The effects on maternal and fetal cardiovascular and acid–base variables after the administration of etomidate in the pregnant ewe

Etomidate is an intravenous (IV) hypnotic agent characterised by its cardiovascular stability. Although etomidate has been satisfactorily used in veterinary and human obstetrics, little is known about its effects on the fetus. This study determined the cardiovascular and acid-base effects of etomidate administration in the pregnant ewe and her fetus. The effects of etomidate were evaluated in two separate studies. In the first study, etomidate was administered as a 1mg/kg IV bolus; in the second, the drug was administered as a continuous infusion of 100 microg/kg/min for 1h, preceded by a 1mg/kg IV bolus. Etomidate administration did not depress cardiovascular function in the pregnant ewe or fetus. When administered as a continuous infusion, maternal heart rate and blood pressure increased during the second half of the infusion and the initial stages of recovery. Acid-base alterations led to transient but slight respiratory depression in both mother and fetus, probably reflecting the combined effects of etomidate on respiration and the positioning of the animal.