The objectives of the study are the following:
1.) To establish whether patients at increased risk of red cell transfusion can be transfused with rejuvenated red cells.
2.) To determine whether the rejuvenation of stored allogeneic red blood cells prior to transfusion will reduce postoperative organ injury in cardiac surgery patients at risk of large volume blood transfusion.
3.) To establish whether the observed effects of red cell rejuvenation are attributable to changes in endothelial, platelet and/or monocyte activation, or improved tissue oxygenation.
Primary Hypothesis: Post-operative organ injury and inflammation will be reduced if patients undergoing cardiac surgery who are at risk of large volume blood transfusion (defined as the administration of ≥4 units of red cells) receive rejuvenated washed cells as compared to standard care (unwashed aged stored cells).
Secondary Hypothesis: Rejuvenation will attenuate platelet and monocyte activation, oxidative stress, endothelial dysfunction and tissue hypoxia attributable to allogeneic red cell transfusion.