**1. Introduction**

Liver failure is a devastating illness with extremely high morbidity and mortality. With the advent of life-saving orthotopic liver transplantation, the mortality and morbidity due to liver failure has been significantly reduced. Many patients awaiting transplant are critically ill. The intensive care management of patients before liver transplantation is aimed at optimizing hepatic and extrahepatic organ function before the transplant operation, with a goal to favorably influence the perioperative and postoperative graft and patient survival.

Critical illness due to liver disease may present in the context of acute liver failure (ALF) or acute on chronic liver failure (ACLF). The differing pathophysiologic processes underlying these two categories of liver failure necessitate specific approaches to their intensive care management. In their extreme presentations, both types of liver failure result in multi-organ system failure; therefore, the intensive care management of these conditions requires a systematic multi-organ system approach to address hepatic and extrahepatic organ dysfunction (*Ford et al., 2010*). This chapter will provide a multi-organ system–based description of critical care management of ALF and ACLF before liver transplantation.
