Acute bronchitis, also known as a chest cold, is short-term inflammation of the bronchi (large and medium-sized airways) of the lungs. The most common symptom is a cough. Other symptoms include coughing up mucus, wheezing, shortness of breath, fever, and chest discomfort. The infection may last from a few to ten days. The cough may persist for several weeks afterward with the total duration of symptoms usually around three weeks. Some have symptoms for up to six weeks.
|Figure A shows the location of the lungs and bronchial tubes. Figure B is an enlarged view of a normal bronchial tube. Figure C is an enlarged view of a bronchial tube with bronchitis.|
|Symptoms||Cough with sputum, wheezing, shortness of breath, fever, chest discomfort|
|Duration||Up to 6 weeks|
|Causes||Typically viral infection|
|Risk factors||Tobacco smoke, dust, air pollution|
|Diagnostic method||Based on symptoms|
|Differential diagnosis||Asthma, pneumonia, bronchiolitis, bronchiectasis, COPD|
|Prevention||Avoiding air pollution, handwashing|
|Treatment||Rest, paracetamol (acetaminophen), NSAIDs|
|Frequency||~5% one or more episodes a year|
In more than 90% of cases the cause is a viral infection. These viruses may be spread through the air when people cough or by direct contact. Risk factors include exposure to tobacco smoke, dust, and other air pollution. A small number of cases are due to high levels of air pollution or bacteria such as Mycoplasma pneumoniae or Bordetella pertussis. Diagnosis is typically based on a person's signs and symptom. The color of the sputum does not indicate if the infection is viral or bacterial. Determining the underlying organism is typically not needed. Other causes of similar symptoms include asthma, pneumonia, bronchiolitis, bronchiectasis, and COPD. A chest X-ray may be useful to detect pneumonia.
Prevention is by not smoking and avoiding other lung irritants. Frequent hand washing and flu vaccination may also be protective. Treatment of acute bronchitis typically involves rest, paracetamol (acetaminophen), and NSAIDs to help with the fever. Cough medicine has little support for its use and is not recommended in children less than six years of age. Salbutamol is not effective in children with an acute cough who do not have restricted airways. There is weak evidence that salbutamol may be useful in adults with wheezing due to a restricted airway; however, it may result in nervousness, shakiness or a tremor. Antibiotics should generally not be used. An exception is when acute bronchitis is due to pertussis. Tentative evidence supports honey and pelargonium to help with symptoms.
Acute bronchitis is one of the most common diseases. About 5% of adults are affected and about 6% of children have at least one episode a year. It occurs more often in the winter. More than 10 million people in the United States visit a doctor each year for this condition with approximately 70% receiving antibiotics, most of which are not needed. There are efforts to decrease the use of antibiotics in acute bronchitis.
Signs and symptomsEdit
Bronchitis may be indicated by an expectorating cough, shortness of breath (dyspnea), and wheezing. On occasion, chest pains, fever, and fatigue or malaise may also occur. In addition, bronchitis caused by Adenoviridae may cause systemic and gastrointestinal symptoms as well. However, the coughs due to bronchitis can continue for up to three weeks or more even after all other symptoms have subsided.
Acute bronchitis can be caused by contagious pathogens, most commonly viruses. Typical viruses include respiratory syncytial virus, rhinovirus, influenza, and others. Bacteria are uncommon pathogens but may include Mycoplasma pneumoniae, Chlamydophila pneumoniae, Bordetella pertussis, Streptococcus pneumoniae, and Haemophilus influenzae.
- Damage caused by irritation of the airways leads to inflammation and leads to neutrophils infiltrating the lung tissue.
- 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.
A physical examination will often reveal decreased intensity of breath sounds, wheezing, rhonchi, and prolonged expiration. Most physicians 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 is useful to exclude pneumonia which is more common in those with a fever, fast heart rate, fast respiratory rate, or who are old.
- A sputum sample showing neutrophil granulocytes (inflammatory white blood cells) and culture showing that has pathogenic microorganisms such as Streptococcus species.
- A blood test would indicate inflammation (as indicated by a raised white blood cell count and elevated C-reactive protein).
Prevention is by not smoking and avoiding other lung irritants. Frequent hand washing may also be protective. Furthermore an oral whole cell nontypeable Haemophilus influenzae vaccine may protect against the disease, but "the evidence is mixed".
Evidence does not support the general use of antibiotics in acute bronchitis. A systematic review found antibiotics reduced cough by an average of 12 hours (out of a total average of about 14-28 days). Antibiotics caused more side effects such as nausea and diarrhoea, and also may promote antibiotic-resistant bacteria. It is possible they are useful in susceptible groups such as the frail and elderly but there was not enough research information to determine this.
Acute bronchitis usually lasts a few days or weeks. 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 physicians may issue a referral to an otorhinolaryngologist (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 physician. In rare cases, physicians may conduct tests to see whether the cause of the bloody sputum is a serious condition such as tuberculosis or lung cancer.
In infants under one year of age, acute bronchitis was the most common reason for admission to the hospital after an emergency department visit in the US in 2011.
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