Effect of ondansetron on hypotension and bradycardia associated with spinal anesthesia during cesarean section

Abstract

Objective The aim of the study was to evaluate the efficacy of ondansetron during spinal anesthesia for cesarean section in overcoming the associated nausea, vomiting, bradycardia, and hypotension. Background Ondansetron, a widely used antiemetic and serotonin antagonist, has been safely used to blunt the Bezold–Jarisch reflex, resulting in less bradycardia and hypotension in humans undergoing spinal anesthesia. Patients and methods One hundred parturients scheduled for elective cesarean section were randomly allocated into two groups. Before induction of spinal anesthesia group I (n = 50) received intravenous ondansetron 4 mg and group II (n = 50) received normal saline. Blood pressure, heart rate (HR), nausea and vomiting, shivering, vasopressor requirements, and Apgar score at 1 and 5 min were assessed. Results Decreases in systolic arterial pressure were significantly lower in group I than in group II. Patients in group I had significantly less requirement for vasopressor (P = 0.005), needed lower dose of vasopressor (P = 0.01), and had significantly lower incidences of nausea and vomiting (P = 0.03). Decreases in HR were significantly lower in group I than in group II just after spinal anesthesia (P = 0.02), at 20 min (P = 0.01), and 50 min (P = 0.02). Decreases in mean blood pressure were significantly lower in group I than in group II just after spinal anesthesia (P = 0.007). Conclusion In parturient women undergoing elective cesarean section, intravenous 4 mg ondansetron significantly decreased the hypotension, HR fluctuation, and vasopressor doses used.