Does ketamine or magnesium affect posttonsillectomy pain in children?

Summary Background: Many previous studies have suggested a role for the N‐methyl‐D‐aspartate (NMDA) receptor antagonists ketamine and magnesium in decreasing postoperative pain and analgesic requirements in adults, but none has investigated these medications in children. Methods: This randomized, double‐blind, placebo‐controlled study evaluated the effects of ketamine and magnesium in children undergoing tonsillectomy. Eighty patients, aged 3–12 years, were randomly assigned to four groups. Patients received either ketamine 0.15 mg·kg−1, magnesium sulphate 30 mg·kg−1, ketamine 0.15 mg·kg−1 plus magnesium sulphate 30 mg·kg−1, or placebo intravenously 5 min prior to the start of surgery. Intraoperative analgesia was standardized, and included fentanyl and dexamethasone. Results: There were no differences among the groups with respect to pain assessment postoperatively. Compared with placebo, the treatment groups did not require less fentanyl in the postanaesthesia recovery room or consume less codeine in the first 24‐h postoperatively. There was no evidence of synergism between ketamine and magnesium. There were no differences among the groups in the incidence of nausea, vomiting, sedation, bleeding, or dreaming postoperatively. Conclusion: This study did not demonstrate a decrease in pain or analgesic consumption in children undergoing tonsillectomy when pretreated with a small dose of ketamine and/or magnesium.