Addition of fentanyl to 1.5% lidocaine does not increase the success of axillary plexus block.

Abstract

This randomized, double-blind study was designed to evaluate the effects of the addition of fentanyl (F) to lidocaine (L) on the onset, duration, and success rate of axillary brachial plexus block. After institutional approval and informed consent, 53 ASA 1 and ASA 2 patients scheduled for orthopedic surgery using brachial plexus anesthesia were included in the study. Axillary brachial plexus block was performed using a peripheral nerve stimulator to localize one nerve of the major plexus. The patients were randomly allocated to two groups. The L + F group (n = 27) were administered 38 mL of 1.5% L with 1/200,000 epinephrine and 100 micrograms of F, and the L + S group (n = 26) were administered 38 mL of 1.5% L with 1:200,000 epinephrine and 2 mL of normal saline. The onset (monitored every 5 minutes) and duration (monitored every 30 minutes) of surgical anesthesia, defined as the total abolition of the pinprick response, were evaluated in each nerve territory. The patients were similar with regard to demographic data and the nerve trunks stimulated. In the L + F group, the onset time was only reduced (P = .012) for the musculocutaneous nerve. The duration of surgical anesthesia and the motor block were similar in both groups. The frequency of complete plexus block and the frequency of anesthesia for each nerve trunk were similar in both groups. There is no clinical benefit resulting from the addition of fentanyl to the local anesthetic for axillary brachial plexus block.