Hypercapnic respiratory distress and loss of consciousness: a complication of supraclavicular brachial plexus block.

Supraclavicular brachial plexus block is a common anesthetic technique performed for surgery of the upper extremities. We experienced a case of acute hypercapnic respiratory distress with loss of consciousness during creation of an arteriovenous fistula under ultrasound-guided supraclavicular brachial plexus block using 30 mL of 0.75 % ropivacaine. We detected ipsilateral hemidiaphragmatic paralysis by means of M-mode ultrasonography of the block. We thus speculate that phrenic nerve palsy caused by supraclavicular brachial plexus block was the underlying mechanism of the event. Bedside ultrasonography played a pivotal role in making a differential diagnosis and in managing this patient.