Definition

Asthma is inflammation and narrowing of the airways (called the bronchial tubes).

	Inflamed Bronchus in the Lungs
	© 2008 Nucleus Medical Art, Inc.

Causes

The cause of asthma is not known, although it does seem to run in some families. Current research implicates environmental respiratory exposures in a genetically and biologically predisposed individual. Possible triggers of an asthma attack in a person with asthma include:

• Exercise
• Cold weather
• Viral illness
• Sinusitis
• Gastroesophageal reflux disease (GERD)
• Sulfites used in dried fruits and wine
• Medications, such as aspirin, ibuprofen, and beta-blockers
• Exposure to irritants or allergens, including:
  • Cigarette smoke, smoke from a wood-burning stove
  • Pet dander
  • Dust
  • Chemicals
  • Mold and mildew
  • Pollen
  • Smog or air pollution
  • Perfumed products

Risk Factors

A risk factor is something that increases your chance of getting a disease or condition.

• Living in a large urban area
• Regularly breathing in cigarette smoke (including second-hand smoke)
• Regularly breathing in industrial or agricultural chemicals
• A parent who has asthma
• History of multiple respiratory infections during childhood
• Low birth weight
• Being overweight
• Gastroesophageal reflux disease (GERD)

Symptoms

Symptoms include:

• Wheezing
• Tightness in the chest
• Trouble breathing
• Shortness of breath
• Cough
• Chest pain
• Self-limited exercise, difficulty keeping up with peers

Diagnosis

The doctor will ask about your symptoms and medical history and perform a physical exam:

Tests may include:

• Peak flow examination—blowing quickly and forcefully into a special instrument that measures your output of air
• Pulmonary function tests (PFTs)—breathing into a machine that records information about the function of your lungs
• Bronchoprovocation tests—lung function tests performed after exposure to methacholine, histamine, or cold or dry air, which can cause narrowing of the airways in susceptible people; this test helps confirm asthma in unclear cases, but is not often used in a general practice setting.
• Exhaled nitric oxide (a marker of airway inflammation)—to confirm the diagnosis and manage medications
• Allergy tests —usually skin or sometimes blood tests to find out if allergies are causing your symptoms

Treatment

The treatment approach to asthma is four-fold: regular assessment and monitoring, control of contributing factors (including treatment of concurrent medical conditions such as gastroesophageal reflux and sinusitis), patient education, and medications. Often, you'll need to take more than one type of medication.

Asthma medications include:

Quick-acting Beta Agonists

Quick-acting beta agonists, such as inhaled albuterol or xopenex, relax your airways so that they become wider again. These medications, also called rescue inhalers, are used to stop an acute episode of asthma, or "asthma attack."

Long-acting Beta Agonists

Long-acting beta agonists, such as inhaled salmeterol, are used daily to prevent asthma attacks. This inhaler should not be used to try to stop an asthma attack in progress. A study showed that long-acting inhalers, like salmeterol, may increase the risk of a life-threatening asthma attack and asthma-related death if taken for more than three months. * If you have any concerns, be sure discuss them with your doctor.

Inhaled Steroid

This medication is used daily to reduce inflammation in your airways. These types of inhalers should not be used to try to stop an asthma attack in progress.

Cromolyn Sodium or Nedocromil Sodium Inhaler

This treatment is used daily to prevent asthma flare-ups. If you have exercise-induced asthma, these may also be used just before exercise. These types of inhalers should not be used to try to stop an asthma attack in progress.

Zafirlukast, Zileuton, and Montelukast

These medications are taken daily to help prevent asthma attacks.

Omalizumab (Xolair)

This is a monoclonal antibody against immunoglobulin E (IgE). Used in conjunction with other medications, omalizumab is given as a subcutaneous injection to treat allergic asthma.

Anticholinergic Agents

Anticholinergic agents are inhaled medications, such as ipratropium, that function as a bronchodilator. These medications are used in conjunction with beta agonists.

Corticosteroids

Pills, injections, or intravenous (IV) medications are given to treat an acute flare-up of symptoms. You may also take corticosteroid pills for a longer period of time if you have severe asthma that isn't responding to other treatments.

Theophylline

These medications are taken daily to help prevent asthma attacks.

Epinephrine

Epinephrine is a shot given to stop an asthma attack.

Prevention

There are no guidelines for preventing asthma because the cause is not known. However, you can help prevent asthma attacks by avoiding substances that trigger the attacks. Some general guidelines include:

• Keep windows closed.
• Consider getting HEPA filters for your heating/cooling system and your vacuum cleaner.
• Keep the humidity down in your house.
• Avoid strenuous outdoor exercise during days with high air pollution, a high pollen count, or a high ozone level.
• Get a yearly flu shot .
• Treat allergies and sinusitis.
• Don't smoke.
• Avoid breathing in chemicals or second-hand smoke.
• Don't use a wood-burning stove regularly.
• Consider getting allergy shots, if allergies trigger your asthma attacks.
• Talk to your doctor about an appropriate level of exercise for you.
• Talk to your doctor about how to track your asthma, so you can identify and treat flare-ups immediately.

RESOURCES:

American Academy of Allergy, Asthma, and Immunology
http://www.aaaai.org

American Lung Association
http://www.lungusa.org

Asthma and Allergy Foundation of America
http://www.aafa.org

CANADIAN RESOURCES:

Allergy Asthma Information Association
http://aaia.ca/

Calgary Allergy Network
http://www.calgaryallergy.ca/

References:

Cecil Textbook of Medicine. 21st ed. WB Saunders Company; 2000.

Conn's Current Therapy 2001 . 53rd ed. WB Saunders Company; 2001.

High ozone levels harmful to respiratory system, especially for asthmatics. American Academy of Allergy, Asthma & Immunology. News Release. June 1, 1999.

Pulmonary and Critical Care Medicine . Mosby-Year Book, Inc; 1998.

Kleigman RM, Jensen HB, Behrman RE, Stanton BF, eds. Nelson Textbook of Pediatrics. 18th ed. Philadelphia, PA: Saunders Elsevier; 2007.

*Updated section on Treatment on 9/14/06 according to the following study, as cited by DynaMed's Systematic Literature Surveillance : Salpeter SR, Buckley NS, Ormiston TM, et al. Meta-analysis: effect of long-acting beta-agonists on severe asthma exacerbations and asthma-related deaths. Ann Intern Med . 2006;144:904-912.

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