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7.11.3 Resetting Care Group Alarms
You can reset the alarm of the currently viewed bed in the View Other Patient window. To enable this function:
Setup>>].
2. In the [Alarm Setup] menu, set [Reset Other Bed’s Alarms] to [On].
When your monitor is viewed by other monitors and [Alarm Reset By Other Bed] is switched on, alarms on your monitor can be reset by other monitors.
WARNING
Resetting care group alarms may cause a potential hazard.
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FOR YOUR NOTES
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8
Monitoring ECG
8.1 Introduction
The electrocardiogram (ECG) measures the electrical activity of the heart and displays it on the monitor as a waveform and a numeric. ECG monitoring provides the following algorithms:
Advanced ECG algorithm
The Advanced ECG algorithm provides 3-, 5- and 12-lead ECG monitoring, ST-segment analysis, and extended arrhythmia analysis.
Mortara ECG algorithm
The Mortara ECG algorithm provides 3-, 5- and 12-lead ECG monitoring, ST-segment analysis, and arrhythmia analysis.
Glasgow algorithm
Glasgow algorithm provides an interpretation of the resting 12-lead ECG.
You can select algorithms at the time of purchase or as upgrades post sale:
The equipment incorporating the Advanced ECG algorithm is labeled with a ST/ARR label.
The equipment incorporating the Mortara ECG algorithm is labeled with the Mortara logo.
The equipment incorporating the Glasgow algorithm is labeled with the Glasgow logo.
8.2 Safety
WARNING
This equipment is not intended for direct cardiac application.
Use only ECG electrodes and cables specified by Mindray.
Make sure the conductive parts of electrodes and associated connectors for applied parts, including the neutral electrode, should not contact any other conductive parts including earth.
Periodically inspect the electrode application site to ensure skin quality. If the skin quality changes, replace the electrodes or change the application site.
Use defibrillation-proof ECG cables during defibrillation.
Do not touch the patient or metal devices connected to the patient during defibrillation.
To reduce the hazard of burns during high-frequency surgical procedure, ensure that the monitor’s cables and transducers never come into contact with the electrosurgery unit (ESU).
The neutral electrode of the HF surgical unit shall properly contact the patient. Otherwise, burns may result.
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CAUTION
Interference from a non-grounded instrument near the patient and electrosurgery interference can cause problems with the waveform.
NOTE
After defibrillation, the screen display recovers within 10 seconds if the correct electrodes are used and applied in accordance with the instructions for use.
8.3 Preparing to Monitor ECG
8.3.1 Preparing the Patient and Placing the Electrodes
To prepare the patient and place the electrodes:
1. Prepare the patient’s skin. Proper skin preparation is necessary for good signal quality at the electrode site, as the skin is a poor conductor of electricity. To properly prepare the skin, choose flat areas and then follow this procedure:
Shave hair from skin at chosen sites.
Gently rub skin surface at sites to remove dead skin cells.
Thoroughly cleanse the site with a mild soap and water solution. We do not recommend using ether or pure alcohol, because this dries the skin and increases the resistance.
Dry the skin completely before applying the electrodes.
2. Attach the clips or snaps to the electrodes before placing them.
3. Place the electrodes on the patient.
4. Attach the electrode cable to the patient cable and then plug the patient cable into the ECG connector.
8.3.2 Choosing AHA or IEC Lead Placement
To choose AHA or IEC lead placement:
1. Select the ECG parameter window or waveform area to enter the [ECG Setup] menu. electrodes.
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8.3.3 ECG Lead Placements
The electrode placement illustrations in this chapter adopt the AHA standard.
3-Leadwire Electrode Placement
Following is an electrode configuration when using 3 leadwires:
RA placement: directly below the clavicle and near the right shoulder.
LA placement: directly below the clavicle and near the left shoulder.
LL placement: on the left lower abdomen.
5-Leadwire Electrode Placement
Following is an electrode configuration when using 5 leadwires:
RA placement: directly below the clavicle and near the right shoulder.
LA placement: directly below the clavicle and near the left shoulder.
RL placement: on the right lower abdomen.
LL placement: on the left lower abdomen.
V placement: on the chest.
The chest (V) electrode can be placed on one of the following positions:
V1 placement: on the fourth intercostal space at the right sternal border.
V2 placement: on the fourth intercostal space at the left sternal border.
V3 placement: midway between the V2 and V4 electrode positions.
V4 placement: on the fifth intercostal space at the left midclavicular line.
