Chronic Obstructive Pulmonary Disease

Chronic Obstructive Pulmonary Disease (COPD) is a progressive respiratory disorder characterized by persistent airflow limitation that is usually irreversible, associated with an abnormal inflammatory response of the lungs to noxious particles or gases.

Definition

Epidemiology

Affects over 250 million people worldwide
Third leading cause of death globally
Prevalence increases with age, mostly in individuals >40 years
Higher prevalence in smokers and individuals exposed to occupational pollutants
More common in men historically, but increasing prevalence in women

Etiology

Cigarette smoking (primary cause in most cases)
Long-term exposure to environmental pollutants (biomass fuel, dust, chemicals)
Occupational exposure to dust, fumes, or chemicals
Alpha-1 antitrypsin deficiency (genetic predisposition)
Severe or recurrent respiratory infections in childhood
Asthma-COPD overlap in some patients
Other genetic and epigenetic factors influencing susceptibility

Pathophysiology

Chronic inflammation of the airways, parenchyma, and pulmonary vasculature
Structural changes: airway remodeling, mucus hypersecretion, alveolar destruction (emphysema)
Progressive airflow obstruction due to loss of elastic recoil and airway narrowing
V/Q mismatch leading to hypoxemia
Chronic inflammation causing systemic manifestations
Exacerbations often triggered by infections or environmental factors
Progressive decline in lung function over time