D'Arcy Little, MD, CCFP
York Community Services,
Toronto, and
Department of Family Medicine
Sunnybrook Campus of
Sunnybrook and Women's
College Health Sciences Centre,
Toronto, Ontario
Chronic Obstructive Pulmonary Disease (COPD) is a general term for a group of conditions characterized by some or all of the following features: a chronic cough, increased sputum production, shortness of breath, airflow obstruction, and impaired gas exchange. Unlike asthma, which is usually episodic and reversible, the major characteristics of COPD are that it is chronically progressive and irreversible. Under the umbrella of COPD, there are two major disease categories: chronic bronchitis and emphysema. Chronic bronchitis is clinically characterized by a productive cough, lasting three months of the year for at least two consecutive years. Pathologically, chronic bronchitis is characterized by mucus gland and airway smooth muscle hypertrophy. Emphysema is clinically characterized by dyspnea, although the other features mentioned above may also be present in various degrees. Technically, emphysema is a pathological diagnosis characterized by destruction of the air spaces distal to the terminal bronchioles (respiratory bronchioles, alveolar ducts and alveoli). It is worthwhile to note that it may not be clinically important, or useful, to categorize a patient as having either chronic bronchitis or emphysema.
