title: Comparison of two devices and two breathing patterns for exhaled breath condensate sampling.
abstract: BACKGROUND
  Analysis of exhaled breath condensate (EBC) is a noninvasive method to access the epithelial lining fluid of the lungs. Due to standardization problems the method has not entered clinical practice. The aim of the study was to assess the comparability for two commercially available devices in healthy controls. In addition, we assessed different breathing patterns in healthy controls with protein markers to analyze the source of the EBC.
  
  
  METHODS
  EBC was collected from ten subjects using the RTube and ECoScreen Turbo in a randomized crossover design, twice with every device--once in tidal breathing and once in hyperventilation. EBC conductivity, pH, surfactant protein A, Clara cell secretory protein and total protein were assessed. Bland-Altman plots were constructed to display the influence of different devices or breathing patterns and the intra-class correlation coefficient (ICC) was calculated. The volatile organic compound profile was measured using the electronic nose Cyranose 320. For the analysis of these data, the linear discriminant analysis, the Mahalanobis distances and the cross-validation values (CVV) were calculated.
  
  
  RESULTS
  Neither the device nor the breathing pattern significantly altered EBC pH or conductivity. ICCs ranged from 0.61 to 0.92 demonstrating moderate to very good agreement. Protein measurements were greatly influenced by breathing pattern, the device used, and the way in which the results were reported. The electronic nose could distinguish between different breathing patterns and devices, resulting in Mahalanobis distances greater than 2 and CVVs ranging from 64% to 87%.
  
  
  CONCLUSIONS
  EBC pH and (to a lesser extent) EBC conductivity are stable parameters that are not influenced by either the device or the breathing patterns. Protein measurements remain uncertain due to problems of standardization. We conclude that the influence of the breathing maneuver translates into the necessity to keep the volume of ventilated air constant in further studies.
authors.affiliation: Division for Pulmonary Diseases, Department of Internal Medicine, Philipps-University Marburg, Marburg, Germany.
authors.forename: Eva-Maria
authors.initials: EM
authors.lastname: Hüttmann
authors.forename: Timm
authors.initials: T
authors.lastname: Greulich
authors.forename: Akira
authors.initials: A
authors.lastname: Hattesohl
authors.forename: Severin
authors.initials: S
authors.lastname: Schmid
authors.forename: Sarah
authors.initials: S
authors.lastname: Noeske
authors.forename: Christian
authors.initials: C
authors.lastname: Herr
authors.forename: Gerrit
authors.initials: G
authors.lastname: John
authors.forename: Rudolf A
authors.initials: RA
authors.lastname: Jörres
authors.forename: Bernd
authors.initials: B
authors.lastname: Müller
authors.forename: Claus
authors.initials: C
authors.lastname: Vogelmeier
authors.forename: Andreas Rembert
authors.initials: AR
authors.lastname: Koczulla
mesh_terms: D000328:Adult; D001944:Breath Tests / Q000295:instrumentation* / Q000379:methods; D004553:Electric Conductivity; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008722:Methods; D011506:Proteins / Q000032:analysis; D012015:Reference Standards; D012119:Respiration; D055815:Young Adult
chemical_list: D011506:Proteins
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