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BeneVision N Series Patient Monitor Operator’s Manual 11 - 23

11.8.9 Adjusting ST Measurement Points

11.8.9.1 About ST Point, ISO Point, and J Point

The ST deviation value for each beat is the potential difference between the isoelectric (ISO) point and the ST

point. The ISO point provides the baseline. The ST point is at the midpoint of the ST segment. The J point is the

end of the QRS complex. As the J point is a fixed distance away from the ST point, it can be useful to help you

correctly position the ST point.

11.8.9.2 Setting ST Point, ISO Point, and J Point

CAUTION

• You need to adjust the ST points before starting monitoring, or if the patient's heart rate or ECG

morphology changes significantly, as this may affect the size of the QT interval and thus the

placement of the ST point. Artifactual ST segment depression or elevation may occur if the

isoelectric point or the ST point is incorrectly set.

• Always make sure that the positions of ST points are appropriate for your patient.

To set ST point, ISO point, and J point, follow this procedure:

1. Select the ST numeric area, ECG numeric area, or ECG waveform area to enter the ECG menu.

2. Select the ST tab→ select the Adjust tab.

3. Set ST Point.

The setting of Auto Adjust defines the method of adjusting the ISO point and J point. Auto Adjust is enabled by

default. In this case, positions of ISO point and J point are automatically adjusted accordingly. If you disable

when Auto Adjust, you need to manually adjust the position of ISO point and J point by selecting the arrows at

the right sides of ISO and J.

■ The ISO point (isoelectric) position is given relative to the R-wave peak. Position the ISO point in the middle

of the flattest part of the baseline (between the P and Q waves).

■ The J point position is given relative to the R-wave peak and helps locating the ST point. Position the J point

at the end of the QRS complex and the beginning of the ST segment.

■ The ST point is positioned a fixed distance from the J point. Move the J point to position the ST point at the

midpoint of the ST segment. 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.

(1 ) IS O po i n t ( 2) J p o i n t (3 ) ST p o i n t ( 4 ) ST d e v i at i o n

(1) (2) (3) (4)

Mindray BeneVision N Series User Manual

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