Phenylephrine Added to Prophylactic Ephedrine Infusion during Spinal Anesthesia for Elective Cesarean Section: A Randomized double-blind study

Abstract

Background: Prophylactic intravenous Ephedrine has been recommended to prevent hypotension after spinal anesthesia during cesarean delivery. However Ephedrine infusion does not adequately prevent hypotension. We investigated adding Phenylephrine would improve its efficacy without adverse events.

Objective: To compare the efficacy of Phenylephrine added to Ephedrine alone in preventing hypotension after spinal anesthesia during elective cesarean delivery, supplement Ephedrine and adverse events

Materials and Methods: A randomized controlled trial study. Sixty parturients with American Society of Anesthesiologists physical status I-II who were scheduled for cesarean delivery at Sawanpracharak Hospital between June 2023 and August 2023. All parturients received an isotonic crystalloid preload of 15 ml/kg. Spinal anesthesia was performed using hyperbaric bupivacaine 10 mg and morphine 0.2 mg. These patients were split into two groups: A vasopressor infusion was started immediately after spinal injection of 10 mcg/min phenylephrine and 2 mg/min Ephedrine (PE group) or 2 mg/min Ephedrine alone (E group). The infusion rate was adjusted according to systolic blood pressure using a predefined algorithm. Hypotension, defined as systolic blood pressure less than 100 mmHg and less than 80% of baseline, was treated with 6 mg Ephedrine bolus doses.

Results: The incidences of overall hypotension were not significantly different between two groups. There were 5 cases with repeated hypotension in E group but none in PE group (p-value=0.056). Supplement Ephedrine in PE group was less than E group : 6 mg versus 9.4+/-3.2 (p-value=0.03). Bradycardia and hypertension were not observed.

Conclusion: Phenylephrine 10 mcg/min added to an infusion of Ephedrine 2 mg/min tended to improve the efficacy in prevention of repeated hypotension compared with Ephedrine 2 mg/min alone and also diminished supplement Ephedrine in spinal anesthesia for elective cesarean section without adverse events.