*Purpose: Lactate clearance provides important information regarding hepatocellular function during normothermic machine perfusion (NMP). Liver Maximum Capacity (LiMAx) measurements, using C¹³-Methacetin, are used to assess liver function prior to major oncologic resections. We evaluated the use of LiMAx to monitor liver function during long-term resuscitation using NMP and correlated it with the liver’s lactate clearing capacity.
*Methods: Seven discarded donor livers were subjected to 87 - 184 hours of NMP using blood-based perfusate, in a modified Liver Assist device with haemofiltration in circuit. Liver function was initially assessed by the perfusate lactate clearance criteria, in combination with 6-hourly sequential LiMAx measurements using fixed boluses of C¹³-Methacetin and recording the delta over baseline (DoB). In addition to this, every 24 hours we assessed the livers’ abilities to clear lactate following a bolus of sodium lactate solution to achieve perfusate lactate levels of 10 mmol/L.
*Results: The initial time to clear lactate below 2.5 mmol/L took 1.75 - 7.75 hours, and the median LiMAx value was 829 (range 325 - 3130) µg/kg/h. In well-functioning livers (defined as lactate clearance time <4 hours; Fig 1A) we observed a steep curve with high DoB peak (Fig 1B), whilst in poorly functioning livers (lactate clearance >4 hours; Fig 1C) they displayed a flat curve with low DoB peak (Fig 1D). Sequential LiMAx curves with similar character and amplitude throughout the 80-hour perfusion was consistent with preserved hepatocellular functioning (Fig 1E). In contrast, livers with declining LiMAx amplitudes and progressively flattening curves were associated with worsening hepatocellular function and eventual organ failure (Fig 1F).
*Conclusions: This is the first study demonstrating the use of LiMAx measurements to assess hepatocyte function and showing qualitative differences in the curve character during longitudinal monitoring of liver metabolic activity during long-term liver resuscitation using NMP.

George Clarke

Queen Elizabeth Hospital Birmingham / University of Birmingham

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