Huntleigh SonicaidTeam, Operator'S Manual, Page: 70 / 113

Sonicaid Team Operator’s Manual
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6.7 Plotting trend data
Pre-printed Trend Graph forms are available in packs of 50, part number 8902-8002.
These enable you to produce a plot manually of the key values given in the analysis
report. With other clinical information, these graphs may allow a trend of fetal
health to be discerned.
The forms allow plotting of:
z
Moves per hour
z
Short-term variation
z
Basal heart rate
z
Declarative trace (mark a ‘D’ on the graph to indicate this)
This is normally done after four or more records are taken in a 28-day period.
6.8 Analysis parameters and calculations
The baseline
The analysis uses pulse intervals averaged over 1/16 minute to fit a baseline to the
fetal heart rate trace. Accelerations and decelerations are measured from this base-
line.
The baseline follows slow, but not rapid, changes in the fetal heart rate. It is re-fitted
at every analysis, as further information becomes available.
Basal heart rate
The basal heart rate is the mean rate averaged over all periods of low variation. If no
low variation is present, it is derived from a statistical analysis.
The basal heart rate should be between 116–160 bpm. A basal heart rate of 160–170
bpm is not sinister antepartum provided that the mean range of the fetal heart rate
variation is within normal limits and there are no large decelerations. A basal heart
rate greater than 170 bpm suggests the possibility of fetal infection.