Axillary Block of the Brachial Plexus

Abstract

Traditionally, the axillary approach to brachial plexus block has been used more frequently in the pediatric population, primarily because this approach reduces the risk of complications, such as pneumothorax, that are greater in other approaches such as supraclavicular and infraclavicular. The advent of ultrasound has made proximal approaches more feasible with less risk; however, the axillary approach remains a useful technique for pediatric patients. Ultrasound guidance may improve success rates of axillary block since the needle tip can be positioned to approach each of the plexus’s terminal nerves, and local anesthetic spread can be monitored to spread circumferentially around the nerves. Combining nerve stimulation to confidently locate the radial nerve is often necessary as this nerve can be challenging to locate under ultrasound in children. Additionally, it is possible to successfully block the musculocutaneous nerve using controlled needle repositioning towards the coracobrachialis muscle. Since there is an abundance of vessels in this region, complete avoidance of vessel puncture can be a challenge even when utilizing ultrasound imaging. It is important to understand that the plexus is close to the surface and hence the needle should be directed cautiously while this block is attempted. Smaller doses can be used to provide adequate blockade of this plexus in infants and children.