Ameta N, et al. - In this study involving 200 American Society of Anesthesiologists physical status I and II patients administered spinal anesthesia, researchers compared the efficacy of intravenous (IV) ketamine, dexmedetomidine, and tramadol when used as prophylaxis, to prevent shivering following spinal anesthesia. Either ketamine 0.5 mg/kg IV or tramadol 0.5 mg/kg IV or dexmedetomidine 0.5 microgm/kg IV or 10 mL of 0.9% normal saline (NS) was administered to patients. All the drugs/NS were administered as IV infusion over 10 minutes immediately before spinal anesthesia. As per observations, dexmedetomidine showed efficacy in preventing shivering following spinal anesthesia and was better than tramadol or ketamine in this regard. Furthermore, dexmedetomidine did not cause respiratory depression and offered favorable sedation and surgical conditions. However, a fall in blood pressure and heart rate was expected with its use.