Asthma Tests
The best way to find out if you have asthma is through Pulmonary Function Testing (PFT). This is a test, done at a doctor's office, which measures how well your breathing passages can move air in and out. The test is done by blowing forcefully into a mouthpiece that is connected to a computer. The computer measures the air moving through the mouthpiece and will show whether your breathing is normal for your age and height.
Further testing may also be necessary. Usually after completing the first PFT, a reversibility test is performed. This test is done by inhaling a medication known as a bronchodilator (reliever), and twenty minutes later another Pulmonary Function Test is performed to see if breathing improves. If breathing improves at least 12%, this confirms a diagnosis of asthma. Some patients may have asthma and not improve. For this reason and others, doctors may recommend another test called a Methacholine Challenge.
A Methacholine Challenge Test is done by having a suspected asthmatic patient inhale increasing doses of Methacholine. Methacholine is a liquid medication that in an asthmatic only, will cause mild asthma symptoms and a decrease in the patient's pulmonary function test measurements. If breathing worsens by at least 20%, this confirms a diagnosis of asthma. If breathing does not worsen, then the patient is considered not to have asthma. This is a very useful and safe test to positively identify asthma in most cases.
No, a chest x-ray does not always show signs of asthma. It will help identify other lung problems that might be causing your breathing problems.
A Pulmonary Function Test shows the severity of asthma.
- Studies have shown that asthmatics often under-report their symptoms because they have become so used to difficult breathing. Therefore, asthmatics may not be receiving the proper amount of medication to fully control their asthma.
- The severity or even presence of asthma is difficult to establish because it is not always active at the time of the physician's exam.
- It is critical for the health care provider to monitor pulmonary function tests to make sure the correct amount of medication is being taken so that permanent lung damage does not occur. All asthmatics should have pulmonary function testing done yearly, routinely and more often if asthma is unstable.
- The NIH (National Institute of Health) has classified the severity of asthma in their recently published document "Guidelines for the Diagnosis and Management of Asthma" NIH Publication No. 97-4051, April 1997. There are four categories of asthma; mild intermittent, mild persistent, moderate persistent, and severe persistent. These categories are based on your pulmonary function test and your symptoms. The medicine you need depends on the category of your asthma.
Swelling and inflammation of the lungs, over time, if not controlled with medications will cause scarring in the lungs and make breathing more difficult and medications less effective. This has been shown to happen in even less than a year if asthma is not treated properly.
