Delirium in the intensive care unit is an acutely developed brain dysfunction affecting up to 80 % of patients. It is associated with significantly increased morbidity and mortality during admission and post-discharge. The mechanism behind the condition is poorly understood but assumably multifactorial, and the purpose of this study is to investigate the pathophysiology further.

The pathophysiology behind delirium in critical illness is not clarified but assumed to involve inflammation, changes in cerebral perfusion and neurotransmission, sleep deprivation and the use of i.e. sedatives.

Cortical spreading depression is a phenomenon occuring in critically ill patients with acute cerebral trauma and likely associated with significant secondary neuron damage.

The hypothesis is that

1. Delirium in critically ill patients without acute cerebral damage is a clinical manifestation of cortical spreading depression and can be recorded in a noninvasive direct current-electroencephalography
2. Electroencephalographic alterations or potentially specific signatures occur in delirium and thus, delirium can be predicted by recording continuous alternate current electroencephalography on admission in an ICU

Inclusion Criteria:

• expected admission in the ICU >24 hours

Exclusion Criteria:

• Cerebral trauma <6 months
• existing delirium
• severe dementia

Critically ill patients with and without acute cerebral trauma

Data analysis is in progress