A comparison of the vertical infraclavicular and axillary approaches for brachial plexus anaesthesia

Background: This prospective, randomized study compared the efficacy of the vertical infraclavicular and axillary approaches using a single injection blockade of the brachial plexus. The primary endpoint was complete blockade in dermatomes C5-Th1, while secondary endpoints included onset time, motor block, block performance time, surgical success rate, patient satisfaction, and side-effects/complications. Methods: Sixty patients, American Society of Anesthesiologists physical status I or II, scheduled for surgery of the forearm or hand received either a vertical infraclavicular (n = 30) or an axillary block (n = 30). A single injection of 0.5 ml/kg ropivacaine 7.5 mg/ml was made after electrolocalization of nerve fibres corresponding to the median nerve at maximum 0.5 mA (2 Hz, 0.1 ms). Onset and distribution of analgesia and motor block were assessed at 5, 10, 15, 20, 30 and 60 min after the local anaesthetic injection. A complete block was defined as analgesia in all dermatomes (C5-Th1) at 60 min post-injection. Results: The vertical infraclavicular approach provided complete blockade in 29 patients (97%) and the axillary approach in 23 patients (77%). Analgesia in C5-C6 dermatomes and corresponding motor block occurred significantly more frequently in the vertical infraclavicular approach, which also had the shortest onset time. Block procedure was quicker in the axillary approach. Side-effects were similar in both groups, and there were no permanent sequelae. Patient satisfaction was equally high in both groups. Conclusions: The vertical infraclavicular approach provides a more complete block than the axillary approach when using a single injection technique and equal volumes/doses of local anaesthetic.