Comparative Efficacy of Intravenous Ketamine and Tramadol in Reducing Postspinal Anesthesia Shivering in Urological Surgeries: A Triple-blind Randomized Clinical Trial.

Objective: Shivering is one of the most common complications due to disturbances in the thermoregulatory system after regional anesthesia, leading to adverse outcomes and decreased patient satisfaction. Ketamine and tramadol are considered mild analgesics that affect the thermoregulatory center. This triple-blind, randomized clinical trial aims to explore the comparative efficacy of intravenous ketamine and tramadol in reducing postspinal anesthesia shivering in high-risk urological surgeries. Methods: A total of 90 patients undergoing urological surgeries under spinal anesthesia at Shahid Hasheminejad Hospital in Tehran in 2024 were randomized into three groups: ketamine (0.5 mg/kg), tramadol (0.5 mg/kg), and placebo (normal saline). Variables, including ambient temperature, patient demographics, surgery duration, and anesthetic techniques, were meticulously controlled. The primary outcome was the incidence of shivering, measured using the Crossley and Mahajan scale. Data were analyzed using the SPSS software Version 19, employing Chi-square tests, analysis of variance, and logistic regression. Findings: The patients were homogeneous regarding demographic and surgical variables. No significant difference was found in patients' body temperature upon admission. The incidence of shivering was significantly lower in the tramadol group (23.3%) compared to the ketamine group (36.7%) and placebo group (60%) ( Conclusion: The incidence of shivering was significantly lower in the tramadol group compared to the ketamine and placebo groups. Tramadol demonstrated superior efficacy with minimal side effects. While effective, ketamine had a higher incidence of hemodynamic fluctuations and psychotropic effects.