Liver Assist Devices
for treatment of liver failure
Artificial Liver Support
Artificial detoxification uses methods such as filtration and adsorption to cleanse the blood without the use of hepatocytes. Some of the techniques used include hemodiafiltration, hemoperfusion, plasmapheresis, and hemodialysis. Unfortunately, these devices currently do not benefit survival though toxins are removed. To clear the blood of albumin-bound, hydrophobic substances with dialysis techniques, adsorbent or acceptor substances are necessary to enhance mass exchange. Albumin is one of the potential acceptor substances.
The Molecular Adsorbents Recirculation System (MARS) created by Teraklin of Germany is a detoxification system based on albumin dialysis. A high-flux hemodialysis filter is used to separate an patient blood. Clean human albumin acts as the acceptor for the toxins and is partly regenerated by passing an anion exchanger and a charcoal adsorber in a closed circuit.
MARS System
Single-Pass Albumin Dialysis (SPAD) is a similar method of detoxification using albumin dialysis. Standard renal replacement therapy machines are used without a perfusion pump system and blood is filtered through a hollow fiber hemodiafilter. The other side of the filter membrane is cleansed with an albumin solution which is discarded. The mechanism is similar to the MARS system; however the albumin solution is not regenerated.
When SPAD and MARS were compared for detoxification capacity, SPAD showed a significantly greater reduction of ammonia and bilirubin. Performance between the two systems was similar regarding other water-soluble substances and the reduction of bile acids.
The Prometheus system developed by Fresenius Medical Care in Germany is a device that combines high-flux hemodialysis with direct albumin adsorption. The adsorbers have the ability to separate and bind the toxins found in the albumin. The Prometheus system has shown improved outcomes over SPAD and MARS. However, due to its limited detoxifying capability it has not contributed to increased patient survival.
Prometheus System
Bioartificial Liver Support >