Hemidiaphragmatic paresis after interscalene supplementation of insufficient axillary block with 3 mL of 2% mepivacaine

Breathing difficulty, agitation, and confusion developed in a 55-year-old male, ASA classification group III with a non-small-cell lung cancer 10 min after interscalene supplementation of insufficient axillary block with 3 mL of 2% mepivacaine with adrenaline 5 mu g mL(-1). After administration of thiopentone and suxamethonium the patient's trachea was intubated and the lungs were ventilated with oxygen-enriched air. The block was successful and surgery was conducted as scheduled. Radiographic monitoring of the lungs at the end of operation showed ipsilateral elevation of the diaphragm with reduced respiratory excursions. Postoperatively, the patient was somnolent and hypercapnic, but maintained satisfactory oxygenation while breathing spontaneously and was extubated. Both the temporal relationship of events and the regression of all symptoms within three hours suggest that 3 mt of mepivacaine with adrenaline injected into the interscalene space blocked the phrenic nerve and compromised diaphragmatic function, which precipitated the respiratory failure.