title: Multiple breath washout cannot be used for tidal breath parameter analysis in infants.
abstract: BACKGROUND
  Multiple breath washout (MBW) testing with SF6 gas mixture is routinely used to assess ventilation distribution in infants. It is currently unknown whether SF6 changes tidal breathing parameters during MBW in infants. We investigated if SF6 does change tidal breathing parameters in infants and whether a separate tidal breathing trace prior to MBW testing is necessary.
  
  
  METHODS
  Tidal breathing during MBW was compared to standard tidal breathing in room air in healthy infants (n = 38), preterm infants (n = 41), and infants with cystic fibrosis (n = 41). Outcomes included inspiratory and expiratory times (TI and TE ), time to peak tidal inspiratory and expiratory flow (tPTIF and tPTEF), tidal volume (VT ), respiratory rate (f), and minute ventilation (VE ).
  
  
  RESULTS
  Breath times were all significantly increased for both healthy (TE : -0.0790 [-0.10566, -0.05217]; mean difference [95% confidence intervals]) and CF (-0.109 [-0.15235, -0.06607]) infants during the MBW wash-in (P < 0.001). Healthy infants and those with CF showed decreased f during MBW wash-in (P < 0.001); however, no change in VT, resulting in a decreased VE (0.154 (0.086, 0.222) and 0.128 (0.069, 0.186) for healthy and CF infants, respectively, P < 0.001). Preterm infants experienced a decreased VE during both wash-in (0.134 [0.061, 0.207]; P < 0.001) and wash-out phases of MBW (P < 0.05).
  
  
  CONCLUSIONS
  There are differences in tidal breathing parameters during MBW testing with SF6 in infants. It is, therefore, important to measure a separate tidal breathing trace in room air, prior to MBW testing to ensure rigour of tidal breath indices derived from analysis.
authors.affiliation: Telethon Kids Institute, University of Western Australia, Subiaco, Australia.
authors.forename: Georgia L
authors.initials: GL
authors.lastname: Banton
authors.affiliation: Telethon Kids Institute, University of Western Australia, Subiaco, Australia.
authors.forename: Graham L
authors.initials: GL
authors.lastname: Hall
authors.affiliation: Telethon Kids Institute, University of Western Australia, Subiaco, Australia.
authors.forename: Mark
authors.initials: M
authors.lastname: Tan
authors.affiliation: Respiratory Medicine, Royal Children's Hospital, Melbourne, VIC, Australia.
authors.forename: Billy
authors.initials: B
authors.lastname: Skoric
authors.affiliation: Respiratory Medicine, Royal Children's Hospital, Melbourne, VIC, Australia.
authors.forename: Sarath C
authors.initials: SC
authors.lastname: Ranganathan
authors.affiliation: School of Population Health, University of Western Australia, Perth, Australia.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Franklin
authors.affiliation: King Edward Memorial Hospital, Mumbai, India.
authors.forename: J Jane
authors.initials: JJ
authors.lastname: Pillow
authors.affiliation: Department of Neonatology, University Children's Hospital Basel, Basel, Switzerland.
authors.forename: Sven M
authors.initials: SM
authors.lastname: Schulzke
authors.affiliation: Telethon Kids Institute, University of Western Australia, Subiaco, Australia.
authors.forename: Shannon J
authors.initials: SJ
authors.lastname: Simpson
mesh_terms: D001944:Breath Tests / Q000379:methods*; D003550:Cystic Fibrosis / Q000503:physiopathology*; D045853:Exhalation; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007234:Infant, Premature; D008297:Male; D012119:Respiration; D012129:Respiratory Function Tests / Q000379:methods*; D056152:Respiratory Rate / Q000502:physiology*; D013990:Tidal Volume
keywords: Infant; multiple breath washout; tidal breathing