Red blood cell damage during normothermic liver perfusion: A hidden barrier to graft assessment?

Abstract

Background: Normothermic machine for liver perfusion (NMP) has emerged as a promising technique for dynamic preservation and functional assessment of liver grafts. However, red blood cell hemolysis is a frequently underestimated complication that may impair the interpretation of viability metrics. This study aims to determine the impact of rising free hemoglobin levels (fHb) on hepatic perfusion during NMP.

Materials and methods: Fifteen healthy female porcine livers were perfused for 18 hours using a NMP circuit primed with autologous whole blood. Hourly measurements included fHb levels, total hepatic, portal, and arterial flows, as well as biochemical parameters. Correlations between fHb and perfusion parameters were evaluated using Spearman's rank test.

Results: All livers were successfully perfused for 18 h. Free hemoglobin levels progressively increased over time. Significant inverse correlations were observed between fHb and portal vein flow (ρ = -0.772) and total hepatic flow (ρ = -0.650). Among biochemical markers, only GGT and CK showed positive correlations with fHb.

Conclusion: Progressive hemolysis during NMP is associated with impaired hepatic perfusion, affecting the portal system, and correlates with selective biochemical injury markers. These findings highlight the need for systematic monitoring of fHb in NMP protocols to ensure viability assessment and optimize graft preservation.