About spread of local cerebral hemorheological disorders to whole body in critical care patients.

Purpose: The aim of the present pathophysiological studies was elucidation of the feasible mechanism of spread of the blood rheological disorders from the cerebral to systemic circulation, and vice versa.

Methods: The investigation was carried out in the critical care patients with the brain tissue damage related to stroke (cerebral ischemic infarcts as well as parenchymatous and subarachnoid hemorrhages). The applied diagnostic techniques provided us with valid and quantitative data revealing the degree of the red blood cell aggregability, the value of local hematocrit, and the blood plasma viscosity in the cerebral and systemic circulation.

Hemorheological disorders in the microcirculation following hemorrhage.

We analysed hemorheological disorders in the microcirculation of intestinal mesenterium of adult laboratory rats following massive exsanguinations when the mean arterial pressure dropped and then the hemorrhagic shock developed in the animals. The mesenteric microcirculation was analysed by the Texture Analysis System (Leitz, Wetzlar): (a) diameters of the afferent arterioles, capillaries, and efferent venules; (b) the blood flow velocity; (c) microvascular blood flow changes (during the RBC aggregation); (d) local microvascular hematocrit; and (e) the transformation of capillaries into plasmatic microvessels. During development of the hemorrhagic shock we found that the blood flow velocity decreased in all microvessels, there was an increased RBC aggregation which gradually enhanced in the mesenteric microvessels' lumen causing blood flow slowing down till appearance of stases.

Lipid peroxidation in the erythrocytes under condition of their increased aggregation.

The aim of the present study was investigation of the lipid peroxidation changes within the erythrocytes under conditions of increased RBC aggregation. This latter was produced both in the in vitro and in vivo conditions by the addition of Dextran T-500. For the in vitro studies blood samples were taken from the cubital veins of 15 healthy subjects.

Local hemorheological disorders during chronic inflammation.

Hemorheological parameters were investigated before, during, and after the standard burn of the distal part of the rabbits' ear shell (54 degrees C for 3 minutes). The erythrocyte aggregation was investigated with the "Georgian technique" and the local hematocrit was determined by centrifugation of blood samples from the inflammatory focus. In addition, we determined the size of the inflammatory edema in the ear shell.

Regional hematocrit changes related to blood flow conditions in the arterial bed.

Present study was aimed at specifying both the anatomical and physiological factors determining the regional hematocrit alterations. These latter were investigated in blood samples from specific vascular branches of rabbits, as well as from the skin and the jugular veins (reflecting the cerebral microcirculation) of humans. Principal findings were as follows: (1) Blood in the heart left ventricle has a higher hematocrit than blood flowing in the hind legs.