Abstract: AIM:To assess the efficacy and safety of wound infiltration with ropivacaine compared with intravenous (i. v.) morphine on postoperative pain relief after acute open appendectomy in children. METHODS: A prospective randomized double-blinded study was conducted on 40 patients aged 4-13 years with a preoperative and postoperative diagnosis of acute appendectomy. They were randomly divided into two groups: Ropivacaine Group (21 patients) and Control Group (19 patients). Patients in Ropivacaine Group received wound infiltration with a dose at 0. 4 mL/kg of 0. 75% ropivacaine, then isotonic saline i. v. 0. 4 mL/kg. Patients in Control Group received wound infiltration with isotonic saline at 0. 4 mL/kg, then morphine i. v. 50 μg/kg. On the ward, the parents used a visual analog scale (PVAS) to assess pain score, 0 = no pain, 10 =worst possible pain. Meanwhile, a modified 10-point objective pain scale (OPS) was used by the anaesthetist to assess the pain score. Pain scores, morphine consumption and the incidence of nausea/vomiting were recorded for 24 h. RESULTS:The average postoperative pain score (PVAS and OPS) showed no statistical difference between the two groups (P >0. 05) except during the 24 th hour postoperative period. During the 0. 5 h postoperative period, the average total amount of injections of morphine was statistically lower in the ropivacaine group (control 15. 8 ± 23. 9 μg/kg versus ropivacaine 2. 4 ±10. 9 μg/kg; P <0. 05); and there were 1 patient (4. 76% ) in the Ropivacaine Group and 6 patients (31. 58% ) in the Control Group who had morphine requirement, which also differed significantly between the two groups (P < 0. 05). Although there was no significant difference in the incidence of postoperative nausea/vomiting, during the whole postoperative period, the incidence of postoperative nausea/vomiting was lower in the Ropivacaine Group (control 42% versus ropivacaine 19% ). CONCLUSION: The efficacy of wound infiltration with ropivacaine is similar to morphine (i. v.) on postoperative pain relief after acute appendectomy in children. Ropivacaine delays the time to first morphine requirement and reduces the consumption of morphine. In addition, the incidence of postoperative nausea/vomiting is decreased.

Key words: ropivacaine, morphine, pediatric anesthesia, wound infiltration, pain relief