2022 Workshop Handout Bundle-Advanced EMG and US of Respiratory System- Boon/Litchy

Advanced EMG and US of Respiratory System- Boon/Litchy

Pdf Summary

Patients with unexplained dyspnea or failure to wean from the ventilator may undergo electrodiagnostic evaluation (EDX) to determine the underlying cause. Various conditions such as central drive disorders, anterior horn cell or nerve root diseases, polyneuropathy, myasthenia gravis, myopathy, and phrenic neuropathy can contribute to these symptoms. Phrenic nerve conduction studies (NCS) and needle electromyography (EMG) can provide valuable information about the underlying pathophysiology and potential for recovery in these cases. However, both techniques require experience and can be technically challenging and involve some degree of risk.<br /><br />Ultrasound is now being utilized in conjunction with phrenic NCS and diaphragm needle EMG for examining the diaphragm. It helps in identifying the safest intercostal space for needle insertion, determining the depth of penetration required to reach the diaphragm, and visualizing the needle entering the diaphragm. Ultrasound imaging also allows the assessment of diaphragm motion and quality, both in response to respiration and phrenic nerve stimulation.<br /><br />Ultrasound techniques, such as B mode and M mode ultrasound, are used to evaluate the diaphragm. B mode ultrasound measures diaphragm thickness and identifies any atrophy or decreased contractility. M mode ultrasound assesses diaphragm motion by observing its movement with respiration. These ultrasound techniques provide valuable information about diaphragm function and can help in diagnosing respiratory dysfunction.<br /><br />Additionally, needle EMG of the diaphragm is performed to obtain further diagnostic information in patients with respiratory symptoms. The diaphragm anatomy and function should be understood before attempting needle EMG. The needle is inserted through the intercostal space to access the diaphragm, and motor unit potentials firing with each inspiration confirm entry into the diaphragm. This technique is relatively safe, with a low risk of complications such as pneumothorax.<br /><br />Ultrasound guidance can be used during needle EMG to minimize risks and improve accuracy. It helps in identifying the best intercostal space for needle insertion and visualizing the needle throughout the examination. Ultrasound-guided needle EMG is particularly beneficial in challenging cases such as obesity, altered anatomy, severe COPD, and patients on anticoagulation.<br /><br />Overall, the use of ultrasound in combination with phrenic NCS and diaphragm needle EMG provides a comprehensive evaluation of the respiratory system and helps in diagnosing and managing patients with unexplained dyspnea or ventilator dependence.

Keywords

unexplained dyspnea

failure to wean

electrodiagnostic evaluation

phrenic nerve conduction studies

needle electromyography

ultrasound

diaphragm examination

respiratory dysfunction

needle EMG

ventilator dependence

nmus

sono