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

Background: Common side effects of spinal anesthesia for cesarean section (CS) include hypotension and bradycardia. Ondansetron, a 5HT3 receptor antagonist has been suggested for prophylactic prevention of spinal?induced hypotension (SIH) in elective cesarean section. Objective: This study was conducted to compare a traditional vasopressor ?ephedrine? with two different doses of 5-HT3 receptor antagonist ?ondansetron? in preventing SIH during cesarean section. Patients: A total of 168 full?term parturients undergoing CS under spinal anesthesia were included. Interventions: Patients were divided randomly into 4 groups (ephedrine, 4 mg ondansetron (O4), 8 mg ondansetron (O8) and control group). All patients were monitored for mean blood pressure, heart rate, vasopressor requirement, and side effects. Main outcome measure: The primary outcome of this study was the incidence of SIH in all 4 groups during the first 60 minutes after spinal anesthesia Results: The incidence of SIH was significantly higher in the control group (45,2%) when compared to ephedrine, O4, O8 groups (19%, 16.7%, 11.9% respectively). There were significant differences between the 4 groups regarding maternal mean arterial pressures during the 1st 60 minutes after spinal anesthesia. No side effects were recorded. Conclusion: Prophylactic intravenous ondansetron - at a dose of 4mg or 8mg- could be an effective alternative to ephedrine in reducing the incidence of SIH and requirement of vasopressors in parturients undergoing CS.