Acute bronchitis

Bronchitis is an inflammation of the large bronchi (medium-size airways) in the lungs. It can lead to pneumonia. Acute bronchitis is usually caused by viruses or bacteria and may last several days or weeks.^[1] Acute bronchitis is characterized by cough and sputum (phlegm) production and symptoms related to the obstruction of the airways by the inflamed airways and the phlegm, such as shortness of breath and wheezing. Diagnosis is by clinical examination and sometimes microbiological examination of the phlegm. Treatment may be with antibiotics (if a bacterial infection is suspected), bronchodilators (to relieve breathlessness) and other treatments.

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Cause/Etiology

In about half of instances of acute bronchitis a bacterial or viral pathogen is identified.^[2] Typical viruses include respiratory syncytial virus, rhinovirus, influenza, and others.^[3]

Acute bronchitis can result from breathing irritating fumes, such as those of tobacco smoke or polluted air.^[4]

Signs and symptoms

Bronchitis may be indicated by an expectorating cough, shortness of breath (dyspnea) and wheezing. Occasionally chest pains, fever, and fatigue or malaise may also occur. Bronchitis caused by Adenoviridae may cause systemic and gastroentestinal symptoms.^[5]

Diagnosis

A physical examination will often reveal decreased intensity of breath sounds, wheezing (rhonchi) and prolonged expiration. Most doctors rely on the presence of a persistent dry or wet cough as evidence of bronchitis.

A variety of tests may be performed in patients presenting with cough and shortness of breath:

• A chest X-ray that reveals hyperinflation; collapse and consolidation of lung areas would support a diagnosis of pneumonia. Some conditions that predispose to bronchitis may be indicated by chest radiography.
• A sputum sample showing neutrophil granulocytes (inflammatory white blood cells) and culture showing that has pathogenic microorganisms such as Streptococcus spp.
• A blood test would indicate inflammation (as indicated by a raised white blood cell count and elevated C-reactive protein).
• Neutrophils infiltrate the lung tissue, aided by damage to the airways caused by irritation.
• Damage caused by irritation of the airways leads to inflammation and leads to neutrophils being present
• Mucosal hypersecretion is promoted by a substance released by neutrophils
• Further obstruction to the airways is caused by more goblet cells in the small airways. This is typical of chronic bronchitis
• Although infection is not the reason or cause of chronic bronchitis it is seen to aid in sustaining the bronchitis.

Treatment

Antibiotics

In most cases, acute bronchitis is caused by viruses, not bacteria and it will go away on its own without antibiotics. To treat acute bronchitis that appears to be caused by a bacterial infection, or as a precaution, antibiotics may be given.^[6] However, a meta-analysis found that antibiotics may reduce symptoms by one-half day.^[7]

Smoking cessation

For more details on this topic, see Smoking cessation.

To help the bronchial tree heal faster and not make bronchitis worse, smokers should cut back on the number of cigarettes smoked daily or quit smoking completely to allow their lungs to recover from the layer of tar that often builds up over time.^[8]

Antihistamines

Using over-the-counter antihistamines may be harmful in the self-treatment of bronchitis.^[9]

An effect of antihistamines is to thicken mucus secretions. Expelling infected mucus via coughing can be beneficial in recovering from bronchitis. Expulsion of the mucus may be hindered if it is thickened. Antihistamines can help bacteria to persist and multiply in the lungs by increasing its residence time in a warm, moist environment of thickened mucus.

Using antihistamines along with an expectorant cough syrup may be doubly harmful: encouraging the production of mucus and then thickening that which is produced. Using an expectorant cough syrup alone might be useful in flushing bacteria from the lungs. Using an antihistamine along with it works against the intention of using the expectorant.

Prognosis

Acute bronchitis usually lasts approximately 20 or 30 days. It may accompany or closely follow a cold or the flu, or may occur on its own. Bronchitis usually begins with a dry cough, including waking the sufferer at night. After a few days it progresses to a wetter or productive cough, which may be accompanied by fever, fatigue, and headache. The fever, fatigue, and malaise may last only a few days; but the wet cough may last up to several weeks.

Should the cough last longer than a month, some doctors may issue a referral to an otolaryngologist (ear, nose and throat doctor) to see if a condition other than bronchitis is causing the irritation. It is possible that having irritated bronchial tubes for as long as a few months may inspire asthmatic conditions in some patients.

In addition, if one starts coughing mucus tinged with blood, one should see a doctor. In rare cases, doctors may conduct tests to see if the cause is a serious condition such as tuberculosis or lung cancer.

Acute bronchitis may lead to asthma or pneumonia.^{[citation needed]}

Prevention

In 1985, University of Newcastle, Australia Professor Robert Clancy developed an oral vaccine for acute bronchitis. This vaccine was commercialised four years later as Broncostat.^[10]

References

See also

• Chronic bronchitis

Online medical references:

• Bronchitis Lungs OnLine
• Acute Bronchitis FamilyDoctor.org (American Academy of Family Physicians)