Effects of Ondansetron on Attenuating Spinal Anesthesia–Induced Hypotension and Bradycardia in Obstetric and Nonobstetric Subjects: A Systematic Review and Meta-Analysis.

Hypotension and bradycardia are common adverse effects following spinal anesthesia. Ondansetron has been studied in the attenuation of spinal anesthesia– induced hypotension (SIH) and bradycardia because of its antagonistic effect on the Bezold-Jarisch reflex. The purpose of this systematic review and meta-analysis of randomized controlled trials (RCTs) was to determine the efficacy of intravenous (IV) ondansetron in reducing the incidence of SIH and bradycardia. Thirteen RCTs were included in this analysis, totaling 1,225 subjects. Hypotension and bradycardia were summarized using a risk ratio (RR) with 95% confidence interval (CI). Heterogeneity was summarized using randomeffects model for I(2) greater than 50%; otherwise, a fixed-effects model was performed. Intravenous ondansetron reduced the incidence of hypotension in both the all-procedure analysis group (RR, 0.64; CI, 0.45-0.90) and cesarean delivery group (RR, 0.63; CI, 0.45-0.88). For bradycardia, IV ondansetron resulted in reduced risk (RR, 0.31; CI, 0.19-0.50). Findings of our meta-analysis suggest that IV ondansetron may mitigate the risks of SIH and bradycardia following spinal anesthesia.