Asthma Basics
May 26, 2004, KidsHealth.org

Take a long, deep breath - right now. Inhale slowly, until your lungs can't hold anymore . . . now let the air out gradually . . . ahhh. Breathing feels so natural that it's easy to take for granted, isn't it? Normally, the air you breathe travels effortlessly through your nose and mouth, down the trachea (also called the "windpipe"), through the bronchial tubes into the lungs, and finally to tiny clusters of air sacs, called alveoli. Here, oxygen is exchanged for carbon dioxide in your blood.

Now try something different: run in place for three minutes. Then place a straw in your mouth, close your lips around it, and try to breathe in and out only through the straw. Not so easy anymore, is it? Now, narrow the straw by pinching it in the middle. Even more difficult to breathe? That's what it feels like when a child tries to breathe during an asthma flare (commonly called an "attack"). During a flare, the airways narrow and become obstructed, making it difficult for air to move through them. Asthma can be very scary (and when not controlled, it can be life-threatening).

Over 15 million people have asthma in the U.S. Did you know it's the number- one reason for kids chronically missing school? And asthma flares are the most common reason for pediatric emergency room visits due to a chronic illness. Some kids have only mild, occasional symptoms or only show symptoms after exercising. Others have severe asthma that, left untreated, can dramatically limit how active they are and cause changes in lung function.

But thanks to new medications and treatment strategies, a child with asthma no longer needs to sit on the sidelines, and parents no longer need to worry incessantly about their child's well-being. With patient education and the right asthma management plan, today's families can learn to control symptoms and flares more independently, allowing kids and parents to do just about anything they want.

Causes and Descriptions of Asthma Flares
Asthma is a chronic inflammatory lung disease that causes airways to tighten and narrow. Anyone can have asthma, including infants and adolescents. The tendency to develop asthma is often inherited.

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.

All children with asthma have airways that are overly sensitive, or hyperreactive, to certain asthma triggers. Things that trigger asthma flares differ from person to person. Some common triggers are exercise, allergies, viral infections, and smoke. The sensitive airway linings react to trigger exposure by becoming inflamed, swollen, and filled with mucus. The muscles lining the swollen airways tighten and constrict, making them even more narrowed and obstructed.

So an asthma flare is caused by three important changes in the airways:
o inflammation of the airways
o excess mucus that results in congestion and mucus "plugs" that get caught in the narrowed airways
o bronchoconstriction: bands of smooth muscle lining the airways tighten up

Together, the inflammation, excess mucus, and bronchoconstriction narrow the airways and make it difficult to move air through (like breathing through a straw. During an asthma flare, kids may experience coughing, wheezing (a breezy whistling sound in the chest when breathing), chest tightness, increased heart rate, perspiration, and shortness of breath.

How Is Asthma Diagnosed?
Diagnosing asthma can be tricky and time-consuming because different children with asthma can have very different patterns of symptoms. For example, some kids cough constantly at night but seem fine during the day, while others seem to get frequent chest colds that don't go away. It's not uncommon for kids to have symptoms like these for months before being seen by a doctor.

When considering a diagnosis of asthma, a doctor rules out every other possible cause of a child's symptoms. He or she asks questions about the family's asthma and allergy history, performs a physical exam, and possibly orders laboratory tests such as chest x-rays, blood tests, and allergy skin tests. During this process, parents must provide the doctor with as many details as possible, no matter how unrelated they might seem, about things such as:
o symptoms: how severe they are, when and where they occur, how frequently they occur, how long they last, and how they go away
o allergies: the child's and the family's allergy history
o illnesses: how often the child gets colds, how severe they are, and how long they last
o triggers: exposures to irritants and allergens, recent life changes or stressful events, or other things that seem to lead to a flare

This information helps the doctor understand a child's pattern of symptoms, which can then be compared to the characteristics of different categories of asthma.

An asthma specialist, such as a pulmonologist or allergist, can perform breathing tests using a spirometer, a machine that does a detailed analysis of a child's airflow through both large and small airways. A spirometer can also be used to see if the child's breathing problems can be reversed with medication, a primary characteristic of asthma. The doctor may take a spirometer reading, give the child an inhaled medication that opens the airways, and then take another reading to see if breathing improves with medication. If medication reverses airway narrowing significantly, as indicated by improved airflow, then there's a strong possibility that the child has asthma.

