title: Exhaled breath condensate pH in lung transplant recipients with bronchiolitis obliterans syndrome.
abstract: BACKGROUND
  Assessment of exhaled breath condensate (EBC) pH is a promising method for investigating airway pathology. However, inaccurate measurement techniques may bias pH readings. In this longitudinal study, we tested whether development of bronchiolitis obliterans syndrome (BOS) in lung transplant recipients is associated with acidification of EBC.
  
  
  METHODS
  EBC was collected in 15 patients with BOS and 16 stable BOS-free patients during routine clinical visits. From nine BOS patients, samples were collected before and after the onset of BOS, as well. Twenty healthy nontransplant subjects served as controls. EBC pH was measured by the carbon dioxide gas standardization method.
  
  
  RESULTS
  EBC pH in patients with and without BOS and controls was similar (BOS group: 6.40±0.04, BOS-free group: 6.45±0.03; controls: 6.39±0.02; P>0.05). In patients who developed BOS during the follow-up, EBC pH before and after the onset of BOS was comparable (pre-BOS: 6.41±0.04 vs. post-BOS: 6.41±0.04; P>0.05). Coefficient of variation for repeated pH measurements in controls and subjects with and without BOS was 2.3%±0.3%, 2.0%±0.3%, and 1.7%±0.2%, respectively (P>0.05). Similarly, the limits of agreement for between-visit variability determined by the Bland-Altman test were comparable among the study groups.
  
  
  CONCLUSIONS
  These data suggest that assessment of EBC pH is of limited value for the diagnosis of BOS.
authors.affiliation: Department of Pathophysiology, National Koranyi Institute for TB and Pulmonology, Budapest, Hungary.
authors.forename: Szabolcs
authors.initials: S
authors.lastname: Soter
authors.forename: Krisztina
authors.initials: K
authors.lastname: Kelemen
authors.forename: Imre
authors.initials: I
authors.lastname: Barta
authors.forename: Marta
authors.initials: M
authors.lastname: Valyon
authors.forename: Eszter
authors.initials: E
authors.lastname: Csiszer
authors.forename: Balazs
authors.initials: B
authors.lastname: Antus
mesh_terms: D000328:Adult; D001944:Breath Tests / Q000379:methods*; D001989:Bronchiolitis Obliterans / Q000175:diagnosis* / Q000378:metabolism; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008137:Longitudinal Studies; D016040:Lung Transplantation; D008297:Male