Asthma

Lungs	Spirometry	Respiratory system

Alternative names

Bronchial asthma; Asthma - bronchial; Exercise induced asthma - bronchial; Reactive airways disease (RAD)

Definition

Asthma is an inflammatory disorder of the airways, characterized by periodic attacks of wheezing, shortness of breath, chest tightness, and coughing.

Causes and risks

Asthma is a disease in which inflammation of the airways causes airflow into and out of the lungs to be restricted. When an asthma attack occurs, the muscles of the bronchial tree become tight and the lining of the air passages swells, reducing airflow and producing the characteristic wheezing sound. Mucus production is increased.

Most people with asthma have periodic wheezing attacks separated by symptom-free periods. Some asthmatics have chronic shortness of breath with episodes of increased shortness of breath. Other asthmatics may have cough as their predominant symptom.  Asthma attacks can last minutes to days, and can become dangerous if the airflow becomes severely restricted.

In sensitive individuals, asthma symptoms can be triggered by inhaled allergens (allergy triggers), such as pet dander, dust mites, cockroach allergens, molds, or pollens. Asthma symptoms can also be triggered by respiratory infections, exercise, cold air, tobacco smoke and other pollutants, stress, food or drug allergies. Aspirin and other non-steroidal anti-inflammatory medications (NSAIDS) provoke asthma in some patients.

Asthma is found in 3-5% of adults and 7-10% of children. Half of the people with asthma develop it before age 10 and most develop it before age 30. Asthma symptoms can decrease over time, especially in children.

Many people with asthma have an individual and/or family history of allergies, such as hay fever (allergic rhinitis) or eczema. Others have no history of allergies or evidence of allergic problems.

Prevention

Asthma symptoms can be substantially reduced by avoiding exposure to known allergens and respiratory irritants. If an asthmatic is sensitive to dust mites, exposure can be reduced by encasing mattresses and pillows in allergen-impermeable covers, removing carpets from bedrooms, and by vacuuming regularly. Exposure to dust mites and mold can be reduced by lowering indoor humidity. If a person is allergic to an animal that cannot be removed from the home, the animal should be kept out of the patient’s bedroom. Filtering material can be placed over the heating outlets to trap animal dander. Exposure to cigarette smoke, air pollution, industrial dusts, and irritating fumes should also be avoided.

Allergy desensitization may be helpful in reducing asthma symptoms and medication use, but the size of the benefit compared to other treatments is not known.

Symptoms

• wheezing
  • usually begins suddenly
  • is episodic
  • may be worse at night or in early morning
  • aggravated by exposure to cold air
  • aggravated by exercise
  • aggravated by heartburn (reflux)
  • resolves spontaneously
  • relieved by bronchodilators (drugs that open the airways)
• cough with or without sputum (phlegm) production
• shortness of breath that is aggravated by exercise
• breathing that requires increased work
• intercostal retractions (pulling of the skin between the ribs when breathing)

Emergency symptoms:

• extreme difficulty breathing
• bluish color to the lips and face
• severe anxiety
• rapid pulse
• sweating
• decreased level of consciousness (severe drowsiness or confusion) during an asthma attack

Additional symptoms that may be associated with this disease:

• nasal flaring
• chest pain
• tightness in the chest
• abnormal breathing pattern, in which exhalation (breathing out) takes more than twice as long as inspiration (breathing in)
• breathing which temporarily stops
• coughing up blood

Signs and tests

Listening to the chest (auscultation) during an episode reveals wheezing. However, lung sounds are usually normal between episodes.

Tests may include:

• pulmonary function tests
• peak flow measurements
• chest X-ray
• allergy testing by skin testing or serum tests
• arterial blood gas
• eosinophil (a type of white blood cell) count

Treatment

Treatment is aimed at avoiding known allergens and respiratory irritants and controlling symptoms and airway inflammation through medication. Allergens can sometimes be identified by noting which substances cause an allergic reaction. Allergy testing may also be helpful in identifying allergens in patients with persistent asthma. Common allergens include: pet dander, dust mites, cockroach allergens, molds, and pollens. Common respiratory irritants include: tobacco smoke, pollution, and fumes from burning wood or gas.

A variety of medications for treatment of asthma are available. These include:

• anti-inflammatory medications
  • inhaled corticosteroids (Azmacort, Vanceril, AeroBid, Flovent)
  • oral or intravenous corticosteroids (such as prednisone, methylprednisolone, and hydrocortisone)
  • leoukotriene inhibitors (Singulair, Accolate)
  • cromolyn sodium (Intal), or nedocromil sodium are used to prevent attacks, not for treatment during an attack
• bronchodilators
  • short-acting (lasting a short time), inhaled or oral (Proventil, Alupent, Bronkosol, and others)
  • long-acting (lasting a long time), inhaled (famoterol, Serevent)
• aminophylline or theophylline

People with mild asthma (infrequent attacks) may use inhalers as needed. Those with significant asthma (symptoms occurring more than twice per week) should be treated with anti-inflammatory medications, preferably inhaled corticosteroids, and then with bronchodilators. Acute severe asthma requires a medical evaluation and may require hospitalization, oxygen, and intravenous medications.

A peak flow meter, a simple device to measure lung volume, can be used at home daily to check on lung functions. This often helps determine when medication is needed or can be tapered in the case of an exacerbation of symptoms. Peak flow values of 50-80% of an individual’s personal best indicate a moderate asthma exacerbation, while values below 50% indicate a severe exacerbation.

Support groups

The stress caused by illness can often be helped by joining a support group, where members share common experiences and problems. See asthma and allergy - support group.

Prognosis

There is no cure for asthma, though symptoms sometimes decrease over time. With proper self management and medical treatment, most people with asthma can lead normal lives.