The Role of Aggressive Phlebotomy and the Use of Erythropoietin
The efficacy of preoperative autologous donation is dependent
on the degree to which the patient's erythropoiesis increases the production of red
blood cells (RBCs).[34]
[35]
[36]
[37]
The endogenous
erythropoietin response and compensatory erythropoiesis are suboptimal under "standard"
conditions of one blood unit donated weekly. As shown in Table
48-3
, weekly PAD is accompanied by an expansion in RBC volume of 11% (with
no oral iron supplementation) to 19% (with oral iron supplementation), which is not
sufficient to prevent increasing anemia in patients undergoing PAD. If the erythropoietic
response to autologous blood phlebotomy is not able to maintain the patient's hematocrit
level during the donation interval, the donation of autologous blood actually may
be harmful.[38]
This outcome was confirmed in a
recent study of patients undergoing hysterectomies,[39]
in which
it was shown that preoperative autologous blood donation resulted in perioperative
anemia and an increased likelihood of any blood transfusion. A mathematical model
[38]
has been published to demonstrate the relationship
between anticipated surgical blood losses, the level of hematocrit that the physician
may want to maintain perioperatively, and the need for autologous blood donation
for individual patients.
In contrast to autologous blood donation under "standard" conditions,
studies of "aggressive" autologous blood phlebotomy (twice weekly for 3 weeks, beginning
25 to 35 days before surgery) have demonstrated that endogenous erythropoietin levels
do increase, along with enhanced erythropoiesis representing RBC volume expansion
of 19% to 26% (see Table 48-3
).
Exogenous (pharmacologic) erythropoietin therapy to further stimulate erythropoiesis
(up to 50% RBC volume expansion[40]
[41]
[42]
) during autologous phlebotomy has been approved
in Canada and Japan but not in the United States.[43]
Perisurgical erythropoietin therapy is approved world-wide for anemic (Hct <39)
patients scheduled for non-cardiac, non-vascular surgeries.
Transfusion Trigger
Disagreement exists about the proper hemoglobin/hematocrit level
("transfusion trigger") at which autologous blood should be given[44]
(also see Chapter 47
). Autologous
blood transfusion is not without risks to the recipient; these include misidentification
of patients or units, bacterial contamination of stored units, and volume overload
( Table 48-4
). The case can
be made that autologous and allogeneic blood transfusion triggers should be similar,
since the mortality risks related to allogeneic blood (transfusion-transmitted infection
and transfusion-related acute lung injury [TRALI]) now are less than risks of mortality
from administrative errors which are associated with both autologous and allogeneic
blood.[45]
Data from a well-designed clinical trial
indicates that even critical care patients can tolerate substantial
TABLE 48-4 -- Advantages and disadvantages of autologous blood donation
|
Advantages |
Disadvantages |
|
Prevents transfusion-transmitted disease |
Does not affect risk of bacterial contamination |
|
Prevents red cell alloimmunization |
Does not affect risk of ABO incompatibility error |
|
Supplements the blood supply |
Is more costly than allogeneic blood |
|
Provides compatible blood for patients with alloantibodies |
Results in wastage of blood not transfused |
|
Prevents some adverse transfusion reactions |
Increased incidence of adverse reactions to autologous donation |
|
Provides reassurance to patients concerned about blood risks |
Subjects patient to perioperative anemia and increased likelihood
of transfusion |
anemia (to Hb ranges of 7 to 9 g/dL) with no apparent benefit from more aggressive
transfusion therapy.[46]
