13 Monitoring Triple FHRs
really is, while the trace for FHR3 is recorded 20 bpm lower than it really is. The trace for FHR2 is
The following trace shows triplets with
The traces for FHR1 and FHR3 are offset. The numerical FHR values displayed on the monitor
remain unchanged. Subtract 20 from the recorded trace for FHR1 to obtain the true FHR1. For
example, if the recorded trace shows 160 bpm, then the true FHR is 140 bpm. Similarly, add 20 to the
recorded trace for FHR3 to obtain the true FHR3.
Switching Trace Separation On and Off
Connect three ultrasound transducers to the monitor to measure FHR.
See "Switching Trace Separation On and Off " on page 162 for details of how to switch trace
separation on or off.
The recorder prints a dotted line labeled +20 across the FHR scale, to identify the
trace for FHR1.
The recorder prints a dotted line labeled -20 across the FHR scale, to identify the
trace for FHR3.
The FHR trace is labeled every 5 cm.
The label for FHR1 is annotated with +20 and the FHR3 label is annotated with
on, and using