Asthma is a chronic (long-term) lung condition that causes breathing difficulties and wheezing when air passages narrow and become inflamed. The condition ranges from mild to severe. Some people have only occasional, mild symptoms, while others have nearly constant symptoms with severe, life-threatening flare-ups.

During an asthma attack, the airways become inflamed and narrower as the muscles surrounding them constrict. The flow of air is blocked partially or completely as mucus produced by the inflammation fills a narrower passageway. Asthma affects both the lung's larger airways, called the bronchi, and the lung's smaller airways, called the bronchioles. Treatment focuses on preventing or stopping the inflammation, and relaxing the muscles that line the airways.

What causes asthma-related inflammation is not clear, but several environmental "triggers" have been identified. Many asthma triggers are allergens, substances that cause the immune system to overreact in some people. Common allergens include animal dander and saliva, pollens, molds, dust mites, cockroaches, some medications and certain foods. Also high on the list of asthma triggers are viral infections, such as colds and influenza; exercise; breathing cold, dry air; environmental pollutants, such as cigarette smoke, wood smoke, paint fumes and chemicals; strong odors; and emotional stress. For some people with severe asthma, no specific triggers can be identified.

Although asthma can develop early, often before age 5, its symptoms can begin at any age. The condition has a genetic (inherited) component and often affects people with a family history of allergies. The American Lung Association estimates that 25 million people in the United States will be diagnosed with asthma in their lifetime. One-third of Americans with asthma symptoms are children.

Symptoms of asthma include:

• Wheezing (a whistling sound as air is forcibly expelled)
• Difficulty breathing
• Chest tightness
• A persistent cough

For some people with asthma, a chronic cough is the main symptom. For some people, symptoms flare up only during or after exercise. Between asthma attacks or flare-ups, people with mild or moderate asthma may not have any symptoms. People with asthma tend to have more severe symptoms when they have an upper respiratory infection such as a cold or the flu.

In addition to extreme shortness of breath and chest tightness, symptoms of a severe asthma attack can include:

• A rapid pulse
• Sweating
• Flared nostrils and pursed lips
• A need to sit upright
• A bluish discoloration of the lips and fingernails (cyanosis)

Your doctor will ask about any symptoms you have, how severe they are, when and where they occur, how frequently they occur, and what triggers and relieves them. These details will help your doctor find ways to help prevent your asthma attacks. Your doctor also will want to know about your personal history of allergies and respiratory illnesses, as well as your family history of asthma, allergies and respiratory illnesses.

Your doctor will listen to your back with a stethoscope to detect wheezing. During an attack, your doctor can assess the severity of your flare-up by listening for the amount of airflow and by looking at how you are using your chest muscles to breathe. Blue lips or skin are a sign that you are not getting enough oxygen. Other tests that can be done in the office include a measurement of the speed of the air you can exhale forcibly. This is done with a small, hand-held device called a peak-flow meter. Another test, called pulse oximetry, measures oxygen levels in your blood and is done by placing a small plastic clip on the tip of your finger.

During an asthma flare-up, blood tests may be done to check for signs of an elevated white blood cell count, which may indicate that you have an infection. A special test, called an arterial blood gas (ABG), can be done on blood drawn from your wrist to measure oxygen levels more accurately. Your doctor also may want you to have a chest X-ray.

Two tests are commonly used to show how well your lungs are functioning:

• Spirometry � This is a more thorough test. It is used when the diagnosis of asthma needs to be confirmed or your doctor needs more details about your lung function. During spirometry, you exhale into a device that analyzes the amount and volume of airflow. One part of the test may be repeated after you are given a medication, called a bronchodilator, that relaxes the muscles surrounding the airways to improve airflow. If airflow improves after using a bronchodilator, this is an indication that you have asthma. Sometimes, a challenge test is done, especially when spirometry appears normal. In this procedure, you inhale a medication (usually methacholine) to see if it provokes a measurable contraction of the airway muscles (bronchospasm). People with asthma are more sensitive to this medication.



• Peak-flow meter � This small portable tube provides a quick and easy measurement of air flow from the lungs. It measures the speed of air expelled when you blow forcibly through it. These devices often are given to asthma patients for use at home to monitor their asthma and help to detect the earliest signs of an asthma flare-up.

If your doctor suspects that your asthma is being triggered by allergens, and the symptoms are not treated or controlled easily with medications, a blood test or allergy skin testing may be done. The blood test, called the radioallergosorbent test (RAST), looks for antibodies to potential specific allergens. In allergy skin testing, the skin is exposed to weak dilutions of different potential allergens either by pricking the skin with the allergen or using a patch taped to the skin for several days. If there is redness and swelling at the injection site, you are allergic to that substance.

Asthma in adults often is a lifelong condition. With treatment, symptoms can be controlled and can be infrequent or very mild. In about half of children with asthma, it can go away on its own or become less severe over time. However, it often reappears later in life.

Asthma episodes can go away on their own or with the help of asthma medications. Attacks vary in frequency and severity, often dependent on which triggers cause the attack.

In some cases, asthma episodes can be prevented by avoiding or minimizing exposure to triggers. These include environmental triggers such as cigarette smoke, environmental pollutants (especially when pollution and ozone levels are high) and strong chemicals.

If exercise triggers your asthma, you can prevent an attack by breathing warm, humidified air before and during exercise or by using inhalers. Preventive medicine also can be used before an anticipated exposure to animals.

