Hidden Acidosis Following Intravascular Red Blood Cell Aggregation in Dogs

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Abstract
Intravascular red cell aggregation and capillary stasis occurs following tissue injury or in acute or chronic disease states. In these experiments intravascular aggregation was induced in dogs by the intravenous administration of high viscosity dextran (HVD). After a suitable length of time, aggregates were dissolved by the administration of low viscosity dextran (LVD). The effects were noted. After infusion of HVD, there was marked aggregation of red blood cells, a decrease in circulating red cell volumes (RCV), an increase in blood viscosity and a drop in large vessel hemato-crit. When LVD was given, capillary circulation improved, RCV increased and there was a prolonged increase in blood lactic acid concentration. Whole blood pH dropped slightly, plasma pCO rose slightly, while standard bicarbonate and blood pressure remained essentially normal. Even after the infusion of LVD into normal animals a similar effect was noted. In this group, however, lactic acid concentrations returned to normal at the end of the experimental period. It is concluded that infusion of HVD causes red cell aggregation and trapping with plugging of many small capillaries. This results in an insufficient tissue blood flow and deficient tissue oxygenation. When LVD is given, capillary circulation is improved and acid tissue metabolites are released to the general circulation.