Spectral Regularities of Viscoelastic Parameters of Whole Blood Exposed to Periodic Shear Stress.

Theoretic and experimental study of viscoelastic properties of the whole blood exposed to shear stress was carried out with acoustic resonance method based on the measurement of gain-frequency characteristics of resonating needle in an ARP-01M piezoelectric thromboelastograph (Mednord). The study revealed regularities in the changes of viscoelastic parameters of the whole blood within 0-80 kHz frequency range of shear vibrations. In this frequency range, the elastic (storage) modulus G' reflecting blood elasticity increased with frequency and significantly contributed to the complex viscosity coefficient. The revealed gain-frequency regularities open the vista to employ the acoustic resonance method to determine the viscoelastic parameters of the whole blood and their coagulation-induced changes in the wide frequency range of shear vibrations.

Analysis of Viscoelastic Parameters of Fluids by Low-Frequency Piezoelastography.

Theoretical and experimental analysis of viscoelastic properties of fluids at low oscillating shear stresses was performed. Mathematic approach for calculating the complex coefficient of viscosity on the basis of experimental data on the amplitude-phase characteristics measured by the method of low-frequency piezoelastography was developed. The dependencies of the amplitude and phase shift of the signal recorded by a piezoelectric detector of a ARP-01M Mednord piezoelectric thromboelastograph on the frequency of forced oscillations of a resonator needle in air, water, and glycerin at fixed temperature of 37°C were studied. It was found that with increasing fluid viscosity, the resonance frequency of oscillations decreases in comparison with the frequency of oscillations in air.

[THE ROLE OF LOW-FREQUENCY PIEZOTHROMBOELASTOGRAPHY IN THE COMPREHENSIVE EVALUATION OF HEMOSTASIS IN CORONARY BYPASS SURGERY WITH CARDIOPULMONARY BYPASS].

Aim: To monitor the hemostatic system during platelet concentrate transfusions using low-frequency piezothromboelastography in patients with coronary bypass surgery given aspirin therapy. Materials and Methods: The study involved 148 patients with coronary bypass surgery, with 76 ones undergoing intraoperative transfusion of platelet concentrate and 72 treated without transfusion. The control group consisted of 20 healthy individuals. In the perioperative period indicators of vascular-platelet, coagulation, anticoagulant and fibrinolytic components of hemostasis were evaluated by low-frequency pezotromboelastography using the ARP-01M "Mednord" hardware and software system (Russia). Results: It was shown that the antiplatelet effect of aspirin in the preoperative period was manifest as inhibition of the initial stage of blood coagulation accompanied by increased thrombin potential, the total gain of anticoagulant and fibrinolytic activity of the blood. Heart-lung bypass was accompanied by structural and chronometric anticoagulation, reduction of anticoagulation and increase of blood fibrinolytic activity. In the postoperative period, structural and chronometric anticoagulation was more pronounced in patients who did not undergo transfusion of platelet concentrate than in the group of patients with transfusion. Donor platelets further increased the blood hemostatic potential by neutralizing the antiplatelet effect of aspirin. Perioperative thrombohemorrhagic complications were absent in both groups. Conclusion: Low-frequency piezothromboelastography provides a tool for real-time monitoring the functional state of hemostasis system. Transfusion of platelet concentrate is not advisable given that the thrombin potential is preserved as confirmed by the results of low-frequency piezothromboelastography.

DIAGNOSTICS AND CORRECTION OF THROMBOHEMORRHAGIC DISORDERS IN PATIENTS WITH GIANT UTERINE MYOMA AT THE PERIOPERATIVE STAGE OF TREATMENT.

The aim of the study was to reduce perioperative blood loss in patients with giant uterine myoma. As a result of studies have provided evidence that the use of anti fibrinolytic therapy as intravenous infusion of tranexamic acid for 30 minutes before the surgery in a dose of 20 mg/kg followed by infusion of 5 mg/kg per hour for the first postoperative day, helped to reduce perioperative blood loss by 29%. Hemoglobin level was higher by 10% (p < 0,05), blood loss was lower by 29% (p < 0,05), the length of stay in hospital was reduced by 24% (p < 0,05) in patients of the second group on the second postoperative day.

Global Tests in Evaluation of the Function of Pro-and Anticoagulant Systems: Present and Future.

Comparative analysis of the effectiveness of global tests for evaluation of the blood coagulation systems demonstrated the possibility of obtaining express data on hemostasis stages I-II and III when working with native substrate (whole blood). Changes in viscous characteristics of the whole blood recorded ex vivo during hemocoagulation allowed us to propose the concept of permanency of fibrinogenesis as the obligatory in vivo process determining the hemostatic potential, an integral characteristic of the hemocoagulation cycle providing sufficient blood fluidity and limiting extravasation of blood components under conditions of permeability disturbances and damage to the vascular wall.

[The functional status of pregnant women hemostasis according to the "global" low-frequency piezothromboelastography test].

This paper presents the research of the hemostatic whole blood's potential of healthy and pregnant women (39-40 weeks) according to the clinical data using the "global" low-frequency piezothromboelastography. Three types of the hemostatic potential (hypo-, normal- and hipercoagulative) are exposed in the status of the physiological optimum. It is shown that when forming the syndrome of the general circulator adaptation of the organism to the pregnancy and the childbirth is accompanied by intensification of thrombin activity and compensatory strengthening of total antihaemostatic activity. It is shown that only the timely research of the whole blood with aliquoties of endotelium (a number of them effects in the bounded time duration) producers tests, blood corpuscle and hemostasis factors, can provide the unbiased information about "time sample" of the hemostatic potential status.