Oxygen supply to the tissues during limited normovolemic hemodilution

Limited normovolemic hemodilution has been performed in splenectomized dogs during pentobarbital anesthesia and controlled ventilation. The hematocrit has been decreased by exchanging arterial blood against dextran 60 until 20% was reached. Cardiac output, myocardial contractility, local muscle blood flow and local tissue PO2 were investigated in relation to progressive decrease in red cell concentration. Limited normovolemic hemodilution was associated with a significant increase of total and local blood flow; local tissue hypoxia did not develop despite the decrease in oxygen capacity of the blood as proved by the measurements of spatial PO2 in liver, kidney, pancreas, small intestine and skeletal muscle. It is concluded that flow improvement in limited normovolemic hemodilution is the key mechanism in maintaining the oxygen supply to the tissues, a fact which favors the concept of normovolemic hemodilution as a therapeutic tool in microcirculatory disorders.