Respiratory impact of analgesic strategies for shoulder surgery.

Shoulder surgery is associated with significant postoperative pain in many patients. The use of an interscalene nerve block offers good analgesia but is associated with a high incidence of an ipsilateral phrenic nerve block. Several strategies to avoid this adverse effect have been studied. Possible strategies are (1) using very low volumes of local anesthetics, (2) targeting the brachial plexus at a lower level in the neck, (3) applying a suprascapular nerve block, and (4) applying the combination of a suprascapular and an axillary nerve block. Using systemic analgesics is a less favorable strategy because this may result in less potent analgesia and may cause more adverse effects, including respiratory depression and nausea.