Effect of granisetron on the spinal anesthesia-induced hemodynamic changes: a meta-analysis of randomized controlled trials.

BACKGROUND: Spinal anesthesia induces hemodynamic disturbances such as hypotension and bradycardia. Granisetron, a 5-HT₃ receptor antagonist primarily used for antiemesis, has been proposed to mitigate these effects. METHODS: This meta-analysis of randomized controlled trials evaluated intravenous granisetron versus placebo/no treatment in adults undergoing elective surgery under spinal anesthesia, reporting hypotension (primary outcome), bradycardia, shivering, hemodynamic changes, and vasopressor use. A random-effects model was used to calculate relative risks (RR) or mean differences (MD) with 95% confidence intervals (CI), with subgroup analysis by surgical type (cesarean vs. nonobstetric). RESULTS: Fourteen trials (n = 1388) were included. Granisetron significantly reduced overall hypotension (RR = 0.51; p < 0.001), vasopressor use (RR = 0.64; p = 0.008), and shivering (RR = 0.32; p < 0.001). Bradycardia reduction was significant only in nonobstetric participants (RR = 0.48; p = 0.047), not overall (p = 0.118); similarly, mean arterial pressure (MAP) at 5 and 15 min (p = 0.001, p < 0.001) and heart rate at 5 min (p = 0.013) improved only in nonobstetric surgery, with no overall significance. Heterogeneity was substantial for most continuous outcomes (I2 > 85%). Funnel plot asymmetry suggested possible publication bias/small-study effects for hypotension and MAP at 30 min, with no major concern for other outcomes. CONCLUSIONS: Granisetron appears effective in reducing hypotension, vasopressor use, and shivering during spinal anesthesia, with early hemodynamic benefits in nonobstetric surgery. Given the heterogeneity and publication bias identified, findings warrant cautious interpretation requiring larger trials. TRIAL REGISTRATION: PROSPERO, CRD420251034777. Registered 17 April 2025, https://www.crd.york.ac.uk/prospero/.