Hemoglobin blood substitutes in extended preoperative autologous blood donation: an experimental study.

Background: The risks of homologous blood transfusion have stimulated interest in developing possible alternatives. In this study we examined the efficacy of using a hemoglobin-derived blood substitute to augment and extend preoperative autologous blood donation.

Methods: In an ovine model, two experimental groups (n = 6 each) of animals donated either 45% or 80% or more of calculated blood volume, which was replaced with a polymerized bovine hemoglobin solution. Two control groups (n = 6 each) either did not donate or donated 45% of calculated blood volume, which was replaced with a 6% hetastarch solution. Twenty-four hours after blood donation, sheep underwent a measured surgical stress with standardized intraoperative blood loss; donated blood was reinfused.

Results: Extended autologous blood donation and replacement with this blood substitute were efficacious in supporting oxygen consumption; there was no systemic toxicity. After the postoperative replacement of autologous blood, animals that donated 80% or more of red cell mass exhibited overall blood conservation with a final hematocrit of 25.7% +/- 3.6%, compared with 20.5% +/- 2.0% (p < 0.05) and with 21.5% +/- 1.1% (p < 0.05) in both control groups.

Conclusions: This study suggests that the benefits of a blood substitute can be combined with autologous blood donation to (1) safely increase the amount of autologous blood donated while supporting oxygen consumption, (2) avoid the need for advanced preoperative donation, and (3) decrease the need for homologous blood transfusion.