Asthma is a chronic respiratory condition characterized by eosinophilic airway inflammation. Individuals with classic asthma experience paroxysmal symptoms including cough, wheeze, shortness of breath and chest tightness. Cough variant asthma (CVA) is asthma in which chronic cough (cough lasting eight weeks or more) is the sole or predominant symptom of asthma. The pathophysiologic mechanisms which differentiate asthma, CVA, and eosinophilic bronchitis without asthma are not fully understood. We have recently identified individuals with chronic cough who cough during methacholine but have normal airway sensitivity (ie. do not have asthma or CVA) (COUGH) and may or may not have eosinophilic bronchitis. The purpose of this research is to further explore the pathophysiologic basis for cough in these conditions using two 'indirect' inhalation challenge tests: eucapneic voluntary hyperventilation (EVH) and Mannitol), which induce osmotic and/or temperature changes in airway. Specifically, this study will collect preliminary data on the sensory-mechanical responses of individuals with CVA, COUGH and healthy controls to EVH and Mannitol Challenges.
