12 Monitoring Triple FHRs
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for FM40/50.
• The trace recorded for the FHR3 is thicker (darker) than that recorded for FHR1, which is thicker
than that for FHR2. This ensures that the three heart rates are easily distinguishable. The thickness
of the recorded trace can be changed in Configuration Mode.
• Remember that only one fetal heartbeat can be heard from the loudspeaker at any time. The audio
source symbol shows you which fetus you are listening to. To hear the another fetal
heartbeat, select the fetal heart rate sound for this channel (see “Selecting Fetal Heart Sound” on
page 99).
• Monitor maternal pulse to avoid mistaking maternal heart rate for FHR.
• Make sure you are recording the best possible signals by referring to the signal quality indicators
and repositioning the transducers if necessary.
Monitoring Triplets
To monitor triple FHRs you need three ultrasound transducers. Follow the procedures described in
“Monitoring FHR and FMP Using Ultrasound” on page 95 and in “Monitoring Twin FHRs” on
page 113. The blue transducer Finder LED lets you identify at a glance which transducer is monitoring
which heart rate channel.
Cross-Channel Verification
If the monitored heart rates (from a fetal or maternal source) coincide at any time (that is, if the same
heart rate is being monitored by more than one transducer), this is detected via the monitor's cross-
channel verification feature, and is repeatedly printed on the trace paper after about 30 seconds. If
the suspended coincidence persists for more than one minute without interruption, then the INOP
COINCIDENCE will additionally appear on the screen. Check the trace and reposition one or more of
the transducers, if necessary, to detect all FHRs correctly.
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