Bronchitis is an inflammation of the air passages between the nose and lungs, which are called the bronchi. Acute bronchitis usually follows a cold or other viral respiratory infection, and features a lingering, dry cough that lasts a few days or weeks. Chronic bronchitis lasts longer and the symptoms, such as a persistent cough that brings up mucus, occur repeatedly.
Diseases that block airways have been described since ancient times. During Europe's industrialization, chronic bronchitis was a major cause of death, but the word bronchitis first was used in 1808 by Charles Badham, a physician. In 1952, severe smog in London caused even more deaths and increased interest in studying bronchitis and describing its symptoms.
Although acute and chronic bronchitis are both inflammations of the air passages, their causes and treatments are different. People have acute bronchitis most often in winter, usually following a viral infection, such as a cold or the flu. Acute bronchitis gets better within two weeks, although the cough can persist longer. Acute bronchitis, like any upper airway inflammatory process, can increase risk of developing pneumonia.
Chronic bronchitis is caused by inhaling bronchial irritants, especially cigarette smoke. Until the twenty-first century, more men than women developed chronic bronchitis, but as the number of women who smoke increased, so did their rate of chronic bronchitis. Other irritants, such as chemical fumes or vapors from jobs such as coal mining or textile manufacturing, can cause chronic bronchitis. Because this disease progresses slowly, middle-aged and older people are more likely to be diagnosed with chronic bronchitis. Chronic bronchitis also may be called chronic obstructive pulmonary disease (COPD).
Bronchitis also can be infectious or caused by infections such as the flu. After a measles outbreak in Romania in 1997, many people were hospitalized with complications, including bronchitis. One common virus that causes bronchitis is the respiratory syncytial virus (RSV). Outbreaks of RSV occur each year in the United States, usually in the fall, winter, or spring. The timing varies depending on the region of the country and other factors. Infections also have a complex relationship with chronic bronchitis. People who have the chronic disease should be careful to avoid infections, because their lungs are more vulnerable to infections such as flu or pneumonia.
Smoking, heart or lung disease, and exposure to chemical fumes or high levels of air pollution increase a person's risk for bronchitis. For example, people who farm or work in occupations that expose them to lots of dust are at much higher risk. If they also smoke, their risk of bronchitis or emphysema is nearly three-fold that of the general population. Infants, young children, and the elderly are also at greater risk for bronchitis.
Acute bronchitis is extremely common. Worldwide, it is one of the top five reasons for a child to see a doctor. The National Center for Health Statistics estimates that about 9% of Americans develop bronchitis each year. In European studies, as many as 20% of school-age children develop bronchitis.
Anyone can get acute bronchitis, but infants, young children, and the elderly are more likely to get the disease because people in these age groups generally have weaker immune systems. Smokers and people with heart or other lung diseases are also at higher risk of developing acute bronchitis. People exposed to chemical fumes or high levels of air pollution also have a greater chance of developing acute bronchitis. Outbreaks were common in the 1950s, before the association between industrial dusts and fumes and lung disease was fully understood. For example, a severe outbreak swept the city of Sydney, Australia, in 1954, and was tied mostly to workers in a suburban factory.
Chronic bronchitis is a major cause of disability and death in the United States. The American Lung Association estimated that in 2009, there were nearly 10 million cases of chronic bronchitis in the United States, and nearly 68% of them were among women. Most cases were among people who were 45 to 65 years of age, and the disease affected people in the South more than in any other region of the country.
Infectious bronchitis outbreaks have been reported around the world since 2003, and more than 60 types of viruses have been identified that affect chicken flocks. After the SARS epidemic, also in 2003, researchers became concerned about the possible spread of the virus to humans, although it does not happen frequently. RSV leads to as many as 125,000 hospitalizations each year in the United States, according to the Centers for Disease Control and Prevention.
Acute bronchitis usually begins with the symptoms of a cold, such as a runny nose, sneezing, and dry cough. However, the cough soon becomes deep and painful. Coughing brings up a greenish-yellow phlegm or sputum. These symptoms might be accompanied by a fever of up to 102°F (38.8°C). Wheezing after coughing is common. Acute bronchitis is caused by exposure to irritants such as dust or fumes, and infectious bronchitis can be caused by viruses, such as the flu, SARS, an adenovirus, or pneumonia. These viruses are transmitted by air, touch, and even swimming pool water.
Chronic bronchitis is caused by inhaling irritants that inflame the airways. The most common irritant is cigarette smoke. The American Lung Association estimates that 80–90% of COPD cases are caused by smoking. Other irritants include chemical fumes, air pollution, and environmental irritants, such as mold or dust.
Chronic bronchitis develops slowly over time. The cells that line the respiratory system contain fine, hairlike outgrowths called cilia. Normally, the cilia of many cells move mucus along the airways. When smoke or other irritants are inhaled, the cilia become paralyzed or snap off. When this occurs, the cilia no longer can move mucus, and the airways become inflamed, narrowed, and clogged. This condition leads to difficulty breathing and can progress to the life-threatening stages of COPD.
