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Asthma

Asthma

Definition

Asthma is a chronic (long-lasting) inflammatory disease of the airways. In people susceptible to asthma, this inflammation causes the airways to narrow periodically. This narrowing, in turn, produces wheezing and breathlessness that sometimes causes the patient to gasp for air. Obstruction to air flow either stops spontaneously or responds to a wide range of treatments, but continuing inflammation makes the airways hyper-responsive to stimuli such as cold air, exercise , dust mites, pollutants in the air, and even stress and anxiety .

Description

The changes that take place in the lungs of people with asthma make the airways (the "breathing tubes," or bronchi and the smaller bronchioles) hyper-reactive to many different types of stimuli that do not affect healthy lungs. In an asthma attack, the muscle tissues in the walls of the bronchi go into spasm, and the cells lining the airways swell and secrete mucus into the air spaces. These two actions cause the bronchi to become narrowed (bronchoconstriction). As a result, a person with asthma has to make a much greater effort to breathe.

Cells in the bronchial walls, called mast cells, release certain substances that cause the bronchial muscles to contract and stimulate mucus formation. These substances, including histamine and a group of chemicals called leukotrienes, also bring white blood cells into the area, which play a key role in the inflammatory response. Many patients with asthma are prone to react to such "foreign" substances as pollen, house dust mites, or animal dander. These are called allergens. An acute asthma attack can begin immediately after exposure to a trigger or several days or weeks later.

When asthma begins in childhood, it often affects a child who is likely, for genetic reasons, to become sensitized to common "allergens" in the environment (atopic person). When these children are exposed to house dust mites, animal proteins, fungi, or other potential allergens, they produce a type of antibody that is intended to engulf and destroy the foreign materials. This makes the airway cells sensitive to particular materials. Further exposure can rapidly lead to an asthmatic response.

Demographics

Asthma affects about 17 million Americans, including nearly five million children. Asthma usually begins in childhood or adolescence , but it also may first appear in adulthood. Asthma is the leading cause of chronic illness in children, accounting for 14 million missed school days annually. It is the third-ranking cause of hospitalization among children under age 15.

Asthma affects as many as 1012 percent of children in the United States and the number has been steadily increasing. Since 1980, asthma has increased by 160 percent among children at least four years of age. Asthma is becoming more frequent, anddespite modern drug treatmentsit is more severe than in the past. Some experts suggest this is due to increased exposure to allergens such as dust, air pollution, second-hand smoke, and industrial components.

Asthma can begin at any age, but most children experience their first symptoms by the time they are five years old. Boys have a higher incidence of asthma than girls, and the disease is more prevalent in African American children. Children living in inner cities, low-income populations, and minorities have disproportionately higher morbidity and mortality due to asthma.

Causes and symptoms

Causes

About 80 percent of childhood asthma cases are caused by allergies . In most cases, inhaling an allergen sets off the chain of biochemical and tissue changes leading to airway inflammation, bronchoconstriction, and wheezing characteristic of asthma. Because avoiding (or at least minimizing) exposure is the most effective way of treating asthma, it is vital to identify the allergen or irritant that is causing symptoms in a particular child.

Once asthma is present, symptoms can be triggered or made worse if the child also has rhinitis (inflammation of the lining of the nose) or sinusitis. Gastroesophageal reflux disease (GERD), a condition that causes stomach acid to pass back up the esophagus, can worsen asthma. Many pulmonary infections in early childhood, including those due to Chlamydia pneumoniae, Mycoplasma pneumoniae, and respiratory syncytial virus, have been linked with an increased risk for wheezing and asthma. Aspirin and a class of drugs called beta-blockers (often used to treat high blood pressure) can also worsen the symptoms of asthma. Foggy and cloudy environments have been noted to aggravate asthma, and obesity facilitates asthma, but does not cause it.

The most important inhaled allergens and triggers contributing to attacks of asthma are:

  • animal dander
  • smites in house dust
  • fungi (molds) that grow indoors
  • mold spores that grow outdoors
  • cockroach allergens
  • tree, grass, and weed pollen
  • occupational exposure to chemicals, fumes, or particles of industrial materials in the air
  • strong odors, such as from perfume
  • wood smoke

Inhaling tobacco smoke (from secondhand smoke or smoking ) can irritate the airways and trigger an asthmatic attack. Air pollutants can have a similar effect.

There are three important factors that regularly produce attacks in certain patients with asthma, and they may sometimes be the sole cause of symptoms. They are:

  • humidity and temperature changes, especially inhaling cold air
  • exercise (in certain children, asthma is caused simply by exercising, and is called exercise-induced asthma)
  • stress, strong emotions, or a high level of anxiety

Risk factors

There are many risk factors for childhood asthma, including:

  • presence of allergies
  • family history of asthma and/or allergies
  • frequent respiratory infections
  • low birth weight
  • mother's exposure to tobacco smoke during pregnancy and/or child's exposure after birth
  • wheezing with upper respiratory infections

Symptoms

Wheezing is often very obvious, but mild asthmatic attacks may be confirmed when the physician listens to the patient's chest with a stethoscope. Wheezing is often loudest when the child breathes out, in an attempt to expel used air through the narrowed airways. Besides wheezing and shortness of breath, the child may cough and experience pain or pressure in the chest. The child may have itching on the back or neck at the start of an attack. Infants may have feeding problems and may grunt while sucking or feeding. Tiring easily or becoming irritated are other common symptoms.

Some children with asthma are free of symptoms most of the time, but may occasionally experience brief periods during which they are short of breath. Others spend much of their days (and nights) coughing and wheezing, until the asthma is properly treated. Crying or even laughing may bring on an attack. Severe episodes, which are less common, may be seen when the patient has a viral respiratory tract infection or is exposed to a heavy load of an allergen or irritant. Asthmatic attacks may last only a few minutes or can go on for hours or even days (a condition called status asthmaticus).

Asthma symptoms can be classified as:

  • Mild intermittent: Symptoms occur twice a week or less; nighttime symptoms occur twice a month or less; symptoms are brief and last a few hours to a few days; no symptoms occur between more severe episodes.
  • Mild persistent: Symptoms occur more than twice a week but not every day; nighttime symptoms occur more than twice a month; episodes are severe and sometimes affect activity.
  • Moderate persistent: Symptoms occur daily; nighttime symptoms occur more than once a week; quick-relief medication is used daily; symptoms affect daily activities; severe episodes occur twice a week or more and last for days.
  • Severe persistent: Symptoms occur continually throughout the day and frequently at night; symptoms affect daily activities and cause the patient to limit activities.

Shortness of breath may cause a patient to become very anxious, sit upright, lean forward, and use the neck or chest wall muscles to help with breathing. These symptoms require emergency attention. In a severe attack that lasts for some time, some of the air sacs in the lung may rupture so that air collects within the chest. This makes it even harder to breathe in adequate amounts of air.

Almost always, even patients with the most severe attacks will recover completely.

When to call the doctor

If a child has the following symptoms, the parent should contact the child's pediatrician:

  • inability to participate in normal activities
  • missed school due to asthma symptoms
  • symptoms that do not improve about 15 minutes after initial treatment with medication
  • signs of infection such as increased fatigue or weakness, fever or chills, sore throat , coughing up mucus, yellow or green mucus, sinus drainage, nasal congestion, headaches, or tenderness along the cheekbones

If the parent is unsure about what action to take to treat the child's symptoms, he or she should call the child's doctor.

The parent or caregiver should seek emergency care by calling 911 in most areas when the child has these symptoms or conditions:

  • bluish skin tone
  • bluish coloration around the lips, fingernail beds, and tongue
  • severe wheezing
  • uncontrolled coughing
  • very rapid breathing
  • inability to catch his or her breath
  • tightened neck and chest muscles due to breathing difficulty
  • inability to perform a peak expiratory flow
  • feelings of anxiety or panic
  • pale, sweaty face
  • difficulty talking
  • difficulty walking
  • confusion
  • dizziness or fainting
  • chest pain or pressure

Diagnosis

Early diagnosis is critical to proper asthma treatment and management. Asthma may be diagnosed by the child's primary pediatrician or an asthma specialist, such as an allergist.

The diagnosis of asthma may be strongly suggested when the typical symptoms and signs are present, including coughing, wheezing, shortness of breath, rapid breathing, or chest tightness. The physician will question the child (if old enough to provide an accurate history of symptoms) or parent about his or her physical health (the medical history), perform a physical examination, and perform or order certain tests to rule out other conditions.

The medical and family history help the physician determine if the child has any conditions or disorders that might be the cause of asthma. A family history of asthma or allergies can be a valuable indicator of asthma and may suggest a genetic predisposition to the condition. The physician will ask detailed questions about the child's symptoms, including when they first occurred, what seems to cause them, the frequency and severity, and how they are being managed.

During the physical exam, the pediatrician will listen to the patient's chest with a stethoscope to evaluate distinctive breathing sounds. He or she also will look for maximum chest expansion during inhalation. Hunched shoulders and contracting neck muscles are signs of narrowed airways. Nasal polyps or increased amounts of nasal secretions are often noted in patients with asthma. Skin changes, like atopic dermatitis or eczema, may demonstrate that the patient has allergic problems.

When asthma is suspected, the diagnosis can be confirmed using certain respiratory tests. Spirometry is a test that measures how rapidly air is exhaled and how much air is retained in the lungs. Usually the child should be at least five years of age for this test to be successful. During the test, the child exhales and the spirometer measures the airflow, comparing lung capacity to the normal range for the child's age and race. The child then inhales a drug that widens the air passages (a short-acting bronchodilator) and the doctor takes another measurement of the lung capacity. An increase in lung capacity after taking this medication often indicates the asthma symptoms are reversible (a very typical finding in asthma). The spirometer is similar to the peak flow meter that patients use to keep track of asthma severity at home.

Often, it is difficult to determine what is triggering asthma attacks. Allergy skin testing may be performed, especially if the doctor suspects the child's symptoms are persistent. An allergic skin response does not always mean that the allergen being tested is causing the asthma. Also, the body's immune system produces an antibody to fight off the allergen. The amount of antibody can be measured by a blood test that will show how sensitive the patient is to a particular allergen. If the diagnosis is still in doubt, the patient can inhale a suspect allergen while using a spirometer to detect airway narrowing. Spirometry can also be repeated after a bout of exercise if exercise-induced asthma is a possibility. A chest x ray will help rule out other disorders.

Treatment

Once asthma is diagnosed, a treatment plan should be initiated as quickly as possible to manage asthma symptoms.

In most cases, asthma treatment is managed by the child's pediatrician. Referral to an asthma specialist should be considered if:

  • There has been a life-threatening asthma attack or severe, persistent asthma.
  • Treatment for three to six months has not met its goals.
  • Some other condition, such as nasal polyps or chronic lung disease, complicates the asthma.
  • Special tests, such as allergy skin testing or an allergen challenge, are needed.
  • Intensive steroid therapy has been necessary.

The first step in bringing asthma under control is to reduce or avoid exposure to known allergens or triggers as much as possible. Treatment goals for all patients with asthma are to prevent troublesome symptoms, maintain lung function as close to normal as possible, avoid emergency room visits or hospitalizations, allow participation in normal activitiesincluding exercise and those requiring exertionand improve the quality of life.

Medications

The best drug treatment plan will control asthmatic symptoms while causing few or no side effects. The child's doctor will work with the parent to determine the drugs that are most appropriate and may be the most effective, based on the severity of symptoms. Age and the presence of other medical conditions may affect the drugs selected.

Two types of asthma medications include short-acting, quick relief, medications and long-acting, controller, medications. Quick relief medications are used to treat asthma symptoms when they occur. They relieve symptoms rapidly and are usually taken only when needed. Long-acting medications are preventative and are taken daily to help a patient achieve and maintain control of asthma symptoms.

Asthma treatment guidelines may be based on these symptom classifications:

  • Mild intermittent: No daily medication is needed but a short-acting beta2 agonist may be used when needed to treat symptoms.
  • Mild persistent: Daily long-term medication may be prescribed.
  • Moderate persistent: Two medications may be prescribed, including a long-term medication to control inflammation and a short-acting medication to use when symptoms are more severe.
  • Severe persistent: Multiple long-term control medications are required.

When asthma symptoms worsen, medication is increased. When asthma symptoms are controlled, less medication is needed. It is very important to discuss any desired changes to the medication schedule with the doctor. The medication dose should never be changed without the doctor's approval. The condition can worsen if certain medications are not taken.

Inhaled medications have a special inhaler that meters the dose. The inhaler may have a spacer that holds the burst of medication until it is inhaled. Patients will be instructed on how to properly use an inhaler to ensure that it will deliver the right amount of medication.

A home nebulizer, also known as a breathing machine, may be used to deliver asthma medications at home. The nebulizer changes medication from liquid form to a mist. The child wears a face mask to breathe in the medications. Nebulizer treatments generally take seven to 10 minutes.

Quick relief medications include short-acting, inhaled beta2 agonists and anticholinergics. Long-acting medications include leukotriene modifiers, mast cell stabilizers, inhaled and oral corticosteroids, long-acting beta2 agonists, and methylxanthines.

SHORT-ACTING BETA-2 AGONISTS These drugs, which are bronchodilators, open the airways by relaxing the muscles around the airways that have tightened (bronchospasm). The short-acting forms of beta-receptor agonists are the best choice for relieving sudden attacks of asthma and for preventing attacks triggered by exercise. These drugs generally start acting within minutes, but their effects last only four to six hours (although longer-acting forms are being developed). They may be taken by mouth, inhaled, or injected.

ANTICHOLINERGICS Anticholinergics are medications that open the airways by relaxing the muscle bands that tighten around the airways. They also suppress mucus production. They do not provide immediate relief, but can be used to control severe attacks when added to an inhaled beta-receptor agonist.

LEUKOTRIENE MODIFIERS Leukotriene modifiers, also called antileukotrienes, can be used in place of steroids for older children who have a mild degree of asthma that persists. They work by counteracting leukotrienes, substances released by white blood cells in the lung that cause the air passages to constrict and promote mucus secretion.

MAST CELL STABILIZERS Available only in inhaled form, mast cell stabilizers, such as cromolyn and nedocromil, prevent asthma symptoms. These anti-inflammatory drugs are often given to children as the initial treatment to prevent asthmatic attacks over the long term. They can also prevent attacks when given before exercise or when exposure to an allergen cannot be avoided. They are not effective until three to four weeks after therapy is started. These medications need to be taken two to four times a day.

STEROIDS These drugs, which resemble natural body hormones, block inflammation. Steroids are extremely effective in relieving asthma symptoms and can control even severe cases over the long term while maintaining good lung function. When steroids are taken by inhalation for a long period, asthma attacks become less frequent as the airways become less sensitive to allergens. Besides being inhaled, steroids may be taken by mouth or injected, to rapidly control severe asthma. Steroids are the strongest class of asthma medications and can cause numerous side-effects, including bleeding from the stomach, loss of calcium from bones, cataracts in the eye, and a diabetes-like state. Patients using steroids for lengthy periods also may have problems with wound healing, weight gain, and mental disorders. In children, growth may be slowed. To prevent serious side effects, the child will have periodic monitoring tests.

LONG-ACTING BETA-2 AGONISTS Long-acting beta-2 agonists are used for better controlnot reliefof asthma symptoms. The medications take longer to work and the effects last longer, up to 12 hours.

METHYLXANTHINES Theophylline is the chief methylxanthine drug. It may exert some anti-inflammatory effect, and is especially helpful in controlling nighttime symptoms of asthma. If a patient cannot use an inhaler to maintain long-term control, sustained-release theophylline is a good alternative. The blood levels of the drug must be measured periodically, as too high of a dose can cause an abnormal heart rhythm or convulsions.

OTHER DRUGS Some inhalers contain a combination of two different medications that can be delivered together to shorten treatment times and decrease the number of inhalers that need to be purchased. Clinical trials are continuously evaluating new asthma medications.

IMMUNOTHERAPY If a patient's asthma is caused by an allergen that cannot be avoided, or if medications have not been effective in controlling symptoms, immunotherapy (also called allergy shots ) may be considered. Immunotherapy is helpful when symptoms tend to occur throughout all or most of the year. Typically, increasing amounts of the allergen are injected over a period of three to five years, so that the body can build up an effective immune response. There is a risk that this treatment may cause the airways to become narrowed and bring on an asthmatic attack.

An international conference, Immunotherapy in Allergic Asthma, hosted by the American College of Allergy, Asthma, and Immunology (ACAII) in 2000 concluded that immunotherapy is an effective treatment for allergic asthma and can prevent the onset of asthma in children with allergic rhinitis . The Preventive Allergy Treatment study, published in 2002, confirmed the ACAII conference conclusions, documenting that immunotherapy reduces the risk of developing asthma and reduces lung airway inflammation in children with hay fever, a condition that predisposes them to asthma.

Managing asthmatic attacks

Urgent measures to control asthma attacks and ongoing treatment to prevent attacks are equally important. No matter how severe a person's asthma, quick-relief medications must be readily available to treat acute symptoms. If the patient's asthma symptoms are present most of the time, an anti-inflammatory medication should be used regularly.

A severe asthma attack should be treated as quickly as possible. It is most important for a patient suffering an acute attack to be given extra oxygen. Rarely, it may be necessary to use a mechanical ventilator to help the patient breathe. A beta-receptor agonist is inhaled repeatedly or continuously. A steroid is given if the patient's symptoms do not improve promptly and completely. Steroids also may help if a viral infection caused severe asthmatic symptoms. A course of steroid therapy, given after the attack is over, will make a recurrence less likely.

Starting treatment at home, rather than in a hospital, minimizes delays and helps the patient gain a sense of control over the disease. When deciding whether a patient should be hospitalized, the past history of acute attacks, severity of symptoms, current medication, and availability of adequate support at home must be taken into account.

Maintaining control

Children with asthma should follow up with their doctor every one to six months, depending on the frequency of attacks. During the follow-up visits, the child's lung function should be measured by spirometry to make sure treatment goals are being met. Once asthma has been controlled for several weeks or months, the child's physician may adjust the medication dosage. If there is no clear improvement with the current treatment plan, another treatment plan should be established.

All patients with asthma should learn how to monitor their symptoms so that they will know when an attack is starting. Symptoms can be monitored with a peak flow meter (also called a peak expiratory flow meter). To effectively follow the instructions for using a peak flow meter, the child should be at least five years old. The peak flow meter measures the child's airflow when he or she blows into it quickly and forcefully. The peak flow meter can be used to determine when to call the doctor or seek emergency care.

Knowing the child's allergens or triggers will help parents reduce exposure by making improvements in the home environment. Specific guidelines may include reducing indoor humidity, using allergen-impermeable bedding covers, minimizing the use of carpet and upholstered furniture, and minimizing pet exposure. For more information, see the Prevention section.

All patients with asthma should have a written action plan to follow if symptoms suddenly become worse, including how to adjust medication and when to seek medical help. A Northwestern University study indicates that asthma symptoms and the need for emergency medications in children can be greatly reduced by using a planned-care method. This method involves regularly scheduled visits with specially trained nurses to help the patient and family learn how to anticipate and improve the management of asthma symptoms.

The health care provider should write out an asthma treatment plan for the child's school personnel or care providers. The plan should detail the early warning signs of an asthma attack, what medications the student uses and how they are taken, and when to contact the doctor or seek emergency care. Children with asthma often need medication at school to control acute symptoms or to prevent exercise-induced attacks. Proper management will usually allow a child to take part in play activities. Only as a last resort should activities be limited.

Alternative treatment

Alternative and complementary therapies include approaches considered to be outside the mainstream of traditional health care. Alternative treatments for asthma include yoga to control breathing and relieve stress and acupuncture to reduce asthma attacks and improve lung function. Biofeedback, which teaches patients how to direct mental thoughts to influence physical functions, may be helpful for some patients. For example, learning to increase the amount of air inhaled may help some patients reduce fear and anxiety. Some Chinese traditional herbs, such as ding-chan tang, have been thought to help decrease inflammation and relieve bronchospasm.

Before learning or practicing any particular technique, it is important for the parent or caregiver and child to learn about the therapy, its safety and effectiveness, potential side effects, and the expertise and qualifications of the practitioner. Although some practices are beneficial, others may be harmful to certain patients.

Relaxation techniques and dietary supplements should not be used as a substitute for medical therapies prescribed by a doctor. Parents should discuss these alternative treatments with the child's doctor to determine the techniques and remedies that may be beneficial.

Nutritional concerns

Some children have reportedly experienced improved symptoms by limiting dairy products and sugar in the diet. Some studies show that vitamin C helps improve asthma symptoms.

Food additives may trigger asthma symptoms in some children, although this is rare. If the parent suspects that certain foods trigger asthma symptoms in the child, the pediatrician may recommend keeping a food diary for a few weeks to identify problematic foods. Allergy skin testing may be recommended to rule out foods that may trigger asthma symptoms.

Prognosis

Although there is no cure for asthma, it can be treated and managed. Most patients with asthma respond well and are able to lead relatively normal lives when the best drug or combination of drugs is found. Asthma should not be a progressive, disabling disease; a child with asthma can have normal or near-normal lung function with the proper treatment.

Some children stop having attacks as they grow and their airways get bigger. About 50 percent of children have less frequent and less severe attacks as they grow older. However, symptoms can recur when the child reaches his or her thirties or forties.

A small number of patients will have progressively more difficulty breathing. These patients have an increased risk of respiratory failure, and they must receive intensive treatment. Asthma can be a deadly disease if it is not managed properly; an estimated 5,000 people die each year from asthma or its complications.

Prevention

Prolonged breastfeeding in infants for six to 12 months has been shown to reduce the child's likelihood for developing persistent asthma.

Minimizing exposure to allergens

There are a number of ways parents can reduce or prevent a child's exposure to the common allergens and irritants that provoke asthmatic attacks:

  • If the child is sensitive to a family pet, the pet should be removed or kept out of the child's bedroom (with the bedroom door closed). The pet should be kept away from carpets and upholstered furniture. All products made from feathers should be removed. An air filter should be used on air ducts in the child's room.
  • To reduce exposure to house dust mites, wall-to-wall carpeting should be removed, humidity should be kept down, and special pillow and mattress covers should be used. The number of stuffed toys should be reduced, and they should be washed in hot water weekly. Bedding should also be washing weekly in hot water, and dried in a dryer on the hot setting. The child should not be allowed to sleep on upholstered furniture. Carpets should be removed from the child's bedroom.

KEY TERMS

Acute Refers to a disease or symptom that has a sudden onset and lasts a relatively short period of time.

Allergen A foreign substance that provokes an immune reaction or allergic response in some sensitive people but not in most others.

Allergy A hypersensitivity reaction in response to exposure to a specific substance.

Alveoli The tiny air sacs clustered at the ends of the bronchioles in the lungs in which oxygen-carbon dioxide exchange takes place.

Anti-inflammatory A class of drugs, including nonsteroidal anti-inflammatory drugs (NSAIDs) and corticosteroids, used to relieve swelling, pain, and other symptoms of inflammation.

Atopy A state that makes persons more likely to develop allergic reactions of any type, including the inflammation and airway narrowing typical of asthma.

Bronchial tubes The major airways to the lungs and their main branches.

Bronchioles Small airways extending from the bronchi into the lobes of the lungs.

Bronchospasm The tightening of the muscle bands that surround the airways, causing the airways to narrow.

Dander Loose scales shed from the fur or feathers of household pets and other animals. Dander can cause allergic reactions in susceptible people.

Dust mites Tiny insects, unable to be seen without a microscope, that are present in carpet, stuffed animals, upholstered furniture, and bedding, including pillows, mattresses, quilts, and other bed covers. Dust mites are one of the most common asthma triggers. They grow best in areas with high humidity.

Hypersensitivity A condition characterized by an excessive response by the body to a foreign substance. In hypersensitive individuals even a tiny amount of allergen can cause a severe allergic reaction.

Inflammation Pain, redness, swelling, and heat that develop in response to tissue irritation or injury. It usually is caused by the immune system's response to the body's contact with a foreign substance, such as an allergen or pathogen.

Peak flow measurement Measurement of the maximum rate of airflow attained during a forced vital capacity determination.

Pollen A fine, powdery substance released by plants and trees; an allergen.

Spirometry A test using an instrument called a spirometer that measures how much and how fast the air is moving in and out of a patient's lungs. Spirometry can help a physician diagnose a range of respiratory diseases, monitor the progress of a disease, or assess a patient's response to treatment.

Trigger Any situation or substance that causes asthma symptoms to start or become worse.

