Effect of needle approach to the axillary artery on transarterial axillary brachial plexus block quality

ABSTRACT

BACKGROUND: The authors sought to determine whether a shallow needle approach to the axillary artery would improve complete sensory blocks of median, radial, and ulnar nerves as compared with a perpendicular approach when transarterial axillary block is performed using a scalp vein needle (23G, 3/4'). METHODS: Fifty-four patients were allocated equally to a perpendicular group (the PA group) or a shallow approach group (SA group). Sensory and motor scores were evaluated and compared in the two groups at 5-minute intervals for 20 minutes after block. The main outcome variables were rates of blockage of median, radial, and ulnar nerves. RESULTS: Excellent block rates (defined as completion of surgery using brachial plexus block alone) were obtained in both groups (SA group 77.8% vs. PA group 70.3%, P = 0.755). However, the rate of blockage of all three nerves was significantly higher in the SA group (74% vs. 40.7%, P = 0.013). Furthermore, the rate of complete sensory block of the radial nerve at 20 minutes was significantly greater in the SA group (85.2% vs. 59.3%, P = 0.033). CONCLUSIONS: A shallow needle approach to the axillary artery resulted in a significantly higher median, radial, and ulnar nerve block rate at 20 minutes after LA injection than a perpendicular approach.