title: Exhaled carbon monoxide is not flow dependent in children with cystic fibrosis and asthma.
abstract: OBJECTIVE
  Exhaled nitric oxide (eNO) and carbon monoxide (eCO) concentrations are elevated in inflammatory airway diseases like asthma and have been investigated as potential diagnostic markers. For eNO concentrations knowledge about the inverse flow dependency is essential for reproducibility and comparability of measurements. The aim of this investigation was to evaluate a possible expiratory flow dependency of eCO in children with different inflammatory airway diseases.
  
  
  METHODS
  ENO and eCO concentrations were measured electrochemically and via chemiluminescence in the exhaled air of 20 healthy children, 17 stable cystic fibrosis (CF)-patients and 15 steroid-naive asthmatics in a combined analyzer at five different expiratory flows (10, 20, 45, 86, 184 ml/sec).
  
  
  RESULTS
  ECO was not flow dependent in any of the three groups. At 45 ml/sec the mean eCO-concentration of healthy children was 3.72 +/- 0.23 ppm, of CF-patients 3.67 +/- 0.37 ppm and of asthmatics 4.99 +/- 0.45 ppm. Elevated eCO (p<0.0122) was found in asthmatics but not in CF-children. There was no age dependency and no correlation between eNO and eCO.
  
  
  CONCLUSIONS
  In contrast to CF-patients in the exhaled air of steroid-naive asthmatics elevated eCO concentrations are found that may serve as non-invasive inflammatory marker. In contrast to eNO, eCO did not show any expiratory flow dependency.
authors.affiliation: Dr. von Hauner Children's Hospital, Ludwig-Maximilians-University, Lindwurmstrasse 4, D-80337 Munich, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Beck-Ripp
authors.forename: P
authors.initials: P
authors.lastname: Latzin
authors.forename: Matthias
authors.initials: M
authors.lastname: Griese
mesh_terms: D000293:Adolescent; D000367:Age Factors; D001249:Asthma / Q000378:metabolism* / Q000503:physiopathology; D015415:Biomarkers / Q000378:metabolism; D001944:Breath Tests; D002248:Carbon Monoxide / Q000378:metabolism*; D002648:Child; D003550:Cystic Fibrosis / Q000378:metabolism* / Q000503:physiopathology; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D008448:Maximal Expiratory Flow Rate; D009569:Nitric Oxide / Q000378:metabolism; D012143:Respiratory Physiological Phenomena
chemical_list: D015415:Biomarkers; D009569:Nitric Oxide; D002248:Carbon Monoxide