Randomized double-blind comparison of prophylactic ketamine, clonidine and tramadol for the control of shivering under neuraxial anaesthesia

BACKGROUND: Shivering is a common problem during neuraxial anaesthesia. Neuraxial anaesthesia impairs thermoregulatory control and up to a 56.7% incidence of shivering has been reported. AIM: To evaluate the effectiveness of prophylactic use of intravenous ketamine, clonidine and tramadol in control of shivering and to note any side-effects of the drugs used. SETTING AND DESIGN: Randomised double-blind study. METHODS: This study was conducted in 200 ASA grade I and II patients. Neuraxial block was performed with 2.8 mL (14 mg) of 0.5% bupivacaine heavy in all patients. The patients were randomly allocated into four groups of 50 each to receive saline as placebo (group P), ketamine 0.5 mg/kg (group K), Clonidine 75 mcg (group C) and Tramadol 0.5 mg/kg (group T). Temperature and hemodynamic parameters were recorded at every 5-min interval. Shivering was graded from 0 to 4 grades and, if grade 3 shivering occurred, the study drug was considered as ineffective and intravenous pethidine 25 mg was given as rescue drug. STATISTICAL ANALYSIS: Data among groups was compared using one-way ANOVA. The incidence of shivering and side-effects were compared using the chi-square test. RESULTS: The incidence of grade 3 shivering showed a statistically significant difference (P=0.001) in group P (27/50) as compared with the other groups (group K=5/50, group C=2/50, group T=4/50). No drug showed any statistically significant advantage over the other. No major hemodynamic changes were seen with prophylactic use of test drugs; however, sedation score was significantly higher in group K (P<0.05) as compared with the other groups. CONCLUSION: The prophylactic use of ketamine, clonidine and tramadol were effective in preventing shivering during neuraxial anaesthesia without causing any major untoward side-effects.