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•	In-Depth Reports Home

In This Report

•	Highlights
•	Introduction
•	Causes
•	Prognosis
•	Risk Factors
•	Symptoms
•	Diagnosis
•	Treatment
•	Quick-Relief Medications...
•	Long-Term Relief Medication...
•	Other Treatments
•	Managing Asthma
•	Resources
•	References

Related Reports

•	Asthma in adults
•	Sinusitis
•	Allergic rhinitis
•	Ear infections

Encyclopedia

•	Pediatric asthma
•	Asthma
•	Lung plethysmography

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Asthma in children and adolescents

Highlights

Drug Warning

In 2007, the FDA requested the manufacturers of omalizumab (Xolair) to include a “boxed warning” emphasizing that this drug may cause a severe and life-threatening allergic reaction (anaphylaxis). Health care providers need to carefully observe patients for 2 hours after they receive an omalizumab injection. However, because an allergic reaction can occur up to 24 hours after the injection, patients need to know the signs and symptoms of anaphylaxis and how to self-administer emergency treatment. Omalizumab is approved for patients ages 12 and older who have moderate-to-severe asthma related to allergies.

Drug Approval

In 2006, budesonide/formoterol (Symbicort) was approved for patients age 12 years and older. Symbicort combines a corticosteroid and a long-acting beta2-agonist into a single inhaler.

Inhaled Corticosteroids

• Inhaled corticosteroids may help reduce wheezing in young children with breathing problems, but they do not help prevent the development of asthma, according to several 2006 studies in the New England Journal of Medicine.
• Inhaled corticosteroids work better than a corticosteroid/long-acting beta2-agonist combination or a leukotrine receptor antagonist drug in treating children with mild-to-moderate asthma, suggests a 2007 study in the Journal of Allergy and Clinical Immunology.

Long-Acting Beta2-Agonists

• Long-acting beta2-agonist drugs such as salmeterol (Serevent Diskus) and formoterol (Foradil Aerolizer) may worsen asthma symptom severity and increase the risk for asthma-related death, indicates a 2006 review in the Annals of Internal Medicine.
• Products that contain salmeterol and formoterol now have strengthened warning labels detailing these risks.

Childhood Asthma Statistics

Asthma death rates among children have largely declined since 1999 while doctors’ office visits for asthma treatment have more than doubled, indicates a recent report from the U.S. Centers for Disease Control and Prevention.

Introduction

The word asthma originates from an ancient Greek word meaning panting. Essentially, asthma is an inability to breathe properly. When any person inhales, the air travels through the following structures:

• Air passes into the lungs and flows through progressively smaller airways called bronchioles. The lungs contain millions of these airways.
• All bronchioles lead to alveoli, which are microscopic sacs where oxygen and carbon dioxide are exchanged.

The major features of the lungs include the bronchi, the bronchioles, and the alveoli. The alveoli are the microscopic blood vessel-lined sacks in which oxygen and carbon dioxide gas are exchanged.

Asthma is a chronic condition in which these airways undergo changes when stimulated by allergens or other environmental triggers. Such changes appear to be two specific responses:

• The hyperreactive response (also called hyperresponsiveness)
• The inflammatory response

These actions in the airway cause patients to cough, wheeze, and experience shortness of breath (dyspnea), the classic symptoms of asthma.

Hyperreactive Response

In the hyperreactive response, smooth muscles in the airways constrict and narrow excessively in response to inhaled allergens or other irritants. Airways in everyone's lungs respond by constricting when exposed to allergens or irritants but there are major differences  in the hyperreactive response that occurs in people with asthma:

• When people without asthma breathe in and out deeply, the airways relax and open in order to rid the lungs of the irritant.
• When people with asthma try to take those same deep breaths, their airways do not relax but instead narrow, causing the patients to pant for breath. Smooth muscles in the airways of people with asthma may have a defect, perhaps a deficiency in a critical chemical that prevents the muscles from relaxing.

Inflammatory Response

The hyperreactive stage is followed by the inflammatory response, which generally contributes to asthma in the following way:

• The immune system responds to allergens or other environmental triggers by delivering white blood cells and other immune factors to the airways.
• These so-called inflammatory factors cause the airways to swell, fill with fluid, and produce a thick sticky mucus.

Click the icon to see an image of a normal versus asthmatic bronchiole.

• This combination of events results in wheezing, breathlessness, inability to exhale properly, and a phlegm-producing cough.

Causes

Asthma occurs in about 5 million American children. Each year about 200,000 of them are hospitalized. It is the most common chronic childhood illness. About half of all cases of asthma develop before the age of 10, and about 80% of patients develop symptoms before they are 5 years old.

General Causes of Asthma

The mechanisms that cause asthma are complex and vary among population groups and even individuals. For example, asthma in children is highly associated with allergies. However, only a minority of children with allergies have asthma, and allergic response cannot explain all cases of asthma. Other factors, such as genetics or environmental conditions are probably involved in the development of asthma. Most likely, several genes combine to make a child susceptible to environmental triggers, not only allergens but also possibly infections, dietary patterns, or air pollution. Physical factors, particularly having smaller lungs, affect the chances for later asthma.

The Allergic Response

Asthma and allergies often coexist, and the allergic response plays a strong role in childhood asthma. About 70 - 85% of children with asthma also have allergies. Some studies suggest that children who have allergies are also at greater risk for developing asthma as adults. A 2006 study found that children who are allergic to dust mites are three times more likely to later develop asthma than children who were not allergic.

However, the evidence is clearly mixed. Several other 2006 studies suggested that avoiding dust mites does not help prevent asthma and, in fact, early exposure to dust mites may even protect children from developing asthma and allergic responses. Some experts think that giving immunotherapy (“allergy shots”) to children with allergies may help prevent asthma development.

An asthma attack can be induced or aggravated by direct irritants to the lungs. Studies indicate that the more indoor allergens a child is allergic to, the higher the risk for severe asthma. Important irritants or allergens include the following:

• Dust mites, specifically mite feces, which are coated with enzymes that contain a powerful allergen. These are the primary allergens in the home.
• Animal dander. Cats harbor significant allergens, which can even be carried on clothing; dogs usually present fewer problems.
• Molds.
• Cockroaches. Cockroaches are major asthma triggers and may reduce lung function even in people without a history of asthma.
• Pollen. An asthma attack from an allergic response to pollen is more likely to occur during extreme air changes, such as thunderstorms. Major weather changes, such as El Nino, can affect the timing of allergy seasons because they cause seasonal changes (and pollen) to start earlier.
• Food allergies. About 8 - 10% of children with asthma also have food allergies. These children also appear to have a high risk for very serious reactions to such foods. In infants and toddlers, allergy to eggs appears to be a predictor of asthma.
• Fossil Fuels. Certain chemicals may trigger allergic rhinitis. Some experts believe that refined fossil fuels, such as diesel fuel and particularly kerosene, may be important triggers for allergic rhinitis. In people who already have allergies or asthma, exposure to such fossil fuels may worsen symptoms.

The Allergic Response. The allergic process, called atopy, and its connection to asthma are not completely understood. It involves various airborne allergens or other triggers that set off a cascade of events in the immune system leading to inflammation and hyperreactivity in the airways. One description is as follows:

• The conductor in an orchestra of immune factors that contribute to allergies and asthma appears to be a category of white blood cells known as helper T cells, in particular a subgroup called Th2 cells.
• Th2 cells overproduce interleukins (ILs), immune factors that are molecular members of a family called cytokines, which are involved in the inflammatory process.
• Interleukins 4, 9, and 13, for example, may be responsible for a first-phase asthma attack. These interleukins stimulate the production and release of antibody groups known as immunoglobulin E (IgE). (People with both asthma and allergies appear to have a genetic predisposition for overproducing IgE.)
• During an allergic attack, these IgE antibodies can bind to special cells in the immune system called mast cells, which are generally concentrated in the lungs, skin, and mucous membranes. This bond triggers the release of a number of active chemicals, importantly potent molecules known as leukotrienes. These chemicals cause airway spasms, overproduce mucus, and activate nerve endings in the airway lining.
• Another cytokine, interleukin 5, appears to contribute to a late-phase inflammatory response. This interleukin attracts white blood cells known as eosinophils. These cells accumulate and remain in the airways after the first attack. They persist for weeks and mediate the release of other damaging particles that remain in the airways.

The Immune Response

Researchers are investigating the role that T cells play in asthma. T cells are white blood cells that are involved in the immune response. Researchers had focused on the T cell called type 2 helper (ThH2) cells. However, a 2006 breakthrough study in the New England Journal of Medicine suggested that a different type of T cell may play a stronger role in asthma than previously thought.

Researchers discovered that these cells, called natural killer T cells, are far more common in the lungs of people with asthma than in the lungs of healthy people. Natural killer T cells are very rare, but researchers found them in 60% of people with moderate-to-severe persistent asthma. While this research is preliminary, it may explain why corticosteroid drugs do not work well for some patients with asthma: Steroid drugs target Th2 and other inflammatory cells, not natural killer T cells. Researchers think that further investigation of natural killer T cells may lead the way to new types of asthma drugs. If these cells prove to be involved in asthma, then drugs that eliminate them might become an important new treatment.

