Exploring the Relationship between Physical Frailty, Diaphragm Muscle Function, and Chronic Obstructive Pulmonary Disease Severity

<bold>Introduction:</bold> Frailty, linked to decreased resilience, is common in COPD. Recognizing it is vital for better care. <bold>Objective:</bold> To elucidate the relationship between physical frailty and respiratory muscle function in COPD patients. <bold>Methods:</bold> We conducted a prospective cross-sectional study including 60 consenting patients diagnosed with stable COPD according to the GOLD 2023 guidelines, at our pulmonology department from September to December 2023. Exclusion criteria included comorbidities that could affect diaphragmatic function. Each participant underwent a comprehensive assessment, including respiratory functional testing, timed up and go (TUG) test , and diaphragmatic ultrasound to evaluate thickening fraction (TF), diaphragm thickness and impaired diaphragm muscle function. Patients were categorized into two groups: G1 (n=32) ; Patients with impaired diaphragm muscle function, and G2 (n=28): Patients with normal diaphragm thickness. <bold>Results:</bold> All patients were male, with a mean age of 62.7 ± 7 years. The mean TUG time was 20.3±2.7 seconds. No differences were observed between the two groups in terms of age and comorbidities. Patients of G2 showed significantly lower vital capacity, decreased Forced expiratory volume in the first second (FEV1), higher CAT scores, a mean TUG time exceeding 30 seconds, and a notably shorter 6-minute walk distance (6MWD; P < 10^-3) even after adjusting for relevant parameters. TF in G1 enhanced the predictive accuracy of desaturation during the 6MWT as evidenced by an improved AUC. <bold>Conclusion:</bold> Impaired diaphragm muscle function correlates with worsened frailty markers and lung function, underscoring the importance of addressing physical frailty in COPD care.