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 often be prevented by avoiding triggers.
- Treatment includes bronchodilators and inhaled corticosteroids.
(See also Asthma in adults.)
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 is one of the most common chronic diseases of childhood, affecting more than 6 million children in the United States. It occurs more frequently in boys before puberty and in girls after puberty. Asthma has become much more common in recent decades. Doctors are not sure why this is so. 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 a 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.
The 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
- Stimulate the muscle cells in the walls of the airways to contract
- Increase mucus production in 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. 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.
Common Asthma Triggers
Dust or house mites, molds, outdoor pollen, animal dander, cockroach feces, and feathers
Particularly exercise in cold or dry air
Firsthand and secondhand tobacco smoke, perfumes, wood smoke, cleaning products, scented candles, outdoor air pollution, strong odors, and irritating fumes
Viral respiratory infections*
Emotions (such as anxiety, anger, and excitement), aspirin or other nonsteroidal anti-inflammatory drugs (NSAIDs), and gastroesophageal reflux
*Viral infections are the most common triggers in children.
Risk Factors for Asthma
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 exposed to fewer infectious diseases 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.
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 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.
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.
Children and adolescents should use a metered-dose inhaler with a spacer or valve-holding chamber (see Figure: How to Use a Metered-Dose Inhaler). The spacer optimizes delivery of the drug to the lungs and minimizes the chance of side effects.
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 convenient and easier to use.
Albuterol also can be taken by mouth, but this route is less effective and may have more side effects than inhalation and usually is used only in infants who do not have a nebulizer and are too young to use an inhaler. 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.
Treatment of chronic asthma consists of
- Taking inhaled 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 (always mixed with an inhaled corticosteroid in a combination inhaler), 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 Asthma 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.
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.
How to Use a Metered-Dose Inhaler
Drugs Mentioned In This Article
|Generic Name||Select Brand Names|
|terbutaline||No US brand name|
|formoterol||FORADIL AEROLIZER, PERFOROMIST|
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