Hemodynamic effects of simultaneous administration of intravenous ephedrine and spinal anesthesia for cesarean delivery.

STUDY OBJECTIVE To evaluate the hemodynamic effects of an intravenous (IV) ephedrine bolus given simultaneously with spinal anesthesia for cesarean delivery. DESIGN Randomized, prospective, double-blind study. SETTING Tertiary-care academic medical center. PATIENTS 40 ASA physical status I and II nonlaboring women undergoing elective cesarean delivery of term, uncomplicated, singleton pregnancies. INTERVENTIONS After a 10 mL/kg IV lactated Ringers bolus given over 15 minutes, patients simultaneously received an IV dose of 2 mL (10 mg) ephedrine or 2 mL saline, and an intrathecal dose of 12 mg (1.6 mL 0.75%) bupivacaine with 10 microg of fentanyl. Hypotension, defined as a 20% decrease in mean arterial pressure (MAP), was treated with 10-mg IV doses of ephedrine. MEASUREMENTS Hemodynamic (heart rate and MAP) and non-invasive thoracic impedance (cardiac index, stroke index, and systemic vascular resistance index) measurements at baseline and at 1-minute intervals until the time of delivery. Total fluid, supplemental ephedrine, and Apgar scores were recorded. Data were evaluated using analysis of variance (ANOVA), ANOVA for repeated measures, and Mann-Whitney U-tests where appropriate, with p < 0.05 considered significant. MAIN RESULTS Significant changes from baseline in MAP, systemic vascular resistance index, heart rate, and cardiac index were observed in both groups after spinal anesthesia. However, there were no differences between the ephedrine and saline groups in the incidence and severity of change from the baseline. The overall incidence of hypotension was 70% in both groups. No difference in total fluid or supplemental ephedrine use was observed. CONCLUSIONS 10 mg of IV ephedrine given at the time of spinal anesthesia, and after a 10 mL/kg lactated Ringers fluid bolus, does not diminish the incidence or severity of hypotension in parturients undergoing cesarean delivery.