[Refinement of a new Doppler sensor for studying fetal hemodynamic disorders (animal model)]

Fetal Doppler techniques applied in the human have furnished information of the regional haemodynamics of fetal circulation but has in general been associated with haemodynamic data obtained by vessel puncture, i.e. arterial pressure or blood gases. With animal models, further data can be obtained in the course of induced pathologies or during dynamic test (hypoxia, drugs). Several studies on utero-placental haemodynamics have been conducted using electromagnetic sensors and implanted catheters. This type of technique is only possible for certain vessels (usually the cord vessels) and, for example, cannot be used to investigate the cerebral area. The aim of this work was to develop a Doppler sensor which could be implanted in utero on the fetus and would permit a real time measurement of the major fetal blood flows. The sensor was made of 2 continuous Doppler transducers (13 mm x 4 mm) with a 45 degrees inclinasion to the sensor surface and carried on a parallellopipedic support system measuring 20 mm x 6 mm. The active surface of the transducer has a silicone film covering. The sensor is placed on the skin of the fetus, facing the artery to be explored, and oriented towards capture of a quality signal. The sensor is then sutured to the skin and the coaxial leads of the 2 transducers are exposed through the skin of a pregnant ewe. The leads are connected to a Doppler control panel later after the operative period. Three sensors can be implanted simultaneously to monitor umbilical, cerebral and uterine blood flows.(ABSTRACT TRUNCATED AT 250 WORDS)