V5 placement: on the left anterior axillary line, horizontal with the V4 electrode position.
V6 placement: on the left midaxillary line, horizontal with the V4 electrode position.
V3R-V6R placement: on the right side of the chest in positions corresponding to those on the left.
VE placement: over the xiphoid process.
V7 placement: on posterior chest at the left posterior axillary line in the fifth intercostal space.
V7R placement: on posterior chest at the right posterior axillary line in the fifth intercostal space.
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12-Leadwire Electrode Placement
12-lead ECG uses 10 electrodes, which are placed on the patient’s four limbs and chest. The limb electrodes should be placed on the soft skin and the chest electrodes placed according to the physician’s preference.
Lead Placement for Surgical Patients
The surgical site should be taken into consideration when placing electrodes on a surgical patient. e.g. for open-chest surgery, the chest electrodes can be placed on the lateral chest or back. To reduce artifacts and interference from electrosurgical units, you can place the limb electrodes close to the shoulders and lower abdomen and the chest electrodes on the left side of the mid-chest.
Do not place the electrodes on the upper arm. Otherwise, the ECG waveform will be very small.
WARNING
When using electrosurgical units (ESU), patient leads should be placed in a position that is equal distance from the electrosurgery electrotome and the grounding plate to avoid burns to the patient. Never entangle the ESU cable and the ECG cable together.
When using electrosurgical units (ESU), never place ECG electrodes near to the grounding plate of the ESU, as this can cause a lot of interference on the ECG signal.
8.3.4 Checking Paced Status
It is important to set the paced status correctly when you start monitoring ECG. The paced symbol is displayed when the [Paced] is set to [Yes]. The pace pulse markers “|” are shown on the ECG wave when the patient has a paced signal. If [Paced] is set to [No] or the patient’s paced status is not selected, the symbol will be shown in the patient information area.
To change the paced status, you can select either:
the patient information area, or
[Main Menu]→[Patient Setup]→[Patient Demographics], or,
the ECG parameter window or waveform area→[Others >>], and then, select [Paced] from the pop-up menu and then select [Yes] or [No].
If you do not set the paced status, the monitor issues a prompt tone when pace pulse is detected. At the same time, the paced symbol flashes and the message [Please confirm the pace of patient] appears in the ECG waveform area. Then, please check and set the paced status of the patient.
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WARNING
For paced patients, you must set [Paced] to [Yes]. If it is incorrectly set to [No], the monitor could mistake a pace pulse for a QRS and fail to alarm when the ECG signal is too weak.
On ventricular paced patients, episodes of Ventricular Tachycardia may not always be detected.
False low heart rate indicators or false Asystole calls may result with certain pacemakers because of pacemaker artifact such as electrical overshoot of the pacemaker overlapping the true QRS complexes.
Do not rely entirely upon the system’s automated arrhythmia detection algorithm. Keep pacemaker patients under close surveillance.
For non-paced patients, you must set [Paced] to [No].
The auto pacer recognition function is not applicable to pediatric and neonatal patients.
8.4 Understanding the ECG Display
Your display may be configured to look slightly different.
1 2 3 4
1. Lead label of the displayed wave
3. ECG filter label
4. Notch filter status
Additionally, when a paced signal has been detected, the pace pulse marks “|” are shown on the ECG wave if the [Paced] setting has been configured to [Yes].
2
3
1
1. Current heart rate alarm limits
2. Heart beat symbol
3. Current heart rate
For 12-lead ECG display screen, refer to section 8.10 12-Lead ECG Monitoring.
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8.5 Changing ECG Settings
8.5.1 Accessing ECG Menus
By selecting the ECG parameter window or waveform area, you can access the [ECG Setup] menu.
8.5.2 Setting Pacemaker Rate (For Mortara ECG Algorithm only)
Some pacemaker pulses can be difficult to reject. When this happens, the pulses are counted as a QRS complex and could result in an incorrect HR and failure to detect some arrhythmias. You can set [Pacemaker Rate] to the pacemaker’s rate in the [ECG Setup] menu. In this way, the monitor can calculate HR and detect arrhythmias more accurately. When
[Paced] is set to [No], the pacemaker rate cannot be set.
8.5.3 Choosing the Alarm Source
In most cases the HR and PR numerics are identical. In order to avoid simultaneous alarms on HR and PR, the monitor uses either HR or PR as its active alarm source. To change the alarm source, select [Alm Source] in the [ECG Setup] menu and then select either:
[HR]: if you want the HR to be the alarm source for HR/PR.
