Incidence of diaphragmatic paralysis following supraclavicular brachial plexus block and its effect on pulmonary function

Thirty unpremedicated ASA physical status 1-3 patients aged between 18 and 69 years, scheduled for upper limb surgery, received a conventional supraclavicular brachial plexus block using a nerve stimulator and bupivacaine 0.375% 0.5 ml.kg-1. Spirometric measurements of pulmonary function and ultrasonographic assessments of diaphragmatic function were made before the block and at 10-min intervals after injection until full motor block of the brachial plexus had developed. Complete paralysis of the ipsilateral hemidiaphragm occurred in 50% of patients. Seventeen per cent of patients had reduced diaphragmatic movement and the rest (33%) had no change in diaphragmatic movement. Those with complete paralysis all showed significant decreases in pulmonary function, whereas those with reduced or normal movement had minimal change. All patients remained asymptomatic throughout, with normal oxygen saturation on room air.