Inclusion Criteria:  Patients aged 40 or above. Patients scheduled for acute abdominal or orthopaedic surgery in general anaesthesia with an expected duration of 30 minutes or more. Patients who are scheduled for surgery within 72 hours of hospital admission. Patients who are expected to stay in hospital for 24 hours or more.  Exclusion Criteria:  Patients screened CAM positive before surgery. Patients who have already been included in the study Patients unable to speak and read Danish. Inability to provide consent.