Influence of intravenous infusions of hydroxyethylstarch (HES) (MW 40,000 and 450,000) on the blood flow properties of healthy volunteers.

Infusions of hydroxyethylstarch (HES) solutions as plasma substitutes and flow improvers play an increasing role in the treatment of various diseases. Little is known about the effect of HES solutions of different molecular weights on the flow properties of blood i.e. blood viscosity, plasma viscosity, erythrocyte aggregation and erythrocyte deformability (filtrability). In the present study the influence of 500 ml-infusions of a 6% solution of HES (MW 450,000) has been compared to that of 6% solutions of HES 40,000. Infusions of 500 ml of HES 450,000 into healthy persons induced a hemodilution with a subsequent decrease in whole blood viscosity whereas the plasma viscosity increased. Red cell aggregation increased as well, red cell deformability was slightly impaired. Infusions of 500 ml of HES 40,000 into healthy persons were followed by a hemodilution with a decrease in blood and plasma viscosity, a decrease in erythrocyte aggregation and a slight improvement of red cell deformability. The reason for this difference in behaviour and its therapeutical consequences are discussed.