Effect of Ondansetron in Prevention of Hypotension in Elective Lower segment Cesarean Section under Spinal Anesthesia: A Randomized, Double-Blind Study

ABSTRACT

Background: Spinal anesthesia is the preferred modality of anesthesia for lower segment cesarean section, but it is complicatedwith hypotension and bradycardia, which may be harmful to both parturient and baby. Bezold–Jarisch reflex plays an importantrole through 5HT3 receptors located in intracardiac vagal nerve endings in causing hypotension and bradycardia. In this study, weevaluated the effect of ondansetron, as a 5HT3 receptor antagonist, on the hemodynamic response following spinal anesthesiain parturients undergoing elective lower segment cesarean section.Methodology: Sixty parturients who were scheduled for lower segment elective cesarean section were randomly allocated intotwo groups. Before giving the spinal injection, Group O (n = 30) received intravenous ondansetron 4 mg and Group S (n = 30)received normal saline. Blood pressure, heart rate, and vasopressor requirements were assessed.Results: Total dose of vasopressor (mephentermine) used in Group “O” was 78 mg (mean±SD = 2.60 ± 4.36) and in Group “S,”it was 168 mg (mean ± SD = 5.6 ± 4.43 (P = 0.010). In Group O, the incidence of hypotension was 9 out of 30 patients whilein Group S, 21 out of 30 patients developed hypotension at any point of surgery (χ2=9.6 and P = 0.002).Conclusion: Ondansetron 4 mg, given intravenously 5 min before spinal anesthesia, causes reduction in hypotension andvasopressor use in parturients undergoing elective lower segment cesarean section.