RESUMO
To compare the effects of intramuscular ketamine with pethidine and placebo on post operative shivering in children undergoing tonsillectomy. A prospective randomized double-blind study was conducted at King Abdulaziz Naval Base Hospital, Jubail, Kingdom of Saudi Arabia, from November 2006 to October 2007. One hundred and twenty children [American Society of Anesthesiologists Grade 1, aged 5-12 years] were enrolled. Children were randomly allocated to receive ketamine 1 mg/kg [group K, n=40], or pethidine 0.5 mg/kg [group P, n=40], or normal saline [group S, n=40] intramuscularly just after induction of general anesthesia. Hemodynamic parameters, oxygen saturation and tympanic temperature were measured and recorded before induction of anesthesia and at regular intervals thereafter. An investigator blinded to the treatment group, graded postoperative shivering using a 5 point scale. The number of patients shivering on arrival to the recovery room and at 10 and 20 minutes after operation were significantly less in groups K [1,1,1] than in group S [19,12,17]. No patient that received pethidine shivered. The time to first analgesic requirement in group S was shorter than groups K and P [p=0.001]. The study indicates that the use of a prophylactic low dose ketamine was found to be effective in preventing post anesthesia shivering in children undergoing tonsillectomy. Ketamine may have at least theoretical advantages over pethidine as regard respiratory depression, nausea, and vomiting