Comparison of Prophylactic Phenylephrine Infusion Versus Intravenous Ondansetron on Hypotension During Spinal Anesthesia for Cesarean Section.

Background: Multiple methods have been proposed to prevent the incidence of hypotension in women undergoing cesarean section under spinal anesthesia. This study was conducted to compare the efficacy of phenylephrine (50 μg.min^-1) versus ondansetron (8 mg) in the prevention of such complications.

Patients and methods: We included a total of 184 full-term pregnant women who were randomly divided into two groups: Group P included 92 cases who were commenced on phenylephrine infusion (50 μg.min^-1 given after puncture) and Group O included the other 92 cases who were administered ondansetron (8 mg given 5 min before puncture).

Results: Demographic data were not significantly different between the two groups. Maternal hypotension was significantly more encountered in the ondansetron group (51.6% vs. 22%) and ephedrine was used more significantly in that group (19.8% vs. 8.8%). In addition, nausea and skin flushing were more commonly encountered in the same group. The incidence of vomiting and patient discomfort was not significantly different between the two study groups.

Conclusion: Phenylephrine is markedly superior to ondansetron in the prevention of maternal hypotension and vasopressor need during cesarean section under spinal anesthesia.