Dyspnea resulting from phrenic nerve paralysis after interscalene brachial plexus block in an obese male--a case report.

Phrenic nerve paralysis is a common complication in interscalene brachial plexus block. This complication is often ignored by most anesthesiologists because no clinical symptoms occur in patients who have no underlying lung disease. We present a case of an obese male suffering from dyspnea due to phrenic nerve block after interscalene brachial plexus block. The decreased respiratory reserve and direct compressing effect of the abdominal organs on the diaphragm in the supine position are thought to be the risk factors in this obese patient. Also discussed are the incidence, diagnostic methods, clinical presentation and treatments of phrenic nerve paralysis during interscalene brachial plexus block.