  • If cockroach allergen is causing asthma attacks, the roaches should be killed (using poison, traps, or boric acid rather than chemicals). Food or garbage should not be exposed.
  • Indoor air may be kept clean by vacuuming carpets once or twice a week (with the child absent), avoiding humidifiers, and using air conditioning during warm weather (so that windows remain closed).
  • To reduce exposure to mold, indoor humidity should be decreased to less than 50 percent, leaky faucets and pipes should be repaired, and vaporizers avoided.
  • Family members should quit smoking and others should not be allowed to smoke in the house or near the child.
  • The child should not exercise outdoors when air pollution levels are high.

Parental concerns

Parents should take an open and honest approach when explaining asthma to their child. They should explain that asthma does not define or limit the child. The success of the child's treatment plan will depend on parental guidance and support. As a child ages, the responsibility for personal asthma management can be increased. For example, toddlers can mimic treatment on a toy or doll; preschoolers can help parents in peak flow monitoring and discuss symptoms with them; schoolaged children can begin to take medications on their own (while supervised); and adolescents can be nearly independent in following the structured management plan.

Parents should stress the consequences of improper symptom management with their child. The main concern with older children is peer pressure and the desire to fit in; therefore, symptoms may not be reported accurately and medications may not be taken to avoid comments from peers or appearing different. Parents may want to counteract peer pressure by offering a contract that outlines the management plan and lists specific rewards and consequences.

Parents should work with school personnel to foster a supportive environment that so the child's symptoms can be managed properly. A specific action plan can be developed for school by the child's doctor. Parents should inform school personnel about the child's specific allergens and asthma triggers so steps can be taken to help the child avoid them at school. Students who are able to recognize symptoms requiring medication and know how to use their inhaler properly should be permitted to keep the medication with them. For younger children, parents must ensure that school personnel know how to administer the child's medications.

Asthma should not be used as an excuse to avoid exercise. Sometimes children with asthma avoid school activities because they are afraid of being embarrassed if symptoms occur. Parents should encourage athletic or physical activity participation and talk to gym teachers or coaches to ensure they understand the child's symptoms and treatment protocol. They should make sure the child knows what to do if exercise causes symptoms. Swimming is generally well-tolerated by many people with asthma because it is usually performed in a warm, moist environment. Other activities that involve brief, intermittent periods of exertion, such as volleyball, gymnastics, baseball, walking, and wrestling are usually well-tolerated. Cold-weather sports , such as skiing, ice skating, or hockey, may be not be tolerated as well. The child's doctor can provide specific exercise recommendations and guidelines.

See also Allergy shots.

Resources

BOOKS

American Medical Association. The American Medical Association Essential Guide for Asthma (Better Health for 2003) Pocket, 2000.

Fanta, Christopher H., et al. The Harvard Medical School Guide to Taking Control of Asthma. New York, NY: Free Press, 2003.

Wolf, Rauol. Essential Pediatric Allergy, Asthma, and Immunology. New York, NY: McGraw-Hill Professional, 2004.

ORGANIZATIONS

Allergy and Asthma Network/Mothers of Asthmatics America, Inc. 2751 Prosperity Ave., Suite 150, Fairfax, VA 22031. (800) 878-4403. Web site: <www.aanma.org.>.

American Academy of Allergy, Asthma and Immunology (AAAAI). 611 E. Wells St., Milwaukee, WI 53202. (800) 822-ASTHMA or (414) 272-6071. Web site: <www.aaaai.org>.

American College of Asthma, Allergy and Immunology (AACI). 85 W. Algonquin Rd., Suite 550, Arlington Hts., IL 60005. (800) 842-7777. Web site: <www.aaci.org.>.

American Lung Association. 1740 Broadway, New York, NY 10019. (800) 586-4872. Web site: <www.lungusa.org.>.

Asthma and Allergy Foundation of America. 1233 20th Street, NW, Suite 402, Washington, DC 20036. (800) 727-8462 or (202) 466-7643. Web site: <www.aafa.org>.

National Asthma Education Program. National Heart, Lung and Blood Institute Information Center. P.O. Box 30105, Bethesda, MD 20824-0105. (301) 592-8573. Web site: <www.nhlbi.nih.gov/about/naepp/>.

National Institute of Allergy and Infectious Diseases. NIAID Office of Communications and Public Liaison, Building 31, Room 7A-50, 31 Center Dr., MSC 2520, Bethesda, MD 20892-2520. Web site: <www.niaid.nih.gov>.

David A. Cramer, M.D. Angela M. Costello

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Asthma

Asthma

Definition

Asthma is a chronic inflammatory disease of the airways in the lungs. This inflammation periodically causes the airways to narrow, producing wheezing and breath-lessness sometimes to the point where the patient gasps for air. This obstruction of the air flow either stops spontaneously or responds to a wide range of treatments. Continuing inflammation makes asthmatics hyper-responsive to such stimuli as cold air, exercise , dust, pollutants in the air, and even stress or anxiety .

Description

Between 16 and 17 million Americans have asthma and the number has been rising since 1980. As many as 9 million U.S. children under age 18 may have asthma. Blacks, Hispanics, American Indians, and Alaskan natives had higher rates of asthma-control problems than whites or Asians in the United States.

The changes that take place in the lungs of asthmatics make their airways (the bronchi and the smaller bronchioles) hyper-reactive to many different types of stimuli that do not affect healthy lungs. In an asthma attack, the muscle tissue in the walls of the bronchi go into spasm, and the cells that line the airways swell and secrete mucus into the air spaces. Both these actions cause the bronchi to narrow, a change that is called bronchoconstriction. As a result, an asthmatic person has to make a much greater effort to breathe.

Cells in the bronchial walls, called mast cells, release certain substances that cause the bronchial muscle to contract and stimulate mucus formation. These substances, which include histamine and a group of chemicals called leukotrienes, also bring white blood cells into the area. Many patients with asthma are prone to react to substances such as pollen, dust, or animal dander; these are called allergens. Many people with asthma do not realize that allergens are triggering their attacks. On the other hand, asthma also affects many patients who are not allergic in this way.

Asthma usually begins in childhood or adolescence, but it also may first appear in adult life. While the symptoms may be similar, certain important aspects of asthma are different in children and adults. When asthma begins in childhood, it often does so in a child who is likely, for genetic reasons, to become sensitized to common allergens in the environment. Such a child is known as an atopic person. In 2004, scientists in Helsinki, Finland, identified two new genes that cause atopic asthma. The discovery might lead to earlier prediction of asthma in children and adults. When these children are exposed to dust, animal proteins, fungi, or other potential allergens, they produce a type of antibody that is intended to engulf and destroy the foreign materials. This has the effect of making the airway cells sensitive to particular materials. Further exposure can lead rapidly to an asthmatic response. This condition of atopy is present in at least one third and as many as one half of the general population. When an infant or young child wheezes during viral infections , the presence of allergy (in the child or a close relative) is a clue that asthma may well continue throughout childhood.

Allergenic materials may also play a role when adults become asthmatic. Asthma can start at any age and in a wide variety of situations. Many adults who are not allergic have such conditions as sinusitis or nasal polyps, or they may be sensitive to aspirin and related drugs. Another major source of adult asthma is exposure at work to animal products, certain forms of plastic, wood dust, metals, and environmental pollution.

Causes & symptoms

In most cases, asthma is caused by inhaling an allergen that sets off the chain of biochemical and tissue changes leading to airway inflammation, bronchoconstriction, and wheezing. Because avoiding (or at least minimizing) exposure is the most effective way of treating asthma, it is vital to identify which allergen or irritant is causing symptoms in a particular patient. Once asthma is present, symptoms can be set off or made worse if the patient also has rhinitis (inflammation of the lining of the nose) or sinusitis. When, for some reason, stomach acid passes back up the esophagus in a reaction called acid reflux, this condition also can make asthma worse. In addition, a viral infection of the respiratory tract can inflame an asthmatic reaction. Aspirin and drugs called beta-blockers, often used to treat high blood pressure, also can worsen the symptoms of asthma. But the most important inhaled allergens giving rise to attacks of asthma are:

  • animal dander
  • dust mites
  • fungi (molds) that grow indoors
INHALED ALLERGENS MOST OFTEN TRIGGERING ASTHMA ATTACKS
Air pollutants
Animal dander
Cockroach allergens
Dust mites
Indoor fungi (molds)
Occupational allergens such as chemicals, fumes, particles of industrial materials
Pollen
  • cockroach allergens
  • pollen
  • occupational exposure to chemicals, fumes, or particles of industrial materials
  • tobacco smoke
  • air pollutants

In addition, there are three important factors that regularly produce attacks in certain asthmatic patients, and they may sometimes be the sole cause of symptoms. They are:

  • inhaling cold air (cold-induced asthma)
  • exercise-induced asthma (in certain children, asthma attacks are caused simply by exercising)
  • stress or a high level of anxiety

Wheezing often is obvious, but mild asthmatic attacks may be confirmed when the physician listens to the patient's chest with a stethoscope. Besides wheezing and being short of breath, the patient may cough or report a feeling of tightness in the chest. Children may have itching on their back or neck at the start of an attack. Wheezing often is loudest when the patient exhales. Some asthmatics are free of symptoms most of the time but may occasionally be short of breath for a brief time. Others spend much of their days (and nights) coughing and wheezing until properly treated. Crying or even laughing may bring on an attack. Severe episodes often are seen when the patient gets a viral respiratory tract infection or is exposed to a heavy load of an allergen or irritant. Asthmatic attacks may last only a few minutes or can go on for hours or even days. Being short of breath may cause a patient to become very anxious, sit upright, lean forward, and use the muscles of the neck and chest wall to help breathe. The patient may be able to say only a few words at a time before stopping to take a breath. Confusion and a bluish tint to the skin are clues that the

OCCUPATIONS ASSOCIATED WITH ASTHMA
Animal Handling
Bakeries
Health Care
Jewelry Making
Laboratory Work
Manufacturing Detergents
Nickel Plating
Soldering
Snow Crab and Egg Processing
Tanneries

oxygen supply is much too low and that emergency treatment is needed. In a severe attack, some of the air sacs in the lung may rupture so that air collects within the chest, which makes it even harder to breathe. The good news is that almost always, even patients with the most severe attacks will recover completely.

Diagnosis

Apart from listening to the patient's chest, the examiner should look for maximum chest expansion while taking in air. Hunched shoulders and contracting neck muscles are other signs of narrowed airways. Nasal polyps or increased amounts of nasal secretions are often noted in asthmatic patients. Skin changes, like dermatitis or eczema , are a clue that the patient has allergic problems. Inquiring about a family history of asthma or allergies can be a valuable indicator of asthma. A test called spirometry measures how rapidly air is exhaled and how much is retained in the lungs. Repeating the test after the patient inhales a drug that widens the air passages (a bronchodilator) will show whether the narrowing of the airway is reversible, which is a very typical finding in asthma. Often patients use a related instrument, called a peak flow meter, to keep track of asthma severity when at home.

Frequently, it is difficult to determine what is triggering asthma attacks. Allergy skin testing may be used, although an allergic skin response does not always mean that the allergen being tested is causing the asthma. Also, the body's immune system produces an antibody to fight off the allergen, and the amount of antibody can be measured by a blood test. The blood test will show how sensitive the patient is to a particular allergen. If the diagnosis is still in doubt, the patient can inhale a suspect allergen while using a spirometer to detect airway narrowing. Spirometry also can be repeated after a bout of exercise if exercise-induced asthma is a possibility. A chest x-ray will help rule out other disorders.

Treatment

There are many alternative treatments available for asthma that have shown promising results. One strong argument for these treatments is that they try to avoid the drugs that allopathic treatment (combating disease with remedies to produce effects different from those produced by the disease) relies upon, which can be toxic and addictive. Mainstream journals have reported on the toxicity of asthma pharmaceuticals. A 1995 New Zealand study showed that before 1940, death from asthma was very low, but that the death rate promptly increased with the introduction of bronchodilators. The New England Journal of Medicine in 1992 reported that albuterol and other asthma drugs cause the lungs to deteriorate when used regularly. A 1989 study in the Annals of Internal Medicine showed that respiratory therapists, who are exposed to bronchodilator sprays, develop asthma five times more often than other healthcare professionals, which could imply that the drugs themselves may induce asthma. Theophylline, another popular drug, has been reported to cause personality changes in users. Steroids can also have negative effects on many systems in the body, particularly the hormonal system. Thus, natural and non-toxic methods for treating asthma are the preferred first choice of alternative practitioners, while drugs are used to manage extreme cases and emergencies.

Alternative medicine tends to view asthma as the body's protective reaction to environmental agents and pollutants. As such, the treatment goal is often to restore balance to and strengthen the entire body and provide specific support to the lungs, immune and hormonal systems. Asthma sufferers can help by keeping a diary of asthma attacks in order to determine environmental and emotional factors that may be contributing to their condition.

Alternative treatments have minimal side effects, are generally inexpensive, and are convenient forms of selftreatment. They also can be used alongside allopathic treatments to improve their effectiveness and lessen their negative side effects.

Dietary and nutritional therapies

Some alternative practitioners recommend cutting down on or eliminating dairy products from the diet, as

these increase mucus secretion in the lungs and are sources of food allergies. Other recommendations include avoiding processed foods, refined starches and sugars, and foods with artificial additives and sulfites. Diets should be high in fresh fruits, vegetables, and whole grains, and low in salt. Asthma sufferers should experiment with their diets to determine if food allergies are playing a role in their asthma. Some studies have shown that a sustained vegan (zero animal foods) diet can be effective for asthma, as it does not contain the animal products that frequently cause food allergies and contain chemical additives. A vegan diet also eliminates a fatty acid called arachidonic acid, which is found in animal products and is believed to contribute to allergic reactions. A 1985 Swedish study showed that 92% of patients with asthma improved significantly after one year on a vegan diet. On the other hand, some people feel weaker on a vegan diet. In addition, many people are allergic to vegetables rather than to meat.

Plenty of water should also be drunk by asthma sufferers, as water helps to keep the passages of the lungs moist. Onions and garlic contain quercetin, a flavonoid (a chemical compound/biological response modifier) that inhibits the release of histamine, and should be a part of an asthmatic's diet. Quercetin also is available as a supplement, and should be taken with the digestive enzyme bromelain to increase its absorption.

As nutritional therapy, vitamins A, C and E have been touted as important. Also, the B complex vitamins, particularly B6 and B12, may be helpful for asthma, as well as magnesium, selenium , and an omega-3 fatty acid supplement such as flaxseed oil. A good multivitamin supplement also is recommended. In 2004, a study of supplements at Cornell University showed that high levels of beta-carotene and vitamin C along with selenium lowered risk of asthma. However, the same study found that vitamin E had no effect.

Herbal remedies

Chinese medicine has traditionally used ma huang, or ephedra , for asthma attacks. It contains ephedrine, which is a bronchodilator used in many drugs. However, the U.S. Food and Drug Administration (FDA) issued a ban on the sale of ephedra that took effect in April 2004 because it was shown to raise blood pressure and stress the circulatory system, resulting in heart attacks and strokes for some users. Ginkgo has been shown to reduce the frequency of asthma attacks, and licorice is used in Chinese medicine as a natural decongestant and expectorant. There are many formulas used in traditional Chinese medicine to prevent or ease asthma attacks, depending on the specific Chinese diagnosis given by the practitioner. For example, ma huang is used to treat socalled "wind-cold" respiratory ailments.

Other herbs used for asthma include lobelia , also called Indian tobacco; nettle , which contains a natural antihistamine; thyme ; elecampane mullein : feverfew ; passionflower : saw palmetto : and Asian ginseng. Coffee and tea have been shown to reduce the severity of asthma attacks because caffeine works as a bronchodilator. Tea also contains minute amounts of theophylline, a major drug used for asthma. Ayurvedic (traditional East Indian) medicine recommends the herb Tylophora asthmatica.

Mind/body approaches

Mind/body medicine has demonstrated that psychological factors play a complex role in asthma. Emotional stress can trigger asthma attacks. Mind/body techniques strive to reduce stress and help asthma sufferers manage the psychological component of their condition. A 1992 study by Dr. Erik Peper at the Institute for Holistic Healing Studies in San Francisco used biofeedback , a treatment method that uses monitors to reveal physiological information to patients, to teach relaxation and deep breathing methods to 21 asthma patients. Eighty percent of them subsequently reported fewer attacks and emergency room visits. A 1993 study by Kaiser Permanente in Northern California worked with 323 adults with moderate to severe asthma. Half the patients got standard care while the other half participated in support groups. The support group patients had cut their asthma-related doctor visits in half after two years. Some other mind/body techniques used for asthma include relaxation methods, meditation, hypnotherapy ,, mental imaging, psychotherapy , and visualization.

Yoga and breathing methods

Studies have shown that yoga significantly helps asthma sufferers, with exercises specifically designed to expand the lungs, promote deep breathing, and reduce stress. Pranayama is the yogic science of breathing, which includes hundreds of deep breathing techniques. These breathing exercises should be done daily as part of any treatment program for asthma, as they are a very effective and inexpensive measure.

Controlled exercise

Many people believe that those with asthma should not exercise. This is particularly true among parents of children with asthma. In a 2004 study, researchers reported that 20% of children with asthma do not get enough exercise. Many parents believe it is dangerous for their children with asthma to exercise, but physical activity benefits all children, including those with asthma. Parents should work with the child's healthcare provider and any coach or organized sport leader to carefully monitor his or her activities.

Acupuncture

Acupuncture can be an effective treatment for asthma. It is used in traditional Chinese medicine along with dietary changes. Acupressure can also be used as a self-treatment for asthma attacks and prevention. The Lung 1 points, used to stimulate breathing, can be easily found on the chest. These are sensitive, often knotted spots on the muscles that run horizontally about an inch below the collarbone, and about two inches from the center of the chest. The points can be pressed in a circular manner with the thumbs, while the head is allowed to hang forward and the patient takes slow, deep breaths. Reflexology also uses particular acupressure points on the hands and feet that are believed to stimulate the lungs.

Other treatments

Aromatherapists recommend eucalyptus, lavender, rosemary , and chamomile as fragrances that promote free breathing. In Japan, a common treatment for asthma is administering cold baths. This form of hydrotherapy has been demonstrated to open constricted air passages. Massage therapies such as Rolfing can help asthma sufferers as well, as they strive to open and increase circulation in the chest area. Homeopathy uses the remedies Arsenicum album, Kali carbonicum, Natrum sulphuricum, and Aconite.

Allopathic treatment

Allopaths recommend that asthma patients should be periodically examined and have their lung functions measured by spirometry. The goals are to prevent troublesome symptoms, to maintain lung function as close to normal as possible, and to allow patients to pursue their normal activities, including those requiring exertion. The best drug therapy is that which controls asthmatic symptoms while causing few or no side effects.

Drugs

The chief methylxanthine drug is theophylline. It may exert some anti-inflammatory effect and is especially helpful in controlling nighttime symptoms of asthma. When, for some reason, a patient cannot use an inhaler to maintain long-term control, sustained-release theophylline is a good alternative. The blood levels of the drug must be measured periodically, as too high a dose can cause an abnormal heart rhythm or convulsions.

Beta-receptor agonists (drugs that trigger cell response) are bronchodilators. They are the drugs of choice for relieving sudden attacks of asthma and for preventing attacks from being triggered by exercise. Some agonists, such as albuterol, act mainly in lung cells and have little effect on the heart and other organs. These drugs generally start acting within minutes, but their effects last only four to six hours. They may be taken by mouth, inhaled, or injected. In 2004, a new lower concentration of albuterol was approved by the FDA for children ages two to 12.

Steroids are drugs that resemble natural body hormones. They block inflammation and are effective in relieving symptoms of asthma. When steroids are taken by inhalation for a long period, asthma attacks become less frequent as the airways become less sensitive to allergens. Steroids are the strongest medicine for asthma, and can control even severe cases over the long term and maintain good lung function. However, steroids can cause numerous side effects, including bleeding from the stomach, loss of calcium from bones, cataracts in the eye, and a diabetes-like state. Patients using steroids for lengthy periods may also have problems with wound healing, may gain weight, and may suffer mental problems. In children, growth may be slowed. Besides being inhaled, steroids may be taken by mouth or injected, to rapidly control severe asthma.

Leukotriene modifiers are among a newer type of drug that can be used in place of steroids, for older children or adults who have a mild degree of persistent asthma. They work by counteracting leukotrienes, which are substances released by white blood cells in the lung that cause the air passages to constrict and promote mucus secretion. Other drugs include cromolyn and nedocromil, which are anti-inflammatory drugs that often are used as initial treatments to prevent long-term asthmatic attacks in children. Montelukast sodium (Singulair) is a drug taken daily that is used to help prevent asthma attacks rather than to treat an acute attack. In 2004, the FDA approved an oral granule formula of Singulair for young children.

If a patient's asthma is caused by an allergen that cannot be avoided and it has been difficult to control symptoms by drugs, immunotherapy may be worth trying. In a typical course of immunotherapy, increasing amounts of the allergen are injected over a period of three to five years, so that the body can build up an effective immune response. There is a risk that this treatment may itself cause the airways to become narrowed and bring on an asthmatic attack. Not all experts are enthusiastic about immunotherapy, although some studies have shown that it reduces asthmatic symptoms caused by exposure to dust mites, ragweed pollen, and cats.

Managing asthmatic attacks

A severe asthma attack should be treated as quickly as possible. It is most important for a patient suffering an acute attack to be given extra oxygen. Rarely, it may be necessary to use a mechanical ventilator to help the patient breathe. A beta-receptor agonist is inhaled repeatedly or continuously. If the patient does not respond promptly and completely, a steroid is given. A course of steroid therapy, given after the attack is over, will make a recurrence less likely.

Long-term allopathic treatment for asthma is based on inhaling a beta-receptor agonist using a special inhaler that meters the dose. Patients must be instructed in proper use of an inhaler to be sure that it will deliver the right amount of drug. Once asthma has been controlled for several weeks or months, it is worth trying to cut down on drug treatment, but this tapering must be done gradually. The last drug added should be the first to be reduced. Patients should be seen every one to six months, depending on the frequency of attacks. Starting treatment at home, rather than in a hospital, makes for minimal delay and helps the patient to gain a sense of control over the disease. All patients should be taught how to monitor their symptoms so that they will know when an attack is starting. Those with moderate or severe asthma should know how to use a flow meter. They also should have a written plan to follow if symptoms suddenly become worse, including how to adjust their medication and when to seek medical help. If more intense treatment is necessary, it should be continued for several days. When deciding whether a patient should be hospitalized, the physician must take into account the patient's past history of acute attacks, severity of symptoms, current medication, and the availability of good support at home.

Expected results

Most patients with asthma respond well when the best treatment or combination of treatments is found and they are able to lead relatively normal lives. Patients who take responsibility for their condition and experiment with various treatments have good chances of keeping symptoms minimal. Having urgent measures to control asthma attacks and ongoing treatment to prevent attacks are important as well. More than one half of affected children stop having attacks by the time they reach 21 years of age. Many others have less frequent and less severe attacks as they grow older. A small minority of patients will have progressively more trouble breathing. Because they run a risk of going into respiratory failure, they must receive intensive treatment.

Prevention

Prevention is extremely important in the treatment of asthma, which includes eliminating all possible allergens from the environment and diet. Homes and work areas should be as dust and pollutant-free as possible. Areas can be tested for allergens and high-quality air filters can be installed to clean the air. If the patient is sensitive to a family pet, removing the animal or at least keeping it out of the bedroom (with the bedroom door closed) is advised. Keeping the pet away from carpets and upholstered furniture, and removing all feathers also helps. To reduce exposure to dust mites, it is recommended to remove wall-to-wall carpeting, keep the humidity low, and use special pillows and mattress covers. Cutting down on stuffed toys, and washing them each week in hot water, is advised for children with asthma. If cockroach allergen is causing asthma attacks, controlling the roaches (using traps or boric acid rather than chemicals) can help.

It is important to not to leave food or garbage exposed. Keeping indoor air clean by vacuuming carpets once or twice a week (with the asthmatic person absent), and avoiding use of humidifiers is advised. Those with asthma should avoid exposure to tobacco smoke and should not exercise outside when air pollution levels are high. When asthma is related to exposure at work, taking all precautions, including wearing a mask and, if necessary, arranging to work in a safer area, is recommended. For chronic sufferers who live in heavily polluted areas, moving to less polluted regions may even be a viable alternative.

Resources

BOOKS

Bock, Steven J. Natural Relief for Your Child's Asthma. New York: HarperPerennial, 1999.

