title: Agreement between multiple-breath nitrogen washout systems in children and adults.
abstract: BACKGROUND
  Comparability of multiple breath washout (MBW) systems has been little explored. We assessed agreement in lung clearance index (LCI) from two similar, commercial nitrogen MBW setups in patients with Cystic Fibrosis (CF) and controls.
  
  
  METHODS
  The EasyOne Pro (NDD) and Exhalyzer D (EM) were randomly applied in 85 adults (34 with CF) and 97 children (47 with CF and normal forced expiratory volume in one second). We assessed differences between setups in LCI, lung volumes and breathing pattern and diagnostic performance for detecting abnormal lung function.
  
  
  RESULTS
  Compared to NDD, EM measured higher LCI, functional residual capacity and cumulative expired volume while respiratory rate was lower. Mean difference (limits of agreement) in LCI was 1.30 (-2.34 to 4.94). In CF, prevalence of abnormal LCI was greater in children and similar in adults using EM compared to NDD.
  
  
  CONCLUSIONS
  Agreement of MBW outcomes between setups is poor and explained by nitrogen measurement techniques and breathing pattern.
authors.affiliation: Cystic Fibrosis Unit, Cliniques Universitaires St Luc, Université de Louvain, Avenue Hippocrate 10, 1200 Brussels, Belgium.
authors.forename: William
authors.initials: W
authors.lastname: Poncin
authors.affiliation: Division of Pediatric Pulmonology, University Children's Hospital Zurich, Steinwiesstrasse 75, 8032 Zurich, Switzerland.
authors.forename: Florian
authors.initials: F
authors.lastname: Singer
authors.affiliation: Cystic Fibrosis Unit, Cliniques Universitaires St Luc, Université de Louvain, Avenue Hippocrate 10, 1200 Brussels, Belgium.
authors.forename: Anne-Sophie
authors.initials: AS
authors.lastname: Aubriot
authors.affiliation: Cystic Fibrosis Unit, Cliniques Universitaires St Luc, Université de Louvain, Avenue Hippocrate 10, 1200 Brussels, Belgium. Electronic address: Patrick.Lebecque@uclouvain.be.
authors.forename: Patrick
authors.initials: P
authors.lastname: Lebecque
mesh_terms: D000328:Adult; D001944:Breath Tests / Q000379:methods; D002648:Child; D003550:Cystic Fibrosis / Q000175:diagnosis / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D008657:Metabolic Clearance Rate; D009584:Nitrogen / Q000493:pharmacokinetics*; D017063:Outcome Assessment, Health Care; D015203:Reproducibility of Results; D012129:Respiratory Function Tests / Q000379:methods
chemical_list: D009584:Nitrogen
keywords: Child; Cystic fibrosis; Data accuracy; Lung volume measurement; Respiratory function tests