Chronic Obstructive Pulmonary Disease I: Introduction

Chronic obstructive pulmonary disease is a common, preventable, and treatable respiratory disorder characterized by persistent symptoms and progressive airflow limitation. This limitation results from a combination of small-airway disease (obstructive bronchiolitis) and parenchymal destruction (emphysema), both driven by chronic inflammation from exposure to harmful particles or gases.

The disease includes two main pathological entities: emphysema, marked by destruction of alveolar walls and loss of elastic recoil, and chronic bronchitis, defined by chronic cough and sputum production due to airway inflammation and mucus hypersecretion. Although distinct in origin, these processes often coexist and together contribute to the clinical presentation of COPD.

Etiology

COPD develops gradually through interactions between environmental exposures, host factors, and genetic predisposition.

• Tobacco smoke is the leading cause, including cigarette, pipe, cigar, and second-hand smoke exposure.
• Occupational hazards, such as long-term exposure to dust (e.g., silica, cotton) and chemical fumes, also contribute.
• Air pollution, especially exposure to biomass fuels in poorly ventilated homes, is a major cause in low-income settings, while urban pollution adds further risk.
• Early-life factors, including recurrent infections, poor lung development from prematurity, or childhood asthma, increase susceptibility later in life.
• Genetic factors, particularly alpha-1 antitrypsin deficiency, predispose individuals to early emphysema due to unopposed elastase activity.
• Socioeconomic factors also influence risk through environmental exposure, healthcare access, and nutrition.

Overall, COPD results from cumulative exposure and individual susceptibility, leading to progressive lung damage.