Cutler, Ellen W. Winning the War against Asthma and Allergies. New York: Delmar, 1998.

PERIODICALS

Allergy and Asthma Magazine. 702 Marshall St., Suite 611. Redwood City, CA 94063. (605) 780-0546.

"Allergy Season Can Mean Trouble." Respiratory Therapeutics Week (April 19, 2004):9.

"Asthma Antioxidants." Better Nutrition (May 2004):2627.

"Children with Asthma Inactive Due to Parental Health Beliefs, Disease Severity." Obesity, Fitness & Wellness Week (May 1, 2004):8.

"Identification of New Asthma Genes Demonstrates Model for Improved Patient Care." Drug Week (April 30, 2004):27.

McNamara, Daniel. "Singulair." Family Practice News (February 1, 2004):108109.

"Nine Million U.S. Children Diagnosed With Asthma, New Report Finds." Medical Letter on the CDC & FDA (April 25, 2004):11.

"Patent Granted for Pediatric Asthma Medication." Health & Medicine Week (April 12, 2004):552.

Ressel, Genevieve. "FDA Issues Regulation Prohibiting Sale of Dietary Supplements Containing Ephedra." American Family Physician (March 15, 2004):1343.

"U.S. Asthma Rates on the Rise." Medical Letter on the CDC & FDA (March 28, 2004):11.

ORGANIZATIONS

Asthma and Allergy Foundation of America. 1125 15th St. NW, Suite 502. Washington, DC 20005. 800-7ASTHMA. <http://www.aafa.org>.

Center for Complementary and Alternative Medicine Research in Asthma, Allergy, and Immunology. University of California at Davis. 3150B Meyer Hall. Davis, CA 95616. (916) 752-6575. <http://www-camra.ucdavis.edu>.

Douglas Dupler

Teresa G. Odle

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Asthma

Asthma

Definition

Asthma is a chronic (long-lasting) inflammatory disease of the airways. In those susceptible to asthma, this inflammation causes the airways to narrow periodically. This, in turn, produces wheezing and breathlessness, sometimes to the point where the patient gasps for air. Obstruction to air flow either stops spontaneously or responds to a wide range of treatments, but continuing inflammation makes the airways hyper-responsive to stimuli such as cold air, exercise, dust mites, pollutants in the air, and even stress and anxiety.

Description

Between 17 million and 26 million Americans have asthma, and the number seems to be increasing. In about 1992, the number with asthma was about 10 million, and had risen 42% from 1982, just 10 years prior. Not only is asthma becoming more frequent, but it also is a more severe disease than before, despite modern drug treatments. Asthma accounts for almost 500,000 hospitalizations, two million emergency department visits, and 5,000 deaths in the United States each year.

The changes that take place in the lungs of asthmatic persons makes the airways (the "breathing tubes," or bronchi and the smaller bronchioles ) hyperreactive to many different types of stimuli that don't affect healthy lungs. In an asthma attack, the muscle tissue in the walls of bronchi go into spasm, and the cells lining the airways swell and secrete mucus into the air spaces. Both these actions cause the bronchi to become narrowed (bronchoconstriction). As a result, an asthmatic person has to make a much greater effort to breathe in air and to expel it.

Cells in the bronchial walls, called mast cells, release certain substances that cause the bronchial muscle to contract and stimulate mucus formation. These substances, which include histamine and a group of chemicals called leukotrienes, also bring white blood cells into the area, which is a key part of the inflammatory response. Many patients with asthma are prone to react to such "foreign" substances as pollen, house dust mites, or animal dander; these are called allergens. On the other hand, asthma affects many patients who are not allergic in this way.

Asthma usually begins in childhood or adolescence, but it also may first appear during adult years. While the symptoms may be similar, certain important aspects of asthma are different in children and adults.

Child-onset asthma

Nearly one-third on the 17 to 26 million Americans with asthma are children. When asthma begins in childhood, it often does so in a child who is likely, for genetic reasons, to become sensitized to common allergens in the environment (atopic person). When these children are exposed to house-dust mites, animal proteins, fungi, or other potential allergens, they produce a type of antibody that is intended to engulf and destroy the foreign materials. This has the effect of making the airway cells sensitive to particular materials. Further exposure can lead rapidly to an asthmatic response. This condition of atopy is present in at least one-third and as many as one-half of the general population. When an infant or young child wheezes during viral infections, the presence of allergy (in the child or a close relative) is a clue that asthma may well continue throughout childhood.

Adult-onset asthma

Allergenic materials may also play a role when adults become asthmatic. Asthma can actually start at any age and in a wide variety of situations. Many adults who are not allergic have conditions such as sinusitis or nasal polyps, or they may be sensitive to aspirin and related drugs. Another major source of adult asthma is exposure at work to animal products, certain forms of plastic, wood dust, or metals.

Causes and symptoms

In most cases, asthma is caused by inhaling an allergen that sets off the chain of biochemical and tissue changes leading to airway inflammation, bronchoconstriction, and wheezing. Because avoiding (or at least minimizing) exposure is the most effective way of treating asthma, it is vital to identify which allergen or irritant is causing symptoms in a particular patient. Once asthma is present, symptoms can be set off or made worse if the patient also has rhinitis (inflammation of the lining of the nose) or sinusitis. When, for some reason, stomach acid passes back up the esophagus (acid reflux), this can also make asthma worse. A viral infection of the respiratory tract can also inflame an asthmatic reaction. Aspirin and a type of drug called beta-blockers, often used to treat high blood pressure, can also worsen the symptoms of asthma.

The most important inhaled allergens giving rise to attacks of asthma are:

  • animal dander
  • mites in house dust
  • fungi (molds) that grow indoors
  • cockroach allergens
  • pollen
  • occupational exposure to chemicals, fumes, or particles of industrial materials in the air

KEY TERMS

Allergen A foreign substance, such as mites in house dust or animal dander which, when inhaled, causes the airways to narrow and produces symptoms of asthma.

Atopy A state that makes persons more likely to develop allergic reactions of any type, including the inflammation and airway narrowing typical of asthma.

Hypersensitivity The state where even a tiny amount of allergen can cause the airways to constrict and bring on an asthmatic attack.

Spirometry A test using an instrument called a spirometer that shows how difficult it is for an asthmatic patient to breathe. Used to determine the severity of asthma and to see how well it is responding to treatment.

Inhaling tobacco smoke, either by smoking or being near people who are smoking, can irritate the airways and trigger an asthmatic attack. Air pollutants can have a similar effect. In addition, there are three important factors that regularly produce attacks in certain asthmatic patients, and they may sometimes be the sole cause of symptoms. They are:

  • inhaling cold air (cold-induced asthma)
  • exercise-induced asthma (in certain children, asthma is caused simply by exercising)
  • stress or a high level of anxiety

Wheezing is often obvious, but mild asthmatic attacks may be confirmed when the physician listens to the patient's chest with a stethoscope. Besides wheezing and being short of breath, the patient may cough and may report a feeling of "tightness" in the chest. Children may have itching on their back or neck at the start of an attack. Wheezing is often loudest when the patient breathes out, in an attempt to expel used air through the narrowed airways. Some asthmatics are free of symptoms most of the time but may occasionally be short of breath for a brief time. Others spend much of their days (and nights) coughing and wheezing, until properly treated. Crying or even laughing may bring on an attack. Severe episodes are often seen when the patient gets a viral respiratory tract infection or is exposed to a heavy load of an allergen or irritant. Asthmatic attacks may last only a few minutes or can go on for hours or even days (a condition called status asthmaticus).

Being short of breath may cause a patient to become very anxious, sit upright, lean forward, and use the muscles of the neck and chest wall to help breathe. The patient may be able to say only a few words at a time before stopping to take a breath. Confusion and a bluish tint to the skin are clues that the oxygen supply is much too low, and that emergency treatment is needed. In a severe attack that lasts for some time, some of the air sacs in the lung may rupture so that air collects within the chest. This makes it even harder to breathe in enough air.

Diagnosis

Apart from listening to the patient's chest, the examiner should look for maximum chest expansion while taking in air. Hunched shoulders and contracting neck muscles are other signs of narrowed airways. Nasal polyps or increased amounts of nasal secretions are often noted in asthmatic patients. Skin changes, like atopic dermatitis or eczema, are a tipoff that the patient has allergic problems.

Inquiring about a family history of asthma or allergies can be a valuable indicator of asthma. The diagnosis may be strongly suggested when typical symptoms and signs are present. A test called spirometry measures how rapidly air is exhaled and how much is retained in the lungs. Repeating the test after the patient inhales a drug that widens the air passages (a bronchodilator) will show whether the airway narrowing is reversible, which is a very typical finding in asthma. Often patients use a related instrument, called a peak flow meter, to keep track of asthma severity when at home.

Often, it is difficult to determine what is triggering asthma attacks. Allergy skin testing may be used, although an allergic skin response does not always mean that the allergen being tested is causing the asthma. Also, the body's immune system produces antibody to fight off the allergen, and the amount of antibody can be measured by a blood test. This will show how sensitive the patient is to a particular allergen. If the diagnosis is still in doubt, the patient can inhale a suspect allergen while using a spirometer to detect airway narrowing. Spirometry can also be repeated after a bout of exercise if exercise-induced asthma is a possibility. A chest x ray will help rule out other disorders.

Treatment

Patients should be periodically examined and have their lung function measured by spirometry to make sure that treatment goals are being met. These goals are to prevent troublesome symptoms, to maintain lung function as close to normal as possible, and to allow patients to pursue their normal activities including those requiring exertion. The best drug therapy is that which controls asthmatic symptoms while causing few or no side-effects.

Drugs

METHYLXANTHINES. The chief methylxanthine drug is theophylline. It may exert some anti-inflammatory effect, and is especially helpful in controlling nighttime symptoms of asthma. When, for some reason, a patient cannot use an inhaler to maintain long-term control, sustained-release theophylline is a good alternative. The blood levels of the drug must be measured periodically, as too high a dose can cause an abnormal heart rhythm or convulsions.

BETA-RECEPTOR AGONISTS. These drugs, which are bronchodilators, are the best choice for relieving sudden attacks of asthma and for preventing attacks from being triggered by exercise. Some agonists, such as albuterol, act mainly in lung cells and have little effect on other organs, such as the heart. These drugs generally start acting within minutes, but their effects last only four to six hours. Longer-acting brochodilators have been developed. They may last up to 12 hours. Bronchodilators may be taken in pill or liquid form, but normally are used as inhalers, which go directly to the lungs and result in fewer side effects.

STEROIDS. These drugs, which resemble natural body hormones, block inflammation and are extremely effective in relieving symptoms of asthma. When steroids are taken by inhalation for a long period, asthma attacks become less frequent as the airways become less sensitive to allergens. This is the strongest medicine for asthma, and can control even severe cases over the long term and maintain good lung function. Steroids can cause numerous side-effects, however, including bleeding from the stomach, loss of calcium from bones, cataracts in the eye, and a diabetes-like state. Patients using steroids for lengthy periods may also have problems with wound healing, may gain weight, and may suffer mental problems. In children, growth may be slowed. Besides being inhaled, steroids may be taken by mouth or injected, to rapidly control severe asthma.

LEUKOTRIENE MODIFIERS. Leukotriene modifiers (montelukast and zafirlukast) are a new type of drug that can be used in place of steroids, for older children or adults who have a mild degree of asthma that persists. They work by counteracting leukotrienes, which are substances released by white blood cells in the lung that cause the air passages to constrict and promote mucus secretion. Leukotriene modifiers also fight off some forms of rhinitis, an added bonus for people with asthma. However, they are not proven effective in fighting seasonal allergies.

OTHER DRUGS. Cromolyn and nedocromil are anti-inflammatory drugs that are often used as initial treatment to prevent asthmatic attacks over the long term in children. They can also prevent attacks when given before exercise or when exposure to an allergen cannot be avoided. These are safe drugs but are expensive, and must be taken regularly even if there are no symptoms. Anti-cholinergic drugs, such as atropine, are useful in controlling severe attacks when added to an inhaled beta-receptor agonist. They help widen the airways and suppress mucus production.

If a patient's asthma is caused by an allergen that cannot be avoided and it has been difficult to control symptoms by drugs, immunotherapy may be worth trying. Typically, increasing amounts of the allergen are injected over a period of three to five years, so that the body can build up an effective immune response. There is a risk that this treatment may itself cause the airways to become narrowed and bring on an asthmatic attack. Not all experts are enthusiastic about immunotherapy, although some studies have shown that it reduces asthmatic symptoms caused by exposure to house-dust mites, ragweed pollen, and cat dander.

Managing asthmatic attacks

A severe asthma attack should be treated as quickly as possible. It is most important for a patient suffering an acute attack to be given extra oxygen. Rarely, it may be necessary to use a mechanical ventilator to help the patient breathe. A beta-receptor agonist is inhaled repeatedly or continuously. If the patient does not respond promptly and completely, a steroid is given. A course of steroid therapy, given after the attack is over, will make a recurrence less likely.

Maintaining control

Long-term asthma treatment is based on inhaling a beta-receptor agonist using a special inhaler that meters the dose. Patients must be instructed in proper use of an inhaler to be sure that it will deliver the right amount of drug. Once asthma has been controlled for several weeks or months, it is worth trying to cut down on drug treatment, but this must be done gradually. The last drug added should be the first to be reduced. Patients should be seen every one to six months, depending on the frequency of attacks.

Starting treatment at home, rather than in a hospital, makes for minimal delay and helps the patient to gain a sense of control over the disease. All patients should be taught how to monitor their symptoms so that they will know when an attack is starting, and those with moderate or severe asthma should know how to use a flow meter. They should also have a written "action plan" to follow if symptoms suddenly become worse, including how to adjust their medication and when to seek medical help. A 2004 report said that a review of medical studies revealed that patients with self-management written action plans had fewer hospitalizations, fewer emergency department visits, and improved lung function. They also had a 70% lower mortality rate. If more intense treatment is necessary, it should be continued for several days. Over-the-counter "remedies" should be avoided. When deciding whether a patient should be hospitalized, the past history of acute attacks, severity of symptoms, current medication, and whether good support is available at home all must be taken into account.

Referral to an asthma specialist should be considered if:

  • there has been a life-threatening asthma attack or severe, persistent asthma
  • treatment for three to six months has not met its goals
  • some other condition, such as nasal polyps or chronic lung disease, is complicating asthma
  • special tests, such as allergy skin testing or an allergen challenge, are needed
  • intensive steroid therapy has been necessary

Special populations

INFANTS AND YOUNG CHILDREN. It is especially important to closely watch the course of asthma in young patients. Treatment is cut down when possible and if there is no clear improvement, some other treatment should be tried. If a viral infection leads to severe asthmatic symptoms, steroids may help. The health care provider should write out an asthma treatment plan for the child's school. Asthmatic children often need medication at school to control acute symptoms or to prevent exercise-induced attacks. Proper management will usually allow a child to take part in play activities. Only as a last resort should activities be limited.

THE ELDERLY. Older persons often have other types of obstructive lung disease, such as chronic bronchitis or emphysema. This makes it important to know to what extent the symptoms are caused by asthma. Giving steroids for two to three weeks can help determine this. Side-effects from beta-receptor agonist drugs (including a speeding heart and tremor) may be more common in older patients. These patients may benefit from receiving an anti-cholinergic drug, along with the beta-receptor agonist. If theophylline is given, the dose should be limited, as older patients are less able to clear this drug from their blood. Steroids should be avoided, as they often make elderly patients confused and agitated. Steroids may also further weaken the bones.

Prognosis

Most patients with asthma respond well when the best drug or combination of drugs is found, and they are able to lead relatively normal lives. More than one-half of affected children stop having attacks by the time they reach 21 years of age. Many others have less frequent and less severe attacks as they grow older. Urgent measures to control asthma attacks and ongoing treatment to prevent attacks are equally important. A small minority of patients will have progressively more trouble breathing and run a risk of going into respiratory failure, for which they must receive intensive treatment.

Prevention

Minimizing exposure to allergens

There are a number of ways to cut down exposure to the common allergens and irritants that provoke asthmatic attacks, or to avoid them altogether:

  • If the patient is sensitive to a family pet, removing the animal or at least keeping it out of the bedroom (with the bedroom door closed), as well as keeping the pet away from carpets and upholstered furniture and Removing hair and feathers.
  • To reduce exposure to house dust mites, removing wall-to-wall carpeting, keeping humidity down, and using special pillows and mattress covers. Cutting down on stuffed toys, and washing them each week in hot water.
  • If cockroach allergen is causing asthma attacks, killing the roaches (using poison, traps, or boric acid rather than chemicals). Taking care not to leave food or garbage exposed.
  • Keeping indoor air clean by vacuuming carpets once or twice a week (with the patient absent), avoiding using humidifiers. Using air conditioning during warm weather (so that the windows can be closed).
  • Avoiding exposure to tobacco smoke.
  • Not exercising outside when air pollution levels are high.
  • When asthma is related to exposure at work, taking all precautions, including wearing a mask and, if necessary, arranging to work in a safer area.

More than 80% of people with asthma have rhinitis and recent research emphasizes that treating rhinitis helps benefit ashtma. Prescription nasal steroids and other methods to control rhinitis (in addition to avoiding known allergens) can help prevent asthma attacks. It is also important for patients to keep open communication with physicians to ensure that the correcnt amount of medication is being taken.

Resources

PERIODICALS

"Many People With Asthma ArenÆt Taking the Right Amount of Medication." Obesity, Fitness & Wellness Week (September 25, 2004): 87.

Mintz, Matthew. "Asthma Update: Part 1. Diagnosis, Monitoring, and Prevention of Disease Progression." American Family Physician September 1, 2004: 893.

Solomon, Gina, Elizabeth H. Humphreys, and Mark D. Miller. "Asthma and the Environment: Connecting the Dots: What Role do Environmental Exposures Play in the Rising Prevalence and Severity of Asthma?" Contemporary Peditatrics August 2004: 73-81.

"WhatÆs New in: Asthma and Allergic Rhinitis." Pulse September 20, 2004: 50.

ORGANIZATIONS

Asthma and Allergy Foundation of America. 1233 20th Street, NW, Suite 402, Washington, DC 20036. (800) 727-8462. http://www.aafa.org.

Mothers of Asthmatics, Inc. 3554 Chain Bridge Road, Suite 200, Fairfax, VA 22030. (800) 878-4403.

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

National Jewish Medical and Research Center. 1400 Jackson St., Denver, CO 80206. (800) 222-LUNG.

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Asthma

ASTHMA

Asthma is a common chronic lung disease characterized by a narrowing of the airways, resulting in obstruction of the flow of air and difficulty in breathing. The airflow obstruction is partially or completely reversible in most patients. Different designations of asthma include bronchial asthma, exercise-induced asthma, drug-induced asthma, occupational asthma, and cardiac asthma (airway narrowing in the setting of congestive heart failure). This discussion focuses primarily on bronchial asthma, a chronic inflammatory disorder of the airways (both the larger "bronchi" and the smaller "bronchioles"), resulting in airflow obstruction and increased sensitivity (responsiveness) of the airways to a variety of stimuli ("bronchial hyperreactivity").

About 15 million Americans, a third of whom are children, suffer from asthma, and more than 5,000 people die from it each year. The condition accounts for an estimated 100 million days of restricted activity and 470,000 hospitalizations annually in the United States. Over the last three to four decades both the prevalence and the death rate from asthma in the United States and many other developed countries have increased. In the United States, the increases in death rates have been higher in women than in men and higher in blacks than in whites.

The most important risk factor to develop bronchial asthma is atopy, an inherited predisposition to have allergies. An acute attack of asthma may occur if an atopic individual inhales allergy-provoking substances (allergens) such as ragweed, cat dander, or house dust. A variety of cells are involved in the asthmatic inflammatory reaction in the airway walls, including neutrophils, eosinophils, lymphocytes, mast cells, and macrophages. These cells release mediators (chemicals such as "cytokines") that provoke the inflammatory process. Asthma also occurs in people without allergies.

During an acute episode of asthma, bronchial narrowing ("bronchoconstriction") results from the buildup of plugs of mucus and cellular debris in the lumen, contraction of smooth-muscle cells ringing the airways, and inflammation and edema of the mucosa. Permanent changes in the airway, including enlargement of the submucosal mucous glands, proliferation of mucus-secreting cells and smooth-muscle cells, and deposition of fibrous tissue in the mucosa, may occur in chronic asthma, a process known as "airway remodeling."

The degree of airflow limitation in patients with asthma is measured by performing breathing tests (pulmonary function tests) such as spirometry and the recording of peak expiratory flow rates (PEFRs). This requires the patient to take in as deep a breath as possible and blow it out with maximum effort into a recording instrument. Obstructive dysfunction is detected if airflow rates are significantly less than predicted values. Partial or complete reversibility of the obstructive dysfunction is possible in most cases after the inhalation of a medication (e.g., albuterol) that dilates the airways. Between episodes of asthma, airflow rates may be normal. However, a patient who has had asthma for many years may display persistent and irreversible obstructive dysfunction as a result of airway remodeling. Spirometry is also employed in bronchial-provocation testing to determine if an individual with suspected asthma has bronchial hyperreactivity (an unusual degree of airway sensitivity to challenges such as exercise or the inhalation of dilute solutions of chemicals such as methacholine).

Patients with asthma suffer from shortness of breath, wheezing, chest tightness, and cough. These symptoms, which may be episodic or chronic, are often worse early in the morning and may disrupt sleep. Asthma often develops in childhood, but it may appear at any age. Episodes of asthma may be spontaneous, but more commonly they are "triggered" by various stimuli, such as inhaling allergens or nonspecific airway irritants (e.g., dusts, smoke, fumes, cold air), upper or lower respiratory tract infections, exercise, certain medications, and exposure to chemicals and other substances in the workplace. The frequency and severity of symptoms vary greatly from patient to patient and tend to be less episodic and more persistent with increasing age.

The diagnosis of bronchial asthma depends upon a medical history of one or more asthma symptoms, evidence of airflow limitation on physical examination or pulmonary function testing, and demonstration of some degree of reversibility of airflow obstruction. Other conditions that mimic asthma must be excluded. These include acute or chronic bronchitis, emphysema, bronchiectasis, cystic fibrosis, upper airway obstruction from various causes, abnormal function of the vocal cords, aspiration, lung cancer, congestive heart failure, pulmonary thromboembolism (blood clots in the pulmonary artery), and even certain psychiatric disorders.

Asthma is classified according to the severity and frequency of its symptoms and the results of pulmonary function tests. Mild intermittent asthma is managed by treating the occasional symptoms with inhaled bronchodilators, called beta2-agonists. Persistent asthma is treated with daily anti-inflammatory drugs, especially inhaled corticosteroids, often in combination with one or more inhaled or oral bronchodilator drugs. A newer class of drugs called leukotriene modifiers is employed to manage some patients with persistent asthma. Severe persistent asthma requires the daily use of several medications, including oral corticosteroids such as prednisone. Acute, severe asthma may require the patient to be hospitalized to manage acute respiratory failure with supplemental oxygen and even respiratory support on a mechanical ventilator.

Patient education, environmental control, smoking cessation, and avoidance of factors known to provoke attacks are the mainstays of prevention. The importance of stopping smoking cannot be overemphasized. Patients with asthma must reduce exposure to allergens (such as house dust mites and animal danders), eliminate certain medications (such as beta-blocker drugs and aspirin), and avoid exposure to indoor and outdoor air pollutants. A diagnosis of occupational asthma requires that steps be taken to curtail workplace exposure to offending agents. Annual vaccination against influenza virus infection is recommended for patients with persistent asthma.

Fortunately, most patients with asthma respond well to appropriate medical management. Anti-inflammatory therapy for persistent asthma and immediate treatment for acute, severe attacks are essential steps to reduce morbidity and mortality from the disease. Death from bronchial asthma is considered to be preventable.

John L. Stauffer

(see also: Chronic Respiratory Diseases; Emphysema; Pulmonary Function )

Bibliography

"Drugs for Asthma." The Medical Letter on Drugs and Therapeutics 41(2000):1924.

McFadden, E. R., Jr. (1998) "Asthma." In Harrison's Principles of Internal Medicine, 14th edition, ed. A. S. Fauci et al. New York: McGraw-Hill.

McFadden, E. R., Jr., and Warren E. L. (1997). "Observations on Asthma Mortality." Annual of Internal Medicine 127:142147.

