Bronchitis is a form of lung disease that interferes with the lungs’ ability to move enough air in and out. In chronic bronchitis, the airways have become permanently swollen, which narrows them and may cause coughing and heavy mucus. This swelling in the airways is usually a response to irritants, such as tobacco smoke. Chronic bronchitis can lead to repeated lung infections.
The condition is called chronic bronchitis because it goes on for months at a time and recurs every year. It is defined by the presence of a daily, mucus-producing cough for at least three months of a year, for a period of at least two successive years without any other disease being diagnosed to explain the condition. Although the symptoms are considered chronic, they can become much worse during what is called an “attack” (exacerbation) of chronic bronchitis. The condition may get worse after a winter cold has passed. A cough may linger for weeks and produce a large amount of mucus. Coughing and the over-production of mucus may last longer after each cold. As the condition continues, chest infections become more frequent and long-term.
How Do the Lungs Work?
The lungs are a complex structure, like an upside-down tree. The main trunk (trachea) brings air in through the mouth and nose. Like a tree, as the airways branch off, they multiply and become narrower, until they finally end in a cluster of air sacs. At these air sacs, oxygen exchanges with carbon dioxide. The oxygen is then delivered to all parts of the body, and the carbon dioxide is exhaled.
What Causes Chronic Bronchitis?
Cigarette smoking is the main cause of chronic bronchitis. When tobacco smoke is breathed into the lungs, it irritates the airways, which then produce mucus. People who have been exposed for a long time to things that irritate their lungs, such as chemical fumes, dust and other substances, can also acquire chronic bronchitis. Once the bronchial tubes become irritated over a long period of time, excessive mucus is produced and the lining of the bronchial tubes becomes thickened.
An irritating cough develops, air passages become partially blocked by phlegm, and signs of wheezing and breathing difficulty are apparent. Unfortunately, some people neglect the severity of chronic bronchitis until the condition is in an advanced stage. It has become common for individuals to mistakenly believe that the disease is not life threatening. By the time a patient visits the healthcare professional, his or her lungs have been seriously injured and susceptible to severe respiratory problems.
In many cases, chronic bronchitis may be accompanied by damage deeper within the lungs called emphysema. Emphysema is a condition in which the tiny air sacs in the lungs called alveoli are destroyed. When this happens, the lungs are not able to bring in oxygen and get rid of carbon dioxide from the body. As a result, the heart has to work overtime to deliver oxygen to the body.
Chronic bronchitis and emphysema often occur together. They are referred to collectively as chronic obstructive pulmonary disease (COPD).