Remodeling and Causes of Persistent Asthma

Over the course of years the repetition of the inflammatory events involved in asthma can cause irreversible structural and functional changes in the airways, a process called remodeling. The remodeled airways are persistently narrow and can cause chronic asthma. Researchers are trying to determine how this process occurs:

Interleukins. Some researchers are looking at potent immune factors, including interleukins 11 and 13. They have been linked to a number of processes possibly involved in remodeling, including scarring in the airways and overgrowth of cells in the smooth muscles that line the airways.

Growth Factors. Compounds known as vascular endothelial growth factor (VEGF) have been observed in the airways of patients with asthma. VEGF is a powerful promoter of cell growth in blood vessel linings and some researchers believe it may be major factor in remodeling.

Genetic Factors

About one-third of all persons with asthma share this condition with another member of their immediate family. Asthma may be more likely to be passed to children from the mother than from the father. Both allergies and asthma are strongly associated with hereditary factors, sharing certain genetic markers, but they are not always inherited together.

Research on the genetics of these conditions is confusing. Of some significant promise, researchers have identified a gene (ADAM33), which has been linked to asthma. The gene regulates one of the enzymes called metalloproteases, which are involved with the smooth muscle in the airway. A mutation of this gene could play a role in airway changes that occur after inflammation.

The Complex Role of Early Infections

The role of early childhood respiratory and intestinal infections is very complex. Viral respiratory infections certainly worsen existing asthma, but the most common ones are unlikely to be causes of childhood asthma. In fact, early respiratory and intestinal infections may offer some protection against asthma.

Early Respiratory Infections as Causes of Asthma. Studies suggest that most respiratory infections are not important causes of asthma in children, except in certain cases. An important exception is the respiratory syncytial virus (RSV), which has been implicated in the development of asthma. RSV is the major viral cause of infant pneumonia. Studies also indicate that infants who have reduced lung function within a few days after birth are at increased risk of developing asthma by the time they are 10 years old.

Common Respiratory Infections Worsen Asthma. Common respiratory infections viruses that cause colds (such as the rhinovirus) may in some cases be associated with the development of asthma. A 2007 study suggested that children who have a wheezing rhinovirus during infancy are at increased risk for developing asthma by age 6. Even if these viruses do not directly cause asthma, they can worsen asthma in children who already have it. Rhinovirus has been reported to be the most common infection associated with asthma attacks. In one study, it was associated with 61% of asthma worsening in children. Some research suggests that colds promote inflammation in patients with existing asthma and increase the intensity of airway responsiveness for weeks.

The Hygiene Theory: Early Infections as Protection Against Asthma. Another blames the dramatic increase in asthma on the reductions in childhood infections that have occurred with modern hygiene and antibiotic use. The basic theory rests on the idea that infections stimulate production of specific immune factors called Th1 cells. As these cells build up, they replace other immune factors called Th2 cells, which react to allergens -- a less serious threat to the body. Without infections to stimulate the production of the Th1 infection fighters, the Th2 allergen fighters are not replaced, and they persist at high levels, making the growing child more susceptible to allergies and asthma.

A number of different studies support this theory:

• Some studies suggest that being part of a large family or attending day care increases the risk for early respiratory infections but reduces the risk of childhood asthma. The occasional cold, then, may be protective.
• In one study, researchers measured levels of bacterial byproducts called endotoxins in the mattress dust of 812 children. Those with the highest levels had 80% lower rates in allergies and asthma.
• Another study further found a strong association between allergy development and the absence of certain beneficial bacteria (called probiotics) carried in the infant's intestines. Infants who were born in more hygienic environments tended to lack these bacteria. Antibiotic overuse and modern hygiene may be reducing these helpful organisms. (Probiotics can be obtained in active yogurt cultures and in supplements, which are being studied for protection.)

The standard vaccinations against serious childhood infections, according to several important studies, pose no risk for asthma. One of the studies even reported some lower risk for asthma and allergies in the second and third years after vaccinations. Infections killed thousands of children every year before immunization became widespread. Asthma, although serious, is rarely fatal in children. No one should stop giving their children vaccinations against childhood killers.

Other Contributing Medical Conditions

GERD. At least half of patients with asthma also have gastroesophageal reflux disease (GERD), the cause of heartburn. It is not entirely clear which condition causes the other or whether they are both due to common factors.

Heartburn is a condition where the acidic stomach contents back up into the esophagus causing pain in the chest area. This reflux usually occurs because the sphincter muscle between the esophagus and stomach is weakened. Standing or sitting after a meal can help reduce the reflux which causes heartburn. Continuous irritation of the esophagus lining as in gastroesophageal reflux disease is a risk factor for the development of adenocarcinoma.

Some theories for the causal connection between GERD and asthma are:

• Acid leaking from the lower esophagus in GERD stimulates the vagus nerve, which runs through the gastrointestinal tract. This stimulated nerve, in turn, triggers the nearby airways in the lung to constrict, causing asthma symptoms.
• Acid back-up that reaches the mouth may be inhaled into the airways (aspirated). Here, the acid triggers a reaction in the airways that cause asthma symptoms.

GERD is sometimes hard to detect and might be suspected as a contributor in the following patients:

• Those who do not respond to asthma treatments.
• Those whose asthma attacks follow episodes of heartburn.
• Those whose attacks are worse after eating or exercise.
• Those whose coughs follow episodes of acid reflux. (One study found that GERD was associated with about half of the episodes of coughs and wheezes in patients with asthma.)

Treating GERD symptoms with anti-acid drugs may resolve asthma in some (but not all) patients who share both conditions. A small 2005 observational study found that while GERD was common in patients with asthma, treatment of GERD had no effect on asthma symptoms. [See In-Depth Report #85: Heartburn and gastroesophageal reflux disease.]

Sinusitis. Almost half of children and adults with allergic asthma have sinus abnormalities, and in various studies, between 17 - 30% of patients with asthma develop true sinusitis. The presence of sinusitis, however, does not appear to increase the severity of asthma.

Click the icon to see an image of sinusitis.

Parental Migraines and Childhood Asthma. Some studies have reported a link between childhood asthma and parental migraines, with one small study suggesting that children are about five times more likely to develop asthma if their parents have a history of migraines.

Exercise-Induced Asthma

Exercise-induced asthma (EIA) is a limited form of asthma in which exercise triggers coughing, wheezing, or shortness of breath.

NSAIDs and Acetaminophen

About 10% of adults and some fewer children have aspirin-induced asthma (AIA). With this condition, asthma gets worse when patients take aspirin. Aspirin is one of the drugs known as nonsteroidal anti-inflammatory drugs (NSAIDs). Although aspirin is used to reduce inflammation in other disorders, it appears to have the opposite effect in many asthma cases. It is not wholly known why this occurs. AIA often develops after a viral infection. It is a particularly severe asthmatic condition and is associated with up to 25% of asthma-related hospitalizations. In about 5% of cases, aspirin is responsible for a syndrome that involves multiple attacks of asthma, sinusitis, and nasal congestion. Such patients also often have polyps (small benign growths) in the nasal passages.

Patients with aspirin-induced asthma (AIA) should avoid aspirin and most likely NSAIDs, including ibuprofen (Advil) and naproxen (Aleve).

Acetaminophen (Tylenol) has been the traditional alternative for relief of minor pain for patients who are aspirin-sensitive. Unfortunately, recent evidence has muddied these recommendations. Moreover, some asthmatic episodes have been linked to high consumption of acetaminophen among adults. And a study of children with asthma reported that those who took ibuprofen were less likely to be hospitalized for asthma than those taking acetaminophen. This is of particular concern, since acetaminophen is the pain reliever of choice in small children.

Nocturnal Asthma

Asthma occurs primarily at night (nocturnal asthma) in as many as 75% of patients with the condition. Attacks often occur between 2 - 4 a.m. Factors that might play role in nocturnal asthma may include one or more of the following:

• Chemical and temperature changes in the body during the night that increase inflammation and narrowing of the airways
• Delayed allergic responses from exposure to allergens during the day
• The wearing off of inhaled medications toward the early morning
• An increase in acid reflux (back up of stomach acid) that causes airways to narrow
• Postnasal drip that occurs during sleep
• Conditions relating to sleep, such as sleep apnea or sleeping on one's back, which may worsen any asthma attack that occurs at night

Some experts believe that nocturnal asthma may actually be a unique form of asthma with its own specific biologic mechanisms that occur only at night and which reduce natural steroid hormones (which block inflammation).

Exercise-Induced Asthma (EIA)

Exercise-induced asthma (EIA) is a limited form of asthma in which exercise triggers coughing, wheezing, or shortness of breath. This condition generally occurs in children and young adults, most often during intense exercise in cold dry air. Symptoms are generally most intense about 10 minutes after exercising and then gradually resolve.

EIA is triggered only by exercise and is distinct from ordinary allergic asthma in that it does not produce a long duration of airway activity, as allergic asthma does. (However, some people have both forms of asthma.) People who have only EIA do not appear to require long-term maintenance therapy. A study of military recruits with EIA also reported that the condition does not hinder a person's overall physical performance.

Medications. Cromolyn, a mild anti-inflammatory drug, or short-acting beta2-agonists have been the treatments of choice for preventing EIA. Newer approaches for people who work out regularly include pretreatment with long-acting beta2-agonists, such as salmeterol (Serevent) or the regular use of inhaled corticosteroids.

