Effect of ondansetron in the prevention of spinal anesthesia-induced hypotension

Abstract

Background and Aims: Hypotension and bradycardia are the common side effects seen after spinal anesthesia. Multiple strategies are tested to prevent the postspinal anesthesia-induced hypotension. Recently, Ondansetron, a 5-HT3 antagonist commonly used as an antiemetic was found to be effective in preventing spinal anesthesia-induced hypotension. The aim of this study is to evaluate the effect of ondansetron in the prevention of spinal anesthesia-induced hypotension. Materials and Methods: A prospective, randomized, and double-blind study was conducted on 110 elderly patients, aged 50–70 years, of the American Society of Anesthesiologists Grade I or II category, scheduled for various surgeries under spinal anesthesia. The patients were randomly divided into two groups of 55 each to receive either ondansetron 8 mg (Group A) or saline (Group B) before spinal anesthesia. The primary outcome of the study was the incidence of hypotension (systolic blood pressure 20% in the baseline values). Secondary outcomes, such as the requirement of ephedrine, the incidence of bradycardia, nausea, and vomiting were also recorded during the study. Results: Group A and Group B were comparable with respect to age, sex, height, and weight. Thirty-four patients in Group B (60.7%) and 22 patients in Group A developed hypotension (39.3%) (P = 0.0359) [Table 1]. The use of ephedrine was greater in Group B than that of Group A (mean 4.61 ± 1.80 vs. 3.45 ± 1.09, P = 0.0107). Thirteen patients in Group B and four patients in Group A had bradycardia (P = 0.0176). Nine patients in Group B and two patients in Group A had vomiting (P = 0.0261). Conclusion: We conclude that prophylactic administration of ondansetron is effective in reducing the incidence of spinal anesthesia-induced hypotension.