New method of hematocrit correction of whole blood viscosity

Hematocrit (HCT), the volume fraction of cells in whole blood, is one of the most important variables that affect the viscosity of whole blood. Matrai's HCT-correction model (Matrai model) provides a method of HCT-correction so that the blood viscosity can be compared at a standard HCT of 45%. Since the Matrai model requires the plasma viscosity, there is a need to have another method for HCT correction of the blood viscosity in cases when the plasma viscosity is not available. The present study introduced a new method of HCT correction using the whole blood viscosity measured over a range of shear rates without plasma viscosity. For validation of the new method, three different human blood samples were used. Each blood sample was reconstituted to eight different HCT levels (from 25 to 60%) and the blood viscosity at each HCT level was measured over a range of shear rates, including the blood viscosity at HCT 45%. HCT-correction results from the Matrai model and the present model were compared with the blood viscosity measured at HCT 45%. The present model gave significantly better HCT corrections (i.e., about 3 times less error) than the Matrai model.