Determining Baseline Respiratory Duty Cycles in Subjects With and Without Airway Hyperresponsiveness

At least fifteen subjects with airway hyper‐responsiveness and fifteen without airway hyper‐responsiveness will be recruited to participate in this randomized, crossover study. Subjects will complete 2 methacholine challenges at least 24 hours apart. One methacholine challenge will entail the volumetric method using a vibrating mesh nebulizer. The second methacholine challenge will be performed identically except that the nebulizer will be fitted onto an ultrasonic nebulizer so as to measure the inspiratory duty cycle throughout the bronchoprovocation challenge.