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

Background. Enteral acetaminophen, when used alone, is not veryeffective for postoperative analgesia because of delayed absorptionand sub-therapeutic plasma concentrations. In contrast, i.v.acetaminophen is devoid of these shortcomings and could potentiallyprovide adequate postoperative analgesia as a single agent.This randomized double-blind study compared the analgesic effectsof i.v. acetaminophen and i.m. meperidine in paediatric patientsundergoing tonsillectomy. Methods. Eighty children undergoing tonsillectomy were randomizedto receive either acetaminophen 15 mg kg^–1 i.v. (acetaminophengroup) or meperidine 1 mg kg^–1 i.m. (meperidine group),intraoperatively. Anaesthesia was induced with either sevofluraneinhalation or propofol, and was maintained with sevoflurane.After operation, the objective pain scale (OPS), Ramsay sedationscore 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 were3.1 (SEM 0.3) for the acetaminophen group and 2.1 (SEM 0.3)for the meperidine group (P=0.147); however, Ramsay sedationscores were 3 (SEM 0.2) and 4 (SEM 0.3) for the acetaminophenand meperidine groups, respectively (P<0.05). Patients inthe meperidine group continued to be more sedated 5 min afterarrival in recovery (P<0.05). Acetaminophen group patientsachieved an Aldrete score of 10 min sooner than those in themeperidine group [median (IQR) time: 15 (0–20) min vs25 (15–30) min, respectively, P=0.005]. Adjusted nursesatisfaction 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. acetaminophenprovided adequate analgesia, less sedation and earlier readinessfor recovery room discharge among paediatric patients undergoingtonsillectomy.