Hints for Reducing EIA. EIA occurs only after exercise and is more likely to occur with regular paced activities in cold, dry air. The following are some suggestions for reducing its impact:

• Warm-up and cool-down periods are important.
• Patients with EIA might do better with activities that involve short bursts of exercise (tennis, football) than with exercises involving long-duration regular pacing (cycling, soccer, and distance running).
• Breathing through a scarf or through the nose helps warm up the airways.
• Restricting dietary salt might help reduce EIA.

Click the icon to see an image of exercise-induced asthma.

Prognosis

Asthma is the third major cause of hospitalization in children under age 15. The condition can be very serious in children, particularly those younger than age 5, because their airways are very narrow.

Degree of Severity

The severity of asthma is graded as mild intermittent and mild, moderate, and severe persistent. A patient in any of these categories, even mild intermittent, can still experience a severe and even life-threatening attack. According to one report, 30% of asthma deaths occur in patients with mild asthma.

Risk Factors for Life-Threatening Asthma

Asthma is rarely fatal in children, with only 187 asthma deaths reported in 2002 in children under age 18. In fact, a 2006 study from the U.S. Centers for Disease Control and Prevention reported that asthma death rates for children have steadily declined since 1999. (During the same time, the number of doctor visits for asthma treatment more than doubled.) Even low mortality numbers are unacceptable, however, since asthma deaths are largely preventable.

Factors associated with an increased risk of death from asthma in children include:

• Previous life-threatening episodes of asthma
• Lack of adequate and ongoing health care. (Most likely the reason for the higher fatalities rates in minority children.)
• Significant behavioral problems
• Underestimating the severity of an acute attack poses the greatest threat. Unfortunately, one study of children found that nearly 40% of them were unaware of asthmatic symptoms when they occurred.

African American children have more than six times the death rate of Caucasians in the age groups of 4 years and younger and 15 - 24 years. Hispanic children also have a higher risk.

Symptoms of a Life-Threatening Attack

The following signs and symptoms may indicate a life-threatening situation:

• As the chest labors to bring enough air into the lungs, breathing often becomes shallow.
• Lacking sufficient oxygen, the skin becomes bluish.
• The flesh around the ribs of the chest appears to be sucked in.
• The patient may begin to lose consciousness.

Asthma often progresses very slowly to a serious condition or may develop to a fatal or near-fatal attack within a few minutes. It is very difficult to predict when an attack will become very serious. Early symptoms or lack thereof do not always reflect the ultimate severity of an attack. Some studies even suggest that people at high risk for fatal or near-fatal asthma attacks are those with poor awareness of their own reduced ability to breathe and who are slow in seeking help. Monitoring peak flow rates is, therefore, an important management component, since it provides a more accurate assessment of lung function than symptoms alone.

Long-Term Outlook

In a 2003 study, researchers followed people with asthma for longer than 30 years. About a third of children had outgrown their asthma in adulthood. In general, the more severe the childhood asthma, the greater the likelihood that it will persist. For example, only 23% of children who experienced wheezy bronchitis (wheezing during respiratory infections) suffered from frequent or persistent asthma in adulthood.

There is evidence that severe asthma can cause long-lasting damage and possibly permanent scarring in some patients. The risk for such injury is highest, however, when asthma strikes children in the first 3 - 5 years. There does not appear to be any significant risk for long-term lung damage for children who develop mild-to-moderate persistent asthma between ages 5 - 12. Children adapt well to living with asthma, and even with severe asthma they can function as well as healthy children in virtually all areas of life.

Psychologic Factors

Studies are mixed over the effects of emotional disorders on the severity of asthma. One study indicated that parents of children with asthma may suffer greater psychological stress than their children. A 2000 study reported that mild-to-moderate asthma does not significantly affect the psychological well-being of most children ages 5 - 12. Teenagers and preteens may have particular difficulty coping with what they perceive as the social stigma of asthma. Parents and older children should not hesitate to seek help from support groups, doctors, friends, or family members. Support programs may help children to better manage their asthma and even reduce hospitalization.

Effect on School and Work

Although there have been few studies on the effects of asthma on schooling, a 2000 study reported that nocturnal (nighttime) asthma affected school attendance and performance in children and work attendance in their parents.

Risk Factors

Asthma affects about 5 million American children between the ages of 5 - 14. Asthma has dramatically increased worldwide over the last few decades, in both developed and developing countries. From 1980 - 1994, asthma increased 160% in American children younger than 4 years and has also dramatically risen worldwide. Experts are puzzling over the cause of this phenomenon. Possible causes and risk factors that are suspects in the dramatic rise in asthma in children include:

• Survival rates are now higher in low-birth-weight babies, who may be more susceptible to asthma.
• Declining rates in nursing may be a contributor. Breast milk contains important anti-inflammatory substances, such as omega-3 fatty acids, which might protect against asthma.
• Western dietary habits (which commonly include more fast foods and less fruits, vegetables, fiber, minerals, and other nutrients) may contribute to the development of childhood asthma.
• Children are spending more time indoors watching television, playing video games, or using the computer and are, therefore, overexposed to indoor allergens.
• The trend of making homes more energy-efficient may result in dust mites being trapped inside them.

Gender

Among younger children, asthma develops twice as frequently in boys as in girls, but after puberty it may be more common in girls.

Socioeconomic Factors

Urban Life. Urban life is strongly associated with a higher risk. Although poverty plays a significant role, urban life has been associated with a higher risk for asthma in any income group and among both children and adults. In some urban areas, as many as 25% of children have asthma or show signs of wheezing. In fact, it may be greatly underdiagnosed in city children. A 1999 study reported that almost a third of children in inner-city kindergartens had asthma symptoms without a diagnosis of the disorder; 10% had actually been diagnosed with asthma, mainly because their symptoms were severe.

Ethnicity. Since 1980, asthma rates have risen the most dramatically among African American children, and they have significantly higher rates of asthma than Caucasian children. Hispanic children are also at higher risk. Both groups of minority children are more likely to have fatal asthma than Caucasian children.

Some studies indicate that the difference in risk exists simply because African Americans and other minority groups are more likely to live in urban areas. Poverty and lack of access to health care also play a role. However, Caucasian children who live in cities also face a high risk for asthma, and rural African American children do not.

Urban life and socioeconomic factors, however, may not fully explain the ethnic disparity.

Issues Surrounding Birth

Low Birth Weight. Infants of low birth weight are at higher risk for lung problems and asthma.

Winter Birth. Children born in the winter may have a greater risk for asthmatic allergies to cockroaches than children born at other times of the year.

Vitamin D. A 2006 study suggested a link between vitamin D intake during pregnancy and development of early childhood asthma. Pregnant women who had a higher intake of vitamin D were less likely to give birth to children who developed asthma.

Breast Feeding. Most studies on breastfeeding report some protection against wheezing and asthma in the first year of life. Breastfeeding has many other benefits for the child as well. The American Academy of Pediatrics recommends exclusively breastfeeding for the child's first 6 months of life.

Complications of Pregnancy. According to a 2000 study, complications of pregnancy, specifically those involving the mother's uterus (such as post-birth hemorrhage, pre-term contractions, insufficient placenta, and restricted growth of the uterus), are associated with an increased risk of childhood asthma. Another study reported that delivery procedures such as Cesarean section, the use of vacuum extraction or forceps also raised the risk of childhood asthma.

Obesity

In both adults and children, the incidence of obesity and asthma has been increasing over recent years. Studies report a strong association between the two conditions. Some experts suggest that excess weight pressing on the lungs may trigger the hyperreactive response in the airways typical of asthma. Others believe that asthma leads to obesity by inhibiting physical activity, although several studies have found no difference in activity levels between people with or without asthma. Some studies suggest that many obese people may be misdiagnosed as having asthma when they are simply short of breath, possibly because of the increased effort required for breathing.

In any case, there is evidence that losing weight can relieve asthma symptoms. Some evidence also suggests that people who are overweight (body mass index greater than 25) have more difficulty getting their asthma under control. Weight loss in anyone who is obese and has asthma or shortness of breath reduces airway obstruction and improves lung function. [See In-Depth Report #53: Weight control and diet.].

Other Risk Factors

Damp Homes. Studies suggest that children who live in damp homes have a much higher risk for asthma.

Mental Health. Research indicates that poor mental health of parents and children are significant predictors of more severe symptoms in childhood asthma. A 2000 study suggested that high stress levels can predict the onset and severity of asthma in children genetically at risk for the condition.

Symptoms

In children with asthmatic symptoms, it is important to first consider as a possible cause inhaled foreign objects such as peanuts; viral infections such as croup; and bacterial infections, which may be accompanied by high fever and progress rapidly. Any child who has frequent coughing or respiratory infections should be checked for asthma.

Typical Asthma Symptoms

The classic symptoms of an asthma attack include:

• Wheezing when breathing out is nearly always present during an attack. Usually the attack begins with wheezing and rapid breathing, and, as it becomes more severe, all breathing muscles become visibly active.
• Shortness of breath (dyspnea). Shortness of breath is a major source of distress in patients with asthma, although severe dyspnea does not always reflect a serious attack or reduced lung function.
• Coughing. In some people, the first symptom of asthma is a nonproductive cough.
• Chest tightness or pain. Initial chest tightness without any other symptoms may be an early indicator of a serious attack.
• Neck muscles may tighten, and talking may become difficult or impossible.
• Rapid heart rate
• Sweating
• Chest pain occurs in about 75% of patients. It can be very severe, although its intensity is not necessarily related to the severity of the asthma attack itself.

