Ultrasound in the Assessment of Respiration

Electromyographers are often asked to evaluate patients presenting with dyspnea or respiratory failure, to rule out an underlying neuromuscular cause for those symptoms. Available tools for diagnosing such patients include pulmonary function tests, transdiaphragmatic pressure testing, various imaging modalities, phrenic nerve conduction studies, and diaphragm electromyography. Phrenic nerve conduction studies and diaphragm electromyography are technically challenging and can be limited by both false positive and false negative results. Integration of diagnostic ultrasound can enhance the accuracy and safety of diaphragm electromyography, and improve sensitivity and specificity of phrenic nerve conduction studies. In addition, brightness-mode ultrasound imaging of the diaphragm allows for measurement of muscle thickness and contractility, and is a very sensitive and specific diagnostic test in this setting. This article will review the electromyographer's approach to patients presenting with respiratory symptoms, with a focus on neuromuscular ultrasound.