title: Physiologic assessment of the ex vivo donor lung for transplantation.
abstract: BACKGROUND
  The evaluation of donor lungs by normothermic ex vivo acellular perfusion has improved the safety of organ utilization. However, this strategy requires a critical re-evaluation of the parameters used to assess lungs during ex vivo perfusion compared with those traditionally used to evaluate the donor lung in vivo. Using a porcine model, we studied the physiology of acellular lung perfusion with the aim of improving the accuracy of clinical ex vivo evaluation.
  
  
  METHODS
  Porcine lungs after 10 hours of brain death and 24 hours of cold ischemia and uninjured control lungs were perfused for 12 hours and then transplanted. PaO2, compliance, airway pressure and pulmonary vascular resistance were measured. Ventilation with 100% nitrogen and addition of red blood cells to the perfusate were used to clarify the physiologic disparities between in vivo blood perfusion and ex vivo acellular perfusion.
  
  
  RESULTS
  During 12 hours of ex vivo perfusion, injured lungs developed edema with decreased compliance and increased airway pressure, but ex vivo PO2 remained stable. After transplantation, injured lungs demonstrated high vascular resistance and poor PaO2. A reduced effect of shunt on ex vivo lung perfusion PO2 was found to be attributable to the linearization of the relationship between oxygen content and PO2, which occurs with acellular perfusate.
  
  
  CONCLUSIONS
  Ex vivo PO2 may not be the first indication of lung injury and, taken alone, may be misleading in assessing the ex vivo lung. Thus, evaluation of other physiologic parameters takes on greater importance.
authors.affiliation: Latner Thoracic Surgery Research Laboratories, McEwen Centre for Regenerative Medicine, University Health Network, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Jonathan C
authors.initials: JC
authors.lastname: Yeung
authors.forename: Marcelo
authors.initials: M
authors.lastname: Cypel
authors.forename: Tiago N
authors.initials: TN
authors.lastname: Machuca
authors.forename: Terumoto
authors.initials: T
authors.lastname: Koike
authors.forename: Douglas J
authors.initials: DJ
authors.lastname: Cook
authors.forename: Riccardo
authors.initials: R
authors.lastname: Bonato
authors.forename: Manyin
authors.initials: M
authors.lastname: Chen
authors.forename: Masaaki
authors.initials: M
authors.lastname: Sato
authors.forename: Thomas K
authors.initials: TK
authors.lastname: Waddell
authors.forename: Mingyao
authors.initials: M
authors.lastname: Liu
authors.forename: Arthur S
authors.initials: AS
authors.lastname: Slutsky
authors.forename: Shaf
authors.initials: S
authors.lastname: Keshavjee
mesh_terms: D000818:Animals; D008168:Lung / Q000502:physiology* / Q000601:surgery; D008170:Lung Compliance / Q000502:physiology; D016040:Lung Transplantation; D008297:Male; D023421:Models, Animal; D010100:Oxygen; D010477:Perfusion; D013552:Swine; D014655:Vascular Resistance / Q000502:physiology
chemical_list: D010100:Oxygen