The end of an attack is often marked by a cough that produces thick, stringy mucus. After an initial acute attack, inflammation persists for days to weeks, often without symptoms. (The inflammation itself must still be treated, however, because it usually causes relapse.)

Diagnosis

The doctor will consider a diagnosis of asthma if a child has a history of periodic attacks of shortness of breath, coughing, and wheezing, perhaps accompanied by tightness in the chest. The parent should describe the pattern of symptoms and possible precipitating factors, including:

• Whether symptoms are more frequent during the spring or fall (allergy seasons)
• Whether exercise, a respiratory infection, or exposure to cold air has ever triggered an attack
• Any family history of asthma or allergic disorders such as eczema, hives, or hay fever

Ruling Out Other Diseases

A number of disorders may cause some or all of the symptoms of asthma. Panic disorder can coincide with asthma or be confused with it. Other diseases that must be considered during diagnosis are pneumonia, bronchitis, severe allergic reactions, psychosomatic illnesses, and certain rare disorders (such as tapeworm and trichomoniasis).

Pulmonary Function Tests

If symptoms and a patient's history are indicative of asthma, the doctor will usually perform tests known as pulmonary function tests to confirm the diagnosis and determine the severity of the disease.

Using a spirometer, an instrument that measures the air taken into and exhaled from the lungs, the doctor will determine several values:

• Vital capacity (VC), which is the maximum volume of air that can be inhaled or exhaled.
• Peak expiratory flow rate (PEFR), commonly called the peak flow rate, which is the maximum flow rate that can be generated during a forced exhalation.
• Forced expiratory volume (FEV1), the maximum volume of air expired in 1 second.

If the airways are obstructed, these measurements will fall. Depending on the results, the doctor will take the following steps:

• If measurements fall, the doctor typically asks the patient to inhale a bronchodilator. This drug is used in asthma to open the air passages. The measurements are taken again. If the measurements are more normal, the drug has most likely cleared the airways, and a diagnosis of asthma is strongly suspected.
• If measurement results fail to show airway obstruction, but asthma is still suspected, the doctor may perform a challenge test. It involves administering a specific drug (histamine or methacholine) that usually increases airway resistance only when asthma is present.

Allergy Tests

The patient may be given skin or blood allergy tests, particularly if a specific allergen is suspected and available for testing. Allergy skin tests may be the best predictive test for allergic asthma, although they are not recommended for people with year-round asthma.

One of the most common methods of allergy testing is the scratch test or skin prick test. The test involves placing a small amount of the suspected allergy-causing substance (allergen) on the skin (usually the forearm, upper arm, or the back), and then scratching or pricking the skin so that the allergen is introduced under the skin surface. The skin is observed closely for signs of a reaction, which usually includes swelling and redness of the site. With this test, several suspected allergens can be tested at the same time, and results are usually available within about 20 minutes.

Other Tests

Tests that either rule out other diseases or obtain more information about the causes of asthma include the following:

• A complete blood count
• Chest and sinus x-rays
• Computed tomography (CT) scans. CT scans may be helpful in certain cases, such as for determining wall thickness in airways in patients who are difficult to treat, which could signify a higher risk for lung damage.
• Examination of the patient's sputum for eosinophils (white blood cells that in high levels are associated with severe allergic asthma).
• Researchers are investigating measurements of certain chemicals in sputum or exhaled air that indicate airway inflammation. Such chemical markers include nitric oxide and hydrogen peroxide. For example, high levels of nitric oxide may prove to be a simple and noninvasive way of diagnosing asthma.

Treatment

Treating an Acute Attack in the Hospital. An acute attack may require hospitalization. Laboratory tests, an electrocardiogram (ECG), and a chest x-ray are performed to determine lung function, oxygen levels, and other indications of severity or rule out other causes. Depending on the results, the following treatments may be given:

• Beta2-agonists are the standard therapy. They are typically administered with a nebulizer (a device that administers the drug in a fine spray). Studies suggest, however, that even very small children may be able to use metered-dose inhalers (MDIs), which are just as effective and more convenient than nebulizers. (Intravenous delivery is not recommended in most cases.)
• An anticholinergic drug (ipratropium) is sometimes added to improve symptoms.
• A corticosteroid (commonly called a steroid) given within the first hour helps reduce the need for hospitalization. Steroids may be administered intravenously, as a shot, or orally. Children may respond well to oral steroids.
• Oxygen is usually administered, and can be life saving in severe cases.
• Infusions of magnesium sulfate open airways and are an important emergency treatment for adults. Its benefits for children need to be further demonstrated.
• In life-threatening situations, the patient may require mechanical ventilation.

Antibiotics are not useful for asthma attacks if there is no strong evidence of the presence of a bacterial infection. Viral infections, most often colds and the flu, are more likely to trigger an asthma attack. In such cases, antibiotics are not helpful and may have adverse effects.

Discharge and Relapse After Hospitalization. It typically takes about 3 - 4 hours to determine if a patient can be safely sent home or if they need to stay. Patients are generally discharged when:

• Symptoms are gone or minimal, and
• The peak expiratory flow rate is 70% or more of the predicted rate

Despite reasonable precautions, between 12 - 16% of patients relapse within 2 weeks of leaving the hospital. Receiving a steroid shot at discharge or taking an oral corticosteroid for a few days can reduce this risk.

General Guidelines for Treating and Managing Asthma on an On-Going Basis

Avoiding allergens, following appropriate drug treatments, and home monitoring are key elements in preventing dangerous asthma attacks and hospitalization. In addition, good communication between the doctor and patient is a key factor in a successful management program.

Understanding the Difference Between Treating Symptoms and Controlling the Disease

Medications for asthma fall into two categories:

• Rescue Medications. Medications that open the airways (bronchodilators, or inhalers) are used to quickly relieve any moderate or severe asthma attack. These drugs are usually short-acting beta-adrenergic agonists (beta2-agonists). Other drugs used in special cases include corticosteroids taken by mouth and anticholinergic drugs. None of these drugs have any effect on the disease process itself. They are only useful for treating symptoms.
• Maintenance Medications. Simply coping with asthma symptoms without also controlling the damaging inflammatory response is a common and serious error. For adults and children over age 5 with moderate-to-severe persistent asthma, experts now recommend inhaled corticosteroids and long-acting beta2-agonists.

Parents can greatly reduce the frequency and severity of their children’s asthma attacks by understanding the difference between coping with asthma attacks and controlling the disease over time. Unfortunately, many patients do not understand the difference between medications that provide rapid, short-term relief and those that are used for long-term symptom control. Many patients with moderate or severe asthma overuse their short-term medications and underuse their corticosteroid medications. The overuse of bronchodilators can have serious consequences; not using steroids can lead to permanent lung damage.

Patients need to understand that asthma symptoms can change quickly over time and that treatment strategies may need to change in response. In 2005, the two leading U.S. allergy associations published joint guidelines on controlling asthma. The guidelines emphasize that asthma treatment decisions need to be made on an individual basis. It is important that patients have a close relationship with their doctor. The doctor needs to evaluate a patient’s asthma symptoms at each visit to determine any need for changes in medication. According to the guidelines, asthma management is classified as either “well-controlled” or “not well-controlled.” The doctor may need to change some medications, or increase or decrease the dosage, depending on whether a child’s asthma is well-controlled or not well-controlled.

These are the signs of well-controlled asthma:

• Asthma symptoms occur twice a week or less
• Rescue bronchodilator medication is used twice a week or less
• Symptoms do not cause nighttime or early morning awakening
• Symptoms do not limit work, school, or exercise activities
• Peak flow meter readings are normal or the patient’s personal best
• Both the doctor and the patient consider the asthma to be well controlled

Devices Used for Administering Inhaled Drugs

Most asthma drugs are inhaled using various forms of inhalers or nebulizers. Inhaled drugs must be used regularly as prescribed and the patient carefully trained in their use in order for them to be effective and safe. Studies suggest that many children fail to use the devices properly, although newer devices are easier to use than others. The basic devices are the metered-dose inhaler (MDI), breath-actuated inhalers, dry powder inhalers, and nebulizers.

MDIs have used chlorofluorocarbons (CFCs) as their propellants. CFCs are damaging to the environment and are now being replaced with other propellants (hydrofluoroalkane) that are more environmentally safe, and do not chill the device as CFCs do. Devices that don't use any propellants are also now available.

Metered-Dose Inhaler. The standard device for administering any asthma medication is the metered-dose inhaler (MDI). This device, particularly when used with a spacer, allows precise doses to be delivered directly to the lungs. (The spacer is a tube that is attached to the inhaler. It serves as a holding chamber for the medication that is sprayed by the inhaler.) MDI-delivered drugs must be used regularly as prescribed and the patient carefully trained in their use in order for them to be effective and safe. Some patients hold the MDI too close to their mouths, or even inside them. Others may exhale too forcefully before inhalation.

The spacer helps improve medication delivery by allowing the patient additional time to inhale. They vary, however, in their effectiveness. It should be noted that MDIs can continue to deliver propellant even after the drug has been used up. Patients should track their medicine and throw the device away when the last dose has been administered.

