BACKGROUND: The administration of erythropoietin (EPO) can be used to incre
ase a patient's hematocrit (Hct) in the preoperative period and thus possib
ly preclude the need for allogeneic red cells, However, the exact effect on
the postoperative Hct of a given rise in Hct in the preoperative period (a
nd on the avoidance of allogeneic blood) has not been thoroughly evaluated,
STUDY DESIGN AND METHODS: Equations were developed on the basis of previous
ly described relationships that allowed the assessment of the impact of a g
iven preoperative Hct increase on the postoperative Hct under a variety of
clinical situations.
RESULTS: Equations were derived that related the change in preoperative Hct
after the administration of EPO to the final Hot after a given blood loss.
In a typical example (blood volume = 5000 mL, pre-EPO Hct of 40%, post-EPO
Hct of 45% after blood losses of 1000, 2000, 3000, 4000, 5000, and 6000 mt
), an additional 205, 168, 137, 112, 92, and 75 mt of red cells, respective
ly, would be present postoperatively over the volume in the same patient wh
o did not receive EPO. For a smaller patient, such as a child (blood volume
, 2500 mt), an additional 17 mL(5000-mL blood loss) to 83 mL(1000-mL blood
loss) of red cells would be present postoperatively. Hemodilution and EPO a
ct synergistically to yield additional postoperative red cell volume.
CONCLUSION: The use of preoperative EPO with a preoperative increase in Hct
results in an increased postoperative Hct after a surgical blood toss. Suc
h a postoperative increase is a function of the volume of blood lost and th
e patient's blood volume but is independent of the patient's initial Hct. T
he final postoperative red cell volume increase associated with a preoperat
ive increase in Hct of 1 to 5 percent is limited, however (generally equiva
lent to a fraction of 1 unit of allogeneic blood). Much of the increase in
the patient's Hct vanishes at higher blood losses, and this therapy is most
effective with blood loss of <4000 mt, EPO therapy alone may be most effec
tively used in patients with mild anemia who are undergoing routine surgica
l procedures that commonly require blood transfusion.