The Beneficial Effects of Increasing Blood Viscosity
Increased hematocrit above normal levels is usually associated with the elevation of mean systemic arterial blood pressure (MAP) due to increased blood viscosity as shown in studies where hematocrit was increased by 40% or more above baseline [1, 2]. This effect is related to the behavior of pressure in rigid tubes subjected to constant flow, in the presence of varying viscosity. Clinically and physiologically, this situation is encountered with pathologically high hematocrits  and in individuals adapted to high altitude with hematocrit levels of 75–91% . Moderate hematocrit changes (and, therefore, changes in blood viscosity) due to variability in the normal population do not appear to affect MAP.
KeywordsHemorrhagic Shock Blood Viscosity Plasma Viscosity Plasma Expander Physiol Heart Circ
Unable to display preview. Download preview PDF.
- 1.Richardson TQ, Guyton AC (1959) Effects of polycythemia and anemia on cardiac output and other circulatory factors. Am J Physiol 197:1167–1170Google Scholar
- 5.Martini J, Carpentier B, Chavez Negrete A, Frangos JA, Intaglietta M (2005) Paradoxical hypotension following increased hematocrit and blood viscosity. Am J Physiol Heart Circ Physiol 289:H2136–2143Google Scholar
- 8.Smiesko V, Johnson PC (1993) The arterial lumen is controlled by flow related shear stress. News Physiol Sci 8:34–38Google Scholar
- 12.Cabrales P, Tsai AG, Intaglietta M (2005) Alginate plasma expander maintains perfusion and plasma viscosity during extreme hemodilution. Am J Physiol 288:H1708–1716Google Scholar
- 13.Cabrales P, Tsai AG, Intaglietta M (2004) Microvascular pressure and functional capillary density in extreme hemodilution with low and high plasma viscosity expanders. Am J Physiol 287:H363–H373Google Scholar
- 18.Krieter H, Brückner UB, Kafaliakis F, Messmer K (1995) Does colloid induced plasma hyperviscosity in haemodilution jeopardize perfusion and oxygenation of vital organs? Acta Anaest Scand 39:326–244Google Scholar
- 21.Cabrales P, Tsai AG, Winslow RM, Intaglietta M (2005) Extreme hemodilution with PEGhemoglobin vs. PEG-albumin. Am J Physiol 289:H2392–2400Google Scholar