Mindray BeneVision N1 User Manual

BeneVision N1 Patient Monitor Operator’s Manual 7 - 19
■ The ST point is positioned a fixed distance from the J point. Position the ST point relative to the J point at
J+60/80ms, J+40ms, J+60ms or J+80ms. When J+60/80ms is selected, the ST point will be positioned 80
ms (heart rate 120 bpm or less) or 60 ms (heart rate more than 120 bpm) from the J point.
7.8 QT/QTc Interval Monitoring
The QT interval is the time between the beginning of the Q-wave and the end of the T-wave. It represents the
total duration of the depolarization (QRS duration) and repolarization (ST-T) phases of the ventricles. QT interval
monitoring can assist in the detection of long QT syndrome.
The QT interval has an inverse relationship to heart rate. Faster heart rates shorten QT interval and slower heart
rates prolong QT interval. Therefore, several formulas are commonly used to correct the QT interval for heart
rate. The heart rate corrected QT interval is abbreviated as QTc.
QT/QTc interval monitoring is intended for adult, pediatric, and neonatal patients.
7.8.1 QT/QTc Monitoring Limitations
Some conditions may make it difficult to achieve reliable QT/QTc monitoring, for example:
■ R-wave amplitudes are too low
■ The presence of frequent ventricular ectopic beats
■ RR intervals are unstable
■ P-waves tending to encroach on the end of the previous T-wave at high heart rates
■ The T-wave is very flat or T-wave are not well defined
■ The end of the T-wave is difficult to delineate because of the presence of U-waves
■ QTc measurements are not stable
■ In the presence of noise, asystole, ventricular fibrillation, atrial fibrillation, or ECG lead off
For reliable QT/QTc monitoring, choose lead with good T-wave amplitude and no visible flutter activity, and
without a predominant U-wave or P-wave.
Some conditions such as left or right bundle branch block or ventricular hypertrophy can lead to a widened QRS
complex. If a long QTc is observed you should verify it to ensure that it is not caused by QRS widening.
Because normal beats followed by ventricular beats are not included in the analysis, no QT measurement will be
generated in the presence of a bigeminy rhythm.
If the heart rate is extremely high (over 150 bpm for adults and over 180 bpm for pediatrics and neonates), QT
will not be measured. When the heart rate changes, it can take several minutes for the QT interval to stabilize. For
reliable QTc calculation it is important to avoid measurements when the heart rate is changing.
7.8.2 Enabling QT/QTc Monitoring
The QT monitoring function is disabled by default. Before you start QT monitoring, enable the QT function. To do
so, follow this procedure:
1. Select the ECG numeric area or waveform area to enter the
ECG dialog.
2. Select the
QT tab→ select the Setup tab.
3. Switch on
QT Analysis.
7.8.3 Displaying QT Numerics and Segments
To display QT numerics and Segments, follow this procedure:
1. Access
Tile Layout by either of the following ways:
◆ Select the Screen Setup quick key → select the Tile Layout tab.
◆ Select Main Menu quick key → from the Display column select Tile Layout.
2. Click the parameter numeric area where you want to display the QT numerics, and then select
ECG → QT/
QTc
.

Mindray BeneVision N1 Specifications

General

Brand	Mindray
Model	BeneVision N1
Category	Medical Equipment
Language	English