Letter to the Editor: A Few Suggestions for Preventing Failure of Ultrasound-Guided Blocks for Below the Shoulder Surgery

We read with great interest the original research published by Anatoli Stav et al.1 in which they compared supraclavicular (SCL), infraclavicular (ICL), and axillary (AX) approaches to the brachial plexus with ultrasonography for upper limb surgeries.1 They concluded that all approaches can be used to provide adequate anesthesia for upper limb surgeries below the shoulder. Nevertheless, they also experienced some sparing and failed blocks: 3 patients from the SCL group, 3 from the ICL group, and 4 from the AX group had a positive pin-prick test; 2 patients from the AX group received sedation supplementation; and 1 patient in the AX group experienced ulnar sparing which required a general anesthetic. Of the 13 failed blocks, 7 (i.e. ~50%) utilized the axillary approach to the brachial plexus. In this letter, we have tried to analyze and provide an explanation regarding the possible causes of the failed blocks performed under ultrasound guidance, particularly for the axillary approach.