Comparative study of Prophylactic Intravenous Granisetron vs Ondansetron for Reducing Hypotensive episodes during Spinal Anaesthesia for Lower Abdominal Surgeries: A Randomised Concurrent Parallel study

Abstract

Background: Post-spinal hypotension is a frequent complication of spinal anaesthesia, requiring effective management to maintain hemodynamic stability. Ondansetron and granisetron, commonly used as antiemetics, have been explored for their potential to mitigate spinal-induced hypotension.

Objectives: To compare the efficacy of prophylactic intravenous granisetron versus ondansetron in reducing the incidence of hypotensive episodes during spinal anaesthesia for lower abdominal surgeries.

Methods: This was a hospital based, single centre, double blinded, randomised controlled, concurrent, parallel study conducted in the Department of Anaesthesiology, Aarupadai Veedu Medical College and Hospital, Puducherry, India between July 2023 and June 2025.

Results: A total of 186 patients having lower abdominal surgery under spinal anaesthesia were randomly assigned into two groups: Group O (Ondansetron, 4 mg) and Group G (Granisetron, 2 mg), with 93 patients each. Baseline characteristics, including age, gender, height, weight, ASA grading, and surgical duration, were comparable between groups (P > 0.05). Group O exhibited a significantly faster onset of sensory blockade (P = 0.034) and a prolonged duration before sensory regression to T8 (P < 0.001). Hemodynamic parameters showed no significant differences in systolic blood pressure (SBP) at any time point (P > 0.05). Diastolic blood pressure (DBP) was significantly lower in Group G at 20 and 25 minutes (P = 0.032, P = 0.001, respectively). Mean arterial pressure (MAP) was consistently higher in Group G from 2 minutes onward (P < 0.05), while heart rate was significantly lower in Group G from 15 to 30 minutes (P < 0.05). No patients experienced intraoperative or postoperative nausea and vomiting. Ephedrine use was significantly higher in Group O, with 16.1% requiring intervention compared to 7.5% in Group G (P = 0.039), and the mean dose was also significantly higher (P = 0.006). No patients required atropine or metoclopramide.

Conclusion: These findings suggest that while both drugs effectively prevent nausea and vomiting, Granisetron is associated with greater hemodynamic stability and a lower requirement for ephedrine.