Establishment of animal model for invasive monitoring in fetus during maternal cardiopulmonary bypass

Abstract

Objective To establish animal model for invasive monitoring in fetus during maternal cardiopulmonary bypass and to evaluate fetal-maternal temperature relationship and fetal cardiovascular response during maternal cardiopulmonary bypass in preg- nant ewes. Methods The atemal cardiopulmonary bypass was established, reaching different levels of maternal hypothennia. 20 pregnant ewes were divided into 4 groups, including normothermic group, mild hypothennic group, moderate hypothennic group and control group. Hypothermic levels were maintained for 20 minutes, then the rewarming phase was started. Fetal and maternal tempera- tare, blood pressure, heart rate were evaluated at different levels of hypothermia and during recovery. Results One ewe died of ven-tricular filbrillation in moderate hypothermi group, and the other ewes and fetuses survived. Maternal temperature was always lower than fetal temperature during cooling; during rewarming the gradient was inverted. The start of cardiopulmonary bypass and cooling was associated with transient fetal tachycardia; then, both fetal heart rate and blood pressure progressively decreased. Conclusion Ma-ternal hypothennic cardiopulmonary bypass was associated with reversible modifications in fetal temperature, cardiovascular parame-ters. The application of normothermic or mild hypothennic perfusion is safe to the fetus and mother. Key words: Pregnancy; Cardiopulmonary bypass; Models; Animal