Indications and Contraindications

Brachial plexus blocks are recommended for emergency procedures on the upper extremities as anesthetic techniques in conscious patients and as analgesic techniques for elective surgery, mostly in anesthetized patients.^{[201] [202] [203] [204]} They are of particular interest in outpatient surgery, for which they are associated with a high degree of patient satisfaction.^{[205] [206]} Axillary blocks are considered first, especially when the lesions involve the forearm and the hand, because they are virtually free of complications. Coracoid approaches are still being evaluated in children but seem particularly useful when catheter placement is mandatory to provide long-lasting pain relief. This approach facilitates immobilization, and dressing is easier to achieve and more comfortable than with axillary techniques. Supraclavicular blocks are recommended when the lesion or a tourniquet is located on the proximal part of the arm, including the elbow. These blocks are often preferred in boisterous children, especially in the case of an unstable fracture or a weak tendon or nerve repair. Among the three main techniques, the parascalene approach should be considered first because it is virtually free of complications. The interscalene approach, especially the modified technique, is the second choice, and peri-subclavian approaches should be restricted to children older than 10 years because of the danger of creating a pneumothorax. Distal nerve blocks are used as complementary blocks when distribution of anesthesia is incomplete after a more proximal block or for a distal lesion (i.e., surgery involving one finger only).

Brachial plexus nerves, trunks, and cords are mixed nerves. They are best identified by using a nerve stimulator, and it would be imprudent, particularly in anesthetized patients, not to use this technique to perform a brachial plexus block, especially by a supraclavicular or coracoid route. Occasionally, in difficult patients, surface mapping using a nerve stimulator^[207] or ultrasound techniques^{[208] [209]} may help to locate the nerves sought.

Specific contraindications to axillary blocks include axillary lymph adenopathies (e.g., infection, malignancies), unstable fractures or lesions in which the movement of the upper extremity is prohibited, and proximal lesions or placement of a tourniquet. Contraindications to supraclavicular blocks depend on the insertion route; they must be avoided in cases of respiratory insufficiency or when a bilateral block is necessary. The parascalene approach is virtually free of complications.