S10/S12/S10A/S12A Patient Monitor User’s Manual
8-25
8.8.1. QT/QTc measurement limitation
The following conditions may affect the accuracy of QT measurement:
The amplitude of R wave is too low.
Excessive ventricular heartbeat.
RR interval is unstable.
High heart rate causes P wave to invade the end of the previous T wave.
T wave is too flat or t wave boundary is unclear.
The existence of U wave makes the end of T wave difficult to define.
QTc measurement is unstable.
In the presence of noise, asystole, ventricular fibrillation, and ECG lead off.
In the above situation, you need to select leads with good T wave amplitude, no
visible flutter, and no dominant U wave or P wave. In some cases, such as left and right
bundle branch block or cardiac hypertrophy, QRS complex may widen. If a long QTc is
observed, this should be confirmed to ensure that it is not caused by QRS broadening.
QT measurement cannot be performed in the presence of bigeminy rhythm because
normal cardiac beats are not included in the analysis when they are followed by
ventricular beats.
QT measurement cannot be performed when the heart rate is extremely high (adults
over 150bpm, pediatric and neonatal over 180bpm). When the heart rate changes, it can
take several minutes for the QT interval to stabilize. In order to obtain reliable QTc
calculation results, it is important to avoid areas where the heart rate changes.
8.8.2. Enabling the QT/QTc Monitoring
QT/QTc monitoring function is off by default, and you need to turn it on before
performing QT/QTc monitoring. Enable QT/QTc monitoring as follows:
1. Select ECG parameter area or waveform area to enter 【ECG】 menu.
2. Select 【QT】 submenu【Setting】submenu.
3. Switch on 【QT Analysis】.
8.8.3. Displaying QT/QTc Parameter
The method for displaying QT parameters and waveforms is as follows:
1. Enter the 【Screen Layout】 page in one of the following ways:
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