine the
appropriate rate for the model being tested.)
2. Quantitative tests
2.1
Grounding Resistance. Using an ohmmeter,
electrical safety analyzer, or multimeter with
good resolution of fractional ohms, measure and
record the resistance between the grounding pin
of the power cord and exposed (unpainted and
not anodized) metal on the chassis. We recommend a maximum of 0.5 Ω. If the system is
modular, verify grounding of the mainframe and
each module. If the device has an accessory outlet, check its grounding to the main power cord.
2.2
Leakage Current. Measure chassis current to
ground with the grounding conductor temporarily opened. Operate the device in all normal
modes, including on, standby, and off, and record
the maximum leakage current. Leakage current
should be 300 µA or less.
2.3
Pressure Monitor. Follow Item 2.10 in Blood
Pressure Monitors Procedure/Checklist 434.
2.4
ECG Monitor. Follow ECG Monitors Procedure/
Checklist 409. (If a pacemaker is incorporated
and is intended to be used, also follow External
Pacemakers Procedure/Checklist 418.)
2.5
Leak Detector. Using the aortic simulator, insert
a T-piece in the balloon catheter and connect a
25 cc syringe to the third port on the T. Be sure
4
2.6
Frequency Weaning. Check the operation of the
weaning control by applying a simulated ECG
signal and setting the unit for 1:1 pumping;
observe the response when the setting for pumping frequency is changed to alternate settings
(e.g., 1:2, 1:3). Verify that the frequency is what
is indicated on the control knob position.
2.7
Triggering/Timing. Using the aortic simulator
and an ECG simulator, confirm the proper operation of the controls for timing and triggering
of the balloon pumping on each unit. Set the
ECG simulator to a heart rate of 90 bpm and
observe the ECG signal on a monitor. Set timing
controls for several settings and confirm changes
in the balloon inflation point, inflation duration,
and the deflation point.
2.8
Driving System. Using a 40 cc balloon in the
aortic simulator, confirm proper vacuum and
pressure levels during operation at high heart
rates. Balloon should completely deflate and
inflate (depending on timing control position)
even at high rates (e.g., 120 bpm).
2.10 Volume Displacement. Set the IABP to fully inflate the 40 cc balloon in the simulator. Leave
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Intra-Aortic Balloon Pumps
the chamber open to the atmosphere, start the
pump, and observe the fluid displaced in the
simulator. It should be within 10% of the setting. Check displacement again at volumes of 30
and 20 cc. (Run the test with a low trigger rate
to aid in measuring the displacement.) Close the
chamber to the atmosphere and increase pressure in the simulator to 40 and then to 60 mm
Hg. Observe the displaced volume when fully
inflating the balloon. If significant decreases in
displaced volume occur (40%), the unit may not
pump effectively. Contact the manufacturer.
3. Preventive maintenance
3.1
Clean the exterior.
3.2
Lubricate per the manufacturer’s instructions.
3.4
Replace pump diaphragms, valves, gaskets, gas
line filters, ventilation filters, safety chambers,
and diaphragm isolators, if needed.
Check the number of hours of use since the last
inspection and the hours of use on safety chambers
(Datascope), VLDs (Aries), or diaphragm isolators
(Mansfield/Boston Scientific). Replace these according to the manufacturer’s recommendations (Aries
every 2,000 hours or every year; Datascope every 1,000
hours or by the expiration date; Mansfield/Boston Scientific every 250 hours). On the inspection form, note
the date installed and the hour meter reading at installation. Be sure clinical personnel know how to change
these components.
4. Acceptance tests
In addition to the tests described in the major inspection procedure, conduct the appropriate tests in
the General Devices Procedure/Checklist 438 and acceptance tests for ECG and blood pressure monitors
and pacemakers (ECG Monitors Procedure/Checklist
409, Blood Pressure Monitors Procedure/Checklist
434, External Pacemakers Procedure/Checklist 418).
In addition, perform the following test.
4.1
Compatibility with ECG and BP monitors. We
have received several reports of difficulties users
have experienced when trying to interface monitors with IABPs. While we generally recommend
against slaving IABPs off separate patient monitoring systems, we recognize that this is a relatively common practice. If your hospital
interfaces IABPs with monitors, verify that the
IABPs purchased are compatible with the monitors to which they may be connected. Using an
ECG or arterial pressure waveform simulator,
connect IABPs to monitors as they are commonly
connected in your hospital and attempt to trigger
the pump. (This type of test will not guarantee
equipment compatibility, but should identify
units that are grossly incompatible. As further
verification, contact the IABP manufacturer to
obtain its recommendations.)
Before returning to use
Make sure controls are set at normal positions and
that alarm volumes, if adjustable, are set loud enough
to be heard in the clinical setting. Verify that cooling
fans are drawing air through the console housing once
the panels are back in place. Be sure that the battery
is charged or the unit is charging. (Note: After running
the unit on battery during this inspection procedure,
it is prudent to allow the IABP to fully recharge before
returning the unit to use. Be sure that an alternate
IABP is available during the interim for clinical use.)
Place a CAUTION tag in a prominent position so that
the next user will be careful to verify control settings,
setup, and function before using. If any gas hoses were
removed or replaced during inspection or servicing, be
sure to verify that the unit works properly by attaching
and pumping a 40 cc balloon in the aortic simulator.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
5
Procedure/Form 439-0595
Isolated Power Systems
Used For:
Isolated Power Systems [15-817]
Line Isolation Monitors [12-361]
Also Called: Isolated power centers
Commonly Used In: Operating rooms and special care areas
Scope: Applies to isolated power systems with dynamic line isolation monitors; in addition, most items are
applicable to older static ground fault detectors, which usually do not have meters to monitor the total hazard
index but which will give audible and/or visual indication after the limit has been exceeded (exceptions noted
in the text)
Risk Level: ECRI Recommended, Low; Hospital Assessment,
Type
ECRI-Recommended
Interval
Major
6 months
months
.
hours
Minor
NA
months
.
hours
Isolated power systems are nonspecialized power distribution systems in which neither load conductor is
directly grounded and a detection device (a line isolation monitor [LIM] or ground fault detector) is incorporated to determine the extent of degradation of
isolation. These systems have been widely installed in
operating rooms and may also be found in other areas
of the hospital (e.g., critical care units, special procedures laboratories, emergency rooms). Until recently,
codes and standards have required their installation
in all anesthetizing locations.
Although appropriate applications of isolated power
systems continue to be debated, these systems are
currently required in operating rooms only if the operating room is not designated as a nonflammable anesthetizing location. Isolated power systems or
alternative protective mechanisms are also required in
“wet” (as defined in NFPA 99, 1993 Edition, Section
3-5.2.4) locations (such as hydrotherapy areas). Periodic inspection and appropriate record keeping is
A NONPROFIT AGENCY
Time Required
required for all installed systems, even in areas in
which they are not currently required.
Overview
009081
439-0595
Interval Used
By Hospital
Once isolated power systems are installed, their
performance is generally taken for granted, and degradation in isolation can go unnoticed. The front-panel
test button and the alarms on many systems will
indicate certain faults. However, we have examined
isolated power systems in which even these features
were not functioning properly.
NFPA requirements call for a monthly test that can
be easily accomplished using the front-panel test button.
The requirements also call for a more thorough inspection when the systems are first installed, after any
required maintenance, and semiannually thereafter.
Our inspection procedure meets these requirements.
The term “total hazard index” is used throughout this
procedure to refer to the meter reading on the LIM. This
term is commonly used to denote the current that the
meter predicts will flow through a line-to-ground short,
should one develop. The total hazard index is the greater
of the currents measured when a leakage current meter
5200 Butler Pike, Plymouth Meeting, PA 19462-1298, USA
Telephone +1 (610) 825-6000 ● Fax +1 (610) 834-1275
●
E-mail [email protected]
Inspection and Preventive Maintenance System
is connected, in turn, between each load conductor and
ground.
The terms “Line 1” and “Line 2” are used to refer to
the power-carrying (load) conductors of an isolated
system. The designation is strictly arbitrary and may
not appear on the wiring itself within the system. It
serves merely to establish a polarity convention. In
newer systems, one line is wired with orange insulated
wire; the other line has brown insulation.
Citations from Health Devices
Isolated power systems [Evaluation], 1974 Aug-Sep;
3:243-58.
Electrical safety analyzers [Evaluation], 1988 Oct;
17:283-309.
Isolated power systems [User Experience NetworkTM],
1988 May; 17:170-1.
Electrical outlets in anesthetizing locations, 1993 AugSep; 22:420.
Test apparatus and supplies
Isolated power system analyzer (optional for routine
inspections); can be a stand-alone device or one that
connects to a leakage current meter, electrical
safety analyzer, or voltmeter (see Special Precautions and Health Devices 1988 Oct; 16:283-309); if
used, many of the following items will not be necessary; for routine major inspections, a safely constructed test fixture with a single resistor (2W) and a
three-position switch — Line 1 to ground; off; Line 2
to ground — can be used (resistance value specified
in Item 7)
AC voltmeter for measuring line voltage
Leakage current meter or voltmeter capable of
measuring 10 to 500 mV
Adapters that plug into the power receptacles (e.g.,
parallel blade, twist-lock, explosion proof, x-ray)
used in the systems to be inspected, and allow safe
connection to test equipment without exposed conductive surfaces that could pose a shock hazard
Adapters that plug into the power receptacles (e.g.,
twist-lock, explosion proof, x-ray) used in the system
that have an exposed ground connection and can be
hooked to a trouble light or some other load to verify
the presence of AC power (120-240 V)
Grounding cable that plugs into special grounding
receptacles used in the system to be checked
Ground resistance ohmmeter (to avoid risk to patients in the area in which testing is being conducted
2
and in areas distant from the testing site, any device
used to determine ground quality or grounding resistance on occupied patient care areas must limit
the output to 500 mV RMS [1.4 V peak-to-peak] or
1.4 VDC; several test devices using different measurement methodologies are available; any of these
special-purpose devices, or simply an ohmmeter, is
satisfactory, so long as it meets the above output
limits and has adequate resolution and accuracy for
the test; for periodic measurement in existing construction, the measurement current can be either
AC or DC; an AC measuring source is required for
postconstruction tests)
Parallel-blade receptacle tension tester (optional)
Long lead with probe (long enough to reach from a
control grounding point to all areas of the room)
Special precautions
Because checking isolated power requires that
measurements be made on energized power lines, it is
possible for personnel to contact full line voltage. Isolated power systems deliver substantial currents
through line-to-line contacts, and, depending on the
condition of the system, contacts from line to ground
may yield hazardous currents. Exercise the same precautions used when testing or working with a conventional grounded system. We strongly recommend that
isolated power systems be inspected by a team of at
least two people so that, in the event of an accident,
one can summon help or begin CPR. The second person will also prove invaluable for testing remote indicator panels and circuit breakers.
In the past, it was necessary to use separate meters
and variable resistances that were interconnected
through a variety of test leads and adapters with the
isolated power system by the person(s) doing the inspection. Several manufacturers currently make devices that can be used in conjunction with electrical
safety analyzers, leakage current meters, and voltmeters to inspect isolated power systems. The use of
such devices significantly decreases the risk of shock,
expedites the inspection process, and alleviates the
need for many of the previously required extra wires
and adapters. Hospitals that intend to inspect isolated
power systems on a regular basis should purchase and
use these types of devices.
Never test isolated power supplies that serve operating rooms, catheterization labs, or special procedures rooms while procedures are underway. If it is
necessary to test systems in other areas of the hospital while patients are present, check with clinical
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Isolated Power Systems
pivots to nominal zero. (Note: The left end of the
scale corresponding to the de-energized meter
may not be labeled “0.”)
personnel to ensure that tripped circuit breakers will
not compromise patient support or safety in the area.
Procedure
4.
Alarms and Silencing Feature. Most LIMs have at
least two buttons or switches — one to test the
alarms and one to silence the audible alarms.
Actuate both to verify proper function. Record the
reading on the LIM when the alarm test button is
actuated. This value can be helpful in diagnosing
failures in the LIM (normally, it should advance to
the trip level). When the alarm-silence button is
actuated, there should be a visible indication
either that the system is still in alarm or that the
alarm is silenced. Remember to test all remote
indicators. Be sure that the audible and visual
alarms reset following this test. The audible alarm
may or may not automatically reset upon resolution of the alarm condition.
5.
Fuses. If the LIM has accessible fuses, examine
them for condition and rating. Their rating
should be placarded near the fuseholder. If it is
not placarded, do not assume that a fuse of the
correct value is installed; check the specifications for the LIM. Be sure that the fuseholders
are in good condition.
6.
Circuit Breakers. Examine and manually operate each primary and secondary circuit breaker
associated with the isolated power system. If the
circuit-breaker panel is usually locked, determine whether this is a necessary precaution. In
most cases, especially if the breakers are located
in the same room that they serve, a locked
breaker panel is inappropriate because it will
delay restoration of power following a fault.
7.
Confirmation of LIM Function. (Note: This test
does not confirm LIM accuracy and does not need
to be performed during acceptance testing when
Item 10 is conducted.) Connect a 24 kΩ resistance
(for 120 V system or 48 kΩ for a 240 V system)
between Line 1 and ground. Repeat the test with
this same resistance connected between Line 2
and ground. (An isolated power analyzer or a
calibrated, adjustable resistance can be used for
this test. However, it may be more convenient to
make a test fixture by wiring an appropriate plug
with a 24, or 48, kΩ resistor that can be switched
from ground to Line 1 or Line 2.) Confirm that
the visual and audible alarm indicators are activated for each of these connections. This test
confirms that an alarm will occur for a fault
that would result in a 5 mA hazard current. A
proportionately higher resistance may be used
The Universal Inspection Form is not applicable to
this procedure. Use the special Isolated Power System
Form 439.
For new installations, fill in the required identification information at the top of the form. This includes
nameplate data on the isolated power system, location
of remote indicators and alarms, and type of power
receptacle. In addition, list all fixed or permanently
connected equipment (e.g., overhead lighting, x-ray
view boxes, clocks) that is powered by the isolated
power system. A box is provided on the form to sketch
the layout of the room or area served by the isolated
power system to identify the location of defective components or receptacles. The sketch should provide
some orientation (e.g., location of bed or operating
table, doors). (An otherwise blank form, with this information filled in, can be copied for routine inspections; verify that no changes have been made since the
acceptance inspection. The sketch is not required if
receptacles are assigned identification numbers and
labeled during acceptance testing.)
Items 1 through 9 constitute a simple operational
check of the system to be performed routinely. These
and the remaining items constitute an acceptance procedure. Although they are listed separately for clarity,
checks of several items (e.g., lights, meters, alarms)
can be performed simultaneously.
Qualitative and quantitative tests
1.
Physical Condition. Check the physical condition of display and circuit-breaker panels, including indicators, meters, and circuit breakers.
Verify that they are not cracked or broken, that
they do not show signs of fluid entry, and that
viewing and access are not obstructed.
2.
Lights. Check all indicator lights, including any
remote indicators, to verify that they are functioning. It may be necessary to actuate the test
feature to check certain lights. Ensure that colored lenses over the indicator lights are intact.
If a light is burned out, replace it or note the type
on the inspection form to facilitate replacement.
3.
Meters. Be sure that the LIM meter is in good
condition. The needle should not be bent and
should advance smoothly when the test button
is pressed. If it is possible to disable the LIM
(e.g., by removing its fuse), check that the needle
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
3
Inspection and Preventive Maintenance System
Verify that each receptacle has power by plugging a lamp or trouble light into the receptacle
(a 240 V bulb is needed for x-ray outlets). Check
the grounding contact of each receptacle. A duplex to locking receptacle adapter (or duplex to
x-ray) may be required. It may be possible to
combine the grounding contact test with the
power test if a light with an accessible grounding
point is used.
for confirmation at the 2 mA level (e.g., 60 kΩ
for 120 V systems, 120 kΩ for 240 V systems). If
an analyzer with adjustable trip point adjustment is used, the alarm should activate at resistances at or above those specified here. If leakage
readings are used, the alarm should activate at
readings no greater than 5 mA (or 2 mA for
2 mA LIM).
8.
Receptacles. Check explosion-proof and x-ray
receptacles. Replace chipped or broken receptacles and cracked faceplates. Parallel-blade duplex receptacles can be checked either as part of
the isolated power inspection procedure or during routine inspection of duplex receptacles in
that area of the hospital (see Electrical Receptacles Procedure/Form 437).
For new construction, NFPA 99 requires
that the voltage limit between a reference
point and grounding contact of each receptacle
in the patient vicinity not exceed 20 mV. In
existing construction, the voltage should not
exceed 500 mV in general care areas and 40 mV
in critical care areas. However, voltages in
modern construction are usually <10 mV; voltages >20 mV may indicate a deteriorating condition and should be investigated. It should be
understood that these limits are not precise,
and differences of <20% should be considered
insignificant.
It is only necessary to record any defective
outlets that are found. If all outlets are satisfactory, check Pass. If the test is postponed because
it will be included as part of the receptacle inspection procedure, put a line through both the
Pass and Fail columns.
Measure ground potentials with a voltmeter
or leakage current meter. Leakage current readings can be converted to millivolts (mV) if the
leakage current meter’s impedance is known.
(Most leakage current meters have a 1,000 Ω
impedance at line frequency; the reading in µA
is then numerically equivalent to the voltage in
mV.) Connect one lead of the meter to a reference
ground point that is known to be securely
grounded. It is usually most convenient to use
the ground contact of one receptacle, but a
ground plug or structural member can also be
used. Do not use the cover plate screw, because
this may not be adequately grounded. Connect
the other lead to the ground contact of each
receptacle in turn.
Measure the retention force of parallelblade outlets with a receptacle tension tester.
Be sure that withdrawal of the tester from the
outlet is straight and smooth. Retention force
on the ground prong must be 4 oz or more.
Although measurement of retention force on
the power-carrying prongs is not required, we
recommend that this be measured. A retention force of 4 oz is also adequate for these
prongs, and forces of 2 to 4 oz are satisfactory
if the plug brand in use tends to stabilize at
this value and does not continue to deteriorate.
Replace any outlet with less than 2 oz retention force on any prong. (See Procedure/ Form
437 for additional information.)
A quantitative test of contact quality cannot
be made in most locking receptacles. Instead,
make a qualitative test of the power contacts
by plugging a movable floor lamp or trouble
light into the receptacle, either directly or
through an adapter (a 240 V bulb will be
needed for x-ray outlets). Jiggle the plug and
pull on it after it has been inserted and notice
whether the light flickers. The insertion and
removal of the plug should be smooth. If the
receptacle is explosion proof, check that the
lamp does not go on until the appropriate action is taken (e.g., twisting the plug in the
receptacle, rotating the cover plate).
4
Measure the resistance between the grounding terminal of the receptacle (accessed through
the adapter) and ground, and verify that it is <0.2
Ω (or 0.1 Ω in new construction) and does not
vary as the plug is jiggled in the receptacle.
9.
Grounding Jacks. Examine all installed
grounding jacks for general physical condition.
Insert a cable intended for that type of receptacle
to make sure that there are no obstructions (e.g.,
broken locking pins) in the receptacle or other
damage that prevents insertion or retention of
the plug.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Isolated Power Systems
Check ground potentials and resistance as
described in Item 8; the same criteria apply.
(24 to 48 kΩ for a 5 mA, 120 V system). If a
resistance higher than this value activates an
alarm, it is indicative of inadequate isolation. This
can result in nuisance alarms.
Acceptance tests
Items 10-14 should be done only after the system is
first installed or if major modifications or repair have
been performed on the system.
10.
If resistances significantly below the expected
value are required to generate an alarm, then
malfunction or miscalibration of the line isolation monitor is likely; this condition should be
corrected before the inspection continues.
Line Voltage. Line voltage tests are not required
by NFPA 99. These tests should be performed
following new construction, renovations, or major repairs to the electrical distribution system
to ensure that voltage taps are set correctly.
Testing after typical loads are applied or testing
in existing facilities may indicate poor wiring or
inadequate system capacity.
Static LIMs may not alarm until the resistance is about 20 kΩ, and LIMs with other alarm
levels may be encountered. Examine the specifications of these special systems; the systems
should operate within those specifications.
(If the hazard index is above 5 mA, do not
attempt the next step [measuring total hazard
current] unless your meter is protected against
line voltage.) Measure the resulting total hazard
current with the resistance in place on Line 1 by
switching the analyzer meter to read from Line
2 to ground (the LIM meter will go to full scale).
Record this current reading. This current
should not exceed 2 mA (5 mA on 5 mA systems)
and should agree, within 20%, with the LIM
meter reading before the leakage current meter
was connected. To satisfy current codes, it
should not be, under any circumstances, significantly higher than 5 mA.
Measure and record the output voltage of the
system between Line 1 and Line 2. The measured value should conform, within reasonable
limits, to the value specified on the nameplate.
Any significant deviation requires further investigation. However, it may reflect the relatively
poor accuracy of many AC voltmeters, so check
your meter before blaming the system.
11.
Alarm Levels. This test verifies that the alarm
will function when a suitable fault from one line
to ground occurs, verifies the accuracy of the LIM
meter, and provides a measure of the degree of
isolation from each line to ground.
Static ground fault detectors may have alarm
levels above 5 mA or more and may be beyond
the range of some meters. In addition, static
detectors do not recognize balanced faults.
Unplug all cord-connected equipment and
turn off all fixed equipment (e.g., x-ray view box)
from the system. Connect the analyzer and set it
to apply a resistance between Line 1 and ground.
Reduce the resistance from a high value (e.g.,
200 kΩ) until the alarm sounds. Record this
resistance value and the total hazard index (LIM
meter reading).
If the analyzer does not indicate the actual
resistance used during this particular test, it is
not imperative that this value be obtained and
recorded. However, it is important to perform
the procedure for determining system leakage
(Item 12) and to record system leakage values.
