Clinical blood rheology 1

Vascular diseases and risk factors such as smoking are accompanied by an increase in blood viscosity due to the enhancement of aggregation of the red blood cells. This is demonstrated both for smokers and for patients with peripheral vascular disease by comparing the viscoelasticity of the blood with that from healthy donors. Also, the hematocrit values measured by centrifugation for the smokers and patients were found to be significantly higher than for the healthy donors, this difference being attributed to the effects of aggregation. A new unit, the calculated hematocrit, is recommended. This unit, calculated from measured values of blood and plasma densities, is independent of the conditions of aggregation.