2026 Workshop Handout Bundle-W11C - Advanced EMG and US of Respiratory System

W11C - Advanced EMG and US of Respiratory System - Boon Skolka

Pdf Summary

This workshop handout reviews electrodiagnostic and ultrasound assessment of respiratory muscle dysfunction, particularly in patients with unexplained dyspnea or difficulty weaning from mechanical ventilation. Possible causes include central nervous system disorders, nerve-root or peripheral nerve disease, neuromuscular junction disorders, myopathy, and phrenic neuropathy.<br /><br />Phrenic nerve conduction studies (NCS), diaphragm needle electromyography (EMG), and ultrasound provide complementary information about diaphragm integrity and help distinguish neuropathic, myopathic, and central causes. Phrenic NCS records the diaphragm’s response to nerve stimulation; careful electrode placement and stimulation are needed to avoid confusing responses from nearby nerves.<br /><br />B-mode ultrasound assesses diaphragm thickness and thickening during inspiration, while M-mode measures movement. A resting thickness below 0.13 cm or thickening ratio below 1.2 may indicate dysfunction, though results must be interpreted in context: shallow breathing, obesity, and mechanical ventilation can reduce thickening without primary muscle disease. M-mode excursion can help identify weakness or paralysis. Ultrasound also helps select a safe site and guide needle placement.<br /><br />Diaphragm EMG can clarify whether abnormal movement reflects nerve, muscle, or reduced central activation. The handout describes an intercostal approach and emphasizes informed consent, knowledge of anatomy, and attention to risks such as pneumothorax, bleeding, and injury to abdominal organs. Ultrasound guidance is especially useful when anatomy is difficult, the diaphragm is severely atrophic, or the patient has obesity, COPD, or bleeding risk.<br /><br />Ultrasound can also locate and assess chest-wall muscles, including the serratus anterior, intercostals, and rhomboid. Overall, combining clinical assessment with NCS, EMG, and ultrasound improves diagnostic confidence and may inform prognosis and ventilator-weaning evaluation.

Keywords

electrodiagnostic

ultrasound

nmus

sono

diaphragm dysfunction

phrenic nerve conduction

diaphragm electromyography

respiratory muscle weakness

mechanical ventilation weaning

neuromuscular disorder

m-mode ultrasound

pneumothorax risk