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.1 In orthopedic surgery reduced use of allogeneic transfusions has been shown to prevent both early2 and late3 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 1998/99.4 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 1995/96,5 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 intra- and 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.4,6,7,8 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%.3,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23 Table 1 summarizes the allogeneic transfusion rates of studies in which various combinations of blood conservation techniques were used.24
Table 1.
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., Mirandola Modena, Italy) attached to the reservoir.20 If there is postoperative bleeding, the blood can be salvaged with the use of a recovery device (e.g., Dideco Recovery BT 797, Dideco S.p.A.) and, after sedimentation and microfiltration, reinfused during the first 8 hours after surgery.
The reinfusion of predonated blood should be spread out over the first 3 days after the operation. The decrease in hemoglobin concentration in the first 2 days, as a consequence of this delay, allows increased production of endogenous erythropoietin25 and reduces the need for allogeneic transfusion.26 Units of allogeneic blood are transfused only if there is symptomatic anemia or the hemoglobin concentration is less than 60 g/L (100 g/L in patients with cerebrovascular damage or heart disease) and only after all available autologous blood has been used and any concomitant hypovolemia has been corrected with crystalloid or colloid solution.18,19 After each unit of allogeneic blood is transfused, the patient's clinical situation needs to be checked and the need for another transfusion evaluated.18
The quality of red blood cells salvaged with the Dideco Compact Advanced intraoperative salvage apparatus and the Dideco Recovery BT 797 postoperative salvage device, as determined by the proportion of cells that are damaged, appears to be similar to the quality of red blood cells collected preoperatively and refrigerated at 4οC for 21 days.27 In addition, compared with stored autologous blood, salvaged blood is more resistant to changes in osmotic pressure and has higher concentrations of 2,3-diphosphoglycerate and higher physiologic concentrations of potassium.28 This level of quality explains why there is no correlation between the amount of intra- and postoperative blood lost and salvaged and the need for allogeneic transfusion.20
On the basis of personal experience and the data in the literature, including the findings of Feagan and coauthors, it is clear that the assessment of expected and tolerated blood loss helps to define transfusion needs. Methods to avoid allogeneic transfusion include autologous donation before elective surgery; intravenous administration of iron if necessary; use of exogenous erythropoietin in addition to or, in the case of Jehovah's witnesses for example, as an alternative to autologous donation;24 intraoperative blood salvage and reinfusion if the hemoglobin concentration falls by more than 20 g/L; hypotensive epidural anesthesia to achieve arterial pressure of about 50 mm Hg;29 monitoring of postoperative bleeding and, if blood loss exceeds 200 mL, reinfusion of salvaged red blood cells during the first 8 hours after surgery; antithromboembolic prophylaxis in doses adapted to body weight and hemocoagulation; and reinfusion of predonated autologous blood spread out over the first 3 days after surgery. In order to apply and integrate these methods and minimize complications related to surgery, cooperation among anesthetists, surgeons and transfusionists is indispensable in the perioperative management of patients.
𝛃 See related article page 310
Footnotes
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Contributors: Both authors contributed substantially to the drafting and revising of the manuscript.
Competing interests: None declared.
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