National Asthma Education Program (1997). "Expert Panel Report 2: Guidelines for the Diagnosis and Management of Asthma." Bethesda, MD: National Heart, Lung, and Blood Institute. Available at http://www.nhlbi.nih.gov/nhlbi/lung/asthma/prof/asthgdln.htm.

Woolcock, A. J., and Barnes, P. J. (2000). "Asthma: The Important Questions. Part 4." American Journal of Respiratory and Critical Care Medicine 161(3):S157 S217.

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Asthma

Asthma


Asthma is a chronic disease of the lungs that affects millions around the world, particularly in industrialized countries. The symptoms of asthma include shortness of breath, chest tightness, wheezing, and coughing; nighttime symptoms that interfere with sleep can be particularly troublesome. These symptoms are caused by inflammation, swelling, and constriction of muscles that surround the breathing tubes in the chest, the airways connecting the lungs to the mouth and nose. The hallmark of asthma is variability and reversibility in the inflammation and constriction of the airways.

Although researchers have identified a number of chemicals in the workplace that can cause asthma, the cause of most cases of asthma is unknown. Genetic risk factors are important; adults who have asthma are more likely to produce children with asthma than adults who do not suffer from this ailment. Genetic risk cannot explain the increase in the number of persons with asthma in the United States, from 6.8 million persons in 1980 to about 15 million in 1996, because the genetic composition of the population changes much more slowly than that.

Whether outdoor air pollution might cause asthma has not been sufficiently studied. Although many people are afflicted with asthma, determining exactly when an individual's disease beganso the critical period of environmental exposures might be identifiedis difficult. Studies comparing the overall rate of asthma with air pollution levels have not produced data showing a relationship between asthma and outdoor pollution. For example, increases in the number of persons with asthma in the United States occurred while the overall levels of outdoor air pollution were declining. Despite the overall decline in air pollution, concentrations of ozone and airborne particles with a diameter less than 10 microns (abbreviated as PM10) have hardly declined at all. Nevertheless, these trends do not implicate outdoor air pollution as an important cause of the increase in asthma sufferers. Information comparing rates of asthma among children born in Germany before and after reunification in 1989 also do not support a role for air pollution in causing asthma. Air pollution from industrial sources was greater in the former East Germany than in West Germany, yet the situation with asthma was the reverse, with a higher rate of asthma present in West Germany. The difference in asthma rates appeared to result from higher rates of allergy in West Germany. In contrast to these studies, one recent study conducted in southern California found an increased risk for developing asthma in children who participated in team sports, a surrogate for greater exposure, and who also lived in areas with higher ozone levels.

Some outdoor air pollutants, such as ground-level ozone, PM10, sulfur dioxide, and nitrogen oxides, can worsen asthma. Related studies compare the rate of emergency department visits for asthma at times of high levels of air pollution with such visits at times of low levels of air pollution. In a study conducted during the 1996 Olympics in Atlanta, changes in traffic patterns were associated with reduced levels of ozone and with fewer emergency department visits for asthma.

Indoor air pollution probably plays a more significant role in asthma than outdoor air pollution. On average, people spend much more time indoors than outdoors, and concentrations of some pollutants can be many times higher indoors. Indoor air exposures are classified as being biological, derived from living organisms, or chemical. Because no regulations exist for levels of indoor air pollutants, concentrations of these exposures are not measured with the same frequency and uniformity as those for outdoor pollutants.

Among indoor exposures, exposure to house dust mites has been found to cause asthma and, for preschool-aged children, environmental tobacco smoke has been associated with the development of asthma. Some evidence exists that exposure to cockroaches and infection with respiratory syncytial virus also may be linked to the development of asthma. Researchers have correspondingly identified a much longer list of indoor exposures that can trigger or worsen asthma: besides the above factors, exposure to cat dander, molds, dogs, and nitrogen oxides.

An individual can take many steps to reduce exposure to the factors that exacerbate asthma. Basic precautions include the following: Stop smoking and avoid tobacco smoke; vacuum the home once or twice a week (but with the asthma-affected person not present); avoid mold, making sure that moisture collections are addressed to prevent mold growth; and reduce exposure to house dust mites, cats, dogs, and cockroaches, depending on which of these are allergic triggers for the asthma sufferer.

The importance of air pollution, whether indoor or outdoor, as a cause of asthma remains a subject of intense study. Exposure to house dust mites appears to be capable of causing asthma and environmental tobacco smoke has been associated with the development of asthma, but evidence linking these exposures to the increase in asthma cases is lacking.

see also Air Pollution; Health, Human; Indoor Air Pollution.

Bibliography

Committee on the Assessment of Asthma and Indoor Air. (2000). Clearing the Air: Asthma and Indoor Air Exposures. Washington, DC: National Academy Press.

Pearce, Neal; Beasley, Richard; Burgess, Carl; and Crane, Julian, eds. (1998). Asthma Epidemiology: Principles and Methods. New York: Oxford University Press.

Internet Resource

National Asthma Education and Prevention Program. (1997). Facts about Controlling Your Asthma. Bethesda, MD: Public Health Service. Available from http://www.nhlbi.nih.gov/health.

Stephen C. Redd

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Asthma

Asthma

Asthma is a reversible lung disease that affects approximately four million people in the United States. It is sometimes referred to as a disease of twitchy or reactive lungs, which means that the airways of the lungs are extremely sensitive to irritants such as pollen, animal dander (hair, feathers, or skin), dust, or tobacco smoke. When these irritants are inhaled, the airways react by constricting or narrowing. In some people, asthma attacks follow a cold or a severe respiratory infection. Stress, exercise, and even changes in temperature or humidity can bring on attacks of asthma, as can certain drugs such as aspirin.

Some people with asthma have only mild symptoms that occur from time to time. Others have symptoms that occur frequently and that can be mild, moderate, or severe in nature. Severe asthma attacks are sometimes life threatening. Although researchers have learned more about the underlying causes of asthma in recent years, there is no specific treatment for the disease. In fact, deaths from asthma are on the rise. Many experts believe that lack of standard treatments and inconsistent monitoring of asthma patients have contributed to this increased rate of death.

How asthma affects the airways

The airways are tubes called bronchi that branch into smaller tubes called bronchioles. They carry air from the windpipe to the lungs. During an asthma attack, the airways are narrowed due to muscle spasms, swelling and inflammation of the airway walls, and the production of large amounts of mucus. This results in a blocking of the passage of air to the lungs. The characteristic sign of asthma is wheezing, the noisy whistling sound that a person makes as he or she tries to push air in and out of narrowed airways. Other symptoms include the sensation of a tight chest, shortness of breath (breathlessness), and a cough.

Treatment of asthma

Treatment of asthma aims at opening the airways and reducing inflammation. There are two general categories of medications used to treat the disease: those that bring quick relief in the sudden onset of an asthma attack and those used long-term to control persistent asthma. The treatment used may vary from patient to patient, based on individual need. While an inhaler may be used occasionally in very mild cases, often a combination of drugs is prescribed for moderate to severe forms. Extremely severe, or acute, attacks of asthma may require the patient to be hospitalized.

Words to Know

Bronchi: The two main airway tubes that branch off from the windpipe and lead to each lung.

Bronchiole: Any of the smaller airway tubes that branch off from the bronchi.

Bronchodilator: A drug, either inhaled or taken orally, that widens the lung airways by relaxing the smooth muscles of the airways.

Constriction: In asthma, the characteristic narrowing of the airways.

Bronchodilators are drugs that dilate, or widen, constricted lung airways by relaxing the smooth muscles of the airways. They can either be inhaled through a special device or taken orally (by mouth) in pill form. Inhaled bronchodilators are usually prescribed for mild to moderate forms of asthma. Because they are applied directly to the constricted airways, they act quickly; the patient is instructed to inhale the drug as soon as he or she feels an attack coming on. Oral bronchodilators are longer acting and are usually prescribed for severe asthma. A new, longer-acting bronchodilator called Salmeterol, which is inhaled, combines the direct effects of inhaled bronchodilators with the long-lasting protection of oral ones. It is useful in maintaining clear airways and in preventing nighttime flare-ups of asthma, as well as those caused by such stimuli as exercise and changes in temperature.

The inflammation associated with asthma has a direct effect on lung function. Increased emphasis has been placed on the use of anti-inflammatory drugs to reduce swelling and inflammation of the airways. In cases of persistent asthma, it is often recommended that anti-inflammatory medications, such as corticosteroids (pronounced kor-tik-oh-STEH-roydz), be taken on a daily basis. They can either be inhaled or taken in pill form.

Another medication commonly used in the treatment of asthma is Cromolyn, a drug that blocks the release of histamine. Histamine is a chemical that the body produces in response to allergy-causing substances. Its release prompts constriction of the airways, which results in difficulty

breathing. Cromolyn is used to prevent asthma attacks rather than as a treatment during attacks.

Managing asthma and preventing attacks

The key to managing asthma and preventing attacks is the patient's ability to recognize the factors that trigger an attackand then making the conscious effort to avoid them. Since allergies and asthma often go hand in hand, allergy testing may be an effective way to identify allergens (allergy-causing substances) in some patients. If asthma is brought on by exercise, finding a level of exertion that is comfortable or using an inhaled bronchodilator before exercise may help to control symptoms. Taking medicine as prescribed is also an important factor in maintaining control of the disease.

For all persons with asthma, the most important aspect of managing their disease is communication with and regular visits to their physician. It is essential that patient and physician work together to monitor progress and keep abreast of any changes in the patient's condition.

[See also Respiratory system ]

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Asthma

ASTHMA

Due to its frequent association with psychoaffective symptoms, asthma is considered a classic psychosomatic disorder. The Hungarian-American analyst Franz Alexander was an early proponent of psychosomatic medicine, and during the 1940s he and Thomas French applied the "specific emotion theory" to try to establish a link between the onset of asthmatic attacks and emotional conflicts. Their research suggested that pregenital instinctual desires, experienced as threatening to the dependent mother-child dyad, could give rise to bronchial symptoms, noting that breathing is the first independent post-natal physiological function. It is possible to view the infant's double separation from the motherbiological and psycho-affectiveas reviving the Freud-Rank birth trauma debate. A generation later in 1963, research by Peter Hobart Knapp suggested that allergic diathesis was a necessary precondition to developing symptoms, and offered as possible triggering mechanisms either hysterical conversion or conflicts of oral incorporation expressed through the respiratory apparatus.

In France, Pierre Marty, one of the founders of the Ecole de Psychosomatique de Paris, theorized that asthma, like other allergic manifestations, arises from a specific type of object relationship that involves a form of profound and almost instantaneous mimetic identification that includes a projective movement identifying object with subject. The difficulty of maintaining such a state of confused fusion either produces some accommodation or, in the case of an intractable object, creates a distance from the object that may be considered at once symbolic and real. The separation from the object whose own characteristics are too distant from, or independent of, the subject, occurs without the work of mourning. The asthmatic attack breaks out during conflict between two objects, both equally invested but themselves in conflict. The asthmatic attack externalizes and diverts internal psychological destruction.

Robert AssÉo

See also: Allergy; Psychosomatic.

Bibliography

Alexander, Franz, and French, Thomas M. (1941). Psychogenic factors in bronchial asthma. Washington, DC: National Research Council.

Bauduin, Andrée. (1985). L'asthme bronchique, aspects dynamiques et psychanalytiques. Revue médicale de Liège, 90 (22).

Fenichel, Otto. (1953). The collected papers of Otto Fenichel. First and second series (H. Fenichel and D. Rapaport, Eds.). New York: Norton.

Knapp, Peter H. (1989). Psychosomatic aspects of bronchial asthma. Madison, CT: International Universities Press.

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asthma

asthma (ăz´mə, ăs´–), chronic inflammatory respiratory disease characterized by periodic attacks of wheezing, shortness of breath, and a tight feeling in the chest. A cough producing sticky mucus is symptomatic. The symptoms often appear to be caused by the body's reaction to a trigger such as an allergen (commonly pollen, house dust, animal dander: see allergy), certain drugs, an irritant (such as cigarette smoke or workplace chemicals), exercise, or emotional stress. These triggers can cause the asthmatic's lungs to release chemicals that create inflammation of the bronchial lining, constriction, and bronchial spasms. If the effect on the bronchi becomes severe enough to impede exhalation, carbon dioxide can build up in the lungs and lead to unconsciousness and death. Following a steady 30-year decline, asthma deaths in the United States, especially among poor, inner-city blacks and among the elderly, began to rise from the late 1970s through the early 1990s. At the same time, the incidence of asthma also increased, both nationally and worldwide.

There is no cure for asthma. Although the disease may go through a period of quiescence, it appears that childhood asthmatics do not outgrow the disease as previously believed. Treatment includes inhaled or oral steroids or bronchodilators (albuterol, theophylline), breathing exercises, and, if possible, the identification and avoidance of triggers.

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asthma

asthma (ass-mă) n. the condition of subjects with widespread narrowing of the bronchial airways, which changes in severity over short periods of time and leads to coughing, wheezing, and difficulty in breathing. bronchial a. asthma that may be precipitated by exposure to one or more of a wide range of stimuli, including allergens, drugs (such as aspirin), exertion, emotion, infections, and air pollution. Treatment is with bronchodilators, with or without corticosteroids, usually administered via aerosol or dry-powder inhalers, or – if the condition is more severe – via a nebulizer. Severe asthmatic attacks may need large doses or oral corticosteroids (see status asthmaticus). cardiac a. asthma that occurs in left ventricular heart failure and must be distinguished from bronchial asthma, as the treatment is quite different.
asthmatic (ass-mat-ik) adj.

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Asthma

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.

Asthma: Words to Know

Allergen:
A foreign substance which, when inhaled, causes the airways to narrow and produces the symptoms of asthma.
Atopy:
A condition in which people are more likely to develop allergic reactions, often because of the inflammation and airway narrowing typical of asthma.
Spirometer:
An instrument that shows how much air a patient is able to exhale and hold in his or her lungs as a test to see how serious a person's asthma is and how well he or she is responding to treatment.

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

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).

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. 8007ASTHMA. http://www.aafa.org.

National Asthma Education Program. 4733 Bethesda Avenue, Suite 350, Bethesda, MD 20814. (301) 4954484.

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).

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asthma

asthma Disorder of the respiratory system in which the bronchi (air passages) of the lungs go into spasm, making breathing difficult. It can be triggered by infection, air pollution, allergy, certain drugs, exertion or emotional stress. Allergic asthma may be treated by injections aimed at lessening sensitivity to specific allergens. Otherwise treatment is with bronchodilators to relax the bronchial muscles and ease breathing; in severe asthma, inhaled steroids may be given. Children often outgrow asthma, while some people suddenly acquire the disease in middle age. Air pollution is increasing the number of asthma sufferers. See also bronchitis; emphysema; lungs

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Asthma

Asthma

A Breathless Story

What Is Asthma?

What Triggers Asthma?

Who Gets Asthma?

What Are the Symptoms?

How Is Asthma Diagnosed?

Why Is Treatment Needed?

How Is Asthma Treated?

How Are Inhaled Medicines Taken?

Breathing Easier

Resources

Asthma (AZ-ma) is a condition in which the airflow in and out of the lungs may be partially blocked by swelling, muscle squeezing, and mucus in the lower airways. These episodes of partial blockage, called asthma flares or attacks, can be triggered by dust, pollutants, smoke, allergies, cold air, or infections.

KEYWORDS

for searching the Internet and other reference sources

Breathing

Lungs

Pulmonary system

Respiratory system

A Breathless Story

When Stacy was young, her parents noticed that she seemed to get tired more quickly than her friends while playing. She also had repeated coughing spells, and her breathing was sometimes noisy. After examining Stacy, asking lots of questions, and having her use a little machine to measure her breathing, the doctor diagnosed her problem as asthma. As part of the way Stacy took care of herself, she sometimes had to take asthma medicine at school. This made her teachers and friends interested in learning more about asthma. When Stacy was 12, she began a schoolwide project with the help of her teacher and the nurse. The goal was to make her school more asthma-friendly. No smoking was allowed, even during after-school events. Extra steps were taken to keep the school as free as possible of things that can trigger asthma flares, such as dust, mold, cockroaches, and strong fumes from paint and chemicals. A plan was set up to let students with asthma take their own medicines at school. Special lessons were offered to all students and teachers about what asthma is and how to help a classmate who has it. The result was a school that was a healthier place not just for Stacy but for everyone.

What Is Asthma?

Several changes happen inside the airways in the lungs of people who have asthma. First, there is inflammation, or swelling, of the lining of the airways. Second, the swollen tissues make a thick, slippery substance called mucus (MYOO-kus). Third, the muscles around the airways may squeeze tight, causing the airways to narrow. These three processes inflammation, mucus production, and muscle constrictioncombine to reduce the size (the diameter) of the airways. That makes it harder to breathe, like trying to blow air through a narrow straw.

During an asthma attack, these changes get worse. The airways swell on the inside while they are being squeezed on the outside. At the same time, thick mucus plugs the smaller airways. The person may start to make whistling or hissing sounds with each breath. The persons chest may also feel tight. In addition, the person may cough to try to clear the lungs.

What Triggers Asthma?

People with asthma have what are sometimes called sensitized airways. Everyday things that cause little or no trouble for most people can sometimes cause people with asthma to have a flare or attack. These things are

known as asthma triggers. There are two main kinds of triggers. The first are allergens (AL-er-jens), or substances that trigger an allergy. Examples of allergens that may trigger asthma are pollens, molds, animal dander (small scales from fur or feathers), dust mites, cockroaches, and certain foods and medicines. Most of these allergy-causing substances enter the body through the air people breathe, but some are swallowed.

The second kind of asthma trigger has nothing to do with an allergy but causes the same kind of reaction in the airways. Asthma can be triggered or made worse by irritating substances in the air, such as tobacco smoke, wood smoke, fresh paint, cleaning products, perfumes, workplace chemicals, and air pollution. Some other triggers include cold air, sudden changes in air temperature, exercise, heartburn, and infections of the airways, such as a cold or the flu. Exactly which of these might trigger a reaction varies from person to person.

Who Gets Asthma?

Asthma is one of the most common health problems in the United States. The number of people with the condition has grown rapidly in recent years. The reason for this increase is not yet known. About a third of these people are children under age eighteen. Asthma is more common in African American children than in white children, although the reason for this is not clear. It may have to do with environmental conditions.

What Are the Symptoms?

Following are the most common symptoms of asthma. A person may have all, some, or just one of these symptoms:

  • Shortness of breath
  • Coughing, particularly if it lasts longer than a week
  • Wheezing (whistling or hissing sounds made primarily when breathing out)
  • A feeling of tightness or discomfort in the chest

The degree to which asthma interferes with a persons daily life varies significantly. Some people have ongoing problems. They may have attacks anywhere from a couple of times a week to almost constantly. Their ability to take part in physical activities may be limited until, with treatment, they are able to get their asthma under control. Those with milder problems are usually able to do whatever they want to do, so long as they reduce their environmental triggers, take their medicine as directed, and follow any other advice from their doctors.

Childhood asthma

Babies often wheeze when they have a cold or other infection of the airways, blockage of the airways, or other problems. This symptom may go away on its own with no ill effects. However, if the problem is severe, lasts a long time, or comes back, treatment may be needed. In older children, normal breathing should be quiet. Wheezing may be a sign of asthma, but it can also signal an infection, lung disease, heartburn, heart disease, a blood vessel blocking the airways, or even a piece of food or other object (such as part of a toy) lodged in the airway. In addition to noisy breathing, asthma in children can cause rapid breathing and frequent coughing spells. Parents may also notice that the child tires quickly during active play.

Nighttime asthma

Asthma tends to get worse at night. Nocturnal (or nighttime) asthma occurs while a person is sleeping. For some people, nocturnal asthma is one of many symptoms; other people seem to have coughing or wheezing only at night.

Exercise-related asthma

Up to four out of five people with asthma have trouble with noisy breathing during or after exercise. This

Four Centuries of Medical Research

The word asthma comes from the Greek word for panting, which is a symptom that occurs in several different pulmonary (lung) disorders. Asthma was first depicted as a disease rather than a symptom by the English chemist Thomas Willis (1621-1675).

In 1698, Sir John Floyer first gave the first formal account of an asthma attack or fit. However, an accurate diagnosis of asthma was not possible until the early nineteenth century when the celebrated French physician René Laënnec (17811826) invented the stethoscope.

During the early nineteenth century, asthma was treated in a variety of ways including whiffs of chloroform and even the smoking of ordinary tobacco.

is known as exercise-induced asthma. Other symptoms include coughing, a rapid heartbeat, and a feeling of tightness in the chest five to ten minutes after exercise. Cold or dry air, high pollen counts, air pollution, a stuffed-up nose, and an infection of the airways are all things that tend to make the problem worse. Types of exercise that may lead to wheezing include running, using a treadmill, and playing basketballin short, exercises that are aerobic (designed to increase oxygen consumption).

Job-related asthma

Occupational asthma is caused by breathing in fumes, gases, or dust while on the job. Asthma can start for the first time in a worker who was previously healthy, or it can get worse in a worker who already had the condition. Symptoms include wheezing, chest tightness, and coughing. Other symptoms that may go along with the asthma include a runny or stuffed-up nose and red, sore, itchy eyes. The asthma may last for a long time, even after the worker is no longer around the substance that caused it.

Severe attacks

Status asthmaticus (STA-tus az-MAT-i-kus) is a severe asthma attack that does not get better when the person takes his or her medicine as usual. This kind of attack is an emergency that must be treated right away in a hospital or doctors office, where other medicines may be used.

How Is Asthma Diagnosed?

The doctor will do a physical checkup and ask questions about symptoms and when they occur. In addition, the doctor may do various tests to help identify asthma and its causes. These are some of the tests that may be done:

Allergy tests

Allergy tests help identify which things a person is allergic to. Skin tests are most common. Tiny amounts of possible allergens are put on the skin, and the skin is checked to see which substances, if any, cause a reaction. In another type of allergy test, a blood sample is checked for certain antibodies, which are substances made in the blood to fight foreign or harmful things. People with allergies may have high levels of immunoglobulin E (IgE) antibodies. However, the blood test is generally not considered as sensitive as the skin test, and it cannot check for as many allergens.

Chest x-ray

An x-ray is an invisible wave that goes through most solid matter and produces an image on film. In this case, a special picture is made to show how the lungs look.

Lung-function tests

These tests show how well the lungs are working. In one test, the person blows into a device called a spirometer (spi-ROM-i-ter), which measures the amount of air going in and out of the lungs. Another test uses a peak flow meter to measure how fast the person can breathe air out of the lungs. A peak flow meter is a simple, hand-held device that can be used at home. Many people with asthma use peak flow meters regularly to check for early warning signs of an upcoming asthma attack. This gives them time to take certain medicines that can often stop the attack.

Why Is Treatment Needed?

Asthma that is not under control can cause many problems. People miss school or work, must go to the hospital, and can even die (rarely) because of asthma. With a doctor s help, though, it is possible to control asthma. People with well-controlled asthma have few, if any, symptoms during the day and can sleep well at night. They can also take part in their usual activities, including sports and exercise. However, the asthma does not go away just because the symptoms do. A person needs to keep taking care of the condition as part of life: avoiding triggers, not smoking, and living in a healthful, clean environment. This is true even if the asthma is mild.

How Is Asthma Treated?

Besides avoiding exposure to asthma triggers, the chief way that asthma is treated is with various medicines. One key to good control is taking the right medicine at the right time. There are two main kinds of asthma medicines: those that help with long-term control of the disease, and those that give short-term relief when a person is having an asthma attack.

Long-term control medicines

Long-term control medicines are taken every day to help prevent symptoms before they start. It may take several weeks for these medicines to produce their best results, though. The most effective ones work by reducing swelling in the airways. Many are inhaled, or breathed into the lungs. Not everyone needs such medicines. However, they may be very helpful for people who have daytime asthma symptoms three or more times a week or nighttime symptoms three or more times a month. These are some medicines for long-term control of asthma:

  • Inhaled corticosteroids (kor-ti-ko-STER-oids). These strong drugs prevent and reduce swelling in the airways. They also make the airways less sensitive to triggers. However, they work only if they are used regularly. These drugs are taken every day by people with long-lasting asthma. They are not the same as the unsafe steroids some athletes use to build muscles.
  • Other inhaled drugs. These medications also help prevent and reduce swelling in the airways and make the airways less sensitive. However, it can take four to six weeks of regular use before they start to work. These drugs are taken every day by people with long-term asthma, but they can also be used before exercise or contact with a trigger.
  • Oral corticosteroids. These drugs are taken by mouth in pill or liquid form. Unlike inhaled corticosteroids, they sometimes cause serious side effects when used for a long time. However, they can often be used safely for a short time to treat severe asthma attacks and to quickly bring asthma under control. They are sometimes taken every day or every other day by people with the most severe asthma.

