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Asthma in Children

by John T. McBride, MD

Asthma is a recurring inflammatory lung disorder in which certain stimuli (triggers) inflame the airways and cause them to temporarily narrow, resulting in difficulty breathing.

  • Asthma triggers include viral infections, smoke, perfume, pollen, mold, and dust mites.

  • Wheezing, cough, shortness of breath, chest tightness, and difficulty breathing are symptoms of asthma.

  • The diagnosis is based on a child's repeated wheezing episodes, a family history of asthma, and sometimes the results of tests that measure how well the lungs function.

  • Many children who wheeze in childhood will not have asthma later in life.

  • Asthma symptoms can be prevented by avoiding triggers.

  • Treatment includes bronchodilators and inhaled corticosteroids.

Although asthma can develop at any age, it most commonly begins in childhood, particularly in the first 5 years of life. Some children continue to have asthma into the adult years. In other children, asthma resolves. Sometimes, children who doctors thought had asthma actually had another disorder that caused similar symptoms (see Wheezing in Infants and Young Children).

Asthma has become much more common in recent decades. Doctors are not sure why this is so, but there are theories. More than 8.5% of children in the United States have been diagnosed with asthma, which is over a 100% increase in recent decades. The rate soars to 25% to 40% among some populations of urban children. Asthma is the leading cause of hospitalization for children and is the number one chronic condition causing elementary school absenteeism.

Most children with asthma are able to participate in normal childhood activities, except during flare-ups. A smaller number of children have moderate or severe asthma and need to take daily preventive drugs to enable them to engage in sports and normal play.

For unknown reasons, children with asthma respond to certain stimuli (triggers) in ways that children without asthma do not. Children with asthma may have certain genes that may make them more susceptible to react to certain triggers. Most children with asthma also have parents and siblings or other relatives with asthma, which is evidence that genes are important in asthma. There are many potential triggers, and most children respond to only a few. In some children, specific triggers for flare-ups cannot be identified.

These triggers all result in a similar response. Certain cells in the airways release chemical substances. These substances cause the airways to become inflamed and swollen and stimulate the muscle cells in the walls of the airways to contract. Repeated stimulation by these chemical substances increases mucus production in the airways, causes shedding of the cells lining the airways, and enlarges the muscle cells in the walls of the airways. Each of these responses contributes to a sudden narrowing of the airways (an asthma attack). In most children, the airways return to normal between asthma attacks.

Common Asthma Triggers

Triggers

Examples

*Viral infections are the most common triggers in children.

Allergens

Dust or house mites, molds, outdoor pollen, animal dander, cockroach feces, and feathers

Exercise

Particularly exercise in cold or dry air

Irritants

Firsthand and secondhand tobacco smoke, perfumes, wood smoke, cleaning products, scented candles, outdoor air pollution, strong odors, and irritating fumes

Viral infections*

Respiratory viruses, particularly those that cause common colds

Other

Emotions (such as anxiety, anger, and excitement), aspirin, and gastroesophageal reflux

Risk Factors

Doctors do not completely understand why some children develop asthma, but a number of risk factors are recognized:

  • Viral infections

  • Inherited and prenatal factors

  • Allergen exposure

A child with one parent who has asthma has a 25% risk of developing asthma. If both parents have asthma, the risk increases to 50%. Children whose mothers smoked during pregnancy may be more likely to develop asthma. Asthma also has been linked to other factors related to the mother, such as young maternal age, poor maternal nutrition, and lack of breastfeeding. Prematurity and low birth weight are also risk factors.

In the United States, children in urban environments are more likely to develop asthma, particularly if they are from lower socioeconomic groups. Although it is not entirely understood, it is believed that poorer living conditions, greater potential exposure to triggers, and less access to health care contribute to the higher incidence of asthma in these groups. Although asthma affects a higher percentage of black children than white, the role that genetic aspects of race play in the increasing rate of asthma is controversial because black children are also more likely to live in urban areas.

Children who are exposed to high concentrations of certain allergens, such as dust mites or cockroach feces, at an early age are more likely to develop asthma. However, doctors have noticed that asthma is more common among children in developed countries. Children in these countries tend to live in very clean, hygienic environments and are given antibiotics and vaccines at an earlier age than children who live in less developed countries. Thus, doctors think that perhaps childhood exposure to certain substances and infections may actually help children's immune system learn not to overreact to triggers. Doctors are not sure whether exposure to cigarette smoke increases children's risk of asthma.

Most children who are having an asthma attack and 90% of children who have been hospitalized for asthma have a viral infection (usually rhinovirus or the common cold). Children who have bronchiolitis (see Bronchiolitis) at an early age often wheeze with subsequent viral infections. The wheezing may at first be interpreted as asthma, but these children are no more likely than others to have asthma during adolescence.

