Section 4. Lung and Airway Disorders

Chapter 41. Bronchitis

Topic: Bronchitis

Bronchitis

Bronchitis is inflammation of the large airways that branch off the trachea (bronchi), usually caused by infection but sometimes caused by irritation from a gas or particle.

Symptoms lasting up to 90 days are usually classified as acute bronchitis; symptoms lasting longer, sometimes for months or years, are usually classified as chronic bronchitis. When chronic bronchitis also decreases airflow, it is considered a defining characteristic of chronic obstructive pulmonary disease (see Section 4, Chapter 45). This chapter discusses acute bronchitis only.

Causes

Acute bronchitis can be caused by infection or by exposure to irritants.

See the figure Understanding Bronchitis.

Infectious bronchitis occurs most often during the winter and is most often caused by viruses. Even after a viral infection has resolved, the irritation it causes can continue to cause symptoms for weeks. Infectious bronchitis may also be caused by bacteria, and it often follows an upper respiratory viral infection. Mycoplasma pneumoniae and Chlamydia pneumoniae often cause bacterial bronchitis in young adults. Among middle-aged and older people, Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis are the most common organisms causing bacterial bronchitis. Viral bronchitis may be caused by a number of common viruses, including the influenza virus. A person often has a combination of bacterial and viral bronchitis.

Smokers and people who have chronic lung diseases may have repeated attacks of acute bronchitis because mucus is less able to drain from their airways. Malnutrition increases the risk of upper respiratory tract infections and subsequent acute bronchitis, especially in children and older people. Chronic sinus infection, bronchiectasis (see Section 4, Chapter 47), and allergies also increase the risk of repeated episodes of acute bronchitis. Children with enlarged tonsils and adenoids may have repeated episodes of bronchitis.

Irritative bronchitis (also called industrial or environmental bronchitis) may be caused by exposure to various mineral and vegetable dusts. Exposure to fumes from strong acids, ammonia, some organic solvents, chlorine, hydrogen sulfide, sulfur dioxide, and bromine can also cause irritative bronchitis.

Symptoms

Infectious bronchitis generally begins with the symptoms of a common cold: runny nose, sore throat, fatigue, chilliness, and back and muscle aches. A slight fever (100° to 101° F) may be present. The onset of cough (usually dry at first) signals the beginning of acute bronchitis. With viral bronchitis, small amounts of white mucus are often coughed up. When the coughed-up mucus changes from white to green or yellow, the condition may have been complicated by a bacterial infection.

With severe bronchitis, fever may be as high as 101° to 102° F and may last for 3 to 5 days even with antibiotic treatment. The cough is the last symptom to subside and often takes several weeks or even longer to resolve. Viruses can damage the epithelial cells lining the bronchi, and the body needs time to repair the damage. Airway hyperreactivity, which is a short-term narrowing of the airways with impairment or limitation of the amount of air flowing into the lungs, is common with acute bronchitis. The impairment of airflow may be triggered by common stimuli, such as inhaling mild irritants, inhaling cold, outdoor air, or smelling strong odors. If the impairment of airflow is severe, the person may be short of breath. Wheezing, especially after coughing, is common.

Serious complications, such as acute respiratory failure (see Section 4, Chapter 55) or pneumonia (see Section 4, Chapter 42), usually occur only in people who have an underlying chronic lung disease, such as chronic obstructive pulmonary disease or asthma.

Diagnosis

A doctor usually makes a diagnosis of bronchitis based on the symptoms and the lack of evidence of pneumonia. The doctor may hear wheezing during the physical examination.

The doctor may inspect a sample of sputum: clear or white sputum suggests a viral infection; yellow or green sputum suggests a bacterial infection. If symptoms are severe, the doctor may order a chest x-ray to exclude pneumonia. If a cough persists for more than two months, a chest x-ray is performed to exclude an underlying lung disease, such as lung cancer.

Treatment

Cough medicines can be used to suppress a dry, disturbing cough (see Section 4, Chapter 39). However, a cough that produces a lot of sputum usually should not be suppressed. Expectorants may help to thin secretions and make them easier to cough up. Adults may take aspirin, acetaminophen, or ibuprofen to reduce fever and general feelings of illness, but children should take only acetaminophen or ibuprofen, not aspirin. People with acute bronchitis, especially those who have a fever, should rest and drink enough fluid to keep their urine pale (except on arising from sleep, when urine is usually darker).

Antibiotics are used to treat acute bronchitis that appears to be caused by a bacterial infection and may be given as a precaution to people with underlying lung disease, even when there is no evidence of bacterial infection. Adults may be given amoxicillin, tetracycline, doxycycline, or trimethoprim-sulfamethoxazole. When Mycoplasma pneumoniae or Chlamydia pneumoniae is the suspected cause, erythromycin or doxycycline is usually given. Newer antibiotics, such as several oral cephalosporins (cefaclor, cefuroxime), azithromycin, clarithromycin, and the newer fluoroquinolones (levofloxacin, gatifloxacin) are highly effective, but because of their high cost, they are generally used for more serious lung infections. For children, amoxicillin is usually given. When symptoms persist or recur or when bronchitis is unusually severe, a laboratory culture of coughed-up sputum may show whether a different antibiotic is needed.

Antibiotics do not help people with viral bronchitis. However, if influenza is the suspected cause, treatment with an antiviral drug may be helpful. The symptoms of limited airflow and wheezing can be treated with the use of cool-mist humidifiers or steam vaporizers. The person can also inhale warm water vapor while leaning over a bathroom sink filled with hot water with a towel loosely draped over the head. Bronchodilators, which dilate the bronchi, can be used to temporarily open the airways and reduce wheezing. Corticosteroids, usually given in a metered-dose inhaler (see Section 4, Chapter 44), are also sometimes used to diminish cough and inflammation and hyperreactivity of the airways, especially when the cough persists after the infection has resolved.