Chapter 15: Infraclavicular Brachial Plexus Block

GENERAL CONSIDERATIONS

The infraclavicular brachial plexus block is a well-established regional anesthesia technique for procedures below the shoulder. The infraclavicular block is devoid of respiratory symptoms that can occur with phrenic nerve palsy with supraclavicular and interscalene blocks. Compared to the axillary block, abduction of the arm is not absolutely necessary; therefore, an infraclavicular block may be more suitable in patients with painful fractures or requiring arm immobilization. An infraclavicular block is also suitable for catheter placement because the musculature of the chest wall may help to stabilize the catheter, preventing its dislodgement compared with the more superficial location of the interscalene or supraclavicular approaches.

Ultrasound (US) guidance facilitates the technique and provides more consistent practice by monitoring of the LA distribution. Although it is not always possible to reliably identify all three cords of the plexus at this position, a successful block can be accomplished simply by depositing the LA around the infraclavicular portion of the axillary artery around its lateral, posterior, and medial aspects. Anatomical studies suggest that several factors may negatively affect the success rate of the brachial plexus block at this level due to the anatomical variability among the cords and their location in the infraclavicular fossa. The infraclavicular periarterial space may also have septae and fascial layers within the neurovascular bundle that can prevent the spread of LA to all cords of the brachial plexus unless additional needle tip adjustments and injections are done. Recently, several other approaches to the infraclavicular plexus have been proposed to circumvent limitations of the classic lateral sagittal approach. In particular, the retroclavicular approach provides a better visualization of the needle, and the costoclavicular approach targets the plexus more proximally (see Chapter 16).

Limitations

The neurovascular bundle at the lateral infraclavicular fossa in patients with a large amount of adipose tissue or large pectoral muscles (e.g., obesity or bodybuilders) is positioned much deeper, making adequate imaging difficult. In these patients, a more proximal (e.g., supraclavicular) or more distal (e.g., axillary) approach to brachial plexus block may be more suitable.

Specific Risks

Although uncommon, the proximity of the pleural cavity theoretically poses the risk of pneumothorax. Injury to and dissection of the axillary artery has also been described.

ANATOMY

The boundaries of the infraclavicular space are the pectoralis minor and major muscles anteriorly, serratus anterior and ribs medially, clavicle and the coracoid process superiorly, and the humerus laterally. On its descent, the brachial ...