Effectiveness of Brachial Plexus Blocks in Obesity: Secondary Analysis of Randomized Controlled Trial

Abstract

Background: Brachial plexus block for hand and upper extremity procedures in the obese presents a unique set of technical challenges. The authors examined how obesity affects procedural success, quality of anesthesia, and patient satisfaction. Methods: Secondary analysis of a randomized control trial comparing the retroclavicular versus supraclavicular brachial plexus block for distal upper extremity surgery was conducted. Patients were randomized to supraclavicular or retroclavicular brachial plexus block groups in the original trial. In this study, the authors dichotomized patients by obesity to compare differences in outcomes. Results: Sixteen of 117 patients (13.7%) were obese. The groups were statistically well balanced in terms of baseline and operative variables. Obese patients had increased imaging time 2.7 minutes (95% confidence interval [CI], 1.44-3.92) versus 1.9 minutes (95% CI, 1.64-2.16), P value = .05; needling time 6.6 minutes (95% CI, 5.17-7.95) versus 5.8 minutes (95% CI, 5.04-5.74), P = .02; and procedure time 9.3 minutes (95% CI, 7.04-11.46) versus 7.3 minutes (95% CI, 6.79-7.79), P = .01. Block success and complications were not statistically significant. The visual analog scores during the block, at 2 hours, and 24 hours after were not statistically different. Patient satisfaction score among obese patients was 9.1 (95% CI, 8.6-9.6) versus 9.2 (95% CI, 9.1-9.4), P = .63. Conclusion: Findings from this trial suggest that despite an increased procedural difficulty, the use of both supraclavicular and retroclavicular brachial plexus blocks is associated with comparable quality of anesthesia, similar complication profile, equal opioid requirements, and similar patient satisfaction in the obese.