A Clinical Comparison of Two Different Oxygen Carriers for Combined Hypothermic and Normothermic Machine Perfusion of High-risk Donor Livers

Abstract

Purpose: Ex-situ normothermic machine perfusion (NMP) is increasingly used for pretransplant viability assessment of high-risk donor livers. When applied after static cold storage (‘back-to-base’), a short period of hypothermic oxygenated machine perfusion (HMP) prior to NMP reduces ischemia-reperfusion injury during NMP. Excellent results have been reported after combined HMP and NMP, using a single perfusion solution containing an hemoglobin-based oxygen carrier (HBOC). We aimed to determine whether similar results can be obtained with a perfusion solution containing red blood cells (RBC) instead of HBOC. Methods: In a prospective observational cohort study, sequential HMP and NMP was applied in 50 nationwide discarded donor livers in the Netherlands. The first 18 procedures were part of a prospective clinical trial with a HBOC-based perfusion solution for both HMP and NMP (www.trialregister.nl; NTR5972). The subsequent 32 procedures were performed using Belzer Machine Perfusion Solution (MPS) for HMP, followed by an RBC-based perfusion solution for NMP. Results: A total of 50 consecutive HMP-NMP procedures were included. All but two livers were derived from donation after circulatory death donors, with a median donor risk index of 2.83 (IQR 2.51-3.09) and median donor age of 63 years (IQR 53-71). After viability assessment during NMP, 12 livers in the HBOC-group were transplanted versus 18 in the RBC-group (utilization rate 67% versus 55%, P=0.42). One-year graft and patient survival were 92% and 100% in the HBOC-group versus 94% and 100% in the RBC-group, resp. (P=0.96 and P=1.00). Post-transplant cholangiopathy occurred in one patient (3%). There were no differences in other post-transplant outcomes among the two groups. Conclusion: Ex-situ machine perfusion using sequential HMP-NMP for resuscitation and viability assessment of high-risk human donor livers results in excellent transplant outcomes, irrespective of the type of oxygen carrier used.