A mild cough, sometimes called smokers' cough, is often the first visible sign of chronic bronchitis. Coughing brings up phlegm, although the amount varies considerably from person to person. Wheezing and shortness of breath may accompany the cough. Diagnostic tests show a decrease in lung function. As the disease advances, breathing becomes difficult and activity decreases. The body does not get enough oxygen, leading to changes in the composition of the blood.
Bronchitis is diagnosed based on a patient's symptoms and health history. The doctor usually listens to the patient's chest, using a stethoscope to notice signs of airway inflammation, such as crackling, wheezing, or a bubbling sound caused by fluids in the bronchial tubes. The health history provides clues about recent exposure to viruses or irritants that might have caused the bronchitis.
The doctor also might order tests such as a sputum culture to check for colored or bloody sputum. The patient is asked to cough deeply and then spit the sputum into a cup. Sometimes, the patient needs a bronchoscopy, which involves passing a tube into the patient's airways to collect a sputum sample. The patient receives a local anesthetic to numb the area before the doctor passes the tube through the airways. A pulmonary function test helps diagnose chronic bronchitis. The patient breathes into an instrument called a spirometer to measure how much air enters and leaves the lungs. Blood tests, chest x rays, and electrocardiograms also might help with diagnosis.
Acute bronchitis often is treated much like a common cold when the patient has no secondary infection. The patient should drink plenty of fluids, rest, avoid smoking and exposure to other irritants, and increase air moisture by using a humidifier. Taking acetaminophen can ease some pain and fever symptoms. Children should not receive aspirin because of its association with Reye's syndrome, a serious illness. Using expectorant cough medicines can help a patient more easily cough up mucus. Antibiotics usually are not prescribed and do not help cure bronchitis caused by a virus, but they might help relieve symptoms or be prescribed if the patient has a secondary infection.
Patients who have chronic bronchitis can receive complex treatments, depending on the stage of disease, cause of disease, and other health problems they might have. They might be encouraged to make lifestyle changes, such as quitting smoking or avoiding irritants such as polluted air. Some patients with chronic bronchitis first receive bronchodilators, drugs that relax the airways and are taken by mouth or inhaled through a nebulizer. As chronic bronchitis progresses, patients may need oxygen therapy, the regular delivery of measured oxygen into the nose to help them breather easier.
Alternative practitioners focus on preventing bronchitis by suggesting that patients eat a healthy diet that strengthens the immune system. Doing so might help prevent viruses from leading to bronchitis. Many botanical and herbal remedies can be formulated to manage bronchitis. Examples include inhaling eucalyptus or other essential oils in warm steam.
When treated, acute bronchitis normally resolves in one to two weeks without complications, although a cough can continue for several more weeks. Chronic bronchitis, by contrast, can be slow in its progression, and a patient may have only some initial improvement in symptoms. Unfortunately, there is no cure for chronic bronchitis, and the disease can often lead to or coexist with emphysema.
The best way to prevent bronchitis is not to begin smoking or to stop smoking. Smokers are ten times more likely to die of COPD than nonsmokers. Smokers who stop show improvement in lung function. Other preventive steps include avoiding secondhand smoke, along with chemical and environmental irritants, such as air pollution, and maintaining good overall health. Immunization against certain types of pneumonia, as well as influenza, is an important preventive measure for anyone with lung or immune system diseases. Good hand-hygiene practices, such as washing hands or using hand sanitizers often, can help prevent spread of viruses that might lead to bronchitis.
See also Air pollution ; Chronic obstructive pulmonary disease ; Mold ; Severe acute respiratory syndrome (SARS) ; Smog ; Smoking ; Viruses .
Shapiro, Steven D., John J. Reilly, and Stephen I. Rennard. “Chronic Bronchitis and Emphysema.” In Textbook of Respiratory Medicine. 5th ed, edited by Robert J. Mason et al., 919–67. Boston: Saunders, 2010.
Centers for Disease Control and Prevention. “Bronchitis (Chest Cold);rdquo; http://www.cdc.gov/getsmart/antibiotic-use/URI/bronchitis.html . (June 8, 2018).
National Institutes of Health. “Bronchitis.” http://www.nhlbi.nih.gov/health/dci/Diseases/brnchi/brnchi_whatis.html (accessed June 6, 2018).
Ong, Samuel. “Bronchitis.” eMedicine. April 29, 2010. http://emedicine.medscape.com/article/807035-overview (accessed June 1, 2018).
American Lung Association, 1301 Pennsylvania Ave. NW, Ste. 800, Washington, DC, 20004, (212) 315-8700, (800)LUNG-USA (548-8252), http://www.lungusa.org .
National Heart Lung and Blood Institute Health Information Center, PO Box 30105, Bethesda, MD, 20824-0105, (301) 592-8573; TTY: (240) 629-3255, Fax: (240) 629-3246, firstname.lastname@example.org, http://www.nhlbi.nih.gov .
Teresa G. Odle