By Douglas W. Mapel, MD, MPH, Lovelace Respiratory Research Institute

Chronic Obstructive Pulmonary Disease (COPD) is the clinical term physicians use to describe the two most common non-cancerous lung diseases: chronic bronchitis and emphysema. Most persons who smoke develop some degree of both disorders, and because the symptoms and effects of both diseases are similar, physicians tend to use the term COPD instead of the two more specific terms.

COPD is a remarkably common and growing problem: It is currently the fourth leading cause of death in the United States, and among the top ten causes of death, it is the only one projected to increase over the next decade.

Chronic bronchitis is a disease of the lung airways. Persons who have chronic bronchitis usually note symptoms including a chronic productive cough, shortness of breath with exertion, and frequent respiratory infections. They may also experience episodes of wheezing and chest tightness associated with exercise or exposure to cold air. On autopsy, the lung airways show evidence of chronic irritation, including enlarged mucus glands, thickened airway muscles, and accumulations of inflammatory cells. The symptoms and pathologic findings of chronic bronchitis share many features with asthma, and the treatment of chronic bronchitis is similar to that of asthma.

Emphysema is a disease of the lung acini, the fleshy part of the lung that contain the millions of tiny air sacs where oxygen and carbon dioxide exchange takes place. In emphysema, the walls of the air sacs are gradually destroyed, resulting in a lung that is full of holes in a pattern similar to Swiss cheese. Because emphysema is a very slowly progressive process, patients may not be aware of any problem until more than half of their lung tissue is destroyed. Lung tissue is not able to regenerate itself, so these holes are permanent, as is the chronic shortness of breath experienced by emphysema patients. There is no specific treatment for emphysema, but the lung destruction does stop if the patient quits smoking.

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Last modified: 07/19/04