Nebulizers (not MDIs) are typically used in very small children, both at home and in the emergency room. However, recent studies suggest spacers may be better than nebulizers for children and shorten the time spent in emergency rooms. Studies also indicate that with the use of a face mask and a spacer, the MDI works well even for infants in the emergency room and may prove to be useable at home.

Click the icon to see an illustrated series detailing a metered dose inhaler.

Breath-Actuated Inhalers. Breath-actuated rotary inhalers (Easi-Breathe and Autohaler) deliver the drug directly to the back of the throat as the user inhales. Their primary advantage over the MDI is their ease of use. They also do not use CFCs as propellants. In comparison studies, patients have been very successful with the breath-actuated inhalers. They are not recommended for children under 8 years old.

Dry Powder Inhalers. Dry powder inhalers (DPIs) deliver a powdered form of beta2-agonists or corticosteroids directly into the lungs. Such devices include Rotahaler, Spinhaler, Turbohaler, Clickhaler, Easyhaler, Diskhaler, Discus, Twisthaler, Spiros, and others. DPIs are as effective as the older devices, and generally have a better taste and are easier to manage. They may differ among themselves, however, in their ability to deliver drugs into the airways. In one study, for example, the Turbohaler was easier to use than the Diskhaler and so achieved better delivery.

Humidity or extreme temperatures can affect DPIs' performance, so they should not be stored in humid places (bathroom cabinets) or locations subject to high temperatures (glove compartments during summer months).

Dry-powder may cause tooth erosion. Children are advised to rinse their mouths out right after using these inhalers and to brush twice a day with a fluoride toothpaste.

Other Hand-Held Inhalers. Respimat delivers a fine-mist spray that is created by forcing the liquid medication through nozzles. It does not use any propellant.

Nebulizers. A nebulizer is a machine that delivers a fine spray of medication-containing liquid. Nebulizers are often used for children younger than 3 years and sometimes for older children who have difficulty using the MDI. It takes 5 - 10 minutes to administer medication using a nebulizer. Because the spray is less targeted than with the inhaler, it must deliver large amounts of the drug. This increases the risk for toxicity and severe side effects. Nebulizers should not be used by children who can manage an inhaler. Their use has been associated with a higher rate of hospitalizations and longer duration of symptoms than inhalers. A 2007 study also suggested that the misuse of home nebulizers may be an important factor in asthma deaths in children and young adults. If children must use an albuterol nebulizer, parents should be sure that it does not contain the preservative benzalkonium, which actually narrows the airways.

Click the icon to see an illustrated series detailing the use of a nebulizer.

Non-Medical Treatment Strategies

Asthma triggers a vicious emotional-physical cycle:

• Breathlessness and wheezing incite a fear of suffocation and death, even in very small children.
• This anxiety produces further constriction on the muscles surrounding the airways, which makes breathing even more difficult.

Caregivers must first focus on alleviating their own anxiety, which can heighten a child's own fears. The next step is to help the child relax. One method for this is as follows:

• The child sits comfortably, bending slight forward with the eyes closed.
• The hands are placed gently over the navel.
• The child is then told to pretend the stomach is a balloon.
• The "balloon" must be "blown up" by inhalation, not exhalation. The child can tell if this working because the hands will move slightly apart.
• When the child breathes out, the "balloon" will be made flat.

This exercise both relaxes the child and discourages shallow, oxygen-poor breathing. Massaging the child in gentle circles on the chest is relaxing and may also loosen mucus.

Other recommendations include:

• A child may also find relief by lying stomach-down on several pillows so that the head is slightly lower than the chest while the caregiver gently pats the back between the shoulder blades.
• Warm liquids, such as soup or hot cider, are effective in loosening mucus and may also relax bronchial muscles. Cold fluids, like cold air, should be avoided.
• Overhydration (too much liquid) can be harmful, however, so these drinks should not be forced on the child.
• Warm, moist air from vaporizers can greatly ease and moderate asthma attacks.
• Daily massages and breathing and relaxation techniques to reduce stress can be very helpful.

Monitoring

Many adults self-manage their asthma using daily monitoring of peak air flow with adjustments of the medications as needed. This involves the use of a peak flow meter, which measures peak expiratory flow rate (PEFR).

Click the icon to see an image of a peak flow meter.

Studies suggest, however, that for most children with asthma, an educational program is just as effective for managing the condition as monitoring. Most children do not need to monitor their peak air flow on any regular basis.

Quick-Relief Medications

These medications quickly control acute asthma attacks.

Short-Acting Beta2-Agonists

Beta2-agonists do not reduce inflammation or airway responsiveness but serve as bronchodilators, relaxing and opening constricted airways during an acute asthma attack. A short-acting inhaled beta2-agonist, taken as needed, is often the only medication used by children with chronic mild asthma.

Asthma is a disease in which inflammation of the airways causes airflow into and out of the lungs to be restricted. When an asthma attack occurs, mucus production is increased, muscles of the bronchial tree become tight, and the lining of the air passages swells, reducing airflow and producing the characteristic wheezing sound.

Specific short-acting beta2-agonists include:

• Albuterol (Proventil, Ventolin), called salbutamol outside the U.S., is the standard short-acting beta2-agonist in America. Other similar beta2-agonists are isoproterenol (Isuprel, Norisodrine, Medihaler-Iso), metaproterenol (Alupent, Metaprel), pirbuterol (Maxair), terbutaline (Brethine, Brethaire, Bricanyl), and bitolterol (Tornalate). Isoetharine (Bronkometer, Bronkosol) is available in nebulizers.
• Newer beta2-agonists, including levalbuterol (Xopenex), have more specific actions than the standard drugs. Xopenex is administered with a nebulizer, and studies have indicated that it is as effective as albuterol with fewer side effects. The original formulation of Xopenex was administered with a nebulizer. A new metered-dose inhaler formulation was launched at the end of 2005. It is approved for children age 4 years and older.

Short-acting bronchodilators are generally administered through inhalation and are effective for 3 - 6 hours. They relieve the symptoms of acute attacks, but they do not control the underlying inflammation. If asthma continues to worsen with the use of these drugs, a doctor may prescribe corticosteroids or other drugs to treat underlying inflammation.

Side Effects of Beta2-Agonists. Side effects of all beta2-agonists may include:

• Anxiety
• Tremor
• Restlessness
• Headache
• Fast and irregular heartbeats. A doctor should be notified immediately if this side effect occurs.
• These drugs should be taken with caution by children with diabetes or a history of seizures.
• Beta2-agonists have serious interactions with certain drugs and parents should tell the doctor about any other medications their child is taking.

Loss of Effectiveness and Overdose. There has been some concern that short-acting beta2-agonists become less effective when taken regularly over time, increasing the risk for overuse. Over time, some patients may become tolerant to many effects of short-acting beta2-agonists. The degree to which this affects the airways is uncertain. In some studies, the duration of action has declined but the peak effect appears to be preserved, making these drugs still useful for acute attacks. Regular use of long-acting beta2-agonists may increase the chances of a reduced effect from the short-acting forms.

A 2005 landmark study suggested that patients’ differing clinical response to albuterol may be based on their genotype. Albuterol targets the beta-adrenergic receptor. In the Beta-Adrenergic Response by Genotype (BARGE) trial, researchers studied the effects of albuterol on patients with two different forms of this receptor. The results suggested that patients with the arginine form of the receptor did not respond to albuterol. These patients’ asthma symptoms actually improved when albuterol was not used. By contrast, patients with the glycine form of the receptor had improved asthma control with albuterol.

Anticholinergic Drugs

Inhaled ipratropium bromide (Atrovent) acts as a bronchodilator over time. Ipratropium bromide alone is only modestly beneficial for acute asthma attacks. In fact, the drug is not approved specifically for asthma. Some parents report benefit for treating wheezing in infants. It is also sometimes used in the emergency room to treat children with severe asthma to enhance the effects of intravenous beta2-agonists.

Oral Corticosteroids

Common oral corticosteroids include prednisone/prednisolone, dexamethasone, methylprednisolone, and hydrocortisone. They reduce inflammation very effectively. A 2006 study indicated that oral prednisolone worked better than inhaled fluticasone for treating mild-to-moderate asthma attacks in children in emergency rooms. However, children often have difficulty taking these drugs because they have a bitter taste and can cause vomiting. Taking oral dexamethasone for 2 days may be as effective and more tolerable than the standard 5-day regimen of prednisone/prednisolone. Prolonged use of oral steroids has widespread and sometimes serious side effects, so they are not generally give to children for longer than a few days.

[See In-Depth Report #4: Asthma in adults.]

Long-Term Relief Medications

These medications are taken on a regular basis to prevent asthma attacks and control chronic symptoms.

Inhaled Corticosteroids

Corticosteroids, also called glucocorticoids or steroids, are powerful anti-inflammatory drugs. Steroids are not bronchodilators (they do not relax the airways) and have little effect on symptoms. Instead, they work over time to reduce inflammation and prevent permanent injury in the lungs. They can also help prevent asthma attacks from occurring. Many studies have shown that the use of inhaled corticosteroids in patients with moderate-to-severe asthma significantly reduces the rate of rehospitalizations and deaths from asthma.

