5-12 170 Series Monitor Revision D
2003023-001
Fetal Heart Rate Monitoring: Fetal Heart Rate Alarms
Signal Quality Alarms
A fetal heart rate signal quality alarm occurs if the monitor is unable to detect an
acceptable FHR signal.
Active Signal Quality Alarm
Signal quality alarms are indicated both visually and audibly. The Alarm indicator
illuminates and dashes “– – –” display in the affected fetal heart rate display.
The audio alarm is described as alternating high-low tones.
Resolved Signal Quality Alarm
As soon as an alarm condition is resolved, both the visual and audible indications
automatically disappear.
100% Signal Loss
In cases where there is a complete absence of signal, the signal quality time-to-alarm
is 1.25 minutes. See
Figure 5-8.
Figure 5-8. 100% Signal Loss Example
12
3
4
5
Time (minutes)
FHR (BPM)
alarm activated
100% signal loss
1.25 min