Comparison of Weight-Adjusted Dose versus Fixed Dose Ondansetron in Preventing Shivering Following Spinal Anaesthesia for Caesarean Deliveries

Abstract

BACKGROUND Spinal anaesthesia is the preferred method of anaesthesia in parturients undergoing both elective and emergency lower-segment caesarean section. A common complication of spinal anaesthesia is shivering. Shivering increases perioperative heart rate and oxygen consumption by 5 times and also increases the metabolic demand by 100 times, thereby increasing chances of myocardial ischemia, hypoxia, hypoxemia and later lactic acidosis. In this study, we wanted to compare the incidence of shivering following spinal anaesthesia when a weight-adjusted dose versus a fixed dose of ondansetron is used during caesarean delivery. METHODS This was a hospital-based randomized double-blinded (patient and observer blinded) single hospital-based study conducted among 190 pregnant patients who underwent elective caesarean delivery under spinal anaesthesia in the Department of Anaesthesiology and Critical Care, Gauhati Medical College and Hospital, Guwahati from 1st August 2021 to 31st July 2022 after obtaining clearance from Institutional Ethics Committee and written informed consent from the study participants. The patients were divided into two groups: group 1 (patients who received a weight-adjusted dose of ondansetron at 0.1mg/kg) and group 2 (patients who received fixed-dose ondansetron). RESULTS Shivering occurred in 11 patients (11.6 %) in group 1 and 21 patients (22.1 %) in group 2, but there was no statistical difference between the two groups (p-value 0.053) (using the chi-square test). 10 patients (10.5 %) developed grade I shivering and 1 patient (1.1 %) developed grade II shivering in group 1. In group 2, 10 patients (10.5 %) developed grade I shivering and 11 patients (11.6 %) developed grade II shivering (P-value - 0.0163) which was statistically significant (using chi-square test). Nausea occurred in 2 patients (2.1 %) in group 2 while no incidence of nausea was seen in group 1. Incidence of headache was seen in both groups; 1 patient (1.1 %). There was no statistical difference between the adverse effects of the groups. CONCLUSIONS The severity of shivering was lower in the weight-adjusted dose at 0.1 mg/kg ondansetron group in patients undergoing spinal anaesthesia for caesarean delivery. The incidence of shivering was comparable in both the weight-adjusted dose and fixed-dose ondansetron groups. The incidence of nausea, vomiting, headache and pruritus did not differ significantly among the groups.