Correlation of Ultrasound-assessed Muscular Bulk with Degree of Airflow Limitation in Patients with Chronic Obstructive Pulmonary Disease

Background: Chronic obstructive pulmonary disease (COPD) is known for its numerous extrapulmonary manifestations, among which muscle dysfunction occupies an eminent position. Worth noting, muscle dysfunction in COPD patients isn’t limited to the diaphragm or respiratory muscles, but it extends to other skeletal muscles, as well. Aim of the work: To investigate the correlation of ultrasonographically assessed bulk of the diaphragm, pectoralis major and rectus femoris muscles with the degree of COPD severity (airflow limitation). Patients and methods: This cross-sectional research has been performed on sixty clinically stable COPD patients, divided into 4 equal subgroups regarding the severity of the disease. Moreover, twenty healthy volunteers, constituting a control group, were also enrolled. Results: Diaphragmatic thickness (DT) at functional residual capacity (FRC), diaphragmatic thickening fraction (DTF), total lung capacity (TLC), pectoralis major thickness (PMT), rectus fermoris thickness (RFT) and rectus femoris cross-sectional area (RFCSA) showed statistically highly significant positive correlations with arterial partial pressure of oxygen (PaO2), oxygen saturation (SO2), 6-minute walk distance (6MWD) and forced expiratory volume in the first second (FEV1). Whereas they exhibited significant negative correlations with arterial partial pressure of carbon dioxide (PaCO2), modified Medical Research Council (mMRC) dyspnea scale, number of exacerbations (last year), BODE index and COPD assessment test (CAT) score. Conclusion: Ultrasonographic measurements of diaphragm, thoracic and lower limb muscles in COPD patients correlate positively with the level of oxygenation, exercise tolerance and FEV1, while they correlate negatively with hypoventilation, degree of dyspnea, prognosis, frequency of exacerbations (last year) and CAT score.