Retroclavicular vs supraclavicular brachial plexus block for distal upper limb surgery: a randomised, controlled, single-blinded trial

Abstract

Background: Regional anaesthesia for upper limb surgery is routinely performed with brachial plexus blocks. A retroclavicular brachial plexus block has recently been described, but has not been adequately compared with another approach. This randomised controlled single-blinded trial tested the hypothesis that the retroclavicular approach, when compared with the supraclavicular approach, would increase the success rate.

Methods: One hundred and twenty ASA physical status 1-3 patients undergoing distal upper limb surgery were randomised to receive an ultrasound-guided retroclavicular or supraclavicular brachial plexus block with 30 mL of a 1:1 mixture of mepivacaine 1% and ropivacaine 0.5%, using a single-injection technique without needle tip repositioning. The primary outcome was block success rate 30 min after local anaesthetic injection, defined as a composite score of 14 of 16 points, inclusive of sensory and motor components. Secondary outcomes included needling time, time to first opioid request, oxycodone consumption, and pain scores (numeric rating scale, 0-10) at 24 h postoperatively.

Results: Success rates were 98.3% [95% confidence interval (CI): 90.8%, 99.9%] and 98.3% [95% CI: 90.9%, 99.9%] in the supraclavicular and retroclavicular groups, respectively (P=0.99). The mean needling time was reduced in the supraclavicular group [supraclavicular: 5.0 (95% CI: 4.7, 5.4) min; retroclavicular: 6.0 (95% CI: 5.4, 6.6) min; P=0.006]. The mean time to first opioid request was similar between groups [supraclavicular: 439 (95% CI: 399, 479) min; retroclavicular: 447 (95% CI: 397, 498) min; P=0.19] as were oxycodone consumption [supraclavicular: 10.0 (95% CI: 6.5, 13.5 mg; retroclavicular: 7.9 (95% CI: 4.8, 11.0) mg; P=0.80] and pain scores at 24 h postoperatively [supraclavicular: 1.2 (95% CI: 2.1, 2.7); retroclavicular: 1.5 (95% CI: 1.6, 2.4); P=0.09].

Conclusions: Ultrasound-guided retroclavicular and supraclavicular brachial plexus blocks share identical success rates, while providing similar pain relief. Reduced needling time in the supraclavicular approach is not clinically relevant.

Clinical trial registration: NCT02641613.

Keywords: brachial plexus; nerve block; postoperative analgesia; regional anaesthesia; ultrasound-guided.

Copyright © 2019 British Journal of Anaesthesia. All rights reserved.

Figures

Fig 1

Ultrasound images of the two brachial plexus block techniques using a single-injection technique where the local anaesthetic was injected without needle repositioning unless paraesthesia was elicited. (a) Supraclavicular brachial plexus block: the needle tip (white arrow) was positioned at the junction of the first rib and subclavian artery (‘corner pocket’) in order to anaesthetise the divisions of the brachial plexus—upper limit is delimited by the dotted arrows. (b) Retroclavicular brachial plexus block: the needle tip (white arrow) was positioned posterior to the axillary artery, in order to block the lateral, posterior, and medial cords of the brachial plexus, from a cephalad to caudad direction, indicated by the dotted arrow. AXa, axillary artery; LA, local anaesthetic; PMm, pectoralis major muscle; Pmm, pectoralis minor muscle; SCa, subclavian artery.

Fig 2

Flow of patients through trial.

Fig 3

Percentage of patients with a minimal composite score of 14 points according to time. There was no significant difference between groups throughout the 30 min period of block assessment.