Eliminating allergens at home often can go a long way to control asthma symptoms. Some people may need to avoid animals entirely or to take special measures with their pets, such as keeping them out of bedrooms and bathing them regularly. If dust mites are a trigger, some household anti-mite measures include encasing mattresses in airtight enclosures, frequent household cleaning, washing bedding frequently in very hot water, and removing carpets and heavy draperies from sleeping areas.

Those who are affected by pollens might stay indoors whenever possible, use air conditioning and keep windows closed during high pollen season.

Monitoring your symptoms and peak-flow readings helps to identify a coming attack hours or even days before symptoms develop, which allows you to adjust your medications to prevent an attack.

Early signs or symptoms of an asthma flare-up include:

• Coughing more often
• Increased mucus or phlegm
• Becoming short of breath quickly with exertion or exercise
• Developing a sinus headache or fever
• Having symptoms that resemble a cold, such as a runny or congested nose, sneezing, or watery eyes

If you have chronic asthma, you should work with your doctor to develop a written asthma-management plan. The plan specifies how to avoid asthma triggers, when and how regular medications should be taken, how to handle acute attacks, and how a peak-flow meter should be used. It is important that preventive asthma medications be taken as prescribed, even when you are not having symptoms.

Several types of medication are available to treat asthma. Some treat acute attacks, while others prevent attacks from happening.

• Bronchodilators relax the muscles around the airways to improve airflow, and they are commonly inhaled. One class of bronchodilators called beta agonists, including albuterol (Proventil and others), typically can be prescribed alone for mild, occasional symptoms. Albuterol also is used as a "rescue" medication to stop an attack. It can be inhaled in an inhaler or taken with a nebulizer, a device that mixes medications with a mist for inhalation. Other bronchodilators, including salmeterol (Serevent) and theophylline (sold under numerous brand names), are used to prevent and control asthma. They are not useful for an asthma attack because they take too long to begin working. Salmeterol only should be used in combination with an inhaled corticosteroid or other anti-inflammatory medication.



• Anti-inflammatory medications usually are taken regularly to prevent asthma attacks from occurring. These drugs work by reducing inflammation, thereby decreasing mucous production and reducing constriction of airway muscles. Anyone with asthma symptoms that occur more than a couple times per week should consider taking an anti-inflammatory medication. The first choice is usually an inhaled corticosteroid. Cromolyn sodium (Intal) and nedocromil (Tilade) are inhaled anti-inflammatories that can be used for people that have problems with inhaled corticosteroids. They help to prevent attacks in mild to moderate asthma if used daily. They also can be used before contact with a known asthma trigger, for example, before exercise or exposure to animals. Leukotriene modifiers are oral drugs that work differentlhy to reduce inflammation. These drugs block leukotrienes, one of the many chemicals that cause inflammation and airway narrowing in many people with asthma.
  
  Doctors prescribe oral corticosteroid medications, such as prednisone, for asthma flares that don't quickly respond to an inhaled bronchodilator. The corticosteroid is taken for one to two weeks, usually with a tapering dose. Inhaled corticosteroids and other asthma medications should be continued at the same time. People requiring emergency department care or admission to the hospital often receive corticosteroids intravenously.
  
  Omalizumab (Xolair) blocks inflammation by attacking IgE antibodies. IgE antibodies are major players in allergic reactions. It is designed to help control symptoms in people with severe allergic asthma unresponsive to other therapies and require frequent oral corticosteroids. The drug is given by injection under the skin, usually once every four weeks. Omalizumab can cause a life threatening reaction called anaphylaxis, so the injection must be given in the doctor's office.

Some people with asthma also benefit from immunotherapy, in which the person is injected with increasing amounts of allergens to desensitize the person's immune system. Immunotherapy for asthma appears to be most effective for mild to moderate symptoms that are caused by sensitivity to indoor allergens such as dust mites, mold spores and animals.

Severe asthma attacks must be treated in a hospital, where oxygen can be administered, and drugs may be given either intravenously (into a vein) or with a nebulizer. In life-threatening cases, the patient may need a breathing tube placed in the large airway (intubation) and artificial ventilation in an intensive care unit.

Call your doctor whenever you or your child has persistent wheezing, chest tightness, difficulty breathing or cough. Some children with asthma may not complain specifically of shortness of breath. However, they may flare their nostrils or use their chest and neck muscles when breathing � signs that they are having trouble.

If you already have been diagnosed with asthma, call your doctor if your symptoms are getting worse or are not being controlled by your regular medications. For example, you should call your doctor if you must use your rescue bronchodilator more than four times a day to control symptoms, or your peak-flow-meter readings are in the yellow or red zones.

If you have an asthma attack and your symptoms persist despite your usual medications, seek emergency help immediately.

Although asthma cannot be cured, it almost always can be controlled successfully. Most people who have asthma can expect to lead relatively normal lives.

American Academy of Allergy, Asthma & Immunology (AAAAI)
555 East Wells St.
Suite 1100
Milwaukee, WI 53202-3823
Phone: 414-272-6071
Toll-Free: 1-800-822-2762
E-Mail: info@aaaai.org
http://www.aaaai.org/

American Lung Association
61 Broadway, 6th Floor
New York, NY 10006
Phone: 212-315-8700
Toll-Free: 1-800-548-8252E-Mail: info@lungusa.org
http://www.lungusa.org/

National Institute of Allergy and Infectious Diseases (NIAID)
Office of Communications & Public Liaison
6610 Rockledge Drive, MSC6612
Bethesda, MD 20892-6612
Phone: 301-496-5717
http://www.niaid.nih.gov/