Neuromuscular ultrasound for evaluation of the diaphragm

Abstract

Neuromuscular clinicians are often asked to evaluate the diaphragm for diagnostic and prognostic purposes. Traditionally, this evaluation is accomplished through history, physical exam, fluoroscopic sniff test, nerve conduction studies, and electromyography (EMG). Nerve conduction studies and EMG in this setting are challenging, uncomfortable, and can cause serious complications such as pneumothorax. Neuromuscular ultrasound has emerged as a non-invasive technique that can be used in the structural and functional assessment of the diaphragm. This article reviews different techniques for assessing the diaphragm using neuromuscular ultrasound and the application of these techniques to enhance diagnosis and prognosis by neuromuscular clinicians.

B-Mode Ultrasound Assessment of Diaphragm Structure and Function in Patients With COPD

“…In comparison with other methods of evaluating diaphragm function, sonography has advantages over plain chest radiograph and videofl uoroscopy, both of which have fairly high rates of false positive and false negative results, and transdiaphragmatic pressure measurements, which are invasive, uncomfortable, and only helpful in bilateral paralysis. 11 Needle EMG of the diaphragm can be very helpful but is relatively contraindicated in patients with COPD because of concerns over hyperinfl ation and a possible heightened risk of pneumothorax.…”

Sensitivity and specificity of diagnostic ultrasound in the diagnosis of phrenic neuropathy

“…The usual workup of patients presenting with unexplained dyspnea may include chest radiographs, fluoroscopy, phrenic nerve conduction studies (NCS), needle EMG of the diaphragm, pulmonary function testing, and transdiaphragmatic pressure measurements; all of these diagnostic tests can produce false-positive and false-negative findings, and some tests are invasive or uncomfortable for the patient. [1][2][3][4][5][6][7][8][9] Ultrasound of the diaphragm is an imaging technique that has recently become more accessible to clinicians, and it can improve the technical quality and safety of phrenic NCS and needle EMG. 10,11 When used in isolation, diagnostic ultrasound can identify atrophy and impaired motion or contractility of the diaphragm.…”

“…In reviewing the literature, we found several studies that examined normal ranges of phrenic CMAPs, and the lower limit of normal varied between 0.1 and 0.4 mV. 7,8,[25][26][27] One way to decrease the risk of recording a volumeconducted response (a false-negative) is to directly visualize the diaphragm with ultrasound to observe diaphragm contraction while stimulating the phrenic nerve, and this is a technique that we have adopted recently in our practice. 10,25 One limitation of this study is that only the role of B-mode sonography (and not M-mode sonography) was evaluated in diagnosing diaphragm dysfunction.…”

Evaluación de la motilidad diafragmática por ultrasonido en pacientes llevados a cirugía ortopédica de miembro superior bajo anestesia regional utilizando bloqueo infraclavicular

“…Estos resultados pudieron relacionarse con la baja prevalencia reportada en la literatura para ambos resultados con el bloqueo de plexo braquial con abordaje infraclavicular [3,4]. Los valores promedio de excursión diafragmática antes del bloqueo infraclavicular y después de este, obtenidos en el estudio, estuvieron dentro del rango reportado por otros autores [14,17].…”

“…En una serie de pacientes, la evaluación ecográfica del diafragma fue realizada en posiciones supino, semisentado y de pie, en que se comparó la medición basal de reposo (luego de espiración normal) con la medición en inspiración normal y en inspiración profunda (sniff, por su denominación en inglés) [14][15][16]. Los valores promedio de desplazamiento diafragmático en reposo y en inspiración profunda reportados en la literatura fueron 1,84 ± 0,76 y 7,88 ±del hombro, quienes aceptaron participar en el estudio y dieron su consentimiento informado por escrito.…”