ASTHMA

DEFINITION

Asthma (pronounced AZ-muh) is a chronic (long-lasting) inflammatory disease of the airways in the human body. The inflammation causes the airways to narrow from time to time. This narrowing can produce wheezing and breathlessness. In extreme cases, the asthma patient may need to gasp to get enough air to breathe. Occasionally, a severe asthma attack can be fatal.

This condition sometimes improves on its own. In other cases, medication is needed to reopen airways. When inflammation occurs over and over again, the airways become especially sensitive to certain environmental conditions, such as cold air, dust mites, and pollen in the air. Exercise, stress, and anxiety can produce similar effects.

DESCRIPTION

About ten million Americans have asthma, and the number seems to be increasing. Between 1982 and 1992, the rate rose by 42 percent. Asthma is also becoming a more serious disease. In the same 10-year period, the death rate from asthma in the United States increased by 35 percent. These changes have come about in spite of new and improved drugs for the treatment of asthma.

An asthma attack affects the bronchi (pronounced BRONG-ki) and bronchioles (pronounced BRONG-kee-olz) in the lungs. The bronchi and bronchioles are tiny tubes through which air passes in and out of the body. In people with asthma, certain materials, such as dust and pollen, can irritate these tubes. By contrast, people without asthma are unaffected by these materials.

As these tubes become irritated, they swell and give off mucus, a sticky liquid. The liquid fills air spaces in the bronchi and bronchioles. Both swelling and mucus narrow the tubes, making it more difficult for air to get in and out of the lungs. As a result, an asthmatic person has to make a much greater effort to breathe in air and to expel it.

Asthma usually begins in childhood or adolescence, however it may first appear during the adult years. While the symptoms may be similar for these two cases, certain aspects of asthma are different in children and adults.

Child-onset Asthma

Some children are thought to develop asthma for genetic reasons. Their bodies are especially sensitive to materials in the environment that have little or no effect on other people. These materials are known as allergens (pronounced AL-erjins) because they produce an allergic response.

When children with this condition are exposed to dust mites, fungi, and other allergens, their bodies produce chemicals known as antibodies. The function of these antibodies is to fight off the invasion of materials from the environment. However, the release of antibodies also inflames the bronchi and bronchioles. The more often an asthmatic child is exposed to allergens, the more serious the response becomes. This condition, known as atopy (pronounced A-tuh-pee), is thought to occur in anywhere from 30 to 50 percent of the general population.

Adult-onset Asthma

Some individuals do not exhibit the symptoms of asthma until their adult years. In some cases, the cause of the disease may be the same as they are for children. In other cases, asthma is thought to be a result of exposure to wood dust, metals, certain forms of plastic, or other materials that get into the air in the workplace or at home.

CAUSES

In most cases, asthma is caused by inhaling an allergen. That allergen then sets off a series of reactions in the body that cause inflammation of bronchi and bronchioles. The most common inhaled allergens that lead to asthma attacks are:

• Animal dander (dry skin that is shed)
• Chemicals, fumes, or tiny particles that occur in the air in workplaces
• Fungi (molds) that grow indoors
• Mites found in house dust
• Pollen

Tobacco smoke is another cause of asthma attacks. The smoke irritates bronchi and bronchioles, setting off an asthma reaction. The same effect is caused whether an individual himself is smoking or is inhaling smoke second-hand (from someone else). Air pollutants can have a similar effect.

Three other factors can produce asthma attacks. They are:

• Exercise (exercise-related asthma)
• Inhaling cold air (cold-induced asthma)
• Stress or anxiety

Other factors that can cause an asthma attack or make it worse are rhinitis (pronounced ri-NIE-tuss; inflammation of the nose), sinusitis (pronounced sie-nuh-SIE-tis; inflammation of the sinuses), acid reflux (known as acid stomach), and viral infections of the respiratory (breathing) system.

SYMPTOMS

Wheezing is the most obvious symptom of an asthma attack. In most cases, the wheezing is loud and easy to observe. In other cases, it may be soft and hard to hear. A doctor may be able to hear the wheezing only by listening to the patient's chest with a stethoscope. Coughing and tightness in

A magnified image of a trachea covered with allergens. Stringy parts are cilia and spheres are pollen. (Reproduced by permission of

Custom Medical Stock Photo

)

the chest are other symptoms of asthma. Children sometimes complain of an itchiness on their back or neck at the start of an asthma attack.

A number of other outward signs are associated with an asthma attack. An attack may cause a person to become very anxious. He or she may sit upright, lean forward, or take some other position to make breathing easier. The person may be able to say only a few words before stopping to take a breath.

An attack may cause a person to become confused or may cause his or her skin to turn blue. Confusion and a blue skin color are signs that the person's body is not getting enough oxygen. The person should be given emergency treatment immediately. In the most severe cases, air sacs in the lungs may rupture. This causes air to collect in the chest, making it even more difficult for the person to breathe.