The resistance between a single power line and
ground that can cause an alarm varies, depending on the isolation of that line. The resistance
required to cause an alarm and the system leakage current are both indications of the isolation
of the system, and either value is sufficient.
For a 2 mA, 120 V system, resistance values
between 60 and 120 kΩ indicate adequate isolation
Older dynamic line isolation monitors scan
between Lines 1 and 2 at rates that can introduce
marked fluctuations in meter readings. When
the scanning rate is slow enough that two distinct readings can be distinguished on the meter,
record the greater of the two values. Otherwise,
record the average current.
Repeat this sequence of tests, connecting the
resistance from Line 2 to ground, adjusting it
until the alarm sounds, and measuring the total
hazard current from Line 1 to ground with a
leakage current meter.
12.
System Leakage. These measurements check
system integrity and give further information on
LIM meter accuracy. While not essential if Item
10 is performed, the information obtained may
be helpful in assessing a new installation and in
future troubleshooting. Comparing the readings
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
5
Inspection and Preventive Maintenance System
with values obtained in previous inspections
may indicate degradation of the isolation of
transformers, wiring, or other components.
mA for a 120 V system (1.2 mA for a 240 V
system).
13.
Record the hazard index indicated on the LIM
with the isolated power system on, all cord-connected devices unplugged, and individual branch
circuit breakers or switches integral to the unit
turned on. Installed lighting powered by the
system (e.g., overhead surgical lights, x-ray view
boxes) should be turned on or off, whichever
yields the higher hazard index.
Measure the system leakage with the line
isolation monitor connected. Connect the leakage current meter between Line 1 and ground
and note the reading. This represents leakage
caused by impedance from Line 2 to ground.
Repeat the measurement with the meter connected between Line 2 and ground. Record the
two values and compare the greater one to the
reading recorded for the LIM meter. A significant difference suggests a line isolation monitor malfunction. To ensure that there will be
adequate leeway on the system to cope with
connected loads, this value should be <1 mA for
2 mA systems and <2.5 mA for 5 mA systems.
If the fuses of the LIM can be removed, if the
grounding wire of the LIM can be disconnected,
or if the breaker serving the LIM can be turned
off, repeat system leakage measurements. This
value measures the collective leakage of installed wiring, transformer, and associated
components, but without the degradation of
isolation caused by the LIM; thus, it is a better
indication of wiring degradation. NFPA 99
states that the isolation must be >200,000 Ω;
therefore, system leakage (mA) should be <0.6
6
Grounding of Exposed Metal. NFPA 99-1993
calls for testing of installed, permanently attached, electrically conductive surfaces that
might become electrically energized and that
might be touched by the patient or persons
touching the patient. Testing is required following significant modifications and is recommended (but not required) at one-year intervals.
However, NEC (1993) no longer requires grounding of such surfaces. We recommend performing
this test after new construction and significant
modifications.
Tests and criteria are the same as for Item 8.
It is not necessary to be concerned about resistance to ground of isolated exposed metal as long
as the potentials measured above are acceptably low.
14.
Circuit Breaker Function and Labeling. Determine the correspondence between circuit breakers and receptacles. Turn off all secondary
circuit breakers and plug a light, voltmeter, or
other indicating device into one receptacle. Momentarily turn on one breaker at a time until the
breaker controlling the receptacle is identified.
Repeat this for all receptacles served by the
isolated power system. As you go through the
area, check that the receptacles and breakers are
labeled (preferably by numbering) to indicate the
relationship between them. This can facilitate
restoration of power should a breaker trip. If
they are not labeled, arrange to permanently tag
each receptacle with the number of the circuit
breaker that controls it. If more than one receptacle is served by a breaker, use letter suffixes
(e.g., 8A, 8B).
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Isolated Power Systems
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
7
Inspection and Preventive Maintenance System
8
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Procedure/Checklist 466-0595
Laparoscopic Insufflators
Used For:
Insufflators, Laparoscopic [16-849]
Also Called: CO2 Insufflators
Commonly Used In: Operating rooms, short procedure and ambulatory surgery areas
Scope: Applies to pneumatically and electronically controlled insufflators intended for introduction of CO2
or N2O gas into the peritoneal space. Does not apply to insufflators for hysteroflation (i.e., insufflation of the
uterus).
Risk Level: ECRI Recommended, Medium; Hospital Assessment,
Type
ECRI-Recommended
Interval
Major
12 months
months
.
hours
Minor
NA
months
.
hours
Overview
Insufflators are used to establish and maintain the
pneumoperitoneum during laparoscopic procedures.
Gas, typically CO2, introduced into the peritoneal cavity distends the abdominal wall to provide a viewing
and working space within the abdomen.
The primary function of the insufflator is to act as
a pressure-controlled gas flow regulator. The insufflator takes in compressed gas from a supply cylinder
(700 to 850 psi) or wall outlet (50 to 100 psi) and
delivers it to the patient, typically at 10 to 15 mm Hg
(0.2 to 0.3 psi). In pneumatic insufflators, abdominal
pressure control is accomplished by limiting the pressure of gas delivered to the patient. Electronic insufflators typically deliver gas at a pressure higher than
that desired in the pneumoperitoneum; these units
limit abdominal pressure by slowing and then suspending flow when intermittent abdominal pressure
measurements approach and reach a user-selected
pressure. For electronic insufflators to accurately
measure abdominal pressure, flow is briefly suspended so that pressure in the abdomen, insufflator
tubing, and the patient outlet port of the insufflator
234107
466-0595
A NONPROFIT AGENCY
Interval Used
By Hospital
Time Required
can stabilize, allowing the pressure in the transducer
inside the insufflator to equalize with the abdominal
pressure. Both pneumatic and electronic insufflators
feature controls for setting the pressure and maximum
flow rate. They feature displays, gauges, or other indicators for set and detected abdominal pressure and
flow, volume of gas consumed, and external gas cylinder pressure or volume remaining. In pneumatic insufflators, flow is typically specified as high or low. In
electronic insufflators, flow rates are specified either
as a time-averaged flow or as an instantaneous flow.
The maximum flow possible from a given insufflator
varies depending on flow resistance introduced by inline tubing filters and by the stopcock connection
through which the insufflator is connected to the
patient.
Citations from Health Devices
Laparoscopic insufflators [Evaluation], 1992 May;
21:143-73.
Entry of abdominal fluids into laparoscopic insufflators [Hazard], 1992 May; 21:180-1.
5200 Butler Pike, Plymouth Meeting, PA 19462-1298, USA
Telephone +1 (610) 825-6000 ● Fax +1 (610) 834-1275
●
E-mail [email protected]
Inspection and Preventive Maintenance System
Fatal gas embolism caused by overpressurization during laparoscopic use of argon enhanced coagulation
[Hazard], 1994 Jun; 23:257-9.
damage is near one end, cut out the defective
portion.
1.6
Strain Reliefs. Examine the strain reliefs at
both ends of the line cord. Be sure that they hold
the cord securely. If the line cord is detachable
(by the user), affix the cord to the unit so that it
cannot be removed by the operator. (See Health
Devices 1993 May-Jun; 22:301-3.)
1.7
Circuit Breaker/Fuse. If the device has an external circuit breaker, check that it operates
freely. If the device is protected by an external
fuse, check its value and type against that
marked on the chassis and ensure that a spare
is provided.
1.8
Tubes/Hoses. Check the condition of reusable
patient tubing and gas-supply hoses. Be sure
that they are not cracked, kinked, or dirty.
High-flow laparoscopic insufflators [Evaluation], 1995
Jul; 24:252-85.
Test apparatus and supplies
Leakage current meter or electrical safety analyzer
Ground resistance ohmmeter
Pressure meter or gauge (range 0 to 75 mm Hg;
mercury manometers are not suitable)
Large-bore (20 ga or larger) hypodermic needle
Empty 500 mL and 3 L (one each) IV and/or anesthesia solution bags with at least two ports
Trocar cannula or IV stopcock
Stopwatch or watch with second hand
Procedure
Before beginning an inspection, carefully read this
procedure and the manufacturer’s instruction and
service manuals; be sure that you understand how to
operate the equipment, the significance of each control
and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive
maintenance procedures or frequencies are recommended by the manufacturer.
1. Qualitative tests
1.1
Chassis/Housing. Examine the exterior of the
unit for cleanliness and general physical condition. Be sure that plastic housings are intact,
that all hardware is present and tight, and that
there are no signs of spilled liquids or other
serious abuse. Inspect the gas outlet port for
evidence of fluid entry, which can indicate contamination by body fluids.
1.2
Mount/Fasteners. If the device is mounted on a
stand or cart, examine the condition of the
mount. If it is attached to a wall or rests on a
shelf, check the security of this attachment.
1.4
AC Plug/Receptacles. Examine the AC power
plug for damage. Attempt to wiggle the blades to
check that they are secure. Shake the plug and
listen for rattles that could indicate loose screws.
If any damage is suspected, open the plug and
inspect it.
1.5
2
Line Cord. Inspect the cord for signs of damage.
If damaged, replace the entire cord or, if the
1.10 Pneumatic Connectors. Verify that the highpressure hose is pin-indexed for the appropriate
gas (e.g., CO2 or N2O).
Examine all external gas fittings and connectors, as well as electrical cable connectors, for
general condition. Electrical contact pins or surfaces should be straight, clean, and bright. Verify
that leads and electrodes are firmly gripped in
their appropriate connectors. Gas fittings should
be tight and should not leak.
1.11 Electrodes/Transducers. Confirm that any necessary electrodes and/or transducers are on
hand, and check their physical condition.
1.12 Filters. Check the condition of internal gas filters. Clean or replace as appropriate, and indicate this in Section 3 of the inspection form.
Follow the manufacturer’s recommended interval for service of internal filters (typically 2
years) and instructions for replacement.
1.13 Controls/Switches. Before changing any controls or alarm limits, check their positions. If any
settings appear inordinate (e.g., a pressure control at maximum), consider the possibility of
inappropriate clinical use or of incipient device
failure. Record the setting of those controls that
should be returned to their original positions
following the inspection.
Examine all controls and switches for physical
condition, secure mounting, and correct motion.
Check that control knobs have not slipped on
their shafts. Where a control should operate
against fixed-limit stops, check for proper
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Laparoscopic Insufflators
ment temporarily opened. Operate the device in
all normal modes, including on, standby, and off;
record the maximum leakage current.
alignment, as well as positive stopping. During
the course of the inspection, be sure to check that
eachcontrol andswitchperformsitsproperfunction.
Measure chassis leakage current with all accessories normally powered from the same line
cord connected and turned on and off. This includes other equipment that is plugged into the
primary device’s accessory receptacles, as well as
equipment plugged into a multiple outlet strip
(“Waber strip”) so that all are grounded through
a single line or extension cord.
1.18 Indicators/Displays. During the course of the
inspection, confirm the operation of all lamps,
indicators, meters, gauges, and visual displays
on the unit. Be sure that all segments of a digital
display function.
1.19 User Calibration. Verify that any calibration
function operates.
1.20 Alarms. Induce alarm conditions to activate
audible and visual alarms. Check that any associated interlocks function. If the unit has an
alarm silence feature, check the method of reset
(e.g., manual or automatic) against the manufacturer’s specifications. It may not be possible to
check out all alarms at this time, since some may
require abnormal operating conditions that will
be simulated later in this procedure.
1.21 Audible Signals. Operate the device to activate
any audible signals. Confirm appropriate volume, as well as the operation of a volume control
if so equipped. If audible alarms have been silenced or the volume set too low, alert clinical
staff to the importance of keeping alarms at the
appropriate level.
Chassis leakage current to ground should be
300 µA or less.
2.3
Set Pressure Accuracy. Connect the insufflator
to an empty 3 L solution bag. Introduce a largebore hypodermic needle through an injection
port on the bag. Connect the pressure meter or
gauge to the hypodermic needle, and measure
the gas pressure in the bag after it has stabilized.
Measurements should be taken at maximum,
minimum, and a pressure setting in the range of
12 to 15 mm Hg and should be within 3 mm Hg
of the pressure setting.
2.4
Displayed Pressure Accuracy. During the preceding test (Item 2.3), compare the displayed
pressure with pressure measured with the
pressure meter or gauge; displayed pressure
should be within 3 mm Hg of the measured
pressure. Manually compress the bag to produce pressure in excess of the set pressure, and
verify that displayed pressure remains within
3 mm Hg or 10% of measured pressure, whichever is greater.
2.5
Pressure Relief Mechanism. An insufflator
should limit delivered pressure to a manufacturer-specified maximum value. In addition to a
pressure-relief valve, some units also have vents
that are electronically opened if the detected
pressure exceeds a threshold value (e.g., 30 mm
Hg) or if the detected pressure exceeds the selected pressure by a certain value. In many
cases, these vents activate after a delay of several seconds. With the insufflator connected to a
filled 3 L solution bag, manually compress the
bag so that pressure is slowly increased 5 mm Hg
at a time until pressure relief is activated. Note
the bag pressure at which pressure relief occurs
as indicated by the pressure meter or gauge also
connected to the bag.
2.6
High-Pressure Alarms. During the preceding
two tests (Items 2.4 and 2.5), note the bag
1.22 Labeling. Check that all necessary placards, labels, conversion charts, and instruction cards
are present and legible.
2. Quantitative tests
2.1
Grounding Resistance. For line-powered units,
use an ohmmeter, electrical safety analyzer, or
multimeter with good resolution of fractional
ohms to measure and record the resistance between the grounding pin of the power cord and
exposed (unpainted and not anodized) metal on
the chassis. We recommend a maximum of 0.5 Ω.
If the system is modular or composed of separate
components, verify grounding of the mainframe
and each module or component. If the device is
double insulated, grounding resistance need not
be measured; indicate “DI” instead of the ground
resistance value.
If the device has an accessory receptacle,
check its grounding to the main power cord.
2.2
Leakage Current. For line-powered units, measure chassis leakage current to ground with the
grounding conductor of plug-connected equip-
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
3
Inspection and Preventive Maintenance System
set intended for use with the insufflator, and
compare it to the flow established for that unit
during acceptance testing. Insufflators should
have a setting that delivers flow in the range of
1 to 2 L/min. For this test, compute the flow using
the following formula:
pressures at which intermittent and continuous
audible alarms and visual indicators are activated.
2.10 Maximum Flow. With the insufflator set to its
maximum flow setting, measure the time required to fill a 3 L solution bag to a typical
pressure setting (e.g., 15 mm Hg) through the
tubing/filter set intended for use with the insufflator, and compare it to the flow established for
that unit during acceptance testing. For this test,
compute the flow using the following formula:
flow (L⁄min) =
(3 L) × (60 min)
fill time (sec)
sec⁄
(This measurement may differ markedly from
the manufacturer’s specified maximum flow rate
if it is specified as an instantaneous flow or is not
adjusted for flow resistance of the tubing set and
filter. It is important to minimize flow resistance
in the connection between the insufflator tubing
set and the reservoir bag [e.g., do not use a
Veress or hypodermic needle for this connection].
If a trocar cannula or IV stopcock is used for this
connection, it should be maintained as a permanent test device because flow resistance of stopcocks and cannulae varies significantly.)
2.11 Low Flow. With the insufflator set to minimum
flow setting, measure the time required to fill a
500 mL IV reservoir bag to a typical pressure
setting (e.g., 15 mm Hg) through the tubing/filter
4
flow (L⁄min) =
(0.5 L) × (60 sec⁄min)
fill time (sec)
3. Preventive Maintenance
3.1
Clean the exterior (interior, if required).
3.2
Lubricate per the manufacturer’s instructions.
3.3
Calibrate pressure settings, if required.
3.4
Replace filters, if required.
4. Acceptance tests
Conduct major inspection tests for this procedure
and the appropriate tests in the General Devices Procedure/Checklist 438.
Before returning to use
Ensure that all controls are set properly. Set alarms
loud enough to alert personnel in the area in which the
device will be used. Other controls should be in their
normal pre-use positions.
Attach a Caution tag in a prominent position so that
the user will be aware that control settings may have
been changed.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Procedure/Checklist 467-0595
Mammography Units
Used For:
Radiographic Units, Mammographic [12-425]
Commonly Used In: Radiology departments, breast clinics
Scope: Applies to mobile and stationary screening x-ray mammography units that use a screen-film receptor;
xeroradiographic and digital receptor systems are not covered here specifically, although many of the following
tests will apply to these systems; biopsy systems are also not covered in this procedure
Risk Level: ECRI Recommended, High; Hospital Assessment,
Type
ECRI-Recommended
Interval
Major
12 months
months
.
hours
Minor
6 months
months
.
hours
Overview
Mammography units use x-rays to produce a film image
of the breast (a mammogram) that provides information about breast morphology, normal anatomy, and
gross pathology. Mammography is primarily used to
detect and diagnose breast cancer, as well as to evaluate
palpable masses and nonpalpable breast lesions.
A mammographic radiographic system consists of
an x-ray generator, an x-ray tube, a positioning assembly, a compression system, a Bucky grid to reduce
scatter radiation, a radiation shield, and an image
recording system. X-ray generators for mammography
are usually high-frequency (they convert the 50- or
60-cycle input voltage to a frequency as high as 100
kilohertz) or constant-potential (they supply a ripplefree, continuous voltage to the x-ray tube, regardless
of the input power). For screen-film mammography,
the kilovoltage (kV) settings range from 20 to 35 kV;
this narrow range accentuates the subtle density differences in breast tissue.
X-rays are produced by the x-ray tube, which usually
has a rotating anode that dissipates heat produced during exposure. A molybdenum (Mo), tungsten (W), or
rhodium (Rh) target on the anode receives the electron
237588
467-0595
A NONPROFIT AGENCY
Interval Used
By Hospital
Time Required
beam from the cathode and emits x-rays. Mo, aluminum (Al), and/or Rh filters are placed in the path of
the x-ray beam to absorb unwanted x-rays. The x-rays
that pass through the filter are shaped by a collimator or by cone apertures. Currently, five target/filter
combinations for screen-film mammography are
available: Mo/Mo, W/Mo, W/Rh, Mo/Rh, and Rh/Rh.
The target/filter combination selected for imaging
depends on the thickness and density of the breast
after compression.
An automatic exposure control (AEC) device is
used to terminate x-ray generation when a radiation
sensor behind the film cassette senses the proper
exposure. AEC devices can automatically compensate for technique variance and patient anatomy
(breast thickness), thereby reducing radiation exposure and retakes.
The positioning assembly is capable of vertical and
rotational movement to adjust for different patient
heights and breast sizes and to permit the acquisition
of images from various angles around the breast
(e.g., craniocaudal, mediolateral). A compression system, either automatic or manually operated, is used to
uniformly reduce the thickness of the breast to facilitate
5200 Butler Pike, Plymouth Meeting, PA 19462-1298, USA
Telephone +1 (610) 825-6000 ● Fax +1 (610) 834-1275 ● E-mail [email protected]
Inspection and Preventive Maintenance System
x-ray beam penetration and maximize the amount of
tissue imaged.
In screen-film mammography, the image recording
system uses high-detail fluorescent screens that convert x-rays to light photons and that are in contact with
a single- or double-emulsion film. Xeromammography,
a method of electrostatic image recording using
charged photoconductive plates, is still available on
some mammography units.
Citations from Health Devices
Mammography units [Evaluation], 1989 Jan; 18(1):3-53.
Quality assurance in screening mammography [Clinical perspective], 1990 May-Jun; 19(5-6):152.
Mammography units [Evaluation], 1990 May-Jun;
19(5-6):153-98.
Test apparatus and supplies
Ground resistance ohmmeter
Wear a lead apron during all radiation testing and
maintain a safe distance between yourself and the
x-ray tube. It should not be necessary to place hands
or fingers in the x-ray beam; if this is unavoidable,
wear lead gloves. For repeated exposures, as required
by some of the tests in this procedure, allow adequate
time between exposures to prevent the x-ray tube from
overheating. Do not remove high-voltage cables from
the wells with the power on. When removing them,
ensure that the cables are completely discharged by
repeatedly contacting the conductor to the ground as
soon as the cables are removed from the wells.
For tests of the AEC and of image quality, it is
imperative that an optimally performing film processor be used. This film processor should be the one that
is normally used to process all mammograms. Also, the
technical tests should be undertaken using the same
screen-film combination that is used for acquiring
mammograms.
Leakage current meter or electrical safety analyzer
Procedure
Noninvasive mammographic kVp meter
Before beginning an inspection, carefully read this
procedure and the manufacturer’s instruction and
service manuals; be sure that you understand how to
operate the equipment, the significance of each control
and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive
maintenance procedures or frequencies are recommended by the manufacturer.
Noninvasive timer (may be included with the kVp
meter)
Ionization chamber with electrometer, or a combination exposure meter, capable of making exposure
measurements in the mammography energy range
and specifically calibrated for this purpose
Five high-purity (>99%) aluminum filters measuring 10 cm × 10 cm × 0.1 cm
10 cm of stiff wire
Four coins or lead markers
One dozen sheets of 18 cm × 24 cm mammography
film from same batch
One dozen sheets of 24 cm × 30 cm mammography
film from same batch
One 18 cm × 24 cm mammography cassette with
screen
One 24 cm × 30 cm mammography cassette with
screen
Densitometer
Ten pieces of 15 cm × 15 cm × 1 cm plexiglass
American College of Radiology (ACR) accreditation
mammography phantom
Oscilloscope (calibration only)
High-voltage divider (calibration only)
2
Special precautions
This procedure is intended to ensure adequate system performance and maintenance. It should not be
construed as providing full compliance with the requirements of all governmental regulations and accreditation standards of professional associations.
Such regulations and standards may include testing
beyond that provided below and may also require documentation by a certified medical physicist.
