title: Validation of multiple-breath washout equipment for infants and young children.
abstract: BACKGROUND
  The new ATS/ERS consensus report recommends in vitro validation of multiple-breath inert gas washout (MBW) equipment based on a lung model with simulated physiologic conditions. We aimed to assess accuracy of two MBW setups for infants and young children using this model, and to compare functional residual capacity (FRC) from helium MBW (FRC(MBW)) with FRC from plethysmography (FRC(pleth)) in vivo.
  
  
  METHODS
  The MBW setups were based on ultrasonic flow meter technology. Sulfur hexafluoride and helium were used as tracer gases. We measured FRC in vitro for specific model settings with and without carbon dioxide and calculated differences of measured to generated FRC. For in vivo evaluation, difference between FRC(MBW) and FRC(pleth) was calculated in 20 healthy children, median age 6.1 years. Coefficient of variation (CV) was calculated per FRC.
  
  
  RESULTS
  In the infant model (51 runs, FRC 80-300 ml), mean (SD) relative difference between generated and measured FRCs was 0.7 (4.7) %, median CV was 4.4% for measured FRCs. In the young child model, one setting (8 runs, FRC 400 ml) showed a relative difference of up to 13%. For the remaining FRCs (42 runs, FRC 600-1,400 ml), mean (SD) relative difference was -2.0 (3.4) %; median CV was 1.4% for measured FRCs. In vivo FRC(pleth) exceeded FRC(MBW) values by 37% on average.
  
  
  CONCLUSIONS
  Both setups measure lung volumes in the intended age group reliably and reproducibly. Characteristics of different techniques should be considered when measuring lung volumes in vivo.
authors.affiliation: Department of Pediatrics, University Hospital of Bern, Bern, Switzerland.|University Children's Hospital of Basel, Basel, Switzerland.
authors.forename: Anne
authors.initials: A
authors.lastname: Schmidt
authors.affiliation: Department of Pediatrics, University Hospital of Bern, Bern, Switzerland.|University Children's Hospital of Basel, Basel, Switzerland.
authors.forename: Sophie
authors.initials: S
authors.lastname: Yammine
authors.affiliation: Department of Pediatrics, University Hospital of Bern, Bern, Switzerland.|University Children's Hospital of Basel, Basel, Switzerland.
authors.forename: Elena
authors.initials: E
authors.lastname: Proietti
authors.affiliation: University Children's Hospital of Basel, Basel, Switzerland.
authors.forename: Urs
authors.initials: U
authors.lastname: Frey
authors.affiliation: Department of Pediatrics, University Hospital of Bern, Bern, Switzerland.|University Children's Hospital of Basel, Basel, Switzerland.
authors.forename: Philipp
authors.initials: P
authors.lastname: Latzin
authors.affiliation: Department of Pediatrics, University Hospital of Bern, Bern, Switzerland.
authors.forename: Thomas
authors.initials: T
authors.lastname: Riedel
authors.affiliation: Department of Pediatrics, University Hospital of Bern, Bern, Switzerland.|University Children's Hospital of Zurich, Zurich, Switzerland.
authors.forename: Florian
authors.initials: F
authors.lastname: Singer
mesh_terms: D001944:Breath Tests / Q000379:methods*; D002648:Child; D002675:Child, Preschool; D005260:Female; D005652:Functional Residual Capacity; D006801:Humans; D007223:Infant; D008168:Lung / Q000502:physiology*; D008176:Lung Volume Measurements / Q000295:instrumentation; D008297:Male; D010991:Plethysmography / Q000295:instrumentation; D015203:Reproducibility of Results; D012129:Respiratory Function Tests / Q000379:methods*; D013990:Tidal Volume
keywords: in vitro; in vivo; respiratory function tests; validation studies