Some asthmatics may be free of symptoms most of the time. They may experience shortness of breath only on rare occasions and for short periods. Other asthmatics are in discomfort much of the time, coughing, wheezing, and trying to breathe normally. In some cases, crying or laughing can bring on an asthma attack.

The most serious attack can occur when a person already has an infection of the respiratory tract. High doses of an allergen can also trigger major attacks. Asthmatic attacks vary in their length as well as seriousness. Some attacks last only a few minutes. Others go on for hours or even days. Except in the most severe cases, patients recover from even the most serious asthma attacks.

DIAGNOSIS

A first step in diagnosis often involves taking a personal and family medical history. These histories can help a doctor determine whether asthma is a likely cause of a patient's problems.

Visual signs can also be used to diagnose asthma. Hunched shoulders and tightened neck muscles indicate that a patient is trying to get more air into his or her lungs. Increased amounts of nasal (nose) secretions are another sign of asthma. Eczema (pronounced EK-suh-muh) and other skin disorders (see skin disorders entry) are a sign that a person may have allergic reactions associated with asthma.

A number of tests can be used to diagnose asthma. A spirometer, for example, measures the rate at which air is exhaled from the lungs and how much air remains in the lungs. The device is used before and after a patient inhales a drug that widens the air passages. It tells whether airway narrowing is reversible, a typical finding with asthma. Patients can be given a similar instrument called a peak flow meter to use at home. The instrument helps them to determine how serious an asthma attack is.

Tests can also be used to determine the conditions that trigger an asthma attack. Skin tests may show any allergens to which a person is sensitive. That allergen may or may not, however, also be the cause of asthma attacks. Blood tests for the presence of antibodies can also be performed. Any antibodies found in the blood may indicate the allergens to which a person is sensitive.

Patients can also be asked to inhale specific allergens to see what effects they have. A spirometer is used to determine whether airways have become narrowed by the allergen. The spirometer is also used after a patient has exercised to see whether exercise-induced asthma is a possibility. A chest X ray can be taken to rule out conditions that produce symptoms similar to those of asthma.

TREATMENT

There are three primary goals of an asthma treatment program. First, troublesome symptoms should be prevented to the greatest extent possible. Second, lung function should be kept as close to normal as possible. Third, patients should be able to carry out their normal activities, including those requiring special effort, such as vigorous exercise. Patients should be examined on a regular basis to make sure treatment goals are being met. Spirometer tests are an essential part of these examinations.

Drugs

The goal of drug therapy is to find medications that control the symptoms of asthma with few or no side effects.

METHYLXANTHINES. The most commonly used methylxanthine (pronounced meth-uhl-ZAN-theen) is theophylline (pronounced thee-OFF-uh-lin).

Bronchodilators are drugs that open up bronchi and bronchioles. Taken with an inhaler, they are a common treatment for asthma. (© 1993

B.S.I.P.

Reproduced by permission of

Custom Medical Stock Photo

.)

Theophylline is used to reduce inflammation of the airways. It is especially helpful in controlling nighttime symptoms of asthma. Blood levels of the drug must be measured on a regular basis, however. If levels get too high, they can cause an abnormal heart rhythm or convulsions.

BETA-RECEPTOR AGONISTS. Beta-receptor agonists are bronchodilators (pronounced brong-ko-die-LATE-urs), drugs that open up bronchi and bronchiole. They make it easier for air to get into and out of airways. They are best used for the relief of sudden asthma attacks and to prevent exercise-induced asthma. These drugs generally start acting within minutes and last for up to six hours. They are taken by mouth, by injection, or with an inhaler.

STEROIDS. Steroids are related to natural body hormones. They reduce or prevent inflammation and are very effective in relieving the symptoms of asthma. When taken over a long period of time by inhalation, steroids can reduce the frequency of asthma attacks. They can also make airways less sensitive to allergens. For these reasons, they are the strongest and most effective methods for treating asthma. They can control even the most severe cases of the disease and maintain good lung function.

On the other hand, steroids have a number of side effects, some of which are serious. They can cause stomach bleeding, loss of calcium from bones, cataracts in the eyes, and a diabetes-like condition. Long-term use of steroids can also result in weight gain, loss of some mental function, and problems with wound healing. In children, growth may be slowed. Steroids can be taken by mouth, by injection, or by inhalation.

LEUKOTRIENE MODIFIERS. Leukotriene (pronounced lyoo-kuh-TRI-een) modifiers are drugs that interfere with changes in the bronchi and bronchioles that occur during an asthma attack. They prevent airways from narrowing and the release of mucus. They are recommended in place of steroids for older children and adults who have mild, long-lasting cases of asthma.

OTHER DRUGS. Anti-inflammatory drugs are sometimes used to prevent asthma attacks over the long term in children. Cromolyn (pronounced KRO-muh-lun) and nedocromil are two such drugs. They can also be taken before exercise or when exposure to an allergen cannot be avoided. These drugs are safe but expensive. They must be taken on a regular basis, even if the patient has no symptoms.

