title: Exhaled nitric oxide and exhaled breath condensate pH in severe refractory asthma.
abstract: BACKGROUND
  Distinct inflammatory cellular phenotypes of severe refractory asthma (SRA) have been reported. Fractional exhaled nitric oxide (FeNO) primarily is related to eosinophilic inflammation. Exhaled breath condensate (EBC) pH has been suggested as a noninvasive tool in the assessment of patients with asthma. We sought to determine whether FeNO and EBC pH could identify the presence and type of the underlying cellular inflammation in patients with SRA.
  
  
  METHODS
  Twenty-nine patients with SRA, 27 patients with moderate asthma, and 17 healthy subjects underwent FeNO measurement, EBC collection for pH measurement, and sputum induction for cell count identification.
  
  
  RESULTS
  FeNO was significantly higher and pH significantly lower in patients with SRA than in the other groups. In SRA, FeNO levels of > 19 parts per billion were associated with a sensitivity of 0.78 and a specificity of 0.73 for sputum eosinophilia, whereas FeNO levels of < 19 parts per billion were associated with a sensitivity of 0.63 and a specificity of 0.9 for sputum neutrophilia irrespective of the presence of eosinophils. The pH failed to predict the cellular profile in SRA, but a cutoff value of < 7.37 could predict sputum eosinophilia in moderate asthma.
  
  
  CONCLUSIONS
  In patients with SRA, different FeNO threshold values can identify those with predominant eosinophilia as well as those with neutrophilia. FeNO levels were reduced in patients with predominant neutrophilia regardless of the concomitant presence of eosinophilia. Although pH could not identify the cellular profile in SRA, it seemed to be a better index for predicting eosinophilia in moderate asthma.
authors.affiliation: Second Respiratory Medicine Department, Universityof Athens Medical School, Attikon Hospital, Athens, Greece.
authors.forename: Eleni
authors.initials: E
authors.lastname: Tseliou
authors.forename: Vasiliki
authors.initials: V
authors.lastname: Bessa
authors.forename: Georgios
authors.initials: G
authors.lastname: Hillas
authors.forename: Vasiliki
authors.initials: V
authors.lastname: Delimpoura
authors.forename: Georgia
authors.initials: G
authors.lastname: Papadaki
authors.forename: Charis
authors.initials: C
authors.lastname: Roussos
authors.forename: Spyros
authors.initials: S
authors.lastname: Papiris
authors.forename: Petros
authors.initials: P
authors.lastname: Bakakos
authors.forename: Stelios
authors.initials: S
authors.lastname: Loukides
mesh_terms: D000328:Adult; D000388:Air / Q000032:analysis*; D001249:Asthma / Q000175:diagnosis / Q000378:metabolism*; D001944:Breath Tests / Q000379:methods*; D045853:Exhalation; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000378:metabolism*; D011379:Prognosis; D012720:Severity of Illness Index; D013183:Sputum / Q000166:cytology
chemical_list: D009569:Nitric Oxide