Asthma in Children and Adolescents

Description

Diagnosis

The doctor will seriously consider a diagnosis of asthma if the 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 the following:

• 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).

• 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.

Pulmonary Function Tests

If symptoms and a patient's history are indicative of asthma, the physician 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 physician will determine several values:

1. Vital capacity (VC), which is the maximum volume of air that can be inhaled or exhaled.

2. 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.

3. Forced expiratory volume (FEV1), which is the maximum volume of air expired in one second.

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

• If measurements fall, then the physician typically asks the patient to inhale a bronchodilator. This is a drug that is used in asthma to open the air passages. The measurements are taken again. If the measurements are more normal, than 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 the doctor still suspects asthma, he or she may perform a challenge test. In this case a specific drug (histamine or methacholine) is administered that usually increases airway resistance only when asthma is present. The challenge test may be quite useful in ruling out occupational asthma. It is not always accurate, particularly in asthmatic patients whose only symptom is persistent coughing.

Another method for inducing airway resistance is to administer cold air. This test is very accurate for ruling out asthma, but it is not sensitive enough to accurately identify adults who actually are asthmatic.

Allergy Tests

The patient may be given skin or blood allergy tests, particularly if a specific allergen or occupational agent 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 obtained 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 patients sputum for eosinophils (white blood cells that in high levels are associated with severe allergic asthma). One 2002 study suggested that asthma might be effectively managed by using treatment goals based on achieving a normal eosinophil counts.