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Table 9.3. Criteria for transplantation of acute liver failure

Kings College Criteria5

• Acetaminophen toxicity

• ph < 7.30 (after hydration and regardless of degree of encephalopathy)

creatinine >3mg/dl Encephalopathy III-IV

• Non-acetaminophen etiology

• INR >6.5 irrespective of degree of encephalopathy or 3 of the following five criteria

Etiology: nonA-E hepatitis, drugs

Duration of jaundice before encephalopathy >7 days

Serum bilirubin >17.5 mg%. Clichy Criteria6

• Factor V <20% (age <30 years) or 30% (age >30 years)

• Confusion and/or coma

Table 9.4. Options for hepatic support

Artificial liver support devices Bioartificial livers Hepatocyte transplantation Extracorporeal liver perfusion Artificial liver support systems going clinical trials, utilizes dialysis fluid containing charcoal and a cation exchange resin to bind toxic substances in the blood. A pilot study performed in acute liver failure patients showed that this system was well tolerated and could produce biochemical improvements, although its ability to reverse the progression to terminal brain swelling has not be demonstrated. A second support device, the molecular absorbents recirculating system (MARS), consists of a dialysis system where the polysulphone membrane is impregnated with albumin and the dialysate enriched with albumin to facilitate the removal of toxic metabolites.8 A third artificial liver support system, the microsphere based detoxification system (MBS), involves plasma recirculation at very high flow rates with all flow being exposed to particle size absorbents, which provide a large surface area for absorption.9

Bioartificial Liver Support Systems

Another approach consists of a Bioartificial Liver (BAL). In this system, plasma obtained with a centrifugal plasma separator is subsequently perfused through microcarrier bound porcine hepatocytes.10 This device has been studied clinically with some promising early results. It is difficult to determine what role the hepatocytes played in these instances since a charcoal column is also included in the circuit. An alternative approach, the Extracorporeal Liver Assist Device (ELAD), utilizes blood perfusion through hollow fiber membranes surrounded by cells of a human tumor cell line (C3A).11

Hepatocyte Transplantation

More recently, hepatocyte transplantation has been used successfully to treat certain metabolic disorders12 and preliminary data indicate that it may also be effective in acute liver failure. However, the number of cryopreserved hepatocytes required to achieve success may limit the utility of this approach.

Extracorporeal Liver Perfusion

This approach overcomes many of the problems associated with the previous approaches including: a) the inability to support all the functions provided by the liver and b) inability to provide enough hepatic support to overcome the derangement associated with fulminant hepatic failure. Both human and porcine livers have been used successfully with this approach. Since the shortage of human livers remains the essential problem in patients with fulminant hepatic failure, the only human livers which will be available for this technique will be those of poor quality and that are not usable for transplantation.

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