Two-dimensional shear wave elastography: a new tool for evaluating respiratory muscle stiffness in chronic obstructive pulmonary disease patients

Abstract

Background Impaired respiratory function caused by respiratory muscle dysfunction is one of the common consequences of chronic obstructive pulmonary disease (COPD). In this study, two-dimensional shear wave elastography (2D-SWE) was used to measure diaphragm stiffness (DS) and intercostal muscle stiffness (IMS) in patients with COPD; in addition, the value of 2D-SWE in evaluating respiratory function was determined. Methods In total, 219 consecutive patients with COPD and 20 healthy adults were included. 2D-SWE was used to measure the DS and IMS, and lung function was also measured. The correlation between respiratory muscle stiffness and lung function and the differences in respiratory muscle stiffness in COPD patients with different severities were analysed. Results 2D-SWE measurements of the DS and IMS presented with high repeatability and consistency, with ICCs of 0.756 and 0.876, respectively, and average differences between physicians of 0.10 ± 1.61 and 0.07 ± 1.65, respectively. In patients with COPD, the DS and IMS increased with disease severity (F1 = 224.50, F2 = 84.63, P < 0.001). In patients with COPD, the correlation with the forced expiratory volume in one second (FEV1)/forced vital capacity (FVC), predicted FEV1% value, residual volume (RV), total lung capacity (TLC), RV/TLC, functional residual capacity (FRC) and inspiratory capacity (IC) of DS (r1=-0.81, r2=-0.63, r3 = 0.65, r4 = 0.54, r5 = 0.60, r6 = 0.72 and r7=-0.41, respectively; P < 0.001) was stronger than that of IMS (r1=-0.76, r2=-0.57, r3 = 0.57, r4 = 0.47, r5 = 0.48, r6 = 0.60 and r7=-0.33, respectively; P < 0.001). Conclusion 2D-SWE has potential for use in evaluating DS and IMS. A specific correlation was observed between respiratory muscle stiffness and lung function. With the worsening of the severity of COPD and the progression of lung function impairment, the DS and IMS gradually increased.

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“…2 It is also used in treatment monitoring 3 as well as image-guided therapy. 4 By evaluating tissue elasticity, elastography techniques enable the diagnosis of lung diseases like pulmonary fibrosis, 5,6 pulmonary edema, 7 and emphysema, 8 as well as liver conditions such as fibrosis, 9 cirrhosis, 10 and hepatic tumors. 11 In renal disease, elastography aids in the early detection of subclinical renal fibrosis, 12 a major risk factor for chronic kidney disease, offering a valuable tool for preventive intervention.…”

The Importance of the Diaphragm in Neuromotor Function in the Patient with Chronic Obstructive Pulmonary Disease

“… 46 As the disease progresses, the chest expands to a lesser extent, the intercostal musculature will become stiffer, and the respiratory accessory musculature will be more ineffective. 47 The diaphragm will be forced to work harder to overcome the resistances of the more rigid chest, with consequent morphological change (more “flat”), structural change (shorter fibers), positional change (inspiratory attitude), phenotypic change (phenotypic shift) and functional (greater stiffness).…”

“…Contractile fibers show signs of atrophy, myolysis, sclerosis and fibrosis. 44 , 47 We can find a decline in endoplasmic reticulum function, which dysfunction causes an accumulation of intracellular calcium (Ca2+). 51 The accumulation of Ca2+ in the sarcoplasm is cytotoxic for the cell, stimulating biochemical reactions that can lead to apoptosis.…”