The Relationship of Hemorheological Blood Values and Blood Velocity of Microcirculatory Bloodstream in Rats’ Skin Vessels

Non-invasive study of blood rheology is relevant, but quitecomplex issue. When systemic blood viscosity and hematocrit levelsdeviate, blood flow indicators in different parts of microvasculature change.Purpose of the study—research of blood flow characteristics in skinmicrocirculatory bloodstream of rats obtained by high-frequencyDoppler ultrasound (HFDU) with given changes in rheological bloodindicators. The studies were carried out on pubescent male Wistarrats. 3 experimental groups were formed. Group 1 (n = 21) “Hemodilution”—viscosity1.99 ± 0.02 mPa*s, hematocrit 31.48 ± 0.31%. Group 2 (n = 32) “Norma”—animals with unchangedblood levels—viscosity 2.84 ± 0.03 mPa*s, hematocrit 41.60 ± 0.3%.Group 3 (n = 32) “Erythrocytosis”—viscosity3.95 ± 0.04 mPa*s, hematocrit 54.56 ± 0.23%. Dynamic blood viscosityin vitro studies were carried out on oscillatory viscometer. Inorder to evaluate hematocrit level heparinized whole blood was centrifugedin glass capillaries using; hematocrit values were assessed takinginto account sedimentation of formed elements column using a hematocritreader card. Blood flow in skin microcirculatory bloodstream ofrats` left thigh area was estimated by HFDU method using Minimax-Doppler-Khardware and software system, with ultrasound transducer (frequency20 MHz). Statistical analysis showed the models are correct. Bloodindicators of the animals in three experimental groups differedstatistically and significantly in terms of blood viscosity andhematocrit. Discriminant analysis was used to determine the relations betweenrheological blood parameters and characteristics of blood velocityin microcirculatory bloodstream which made it possible to identifythe most significant characteristics of blood flow that tend tochange depending on altered blood composition. These include: meansystolic velocity Vas (p < 0.01), mean velocity Vam (p <0.001), mean volume velocity Qam (p < 0.001), vascular resistanceindex RI (p <0.01) and the percentage of blood cells moving in low-speed H’ (p =0.03). The reliability of selected characteristics was checked withone-way ANOVA; and their significance in determining membershipin “Hemodilution”, “Norma” or “Erythrocytosis” groups accordingto HFDU data was confirmed. Based on this analysis classificationfunctions were generated for non-invasive dynamic blood viscosity determinationaccording to Doppler ultrasound data.