11 Monitoring Twin FHRs
117
When Trace Separation is On
When trace separation is turned on, the recorder prints a dotted line labeled with the two FHRs at the
top, and at the bottom.
Examples of the two methods (Standard, Classic) for determining the trace separation order are
provided here.
"Standard" Separation Order
To make differentiating the traces easier, the trace from the ultrasound transducer connected to the
FHR2 channel is separated from that of FHR1 by 20 bpm. In other words, the trace for FHR2 is
recorded 20 bpm higher than it really is. The trace for FHR1 is never shifted.
• The recorder prints a dotted line labeled across the FHR scale, to identify the trace for FHR2.
• The FHR trace is labeled every 5cm.
• The label for FHR2 is annotated with .
The following trace shows trace separation switched on.
Only the FHR2 trace is offset. The numerical FHR value displayed on the monitor remains
unchanged. Subtract 20 from the recorded trace for FHR2 to obtain the true FHR2 value. For
example, if the recorded trace shows 160, then the true FHR is 140.
"Classic" Separation Order
To make differentiating the traces easier, the trace from the ultrasound transducer connected to the
FHR1 channel is separated from that of FHR2 by 20 bpm. In other words, the trace for FHR1 is
recorded 20 bpm higher than it really is. The trace for FHR2 is never shifted.
• The recorder prints a dotted line labeled across the FHR scale, to identify the trace for FHR1.
• The FHR trace is labeled every 5cm.
• The label for FHR1 is annotated with .
The following trace shows trace separation switched on.
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