The optimal dose of fentanyl added to 0.2% ropivacaine for postoperative epidural analgesia after gynecological surgery

Background: Combined administration of local anesthetics and an opioid is frequently used in order to minimize the dose of each drug and to reduce adverse effects. Although fentanyl is commonly administered with local anesthetic, side effects of fentanyl increase in a dose-dependent manner. In this study, we determined the optimal dose of epidural fentanyl after gynecological surgery. Methods: One hundred and sixteen adult patients scheduled for elective gynecological surgery were divided into 3 groups according to postoperative epidural analgesics; 0.2% ropivacaine (group R), 0.2% ropivacaine with 2 μg · ml^-1 fentanyl (group RF 2), or 0.2% ropivacaine with 5 μg · ml^-1 fentanyl (group RF 5). Each analgesic was infused at 5 ml · hr^-1 for 48 hr. Pain scores , incidence of NSAIDs administration and side effects were recorded for 48 hr after the surgery. Results and Conclusions: Ropivacaine alone could not provide sufficient analgesia. Although the addition of 5 μg · ml^-1 fentanyl to 0.2% ropivacaine at a rate of 5 ml · hr^-1 improved postoperative pain, side effects caused by fentanyl increased. Supplementing 2 μg · ml^-1 fentanyl provided sufficient analgesia with the least incidence of side effects.