Liver support in acute liver failure

Detoxification as a treatment goal in hepatic failure

Acute liver failure (ALF) is a dramatic clinical syndrome with high mortality because of cerebral oedema (type A hepatic encephalopathy) and multi-organ failure. With intensive care medicine and emergent liver transplantation being the mainstay of treatment, alternatives to transplantation are increasingly needed. Ammonia has been recognised as a major toxin in patients with ALF. It can be effectively removed by haemodialysis, haemofiltration and artificial liver support (a combination of extracorporeal toxin absorption and haemodialysis). Previous studies of extracorporeal detoxification, however, have either not specifically targeted ammonia or were hampered by poor biocompatibility and obsolete pathophysiological assumptions, ultimately failing to improve the prognosis. Moreover, most patients were treated only late after the emergence of advanced HE and multi-organ failure, while detoxification should prevent these complications. Acute-on-chronic liver failure (AOCLF) occurs in the setting of chronic liver disease and has an equally poor prognosis. Here, the goals of extracorporeal blood detoxification are renal support and haemodynamic stabilisation in order to support recompensation. Patients with AOCLF, unfortunately, are at a risk for treatment-related complications including bleeding, thrombocytopenia, hypotension and acute renal failure, making biocompatibility a critical issue. Peritoneal dialysis could possibly emerge as a more biocompatible way of treating refractory hepatorenal syndrome. This article will critically analyse the pathophysiological concepts and goals of extracorporeal detoxification in acute and chronic liver diseases.

Bridging to transplantation in acute liver failure in a 7-month-old infant

BACKGROUND

Acute liver failure (ALF) in children is a rare but often fatal event. At present, liver transplantation is the only successful therapy in most cases. In the face of deteriorating hepatic encephalopathy in these children, some bridging therapy using artificial detoxification can be necessary to enable successful transplantation. In adults, albumin dialysis using the molecular absorbent recycling system (MARS) has been described as effective for bridging to liver transplantation.

CASE REPORT

A previously healthy 7-month-old infant was admitted with ALF due to autoimmune hepatitis. King's College criteria for children with ALF indicated the need for transplantation (bilirubin 13.7 mg/dl, leukocytes 18,980/mm3, INR 5.83, age<2 years). Despite moderate hyperammonemia (75 microm/l) along with the development of pneumonia, the child deteriorated hemodynamically and neurologically, showing grade III encephalopathy proven by EEG. Albumin dialysis using MARS was used to bridge 36 hours to successful living-donor split-liver transplantation, and resulted in improvements in EEG, plasma levels of amino acids and hemodynamics. Twenty-four months after transplantation the child shows normal liver function and normal neuropsychological development. The explanted liver showed 80 % tissue destruction from autoimmune hepatitis.

CONCLUSION

Albumin dialysis as described can be used successfully in infants < 1 year old for bridging to liver transplantation in cases of acute hepatic failure with deteriorating encephalopathy.

Acute liver failure

Acute liver failure is a rare and life-threatening clinical syndrome following severe hepatic injury. Depending on the rapidity of its development, two distinct complications contribute to a high mortality: in hyperacute liver failure, rapid development of massive hepatic necrosis and apoptosis gives rise to severe hyperammonemia, hepatic encephalopathy and life-threatening cerebral edema. The high risk of cerebral herniation requires early listing for emergency liver transplantation. Patients with hyperacute liver failure surviving the initial episode of cerebral edema have a substantial potential for hepatic recovery. If progressive hepatic failure develops more slowly, astrocytic osmoregulation prevents cerebral herniation in most instances. Unfortunately, these patients have a small potential of hepatic regeneration and transplantation should be performed before renal failure, sepsis or multiorgan failure emerge. Experimental treatment methods including detoxification by artificial or bioartificial liver support or by stimulating hepatic regeneration are currently evaluated. Recognition of ammonia toxicity has stimulated the search for early ammonia-lowering strategies and strongly renewed the interest in dialytic therapies. Anti-apoptotic interventions are among the most promising pharmacological options for the near future.