[Hemorheologic changes in preoperative hemodilution during total hip replacement. Randomized study comparing hydroxyethyl starch 200,000/0.62 (HES) and a dextran 60,000].

Hemodilution can be used to save blood transfusion during total hip replacement. We have carried out a randomized study to compare the hemorheological effects of two plasma substitutes: a hydroxyethylstarch 200,000/0.62 versus a dextran 60,000. Twenty-two patients were hemodiluted with 20 mk/kg of either substitute, just after the spinal anesthesia. Whereas the hematocrit have fallen by 30% in the two groups, significant differences are observed about hemorheological parameters. The plasma viscosity express a greater increase at hour 4 in the dextran group. The whole blood viscosities are more increased in the dextran group at hour 4 and 24. The erythrocyte aggregation is decreased in the HES group at hour 4 and 24, but is increased in the dextran group. The fibrinogen is more increased in the dextran group at day 7. In spite of similar hemodilutions, the two substitutes express different hemorheological effects with a favourable role of HES on erythrocyte aggregation and blood viscosities. This can improve the microcirculation and decrease the activation of the endothelial cells, reducing the inflammatory reaction.