The study is conducted in Finland, in the intensive care unit of the Surgical Hospital of Helsinki. The total number of patients in this study is 20, and it is a part of a larger neuromonitoring study with a total of 110 patients. The patients are divided into four subgroups, as follows: 1. patients admitted to ICU with acute liver failure, 2. patients admitted to the postoperative cardio-thoracic ICU after cardiac surgery with perioperative total heart arrest, 3. patients admitted to the ICU because of status epilepticus and finally 4. patients in critical condition, admitted to the ICU after any surgery. This study concentrates on the first group of patients with acute liver failure.