Ultrasonic Evaluation of Diaphragm in Patients with Systemic Sclerosis

Abstract

The diaphragm is the most important muscle in respiration. Nevertheless, its function is rarely evaluated. Patients with systemic sclerosis (SSc) could be at risk of diaphragmatic dysfunction because of multiple factors. These patients often develop interstitial lung disease (SSc-ILD) and earlier studies have indicated that patients with different ILDs have decreased diaphragmatic mobility on ultrasound (US). This study aimed to evaluate diaphragmatic function in SSc patients using US with regard to the ILD, evaluated with the Warrick score on high-resolution computed tomography (HRCT), and to investigate associations between ultrasonic parameters and dyspnea, lung function, and other important clinical parameters. In this cross-sectional study, we analyzed diaphragm mobility, thickness, lung function, HRCT findings, Modified Medical Research Council (mMRC) dyspnea scale, modified Rodnan skin score (mRSS), autoantibodies, and esophageal diameters on HRCT in patients with SSc. Fifty patients were enrolled in the study. Patients with SSc-ILD had lower diaphragmatic mobility in deep breathing than patients without ILD. The results demonstrated negative correlations between diaphragmatic mobility and mMRC, mRSS, anti-Scl-70 antibodies, esophageal diameters on HRCT, and a positive correlation with lung function. Patients with SSc who experience dyspnea should be evaluated for diaphragmatic dysfunction for accurate symptom phenotyping and personalized pulmonary rehabilitation treatment.

Keywords: computed tomography; diaphragm; interstitial lung disease; lung function tests; systemic sclerosis; ultrasound.

Figure 1

A study outline describing the different parameters evaluated in the patient groups, as well as the different diagnostic modalities used in the study. SSc-ILD—systemic sclerosis-associated interstitial lung disease, mMRC—Medical Research Council dyspnea scale, DLCO—lung diffusing capacity for carbon monoxide, HRCT—high-resolution computed tomography, FRC—functional residual capacity, TLC—total lung capacity.