Clinical trial NCT03105843: Sensory-Mechanical Responses to Eucapneic Voluntary Hyperventilation and Mannitol
Official title: Sensory-Mechanical Responses to Eucapneic Voluntary Hyperventilation and Mannitol in Individuals With Cough Variant Asthma and Chronic Cough
Study type: INTERVENTIONAL
Overall status: RECRUITING
Phase: PHASE4
Conditions: Asthma
Cough
Cough Variant Asthma
Keywords: Asthma
Cough
Eucapneic Voluntary Hyperventilation
Hypertonic Saline
Lead sponsor: Queen's University
Sponsor class: OTHER
First posted: 2017-04-10
Enrollment: 30
Sex: ALL
Minimum age (years): 18
Maximum age (years): 65
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: CROSSOVER
Primary purpose: BASIC_SCIENCE

Brief summary: 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).

Detailed description: 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.

Eligibility criteria: 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.

Primary outcomes:
measure: Mid expiratory flows
timeFrame: Time frame of the methacholine challenge varies between individuals. At provocative dose/ventilation causing a 20% decline in FEV1 (PD20 and PC20 respectively). On average, these occur about 15-25 minutes into the challenge test
Secondary outcomes:
measure: Respiratory System Reactance (X5)
timeFrame: After dose administration; will occur 2-5 minutes after dose
measure: Peripheral Resistance (R5-R20)
timeFrame: After dose administration; will occur 2-5 minutes after dose
measure: Central Airway Resistance
timeFrame: After dose administration; will occur 2-5 minutes after dose
measure: Forced Vital Capacity (FVC)
timeFrame: After dose administration; will occur 2-5 minutes after dose
measure: FEV1/FVC
timeFrame: After dose administration; will occur 2-5 minutes after dose
Other outcomes:
Locations:
city: Kingston
country: Canada
facility: Kingston Health Sciences Centre
state: Ontario
Study officials:
affiliation: Department of Medicine, Queen's University
name: M. Diane Lougheed, MD, MSc
role: PRINCIPAL_INVESTIGATOR
References: