Emphysema

Not all smokers develop emphysema, but those who develop the condition become progressively worse over a period of years. Some scientists believe that cigarette smoke neutralizes the protective effects of alpha-1-antitrypsin so that the harmful elements in the smoke can damage the alveolar walls. This has yet to be proved, however.

Once destroyed, the alveoli cannot be repaired or replaced. Continued destruction of these air sacs leads to open, nonfunctional areas in the lungs, reducing the area through which oxygen and carbon dioxide can be exchanged.

In emphysema, the bronchi and bronchioles also become constricted, interfering with the free flow of air in and out of the lungs. The patient finds it harder and harder to breathe and will find himself straining to force air in and out of the lungs. The initial symptoms of emphysema are shortness of breath and a mild cough, both of which become more severe as the disease progresses.

In advanced stages of the disease, the patient will develop a barrel chest from the strain of breathing and probably will need to breathe pure oxygen with the aid of a machine. He or she will no longer have the lung power to blow out a candle held only a few inches from the mouth. The emphysema patient also is at increased risk of worsening the disease by catching pneumonia or even a common cold.