Tissue oxygenation after exchange transfusion with ultrahigh molecular weight tense and relaxed state polymerized bovine hemoglobins.
The aim of the study was to compare the efficacy of two PolybHb solutions (10 g/dl Hb of bovine origin) differing in solution viscosity and oxygen affinity (P 50 value) on macro- and microhemodynamics, oxygen transport and tissue oxygenation. The well-known skin fold window model of the moderately hemodiluted (dextran 60), unanesthetized hamster was used for the experiments.
At Hct 18% blood is exchanged for the test solutions. The methods for analysis of the animals macro- and microhemodynamics including determination of functional capillary density (FCD) and local tissue oxygenation (phosphorescence quenching microscopy) have been published by Intaglietta, Cabrales et al. in extenso. In this new study Cabrales et al. convincingly demonstrate that the efficacy of PolybHb as blood replacement fluid depends upon its biophysical properties. T-PolybHb (viscosity 11.4 cP, P50 40 mmHg) was found superior to R-PolybHb (viscosity 7.8 cP, P50 1 mmHg) in maintaining macro-and microhemodynamics, oxygen transport and oxygen release from PolybHb to the tissue (striated skin muscle).
Thus, in normovolemic anemia, at the treshold for red cell transfusion, T-PolybHb, in contrast to R-PolybHb, acted as a viscogenic oxygen carrier both on shear stress (microvascular endothelium) and oxygen release to the tissue. In contrast to hitherto investigated high-viscosity plasma expanders, T-PolybHb can be characterized as efficient high-viscosity oxygen carrier. Unwanted effects to the hamsters are not reported.
– Konrad Messmer