Emphysema

Definition:

A lung disease involving damage to the air sacs (alveoli). The lungs become less able to expand and contract (loss of elasticity). The air sacs are unable to completely deflate (overinflation) and are therefore unable to fill with fresh air for adequate ventilation.

Causes, incidence, and risk factors:

Cigarette smoking is the major cause of emphysema. Tobacco smoke and other pollutants are thought to cause the release of chemicals within the air sacs of the lung that damage the walls of the air sacs. The damage becomes worse over time, affecting the exchange of oxygen and carbon dioxide in the lungs.

A substance called alpha-1 antitrypsin may protect against the damage. People with alpha-1 antitrypsin deficiency are at a higher risk for severe disease. The incidence is 2 out of 1,000 people.

Emphysema in children is caused by congenital abnormalities of the lung and alpha-1 antitrypsin deficiency.