Comparison of 0.2% Ropivacaine and 0.25% Bupivacaine in Pediatric Caudal Block : Evaluation of Postoperative Pain and Plasma Concentration of Local Anesthetics

The purpose of this study is to assess the effects of pediatric caudal block using 0.2% ropivacaine or 0.25% bupivacaine on intraoperative and postoperative analgesia. We also examined plasma concentrations of the local anesthetics after caudal injection. Forty children, who were scheduled for inguinal herniorrhaphy, underwent caudal block with 0.2% ropivacaine 1 ml/kg (group R, n=20) or 0.25% bupivacaine 1 ml/kg (group B, n=20) after induction of general anesthesia. Anesthesia was maintained using a face mask with 66% nitrous oxide in oxygen supplemented with sevoflurane. Postoperative pain scores using a pediatric pain scale and plasma concentration of each local anesthetic were measured using gas chromatography. Since two patients in Group R and one patient in Group B required more than 1 % of sevoflurane to prevent their body movement when the surgical procedure was started, they were excluded from this study as the failed block. No patient in Groups R and B required intraoperative analgesics under light general anesthesia and postoperative analgesics. The maximum plasma concentration of ropivacaine and bupivacaine were 0.70±0.28μg/ml at 45 min and 0.80±0.42μg/ml at 30 min after the caudal injection, respectively. In conclusion, pediatric caudal block with 0.2 % ropivacaine is an alternative to 0.25 % bupivacaine for intraoperative and postoperative analgesia