title: A fast, simple, and inexpensive method to collect exhaled breath condensate for pH determination.
abstract: BACKGROUND
  Exhaled breath condensate (EBC) analysis is a noninvasive method for assessing lower airway inflammation. Various methods of collecting EBC have been described. However, they are often time-consuming or involve expensive equipment.
  
  
  OBJECTIVE
  To evaluate the efficiency and repeatability of a simple, fast, and inexpensive method of EBC collection for pH determination.
  
  
  METHODS
  Twenty-four mild asthmatic patients, 18 moderate-to-severe asthmatic patients, and 26 controls were asked to slowly exhale for 45 seconds into a -80 degrees C cooled metal cylinder covered with protective rubber and attached to a piece of tubing. The EBC was collected using a syringe's plunger. The groups were compared regarding EBC pH. Reproducibility tests were also performed. Induced sputum samples were obtained for inflammatory cell counts.
  
  
  RESULTS
  We obtained approximately 50 microL of EBC for pH determination. Mild asthmatic patients had lower mean +/- SD pH values than controls (5.97 +/- 0.48 vs 6.36 +/- 0.34; P = .008), and corticosteroid-treated, moderate-to-severe asthmatic patients had mean +/- SD pH values similar to controls (6.23 +/- 0.38; P > .05). Mean +/- SD sputum eosinophil percentages were higher in both asthmatic groups than in controls (3.42% +/- 5.37% and 4.14% +/- 4.98% vs 0.04% +/- 0.12%; P < .001) and were not correlated with pH values in all groups. The mean intraday coefficient of variation for the method was 4.8% (range, 0.9%-8.8%). No correlation was found in all groups between sputum neutrophils and pH.
  
  
  CONCLUSIONS
  We developed a useful device for collecting EBC for pH evaluation that could provide an alternative to other methods when pH is the main variable evaluated.
authors.affiliation: Unité de recherche en pneumologie, Centre de recherche de l'Hôpital Laval, Institut universitaire de cardiologie et de pneumologie de l'Université Laval, Québec, Québec, Canada.
authors.forename: Philippe
authors.initials: P
authors.lastname: Prince
authors.forename: Marie-Eve
authors.initials: ME
authors.lastname: Boulay
authors.forename: Louis-Philippe
authors.initials: LP
authors.lastname: Boulet
mesh_terms: D000293:Adolescent; D000305:Adrenal Cortex Hormones / Q000627:therapeutic use; D000328:Adult; D001249:Asthma / Q000175:diagnosis* / Q000188:drug therapy; D015415:Biomarkers / Q000032:analysis; D001944:Breath Tests / Q000295:instrumentation / Q000379:methods; D002452:Cell Count; D019937:Diagnostic Techniques and Procedures / Q000295:instrumentation*; D004804:Eosinophils / Q000473:pathology; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013183:Sputum / Q000166:cytology
chemical_list: D000305:Adrenal Cortex Hormones; D015415:Biomarkers