[PR]: if you want the PR to be the alarm source for HR/PR.
[Auto]: If the [Alm Source] is set to [Auto], the monitor will use the heart rate from the ECG measurements as the alarm source whenever a valid heart rate is available. If the heart rate becomes unavailable, for example the ECG module is turned off or becomes disconnected, the monitor will automatically switch to PR as the alarm source.
8.5.4 Changing ECG Wave Settings
In the [ECG Setup] menu:
You can select [ECG], [ECG1], or [ECG2] to select a lead to view. The ECG lead (s) selected is used for analysis (beat detection, beat classification, and V-Fib detection). The waveform of selected lead should have the following characteristics:
The QRS should be either completely above or below the baseline and it should not be biphasic.
The QRS should be tall and narrow.
The P-waves and T-waves should be less than 0.2mV.
If the wave is too small or clipped, you can change its size by selecting an appropriate [Gain] setting. If you select
[Auto] from [Gain], the monitor will automatically adjust the size of the ECG waves. In normal screen, only the selected ECG wave can be adjusted. In other screens, all ECG waves can be adjusted simultaneously.
You can change the wave sweep speed by selecting [Sweep] and then selecting the appropriate setting.
NOTE
Changing the display gain on the monitor does not affect the amplitude of signal that is used by the algorithm for beat detection.
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8.5.5 Changing the ECG Filter Settings
The ECG filter setting defines how ECG waves are smoothed. To change the filter setting, select [Filter] from [ECG Setup] and then select the appropriate setting.
[Mon]: Use under normal measurement conditions.
[Diag]: Use when diagnostic quality is required. The unfiltered ECG wave is displayed so that changes such as
R-wave notching or discrete elevation or depression of the ST segment are visible.
[Surg]: Use when the signal is distorted by high frequency or low frequency interference. High frequency interference usually results in large amplitude spikes making the ECG signal look irregular. Low frequency interference usually leads to wandering or rough baseline. In the operating room, the surgery filter reduces artifacts and interference from electrosurgical units. Under normal measurement conditions, selecting [Surgery] may suppress the QRS complexes too much and then interfere with ECG analysis.
[ST]: Use when ST monitoring is applied.
CAUTION
The [Diagnostic] filter is recommended when monitoring a patient in an environment with slight interference only.
8.5.6 Setting the ECG Lead Set
You can set the [Lead Set] by selecting [ECG Setup]
→[Others >>]. You can set the [Lead Set] as [Auto] if the auto lead detection function is available.
8.5.7 Choosing an ECG Display Screen
When monitoring with a 5-lead or 12-lead set, you can select [Main Menu]→[Screens], or [Others>>]→[ECG Display] in the [ECG Setup] menu to choose the screen type as:
[Normal]: The ECG waveform area shows 2 ECG waveforms.
[Full-Screen]: The whole waveform area shows 7 ECG waveforms only.
[12-Lead]: The whole waveform ares displays 12 ECG waveforms (for 12-lead set only).
When monitoring with a 3-lead set, the screen type can only be set to [Normal].
When the screen type is set to [Normal], cascaded ECG waveforms can be displayed.
To cascade ECG waveforms:
1. Select the [Main Menu]→[Screens]→[Screen Setup].
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8.5.8 Setting the Notch Filter
The notch filter removes the line frequency interference. Only when [Filter] is set to [Diagnostic], the [Notch Filter] is adjustable.
To set the notch filter:
1. Select the ECG parameter window or waveform area to enter its setup menu. Then select [Others >>].
[Strong]: when waveform interference is strong (such as spikes).
[Weak]: when waveform interference is weak.
[Off]: to turn the notch filter off.
Set notch frequency according to the electric power frequency of your country. To set notch filter frequency: required password.
8.5.9 Changing the Pacer Reject Settings
To change the pacer reject settings, select [ECG Setup]→[Others>>]→[Pacer Reject], and then select [On] or [Off].
When [Paced] is set to [Yes]:
When [Pacer Reject] is switched on, the pace pulses are not counted as extra QRS complexes.
The pace pulse marks “|” are shown on the ECG wave when pace pulses are detected.
When [Paced] is set to [No], the pace markers are not shown on the ECG wave, and the options of [Pacer Reject] are inactivated.
8.5.10 Enabling Smart Lead Off
When the smart lead off function is enabled and there is a “lead off” in the lead of the first ECG wave, if another lead is available, the monitor will automatically select the available lead. The system will re-calculate HR and analyze and detect arrhythmia. When the “lead off” condition is corrected, the leads are automatically switched back.
