NONBIOLOGICAL LIVER SUPPORT - HISTORIC OVERVIEW

An effective hepatic assist system could serve as a bridge to transpla ntation or to treat acute or chronic hepatic failure. Early nonbiologi cal approaches focused on the removal of low molecular weight toxins b y dialysis or hemoperfusion, such as over charcoals or resins. This ap proach led to clinical trials that showed varying degrees of success. Introduction of more porous membranes and blood separation technologie s stimulated the development of plasma exchange, on-line plasma fracti onation technologies with sorbents and membranes, and other schemes of sorbent-blood interactions based on the principles of dialysis and he mofiltration with sorbent perfusion. Although detoxification of blood has improved the prognosis for acute liver failure, key issues of when to initiate treatment and by which method need to be resolved. In chr onic liver disease, blood detoxification can be applied in patients in tractable to conventional therapies and for some awaiting transplantat ion to relieve disease symptoms such as pruritus, jaundice, elevated b ile acids, hyperbilirubinemia, endotoxemia, and hypercholesterolemia. Although biological support is considered the ideal, nonbiological tec hniques can be useful because hepatocytes possess a regenerative capac ity and temporary support is helpful. Available nonbiological liver su pport technologies can substitute for select liver functions in acute and chronic disease.