title: Effects of CPAP therapy withdrawal on exhaled breath pattern in obstructive sleep apnoea.
abstract: BACKGROUND
  Obstructive sleep apnoea (OSA) is highly prevalent and associated with cardiovascular and metabolic changes. OSA is usually diagnosed by polysomnography which is time-consuming and provides little information on the patient's phenotype thus limiting a personalised treatment approach. Exhaled breath contains information on metabolism which can be analysed by mass spectrometry within minutes. The objective of this study was to identify a breath profile in OSA recurrence by use of secondary-electrospray-ionization-mass spectrometry (SESI-MS).
  
  
  METHODS
  Patients with OSA effectively treated with CPAP were randomised to either withdraw treatment (subtherapeutic CPAP) or continue therapeutic CPAP for 2 weeks. Exhaled breath analysis by untargeted SESI-MS was performed at baseline and 2 weeks after randomisation. The primary outcome was the change in exhaled molecular breath pattern.
  
  
  RESULTS
  30 patients with OSA were randomised and 26 completed the trial according to the protocol. CPAP withdrawal led to a recurrence of OSA (mean difference in change of oxygen desaturation index between groups +30.3/h; 95% CI 19.8/h,40.7/h, p<0.001) which was accompanied by a significant change in 62 exhaled features (16 metabolites identified). The panel of discriminating mass-spectral features allowed differentiation between treated and untreated OSA with a sensitivity of 92.9% and a specificity of 84.6%.
  
  
  CONCLUSIONS
  Exhaled breath analysis by SESI-MS allows rapid and accurate detection of OSA recurrence. The technique has the potential to characterise an individual's metabolic response to OSA and thus makes a comprehensible phenotyping of OSA possible.
  
  
  BACKGROUND
  NCT02050425 (registered at ClinicalTrials.gov).
authors.affiliation: Department of Pulmonology and Sleep Disorders Centre, University Hospital of Zurich, Zurich, Switzerland.
authors.forename: Esther I
authors.initials: EI
authors.lastname: Schwarz
authors.affiliation: Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology, Zurich, Switzerland.
authors.forename: Pablo
authors.initials: P
authors.lastname: Martinez-Lozano Sinues
authors.affiliation: Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology, Zurich, Switzerland.
authors.forename: Lukas
authors.initials: L
authors.lastname: Bregy
authors.affiliation: Department of Pulmonology and Sleep Disorders Centre, University Hospital of Zurich, Zurich, Switzerland.
authors.forename: Thomas
authors.identifier: http://orcid.org/0000-0002-9017-6143
authors.initials: T
authors.lastname: Gaisl
authors.affiliation: Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology, Zurich, Switzerland.
authors.forename: Diego
authors.initials: D
authors.lastname: Garcia Gomez
authors.affiliation: Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology, Zurich, Switzerland.
authors.forename: Martin T
authors.initials: MT
authors.lastname: Gaugg
authors.affiliation: Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology, Zurich, Switzerland.
authors.forename: Yannick
authors.initials: Y
authors.lastname: Suter
authors.affiliation: Department of Pulmonology and Sleep Disorders Centre, University Hospital of Zurich, Zurich, Switzerland.
authors.forename: Nina
authors.initials: N
authors.lastname: Stebler
authors.affiliation: Department of Pulmonology and Sleep Disorders Centre, University Hospital of Zurich, Zurich, Switzerland.
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Nussbaumer-Ochsner
authors.affiliation: Department of Pulmonology and Sleep Disorders Centre, University Hospital of Zurich, Zurich, Switzerland Centre for Integrative Human Physiology, University of Zurich, Zurich, Switzerland Zurich Centre for Interdisciplinary Sleep Research, University of Zurich, Zurich, Switzerland.
authors.forename: Konrad E
authors.initials: KE
authors.lastname: Bloch
authors.affiliation: Oxford Centre for Respiratory Medicine and NIHR Oxford Biomedical Research Centre, Churchill Hospital, Oxford, UK.
authors.forename: John R
authors.initials: JR
authors.lastname: Stradling
authors.affiliation: Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology, Zurich, Switzerland.
authors.forename: Renato
authors.initials: R
authors.lastname: Zenobi
authors.affiliation: Department of Pulmonology and Sleep Disorders Centre, University Hospital of Zurich, Zurich, Switzerland Centre for Integrative Human Physiology, University of Zurich, Zurich, Switzerland Zurich Centre for Interdisciplinary Sleep Research, University of Zurich, Zurich, Switzerland.
authors.forename: Malcolm
authors.initials: M
authors.lastname: Kohler
mesh_terms: D000328:Adult; D000368:Aged; D001944:Breath Tests; D045422:Continuous Positive Airway Pressure / Q000379:methods*; D045853:Exhalation / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000032:analysis*; D010101:Oxygen Consumption / Q000502:physiology*; D017286:Polysomnography; D012189:Retrospective Studies; D020181:Sleep Apnea, Obstructive / Q000503:physiopathology / Q000628:therapy*; D015300:Ventilator Weaning; D028761:Withholding Treatment; D055815:Young Adult
chemical_list: D010100:Oxygen
keywords: Exhaled Airway Markers; Sleep apnoea