Sometimes additional specialized tests are performed, such as allergy skin testing, complete pulmonary function studies, or exercise challenge (when the doctor induces an asthma flare and then measures changes in breathing). These tests can help verify that a child has asthma, and not a condition that just seems like asthma.

Once the child is diagnosed, the family can start learning how to control asthma - so it no longer controls the family. At home, a peak flow meter - a hand-held tool that measures breathing ability - can be used. When peak flow readings drop, it's a sign of increasing airway inflammation.

Exercise-induced asthma
Kids who have exercise-induced asthma (EIA) develop asthma symptoms after vigorous activity, such as running, swimming, or biking. Some kids with EIA develop symptoms only after physical exertion, while others have additional asthma triggers. With the proper medications, most kids with EIA can play sports like any other child. In fact, over 10% of Olympic athletes have exercise-induced asthma they've learned to control.

Usually, a doctor can diagnose EIA after taking a history alone. But sometimes further tests, including an exercise challenge in a pulmonary function laboratory, are needed to confirm the diagnosis. The doctor may want to target a child's tolerance for a particular exercise, as not every type or intensity of exercise affects kids with EIA the same way.

If exercise is a child's only asthma trigger, the doctor may prescribe a medication that the child takes before exercising to prevent airways from tightening up. Of course, even after premedicating, asthma flares can still occur. Parents (or older children) must carry the proper "rescue" medication to all games and activities, and the child's school nurse, coaches, scout leaders, and teachers must be informed of the child's asthma, especially so the child will be able to take the medication at school as needed.

Allergy-triggered asthma
Not every child with asthma has allergy-triggered asthma, but an estimated 75-85% of people with asthma have some type of allergy. Even if a child's primary triggers are colds and flu (the most common triggers for children) or exercise, allergies can sometimes play a minor role in aggravating the condition.

How do allergies cause flares in children with asthma? Children inherit the tendency to have allergies from their parents, who pass along the genetic material to make greater than normal amounts of the "allergic antibody," immunoglobulin E (IgE). The IgE antibody recognizes small quantities of allergens such as dust mites and molds and is responsible for generating allergic reactions to these usually harmless particles. (IgE may also have a role in fighting off parasitic infections.)

The IgE antibodies sit on the surfaces of mast cells, which are found in connective tissue throughout the body. When allergens enter the body, they attach to the IgE antibody, which triggers the mast cells to release histamine, a naturally occurring chemical, to defend against the allergen "invader." The released histamine is what causes the familiar sneezing, runny nose, and watery eyes associated with some allergies - ways the body attempts to rid itself of the invading allergen. 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. Environmental control measures for the home can help reduce a child's exposure to allergens. When avoidance isn't possible, antihistamine medications may be prescribed to block the release of histamine in the body. Nasal steroids may be given to block allergic inflammation in the nose. In some cases, an allergist can prescribe immunotherapy, a series of allergy shots that gradually make the body unresponsive to specific allergens.

Categories of asthma
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: A child who has brief episodes of wheezing, coughing, or shortness of breath occurring no more than twice a week is said to have mild intermittent asthma. The child rarely has symptoms between episodes, with the exception of one or two instances per month of mild symptoms at night. Mild asthma should never be ignored; even between flares, airway inflammation exists. The doctor will design an asthma management plan to treat mild symptoms.

Mild persistent asthma: Children with episodes of wheezing, coughing, or shortness of breath that occur more than twice a week but less than once a day are said to have mild persistent asthma. Symptoms usually occur at least twice a month at night and may affect normal physical activity.

Moderate persistent asthma: Children with moderate persistent asthma have daily symptoms and require daily medication. 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. They tend to have frequent episodes of wheezing, coughing, or shortness of breath that 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.

Every child needs to follow a custom asthma management plan to control his symptoms. The severity of a child's asthma can both worsen and improve over time, placing him in a new asthma category that requires different treatment.