For acceptance testing, we strongly recommend contracting with a medical physicist. Acceptance testing
is crucial because it generates data on baseline performance of the device.
1. Qualitative tests
1.1
Chassis/Housing. Examine the exterior of the
mammography unit for cleanliness and general
physical condition. Be sure that all hardware is
present and secure and that there are no signs of
serious abuse. Check the movements of the Carm assembly, both for rotation and vertical
movements, ensuring that all of its movements
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Mammography Units
are smooth and that the locks function adequately. Also check during these tests that the
film cassette is retained securely but that it is
not difficult to insert or remove. Check the condition of the operator shield and the patient face
shield.
1.2
Mounts/Fasteners. Ensure that the mammography unit is securely mounted on the floor so
that it is not likely to become unstable when a
patient is leaning on the breast platform or when
the technologist is moving the C-arm assembly.
1.3
Casters/Brakes. For mobile mammography
units, verify that the wheels turn and swivel, as
appropriate, and look for accumulations of dirt
and grime around the wheels. Also, check the
operation of brakes and the adequacy of the park
positions of the C-arm assembly and of any other
components likely to move during transport.
1.4
1.5
AC Plug/Receptacles. For line-powered mammography units, examine the AC power plug for
damage. Attempt to wiggle the blades to check
that they are secure. Shake the plug and listen
for rattles that could indicate loose screws. If any
damage is suspected, open the plug and inspect
it. If the unit has electrical receptacles for accessories (e.g., printers), verify the presence of line
power and insert an AC plug into each and check
that it is held firmly. If accessories are plugged
and unplugged often, consider a full inspection
of the receptacles.
Line Cord. Inspect the cord for signs of damage.
If damaged, replace the entire cord or, if the
damage is near one end, cut out the defective
portion. Be sure to wire a new power cord or plug
with correct polarity. Also check line cords of
battery chargers.
1.6
Strain Reliefs. Examine the strain reliefs at
both ends of the line cord. Be sure that they hold
the cord securely.
1.7
Circuit Breaker/Fuse. If the device has an external circuit breaker, check that it operates freely. If
the device is protected by an external fuse, check
its value and type against that marked on the
chassis and ensure that a spare is provided.
1.9
Cables. Inspect any cables (e.g., from the AEC
detectors to the generator, cable to footswitches)
and their strain reliefs for general condition.
Carefully examine cables to detect breaks in the
insulation and to ensure that they are gripped
securely in the connectors at each end to prevent
rotation or other strain. Verify that there are no
intermittent faults by flexing electrical cables
near each end and looking for erratic operation
or by using an ohmmeter.
1.10 Fittings/Connectors. Examine all electrical cable connectors for general condition. Electrical
contact pins or surfaces should be straight,
clean, and bright. Verify that leads and electrodes are firmly gripped in their appropriate
connectors. If keyed connectors are used, make
sure that no pins are missing and that the keying
is correct. Also, check the mechanical connections, particularly of the compression paddles
and of the magnification platforms. Ensure that
the connections permit safe and adequate attachment of these devices.
1.13 Controls/Switches. Before changing any controls or alarm limits, check their positions. If any
settings appear inordinate (e.g., very large preset
density change or a kVp that is too low), consider
the possibility of inappropriate clinical use or of
incipient device failure. Record the setting of
those controls that should be returned to their
original positions following the inspection.
Examine all controls and switches (x-ray initiation, technique selection, filter selection, focal
spot selection, compression and decompression
switches, preset density change, etc.) for physical condition, secure mounting, and correct motion. Check that control knobs, if present, have
not slipped on their shafts. Where a control
should operate against fixed-limit stops, check for
proper alignment, as well as positive stopping.
During the inspection, be sure to check that each
control and switch performs its proper function.
For the radiographic exposure switches, ensure that they do not stick and that continuous
pressure is required to continue exposure. Release of pressure should immediately terminate
exposure. Also pay close attention to the operation of the compression and decompression
switches. Ensure that, where provided, automatic decompression follows exposure.
1.15 Motor/Pump/Fan/Compressor. Check the physical condition of the motor-driven compression
mechanism. Also, ensure that the cooling fan in the
tube head assembly is clean and operates adequately. Clean and lubricate if necessary and note
this in Items 3.1 and 3.2 of the inspection form.
1.18 Indicators/Displays. During the inspection,
confirm the operation of all lamps, indicators,
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©1995 ECRI. All Rights Reserved.
3
Inspection and Preventive Maintenance System
meters, gauges, and visual displays on the unit.
Examples of indicators and displays are technique settings, choice of focal spots, filter in use,
breast thickness, source-to-image distance
(SID), and C-arm rotation indicators. Include
checks of the light field in this test.
1.20 Alarms. Induce conditions to activate audible and
visual alarms (for example, x-ray exposure, backup
timer activation). Check that any associated interlocks (e.g., no exposure if there is no film cassette
in the Bucky) function. If the unit has an alarm
silence feature, check the method of reset (e.g.,
manual or automatic) against the manufacturer’s
specifications. It may not be possible to check out
all alarms at this time, since some may require
abnormal operating conditions (e.g., long exposure
times). Instruct users to document activation of
these alarms to ensure that they are functional.
2.2
Leakage Current. For mobile mammography
units, use a safety analyzer to measure leakage
current. The chassis leakage current to ground
should not exceed 300 µA. Note that for existing
mobile units, leakage currents of up to 500 µA are
deemed not to pose a hazard, but, if the leakage
current is between 300 and 500 µA, a documented
maintenance schedule should be implemented to
ensure the integrity of the grounding connection.
Permanently wired equipment should be tested
before installation. With all grounds lifted, leakage current should not exceed 5 mA.
2.3
Accuracy of kVp. Use a noninvasive kVp meter
capable of making measurements in the mammographic energy range. The kVp meter should
have been previously calibrated against a highvoltage divider on the type of generator that powers the mammography unit. Use the kVp meter in
accordance with the recommendations of the meter’s manufacturer (e.g., the distance at which the
kVp meter has to be placed).
1.21 Audible Signals. Operate the device to activate
any audible signals (for example, radiographic
exposure). Confirm appropriate volume.
Make measurements at a minimum of three
kVp settings that span the range normally used
at your facility. For units that have two focal
spots, measurements should be made using each
focal spot at the tube current setting appropriate
for the focal spot in use. After appropriate corrections have been applied to the measured kVp
readings (e.g., for filtration), the measured kVp
should be within ±5% of the preset kVp.
1.22 Labeling. Check that all necessary certification
labels, warning labels, technique charts, and
instruction cards are present and legible.
1.23 Accessories. Confirm the presence and condition
of accessories (e.g., full and spot compression
paddles, grids, magnification platform, diaphragms, and cones).
2. Quantitative tests
2.1
Grounding Resistance. Using an ohmmeter,
electrical safety analyzer, or multimeter with
good resolution of fractional ohms, measure and
record the resistance between the ground pin (or
the ground for hard-wired systems) and the accessible conductive surfaces on the mammography unit. The resistance should not exceed
0.5 Ω. Handswitches and footswitches that are
powered from low voltages need not be grounded.
Although confirmation of grounding integrity
provides reasonable assurance of safety, NFPA
99 calls for voltage measurements for installed
devices in the patient vicinity. Using a voltmeter,
measure and record the voltage between a reference grounding point (e.g., the grounding pin of
an electrical receptacle or some other known
ground) and exposed (i.e., unpainted and not
anodized) metal on the chassis. A voltage reading below 500 mV is acceptable for general care
areas in existing construction.
4
If a consistent significant error between the
preset kVp and the measured kVp is detected,
further testing with a high-voltage divider may
be required to identify the problem.
2.4
Timer Accuracy. Use a noninvasive timer to
measure the accuracy of the time settings. If the
noninvasive kVp meter also displays exposure
times, it is acceptable for this test. Follow the
manufacturer’s recommended technique for
making time measurements.
Measure at a minimum of three time settings
spanning the range normally used at your facility.
For all measurements, use a fixed tube voltage
setting of 28 kVp. If the time settings are not
displayed on the mammography unit, calculate
them from the mAs values by factoring out the mA
the unit uses at 28 kVp for that focal spot. Make
measurements for both focal spots, where available. The difference between the measured time
and the preset time should not exceed ±1 msec or
±5% of the preset time, whichever is greater.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Mammography Units
2.5
mR with no added filters in the beam. These kVp,
mAs values should be held constant during the
whole course of this test.
Linearity of mAs. Use an ionization chamber
with an electrometer (or a combination exposure
meter) to measure the exposure in mR for this
test. The devices should have been specifically
calibrated using mammographic energy ranges.
The ionization chamber should be placed centrally
in the x-ray beam, with the compression paddle
removed.
Record the initial exposure value (in mR)
with nothing in the primary beam (i.e., 0 mm of
aluminum). Then add aluminum filters in 0.1
mm steps up to a total of 0.5 mm, and obtain an
exposure reading for each 0.1 mm addition. Plot
mR values against aluminum thickness on
semilog paper (mR vertically on log scale). Read
the amount of aluminum thickness required to
drop the initial mR value by 50%. This is the
HVL. The measured HVL should comply with the
following equation:
Dial up a midrange kVp setting (e.g., 28 kVp).
Make radiographic exposures at this fixed kVp,
using a minimum of at least three mAs settings
that span the range normally used. Record the
exposure values (in mR) from the electrometer or
exposure meter for each exposure. Calculate the
mR/mAs for each exposure and average the calculations. Each individual mR/mAs value should
be within ±10% of the average mR/mAs value.
2.6
Exposure Reproducibility. Use one of the above
mR/mAs values at 28 kVp as the one value to be
used for evaluating short-term and long-term
reproducibility of the mammography unit. For
the short-term test, make a minimum of four
exposures at the same mAs over a span of 15
minutes. The mR/mAs values should have a coefficient of variation no larger than 5%. For
long-term reproducibility, simply mark the current average mR/mAs value on a trend chart
together with values recorded at previous tests.
HVL ≥ [(kVp/100) + 0.03] mm Al
For example, at 28 kVp, the HVL should be a
minimum of 0.31 mm of aluminum. Previous
HVL values should be compared with the current
measurement; a change in HVL may indicate
tube deterioration.
2.8
It is critical that identical test conditions
(e.g., same chamber-electrometer, chamber at
same distance from focal spot, same technique,
absence of compression paddle) be maintained
for accurate assessment of long-term reproducibility. Long-term reproducibility should be
within ±5% of the average.
2.7
Half-Value Layer (HVL). Use high-purity aluminum filters for this test. This test should be
conducted with the compression paddle in place
and at a kVp setting commonly used to image a
compressed breast 4 cm thick so that the derived
HVL may be used to calculate the average glandular dose (see Item 2.14). Position the compression paddle as close as possible to the x-ray tube.
Place the ionization chamber on the cassette
table, roughly 4 cm in from the patient edge of
the table. Collimate the beam so that only the
sensitive area of the chamber is fully exposed.
Check this with the light field. Set the mammography unit to operate at the kVp setting that
would be commonly used to image a compressed
breast 4 cm thick (e.g., 28 kVp). Select the mAs
value that produces an exposure of around 500
Collimation. Place an 18 cm × 24 cm film cassette
in the cassette tray. Place a larger nonscreen film
(24 cm × 30 cm) on top of the cassette table, such
that it extends beyond the patient edge of the
cassette table by about 4 cm. Position a 10 cm stiff
wire on the larger film such that it is aligned with
the patient edge of the cassette table. Next, turn
on the light field and place one coin at each of the
other three sides of the field defined by the light
field. The outer edges of the coins should mark the
edges of the light field. Finally, place a fourth coin
in the bottom left corner of the light field to provide
orientation information. (See Figure 1 for wire
and coin placement.)
Record the SID in use on the mammography
unit. Then make an exposure and process both
films. On the 18 cm × 24 cm film, ensure that no
area beyond the outer edges of the coins can be seen
on the film. On the larger film, measure the distance from the wire edge to the edge of the x-ray
field. This distance should be no greater than 2%
of the SID. Note that this 2% criterion is valid only
for the side that is adjacent to the patient’s chest.
Repeat this test for the 24 cm × 30 cm film size
in the cassette table and for all collimators in use
on the system. The same criteria apply to all film
sizes and for all collimators.
2.9
AEC Object Thickness Compensation. Place 4 cm
of 15 cm × 15 cm plexiglass on the cassette table.
Ensure that it covers the AEC detectors. Bring the
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©1995 ECRI. All Rights Reserved.
5
Inspection and Preventive Maintenance System
compression paddle down to touch the top of the
stack. Set the mammography unit to operate at
the commonly used kVp for imaging a compressed breast 4 cm thick (e.g., 28 kVp). Use the
standard screen-film combination utilized at
your facility as the receptor in the cassette
holder.
Make an AEC-controlled exposure. Process
the film on the standard film processor used to
process all mammography films, having
checked that it is performing optimally. Use a
densitometer to measure the optical density of
the phantom image at a point about 4 cm in
from the edge of the phantom. The optical
density should measure in the range of 1.2-1.4
OD, or some other value that the radiologists
have had programmed into the unit. Periodic
checks should result in optical density changes
within ±0.1 OD.
If the measured optical density falls within
the acceptable range, repeat the test using identical setup conditions but with varying amounts
of plexiglass on the cassette table. At a minimum, check the optical density at 2 and 6 cm of
plexiglass. All films used in this test should come
from the same batch, and for each check the film
must be loaded into the same cassette for the
whole test. The optical density of all processed
films should agree to within ±0.3 OD of the
optical density at 4 cm of plexiglass. Repeat this
test using the magnification imaging mode on the
mammography unit. The same criteria apply.
2.10 AEC kVp Compensation. Place 4 cm of plexiglass
on the cassette table. Ensure that it covers the
AEC detectors. Bring the compression paddle
down to touch the top of the plexiglass stack. Load
a standard film-screen cassette into the cassette
holder for all checks in this test.
Make a series of AEC-controlled exposures
of the 4 cm thick plexiglass at different kVp
values. At a minimum, use four kVp settings
that span the range commonly used. For each
exposure at a given kVp, process the film on an
optimally performing processor. Read the optical density of the phantom image using a densitometer. The optical density of all films at all
kVp settings checked should agree to within
±0.3 OD. Repeat this test using the magnification imaging mode.
2.13 Image Quality. Place the ACR accreditation
test phantom on the cassette table. Bring the
compression paddle down to touch the top of the
phantom. Load a standard screen-film cassette
into the Bucky. Dial up 28 kVp on the mammography unit (or the kVp commonly used at your
facility for this thickness of compressed breast)
and acquire an image using an AEC-controlled
exposure. Process the film using the standard
film processor used for all mammography films,
having first ensured that it is performing optimally. Once processed, the film should be
viewed on the viewbox normally used to display
mammograms. It should be possible to see a
minimum of four fibrils, three speck clusters,
and three masses.
Figure 1. Collimation test setup
6
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Mammography Units
TABLE 1. Glandular Dose (in mrad) for 1 Roentgen Entrance Exposure to a 4.2 cm Breast Thickness —
50% Adipose/50% Glandular Breast Tissue Using a Mo/Mo or W/Al Target Filter Combination
X-Ray Tube Voltage (kVp)
HVL
23
24
26
27
0.23
0.24
116
121
124
0.25
126
129
131
0.26
0.27
130
135
133
138
135
140
138
142
0.28
0.29
0.30
140
144
149
143
142
146
151
144
148
153
146
150
155
0.31
154
156
157
0.32
0.33
158
163
160
165
0.34
168
0.35
0.36
0.37
0.38
0.39
0.40
25
28
29
30
147
151
156
149
153
157
154
158
159
159
160
161
162
163
164
162
166
163
168
164
169
166
170
167
171
168
173
168
173
170
174
171
175
180
185
170
171
172
173
174
175
176
177
178
179
190
174
175
179
176
181
185
177
182
186
178
183
187
179
184
188
180
185
189
181
185
190
182
186
191
183
187
191
194
199
204
190
191
192
193
194
195
195
208
196
197
201
198
202
198
203
199
204
200
204
213
217
206
207
208
208
221
211
212
215
212
216
225
230
220
234
238
0.41
0.42
0.43
31
32
33
W/Al
Target-Filter
Combination
170
175
0.44
0.45
Source: American College of Radiology. Mammography quality control manual. Revised ed. 1994:163.
2.14 Average Glandular Dose to Standard Breast.
The average glandular dose is determined by
using the HVL value measured in Item 2.7 together with the entrance exposure measured in
air for imaging the ACR mammography accreditation phantom.
To measure the entrance exposure, place the
phantom on the cassette table, ensuring that the
phantom completely covers the sensitive area of
the AEC detectors. Next, set the ionization
chamber at one side of the phantom such that its
center is 4 cm in from the patient edge of the
cassette table and also vertically in alignment
with the top of the accreditation phantom. Secure the chamber in this position. Make sure
that the x-ray field completely envelops both the
phantom and the ionization chamber. Lower the
compression paddle so that it is just in contact
with the chamber and the phantom. Set the
mammography system at the kVp setting commonly used to image a compressed breast 4 cm
thick (note that this kVp should match the value
used for measuring the HVL in Item 2.7), and
engage the AEC system. For a mammography
system provided with a variable SID, record the
SID together with the technique settings.
Make an exposure of the phantom and record
the mR value. This is the entrance exposure for
the mammography phantom. Using the HVL
measured in Item 2.7 and the entrance exposure
measured in this test, the average glandular
dose may be calculated as follows:
a. Determine the target/filter combination of
the system under test. If it is a Mo/Mo system
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
7
Inspection and Preventive Maintenance System
TABLE 2. Glandular Dose (in mrad) for 1 Roentgen Entrance Exposure to a 4.2 cm Breast Thickness —
50% Adipose/50% Glandular Breast Tissue Using a Mo/Rh Target Filter Combination
X-Ray Tube Voltage (kVp)
HVL
25
26
27
28
29
0.28
0.29
0.30
149
154
158
151
156
160
154
158
162
31
32
159
162
163
0.31
163
164
166
166
167
167
0.32
0.33
167
171
169
173
171
175
171
176
171
176
172
176
172
176
0.34
176
178
179
179
177
180
180
180
0.35
0.36
180
185
181
186
183
187
181
181
183
187
184
188
185
188
185
189
186
190
187
191
0.37
0.38
0.39
189
193
198
190
194
199
191
191
196
200
191
196
200
192
197
201
193
197
201
193
197
202
194
198
202
195
199
203
195
199
203
200
204
0.40
202
0.41
0.42
206
211
203
204
204
205
205
206
207
208
208
208
207
211
208
212
208
212
209
213
209
213
210
214
211
215
212
216
212
216
212
217
0.43
0.44
0.45
0.46
215
216
217
217
218
218
219
219
220
220
221
220
224
220
224
228
221
225
229
221
225
229
222
226
230
222
226
231
223
227
231
223
227
232
224
228
233
224
228
233
225
229
234
0.47
233
233
234
235
235
236
237
237
238
0.48
0.49
238
238
242
239
243
240
243
240
244
241
244
241
245
242
245
242
246
247
247
248
248
249
250
251
251
252
257
253
257
254
258
254
258
255
259
261
261
265
269
262
266
270
263
267
271
264
268
272
0.56
275
276
276
0.57
0.58
279
280
284
281
285
288
289
0.50
0.51
0.52
0.53
0.54
0.55
30
0.59
0.60
33
34
35
293
Source: American College of Radiology. Mammography quality control manual. Revised ed. 1994:164.
or a W/Al system, use Table 1. For Mo/Rh and
Rh/Rh systems, use Table 2 and Table 3,
respectively.
b. Go down the first column in the table until you
find the HVL value measured in Item 2.7.
c. Progress along the row at this HVL until you
are in the column headed by the kVp setting
used to measure the entrance exposure in this
test.
8
d. The value at the intersection of the HVL row
and the kVp column is the normalized glandular dose (i.e., the dose that applies to an
entrance exposure of 1 R). Multiply the normalized glandular dose by the entrance exposure measured in this test. The value
obtained is the average glandular dose for the
system under test.
The average glandular dose for the system
under test should not exceed 300 mrad (3 mGy).
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Mammography Units
TABLE 3. Glandular Dose (in mrad) for 1 Roentgen Entrance Exposure to a 4.2 cm Breast Thickness —
50% Adipose/50% Glandular Breast Tissue Using a Rh/Rh Target Filter Combination
X-Ray Tube Voltage (kVp)
HVL
25
26
27
28
29
0.28
0.29
0.30
150
155
160
155
160
164
159
164
168
30
31
168
172
176
0.31
0.32
165
169
168
173
172
177
174
181
0.33
174
178
181
0.34
0.35
179
184
183
187
0.36
189
0.37
0.38
0.39
193
198
203
0.40
0.41
0.42
34
35
180
184
182
186
188
185
188
190
192
186
190
190
194
193
197
195
199
196
201
199
203
192
195
198
201
204
205
207
209
196
201
206
199
204
208
202
207
211
205
209
214
207
211
216
209
213
217
211
215
219
213
217
221
219
223
221
224
208
211
213
216
218
220
221
213
218
215
220
217
222
220
224
222
226
224
228
225
229
223
224
226
228
227
231
228
232
230
234
232
236
0.43
222
224
226
228
230
232
0.44
0.45
0.46
227
232
229
234
231
235
239
233
237
241
235
239
243
237
241
245
233
235
236
238
240
238
242
246
239
243
247
240
244
248
242
246
250
243
247
251
247
251
249
253
250
254
251
255
252
256
254
258
255
259
0.49
257
258
259
260
261
262
0.50
0.51
261
262
266
263
267
264
268
265
269
266
270
0.52
270
271
272
273
274
0.53
0.54
0.55
275
276
279
283
276
280
284
277
280
284
278
281
285
0.47
0.48
32
0.56
33
288
0.57
0.58
288
289
292
296
293
297
0.59
300
0.60
304
Source: American College of Radiology. Mammography quality control manual. Revised ed. 1994:165.
