Early effects of the ex vivo evaluation system on graft function after swine lung transplantation

Objectives: Ex vivo lung evaluation (ex vivo) has been developed as a useful method by which to assess lungs from donation-after-cardiac death (DCD) donors prior to transplant. However, the safety of the ex vivo circulation itself with respect to grafts has not been fully investigated. The aim of this study is to evaluate the effects of the ex vivo circuit using a swine lung transplant model. Methods: Lungs with or without 2-h warm ischemia were used. To assess post-transplant graft function, the left lung was transplanted after 2-h ex vivo or cold preservation; blood gas analysis of the left pulmonary vein (partial pressure of oxygen, PO ₂) was performed during the 6-h post-transplant follow-up period. Data were compared between the ex vivo (+) and ex vivo (-) groups. Results: Partial pressure of oxygen/ inspired oxygen fraction (PO ₂/FiO ₂) in the ex vivo (-) group was significantly greater than that in the ex vivo (+) group until 3h after transplant. The PO ₂/FiO ₂ levels in both groups then increased and became similar at 6h after transplant, regardless of whether ischemic or non-ischemic lungs (p<0.001 and p=0.004, respectively) were used. Conclusions: Negative effects of the ex vivo system were limited and seen only in the immediate post-transplant period. Therefore, in DCD swine lung transplantation, the ex vivo system appears to be safe.