Prophylactic Ketamine for Prevention of Post-Spinal Shivering: Randomised Controlled Trial

Background: Post spinal anaesthesia shivering is a common complication and a leading cause of discomfort to patients under spinal anaesthesia. It follows a decrease in sympathetic tone which results in vasodilatation and redistribution of heat from core to peripheral part of the body. The physiological consequences of shivering include increase in cardiac and systemic energy expenditure, oxygen consumption and carbon dioxide production. Objective: The aim of this study was to compare prophylactic low dose intravenous ketamine with placebo for prevention of post spinal anaesthesia shivering. Methods: Following Institutional Ethical Review committee approval, this randomized, double blind study was conducted on eighty two patients aged ranged 16 to 50 years and ASA I and II who had repair of vesicio-vaginal fistula under spinal anaesthesia. Immediately after the spinal anaesthesia was established; Groups K and S received iv ketamine 0.25 mg/kg diluted to 5 mls and iv normal saline 5mls respectively. Incidence of shivering, haemodynamic parameters and side effects were assessed as primary outcome measures. Results: The incidence of shivering in groups S and K was 46.3% vs 7.3% in Group S compared to Group K respectively. Two (4.8%) patients had hallucination and 1 (2.4%) patient vomited among the group K patients. Similarly, mean arterial blood pressure, heart rates at 5 and 10 minutes after the spinal anaesthesia Group K were significantly higher. Conclusion: The use of prophylactic low dose ketamine significantly reduced spinal anaesthesia-induced shivering.