Emphysema is a chronic and serious disease that is characterized by severe shortness of breath. Damage to the lung tissue and the loss of elasticity in the lungs cause the changes that make breathing very difficult Figure 01. Under normal conditions, air enters the nose or mouth and travels down the air tube (trachea) to the main air passages (bronchi). These passages allow air to go into the right and left lungs. Each bronchus branches into smaller passages (bronchioles) and eventually into tiny air sacs (alveoli). It is through the alveoli that oxygen enters the bloodstream when we inhale and that carbon dioxide is expelled when we exhale.
Figure 01. How emphysema damages the lungs
Emphysema causes damage to the lungs that is irreversible. As air sacs are destroyed, the lungs become less able to transfer oxygen in the lungs for carbon dioxide in the bloodstream.
The lungs also lose their elasticity and the patient experiences great difficulty exhaling. This leads to over inflation of the lungs and very shallow breathing. The loss of elasticity results in lung enlargement. The enlarged areas are ineffective in eliminating carbon dioxide and in transferring oxygen from the air into the blood stream. Damage to the air sacs in the lungs not only results in difficulty breathing, but the heart also has to work harder to circulate blood through the lungs. All these changes make less oxygen available to the body.
Most people with this disease are men between 50 and 70 years of age who have been heavy smokers for most of their lives. However, as the rate of female smokers rises, the rate of emphysema among women will also increase. People with emphysema have permanently enlarged lung regions. Almost 44% of people with emphysema report that having this disease significantly affects their daily lives and limits their activities.
Emphysema develops very slowly. Shortness of breath during activity or exercise is usually the reason that prompts a person with this disease to see a doctor. Emphysema comes on very gradually—-usually after years of cigarette smoking. As the disease becomes worse, any amount of activity may cause difficulty breathing.
Smoking is the number one cause of emphysema. Smoking is responsible for 80% to 90% of all cases of emphysema. Environmental conditions, including air pollution containing sulfur dioxide and particulate matter or working with hazardous chemicals or substances can also contribute to emphysema.
An inherited, genetic disorder is responsible for causing emphysema in some patients. Deficiency in the protein AAT is an inherited disorder. AAT is necessary to prevent an enzyme (neutrophil elastase) from destroying another protein (elastin) that is an essential part of the connective tissue of the lungs. People with this form of emphysema generally develop the disease in their thirties and forties. There are approximately 50,000 to 100,000 people in the United States with AAT deficiency; 20,000 to 40,000 of these people will develop emphysema. People with AAT deficiency who smoke are at an increased risk for emphysema and for suffering severe consequences of the disease. Smoking can decrease the life span of someone with AAT deficiency by as much as 10 years.
Emphysema is classified according to the specific region of the lung that is affected by the disease. Emphysema is classified into two types:
- Centriacinar emphysema: The central or proximal parts of the acini are damaged. This type of emphysema accounts for 95% of all cases and is the type that is most often associated with smoking or environmental causes.
- Panacinar emphysema: The lower regions of the lung are damaged. The acini are uniformly enlarged. This type is most often associated with AAT deficiency.
The location of the disease may help determine whether smoking or AAT deficiency caused the disease. However, the cause of emphysema has little bearing on its outcome.
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