Frontal Electroencephalogram Variables Are Associated With Outcome and Stage of Hepatic Encephalopathy in Acute Liver Failure

Neuromonitoring of critically ill patients in the intensive care unit (ICU) is challenging. Clinical scoring systems produce insufficient information with deeply sedated patients, and disturbances of normal hemostasis limit the use of invasive intra-cranial pressure measurements. EEG based monitoring algorithms have been introduced into the operation theater and general anaesthesia, but these algorithms cannot be used in the intensive care setting without modifications. EEG is also susceptible to electrical disturbances, such as those created by patient movement.

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.

Clinical care of patients is not altered. When arriving into the ICU EEG-monitoring will added to routine monitoring. To evaluate the neurological status the following tests are performed: clinical test, blood tests and transcranial doppler ultrasound. The Entropy of EEG is measured along with the raw EEG signal.

The recruiting of study patients was begun in December 2005 and the final study patients were recruited in December 2011. GE Healthcare Finland supplies the entropy monitoring devices and pays the salary of the research nurses who collect the study data. Clinical investigators will not receive funding from any commercial company. All patients (or their next of kin) included have given their written informed consent for inclusion in the study.

The aim of this study is to find new factors and new non-invasive techniques, which correlate with the neurological state and outcome of patients suffering critical illness.