Small airways disease in chronic obstructive pulmonary disease

Small airway disease (SAD) represents a common and critical feature of Chronic Obstructive Pulmonary Disease (COPD). Introduced in the '60s, SAD has gradually gained increasing interest as assessment methodologies have improved. Chronic exposure to smoking and noxious particles or gases induces inflammation and remodeling, leading to airway obstruction and SAD, eventually resulting in complete airway loss.

A literature search up to June 2024 was performed in PubMed to identify articles on SAD and airway diseases mainly COPD, but also to the extent that it seemed relevant in the uncontrolled/severe asthma field, where SAD is better studied. We provide clinicians and translational scientists with a comprehensive analysis of the existing literature on SAD in COPD, concentrating on the underlying pathophysiological mechanisms, diagnostic techniques, and current pharmacological approaches targeting airflow obstruction in small airways.

Small airways are the primary site for the onset and progression of airflow obstruction in patients with COPD, with significant clinical consequences associated with poor lung function, hyperinflation, and impaired quality of life. The early identification of individuals with subclinical SAD may allow us to prevent its further progress from airway loss and potential development of emphysema and choose the appropriate therapeutic approach.