Blood-viscosity and Vascular Flow Rate Blood-viscosity Measured in a Cone-plate Viscometer and the Flow Rate in an Isolated Vascular Bed

The whole-blood viscosity measured in a cone-plate viscometer and the flow ratio estimated in the vascular bed of an isolated rabbit ear have been compared for different blood samples. The reciprocal ratio between the flow rate of human blood and the flow rate of saline in the vascular bed was statistically significantly correlated to the haematocrit value. The estimated flow ratio in the vascular bed was approximately proportional to the viscosities measured in the cone-plate viscometer. The closest proportionality was found at shear rate 5.75 sec-1. The flow rate of blood relative to saline was at all shear rates found to be higher than expected from the measured viscosities. This indicates that the Fåhræus-Lindqvist effect is effective in the vascular bed.