A prospective, randomized comparison between double-, triple-, and quadruple-injection ultrasound-guided axillary brachial plexus block

This prospective, randomized, observer-blinded study compared double-, triple-, and quadruple-injection ultrasound (US)-guided axillary brachial plexus block (AXB) for upper-extremity surgery. One hundred twenty patients were randomly allocated to receive a double- (n = 40), triple- (n = 40), or quadruple-injection (n = 40) US-guided AXB. The local anesthetic agent (lidocaine 1.5% with epinephrine 5 μg/mL) and total volume (35 mL) were identical in all subjects. For all 3 groups, the musculocutaneous nerve was identified and anesthetized first. Subsequently, a perivascular technique was performed. Lidocaine was deposited at the 6-o'clock position of the axillary artery for the 2-injection group. For the 3- and 4-injection groups, injections were carried out at the 12-/6-o'clock and 2-/10-/6-o'clock positions, respectively. During the performance of the block, the performance time, number of needle passes, and complications (vascular puncture, paresthesia) were recorded. Subsequently, a blinded observer assessed the onset time, block-related pain scores, and success rate (surgical anesthesia). The main outcome variable was the total anesthesia-related time (sum of performance and onset times). No differences were observed among the 3 groups in terms of total anesthesia-related time (29.2-31.4 mins), success rate (90.0%-97.5%), block-related pain scores, vascular puncture, and paresthesia. Compared with its 3- and 4-injection counterparts, the double-injection technique required fewer needle passes (4.0 ± 1.6 vs 5.2-6.0 ± 1.7-2.8; both P ≤ 0.001). Double-, triple-, and quadruple-injection US-guided perivascular AXB result in comparable success rates and total anesthesia-related times. Because it requires fewer needle passes, the double-injection technique provides a simple alternative for US-guided AXB.