Clinical Research Directory

Correlation of Diaphragm Shear-Wave Elastography With Transdiaphragmatic Pressure in Healthy Adults: a Feasibility Study

Changes in intrapleural pressure after lung volume reduction in Chronic Obstructive Pulmonary disease (COPD) patients can lead to complications, including an increased risk of pneumothorax. This procedure, intended to improve lung function, may disturb the pressure balance within the pleural space, potentially precipitating pneumothorax. Careful monitoring of intrapleural pressure could help predict patients at risk. However, intrapleural pressure can currently only be measured invasively. Diaphragm shear-wave elastography (SWE) has been shown to reflect transdiaphragmatic pressure during isovolumetric inspiratory efforts and ventilation against inspiratory loading, and therefore may serve as a non-invasive surrogate for intrapleural pressure. This project outlines a stepwise study plan to evaluate SWE as a tool for intrapleural pressure monitoring (Figure 1). The project only moves to the next phase is the study previous phase was achieved successfully. The current protocol involves the first phase: to validate diaphragm SWE against transdiaphragmatic pressure and assess measurement reliability for local ultrasound systems in healthy adults.This prospective, single-centre, observational validation study will include twelve healthy adult volunteers. During a single study session, participants will perform standardized inspiratory efforts while simultaneous measurements of diaphragm SWE, transdiaphragmatic pressure (via esophageal and gastric balloon catheters), and mouth pressures are obtained. These methods are routinely applied in physiological research and carry minimal risk. Apart from brief nasal or throat discomfort during catheter placement, no significant adverse effects are expected. By establishing the relationship between diaphragm SWE, transdiaphragmatic pressure, and mouth pressures, this study aims to provide the essential validation step for future clinical research in COPD patients following lung volume reduction.

Incidence and Impact of ICU-acquired Diaphragm Weakness

ICU survivors are at an increased risk of hospital and ICU readmission. Among the complications of ICU stay, diaphragmatic dysfunction is common, with a prevalence of 60 to 80%, and is associated with increased mortality and prolonged hospital stays. Furthermore, several studies have reported that the observation of impaired respiratory muscle function upon ICU discharge is associated with a poor long-term prognosis. However, the incidence and prognostic impact of persistent diaphragmatic dysfunction at ICU discharge have never been evaluated. The measurement of dyspnea, a composite evaluation of respiratory muscle function, has not been assessed for predicting prognosis upon ICU discharge. The hypothesis of the project is that the presence of ICU-acquired diaphragmatic dysfunction at ICU discharge is associated with a poorer prognosis within 90 days.