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emphysema (ĕmfĭsēˈmə), pathological or physiological enlargement or overdistention of the air sacs of the lungs. A major cause of pulmonary insufficiency in chronic cigarette smokers, emphysema is a progressive disease that commonly occurs in conjunction with chronic bronchitis. It is found predominantly in people over age 45, but a genetically based early-onset form also exists. Symptoms are difficulty in breathing, cough with thick sticky sputum, and a bluish tinge of the skin. Progressive disease can result in disability, and in severe cases heart or respiratory failure and death.
Cigarette smoking is the cause of most cases of emphysema. Tobacco smoke damages the lungs' alveoli, the tiny air sacs through which inhaled oxygen is transferred to the bloodstream and carbon dioxide is passed back to the lungs to be exhaled. The lungs become less elastic and breathing becomes increasingly difficult. The genetic form of emphysema occurs earlier in life (worsened by, but not dependent upon cigarette smoking). It is caused by a rare genetic deficiency of the protein alpha1-antitrypsin. In the absence of antitrypsin, which normally functions to protect the lungs from damage, the walls of the alveoli are attacked by chemicals released in alveoli in response to tobacco smoke and air pollutants.
Emphysematous lung damage is irreversible. Its progression can be slowed by giving up smoking. Treatment is aimed at increasing the functional capacity of the lungs and may include bronchodilators, administration of supplemental oxygen, or lung transplantation. Surgical removal of affected lung tissue (lung volume reduction surgery), aimed at allowing healthy areas of the lung room to function, is being studied for its effectiveness and safety. The genetic form is treated with supplemental antitrypsin administered by infusion or by a gene therapy technique that uses T cells (special immune cells that identify diseased or deformed cells) to deliver it to the desired cell sites.
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A pulmonary disorder characterized by overdistention and destruction of the air spaces in the lungs.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
1. a condition in which the air sacs of the lungs are grossly enlarged, causing breathlessness and wheezing
2. the abnormal presence of air in a tissue or part
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005