Addition of fentanyl to mepivacaine does not affect the duration of brachial plexus block

Abstract Objectives : Numerous studies dealing with the effects of the addition of opioids to a local anesthetic (LA) in peripheral nerve block have been published, but results are conflicting. The present study was aimed at studying the question of whether fentanyl addition to mepivacaine could improve intra- and postoperative conditions of an axillary plexus block. Methods : After institutional approval and informed consent, 51 patients (ASA I and II) undergoing plexus anesthesia for forearm and hand surgery were included into the study. Patients were randomly assigned to one of three groups: group A (50 ml mepivacaine, 15 mg ml −1 , with 4 ml saline for nerve block and 4 ml normal saline (NS) subcutaneously), group B (50 ml mepivacaine, 15 mg ml −1 , with 100 μg fentanyl in 4 ml NS for nerve block, and 4 ml NS subcutaneously), or group C (50 ml mepivacaine, 15 mg ml −1 , with 4 ml NS for nerve block and 100 μg fentanyl in 4 ml saline subcutaneously). Visual analogue score (VAS), sensory block, motor block and hemodynamics were recorded prior to and 5, 10, 30 and 60 min and 2, 3, 4, 12 and 24 h after induction of the block. Results : There were no differences in VAS scores, time to administration of the first postoperative dose of an analgesic, or the total dose of analgesic given postop. No differences with respect to the intensity of sensory block and motor block or time to onset of block were observed. Conclusions : Addition of 100 μg fentanyl to mepivacaine, 15 mg ml −1 , does not affect the quality of anesthesia of brachial plexus block.