Background and Objectives The aim of this study was to compare the efficacy and safety of continuous axillary brachial plexus block by infusion and by intermittent injection of bupivacaine 0.25% in the management of postoperative pain.

Methods Two methods of continuous axillary brachial plexus block for pain management were compared in a prospective randomized trial. Twenty 16- to 62-year-old male patients (ASA I and II), undergoing microsurgery, received 0.25% bupivacaine following surgery, by either continuous infusion (group C, n=10), or intermittent hourly bolus (group B, n=10), via an axillary brachial plexus catheter inserted prior to operation. Efficacy assessments and analysis of plasma bupivacaine levels were performed for up to 38 hours postsurgery.

Results There was no difference between groups with respect to pain scores, degree of motor block, or supplemental narcotic requirements. Plasma bupivacaine levels were higher in group C, with the difference reaching significance after 26 hours (means ± SEM: C = 1.03 ± 0.10 μg/mL, B = 0.73 ± 0.08 μg/mL, P < .05). There were no significant differences in cumulative bupivacaine doses or infusion rates between the groups. Complications included one case of axillary artery puncture at insertion, two unplanned premature catheter removals, and a self-limited grand mal convulsion in a known epileptic.

Conclusions Overall, both techniques provided safe and effective postoperative analgesia. As compared with continuous infusion, intermittent bolus administration resulted in lower plasma bupivacaine levels despite similar infusion rates.