As an illustration of the above method, assume
that on a Mo/Mo system, the HVL measured at
28 kVp was 0.33 mm Al and that the entrance
exposure measured at 28 kVp was 500 mR (0.5
R). From Table 1, the normalized glandular dose
is 170 mrad. Multiplying the normalized dose by
the entrance exposure of 0.5 R provides the glandular dose value of 85 mrad.
3. Preventive maintenance
3.1
Clean exterior and interior, if needed.
3.2
Lubricate according to the manufacturer’s instructions (e.g., clean and lubricate casters, if
needed).
3.3
Calibrate the unit, if needed.
3.4
Replace items on the unit, if needed.
4. Acceptance tests
Acceptance testing is typically performed by a medical physicist.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
9
Inspection and Preventive Maintenance System
Before returning to use
Ensure that all controls are set properly. Set alarms
loud enough to alert personnel in the area in which the
device will be used. Other controls should be in their
normal pre-use positions. If the unit is being used at
10
home, ensure that all controls are set correctly before
it is returned to the patient.
Attach a Caution tag in a prominent position so that
the user will be aware that control settings may have
been changed.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Procedure/Forms 440-0595
Medical Gas/Vacuum Systems
Used For:
Alarms, Central Gas System [15-824]
Medical Gas and Vacuum Systems [18-046]
Medical Gas Outlets [17-682]
Valves, Medical Gas and Vacuum [18-044]
Also Called: Piped medical gas systems, medical-surgical gas systems, nonflammable medical gas systems,
vacuum systems
Commonly Used In: Most patient care areas and some laboratories
Scope: Applies to any piped medical gas system (including oxygen, air, and nitrous oxide) and central vacuum
system; does not replace full testing according to NFPA 99, Standard for Health Care Facilities, which must be
conducted following any new construction or modification; does not apply to medical air compressors, dryers,
contaminant monitors, or purification systems, which must receive regular IPM for safe and reliable operation
(see Medical gas and vacuum systems, Health Devices [Guidance article], 1994 Jan-Feb; 23:4-41)
Type
ECRI-Recommended
Interval
Interval Used
By Hospital
Time Required
Major
After any renovations,
modifications, and/or additions
to the medical gas system
Months
Approximately 100
outlets/day in occupied
areas; 250 outlets/day
in unoccupied areas
Minor
12 months*
Months
Same as above
* Although we recommend that a major inspection (Items 2, 3, 5, 6, 7, and 8) be performed annually for medical
gas and vacuum systems, we understand that, for some hospitals, this may not be practical. Increasing the
inspection interval up to but not more than two years is acceptable in these cases. However, some frequently
used outlets and inlets (e.g., in the emergency room) are subject to wear, and more frequent performance of
Items 5 and 6 should be considered to ensure their safe operation. Where alarm-system test buttons are
provided, audible and visual alarm indicators should be tested monthly (NFPA 99, Appendix C, Section C-4.2.17).
Overview
multiple fatalities in some institutions, in at least 15
hospitals in North America.
In an actual case, workers renovating an emergency
room inadvertently cross-connected the nitrous oxide
and oxygen supply lines. As a result, 20 outlets labeled
“oxygen” actually delivered nitrous oxide for more than
six months before the hospital’s chief anesthesiologist
discovered the error. We are also aware of other cases
in which similar incidents have occurred. Mix-ups in
medical gas connections have caused deaths, including
Piped gas systems present certain characteristic
hazards, usually related to their original construction,
modification, or repair. However, problems can develop during the working lifetime of the systems, particularly in medical compressed air systems, outlets,
and vacuum inlets. The hazards include plumbing
errors, as described above; use and degradation of
materials incompatible with the gases to be delivered;
241434
440-0595
A NONPROFIT AGENCY
5200 Butler Pike, Plymouth Meeting, PA 19462-1298, USA
Telephone +1 (610) 825-6000 ● Fax +1 (610) 834-1275
●
E-mail [email protected]
Inspection and Preventive Maintenance System
obstruction of flow by migration of material left in the
pipelines; gas contamination by residual debris or accumulated foreign matter (e.g., scale, hydrocarbons,
microorganisms, moisture, or dirt in medical compressed air pipelines); gas contamination due to chemical interaction, including fire and explosion, between
the gases and pipeline components or foreign matter;
and gas contamination due to a contaminated source
(e.g., air intake near diesel exhausts). (See Cleaning
contaminated MGVSs, Health Devices 1994 Jan-Feb;
23:34-5.) Problems related to how the system is used
and maintained during its lifetime include leaking
outlet seals, clogged vacuum inlets and piping (e.g., by
dust or by body fluids), inadequate particulate filtration, corrosion of automatic condensate drains, wear
or embrittlement of valve seals, physically damaged or
loose outlets, wear of compressor or pump seals and
bearings, and pressure sensor drift.
NFPA 99, which is mandatory in some localities,
states in Chapter 4, the section on gas and vacuum
systems, that the piping systems must be tested following new construction, addition, renovation, or repair. (In this procedure, references to NFPA 99 refer
to the 1993 edition, unless otherwise specified.) It
specifies tests for zone-valve and alarm-system function, leaks, and cross-connections (in addition to other
items) and provides specific criteria for gas analysis
and monitoring. Installers are required to perform
some testing of new or modified systems; independent
testing of these systems before they are used for patient care is recommended. NFPA 99 also calls for the
healthcare facility to develop and implement procedures for testing medical gas and vacuum systems and
their related alarm systems; this IPM procedure
should satisfy this requirement for piping and alarm
systems testing. The standard also requires that
proper medical gas concentration be verified and that
the supply systems be tested after any breach of or
modification to the system.
Also, in its 1995 Accreditation Manual for Hospitals,
the Joint Commission on Accreditation of Healthcare
Organizations (JCAHO) requires that the hospital
have documented plans and procedures for routine
testing, inspection, and maintenance of utility systems
(e.g., medical gas and vacuum systems) to ensure that
these systems operate properly and will continue to
operate in an emergency. The JCAHO manual also
indirectly refers to NFPA 99 through NFPA 101, Life
Safety Code, and the American Institute of Architects’
Guidelines for Construction and Equipment of Hospital and Medical Facilities, which base design and
safety requirements on NFPA 99. Also, because medical gases are drugs, the JCAHO manual, in its section
2
on medications, requires that medications (i.e., drugs)
be prepared, delivered, and administered according to
appropriate laws and standards of practice, which
again indirectly refers to NFPA 99.
Hospitals should insist that those responsible for
construction document the test methods and results as
required in NFPA 99; this documentation, as well as
documentation from analytical tests, should be kept on
permanent record. Hospitals should also obtain documentation verifying the purity of medical gases from
suppliers. In addition, the hospital should perform
acceptance inspection and testing of the medical gas
and vacuum systems independently of tests conducted
by the installing contractor. The hospital’s facility
engineering, anesthesia, clinical engineering, or respiratory therapy department may perform this testing.
If adequate personnel, experience, or equipment is
lacking, an independent testing organization that specializes in this type of activity can be employed.
In a typical hospital, piped medical gas and vacuum
systems are frequently repaired, modified, and expanded. These activities may include replacing defective outlets or inlets, valves, or piping; relocating
outlets; and adding outlets to the existing system. Identification plates and other labels are often removed
during this activity, increasing the probability of error.
Major changes to systems (e.g., construction of a building addition) are not included in this category.
ECRI knows of no procedure other than this one that
enables the hospital to safely, easily, accurately, and
completely inspect only the modified portion of the
system. The procedures outlined in NFPA 99 are
clearly intended to test newly constructed systems
that have not yet been put into service. The process
described by that standard requires testing at different stages of installation before proceeding with additional installation. For example, both the 150 psig
pressure test (Section 4-5.1.2.1) and the blow-down (or
initial purging) test (Section 4-5.1.2.2) must be performed before system components, such as pressureactuating alarm switches, alarms, manifolds, pressure
gauges, and pressure relief valves, are installed.*
Pressure testing and purging of the completed system
must also be performed. The hospital should have the
contractor who installs the system and an outside testing
organization provide documentation of conformance
* Pressure is measured relative to one of two reference points: standard
atmospheric pressure (14.7 psia) or zero absolute pressure; psig refers
to gauge pressure (i.e., the reference pressure to which the measuring
device is calibrated, typically standard atmospheric pressure), and psia
refers to absolute pressure (i.e., reference pressure of zero).
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Medical Gas/Vacuum Systems
with all portions of NFPA 99, Chapter 4, for all new
medical gas and vacuum system construction.
Pressure measuring devices, 0 to 100 and 0 to 400
psig, with 5% accuracy
Performing certain portions of the NFPA 99 testing
procedure requires a complete shutdown of the system.
Thus, the hospital must provide a large number of
alternative gas or vacuum sources (e.g., cylinders with
regulators, portable suction systems) and may need to
minimize gas or vacuum usage (e.g., by rescheduling
surgery) to test the entire medical gas or vacuum
system following modifications.
Flowmeter, 0 to 250 L/min, with 5% accuracy (flowmeter manufacturers usually supply calibration
curves for a range of common gases with each instrument); alternatively, if a flowmeter calibrated
for the gas being measured is not available, use the
following formula:
Because of the difficulty and expense entailed and
the possible compromise of patient care, hospitals are
reluctant to fully test modified systems, except after
major modifications or additions. However, failure to
fully test systems can allow serious problems
(e.g., cross-connections, which are usually thought of
as problems associated only with new systems) to go
undetected.
Flow control valve(s)
ECRI has developed a simple technique that permits testing and inspection both of existing systems
and of modified portions without affecting the entire
hospital at once; this procedure also allows detection
of most problems that can develop during system modification or system operation.
Citations from Health Devices
Corrected Flow = Indicated Flow

√
Density (Design Gas)
Density (Test Gas)
Test equipment that combines the functions of the
above test devices or that automates the testing described in this procedure is available and may be
substituted. Also, portable pneumatic calibrators or
anesthesia machine calibrator/analyzers may be suitable alternatives.
Note: Medical gas systems may contain contaminants that may affect test instruments; periodic cleaning, in addition to calibration, may be needed.
Source of oil-free dry nitrogen with a pressure regulator to supply a test gas (see the section on compressed gases in “IPM Safety” behind the Guidance
Tab of this binder)
Restricted draw in Schrader-type vacuum inlets [User
Experience NetworkTM], 1993 Aug-Sep; 22:426-7.
Hoses and adapters to connect the pressure or vacuum measuring device and test gas cylinder to each
gas outlet
Color-coded compressed medical gas hose changes
color [Hazard], 1986 Apr; 15:106-7.
Hand tools, such as screwdrivers, wrenches (including Allen wrenches), and pliers
Medical gas and vacuum systems [Guidance article],
1994 Jan-Feb; 23:4-41.
Should vacuum pump effluent be treated? [User Experience NetworkTM], 1994 Jul; 23:310.
Use of filters on medical gas system outlets and vacuum system inlets [User Experience NetworkTM],
1994 Dec; 23:494-5.
Soldered medical gas piping [User Experience NetworkTM], 1995 Mar; 24:127.
Test Apparatus and Supplies
Oxygen analyzer that will remain accurate in the
presence of and not be damaged by nitrous oxide
(analyzers used with anesthesia units are probably
satisfactory)
Vacuum measuring device, 0 to 30 inches of mercury
(in Hg; 0 to 760 mm Hg), with 5% accuracy
Labels, such as “Do Not Use” and “System Under
Test”
Sampling bottles and filters for collecting samples
for analysis; typically, these are obtained from the
laboratory that will conduct the analysis
Special Precautions
General. Before testing, alert clinical personnel,
and ensure that an adequate supply of appropriate gas
cylinders and/or vacuum sources is available in the
immediate area as a backup for piped gases. Provide
ample preparation time, especially if a system or zone
must be shut down for testing.
Never disconnect or test any medical gas outlet,
vacuum inlet, or system serving a patient or patient
care area without the approval of clinical personnel.
Do not perform any test that may interfere with the
gas supply to patients (e.g., turn off zone valves,
pressurize with another gas or to a pressure different
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
3
Inspection and Preventive Maintenance System
from the usual supply pressure) while that section
of the system is in use for patients.
Never use oxygen as a test gas (e.g., pressure
test) — use only oil-free dry nitrogen.
Do not allow smoking or other open sources of ignition in the immediate test area, especially in the
presence of nitrous oxide or oxygen.
Because of high pressure, take special care when
inserting and disconnecting adapters from the outlet under test. Also, before testing, make certain
that the adapter is securely locked into the outlet.
Never pressurize (i.e., apply a test gas to) a vacuum
system with gauges in the section of the system to
be pressurized; this could damage the vacuum
gauges. Overpressurizing compressed gas lines, as
required for certain sensors (e.g., newly installed or
modified systems), can also damage certain sensors,
alarm switches, and outlets in these systems. Certain pressure tests must be conducted before these
components are installed in the system per NFPA
99, Section 4-5.1.2.1.
Purging. When using the test gas (oil-free dry nitrogen) to inspect an alarm panel or to pressurize a piping
system, purge the test gas from the system before
using it for patients. With the appropriate zone valve
closed, open an outlet to depressurize the system. After
depressurization, close that outlet; then open the zone
valve and each outlet in the zone in order, starting with
the outlet nearest the zone valve. You can turn off an
outlet before opening the next outlet in the line. Where
appropriate (e.g., with oxygen and medical compressed
air pipelines), use an oxygen analyzer to verify proper
oxygen content at each outlet, or flush each outlet with
its labeled gas for approximately 1 min (except nitrous
oxide — see the precautions below — and also note
that an oxygen analyzer, by definition, will not detect
nitrogen or nitrous oxide).
Nitrous Oxide. Take special precautions when testing or purging nitrous oxide systems to minimize exposure to the exhausted gas. Although occasional acute
exposure to nitrous oxide, which might occur during
annual testing, has not been shown to be hazardous,
we recommend that you still take reasonable precautions to minimize exposure. For example:
Women of childbearing age should not routinely
perform this procedure or be in the area during the
procedure.
Use a length of corrugated tubing (about one inch in
diameter) to direct the exhausted gas away from
personnel and, where practical, into a ventilation
return duct or out a window.
4
Limit purging and flow measurement times from
each outlet to 10 sec. (About 200 ft of piping can be
purged in this time; correspondingly shorter purge
times can be used for shorter piping runs.)
Purge the nitrous oxide system last, and leave the
room after turning off the outlets. Restrict personnel from entering the room to allow the exhausted
gas to dissipate. In a typical operating room, 15 min
is adequate. In smaller rooms with lower ventilation
room-air exchange rates, such as delivery rooms,
dissipation may require 1 hr. Restrict unnecessary
entry into the room during this time; the room may
be used if essential for patient care.
Procedure
This procedure was developed to help hospitals find
and correct hazards associated with existing and modified piped medical gas and vacuum systems. It does not
replace the full testing required by NFPA 99; it confirms safe operation and is recommended for use by the
hospital for independent confirmation of safety and
performance only after the construction, tests, and
inspection per NFPA 99 have been completed and on
an annual basis thereafter.
You must perform all items in the procedure on any
portion of the system that is repaired or modified
before that portion of the system is put into service.
Before beginning the inspection, carefully read this
procedure; be sure you understand how the gas system
and associated equipment are intended to operate, the
significance of all controls and indicators, and the
alarm capabilities. Begin the inspection procedure by
identifying the area to be tested. This may be a room,
a special care area, or an area with many outlets. We
recommend that each gas outlet be identified with a
numbered label or an engraved number on the faceplate. One systematic numbering method consists of
starting to the left of a given doorway from a position
facing into the room and proceeding clockwise, numbering the outlet stations in the room (see Figure 1).
Include ceiling columns (e.g., as in an operating room),
as well as surface-mounted stations. Each outlet at a
given station is then numbered from left to right.
Disconnect equipment from each outlet before performing the inspection of that outlet station. If you are
inspecting a system that is already in operation, consult clinical personnel before disconnecting any patient care equipment being used. Inspect every outlet
at each station in the area.
Because the Universal Inspection Form is not applicable, use the special three-part Medical Gas and
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Medical Gas/Vacuum Systems
1.
When all components of the system have been
installed and the system is ready to be used, pressurize the appropriate section of the medical gas
or vacuum system to 100 psig with oil-free dry
nitrogen. On additions and modifications, close the
appropriate zone valve before pressurizing so that
the section to be tested is isolated from the rest of
the system. We recommend using 100 psig (instead
of 150 psig, as required by NFPA 99 during the
initial pressure test) for testing to reduce the risk
of damaging system components. (Verify that components [e.g., pressure sensors] will not be damaged by this test pressure.) However, this does not
substitute for pressure testing according to NFPA
99 during installation. Measure the pressure immediately after pressurization to 100 psig and
again 1 hr later. After correcting for any temperature changes, confirm that there has been no
change in line pressure after the 1 hr period. To
correct for temperature changes, use the following
formula:
Figure 1. Sample room with 6 stations, numbered clockwise from left, and 18 outlets.
Vacuum System Inspection Form provided. Part A of
the form is for alarm-panel and zone-valve inspections,
and Part B is for medical gas outlet and vacuum inlet
inspections. Part C is for documenting medical gas
purity analysis.
On the appropriate part of the inspection form (on
Parts A and B), record the test data and the actions
needed and taken. If deficiencies detected during the
inspection are serious enough to preclude using an
outlet until it is repaired, check both the Action Needed
and the Do Not Use columns; label the outlet so that it
will not be used and so that it can be quickly identified
for future repairs. If the outlet is in an area being used,
inform clinical personnel, and make sure that an adequate alternative gas supply is available. If the outlet
is usable, check only the Action Needed column. To
clearly identify defective outlets on the inspection
form, circle unacceptable values, or note specific defects in the Comments section at the bottom of the
form.
The Status box in the upper right corner of each
form provides a quick indication of the condition of the
outlets or alarms and valves listed. Check the appropriate box after completing the inspection. If even one
outlet, alarm, or valve on the sheet requires servicing,
check the Service Required box. The individual who
completes the repairs should record the date and his
or her initials in the Action Taken column; check the
OK column after confirming the satisfactory condition
and performance of that item. Check the Passed box in
the Status area only after all repairs for all items on
that form are complete.
Pressure Testing. All new or modified systems
should be pressure tested per NFPA 99, Sections
4-5.1.2.1 and 4-5.1.2.3. We recommend that the
following acceptance test be performed by the
hospital or an independent agency before a new
system or modified portion of the existing system
is put into use.
PFinal =
PInitial × TFinal
TInitial
where T = absolute temperature measured in
kelvins or degrees Rankine*
2.
Area Pressure Alarms. Area pressure alarms
should be activated when line pressure varies
20% from normal system pressure.
To test the high-pressure alarm, close the
appropriate zone valve, and apply oil-free dry
nitrogen through a pressure measuring device to
one outlet in the zone until the alarm is activated. Measure and record the alarm pressure.
To test the low-pressure alarm, bleed system
pressure with the zone valve closed until the
low-pressure alarm is activated. Measure and
record the alarm activation pressures on the top
portion of Part A of the Medical Gas/Vacuum
Systems Inspection Form. (Note: This test can
be performed in conjunction with Item 3.)
Check area signal panels, remote indicators
(if present), and appropriate gauges for proper
* To obtain a temperature in kelvins or degrees Rankine, add 273.2
to degrees Celsius and 459.7 to degrees Fahrenheit, respectively.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
5
Inspection and Preventive Maintenance System
With appropriate adapters (which should match
outlet labels), check each individual outlet of
each gas and vacuum system to determine that
test gas is not present at any outlet other than
the one connected to the pressurized supply.
Disconnect the source of the test gas, and reduce
the first system to atmospheric pressure. Repeat
this test by pressurizing each additional piping
system, one at a time, including vacuum (unless
gauges are present). Purge all tested systems in
accordance with NFPA 99, Section 4-5.1.3.9, and
the special precautions noted previously.
labeling and function or accuracy. Also check
audible alarm-silence systems during alarm activation — a visual alarm light should remain
on. In addition, check signal panels for deactivation after returning the system to normal pressure. Before placing the system in service, purge
it as described in the Special Precautions section
and in accordance with NFPA 99, Section
4-5.1.3.9. (Other testing may be completed with
the test gas before purging; see the precautions
regarding nitrous oxide.)
If the alarm panel has test buttons, retesting
of audible and visual alarms should be done
monthly.
3.
Zone Valves. Zone valves are tested to ensure
that the branch served by the zone valve will be
closed and isolated in the event of an emergency.
Check each zone valve for a label or placard that
lists the gas it controls and the area it serves. Also
check that a line-pressure gauge is present downstream of the zone valve and that it correctly reads
the system pressure by comparing it with a pressure measuring device at an outlet in that area.
Close the valve, and bleed the branch to zero
pressure. Confirm that the system gauge and pressure measuring device read zero. Record findings
on the bottom portion of Part A of the Medical
Gas/Vacuum System Inspection Form.
Perform a leakage test on all threaded components of the pressurized zone valve using a test
solution listed as safe for use with oxygen.
4.
Cross-Connection Testing. This test should only
be performed on new systems or following any
system modifications. The test must be performed after all outlets are completely installed,
including labels, cover plates, and fittings. This
will ensure that outlets are connected to and
labeled for the appropriate gas system. Do not
rely on testing done before final attachment of
labels and other identification plates that identify gas outlets.
To test new systems or major modifications
to existing systems where gas sources can be
shut down without disrupting existing patient
care, use the following procedure. Reduce all
pipelines to atmospheric pressure. Disconnect
all sources of test gas from all of the systems
with the exception of the one system to be
checked. Pressurize this system to 50 psig with
oil-free dry nitrogen to avoid disruption to and
possible contamination of the existing services.
