- Indications: shoulder and upper arm surgery
- Transducer position: transverse on neck, 3–4 cm superior to clavicle, over external jugular vein
- Goal: local anesthetic spread around superior and middle trunks of brachial plexus, between anterior and middle scalene muscles
- Local anesthetic: 15–25 mL
Ultrasound-guided interscalene brachial plexus block; transducer and needle position to obtain the desired ultrasound image for an in-plane approach.
The ultrasound-guided technique of interscalene brachial plexus block differs from nerve stimulator or landmark-based techniques in several important aspects. Most importantly, distribution of the local anesthetic is visualized to assure adequate spread around the brachial plexus. Ultrasound guidance allows multiple injections around the brachial plexus, therefore eliminating the reliance on a single large injection of local anesthetic for block success as is the case with non–ultrasound-guided techniques. Ability to inject multiple aliquots of local anesthetic also may allow for the reduction in the volume of local anesthetic required to accomplish the block. Repetition of the block in case of inadequate anesthesia is also possible, a management option that is unpredictable without ultrasound guidance. Finally, the risk of major vessel and nerve puncture during nerve block performance is reduced.
The brachial plexus at the interscalene level is seen lateral to the carotid artery, between the anterior and middle scalene muscles (Figures 29-2, 29-3, and 29-4). Prevertebral fascia, superficial cervical plexus and sternocleidomastoid muscle are seen superficial to the plexus. The transducer is moved in the superior-inferior direction until two or more of the brachial plexus trunks are seen in the space between the scalene muscles. Depending on the depth of field selected and the level at which the scanning is performed, first rib and/or apex of the lung may be seen. The brachial plexus is typically visualized at a depth of 1 to 3 cm.
Relevant anatomy for interscalene brachial block and transducer position to obtain the desired views. Brachial plexus (BP) is seen sandwiched between middle scalene muscle (MSM) laterally and anterior scalene muscle (ASM) medially. Ultrasound image often includes a partial view of the lateral border of the sternocleidomastoid muscle (SCM) as well as the internal jugular vein (IJV) and carotid artery (CA). The transverse process of one of the cervical vertebrae is also often seen.
Interscalene brachial plexus is seen between middle scalene muscle and anterior scalene muscle. Carotid artery is seen medial at 1 cm depth in this image.
Typical image of the brachial plexus (BP). The BP is seen positioned between the anterior scalene muscle (ASM) and the middle scalene muscle (MSM). The superficial cervical plexus (white arrowhead) can be seen posterior ...