Sensory-Mechanical Responses to Eucapneic Voluntary Hyperventilation and Hypertonic Saline
Sensory-Mechanical Responses to Eucapneic Voluntary Hyperventilation and Hypertonic Saline
The objectives of this study are to determine the sensory-mechanical responses to Eucapneic
 Voluntary Hyperventilation (EVH) and Hypertonic Saline (HS) 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 HS 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 HS) are
 comparable within groups (CVA, COUGH and healthy controls).
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 hypertonic saline (HS), 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
 HS challenge.
Inclusion Criteria:

 -  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:

 1. 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);

 2. 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.

 Exclusion Criteria:

 -  an exacerbation necessitating a change in medication, emergency department visit or
 hospitalizations within the previous 4 weeks

 -  inability to perform acceptable spirometry

 -  medical contraindications to methacholine challenge testing

 -  smoking history in excess of 10 pack years Note: Previous treatment with inhaled or
 systemic corticosteroids is not an exclusion criterion; medication use will be
 recorded and examined in the analysis.