ABSTRACT

Chronic obstructive pulmonary disease (COPD) usually develops after prolonged exposure to inhaled noxious gases. In contrast to chronic bronchitis, emphysema is a "pathological entity" characterized by permanent nonreversible destruction of airspaces located distal to the terminal bronchiole. This destruction leads to airspace enlargement and decreased alveolar-capillary contact area. In emphysema, the main symptom is shortness of breath, which is usually progressive and can lead to exercise intolerance. The bronchial mucosa of patients with emphysema is characterized by epithelial cell metaplasia without thickening of the basal membrane. Inflammatory and structural changes observed in small airways and lung parenchyma of emphysema patients are the most important contributing factors to airflow obstruction and decline in lung function. Early airway closure during forced expiration also contributes to increasing total lung capacity (TLC) and residual volume (RV). This chapter discusses mechanisms involved in the pathogenesis of COPD.