Diagnosing Asthma

This test will determine how well air travels through the airways of your lung with and without a bronchodilator. A bronchodilator is a type of medication that helps loosen muscles that constrict your airways and helps clear mucus that interferes with breathing. You will take the test twice. First, you will breathe into a testing device without the medication. Then you will inhale the bronchodilator and breathe into the device again. Your doctor will compare the results to help make a diagnosis. This test takes about 30 minutes.

This test will measure whether your airways react when you inhale methacholine. Methacholine is a medication that can cause the airways of your lungs to begin to constrict and affect your ability to breathe. You will begin the test by breathing into a testing device to establish a baseline for the flow and volume of air traveling through your airways when you exhale. You then will inhale the methacholine and breathe into the testing device again. Depending on the results, you may continue to inhale increasing amounts of methacholine until the amount of air you breathe out in the first second begins to drop or you use all of the medication. The test helps to determine if you have bronchial asthma. It takes about 90 minutes.

This test will determine if exercise causes your breathing difficulties. You will begin this test by breathing into the spirometer to measure how much and how quickly air travels through your airways. You then will exercise on a treadmill or stationary bike while breathing very cold air. A spirometer reading will be taken again to measure how your airways react after the exercise. A positive test result suggests exercised-induced asthma. This test takes about 90 minutes.