A novel concept for evaluation of pulmonary function utilizing PaO2/FiO2 difference at the distinctive FiO2 in cellular ex vivo lung perfusion-an experimental study

For more accurate lung evaluation in ex vivo lung perfusion (EVLP), we have devised a new parameter, PaO2/FiO(2) ratio difference (PFD); PFD1-0.4 = P/F ratio at FiO(2) 1.0 - P/F ratio at FiO(2) 0.4. The aim of this study is to compare PFD and transplant suitability, and physiological parameters utilized in cellular EVLP. Thirty-nine human donor lungs were perfused. At 2 h of EVLP, PFD1-0.4 was compared with transplant suitability and physiological parameters. In a second study, 10 pig lungs were perfused in same fashion. PFD1-0.4 was calculated by blood from upper and lower lobe pulmonary veins and compared with lobe wet/dry ratio and pathological findings. In human model, receiver operating characteristic curve analysis showed PFD1-0.4 had the highest area under curve, 0.90, sensitivity, 0.96, to detect nonsuitable lungs, and significant negative correlation with lung weight ratio (R-2 = 0.26, P < 0.001). In pig model, PFD1-0.4 on lower and upper lobe pulmonary veins were significantly associated with corresponding lobe wet/dry ratios (R-2 = 0.51, P = 0.019; R-2 = 0.37, P = 0.060), respectively. PFD1-0.4 in EVLP demonstrated a significant correlation with lung weight ratio and allowed more precise assessment of individual lobes in detecting lung edema. Moreover, it might support decision-making in evaluation with current EVLP criteria.