BRONCHIAL TRIGGER TESTS FOR ASTHMA DIAGNOSIS

There are three kinds of “provocation” or trigger tests that measure breathing to diagnose asthma: the irritant challenge, the exercise challenge, and the methacholine challenge. Before and after each test, lung function is measured with a spirometer. The irritant challenge exposes you to a substance suspected of triggering asthma. The exercise challenge monitors changes in heartrate and oxygen levels while you run on a treadmill. The methacholine challenge uses the drug to constrict the airways and induce an asthmatic response. People with asthma respond to a low dose of methacholine, while non-asthma people respond to higher doses. If you have asthma symptoms but the lower dose doesn’t trigger a response, you may have a different lung condition.

P.S. Methacholine is in a class of drugs called cholinergic receptor agonists. It uses muscarinic receptors in the lungs to induce bronchoconstriction (tightening of the airways).

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