Chronic obstructive pulmonary disease (COPD) refers to two lung diseases that are closely related: emphysema and chronic bronchitis. Although these diseases often occur together, you may have symptoms more characteristic of one than the other. In both conditions, airflow out of the lungs is restricted, making breathing very difficult.

Up to 90% of COPD cases are caused by smoking, and smokers are 10 times more likely to die from the disease. Frequent lung infections and exposure to certain industrial chemicals can also cause COPD, and some cases are related to genetic abnormalities. Approximately 14 million Americans have COPD, which causes about 120,000 deaths per year. Although the changes in lung tissue differ between the two diseases, the causes and treatments are similar.

Chronic Bronchitis

Chronic Bronchitis

© 2008 Nucleus Medical Art, Inc.

Chronic bronchitis is characterized by inflamed airway tissue and excessive mucus production. This leads to a persistent, productive cough that lasts for several months each year. Sometimes the large and small airways of the lungs become narrowed, and the lining of the passageways may become scarred. This makes it hard to move air in and out of your lungs, resulting in shortness of breath. Over 12 million Americans have chronic bronchitis.

Emphysema

Emphysemic Lung

© 2008 Nucleus Medical Art, Inc.

In emphysema, the walls between the tiny air sacs in the lungs lose their ability to stretch, and they become weakened and break. As the lung tissue becomes less elastic, air is trapped inside the air sacs, and the exchange of oxygen and carbon dioxide is impaired. Nearly three million Americans have emphysema.