In cardiac operations under cardiopulmonary bypass(CPB), monitoring of brain tissue oxygen saturation with infrared spectrophotoscopy leads to a reduction of the number of packed red cell(PRC) transfusions during the period of extracorporeal circulation.

The purpose of this study is to investigate whether the use of brain tissue oxygen saturation monitoring will lead to a reduction of the intra-operative use of packed red cell units.

Patients randomly allocated to groups A and B. In group A INVOS monitoring available. In group B, no access to INVOS for the attending anesthesiologist. An "observer" anesthesiologist has access to INVOS and provides information if it is considered necessary.

For BOTH GROUPS:

During CBP and before aortic unclamping, PRC not to be given if hemoglobin is >7g/dl. For values less than 5.5g/dl, one unit of PRC is transfused and the patient is reevaluated. After weaning from CPB and retransfusion of the salvaged shed blood, transfusion when hemoglobin is <8g/dl. During ICU stay, transfusion when hemoglobin is <8g/dl. Between 8-10g/dl evaluation for transfusion in a multimodal manner.

For GROUP A:

As above and during CBP and before aortic unclamping, if hemoglobin is between 5.5-7g/dl, transfusion when INVOS is less than 60%.

For GROUP B:

As above and during CBP and before aortic unclamping, if hemoglobin is between 5.5-7g/dl, decision for transfusion is taken by the attending anesthesiologist (judgment).

Inclusion Criteria:

• Cardiac operations under cardiopulmonary bypass, consequently (including coronary-aortic bypass graft), valve replacement, surgery of the ascending aorta, combined procedures, redo-operations)

Exclusion Criteria:

• Cardiac operations without the aid of extracorporeal circulation (ex. "off-pump" techniques)
• Emergency operations