Ondansetron versus Tramadol in the Prevention of Postanaesthesia Shivering following Caesarean Section Under Spinal Anaesthesia

Abstract

Background : Postanaesthesia shivering is a frequent and undesirable complication of spinal anaesthesia. Because of the increased physiological stress it places on the patient, different drugs have been used for its management. This study compared the efficacy of ondansetron versus tramadol in the prevention of postanaesthesia shivering following elective Caesarean section under spinal anaesthesia. Patients and Methods : In this prospective, double-blind controlled trial, 90 American Society of Anesthesiologist (ASA) I or II patients, with singleton pregnancies, undergoing elective Caesarean section under subarachnoid block, were randomized to receive 4mg ondansetron, 0.5mg/kg tramadol or normal saline intravenously after spinal anaesthesia. The primary outcome was the incidence of shivering. Results : The incidence of shivering was 20.0% in the ondansetron group, 16.7% in the tramadol group and 53.3% in the saline group (p = 0.003). Severe shivering occurred in eight patients in the saline group compared to one in the ondansetron group and none in the tramadol group (p = 0.007). Seven patients in the tramadol group, 1 patient in the ondansetron group and 2 patients in the saline group had nausea and vomiting (p = 0.031). Haemodynamic variables, neonatal outcome and perioperative complications were comparable between the 3 groups. Conclusion : Ondansetron 4mg was comparable to tramadol 0.5mg/kg but superior to placebo in protecting Caesarean section patients undergoing spinal anaesthesia against shivering. Ondansetron further protects against nausea and vomiting while having no significant side effects. Ondansetron at a dose of 4mg may be considered for prophylaxis against shivering in this group of patients. Keywords : Ondansetron, Tramadol, Prophylaxis, Postanaesthesia shivering, spinal anaesthesia, Caesarean section