Introduction Regional anesthesia is frequently used for upper limb surgeries and postoperative pain control. Different approaches to brachial plexus blocks are similarly effective but may differ in the frequency and severity of iatrogenesis. We, therefore, examined large-scale registry data to explore the risks of typical complications among different brachial plexus block sites for regional anesthesia.

Methods 26,947 qualifying adult brachial plexus blocks (2007–2022) from the Network for Safety in Regional Anesthesia and Acute Pain Therapy registry were included in a retrospective cohort analysis. Interscalene, supraclavicular, infraclavicular, and axillary approaches were compared for block failure and bloody punctures using generalized estimating equations. For continuous procedures, we analyzed the influence of the approach on catheter failure, neurological disorders, and infections.

Results The axillary plexus block had the highest risk of block failure (adjusted OR, 2.3; 95% CI 1.02 to 5.1; p=0.04), catheter failure (adjusted OR, 1.4; 95% CI 1.1 to 2.0; p=0.02), and neurological dysfunction (adjusted OR, 3.0; 95% CI 1.5 to 5.9; p=0.002). There was no statistically significant difference among block sites for bloody punctures, while infraclavicular blocks had the highest odds for catheter-related infections.

Discussion The axillary approach to the brachial plexus had the highest odds for block failure and neurological dysfunction after catheter placement, as well as a significant risk for catheter failure. However, considering that the axillary approach precludes other complications such as pneumothorax, none of the four common approaches to the brachial plexus has a fundamentally superior risk profile.