LIMITATIONS in the use of blood substitutes in severe hemorrhage in dogs have been studied in our laboratory using a new experimental model.1-3 Severe acute anemia (to 10% hematocrit reading) was produced by serial blood withdrawals (10 ml/kg each every ten minutes) and immediate infusion of equal volumes of colloid solution (dextran 40, dextran 75, or hydroxyethyl starch). Long-term survival was obtained in 80% of 43 animals studied. Early compensation was by increased cardiac output and increased coefficient of oxygen extraction.* Late compensation was by increased coefficient of oxygen extraction and erythropoiesis.
Limitations of the treatment of hemorrhage with salt solutions are still not clear, partially because of varying results obtained with different experimental methods. Ebert and associates4 showed that following hemorrhage, infusion of saline solution alone could not maintain plasma volume unless circulating protein was restored. In our pilot experiments during which blood was replaced with equal