Corometrics 145 - Page 15

SECTION 4
OPERATION
FETAL HEART RATE MONITORING
EXTERNAL METHOD
Ultrasound
An ultrasound transducer placed on the maternal abdomen senses heart motion utilizing the Doppler principle. The rate is
determined using the patented autocorrelation processing to determine the time interval between successive heart beats.
Fetal Heart Rate Displays
The fetal heart rate is displayed in several ways. A heart beat indicator (amber backlit heart symbol) flashes for each detected
valid heart beat. It does not flash for event triggers which are rejected by the monitor’s editing. A three digit amber numeric
display indicates FHR in beats per minute. This display will be blanked (- - -) if a front panel FHR connector is not inserted
into the monitor. FHR trends will be plotted on the fetal channel of the strip chart. There is a few seconds delay from printing
until the tracing appears on the moving chart paper. The rear panel speaker will emit audible tones which reflect the Doppler
shift signals sensed by the monitor.
UTERINE ACTIVITY
Tocodynamometer
A tocotransducer placed on the maternal abdomen will record changes in abdominal tension. The resulting tracings will reflect
uterine contractions and fetal or maternal movement.
10 + Operation