Liver failure occurs when loss of hepatic parenchymal function exceeds the capacity of hepatocytes to regenerate or repair liver injury. Acute liver failure is characterized by jaundice and prolongation of the prothrombin time in the context of recent acute liver injury, with hepatic encephalopathy occurring within 8 weeks of the first onset of liver disease. Acute-on-chronic liver failure is characterized by hepatic and/or extrahepatic organ failure in patients with cirrhosis associated with an identified or unidentified precipitating event. The commonest causes of acute liver failure are acute viral hepatitis and drugs. Acute-on-chronic liver failure is most commonly precipitated by infection, alcohol abuse, and superimposed viral infection. The main clinical manifestations are hepatic encephalopathy, coagulopathy, jaundice, renal dysfunction, and haemodynamic instability. Infection and systemic inflammation contribute to pathogenesis and critically contribute to prognosis. Specific therapy for the underlying liver disease is administered when available, but this is not possible for most causes of liver failure. Treatment is predominantly supportive, with particular emphasis on (1) correction or removal of precipitating factors; (2) if encephalopathy is present, using phosphate enemata, nonhydrolysed disaccharide laxatives, and/or rifaximin; (3) early detection and prompt treatment of complications such as hypoglycaemia, hypokalaemia, cerebral oedema, infection, and bleeding. The onset of organ failure should prompt discussion with a liver transplantation centre. The mortality of acute liver failure (without liver transplantation) is about 40%. Patients with acute liver failure who do not develop encephalopathy can be expected to recover completely. Those who recover from an episode of acute-on-chronic liver failure should be considered for liver transplantation because otherwise their subsequent mortality remains high.
