Fluidized Bed Adsorbent Systems for Extracorporeal Liver Support

Abstract

Acute liver failure based on acute-on-chronic liver failure (AoCLF) or on acute severe damage of the liver caused by different etiologies includes complex mechanisms resulting in severe disturbances of principle liver functions. In order to compensate the liver's function of detoxification as efficiently as possible, fluidized bed absorbent systems have been designed. In these systems, small particles with specific adsorption properties for toxins related to acute liver failure are applied. A special technology based on adsorbents in suspension has been developed under the guidance of our group and is prepared for clinical application during the coming year. This technology is called microspheres-based detoxification system (MDS) and is based on microadsorbents with a diameter of 1-10 microm which are recirculated in suspension. The safety of the MDS is guaranteed by the use of fluorescently labeled magnetic microparticles, which in case of a membrane-leakage are detected in the blood circuit by an optical system equipped with a magnetic trap. In vitro tests with two kinds of microadsorbents (a combination of a hydrophobic neutral resin and an anion exchange resin) showed excellent efficiency of the system with respect to adsorption capacity as well as to the kinetics of elimination of albumin-bound substances (e.g. unconjugated bilirubin or cholic acid) and of non-protein-bound substances (e.g. phenol). Moreover, using a plasma filter or the Albuflow filter as membrane filters in the blood circuit, the MDS technology offers the possibility to remove inflammatory mediators such as tumor necrosis factor-alpha (TNF) by additional use of specific adsorbents.