Emphysema << `ehm` fuh SEE muh >> is a lung disease in which patients have difficulty breathing, especially when they exhale. Emphysema is one of the two main forms of chronic obstructive pulmonary disease (COPD). The other is chronic bronchitis (see Bronchitis). Chronic obstructive pulmonary diseases are characterized by blockage of the airflow—that is, the ability to force air in or out of the lungs.
Chronic obstructive pulmonary diseases are a major cause of death in many countries. An estimated 125,000 Americans die from these diseases each year. Cigarette smokers are at least 12 times more likely than nonsmokers to get the diseases. Symptoms usually do not appear until about the age of 50. The diseases affect men and women equally.
How emphysema affects breathing.
When fresh air is inhaled, it is carried through the airways to small air sacs, called alveoli, in the lungs. The walls of these air sacs contain a network of tiny blood vessels called pulmonary capillaries. As the blood in the pulmonary capillaries moves along the walls of the air sacs, oxygen from the inhaled air leaves these alveoli and enters the blood. At the same time, carbon dioxide moves from the blood into the alveoli. The oxygen in the blood is distributed to tissues throughout the body by the arteries. Carbon dioxide from the alveoli is carried through the airways to the nose and mouth and then out of the body when a person exhales. See Respiration.
Emphysema destroys the walls of air sacs, including the pulmonary capillaries. Because a healthy adult has several hundred million air sacs, this process may occur for many years before a person suffering from emphysema experiences any difficulty breathing. As the disease progresses, the alveolar walls with their capillaries are destroyed. This results in obstruction of airways because the alveolar walls help hold small airways open. It also results in the formation of large, inefficient air spaces that trap air, containing carbon dioxide, inside the lung. The lung begins to lose elasticity and becomes overinflated as more air is inhaled and trapped in the air spaces. Thus, emphysema disrupts the flow of carbon dioxide from the body and deprives body tissues of needed oxygen.
Symptoms
of emphysema include difficulty in breathing, especially during exhalation; shortness of breath; an enlarged chest; and a bluish skin color resulting from a less-than-normal amount of oxygen in the blood. Emphysema patients often suffer from frequent colds and lung infections. Some also develop serious heart disease over time.
Diagnosis.
Physicians diagnose COPD using tests of lung function called spirometry. Patients with COPD often have larger lung volume because they have difficulty emptying their lungs by exhaling. Physicians can also measure the diffusion capacity of the lungs. Diffusion capacity is a measure of how well oxygen moves from the lungs into the bloodstream. Lung tissue damaged by emphysema shows reduced diffusion capacity.
Treatment.
Emphysema cannot be cured, but treatment may help reduce further lung damage. Emphysema patients should avoid cigarette smoking and air pollution. They should receive a flu shot each year and promptly treat recurrent colds and infections. Many patients are helped by drugs, physical therapy, special breathing techniques, and by breathing oxygen-enriched air.
