What Is Chronic Bronchitis - What Is Copd: Respiratory Health
Content provided by the Faculty of the Harvard Medical School
What is chronic bronchitis?
Chronic bronchitis is an inflammatory condition of the airways that causes a cough that brings up sputum. According to the formal definition, the cough occurs nearly every day for at least three months of the year for two consecutive years. In reality, doctors don't necessarily count the months or years when making a diagnosis. If your symptoms are ongoing and follow this general pattern, it's likely that your doctor will diagnose chronic bronchitis.
Unlike acute bronchitis, which is usually a viral infection that lasts several days or so, chronic bronchitis is not caused by infection. It develops when the bronchial tubes are irritated day after day, most often from tobacco smoke. In an effort to expel the irritants, the body mounts a defense that involves inflammation and swelling of the airways and a constant production of mucus. The inflammation narrows the airways, and the mucus obstructs them further. Like traffic crawling through a road that's partially blocked by construction, air moves more slowly in and out of your lungs. You may wheeze as you work hard to breathe, and you cough in an attempt to clear mucus from your airways.
Symptoms of chronic bronchitis
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Some people with chronic bronchitis also have episodes that feel like asthma attacks. These may be caused by bronchospasm, a sudden contraction of the airways that makes it difficult to breathe and may trigger a torrent of wheezing or coughing. Bronchospasm is characteristic of asthma, which is a separate illness from COPD (see "Chronic bronchitis or asthma?"). But if you have both chronic bronchitis and episodes of bronchospasm, your doctor may diagnose asthmatic bronchitis, a hybrid condition that has features of both chronic bronchitis and asthma. Doctors use many of the same medications to treat both conditions.
People with chronic bronchitis find it increasingly difficult to exercise and exert themselves in other ways. Some people experience swelling, particularly in the ankles and feet, because heart complications that sometimes occur with chronic bronchitis can cause fluid retention. You may gain weight because of this excess fluid. Difficulty breathing can decrease the oxygen level in your blood, causing your lips or the part of your fingertips under the nails to appear blue.
How is it different from lung cancer?Most people know that smoking causes lung cancer. But not everyone knows that COPD is an even more common result. Although both conditions are caused primarily by smoking, they are distinct diseases that cause different kinds of lung damage. As with other cancers, lung cancer is the uncontrolled growth of tumor cells. It occurs when cancer-causing agents known as carcinogens, which typically come from tobacco smoke, cause genetic mutations that trigger uncontrolled cell growth. When cells can't stop reproducing, they form tumors that can interfere with the normal function of organs. These cells can spread to other parts of the body, where they form more tumors in other organs. Chronic obstructive pulmonary disease, on the other hand, is not a form of cancer. It is the result of inflammation in the lungs, which triggers many physiological processes that damage the airways and degrade lung tissue. This damage makes it difficult to breathe and impedes the lungs' ability to deliver oxygen to the bloodstream. Both lung cancer and COPD may produce chronic cough. Shortness of breath is more typical of COPD than lung cancer, unless the lung cancer is relatively advanced. Coughing up blood may occur with either chronic bronchitis or lung cancer, so when a patient has this symptom, the doctor may need to do further evaluation to identify the reason for the blood. Survival rates are also quite different: People with COPD often live for many years, whereas those with lung cancer typically die within a few years of diagnosis. |
| Last updated: | May 23, 2007 |
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Medical content reviewed by the Faculty of the Harvard Medical School. Harvard Health Publications, Copyright © 2007 by President and Fellows of Harvard College. All rights reserved. Used with permission of StayWell.
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