Limitations to donating adequate autologous blood prior to elective orthopedic surgery.

We reviewed 175 patients who predeposited autologous blood prior to elective orthopedic surgery to define potential limitations of procuring adequate autologous blood. These potential limitations include physician underordering, storage interval, and erythropoietic response. We found that a continuing medical education intervention increased the amount of autologous blood requested by physicians for storage: from 121 U for 50 patients (mean = 2.4) before CME to 195 U for 65 patients (mean = 3.0) afterward; eight (16%) of 50 patients had 4 U or more requested before CME vs 25 (38%) of 65 patients afterward. Continuing medical education had no impact on mean (+/- SD) effective storage interval, 22.6 +/- 9.0 vs 21.6 +/- 9.4 days. Thirty (17%) of 175 patients were deferred (hematocrit less than or equal to 0.34) and were unable to donate units of blood requested; of these, 13 (43%) received homologous blood compared with 19 (13%) of 145 not deferred. We conclude that a significant percentage of patients are deferred from autologous donation because of hematocrit limitations and receive homologous blood. This problem is not related to physician underordering or inappropriate physician transfusion behavior, but rather to the erythropoietic response to serial phlebotomy over a limited storage interval. Future studies should focus on mechanisms to maximize autologous blood procurement.