The Hewlett Packard 8040A is an antepartum (pre-labor) fetal monitor for measuring and recording maternal and fetal activity. Data is displayed on the front panel, recorded on a strip chart recorder, and if the transmission option is installed, can be transmitted via telephone modem to a remote data receiver. The transmission option is installed on all Medical Specialties-owned units.
Uterine activity and fetal heart rate is monitored externally using a ultrasound tocotransducer strapped to the abdomen of the patient. This tocotransducer sends sound waves into the maternal abdomen and detects echoes coming from moving objects within. The monitor analyzes these echoes, picking out indications of fetal heart motion, and uses the rhythm of the motions to compute heart rate. At the same time, the toco transducer detects uterine activity by sensing changes in tension on the abdomen. An event marker is manipulated by the patient to note events of fetal activity, which is recorded on the chart.
Similar to the UXAM66 in function, the HP8040 can monitor fetal heartrate either externally, using the included ultrasonic transducer, or internally, using the ECG Direct cable input. Uterine activity is monitored by a second toco transducer, and an event marker can be used by the patient to mark contractions. All readings, including ECG, fetal heartrate, uterine activity, and events, are printed on the printer mounted on the face of the unit.
Both the fetal and maternal heartrates can be monitored at the same time by using the ultrasonic transducer for the fetal heartrate, and attaching the ECG to the mother's chest to monitor her heartrate; both will be simultaneously recorded and printed. It is also possible to monitor intrauterine pressure using the optional pressure transducer. This is often done when uterine membranes have been ruptured.
Monitoring of twins is possible by monitoring one fetus externally, using the ultrasonic transducer, and the other internally, using direct ECG. Not all versions of the HP8040A are set up to perform this kind of monitoring, so individual units must be checked to see if they have twin monitoring capability.