Changes in diaphragm stiffness assessed with ultrasound shear wave elastography reflect changes in transdiaphragmatic pressure

Abstract

Background: Transdiaphragmatic pressure (Pdi) is the gold standard for the assessment diaphragm function. However, it is an indirect measure of diaphragm contractility. Muscle stiffness measured using ultrasound shear wave elastography (SWE) provides reliable estimates of force output in locomotor muscles. It is yet unknown whether SWE can be used in the diaphragm. Aim: To investigate the potential of SWE for gauging diaphragm contractility. Methods: 14 volunteers were studied during a stepwise inspiratory loading protocol from 0 to 50% of maximal inspiratory pressure during closed-airways maneuvers (Fig 1A) and during ventilation against external elastic loads (Fig 1B). Pdi was monitored and shear modulus of the diaphragm (SMdi) was measured over the right zone of apposition. Pearson correlation coefficient (r) and repeated measures correlation (R) were used to determine within-subject and overall relationships between Pdi and SMdi, respectively. Fig. 1: Typical recordings. Results: During closed-airways maneuvers, mean Pdi correlated to mean SMdi (r ranged from 0.77 to 0.96, all p Conclusions: SWE provides a new opportunity for non-invasive assessment of diaphragm contractility.