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Pulmonary Function Lab

Diagnosing Asthma

Your doctor may order a bronchospasm evaluation.

Diagnosing Asthma The Breathing Tests Pulmonary Function Laboratory

How can Christiana Care Diagnose Asthma?

If you show signs of asthma, your doctor may order a bronchospasm evaluation. During the evaluation, you will perform breathing tests that gauge your reaction to medications that may affect airway function or determine if your breathing is affected by exercise.

When you take these tests, you will breathe through a mouthpiece into a spirometer. A spirometer is a testing device that measures your airflow. A respiratory therapist will explain how you should breathe into the spirometer and coach you through the maneuver. You will perform the maneuver several times to ensure an accurate and reliable test result.

The Breathing Tests

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.