Uncontrolled donation after circulatory death and liver transplantation: evidence and unresolved issues.

This review aims at summarizing the available evidence on liver transplantation from uncontrolled Donation after Circulatory Death (uDCD) on differences in protocols, donor management, in and ex vivo perfusion techniques from center to center. Uncontrolled DCDs represent an unique, complex model of ischemia-reperfusion injury, so far not completely understood. Nevertheless, results on liver transplantation from uDCDs are promising in terms of long term graft survival. True difficulties still remain since common/shared protocols are not achievable due to legal differences between countries (i.e. no touch period duration). To date, there is no reliable metrics to determine whether a liver is safe to be ex situ perfused or to be transplanted since existing criteria, as stated by investigators themselves, are so far arbitrary. Values and kinetics of transaminanes during normothermic regional perfusion (nRP) should not considered absolute contraindication at least for ex vivo perfusion. Intraoperative evaluation at organ recovery remains pivotal since macroscopic alterations (i.e. hepatic rupture, an abnormal appearance of gall bladder and choledocus) still represent contraindications for organ retrieval. Concerning ex vivo perfusion, the debate is still open, since the choice of type of machine perfusion (mainly hypothermic vs normothermic) varies from center to center, mainly relying to the single center experience (especially in controlled DCD), surgeons' believes and/or criteria translated from animal models.