Prophylactic Low Dose Intravenous Ketamine Infusion in Prevention of Intraoperative and Postoperative Shivering after Spinal Anesthesia in Adults Scheduled for Abdominal and Lower Limb Surgeries- A Prospective Randomized Controlled Trial

Background: Incidence of perioperative shivering following spinal anesthesia (SA) is 40% to 60% based on current literature. Ketamine in doses between 0.2 to 0.75 mg/kg has been used to prevent shivering after SA, but associated with dose dependent side-effects. This study evaluated the efficacy of Ketamine in a lower dose (0.1 mg/ kg) for prevention of intraoperative shivering (IOSH) and postoperative shivering (POSH) following SA. Methods: Seventy patients who belong to ASA 1 and 2 posted for elective abdominal and lower limb surgeries were randomized among two groups. Adults in Group K were subjected to 0.1 mg/kg of ketamine as intravenous (IV) bolus succeeded by an infusion of 0.1 mg/kg/hr, while adults in Group S received 5 ml saline succeeded by 0.1 ml/kg/hr saline as IV infusion till the end of surgery. 3 ml of hyperbaric bupivacaine 0.5% without additive was used for SA. The incidence of IOSH and POSH was the primary outcome, degree of shivering, sedation scores, side-effects, and hemodynamics among the groups were the secondary outcomes.  Results: Demographic parameters and Hemodynamics were comparable among groups. IOSH incidence was significantly higher in Group S (60%) upon comparison with Group K (20%) (p< 0.001) and POSH incidence was significantly higher in Group S (22.9%) upon comparison with Group K (2.9%) (p< 0.012). Grades of shivering were more among Group S when compared with Group K (p< 0.001). Sedation scores were remarkably higher in Group K (p < 0.001) without any other side-effects. Conclusion: Prophylactic low dose ketamine (0.1 mg/kg) as IV bolus and infusion (0.1 mg/kg/hr) significantly decreased IOSH and POSH following SA with significant sedation and without other side-effects when compared to saline.