Ultrasound innovations in diaphragm assessment: an integrative review of expanding clinical applications

Abstract

Introduction Diaphragm dysfunction is prevalent across various patient populations, requiring precise structural and functional assessment. Ultrasound, being bedside-accessible and radiation-free, has gained relevance for evaluating the diaphragm and other respiratory muscle. Recent advancements have introduced novel techniques that have expanding its assessment scope. This review aims to identify emerging ultrasound methods for quantitative diaphragm assessment in adults, emphasising reliability and clinical relevance. Methods A systematic literature search was conducted using keywords related to the diaphragm, ultrasound techniques and innovation. We included original studies on adult participants using innovative ultrasound methods extending beyond conventional assessments. Studies lacking original data, case reports, animal studies and studies on automated analysis techniques were excluded. Screening and data extraction followed a structured process, with one researcher extracting data and a second verifying accuracy. Results were categorised by reliability and by physiological and clinical outcomes. Results Of 1411 records screened, 288 full-text articles were reviewed, and 36 studies met inclusion criteria, with four additional studies identified via reference analysis. These studies, published between 2013 and 2024, explored seven innovative techniques: the area method, contrast-enhanced ultrasound, echogenicity/echodensity, excursion of the zone of apposition, shear wave/strain elastography, speckle tracking and pulsed-wave tissue Doppler imaging. Studies focused on both healthy subjects and critically ill, surgical and COPD patients. Conclusions Recent ultrasound advancements enhance diaphragm assessment by evaluating muscle quality, functional mechanical properties and blood flow. These innovative methods also provide alternatives when conventional approaches are limited. Further research is essential to refine protocols, validate clinical applications and standardise assessments for broader implementation.