Lidocaine with fentanyl, compared to morphine, marginally improves postoperative epidural analgesia in children

Abstract

Purpose: To compare the epidural administration of fentanyl (I μg·mL-1) combined with lidocaine 0.4% to preservative- free morphine for postoperative analgesia and side effects in children undergoing major orthopedic surgery. Methods: In a prospective, double-blind study, 30 children, ASA 1-11, 2-16-yr-old, were randomly allocated to receive immediately after surgery either epidural F-L (epidural infusion at a rate of 0.1-0.35 mL·kg-1·hr-1 of 1 μg·mL-1 of fentanyl and lidocaine 0.4%) or epidural M (bolus of 20 μg·kg-1 of morphine in 0.5 mL·kg-1 saline every eight hours). Both groups received 40 mg·kg-1 of iv metamizol (dipyrone) every six hours. In the F-L Group, blood samples were taken on the second and third postoperative day to determine total lidocaine concentrations. Adequacy of analgesia using adapted pediatric pain scales (0-10 score) and side-effects were assessed every eight hours postoperatively. Results: Resting pain scores were under 4, 95% of the time in the F-L Group and 87% of the time in the M Group (Chi square=4.674, P <0.05). The frequency of complications was very similar in both groups. The F-L Group total plasma lidocaine concentrations were directly related to the dose received, and below the toxic range in all patients. Conclusions: Postoperative epidural fentanyl with lidocaine infusion provides slightly better analgesia than conventional bolus administration of epidural morphine. Side-effects or risk of systemic toxicity were not augmented by the addition of lidocaine to epidural opioids.