[Acid-base equilibrium during acute fetal hypoxia. Experimental study].

The authors studied the effects of acute hypoxia of short duration in eight pregnant ewes that had been anaesthetised. They showed that during the experiment the E.E.G. as well as the pH and pCO and the maternal lactate levels were not changed and that therefore changes that can be found in the fetus are due solely to its own hypoxia and not due to transmission from the mother. In the fetus the trace flattens in about 30 minutes on an average. After this interval a moderate drop in pH occurs at the same time as an increase in lactacidemia and the relationship between lactate and pyruvate. The heart rate is changed in a variable manner: it accelerates if the basal rate is less than 180 beats a minute and slows if it is above 180. Blood pressure rises. Changes in the cardio-vascular system always precede those in the electroencephalograms.