ARTICLE: Effect of CPAP on Airways Reactivity in Asthma: A Randomized Sham-Controlled Clinical Trial
AUTHORS: Janet T Holbrook, Elizabeth A Sugar, Robert H Brown, Lea T Drye, Charles G. Irvin, Alan R Schwartz, Robert S Tepper, Robert A Wise, Razan Z Yasin, Michael F Busk, and on behalf of the American Lung Association–Airways Clinical Research Centers
JOURNAL: Ann Am Thorac Soc. 2016 Jul 11. [Epub ahead of print]
RATIONALE: Studies have demonstrated that application of stress suppresses airway smooth muscle contractility. In animal models of asthma, continuous positive airway pressure (CPAP) reduced airways reactivity. Short-term studies of CPAP in asthma patients showed reductions inairways reactivity.
OBJECTIVES: To evaluate whether nocturnal CPAP decreased the provocative concentration of methacholine to reduce FEV1 by 20% (PC20).
METHODS: 194 asthmatics were randomized (1:1:1) to use CPAP with warmed, filtered, humidified air at night at pressures less than 1cmH2O (sham), 5cmH2O, or 10cmH2O. The primary outcome was change in PC20 after 12 weeks.
MEASUREMENTS AND MAIN RESULTS: Adherence to CPAP was low in all groups. Regardless, all groups had a significant improvement in PC20 with 12-week to baseline ratios of PC20 was 2.12, 1.73, and 1.78 for sham, 5cmH2O, and 10cmH2O groups, respectively, and no significant differences between active and sham groups. Changes in FEV1 and exhaled nitric oxide were minimal in all groups. The sham group had larger improvements on most patient-reported outcomes measuring asthma symptoms and quality of life, and sinus symptoms than the 5cmH2O group. The 10cmH2O group showed similar, but less consistent, improvements in scores, which were not different from improvements in the sham group.
CONCLUSIONS: Adherence to nocturnal CPAP was low. There was no evidence to support positive pressure as effective for reducing airwaysreactivity in people with well controlled asthma. Regardless, airways 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 airways reactivity. Clinical trial registered with www.clinicaltrials.gov (NCT01629823).
For a link to the full article, click here: http://www.atsjournals.org/doi/abs/10.1513/AnnalsATS.201601-043OC?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%3dpubmed#.V4aAX5MrLUI