6 Infraclavicular Block

Perspective

Infraclavicular brachial plexus block is often used for patients requiring prolonged brachial plexus analgesia and is increasingly used for surgical anesthesia by modifying it into a single-injection technique. Anesthesia or analgesia with this technique results in a “high” axillary block. Thus, it is most useful for patients undergoing procedures on the elbow, forearm, or hand. Like the axillary block, this technique is carried out distant from both the neuraxial structures and the lung, thus minimizing complications associated with those areas (see Video 6: Infraclavicular Nerve Block on the Expert Consult Website).

Patient Selection

To undergo an infraclavicular block, the patient need not abduct the arm at the shoulder, as is required for the axillary block, and thus the technique can substitute for an axillary block in patients who cannot abduct their arms. Nevertheless, abduction of the arm at the shoulder may make identification of the axillary artery easier and can provide an enhanced sense of three-dimensional anatomy during the technique.

Pharmacologic Choice

Because prolonged brachial plexus analgesia requires less motor blockade than is needed for surgical anesthesia, the concentration of local anesthetic can be decreased during postoperative analgesia regimens. An appropriate drug is bupivacaine 0.25% or ropivacaine 0.2%, both administered at initial rates of approximately 8 to 12 mL/hr. If a single-injection technique is used, appropriate drugs are lidocaine (1% to 1.5%), mepivacaine (1% to 1.5%), bupivacaine (0.5%), or ropivacaine (0.5% to 0.75%). Lidocaine and mepivacaine produce 2 to 3 hours of surgical anesthesia without epinephrine and 3 to 5 hours with the addition of epinephrine. These drugs are useful for less involved procedures or outpatient surgical procedures. For more extensive surgical procedures requiring hospital admission, longer-acting agents such as bupivacaine or ropivacaine are appropriate. Plain bupivacaine and ropivacaine produce surgical anesthesia lasting 4 to 6 hours; the addition of epinephrine may prolong this period to 8 to 12 hours. The local anesthetic timeline must be considered when prescribing a drug for outpatient infraclavicular block because blocks lasting as long as 18 to 24 hours can result from higher concentrations of bupivacaine with added epinephrine.

Traditional Block Technique

At the level of the proximal axilla, where infraclavicular block is performed, the axilla is a pyramid-shaped space with an apex, a base, and four sides (Fig. 6-1A). The base is the concave armpit, and the anterior wall is composed of the pectoralis major and minor muscles and their accompanying fasciae. The posterior wall of the axilla is formed by the scapula and the scapular musculature, the subscapularis and the teres major. The latissimus dorsi muscle abuts the teres major muscle to form the inferior aspect of the posterior wall of the axilla (Fig. 6-1B). The medial wall of the axilla is composed of the serratus anterior muscle and its fascia, and the lateral wall is formed by the converging muscle and tendons of the anterior and posterior walls as they insert into the humerus (see Fig. 6-1B). The apex of the axilla is triangular and is formed by the convergence of the clavicle, the scapula, and the first rib. The neurovascular structures of the limb pass into the pyramid-shaped axilla through its apex (Fig. 6-2A).