A prospective, double-blind, randomized trial of caudal block using ropivacaine 0.2% with or without fentanyl 1 μg kg^-1 in children

Background. It has been reported that ropivacaine produces vasoconstriction in contrast to vasodilation produced by bupivacaine. It is possible that additives to ropivacaine can provide further analgesic advantages compared with bupivacaine. We thus evaluated whether the addition of fentanyl to ropivacaine prolonged the duration of analgesia after a single shot caudal block. Methods. A total of 36 children undergoing surgical procedures below the umbilicus were randomly allocated to one of two groups: Group F received ropivacaine 0.2%, 1 ml kg^-1 with fentanyl 1 μg kg^-1 and Group S received ropivacaine 0.2%, 1 ml kg^-1 with saline. The analgesic effect of the caudal block was evaluated using the Children's Hospital of Eastern Ontario Pain Scale (CHEOPS) and sedation was assessed using the Steward score at 30 min after extubation and at 1, 2, 4, 6, 12 and 24 h. The first analgesic requirement time and side-effects in a 24 h period were also recorded. Results. There were no differences in characteristics between the groups. The end-tidal concentration of sevoflurane at extubation in Group F was significantly lower than in Group S. However, there was no significant difference in time from discontinuation of the volatile anaesthetics to tracheal extubation. No statistical differences were found in the CHEOPS and Steward score, and the time to first analgesia. The incidence of postoperative vomiting was not significantly different. Conclusion. We found that the addition of fentanyl 1 μg kg^-1 to ropivacaine 0.2% for caudal analgesia provides no further analgesic advantages over ropivacaine 0.2% alone.