Bronchitis is inflammation of the mucousmembranes of the bronchi, the airways that carry airflow from the trachea into the lungs. Bronchitis canbe classified into two categories, acute and chronic.
Acute bronchitis is characterized by thedevelopment of a cough,with or without the production of sputum, mucus that is expectorated(coughed up) from the respiratory tract. Acute bronchitis often occursduring the course of an acute viral illness such as the common coldor influenza.Viruses causeabout 90% of cases of acute bronchitis while bacteriaaccount for less than 10%.
Chronic bronchitis, a type of chronic obstructive pulmonarydisease, is characterized by the presence of a productive cough that lastsfor 3 months or more per year for at least 2 years. Chronic bronchitis mostoften develops due to recurrent injury to the airways caused by inhaledirritants. Cigarette smoking is the most common cause,followed by air pollution and occupational exposure to irritants,and cold air.
Acute bronchitis is most often caused by viruses that infectthe epitheliumof the bronchi, resulting in inflammation and increased secretion of mucus. Cough, a commonsymptom of acute bronchitis, develops in an attempt to expel the excess mucusfrom the lungs. Other common symptoms include sore throat,runny nose,nasalcongestion (coryza),low-grade fever, pleurisy, malaise, and theproduction of sputum.
Acute bronchitis often develops during the course of an upper respiratory infection (URI) suchas the commoncold or influenza.
Even with no treatment, most cases of acute bronchitis resolve quickly.
Only about 5-10% of bronchitis cases are caused by a bacterial infection.Most cases of bronchitis are caused by a viral infection and are"self-limited" and resolve themselves in a few weeks. As most casesof acute bronchitis are caused by viruses, antibioticsshould not be used since they are only effective against bacteria. Usingantibiotics in patients who do not have bacterial infections promotes thedevelopment of antibiotic-resistant bacteria, whichmay lead to greater morbidity and mortality.
Chronic bronchitis, a type of chronic obstructive pulmonarydisease, is defined by a productive cough that lasts for 3 months or moreper year for at least 2 years. Other symptoms may include wheezing and shortness of breath, especially upon exertion.The cough is often worse soon after awakening, and the sputum produced mayhave a yellow or green color and may be streaked with blood.
Chronic bronchitis is caused by recurring injury or irritation to therespiratory epithelium of the bronchi, resulting in chronic inflammation,edema (swelling),and increased production of mucus by gobletcells.Airflow into and out of the lungs is partly blocked because of the swelling andextra mucus in the bronchi or due to reversible bronchospasm.
Most cases of chronic bronchitis are caused by smoking cigarettes or other forms oftobacco. Chronic inhalation of irritating fumes or dust from occupationalexposure or air pollution may also be causative. About 5% of the population haschronic bronchitis, and it is two times more common in males than females.
Chronic bronchitis is treated symptomatically.
The most effective method of preventing chronic bronchitis and other formsof COPD is to avoid smoking cigarettes and other forms of tobacco.