Efficacy of Intravenous Ondansetron Versus Ephedrine as Prophylactic Against Hypotension and Bradycardia Following Spinal Anaesthesia in Elective Caesarean Section - A Comparative Study

Abstract

Background: The pathophysiological mechanism involved in the occurrence of hypotension and bradycardia following central neuroaxial blockade is peripheral vasodilatation, parasympathetic dominance and increased baroreceptor activity.Current studies correlate these haemodynamic changes with activation of a phenomenon naming Bezold-Jarisch reflex (BJR). 5-Hydroxytryptamine-3 is an important factor associated with inducing BJR and Ondansetron antagonizes the induction of BJR. Objective: To compare the efficacy between ondansetron and ephedrine as prophylactic against spinal anaesthesia induced hypotension and bradycardia. Method: 120 mothers of ASA grade I and II scheduled for elective caesarean section under spinal anaesthesia were selected and randomized into two equal groups naming Group A(n=60) and Group B (n=60). Group A received Ondansetron IV (0.1mg/kg body wt) and group B Ephedrine (0.15 mg/kg body wt) 5 minutes prior spinal anaesthesia. Data were recorded before and just after anaesthesia and at two minutes intervals up to 10th minute followed by five minutes intervals until the end of surgery. Results analyzed using unpaired t-test. A “P” value < 0.05 was considered statistically significant. Result: Group A showed slight but statistically significant higher heart rate than after Group B at 10th min and 15th min (P=0.001). Statistically significant higher values of MAP in Group A found up to the 15th minute of perioperative period. Rescue medications for hypotension were significantly higher in Ephedrine group. Shivering is common for both groups ,whereas nausea and vomiting is significantly less in group A. Conclusion: Ondansetron and Ephedrine has potential role to prevent spinal anaesthesia induced hypotension and bradycardia but Ondansetron shows better efficacy. Ondansetron also plays important role in prevention nausea and vomiting. JBSA 2016; 29(2): 67-74