title: Exhaled breath condensate purines correlate with lung function in infants and preschoolers.
abstract: BACKGROUND
  Although airway inflammation begins early in life in children with chronic respiratory diseases, current methods to assess this inflammation are invasive and entail significant risk. Measurement of exhaled breath condensate (EBC) purines and other biomarkers offers a less invasive method to assess airway inflammation; however, the feasibility and utility of EBC biomarkers in young children has not been established.
  
  
  METHODS
  EBC was collected from children <3 years old with cystic fibrosis or other lung diseases during clinically indicated infant pulmonary function tests (iPFTs). EBC concentrations of the purine biomarkers adenosine (Ado), adenosine monophosphate (AMP), and the dilution marker urea were measured using mass spectrometry.
  
  
  RESULTS
  EBC was successfully collected (average volume 330 ± 170 µl) from preschool children (age 2.3 ± 0.8 years) in 15 of 17 iPFTs. No significant changes in oxygen saturation (96.9 ± 1.6 start, 96.8 ± 1.7 end, P = 0.389) or respiratory rate (35.2 ± 7.5 start, 34.6 ± 7.9 end, P = 0.443) were observed during collection. Ado and AMP were successfully measured in 13/15 samples [8 cystic fibrosis (CF)]. EBC AMP to Ado ratio (AMP/Ado) negatively correlated with forced expiratory volume at 0.5 sec (FEV(0.5) , r = -0.71, P < 0.01) and positively with the ratio of residual volume to total lung capacity (RV/TLC, r = 0.66, P = 0.015). These correlations remained statistically significant in the subset with CF.
  
  
  CONCLUSIONS
  EBC can be safely collected and analyzed in preschool children using commercially available equipment. The EBC AMP/Ado ratio correlates with measures of infant lung function and may be a less invasive means of monitoring airway inflammation in this population.
authors.affiliation: Department of Pediatric Pulmonology, University of North Carolina, Chapel Hill, North Carolina, USA.
authors.forename: Kavita
authors.initials: K
authors.lastname: Patel
authors.forename: Stephanie D
authors.initials: SD
authors.lastname: Davis
authors.forename: Robin
authors.initials: R
authors.lastname: Johnson
authors.forename: Charles R
authors.initials: CR
authors.lastname: Esther
mesh_terms: D000241:Adenosine / Q000032:analysis*; D000249:Adenosine Monophosphate / Q000032:analysis*; D015415:Biomarkers / Q000032:analysis; D001944:Breath Tests; D002675:Child, Preschool; D003371:Cough / Q000175:diagnosis; D003550:Cystic Fibrosis / Q000175:diagnosis*; D005260:Female; D006801:Humans; D007223:Infant; D007249:Inflammation / Q000175:diagnosis; D007619:Kartagener Syndrome / Q000175:diagnosis; D008171:Lung Diseases / Q000175:diagnosis*; D008297:Male; D013058:Mass Spectrometry; D012129:Respiratory Function Tests
chemical_list: D015415:Biomarkers; D000249:Adenosine Monophosphate; D000241:Adenosine