Double-injection perivascular ultrasound-guided axillary brachial plexus block according to needle positioning: 12 versus 6 o'clock position of the axillary artery

BACKGROUND We conducted prospective, randomized, observer-blinded trial to compare two double-injection perivascular (PV) ultrasound-guided techniques of axillary brachial plexus block (BPB). METHODS American Society of Anesthesiologists physical status I-II, 50 patients undergoing surgery of the forearm, wrist or hand were randomly allocated to two groups. For PV12 group, injection was carried out at the 12 o'clock position using 24 ml of 2% lidocaine. Patients of PV6 group got their injection of 24 ml of 2% lidocaine at direction of 6 o'clock of axillary artery. For all 2 groups, the musculocutaneous nerve was identified and 5 ml of 2% lidocaine was deposited around the nerve. The performance time and the onset time were recorded. The induction time (sum of performance and onset time), the success rate of the block, the need rate of rescue block, and incidence of adverse events was compared. RESULTS The success rate was same (84%) in two groups. The performance time, onset time, and induction time showed no differences between two groups. There were no differences in vessel puncture, paresthesia, and numbness. CONCLUSIONS Double-injection perivascular ultrasound-guided axillary BPB can be performed at 12 o'clock or 6 o'clock position of axillary artery, and performer may choose needle targeting position by considering surgery site. Thus perivascular double-injection technique may be an alternative method for axillary BPB and useful in case of difficult block.