Correlation analysis of chest HRCT quantitative parameters, exhaled nitric oxide, and pulmonary function in patients with chronic obstructive pulmonary disease

This study aimed to explore the multidimensional associations among airway inflammation, structural remodeling, and pulmonary function impairment in patients with chronic obstructive pulmonary disease (COPD). We enrolled 115 patients in the acute exacerbation of COPD (AECOPD) group, 89 stable COPD patients, and 70 healthy controls. High-resolution computed tomography (HRCT) quantitative indices were compared among the three groups. The AECOPD and COPD groups were further analyzed to assess the correlations between derivative parameters, exhaled nitric oxide (eNO), and pulmonary function. Compared with stable COPD patients, those with AECOPD presented increased wall thickness normalized to body surface area (WT/BSA) and a greater ratio of airway wall thickness to accompanying pulmonary artery diameter (WT/PA) in the right upper lobe apical segment (RB1). Both the RB1 segment and the right upper lobe subapical segment (RB1a) in the AECOPD group presented elevated WT/BSA values, airway wall areas normalized to the BSA (WA/BSA), ratios of airway wall thickness to the luminal diameter (TDR), and WT/PA values compared with those of healthy controls. Nitric oxide concentration in exhaled breath at a flow rate of 200 ml/s (FeNO200) and concentration of alveolar nitric oxide (CaNO) showed positive correlations with airway remodeling indices but inverse correlations with z-scores of forced expiratory volume in 1 s (FEV1, z−scores), FEV1 ratio Forced vital capacity (FEV1/FVC, z−scores), forced expiratory flow at 75% of forced vital capacity (FEF75, z−scores), and maximal mid-expiratory flow (MMEF,z−scores). Similarly, WT/BSA and WT/PA in RB1/RB1a, as well as the percentage of low-attenuation areas below − 950 Hounsfield units (LAA− 950%) are negatively associated with FEV1/FVC, z−scores, FEF75, z−scores, and MMEF, z−scores. Compared with stable disease, small airway remodeling is more pronounced during COPD exacerbations. FeNO200, and CaNO may serve as a biomarker for assessing small airway remodeling and pulmonary function impairment in COPD patients.