Limited hemodilution in hemorrhagic shock in dogs: effects on central hemodynamics and the microcirculation in skeletal muscle.

Abstract

The keyproblem of hemorrhagic shock consists in decreased tissue nutrition and tissue drainage from metabolites with subsequent hypoxic cellular damage. In two groups of 50 dogs the effect of whole blood (n = 30) versus hemodilution with dextran-60 (n = 20) was evaluated from central hemodynamics, capillary blood flow and transcapillary exchange from tissue to blood in skeletal muscle by use of a double isotope technique. Following a period of hemorrhagic hypotension either all the shed blood or dextran-60 were infused. Hemodilution with dextran produced a decrease in hematocrit to 20%, lowered effeciently blood viscosity and TPR and increased cardiac output to 160% of control. Capillary blood flow and exchange were nearly doubled as compared to the control level. Retransfusion of blood caused only transient normalization with rapid deterioration in central and peripheral hemodynamics, together with an increase in blood viscosity. The viscosity depressant effect of hemodilution is discussed as key factor causing the better immediate response to dextran infusion in hemorrhagic shock.