6
To avoid disrupting patient care when testing
modifications to existing systems that are in use,
use the oxygen concentration measuring procedure described in Item 5.
5.
Medical Gas Outlets (medical compressed air,
nitrogen, nitrous oxide, oxygen, carbon dioxide,
and other gases if piped). Examine the condition
of the outlet. Check that each outlet is properly
labeled with the name of the dispensed gas and
that its cover plate is securely fastened. Ensure
that color coding is consistent with standards for
the gas supplied to each outlet (e.g., green for
oxygen, yellow for medical compressed air).
Make sure that the adapter specific for the gas
dispensed locks securely into the outlet, that the
outlet does not leak with the adapter installed,
that the adapter is easily removed, and that the
valve closes when the adapter is removed. Listen
for leaks before and after inserting adapters.
Leaks may be corrected by replacing seals
(e.g., O-rings, gaskets) in the valve assembly.
Attach an oxygen analyzer, a pressure measuring device, and a flowmeter or pneumatic analyzer to the outlet; measure and record the flow
and pressure at that flow on Part B of the Medical Gas/Vacuum System Inspection Form. NFPA
99 requires that piping systems be able to deliver
flows at the pressures listed in Table 1, Recommended Pressures and Flows.
Open the flow-control valve until a flow of 100
L/min is seen. Pressure at that outlet should not
Table 1. Recommended Pressures and Flows*
Medical Gas
Pressure, psig
Flow, L/min
Oxygen
Nitrous Oxide
Medical Air
Carbon Dioxide
Nitrogen
50 to 55
50 to 55
50 to 55
50 to 55
≥160
≥100
≥100
≥100
≥100
≥145
*Pressures and flows per NFPA 99, Section 4-5.1.3.8.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Medical Gas/Vacuum Systems
drop below 50 psig for all gases except nitrogen,
which should not drop below 160 psig at a flow
of at least 145 L/min. Some older systems may
not be able to meet these requirements. However,
if the pressure drops to below 80% of the listed
values in older systems or below the required
values in newer systems or if the required flows
cannot be obtained, corrective action is required.
Unacceptable pressure or flow may indicate a
blockage in either the distribution piping or the
outlet check valve(s). Blowing the piping clear
with the outlet removed and cleaning the outlet
check valve(s) will usually resolve this problem.
(Minimize exposure to nitrous oxide; see Special
Precautions.) If the above measures do not resolve the problem, the outlet may have to be
replaced or, depending on the severity of the
restriction, a portion of the system may need to
be modified. Consult with clinical staff to determine the minimum acceptable flow for clinical
needs, including the safe operation of life-support equipment. Also consider whether simultaneous use of multiple outlets will further
degrade performance. ECRI can provide advice
on the most appropriate action to take should a
flow-restriction problem exist.
label. This problem may also arise if you use
extension hoses to connect equipment to a wall
or ceiling outlet. Recheck each time service personnel remove a hose for repair, maintenance, or
replacement.
Gas hoses should have appropriate connectors
for attachment to equipment. Avoid using special adapters for connecting hoses (e.g., DISS to
quick-connect fittings) to minimize problems
such as gas leaks at the connectors. Color-coded
hoses are recommended for this application to
reduce the risk of misconnection. Be aware that
the color of gas hoses can change over a period of
time (see Color-coded compressed medical gas
hose changes color [Hazard], Health Devices
1986 Apr; 15:106-7.) Replace any hoses that have
changed color or faded.
6.
Vacuum Inlets (vacuum and evacuation vacuum). Inspect the condition of each inlet, as
described in Item 5.
Measure and record (on Part B of the Medical
Gas/Vacuum Systems Inspection Form) the oxygen concentration to determine that the outlet is
delivering the proper medical gas. The oxygen
concentration should be 100% at oxygen outlets
and 21% at medical compressed air outlets.
NFPA 99, Section 4-5.1.3.9, requires the use of
gas-specific analyzers for initial testing of new
and renovated systems, but for routine testing of
installed systems, nitrogen, nitrous oxide, and
carbon dioxide outlets should read 0% on an
oxygen analyzer. Note that, in an operating system, nitrogen will be at a higher pressure than
nitrous oxide. This test can also serve to check
for cross-connection in existing systems.
Attach the vacuum measuring device to an
inlet and a flowmeter to an adjacent inlet. Measure and record the pressure and flow on Part B
of the Medical Gas/Vacuum System Inspection
Form. NFPA 99, Section 4-11.2.1.3, requires that
the vacuum pressure be at least 12 in Hg (305
mm Hg) while 85 L/min (3 standard cubic feet
per minute) flow is being drawn at an adjacent
inlet. We recommend that, where practical, the
two inlets be on the same branch and that the
pressure be measured at an inlet beyond the
inlet at which the flow is established. In addition,
we recommend noting the maximum flow. Most
newer systems will be able to provide 85 L/min
at an inlet, although such high flows may not be
required for many applications. Some older systems may not be able to meet these criteria; it is
then necessary to determine whether corrective
action (e.g., cleaning the pipeline) is required to
meet clinical needs.
In some hospitals, hoses extend from ceiling
connectors to outlets that are suspended at a
lower, more accessible height. Although the ceiling connector and suspended outlets may have
proper labels and unique fittings for each gas to
prevent incorrect connections, the end connections of the hoses and the pipelines to the gas
fittings and outlets may be identical. Thus, it
may be possible to attach an outlet or connector
to the wrong hose. If you have such an installation, make sure that the ceiling connector and
outlet linked by a given hose have the same gas
For inlets that have reduced vacuum draw,
inspect the interior of each vacuum inlet for
accumulated dust or other debris from leaking
seals or poor suctioning procedures. Clean the
inlet, if necessary, by removing the inlet valve
assembly and washing it in warm soapy water
(see the section on infection control in “IPM
Safety” behind the Guidance Tab in this binder).
Using a piece of tubing, suck about a liter of the
wash water into the disassembled inlet to clean
debris from the inlet section of the pipeline.
Rinse the inlet valve assembly with clean water
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
7
Inspection and Preventive Maintenance System
and reassemble the inlet. Remeasure vacuum
pressure and flow at the cleaned inlet. Inadequate flow may indicate other problems in the
vacuum system (e.g., a clogged pipe).
7.
8.
Master Alarm Panel. Refer to NFPA 99, Section
4-4.1.1.2 and Appendix C-4, for required components and recommended test intervals. Section
4-6.2.3.9 of NFPA 99 requires periodic retesting
of audible and visual alarms to determine
whether they are functioning properly, and Section C-4.2.16 recommends annual testing of all
components of warning systems if testing can be
performed without changing system line pressure. Refer to the manufacturer’s instructions
for component testing.
Medical Gas Analysis. Acceptance testing of
medical gas purity is not usually required if
purity testing required by NFPA 99 is conducted
by an independent test organization when the
system is completed.
Obtain certificates of purity showing all testing performed by the gas manufacturer for each
shipment of gas.
For oxygen, nitrous oxide, nitrogen, and carbon dioxide, verify that certificates of purity have
been received and filed for each gas shipment,
and note this on the Confirmation of Purity
section of the inspection form. Include the source
of any certificate of purity and the date of the
certificate. After installation of a new system,
the piping system for these gases should also be
tested for gaseous and liquid hydrocarbons, as
well as for particulates and gas concentration.
We recommend taking gas samples from an outlet nearest the gas source and at the outlet most
remote from the source. Refer to Table 2 for
recommended maximum allowable levels of contaminants for these gases.
NFPA 99, Section 4-3.1.9.8, requires that the
quality of the medical compressed air generated
on-site be monitored continuously for dew point
and carbon monoxide. A gas sampling port
downstream of the system pressure regulators
is used for this purpose. Reciprocating (oil-less)
8
compressors must also be monitored for liquid
(continuously) and gaseous (quarterly) hydrocarbons. Piped medical compressed air systems
should also be tested annually for particulates.
Independent dew point and carbon monoxide
tests should be conducted at least annually for
all medical compressed air systems, preferably
in the summer when these contaminants are
most prevalent, to verify monitor performance.
More frequent analyses may be warranted in
hospitals with medical compressed air problems
until those problems are resolved.
For medical compressed air analysis, obtain
sampling bottles (as well as instructions for their
use) from an analytical laboratory. For annual
inspections, sampling can be done at an outlet
close to the source. To determine the cause of any
problem, it may be necessary to monitor the
quality of the outside air at the medical air compressor intake. For all other analyses, take a
sample at the farthest outlet locations from the
compressor in the piped medical compressed air
system.
Enter the results of the medical air analysis
on Part C of the inspection form. Compare the
results to the values listed in Table 2, in which
most allowable values meet or exceed the contaminant limits of most of the various concerned
agencies. ECRI chose the values listed in the
table because we believe they are reasonable to
obtain and safe for the particular gas and contaminant based on our review of the several
documents that define the composition of medical gases.
Judging the level of a particular contaminant
relative to this table should be done with caution.
Such factors as the measurement accuracy, the
sampling location, the sampling technique, and
the contaminant itself will affect what should be
done. Regardless, a second test, independent of
the first, should be made to verify any suspected
contamination. Determination of the source of
the contamination will direct the course of corrective action (e.g., change of source, purge of
pipeline).
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Medical Gas/Vacuum Systems
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
9
Inspection and Preventive Maintenance System
10
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Medical Gas/Vacuum Systems
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
11
Inspection and Preventive Maintenance System
12
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Procedure/Checklist 463-0595
Mobile C-arms
Used For:
Radiographic/Fluoroscopic Units, Mobile [11-758]
Also Called: Portable C-arms, surgical C-arms
Commonly Used In: Critical care areas, emergency departments, and operating rooms
Scope: Applies to mobile C-arms capable of fluoroscopy and radiography
Risk Level: ECRI Recommended, High; Hospital Assessment,
Type
ECRI-Recommende
Interval
Major
12 months
months
.
hours
Minor
6 months
months
.
hours
Overview
C-arms provide radiographic and fluoroscopic imaging in surgical, orthopedic, critical care, and emergency care procedures. They are used to image
patients in radiolucent beds, stretchers, or tables
when it is not feasible to transport the patient to the
radiology department. The fluoroscopic feature allows
real-time imaging, which permits quick diagnoses and
minimal patient time under anesthesia during surgical procedures.
C-arms are used in a variety of general surgical,
cardiac, and neurological applications, including aneurysm repair, pacemaker implantation, hip replacement, fracture reduction, foreign-body location, needle
biopsy, catheter placement, percutaneous lithotripsy,
and brachytherapy. These devices also enable special
studies, such as the diagnosis of swallowing disorders
in patients who cannot readily sit on a standard fluoroscopic table or stand on a footboard. Mobile C-arms can
also be equipped with a variety of digital hardware and
software options for use in angioplasty, interventional
neuroradiology, neurosurgery, and trauma care.
Compact, scaled-down fluoroscopic imaging systems called mini C-arms are designed for extremity
imaging in the emergency room, the operating room,
241477
463-0595
A NONPROFIT AGENCY
Interval Used
By Hospital
Time Required
the physician’s office, the industrial site, and the athletic field. The user can quickly acquire projections of
the patient’s anatomy from various angles while continuously viewing the fluoroscopic images. Radiographic imaging capability may not be provided.
Citations from Health Devices
Mobile C-arm units [Evaluation], 1990 Aug; 19: 251-91.
International Medical Systems Exposcop Plus mobile
C-arm system [Evaluation], 1993 Mar; 22:103-21.
FluoroScan Mini C-arm unit [Evaluation], 1995 Feb;
25:44-70.
Test apparatus and supplies
Ground resistance ohmmeter
Leakage current meter or electrical safety analyzer
Noninvasive kVp meter (compatible with the x-ray
generator being inspected)
Noninvasive timer (may be included with kVp
meter)
Ionization chamber with electrometer or a combination exposure meter
5200 Butler Pike, Plymouth Meeting, PA 19462-1298, USA
Telephone +1 (610) 825-6000 ● Fax +1 (610) 834-1275 ● E-mail [email protected]
Inspection and Preventive Maintenance System
Five filters of 10 cm × 10 cm × 1 mm Type 1100
aluminum
maintenance procedures or frequencies are recommended by the manufacturer.
Ruler with leaded 1 cm or 1⁄2″ markers
This procedure is intended to ensure adequate system performance and maintenance. It should not be
construed as providing full compliance with the requirements of all governmental regulations and accreditation standards of professional associations.
Such regulations and standards may include testing
beyond that provided below and may also require documentation by a certified medical physicist.
Large-format x-ray film (30 cm × 30 cm)
Patient simulator material (e.g., 8 pieces of 30 × 30
× 2.5 cm plexiglass, or appropriate thickness of
aluminum or copper) to bring the unit to midrange
technique under automatic brightness stabilization
(ABS) control
Six pieces of 30 cm × 30 cm × 1 mm lead
High-contrast resolution line-pair phantom to 5
lp/mm minimum
Low-contrast phantom consisting of two 3/4″ (2 cm)
aluminum plates, 7 × 7″ (18 × 18 cm), and one sheet
of 1.0 mm aluminum, 7 × 7″ (18 × 18 cm), with two
sets of four holes of the following sizes: 1/16″, 1/8″,
3/16″, and 1/4″ (1.0, 3.0, 5.0, and 7.0 mm) (using an
alternative low-contrast phantom is acceptable provided that it can be reproducibly used for assessing
long-term performance; use the criterion applicable
to the phantom selected)
For acceptance testing, we strongly recommend contracting with a medical physicist. Acceptance testing
is crucial because it generates data on baseline performance of the device.
1. Qualitative tests
1.1
Oscilloscope (calibration only)
High-voltage divider (calibration only of rotating
anode type x-ray tubes)
Check the mechanical operation of the C-arm,
including up/down motion, rotation, and
wig/wag, ensuring that all movements are
smooth; ensure that the arm locks securely at
each position.
Special precautions
Wear a lead apron and thyroid shield at all times
during x-ray exposure. Maintain the greatest possible
reasonable distance from the x-ray source and all scattering material. It should not be necessary to place
hands or fingers in the x-ray beam; if unavoidable, wear
lead gloves. Keep x-ray exposure time to a minimum.
Do not remove the high-voltage cables from the
wells with the power on. Ensure that high-voltage
cables are completely discharged by repeatedly touching the conductor to ground as soon as it is removed
from the well. Wear rubber gloves or other appropriate
protection when exposed to blood or other body fluids.
1.3
Casters/Brakes. Verify that the casters turn
and swivel freely. Check the ease of steering of
the C-arm stand and the display cart. Ensure
that caster brakes secure the stand from movement.
1.4
AC Plug/Receptacles. Examine the AC power
plug for damage. Attempt to wiggle the blades to
check that they are secure. Shake the plug, and
listen for rattles that could indicate loose screws.
If any damage is suspected, open the plug and
inspect it.
For repeated exposures, allow adequate time between exposures to prevent overheating of the x-ray
tube.
If the device has electrical receptacles for accessories, verify the presence of line power. Insert an AC plug into each receptacle, and check
that it is held firmly. If accessories are plugged
and unplugged often, consider a full inspection
of the receptacles.
Procedure
Before beginning an inspection, carefully read this
procedure and the manufacturer’s instructions and
service manuals; ensure that you understand how to
operate the equipment, the significance of each control
and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive
2
Chassis/Housing. Examine the exterior of all
components of the C-arm for cleanliness and
general physical condition. Be sure that all hardware is present and tight and that there are no
signs of spilled liquids or other serious abuse.
External collimators should be checked for pooling of blood and be cleaned, if necessary. The grid
and image intensifier housing should be checked
for blood and cleaned, if necessary.
1.5
Line Cord. Inspect the cord for signs of damage.
If damaged, replace the entire cord or, if the
damage is near one end, cut out the defective
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Mobile C-arms
proper alignment, as well as positive stopping.
During the course of the inspection, be sure to
check that each control and switch performs its
proper function. For the fluoroscopic and radiographic exposure switches, ensure that they do
not stick and that continuous pressure is required to continue exposure. Release of pressure
should immediately terminate exposure.
portion. Ensure that the remaining length is
adequate. Be sure to wire a new power cord or
plug with correct polarity.
1.6
Strain Reliefs. Examine the strain reliefs at
both ends of the line cord. Be sure that they hold
the cord securely.
1.7
Circuit Breaker/Fuse. If the device has an external circuit breaker, check that it operates
freely. If the device is protected by an external
fuse, check its value and type against that
marked on the chassis, and ensure that a spare
is provided.
1.9
Cables. Inspect any cables (e.g., between the
C-arm stand and display cart, from the C-arm,
connecting the footswitch) and their strain reliefs for general condition. Carefully examine
cables to detect breaks in the insulation and to
ensure that they are gripped securely in the
connectors at each end to prevent rotation or
other strain. Verify that there are no intermittent faults by flexing cables for the display near
each end and looking for erratic operation.
For units with rotating anode tubes, the highvoltage cables should be removed from the wells,
and the ends and the wells should be cleaned,
coated with high-voltage compound, reinserted,
and tightened securely.
1.10 Fittings/Connectors. Examine all electrical cable connectors for general condition. Electrical
contact pins or surfaces should be straight,
clean, and bright. Verify that leads and electrodes are firmly gripped in their appropriate
connectors. If keyed connectors are used, make
sure that no pins are missing and that the keying
is correct.
1.13 Controls/Switches. Before changing any controls or alarm limits, check their positions. If any
setting appears inordinate (e.g., high mA setting), consider the possibility of inappropriate
clinical use or of incipient device failure. Record
the settings of those controls that should be
returned to their original positions following the
inspection.
Examine all controls and switches (x-ray initiation, collimation, image manipulation, technique selection, size of image, etc.) for physical
condition, secure mounting, and correct motion.
Check that control knobs, if present, have not
slipped on their shafts. Where a control should
operate against fixed-limit stops, check for
1.18 Indicators/Displays. During the course of the
inspection, confirm the operation of all lamps,
indicators, meters, gauges, and visual displays
on the unit. Examples of indicators and displays
are technique settings, image modes, fluoroscopic exposure time, x-rays on, display monitor
text, and image storage numbers.
1.20 Alarms. Induce conditions to activate audible
and visual alarms (e.g., x-rays on). Check that
any associated interlocks (e.g., fluoroscopy inhibition) function. If the unit has an alarm silence
feature, check the method of reset (e.g., manual
or automatic) against the manufacturer’s specifications. It may not be possible to check out all
alarms at this time, since some may require
abnormal operating conditions (e.g., long exposure times). Instruct users to document activation of these alarms to ensure that they are
functional.
1.21 Audible Signals. Operate the device to activate
any audible signals (e.g., radiographic exposure,
boost or high-level control fluoroscopy). Confirm
appropriate volume. If audible alarms have been
silenced or the volume set too low, adjust alarm
volume to the appropriate level.
1.22 Labeling. Check that all necessary certification
labels, warning labels, technique charts, and
instruction cards are present and legible.
1.23 Accessories. Confirm the presence and condition
of accessories (e.g., film cassette holder, digital
acquisition systems, multiformat cameras, video
printers).
2. Quantitative tests
2.1
Grounding Resistance. Using an ohmmeter,
electrical safety analyzer, or multimeter with
good resolution of fractional ohms, measure and
record the resistance between common ground
and exposed metal on the C-arm, the control
stand, and the display cart. We recommend a
maximum resistance of 0.5 Ω. The footswitch
does not need to be grounded if it operates from
low voltages.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
3
Inspection and Preventive Maintenance System
2.2
2.3
Leakage Current. Measure chassis leakage current to ground with the grounding conductor of
plug-connected equipment temporarily opened.
Operate the device in all normal modes, including on, standby, during exposure, and off; record
the maximum leakage current. Chassis leakage
current should be 300 µA or less. For older Carms, leakage current up to 500 µA is acceptable,
provided that a documented maintenance schedule is established to ensure grounding integrity;
a three-month interval is a nominal period, but
may be adjusted depending on intensity of use
and previous experience.
Timer Accuracy. Use a noninvasive timer to
measure the accuracy of the timer settings available on the C-arm system when it is operated in
the radiographic mode. Most noninvasive kVp
meters also display exposure times. Follow the
manufacturer’s recommended technique for
making time measurements. Cover the image
intensifier with 6 mm thick lead plate to protect
the image intensifier and TV camera system.
Once the unit has been appropriately set up,
dial up a midrange kVp setting (e.g., 70 kVp).
The mobile C-arm may have a display only of
mAs rather than exposure time. If this is the
case, consult the C-arm manuals to find out what
mA is being used at 70 kVp in the radiographic
mode. The exposure time readings can then be
4
2.5
Accuracy of kVp. Use a noninvasive kVp meter
that has previously been calibrated against a
high-voltage divider on the type of generator
that powers the C-arm system. Use the kVp
meter in accordance with the recommendations
of the manufacturer of the kVp meter. (These
may include the kind of filters to use and the
distance at which the kVp meter has to be placed.
Some meters require that the user specify the
type of generator being tested and the amount of
filtration present in the primary x-ray beam.)
Take measurements in the radiographic and
fluoroscopic modes of operation of the C-arm at
low, medium, and high settings (e.g., 60, 80, and
100 kVp). After the appropriate corrections have
been applied to the measured kVp readings (e.g.,
for filtration), the difference between the measured kVp and the preset kVp should not exceed
5% of the preset kVp. If a consistent significant
error between the preset kVp and the measured
kVp is detected, further testing with a high-voltage divider may be required to identify the problem.
2.4
calculated from the mAs values. Conduct measurements at typically used low, medium, and
high time settings. As a general rule, the difference between the measured time and the preset
time should not exceed 1 ms or 5%, whichever is
greater.
Linearity of mAs. Use an ionization chamber
with an electrometer (or a combination exposure
meter) to measure the exposure in mR for this
test. The ionization chamber should be placed
centrally in the x-ray beam. The image intensifier should be covered with a lead plate to protect
it from excessive radiation.
