Post COVID-19 Condition Patients with Dyspnea Show Diaphragm Dysfunction in Sonographic Imaging – a Prospective Observational Study

Abstract Around 6.2% of patients report symptoms as fatigue, muscle pain and dyspnea more than three months after SARS-CoV-2 infection, defined as post COVID-19 condition (PCC). Non-hospitalized patients with PCC often show normal pulmonary functioning tests and imaging but suffer from respiratory symptoms. On clinical examination, PCC with dyspnea show signs of diaphragmatic dysfunction. The study aimed to objectively visualize and quantify the diaphragmatic function using sonographic parameters in PCC patients with and without dyspnea. Adult PCC patients were prospectively assessed for dysfunctional breathing and diaphragmatic stiffness using sonographic imaging. Multiparametric sonography evaluated diaphragm thickness, mobility, stiffness and elasticity in different breathing cycles using B-mode imaging, M-mode and quantitative shear wave elastography. PCC patients were stratified into two groups with and without dyspnea. Fifty-four post-COVID patients were assessed, of whom n=24 (44.4%) reported dyspnea and presented dysfunctional breathing, while 30 PCC without dyspnea served as control. PCC with dyspnea compared to PCC without dyspnea showed a less deep first breath (5.8 mm vs. 6.5 mm, p=0.044), reduced diaphragm thickness on inspiration (3.4 mm vs. 3.9 mm, p=0.030), as well as less increase of diaphragmatic elasticity (108% vs. 146%; p=0.027) and diaphragmatic stiffness (40% vs. 53%; p=0.022) during inspiration. Diaphragm dysfunction as a possible origin of dyspnea in PCC can be assessed and objectively quantified using multiparametric sonography and may help evaluate therapeutic interventions that are otherwise overlooked.