Bronchodilating and Bronchoprotective Effects of Deep Inspirations

Inclusion Criteria:

• Individuals aged 18-65 years of age with asthma, CVA and individuals with methacholine-induced cough but normal airway sensitivity. The following definitions will be used:

  1. asthma: episodic respiratory symptoms occurring in association with variable airflow obstruction (Canadian Asthma Consensus Report definition);
  2. 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);
  3. 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).

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

  1. Severe airflow limitation (FEV1 <50% predicted or <1.0 L);
  2. Heart attack or stroke in last 3 months;
  3. Uncontrolled hypertension, systolic BP > 200 or diastolic BP > 100;
  4. Known aortic aneurysm;
  5. Moderate airflow limitation <60% predicted or 1.5) is a relative contraindication;
  6. Inability to perform acceptable quality spirometry;
  7. Current use of cholinesterase inhibitor medication (for myasthenia gravis); and
  8. Pregnant or nursing mothers.
• 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.