The aim of this study was to compare the efficacy of prophylactic ketamine, dexmedetomidine and tramadol for prevention of shivering after spinal anaesthesia. Dexmedetomidine is a highly selective α2 receptor agonist, the role of which in prevention of shivering after spinal anaesthesia has not been studied much. We also studied the efficacy in prevention of shivering, the haemodynamic profiles, and the side effects associated with each drug individually.

00 patients of American Society of Anaesthesiologists physical status class I and II were randomized into four groups with 50 patients in each group. Group K received ketamine 0.5 mg/kg, Group D received Dexmedetomidine 0.5 mcg/kg, Group T received tramadol 0.5 mg/kg and Group C received normal saline by an infusion over 10 minutes just before administering spinal anaesthesia. The groups were studied at scheduled intervals for haemodynamic parameters (heart rate, systolic blood pressure, diastolic blood pressure, mean arterial pressure, surface and core temperatures), grade of shivering, sedation score, and complications like hypotension, bradycardia, requirement of rescue treatment for shivering in the form of pethidine (25 mg IV) and side effects. Analysis of variance (ANOVA) and Kruscal Wallis test were used for data analysis.

Number of patients with higher grades of shivering was significantly less in Group D as compared to other three groups; however, most patients required treatment for accompanying hypotension. Sedation scores were also much higher and statistically significant in this group.

We conclude that all the drugs are effective in prevention of shivering, and dexmedetomidine is better than other two drugs in preventing higher grades of shivering after spinal anaesthesia. Dexmedetomidine is associated with higher sedation scores and hypotension. The dose of dexmedetomidine can be reduced still further to avoid these complications.