Breathtaking Facts

  • More than 17 million people in the United States have asthma. Of these, almost 5 million are children.
  • About one in every ten children has asthma-like symptoms.
  • About three out of four children with asthma continue to have symptoms as adults.
  • Asthma results in about 3 million lost days of work each year among American adults.
  • According to the Centers for Disease Control and Prevention (CDC), between 1980 and 1994, the number of Americans who reported having asthma rose 75 percent.

Winning Ways

Jackie Joyner-Kersee (b. 1962) has often been called the worlds greatest female athlete. What many fans never suspect is that she is also an asthma patient. Joyner-Kersee became active in sports at age nine. As a teenager, she was an all-state player in basketball and a Junior Olympics champion in pentathlon, an athletic contest in which each person takes part in five different events. While still in high school, Joyner-Kersee began having trouble breathing. When she first found out that she had asthma, she did not take it seriously. She often skipped her medicine. After a serious asthma attack, though, she realized that she had to work to control the condition just as she worked to win at sports. After college, Joyner-Kersee went on to win six Olympic medals as well as to break the world and Olympic records in the heptathlon, an athletic contest with seven different events: 100-meter hurdles, high jump, shot put, 200-meter dash, long jump, javelin, and 800-meter race. Today she serves as a spokesperson for groups that educate the public about asthma.

  • Long-acting bronchodilators (brong-ko-DY-lay-tors). These drugs relax the muscles around the airways, making it easier to breathe. They can prevent or reduce narrowing of the airways. However, they keep working only if they are used regularly. These drugs are inhaled or taken by mouth in a pill. Some are especially useful for preventing nighttime or exercise-related asthma.
  • Antileukotrienes (an-ti-loo-ko-TRY-eens). This is a new class of asthma drugs. These drugs prevent and reduce swelling in the airways and make the airways less sensitive to triggers. They also prevent squeezing of the muscles around the airways. These drugs are taken regularly by mouth in a pill. So far, they have been used mainly for mild asthma in patients of age twelve and older.
  • Allergy vaccines. In some cases, a persons asthma symptoms can be prevented or lessened by giving a course of special allergy injections over months or years. These shots contain small amounts of the allergens that are triggering the persons asthma. The course of injections causes the person to become less sensitive to the allergen when exposed to it.

Short-term relief medicines

Short-term relief medicines are taken only when needed to relax and open the airways quickly. They can be used to relieve symptoms or to prevent them if a persons peak flow meter readings begin to drop, signaling an upcoming asthma attack. However, the effects last for only a few hours. They cannot keep the symptoms from coming back the way long-term control medicines can. These drugs are inhaled and are taken at the first sign of trouble or before contact with a trigger.

Medicines that provide short-term relief of asthma are called short-acting bronchodilators. These drugs relax the muscles around the airways, making it easier to breathe. They begin to work within five minutes, and their effects last for four to six hours. Such drugs are taken right after symptoms start or just before exercise.

How Are Inhaled Medicines Taken?

Many asthma medicines are made to be breathed into the lungs. Such inhaled drugs go straight to the place where they are needed. The most popular device for taking inhaled medicines is a metered dose inhaler, which gets the drug to the lungs in exact amounts. The inhaler is a small, hand-held canister with a button that the person pushes to make the medicine spray out. Often a tube, called a spacer, is attached to the canister to make it easier to use.

Another type of device that is sometimes used to take inhaled medicines is a nebulizer (NEB-you-lyz-er), which turns liquid medicine into a very fine mist. These devices are helpful for babies, young children, and elderly or very sick adults who would have trouble handling a metered dose inhaler.

Breathing Easier

People with asthma should try to figure out what makes their symptoms worse and take steps to avoid or control those things. Here are a few ways that many people control some common asthma triggers. Not all of them will work for everyone.

Pollens and outdoor molds

To control pollens and outdoor molds, people with asthma often:

  • keep windows and doors closed when pollen or mold spore counts are high.
  • avoid walking in gardens and fields when they are in bloom and when pollen and mold spore counts are highest.
  • ride with the car windows shut and the air conditioner on during pollen season.
  • ask their doctors about starting or increasing a long-term control medicine before peak pollen season begins.

Indoor molds

To control indoor molds, people with asthma often:

  • fix leaky faucets, pipes, and other sources of water.
  • clean moldy surfaces with a product that contains bleach.
  • remove wallpaper, which can have mold growing on it.
  • get rid of houseplants, which can gather mold and dust.

Animal dander

Dander is small scales from the hair of animals, like cats, and from bird feathers. Some people are allergic to it, and people with asthma often:

  • keep pets with fur or feathers out of their homes, if possible.
  • have pets stay out of bedrooms, in particular, and keep bedroom doors closed.
  • remove carpets and cloth-covered furniture, or keep pets away from these things.
  • use polyester-fill rather than feather pillows, and avoid down quilts.

Dust mites

People with asthma often find that they are allergic to dust because of the tiny animals that live in the dust, called mites. Many people with asthma find that it helps to keep their homes especially clear of dust. For example, they:

  • wash their bedding each week in hot water (it must be hotter than 130 degrees F to kill mites).
  • enclose mattresses and pillows in special dust-proof covers, or wash pillows each week in hot water.
  • try not to sleep or lie on cloth-covered furniture or cushions.
  • remove carpets in bedrooms and those laid on concrete.
  • keep stuffed toys out of beds, and wash the toys each week in hot water.
  • wear a dust mask while vacuuming, or have someone else do the vacuuming.

Cockroaches

Many people with asthma are sensitive to cockroach droppings and make a special effort to get rid of these stubborn creatures by:

  • keeping all food out of bedrooms.
  • storing food and garbage in closed containers and never leaving food or crumbs sitting around.
  • using poison bait, powder, gel, paste, or traps (following label instructions) to kill cockroaches.
  • staying out of the room until the odor goes away if a spray is used to kill roaches.

Certain foods and medicines

It is important to:

  • avoid foods that have caused problems in the past.
  • tell the doctor about any past reactions to medicines.

Smoke and strong odors

Smoking is not good for anyone, the person smoking or people who are in the same room with tobacco smoke. People with asthma are especially endangered by tobacco smoke and find it is best not to smoke, to ask other family members to quit smoking, and to ask visitors not to smoke.

People with asthma also:

  • avoid using a wood-burning stove, kerosene heater, or fireplace, if possible.
  • try to stay away from strong odors and fumes, such as perfume, hairspray, and fresh paint.

Exercise

It is healthy for just about everyone to exercise, and people with asthma are no exception. To make their exercise and sports more enjoyable, people with asthma usually:

  • warm up for six to ten minutes before exercising.
  • avoid exercising outside when air pollution or pollen counts are high or when the air is cold.
  • pick activities that do not cause symptoms; running sports are the most likely to trigger problems.
  • ask a doctor about taking medicine before exercise to prevent symptoms.

See also

Allergies

Emphysema

Heartburn (Dyspepsia)

Resources

Books

American Lung Association and Norman H. Edelman. The American Lung Association Family Guide to Asthma and Allergies: How You and Your Children Can Breathe Easier. New York: Back Bay Books, 1997.

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

Organizations

Allergy and Asthma Network/Mothers of Asthmatics, 2751 Prosperity Avenue, Suite 150, Fairfax, VA 22031. Telephone 800-878-4403 http://www.aanma.org

American Academy of Allergy, Asthma and Immunology, 611 East Wells Street, Milwaukee, WI 53202. Telephone 414-272-6071 http://www.aaaai.org

American College of Allergy, Asthma and Immunology, 85 West Algonquin Road, Suite 550, Arlington Heights, IL 60005. Telephone 847-427-1200 http://allergy.meg.edu

American Lung Association, 1740 Broadway, New York, NY 10019. Telephone 800-LUNG-USA

http://www.lungusa.org

Asthma and Allergy Foundation of America, 1125 Fifteenth Street N.W., Suite 502, Washington, DC 20005. Telephone 800-7-ASTHMA http://www.aafa.org

Asthma Information Center. This website is run by the Journal of the American Medical Association. http://www.ama-assn.org/special/asthma/asthma.htm

U.S. National Heart, Lung, and Blood Institute, NHLBI Information Center, P.O. Box 30105, Bethesda, MD 20824-0105. NHLBI has an Asthma Management Model System and runs a National Asthma Education and Prevention Program. Telephone 301-592-8573 http://www.nhlbisupport.com/asthmahttp://www.nhlbi.nih.gov

The U.S. Centers for Disease Control, located in Atlanta, Georgia, posts information on asthma at http://www.cdc.gov/nceh/programs/asthma/default.htm

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asthma

asth·ma / ˈazmə/ • n. a respiratory condition marked by spasms in the bronchi of the lungs, causing difficulty in breathing. It usually results from an allergic reaction or other forms of hypersensitivity.

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asthma

asthma XIV. — Gr. ásthma, -mat-.
So asthmatic XVI.

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asthma

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Asthma

Asthma


Asthma is a condition characterized by unpredictable and disabling shortness of breath. It features episodic attacks of bronchospasm (prolonged contractions of the bronchial smooth muscle), and is a complex disorder involving biochemical, autonomic, immunologic, infectious, endocrine, and psychological factors to varying degrees in different individuals.

Asthma occurs in families suggesting that there is a genetic predisposition for the disorder, although the exact mode of genetic transmission remains unclear. The environment appears to play an important role in the expression of the disorder. For example, asthma can develop when predisposed individuals become infected with viruses or are exposed to allergens or pollutants. On occasion foods or drugs may precipitate an attack. Psychological factors have been investigated but have yet to be identified with any specificity.

The severity of asthma attacks varies among individuals, over time, and with the degree of exposure to the triggering factors. Approximately half of all cases of asthma develop during childhood. Another third develop before the age of 40. There are two basic types of asthmaintrinsic and extrinsic. Extrinsic asthma is triggered by allergens while intrinsic asthma is not. Extrinsic asthma, or allergic asthma, is classified as Type I or Type II, depending on the type of allergic response involved. Type I extrinsic asthma is the classic allergic asthma which is common in children and young adults who are highly sensitive to dust and pollen, and is often seasonal in nature. It is characterized by sudden, brief, intermittent attacks of bronchospasms that readily respond to bronchodilators. Type II extrinsic asthma, or allergic alviolitis, develops in adults under age 35 after long exposure to irritants. Attacks are more prolonged than Type I and are more inflammatory. Fever and infiltrates which are visible on chest x-rays often accompany bronchospasm.

Intrinsic asthma has no known immunologic cause and no known seasonal variation. It usually occurs in adults over the age of 35, many of whom are sensitive to aspirin and have nasal polyps. Attacks are often severe and do not respond well to bronchodilators.

A third type of asthma which occurs in otherwise normal individuals is called exercise induced asthma. Individuals with exercise induced asthma experience mild to severe bronchospasms during or after moderate to severe exertion. They have no other occurrences of bronchospasms when not involved in physical exertion. Although the cause of this type of asthma has not been established it is readily controlled by using a bronchodilator prior to beginning exercise.

[Brian R. Barthel ]


RESOURCES

BOOKS

Berland, T. Living With Your Allergies and Asthma. New York: St. Martin's Press, 1983.

Lane, D. J. Asthma: The Facts. New York: Oxford University Press, 1987.

McCance, K. L. Pathophysiology: The Biological Basis for Disease in Adults and Children. St. Louis: Mosby, 1990.

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Asthma

Asthma

Definition

Asthma is a chronic inflammatory disease of the airways in which periods of relatively free breathing are punctuated by episodes in which breathing becomes difficult. During an attack, inflammation causes the airways to fill with mucus secretions and become obstructed. Asthmatics cough, gasp for air, wheeze, gag, and feel choking sensations as they struggle to breathe. Obstruction to airflow usually responds to a wide range of treatments.

Depending of the type of asthma, attacks may be triggered by environmental factors such as cold temperatures, air pollution, smoke, pollen, dust, mildew, mold, and animal hair or dander. Exercise, allergic reactions, respiratory infections, and emotional stress may also trigger attacks. Like other chronic diseases, asthma can be controlled, but not cured.

According to the American Lung Association, in 1998 there were 26 million Americans asthmatics, 10.6 of whom had had an attack during the past year. About a third of all asthmatics are children under 18. Since asthma is often undiagnosed, these statistics probably underestimate the true prevalence of the disease.

Description

The lungs of asthmatics are hypersensitive to stimuli that do not affect healthy lungs. Many patients with asthma react to allergens such as pollen, dust mites, or animal dander, but colds, viruses, and environmental irritants such as dust and pollution can also be triggers.

During an asthma attack, cells in the bronchial walls called mast cells release chemicals that force the bronchial muscle to contract in spasms These chemicals, which include histamine, acetylcholine, and a group of substances called leukotrienes, also bring white blood cells into the area, which is a key part of the inflammatory response. This process also stimulates mucus formation. The entire process creates bronchoconstriction, making it difficult for the asthmatic person to breathe.

Asthma usually begins in childhood or adolescence, but it also may first appear in adulthood. While the symptoms may be similar, certain important aspects of asthma are different in children and adults.

Child-onset asthma

When asthma begins in childhood, it often does so in an atopic child, one who is genetically predisposed to become sensitized to allergens in the environment. Atopy is present in at least one-third and as many as half of the general population. When these children are exposed to dust mites, animal proteins, fungi, or other potential allergens, they produce a type of antibody intended to engulf and destroy the foreign materials. This sensitizes the airway cells to particular allergens. Further exposure can lead rapidly to an asthmatic response.

Adult-onset asthma

Allergies may also play a role in adult-onset asthma, which can start at any age and in a wide variety of situations. Adults may begin to react to allergens such as pollen, dust mites, and pet dander; they may find themselves allergic to aspirin and other drugs; and can even trigger an asthma attack with exercise. Another major cause of adult asthma is occupational exposure (and sensitization) to animal products, certain forms of plastic, wood dust, or metals. In addition, many people have such conditions as sinusitis or nasal polyps that also make them prone to asthma attacks.

Causes and symptoms

In most cases, asthma is caused by inhaling an allergen that sets off the biochemical chain reaction, causing the tissue changes that lead to airway inflammation, bronchoconstriction, and wheezing. Since avoiding, or at least minimizing, exposure is the most effective way to treat asthma, it is vital to identify which allergen or irritant is causing symptoms in each patient. Once asthma is present, symptoms can be triggered or made worse if the patient also has rhinitis (a cold or cold-like symptoms caused by allergies), sinusitis (inflammation or infection of the sinuses), or a viral infection of the respiratory tract (such as influenza ). Gastroesophageal reflux disease (GERD), commonly referred to as acid reflux or heartburn, can also make asthma worse. Some asthmatics are free of symptoms most of the time but may occasionally be short of breath. Others spend their days (and nights) coughing and wheezing, until properly treated.

Allergens and irritants most likely to cause asthma attacks are: smoke, animal dander, dust mites, fungi and molds, cockroach allergens, pollen, and industrial chemicals, fumes, or pollution. In addition, there are three conditions that can also provoke attacks in certain asthmatic patients: inhaling cold air, breathing hard during exercise, and stress or a high anxiety level.

During moderate to severe asthma attacks wheezing may be obvious, but mild attacks can be confirmed by listening to the patient's chest with a stethoscope. Wheezing is often loudest during exhalation, when the patient tries to expel air through narrowed airways. Besides wheezing and shortness of breath, the patient may also cough and report a feeling of tightness in the chest. Children may experience itching on their back or neck. Crying or even laughing may bring on an attack. Severe episodes often occur when patients contract viral respiratory tract infections or are exposed to heavy loads of an allergen or irritant. Asthma attacks may last only a few minutes or can persist for hours or even days (a condition called status asthmaticus).

Shortness of breath may cause a patient to become very anxious, sit upright, lean forward, and use the accessory muscles of respiration to help breathe. The patient may be able to say only a few words at a time before stopping to take a breath. Confusion and a bluish tint to the skin indicate that the patient's oxygen supply is very low and emergency treatment is needed. If a severe attack lasts for some time, air sacs in the lung may rupture, trapping air within the chest. This makes it even harder to breathe in enough air. Fortunately, even patients with the most severe attacks usually recover completely.

Diagnosis

Physical examination

Apart from listening to the patient's chest, the examiner should look for maximum chest expansion while taking in air. Hunched shoulders and contracting neck muscles are other signs of narrowed airways. Nasal polyps or increased amounts of nasal secretions are often noted in asthmatic patients. Skin problems like atopic dermatitis or eczema indicate that the patient has allergic problems. A family history of asthma or allergies can be a valuable indicator. The diagnosis may be strongly suggested when typical symptoms and signs are present.

Spirometry and chest x ray

Spirometry can confirm a diagnosis of asthma by measuring lung function: how much air the lungs can hold and how much they can expel. Asthma patients typically have normal lung volumes with diminished flow rates. Repeating the test after the patient inhales a bronchodilator will show whether the airway narrowing is reversible, a finding that distinguishes asthma from other obstructive diseases like emphysema.

Often patients use a related instrument, called a peak flow meter, to monitor asthma severity at home. Because this device measures the strength with which air is exhaled, it can detect narrowed airways at the earliest stage, before an attack becomes full blown. This allows the patient to take the appropriate medication and diminish or avoid the episode.

Determining what triggers asthma attacks can be difficult. Skin testing may be helpful, although an allergic skin response does not necessarily mean that the allergen being tested is causing the asthma. Once a specific allergen is suspected, a blood test can be run to check for IgE antibodies, since the immune system always produces an antibody in response to an allergen. This will show if the patient is sensitive to a particular allergen. If the diagnosis is still in doubt, the patient can inhale a suspect allergen while using a spirometer to detect airway narrowing, a test called "allergen challenge." Spirometry may also be repeated after a bout of exercise to confirm or refute the diagnosis of exercise-induced asthma. A chest x ray may help to rule out other pulmonary disorders, or confirm findings particular to asthma.

Treatment

Patients should be examined periodically and have their pulmonary function measured by spirometry to ensure that treatment goals are being maintained. The goal is to prevent troublesome symptoms, maintain lung function as close to normal as possible, and allow patients to pursue their normal activities, including those requiring exertion. The best drug therapy is that which controls asthmatic symptoms while causing few or no side-effects.

Drugs

METHYLXANTHINES. The chief methylxanthine is theophylline. It may exert some anti-inflammatory effect, and is especially helpful in controlling nighttime asthma. When, for some reason, a patient cannot use an inhaler to maintain long-term control, sustainedrelease oral theophylline is a good alternative. The blood levels of the drug must be measured periodically, as too high a dose can cause an abnormal heart rhythm or convulsions.

BETA-RECEPTOR AGONISTS. These bronchodilators, such as albuterol, are the best choice for relieving sudden attacks of asthma and for preventing attacks triggered by exercise because they relax the smooth muscles in the lungs. This prevents bronchospasm but doesn't help the swelling that often accompanies an asthma attack. These drugs are effective within about 30 minutes, and are maximally effective for three or four hours. They may be taken by mouth, inhaled, or injected, although the oral forms often produce such side effects as jitters and sleeplessness.

STEROIDS. Steroids and corticosteroids block inflammation and are extremely effective in relieving asthma symptoms. When taken by inhalation for a long period, they reduce the airways' sensitivity to allergens, and asthma attacks become less frequent. This is the strongest medicine for asthma, and can control even severe cases over the long term. Oral or intravenous steroids taken over long periods, however, can cause numerous side effects, including gastric bleeding, loss of calcium from bones, cataracts, and diabetes. Patients on long-term steroid therapy may also have problems with wound healing and weight gain, and may develop mental problems as well. In children, growth may be slowed. Besides being inhaled, steroids may be taken by mouth or injected to control severe asthma rapidly.

LEUKOTRIENE MODIFIERS. Leukotriene modifiers, such as montelukast (Singulair), zileuton (Zyflo), and zafirlukast (Accolate) are drugs that work by counteracting leukotrienes, substances released by white blood cells in the lungs that constrict air passages and promote mucus secretion. They may reduce the need for short-acting inhalers, and may replace inhaled steroid treatment for patients with mild forms of asthma. Leukotrine modifiers may also help asthma patients recover from severe attacks more quickly, and can even help alleviate the allergic rhinitis that often accompanies allergies.

OTHER DRUGS AND TREATMENTS. Cromolyn sodium (Intal) and nedocromil (Tilade) are antiinflammatory agents that stabilize the airways and help prevent the swelling and inflammation that trigger asthma attacks. They can also prevent flareups when given before exercise or when exposure to an allergen cannot be avoided. Like most asthma medication, these drugs must be taken regularly even if there are no symptoms, and require weeks or months of use before they reach their optimum effectiveness.

Anti-cholinergic drugs, such as ipratropium bromide (Atrovent), are useful in controlling severe attacks when added to an inhaled beta-receptor agonist. They help widen the airways and suppress mucus production. The effects of anti-cholingerics usually last longer than beta-agonists, and are often given in combination with bronchodilators to improve breathing.

If a patient's asthma is caused by an allergen that cannot be avoided and has become difficult to control through drug therapy alone, immunotherapy (allergy shots) may be beneficial. In this treatment, increasing amounts of the allergen are injected over a period of three to five years, so the body can build up an effective immune response. There is a risk that this treatment may itself trigger an asthma attack or even anaphylaxis. Immunotherapy has been used since the early twentieth century to treat allergies and hayfever. New studies have indicated that it also reduces asthma symptoms caused by exposure to such allergens as dust mites, ragweed pollen, and cats.

Managing asthmatic attacks

A severe asthma attack can be a medical emergency and should be treated as quickly as possible. It is most important for a patient suffering an acute attack to be given oxygen. Rarely, it may be necessary to use a mechanical ventilator to help the patient breathe. Under a doctor's care, a beta-receptor agonist is inhaled repeatedly or continuously. If the patient does not respond promptly and completely, a steroid is given. An additional course of steroid therapy, given after the attack is over, will make a recurrence less likely.

Once asthma has been controlled for several weeks or months, the dose may be gradually tapered. The last drug added to the regimen should be the first to be reduced. Patients should be evaluated every one to six months, depending on the frequency of attacks.

Long-term treatment

Long-term asthma treatment is based on inhaled medications that are a combination of beta-receptor agonists and steroids. The drugs are delivered to the lungs via special inhalers that meter each dose. While this regimen is usually quite successful in diminishing or preventing attacks, all patients should be taught how to monitor their symptoms so they will know when an attack is starting. Those with moderate or severe asthma can use a peak flow meter to determine if inflammation is increasing.

Asthmatics should also have a written action plan to follow if symptoms suddenly worsen, including how to adjust their medication and when to seek medical care. When deciding whether a patient should be hospitalized, the past history of acute attacks, severity of symptoms, current medication, and whether good support is available at home all must be taken into account.

Referral to an asthma specialist should be considered if:

  • There has been a life-threatening asthma attack or severe, persistent asthma.
  • Treatment for three to six months has been ineffective.
  • Another condition, such as nasal polyps or chronic lung disease, is complicating asthma.
  • Special tests, such as allergy skin testing or an allergen challenge are needed.
  • Intensive steroid therapy has been necessary.

Special populations

INFANTS AND YOUNG CHILDREN. It is especially important to monitor the course of asthma in young patients so that treatment may be diminished or increased as necessary. The health care provider should write out an asthma treatment plan for the child's school. Although asthmatic children often need medication at school to control acute symptoms or to prevent exercise-induced attacks, proper management usually enables a child to take part in physical activities. Only as a last resort should activities be limited.

OLDER ADULTS. Side effects from beta-receptor agonist drugs (including rapid heart rate and tremor) may be more common in older patients. These patients may benefit from receiving an anti-cholinergic drug along with the beta-receptor agonist. If theophylline is given, the dose should be carefully monitored, as older patients may be less able to metabolize this drug. Asthma in older patients may also be complicated by other obstructive lung diseases such as chronic bronchitis or emphysema. It is important to know the extent the symptoms caused by the asthma. A two- to three-week course of steroids can help determine which symptoms are attributable to asthma.

Prognosis

Once the best drug or combination of drugs is found, most patients with asthma respond well and are able to lead relatively normal lives. More than half of affected children stop having attacks by the time they reach twenty-one. Many others have less frequent and less severe attacks as they grow older. In either case ongoing treatment to prevent attacks and urgent measures to control them if they occur are equally important. A small minority of patients will have progressive difficulties breathing. These patients are at risk for respiratory failure and must receive intensive treatment.

