Cerebral oxygen saturation (ScO2) is a measure of cerebral and systemic oxygen delivery to demand ratio. An observational trial in a heterogeneous cohort of 1078 patients patients revealed that a ScO2 below 50% absolute during oxygen insufflation is an independent predictor of short and long term mortality in patients undergoing on-pump cardiac surgery. Comparably, a low ScO2 was a predictor of postoperative morbidity determined as a combined endpoint of a high dependency unit stay of more than 9 days and/or at least 2 of the major postoperative complications. low cardiac output syndrome, stroke, need of renal replacement therapy or reintubation.

The primary objectives of the present prospective observational study is to determine, if there is an association between preoperative ScO2 and postoperative organ dysfunction determined by sensitive markers of organ dysfunction (N-Terminal pro B-type natriuretic peptide, high sensitive troponin T, growth-differentiation factor 15, soluble -FLT1, and placental growth factor)

Inclusion Criteria:

• all patients scheduled for cardiac surgery

Exclusion Criteria:

• age less than 18 years

Patients scheduled for cardiac surgery