Sensory-Mechanical Responses to Eucapneic Voluntary Hyperventilation and Mannitol

The objectives of this study are to determine the sensory-mechanical responses to Eucapneic Voluntary Hyperventilation (EVH) and Mannitol in individuals with cough variant asthma (CVA) and methacholine-induced cough with normal airway sensitivity (COUGH) and compare these responses to a control group of healthy individuals without asthma or chronic cough. We hypothesize: 1. EVH and Mannitol cause dyspnea, cough, small airway obstruction with resultant dynamic hyperinflation, gas trapping and autoPEEP in individuals with CVA and COUGH, but not healthy controls. 2. The sensory-mechanical responses to both hyperosmolar challenges (EVH and Mannitol) are comparable within groups (CVA, COUGH and healthy controls).