Dial up a midrange kVp setting (e.g., 80 kVp)
with the C-arm set to operate in the radiographic
mode. Make radiographic exposures at this fixed
kVp, and record the exposure values (in mR)
from the electrometer or exposure meter at a
minimum of three settings that span the range
typically used. Calculate the mR/mAs at each
setting, and average the calculations. Each individual mR/mAs value should be within 10% of
the average.
2.6
Exposure Reproducibility. Use one of the above
mR/mAs values as the one value to be used for
evaluating short-term and long-term reproducibility of the x-ray tube and the generator combination. For the short-term test, make a
minimum of four exposures at the same mAs
over a span of approximately 15 minutes. The
mR/mAs value should have a coefficient of variation no larger than 10%. For long-term reproducibility, simply record the current average
mR/mAs value from the four values above and
compare this with the value recorded during the
preceding inspection. It is critical that identical
test conditions be used for assessing reproducibility. For example, the same chamber-to-source
distance should be used, and the technique (kVp,
mAs) should be the same. Long-term reproducibility should be within ±10% of the average.
2.7
Half-Value Layer (HVL). Use an ionization
chamber, electrometer, and Type 1100 aluminum filters for this test. Place the ionization
chamber on the image intensifier or at about 60
cm from the focal spot. Under fluoroscopic guidance, adjust the collimation on the C-arm so that
the x-ray field just encompasses the ionization
chamber.
Set the C-arm to operate in the radiographic
mode at 80 kVp. Select a midrange mAs value.
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©1995 ECRI. All Rights Reserved.
Mobile C-arms
These kVp and mAs values should be held constant during the whole course of this test.
Record the initial exposure value (in mR) with
nothing in the primary beam (i.e., 0 mm of aluminum). Then record the exposure reading with
aluminum thickness of 2 mm and 4 mm. The
thickness of aluminum required to reduce the
initial exposure reading by half is the half-value
layer of the beam. The HVL is most accurately
read by plotting the measurements on semilog
graphing paper. Plot the exposure values on the
logarithmic scale against the thickness of aluminum on the linear scale. At 80 kVp, the HVL
should be a minimum of 2.3 mm of aluminum.
The HVL measurement should be compared to
measurements from previous inspections, since
a change in HVL may indicate tube deterioration.
2.8
Collimation. Place a ruler with leaded 1 cm or
1/2″ markers on the image intensifier housing,
and measure the visual field size (length and
width) of the image intensifier on the display
monitor during a fluoroscopic exposure using the
largest available mode on the image intensifier.
Next, place a large-format x-ray film (30 cm by
30 cm minimum) on the image intensifier housing and make a fluoroscopic exposure, still using
the largest available mode on the image intensifier. A fluoroscopic exposure of about five seconds is likely to provide sufficient film
darkening. After the film has been processed,
ensure that the dimensions of the x-ray beam
measured on the film do not differ from the
dimensions of the fluoroscopic image measured
with the lead ruler by more than 3% of the
source-to-image distance (SID).
2.11 Standard Fluoroscopic Exposure Rate. In addition to verifying that the unit meets exposure
requirements, this test also verifies functioning
of the ABS system.
Use an ionization chamber with an electrometer (or a combination exposure meter) capable of
measuring exposure rate. Place the chamber or
the meter 30 cm above the image intensifier
input plane. Place sufficient patient simulator
material on the image intensifier that the technique tracks to about midrange (e.g., 70 kVp) in
the automatic fluoroscopic mode.
Run a fluoroscopic exposure, and record the
exposure rate. Check for consistency of the exposure rate with those made during previous
inspections. The typical exposure rate is 1 R/min
(with a range of 0.5 to 2.0 R/min). If the exposure
rate has increased from that of previous inspections, further testing should be performed to
determine the reason for the required increase
in radiation.
2.12 Maximum Fluoroscopic Exposure Rate. Use an
ionization chamber with an electrometer (or a
combination exposure meter) capable of measuring exposure rate. Place a thick lead plate (at
least 6 mm thick) over the image intensifier
housing. Ensure that the whole input face of the
image intensifier is covered by the lead plate.
Place the ionization chamber 30 cm above the
image intensifier input plane.
Record the exposure rate on the electrometer
or exposure meter during a fluoroscopic exposure in the automatic mode, as well as in the
manual mode at the highest technique. If the
C-arm also has a “boost” or “high-level” control
mode, record the exposure rate during a fluoroscopic exposure in this mode. For units that have
only manually selectable kVp and mA settings,
the exposure rate at the highest settings should
not exceed 5 R/min. For units that have automatic kVp and mA control, the exposure rate should
not exceed 10 R/min.
There are no governmental regulations that
limit exposure rates under boost mode for devices in use now. However, for devices manufactured in 1996 and after, the exposure rate in the
boost or high-level control mode should not exceed 20 R/min.
2.13 Image Quality.
High-Contrast Resolution. Place the line-pair
phantom on the grid. It should be placed at a
45-degree angle to the grid lines and raster
lines of the TV system. At low kVp (ABS with
nothing other than the line-pair phantom in
the field), determine the maximum line-pair
resolution for all available field sizes. It may
be necessary to alter the brightness and contrast settings on the TV monitor to optimize
the display for the visualized object. Resolution should be at or above 1.2 lp/mm for a 22
cm (9″) field of view (FOV) and 1.7 lp/mm for
a 15 cm (6″) FOV.
Low-Contrast Resolution. Ensure that the 1 mm
piece of aluminum is next to the grid. Place the
low-contrast phantom on the grid. The thicker
aluminum pieces should be on top of the 1 mm
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
5
Inspection and Preventive Maintenance System
thick plate. Initiate a fluoroscopic exposure
under ABS control. On the 15 cm (6″) FOV,
the three smallest holes should be visible. It
may be necessary to alter the brightness and
contrast settings on the TV monitor to optimize the display for the visualized object.
3. Preventive Maintenance
3.1
Clean the exterior, as well as the interior if needed.
3.2
Lubricate per the manufacturer’s instructions.
3.3
Calibrate per the manufacturer’s instructions.
Adjust caster brakes and arm locks, if needed.
6
4. Acceptance Tests
Acceptance testing is typically performed by a medical physicist.
Before returning to use
Ensure that all controls are set properly. Set alarms
loud enough to alert personnel in the area in which the
device will be used. Other controls should be in their
normal pre-use positions.
Attach a Caution tag in a prominent position so that
the user will be aware that control settings may have
been changed.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Procedure/Checklist 468-0595
Mobile X-ray Units
Used For:
Radiographic Units, Mobile [13-272]
Also Called: Mobile radiographic systems, portable x-ray machines
Commonly Used In: Patient rooms, surgical suites
Scope: Applies to portable radiographic systems powered from or charged by a standard 115 VAC receptacle
Risk Level: ECRI Recommended, High; Hospital Assessment,
Type
ECRI-Recommended
Interval
Major
12 months
months
.
hours
Minor
6 months
months
.
hours
Overview
Mobile x-ray units are used for radiographic imaging
of patients who cannot be moved to the radiology
department and who are in areas, such as intensive
care units or emergency rooms, that lack standard,
fixed radiographic equipment. These units consist of
an x-ray generator, an x-ray tube and tubestand, collimators, and a film cassette storage drawer. Batterypowered units also contain a battery and charging
system, and self-propelled units contain a motor drive.
One of three different types of x-ray generators can
be used: a line-powered transformer, a capacitor-discharge generator, or a battery-powered transformer.
Line-powered transformers use 120 or 220 VAC for
x-ray production. A step-up transformer increases the
voltage, and a rectifier converts the AC to the DC
required by the x-ray tube. In a capacitor-discharge
generator, 110 or 220 VAC power is fed into a step-up
transformer; the output is then rectified and used to
charge a large capacitor or group of capacitors, which
are then discharged through a grid-controlled x-ray
tube. Because the capacitors are charged to the same
potential, each exposure begins at the same peak kilovoltage (kVp), but the kV will decrease during exposure as the capacitor discharges. At the end of each
241473
468-0595
A NONPROFIT AGENCY
Interval Used
By Hospital
Time Required
exposure, the capacitor(s) must be recharged. In a
battery-powered generator, line power is used to
charge lead-acid batteries; the fully charged unit can
then be operated independently of an outside power
source until the batteries need to be recharged. Battery-powered generators supply a constant kV and
current throughout the exposure.
The x-ray tube assembly, which includes the x-ray
tube and collimator, is attached to a tubestand that
can be rotated about its base or moved horizontally and
vertically. The x-ray tube anode is either stationary or
rotating. Filters are placed in the path of the x-ray
beam to absorb the less penetrating x-rays. After the
beam passes through the filters, a set of collimators
confines the primary beam to the size and shape that
will cover the area of diagnostic interest.
Because of design constraints, tube current in
mobile units is often lower than in stationary radiographic systems. Therefore, radiographs taken with
mobile units are usually of poorer quality. Furthermore, because patient positioning and film placement
are more difficult with bedside radiography, the overall image quality is lower, as well. Mobile radiographic
units are designed for use only when patient transport
is contraindicated; the radiology department, with
5200 Butler Pike, Plymouth Meeting, PA 19462-1298, USA
Telephone +1 (610) 825-6000 ● Fax +1 (610) 834-1275
●
E-mail [email protected]
Inspection and Preventive Maintenance System
fixedradiographic equipment, offers a more controlled,
optimal setting for imaging.
maintenance procedures or frequencies are recommended by the manufacturer.
Test apparatus and supplies
This procedure is intended to ensure adequate system performance and maintenance. It should not be
construed as providing full compliance with the requirements of all governmental regulations and accreditation standards of professional associations.
Such regulations and standards may include testing
beyond that provided below and may also require documentation by a certified medical physicist.
Ground resistance ohmmeter
Leakage current meter or electrical safety analyzer
Noninvasive kVp meter (compatible with the x-ray
generator being inspected)
Noninvasive timer (may be included with the kVp
meter)
Ionization chamber with electrometer or a combination exposure meter
Five filters of 10 cm × 10 cm × 1 mm Type 1100
aluminum
Collimator alignment template marked in centimeters or inches
For acceptance testing, we strongly recommend using a medical physicist. Acceptance testing is crucial
because it generates data on baseline performance of
the device.
1. Qualitative tests
1.1
Chassis/Housing. Examine the exterior of all
components of the portable x-ray unit for cleanliness and general physical condition. Be sure
that all hardware is present and tight, and that
there are no signs of spilled liquids, deep
scratches, dents, or other serious abuse. Check
the mechanical operation of all moving parts to
include any film storage compartment, as well as
all movements of the x-ray tube, x-ray tube support, and collimator, ensuring that all movements are smooth with no binding or undue
resistance.
1.3
Casters/Brakes. Verify that the casters turn
and swivel freely. Look for accumulations of dirt
and grime around the casters. Check the ease of
steering. Check the brake or locking device for
each movement of the x-ray tube, x-ray tube
support, and collimator. Ensure that all locks
function properly and hold securely.
1.4
AC Plug/Receptacles. Examine the AC power
plug for damage and ensure that the AC plug is
clamped securely to the line cord. If you find
evidence that the plug is being removed from the
receptacle by pulling on the cord, caution users
against this practice. Attempt to wiggle the
blades to check that they are secure. Shake the
plug and listen for rattles that could indicate
loose screws. If any damage is suspected, open
the plug and inspect it.
1.5
Line Cord. Inspect the cord for signs of damage.
If damaged, replace the entire cord or, if the
damage is near one end, cut out the defective
portion. Ensure that the remaining length is
adequate. Be sure to wire a new power cord or
plug with correct polarity.
Medium-format x-ray film (25 cm × 30 cm or 10″ × 12″)
Ten pieces of 30 cm × 30 cm × 2.5 cm plexiglass (or
another patient-simulating material for testing the
automatic exposure control [AEC])
Densitometer
Oscilloscope (calibration only)
High-voltage divider (calibration only)
Special precautions
Wear a lead apron and thyroid shield. Maintain the
greatest possible reasonable distance from the x-ray
source and all scattering material during all x-ray
exposures. It should not be necessary to place hands or
fingers in the x-ray beam. If this is unavoidable, wear
lead gloves.
Do not remove the high-voltage cables from the
wells with the power on. Ensure that high-voltage
cables are completely discharged by repeatedly touching the conductor to ground as soon as it is removed
from the well.
Wear rubber gloves or other appropriate protection
when exposed to blood or other body fluids.
Allow adequate time between repeated exposures to
prevent overheating of the x-ray tube.
Procedure
Before beginning an inspection, carefully read this
procedure and the manufacturer’s instruction and
service manuals; ensure that you understand how to
operate the equipment, the significance of each control
and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive
2
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Mobile X-ray Units
1.6
Strain Reliefs. Examine the strain reliefs at
both ends of the line cord. Be sure that they hold
the cord securely.
1.7
Circuit Breaker/Fuse. If the device has an external circuit breaker, check that it operates freely. If
the device is protected by an external fuse, check
its value and type against that marked on the
chassis and ensure that a spare is provided.
1.9
Cables. Inspect any cables (e.g., collimator cables, high-voltage cables) and their strain reliefs
for general condition. Carefully examine cables
to detect breaks in the insulation and to ensure
that they are gripped securely in the connectors
at each end to prevent rotation or other strain.
For cables other than high-voltage cables, verify
that there are no intermittent faults by flexing
electrical cables near each end and looking for
erratic operation. Use an ohmmeter if a problem
is suspected. High-voltage cables should be removed from the wells (at the x-ray tube ends),
cleaned, coated with high-voltage compound, reinserted, and tightened securely. The high-voltage transformer end should not require routine
inspection if the wells are vertical and high-voltage oil is used.
1.10 Fittings/Connectors. Examine all electrical cable
connectors for general condition. Electrical contact
pins or surfaces should be straight, clean, and
bright. If keyed connectors are used, make sure
that no pins are missing and that keying is correct.
1.12 Filters. Check the condition of any air filters
present in the systems. Clean or replace as
needed.
1.13 Controls/Switches. Before changing any controls or alarm limits, check their positions. If
any settings appear inordinate (e.g., high mA
setting), consider the possibility of inappropriate clinical use or of incipient device failure.
Record the setting of those controls that should
be returned to their original positions following
the inspection. Examine all controls and
switches (x-ray initiation, collimation, technique selection, etc.) for physical condition, secure mounting, and correct motion. Check that
control knobs, if present, have not slipped on
their shafts. Where a control should operate
against fixed-limit stops, check for proper alignment, as well as positive stopping. During the
inspection, be sure to check that each control
and switch performs its proper function. Ensure
that radiographic exposure switches do not
stick, that continuous pressure is required to
continue exposure, and that release of pressure
immediately terminates exposure. Ensure the
proper operation of the two-position exposure
switch (i.e., ensure that the x-ray exposure is not
released by the first trigger only), if present.
1.17 Battery/Charger. Using a multimeter, measure
the battery voltage. (Consult the manufacturer’s
documentation for appropriate measuring
points.) Verify that the level of charge is accurately represented by the level-of-charge indicator on the operator’s panel. Verify that the
battery charger automatically stops charging
when the appropriate state of charge is reached.
Ensure that any cooling or ventilation fans operate properly.
1.18 Indicators/Displays. During the inspection,
confirm the operation of all lamps, indicators,
meters, gauges, and visual displays on the unit.
Examples of indicators and displays are technique settings, exposure time, and x-ray on. Inspect the source-to-image distance (SID)
indicator (usually a tape measure). Ensure that
it is present, operates smoothly, and is accurate.
1.20 Alarms. Induce conditions to activate audible and
visual alarms (e.g., x-ray on). Check that any associated interlocks (e.g., x-ray tube park) function. If
the unit has an alarm silence feature, check the
method of reset (e.g., manual or automatic) against
the manufacturer’s specifications. It may not be
possible to check out all alarms at this time, since
some may require abnormal operating conditions.
Instruct users to document activation of these
alarms to ensure that they are functional.
1.21 Audible Signals. Operate the device to activate
any audible signals (e.g., radiographic exposure,
audible signal during motorized drive if applicable). Confirm appropriate volume. If audible
alarms have been silenced or the volume set too
low, adjust alarm volume to the appropriate level.
1.22 Labeling. Check that all necessary certification
labels, warning labels, technique charts, and
instruction cards are present and legible.
1.23 Accessories. Confirm the presence and condition
of accessories (e.g., film cassette holder).
1.24 Drive Mechanism (for motor-powered units only).
Ensure that the drive system operates smoothly,
does not pull to one side or the other, and makes
no unusual noises (e.g., apparent binding,
squeaking). If there are variable-speed controls
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3
Inspection and Preventive Maintenance System
been appropriately set up, dial up a midrange
kVp setting (e.g., 80 kVp). The unit may have a
display only of mAs rather than exposure time.
If this is the case, consult the instruction and
service manuals to find out what mA is being
used at 80 kVp. The exposure time readings can
then be calculated from the mAs values. Conduct
measurements at typical low, medium, and high
settings. The difference between the measured
time and the preset time should not exceed ±1
msec or ±5%, whichever is greater.
present, test their operation. Verify that the
bumper switches disable the drive circuitry for
both forward and reverse motions. Verify that
any interlocks associated with the drive circuitry
are functional (e.g., that an x-ray tube not in
park position allows slow drive only, that the
main drive handle must be depressed or
squeezed to allow movement).
2. Quantitative tests
2.1
2.2
2.3
2.4
4
Grounding Resistance. Using an ohmmeter,
electrical safety analyzer, or multimeter with
good resolution of fractional ohms, measure and
record the resistance between common ground
and exposed metal on the portable x-ray unit. We
recommend a maximum resistance of 0.5 Ω.
Leakage Current. Measure chassis leakage current to ground with the grounding conductor of
plug-connected equipment temporarily opened.
Operate the device in all normal modes, including on, standby, exposure, and off, and record the
maximum leakage current. Chassis leakage current should be 300 µA or less. For older portable
x-ray units, up to 500 µA is acceptable, provided
that a documented maintenance schedule is established to ensure grounding integrity; three
months is an acceptable interval, but may be
adjusted depending on the intensity of use and
on previous experience.
Accuracy of kVp. Use a noninvasive kVp meter
that has previously been calibrated against a highvoltage divider on the type of generator that powers the portable x-ray unit. Use the meter in
accordance with the manufacturer’s recommendations. (These may include the kind of filters to use
and the distance at which the kVp meter has to be
placed. Some meters require that the user specify
the type of generator being tested and the amount
of filtration present in the primary x-ray beam.)
Make measurements at low, medium, and high
settings (e.g., 60, 80, 100 kVp). After the appropriate corrections have been applied to the measured
kVp readings (e.g., for filtration), the difference
between the measured kVp and the preset kVp
should not exceed ±5% of the preset kVp.
Timer Accuracy. Use a noninvasive timer to
measure the accuracy of the time settings available on the unit when it is operated in the
radiographic mode. Most noninvasive kVp meters also display exposure times. Follow the
manufacturer’s recommended technique for
making time measurements. Once the unit has
2.5
Linearity of mAs. Use an ionization chamber
with an electrometer (or a combination exposure
meter) to measure the exposure in mR for this
test. The ionization chamber should be placed
centrally in the x-ray beam at a known standard
distance from the focal spot (e.g., 100 cm). Dial
up a midrange kVp setting (e.g., 80 kVp). Make
radiographic exposures at this fixed kVp and
record the exposure values (in mR) from the
electrometer or exposure meter at a minimum of
three mA settings that span the range commonly
used for a generator with variable mA. Also use
three mAs settings for constant mA generators.
Calculate the mR/mAs at each setting and average the calculations. Each individual mR/mAs
value should be within 10% of the average.
2.6
Exposure Reproducibility. Use one of the above
mR/mAs values as the one value to be used for
evaluating short-term and long-term reproducibility of exposure. For the short-term test, make
a minimum of four exposures at the same mAs
over a span of 15 minutes. The mR/mAs values
should have a coefficient of variation no larger
than 10%. For long-term reproducibility, simply
record the current average mR/mAs value, and
compare it with the value recorded during the
preceding inspection. It is critical that identical
test conditions be used for assessing reproducibility. For example, the same chamber-to-source
distance should be used, and the technique (kVp,
mAs) should be the same. Long-term reproducibility should be within ±10% of the average.
2.7
Half-Value Layer (HVL). Use an ionization
chamber, electrometer, and Type 1100 aluminum filters for this test. Place the ionization
chamber in the center of the x-ray beam at about
100 cm from the focal spot. Collimate so that the
x-ray field just encompasses the ionization
chamber. Set the unit to operate at 80 kVp.
Select a midrange mAs value. These kVp, mAs
values should be held constant during the whole
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Mobile X-ray Units
course of this test. Record the initial exposure
value (in mR) with nothing in the primary beam
(i.e., 0 mm of aluminum). Then record the exposure reading with aluminum thicknesses of 2 mm
and 4 mm. The thickness of aluminum required
to reduce the initial exposure reading by half is
the HVL of the beam. The HVL is most accurately
read by plotting the measurements on semilog
graphing paper. Plot the exposure values on the
logarithmic scale against the thickness of aluminum on the linear scale. At 80 kVp, the HVL
should be a minimum of 2.3 mm of aluminum.
The HVL measurement should be compared to
measurements from previous inspections since a
change in HVL may indicate tube deterioration.
2.8
Collimation. Place a medium-format x-ray film
(25 cm × 30 cm or 10″ × 12″), at an SID of 100 cm
(40″). Ensure that the x-ray film is perpendicular
to the x-ray beam. Precisely center the collimator
alignment tool on the cassette. Turn on the collimator light and collimate to an area of 20 cm ×
20 cm. Ensure that the light beam is exactly
centered on the collimator alignment tool. Note
the exact readout of the exposure area size indicators. Record the exact size of the illuminated
boundaries from the collimator alignment tool.
