The Emerging Role of Viability Testing During Liver Machine Perfusion

Abstract

The transplant community continues to be challenged by the disparity between the need for liver transplantation and the shortage of suitable donor organs. At the same time, the number of unused donor livers continues to increase, most likely attributed to the worsening quality of these organs. To date, there is no reliable marker of liver graft viability that can predict good posttransplant outcomes. Ex situ machine perfusion offers additional data to assess the viability of donor livers before transplantation. Hence, livers initially considered unsuitable for transplantation can be assessed during machine perfusion in terms of appearance and consistency, hemodynamics, and metabolic and excretory function. In addition, postoperative complications such as primary nonfunction or posttransplant cholangiopathy may be predicted and avoided. A variety of viability criteria have been used in machine perfusion, and to date there is no widely accepted composition of criteria for clinical use. This review discusses potential viability markers for hepatobiliary function during machine perfusion, describes current limitations, and provides future recommendations for the use of viability criteria in clinical liver transplantation.

Outcome of liver transplantation with grafts from brain-dead donors treated with dual hypothermic oxygenated machine perfusion, with particular reference to elderly donors

“…For these grafts, upfront hypothermic or normothermic 52 machine perfusion using a transportable device could represent a valuable option, whereas viability assessment appears to be of particular interest when a period of initial SCS in unavoidable. [53][54][55][56][57] In settings where upfront machine perfusion is difficult to implement, a sequential approach including HOPE/D-HOPE followed by normothermic machine perfusion would combine the benefit of hypothermic perfusion on mitochondrial respiration with the possibility of viability testing during normothermic perfusion. 56 Graft damage sustained during initial SCS represents a major issue of any end-ischemic approach, as there may be a threshold of hepatocyte and/or cholangiocyte injury that cannot be corrected despite optimal MP.…”

“…As steatotic grafts might suffer from substantial damage even during a relatively brief initial SCS, an end‐ischemic approach might not always be sufficient. For these grafts, upfront hypothermic or normothermic 52 machine perfusion using a transportable device could represent a valuable option, whereas viability assessment appears to be of particular interest when a period of initial SCS in unavoidable 53‐57 . In settings where upfront machine perfusion is difficult to implement, a sequential approach including HOPE/D‐HOPE followed by normothermic machine perfusion would combine the benefit of hypothermic perfusion on mitochondrial respiration with the possibility of viability testing during normothermic perfusion 56 …”

Introduction of the Concept of Diagnostic Sensitivity and Specificity of Normothermic Perfusion Protocols to Assess High‐Risk Donor Livers

“…( 11 ) The emerging opportunity to objectively assess organ transplantability brings a ground‐breaking advancement but also adds another layer of complexity. ( 12 ) The currently used protocols were developed on small discarded liver series, without clearly defined inclusion and exclusion criteria. With the cumulatively growing experience with NMP viability testing, the initially proposed benchmarks are now being updated and extended.…”

The Need to Update Endpoints and Outcome Analysis in the Rapidly Changing Field of Liver Transplantation

“…24,168 This is attractive, since parameters predicting BCs can be assessed during MP. [169][170][171] Furthermore, pharmacological interventions to mitigate reperfusion injury and stimulate regenerative capacity of progenitor biliary cells are novel tactics applied during MP. 168,172 The limitation of BCs as an endpoint lies with the definition of BCs and ITBLs specifically.…”