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Emphysema?The Gale Encyclopedia of Science,?2008Top of FormBottom of FormEmphysema is a lung disease that results in the destruction of air sacs. It is brought about almost exclusively by smoking. In the past, the majority of its victims were male, but the disease has become more common in women as more women become smokers.Emphysema is also called chronic obstructive pulmonary disease (COPD). Chronic bronchitis (inflammation) of the air tubes leading into the lungs is linked to the development of emphysema, and may in fact represent the same disease.Although?emphysema?is closely linked to?smoking, a few patients--fewer than 1% of cases--have a genetic lack of an enzyme, called alpha-1-antitrypsin, that leads to the development of the disease. Alpha-1-antitrypsin normally protects the elastic fibers in the walls of the small air sacs in the lungs. If the enzyme is not present, the air sacs are vulnerable to damage by cigarette smoke, chemical fumes, dust, and other substances that are inhaled.The target of emphysema are the lungs; two large, spongy sacs that lie on each side of the chest (thorax), separated by the heart. The right lung is divided into three lobes and the left into two lobes. Each lobe is further divided into two to five segments, which are divided by a membrane. Each segment is supplied with incoming air by a branching tube called a bronchiole. The bronchioles are connected to larger and larger bronchioles, which, in turn, connect to large tubes called bronchi. Each individual bronchus from each lung merge into a single tube called the trachea, which connects with the upper part of the respiratory system leading to the nose.The lungs are made up of hundreds of millions of tiny air sacs called alveoli. Each alveolus is surrounded by tiny blood vessels, and it is here that the carbon dioxide from the body is exchanged for fresh oxygen that has been inhaled into the lungs.During respiration, the diaphragm, which forms the floor of the thorax, moves downward toward the abdomen and draws fresh air, inflating the lungs. When the diaphragm relaxes, it resumes its resting domed shape, which forces the air, now heavy with carbon dioxide, out of the lungs. The cycle then is repeated for the next breath. In the case of lung disease such as emphysema the declining number of alveoli means that less oxygen is absorbed into the blood with each breath. At first this may not be a discomfort, especially when the individual is at rest, but with exercise or as more of the alveoli are destroyed the patient will notice an increasing difficulty in getting a breath, will tire easily, and will gasp for air even while resting.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 lungpower 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.There is no treatment that will reverse emphysema. The alveoli cannot be healed to restore normal respiration. Some patients may need to take medications to keep the bronchi as open as possible. Also, many emphysema patients require oxygen infusion to provide sufficient oxygen for the body functions. Emphysema patients are advised to avoid people who have colds or pneumonia or other contagious diseases. Also, avoiding cold air is advisable, as the air will constrict the bronchi even more and increase the effort required to breathe. The patient should also avoid dusty areas, paint fumes, automobile exhaust, and other lung irritants. Above all, when the early symptoms of emphysema appear, the individual should stop smoking. This will prevent further lung damage and ease the burden of respiration. Continued cigarette smoking will worsen the condition and lead to an earlier death.Special breathing techniques and respiratory exercises can strengthen the diaphragm, abdominal muscles, and chest muscles to make breathing easier. Oxygen tanks can be installed in the home and small, portable oxygen tanks can be obtained for travel. These may be so small that they can hang on the belt, or if larger supplies are needed, small packs containing tanks can be worn on the back or pushed in a cart.Individuals who have severe emphysema may be helped by a lung transplant. Until recently efforts to transplant only the lungs were met with little success. Now, however, improvement in medications and technology allow successful lung transplants.Individuals who have a genetic lack of alpha-1-antitrypsin may benefit from enzyme replacement therapy, in which a function version of the enzyme is infused into the lungs. It is necessary that the infusion be started in the early stages of the disease. Repeated infusions will be needed during the patient's lifetime, since the enzyme has a limited functional lifetime. ................
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