Mixtures of whole blood and hydroxyethyl starch--hemoglobin polymers.

This study examines some of the biophysical properties of mixtures of whole blood with 3 different hydroxyethyl starch-hemoglobin (HES-Hgb) polymer blood substitutes. The polymers have about a 3-fold range of number average molecular weight and intrinsic viscosity range. The range dependent rheologic studies with a 60 g/L of polymer solution showed that all 3 blood substitutes were very effective hemodiluents paralleling the hemorheologic properties of the starting HES polymers. The 2 higher molecular weight polymers enhanced the erythrocyte sedimentation rates (ESR) at an 8:1 blood to polymer dilution; however, the lowest molecular weight sample actually retarded the settling. The kinetics of malonamide-induced hemolysis indicated that these new polymers do not increase the rate of hemolysis but rather, offer some protection in a manner similar to stroma-free Hgb (SFH) solutions. The oxygen transport properties determined by biotonometry during an exchange transfusion showed that the P50 values decreased and were dependent upon the Hct. However, these samples were able to maintain rats at an Hct level of 10%.