asthma

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is pronounced ass-mǝ in British English, and az-mǝ in American English. The -th- is not normally pronounced in either variety.

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For more information on asthma, visit Britannica.com.

An allergic inflammatory disease of the airways, involving mast cells, eosinophils, macrophages, fibroblasts, and neutrophils. Such inflammatory changes are associated with widespread airflow obstruction, which is variable and improves (reverses) spontaneously or with appropriate therapy. Inflammation progresses to increased airway irritability (hyperresponsiveness) induced by the inhalation of allergens, cold air, and occupational factors. Although bronchospasm can be induced immediately after exposure to a specific allergen in an appropriately sensitized recipient, it is the late allergic response that most resembles the inflammatory reaction occurring in asthma. Central to this reaction is the release from mast cells, eosinophils, and lymphocytes of chemical mediators such as histamine, leukotrienes (potent bronchoconstricting agents), and various cytokines which perpetuate the response. Potent neurohumoral agents derived from neural pathways contribute further to the bronchospasm. See also Cytokinins; Hypersensitivity.

Wheezing, nocturnal breathlessness, coughing, and chest tightness often relieved by expectoration are highly suggestive of asthma. Episodes of breathlessness which result from exposure to an irritant (such as cold air) or an allergen (such as dust mites) following exercise or a viral infection and which are reversed spontaneously or with therapy are diagnostic of asthma. Eczema and edema in the folds of the nasal chambers are suggestive of a hereditary allergy, the major predictor of asthma. Objective measures of airflow obstruction which improved spontaneously or with therapy are also central to establishing an asthma diagnosis. Atopy, the genetic predisposition for developing an immunoglobulin-E (IgE) mediated (allergic) response to inhaled environmental allergens, is the strongest predisposing factor for developing asthma. Asthma may be classified, therefore, according to severity, etiology, or pattern of airflow obstruction. It is helpful to differentiate those factors that induce inflammation from those that incite acute bronchospasm in susceptible individuals. The association of an elevated serum IgE and the occurrence of asthma in all age groups, including those who are not atopic, makes antigenic stimulation causal in all instances of asthma. The severity of asthma can best be defined in terms of peak-flow monitoring (monitoring the severity of the allergy). Such evaluations as mild, moderate, and severe are useful in applying therapy in a stepwise manner contingent on severity. See also Immunoglobulin.

Successful management of asthma requires education of the sick individual coupled with the development of a partnership with an asthma management health-care team; assessing and monitoring the severity of asthma, with utilization of objective parameters of assessment (for example, the peak-flow meter, a device that measures the amount of air that enters and leaves the lungs); environmental management to avoid asthma triggers; and establishment of a drug regimen that controls asthma (medications include bronchodilators, which act as relievers, and bronchodilators, which act as preventers), as well as a written plan to prevent the condition from becoming worse. Adequate management of asthma should control the symptoms, prevent asthma attacks, return and maintain pulmonary function as close to normal as possible, maintain normal activity levels including exercise, avoid adverse side effects from the drugs, reduce and prevent irreversible airway changes, and prevent mortality. See also Allergy; Respiratory system disorders.

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A respiratory disorder characterized by recurrent attacks of difficulty in breathing (described in medical books as ‘episodic wheezing’), particularly on exhalation. It is caused by an increased resistance to air flow through the respiratory bronchioles (small air tubes leading to the lungs). Sufferers are hypersensitive to a variety of stimuli (e.g. house dust mites; diesel exhaust particulates; and vehicle exhaust gases, such as ozone and nitrogen oxides) which cause the airways to narrow. Asthma may be induced by exercise (see exercise induced asthma) and food allergies. Sports vary in their tendency to induce asthma, with running having a high tendency, cycling a moderate tendency, and gymnastics and swimming a low tendency. Paradoxically, many asthmatics gain relief from bronchospasms by regular exercise, and exercise is now seen as important in the management of asthma. Asthmatic attacks are relieved by a number of drugs, but competitive sports people should be aware that some of these are banned by sports federations because, as well as controlling asthma, they may act as artificial stimulants.

A condition marked by widespread narrowing of the bronchial airways, which changes in severity over short periods of time (either spontaneously or under treatment) and leads to cough, wheezing, and difficulty in breathing. Bronchial asthma may be precipitated by exposure to one or more of a wide range of stimuli, including allergens, drugs (such as aspirin and other non-steroidal anti-inflammatory drugs), exertion, emotion, infections, and air pollution.

Treatment of asthma is with sympathomimetic drugs that stimulate beta receptors, such as salbutamol, salmeterol, or terbutaline (see bronchodilators), with or without corticosteroids (such as beclometasone dipropionate and budesonide); all these drugs are usually administered via aerosol or dry-powder inhalers, or – if the condition is more severe – via a nebulizer. Other drugs that can be used for the prevention of asthmatic attacks include sodium cromoglicate or nedocromil, theophylline, the antimuscarinic drug ipratropium bromide, and the leukotriene receptor antagonists. Oral corticosteroids are reserved for those patients who fail to respond adequately to these measures. Severe asthmatic attacks may need large doses of oral corticosteroids (such as prednisolone).