To switch on/off the smart lead off function, select [Others >>] from the [ECG Setup] menu; select [Smart Lead Off] and then select [On] or [Off] from the pop-up menu.
8.5.11 Setting the Alarm Level for ECG Lead Off Alarms
Select [Alarm Setup >>] from the [User Maintenance] menu. You can set [ECGLeadOff Lev.] from the pop-up menu.
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8.5.12 Adjusting QRS Volume
QRS sounds are produced based on the alarm source.
To adjust the QRS volume,
When a valid SpO
2
measured value is available, the system adjusts the pitch tone of QRS sound based on the SpO
2
value.
8.5.13 Adjusting the Minimum QRS Detection Threshold (For Advanced ECG Algorithm
Only)
To avoid false asystole alarms when the R wave amplitude is low and missed asystole alarms during ventricular standstill
(tall P waves, but no QRS), a means to manually adjust the minimum QRS detection threshold is provided.
To adjust the QRS threshold,
1. In the [ECG Setup] menu, set [Filter] to [Monitor].
2. Select [Others >>]→[Minimum QRS Threshold >>] to enter the [Minimum QRS Threshold] menu.
3. Select the up or down arrow to adjust the QRS threshold. Selecting [Default] resets the QRS threshold to the default value (0.16 mV).
CAUTION
The setting of QRS threshold can affect the sensitivity of arrhythmia, ST, QT/QTc detection, and heart rate calculation.
If QRS amplitude is low, the monitor might not be able to calculate heart rate and false asystole may occur.
NOTE
The minimum QRS detection threshold can only be adjusted when the ECG filter is set to [Monitor].
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8.5.14 About the Defibrillator Synchronization
A synchronization pulse (100 ms, +5 V) is output through the multifunctional connector each time the monitor detects an R-wave.
To use the defibrillator synchronization function, connect the monitor and the defibrillator with a synchronization cable.
WARNING
Improper use of a defibrillator may cause injury to the patient. The user should determine whether to perform defibrillation or not according to the patient’s condition.
8.6 About ST Monitoring
Mortara ST segment analysis is not intended for neonatal patients.
ST segment analysis calculates ST segment elevations and depressions for individual leads and then displays them as numerics in the ST1 and ST2 areas.
A positive value indicates ST segment elevation; a negative value indicates ST segment depression.
Measurement unit of the ST segment deviation: mV or mm. You can set the unit in the [Unit Setup] menu from the
[User Maintenance] menu.
Measurement range of the ST segment deviation: -2.0 mV to +2.0 mV.
WARNING
The ST algorithm has been tested for accuracy of the ST segment data. The significance of the ST segment changes need to be determined by a clinician.
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8.6.1 Switching ST Monitoring On and Off
To switch ST monitoring on or off:
1. In the [ECG Setup] menu, select [ST Analysis >>].
Reliable ST monitoring cannot be ensured if:
You are unable to get a lead that is not noisy.
Arrhythmias such as atrial fib/flutter cause irregular baseline.
The patient is continuously ventricularly paced.
The patient has left bundle branch block.
In these cases, you may consider switching ST monitoring off.
8.6.2 Changing ST Filter Settings
ST-segment analysis can be carried out only when the filter mode is set to [Diagnostic] or [ST]. When ST-segment analysis is switched on, [Filter] will automatically switch to [ST] if it is not [Diagnostic] or [ST]. When ST-segment analysis is switched off, the filter mode automatically switches to previous manual setting.
However, if you switch [Filter] to [Monitor] or [Surgery], ST-segment analysis will turn off automatically. If you change
[Monitor] or [Surgery] to [Diagnostic] or [ST], ST-segment analysis remains off, you can turn it on manually.
8.6.3 Understanding the ST Display
8.6.3.1 ST Numerics
This example shows ST numerics with 5-lead ECG. Your monitor screen may look slightly different from the illustration.
8.6.3.2 ST Segment
ST segment shows a QRS segment for each measured ST lead. The current ST segment is drawn in the same color as the
ECG wave, usually green, superimposed over the stored reference segment, drawn in a different color. The information is updated once every ten seconds.
To display the ST segment on normal screen:
1. Enter the [ST Analysis] menu. Set [ST Analysis] to [On].
2. Enter the [Screen Setup] window from the [Screens] menu. Set [ST Segment] to be displayed.
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