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

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

The study investigates the inspiratory duty cycle in subjects with and without airway hyper-responsiveness both at rest and during a bronchoprovocation challenge. The primary goal is to determine an average inspiratory duty cycle for standard use in the calculation of bronchoprovocation test results.

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.

Inclusion Criteria:

• Must be 18 years of age or older
• Participants with airway hyper-responsiveness must have a positive methacholine challenge
• Forced expiratory volume (FEV1) of at least 65% of predicted (based on age, height, and gender)
• Participants without airway hyper-responsiveness must have a negative methacholine challenge
• All participants must avoid strenuous exercise on test days
• No short-acting beta-2 agonist use within 6 hours of study visit

Exclusion Criteria:

• Participants without known airway hyper-responsiveness cannot have a current or historical respiratory condition (e.g. asthma, allergic rhinitis)
• Participants cannot be taking long-acting bronchodilators
• Participants cannot be pregnant or lactating
• Participants cannot have cardiovascular problems