Interscalene brachial plexus block: area of analgesia, complications and blood concentrations of local anesthetics.

In a prospective clinical study including 100 patients, the consequences of using the interscalene approach to block the brachial plexus were investigated according to the area of analgesia, complications, and blood concentrations of local anesthetics. Sufficient analgesia of the shoulder and the upper part of the arm was obtained in 98-99% of the cases, whilst the area of analgesia in the forearm and the hand was more variable. In two groups, with 10 patients in each group, the blood concentration was measured during the first 50 min after injection in the neurovascular sheath by either the interscalene or the axillary approach. The peak values were at the same level in the two groups, but there was a much more rapid rise in concentration in the interscalene group. No toxic reactions were seen. The complications were in accordance with those reported in other publications.