Ephedrine Versus Ondansetron in the Prevention of Hypotension During Cesarean Section: A Randomized, Double-Blind, Placebo-Controlled Trial

Background: Common side effects of spinal anesthesia for cesarean section (C.S.) include hypotension and bradycardia. Ondansetron, a ۵HT۳ receptor antagonist, has been suggested for prophylactic prevention of spinal induced hypotension (SIH) in elective cesarean section. This study compared a traditional vasopressor "ephedrine" with two doses of ۵-HT۳ receptor antagonist "ondansetron" to prevent SIH during cesarean section. Materials and Methods: A total of ۱۶۸ full‑term parturients undergoing C.S. under spinal anesthesia were included. Patients were divided randomly into four groups (ephedrine, ۴ mg ondansetron (O۴), ۸ mg ondansetron (O۸), and control group). All patients were monitored for mean blood pressure, heart rate, vasopressor requirement, and side effects. The primary outcome of this study was the incidence of SIH in all four groups during the first ۶۰ minutes after spinal anesthesia. Results: The incidence of SIH was significantly higher in the control group (۴۵.۲%) compared to the ephedrine, O۴, and O۸ groups (۱۹%, ۱۶.۷%, and ۱۱.۹%, respectively). There were significant differences between the four groups regarding maternal mean arterial pressures during the ۱st ۶۰ minutes after spinal anesthesia. No side effects were recorded. Conclusion: Prophylactic intravenous ondansetron (at a dose of ۴mg or ۸mg) could be an effective/non-inferior alternative to ephedrine in reducing the incidence of SIH and the requirement of vasopressors in parturients undergoing C.S.

Keywords:

Bezold‑Jarisch reflex , Cesarean section , Ephedrine , Ondansetron , Spinal induced hypotension