Effect of Positive Airway Pressure on Reducing Airway Reactivity in Patients With Asthma (CPAP)

Inclusion criteria

• 15 - 60 years of age at V1
• Physician diagnosis of asthma and on prescribed asthma medication for at least the past 12 months at V1
• Pre-bronchodilator FEV₁ greater than or equal to 75% predicted at V1 (to minimize the likelihood that variability in FEV₁ will preclude participants from having methacholine challenges in follow-up visits)
• Airways reactivity: Methacholine bronchial challenge with concentration of methacholine causing a 20% fall in forced expiratory volume in 1 second (PC ₂₀) less than or equal to 8 mg/mL at V1
• Stable asthma defined by no change in treatment, emergency department (ED) visit, hospitalization, or urgent health care visit for asthma for the 8 weeks prior to screening
• Non-smoker for more than 6 months and less than or equal to 10 pack-year history of smoking
• Ability and willingness to provide informed consent
• If receiving immunotherapy, must have had stable therapy for the 8 weeks prior to screening
• Spend a minimum of six hours per night in bed on average
• Willingness to sleep 5 days a week on average in the same place for the next 4 months
• For women of child bearing potential; not pregnant, not lactating and agree to practice and adequate birth control method (abstinence, combination barrier and spermicide, or hormonal) for the duration of the study

Exclusion criteria

• Weight less than or equal to 66 lbs. (30kg) at V1
• BMI greater than or equal to 35 at V1
• Acute respiratory illness in the month prior to screening
• Systemic corticosteroid therapy during the 3 months preceding screening
• History of sleep apnea by self-report High risk of sleep apnea as assessed by Multivariable Apnea Prediction (MAP) Index; high risk defined as probability that is equal to or greater than 20%
• Chronic diseases (other than asthma) that in the opinion of the investigator would interfere with participation in the trial or put the participant at risk by participation, e.g. non-skin cancer, chronic diseases of the lung (other than asthma), chronic heart diseases, endocrine diseases, liver, kidney or nervous system diseases, or immunodeficiency, any pre-existing conditions that may be contraindications to positive airway pressure including: severe bullous lung disease, pneumothorax, pathologically low blood pressure, dehydration, cerebrospinal fluid leak, recent cranial surgery, trauma, bypassed upper (supraglottic) airway
• Known sleep disorders that are currently under treatment by a sleep specialist
• Known intolerance to methacholine
• Absolute contraindications to methacholine that include: current use of beta-adrenergic blocking agent, heart attack or stroke in the last 3 months, uncontrolled hypertension, known aortic aneurysm
• Use of investigative drugs or intervention trials in the 30 days prior to screening or during the duration of the study
• Prior use of CPAP for any reason Homelessness, lack of telephone access, or intention to move within the next 4 months of the trial.
• For blinding purposes, members from the same household cannot participate in the study at the same time.