ABSTRACT
Chronic obstructive pulmonary disease (COPD) represents the spectrum of lung disease that includes chronic bronchitis and emphysema, previously called chronic obstructive airways disease, and is characterized by chronic, non-reversible airways obstruction. Chronic bronchitis is defined as a cough on most days, for at least 3 consecutive months per year, for at least 2 years. Emphysema is defined as the destruction and enlargement of airways distal to the terminal bronchioles. It is therefore a pathological rather than a clinical diagnosis.
