Epidural anesthesia in the normotensive pregnant ewe: Effects on uterine blood flow and fetal acid-base status.

Abstract

Lumbar epidural anesthesia was administered to 12 normotensive pregnant ewes. Blood pressure was maintained by intravenous fluid infusion. Six ewes received anesthesia with 1.5 per cent 2-chloroprocaine with 1:100,000 epinephrine and the remaining six received 1.5 per cent 2-chloroprocaine without epinephrine. The sensory level of anesthesia was between the umbilicus and xiphisternum. Except for a transient 14 per cent decrease in uterine blood flow in the ewes receiving 2-chloroprocaine with epinephrine, uterine blood flow remained near control values and was sufficient at all times to maintain stable fetal acid-base and blood gas values. Provided blood pressure and uterine blood flow were stable, the percentage of uterine blood flow distributed to the placenta in the absence of uterine contractions was not altered by epidural anesthesia or by addition of epinephrine to the anesthetic solution.