Health care team roles

Diagnosis and effective asthma management involve cooperation and collaboration between the patient, family, and an interdisciplinary team of health care professionals. These include the patient's primary health care provider, allergy and immunology specialists, nurses, laboratory technologists, respiratory therapists, pharmacists, pharmacy assistants, and health educators are involved in helping patients and families gain an understanding of how to manage this chronic disease.

Patient education

Nurses, respiratory therapists, and health educators teach patients and families how to prevent, recognize, and manage asthma attacks, including the distinction between mild episodes and those requiring immediate medical attention. They can also train them in stress management techniques that reduce anxiety to help them gain control of this chronic condition.

USING AN INHALER. Perhaps most importantly, these professionals show patients the proper technique for using inhalers and other medications, and stress the importance of compliance. Using a respiratory inhaler properly is a critical skill in asthma management and it's vitally important that patients be instructed in its proper use:

  • Remove the inhaler's cap.
  • Holding the inhaler upright, shake it thoroughly for several seconds.
  • Exhale as much air as possible, while tilting the head back slightly.
  • Hold the inhaler in the position required by the manufacturer. Some should be held an inch or two away from the mouth, others should be placed directly in the mouth.
  • Press the inhaler to dispense the medication.
  • Inhale slowly and deeply through the mouth only for several seconds.
  • Hold the breath for at least 10 seconds; this allows the medication to penetrate into the lungs Take only one breath for each puff.
  • Exhale.
  • Wait a minute or so between puffs (This delay allows the second dose to get even farther into the airways.)

Successful use of metered-dose inhalers requires a close degree of coordination between dispensing the drug and inhaling it. Because this is usually difficult for young children, they are often told to attach "spacers" to their inhalers. These are chambers into which the drug is sprayed before it is inhaled, allowing the medication to be ingested in one or more breaths. For the tiniest patients, masks are attached to the spacers. Many doctors recommend spacers for adult patients as well, since they decrease the chances of using the inhaler improperly, and increase the amount of medication that reaches the lungs. During a severe asthma attack, when patients may not have the ability to inhale a full dose, spacers can literally save lives by allowing patients in distress to take their medication in shorter breaths. Spacers are also usually attached to corticosteroid inhalers.

When using powder inhalers (Rotacaps), patients should close their lips around the inhaler's mouthpiece and inhale quickly. After using a corticosteroid inhaler patients should gargle or rinse their mouths with water to avoid thrush, an overgrowth of yeast in the mouth.

Pharmacists and pharmacy assistants may offer additional instruction about medication use and reiterate the importance of adhering to prescribed treatment.

Prevention

Minimizing exposure to allergens

There are a number of ways patients can reduce exposure to allergens and irritants that provoke asthmatic attacks, or to avoid them altogether:

  • If the patient is sensitive to the family pet, remove the animal or at least keep it out of the bedroom. Keep the pet away from carpets and upholstered furniture. Remove all feathers.
  • To reduce exposure to dust mites, remove wall-to-wall carpeting, keep the humidity down, and use special pillow and mattress covers. Wash bedding in hot water once a week.
  • Reduce the number of stuffed toys, and wash them each week in hot water as well.
  • Eliminate cockroaches using poison, traps, or boric acid rather than chemical pesticides.
  • Keep indoor air clean by vacuuming carpets once or twice a week (with the patient absent), avoid using humidifiers, and use air conditioning during warm weather so windows can remain closed.
  • Avoid exposure to tobacco smoke.
  • Do not exercise outside when air pollution levels are high.
  • To reduce occupational exposure, wear a mask when working with or around irritants. Some patients may find it necessary to find work in a safer environment.

KEY TERMS

Allergen— A foreign substance, such as mites in dust or animal dander which, when inhaled, causes the airways to narrow and produces asthma symptoms.

Allergen challenge— "Provocation" testing in which a patient is exposed to a suspected allergen under controlled conditions.

Atopy— An allergy (probably hereditary) that makes people react immediately to allergens they encounter. Atopic individuals are more likely to develop allergic reactions of any type, including the inflammation and airway narrowing typical of asthma.

Hypersensitivity— The state where even a tiny amount of allergen can cause the airways to constrict and bring on an asthmatic attack.

Spirometry— A test using an instrument called a spirometer that shows how well an asthmatic is breathing, the severity of the asthma, and how well it is responding to treatment.

Resources

BOOKS

American Medical Association. The Washington Manual of Medical Therapeutics, 30th ed. Philadelphia: Lippincott Williams & Wilkins, 2001, pp. 245-251.

ORGANIZATIONS

Asthma and Allergy Foundation of America. 1125 15th St. NW, Suite 502, Washington, DC 20005. 800-7ASTHMA. 〈http://www.housecall.com/sponsors/nhc/1966vha/aafa.html〉.

National Asthma Education Program. 4733 Bethesda Ave., Suite 350, Bethesda, MD 20814. 301-495-4484.

National Jewish Medical and Research Center. 1400 Jackson St., Denver, CO 80206. 800-222-LUNG.

OTHER

Mothers of Asthmatics, Inc. Allergy and Asthma Network. 3554 Chain Bridge Road, Suite 200, Fairfax, VA 22030. 800-878-4403. 〈http://www.aanma.org〉.

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Asthma

Asthma

Resources

Asthma, which is derived from the Greek word aazein, meaning sharp breath, is a lung disease that affects approximately four million people in the United States. In the U.S., close to 10% of those 18 years of age and younger have asthma. In urban areas, surveys have indicated that the rate among this age group can be upwards of 40%.

In people with asthma, the airways of the lungs are hypersensitive to irritants such as cigarette smoke or allergens (compounds that trigger a reaction by the immune system). When these irritants are inhaled, the airways react by constricting, or narrowing. Some people with asthma have only mild, intermittent symptoms that can be controlled without drugs. In others, the symptoms are chronic, severe, and sometimes life threatening.

Asthma is sometimes referred to as a disease of twitchy lungs, which means that the airways are extremely sensitive to irritants. The airways are the tubes (bronchi) that bring air from the windpipe (trachea) to the lungs. An individual bronchus, in turn, branches into smaller tubes called bronchioles. At the end of the bronchioles are small, balloon-like structures called alveoli. The alveoli are tiny sacs that allow oxygen to diffuse into the blood and carbon dioxide to diffuse from body tissues into the lungs to be exhaled.

During an asthma attack, the bronchi and bronchioles constrict and obstruct the passage of air into the alveoli. Besides constricting, the airways may secrete a great deal of mucus in an effort to clear the irritation from the lungs. The airway walls also swell, causing inflammation and further obstruction. As the airways become increasingly obstructed, oxygen cannot reach the small airsacs; blood oxygen levels drop; and the bodys tissues and organs become oxygen-deprived. At the same time, carbon dioxide cannot escape the small airsacs for exhalation; blood levels of carbon dioxide increase and exert a toxic effect on the tissues and organs of the body.

Underlying the bronchial inflammation is an immune response in which white blood cells known as type 2 helper T (Th2) cells are prominent. Th2 cells secrete chemicals known as interleukins that promote allergic inflammation and stimulate another set of cells known as B cells to produce IgE and other antibodies. In contrast, type 1 helper T (Th1) cells produce specific types of interferon and interleukin, which initiate the killing of viruses and other intracellular organisms by activating macrophages and cytotoxic T cells. These two subgroups of helper T cells arise in

response to different immunogenic stimuli and cytokines, and they constitute an immunoregulatory loop: cytokines from Th1 cells inhibit Th2 cells, and vice versa. An imbalance in this reciprocal arrangement may be the key to asthma; when freed from the restraining influence of interferon, the Th2 cells can provoke airway inflammation.

One of the hallmarks of asthma is that the airway obstruction is reversible. This reversibility of the airway swelling is used to definitively diagnose asthma. If the swelling and inflammation can be brought under control with asthma drugs, the person has asthma and not some other upper respiratory tract disease.

In addition to cigarette smoke and various allergens, other triggers can cause asthma attacks. A cold or other upper respiratory infection may bring on an asthma attack. Strong emotions, such as excitement, tension, or anxiety, may trigger asthma symptoms. Exercise can cause symptoms of asthma. Weather conditions, such as extreme cold, heat, or humidity can cause an asthma attack. Pollution and increasing ozone levels are also associated with episodes of asthma. Other environmental factors include occupational exposure to certain substances like animal dander, wood particles, dusts, various industrial chemicals, and metal salts.

The characteristic sign of asthma is wheezing, the noisy, whistling breathing that a person makes as he or she tries to push air in and out of narrowed airways. Other symptoms of asthma include a tight chest, shortness of breath, and a cough.

Currently, several drugs are used to treat asthma. Some patients with mild asthma only need to use medication intermittently to control wheezing, while patients with more serious asthma need to take medication at regular intervals to avoid life-threatening attacks. It is important for asthma patients to see their doctors if the frequency or severity of their symptoms change. It has been suggested that many of the life-threatening asthma attacks are in people who once had mild asthmawith symptoms that could be treated as they occurredwhich then progressed to a more severe case of the disease.

Bronchodilators open up (dilate) constricted lung airways by relaxing the muscles that line the bronchial tubes. Oral bronchodilators include theophylline. A related compound, called aminophylline, is given via injection for severe episodes of asthma. During severe, rapidly-appearing asthma attacks, injections of epinephrine are given just under the patients skin. Epinephrine has a quick, but short-lasting, effect of bronchodilatation.

Most asthma patients are given bronchodilators such as albuterol that are used in a mist form that is inhaled from either a special inhaler device or an aerosol machine. Some patients are instructed to use their bronchodilator at regular intervals, while others may just be told to use the inhaler if they notice the beginning of an asthma attack. The inhaled medications are quick-acting because they are directly applied to the constricted airways.

Salmeterol combines the direct effects of inhaled bronchodilators with the long-lasting protection afforded by oral bonchodilators and is popular for the control of mild and severe asthma.

Asthma also responds favorably to anti-inflammatory drugs, which reduce the swelling and inflammation of the airways. These drugs can be inhaled or taken in pill form. Two types of anti-inflammatory drugs are prescribed for asthma patients: chromolyn sodium and corticosteroids. Chromolyn sodium is also prescribed for people with allergies, and it has few side effects. Oral corticosteroids are very effective in treating asthma, but should be reserved for severe cases due to their serious side effects. Short-term side effects include increased appetite, weight gain, hypertension, and fluid retention. Over the long-term, corticosteroids may cause osteoporosis, cataracts, and impaired immune response. These side effects usually preclude the use of corticosteroids for long periods of time. In fact, short-courses of steroids are preferred. These steroid bursts are given as a treatment for a sudden severe asthma attack, perhaps brought on by exposure to an allergen

KEY TERMS

Bronchiole The smallest diameter air tubes, branching off of the bronchi, and ending in the alveoli (air sacs).

Bronchodilator A drug, either inhaled or taken orally, that dilates the lung airways by relaxing the chest muscles.

Bronchus (plural, bronchi) One of the two main airway tubes that branch off from the windpipe and lead to each lung.

Wheezing The characteristic sound of asthma; it results when a person tries to push air in and out of narrowed airways.

or a viral infection, over about a weeks time and then discontinued.

Inhaled corticosteroids have few side effects. These medications are also prescribed for allergy patients. Unlike their oral counterparts, these drugs can be taken for much longer periods of time. They are especially useful in controlling moderate asthma.

Another newer class of asthma medications are called leukotriene receptor antagonists. These drugs, including an oral medication called zafirlukast, interfere with the actions of a class of chemicals called leukotrienes. Leukotrienes help produce the symptoms of asthma. Interference with their actions decreases asthma symptomatology. The receptor antagonists greatly reduce asthma severity when taken daily and work especially well in conjunction with inhaled steroids and salmeterol inhalers. This regimen (zafirlukast + inhaled steroids + inhaled salmeterol) seems to improve daily living for many asthmatics. Other inhaled bronchodilators are then reserved for exacerbations, such as may occur during a viral infection.

A key to lessening episodes of asthma is eliminating the irritant. If asthma is brought on by cigarette smoke, the patient must avoid this irritant. If asthma is brought on by exercise, the person should try to find a level of exertion that is comfortable. Using an inhaled bronchodilator before exercising may also control asthma symptoms.

Resources

BOOKS

Bellenir, Karen. Asthma Sourcebook: Basic Consumer Health Information about the Causes, Symptoms, Diagnosis, and Treatment of Asthma in Infants, Children, Teenagers, and Adults. Holmes, PA: Omnigraphics, 2006.

Berger, William, and Jackie Joyner-Kersee. Asthma for Dummies. New York: For Dummies, 2004.

Fanta, Christopher H., Lynda M. Cristiano, and Kenan Hayer. The Harvard Medical School Guide To Taking Control Of Asthma. New York: Free Press, 2003.

Kathleen Scogna

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Asthma

Asthma

Definition

Asthma is a chronic inflammatory disease of the respiratory system that makes it hard to breath. The disease is an over-responsiveness of the respiratory system to stimulating factors. Symptoms include repeated, temporary episodes of constriction and inflammation of the airways and lungs, along with excess mucous production. Asthma causes wheezing, coughing, and shortness of breath. Asthma attacks are characterized by severe difficulty breathing, especially when exhaling.

Description

Asthma is a chronic disease that affects the network of air passages of the respiratory system. People with asthma may experience symptoms ranging from mild discomfort to life-threatening attacks that require immediate emergency treatment. The respiratory system is made up of bronchial tubes (airways) and the lungs. Asthma involves inflammation of the bronchial tubes and lining of the lungs. The inflammation causes the airways to be overly sensitive to irritating factors,

Percentage of people in the United States age 65 and over who reported having asthma, by sex and by race, 2005–2006
Data is based on a 2-year average from 2005–2006.
source: National Health Interview Survey, National Center for
Health Statistics, Centers for Disease Control and Prevention,
U.S. Department of Health and Human Services
Sex Percent
Men9.5%
Women11.5%
Total 10.6%
Race Percent
White10.5%
Black12.3%
Hispanic or Latino9.0%

which cause constriction and obstruction to the passageway that brings air to the lungs.

People with asthma produce excess amounts of mucous in the respiratory tract. Mucous is a normal component of respiratory function that aids in carrying irritating particles up and out of the respiratory system to be coughed up from the body. People with asthma produce excessive, abnormally thick mucous that interferes with breathing and contributes to the problem.

Severe asthma attacks can be fatal. Persistent or chronic inflammation of the airways can cause permanent damage. Severe attacks can also reduce lung function so that breathing becomes less efficient even outside of asthma attacks. People with asthma may experience chronic wheezing, coughing, shortness of breath, and tightness in the chest. Medication and careful management of the disease is often necessary for maintaining normal function. Chronic asthma has both a genetic and an environmental component. Research shows that some people inherit a strong genetic predisposition for asthma that can be triggered by a variety of environmental factors. These triggering factors include repeated exposure to lung irritants, such as dust mites, pet hair, and tobacco smoke. These types of stimuli are called allergens, which are particles that trigger an allergic response. Asthma may also be induced by exercise , especially in cold climates where the respiratory system has to work harder to warm and moisten the air that is breathed in. Some people with asthma only experience symptoms during viral infections. Asthma can be brought on by emotional stress . Both physical and psychological factors can bring on an asthma attack. Severe attacks that are left untreated can become fatal. A person with asthma may not have any symptoms between attacks.

Demographics

Asthma is more common in children than adults. In adults, it is more common in women than men. Adult females have a 30% higher prevalence of asthma than adult males. In the United States, nearly 11% of people 65 and older have asthma, compared to 8% in the United Kingdom, 6% in France, and up to 8% in Canada. Within ethnic groups, non-Hispanic blacks have more asthma attacks and are more likely to be hospitalized and die from asthma than non Hispanic whites. Asthma is distinct from, but closely linked to, allergies . Most, but not all, people with asthma have allergies.

Asthma has been described as the fastest-growing chronic disease and a worldwide epidemic. According to Global Initiative for Asthma (GINA), an asthma research and education program, asthma accounts for about one in every 250 deaths worldwide. Many of the deaths are believed to be preventable and are caused by poor medical care. GINA estimates that there are over three million people with asthma worldwide. In most countries, asthma cases are increasing 20–50% every decade. The United States is one of the top countries for prevalence of asthma, along with England, Australia, parts of South America, and Canada.

Causes and symptoms

Causes

People who have a family history of asthma are more likely to develop the condition than people with no family history of asthma. Elderly persons often have more severe asthma than younger people and may be more likely to require urgent medical treatment and hospital admission. In the elderly, the most common causes of late-onset asthma are sensitivity to cat allergen and other allergies, especially dust mites. They are also more likely than younger persons to develop asthma associated with the use of certain medications, including aspirin , nonsteroidal antiinflammatory drugs (NSAIDs), and adrenergic-blocking agents used to treat some types of heart conditions and high blood pressure .

Exercise is a common trigger for asthma in about 80% of asthmatic individuals. Some people with asthma have exercise-induced symptoms brought on by brisk activity such as running, especially during cold weather. Pretreatment medications, such as short-acting bronchodilators , quickly widen air passages and help prevent the onset of asthma during physical activity. Activities that allow for frequent breaks rather than prolonged endurance are most suitable. Asthma does not have to be a barrier to participating in athletic activities. Many Senior Olympic athletes have exercise-induced asthma that is controlled by medication. Emotional stress may also trigger asthmatic symptoms, such as coughing or wheezing from prolonged crying or laughing.

Every asthma patient is unique. Because there are so many environmental conditions that affect individuals with a genetic predisposition for asthma, it is often difficult to pinpoint the primary cause of the disease in individual cases.

Symptoms

There are several common symptoms of asthma. The frequency and intensity depends on each individual person and attack. The symptoms most often experienced include:

  • coughing that is worse at night or early in the morning, making sleep difficult
  • wheezing; a whistling or squeaky sound when breathing, especially during a cold, flu, or other illness
  • tightness in the chest, as if it is being compressed
  • shortness of breath and the feeling of breathlessness
  • difficulty getting enough air in or out of the lungs, especially when exhaling
  • fast breathing; if airflow to the lungs is inadequate, a lack of sufficient oxygen to the tissues causes the body to breathe faster in an attempt to get more oxygen

A person with asthma may have any combination of symptoms, which can vary from one asthma attack to another. Symptoms may exhibit a range of severity, from mildly irritating to life-threatening. Symptoms occur with varying frequency from once every few months to every day. Asthma classifications are based on symptom levels in the absence of medication.

  • Mild intermittent asthma—Defined as symptoms of wheezing, coughing, or breathing difficulty twice a week or less, with night symptoms twice a month or less.
  • Mild persistent asthma—Defined as symptoms of wheezing, coughing, or breathing difficulty once a day or less, but more than twice a week. Symptoms occur at night more than twice a month.
  • Moderate persistent asthma—Defined as daily symptoms that require daily medication. Symptoms at night occur more than once a week. Symptoms may be severe enough to interfere with normal physical activity.
  • Severe asthma—Described as ongoing, persistent symptoms with more serious asthma attacks. Symptoms may occur throughout the day, with night symptoms occurring often. In severe asthma, physical activity is likely to be limited.

People with any degree of asthma may have severe asthma attacks. However, with appropriate treatment and avoidance of asthma stimulators, most people with asthma can achieve a general condition of minimal or no symptoms. People with asthma are encouraged to recognize their own specific asthma stimulators and avoid them, and to recognize their specific early warning signs that signal the start of an attack. The first signs of a mild or moderate attack may be a slight tightening of the chest, coughing or wheezing, and spitting up mucous. Severe attacks can bring on a feeling of extreme tightening of the neck and chest, making breathing increasingly difficult. People with asthma may struggle to speak or breathe. In advanced stages of severe attacks, lips and fingernails may take on a grayish or bluish tinge, indicating declining oxygen levels in the blood. Such attacks can be fatal in the absence of prompt medical attention. Asthma symptoms are usually reversible with medication.

Diagnosis

Asthma is often difficult to diagnose in the elderly due to misconceptions about its prevalence and because older patients often have other conditions that mimic asthma symptoms, such as heart failure and chronic obstructive pulmonary disease (COPD). At least half of elderly people with asthma were recently diagnosed, according to the Canadian Medical Association.

The first stage of asthma diagnosis is to obtain a history of asthma symptoms. These symptoms include periods of coughing, wheezing, shortness of breath, or chest tightness that come on suddenly in response to specific stimulants or time periods. A history of head colds that evolve into chest congestion or take more than 10 days to recover from is pertinent. Family history of asthma or allergies may also be part of the diagnosis.

A physical exam may reveal wheezing in the chest that can be heard with a stethoscope. A device called a spirometer may be used to check the function of the airways. This test measures the volume of air and the speed with which air can be blown out of the lungs after a deep breath. If the airways are narrowed from inflammation and the muscles around the airways tightening up from asthma, the results will be lower than normal. If spirometry results are normal but asthma symptoms are present, other tests are performed. A bronchial challenge test involves inhalation of a substance such as methacholine, which causes narrowing of the airways in asthma. The effect is measured by spirometry to determine if asthma is present.

Treatment

There is no cure for asthma but it can be controlled with proper treatment. In many respects, asthma in the elderly is treated the same as in younger people. Asthma in senior populations is treated by avoiding factors that trigger the condition, such as allergens and certain medications. It is important for elderly patients to give their health care practitioner a complete list of medications, including over-the-counter drugs, that the patient takes both regularly and infrequently.

Asthma is treated primarily by two types of drugs: acute short-term medications and long-term medications. Acute medications give rapid, short-term relief, and are only used when asthma symptoms require immediate treatment. Acute medications are bronchodilators that may be inhaled or taken orally and take effect within minutes to dilate the airways and allow normal breathing. Bronchodilators may be used at the beginning of an asthma attack to provide relief. Bronchodilators may also be used before exercise to prevent exercise-induced asthma symptoms. Long-term control medications are taken daily over long periods of time to control chronic symptoms and prevent asthma attacks. The full effect of these medications requires several weeks of use.

Individuals with persistent asthma require long-term control medications. The most effective long-term control medication for asthma is an inhaled corticosteroid. Corticosteroids reduce the swelling of airways and help to prevent asthma attacks from occurring. Inhaled corticosteroids are preferred for treatment of all levels of persistent asthma. In some cases, steroid tablets or liquid medications are used temporarily to control asthma. Prolonged treatment of the elderly with oral corticosteroids can cause high blood pressure, diabetes, weight gain, and osteoporosis—a disease, occurring especially in women after menopause , in which the bones become very porous, break easily, and heal slowly. Physicians treating older patients for asthma need to take measures to prevent osteoporosis from developing.

Other types of asthma medications inhibit the inflammatory mediators released in the asthma response. Long-acting bronchiodialators, such as montelukast (Singulair), are also available for use as inhalers. A newer treatment, omalizumab (Xolair), is an antibody directed at the antibody IgE that is produced in allergic reactions. It is primarily used for allergic asthma that does not respond well to more standard therapies. Some long-term control medications may be used in combination with inhaled corticosteroids to treat moderate persistent and severe persistent asthma.

Long-term control medications are used to prevent an asthma attack and will not stop a currently occurring asthma attack. Many people with asthma require both a short-acting bronchodilator to use when symptoms worsen and a long-term daily asthma control medication to treat ongoing inflammation.

Emergency treatment

Emergency care may be necessary during a severe asthma attack. Emergency care takes place in a hospital setting and may include treatment with high levels of bronchodilators and corticosteroids, additional medications, and oxygen administration in an attempt to restore normal breathing. Delayed access to emergency treatment can lead to complete respiratory failure where the patient simply stops breathing and cannot be revived. In cases of allergic asthma, allergy shots may assist in reducing symptoms. Allergy shots, also known as allergen immunotherapy, are recommended for people who have allergic asthma but cannot avoid contact with the allergens that stimulate asthma. A series of shots with controlled and gradually increasing amounts of allergen are given over a number of months or years. The shots are vaccines containing various allergens, such as pollen or dust mites. Increased exposure to the allergen desensitizes the immune system to allergen triggers. Allergy shots can diminish the severity of asthma symptoms and lower the dosage of required asthma medications.

Nutrition/Dietetic concerns

There is some evidence of a link between obesity and asthma. It is important for people with asthma who are overweight or obese to reduce their weight to a normal level. Obese people without asthma who reduce their weight to a normal level may lessen their risk of developing asthma. Use of a class of medications called bisphosphonates, primarily used to strengthen bones, along with vitamin D and calcium supplements is recommended in older patients who require prolonged use of oral corticosteroids to treat their asthma.

