Intravenous Ondansetron versus Granisetron for Prevention of Spinal Anaesthesia-induced Haemodynamic Changes in Elderly Patients Undergoing Infraumbilical Surgeries: A Randomised Double-blind Controlled Trial

Introduction: Spinal anaesthesia is the most preferred anaesthetic approach for infra-umbilical surgical procedures. Despite its advantages, spinal anaesthesia has important side effects, including hypotension and bradycardia, particularly in elderly patients, which need to be prevented and treated if they occurs. Aim: To compare the efficacy of intravenous ondansetron and granisetron in preventing spinal anaesthesia-induced hypotension and bradycardia in elderly patients undergoing elective infraumbilical surgeries. Materials and Methods: This randomised, double-blind, controlled study was conducted in the Department of Anaesthesiology, Guru Gobind Singh Medical College and Hospital, Faridkot, Punjab, India, over a period of 18 months from October 2021 - March 2023. It included a total of 120 patients, aged 50-70 years, American Society of Anaesthesiologists (ASA) physical status I or II, planned for elective infraumbilical surgeries. They were divided randomly into three groupsGroup O: injected with 4 mg of Ondansetron diluted upto 10 mL normal saline i.v.; group G: injected with 1 mg granisetron diluted upto 10 mL normal saline i.v. and group N was injected with 10 mL normal saline i.v. every 5 min for 30 min, then every 10 min before giving spinal anaesthesia. HypotensionBradycardia Events (HBEs), Heart Rate (HR) and blood pressure were recorded every five minutes till end of surgery. The total consumption of vasopressors, atropine and adverse effects if any were recorded. Statistical analysis was performed using One-way Analysis of Variance (ANOVA), Chi-square/Fisher’s exact test, with p<0.05 considered statistically significant. Results: Demographic characteristics were comparable among the three groups (p>0.05). It was observed that in group O, 25% of patients; in group G, 45% and in group N, 67.5% of patients had HBEs (p=0.001). Although the incidence was numerically lower in group O than in group G, the pairwise difference for HBE incidence was not statistically significant on Bonferroniadjusted post-hoc analysis. Also, group O demonstrated better preservation of Systolic Blood Pressure (SBP), Diastolic Blood Pressure (DBP) and Mean Arterial Pressure (MAP) than groups G and N (p<0.05). The ephedrine requirement was lowest in the ondansetron group with (10.20±4.05) mg as compared to (16.33±7.36) mg in the granisetron group, and (15.11±6.73) mg in the normal saline group. HR remained more stable in group O throughout the intraoperative period. Conclusion: Intravenous ondansetron 4 mg administered before spinal anaesthesia provided better overall haemodynamic stability and demonstrated reduced incidence of Hypotension and Bradycardia Events (HBE) and reduced vasopressor requirement.