title: Independent information of nonspecific biomarkers in exhaled breath condensate.
abstract: BACKGROUND
  Exhaled breath condensate (EBC) has been used for diagnosing and monitoring respiratory disorders. For clinical purposes the assessment of easy-to-obtain nonspecific markers seems particularly interesting.
  
  
  OBJECTIVE
  As these measures are related to each other, our objective was to extract the independent information in global EBC markers across a range of respiratory disorders.
  
  
  METHODS
  EBC was collected from patients with asthma (n = 18), chronic obstructive pulmonary disease (n = 17), and cystic fibrosis (n = 46), as well as from lung transplant (LTX) recipients (n = 14) and healthy controls (n = 26). Samples were assessed for electrical conductivity, ammonia, pH, and nitrite/nitrate. pH was measured after both deaeration with argon and CO(2) standardization. Additionally, the fraction of exhaled nitric oxide (FE(NO)) was assessed. Factor analysis was applied to identify major factors concerning these measures.
  
  
  RESULTS
  Three independent factors were detected; the first comprised conductivity, ammonia, and pH, especially when standardized using CO(2), the second nitrite/nitrate, and the third FE(NO). Conductivity and ammonia were highly correlated (r = 0.968; p < 0.001). FE(NO) provided independent information mainly in asthma. The nonspecific EBC markers showed considerable overlap between patient groups and healthy subjects. However, conductivity, ammonia, pH standardized for CO(2) and nitrite/nitrate were increased in LTX recipients compared to healthy controls (p < 0.05 each).
  
  
  CONCLUSIONS
  A panel of nonspecific easy-to-obtain exhaled breath markers could be reduced to 3 independent factors. The information content of conductivity, ammonia, and pH after CO(2) equilibration appeared to be similar, while FE(NO) was independent. The increased levels of these biomarkers in LTX might indicate a potential for their use in these patients.
authors.affiliation: Institute and Outpatient Clinic for Occupational, Social and Environmental Medicine, Ludwig-Maximilians-University, Ziemssenstrasse 1, Munich, Germany. holger.dressel@med.uni-muenchen.de
authors.forename: Holger
authors.initials: H
authors.lastname: Dressel
authors.forename: Florian
authors.initials: F
authors.lastname: Müller
authors.forename: Rainald
authors.initials: R
authors.lastname: Fischer
authors.forename: Horst
authors.initials: H
authors.lastname: Römmelt
authors.forename: Jens M
authors.initials: JM
authors.lastname: Hohlfeld
authors.forename: Jürgen
authors.initials: J
authors.lastname: Behr
authors.forename: Rudolf M
authors.initials: RM
authors.lastname: Huber
authors.forename: Dennis
authors.initials: D
authors.lastname: Nowak
authors.forename: Rudolf A
authors.initials: RA
authors.lastname: Jörres
mesh_terms: D000328:Adult; D000368:Aged; D000641:Ammonia / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D001944:Breath Tests; D002245:Carbon Dioxide / Q000378:metabolism; D016022:Case-Control Studies; D004553:Electric Conductivity; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008171:Lung Diseases / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009566:Nitrates / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D009573:Nitrites / Q000378:metabolism
chemical_list: D015415:Biomarkers; D009566:Nitrates; D009573:Nitrites; D002245:Carbon Dioxide; D009569:Nitric Oxide; D000641:Ammonia