Overview of Emphysema
Emphysema is a type of lung disease classified as a chronic obstructive pulmonary disease (COPD). It is an irreversible, progressive condition characterized by inflammation and reduced airflow in the lungs. Emphysema often occurs in combination with chronic bronchitis. The most common cause is cigarette smoking.
Respiratory System Anatomy
The lungs are the major organs of the respiratory system. During inhalation, the body takes in air through the nose and mouth. This oxygen-rich air travels through passageways in the throat (i.e., pharynx, larynx), through the windpipe (trachea), through the bronchial tree (i.e., bronchi, bronchial tubes, bronchioles), and into air sacs (called alveoli) in the lungs.
In the alveoli, oxygen is transferred to oxygen-depleted red blood cells in blood vessels called capillaries. The oxygen-rich blood returns to the heart and is pumped throughout the body.
During exhalation, carbon dioxide (CO2) is transferred from the blood into space between the air sacs (called alveolar space) and is exhaled from the body.
There are approximately 3,000,000 alveoli in the lungs. These tiny, thin-walled air sacs are lined with a substance (called surfactant) that reduces pressure within the alveoli and prevents them from collapsing during breathing. Other substances in the walls of the alveoli (e.g., elastin, collagen) allow the air sacs to "shrink" during exhalation.
Emphysema results from permanent enlargement of the alveoli and damage to the walls of the air sacs. The walls of the alveoli lose the ability to expand and contract properly (similar to an overstretched balloon), the air sacs become weak, and air flow in the lungs is reduced. Emphysema affects the body's oxygen supply and makes breathing difficult.
Incidence and Prevalence of Emphysema
According to the American Lung Association, more than 3.1 million people in the United States have been diagnosed with emphysema. Emphysema and other types of COPD are the fourth leading cause for death in the United States. The condition occurs slightly more often in men (about 52 percent of cases) than women; however, the mortality rate is higher in women. Emphysema is more common in Caucasians than African Americans.
More than 90 percent of patients who have emphysema are over the age of 45 at the time of diagnosis. The disease is most common between the ages of 60 and 80.
Approximately 100,000 people in the United States have an inherited form of the condition called alpha-1 antitrypsin deficiency emphysema or familial emphysema. This disease, which is more common in people of northern European descent, often causes symptoms between the ages of 32 and 40.