**6. Conclusion**

330 Liver Transplantation – Basic Issues

transplant greatly exceeds the supply of donor livers, and many patients either die while awaiting a donor or become too critically ill to qualify for transplant. The discrepancy in the supply and demand for organs, and the high pre-transplant mortality and posttransplant morbidity have generated interest in surgical techniques to avoid transplantation and chronic immunosuppression, and support systems to serve as a bridge to transplant or spontaneous recovery. Examples of these include auxiliary liver transplantation and liver

An alternative to traditional orthotopic liver transplantation for patients with ALF is that of auxiliary transplant, based on the well-established regenerative capacity of hepatocytes. Unlike traditional transplantation, where native hepatectomy is performed simultaneously with donor engraftment, in auxiliary transplants, the patient's native liver is left surgically intact, while a partial or smaller sized donor graft is transplanted. This procedure allows assumption of hepatic functions by the donor graft, resolution of multiorgan failure, and clinical stabilization of the patient. In turn, the native liver benefits both from additional time, as well as improved physiological conditions, thus maximizing the opportunity for hepatic regeneration. Younger patients (below 40 years of age) with ALF due to viral hepatitis or acetaminophen toxicity appear to have the best outcome with this strategy. After native hepatic function is demonstrated, the auxiliary graft can be removed, but is most frequently allowed to atrophy by withdrawal of immunosuppression. Complete cessation of immunosuppression can be achieved in many

Mechanical hepatic support systems serve as a bridge to transplant in patients with ACLF, and as a bridge to transplant or spontaneous recovery in patients with ALF. These systems are designed to reproduce the detoxifying functions of the liver, and mimic the principles upon which renal replacement therapy is based. While conventional renal dialysis removes small toxins and water-soluble toxins, the liver detoxifies larger toxins and protein-bound toxins. Dialysis of these larger and protein-bound toxins through unbound human albumin

Several artificial systems have been developed utilizing albumin dialysis. The Molecular Adsorbent Recirculating System (MARS), Single Pass Albumin Dialysis (SPAD), and Prometheus are examples; of these, MARS has been the most widely studied. MARS has been utilized for management of hepatic encephalopathy, cerebral edema, hepatorenal syndrome, treatment of drug overdoses, and as a bridge to transplantation (*Mitzner, 2011*). MARS has been shown to improve hemodynamic parameters and organ perfusion during circulatory collapse, and has been associated with improvement in hepatic synthetic function. For patients with ACLF, MARS can provide temporarily relief of intractable

Bioartificial systems work similarly to artificial systems to remove toxins by albumin dialysis, but additionally utilize human or porcine hepatocytes to mimic hepatic synthetic

assist devices.

**5.1 Auxiliary liver transplantation** 

patients (*Boudjema et al., 1995*).

pruritis and fatigue.

**5.2 Artificial and bioartificial hepatic support systems** 

solutions allows the removal from the patient's circulation.

Acute liver failure and acute on chronic liver failure are complex illnesses often culminating in multi-organ failure, and require meticulous care in the pre-transplant phase. Mortality in the absence of transplantation is high, but the advent of multi-disciplinary critical care has significantly improved the outcome in these disease processes. A protocolized approach to the intensive care management of patients prior to liver transplantation will favorably impact the pre-transplant and post-transplant status of these patients.
