Control of shivering during regional anaesthesia: prophylactic ketamine and granisetron

Background: The aim of the present study was to compare placebo, ketamine, granisetron and a combination of ketamine and granisetron in the prevention of shivering caused by regional anaesthesia. Methods: In this prospective, randomized, double-blind study, 160 ASA I and II patients undergoing urological surgery were included. Subarachnoid anaesthesia was performed in all patients with bupivacaine 15 mg. The patients were randomly allocated to receive saline (group P, n = 40), ketamine 0.5 mg (group K, n = 40), granisetron 3 mg (group G, n = 40) or ketamine 0.25 mg + granisetron 1.5 mg (group KG, n = 40). Shivering was graded as 0 = no shivering, 1 = piloerection or peripheral vasoconstriction but no visible shivering, 2 = muscular activity in only one muscle group, 3 = muscular activity in more than one muscle group but not generalized, and 4 = shivering involving the whole body. If 15 min after spinal anaesthesia and concomitant administration of a prophylactic dose of one of the study drugs, the patients shivered according to at least grade 3, the prophylaxis was regarded as ineffective and intravenous (i.v.) pethidine 25 mg was administered. Results: After 15 min, the number of patients with observed shivering was 22 in group P, 6 in group G, 7 in group GK and 0 in group K. The difference between group K and all the other groups was statistically significant (P < 0.0001). The number of patients with a shivering score of 3 was statistically significantly higher in group P compared with the other groups. Conclusions: The prophylactic use of 0.5 mg/kg i.v. ketamine was effective in preventing shivering developed during regional anaesthesia.