Inhalation of corticosteroids makes it possible to provide effective local anti-inflammatory activity in the lungs with minimal systemic effects. (By contrast, oral steroids have considerable side effects throughout the body.) Inhaled corticosteroids are recommended as the primary therapy under the following circumstances:

• For any asthmatic condition more serious than occasional episodes of mild asthma. (Low-doses of inhaled steroids may even be safe and effective for some people with mild asthma, particularly those who find themselves using beta2-agonists daily.)
• When treatment with bronchodilators is not effective.

Examples of inhaled corticosteroids:

• Inhaled steroids include fluticasone (Flovent), budesonide (Pulmicort), triamcinolone (Azmacort and others), and flunisolide (AeroBid). In general, the newer drugs are more powerful than the older generation of inhaled drugs. Budesonide (Pulmicort Respules) is available in a jet nebulizer for children from 12 months to 8 years. It is the first such medication to be approved for children in this age group.
• The FDA approved a new inhaled corticosteroid, mometasone furoate (Asmanex) was approved in 2005 for patients age 12 and older.
• The older corticosteroid inhalants are beclomethasone (Beclovent, Vanceril) and dexamethasone (Decadron Phosphate Respihaler and others). They are less powerful than the newer steroids when delivered with standard inhalers. New inhalers that use very fine sprays (QVAR, Autohaler) to deliver the drugs deep into the lungs may prove to be as effective as the newer, more potent steroids.
• Inhalers that combine both long-acting beta2-agonists and corticosteroids are also available. These include Symbicort (budesonide/formoterol), which was approved in 2006 for patients ages 12 years and older.

Expert guidelines recommend inhaled corticosteroids as the preferred first-line therapy for children with mild-to-moderate asthma. Nevertheless, they are still significantly underprescribed in the patients who need them most. An important 2007 study of 6 - 14 year old children with asthma compared inhaled corticosteroid therapy (fluticasone) with an inhaled corticosteroid/long-term beta2 agonist (fluticasone/salmeterol) and a leukotrine receptor antagonist (montelukast). The results indicated that fluticasone alone worked better than the other two treatments.

Researchers have been investigating whether early treatment with corticosteroids can help prevent the development of asthma in at-risk children. Two important 2006 studies in the New England Journal of Medicine suggested that while inhaled corticosteroids helped ease symptoms and reduce breathing problems in pre-school children at risk for asthma, they did not help protect against asthma development.

For now, experts caution against corticosteroids for infants and toddlers with mild asthma and urge close monitoring especially for children under age 5 with severe asthma who are receiving high doses. Because the newer potent drugs, particularly fluticasone, may produce major side effects similar to oral steroids, it is important when treating all children to aim for the lowest effective dose possible. Fortunately, studies suggest that low doses of fluticasone may achieve the same benefits as with high ones, thus reducing risks for serious side effects. Better delivery methods may also allow lower doses.

Side effects of inhaled steroids may include:

• The most common side effects are throat irritation, hoarseness, and dry mouth. These effects can be minimized or prevented by using a spacer device and rinsing the mouth after each treatment.
• Rashes, wheezing, facial swelling (edema), fungal infections (thrush) in the mouth and throat, and bruising are also possible but not common with inhalators.
• Some children experience changes in mood, memory, and behavior. These changes are not permanent.
• Some studies have suggested a higher risk for gum inflammation.
• Oral steroids reduce bone density. Research reports that inhaled steroids -- both older and newer drugs -- may also affect bone growth and density. However, a number of studies report only a slight effect (about half an inch) on children's growth, which may be only temporary. It is still unknown if these drugs have any significant long-term effect on bone density. Calcium supplements may help prevent bone loss that is due to inhaled steroids.
• It is not yet known whether inhaled steroids affect lung growth in very young children. Steroids administered using nebulizers are of particular concern.
• There is also some concern that the stronger drugs, particularly fluticasone, suppress the adrenal system to a greater degree than other steroid inhalants. This effect, in turn, reduces levels of natural steroids -- notably cortisol, the major stress hormone. (This is a serious side effect of oral steroids).

Long-Acting Beta2-Agonists

Long-acting beta2-agonists are used in combination with inhaled corticosteroids for treating children with moderate-to-severe asthma. These drugs include include salmeterol (Serevent Diskus) and formoterol (Foradil Aerolizer). A single inhaler (Advair Diskus) that combines both salmeterol and the corticosteroid fluticasone is available for children age 4 years and older, and an inhaler (Symbicort) combining formoterol and the corticosteroid budesonide is approved for children age 12 years and older.

Long-acting beta2-agonists are used for preventing an asthma attack (not for treating attack symptoms). The effects of one dose of a long-acting beta2-agonist last for about 12 hours, so they are particularly effective during the night. These drugs also may be used for prevention of exercise-induced asthma in people and to protect against aspirin-induced asthma.

However, research indicates that long-acting beta2-agonists can worsen asthma by increasing symptom severity. These drugs may also increase the risk for asthma-related deaths. Experts are still trying to determine when long-acting beta2-agonists should be added to an asthma treatment plan. If a child’s symptoms do not improve or if symptoms worsen with this type of drug, the doctor will recommend discontinuing it. Patients should not, however, stop taking this drug or other asthma medications without first talking with their doctors.

Side Effects. Side effects of long-acting beta2-agonists are similar to the short-acting drugs.

Specific Warning on Salmeterol and Formoterol. In 2003 a "black box" warning was added to product packaging for drugs that contain salmeterol, including Serevent Diskus, and Advair Diskus. Serevent and Advair are approved for patients age 12 years and older. The warning was based on a study that demonstrated more serious and even fatal asthma episodes in patients who used the drug than in patients who used a placebo.

In 2006, the FDA updated the warning to include formoterol (Foradil Aerolizer, approved for patients 5 years and older). Warnings for salmeterol and formoterol products emphasize that these medicines can increase the risk of severe asthma episodes. Long-acting beta2-agonists require up to 20 minutes to achieve effectiveness, and there is a danger of overdose if a patient is not aware of this delay and takes additional doses to achieve faster relief. The FDA recommends that patients:

• Use long-acting beta2-agonists only if other medicines (such as steroids) have not helped control asthma.
• Use a short-acting bronchodilator, not a long-acting beta2-agonist, to treat sudden wheezing.
• Do not use long-acting beta2-agonists to treat wheezing that is getting worse. Call your doctor if this situation occurs.
• Do not stop using any asthma medicines without first talking to your doctor.

Cromolyn and Similar Drugs

Cromolyn sodium (Intal) is both an anti-inflammatory drug and has antihistamine properties that block asthma triggers such as allergens, cold, or exercise. Cromolyn has been the anti-inflammatory drug of choice for prevention of asthma attacks in children over age 4 with chronic moderate asthma. It is not as effective as inhaled corticosteroids, however, for reducing hospitalization rates, improving symptoms, and reducing the use of beta2-agonists in children with persistent asthma. Still, cromolyn has a well-known long-term safety record, while the long-term adverse effects of corticosteroids in children are still not fully known. Many children who need asthma maintenance therapy will still do well on cromolyn. (It may not provide any real benefit for children under age 4.)

Nedocromil (Tilade) is similar to cromolyn and needs to be taken only once a day. It also prevents asthmatic reactions to cold and exercise. It is not used in very young children. A cromolyn nasal spray called Nasalcrom has been approved for over-the-counter purchase, but only to relieve nasal congestion caused by allergies. Patients should not use it for self-medication without the advice of a doctor.

Side Effects. Side effects of cromolyn include nasal congestion, coughing, sneezing, wheezing, nausea, nosebleeds, and dry throat. Nedocromil has an unpleasant taste, and some people have complained of nausea, headache, and spasms in the airways, but no serious side effects have been reported.

Leukotriene-Antagonists

Leukotriene-antagonists (also called anti-leukotrienes or leukotriene modifiers) are oral medications that block leukotrienes. Leukotrienes are powerful immune system factors that, in excess, produce a battery of damaging chemicals that can cause inflammation and spasms in the airways of people with asthma. As with other anti-inflammatory drugs, leukotrienes are used for prevention and not for treating acute asthma attacks.

Leukotriene-antagonists include zafirlukast (Accolate), montelukast (Singulair), zileuton (Ziflo), and pranlukast (Ultair, Onon). These drugs are proving helpful for long-term prevention of asthma, including exercise-induced asthma and aspirin (or NSAID) -induced asthma. However, most studies to date have reported better success with inhaled corticosteroids than with the leukotriene-antagonists. A 2006 study of children with mild-to-moderate persistent asthma indicated that the corticosteroid fluticasone worked better than the leukotriene-antagonist montelukast in controlling symptoms. Nevertheless, some studies suggest that montelukast, which comes in a chewable tablet, may be particularly useful for managing asthma in small children (ages 2 - 5), since they have trouble with inhaled steroids.

Side Effects and Complications. Gastrointestinal distress is the most common side effect of leukotriene-antagonists. Very few other side effects have been reported. In general, these drugs appear to be safe and well-tolerated.

Of some concern are reports of Churg-Strauss syndrome in a few people taking zafirlukast or montelukast. Churg-Strauss syndrome is very rare, but it causes blood vessel inflammation in the lungs and can be life threatening. Oral steroids quickly resolve the problem. In fact, usually the syndrome has occurred in patients who were tapering off steroids and changing over to the leukotriene-antagonists. Some experts believe that, in such cases, the steroids may simply have masked the presence of the disorder, which then developed when the steroid drugs were withdrawn. Symptoms include severe sinusitis, flu-like symptoms, rash, and numbness in the hands and feet.

