PREOPERATIVE AUTOLOGOUS BLOOD DONATION - BENEFIT OR DETRIMENT - A MATHEMATICAL-ANALYSIS

Background: Advocates of preoperative autologous blood donation (PABD) often fail to consider the needs of individual patients and the effec ts of donation on hematocrit. Mathematical modeling is used here to an alyze PABD. Study Design and Methods: A model of PABD was constructed to simulate the transfusion of red cells once a predetermined minimum hematocrit was reached. Preoperatively deposited units not needed to m aintain a hematocrit at this level were not transfused. Final hematocr its were compared to the hematocrit that would be expected if the pati ent had not donated blood for his or her own operative use. Results: F or many patients, particularly those with normal initial hematocrits, large estimated blood losses must occur before the minimum hematocrit is reached. It is also known that patients donating multiple units typ ically cannot maintain their baseline hematocrit. In such cases, for b lood losses of any volume, the final hematocrit was lower if units wer e collected preoperatively and transfusion did not occur, Preoperative ly donating patients are more likely to be transfused earlier and more frequently than nondonating patients. Derived figures, based on indiv idual patient values, help predict which patients will benefit most fr om PABD. Conclusion: PABD may actually lead to decreased postoperative hematocrits (with enhanced risk of ischemia) and otherwise unnecessar y transfusions.