The Asthma Corner
Before discussing the actual "asthma test", it is important to know that most children who develop asthma do so in the first few years of life. The diagnosis is made by the history of symptoms. It is generally agreed that if a child has repetitive episodes of shortness of breath, and/or wheezing and/or cough, and has no other lung problem, the diagnosis of asthma can be made.
Testing for asthma is not that simple. The only test that can prove that a child has asthma is the "provocation or challenge test" where children breathe in a substance known to close down the bronchi or airway tubes. Ordinarily, at a certain dose, everyone will react to this medication (histamine or metacholine) and their bronchi will close down or constrict, which can be measured by the rate at which one breathes out. Persons with asthma react to lower doses of the provoking substance. In other words, their airways are more sensitive.
When A Child Can Be Tested For Asthma?
This is a very common question, as parents want to make sure, and rightfully so, that their child is not on medications unnecessarily. This type of test requires that a child be fully cooperative and can breathe out as hard and fast as he/she can repetitively and on demand. In general, only children older than eight years of age can undergo this "Pulmonary Challenge", as younger children cannot perform this test.
Peak Flow Meters
The "challenge or provocation test" should not be confused with the breathing tests(spirometry) that are performed at many clinics and offices or even with peak flow meters. These tests, again, only possible in school age or older children, determine how quickly a child can breathe out - a measure of airway blockage at that time - and are used to monitor a child's symptoms on a daily basis. A normal test in this instance neither confirms nor eliminates the diagnosis of asthma.
Another evaluation that parents inquire about is a chest x-ray, which is not useful in confirming the diagnosis of asthma. A chest x-ray is generally used, depending on the individual situation, to make sure there are no other problems that can cause chronic respiratory symptoms. Given that asthma testing is not possible in the majority of young asthmatics, the diagnosis, the follow-up treatment and decisions to modify treatment, are based solely on the symptoms. Any other tests performed depend on the individual situation and are used to exclude or rule out other conditions that may mimic or be confused with asthma symptoms.
Daily Asthma Diary
This is the best way to document a child's asthmatic symptoms and progress. Parents should record the following: the presence of day or night-time symptoms, dates of hospitalizations or emergency room visits, peak flow measurements in older children, and very importantly, the need for bronchodilator use. This last measurement is a very good indication of the degree of asthma control. In general, asthmatic children requiring less than five bronchodilator doses per week are usually considered to be well controlled. Click here for an example of an asthma diary.