Other concerns are indications of liver injury in patients taking zileuton and zafirlukast when taken at higher than standard doses. No adverse effects on the liver have been reported to date with montelukast.

Theophylline

Theophylline (Theo-Dur, Theolair, Slo-Phyllin, Slo-bid, Constant-T, Respbid) is a mild-to-moderate bronchodilator that has been used to treat childhood asthma for more than 30 years. It is useful for treating nocturnal asthma and may also have anti-inflammatory qualities even in low doses.

Available in tablet, liquid, and injectable forms, some theophylline sustained-release tablets and capsules have a long duration of action and can therefore be taken once or twice a day with good results.

Side effects may include changes in behavior, mood, and memory. If theophylline is not taken exactly as prescribed, an overdose can easily occur. Toxicity can cause nausea, vomiting, headache, insomnia, and, in rare cases, disturbances in heart rhythm and convulsions. Contact a doctor immediately if any of these side effects occur.

The risks for these adverse effects are small if the drug is taken exactly as prescribed but the following precautions should be noted:

• Infants tend to metabolize the drug extremely slowly and, therefore, should receive very low doses.
• By the time children reach age 1, however, they metabolize the drug faster than adults. There is a risk, therefore, of toxic effects.
• Fever and certain antibiotics may slow down the rate at which theophylline is eliminated from the body. In such cases, the doctor may want to reduce the dosage of theophylline.

If a child is taking theophylline on an ongoing basis, the doctor should monitor the drug level at the start of therapy and at regular intervals thereafter.

Omalizumab

Omalizumab (Xolair) is FDA-approved for patients age 12 and older who have moderate-to-severe persistent asthma related to allergies. The first drug of this type to be approved for asthma, omalizumab is a monoclonal antibody (MAb), a genetically developed drug designed to attack very specific targets. Omalizumab is administered by injection every 2 - 4 weeks. It is used only to treat patients whose symptoms are not controlled by inhaled corticosteroids.

Omalizumab prevents the antibody immunoglobulin E (IgE) from triggering the inflammatory events that lead to asthmatic attacks. Studies have shown excellent benefits of the drug, including a reduced need for corticosteroids, fewer hospitalizations, and significant symptomatic improvements.

However, about 1 in 1,000 patients who take omalizumab develop anaphylaxis (a life-threatening allergic reaction). In 2007 the FDA requested the manufacturers of omalizumab to put a “boxed warning” on the medicine’s label emphasizing the drug’s risk for anaphylaxis. The boxed warning notes that patients can develop anaphylaxis after any dose of omalizumab, even if they had no reaction to a first dose. Anaphylaxis may occur up to 24 hours after the dose is given.

The FDA recommends that healthcare providers observe patients for at least 2 hours after an injection. Patients should also carry emergency self-treatment for anaphylaxis (such as an Epi-Pen) and know how to administer it. With an Epi-Pen, or similar auto-injector device, patients can quickly give themselves a life-saving dose of epinephrine.

Anaphylaxis symptoms include:

• Difficulty breathing
• Chest tightness
• Dizziness
• Fainting
• Itching and hives
• Swelling of the mouth and throat

[See In-Depth Report #4: Asthma in adults.]

Other Treatments

Alternative therapies are widely used by children, adolescents, and adults with asthma. In one study, nearly half of asthma or allergy sufferers resorted to alternative treatments. To date, however, evidence does not support most alternative therapies, including high-dose vitamins, urine injections, homeopathic remedies, and most herbal remedies.

Relaxation and Stress-Reduction Techniques. Patients report benefits from many stress reduction and physical techniques, such as acupuncture, hypnosis, breathing relaxation techniques, the Alexander technique, massage therapy, and meditation practices. There have been very few well-conducted studies supporting their use, however.

Acupuncture, hypnosis, and biofeedback are alternative ways to control pain. Acupuncture involves the insertion of tiny sterile needles, slightly thicker than a human hair, at specific points on the body.

Breathing Exercises. Some studies have suggested that breathing exercises or training may be helpful. A number of different methods are available. One example is the Buteyko breathing method, an experimental approach designed to increase levels of carbon dioxide in the body. To do this, patients are trained to reduce their volume of breath and to avoid hyperventilation (over-breathing). Some studies report that patients using this method reduce their use of medications and improve their quality of life. The system originated in Australia and is not yet widely available in the U.S.

Probiotics. Probiotics are beneficial bacteria that may possibly help protect against allergies and asthma. Antibiotic overuse and modern hygiene may specifically be reducing these helpful organisms. Look for probiotics in active yogurt cultures and in supplements, which are being studied for protection.

Herbal Remedies. Butterbur (also known as Petasites hybridus, butter dock, blatterdock, bog rhubarb, and exwort), is a traditional herbal remedy used for seasonal allergies and asthma. In a 2002 study, it was as effective and less sedating than a commonly prescribed antihistamine for treating seasonal allergies over a 2-week period. However, little research exists on its effect on asthma. Overall, there is scant evidence supporting the benefits of herbs and nutritional supplements for asthma control.

Generally, manufacturers of herbal remedies and dietary supplements do not need FDA approval to sell their products. Just like a drug, herbs and supplements can affect the body's chemistry, and therefore have the potential to produce side effects that may be harmful. There have been a number of reported cases of serious and even lethal side effects from herbal products. Always check with your doctor before using any herbal remedies or dietary supplements.

Managing Asthma

The more allergies a child has, the more severe the asthma. Making lifestyle changes to reduce allergy attacks and other triggers is extremely important.

Indoor Protection

House dust is a reservoir for pollen and dust mites. Some experts believe that reducing household allergens and pollutants in the home could reduce asthma in children by 40%.

Controlling for Dust. Spray furniture polish is very effective for reducing both dust and allergens. Air cleaners, filters for air conditioners, and vacuum cleaners with High Efficiency Particular Air (HEPA) filters can help remove particles and small allergens found indoors. Neither vacuuming nor the use of anti-mite carpet shampoo, however, is effective in removing mites in house dust. Vacuuming actually stirs up both mites and cat allergens. If possible, avoid carpets and rugs.

Click the icon to see an image of a HEPA air filter.

Bedding and Curtains. Many experts recommend reducing exposure to dust mites by enclosing mattresses and pillows in semipermeable coverings. (Vinyl mattress covers limit airflow and may also worsen, or even cause, asthma in children. Synthetic pillows may pose a significantly higher risk for severe asthma attacks in children than feather or no pillows.) However, several 2005 studies suggested that such covers do not prevent asthma or allergies. Replace curtains with shades or blinds, and wash bedding using the highest temperature setting.

Click the icon to see an image of dust mite prevention.

One study found that children sleeping in bottom bunk beds are significantly more likely to develop asthma than siblings occupying the upper bunks. Families with children who have asthma or allergies should avoid bunk beds or be sure that children with asthma sleep in the top bunk. Even with standard beds, it may be useful to have them sleep as high off the floor as possible.

Exterminating Pests (Cockroaches and Mice). Use professional exterminators to eliminate cockroaches. (One study reported that ridding a home of cockroaches and cleaning the house using standard housecleaning techniques failed to eliminate the cockroach allergens themselves.) Exterminate mice, and attempt to remove all dust, which might contain mouse urine and dander.

Reducing Humidity in the House. Although warm, moist air from vaporizers can greatly ease and moderate asthma attacks, living in a damp house is counterproductive. Dust mites thrive in humidity and damp houses increase the risk for mold, so on-going humidifiers can be unhelpful. If they are used, humidity levels should not exceed 40%, and humidifier should be cleaned daily with a vinegar solution.

Controlling Pets. People with asthma who already have pets and are not allergic to them probably have a low risk for developing such allergies later on. When children are exposed to more than one dog or cat during their first year, they have a much lower risk for allergies and asthma.

For children who have an existing allergy to pets, however, the pets should be given away or kept outside. If this isn't possible, they should at least be confined to carpet-free areas outside the bedroom. Cats harbor significant allergens, which can even be carried on clothing; dogs usually present fewer problems. Washing animals once a week can reduce allergens. Dry shampoos, such as Allerpet, are now available for both cats and dogs to remove allergens from skin and fur and are easier to administer than wet shampoos.

Many of the same substances trigger both allergies and asthma. Common allergens include pollen, dust mites, mold and pet dander. Other asthma triggers include irritants like smoke, pollution, fumes, cleaning chemicals, and sprays. Asthma symptoms can be substantially reduced by avoiding exposure to known allergens and respiratory irritants.

Preventing Exposure to Cigarette and Cooking Smoke. Parents who smoke are strongly urged to quit. Studies indicate that exposure to second-hand smoke in the home increases the risk for asthma and asthma-related emergency room visits in children. Even smoky cooking can worsen asthma.

Parental smoking has been shown to increase the airway responsiveness of infants as early as the first 2 - 10 weeks of life. This extends even to the fetus of pregnant women who smoke. Such mothers tend to have babies born at a low birth weight, which affects lung function and increases babies' risks for asthma.

