Reducing the risk of allogeneic blood transfusion.

The restricted use of allogeneic blood transfusions has been accepted throughout the world as important in reducing risk, particularly of the transmission of infectious diseases. In orthopedic surgery reduced use of allogeneic transfusions has been shown to prevent both early and late postoperative infection. In this issue (page 310) Brian Feagan and colleagues describe transfusion practices and blood conservation strategies used in 19 hospitals across Canada for patients undergoing elective total hip or knee arthroplasty during 1998/99. Of the 4535 patients whose charts they reviewed, 18.6% (range 1.3%–66.0%) predonated blood before their procedure, even though 57.9% were eligible to do so. Not surprisingly, the rate of allogeneic transfusions was much lower among those who predonated their blood than among those who did not (14.1% v. 30.6%). Although the rate of autologous blood donation was higher than that in a similar study by the authors in 1995/96, it is striking that other methods for avoiding allogeneic transfusions are still being used infrequently. In only 2.4% of the cases in the current study were alternative blood conservation techniques such as normovolemic hemodilution and intraand postoperative red blood cell salvage used. As others have shown, including Feagan and coauthors, it is possible with autologous predonation alone to reduce dramatically the need for allogeneic transfusions. In other countries, various blood conservation programs are in use, and studies have shown that autologous donation, intraoperative blood salvage and postoperative blood salvage, alone or in combination, have reduced the rate of allogeneic transfusion to as low as 8%. Table 1 summarizes the allogeneic transfusion rates of studies in which various combinations of blood conservation techniques were used. With intraoperative blood salvage, uncoagulated blood is aspirated during surgery and collected in a bag connected to the inferior edge of the surgical wound and then into a reservoir. If the hemoglobin concentration falls by more than 20 g/L (or less if the risk of allogeneic transfusion is high, as in cases of pre-existing anemia or cardiovascular disease, for example) the red blood cells are concentrated, washed and reinfused with the use of an autotransfusion device (e.g., the Dideco Compact Advanced, Dideco S.p.A., Reducing the risk of allogeneic blood transfusion