[Anti-thixotropic therapy in arterial occlusive disorders: What is the effectiveness of "rheological procedures" in the presence of persisting obliterations?].

In the attempt to illustrate the pathogenetic (and thence the clinical) significance of the anomalous properties of the human blood, we have earlier proposed to use the term "thixotropy" for describing all those rheological anomalies of the blood, which are responsible for the reversible loss of blood fluidity at low rates of shear. "Thixotropy" is a tendency which is present even in normal human blood, but is much more pronounced in the blood of many vascular patients due to exaggerated red cell aggregation and due to red cell "rigidity". This tendency manifests itself when the flow forces are reduced by interfering with the fluidity of the blood. It has no effect on the viscous resistance of the rapidly flowing blood. Most of all, the effect of thixotropy of the blood depends on the haematocrit level, both in normal blood and in the blood of patients: when associated with anaemia, the thixotropic tendency is largely irrelevant, while it gains significance with each increase in the haematocrit level. Theoretically justified by the described premise, the rheological treatments can now be classified as "anti-thixotropic therapies". In the present review, the principle of therapeutic defibrinogenation and of plasmapheresis are discussed as consequences of the resulting desegregation, the principle of isovolemic haemodilution is interpreted as the most effect antithixotropic procedure owing to its profound effect on haematocrit value and thence thixotropic potential.