Therapy

Use of an inhaler to take asthma medications is usually required, especially in people with severe asthma. It is important as a quality of life issue that elderly persons with asthma chose an inhaler that is both comfortable and easy for them to use.

Prognosis

When medication is used properly, the prognosis for most people with asthma is excellent. An improvement in environmental conditions can reduce the number and severity of asthma attacks and improve the prognosis for people with asthma. Elderly patients with severe asthma may develop anxiety and depression . Proper treatment and management can dramatically improved the quality of life for older people with asthma.

QUESTIONS TO ASK YOUR DOCTOR

  • What treatments are available to treat my asthma?
  • What are the side effects of asthma treatments?
  • Are there alternative or complementary treatments available?
  • What are inhalers and how are they used?
  • How will asthma affect what I can do?
  • What do I do if I have an asthma attack?

Prevention

There is no known way to prevent asthma but there are ways to decrease the chances of having an asthma attack.

  • Learning about asthma and how to control it.
  • Using medications under a doctor's guidance to prevent or stop attacks.
  • Avoiding things that make asthma worse.
  • Getting regular medical check-ups.
  • Following an asthma self-management plan developed in conjunction with a physician.

Caregiver concerns

It is important for the caregiver to recognize symptoms of asthma and know how to react when the person they are caring for has an asthma attack. The caregiver should know where the patient's medication inhalers are kept and ensure the supply does not run out. At the first signs of an asthma attack, the caregiver should:

  • Sit the person upright, remain calm, and provide the person with reassurance. Do not leave the person alone.
  • Give the person four puffs from an inhaler, one puff at a time, preferably through a spacer device. Have the person take four breaths from the spacer after each puff of medication. If no spacer is available, use a inhaler on its own.
  • Wait four minutes. If there is little or no improvement, the caregiver should repeat the inhaler treatment.
  • If there is still little or no improvement, immediately call for an ambulance, paramedics, or fire-rescue. Continue inhaler treatment until medical help arrives.

KEY TERMS

Adrenergic-blocking agents —Medications used to treat some types of heart conditions and high blood pressure.

Allergen —A substance or organism foreign to the body; allergens stimulate the immune system to produce antibodies.

Allergy —A condition in which the immune system is hypersensitive to contact with allergens; an abnormal response by the immune system to contact with an allergen; condition in which contact with allergen produces symptoms such as inflammation of tissues and production of excess mucus in respiratory system.

Antibody —A protein produced by the mature B cells of the immune system that attach to invading microorganisms and target them for destruction by other immune system cells.

Bronchial tubes —The tubular passages that form part of a network of airways to and within the lungs.

Bronchodilators —Drugs that relax the main air passages in the bronchial tubes that carry air in and out of the lungs.

Chronic obstructive pulmonary disease (COPD) —A term referring to two lung diseases, chronic bronchitis and emphysema, that are characterized by obstruction to airflow that interferes with normal breathing.

Corticosteroid —A steroid hormone produced by the adrenal gland involved in metabolism and immune response.

Hypersensitive —A process or reaction that occurs at above normal levels; overreaction to a stimulus.

Inflammation —Swelling and reddening of tissue; usually caused by the immune system's response to the body's contact with an allergen.

Spirometer —An instrument for measuring the capacity of the lungs.

Resources

BOOKS

Berger, William E., M.D. Asthma for Dummies. Hoboken, NJ: Wiley Publishing, 2006.

Mahmoudi, Massoud. Allergy and Asthma: Practical Diagnosis and Management. New York: McGraw-Hill, 2007.

Mitchell, Dean. Dr. Dean Mitchell's Allergy and Asthma Solution: The Ultimate Program for Reversing Your Symptoms One Drop at a Time. New York: Marlowe & Company, 2006.

Pulmonary Disorders of the Elderly: Diagnosis, Prevention, and Treatment, edited by Thomas Petty and James S. Seebass. Philadelphia: American College of Physicians, 2007.

PERIODICALS

Bellia, Vincenzo, et al. “Asthma in the Elderly.” Chest October 2007: 1175–1182.

Fanta, Christopher H. “Plan for an Asthma Attack.” Adult Asthma (Harvard Special Health Report) Annual 2007: 41–43.

King, Monroe James. “Identifying and Treating Comorbidities Can Be Crucial—How Best to Diagnose and Control Asthma in the Elderly.” Journal of Respiratory Diseases June 1, 2006: 238.

Ramos, Rosemarie G., et al. “Community Urbanization and Hospitalization of Adults for Asthma.” Journal of Environmental Health April 2006: 26–32.

Wendling, Patrice. “Asthma Deaths Declining Overall, Most Common in Elderly.” Internal Medicine News June 1, 2006: 12.

“What Works Best to Control Asthma in Older Adults? It Isn't Only a Disease that Affects Children; Older People Can Suffer From Asthma, Too.” Focus on Healthy Aging December 2007: 1–2.

ORGANIZATIONS

American Academy of Allergy, Asthma, and Immunology, 555 E. Wells St., Suite 1100, Milwaukee, WI, 53202-3823, (414) 272-6071, (800) 822-2762, [email protected], http://www.aaaai.org.

American Lung Association, 61 Broadway, 6th Floor, New York, NY, 10006, (212) 315-8700, (800) 548-8252, http://www.lungusa.org.

Asthma and Allergy Foundation of America, 1233 20th St., NW, Suite 402, Washington, DC, 20036, (202) 466-7643, (800) 727-8462, [email protected], http://www.aafa.org.

British Lung Foundation, 73–75 Goswell Road, London, United Kingdom, EC1V 7ER, 08458 50 50 20, [email protected], http://www.lunguk.org.

National Heart, Lung, and Blood Institute, P.O. Box 30105, Bethesda, MD, 20824-0105, (301) 592-8573, (240) 629-3246, [email protected], http://www.nihlbi.nih.gov.

The Lung Association, 1750 Courtwood Crescent, Suite 300, Ottawa, ON, Canada, K2C 2B5, (613) 569-6411, (888) 566-5864, (613) 569-8860, [email protected], http://www.lung.ca.

Ken R. Wells

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Asthma

ASTHMA

Asthma is the most common chronic illness seen in childhood, affecting 5 to 15 percent of children in the United States, approximately 3 million children younger than eighteen years of age. One-third of these children have severe asthma. Over the last twenty-five years, there has been an increase in the prevalence of asthma. Although part of this may be attributed to physicians diagnosing asthma earlier in children, there still seems to be a real rise in the number of children worldwide with asthma. In the United States, African-American children are more likely to have asthma and more severe instances of the disease compared to Caucasian children. African-American children under four years of age are hospitalized four times as often for their asthma. Crowded inner city living also has been shown to increase a child's likelihood of having asthma, regardless of race. The inner city environment has particles or allergens such as air pollutants that sensitize these children to develop asthma. Urban settings provide increased allergic exposures and increased viral infections early in life (possibly secondary to earlier daycare placement), and crowding. Furthermore, asthma tends to be more severe among children, resulting in higher death rates for children with asthma. Other associated factors include prematurity, low birthweight, poor nutrition, lack of breastfeeding, and low family income. Genetics also plays a role in developing asthma. If one parent is affected with asthma, the child is three times as likely to develop asthma compared to a child with non-asthmatic parents; if both parents have asthma, the risk increases sixfold.

Asthma is an illness that affects the lungs, specifically the airways. Air enters the body through the nose or mouth. It then enters the trachea, also known as the windpipe. This is the large main airway of the lungs. The trachea then divides into two smaller pipes called bronchi that bring air to both the right and left lungs. These airways then divide into many smaller airways called bronchioles. These small airways eventually bring air (and oxygen) to the smallest sub-unit of the lung called the alveolus. The alveolus is where oxygen enters the blood and where carbon dioxide is released. There are hundreds of thousands of alveoli in each lung.

The airways are made up of three parts. First there are the smooth muscle cells that surround the airway. These cells allow the airway to get bigger or smaller by relaxing or contracting. These muscles are involuntary, meaning that they cannot be consciously moved. They respond to local chemicals and nerves to relax and contract. The second part is the lining of the tube, which is made of normally thin cells called epithelial cells. These cells help to protect the body from particles (such as viruses or bacteria) that may be breathed in but that should not be absorbed into the lungs or the body. The cells do this by trapping particles in mucus and moving them out by a brush border, which acts as a moving carpet by beating and bringing the particle laden mucus back out of the lungs. When the particles get closer to the throat, a person can feel them and is then stimulated to cough to get them out of the lungs. The third part is the lumen, or airway opening through which the air passes on its way to the alveolus to bring oxygen to the lungs (that will then be used by the body). The size of this lumen is affected by the smooth muscle, the lining cells, and by any debris (mucus and particles).

When someone has an acute asthma attack, their airways narrow because of smooth muscles, swelling or edema of the airway lining cells, and production of excessive mucus by these cells, making it more difficult to move air in and out of the lungs. When this happens, the patient will often cough, breathe more quickly than normal, and feel short of breath. People with asthma may also have noisy breathing, or wheezing. Wheezing occurs because the patient must still move the same amount of air through a narrower airway in the same amount of time. This means the air has to move faster to move past these narrow areas. This is heard as wheezing. The process is similar to water flowing through a narrowed pipe or tube; for example, through a nozzle. Water flow becomes noisy and audible, where it is normally quiet. Wheezing, however, may also occur in patients who do not have asthma but may have airway narrowing for other reasons such as a foreign body in the airway. Very young children may wheeze in response to a cold but may not have asthma when they get older. Patients having an asthma attack also can appear to be breathing hard, using extra muscles like their abdomen, shoulders and rib muscles to breathe. If allowed to continue without treatment, a patient will continue to work harder and harder until the muscles of breathing are exhausted, thus leading to death. Patients with asthma may be mildly to severely ill with an asthma attack, and symptoms can progress very quickly if not treated.

Many things can cause asthma attacks. For some people key triggers can be identified. Triggers are environmental, infectious, or social causes that set off a person's asthma. Common triggers include pollens, cigarette smoking, secondhand smoke exposure, dust mites, molds, pet dander, colds, cold air, exercise, stress, and changes in weather. These triggers are sensed by the lungs and the body over-responds, causing an asthma attack. Some patients have asthma where no clear trigger can be identified. Individuals with many allergies are at higher risk for getting asthma. People with eczema (an itchy dry skin condition often associated with allergies) also are more likely to have asthma.

Treatment of asthma requires a whole life approach. Prevention of attacks is extremely important, especially in children with moderate to severe asthma. This requires a multifactorial approach involving attention to and potential changes in all spheres of a child's life, including home and school. Environmental modification includes elimination of triggers such as cigarette smoke, pet dander, dust, molds, pollens, and insects (especially cockroaches). Special care to avoid colds is also important. Furthermore, some children require preventive or prophylactic medicine daily to decrease the number of attacks. These include anti-inflammatory medications in more severe cases of asthma, to help decrease inflammation and swelling of airway lining cells. Once an acute asthma attack has started, treatment consists of albuterol, which immediately relaxes the smooth muscle to help open the airway. Steroids can also increase airway size by decreasing acute inflammation. Oxygen may also be needed. Education of patient, family, and other caregivers in the early recognition of symptoms is key to successful treatment of an asthmatic attack, and improving baseline lung functioning.

Asthma, like any chronic illness, can have a significant impact on a child's psychosocial functioning and development. Children with asthma exhibit a threefold increase in school absences (on average) when compared to children without asthma. A study by Fowler from 1992 also suggests a potential link between asthma and learning disabilities in children with poor to fair health because of severe asthma with poorer school performance. Children with asthma who come from lower income families (household income less than $20,000 per year) were twice as likely to fail a grade than healthy children from low income homes in this study.

Children with asthma also exhibit increased emotional vulnerability. They may demonstrate anxiety regarding their asthma, and feel physically vulnerable as well, sometimes out of proportion to the severity of their asthma. Anxiety with hyperventilation can be a trigger for stress-induced asthma attacks. Young children with moderate to severe asthma may have great fears and anxieties regarding their health and fear of death at a very young age. In addition to the child, parents also develop fear and anxiety in relation to their child with chronic illness, which also may be out of proportion to the severity of the child's asthma. This can lead to increased parental sheltering and over protectiveness, giving rise to the vulnerable child syndrome and feeding the child's anxiety.

Asthma can also be an isolating illness for school-age children. Increased school absences take them away from their friends and peers. Having to leave the classroom to receive medicines or treatments also may give the child a sense of being set apart from peers and therefore different. Furthermore, classmates may perceive the child as being "sick" and may treat him differently as a result, further impairing bonding with peers.

In conclusion, asthma is a common illness among children. It affects their physical, psychosocial, and emotional lives. Effective management involves the child, family, pediatrician, school personnel, and when needed, allergy specialists to minimize symptoms and allow children with asthma to thrive.

See also:CHRONIC ILLNESS

Bibliography

Bloomberg, G. R. "Crisis in Asthma Care." Pediatric Clinics of North America 39 (1992):1225-1241.

Brugman, S. M. "Asthma in Infants and Small Children." Clinics inChest Medicine 16 (1995):637-656.

Fowler, M. G. "School Functioning of U.S. Children with Asthma."Pediatrics 90 (1992):939-944.

Gern, J. E. "Childhood Asthma: Older Children and Adolescents."Clinics in Chest Medicine 16 (1995):657-670.

Hoekelman, Robert, Stanford B. Friedman, and Modena E. H. Wilson, eds. Primary Pediatric Care, 3rd edition. St. Louis: Mosby, 1997.

Morgan, W. J. "Risk Factors for Developing Wheezing and Asthma in Childhood."Pediatric Clinics of North America 39 (1992):1185-1203.

Warner, J. O. "Third International Pediatric Consensus Statement on the Management of Childhood Asthma."Pediatric Pulmonology 25 (1998):1-17.

Ericka V.Hayes

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Asthma

Asthma

Asthma is a lung disease that affects approximately four million people in the United States. In people with asthma, the airways of the lungs are hypersensitive to irritants such as cigarette smoke or allergens. When these irritants are inhaled, the airways react by constricting, or narrowing. Some people with asthma have only mild, intermittent symptoms that can be controlled without drugs. In others, the symptoms are chronic, severe, and sometimes life threatening. Although researchers have learned more about the underlying causes of asthma in recent years, a definitive treatment is still unavailable. In fact, deaths from asthma are on the rise. In the last decade, asthma deaths worldwide rose 31%. The reasons for this increase are not clear; however, many experts believe that the lack of standard treatments and the inconsistent monitoring of asthma patients have contributed to the increased mortality rate .


What is asthma?

Asthma is sometimes referred to as a disease of "twitchy lungs," which means that the airways are extremely sensitive to irritants. The airways are the tubes that bring air from the windpipe, or trachea, to the lungs. These tubes are called the bronchi. Each bronchus, in turn, branches into smaller tubes called bronchioles. At the end of the bronchioles are small, balloon-like structures called alveoli. The alveoli are tiny sacs that allow oxygen to diffuse into the blood and carbon dioxide to diffuse from body tissues into the lungs to be exhaled.

During an asthma attack, the bronchi and bronchioles constrict and obstruct the passage of air into the alveoli. Besides constricting, the airways may secrete copious amounts of mucus in an effort to clear the irritation from the lungs. The airway walls also swell, causing inflammation and further obstruction. As the airways become increasingly obstructed, oxygen cannot reach the small airsacs; blood oxygen levels drop and the body's tissues and organs become oxygen-deprived. At the same time, carbon dioxide cannot escape the small airsacs for exhalation; blood levels of carbon dioxide increase, and exert a toxic effect on the tissues and organs of the body.

Underlying the bronchial inflammation is an immune response in which white blood cells known as type 2 helper T (Th2) cells (a type of CD4 helper T cell ) are prominent. Th2 cells secrete chemicals known as interleukins that promote allergic inflammation and stimulate another set of cells known as B cells to produce IgE and other antibodies. In contrast, type 1 helper T (Th1) cells, another class of CD4 T cells , produce interferon-g and interleukin-2, which initiate the killing of viruses and other intracellular organisms by activating macrophages and cytotoxic T cells. These two subgroups of helper T cells arise in response to different immunogenic stimuli and cytokines, and they constitute an immunoregulatory loop: cytokines from Th1 cells inhibit Th2 cells, and vice versa. An imbalance in this reciprocal arrangement may be the key to asthma and there is credible evidence that, when freed from the restraining influence of interferong, Th2 cells can provoke airway inflammation. Recent experiments in support of this concept have focused on a newly discovered transcription factor, T-bet, which is necessary to induce helper T cells to differentiate into Th1 cells and for Th1 cells to produce interferon-g. For these reasons, T-bet is thought to be central to the feedback loops that regulate Th1 and Th2 cells, and in this way it could be important in asthma.

One of the hallmarks of asthma is that the airway obstruction is reversible. This reversibility of the airway swelling is used to definitively diagnose asthma. If the swelling and inflammation can be brought under control with asthma drugs, the person has asthma and not some other upper respiratory tract disease.

In addition to cigarette smoke and various allergens, other triggers can cause asthma attacks. A cold or other upper respiratory infection may bring on an asthma attack. Strong emotions, such as excitement, tension, or anxiety , may trigger asthma symptoms. Exercise can cause symptoms of asthma. Weather conditions, such as extreme cold, heat , or humidity can cause an asthma attack. Pollution and increasing ozone levels are also associated with episodes of asthma. Other environmental factors include occupational exposure to certain substances like animal dander, wood particles, dusts, various industrial chemicals, and metal salts.

The characteristic sign of asthma is wheezing, the noisy, whistling breathing that a person makes as he or she tries to push air in and out of narrowed airways. Other symptoms of asthma include a tight chest, shortness of breath, and a cough.


Treatment of asthma

Currently, several drugs are used to treat asthma. Not all of the asthma drugs, however, should be used by every asthma patient. Some patients with mild asthma only need to use medication intermittently to control wheezing, while patients with more serious asthma need to take medication at regular intervals to avoid life-threatening attacks. It is important for asthma patients to see their doctors if the frequency or severity of their symptoms change. It has been suggested that many of the life-threatening asthma attacks are in people who once had mild asthma—with symptoms that could be treated as they occurred—which then progressed to a more severe case of the disease.

Bronchodilators dilate constricted lung airways by relaxing the muscles that line the bronchial tubes. Oral bronchodilators include theophylline; theophylline's counterpart, aminophylline, is used through a needle in the vein (intravenous or IV) for severe episodes of asthma. During severe, acute attacks of asthma, injections of epinephrine are given just under the patient's skin. Epinephrine has a quick, but short-lasting effect of bronchodilatation.

Most asthma patients are given bronchodilators such as albuterol that are used in a mist form that is inhaled from either a special inhaler device or an aerosol machine. Some patients are instructed to use their bronchodilator at regular intervals, while others may just be told to use the inhaler if they notice the beginning of an asthma attack. The inhaled medications are quick-acting because they are directly applied to the constricted airways.

In the 1990s, some controversy about inhaled bronchodilators arose in the medical field. In a study published in 1993, doctors found an increased risk of death or near-death from asthma when patients used a type of inhaled bronchodilator commonly prescribed to control asthma. Although more information is still needed regarding the reasons behind the increase in deaths and near-deaths and their association with inhaled bronchodilators, some experts think that the association can be explained by several factors:

  1. More people who use inhaled bronchodilators die because their asthma suddenly becomes more severe and they do not see their doctors. These patients are treating severe asthma with a drug usually prescribed for milder forms.
  2. Bronchodilators may have long-term effects on organ systems.
  3. Bronchodilators may, over time, increase airway hyper-responsiveness.
  4. Physicians are not adequately monitoring their patients for progression from mild to severe asthma.

These factors are currently being investigated. Asthma experts stress, however, that people with asthma who use inhaled bronchodilators should continue to do so, but under medical supervision. They should also immediately contact their physicians if they notice a change in the severity and frequency of their symptoms.

A newer inhaled bronchodilator, called salmeterol, combines the direct effects of inhaled bronchodilators with the long-lasting protection afforded by oral bonchodilators. Salmeterol offers a new, effective drug choice for mild and severe asthma.


Anti-inflammatory drugs

Anti-inflammatory drugs reduce the swelling and inflammation of the airways. These drugs can be inhaled or taken in pill form. Two types of anti-inflammatory drugs are prescribed for asthma patients: chromolyn sodium and corticosteroids. Chromolyn sodium is also prescribed for people with allergies, and it has few side-effects. Oral corticosteroids are very effective in treating asthma, but should be reserved for severe cases, due to their serious side-effects. Short-term side effects include increased appetite, weight gain, hypertension , and fluid retention. Over the long-term, corticosteroids may cause osteoporosis , cataracts, and impaired immune response. These side-effects usually preclude the use of corticosteroids for long periods of time. In fact, short-courses of steroids are preferred. These "steroid bursts" are given over about a week's time and then discontinued, as a treatment for a sudden severe asthma attack, perhaps brought on by exposure to an allergen or a viral infection.

Inhaled corticosteroids have few side effects. These medications are also prescribed for allergy patients. Unlike their oral counterparts, these drugs can be taken for much longer periods of time. They are especially useful in controlling moderate asthma.

Another newer class of asthma medications are called leukotriene receptor antagonists (LTRAs). These drugs, including an oral medication called zafirlukast, interfere with the actions of a class of chemicals called leukotrienes. Leukotrienes help produce the symptoms of asthma. Interference with their actions decrease asthma symptomatology. LTRAs are thought to greatly reduce asthma severity, when taken daily. LTRAs seem to work especially well in conjunction with inhaled steroids and salmeterol inhalers. This regimen (zafirlukast + inhaled steroids + inhaled salmeterol) seems to improving daily living for many asthmatics. Other inhaled bronchodilators are then reserved for exacerbations, such as may occur during a viral infection.


Can asthma attacks be prevented?

Asthma experts are currently working to dispel many myths about asthma. For instance, it was once thought that increasing fluid intake would lessen mucus production and therefore lessen the frequency and severity of asthma attacks. But drinking lots of water does not affect asthma (although drinking a lot of water is a good idea for maintaining general health).

Breathing into a paper bag is also a bad idea for someone with an asthma attack. Persons with asthma should avoid over-the-counter medications advertised to treat asthma.

Depending on the triggers associated with asthma attacks, patients can sometimes avoid attacks by taking certain preventive steps. If allergens such as dust and pollen trigger an attack, asthma can be avoided by doing the following:

  1. Avoid being outside during the early morning and late afternoon hours, when pollen levels are highest.
  2. Since dust has been associated with asthma attacks, thoroughly and frequently clean the indoor environment. Dust and vacuum every day. Wash bed linens in hot, soapy water every few days. Replace air filters in air conditioners and furnaces regularly.
  3. During hot weather, use air conditioning.

Eliminating the irritant is the key. If asthma is brought on by cigarette smoke, the patient must avoid this irritant. If asthma is brought on by exercise, the person should try to find a level of exertion that is comfortable. Using an inhaled bronchodilator before exercising may also control asthma symptoms.

For all persons with asthma, communication with and regular visits to their physicians are essential components of treatment. Without periodic check-ups, the physician cannot monitor progress or potential worsening of symptoms. Thus, the most important aspect of prevention and treatment for asthma patients is the regular physician visit.

See also Antibody and antigen; Respiratory diseases; Respiratory system.


Resources

books

Adams, Francis V., MD. The Asthma Sourcebook: EverythingYou Need to Know. 2nd ed. New York: McGraw-Hill, 1998.

Lavy, M., Hilton, S., Barnes, G. Asthma at Your Fingertips, 3rd ed. London: Class Publishing, 2000.

Periodocals

Spilner, Maggie. "Get Off the Asthma Tightrope." Prevention 46, no. 9 (September 1994): 88.

Other

American Lung Association. 61 Broadway, 6th Floor New York, New York 10006. 1–800–LUNG–USA (1–800–586–4872).) Asthma Website [cited October 16, 2002]. <www.lungusa.org/asthma>.

National Asthma Education Program, Expert Panel. ExecutiveSummary: Guidelines for the Diagnosis and Management of Asthma. Washington, DC: U.S. Department of Health and Human Services, Public Health Service, National Institutes of Health, 1997.


Kathleen Scogna

KEY TERMS

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Bronchiole

—The smallest diameter air tubes, branching off of the bronchi, and ending in the alveoli (air sacs).

Bronchodilator

—A drug, either inhaled or taken orally, that dilates the lung airways by relaxing the chest muscles.

Bronchus (plural, bronchi)

—One of the two main airway tubes that branch off from the windpipe and lead to each lung.

Wheezing

—The characteristic sound of asthma; it results when a person tries to push air in and out of narrowed airways.

