13 Monitoring Triple FHRs
The transducer Finder LED lets you identify at a glance which transducer is monitoring which
heart rate channel.
The fetal sensor socket to which a transducer is connected, is identified by the transducer position
indicator in the setup menu header:
The trace recorded for the
than that for
of the recorded trace can be changed in Configuration Mode.
Remember that only one fetal heartbeat can be heard from the loudspeaker at a time. The audio
source symbol shows you which fetus you are listening to. To hear the other fetal heartbeat, select
the fetal heart rate sound for this channel (see "Selecting Fetal Heart Sound" on page 146).
Monitor maternal pulse to avoid mistaking maternal heart rate for FHR.
Ensure you are recording the best possible signals by referring to the signal quality indicators and
repositioning the transducers if necessary.
For the Avalon CL transducer system see "Cableless Monitoring - Important Considerations" on
To monitor triple FHRs you need three ultrasound transducers. Follow the procedures described in
"Monitoring FHR and FMP Using Ultrasound" on page 141 and in "Monitoring Twin FHRs" on
page 159. The transducer Finder LED lets you identify at a glance which transducer is monitoring
which heart rate channel.
Separating FHR Traces
To help you to interpret traces with similar baselines, you can separate the baselines by an offset of
20 bpm by switching trace separation on. For details of the offset, see "Separation Order Type" on
"Standard" Separation Order
To make differentiating the traces easier, the trace for FHR2 is offset by +20 bpm, and the trace for
FHR3 is offset by -20 bpm. In other words, the trace for FHR2 is recorded 20 bpm higher than it
is thicker (darker) than that recorded for
. This ensures that the three heart rates are easily distinguishable. The thickness
, which is thicker