Intraoperative cell salvage may damage erythrocytes as indicated by macrophage uptake

Cell salvage is a blood conservation strategy commonly implemented in cardio-thoracic and orthopaedic surgery. Since its introduction in the 1990s, remarkably little work has been carried out investigating possible adverse effects of these transfusions. Adverse effects of blood transfusion have been linked with excessive uptake of erythrocytes by splenic macrophages. We investigated whether the salvage process alters the immune properties of the erythrocytes that are reinfused. Patients set to undergo coronary artery bypass grafting or primary hip replace-ment were recruited. Native and salvaged blood samples were obtained intra-operatively. We compared the phagocytosis of these red blood cells by murinemacrophages using microscopy and used a flow cytometric technique to quantify any changes in surface markers for uptake. Twenty patients were recruited. We observed a significant increase in uptake of salvaged red cells compared with native cells (p = 0.008). Flow cytometry failed to show any changes in markers for uptake (Phosphatidylserine, CD47, SNA, MAL-II) that may have explained this increase. The salvage process appears to damage red cells so that they are taken up by macrophages more readily than native cells, which may predispose to adverse clinical outcomes. Although the structural basis for this could not be identified, our findings indicate that further investigation into the effects of cell salvage on erythrocytes should be undertaken.