Huntleigh Sonicaid FM800 Series, Инструкция по эксплуатации, Страница: 42 / 130

Sonicaid FM800 Encore Series Instructions for Use
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The FHR confidence indicator
The heart symbol which appears against the FHR display is a confidence indicator, not an
indicator of signal strength.
If the heart symbol is displayed in outline only, and no FHR is displayed, the FM800E
cannot detect the fetal heartbeat.
If the heart symbol is displayed in the form of a ‘beating’ heart alternate small and large
filled heart, and the FHR is displayed, the FM800E can detect a fetal heartbeat. The
colour gives a confidence indication, where –
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Yellow is low confidence
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Orange is moderate confidence
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Red is high confidence
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False recording of FHR
When monitoring FHR using Doppler ultrasound, the heart
rate may be falsely reported. This can be caused by a
number of effects including double-rating or half rating, and
is characteristic of ultrasound fetal monitoring. Another
cause may be detection of maternal signals, (particularly in
the absence of fetal signals). Doubling of the maternal rate
can result in a trace looking very like a normal fetal trace.
If the fetal heart signal has large variations in rate, is weak, or is in the presence of large
maternal signals, noise or artefact, it is possible for the system to double count or half rate
for short periods of time. This is characteristic of monitoring fetal heart rates with
ultrasound.
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How to minimise the chances of double rating, half rating or other types
of artefact occurring
Always palpate the abdomen and listen to the fetal heart
with a Pinard stethoscope or hand-held Doppler unit before
applying the ultrasound transducers. This helps to verify
the fetal heart and to locate the area where best signal
quality can be expected.
1 Palpate the maternal pulse for one minute simultaneously and record it on the printed
output. Check that the maternal rate is different from the displayed fetal rate.
2 Recording a signal for maternal ECG/MSpO
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will help to identify any cross-correlation
between maternal and fetal heart rates.