Comparative analysis of in situ versus ex situ perfusion on micro circulation in liver procurement--an experimental trial in a porcine model

Introduction: The Achilles heel of liver transplantation remains the biliary system. The crucial step for liver preservation is effective rinsing and perfusion of the peribiliary plexus (PBP). Due to the physiology of the vascular tree, it seems almost impossible to achieve the necessary physiologic ranges of pressure and flow by the in situ perfusion technique. We investigated the role of additional ex situ perfusion via the hepatic artery in this animal model.

Materials and methods: Fifteen German Landrace pigs underwent standardized multiorgan procurement. In situ perfusion and additional ex situ perfusion were performed consecutively. Meanwhile the external pressure applied to the perfusion system was increased stepwise. To visualize the effects on the liver parenchyma and PBP, we administered colored microparticles (MPs; 10 μm). Frozen sections of the explanted liver were studied histologically by quantitative evaluation of the MPs.

Results: Ex situ perfusion was able to build up significantly higher values of pressure (P < .001) and flow (P < .001) than in situ perfusion. Those of ex situ perfusion reached physiological levels under application of an external pressure of 200 mm Hg. Considering the liver parenchyma, significantly higher amounts of MPs originating from ex situ perfusion were evident (P < .001) and PBP (P < .001).

Conclusion: MPs provide an appropriate tool to determine organ perfusion quantitatively in experimental models. Considering flow, pressure, and microcirculation, we consider that additional ex situ perfusion of the liver is more effective than in situ perfusion.