Symptomatic Phrenic Nerve Palsy After Supraclavicular Block in an Obese Man

Abstract

Regional anesthesia has an expanding role in upper extremity surgery. Brachial plexus blocks offer several advantages including providing effective analgesia, reducing narcotic requirements, and facilitating ambulatory care surgery. Despite the popularity of nerve blocks, the surgeon must not forget the complications associated with regional anesthesia. This article describes a case of symptomatic phrenic nerve palsy after supraclavicular brachial plexus block in an obese man. A 46-year-old obese man underwent a left-sided supraclavicular block in preparation for decompression of Guyon's canal for ulnar mononeuropathy at the wrist. The patient experienced acute-onset dyspnea, chest discomfort, and anxiety, and physical examination demonstrated reduced breath sounds in the left hemithorax. Chest radiographs documented elevation of the left hemidiaphragm consistent with an iatrogenic phrenic nerve palsy. The patient was admitted for 23-hour observation and underwent an uncomplicated ulnar nerve decompression under Bier block anesthesia 1 week later. No long-term sequelae have been identified; however, there was a delay in surgical care, admission to the hospital, and transient pulmonary symptoms. We attribute this complication to significant abdominal obesity causing compromised pulmonary reserve and poor tolerance of transient hemidiaphragmatic paresis. In recent studies, waist circumference and abdominal height were inversely related to pulmonary function. We suspect that the incidence of symptomatic phrenic nerve palsy associated with brachial plexus blocks will increase as the prevalence of obesity increases in this country.