title: Optimal mean airway pressure during high-frequency oscillatory ventilation determined by measurement of respiratory system reactance.
abstract: BACKGROUND
  The aims of the present study were (i) to characterize the relationship between mean airway pressure (PAW) and reactance measured at 5 Hz (reactance of the respiratory system (X RS), forced oscillation technique) and (ii) to compare optimal PAW (P opt) defined by X RS, oxygenation, lung volume (VL), and tidal volume (VT) in preterm lambs receiving high-frequency oscillatory ventilation (HFOV).
  
  
  METHODS
  Nine 132-d gestation lambs were commenced on HFOV at PAW of 14 cmH2O (P start). PAW was increased stepwise to a maximum pressure (P max) and subsequently sequentially decreased to the closing pressure (Pcl, oxygenation deteriorated) or a minimum of 6 cmH2O, using an oxygenation-based recruitment maneuver. X RS, regional V L (electrical impedance tomography), and V T were measured immediately after (t 0 min) and 2 min after (t 2 min) each PAW decrement. P opt defined by oxygenation, X RS, V L, and V T were determined.
  
  
  RESULTS
  The PAW-X RS and PAW-VT relationships were dome shaped with a maximum at Pcl+6 cmH2O, the same point as P opt defined by VL. Below Pcl+6 cmH2O, X RS became unstable between t 0 min and t 2 min and was associated with derecruitment in the dependent lung. P opt, as defined by oxygenation, was lower than the P opt defined by X RS, V L, or V T.
  
  
  CONCLUSIONS
  X RS has the potential as a bedside tool for optimizing PAW during HFOV.
authors.affiliation: Dipartimento di Elettronica Informazione e Bioingegneria, Politecnico di Milano University, Milano, Italy.
authors.forename: Emanuela
authors.initials: E
authors.lastname: Zannin
authors.affiliation: Neonatology and Neonatal Intensive Care Unit, Fondazione MBBM - Ospedale San Gerardo, Monza, Italy.
authors.forename: Maria Luisa
authors.initials: ML
authors.lastname: Ventura
authors.affiliation: Dipartimento di Elettronica Informazione e Bioingegneria, Politecnico di Milano University, Milano, Italy.
authors.forename: Raffaele L
authors.initials: RL
authors.lastname: Dellacà
authors.affiliation: Neonatology and Neonatal Intensive Care Unit, Fondazione MBBM - Ospedale San Gerardo, Monza, Italy.
authors.forename: Miria
authors.initials: M
authors.lastname: Natile
authors.affiliation: Neonatology and Neonatal Intensive Care Unit, Fondazione MBBM - Ospedale San Gerardo, Monza, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Tagliabue
authors.affiliation: 1] Neonatal Research, Murdoch Childrens Research Institute, Melbourne, Victoria, Australia [2] Department of Neonatology, Royal Children's Hospital, Melbourne, Victoria, Australia.
authors.forename: Elizabeth J
authors.initials: EJ
authors.lastname: Perkins
authors.affiliation: Department of Neonatology, Royal Children's Hospital, Melbourne, Victoria, Australia.
authors.forename: Magdy
authors.initials: M
authors.lastname: Sourial
authors.affiliation: Neonatal Research, Murdoch Childrens Research Institute, Melbourne, Victoria, Australia.
authors.forename: Risha
authors.initials: R
authors.lastname: Bhatia
authors.affiliation: 1] Neonatal Research, Murdoch Childrens Research Institute, Melbourne, Victoria, Australia [2] Department of Paediatrics, Royal Hobart Hospital and University of Tasmania, Hobart, Tasmania, Australia [3] Neonatal Respiratory Group, Menzies Research Institute, Hobart, Tasmania, Australia.
authors.forename: Peter A
authors.initials: PA
authors.lastname: Dargaville
authors.affiliation: 1] Neonatal Research, Murdoch Childrens Research Institute, Melbourne, Victoria, Australia [2] Department of Neonatology, Royal Children's Hospital, Melbourne, Victoria, Australia [3] Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: David G
authors.initials: DG
authors.lastname: Tingay
mesh_terms: D000818:Animals; D005260:Female; D006612:High-Frequency Ventilation / Q000379:methods*; D008297:Male; D010100:Oxygen / Q000378:metabolism; D011312:Pressure; D012756:Sheep; D014132:Trachea / Q000502:physiology*
chemical_list: D010100:Oxygen