Copyright ©The Author(s) 2021.
World J Gastroenterol. Sep 14, 2021; 27(34): 5727-5736
Published online Sep 14, 2021. doi: 10.3748/wjg.v27.i34.5727
Table 1 Potential benefits of the different modalities of machine perfusion of the liver on clinical studies

Safety and feasibility
Prevention of early allograft dysfunction
Prevention of biliary complications
Prolonged preservation time
Viability assessment
Therapeutic interventions
Normothermic regional perfusion1Yes[11,19,46]Yes[11,19,46]Yes[11,19,46]No data available yetYes[11,46]No data available yet
Normothermic machine perfusionYes[2,6,21,42,50,51]Yes[2,6,42]No data available yetYes[2,6]Yes[6,24,26,50,51]Yes[43]2
Subnormothermic machine perfusionNo data available yetNo data available yetNo data available yetNo data available yetNo data available yetNo data available yet
Hypothermic machine perfusionYes[3,37]Yes[3,37]Yes[3,22,37]Yes[39]2Yes[34]No data available yet
Controlled oxygenated rewarmingYes[9,47]Yes[9,47]No data available yetNo data available yetNo data available yetNo data available yet
Combined modalities (HMP + NMP)Yes[14,15] No data available yetNo data available yetYes[39]2Yes[14,15] No data available yet
Ischaemia-free liver transplantation3Yes[12,48]Yes[48,49]No data available yetNo data available yetNo data available yetNo data available yet
Table 2 Parameters employed in clinical studies to assess the viability of donor organs before transplantation
Perfusate parameters
Bile parameters
Perfusion parameters
Watson et al[11]NRPWithin 2 h of NRP: Alanine transaminase up to 500 IU/L, providing no continued rise between the first and second hours
Muller et al[34]HMPAt least 1 h of HMP: Threshold at 10000 A.U. (100 ng FMN/mL perfusate) to refuse livers regardless of the use of a DCD or DBD liver
Watson et al[32]NMPNo timepoint defined: Changes in lactate, glucose, and transaminase concentrations and the ability of the liver to maintain perfusate pH without supplemental bicarbonate
Matton et al[26]NMPWithin 2.5 h of NMP: Bicarbonate concentration > 18 mmol/L, pH > 7.48, glucose concentration < 16 mmol/L, bile/perfusate glucose concentration ratio < 0.67, and LDH concentration < 3689 U/L
de Vries et al[14]NMPWithin 150 min of NMP: Lactate concentration within “normal” values (0.5-1.7 mmol/L); pH within normal values (7.35-7.45), without continuing sodium bicarbonate supplementationWithin 150 min of NMP: Cumulative bile production of ≥ 10 mL and ≥ 4 mL in the preceding hour. pH > 7.45
Mergental et al[6]NMPWithin 4 h of NMP: Lactate ≤ 2.5 mmol/L; and two or more parameters: pH ≥ 7.30; Evidence of glucose metabolismWithin 4 h of NMP: Evidence of bile productionWithin 4 h of NMP: HA flow ≥ 150 mL/min and PV flow ≥ 500 mL/min; and homogenous perfusion of the parenchyma
Cardini et al[50]NMPWithin 2 h of NMP: Rapid decrease and maintenance of lactate to physiological levels, maintenance of physiological pH values without sodium bicarbonate supplementation, and glucose consumption. Remarkably high transaminases and LDH levels and a severe rise of these parameters are deemed warning signalsWithin 2 h of NMP: Bile production and bile pH are indicators for bile duct viability and function
Reiling et al[51]NMPWithin 2 h of NMP: Lactate clearance to < 2 mmol/L. Within 4 h of NMP: Evidence of glucose metabolism. Maintenance of physiological pH without continuing administration of sodium bicarbonateWithin 4 h of NMP: Bile production (no lower limit)Within 4 h of NMP: Stable hepatic arterial and portal venous flows. Homogeneous graft perfusion with soft consistency of parenchyma