Asthma in Children

Approximately 17.3 million Americans have asthma. The cost of illness related to asthma is around $6.2 billion per year in the United States. Each year, an estimated 1.81 million people with asthma require treatment in the emergency department with approximately 500,000 hospitalizations. Children younger than the age of 18 years account for 47.8% of the emergency department visits and 34.6% of the hospitalizations due to asthma exacerbations. The magnitude of the impacts of asthma in children is illustrated by the fact that asthma accounts for more hospitalizations in children than any other chronic illness. Moreover, asthma causes children and adolescents to miss school and causes parents to miss days at work. As might be expected asthma also accounts for more school absences than any other chronic illness.

Asthma is a disorder caused by inflammation in the airways (called bronchi) that lead to the lungs. This inflammation causes airways to tighten and narrow, which blocks air from flowing freely into the lungs, making it hard to breathe. Symptoms include wheezing, breathlessness, chest tightness, and cough, particularly at night or after exercise/activity. The inflammation may be completely or partially reversed with or without medicines.

Inflammation of the airways is linked to bronchial hyperresponsiveness, which means that the airways leading to the lungs can narrow when they are exposed to anything to which they are sensitive, making it hard to breathe. All children with asthma have airways that are overly sensitive, or hyperreactive, to certain asthma triggers. Things that trigger asthma differ from person to person. Some common triggers are exercise, allergies, viral infections, and smoke. When a person with asthma is exposed to a trigger, their sensitive airways become inflamed, swell up, and fill with mucus. In addition, the muscles lining the swollen airways tighten and constrict, making them even more narrowed and blocked (obstructed).

So an asthma flare is caused by 3 important changes in the airways that make breathing more difficult:

• Inflammation of the airways
  
  
• Excess mucus that results in congestion and mucus "plugs" that get caught in the narrowed airways
  
  
• Bronchoconstriction (bands of muscle lining the airways tighten up)

Many children with asthma can breathe normally for weeks or months between flares. When flares do occur, they often seem to happen without warning. Actually, a flare usually develops over time, involving a complicated process of increasing airway obstruction.

• Wheezing
  
  
  • Wheezing is when the air flowing into the lungs makes a high-pitched whistling sound.
    
    
  • Mild wheezing occurs only at the end of a breath when the child is breathing out (expiration or exhalation). More severe wheezing is heard during the whole exhaled breath. Children with even more severe asthma can also have wheezing while they breathe in (inspiration or inhalation). However, during a most extreme asthma attack, wheezing may be absent because almost no air is passing through the airways.
    
    
  • Asthma can occur without wheezing, so wheezing is not necessary for the diagnosis of asthma. Also, wheezing can be associated with other lung disorders, such as cystic fibrosis.
    
    
  • In asthma related to exercise (exercise-induced asthma) or asthma that occurs at night (nocturnal asthma), wheezing may be present only after exercise or during the night.
  
  
• Coughing: Cough may be the only symptom of asthma, especially in cases of exercise-induced or nocturnal asthma. Cough due to nocturnal asthma (night time asthma) usually occurs during early hours of morning, such as 1 am to 4 am. Usually, the child doesn’t cough anything up so there is no phlegm or mucus. Also, coughing may occur with wheezing.
  
  
• Chest tightness: The child may feel like the chest is tight or won’t expand when breathing in, or there may be pain in the chest with or without other symptoms of asthma, especially in exercise-induced or nocturnal asthma.
  
  
• Other symptoms: Infants or young children may have a history of coughs or lung infections (bronchitis) or pneumonia. Children with asthma may get coughs every time they get a cold. Most children with chronic or recurrent bronchitis have asthma.
  
  

• Symptoms during a mild episode: Children may be out of breath after a physical activity, such as walking. They can talk in sentences and lie down, and they may be restless. The feeding may be with interruption, therefore, the infant takes longer to finish the feed.
  
  
• Symptoms during a moderately severe episode: Children are out of breath while talking. Infants have a softer shorter cry, and feeding is difficult. There is feeding with interruption and child may not be able to finish the usual quantity of the feed.
  
  
• Symptoms during a severe episode: Children are out of breath while resting, they sit upright, they talk in words (not sentences), and they are usually restless. Infants are not interested in feeding and are restless and out of breath. Infant may try to start feeding but can not sustain feeding due to breathlessness. 
  
  
• Symptoms indicating that breathing will stop: In addition to the symptoms already described, the child is sleepy and confused. However, adolescents may not have these symptoms until they actually stop breathing. The infant may not be interested in feeding.
  
  

Diagnosing asthma can be difficult and time-consuming because different children with asthma can have very different patterns of symptoms. For example, some kids cough at night but seem fine during the day, while others seem to get frequent chest colds that don't go away.

To establish a diagnosis of asthma, a doctor rules out every other possible cause of a child's symptoms. The doctor asks questions about the family's asthma and allergy history, performs a physical exam, and possibly orders laboratory tests (see Tests Used to Diagnose Asthma). Be sure to provide the doctor with as many details as possible, no matter how unrelated they might seem. In particular, keep track of and report the following:

• Symptoms: How severe are the attacks, when and where do they occur, how often do they occur, how long do they last, and how do they go away?
  
