Addition of fentanyl to bupivacaine prolongs anesthesia and analgesia in axillary brachial plexus block

Background and Objectives: To evaluate the analgesic and anesthetic effects of 40 mL bupivacaine 0.25%, 40 mL bupivacaine 0.25% plus fentanyl 2.5 mug/mL, and 40 mL bupivacaine 0.125% plus fentanyl 2.5 mug/mL for axillary brachial plexus block. Methods: Sixty patients were randomly allocated to 3 groups and received axillary brachial plexus block with 40 mL bupivacaine 0.25 % (group B), 40 mL bupivacaine 0.25 % with fentanyl 2.5 mug/mL (group BF), or 40 mL bupivacaine 0.125% with fentanyl 2.5 mug/mL, (group DBF). The onset times and the duration of sensory and motor blocks, duration of analgesia, hemodynamic parameters, and adverse events were noted. Results: The mean duration of sensory block and analgesia were longer in group BF (10.1 hours and 20.9 hours) than group B (6.9 hours and 11.6 hours) and DBF (5.9 hours and 12.0 hours) (P < .01, P < .001, respectively). The mean duration of motor block was also longer in group BF (10.7 hours) than group B (4.9 hours) (P < .01). Only 2 patients experienced motor block in group DBF. The frequency of successful block was 35% in group DBF (P < .01). Hemodynamic parameters were similar in all groups. In group B, only 1 patient experienced dizziness. Nausea was observed in 1 patient in each fentanyl group. Conclusion: The addition of 100 mug/mL fentanyl to 0.25% bupivacaine almost doubles the duration of analgesia following axillary brachial plexus block when compared with 0.25% bupivacaine alone.