Extracorporeal Liver Support: Albumin Removal vs. Albumin Regeneration

摘要

With the development of clinically successful renal replacement therapies after World War II the idea of extracorporeal liver detoxification gained attractiveness as well. Small metabolites such as ammonia or bilirubin that accumulate during liver failure seemed to represent a group of "liver toxins" worth removing in order to improve the clinical status (Kiley 1956). Since then various techniques have been deployed, including both artificial (i.e. without liver cells or tissue) and bioartificial approaches. Among the artificial systems techniques based on plasma-exchange and plasma-adsorption were studied best. Lack of selectivity and/or efficacy of detoxification appeared as the major shortcoming of the plasma-treatments for liver failure (Mitzner 2002). An interesting new method of liver support is albumin dialysis. The concept is based on two observations, a) that human serum albumin is the major transport protein for hydrophobic metabolites and drugs (including the majority of all known "liver failure toxins") and b) that the albumin pool is overloaded in liver failure (Klammt 2007). Albumin dialysis was introduced clinically as the Molecular Adsorbent Recirculating System (MARS) in 1993 (Stange 1993). An albumin-containing dialysate attracts albumin-bound ligands, such as bilirubin, bile acids or nitric oxide, through the pores of a high-flux dialyzer. The albumin-dialysate is on-line regenerated by a combined dialysis- and adsorption procedure (including charcoal- and anion-exchanger-perfusion of the dialysate) (Mitzner 2001). This ensures both, good selectivity and clinically meaningful detoxification. A modification of albumin dialysis is the Single pass albumin dialysis (SPAD).