[Extracorporeal liver support of liver failure]

Extracorporeal liver support can be classified into cell-free, artificial methods (artificial liver support, ALS) and cell-based bioartificial methods (bioartificial liver support, BLS). ALS improves biochemical parameters of liver failure by the simultaneous removal of protein-bound and water-soluble substances. Here, the MARS therapy belongs to the most studied methods with a proved beneficial effect on hepatic encephalopathy (HE), hepatorenal syndrome (HRS) or hyperbilirubinemia. However, a general survival advantage of any liver support for liver failure has not been shown yet and is restricted to meta-analyses or patient subgroups. There are no prospective randomized studies on the treatment of liver failure by intoxication. However, several case series report positive treatment effects using the MARS system, particularly in mushroom poisoning or acetaminophen intoxication. In acute liver failure (ALF) studies, the usage of BLS showed no survival advantage. Using ALS systems, a positive effect on mortality could be demonstrated in patient subgroups after several consecutive MARS therapies. The first randomized controlled trial demonstrating a survival benefit used large-volume plasmapheresis. Apparently, immunomodulatory and hemodynamic effects of the treatment play a crucial role in this context. In patients with acute-on-chronic liver failure (ACLF) accompanied by hyperbilirubinemia without any further organ failure (singular hepatic dysfunction), prognostic favorable effects by using a BLS system have been shown. However, once other extrahepatic organ systems are affected, indicating a progressive transition to multi-organ failure, a survival advantage could be achieved with the MARS and Prometheus system. Decisive for a successful therapy is the exact indication of the respective liver dialysis procedure for this very heterogeneous disease. Future studies are needed to define more accurate patient selection criteria for each liver support.