Emerging Innovations in Liver Preservation and Resuscitation.

The availability of marginal liver grafts represents a potential resource of orthotopic liver transplantation (OLT) in the era of organ shortage. However, an increased susceptibility to ischemia-reperfusion injury results in the increased risk for primary nonfunction and biliary complications. Novel methods of organ preservation and resuscitation are under investigation to improve outcomes of OLT with the use of marginal grafts. Machine perfusion (MP) in OLT is categorized based on the temperature setting. Hypothermic MP minimizes oxygen demand and uses single- or dual-vessel infusion with or without oxygenation. Normothermic MP increases the metabolic rate to the physiologic level, and requires dual-vessel infusion with a higher blood flow rate with oxygenation typically by blood as an oxygen carrier. Midthermic or subnormothermic MP uses medium temperature settings to allow metabolic activity to maintain cellular integrity as well as decrease oxygen demand. Since 2010, a total of 9 clinical trials have investigated the safety and feasibility of hypothermic and normothermic MP. The results suggest that the incidence of primary nonfunction was minimal even when marginal grafts were used. Organ preservation time could be reasonably increased. MP offers an opportunity to assess the viability and time to apply therapeutic interventions. This review highlights the history of MP, mechanisms of different temperature settings in MP, and recent large animal studies and clinical trials in OLT.