Sensory-Mechanical Responses to Eucapneic Voluntary Hyperventilation and Mannitol in Individuals With Cough Variant Asthma and Chronic Cough
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).
• Individuals aged 18-65 years of age with CVA and individuals with methacholine-induced cough but normal airway sensitivity. The following definitions will be used:
‣ CVA: chronic cough (≥8 weeks) is the sole or predominant symptom and positive methacholine challenge (PC20 ≤ 16 mg/mL) and history of cough responding to specific asthma treatment (such as inhaled steroid or 1 week trial of bronchodilator);
⁃ Methacholine-induced cough but normal airway sensitivity: chronic cough (≥8 weeks) is the sole or predominant symptom and negative methacholine challenges (PC20 \> 16 mg/mL).
• Individuals aged 18-65 years of age with no history of asthma or chronic cough.