Question

What is delay time to establish a missing foetal trigger pulse by substitution logic?

(a) 150 ms

(b) 200 ms

(c) 250 ms

(d) 270 ms

The question was posed to me during an interview for a job.

This interesting question is from Ambulatory Monitoring Instruments topic in portion Arrhythmia and Ambulatory Monitoring Instruments of Biomedical Instrumentation

Answer 1

The correct choice is (d) 270 ms

The explanation: The substitution logic requires a delay time to establish a missing foetal trigger pulse. On the one hand, this delay has to be longer than the maximum permissible change in heart period (14 bpm change from 50–64 bpm = 262 ms) and on the other hand, it has to be shorter than the shortest period duration (216 bpm = 285.7 ms). It is thus kept as 270 ms.