A comparison of three vasopressors for tight control of maternal blood pressure during cesarean section under spinal anesthesia: Effect on maternal and fetal outcome

PURPOSE: Maintaining systolic blood pressure (SBP) at 100% of baseline is best for fetal and maternal outcome. We hypothesized that irrespective of the vasopressor used, maintaining SBP at 100% of baseline with phenylephrine (P), metaraminol (M), or ephedrine (E) will produce the best fetal pH after cesarean section (LSCS) under subarachnoid block (SAB). MATERIALS AND METHODS: Ninety ASA 1 women scheduled for elective LSCS were randomly allocated to receive P, M, or E. SAB was established with patient in left lateral position using 2.5 cc of 0.5% hyperbaric bupivacaine. Immediately following SAB, patients received a bolus of the study drug (E = 5 mg, M = 0.5 mg, P = 30 mcg) followed by infusion (E = 2.5 mg/min, M = 0.25 mg/min, P = 15 mcg/min) to maintain SBP at 100% baseline. Umbilical blood gases, maternal hemodynamic parameters, and complications were recorded. RESULTS: The umbilical pH was comparable in all the three groups (P > 0.05). The mean SBP from spinal block until delivery was similar over time for all the three groups. The incidence of reactive hypertension was more in group M (P < 0.05) than in group E and group P. Total drug consumption to meet target blood pressure till delivery was 39.3 ± 14.6 mg in group E, 1.7 ± 0.9 mg in group M, and 283.6 ± 99.8 mcg in group P. The incidence of nausea and vomiting was comparable in the three groups. CONCLUSION: All the three vasopressors were equally effective in maintaining maternal blood pressure as well as umbilical pH during spinal anesthesia for cesarean section without any detrimental effects on fetal and maternal outcome.