Only two devices for liver dialysis are FDA approved for acute hepatic encephalopathy due to decompensation of chronic liver disease, fulminant hepatic failure and drug overdose and poisonings so far.
Albumin Dialysis
The most promising non-biologic liver support therapies combine detoxification of water-soluble and (albumin) protein-bound toxins in a dialysis system, such as albumin dialysis systems. Beneficial effects on plasma toxin levels were observed in non-controlled studies. Only one treatment until now showed significantly improved survival in a controlled trial of a subgroup of patients with hepatorenal syndrome.
Most dialysis systems are Hollow Fiber Adsorbers consisting of two separate dialysis circuits. The first circuit consists of human serum albumin, is in contact with the patient's blood through a semi permeable membrane and has two special filters to clean the albumin after it has absorbed toxins from the patient's blood. The second circuit consists of a hemodialysis machine and is used to clean the albumin in the first circuit, before it is recirculated to the semi permeable membrane in contact with the patient's blood. The system can remove a number of toxins, including ammonia, bile acids, bilirubin, copper, iron and phenols.
The success of OLT has demonstrated the importance not only of detoxification, but also metabolic functions in patient outcome. Because these functions can be carried out by hepatocytes, more is expected from biologic liver support systems.
Powdered Sorbent Liver Dialysis
Some liver-assist devices employ hemodiabsorption, the dialysis of blood against powdered sorbents, to selectively remove numerous small molecular weight toxins of hepatic failure. Liver dialysis resulted in physiologic and neurologic improvement of patients with AHE. Liver dialysis significantly improved the incidence of positive outcomes of A-on-C patients, but had an insignificant improvement in the outcome of patients with FHF.
An add-on with powdered sorbent surrounding plasmafilters combines hemodiabsorption with push-pull sorbent-based pheresis. It adds the capability to remove bilirubin and other strongly protein-bound toxins from treated patients and may be of clinical benefit in the management of patients with the most severe hepatic failure and encephalopathy, including patients with FHF or concomitant sepsis. The system clears creatinine, aromatic amino acids, unconjugated bilirubin and cytokines.
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