Bronchitis - causes, symptoms, treatment

Bronchitis is an acute (short-term) or chronic (long-term) inflammation of the airways of the lungs. It is caused by infection, cigarette smoking, and inhalation of environmental pollutants. The most characteristic symptoms are coughing and wheezing. Treatment of bronchitis primarily involves the relief of symptoms and, in cases of chronic bronchitis, minimising damage to the airways. 

General information

Bronchitis, which can affect anyone, is one of the most common conditions for which people seek medical advice. It occurs mostly in winter, especially during outbreaks of influenza (the flu). People with bronchitis are more susceptible to developing pneumonia, which is a serious bacterial or viral infection of the lungs. 

Inflammation of the airways causes them to narrow and secrete thick mucus, or phlegm, which clogs the small airways, causing the characteristic cough of bronchitis, wheezing, and shortness of breath. The cough may produce sputum, which is phlegm coughed up from the lungs. This is known as a productive cough – an attempt by the body to clear mucus that is clogging the airways. 

Recurrent or long-term inflammation, as seen with chronic bronchitis, can result in irreversible (permanent) damage to, and narrowing of, the airways. Airway narrowing obstructs the flow of air in and out of the lungs. For this reason, chronic bronchitis is considered to be a type of chronic obstructive pulmonary disease (COPD), which is a progressive and irreversible condition of reduced lung function. 

Causes

The most common cause of acute bronchitis is viral infection (90% of cases), but bacterial infection and environmental irritants are also causes. Acute bronchitis usually occurs after having had a cold or flu. It also often occurs with or after childhood infections, such as measles, whooping cough (pertussis), and diphtheria. Exposure to second-hand cigarette smoke during pregnancy and in the household is strongly linked to recurrent bronchitis in infants and children. 

Chronic bronchitis may result from a series of acute bronchitis episodes, or it may evolve gradually due to heavy cigarette smoking or breathing air contaminated with other environmental pollutants, including work-place (occupational) exposures. In addition to cigarette smoking, the list of causative substances includes coal dust, oil mist, cement dust, welding fumes, organic dusts, engine exhausts, fire smoke and second-hand cigarette smoke. The majority of people diagnosed with chronic bronchitis are aged 45 years or older. 

People with chronic bronchitis can experience acute exacerbation (worsening) of their bronchitis, usually (in 70-80% of cases) due to an infection of the airways.

Signs and symptoms

The most obvious symptom of acute bronchitis is a short-term dry hacking cough, which can become a productive cough that produces white or yellow sputum. Other symptoms may be wheezing and shortness of breath. As with any infection, there may also be associated fever, sore throat, chills, aches and pains, and a general feeling of tiredness and being unwell.  Children aged less than five years rarely have a productive cough – sputum is usually seen in vomit – and parents will often hear a rattling sound in the chest.
 
The most common symptoms of chronic bronchitis are a recurrent or persistent productive cough, wheezing, and gradually worsening shortness of breath. Other symptoms include fatigue, sore throat, nasal congestion and headaches. Severe coughing may cause chest pain and cyanosis, which is a blue/grey colouration of the skin. Recurrent infection of the airways is also a sign of chronic bronchitis.
 
Because many symptoms of chronic bronchitis are similar to those of other lung conditions it is important that a doctor is consulted for a proper diagnosis.

Diagnosis

In acute bronchitis, coughing usually lasts between 10 to 20 days. There are no specific tests for acute bronchitis, although a chest x-ray may be requested if pneumonia is also suspected. Tests may be required if there is recurrent or persistent cough that may suggest asthma or chronic bronchitis. Coughing for a period of greater than four weeks may be due to whooping cough (pertussis).
 
Chronic bronchitis is clinically defined as productive cough for at least three months during a period of two consecutive years. Chronic bronchitis is diagnosed by taking a thorough medical history, including cigarette smoking and inhalation of toxic substances, as well as a physical examination. Testing may include a chest x-ray and sputum tests, and a spirometry test to measure lung function. An important part of the diagnosis is to distinguish chronic bronchitis from other lung conditions, such as chronic asthma and bronchiectasis.

Treatment

Acute bronchitis will usually resolve on its own within a couple of weeks, with complete healing of the airways and return to full function. Hence, the aim of treatment is to control symptoms. Antibiotics are not usually effective because most cases of acute bronchitis are caused by viruses. They should only be used if bacterial infection is strongly suspected or confirmed by testing.  Treatment of acute bronchitis involves:  

• Getting adequate rest and fluid intake 
• Use of over-the-counter medications to relieve muscle aches and pains and headaches, and to reduce fever 
• Use of cough suppressants for a dry cough, but not for a productive cough 
• Use of expectorants for productive cough, to help clear the airways of mucus
• Stopping smoking and avoidance of other airborne irritants
• Use of bronchodilator medication (relievers) to open obstructed airways in people who have associated wheezing with their coughing or underlying asthma or COPD.

In children with acute bronchitis, the main target of treatment is the control of fever and muscle pain, which can be achieved with over-the-counter medications such as paracetamol or ibuprofen. 

Because most cases of acute bronchitis, as well as acute exacerbations of chronic bronchitis, are caused by the common cold or the flu, it helps to take measures to stop the spread of these viruses including the following:  

• Regular thorough hand washing and drying
• Avoiding contact with people who are unwell
• Reducing time spent in crowded places, especially during cold and flu season
• Getting an annual influenza vaccination.

The primary objective of treatment for chronic bronchitis is to control symptoms and to prevent further airway damage and narrowing. The most effective way of achieving this is to quit smoking and to avoid inhalation of environmental irritants and toxins. Pulmonary rehabilitation, which is a programme of education and exercise, will help to maintain lung function and quality of life. Physiotherapy is useful for learning how to control breathing to avoid breathlessness and to clear phlegm from the lungs.

Medications used in the treatment of chronic bronchitis include:

• Bronchodilators (relievers), such as salbutamol, theophylline and ipratropium bromide, to open obstructed airways to make breathing easier
• Oral corticosteroids, such as methylprednisone, to control acute exacerbations of chronic bronchitis
• Inhaled corticosteroids (preventers), such as beclomethasone and fluticasone, to prevent acute exacerbations of chronic bronchitis
• Use of a combined bronchodilator and inhaled corticosteroid, such as formoterol with budesonide or salmeterol with fluticasone, to control persistent cough
• Antibiotics, such as amoxicillin/clavulanate, to control acute exacerbations of chronic bronchitis.
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