The effect of temperature and hematocrit on the viscosity of blood

An in vitro technique for studying the changes that occur in blood viscosity over a wide variation in both temperature and hematocrit is described. The role played by the red cell concentration in determining the nature of the viscosity-temperature relationship is discussed and illustrated. The effect of temperature on the viscosity-hematocrit relationship is presented. A critical temperature range somewhere between 10 ° and 20 °C., where there appears to be disproportionate increases in viscosity with both hemoconcentration and hypothermia, is discussed and illustrated. The possible significance of this critical temperature range in determining the effectiveness of capillary flow is discussed.