What is Chronic obstructive pulmonary disease?

Chronic obstructive pulmonary disease

What is chronic obstructive pulmonary disease (COPD)?

COPD is a lung disease that's usually caused by smoking. If you have a bad cough that never seems to go away, and if you get out of breath without doing very much, you may have this condition.

This disease is also known as

chronic bronchitis
Your doctor may say that you have chronic bronchitis if you have a cough that brings up phlegm, if it lasts for three months or more, and you have had it twice in two years. Smoking is a common cause of chronic bronchitis.

chronic bronchitis,

emphysema
Emphysema is a long-term disease of the lungs. The walls of the air sacs (alveoli) in the lungs become thin and less elastic. This makes it harder for oxygen to get in your blood and carbon dioxide to get out of your body. It makes you cough and feel short of breath. Smoking is the most common cause of emphysema.

emphysema or chronic obstructive lung disease.

Smoking is the main cause of COPD.

If you have COPD and you smoke, the best thing you can do is quit smoking.

This can help slow down how quickly the disease gets worse. (To learn more, see Why stop smoking?)

You can also take drugs to help you breathe more easily, and do exercises to make you stronger and more fit.

If you're underweight, eating well so that you gain weight also can help.

Key messages for people with COPD

Smoking is the main cause of COPD.
If you have a smoker's cough or get out of breath easily, you could have COPD.
You can get COPD even if you quit smoking some years ago.
There are treatments that can help you breathe more easily and live a more active life.
If you stop smoking, it will slow down how quickly your lungs get worse.

How your lungs work

To understand what happens in COPD and how to treat it, it helps to know something about your lungs.

When you breathe in, air goes into your lungs through your windpipe.

Your lungs are in the center of your chest, behind your ribs.

They are like two spongy, stretchy bags that fill up with air when you breathe in and empty when you breathe out.

When you take a breath, air travels down your windpipe and goes into your lungs.
The air passes into your lungs through a network of thin tubes.
These tubes are lined with fine hairs (called cilia) that help to push the air through the lungs. The hairs also help to sweep tiny specks of dust or dirt and germs out of your lungs.
The lungs make small amounts of a thick fluid, called mucus. It keeps the airways moist and helps get rid of dirt and germs.
The air you breathe in goes into tiny sacs at the end of each airway. Your doctor may call these sacs alveoli.
Each little sac is covered with tiny blood vessels. Oxygen from the air passes through the wall of the air sac and into the blood vessels.
The blood carries the oxygen all around your body. Oxygen is released into your body's tissues to be used as food. After your tissues use the oxygen, waste gases pass back to the blood.
The blood returns to your lungs with these waste gases. The gases move through the air sacs and back into your lungs. These are gases that your cells don't need any more, mainly carbon dioxide. When you breathe out, you get rid of these gases.

What happens in COPD

If you have COPD, your lungs are damaged, usually by cigarette smoke. Sometimes, but not very often, people get COPD from breathing in harmful chemicals at work or they inherit a disease from their family. (See Risk factors for COPD for more about the things that can lead to COPD.)

This is how the poisons in cigarette smoke and in other chemicals damage people's lungs.

Source:
Honig HG, Ingram RH.
Chronic Bronchitis, emphysema and airways obstruction.
In: Braunwald E, Fauci AS, Kasper DL, et al. Harrison's principles of internal medicine. 15th edition. McGraw-Hill, New York, U.S.A.; 2001.

They irritate the airways in the lungs and make them produce more mucus.
They stop the tiny hairs in the airways (cilia) from working properly. This means mucus stays trapped in the lungs instead of being forced out when you cough. Too much mucus in your airways makes it hard to breathe.
They make the walls of the airways swell and get thicker. When this happens, the airways get narrower. This makes it harder to breathe.
They damage the walls of the small sacs in the lungs that hold air (the alveoli). Less oxygen can get through the walls and into your blood. When you don't have enough oxygen in your blood, you get out of breath and tired faster.

There are two types of COPD: chronic bronchitis and emphysema. Some people with COPD have just chronic bronchitis, others have just emphysema. Many people have both.

In chronic bronchitis, the airways get clogged with mucus, and that's why it's hard to breathe. See Chronic bronchitis to learn more.

In emphysema, the air sacs lose their stretchiness and get damaged permanently, so they can't expand and contract well. The air gets trapped in the air sacs. See Emphysema to learn more.

Why me?

Things that increase your chance of getting a disease are called risk factors. The main risk factor for COPD is smoking, but there are other risk factors as well, including air pollution, infection, your genes and possibly your job. To learn more, see Risk factors for COPD.

Sources for the information on this page:

Honig HG, Ingram RH.Chronic Bronchitis, emphysema and airways obstruction.In: Braunwald E, Fauci AS, Kasper DL, et al. Harrison's principles of internal medicine. 15th edition. McGraw-Hill, New York, U.S.A.; 2001.

This information was last updated on Mar 06, 2009

This information is for educational use only, and is not a substitute for prompt professional medical advice. Readers should always consult a physician or other professional for advice and treatment.
© BMJ Publishing Group Limited 2009. All rights reserved.

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