Effects of intraoperative i.v. acetaminophen vs i.m. meperidine on post-tonsillectomy pain in children

Background. Enteral acetaminophen, when used alone, is not very effective for postoperative analgesia because of delayed absorption and sub-therapeutic plasma concentrations. In contrast, i.v. acetaminophen is devoid of these shortcomings and could potentially provide adequate postoperative analgesia as a single agent. This randomized double-blind study compared the analgesic effects of i.v. acetaminophen and i.m. meperidine in paediatric patients undergoing tonsillectomy. Methods. Eighty children undergoing tonsillectomy were randomized to receive either acetaminophen 15 mg kg(-1) i.v. (acetaminophen group) or meperidine 1 mg kg(-1) i.m. (meperidine group), intraoperatively. Anaesthesia was induced with either sevoflurane inhalation or propofol, and was maintained with sevoflurane. After operation, the objective pain scale (OPS), Ramsay sedation score and Aldrete score were recorded every 5 min, and nurses' satisfaction was determined on a 7-point scale (1-7). Results. On admission to the recovery room, OPS scores were 3.1 (sem 0.3) for the acetaminophen group and 2.1 (sem 0.3) for the meperidine group (P=0.147); however, Ramsay sedation scores were 3 (sem 0.2) and 4 (sem 0.3) for the acetaminophen and meperidine groups, respectively (P < 0.05). Patients in the meperidine group continued to be more sedated 5 min after arrival in recovery (P < 0.05). Acetaminophen group patients achieved an Aldrete score of 10 min sooner than those in the meperidine group [median (IQR) time: 15 (0-20) min vs 25 (15-30) min, respectively, P=0.005]. Adjusted nurse satisfaction scores were similar in both groups [6.1 (sem 0.2) vs 5.7 (sem 0.2) min, P=0.311]. Conclusion. Compared with i.m. meperidine, i.v. acetaminophen provided adequate analgesia, less sedation and earlier readiness for recovery room discharge among paediatric patients undergoing tonsillectomy.