Blood Viscosity as a Determinant of Regional Blood Flow

Abstract

Introduction Increasing importance of the role of blood viscosity alterations in various "flow problems," such as shock, hypothermia, extracorporeal circulation, thromboembolism, and peripheral vascular surgery is suggested by the growing popularity of this topic in current medical literature.^{1,4,9,10,14,18,21} Experimental and clinical studies have documented changes in cardiac output, myocardial contractility, and peripheral vasomotor tone in shock, whereas only recent attention has been given to changes occurring in the microcirculation, arbitrarily defined as that complex of arterioles, capillaries, and venules with internal diameters of less than 100μ.¹⁸ Interest in the subject of viscosity has been heightened through basic investigations by Swedish investigators of low viscous dextran (LVD) or low molecular weight dextran (LMDX) and its flow and viscosity altering properties.^7,17 This report concerns the effect of viscosity alterations on blood flow in an animal under conditions of experimental shock, documenting these changes with actual measurements of viscosity and