A method has been developed for studying blood viscosity at shear rates from 4·10−2 to 7·102 sec−1 i.e., in the shear range in which the influence of shear rate on viscosity is greatest. Blood viscosity is expressed by the two regression coefficients of a power regression, according to the equation:
in which η is viscosity, D is the shear rate, a and b are the two regression coefficients, which are independent of the shear rate. We found that the power regression gives a good fit of the experimental data over a wide range of hematocrit. We also found significant correlations between the two regression coefficients and hematocrit and plasma viscosity, thus making it possible to correct the two regression coefficients for standard hematocrit and standard plasma viscosity. This method is simple, highly reproducible, and can easily be automatically performed by using a computer.
