Describe the supraclavicular approach to blocking the brachial plexus.
With the patient supine, arms at the side, and head turned to the contralateral side, the midpoint of the clavicle is identified. At the superior border, a 22G 4-inch insulated needle is inserted, directed caudally in the plane of the patient. Making contact with the first rib, one then walks off the rib posteri-orly until a paresthesia is achieved. After a negative aspira-tion, a volume of 40 cc of local anesthetic is injected. The same preparation as used for the interscalene block can also be used here. It is important to be aware that the subclavian artery is in close proximity to this area and, if punctured, it would be very difficult to provide adequate compression. This block has a high incidence of pneumothorax.