Diet may be a risk factor. Children who do not consume enough of vitamins C and E and omega-3 fatty acids or who are obese may be at risk of asthma.

Symptoms

As the airways narrow in an asthma attack, the child develops difficulty breathing, chest tightness, and coughing, typically accompanied by wheezing. Wheezing is a high-pitched noise heard when the child breathes out (see Wheezing in Infants and Young Children).

Not all asthma attacks cause wheezing, however. Mild asthma, particularly in very young children, may result only in a cough. Some older children with mild asthma tend to cough only when exercising or when exposed to cold air. Also, children with extremely severe asthma may not wheeze because there is too little air flowing to make a noise.

In a severe attack, breathing becomes visibly difficult, wheezing usually becomes louder, the child breathes faster and with greater effort, and the ribs stand out when the child breathes in (inspiration). With very severe attacks, the child gasps for breath and sits upright, leaning forward. The skin is sweaty and pale or blue-tinged. Children who have frequent severe attacks sometimes have slowed growth, but their growth usually is similar to that of other children by adulthood.

Diagnosis

  • Wheezing and family history of asthma or allergies

  • Sometimes allergy testing

  • Sometimes pulmonary function tests

A doctor suspects asthma in children who have repeated episodes of wheezing, particularly when family members are known to have asthma or allergies. X-rays of the chest are rarely necessary for the diagnosis of asthma in children. X-rays are usually done only if doctors think that the child's symptoms might be caused by a different disorder, such as pneumonia. Doctors sometimes do allergy testing to help determine potential triggers.

Children with frequent wheezing episodes may be tested for other disorders, such as cystic fibrosis or gastroesophageal reflux. Older children sometimes undergo tests that are used to measure how well the lungs function (pulmonary function tests—see Pulmonary Function Testing (PFT)). In most children, however, lung function is normal between flare-ups.

Older children or adolescents known to have asthma often use a peak flow meter (a small handheld device that records how fast a person can blow out air—see Diagnosis of Lung Disorders:Lung volume and flow rate measurements) to measure the degree of airway narrowing. This device can be used at home. Doctors and parents can use this measurement to assess the child's condition during an attack and between attacks. X-rays are not done during an attack in children known to have asthma unless doctors suspect another disorder such as pneumonia or a collapsed lung.

Did You Know...

  • One speck of dust can contain 40,000 dust mites, which are major triggers of asthma.

Prognosis

Many children outgrow asthma. However, as many as 1 in 4 children either continue to have asthma attacks or the asthma symptoms resolve only to return (called relapse) when children are older. Children who have severe asthma are more likely to have asthma as adults. Other risk factors for persistence and relapse include female sex, smoking, development of asthma at a younger age, and sensitivity to household dust mites.

Although asthma causes a significant number of deaths each year, most of these are preventable with treatment. Thus, the prognosis is good for children who have access to treatment and who are able to follow their treatment plan.

Prevention

It is not yet known how to prevent a child with a family history of asthma from developing asthma. However, because there is evidence that children of mothers who smoked during pregnancy are more likely to have asthma, pregnant women should not smoke, particularly if there is a family history of asthma.

On the other hand, there are many things that can be done to prevent asthma symptoms or attacks in children who have asthma.

Asthma flare-ups often can be prevented by avoiding or trying to control whatever triggers a particular child's attacks. Children who have allergies should have the following items removed from their room:

  • Feather pillows

  • Carpets and rugs

  • Drapes

  • Upholstered furniture

  • Stuffed toys

  • Pets

  • Other potential sources of dust mites and allergens

Other ways to reduce allergens include

  • Using synthetic fiber pillows and impermeable mattress covers

  • Washing bed sheets, pillowcases, and blankets in hot water

  • Using dehumidifiers in basements and in other poorly aerated, damp rooms to reduce mold

  • Using steam to clean the home to reduce dust mite allergens

  • Cleaning the house and pest extermination to eliminate cockroach exposure

  • Eliminating smoking in the home

If a particular allergen cannot be avoided, a doctor may try to desensitize the child by using allergy shots, although the benefits of allergy shots for asthma are not well known.

Secondhand tobacco smoke often worsens symptoms in children with asthma, so it is important to eliminate smoking in areas where the child spends time.

Other triggers, such as strong odors, irritating fumes, cold temperatures, and high humidity, should also be avoided or controlled when possible.

Because exercise is so important for a child's development, doctors usually encourage children to maintain physical activities, exercise, and sports participation and use an asthma drug immediately before exercising if needed.