Make an x-ray exposure (for a film/screen speed
of 400, a technique of 55 kVp and 5 mAs should
be sufficient), and process the x-ray film.
Congruence of the light field to the x-ray field.
Measure the distances L1, L2, W1, and W2 on
the processed film. The sum of W1 + W2 + L1
+ L2 is the total misalignment between the
light field and the x-ray field. This sum must
not exceed 2% of the SID; that is, at an SID of
100 cm, the misalignment should not exceed
2 cm. See Figure 1.
Field size indicators versus actual exposed area.
Measure the length and width of the exposed
area on the exposed film. Compare the actual
size of the exposed area to the readout of the
exposure area size indicators noted earlier.
The dimensions of the exposed area must be
within 2% of the SID — that is, 2 cm at an SID
of 100 cm.
2.9
AEC Object Thickness Compensation (for units
provided with an AEC system). This test is to be
conducted on each available radiographic image
receptor holder (e.g., spot-film, table Bucky, wall
Bucky). Place 20 cm of 30 cm × 30 cm plexiglass
on the table or support it up against the wall
Bucky. (It is acceptable to use another patient
simulating material for AEC tests, such as aluminum.) Ensure that the plexiglass covers the
AEC detectors. Set the unit to operate at 80 kVp
(or some other setting commonly used to image a
medium-sized patient). Load a cassette of a size
commonly used with the standard film used at
the facility, and place this into the receptor holder
being tested. Then make an AEC-controlled exposure. Process the film on a processor that has
previously been verified as operating optimally.
″
″
Figure 1. Schematic showing misalignment of the light field with respect to the x-ray field
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5
Inspection and Preventive Maintenance System
Use a densitometer to measure the optical density of the radiograph in the center of the image.
If the optical density falls within the range chosen by the radiologists (typically 1.2-1.4 OD),
repeat the test using identical setup conditions
but with varying amounts of plexiglass in the
beam. At a minimum, check the optical density
at 15 cm and 25 cm of plexiglass. All films used
in this test should come from the same batch,
and only one cassette is to be used for all exposures. The optical density of all the processed
films should agree to within ±0.3 OD of the
optical density at 20 cm.
2.10 AEC kVp Compensation (for units provided with
an AEC system). This test should also be conducted on each available radiographic image receptor holder (spot-film, table Bucky, and wall
Bucky). Place 20 cm of plexiglass (or some other
patient simulating material) on the table or support it up against the wall Bucky. Ensure that
the AEC detectors are covered by the plexiglass.
Use the most common size of films in the same
cassette holder for all checks in this test. Make
a series of AEC-controlled exposures of the 20 cm
of plexiglass at different kVp values. At a minimum, use three kVp settings (e.g., 60, 80, 100
kVp). For each exposure, process the film on an
optimally performing processor. Read the optical
density of the radiograph using a densitometer.
6
The optical density of the films at all kVp settings checked should agree to within ±0.3 OD.
3. Preventive maintenance
3.1
Clean the exterior and interior. Take precautions when dealing with body fluids.
3.2
Lubricate per the manufacturer’s instructions.
3.3
Calibrate the system to ensure performance
within the manufacturer’s specifications, at intervals recommended by the manufacturer or as
indicated by inspection results. Adjust all brakes
and locks to ensure proper performance.
3.4
Replace components if needed.
4. Acceptance Tests
Acceptance testing is typically performed by a medical physicist.
Before returning to use
Ensure that all controls are set properly. Set alarms
loud enough to alert personnel in the area in which the
device will be used. Other controls should be in their
normal pre-use positions. Attach a Caution tag in a
prominent position so that the user will be aware that
control settings may have been changed. Recharge
battery-powered devices or equip them with fresh batteries, if needed.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Procedure/Checklist 447-0595
Nd:YAG Surgical Lasers
Used For:
Lasers, Surgical, Nd:YAG [16-943]
Also Called: YAG lasers (incorrectly), continuous-wave YAG lasers, surgical lasers, urology lasers,
angioplasty lasers, bronchopulmonary lasers, gastroenterology lasers, neurosurgical lasers, photocoagulator
lasers
Commonly Used In: Operating rooms, short procedure areas, cystology rooms, catheterization laboratories, endoscopy laboratories, radiology areas
Scope: Applies to general-purpose Nd:YAG surgical lasers that include contact (e.g., sapphire tip) and/or
noncontact flexible fiberoptic delivery systems (either reusable or disposable), emit near-infrared energy at
1,064 nm, and can provide sufficient power output to coagulate and vaporize tissue; applies to low- and
high-power Nd:YAG surgical lasers that are typically used for general surgery, urology, cardiovascular surgery,
gastroenterology, bronchopulmonary, neurosurgery, gynecology, ENT, and plastic surgery procedures; applies
to the Nd:YAG portion of units that combine the Nd:YAG wavelength with other wavelengths (e.g., KTP or
CO2); does not apply to ophthalmic Nd:YAG lasers or to Nd:YAG lasers that are, for example, frequencydoubled and do not emit energy for delivery to the patient at 1,064 nm (frequency-doubled units are covered
in Procedure/Checklist 464); also does not apply to CO2 lasers, argon lasers, or other ophthalmic lasers;
however, many of the tests listed herein can be used or modified for these other lasers
Risk Level: ECRI Recommended, High; Hospital Assessment,
Type
ECRI-Recommended
Interval
Major
12 months
months
.
hours
Minor
6 months
months
.
hours
Overview
Nd:YAG lasers are normally checked before each use
by the laser’s power-on self-test and by user examination of the aiming beam and calibration of the system
with the delivery system to be used. This minimizes
the need for frequent additional periodic testing.
Interval Used
By Hospital
Time Required
sers must be meticulously maintained to ensure proper
and safe operation.
Manufacturers or outside service vendors often
maintain lasers for hospitals. The extent and frequency of inspection by hospital personnel should be
coordinated with these outside services.
Nd:YAG surgical lasers affect tissue by delivering
invisible near-infrared energy at a sufficient power density to cause photocoagulation, thermal denaturation,
and/or vaporization of tissue. The 1,064 nm Nd:YAG
energy is not well absorbed by any tissue and is typically
scattered over a 5 mm depth within tissue. Nd:YAG
surgical lasers are frequently used to cause photocoagulation or thermal denaturation of tissue in the noncontact mode or with quartz or sapphire contact tips.
Failure of an Nd:YAG surgical laser can cause patient or staff injury, abrupt interruption of a surgical
procedure, or damage to the laser system. These la-
General-purpose Nd:YAG surgical lasers have a
laser cavity that houses an yttrium-aluminum-garnet
(YAG) crystalline rod that is doped with neodymium
046828
447-0595
A NONPROFIT AGENCY
5200 Butler Pike, Plymouth Meeting, PA 19462-1298, USA
Telephone +1 (610) 825-6000 ● Fax +1 (610) 834-1275
●
E-mail [email protected]
Inspection and Preventive Maintenance System
(Nd). Energy leaving the laser tube through a partially
reflecting mirror is typically directed into a flexible optical fiber that transmits the laser energy to the tissue. The
fiber may be used with additional connectors (e.g.,
through an endoscope), with contact tips or contact-tip
fibers connected, and/or with a laser handpiece or a laser
micromanipulator (used to interface the laser with the
surgical microscope) connected. These attachments can
focus the energy into a small spot size at a known
working distance or a specific beam pattern to accomplish a specific task. In a few cases (e.g., the Trimedyne
Laserprobes SLT contact tips), the laser energy is transformed into thermal energy to heat a catheter tip, which
then causes the clinical effect; in this case, no or very little
direct laser irradiation of tissue occurs.
Because the near-infrared energy emitted by the
Nd:YAG laser is invisible, a second, nontherapeutic
aiming helium-neon (He-Ne) laser — which emits visible red light — a red diode laser, or a xenon lamp with
filters to emit white or blue light simultaneously traverses the fiber and is coincident (i.e., travels the same
path) with the Nd:YAG laser beam.
Like most lasers, Nd:YAG lasers are inefficient in
converting electrical energy into laser energy of 0 to 140
W. As a result, excess heat is generated in the laser
tube, requiring a cooling system. Some Nd:YAG lasers
use internal water/air cooling systems, while others
require external connection to a water source and drain
or to a freestanding cooling system. Most Nd:YAG laser
fibers require gas or liquid cooling as well for certain
applications. As a result, gas compressors/regulators
and/or fluid pumps are typically integral or attached to
these lasers. Because Nd:YAG laser fibers may be used
in body cavities (e.g., during gastroscopy), some lasers
may include a gas recirculation system that inserts gas
to cool the fiber and/or insufflate the cavity and withdraw gas to limit pressure and avoid distension.
With Nd:YAG lasers, unlike those lasers that use
mirror delivery systems (e.g., articulating arms on CO2
lasers), it is not necessary to periodically verify coincidence of the aiming and therapeutic beam or to assess
the therapeutic beam pattern (e.g., TEM00) within the
beam or spot. Since the therapeutic and aiming laser
beams are transmitted through a single optical fiber,
these two beams are coincident as they exit the fiber.
Any beam pattern distortion at the fiber entrance
would be eliminated as the laser beams travel through
the fiber because of internal reflections within the
fiber. Misalignment of the beam at the fiber entrance
would result in decreased power output or loss or
distortion of the aiming beam. In a well-aligned system, any significant problem with the therapeutic
2
beam pattern introduced by an accessory would be
apparent by examining the visible aiming beam.
Citations from Health Devices
Lasers in medicine: An introduction, 1984 Jun;
13:151-78.
Lasers as investigational devices: Appendix A, 1984
Jun; 13:167-9.
Lasers: Model policy and procedures statement: Appendix B, 1984 Jun; 13:169-71.
Loss of metal nozzle on Nd:YAG surgical laser fibers
[User Experience NetworkTM], 1987 Mar-Apr; 16:115.
Fatal gas embolism associated with intrauterine laser
surgery [Hazard], 1989 Sep; 18:325-6.
Surgical lasers [Evaluation], 1991 Jul-Aug; 20:239-316.
Test apparatus and supplies
Leakage current meter or electrical safety analyzer
Ground resistance ohmmeter
New, unused fiber delivery system
Black Delrin block ≥1⁄2″ thick, ≥1″ wide, about 3″ to
4″ long; tongue depressors; or firebrick
Laser radiometer (power meter)
Laser safety signs
Laser safety eyewear specifically designed for use
with Nd:YAG surgical lasers and of sufficient optical density to protect the wearer’s eyes from laser
injury
Vise with padded jaws or ring stand with padded
clamp
Pressure gauges and coolant system tee fitting
Outlet test fixture (optional)
Insulating gloves, high voltage (optional)
Grounding strap (optional)
Calibrated flowmeter
Special precautions
Inspecting and maintaining lasers is a dangerous as
well as necessary process, and far greater care is
required than with most devices. Personnel who inspect or service lasers should receive special training
from the manufacturer or from a qualified alternative
training source.
Laser energy can cause serious injury, particularly
when the internal interlock is overridden or in any
other situation in which the energy does not diverge
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Nd:YAG Surgical Lasers
significantly over long distances. Under some circumstances, the beam may not diverge significantly, even
a full room length or more away from the laser (and
can harm tissue or burn material even at this distance). Therefore, exercise great care whenever a laser
beam is accessible. Area security and use of personnel
protective devices and practices should be consistent
with hospitalwide laser safety procedures and/or be
approved by the laser safety committee.
In addition, windows should be covered with nonreflective material to prevent transmission of laser energy to other areas.
Wear appropriate laser safety eyewear at all times
whenever the laser is in the Operating mode. WARNING: Laser safety eyewear may not protect the wearer
from the aiming system light. Do not stare directly into
the aiming system beam or the therapeutic laser beam,
even when wearing laser safety eyewear. Avoid placing
the laser beam path at eye level (i.e., when kneeling,
sitting, or standing).
Do not perform these procedures when a patient is
present or clinical staff is working, and do not aim the
laser across a path that a person might normally use
as a thoroughfare. Furthermore, at minimum, post
doors to the room with appropriate laser safety signs
stating that the laser is in use and that it is unsafe to
enter the room without authorization by the service
person performing the procedure. A second person
should be present, especially during procedures of recognized risk, to summon help in case of an accident.
Some surgical lasers use high voltages (e.g., 20 kV),
which can be lethal. Capacitors may store charges
long after the device has been disconnected from line
voltage. Consult the manufacturer’s recommended
procedures for servicing high-voltage laser circuits,
and avoid contact with any portion of the high-voltage
circuit until you are certain that the charge has been
drained. In such instances, a good ground must be
present; preferably, use a redundant ground strap if
you must enter the laser cabinet. When possible, disconnect the laser from line voltage before entering the
laser cabinet, and use insulated gloves for those procedures in which contact with a high-voltage source is
possible (and the gloves are not otherwise contraindicated). Ensure that equipment intended to be used to
measure, drain, or insulate high voltages carries the
appropriate insulation rating (e.g., above 20 kV).
Where possible, perform tests with the unit turned
off. Because of the presence of high voltage, perform
the Grounding Resistance test (Item 2.1) before any
other item that requires operation of the laser.
WARNING: Do not use an anesthesia or other similar bag that may have a mold-release agent (e.g., starch,
talc) on its inside surface because the agent could
contaminate the gas recirculation system of the laser
and ultimately contaminate a patient wound during a
subsequent procedure.
Report any laser accident immediately to the laser
safety officer or equivalent, as well as to the hospital
risk manager.
Procedure
The laser should remain in the Off position when
not in use. When in use, the laser should be in the
Standby/Disabled mode. Do not switch it to the Operating mode until the procedure is about to begin and
the laser and its delivery system are properly positioned. If the procedure must be interrupted, disconnect the laser from line voltage, and remove the laser
operation key and store it in a controlled location.
Before beginning the inspection, carefully read this
procedure and the manufacturer’s instruction and service manual; be sure that you understand how to operate
the equipment, the significance of each control and indicator, and precautions needed to ensure safety and avoid
equipment damage. Also determine whether any special
inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer.
Do not use the laser in the presence of flammable
anesthetics or other volatile substances or materials
(e.g., alcohol), or in an oxygen-enriched atmosphere, because of the serious risk of explosion and fire. Remove
from the working area or cover with flame-resistant
opaque material all reflective surfaces likely to be contacted by the laser beam. Whenever possible, use a
firebrick or other nonflammable material behind the
target material (e.g., black Delrin) when the laser is to
be activated. Target materials will ignite when exposed
to high laser energies; use short durations when practical. A CO2 fire extinguisher should be readily available.
1. Qualitative tests
1.1
Chassis/Housing.
General. Verify that the key has not been left in
the laser. (Remove it if it has, and inform
users of the importance of storing the key in a
controlled location.) Examine any external
gas tanks that may be in use with the laser,
and ensure that they have been turned off
after the last use. Examine the exterior of the
unit for cleanliness and general physical condition. Be sure that all housings are intact
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
3
Inspection and Preventive Maintenance System
and properly aligned, that assembly hardware
is present and tight, that any retractable parts
slide easily and lock in place if so constructed,
that there are no signs of spilled liquids or other
evidence of abuse, and that there are no obvious
signs of water or oil leakage.
Shutters. If manual shutters for the aiming system or therapeutic laser are accessible, ensure that they operate smoothly and correctly.
Be sure to leave the shutter in the proper
position for normal operation.
1.2
1.3
Mounts/Holders. Check that the mounts securely contain any gas cylinders that may be in
use. Be sure that mounts or holders intended to
secure the fiber to the fiber support (to protect
the fiber when in use) are present, in good working order, and being used. Similarly, check
mounts or holders for other devices (e.g., external power meters, footswitches).
Casters/Brakes. Check that the casters roll and
swivel freely. Check the operation of brakes and
swivel locks.
1.4
AC Plug/Receptacle. Examine the AC power
plug for damage. Wiggle the blades to determine whether they are secure. Shake the plug,
and listen for rattles that could indicate loose
screws. If you suspect damage, open the plug
and inspect it.
1.5
Line Cords. Inspect line cords for signs of damage. If a cord is damaged, replace the entire cord,
or, if the damage is very near one end, cut out
the defective portion. Be sure to wire a new
power cord or plug with the correct polarity.
1.6
Strain Reliefs. Examine the strain reliefs at
both ends of the line cord. Be sure that they grip
the cord securely.
1.7
Circuit Breakers/Fuses. If the device has a
switch-type circuit breaker, check that it moves
freely. If the device is protected by an external
fuse(s), check its value and type against what is
marked on the chassis or noted in the instruction
or service manual. Ensure that a spare is provided or readily available.
1.8
4
Tubes/Hoses. Check the condition of all cooling-system hoses and any other hoses or tubing
the laser may have (e.g., drain, gas). Check that
they are of the correct type; that they have not
become cracked and do not show other signs of
significant abuse; that they are connected correctly and positioned so that they will not leak,
kink, trail on the floor, or be caught in moving
parts; and that they are secured adequately to
any connectors.
1.9
Cables. Inspect all cables and their channels or
strain reliefs for general physical condition. Examine cables carefully to detect breaks in insulation and to ensure that they are gripped
securely in the connectors at each end to prevent
strain on the cable.
1.10 Fittings/Connectors. E xam ine all optical
(e.g., fiber), gas, liquid, and electrical fittings
and connectors for general physical condition.
Gas and liquid fittings should be tight and not
leak. Electrical contacts should be straight,
clean, and bright.
There should be no visible dirt or residue in
the optical path of the laser aperture. Ensure
that any mechanism to close off the fiber laser
aperture (fiber port) is clean, operates smoothly,
and is in use.
If external gas tanks or wall-supply outlets
can be used, gas-specific connectors should be
present. Be sure that no pins are missing from
yokes and that the keying and indexing of connectors for each gas to be used is correct. A laser
that connects to a central piped medical gas
system or to a freestanding medical gas system
should have the matching DISS or quick-connect
fitting for the gas that it is to be used with.
Verify that suitable connectors are supplied so
that adapters are not required.
1.12 Filters. Check the condition of all liquid and air
filters. Some Nd:YAG surgical lasers require
deionized water, and most require special filtration. Measuring the pressure drop across a liquid
filter can be helpful in determining whether the
filter should be replaced. Clean or replace filters
according to the manufacturer’s recommendations (e.g., replace if the pressure drop is >5 psi),
and indicate this in the preventive maintenance
section of the inspection form. Clean or replace
air filters and radiators that are obviously dirty.
1.13 Controls/Switches.
General. Before moving any controls, check and
record their positions. If any position appears unusual, consider the possibility of inappropriate use or of incipient device failure.
Examine all controls and switches for physical
condition, secure mounting, and correct motion. If a control has fixed-limit stops, check
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Nd:YAG Surgical Lasers
for proper alignment, as well as positive stopping. Check membrane switches for tape residue and for membrane damage (e.g., from
fingernails, pens, surgical instruments). If
you find such evidence, notify users to avoid
using tape and sharp instruments. During the
inspection, be sure that each control and
switch works properly.
Remote. Examine the exterior of the control for
cleanliness and general physical condition.
Be sure that housings are intact, that assembly hardware is present and tight, and that
there are no signs of spilled liquids or other
serious abuse. If the remote control is attached by cable to the laser, ensure that the
cable and any connectors are in good condition. Examine all controls and switches for
general physical condition, secure mounting,
correct motion, and intended range of settings. Where a control should operate against
fixed-limit stops, check for proper alignment,
as well as positive stopping. During the inspection, be sure to check that each control
and switch performs properly.
Footswitch. Examine the footswitch for general
physical condition, including evidence of
spilled liquids. Footswitches for lasers include an internal switch that activates according to the depth of pedal depression. It is
usually possible to feel the vibration caused
by closure of the switch, even through a shoe.
Check that the internal switch is operating
and that the footswitch does not stick in the
On position. Some footswitches include two
internal switches; in this case, verify the operation of both. Some footswitches also include a switch to operate the liquid- or
gas-cooling system. Check to be sure that this
switch operates reliably.
1.15 Motors/Pumps/Fans/Compressors. Check the
physical condition and proper operation of these
components, if present. If lubrication is required,
note this in the preventive maintenance section
of the inspection form. Clean any obvious dust
from these components.
1.16 Fluid Levels. Check all fluid (e.g., coolant) levels.
Refill or change the fluid according to the manufacturer’s recommendations, and note this in the
preventive maintenance section of the inspection
form. If an external water supply is in use, ensure
that the water pressure is properly regulated and
at the appropriate pressure and that the supply
and drain system is properly configured (e.g.,
filters are oriented for proper flow, drain hoses
are positioned in a sink or drain).
1.17 Battery. If a remote control or display is battery
powered, check or replace the battery (periodic
prophylactic battery replacement is often preferred to risking battery failure during use).
Other batteries, such as those used to provide
additional power for 110 VAC Nd:YAG lasers,
should be inspected according to the manufacturer’s recommendations. When it is necessary
to replace a battery, label it with the date.
1.18 Indicators/Displays. During the course of the inspection, verify proper operation of all lights, indicators, meters, gauges, and visual displays on the
unit and remote control. Ensure that all segments
of a digital display function. Note any error messages displayed during the power-on self-test.
If primary and remote-control indicators and
displays can be used at the same time or if
control can be switched from one to the other
during a procedure, operate the laser in a way
that will verify that the same information (e.g.,
settings, displays) is indicated on both controls.
During the procedure, check to be sure that
the laser activates and deactivates consistently
when the footswitch is depressed and that the
fiber-coolant system operates properly when
the fiber-coolant switch is activated and deactivated. Flex the cable at the entry to the switch,
and, using an ohmmeter, check for internal wire
breaks that cause intermittent operation. Confirm that strain reliefs are secure.
