How do you measure the duration of a QRS complex?

The duration of a QRS complex is measured from the beginning of the Q wave (or R wave if no Q wave is present) to the end of the S wave. The measurement is taken from the baseline.

Here are the steps to measure the QRS duration:

1. Identify the beginning of the Q wave or the R wave if there is no Q wave.

2. Identify the end of the S wave.

3. Measure the distance between the beginning of the Q or R wave and the end of the S wave.

4. The measurement should be taken in milliseconds.

The normal duration of a QRS complex is between 80 and 100 milliseconds. A QRS complex that is longer than 120 milliseconds is considered to be prolonged.