Study on alterations of blood flow and blood viscosity under hemorrhagic shock and effects of plasma expander.

Experiments were performed in 48 dogs subjected to a shock produced by hemorrhage after the modified Wiggers' method. Dogs were infused 90 minutes after hemorrhage with one of six test substances; shed blood, 5% glucose solution, or four kinds of dextran ( mw. 75,000, 47,000, 29,000 and 12,000 ). Infusion of dextran with mw. 29,000 produced the most remarkable increase in femoral arterial blood flow above the prehemorrhagic level. This flow improvement was thought to be more attributable to reduction in blood viscosity than an increase in blood volume. INTRODUCTION The development of shock is a complicated phenomenon not necessarily causally related to any one factor. The shock may be resulted from a multiplicity of influences such as hormonal, neural, circulatory and so onn. Hemorrhage, if it is significant in amount, may cause irreversible responses of the circulatory system. Maintenance of blood volume and blood pressure is necessary, but there is no guarantee to restore capillary circulation even with an adequate blood replacement. The circulatory conditions after hemorrhage are accompanied by cellular aggregation or sludging, increased blood viscosity and venular stasis of cells11 41 • Cellular aggregation, if uncorrected, may reduce nutritive capillary blood flow and result in hypoxic damages of the parenchymatous organs. A failure of capillary circulation is related to a principal cause of a fatal process. Reversal of cellular aggregation with return toward normal circulation is seen after the administration of low molecular weight dextran (LMWD )215)-91. The hemodynamic changes induced by the LMWD administration have been studied, both in terms of acute plasma volume expansion and in terms of blood flow increase attributed to the viscosity altering effects101 131 • Many studies216171 101 121 emphasize the relationship of viscosity alterations to the microcirculatory changes in the disturbed circulatory states and the usefulness of LMWD for Received for publication December 12, 1967. ~7l<rr'frl