Treatment

  • For acute attacks, bronchodilators and sometimes corticosteroids

  • For chronic asthma, corticosteroids and possibly leukotriene modifiers, bronchodilators, and/or cromolyn

Treatment is given to resolve sudden (acute) attacks and sometimes to prevent attacks.

Children who have mild, very infrequent attacks usually take drugs only during an attack. Children who have more frequent or severe attacks also need to take drugs even when they are not having attacks. Different drugs are used depending on the frequency and severity of the attacks. Children with infrequent attacks that are not very severe usually use a low dose of an inhaled corticosteroid or a leukotriene modifier (montelukast or zafirlukast) every day to help prevent attacks. These drugs reduce inflammation by blocking the release of the chemical substances that inflame the airways.

Acute attacks (flare-ups)

Treatment of an acute attack consists of

  • Opening the airways (bronchodilation)

  • Stopping inflammation

A variety of inhaled drugs open the airways (bronchodilators—see Treating Attacks). Typical examples are albuterol and ipratropium. Doctors do not recommend using long-acting bronchodilators, such as salmeterol and formoterol, as the only treatment for children.

Older children and adolescents usually can take these drugs using a metered-dose inhaler. Children younger than 5 years (and some older children) are not capable of using a metered-dose inhaler correctly and should only use an inhaler with a spacer or holding chamber attached (see Figure: How to Use a Metered-Dose Inhaler).

Infants and very young children sometimes can use an inhaler and spacer if an infant-sized mask is attached.

Children who cannot use inhalers may receive inhaled drugs at home through a mask connected to a nebulizer (a small device that creates a mist of the drug by using compressed air). Inhalers and nebulizers are equally effective at delivering the drugs, but most parents find the inhaler and spacer much more efficient and easier to use.

Albuterol also can be taken by mouth, but this route is less effective than inhalation and usually is used only in infants who do not have a nebulizer. Children with moderately severe attacks also may be given corticosteroids by mouth or injection.

Children with very severe attacks are treated in the hospital with bronchodilators given in a nebulizer or an inhaler at least every 20 minutes initially. Sometimes doctors use injections of epinephrine or terbutaline (bronchodilators) in children with very severe attacks if inhaled drugs are not effective. Doctors usually give corticosteroids by vein to children having a severe attack.


Chronic asthma

Treatment of chronic asthma consists of

  • Taking corticosteroids daily and possibly other drugs that control inflammation

  • Using an inhaler before exercise

Infants and children under age 5 who need treatment more than 2 times a week, who have more persistent asthma, or those at risk of frequent or more severe attacks should receive daily anti-inflammatory treatment with inhaled corticosteroids. These children may also be given an additional drug such as a leukotriene modifier (montelukast or zafirlukast), a long-acting bronchodilator, or cromolyn. Drugs are increased or decreased over time to achieve optimal control of the child’s asthma symptoms and to prevent severe attacks. If these drugs do not prevent severe attacks, children may need to take corticosteroids by mouth. Children over age 5 and adolescents with asthma can be treated similarly to adults (see Treating Attacks).

Children who have attacks during exercise usually inhale a dose of bronchodilator just before exercising.

Children whose asthma is triggered by aspirin or other nonsteroidal anti-inflammatory drugs (NSAIDs) must avoid using these drugs. This reaction, however, is very uncommon in children. There is also evidence that taking acetaminophen (an alternative drug used to treat fever) during a viral infection increases the risk of a flare-up in children who have asthma. To decrease the risk of a flare-up, parents of children with asthma should limit the use of acetaminophen. Instead, an NSAID can be used unless the child is one of the rare individuals with aspirin sensitivity.

Because asthma is a long-term disorder with a variety of treatments, doctors work with parents and children to make sure they understand the disorder as well as possible. Adolescents and mature younger children should participate in developing their own asthma management plans and establishing their own goals for therapy to improve adherence to treatment. Parents and children should learn how to determine the severity of an attack, when to use drugs and a peak flow meter, when to call the doctor, and when to go to the hospital.

Parents and doctors should inform school nurses, child care providers, and others of the child's disorder and the drugs being used. Some children may be permitted to use inhalers in school as needed, and others must be supervised by the school nurse.


Resources In This Article

Drugs Mentioned In This Article

  • Generic Name
    Select Brand Names
  • No US brand name
  • ACCOLATE
  • CROLOM
  • SINGULAIR
  • ADRENALIN
  • SEREVENT
  • FORADIL AEROLIZER, PERFOROMIST
  • ATROVENT
  • PROVENTIL-HFA, VENTOLIN-HFA
  • TYLENOL