**6. Specific organs**

## **6.1 Liver**

The liver has vital functions including plasma protein synthesis, hormone production, detoxification, decomposition of red blood cells, and regulation of glycogen storage. Due to these important functions, liver failure poses a threat to life. Historically, liver transplantation is second to kidney transplantation. Liver transplantation is a definitive treatment modality for acute liver failure and endstage chronic liver disease. The shortage of organ supply has initiated the usage of new therapeutic systems to reduce mortality and bridge patients to transplantation.

Albumin dialysis, plasmapheresis, column perfusion, and hybrid devices are among the instruments that have been used to compensate for liver function.

Artificial liver support systems may replace the failing functions of the organ and therefore time is gained for liver regeneration or transplantation. Artificial liver support systems are expected to detoxify, replenish plasma proteins, and reverse the inflammatory process. Among the artificial liver support systems, molecular adsorbent recirculating system [MARS], therapeutic plasma exchange [TPE], single- pass albumin dialysis [SPAD], and Prometheus can be named. MARS uses albumin dialysis to replace the detoxification function of the liver while TPE improves survival in patients with acute liver failure. MARS and TPE improve systemic hemodynamics and the grade of hepatic encephalopathy [36, 37].

Extracorporeal liver support systems are either cell- based [biological] or noncell-based. Non- cell-based systems include high volume plasma exchange and albumin dialysis. Bioartificial liver systems improve neurologic function, reduce intracranial pressure and increase cerebral perfusion pressure Biological extracorporeal liver support systems aim to support the failing liver through detoxification [38].

Shen Yi and colleagues have performed a time-series-based meta-analysis of randomized clinical trials and observational studies that examined differences in mortality in acute-on-chronic liver failure patients treated with artificial liver support systems. The results revealed that an artificial liver support system had reduced the risk of short-term [1–3 months] mortality for patients with acute-onchronic liver failure by nearly 30%. As the results of the meta-analysis suggested, an artificial liver support system might reduce medium-term [6 month-1 year]