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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 10–12 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, and—despite modern drug treatments—it 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 activities—including exercise and those requiring exertion—and 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 control—not relief—of 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.

• 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.

[Article by: David A. Cramer, M.D. Angela M. Costello]

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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.

(SEE ALSO: Chronic Respiratory Diseases; Emphysema; Pulmonary Function)

Bibliography "Drugs for Asthma." The Medical Letter on Drugs and Therapeutics 41(2000):19–24.

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 127:142–147.

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.

— JOHN L. STAUFFER

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A respiratory disorder characterized by recurrent attacks of difficult breathing, particularly on exhalation, due to an increased resistance to airflow through the respiratory bronchioles. Asthmatics are usually hypersensitive to a variety of stimuli, which cause the airways to narrow by contraction of their smooth muscle, by a swelling of the mucous membrane, or due to an increased mucus secretion. All asthmatics wheeze upon exercise, but some seem to be particularly sensitive to exercise (see exercise-induced asthma). Sports vary in their tendency to induce asthma with running having a high tendency, cycling a moderate tendency, and gymnastics and swimming a low tendency. Paradoxically, many asthmatics gain relief from their bronchospasms by regular exercise, and exercise is now regarded as important in the management of asthma. Many drugs help to control asthma, but some are on the World Anti-Doping Agency's 2005 Prohibited List, e.g. those containing stimulants such as ephedrine. Several athletes have been disqualified from the Olympic Games because of pre-race administration of an oral anti-asthmatic drug. All beta₂ agonists (the group of drugs commonly used to treat asthma) are prohibited, except formoterol, salbutamol (less than 1000 ng/mL), salmeterol, and terbutaline, which are permitted by inhalation only when a Therapeutic Use Exemption has been granted.

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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 mother—biological and psycho-affective—as 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.

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.

—ROBERT ASSÉO

(az-muh)

A chronic disease of the respiratory system, characterized by sudden, recurring attacks of difficult breathing, wheezing, and coughing. During an attack, the bronchial tubes go into spasms, becoming narrower and less able to move air into the lungs. Various substances to which the sufferer has an allergy, such as animal hair, dust, pollen, or certain foods, can trigger an attack.

IN BRIEF: n. - A person suffering from labored breathing either continuous or paroxysmal accompanied by wheezing, a sense of constriction in the chest, and often by attacks of coughing adj. - Relating to breathing with a whistling sound.

In his case it is that he is a chronic asthmatic. — yourdictionary.com

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sign description: Combination Sign: BREATH + LUNGS

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a common chronic and debilitating illness in which swollen and inflamed airways are produced by IgE-mediated allergic reactions to airborne allergens (most commonly from cockroaches, house-dust mites, or pets) or induced by exercise or cold. Two genes that seem to be involved are those for elevated IgE levels (locus at 5q31 — q33) and for ADAM-33 (locus at 20p).
—asthmatic adj., n.; —asthmatically adv.

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A condition marked by recurrent attacks of dyspnea, with wheezing due to spasmodic constriction of the bronchi.
It is also known as bronchial asthma. Attacks vary greatly from occasional periods of wheezing and slight dyspnea to severe attacks that almost cause suffocation.

• acute equine a. — sudden attacks of respiratory distress in horses at pasture; the dyspnea responds dramatically to treatment with corticosteroids combined with antihistamines.
• allergic a. — extrinsic asthma; bronchial asthma due to allergy. Called also atopic asthma.
• atopic a. — see allergic asthma (above).
• bronchial a. — asthma.
• cardiac a. — a term applied to breathing difficulties due to pulmonary edema in heart disease, such as left ventricular failure.
• feline a. — see feline bronchial asthma.

(az′mə)
n

Paroxysmal wheezing and difficulty in breathing resulting from bronchospasms. Frequently has an allergic basis and occasionally an emotional origin. See also status asthmaticus.

For a list of words related to asthmatic, see:

• Weak, Fearful, or Anxious

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See words rhyming with "asthmatic."

This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)

Dansk (Danish)
n. - astma

Nederlands (Dutch)
astma

Français (French)
n. - asthme

Deutsch (German)
n. - Asthma

Ελληνική (Greek)
n. - (παθολ.) άσθμα

Italiano (Italian)
asma

Português (Portuguese)
n. - asma (f) (Med.)

Русский (Russian)
астма

Español (Spanish)
n. - asma

Svenska (Swedish)
n. - astma

中文（简体）(Chinese (Simplified))
哮喘, 气喘

中文（繁體）(Chinese (Traditional))
n. - 哮喘, 氣喘

한국어 (Korean)
n. - 천식

日本語 (Japanese)
n. - 喘息

العربيه (Arabic)
‏(الاسم) الأزمه : دا الربو‏

עברית (Hebrew)
n. - ‮קצרת, גנחת, אסתמה‬

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