title: Pathophysiology of the small airways in chronic obstructive pulmonary disease.
abstract: Chronic obstructive pulmonary disease (COPD) is characterized by a persistent airflow limitation that is usually progressive and associated with an enhanced chronic inflammatory response in the airways and the lung to noxious particles or gases. From a pathological point of view, COPD is characterized by two distinct and frequently coexisting aspects: small airway abnormalities and parenchymal destruction (or emphysema). When pathological changes are localized in lung parenchyma, they will contribute to airflow limitation by reducing the elastic recoil of the lung through parenchymal destruction, as well as by reducing the elastic load applied to the airways through destruction of alveolar attachments. Conversely, when pathological changes involve the small airways, they will contribute to airflow limitation by narrowing and obliterating the lumen and by actively constricting the airways, therefore increasing the resistance. In this article we will review the structural abnormalities in small airways and their relationship with the disordered pulmonary function in COPD, in the attempt to disentangle the mechanisms contributing to the development and progression of airflow limitation in smokers. We will start by describing the normal structure of the small airways, and then observe the main pathological alterations that accumulate in this site and how they parallel pulmonary function derangement.
authors.affiliation: Department of Cardiac, Thoracic and Vascular Sciences, Respiratory Diseases Clinic, University of Padova, Padua, Italy.
authors.forename: Simonetta
authors.initials: S
authors.lastname: Baraldo
authors.forename: Graziella
authors.initials: G
authors.lastname: Turato
authors.forename: Marina
authors.initials: M
authors.lastname: Saetta
mesh_terms: D000393:Air Pollutants / Q000009:adverse effects / Q000493:pharmacokinetics; D015824:Blood-Air Barrier / Q000503:physiopathology; D055745:Bronchioles / Q000033:anatomy & histology / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology; D018450:Disease Progression; D006801:Humans; D019570:Inhalation Exposure / Q000009:adverse effects*; D029424:Pulmonary Disease, Chronic Obstructive / Q000209:etiology / Q000473:pathology / Q000503:physiopathology; D011656:Pulmonary Emphysema / Q000209:etiology* / Q000473:pathology / Q000503:physiopathology; D012123:Pulmonary Ventilation / Q000502:physiology; D012720:Severity of Illness Index; D012907:Smoking / Q000009:adverse effects*
chemical_list: D000393:Air Pollutants