Viscosity alterations have been invoked to explain certain phenomena associated with shock and other disturbed circulatory states. Unfortunately, methods for the measurement of the viscosity of blood in vivo are not yet available. However, in vitro measurements of the relative viscosity may be obtained by measuring the shear stress at various shear rates in samples of blood or plasma withdrawn from the patient or experimental animal. Alternatively, the effects of viscosity alterations may be studied by physiologic measurements before and after addition of highly viscous materials to a biological preparation. Sucrose is polymerized to dextrans of various molecular weights and viscosities by the bacteria, Leuconostoc mesenteroides1; these dextrans may be fractionated to provide material of relatively uniform viscosity and molecular weight for clinical and experimental studies.2 The physiologic effects of viscosity alterations produced by the administration of high or low viscosity dextran then may be observed and studied
SHOEMAKER WC. Studies on Viscosity Alterations in Shock: I. Effect of High and Low Viscosity Dextrans Upon Plasma and Red Cell Volumes. Arch Surg. 1963;87(2):355–364. doi:10.1001/archsurg.1963.01310140163024
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