A Double Blind Randomized, Placebo Controlled Study Evaluating the Effect of Ondansetron in Reducing Spinal- Induced Hypotension Using Low Dose Bupivacaine in Parturients Undergoing Caesarean Section

Background: Spinal induced hypotension is the most common intraoperative complication after spinal anesthesia during cesarean delivery. Various adjuvant techniques/drugs had been used in the past to minimize the haemodynamic effects of spinal anaesthesia. Five-hydroxytriptamine (5-HT), a serotonergic receptor, may be an important factor associated with inducing the Bezold Jarish reflex (BJR) that may lead to the bradycardia and hypotension in the setting of decreased blood volume. Some animal and human studies further supported that BJR can be decreased by 5-HT3 antagonists. Aim: The present study work is to assess the effects of Inj. Ondansetron (a selective 5‐HT3 receptor antagonist) in preventing spinal induced hypotension in patient undergoing elective Caesarean section. Methods: Sixty parturients scheduled for elective caesarean section were randomly allocated into two groups. Group O (30 patients): Inj. Ondansetron (4 mg IV) diluted in 10 mL of normal saline, administered 5 minutes before spinal anaesthesia and Group N (30 patients): Normal saline 10 mL given 5 minutes before spinal anaesthesia. We observed the haemodynamic parameters as our primary outcome and neonatal outcome in terms of APGAR scoring as secondary outcome. Results: Both the groups were comparable in terms of demographic characteristics. The decrease in mean arterial pressure in Group O was significantly lesser than Group N from 6 min until 30 min. The requirement of vasopressor (Inj. Phenylephrine) was significantly less in Group O than Group N (P = 0.015). Neonatal outcome in terms of APGAR Score and gas analysis were comparable between the groups. Conclusion: Inj. Ondansetron (4 mg IV), given intravenously 5 min before subarachnoid block reduced hypotension and vasopressor use in parturients undergoing elective caesarean section.