Background and aims Ultrasound-guided axillary brachial plexus block can be either performed with a multiple-injection technique (each nerve blocked individually), or a dual-injection technique (an injection for the musculocutaneous nerve and another one for the radial, median, and ulnar nerves). When the arm is in full abduction, the musculocutaneous nerve lies close to the axillary artery and the other nerves. This randomised controlled single-blinded trial tested the hypothesis that a single-injection technique has a reduced procedure time and is as effective as a multiple-injection technique.

Methods Fifty ASA I-III patients randomly received an ultrasound-guided multiple- or single-injection block with 32 mL of local anaesthetics. In the single injection group, the needle was positioned inferior to the axillary artery, without needle tip repositioning. In the multiple injection group, each nerve was blocked separately. the primary outcome was the performance time. Secondary outcomes included needling time, block success, oxycodone consumption and pain scores.

Results Demographic data were similar between groups (table 1). Success rates were 96% [95%CI:80%-100%] and 84% [95%CI:64%-96%] in the multiple- and single-injection groups, respectively (p=0.16) Mean procedure time was significantly reduced in the single-injection group (5.7 min [95%CI:5.1–6.4]), when compared with the multiple-injection group (4.0 min [95%CI:3.6.4.4]; p<0.001). Other block-related outcomes were similar between groups except needling time which was significantly reduced in the single-injection group (table 2). table 3 presents the pain-related outcomes.

Conclusions An axillary brachial plexus block performed with a single-injection technique is associated with a reduced time performance but an increased consumption of opioids at 24 postoperative hours.