RESUMEN
Ultrasound-guided nerve blocks (UGNBs) are becoming a more common method for pain control in the emergency department. Specifically, brachial plexus blocks have shown promise for acute upper extremity injuries as well as an alternative to procedural sedation for glenohumeral reductions. Unfortunately, there is minimal discussion in the EM literature regarding phrenic nerve paralysis (a well-known complication from brachial plexus blocks). The anatomy of the brachial plexus, its relationship to the phrenic nerve, and why ultrasound-guided brachial plexus blocks can cause phrenic nerve paralysis and resultant respiratory impairment will be discussed. The focus on patient safety is paramount, and those with preexisting respiratory conditions, extremes of age or weight, spinal deformities, previous neck injuries, and anatomical variations are at greater risk. We put forth different block strategies for risk mitigation, including patient selection, volume and type of anesthetic, block location, postprocedural monitoring, and specific discharge instructions. Understanding the benefits and risks of UGNBs is critical for emergency physicians to provide effective pain control while ensuring optimal patient safety.