Sonographic evaluation of a paralyzed hemidiaphragm from ultrasound-guided interscalene brachial plexus nerve block.

The ultrasound-guided interscalene brachial plexus is becoming increasingly popular for anesthesia in the management of upper-extremity injuries by emergency physicians. Traditional high-volume injections of local anesthesia will also affect the phrenic nerve, leading to temporary paralysis of the ipsilateral hemidiaphragm. With direct ultrasound guidance, more precise needle placement allows for lower-volume injections that reduce inadvertent spread of local anesthetic to the phrenic nerve without decreasing the efficacy of onset of time and quality of the block. However, the risk of incidental paralysis of the hemidiaphragm is still not eliminated with low-volume intraplexus injections. This case highlights this common complication of interscalene brachial plexus nerve blocks and demonstrates how emergency physicians can easily use B-mode and M-mode ultrasound to evaluate the paralysis of the hemidiaphragm.