title: Variability in Pressure of Arterial Oxygen to Fractional Inspired Oxygen Concentration Ratio During Cellular Ex Vivo Lung Perfusion: Implication for Decision Making.
abstract: BACKGROUND
  The pressure of arterial oxygen to fractional inspired oxygen concentration (PaO2/FiO2, P/F) ratio has been the gold standard in the assessment of transplant suitability in ex vivo lung perfusion (EVLP) with red blood cells. However, several reports using mathematical models and clinical data analysis suggest that the P/F ratio fluctuates at different FiO2. The purpose of this study was to examine the variations in P/F ratio at different FiO2 during EVLP and develop a practicable decision making algorithm in the EVLP.
  
  
  METHODS
  Porcine lungs (n = 16) were perfused in cellular EVLP for 2 hours after a combination of warm ischemia (20-420 min) and cold ischemia (120-600 min). The P/F ratio, vascular/airway parameters, shunt fraction, alveolar-arterial gradient and oxygenation index were measured at FiO2 of 0.21, 0.4 and 1.0 at 1 hour. All 16 cases were divided into two groups according to the relationship between P/F0.21 and P/F1.0; P/F0.21 < P/F1.0, P/F0.21 > P/F1.0.
  
  
  RESULTS
  The P/F ratio was not constant at different FiO2. The pattern of P/F0.21 < P/F1.0 was significantly associated with higher P/F ratio, higher pulmonary compliance, lower shunt fraction, lower alveoli-arterial gradient and lower oxygenation index compared to the pattern of P/F0.21 > P/F1.0 in porcine lungs (P < 0.05, each). In nonsuitable group, pulmonary vascular resistance was increased at FiO2 of 0.21 compared to FiO2 of 1.0.
  
  
  CONCLUSIONS
  The P/F ratio must be considered in combination with the FiO2. The relationship between P/F0.21 and P/F1.0 might be a complementary indicator of lung function in cellular EVLP.
authors.affiliation: 1 Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH. 2 Department of Thoracic and Cardiovascular Surgery, Cleveland Clinic, Cleveland, OH. 3 Transplant Center, Cleveland Clinic, Cleveland, OH. 4 Department of Outcomes Research and Center for Critical Care, Cleveland Clinic, Cleveland, OH.
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Okamoto
authors.forename: David
authors.initials: D
authors.lastname: Wheeler
authors.forename: Qiang
authors.initials: Q
authors.lastname: Liu
authors.forename: Cristiano
authors.initials: C
authors.lastname: Quintini
authors.forename: J Steven
authors.initials: JS
authors.lastname: Hata
authors.forename: Kenneth R
authors.initials: KR
authors.lastname: McCurry
mesh_terms: D000818:Animals; D001784:Blood Gas Analysis; D003657:Decision Making; D004195:Disease Models, Animal; D005112:Extracorporeal Circulation; D008168:Lung / Q000098:blood supply*; D016040:Lung Transplantation; D010100:Oxygen / Q000097:blood*; D010477:Perfusion / Q000379:methods*; D011659:Pulmonary Gas Exchange; D013552:Swine; D014655:Vascular Resistance / Q000502:physiology*; D052096:Warm Ischemia / Q000379:methods
chemical_list: D010100:Oxygen