  
• Allergies: Does the child or anyone else in the family have any history of allergies?
  
  
• Illnesses: How often does the child get a cold, how severe are the colds, and how long do they last?
  
  
• Triggers: Has the child been exposed to irritants and allergens, has the child experienced any recent life changes or stressful events, and do any other things seem to lead to a flare?

The criteria for a diagnosis of asthma are:

• Airflow into the lungs is reduced periodically (due to narrowed airways).
  
  
• The symptoms of reduced airflow are at least partially reversible.
  
  
• Other diseases and conditions are ruled out.
  
  

The severity of asthma is classified based on how often the symptoms occur and how bad they are, including symptoms that happen at night, the characteristics of episodes, and lung function. These classifications do not always work well in children because lung function is difficult to measure in younger children. Also, children often have asthma that is triggered by infections, and this kind of asthma does not fit into any category. A child's symptoms can be categorized into one of four main categories of asthma, each with different characteristics and requiring different treatment approaches.

• Mild intermittent asthma: Brief episodes of wheezing, coughing, or shortness of breath that occur no more than twice a week is called mild intermittent asthma. Children rarely have symptoms between episodes (maybe just one or two flare-ups per month involving mild symptoms at night). Mild asthma should never be ignored because, even between flares, airways are inflamed.
  
  
• Mild persistent asthma: Episodes of wheezing, coughing, or shortness of breath that occur more than twice a week but less than once a day is called mild persistent asthma. Symptoms usually occur at least twice a month at night and may affect normal physical activity.  
  
  
• Moderate persistent asthma: Symptoms occurring everyday and requiring medication everyday is called moderate persistent asthma. Nighttime symptoms occur more than once a week. Episodes of wheezing, coughing, or shortness of breath occur more than twice a week and may last for several days. These symptoms affect normal physical activity.
  
  
• Severe persistent asthma: Children with severe persistent asthma have symptoms continuously. Episodes of wheezing, coughing, or shortness of breath are frequent and may require emergency treatment and even hospitalization. Many children with severe persistent asthma have frequent symptoms at night and can handle only limited physical activity.

Asthma in children usually has many causes, or triggers. These triggers may change as a child ages. A child’s reaction to a trigger may also change with treatment. Viral infections can increase the likelihood of an asthma attack. Common triggers of asthma include the following:

• Respiratory infections: These are usually viral infections. In some patients, other infections with fungi, bacteria, or parasites might be responsible.

• Allergens (see below for more information): An allergen is anything in a child’s environment that causes an allergic reaction. Allergens can be foods, pet dander, molds, fungi, roach allergens, or dust mites. Allergens can also be seasonal outdoor allergens (eg, mold spores, pollens, grass, trees).

• Irritants: When an irritating substance is inhaled, it can cause an asthmatic response. Tobacco smoke, cold air, chemicals, perfumes, paint odors, hair sprays, and air pollutants are irritants that can cause inflammation in the lungs and result in asthma symptoms.

• Weather changes: Asthma attacks can be related to changes in the weather or the quality of the air. Weather factors such as humidity and temperature can affect how many allergens and irritants are being carried in the air and inhaled by your child.

• Exercise (see below for more information): Exercise can trigger asthma. Exactly how exercise triggers asthma is unclear, but it may have to do with heat and water loss and temperature changes as a child heats up during exercise and cools down after exercise.

• Emotional factors: Some children can have asthma attacks that are caused or made worse by emotional upsets.

• Gastroesophageal reflux (GER): GER is more commonly known as heartburn. GER is related to asthma because the presence of small amounts of stomach acid outside of the stomach (in the esophagus) can irritate the airways.

• Inflammation of the upper airways (including the nasal passages and the sinuses): Inflammation in the upper airways, which can be caused by allergies, sinus infections, or lung (respiratory) infections, must be treated before asthmatic symptoms can be completely controlled.

• Nocturnal asthma: Nighttime asthma is probably caused by multiple factors. Some factors may be related to how breathing changes during sleep, exposure to allergens during and before sleep, or body position during sleep.

Allergy-related asthma

Although an estimated 75-85% of people with asthma have some type of allergy, the allergy isn’t always the primary cause of asthma. Even if allergies are not your child's primary triggers for asthma (asthma may be triggered by colds, the flu, or exercise for example), allergies can still make symptoms worse.

Children inherit the tendency to have allergies from their parents. People with allergies make too much "allergic antibody," which is called immunoglobulin E (IgE). The IgE antibody recognizes small quantities of allergens and causes allergic reactions to these usually harmless particles. Allergic reactions occur when IgE antibody triggers certain cells (called mast cells) to release a substance called histamine. Histamine occurs in the body naturally, but it is released inappropriately and at too high an amount in people with allergies. The released histamine is what causes the sneezing, runny nose, and watery eyes associated with some allergies. In a child with asthma, histamine can also trigger asthma symptoms and flares.

