Bronchial provocation (challenge) testing is the most commonly used and accepted approach for evaluationg airway hyperresponsiveness (twitchy airways).
A common nonspecific challenge agent used for bronchial provocation is aerosolized methacholine. In this test, the patient inhales an aerosol of one or more concentrations methacholine. Results of pulmoary function tests (e.g., spirometry and specfic conductance) performed before and after the inhalations are used to measure response.