Description

The viscosity of blood varies with the hematocrit.

The viscosity is from observed leukocrit and erythrocrit (Figure 1, page 726, Lichtman 1987; Figure 2, page 280, Lichtman 1982). Equations derived in JMP from points read from diagram. The viscosity associated with the hematocrit is linear in a semi-logarithmic plot and exponential in a non-logarithmic plot.

LOG10(viscosity due to erythrocrit) = X =

= (0.01138 * (hematocrit in percent)) + 0.03699

viscosity due to erythrocrit in centipoise =

= 10 ^ (X)

NOTE: For the influence of a very high white blood cell count (sufficient to give a measureable leukocrit) see 28.15.01.

If the equations are rewritten:

estimated hematocrit in percent for a given viscosity =

= ((LOG10(viscosity in centipoise)) - (0.03699)) / 0.01138 =

= (87.873 * LOG10(viscosity in centipoise)) - 3.25

In the Scientific Tables (Documenta Geigy) there is a graphical plot showing the correlation of hematocrit to blood viscosity from Pirofsky. This gives lower values than Licthman et al. if the plot is analyzed:

 Hematocrit in percent Viscosity in Centipoise 20 1.41 22.5 1.5 30 1.79 35 2 40 2.29 50 2.85 51.8 3 60 3.7 62.5 4 68.6 5 70 5.23 73.1 6 78.4 8 80 9

If this is modeled in JMP:

viscosity in centipoise =

= (0.00000205 * ((hematocrit)^4)) - (0.000339 * ((hematocrit)^3)) + (0.02077 * ((hematocrit)^2)) - (0.499 * (hematocrit)) + 5.513