Outdoor Protection

Avoiding Outdoor Allergens. The following are some recommendations for avoiding allergens outside:

• Avoid scheduling camping and hiking trips during times of high pollen count (generally, May and June for grass pollen and mid-August to October for ragweed).
• Patients should avoid strenuous activity when ozone levels are highest, which usually occur in early afternoon, particularly on hot hazy summer days. Levels are lowest in early morning and at dusk.
• Asthma attacks are often higher during thunderstorms. Some evidence points to a build-up of ozone that accompanies such storms. Other evidence suggests that the changing airflow patterns bring a sudden downdraft of air containing concentrations of pollens, small particles and allergens.
• Patients who are allergic to mold should avoid barns, hay, raking leaves, and mowing grass.
• Exposure to automobile fumes may worsen asthma. Fungi in car air conditioners can also be a problem.

Reducing Exposure to Air Pollution. Children breathe faster than adults, taking in more pollutants, and therefore are particularly susceptible to soot and other small particles in the air. A 2001 study found an association between higher rates of asthma and other health problems in children who were exposed to high levels of specific pollutants (particularly sulfur dioxide and nitrogen dioxide). Diesel fuel exhaust has also been associated with worsening asthma in children.

Some experts point out that asthma rates in North America have increased over recent years while the prevalence of many common air pollutants have declined. So pollution is unlikely to be a primary cause of asthma. Regardless of whether pollution is an important cause of asthma, evidence strongly suggests that it can affect existing asthma.

Medications for Treating Seasonal Allergies

Patients with asthma and chronic allergic rhinitis may require daily medications. Patients with severe seasonal allergies may be advised to start medications a few weeks before the pollen season, and to continue it until the season is over.

Immunotherapy ("allergy shots") may help reduce asthma symptoms, and the use of asthma medications, in patients with known allergies. They may also help prevent the development of asthma in children with allergies. Immunotherapy poses some risk for severe allergic reactions, especially for children with poorly controlled asthma, so it is important that the doctor carefully evaluates the child’s asthma condition.

[See In-Depth Report #77: Allergic rhinitis.]

Dietary Factors

Weight Loss. Children who are both asthmatic and overweight may reduce asthma symptoms simply with weight loss.

Fruits, Vegetables, and Whole Grains. Healthy foods are important for lung function. Specific foods that may be important for healthy lungs contain antioxidants (deep green and yellow-orange fruits and vegetables), selenium (fish, red meat, grains, eggs, chicken, liver, garlic), plant chemicals called flavonoids (apples, onions), and magnesium (green leafy vegetables, nuts, whole grains, milk, and meats).

Fish Oil. Omega-3 fatty acids, found in cold water oily fish and in supplements (preferably DHA-EPA, the important compounds in fish oil) have anti-inflammatory effects. Some evidence suggests they may be helpful for people with asthma.

Caffeine. Caffeine has properties that are similar to the asthma drug theophylline. A major analysis of studies reported that caffeine improved lung function for up to 4 hours after consumption. Although tea and coffee are the major sources of caffeine, some sodas contain it and should be avoided when children have an asthma attack. (People who are going to have their lung function tested should avoid drinking coffee, tea, or other caffeinated beverages for at least 4 hours beforehand.)

Food Allergies. Although about 70% of people with asthma believe their symptoms are aggravated by food allergies, studies indicate that this belief may be true in only 5% of cases. If young children show signs of or test positive for food allergies, however, parents should be extra cautious in preventing exposure to any asthma trigger. Some doctors now counsel all children with asthma to avoid nuts entirely, and, of course, children who experience reactions to any foods should avoid them.

Chemicals that may pose some risk for an allergic reaction are monosodium glutamate, or MSG (found in some canned soups, cheese, and certain vegetables), and sulfites (preservatives in foods, such as frozen potatoes and tuna). Contrary to what many believe, dairy products do not appear to worsen asthma symptoms in people who are not already allergic to them.

Exercise

Asthma is no reason to avoid exercise. Historically, about 10% of Olympic athletes have asthma. Some studies indicate that long-term exercise may help control asthma and reduce hospitalization.

Encourage children with asthma to swim and play sports, such as baseball, that will present less difficulty for them. Intense activities lasting less than 2 minutes, such as sprinting or competitive swimming, may cause fewer problems than longer-lasting exercises.

Young people who enjoy running should probably choose an indoor track to avoid pollutants. Swimming is excellent for people with asthma. Yoga practice, which uses both stretching, breathing, and meditation techniques, may have particular benefits. One study reported that two-thirds of patients who practiced yoga regularly were able to reduce or stop taking their asthma medications.

Patients should consult their doctors before starting any exercise program. Exercise-induced asthma is a limited condition that has specific recommendations.

Preventing and Treating Respiratory Infections

People with asthma should try to minimize their risk for respiratory tract infections. Washing hands is a very simple but effective preventive measure.

Patients with asthma should ask their doctor about getting the influenza ("flu") vaccine and also whether they should receive the vaccination against pneumococcal pneumonia.

Zanamivir, a new drug used for treating influenza, is considered safe for patients with asthma 12 years of age or older. In one study, patients with asthma treated with zanamivir experienced fewer flu symptoms, and their lung function improved.

Reducing Stress and Negative Moods

People with asthma have no higher rate of anxiety or depression than the general population. However, such emotions interact with the effects of asthma and its treatments in important ways:

• Negative emotions can discourage compliance with medication and the ability to cope.
• Poor control of asthma symptoms, in turn, increases the risk for negative emotions.
• Stress and depression have been associated with more severe symptoms and even an increased risk of fatal asthma attacks.

Some evidence suggests that stress reduction techniques, a positive attitude, and relaxation techniques may be very helpful in the long-term management of asthma.

Resources

• www.lungusa.org -- The American Lung Association
• www.acaai.org -- American College of Allergy, Asthma & Immunology
• www.aaaai.org -- American Academy of Allergy, Asthma, and Immunology
• www.nhlbi.nih.gov -- National Heart, Lung, and Blood Institute
• www.asthma-carenet.org -- Childhood Asthma Research and Education Network
• www.njc.org -- National Jewish Center for Immunology and Respiratory Medicine
• www.aafa.org -- Asthma and Allergy Foundation of America
• www.aanma.org -- Allergy and Asthma Network, Mothers of Asthmatics

References

Akinbami L; Centers for Disease Control and Prevention National Center forHealth Statistics. The state of childhood asthma, United States, 1980-2005. Adv Data. 2006 Dec 12;(381):1-24.

Bisgaard H, Hermansen MN, Loland L, Halkjaer LB, Buchvald F. Intermittent inhaled corticosteroids in infants with episodic wheezing. N Engl J Med. 2006 May 11;354(19):1998-2005.

Cates CJ, Crilly JA, Rowe BH. Holding chambers (spacers) versus nebulisers for beta-agonist treatment of acute asthma. Cochrane Database Syst Rev. 2006 Apr 19;(2):CD000052.

Douwes J, van Strien R, Doekes G, Smit J, Kerkhof M, Gerritsen J, et al. Does early indoor microbial exposure reduce the risk of asthma? The Prevention and Incidence of Asthma and Mite Allergy birth cohort study. J Allergy Clin Immunol. 2006 May;117(5):1067-73.

Guilbert TW, Morgan WJ, Zeiger RS, Mauger DT, Boehmer SJ, Szefler SJ, et al. Long-term inhaled corticosteroids in preschool children at high risk for asthma. N Engl J Med. 2006 May 11;354(19):1985-97.

Haland G, Carlsen KC, Sandvik L, Devulapalli CS, Munthe-Kaas MC, Pettersen M, et al. Reduced lung function at birth and the risk of asthma at 10 years of age. N Engl J Med. 2006 Oct 19;355(16):1682-9.

Marks GB, Mihrshahi S, Kemp AS, Tovey ER, Webb K, Almqvist C, et al. Prevention of asthma during the first 5 years of life: a randomized controlled trial. J Allergy Clin Immunol. 2006 Jul;118(1):53-61.

National Asthma Education and Prevention Program Expert Panel Report: Guidelines for the Diagnosis and Management of Asthma Update on Selected Topics -- 2002. Rockville, MD. National Heart, Lung, and Blood Institute, US Dept of Health and Human Services; 2003. NIH publications 02-5074.

O'Byrne PM, Pedersen S, Busse WW, Tan WC, Chen YZ, Ohlsson SV, et al. Effects of early intervention with inhaled budesonide on lung function in newly diagnosed asthma. Chest. 2006 Jun;129(6):1478-85.

Salpeter SR, Buckley NS, Ormiston TM, Salpeter EE. Meta-analysis: effect of long-acting beta-agonists on severe asthma exacerbations and asthma-related deaths. Ann Intern Med. 2006 Jun 20;144(12):904-12.

Schuh S, Dick PT, Stephens D, Hartley M, Khaikin S, Rodrigues L, Coates AL. High-dose inhaled fluticasone does not replace oral prednisolone in children with mild to moderate acute asthma. Pediatrics. 2006 Aug;118(2):644-50.

Sorkness CA, Lemanske RF Jr, Mauger DT, Boehmer SJ, Chinchilli VM, Martinez FD, et al. Long-term comparison of 3 controller regimens for mild-moderate persistent childhood asthma: the Pediatric Asthma Controller Trial. J Allergy Clin Immunol. 2007 Jan;119(1):64-72.

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