Expectations and implications of blood sparing with hemoglobin based oxygen carriers.

To gain insight into the degree to which hemoglobin based oxygen carriers may replace the need for transfusion in surgical patients experiencing blood loss, a simple mathematical model was developed. This model predicts the amount of blood sparing resulting from a bolus infusion of different doses of hemoglobin solution as a function of circulating hemoglobin half-life and degree of erythropoesis enhancement subsequent to treatment. The results of this analysis are consistent with published clinical data and imply that blood sparing increases with increasing oxygen carrier dose and half-life, as well as increasing levels of erythropoesis enhancement. The analysis also predicts that the total circulating hemoglobin content in patients infused with HBOC solutions may reach a minimum value up to ten days after treatment.