Viability assessment of livers donated after circulatory determination of death during normothermic regional perfusion

Background: Abdominal normothermic regional perfusion (A-NRP) allows in-situ reperfusion and recovery of abdominal organs metabolism in donors after circulatory death (DCD). Besides improving liver transplantation outcomes, liver injury and function can be assessed during A-NRP.Methods: To refine liver viability assessment during A-NRP, prospectively collected data of controlled DCD donors managed at our Institution between October 2019 and May 2022 were retrospectively analyzed. Baseline characteristics, procedural variables and A-NRP parameters of donors whose liver was successfully transplanted were compared to those of donors whose liver was discarded.Results: Twenty-seven donors were included and in 20 (74%) the liver was accepted (positive outcome). No differences between study groups were observed concerning baseline characteristics and warm ischemia times (WIT). Initial lactate levels were positively correlated with functional WIT (r(2) = 0.4, p = 0.04), whereas transaminase levels were not. Blood flow during A-NRP was comparable, whereas oxygen consumption (VO2) was significantly higher in the positive outcome group after 1 h. Time courses of lactate, AST and ALT were significantly different between study groups (p < 0.001). Donors whose liver was accepted showed faster lactate clearance, a difference which was amplified by normalizing lactate clearance to oxygen delivery (DO2) and VO2. Lactate clearance was correlated to transaminase levels and DO2-normalized lactate clearance was the parameter best discriminating between study groups.Conclusions: DO2-normalized lactate clearance may represent an element of liver viability assessment during A-NRP.