EFFECTS OF ETHANOL ON THE CIRCULATION AND ACID-BASE-BALANCE OF PREGNANT SHEEP

Abstract

It has been demonstrated by Fuchs and associates that ethanol can suppress human uterine contractions during labor, at present ethanol is used as a drug for the treatment of premature labor. Infusions [9] of 15 cm3/kg per 120 min of 9.5% ethanol were administered to 4 chronically catheterized ewes, at 109-135 days gestation. Stabilization periods ranged from 6-28 days postoperatively. Maternal and fetal concentrations of ethanol were almost identical (r [correlation coefficient] = 0.9925), with peak levels of 122 .+-. 20 mg/100 ml (mean .+-. 1 SE) and 121 .+-. 19 mg/100 ml, respectively, at the end of infusion. Maternal pH decreased from 7.50 .+-. 0.02 to 7.44 .+-. 0.02 (P < 0.005) at 120 min. Maternal glycemia increased from 76 .+-. 14 mg/100 ml to 162 .+-. 23 mg/100 ml (P < 0.005) at 120 min. Maternal heart rate, blood pressure, PO2 [partial pressure of O2], O2 content, PCO2 [blood partial pressure of CO2] and bicarbonate remained unchanged. Fetal PO2 increased during and following infusion from 18.9 .+-. 0.9 mmHg to 22.0 .+-. 1.0 mmHg (P < 0.005) at 180 min. Fetal blood pressure increased from 51.3 .+-. 3.1 mmHg to 53.7 .+-. 3.3 mmHg (P < 0.01) at 30 min. Fetal pH, PCO2, glucose and lactate levels remained unchanged. Ethanol crosses the sheep placenta readily, causes maternal acidosis and hyperglycemia and increases fetal PO2, blood pressure and heart rate without any effects on fetal acid-base status.