33. Feasibility study on hypothermic machine perfusion of human donor livers using a pressure controlled perfusion system: Initial results on single or dual-flow modalities

Abstract

Hypothermic machine perfusion (HMP) has shown superior results to conventional cold storage method in kidney preservation. Similar promising results have been reported for HMP of livers in large animal models; however data from human livers remain scarce. The aims of this study is to establish a reproducible method of HMP of human livers using a pressure controlled system, to assess if sterility can be maintained throughout the procedure, and evaluate modes of perfusion (artery alone, portal vein alone, or both simultaneously). 16 human livers rejected for transplant by all UK centres with appropriate consent for research were randomised into four groups. Group 1: 7 h cold storage and 1 h HMP through hepatic artery (HA) alone ( n = 4). Group 2: 7 h cold storage and 1 h HMP through hepatic artery (HA) and portal vein (PV) ( n = 4). Group 3: 7 h cold storage and 1 h HMP through PV ( n = 4). Group 4: 8 h simple cold storage (CS). A pressure controlled system where flow is automatically adjusted according to resistance to maintain a constant pressure (7 mmHg for PV and 30 mmHg for HA) was used, based on the Lifeport kidney machine using Belzers KPS perfusate. Livers were perfused at 4–8 °C using KPS solution under sterile conditions. Perfusion parameters (pressure, flow, resistance and temperature) were recorded every 15 min. Perfusate samples for microbial culture and sensitivity were taken before and after the perfusion. HA pressure of 30 mmHg and PV pressure of 7 mmHg were maintained throughout the perfusion. HA and PV flow ranged from 11 to 107 ml/min (average 59.5 ml/min) and 39–199 ml/min (average 96.2 ml/min). HA and PV resistance ranged from 0.17 to 1.99 (average 0.71) and 0.07 to 0.17 mmHg/ml/min (average 0.08). Temperature was maintained between 4 and 8 °C using the supplied heat exchanger. Culture and sensitivity results from the perfusate showed that sterility was maintained throughout the procedure. Our technique proved to be a reliable and reproducible method of donor liver HMP. Resistance in HA was higher than in PV, while flow in the HA was less than the PV. Sterility could be maintained throughout the perfusion process. These data provide a basis for further evaluation of liver HMP as a method for preserving livers during clinical hepatic transplantation.