title: Exhaled nitric oxide and exhaled breath condensate pH as predictors of sputum cell counts in optimally treated asthmatic smokers.
abstract: OBJECTIVE
  Smoking is thought to modify the pattern of airway inflammation. Induced sputum provides useful information on cellular phenotype in inflammatory airways disorders; however, it is time-consuming and difficult to implement in everyday clinical practice. The aim of this study was to determine whether exhaled NO (FeNO) and exhaled breath condensate (EBC) pH differed in asthmatic smokers compared with asthmatic non-smokers and healthy subjects, and to evaluate the performance of FeNO and EBC pH for predicting the cellular phenotype of induced sputum.
  
  
  METHODS
  Asthmatic smokers (n = 40) and non-smoking asthmatic patients (n = 43) were recruited for the study. Healthy smoking (n = 30) or non-smoking (n = 30) subjects served as controls. FeNO and EBC pH were measured and all subjects underwent sputum induction for assessment of cell counts.
  
  
  RESULTS
  EBC pH was significantly lower in asthmatic smokers compared with non-smokers (P < 0.01). FeNO levels were also significantly lower in asthmatic smokers compared with non-smokers (P < 0.001). EBC pH was inversely associated with sputum eosinophils in both asthmatic smokers and non-smokers (P < 0.001), whereas it was inversely associated with sputum neutrophils only in asthmatic smokers (P < 0.001). FeNO was positively associated with sputum eosinophils both in asthmatic smokers and non-smokers (P < 0.001) but was not associated with sputum neutrophils. In asthmatic smokers, FeNO was a better predictor of sputum eosinophilia, whereas EBC pH was a better predictor of sputum neutrophilia. A combination of FeNO ≤ 14 ppb together with EBC pH > 7.20 predicted the paucigranulocytic induced sputum phenotype.
  
  
  CONCLUSIONS
  EBC pH and FeNO levels were significantly lower in asthmatic smokers compared with non-smokers. Combined specific cut-off levels for FeNO and EBC pH may predict the paucigranulocytic phenotype in asthmatic smokers.
authors.affiliation: First Respiratory Medicine Department, University of Athens Medical School, Sotiria Chest Diseases Hospital, Athens, Greece.
authors.forename: Georgios
authors.initials: G
authors.lastname: Hillas
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Kostikas
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Mantzouranis
authors.forename: Vassiliki
authors.initials: V
authors.lastname: Bessa
authors.forename: Konstantina
authors.initials: K
authors.lastname: Kontogianni
authors.forename: Georgia
authors.initials: G
authors.lastname: Papadaki
authors.forename: Spyros
authors.initials: S
authors.lastname: Papiris
authors.forename: Manos
authors.initials: M
authors.lastname: Alchanatis
authors.forename: Stelios
authors.initials: S
authors.lastname: Loukides
authors.forename: Petros
authors.initials: P
authors.lastname: Bakakos
mesh_terms: D000280:Administration, Inhalation; D000305:Adrenal Cortex Hormones / Q000008:administration & dosage / Q000627:therapeutic use; D000328:Adult; D000368:Aged; D001249:Asthma / Q000188:drug therapy* / Q000378:metabolism* / Q000473:pathology; D015415:Biomarkers / Q000378:metabolism; D001944:Breath Tests / Q000379:methods*; D016022:Case-Control Studies; D002452:Cell Count; D003430:Cross-Sectional Studies; D045853:Exhalation; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000378:metabolism*; D011237:Predictive Value of Tests; D012907:Smoking / Q000378:metabolism* / Q000473:pathology; D013183:Sputum / Q000166:cytology*; D016896:Treatment Outcome
chemical_list: D000305:Adrenal Cortex Hormones; D015415:Biomarkers; D009569:Nitric Oxide