Efficacy of Prophylactic Low Dose Ketamine in Preventing Shivering after General Anesthesia

Background and Post anesthetic shivering is a common and unpleasant postoperative complication. The aim of this study was to evaluate the efficacy of low-dose prophylactic ketamine in preventing postoperative shivering after general anesthesia. A double-blind randomized controlled trial was carried out in 60 patients of ASA class I-II undergoing general anesthesia. General anesthesia was performed with fentanyl، midazolam، sodium thiopental and atracurium. The patients were randomly allocated to receive either saline 0. 9% or ketamine 0. 25 mg kg−1 intravenously at the beginning of wound closure. Occurrence and severity of shivering was evaluated for 30 min in the recovery room. Side effects were also assessed in the recovery room. In postoperative period incidences of shivering were 36. 07% and 6. 7% in control group and ketamine group، respectively. The difference between ketamine group and control group was statistically significant. (P=0. 005) The number of patients with shivering score of 2 was significantly higher in control group compared with that of the ketamine group. (p=0. 02) The incidence of side effects was similar in the two groups. Prophylactic low dose ketamine (20mg) was effective in preventing postoperative shivering without significant side effect. (Clinical Trials Registry Number: IRCT201012224923N1)