Small airway disease (SAD) is associated with respiratory symptoms and relevant for therapy in early COPD

Background: SAD is common in patients with COPD. Occurring early in the course of the disease, it is frequently missed by currently used diagnostic tests. Multiple breath washout (MBW) testing detects ventilation heterogeneity (VH) while oscillometry (OS) assesses peripheral obstruction, both associated with SAD. We therefore set out to evaluate the presence and symptoms of SAD in patients with early COPD. Methods: We prospectively evaluated 26 patients (FEV1 77±19% pred., 88% GOLD I/II). In an 8-week cross-over design, the effect of dual bronchodilatation (tiotropium/olodaterol, T/O) on lung function and symptoms (CAT) was compared to monotherapy (formoterol). Lung function was assessed by…