title: Tidal breathing FeNO measurements: a new algorithm.
abstract: OBJECTIVE
  International guidelines recommend measuring fractional exhaled nitric oxide (FeNO) during a single slow exhalation with a constant flow of 50 ml/sec. We developed a new algorithm to compute FeNO at 50 ml/sec from tidal breathing measurements. The main objective is to assess the correlation and agreement of this algorithm with the conventional single breath FeNO measurements.
  
  
  METHODS
  We recruited children aged 6-18 years, who performed both a single breath and a tidal breathing FeNO measurement in random order. Both maneuvers were performed on the Eco Medics NO-analyser (Eco Physics AG, Duernten, Switzerland).
  
  
  RESULTS
  We included 109 patients between January 2011 and April 2011. Geometric mean (95% CI) FeNO values did not differ significantly between single breath and tidal breathing technique: 21.0 (17.7-24.8) ppb and 20.0 (17.0-23.6) ppb (P = 0.18), respectively. We found an excellent intraclass correlation coefficient of 0.96 (0.94-0.97) and moderate agreement with a mean difference of 4% (95% limits of agreement -43% and +90%).
  
  
  CONCLUSIONS
  Tidal breathing FeNO values could be transformed with a new algorithm to match single breath FeNO at a constant flow of 50 ml/sec. This algorithm opens the way to standardized FeNO measurements in preschool children and uncooperative patients.
authors: Department of Pediatric Respiratory Medicine, Erasmus University Medical Center-Sophia Children's Hospital, Rotterdam, The Netherlands.
authors: Esther
authors: E
authors: van Mastrigt
authors: Ruben C A
authors: RC
authors: de Groot
authors: Hans W
authors: HW
authors: van Kesteren
authors: Anton T J
authors: AT
authors: Vink
authors: Johan C
authors: JC
authors: de Jongste
authors: Mariëlle W H
authors: MW
authors: Pijnenburg
mesh_terms: D000293:Adolescent; D000465:Algorithms; D001944:Breath Tests; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D009569:Nitric Oxide / Q000032:analysis*
chemical_list: D009569:Nitric Oxide
keywords: children; exhalation flow; fractional exhaled nitric oxide; single breath; tidal breathing