Comparison of prophylactic angiotensin II versus ephedrine infusion for prevention of maternal hypotension during spinal anesthesia.

OBJECTIVE: Our purpose was to study the efficacy of ephedrine versus angiotensin II prophylactic infusions to counter maternal hypotension that occurs during spinal anesthesia at cesarean delivery.

STUDY DESIGN: Healthy pregnant women undergoing elective repeat cesarean delivery at term with spinal anesthesia were randomized either to a control group (n = 10) or to one of two prophylactic infusion groups: angiotensin II (n = 10) or ephedrine (n = 10). Prophylactic infusions were titrated to a maternal diastolic blood pressure 0 to 10 mm Hg above baseline. Maternal and fetal blood samples for angiotensin II levels and acid-base status were obtained. Student's t test, chi 2, and analysis of variance were used.

RESULTS: Mean arterial pressures were maintained after spinal anesthesia in the ephedrine and angiotensin II groups but decreased (p < 0.05) in the control group. Maternal angiotensin II levels rose with angiotensin II infusions but were unaltered in the other groups. Umbilical artery and vein angiotensin II levels were unaltered by angiotensin II infusions. Mean umbilical artery blood pH was lower (p < 0.05) in the ephedrine group than in the angiotensin II and control groups.

CONCLUSIONS: In the healthy term fetus there is an advantage in using angiotensin II to maintain maternal blood pressure during regional anesthesia.