ABSTRACT Background: Spinal anaesthesia is the preferred technique for caesarean section as it has several advantages to the parturient, but is associated with side effects like hypotension, bradycardia and shivering which could be deleterious to the parturient and the child. Along with sympathetic blockade, 5-hydroxytryptamine(5-HT) may be another important factor to produce bradycardia, hypotension and vasodilation due to Bezold-Jarisch reflex mediated by the 5-HT3 intracardiac receptors through non-myelinated vagal afferent pathways. Administration of 5-HT3 receptor antagonist could therefore be benefical. This study is aimed at investigating the effect of ondansetron , a 5-HT3 receptor antagonist administered intravenously, on the hemodynamic response in parturients undergoing caesarean section under spinal anaesthesia.

Methods: After approval of Institutional Ethical Clearance Committee, 60 pregnant women who underwent caesarean section under spinal anaesthesia at Cheluvamba Hospital attached to MMC&RI were randomly allocated into 2 groups. The study group'O'(n=30) received 4mg ondansetron intravenously and the control group'S'(n=30) received normal saline 5 minutes before administering spinal anaesthesia. Pulse rate, mean arterial pressure(MAP) and shivering were assessed along with vasopressor requirement till completion of surgery.

Results: MAP changes and requirement of vasopressors were significantly high in the control group(p=0.02). Incidence of nausea and vomiting were significantly low in study group(p=0.04)

Discussion: Results of the study concurs with similar studies done by other authors.

Conclusion: Administration of ondansetron 4mg intravenously prior to spinal anaesthesia significantly attenuates spinal induced hypotension, bradycardia and shivering in addition to its antiemetic effect in parturients undergoing caesarean section.