Organ dysfunction and failure in liver disease.

Acute-on-chronic liver failure (ACLF) is a complex syndrome defined by the existence of different organ failures (OFs) in patients with chronic liver disease, mainly cirrhosis. Several definitions have been proposed to define the syndrome, varying in the grade of the subjacent liver disease, the type of precipitants and the organs considered in the definition. Liver, coagulation, brain, kidney, circulatory and pulmonary are the six types of OFs proposed in the different classifications, with different prevalence worldwide. Irrespective of the definition used, patients who develop ACLF present a hyperactive immune system, profound haemodynamic disturbances and several metabolic alterations that finally lead to organ dysfunction. These disturbances are triggered by different factors such as bacterial infections, alcoholic hepatitis, gastrointestinal bleeding or hepatitis B virus flare, among others. Because patients with ACLF present high short-term mortality, a prompt recognition is needed to start treatment of the trigger event and specific organ support. Liver transplantation is also feasible in carefully selected patients and should be evaluated.