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Asthma

Asthma

Definition

Asthma is a chronic inflammatory disease of the respiratory system that causes breathing difficulty. Asthma comes from the Greek word for panting. The disease is an over-responsiveness of the respiratory system to stimulating factors. It is characterized by repeated, temporary episodes of constriction and inflammation of the airways and lungs, along with excess mucous production. Asthma causes wheezing, coughing, and shortness of breath. Asthma attacks are characterized by severe difficulty breathing, especially when exhaling. Severe attacks that are left untreated may become fatal. An individual with asthma may be completely without symptoms between attacks.

Description

Asthma is a chronic, lifelong disease that affects the complex network of air passageways of the respiratory system. People with asthma may experience from mild discomfort to life-threatening attacks that require immediate emergency treatment. The respiratory system is made up of bronchial tubes (airways) and the lungs. Asthma involves the inflammation of the bronchial tubes and lining of the lungs. The inflammation causes the airways to be overly sensitive to irritating factors, which cause constriction and obstruction to the passage of air into the lungs. Asthmatics also produce excess amounts of mucous in the respiratory tract. Mucous is a normal component of respiratory function that aids in carrying irritating particles up and out of the respiratory system to be expectorated (coughed up) from the body. Asthmatics produce excessive, abnormally thick mucous that interferes with breathing and contributes to the problem. Severe asthma attacks can be fatal. Persistent or chronic inflammation of the airways can cause permanent damage, or airway "remodeling," and reduce lung function so that breathing becomes less efficient even outside of asthma attacks. Asthmatics may experience chronic wheezing, coughing, shortness of breath, and a feeling of a tightening of the chest. Medication and careful management of the disease is often necessary for maintaining normal function.

Chronic asthma has both a genetic and an environmental component. Research has demonstrated that some individuals inherit a strong genetic predisposition for asthma that can be triggered by a variety of environmental factors. Stimuli for triggering asthmatic symptoms include repeated exposure to irritants, such as dust mites, pet hairs, and tobacco smoke. These types of stimuli are considered allergens, or particles that trigger an allergic response. Asthma may also be induced by exercise, especially in cold climates where the respiratory system has to work harder to warm and moisten inhaled air. Some asthmatics only experience symptoms during viral infections. Asthma may also be stimulated by emotional stress. Both physical and psychological factors may precipitate an asthma attack.

Genetic profile

Asthma is a complex heritable disease in which a number of different genes contribute to asthmatic predisposition. While genes may cause a predisposition to asthma, actual asthma attacks are triggered by stimulating environmental factors. It has been clearly established that asthma tends to run in families. Research demonstrates increased risk of developing asthma for children of asthmatics. Studies also show that identical twins are more likely to share a genetic predisposition for asthma than are fraternal (non-identical) twins.

According to the National Institutes of Health (NIH) in 2005, chromosomes 5, 6, 11, 14, and 12 have all been implicated in asthmatic predisposition. However the relative role each of these genes has in asthma predisposition is not clear. One of the most likely candidates for further investigation is chromosome 5. Chromosome 5 is full of genes-encoding molecules involved in the inflammatory response that characterizes asthma.

Research studies show that specific symptoms experienced by asthma patients, such as the inflammation of the airways and lungs, are initiated by the action of genes that regulate the activity of the immune system. In other words, these genes control how the immune system responds to the presence of substances that can potentially trigger asthma symptoms. Like a microscopic army, the immune system consists of a wide array of specialized cells that work together to neutralize threats to the system. Antigens are any foreign agent invading the body that triggers such an immune response. Antigens include disease-producing organisms such as viruses, toxic chemicals in the environment, or allergens such as animal dander and dust mites. In response to the identification of foreign antigen particles, some immune cells produce antibodies to attack specific types of antigens. This immune response occurs after an initial encounter with an antigen and is known as a primary immune response. The immune system recognizes past contact with specific antigens by maintaining specific levels of the antibodies customized to attack specific antigens. When the same antigen is encountered again, the specific antibodies that have been maintained in the body multiply and mount a stronger immune response than the primary response. This process is known as the secondary immune response.

One of the specific antibodies produced in response to allergens is a protein known as immunoglobulin E (IgE), encoded by chromosome 5. In a normal inflammatory response, IgE recognizes foreign antigens and initiates immune reactions against the antigen by binding to other immune cells such as mast cells. Mast cells release chemical mediators that contribute to inflammation directly, but also recruit more immune cells to the site of inflammation. The recruited immune cells also release mediators of inflammation, such as histamine, that amplify the response and cause inflammation. Chromosome 5 encodes for multiple components of this immune response. In asthmatics, the IgE mast cells are highly excitable, making them hypersensitive to stimulation. When foreign antigens are breathed into the respiratory system, the entire inflammatory process, including the recruitment of other immune cells that release histamine, becomes exaggerated, resulting in asthma.

Research indicates that asthmatics produce higher levels of IgE antibodies, more hyperactive mast cells, and higher levels of consequent histamine than non-asthmatics. Histamine is a type of chemical signal that initiates the inflammatory response. Histamine stimulates the dilation of blood vessels walls and makes them more porous. As a result, blood fluid and proteins leak out of the blood vessels and into surrounding tissue, causing the swelling and reddening typical of inflammation. Inflammation involves increased blood flow to affected tissues to allow the passage of the recruited immune cells from the blood into the affected tissues. The immune cells may then dispose of the foreign particles. While this response is designed to defend the tissue from foreign invasion of harmful particles, an exaggerated response can be dangerous. In asthma, the resultant inflammation, along with the reactive constriction of the muscles in walls of the bronchial airways, narrows the air passages and causes an asthma attack.

Another component of the immune defense is the production of nitric oxide gas (NO) by an enzyme called inducible nitric oxide synthase (iNOS). Cells lining the bronchial tubes contain this enzyme that produces NO in response to chemical signals released from immune cells. Asthmatics produce an abnormally high level of iNOS in their respiratory cells than do non-asthmatics. Asthmatics have higher levels of NO in their lungs and bronchial tubes that contribute to the disease.

While chromosome 5 is implicated in asthma, there is conflicting evidence as to whether the genes responsible for the hyperactivity of the immune response in bronchial passages are distinct from the genes that regulate the action of the immune system. However, a region of chromosome 5 involved in the regulation of the immune system has been named bronchial hyperresponsiveness-1 (BHR1). Research on the BHR1 region is currently being performed by the NIH, in addition to other genetic regions. Another possible contributing factor for the overproduction of IgE antibodies could be a lack of exposure to common childhood illnesses. For example, cold viruses and other respiratory illnesses stimulate the human immune system to produce a certain type of immune cell, called a helper T cell, which specifically targets these disease agents. However, in the absence of stimuli, the immune system instead produces another type of helper T cell that initiates the production of the IgE antibody.

Demographics

In the United States, about 15 million people had asthma in 2004; approximately five million were children. Asthma affects individuals of all ages, but often starts in childhood. More than 50% of asthma cases occur in children between two and 17 years of age. Asthma is the most prevalent childhood chronic disease, and is more common in children than adults. In children, more males have asthma than females. Male children have a 30% higher prevalence of asthma compared to females. In adults, the trend is reversed, with more females having asthma than males. Adult females have a 30% higher prevalence of asthma than adult males. Within ethnic groups, non-Hispanic blacks have more asthma attacks and are more likely to be hospitalized and die from asthma than non-Hispanic whites. Asthma is distinct from, but closely linked to, allergies. Most, but not all, people with asthma have allergies.

The Centers for Disease Control (CDC) conducted a National Health Interview Survey in 2002 regarding asthma. At the time of the survey, 30.8 million individuals in the United States had been diagnosed with asthma during their lifetime: 21.9 million were adults and 8.9 million were children. Among all racial and ethnic groups, Puerto Ricans had the highest rate of lifetime asthma. Puerto Ricans were approximately 80% more likely than non-Hispanic whites to have been diagnosed with asthma.

Asthma attack prevalence is a crude indicator of how many individuals have uncontrolled asthma and are at risk for hospitalization. In 2002, 12 million people had experienced an asthma attack within the past year. Asthma attack prevalence decreased with age, being most prevalent in children. Puerto Ricans had the highest asthma attack prevalence, a full 100% higher than non-Hispanic whites. The prevalence of an asthma attack was about 30% higher in non-Hispanic blacks than in non-Hispanic whites. In this survey, Non-Hispanic blacks were the most likely to die from asthma, with an asthma death rate more than 200% higher than non-Hispanic whites. Females had an asthma death rate approximately 40% higher than males. Differences in male and female hormones may cause this disparity.

Asthma has been described as the fastest-growing chronic disease and a worldwide epidemic. According to Global Initiative for Asthma (GINA), an asthma research and education program, asthma accounts for about one in every 250 deaths worldwide. Many of the deaths are believed to be preventable and are caused by poor medical care. GINA estimates there are over three million asthmatic individuals worldwide. In most countries, asthmatic cases are increasing 20–50% every decade. The United States is one of the top countries for prevalence of asthma, along with England, Australia, parts of South America, and Canada. In Australia, the incidence of asthma is very high in Caucasian children, but much lower in aboriginal children.

It is speculated that lifestyle factors, such as a lack of physical activity, increased obesity, and more time spent indoors, may contribute to higher rates of asthma in highly developed countries. It is also possible that environmental irritants, such as poor indoor and outdoor air quality, along with the presence of potent irritants such as cockroach allergens, may contribute to higher rates of childhood asthma in poorer communities. Other factors that may prompt the onset of asthma are viral respiratory infections, low birth weight, and smaller-than-average air passageways in asthmatic patients.

Another area of research concerns the connection between common childhood infections and asthma. Many studies have shown that children who are exposed to viruses that cause the common cold and other respiratory infections at a very young age are less likely to develop asthma than peers living in a more hygienic environment. Children living at home with older siblings and those who spend time in daycare centers may be less likely to develop asthma than children who do not interact with others of their own age group. A related factor could be the overuse of antibiotics. Frequent use of antibiotic medications to treat relatively minor infections may produce changes in a person's immune system that increase the chance of developing asthma later in life.

Signs and symptoms

Asthmatics may experience coughing that is often worse at night or early in the morning, making sleep difficult. Wheezing is a common symptom, creating a whistling or squeaky sound when breathing. Asthmatics experience tightness in the chest region, as if it is being compressed. Shortness of breath and the feeling of breathlessness are common symptoms. There is difficulty getting enough air in or out of the lungs, especially during exhalation. If airflow to the lungs is inadequate, a lack of sufficient oxygen to the tissues causes the body to breathe faster, in an attempt to get more oxygen. Asthmatics often breathe faster as a result.

Asthmatics often have wheezing during a cold, flu, or other illness. Emotional stress may also result in asthmatic symptoms, such as coughing or wheezing from prolonged crying or laughing. Many indoor and outdoor factors can trigger or initiate typical symptoms of asthma, including allergies, viral respiratory infections, weather changes, and exercise. Medications containing aspirin also act as an asthma trigger in about 10–20% of adult asthmatics.

When allergies stimulate an asthma attack, it is known as allergic asthma. Allergic asthma is stimulated when an affected individual is physically near an allergen or irritant. Research has confirmed that allergies cause the majority of childhood asthma cases. Allergic asthma is the most common form of asthma and tends to run in families. Common allergens that may contribute to allergies and asthmatic reactions include dust mites, dust particles, animal dander, animal hair or bird feathers, mold, plant pollen, and substances found in food. Food products containing peanuts, eggs, dairy products, or seafood can cause asthma attacks in some children with allergies to these foods. Food additives, such as sulfites, can also act as asthma triggers. Synthetic (manmade) products like the latex material used in surgical gloves can also trigger asthma episodes in susceptible individuals. Non-allergic factors that can stimulate or aggravate asthma symptoms include tobacco smoke, chalk dust, talcum powder, car exhaust, and fumes from chemicals such as household cleaners. Auto pollution is a major factor in asthma prevalence.

Exercise is a common trigger for asthma in about 80% of asthmatic individuals. Some asthmatics have exercise-induced symptoms precipitated by brisk activity such as running, especially during cold weather. Pretreatment medications, such as short-acting bronchodilators, quickly widen air passages and thus help prevent the onset of asthma while an asthmatic participates in physical activities. Activities that allow for frequent breaks rather than prolonged endurance are most suitable. Asthma does not have to be a barrier to participating in athletic activities. Many Olympic athletes have exercise-induced asthma that is controlled by medication.

Changes in the weather, such as temperature and humidity variations, can also negatively affect asthma patients. Cold climates may exacerbate asthma because the lungs have to work harder to warm and moisten inhaled air. Asthmatics exercising in such conditions could wear a surgical mask that can trap the warm, moist air exhaled with each breath. Viral infections of the respiratory system that tend to increase in number during winter months may trigger severe asthma attacks. Additionally, unclean and poorly maintained forced-air heating systems release many pollutants that further aggravate asthmatic symptoms.

Every asthma patient is unique. Because there are so many environmental conditions that affect individuals with a genetic predisposition for asthma, it is often difficult to pinpoint the primary cause of the disease in individual cases.

An asthmatic may have any combination of symptoms, with symptoms varying from one asthma attack to another. Symptoms may exhibit a range of severity, from mildly irritating to life-threatening. Symptoms occur with varying frequency from once every few months to every day. Asthma classifications are based on symptom levels in the absence of medication. Mild intermittent asthma is defined as symptoms of wheezing, coughing, or breathing difficulty less than twice a week or less, with night symptoms twice a month or less. Mild persistent asthma is defined as symptoms of wheezing, coughing, or breathing difficulty once a day or less, but more than twice a week. Symptoms occur at night more than twice a month. Moderate persistent asthma is defined as daily symptoms that require daily medication. Symptoms at night occur more than once a week. Symptoms may be severe enough to interfere with normal physical activity. Severe asthma is described as ongoing, persistent symptoms with more serious asthma attacks. Symptoms may occur throughout the day, with night symptoms occurring often. In severe asthma, physical activity is likely to be limited.

All types of asthmatics may have severe asthma attacks. However, with appropriate treatment and avoidance of asthma stimulators, most asthmatics can achieve a general condition of minimal or no symptoms. Asthmatics are encouraged to learn to recognize their own specific asthma stimulators and avoid them, and to recognize their specific pattern of early warning signs that signal the start of an attack. The first signs of a mild or moderate attack may be a slight tightening of the chest, coughing or wheezing, and spitting up mucous. Severe attacks can bring on a feeling of extreme tightening of the neck and chest, making breathing increasingly difficult. Asthmatics may struggle to speak or breathe. In advanced stages of severe attacks, lips and fingernails may take on a grayish or bluish tinge, indicating declining oxygen levels in the blood. Such attacks can be fatal in the absence of prompt medical attention. Fortunately, asthma symptoms are usually reversible with medication.

Diagnosis

The first stage of asthma diagnosis is from a history of asthmatic symptoms. These symptoms include periods of coughing, wheezing, shortness of breath, or chest tightness that come on suddenly in response to specific stimulants or time periods. A history of head colds that evolve into chest congestion or take more than 10 days to recover from is pertinent. Family history of asthma or allergies may also be part of the diagnosis.

A physical exam may reveal wheezing in the chest that can be heard with a stethoscope. A device called a spirometer may be used to check the function of the airways in children over five years of age and in adults. The test measures the volume of air and the speed with which air can be blown out of the lungs after a deep breath. If the airways are narrowed from inflammation and the muscles around the airways tightening up from asthma, the results will be lower than normal. If spirometry results are normal but asthma symptoms are present, other tests are performed. A bronchial challenge test involves inhalation of a substance such as methacholine, which causes narrowing of the airways in asthma. The effect is measured by spirometry to determine is asthma is present. Children under five years of age usually cannot use a spirometer successfully. In such cases, asthma medications are often attempted as part of the diagnosis to determine if they are able to alleviate the symptoms.

Allergy testing may be performed to determine if there are specific allergens that the individual is reactive to. A device called a peak flow meter may be used every day for several weeks to measure breathing efficiency. Tests may be performed to determine the reaction of the airways to exercise. In some cases, a chest x ray or an electrocardiogram may be used to determine if a foreign object, other lung disease, or heart disease could be causing asthma-like symptoms. The results of the medical history, physical exam, and lung function tests are used to diagnose the severity of asthma and determine treatment.

Treatment and management

Asthma is treated by avoiding stimulating factors and by medication. There are two main types of asthma medication. Acute medications give rapid, short-term treatment, and are only used when asthma symptoms require immediate relief. Acute medications are bronchodilators that may be inhaled and take effect within minutes to dilate the airways and allow normal breathing. Bronchodilators may be used at the beginning of an asthma attack to provide relief. Bronchodilators may also be used before exercise to prevent exercise-induced asthma symptoms. Long-term control medications are taken daily over long periods of time to control chronic symptoms and prevent asthma attacks. The full effect of these medications requires several weeks of use. Individuals with persistent asthma require long-term control medications.

The most effective, long-term control medication for asthma is an inhaled corticosteroid. Corticosteroids reduce the swelling of airways and help to prevent asthma attacks from occurring. Inhaled corticosteroids are preferred for treatment of all levels of persistent asthma. In some cases, steroid tablets or liquid medications are used temporarily to control asthma. Other types of asthma medications inhibit the inflammatory mediators released in the asthma response. Some of these long-term control medications may be used in combination with inhaled corticosteroids to treat moderate persistent and severe persistent asthma. Long-term control medications are used in a preventative manner and will not stop a currently occurring asthma attack. Many asthmatics require both a short-acting bronchodilator to use when symptoms worsen and a long-term daily asthma control medication to treat ongoing inflammation.

Uncontrolled asthma during pregnancy can be very dangerous. Lowered oxygen levels to the fetus may cause damage. Many asthma treatments are considered safe to use during pregnancy. Older adults may need adjustments in asthma treatment because of other present diseases or conditions. Some medications, such as beta-blockers used for hypertension, aspirin, and nonsteroidal anti-inflammatory drugs such as ibuprofen, can interfere with some asthma medications or cause asthma attacks. The use of corticosteroids may also adversely affect bone density in adults.

Asthmatics can monitor the function of their respiratory system with the aid of peak flow meters and spiro-meters. These devices measure the amount of air exhaled with each breath. They are used to regularly monitor the severity of asthma symptoms and to evaluate and manage treatment procedures for individual patients. Maintaining control over asthma symptoms, combined with a healthy lifestyle, are key components of asthma treatment.

Emergency care may become necessary during a severe asthma attack. Emergency care takes place in a hospital setting and may include treatment with high levels of bronchodilators and corticosteroids, additional medications, and oxygen administration in an attempt to restore normal respiratory activity. Delayed access to emergency treatment can lead to complete respiratory failure where the patient simply stops breathing and cannot be revived.

In cases of allergic asthma, allergy shots may also assist in reducing symptoms. Allergy shots, also known as allergen immunotherapy, are recommended for individuals who suffer from allergic asthma when it is not possible to avoid contact with the allergens that stimulate asthma. A series of shots with controlled and gradually increasing amounts of allergen may be given over a number of months or years. The shots are vaccines containing various allergens, such as pollen or dust mites. The increased exposure to the allergen desensitizes the immune system to allergen triggers. Allergy shots can diminish the severity of asthma symptoms and lower the dosage of required asthma medications.

Prognosis

There is currently no cure for asthma. Proper treatment and management has dramatically improved the quality of life for individuals with asthma. When medication is utilized properly, the prognosis for most asthmatics is excellent. An improvement in environmental conditions can reduce the number and severity of asthma attacks and improve the prognosis for asthmatics. Such improvement is also believed to affect the overall prognosis for a society, simply by decreasing the number of individuals sensitized to environmental triggers.

Resources

BOOKS

Katzung, B. G. Basic and Clinical Pharmacology, Seventh Edition. Stamford, CT: Appleton and Lange, 1998.

Roitt, I., J. Brostoff, and D. Male. Immunology, Fifth Edition. London, England: Mosby International, 1998.

PERIODICALS

"Clearing the Air: Asthma and Indoor Air Exposures." The New England Journal of Medicine 343 (December 14, 2000): 24.

"Day Care, Siblings, and Asthma—Please, Sneeze on My Child." The New England Journal of Medicine 343 (August 24, 2000): 8.

Folkerts, Gert, Gerhard Walzl, and Peter J. M. Openshaw. "Do Common Childhood Infections 'Teach' the Immune System Not to Be Allergic?" Immunology Today 21, no. 3 (2000): 118–120.

Herz, Udo, Paige Lacy, Harald Renz, and Klaus Erb. "The Influence of Infections on the Development and Severity of Allergic Disorders." Current Opinion in Immunology 12, no. 6 (2000): 632–640.

Illi, S., E. von Mutius, S. Lau, R. Bergmann, B. Niggemann, C. Sommerfeld, and U. Wahn. "Early Childhood Infectious Diseases and the Development of Asthma Up to School Age: A Birth Cohort Study." British Medical Journal 322 (February 17, 2001): 390–395.

Johnston, Sebastian L., and Peter J. M. Openshaw. "The Protective Effect of Childhood Infections—The Next Challenge Is to Mimic Safely This Protection Against Allergy and Asthma." British Medical Journal 322 (February 17, 2001): 376–377.

"Siblings, Day-Care Attendance, and the Risk of Asthma and Wheezing." The New England Journal of Medicine 343, no. 26 (December 28, 2000).

ORGANIZATIONS

Allergy and Asthma Network. Mothers of Asthmatics, Inc. 2751 Prosperity Ave., Suite 150, Fairfax, VA 22031. (800) 878-4403. Fax: (703) 573-7794.

American Academy of Allergy, Asthma & Immunology. 611 E. Wells St., Milwaukee, WI 53202. (414) 272-6071. Fax: (414) 272-6070. (April 18, 2005.) <http://www.aaaai.org/default.stm>.

American Lung Association. 1740 Broadway, New York, NY 10019. (212) 315-8700 or (800) 586-4872. (April 18, 2005.) <http://www.lungusa.org>.

Asthma and Allergy Foundation of America (AAFA). 1233 20th St. NW, Suite 402, Washington, DC 20036. (800) 7-ASTHMA. Fax: (202) 466-8940. (April 18, 2005.) <http://www.aafa.org>.

Division of Lung Diseases, National Heart, Lung and Blood Institute. Suite 10122, 6701 Rockledge Dr. MSC 7952, Bethesda, MD 20892-7952. (301) 435-0233. (April 18, 2005.) <http://www.nhlbi.nih.gov/index.htm>.

Global Initiative for Asthma (GINA). (207) 594-5008. Fax: (207) 594-8802. [email protected] (April 18, 2005.) <http://www.ginasthma.com>.

KidsHealth. Nemours Center for Children's Health Media. PO Box 269, Wilmington, DE 19899. (April 18, 2005.) <http://www.kidshealth.org>.

National Asthma Education and Prevention Program (NAEPP). School Asthma Education Subcommittee. (April 18, 2005.) <http://www.nhlbi.nih.gov/health/dci/Diseases/Asthma/Asthma_WhatIs.html>.

National Center for Environmental Health. Centers for Disease Control and Prevention, Mail Stop F-29, 4770 Buford Highway NE, Atlanta, GA 30341-3724. (April 18, 2005.) <http://www.cdc.gov/asthma/>.

National Institutes of Health (NIH). PO Box 5801, Bethesda, MD 20824. (800) 352-9424. (April 18, 2005.) <http://www.ninds.nih.gov>.

OTHER

Asthma. National Heart, Lung, and Blood Institute. (April 18, 2005.) <http://www.nhlbi.nih.gov/health/public/lung/index.htm>.

Asthma and Allergies. Centers for Disease Control and Prevention. (April 18, 2005.) <http://www.cdc.gov/niosh/topics/asthma>.

Asthma Basics. National Institutes of Health. (April 18, 2005.) <http://www2.niaid.nih.gov/newsroom/focuson/asthma01/basics.htm>.

Asthma Prevalence, Health Care Use and Mortality, 2002. National Center for Health Statistics. (April 18, 2005.) <http://www.cdc.gov/nchs/products/pubs/pubd/hestats/asthma/asthma.htm>.

Breath of Life Exhibition. National Library of Medicine. (April 18, 2005.) <http://www.nlm.nih.gov/hmd/breath/breath_exhibit/mainframe.html>.

"What Makes Asthma Worse?" medfacts 2000. Lung Line, National Jewish Medical and Research Center, 1400 Jackson Street, Denver, CO 80206. (303) 388-4461 (7700). (April 18, 2005.) <http://www.nationaljewish.org/medfacts/worse.html>.

Maria Basile, PhD

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