Comparative haemorheology of pathological blood

Abstract

We have studied the rheological behaviour of pathological blood (patients with polycythaemia, patients with myocardial infarction, patients with renal disease) and normal blood with two different rheometric apparatus.

With filterability measurements we obtain information about red blood cell deformability and with viscometric measurements in transient flow, it is possible to reach the red blood cell aggregability. We have compared these two methods and found correlation between some of the rheological parameters and filter-ability.

We have used a Couette viscometer (Healy & Joly, 1975). This allowed us to plot the curves of stress as a function of time or shear rate. The study of the rheological behaviour of blood in transient flow permits us to show the viscoelasticity and the thixotropy of blood samples. The filterability is measured with a filtration apparatus (Reid, 1976).

The results obtained indicate significant differences between the rheological behaviour of the control group (healthy people) and that of the patients with polycythaemia (patients with high levels in their haematocrit and haemoglobin). But not all the patients have the same rheological behaviour. With some patients with myocardial infarction the measurements reveal a reduced thixotropy in relation to control. This modification is interpreted as a more stable red cell aggregation. Haemodialysed patients have a reduced filterability. For some of them the time of filtration is very long.

Key Words:

• Filterability and cardiovascular risk factors
• blood viscosity
• red blood cell aggregation