Brain Tissue Oxygen Saturation and Blood Transfusion in Cardiac Surgery (INVOS)

• The number of packed red cell units transfused intra-operatively [ Time Frame: one year ] [ Designated as safety issue: Yes ]
  

• The INVOS values electronically and continuously [ Time Frame: one year ] [ Designated as safety issue: Yes ]
  
• The volume of any kind of intravenous fluids administered to the patient [ Time Frame: one year ] [ Designated as safety issue: Yes ]
  
• The volume of urine output from the initiation to termination of CPB and to the end [ Time Frame: one year ] [ Designated as safety issue: Yes ]
  
• The hematocrit values at certain timeframes [ Time Frame: one year ] [ Designated as safety issue: Yes ]
  

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).