An allergist can usually identify any allergies a child may have. Once identified, the best treatment is to avoid exposure to allergens whenever possible. When avoidance isn't possible, antihistamine medications may be prescribed to block the release of histamine in the body and stop allergy symptoms. Nasal steroids can be prescribed to block allergic inflammation in the nose. In some cases, an allergist can prescribe immunotherapy, which is a series of allergy shots that gradually make the body unresponsive to specific allergens.

Exercise-induced asthma

Children who have exercise-induced asthma develop asthma symptoms after vigorous activity, such as running, swimming, or biking. For some children, exercise is the only thing that triggers asthma; for other children, exercise as well as other factors trigger symptoms. Young children with exercise-induced asthma may have subtle symptoms such as coughing or undue breathlessness after physical activity during play. Not every type or intensity of exercise causes symptoms in children with exercise-induced asthma. With the right medicine, most children with exercise-induced asthma can play sports like any other child. In fact, over 10% of Olympic athletes have exercise-induced asthma they've learned to control.

• Pulmonary function tests (PFTs) are used to test lung performance, but in children younger than 5 years, the results are typically not reliable.
  
  
  • An asthma specialist, such as a pulmonologist or allergist, can perform breathing tests using a spirometer, a machine that measures the amount of air that flows in and out of the lungs. It can detect blockage if the airflow is lower than normal, and it can also detect if the airway obstruction is involving only small airways or larger airways too. The doctor may take a spirometer reading, give the child an inhaled medication that opens the airways (bronchodilator therapy), and then take another reading to see if breathing improves with medication. If medication reverses airway obstruction (blockage), as indicated by improved airflow, then there's a strong possibility that the child has asthma. A peak flow meter is a simple device used to measure the peak flow of air coming out of the lungs when a child is asked to blow air into it. The peak flow meter readings are different than spirometer readings. However, a child can have a normal peak airflow and still have airway obstruction that is not detected with spirometry. The peak flow can have a normal value while the values for other parameters, such as forced expiratory volume in 1 second (FEV1) or forced expiratory flow during mid-portion of forced vital capacity (FEF25-75), are reduced suggesting airway obstruction. Thus, spirometry is more informative compared to only peak flow meter readings.
    
    
  • Another test is called plethysmography. This test measures lung capacity and lung volumes (the amount of air the lung can hold). Patients with chronic persistent asthma may have lungs that are over-inflated; over-inflation is diagnosed when a patient has increased lung capacity detected by this test.
  
  
• Other tests called bronchial provocation tests are performed only in specialized laboratories by specially trained personnel. These tests involve exposing patients to irritating substances and measuring the effect on lung function.
  
  
• Patients with a history of exercise-induced symptoms (eg, cough, wheeze, chest tightness, pain) can undergo an exercise challenge test. This test is usually done in children older than 6 years. The baseline (or usual) lung function for the child is measured (using spirometry) while the child is sitting still. Then the child exercises, usually by riding a stationary bicycle or walking fast on a treadmill. When the child’s heart is beating faster from the exercise, the lung function is measured again. Measurements are taken immediately after the exercise and at 3, 5, 10, 15, and 20 minutes after the first measurement. This test detects decreased lung function caused by exercise. 
  
  
• Your doctor may take a chest x-ray (radiograph) if the asthma isn’t helped by the usual treatments.
  
  
• Allergy testing can be used to identify factors your child is allergic to because these factors might contribute to asthma. Once identified, environmental factors (eg, dust mites, cockroaches, molds, animal dander) and outdoor factors (eg, pollen, grass, trees, molds) may be controlled or avoided to reduce asthma symptoms.
  
  
• Ask your doctor for more information on these and other tests.
  
  

The goals of asthma therapy are to prevent your child from having chronic and troublesome symptoms, to maintain your child’s lung function as close to normal as possible, to allow your child to maintain normal physical activity levels (including exercise), to prevent recurrent asthma attacks and to reduce the need for emergency department visits or hospitalizations, and to provide medicines to your child that give the best results with the fewest side effects. See Understanding Asthma Medications.

Medicines that are available fall into two general categories. One category includes medications that are meant to control asthma in the long term and are used daily to prevent asthma attacks (controller medications). These can include inhaled corticosteroids, inhaled cromolyn or nedocromil, long-acting bronchodilators, theophylline, and leukotriene antagonists. The other category is medications that provide instant relief from symptoms (rescue medications). These include short-acting bronchodilators and systemic corticosteroids. Inhaled ipratropium may be used in addition to inhaled bronchodilators following asthma attacks or when asthma worsens.

In general, doctors start with a high level of therapy following an asthma attack and then decrease treatment to the lowest possible level that still prevents asthma attacks and allows your child to have a normal life. Every child needs to follow a customized asthma management plan to control asthma symptoms. The severity of a child's asthma can both worsen and improve over time, so the type (category) of your child's asthma can change, which means different treatment can be required over time. Treatment should be reviewed every 1-6 months, and the choices for long- and short-term therapy are based on how severe the asthma is.

Talk to your doctor about the various medications available to treat asthma.