Comparison of ketamine and morphine for analgesia after tonsillectomy in children

In a double blind study we compared the effects of i.m. ketamine with morph ine on postoperative analgesia in children undergoing tonsillectomy. Eighty children (aged 6-15 yr) were randomized to receive either i.m. morphine 0. 1-0.15 mg kg(-1) or ketamine 0.5-0.6 mg kg(-1), after induction of a standa rd general anaesthetic. Pain scores 30 min after extubation were higher (P< 0.05) in the ketamine group, but were similar thereafter to the morphine gr oup. Mean (SD) times to recovery from anaesthesia were 20.1 (SD 6.5) min in the ketamine group compared to 14.2 (5.6) min in the morphine group (P<0.0 1). There were no differences in supplemental analgesia requirements, or th e incidence of vomiting or dreaming between the groups. We conclude that ke tamine 0.5 mg kg(-1) i.m. may be an alternative analgesic for children unde rgoing tonsillectomy.