title: Diagnostic utility of exhaled breath condensate analysis in conjunction with specific inhalation challenge in individuals with suspected work-related asthma.
abstract: BACKGROUND
  Establishing the role of exhaled breath condensate (EBC) analysis in work-related asthma (WRA), and more specifically, in conjunction with specific inhalation challenge (SIC), is difficult.
  
  
  OBJECTIVE
  To measure EBC pH, and nitrite/nitrate concentrations before and after SIC in individuals with suspected WRA exposed to either high-molecular-weight (HMW) or low-molecular-weight (LMW) agents and evaluate whether these changes are useful to distinguish between occupational asthma (OA) and work-exacerbated asthma (WEA).
  
  
  METHODS
  One hundred twenty-five consecutive workers undergoing SIC were enrolled. Exhaled breath condensate was collected at the end of the baseline day and 24 hours after exposure to the offending agent. In all EBC samples, pH was measured, and nitrite and nitrate concentrations were determined.
  
  
  RESULTS
  Specific inhalation challenge was positive in 66 individuals, who were then diagnosed with OA. Work-exacerbated asthma was diagnosed in 14, and in 45 patients establishing a direct relationship between the symptoms and work exposure was not possible. In patients with WEA, EBC pH values after SIC were significantly lower than those before SIC (P = .0047). Using the receiver operating characteristic (ROC) curve, we found that an EBC pH decrease of greater than 0.4 units after SIC achieved the most satisfactory sensitivity 79% (confidence interval [CI]: 49-94) and specificity of 100% (CI: 68-100), considering only patients with asthma and without OA. A decrease in EBC pH of 0.4 or more common in those exposed to HMW agents (8/19, 42%) than in those exposed to LMW agents (7/47, 15%).
  
  
  CONCLUSIONS
  Exhaled breath condensate pH in conjunction with SIC may be useful for diagnosing WEA.
authors.affiliation: Servei de Pneumologia, Hospital Vall d'Hebron, Institut de Recerca, Universitat Autònoma de Barcelona, Barcelona, Spain.
authors.forename: Sara
authors.initials: S
authors.lastname: Sánchez-Vidaurre
authors.forename: Maria-Jesus
authors.initials: MJ
authors.lastname: Cruz
authors.forename: Susana
authors.initials: S
authors.lastname: Gómez-Ollés
authors.forename: Ferran
authors.initials: F
authors.lastname: Morell
authors.forename: Xavier
authors.initials: X
authors.lastname: Muñoz
mesh_terms: D000293:Adolescent; D000328:Adult; D059366:Asthma, Occupational / Q000175:diagnosis*; D001944:Breath Tests / Q000379:methods*; D001985:Bronchial Provocation Tests; D003430:Cross-Sectional Studies; D045853:Exhalation; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D019570:Inhalation Exposure; D008297:Male; D008875:Middle Aged; D009566:Nitrates / Q000032:analysis*; D009573:Nitrites / Q000032:analysis*
chemical_list: D009566:Nitrates; D009573:Nitrites