MULTISENSOR DOPPLER SYSTEM FOR MONITORING FETAL BEHAVIOR

Purpose: The purpose of our work was to develop a portable Doppler system able to monitor different fetal rhythms (cardiac, respiratory, rest/activity), and to follow their changes during external or maternal stimulation as well as in pathological conditions. One of the final objective is to use this system both in clinics and for tele medicine.

Methods and Materials: We developed a new pulsed Doppler system connected to 12 separated captors which can be fixed on the maternal abdomen through a supple probe holder. Each captor detects Doppler signals in 5 different depths positioned between 2 and 15 cms. The backscattered signals from fetal structures are characterized by their amplitude, phase and Doppler frequency shift.

Results: It was possible to record fetal rhythms and activity over periods varying from 20min up to several hours (samples of pre-selected duration). The first results obtained in pregnancies of 20 to 30 weeks are very encouraging. New software has been developed for automatic calculation of heart rate and respiratory rate and for characterizing fetal movements in terms of amplitude, duration, and velocity.

Conclusions: The multigate multi transducer system which has been developed (called Actifoetus) gives several simultaneous information concerning fetal activity and fetal behavior. It will serve as a new mean for studying fetal response to its environment and also for detecting anomalies related to fetal suffering. After validation,its applications in clinics could be extended to telemedicine for at home surveillance of at risk pregnancies