BLOCK AT A GLANCE
Block of the brachial plexus at the medial aspect of the infraclavicular fossa, close to the midpoint of the clavicle.
The ultrasound (US)-guided brachial plexus block at the costoclavicular space has been recently described as an alternative approach to the traditional infraclavicular block (sagittal paracoracoid approach deep to the pectoral muscles). Of note, the site of injection is similar to the landmark-based “vertical infraclavicular brachial plexus block” (VIB) described by Kilka et al. The compact organization of the brachial plexus at this level, clustered lateral to the artery and more superficial than in the traditional approach, may be more favorable to block with a single needle pass. The more cephalad spread of LA toward the supraclavicular fossa also may reach the trunks of the brachial plexus and, therefore, provide shoulder analgesia.
Few recent studies suggest that the onset of sensory and motor block may be somewhat faster compared to the paracoracoid approach and that lower volumes of LA may be efficacious.
The cephalic vein and the thoracoacromial artery may be on the needle’s path. Care must be taken to avoid these vessels during needle advancement. Otherwise, risks are similar as for infraclavicular block and mostly related to the proximity of the axillary artery, vein, and the pleura
The transition from trunks to cords of the brachial plexus occurs at the costoclavicular space, where all the neural elements travel flattened, arranged laterally to the axillary artery. It is at this level that the lateral and medial pectoral nerves leave the corresponding cords, whereas the subscapular and thoracodorsal nerves leave the posterior cord. More distally, the cords separate from each other and surround the axillary artery as they travel deep to the pectoral muscles (Figure 16-1).
Functional anatomy of the brachial plexus for the costoclavicular approach. Note the relationship of the brachial plexus cords to the proximal axillary artery. BP, brachial plexus; AV, axillary vein; AA, axillary artery.
The cords of brachial plexus at this location lie between the subclavius and the anterior serratus muscle, lateral to the artery, in a consistent relationship to each other. The lateral cord is in the most superficial, the posterior and medial cords lie lateral and medial respectively sharing a common sheath. The second rib can be imaged deep to the serratus muscle. The axillary vein is located medially to the artery and deep to the pectoralis major muscle
Sonoanatomy and reverse anatomy of the brachial plexus at the costoclavicular level. AA, axillary artery; AV, axillary vein; MC, medial cord; LC, lateral cord; PC, posterior cord; R2, second rib.
The costoclavicular approach results in sensory and motor block of the upper extremity and anterior shoulder (Figure 16-3). The cephalad spread of larger volumes (20 mL) of the LA may reach to the supraclavicular and the interscalene brachial plexus and result in a complete block of the shoulder. Larger volumes (35 mL) may even reach the phrenic nerve. The combination of low-volume costoclavicular block with a suprascapular nerve block is an effective alternative for shoulder surgery (see Chapter 18). Like with any other brachial plexus block, the skin of the medial side of the upper arm is not anesthetized (that is innervated by the intercostobrachialis [T2]). When required, the skin of the medial aspect of the upper arm can be anesthetized by an additional subcutaneous injection on the medial aspect of the arm just distal to the axilla.
Distribution of anesthesia with the costoclavicular brachial plexus block.
The block can be performed with the patient in the supine or semi-sitting position, and a slight elevation of the head of the bed may improve the patient’s comfort and exposure of the anatomy. The patient’s head is turned away from the side to be blocked, and if possible, the arm is abducted 90° to facilitate the view of the plexus as it positions the plexus more superficially (Figure 16-4)
Recommended patient position for a costoclavicular brachial plexus block.
Position the transducer in the medial infraclavicular fossa parallel and next to the clavicle to identify the axillary artery. The transducer is then tilted cephalad to image the brachial plexus and the artery in a perpendicular orientation between the subclavius muscle and the serratus anterior. The three cords are visualized in a single transverse US scan superficial and lateral to the artery as a triangular shaped hyperechoic structure (Figure 16-5). Releasing the pressure on the transducer and applying color Doppler is useful to determine the location of the cephalic vein and thoracoacromial artery.