title: Factors influencing the assessment of lung function in mice with influenza-induced lung disease.
abstract: BACKGROUND
  The constant-phase model (CPM) is commonly fit to respiratory system input impedance (Zrs) to estimate lung mechanics. Driving signal frequencies and the method of model fitting may influence the results, especially in cases of severe lung disease or under severe bronchoconstriction.
  
  
  OBJECTIVE
  To illustrate the effects of different CPM fits to Zrs data using a mouse model of influenza-induced lung disease.
  
  
  METHODS
  BALB/c mice infected with influenza (or control) were challenged with methacholine. The CPM was fitted to Zrs, measured between 0·25 and 19·625 Hz, using both unweighted and weighted fits. The effect of different lowest frequencies was assessed.
  
  
  CONCLUSIONS
  For influenza-infected mice, the unweighted fit was poor, and airway resistance (Raw) was often biologically impossible. The weighted fit provided more realistic estimates of Raw. Different model fits and minimal frequencies had little effect on tissue mechanics.
authors.affiliation: Division of Clinical Sciences, Telethon Institute for Child Health Research & Centre for Child Health Research, University of Western Australia, Perth, WA, Australia.Airway Physiology/Imaging Research Group, Woolcock Institute of Medical Research, Sydney, NSW, Australia.Department of Medical Physics and Informatics, University of Szeged, Szeged, Hungary.Queensland Children's Medical Research Institute, University of Queensland, Brisbane, Qld, Australia.
authors.forename: Alexander N
authors.initials: AN
authors.lastname: Larcombe
authors.forename: Graeme R
authors.initials: GR
authors.lastname: Zosky
authors.forename: Cindy
authors.initials: C
authors.lastname: Thamrin
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Bozanich
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Hantos
authors.forename: Peter D
authors.initials: PD
authors.lastname: Sly
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D005260:Female; D008171:Lung Diseases / Q000503:physiopathology*; D051379:Mice; D008807:Mice, Inbred BALB C; D009976:Orthomyxoviridae Infections / Q000503:physiopathology*; D012129:Respiratory Function Tests / Q000379:methods*
keywords: Constant-phase model; forced oscillation technique; influenza; mouse; severe lung disease