If display screens or digital displays are provided for user prompts or for viewing accumulated information (e.g., pulse or accumulated
energy counter), ensure that each display provides the information expected. Ensure that user
prompts occur in the proper sequence. Store
some sample information, and verify that it is
correct. If a feature to manually reset this information is available, ensure that it works.
Examine the male and female connectors for
attaching the footswitch to the laser cabinet to
be sure that no pins are bent and that no other
damage is present. Ensure that the connector
secures acceptably to the laser cabinet.
1.19 Laser Delivery System Calibration. Nd:YAG surgical lasers typically include a user-accessible calibration port leading to an internal power meter that
allows output calibration and testing of the laser
fiber. This feature is provided because transmis-
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
5
Inspection and Preventive Maintenance System
sion of laser energy through a fiber can change
in response to fiber use. Based on the measurement from the calibration power meter, the laser
may automatically recalibrate itself and/or adjust displays so that the power indicated to be
delivered to the patient will be correct; or it may
require the user to do this manually. Verify that
this feature is functioning by using the manufacturer’s recommended calibration procedure to
test one delivery system (e.g., fiber, handpiece)
that the manufacturer indicates can be acceptably calibrated using these procedures. (Contact
tips cannot be calibrated using the laser’s calibration power meter.)
1.20 Alarms/Interlocks. Operate the device in a manner that will activate the self-check feature, if
present, and verify that all visual and audible
alarms activate according to the manufacturer’s
documentation. If no self-check feature is present,
operate the laser in a manner that will activate
each audible and visual alarm; be sure to test only
those alarms that will not cause damage to the
laser or present an unnecessary risk of laser beam
exposure to yourself or bystanders.
If a door or window interlock is used, ensure
that it properly deactivates the laser. (Do not
disassemble major parts of the laser to test internal interlocks.) After deactivating the laser
and reclosing the door or window, check to be
sure that the laser will restart. Be sure to check
the interlocks in all locations where the laser is
used. (For some lasers, the function of the interlocks can be checked using an ohmmeter.)
If the laser is equipped with an emergency
“kill” switch, test this feature to be sure that it
deactivates the laser and that the laser will
subsequently restart.
1.21 Audible Signals. Operate the device to activate
any audible signals (e.g., laser emission, setting
change). Check for proper operation, and verify
that the signal can be heard in the environment
in which the laser will be used.
1.22 Labeling. Check that all placards, labels, and
instruction cards noted during acceptance testing
(see Item 4.3) are present and legible. Check to
see that an instruction manual is kept with the
laser or is readily available.
1.23 Accessories.
General. Verify that all necessary accessories
are available and in good physical condition.
6
Set up reusable accessories with the laser to
ensure compatibility and proper functioning.
Checking all fibers or accessories during a
single inspection and preventive maintenance procedure is unnecessary as long as
accessories are routinely checked by the person(s) responsible for laser setup and operation. In addition, many of the accessories are
sterile and would require resterilization before use, making the laser potentially unavailable. Be sure to check with the person
responsible for scheduling the use of the laser
before beginning the procedure.
Fibers. For the test fiber and before each use,
examine the aperture connector, cable, and
tip of each fiber to be used, as well as the fiber
support, for cleanliness and general physical
condition. Be sure that all hardware (e.g.,
laser gas tubing channels) is present, in good
condition, and firmly attached. Ensure that
the aperture connector properly seats into the
laser aperture of the laser cabinet. Examine
the distal end of fibers to ensure that any
connecting mechanisms (e.g., threads) are in
proper working order.
If a fiber appears to be dirty or damaged,
remove it from service. If a fiber is reusable,
notify the person(s) responsible for fiber repair. The fiber should be repaired and/or
cleaned according to the manufacturer’s recommendations. Verify fiber performance.
Contact tips. Examine each tip that may be used
with the laser fibers for cleanliness and general physical condition. Be sure that the
mechanism to connect a tip to a fiber is in
proper working order and forms a secure connection. If a tip appears to be dirty or damaged, remove it from service and notify the
person(s) responsible for tip repair or replacement. Some tips may look dirty after a single
use, but remain acceptable for use; if you are
unsure about the need to clean or repair a tip,
consult with the person(s) responsible for tip
repair or replacement and with the manufacturer, if necessary.
Handpieces. Examine each handpiece component
(e.g., body, tips, lenses) for cleanliness and general physical condition. Examine individually
only those components that are intended for
removal during normal use and storage. (Do
not remove other parts that are press-fit or
attached by screws, bolts, or snap-rings.) If
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Nd:YAG Surgical Lasers
brightness of the aiming beam. Similarly, check
pulsing controls to verify that the aiming beam
can be pulsed. If several color choices are available for the aiming beam, verify that each color
is present and working properly.
lenses are detachable, be sure not to touch the
lens surface; handle lenses by the edges only.
Consult the manufacturer’s recommendations for the procedures and cleaning agents
to use to clean lenses.
Ensure that major subcomponents of the
handpiece, when assembled, are secure. Ensure that the mechanisms used to connect the
handpiece(s) to the fiber are in good working
order and that they reliably secure each handpiece to the fiber.
Microscope micromanipulator. Examine the microscope micromanipulator for cleanliness
and general physical condition. Be sure to
handle it by the main body; do not hold it by
the joystick, and do not touch the reflecting
lenses in the body. Inspect micromanipulators
provided by both the laser manufacturer and
the laser accessory manufacturer.
Ensure that the reflecting surfaces and
lenses are intact and clean. Consult the
manufacturer’s recommendations for the procedures and cleaning agents to use to clean
reflecting surfaces and lenses.
1.25 Laser Aperture.
WARNING: Make this inspection with the laser powered off. Remove and inspect the protective window (e.g., blast shield) behind the laser
aperture. It should be clean and undamaged;
clean or replace if needed. There should be no
visible dirt or residue in the optical path of the
laser aperture.
1.26 Gas Regulators. Examine any gas regulators for
cleanliness and general physical condition. Ensure that the gauges on the regulators are not
broken. During the procedure, ensure that the
regulator and the gauge operate as expected.
Verify that the correct gas is attached to each
regulator. Be sure that a key or wrench to facilitate changing the gas supply is with the unit or
readily available.
If the laser includes a gas recirculation system,
ensure proper operation by allowing it to control
the gas supply into and out of a sealed plastic bag.
Examine the joystick to ensure that it is
firmly attached and that it freely moves the
reflecting lens. If a finger rest is present, ensure
that it is firmly attached and properly oriented.
WARNING: Do not use an anesthesia or other
similar bag that may have a mold-release agent
(e.g., starch, talc) on its inside surface because the
agent could contaminate the gas recirculation
system of the laser and ultimately contaminate a
patient wound during a subsequent procedure.
If a zoom focus feature is present, be sure
that it turns easily and does not slip. Examine
each objective lens to ensure that it is intact
and clean. Do not touch the lens surface. Consult the manufacturer’s recommendations for
the procedures and cleaning agents to use to
clean the objective lenses. Carefully insert
each lens into the micromanipulator, and ensure that it fits snugly.
Inspect the mechanism used to attach the
micromanipulator to the microscope to ensure
that all parts are present and that it is in good
working order. Connect the micromanipulator to
the microscope to check for a secure connection.
Safety filters. Verify operation of safety filters in
microscope and endoscope delivery systems.
1.24 Aiming Beam. Activate the aiming beam (without the therapeutic beam), and verify that it
produces a round, uniformly bright spot, with no
halo. For handpieces that provide adjustable
spot sizes, verify that the spot size changes as
expected and still remains uniform. Check that
the intensity control, if present, does change the
If proper operation is questionable, consider
using a calibrated flowmeter to measure actual
gas flow.
2. Quantitative tests
WARNING: In general, do not use liquid fiber cooling
for tests unless specifically described in the item. Use of
this kind of cooling rather than gas fiber cooling may
damage test equipment or cause erroneous test results.
2.1
Grounding Resistance. Use an ohmmeter, electrical safety analyzer, or multimeter with good
resolution of fractional ohms to measure and
record the resistance between the grounding pin
on the power cord and exposed (unpainted and
not anodized) metal on the chassis, accessory
outlet, ground pins, and footswitch. We recommend a maximum of 0.5 Ω. (If the footswitch is
of low voltage, grounding is not required.)
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
7
Inspection and Preventive Maintenance System
2.2
Pulse feature operates as expected by moving the
target material slightly between each pulse. Be
extremely careful to keep hands out of the laser
beam path. If the number or duration between
repeat pulses is adjustable, test that setting
changes made throughout the range result in the
expected performance.
Leakage Current.
WARNING: Do not reverse power conductors
for this or any other test. Improper attachment
of conductors may damage the laser.
With the laser attached to a grounded powerdistribution system, measure the leakage current between the chassis and ground with the
unit grounded and ungrounded. The leakage
current on the chassis should not exceed 300 µA;
in no case should it exceed 500 µA. Where it is
greater than 300 µA, ensure that appropriate
grounding is present.
2.3
Exposure Duration. Some laser power meters
can measure pulse duration. If the power meter
can react to pulse duration (this is the preferred
circumstance), test the laser at each setting.
However, if the laser power meter does not measure pulse duration, use the following less preferable alternative.
Place and secure the laser fiber, handpiece, or
micromanipulator with the aiming system focused on the target material (e.g., black Delrin
or a tongue depressor). With the laser set to
about 10 W and the exposure set at minimum
duration, activate the laser and create a burn.
Carefully move the target material to expose a
clean area, maintaining the same distance. Adjust the exposure setting in increments of 0.1 sec
or the next longest duration, and activate the
laser at each setting. Continue this process until
you have tested all exposure settings, except
continuous, and have developed a series of
burns. Compare the burns to verify that progressively larger burns occurred as the exposure
duration increased.
2.4
Repeat Pulse. If the unit includes a Repeat Pulse
feature, which repeats the pulse at a fixed or
adjustable rate, test this feature with the laser
set at the minimum, median, and maximum
Repeat Pulse settings, if adjustable. Some laser
power meters can react quickly enough to be
used to test this feature of the laser. If you are
using such a power meter, test the laser to be
sure that the correct power is repeatedly delivered over the correct time period.
If your laser power meter cannot be used for
this test, use this alternative test method. Set
the laser to about 10 W and a 0.1 sec exposure
duration with the fiber, handpiece, or micromanipulator attached, and verify that the Repeat
8
2.5
Footswitch Exposure Control. Set the output
time for about 5 sec, activate the unit, and release
the footswitch after about 1 sec. Verify that the
beam turns off when the footswitch is released.
2.10 Power Output. Select one delivery system (e.g.,
fiber, handpiece, micromanipulator), and perform the manufacturer’s recommended user calibration procedure. Secure the delivery system at
the distance from the laser power meter to meet
spot-size requirements specified in the instructions for the meter. (Do not focus the beam to a
small spot on the power meter. Some power
meters require that the unfocused or a defocused
laser beam be projected into the power meter to
cover the majority of the absorber surface. If the
laser beam is focused on the receiver of such
meters, the meter may be damaged.)
WARNING: Accessing the unfocused laser
beam may require defeating internal interlocks.
Because of the heightened risk associated with an
unfocused, nondiverging laser beam, exercise
great care if the interlocks are to be defeated.
With the laser set at low (e.g., 10% of full scale),
medium (e.g., 50% of full scale), and maximum
output, activate the laser for a sufficient period to
acquire acceptable readings. (Power meters use
different time constants to acquire an acceptable
reading, and you must know and meticulously
follow them.) Compare the reading with the power
display of the laser; the measured and displayed
values should all be within 10% of one another. In
addition, compare the reading obtained with the
reading taken on incoming acceptance testing, at
the last preventive maintenance procedure, or after the last service procedure. If the laser includes
a low-power (e.g., mW) feature, test it in a similar
fashion with a power meter of appropriate resolution in the low-power range.
3. Preventive maintenance
Verify that all daily preventive maintenance procedures recommended by the manufacturer are carried out.
3.1
Clean the exterior. Clean cooling system fibers
and accessible optical components (e.g., blast
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Nd:YAG Surgical Lasers
shield, microscope lenses), if necessary, using
techniques and cleaning solutions recommended
by the manufacturer.
3.2
Lubricate any motor, pump, fan, compressor, or
printer components as recommended by the
manufacturer.
3.3
Calibrate/adjust any components (e.g., printer)
according to manufacturer recommendations.
Only appropriately trained personnel should attempt laser adjustments. Ensure that all hoses
and tubes are tight.
3.4
4.4
Electrical Wiring Configuration. Ensure that
the branch circuits and the outlets for the laser
are properly wired and rated for use with the
laser. Examine the receptacles at each location
where the laser is to be used to ensure that the
proper electrical configuration (e.g., proper neutral and ground connections, proper phase rotation) has been installed. Connect the laser to
each receptacle and confirm that the laser operates properly, specifically confirming that motors are operating in the proper direction.
4.5
AC Plug. Verify that the plug is acceptable for
use with the maximum current and voltage
specifications for operating the laser. (Consult
National Electrical Manufacturers Association
[NEMA] configurations for general-purpose nonlocking and locking connectors if in doubt.)
4.6
Pulse Duration. Verify that progressive increases in pulse duration throughout its range of
adjustment result in progressively larger burns.
4.7
Repeat Pulse. If the unit includes a Repeat Pulse
feature, test this feature as described in Item 2.4,
but over the full range of available settings.
4.8
Power Range. Using the technique described in
Item 2.10, test the power output accuracy at
several low, medium, and high settings.
4.9
Laser Delivery System Calibration. Use the manufacturer’s recommended calibration procedure to
test each new reusable delivery system (e.g., fiber,
handpiece) that the manufacturer indicates can be
acceptably calibrated using these procedures.
(Contact tips cannot be calibrated using the laser’s
calibration power meter.) Note the fiber transmission for each delivery system tested if this information is provided by the laser. Or, you can
calculate it using the following formula:
Replace filters if needed. Check all fluid levels
and supplement or replace fluids if needed.
4. Acceptance tests
Conduct major inspection tests for this procedure
and the appropriate tests in the General Devices Procedure/Checklist 438.
WARNING: Lasers may be damaged by switching
between normal and reverse polarity while the device is
on. If reverse-polarity leakage current measurements
are made, turn off the unit being tested before switching
polarity. Also, lasers powered by three-phase electrical
systems may be damaged if proper electrical phase
connections are not made initially and maintained
thereafter. Thus, do not switch conductor connections
or wiring configurations for any tests, including leakage current measurement. Do not conduct electrical
leakage current tests with reversed-polarity wiring.
Also test the ability of the laser to deliver laser
energy as expected in all configurations and with all
provided laser accessories. In addition, perform the
following tests.
4.1
4.2
4.3
Areas of Use. Visit the area(s) in which the laser
is to be used and ensure that laser signs, eyewear,
and window coverings are available and being
used and that safety interlocks for doors or windows, if present, are functioning properly.
% Transmission =
Delivered power
× 100%
Power entering the fiber
Casters/Mounts/Holders. Ensure that the assembly is stable and that the unit will not tip over
when pushed or when a caster is jammed on an
obstacle (e.g., a line cord threshold), as may occur
during transport. If the device is designed to rest
on a shelf, ensure that it has nonslip legs or
supports.
Before returning to use
Labeling. Examine the unit and note the presence, location, and content of all labels. Labeling
information is typically found in the laser’s operator manual.
Be sure to return controls to their starting position,
and place a Caution tag in a prominent position so that
the next user will be careful to verify control settings,
setup, and function before using the unit.
Delivery systems with less than the manufacturer-recommended transmission (typically
80%) should be discarded if they are disposable,
or repaired if they are reusable and intended for
repair.
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
9
Procedure/Checklist 444-0595
Oxygen-Air Proportioners
Used For:
Oxygen-Air Proportioners [12-876]
Also Called: Oxygen blenders, oxygen controllers, oxygen-air mixers
Commonly Used In: Critical care units, NICUs; occasionally used in operating rooms and most other patient
care areas
Scope: Applies to external oxygen-air proportioners; can be adapted for proportioners that are built into
ventilators
Risk Level: ECRI Recommended, Medium; Hospital Assessment,
Type
ECRI-Recommended
Interval
Major
12 months
months
.
hours
Minor
NA
months
.
hours
Overview
Oxygen-air proportioners are designed to mix compressed air and oxygen to user-selectable oxygen concentrations varying from 21% to 100% at high- or
low-output flows. Their mixed-gas output is often
passed through a humidifier or a nebulizer and delivered to patients through ventilators, tracheostomy
tubes, endotracheal tubes, oxygen tents, oxygen hoods,
or masks at flows ranging from 1 to more than 100
L/min. Oxygen-mixing devices are built into ventilators or supplied as stand-alone units. This procedure
covers the stand-alone units but can be adapted for
other units.
Oxygen-air proportioners operate by receiving air
and oxygen from central gas pipelines in the hospital
or from other compressed-gas sources, such as tanks
or portable air compressors. Ideally, the two input gas
sources are regulated at equal pressures (usually 50
psi). However, because this is often not the case,
proportioners have their own pressure-regulating
mechanisms to match input supply pressures or adjust
022999
444-0595
A NONPROFIT AGENCY
Interval Used
By Hospital
Time Required
them to preset levels at or below inlet supply levels.
At these matched or preset pressures, air and oxygen
enter a mixing valve that regulates their proportions
as they flow out of the unit.
When input pressures drop too low or differ greatly,
proportioners cannot deliver accurate concentrations.
For this reason, proportioners have built-in reed
alarms that sound when there are large pressure differentials at the gas inlets or when there are low inlet
or outlet pressures.
The most common problems related to these units
involve the contamination of oxygen or air sources due
to backflow of the other gas and the delivery of inaccurate oxygen concentrations. These problems are most
often caused by buildup of moisture or particulates
inside the units from the compressed-gas lines. Along
with regular preventive maintenance schedules, hospitals can maintain accuracy and reliability by installing water-trap filters at the gas inlets and using gas
filtration and drying systems at compressed-gas
sources.
5200 Butler Pike, Plymouth Meeting, PA 19462-1298, USA
Telephone +1 (610) 825-6000 ● Fax +1 (610) 834-1275
●
E-mail [email protected]
Inspection and Preventive Maintenance System
Citations from Health Devices
Oxygen-air proportioners [Evaluation], 1985 Jul;
14:263-76.
Using a double flowmeter assembly in lieu of an oxygen
blender [User Experience NetworkTM], 1985 Nov;
14:401.
Inaccurate O2 concentrations from oxygen-air proportioners [User Experience NetworkTM], 1989 Oct;
18:366.
Test apparatus and supplies
Although this procedure can be performed using
only the common tools and materials listed below,
some manufacturers sell special service kits for their
units. This procedure, as well as service and repair,
may be facilitated by these kits; consult your service
manual to determine if a kit is available. See Figure 1
for a typical test setup.
High-flow flowmeters with a range of 0 to 100 L/min
(accurate to within 10% of reading)
Flowmeters with ranges of approximately 0 to
50 mL/min and 1 to 15 L/min with 10% accuracy
Hoses and adapters for connecting pressure gauges
and flowmeters to equipment being inspected
Cylinders of oxygen and air with pressure gauges
that can be regulated between 0 and 100 psi; cylinder pressures should be at least 1,000 psi
Nondisposable corrugated breathing hose (disposable tubing may be used only if it provides reliable
connections)
Oxygen analyzer with at least ±3% accuracy and
with a “T” adapter for sensor head
Flow-control valve
Teflon tape
Cleaning solvent recommended by the manufacturer
Lubricant specified by the manufacturer
Special precautions
Figure 1. Typical test setup
the equipment, the significance of each control and
indicator, and the alarm capabilities. Also, determine
if any special inspection or preventive maintenance
procedures are recommended by the manufacturer.
1. Qualitative tests
1.1
Chassis/Housing. Examine the exterior of the
unit for cleanliness and general physical condition. Be sure that plastic housings are intact,
that all connectors are present and tight, and
that there are no signs of spilled liquids or other
serious abuse.
1.2
Mount/Fasteners. If the device is mounted on a
stand or cart, examine the condition of the
mount. If it is attached to a wall or rests on a
shelf, check the security of this attachment.
All testing should be done with pressure gauges and
flowmeters specified for oxygen or medical gas use
only. Turn off all pressurized gas sources when they
are no longer in use.
Procedure
Before beginning an inspection, carefully read this
procedure and the manufacturer’s instruction and service manuals; be sure that you understand how to operate
2
Inspection and Preventive Maintenance System
©1995 ECRI. All Rights Reserved.
Oxygen-Air Proportioners
1.8
Tubes/Hoses. Check the condition of all tubing
and hoses. Be sure that they are not cracked,
kinked, or dirty and that they do not leak.
2. Quantitative tests
2.3
Maximum Flow Rate. Using a high-flow flowmeter, measure the maximum flow rate out of
the proportioner. If the proportioner has two
outlets, measure the flow from its high-flow outlet. Unless designed specifically to deliver low
flows (e.g., below 15 L/min), the proportioner
should be able to deliver at least 80 L/min from
its high-flow outlet when the concentration is set
at 60%. Also, measure the maximum flow rate
when the concentration is set to 21% and 100%.
The flows at these concentration settings should
not differ by more than 10 L/min. Flow differences greater than 10 L/min indicate a restriction at one of the inlets and probably the need to
replace an inlet filter.
2.4
Alarms. Adjust input pressures to the proportioner’s specified alarm conditions. Verify that
the alarms can be heard clearly and that the unit
delivers accurate concentrations before the
alarm sounds.
2.5
Flow with Loss of an Input Source. Turn off one
of the input supplies and verify that the unit
continues to alarm and deliver adequate flows
at all concentration settings. With the loss of an
input source, the proportioner should be able to
deliver at least 30 L/min from its high-flow
output and 15 L/min from its low-flow output.
Note that not all proportioners have the same
alarm conditions; check the manufacturer
alarm specifications.
2.