Chronic obstructive pulmonary disease (COPD) is a lung disease in which the lung is damaged, making it hard to breathe. In COPD, the airways-the tubes that carry air in and out of your lungs-are partly obstructed, making it difficult to get air in and out.
Cigarette smoking is the most common cause of COPD. Most people with COPD are smokers or former smokers. Breathing in other kinds of lung irritants, like pollution, dust, or chemicals over a long period of time may also cause or contribute to COPD.
The airways branch out like an upside-down tree, and at the end of each branch are many small, balloon-like air sacs. In healthy people, each airway is clear and open, the air sacs are small and dainty, and both are elastic and springy. When you breathe in, each air sac fills up with air, like a small balloon, and when you breathe out, the balloon deflates and the air goes out. In COPD, the airways and air sacs lose their shape and become floppy. Less air gets in and less air goes out because:
•The airways and air sacs lose their elasticity (like an old rubber band)
•The walls between many of the air sacs are destroyed
•The walls of the airways become thick and inflamed (swollen)
•Cells in the airways make more mucus (sputum) than usual, which tends to clog the airways.
COPD develops slowly, and it may be many years before you notice symptoms like feeling short of breath. Most of the time, COPD is diagnosed in middle-aged or older people, and is a major cause of death and illness throughout the world.
It is the 4th leading cause of death in the U.S. and the world.
There is no cure for COPD. The damage to your airways and lungs cannot be reversed, but there are things you can do to feel better and slow the damage to your lungs.
COPD is not contagious-you cannot catch it from someone else.
Other Names for COPD
•Chronic obstructive airway disease
•Chronic obstructive lung disease
In the U.S., COPD includes:
In the emphysema type of COPD, the walls between many of the air sacs are destroyed, leading to a few large air sacs, instead of many tiny ones (see How Do the Lungs Work). Then, the lung looks like a sponge with many large bubbles or holes in it, instead of a sponge with very even tiny holes. These few large air sacs have less surface area than the normal tiny ones for the exchange of oxygen and carbon dioxide. Poor exchange of the oxygen and carbon dioxide causes shortness of breath.
In chronic bronchitis, the airways have become inflamed and thickened and there is an increase in the number and size of the mucus-producing cells. This results in excessive mucus production, which in turn contributes to cough and difficulty getting air in and out of the lungs.