title: Effect of Continuous Positive Airway Pressure on Airway Reactivity in Asthma. A Randomized, Sham-controlled Clinical Trial.
abstract: Studies have demonstrated that application of stress suppresses airway smooth muscle contractility. In animal models of asthma, continuous positive airway pressure (CPAP) reduced airway reactivity. Short-term studies of CPAP in patients with asthma showed reductions in airway reactivity.
  
  
  
  To evaluate whether nocturnal CPAP decreased the provocative concentration of methacholine to reduce FEV1by 20% (PC20).
  
  
  
  One hundred ninety-four individuals with asthma were randomized (1:1:1) to use CPAP with warmed, filtered, humidified air at night at pressures either less than 1 cm H2O (sham) or at 5 cm H2O or 10 cm H2O. The primary outcome was change in PC20after 12 weeks.
  
  
  
  Adherence to CPAP was low in all groups. Regardless, all groups had a significant improvement in PC20, with 12 weeks/baseline PC20ratios of 2.12, 1.73, and 1.78 for the sham, 5 cm H2O, and 10 cm H2O groups, respectively, and no significant differences between the active and sham groups. Changes in FEV1and exhaled nitric oxide were minimal in all groups. The sham group had larger improvements in most patient-reported outcomes measuring asthma symptoms and quality of life, as well as sinus symptoms, than the 5 cm H2O group. The 10 cm H2O group showed similar but less consistent improvements in scores, which were not different from improvements in the sham group.
  
  
  
  Adherence to nocturnal CPAP was low. There was no evidence to support positive pressure as being effective for reducing airway reactivity in people with well-controlled asthma. Regardless, airway reactivity was improved in all groups, which may represent an effect of participating in a study and/or an effect of warm, humid, filtered air on airway reactivity. Clinical trial registered with www.clinicaltrials.gov (NCT01629823).
authors.affiliation: 1 Department of Epidemiology and.
authors.forename: Janet T
authors.initials: JT
authors.lastname: Holbrook
authors.affiliation: 2 Department of Biostatistics, Bloomberg School of Public Health, The Johns Hopkins University, Baltimore, Maryland.
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Sugar
authors.affiliation: 3 Anesthesiology and Critical Care Medicine and.
authors.forename: Robert H
authors.initials: RH
authors.lastname: Brown
authors.affiliation: 1 Department of Epidemiology and.
authors.forename: Lea T
authors.initials: LT
authors.lastname: Drye
authors.affiliation: 4 Department of Medicine, University of Vermont, Burlington, Vermont.
authors.forename: Charles G
authors.initials: CG
authors.lastname: Irvin
authors.affiliation: 5 Pulmonary and Critical Care Medicine, School of Medicine, The Johns Hopkins University, Baltimore, Maryland.
authors.forename: Alan R
authors.initials: AR
authors.lastname: Schwartz
authors.affiliation: 6 Department of Pediatrics, Indiana University, Indianapolis, Indiana; and.
authors.forename: Robert S
authors.initials: RS
authors.lastname: Tepper
authors.affiliation: 5 Pulmonary and Critical Care Medicine, School of Medicine, The Johns Hopkins University, Baltimore, Maryland.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Wise
authors.affiliation: 1 Department of Epidemiology and.
authors.forename: Razan Z
authors.initials: RZ
authors.lastname: Yasin
authors.affiliation: 7 St. Vincent Health, Wellness and Preventive Care Institute, Indianapolis, Indiana.
authors.forename: Michael F
authors.initials: MF
authors.lastname: Busk
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D001249:Asthma / Q000628:therapy*; D001985:Bronchial Provocation Tests; D016085:Bronchoconstrictor Agents / Q000008:administration & dosage; D045422:Continuous Positive Airway Pressure / Q000379:methods*; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D016210:Methacholine Chloride / Q000008:administration & dosage; D008875:Middle Aged; D010349:Patient Compliance; D011788:Quality of Life; D016896:Treatment Outcome; D014481:United States; D055815:Young Adult
chemical_list: D016085:Bronchoconstrictor Agents; D016210:Methacholine Chloride
keywords: CPAP; PC20; airway reactivity; asthma; methacholine