In Chronic Obstructive Pulmonary Disease (COPD) patients, the opportunity to carry out a thoracic high-resolution CT (HRCT) scan and to perform an incremental cardiopulmonary exercise test (CPET) increases the possibility to identify the different clinical features of disease. The aim of our study was to evaluate the relationships between HRCT metrics (on emphysema by low attenuation areas-LAA% and airways by wall area-WA%) and CPET variables related to the dynamic response to exercise in terms of elastic balance (Δ rest-to-peak IC/TLC) and ventilation capacity for carbon dioxide output (V_E/V_{CO2 slope} and V_E/V_{CO2 intercept}).

We prospectively enrolled COPD outpatients from the University Hospital of Parma. Data on anthropometrics characteristics, lung function, HRCT (LAA% and WA%) and CPET (Δ rest-to-peak IC/TLC, V_E/V_CO2 slope and V_E/V_{CO2 intercept}) were recorded.

Fifty-one mild to moderate COPD patients (66% males; median age 70 y; mean FEV₁ 56% of pred.) were enrolled in the study. LAA% demonstrated a significant correlation with Δ rest-to-peak IC/TLC and V_E/V_{CO2 slope} (r = 0.405, p = 0.005 and r = 0.453, p = 0.001, respectively), while WA% with V_E/V_{CO2 slope} (r = −0.333, p = 0.020). In multivariate regression models, after adjustment for oxygen uptake (peak V_O2) and physical capacity (peak workload), LAA was the only independent predictor of Δ rest-to-peak IC/TLC (β 0.774, SE 0.334, p = 0.025) and V_E/V_{CO2 slope} (β 0.155, SE 0.053, p = 0.005 and β 0.305, SE 0.123, p = 0.018, respectively). V_E/V_{CO2 intercept} was instead predicted from FEV₁ only (β −0.097, SE 0.042, p = 0.027).

In mild to moderate COPD patients, emphysema (LAA) and airways metrics (WA) have close relationships with the different characteristics of ventilatory response to exercise. In particular, we were able to show that LAA is an independent predictor of exercise-induced Δ rest-to-peak IC/TLC and V_E/V_{CO2 slope}.