Acute Bronchitis

Acute bronchitis is inflammation of the bronchi due to upper airway infection. There is also an increase in the production of mucus in the airways.

Causes
Acute bronchitis is usually caused by a virus. Commonly it occurs after an upper respiratory tract infection, such as the common cold. The virus infects the bronchi, causing inflammation and an increased production of mucus.

Signs and Symptoms
The most common symptom is a persistent cough. Cough occurs because the airways are inflamed and irritated. The persistent cough usually lasts between 10 days to 20 days.

The cough may be productive of sputum. The sputum may be clear, yellow or green in colour. Some cells from the inner lining of the airways shed off, and therefore can cause purulent sputum. But purulent sputum does not signify a bacterial infection.

There may be chest discomfort due to muscle strain from excessive coughing. There may be mild shortness of breath. Fever is not common in acute bronchitis. Often the presence of a fever is a sign of another illness, such as pneumonia or influenza. 

Investigations
Auscultation may reveal wheeze, due to the narrowed bronchi. Auscultation may also reveal noisy breath sounds (called rhonchi) which often clear after coughing.

For most cases of acute bronchitis, the diagnosis is made based upon the history and physical examination. Further investigations (such as blood tests and chest x-ray) are not usually required.

However, further investigations are advised if the vital signs are abnormal or if the patient has impairment of the immune system, including the elderly and certain chronic diseases. Furthermore, investigations are required if another diagnosis is suspected, such as pneumonia, tuberculosis or pertussis.

Treatment
The majority of the time, acute bronchitis is caused by a virus. Therefore antibiotics are not required. The patient should be advised to keep well hydrated as this helps loosen respiratory secretions. Most people make a full recovery after 2 or 3 weeks.