The aim of the study is to identify the incidence of early postoperative delirium in intensive care patients after cardiac surgery and detect possible risk factors associated with increased risk for developing delirium after cardiac surgery.

A consecutive series of patients scheduled for elective cardiac surgery is included in the study. Delirium screening is performed using Intensive Care Delirium Screening Checklist. Preoperative cognitive state is evaluated with Mini-Mental State Examination. Information of possible risk factors is collected from patient's history and chart. The Snoring, Tiredness, Observed apnea, high blood Pressure-Body mass index (BMI), Age, Neck circumference and Gender questionnaire (STOP-BANG questionnaire) is used for obstructive sleep apnea screening.

Inclusion Criteria:

• elective cardiac surgery
• patient spends more than 1 day in the intensive care unit after the surgery

Exclusion Criteria:

• refusal to participating in the study
• documented severe central nervous system, cognitive or psychiatric disorder
• unable to be screened with Intensive Care Delirium Screening Checklist up to 6th postoperative day (e.g. deeply sedated, intubated patients)

All consecutive patients scheduled for elective cardiac surgery