VELOCIMETRIC AND BIOCHEMICAL FETAL EFFECTS OF PLACENTAL EMBOLIZATION USING MICROSPHERES IN EWES

Objective: To investigate the reliability of our animal model and stud y the fetal response to placental ischemia. Study design: Eight monofe tal pregnant ewes were fitted with appliances in conformity with a pre viously defined operating protocol which we have developed. Microspher es at different concentrations were injected through the fetal face of the placenta. The extent of this embolisation was evaluated using bio chemical (acid-base balance) and velocimetric criteria (umbilical and carotid arteries). Results: Five fetuses received high concentrations of microspheres and developed acute fetal distress (pH = 6.8 +/- 0.05; PO2 = 6.7 +/- 0.4; (S - D)/S (U.A.) = 1.0; (S - D)/S (C.D.) = 0.58 +/ - 0.05). Three fetuses received lower concentrations of microspheres a nd developed chronic fetal distress (pH = 7.2 +/- 0.02; PO2 = 15 +/- 1 ; (S - D)/S (U.A.) = 0.75 +/- 0.09; (S - D)/S (A.C.) = 0.62 +/- 0.04). Conclusion: Our experimental model is able to reproduce acute and chr onic fetal distress. The concentration of microspheres used to create chronic distress is currently understood. Long-term fetal compensation mechanisms prevent the evaluation of risks linked to each degree of c hronic distress in utero. The subsequent aim is to obtain a correlatio n between velocimetric observations and acid-base balance data.