Asthma is an inflammatory disorder of the airways, characterized by periodic attacks of wheezing, shortness of breath, chest tightness, and coughing.
Three things make it harder to breathe during an asthma attack -- the inflammation (swelling) of the lining of the airways, the tightening of the muscles around the airways, and fluid/mucus filling the airways. These factors reduce airflow and produce the characteristic wheezing sound.
Most people with asthma have periodic wheezing attacks separated by symptom-free periods. Some people have chronic shortness of breath with episodes where it gets worse. In other cases, cough is the 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 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.
The doctor will conduct a physical exam that focuses on the upper respiratory tract, chest, and skin. The doctor will listen for wheezing and may look for nasal secretions, eczema, and similar allergy-related symptoms.
The most important test for diagnosing asthma is called spirometry. A spirometer is an instrument that measures the maximum volume you can exhale after breathing in as much as you can. A drug called a bronchodilator is given to the patient to see whether breathing obstruction is "reversible." If so, this is a strong indication of asthma.
No one single test, or set of tests, is appropriate for every patient. Your doctor may use other tests to help rule out the possibility of other causes of your symptoms.
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:
- Long-term control (anti-inflammatory ) medications, which are used on a regular basis to prevent attacks, not for treatment during an attack.
- Inhaled corticosteroids (Azmacort, Vanceril, AeroBid, Flovent)
- Leoukotriene inhibitors (Singulair, Accolate)
- Long-acting bronchodilators (famoterol, Serevent)
- Cromolyn sodium (Intal) or nedocromil sodium
- Combination anti-inflammatory/bronchodilator (Advair diskus)
- Short-term control medications, which are used to relieve symptoms during an attack.
- Short-acting bronchodilators (Proventil, Alupent, Bronkosol, and others)
- Oral or intravenous corticosteroids (such as prednisone, methylprednisolone, and hydrocortisone) for stabilizing severe episodes
People with mild asthma (infrequent attacks) may use inhalers as needed. Those with significant asthma (symptoms occurring more than twice per week) should take anti-inflammatory medications on a regular basis for long-term control. A severe asthma attack 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.
Asthma symptoms can be substantially reduced by avoiding known allergens and respiratory irritants. If someone with asthma 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.
Alan Greene, M.D., F.A.A.P., Department of Pediatrics, Packard Children's Hospital, Stanford University School of Medicine; Chief Medical Officer, A.D.A.M., Inc.
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