PROPHYLACTIC ANGIOTENSIN-II INFUSION DURING SPINAL-ANESTHESIA FOR ELECTIVE CESAREAN DELIVERY

Background: Angiotensin II may prove useful in treating regional anest hesia-induced hypotension in obstetric patients, because it causes les s uterine vasoconstriction than do other vasoconstrictor drugs (such a s phenylephrine). This study compared (1) maternal blood pressure and heart rate and (2) fetal status at delivery in parturients given eithe r prophylactic angiotensin II or ephedrine infusion during spinal anes thesia for elective cesarean delivery. Methods: Fifty-four women were randomized to receive either angiotensin II or ephedrine infusion intr avenously during spinal anesthesia for elective cesarean section deliv ery. Simultaneous with subarachnoid injection, infusion of angiotensin II (2.5 mu g/ml) or ephedrine (5 mg/ml) was initiated at 10 ng.kg(-1) .min(-1) and 50 mu g.kg(-1).min(-1), respectively. The rate of each in fusion was adjusted to maintain maternal systolic blood pressure at 90 -100% of baseline. Results: Cumulative vasopressor doses (mean +/- SD) through 10, 20, and 30 min were 150 +/- 100, 310 +/- 180, and 500 +/- 320 ng/kg in the angiotensin group and 480 +/- 210, 660 +/- 390, and 790 +/- 640 mu g/kg in the ephedrine group. Maternal heart rate was si gnificantly higher (P < 0.001) during vasopressor infusion in the ephe drine group than in the angiotensin group, Umbilical arterial and veno us blood pH and base excess were all significantly higher (P < 0.05) i n the angiotensin group than in the ephedrine group. Conclusions: Angi otensin II infusion maintained maternal systolic blood pressure during spinal anesthesia without increasing maternal heart rate or causing f etal acidosis.