A class of drugs known as anti-cholinergics (pronounced ko-luh-NER-jiks) can also be used in the case of severe asthma attacks. Atropine is an example of this class of drugs. Anti-cholinergics are usually taken in combination with beta-receptor agonists. The combination helps widen airways and reduce the production of mucus.

Immunotherapy is used when a person cannot avoid exposure to an allergen. Immunotherapy is a procedure that involves a series of injections of the allergen. The series must be continued over a very long period of time, usually three to five years. During this period, the amount of allergen given in a shot is gradually increased. As more and more allergen is given, the patient's body slowly builds up an immunity (resistance) to the allergen.

Immunotherapy also has its risks. Injecting an allergen can itself cause an asthmatic attack. Studies seem to indicate, however, that the procedure can be effective against certain types of allergens, such as house-dust mites, ragweed pollen, and cat dander.

Managing Asthma Attacks

A severe asthma attack requires immediate treatment. Patients usually require supplemental (extra) oxygen. In rare cases, a mechanical ventilator may be needed to help a patient breathe. Inhalation of a beta-receptor is often effective in treating serious asthma attacks. If the patient does not respond to a beta-receptor, an injection of steroids may be necessary. Follow-up treatments with steroids make a recurrence of the attack less likely.

Maintaining Control

Long-term control over asthma is based on the use of beta-receptor drugs. These drugs are taken with inhalers that monitor the dose. Patients are instructed how to properly use an inhaler to make sure they receive the amount of drug needed to keep their disease under control. Once that goal is achieved, the amount of beta-receptor taken can be reduced. Patients should be seen by a doctor on a regular basis, however (such as once every one to six months).

As early on as possible, asthma patients should be trained in the treatment and control of their disease. They should be taught how to monitor their symptoms so they will know when an attack is starting. Using a flow meter is essential to this process. Over-the-counter medications should be avoided. Patients should also have an action plan to follow if their symptoms become worse. This plan includes how to adjust their medication and when to seek medical help.

Calling an asthma specialist should be considered when:

• There has been a life-threatening asthma attack or the disease has become severe and persistent (long-lasting).
• Treatment for three to six months has not met its goals.
• Some other condition, such as chronic lung disease, is complicating asthma.
• Special tests, such as allergy skin testing, are needed.
• Intensive steroid therapy has been necessary.

Hospitalization can sometimes be necessary for an asthma patient. That decision depends on a number of factors, such as the past history of serious attacks, severity of symptoms, current medication, and the availability of support at home.

PROGNOSIS

Most patients with asthma respond well when the best drug or combination of drugs is found. They are then able to lead relatively normal lives. More than half of all children diagnosed with asthma stop having attacks by the time they reach the age of twenty-one. Many others have less frequent and less severe attacks as they grow older.

A small minority of patients have progressively more trouble breathing as they grow older. These people run the risk of going into respiratory failure (loss of ability to breathe). They require immediate and intensive treatment.

PREVENTION

A number of steps can be taken to minimize or eliminate exposure to allergens and other factors that bring on an asthma attack. These steps include:

• As much as possible, avoid contact between an asthma patient and family pets to which he or she is allergic. Keep the pet out of the bedroom and away from carpets and upholstered furniture. Remove all feathers from the house.
• Avoid exposure to dust mites by removing wall-to-wall carpeting, reducing the humidity, and using special pillows and mattress covers. Remove stuffed toys or wash them each week in hot water.
• Cockroach allergens can be eliminated by killing the insects with poison, traps, or boric acid. Do not use synthetic chemicals. Prevent cockroaches from returning by making sure that food and garbage are not left out.
• Keep indoor air clean by vacuuming carpets once or twice a week while the patient is not present. Do use air conditioners during warm weather, but do not use humidifiers.
• Avoid exposure to tobacco smoke.
• Avoid outdoor exercise when air pollution levels are high.
• Exposure to workplace allergens can be avoided by following simple precautions. Always wear a mask and, if possible, arrange to work in a safer area.

FOR MORE INFORMATION

Books

Adams, Francis V. The Asthma Sourcebook: Everything You Need to Know. 2nd edition. Los Angeles, CA: Lowell House, 1998.

Gershwin, M. Eric, and E. L. Klinglhofer. Asthma: Stop Suffering, Start Living, 2nd edition. Reading, MA: Addison-Wesley Publishing Co., 1992.

Hyde, Margaret O. Living With Asthma. New York: Walker & Company, 1995.

Weiss, Jonathan H. Breathe Easy: Young People's Guide to Asthma. Washington, DC: Magination Press, 1994.

Organizations

Asthma and Allergy Foundation of America. 1233 Twentieth Street NW, Suite 402, Washington, DC 20036. 800–7ASTHMA. http://www.aafa.org.

National Asthma Education Program. 4733 Bethesda Avenue, Suite 350, Bethesda, MD 20814. (301) 495–4484.

Web sites

"Ask NOAH About: Asthma." NOAH: New York Online Access to Health. [Online] http://www.noah.cuny.edu (accessed on June 15, 1999).

"Asthma Information Center." [Online] http://www.mdnet.de/asthma/home.cfm (accessed on October 5, 1999).