Assessing Chronic Obstructive Pulmonary Disease Severity through Diaphragmatic Ultrasonography: A Comprehensive Exploration

<bold>Introduction:</bold> The dysfunction of the diaphragm emerges as a primary pathophysiological mechanism in chronic obstructive pulmonary disease (COPD) and is likely linked to its progression. <bold>Objective:</bold> We sought to explore the relationship between diaphragmatic ultrasonography (DU) and the severity of COPD. <bold>Methods:</bold> We conducted a prospective cross-sectional study involving consenting patients diagnosed with stable COPD according to the GOLD 2023 guidelines at our pulmonology department from September to December 2023. We excluded patients with comorbidities that could affect diaphragmatic function. DU was used to assess parameters such as thickening fraction (TF), diaphragmatic excursion (DE), and diaphragm force reserve ratio during both tidal breathing and maximum volitional effort. <bold>Results:</bold> Sixty male patients were included. The mean age was 62,78 ± 7 years. The mean TF was 28.89 %. The mean DE was 3.3 (2.6–4.1) cm. Thirty patients were of Group E. DEmax was lower in this group of patients (p<10^-3). TF was twice as high in patients who were frequent exacerbators. Diaphragm force reserve ratio (DFRR) was lower in patients of Group B who experienced desaturation during the six-minute walk test with a walking distance < 50% of the theoretical value and of Group E. A significant correlation was found between DFRR and Body mass index (r=-0,378), airflow obstruction (r=0,457), hospitalisation for acute exacerbation of COPD and CAT score (r=0.680). Remarkably, DFRR predicted the risk of chronic respiratory impairment at a cut-off value 0.33 with a specificity of 89% and a sensitivity of 92%. <bold>Conclusion:</bold> These results imply that DU could play a significant role in tailoring COPD for each patient.