title: Comparison of exhaled breath condensate pH using two commercially available devices in healthy controls, asthma and COPD patients.
abstract: BACKGROUND
  Analysis of exhaled breath condensate (EBC) is a non-invasive method for studying the acidity (pH) of airway secretions in patients with inflammatory lung diseases.
  
  
  OBJECTIVE
  To assess the reproducibility of EBC pH for two commercially available devices (portable RTube and non-portable ECoScreen) in healthy controls, patients with asthma or COPD, and subjects suffering from an acute cold with lower-airway symptoms. In addition, we assessed the repeatability in healthy controls.
  
  
  METHODS
  EBC was collected from 40 subjects (n = 10 in each of the above groups) using RTube and ECoScreen. EBC was collected from controls on two separate occasions within 5 days. pH in EBC was assessed after degasification with argon for 20 min.
  
  
  RESULTS
  In controls, pH-measurements in EBC collected by RTube or ECoScreen showed no significant difference between devices (p = 0.754) or between days (repeatability coefficient RTube: 0.47; ECoScreen: 0.42) of collection. A comparison between EBC pH collected by the two devices in asthma, COPD and cold patients also showed good reproducibility. No differences in pH values were observed between controls (mean pH 8.27; RTube) and patients with COPD (pH 7.97) or asthma (pH 8.20), but lower values were found using both devices in patients with a cold (pH 7.56; RTube, p < 0.01; ECoScreen, p < 0.05).
  
  
  CONCLUSIONS
  We conclude that pH measurements in EBC collected by RTube and ECoScreen are repeatable and reproducible in healthy controls, and are reproducible and comparable in healthy controls, COPD and asthma patients, and subjects with a common cold.
authors.affiliation: Department of Pulmonology, Leiden University Medical Center, the Netherlands. rembertkoczulla@web.de
authors.forename: Rembert
authors.initials: R
authors.lastname: Koczulla
authors.forename: Silvano
authors.initials: S
authors.lastname: Dragonieri
authors.forename: Robert
authors.initials: R
authors.lastname: Schot
authors.forename: Robert
authors.initials: R
authors.lastname: Bals
authors.forename: Stefanie A
authors.initials: SA
authors.lastname: Gauw
authors.forename: Claus
authors.initials: C
authors.lastname: Vogelmeier
authors.forename: Klaus F
authors.initials: KF
authors.lastname: Rabe
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Sterk
authors.forename: Pieter S
authors.initials: PS
authors.lastname: Hiemstra
mesh_terms: D000328:Adult; D001249:Asthma / Q000175:diagnosis*; D001944:Breath Tests / Q000295:instrumentation* / Q000379:methods*; D004867:Equipment Design; D045853:Exhalation; D006801:Humans; D006863:Hydrogen-Ion Concentration; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis*; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult
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