To assess the efficacy of pre-incisional peritonsillar infiltration of two doses of ketamine on postoperative analgesia compared with peritonsillar normal saline in children undergoing tonsillectomy. Double blind, randomized controlled trial. Department of Anaesthesiology, Surgical Intensive Care and Pain Management, Civil Hospital, Karachi, Dow University of Health Sciences, from August 2008 to January 2009. Seventy-five ASA physical status one patients, aged 5 - 12 years scheduled for

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... ctomy were enrolled in this study. Patients were divided into three groups of 25 each. Group-A received normal saline, Group-B, ketamine 0.5 mg/kg while group-C ketamine 1 mg/kg respectively. All medications were 2 ml and were applied 1 ml per tonsil; 3 minutes before tonsillectomy incision. Anaesthesia was induced and maintained with standard technique. All patients were monitored throughout surgery. The Children's Hospital of Eastern Ontario Pain Scale (CHEOPS) and Wilson sedation scale were used to evaluate pain levels and sedation respectively after operation. Mean duration of analgesia was significantly higher in group-C (17.28 ± 5.33 hours) as compared to group-B (11.36 ± 4.15 hours) and A (3.2 ± 0.71 hours) as well as group-B was also significantly higher than group-A (p < 0.05). Group-A had significantly higher pain scores than group-B and group-C. Both B and C groups had comparable pain scores, which were statistically significant at 6 and 8 hours. Single 0.5 or 1 mg/kg injection of ketamine given before surgical incision by peritonsillar infiltration provides efficient pain relief during postoperative period without significant side-effects in children undergoing tonsillectomy.