Does ex vivo vascular resistance reflect viability of non–heart-beating donor livers?

Abstract

Aims The use of non–heart-beating (NHB) donor livers is limited by a higher risk for primary nonfunction and the absence of methods to measure this risk. This study was designed to determine whether ex vivo vascular resistance of livers correlates with the length of warm ischemia (WI), and, thus, with viability of NHB livers. Methods Porcine livers were recovered after 0, 45, or 90 minutes WI. Livers were flushed by gravity and cold stored for 3 hours. Thereafter, livers were perfused at 4°C. Portal vein (PV) and hepatic artery (HA) vascular resistance were calculated during liver flush-out and during 24 hours of machine perfusion. Results During flush-out, PV and HA vascular resistance were higher among livers with longer WI times; however, only in the PV did the results reach statistical significance. During machine perfusion, PV vascular resistance was low from the start and remained fairly constant. In contrast, HA vascular resistance was higher at the start but gradually diminished to reach a more constant value after 4–6 hours. No correlation was observed between HA or PV vascular resistance and WI during machine perfusion. Conclusions The vascular resistance during ex vivo machine perfusion of NHB livers does not correlate with the extent of WI damage and, therefore, cannot predict organ viability.