Blood Circulation Parameters Research Articles

Unveiling the human fetal-maternal interface during the first trimester: biophysical knowledge and gaps.

The intricate interplay between the developing placenta and fetal-maternal interactions is critical for pregnancy outcomes. Despite advancements, gaps persist in understanding biomechanics, transport processes, and blood circulation parameters, all of which are crucial for safe pregnancies. Moreover, the complexity of fetal-maternal interactions led to conflicting data and methodological variations. This review presents a comprehensive overview of current knowledge on fetal-maternal interface structures, with a particular focus on the first trimester. More in detail, the embryological development, structural characteristics, and physiological functions of placental chorionic plate and villi, fetal membranes and umbilical cord are discussed. Furthermore, a description of the main structures and features of maternal and fetal fluid dynamic exchanges is provided. However, ethical constraints and technological limitations pose still challenges to studying early placental development directly, which calls for sophisticated in vitro, microfluidic organotypic models for advancing our understanding. For this, knowledge about key in vivo parameters are necessary for their design. In this scenario, the integration of data from later gestational stages and mathematical/computational simulations have proven to be useful tools. Notwithstanding, further research into cellular and molecular mechanisms at the fetal-maternal interface is essential for enhancing prenatal care and improving maternal and fetal health outcomes.

Mathematical modelling of peripheral haemodynamics of the shin in volleyball players of mesomorphic somatotype

Statistical modelling of peripheral haemodynamics indicators, which is conducted based on determining anthropometric and somatotypic features of the organism, can be considered a new way of personalising instrumental diagnostic examination. Therefore, determining the suitable rheovasographic parameters of the shin in highly skilled volleyball players of a particular somatotype is relevant. The purpose of this study was to investigate the total influence of indicators of the external structure of the body on the value of indicators reflecting the specific features of blood circulation in the shin in volleyball players of mesomorphic somatotype. A comprehensive clinical and laboratory study of the state of health and physical development of 108 volleyball players aged 16-20 years was conducted. The method of tetrapolar rheography with the use of a diagnostic computer multifunctional apparatus was used to determine the rheovasographic parameters of the shin, amplitude, time, and indicators of the ratio of amplitude and time rheovasographic parameters were evaluated. An anthropometric study of total and partial body measurements was carried out. Somatotyping was performed using the Heath-Carter method. The study selected 28 volleyball players of mesomorphic somatotype. Statistical models were created using direct stepwise multivariate regression analysis. For all amplitude and time rheovasographic parameters of the hip in volleyball players of mesomorphic somatotype, statistical models with high accuracy of description of signs were built. The 10 models included 94 anthropometric dimensions. The key determinants of shin blood circulation parameters are body circumference (most often forearm, neck, and shin circumference), chest and pelvic diameters, thickness of skin and fat folds (most often on the shin, abdomen, flank), and width of the epiphyses of long tubular bones. It was found that the indicators of external body structure within 63.84- 99.99% determine the value of indicators of regional blood circulation on the shin in volleyball players of mesomorphic somatotype. Statistical modelling makes it possible to determine the proper values of individual rheovasographic indicators on the shin depending on the anthropometric parameters of individuals of a certain gender, age, somatotype, which is especially significant for athletes of a certain sport, since their cardiovascular system indicators are greatly influenced by the specifics of sports activity

Proposed cardio-pulmonary model to investigate the effects of COVID-19 on the cardiovascular system

In this paper, we propose a new mathematical model of cardiovascular system coupled with a respiratory system to study the effects of COVID-19 on global blood circulation parameters using the lumped parameters model. We use the fourth-order Runge-Kutta method for solving the sets of equations of motion. We validate our model by showing that the simulated flows in pulmonary and aortic valves corroborate, respectively, the results established by Smith et al. [IFAC Proceedings Volumes, 39 (2006) 453–458]. Then we examine the effects of the new coronavirus (covid-19) on the cardiopulmonary system through the impact of the high respiratory frequency and the variation of the alveoli volume. To achieve this aim, we propose a new exponential law for the time varying of the pulmonary resistance. It appears that when the respiratory frequency grows, the delay between the systemic artery flow and the flow in the pulmonary artery diminishes. Therefore, the efficiency of the cardiac pump is reduced. Moreover, our results also show that variations of the alveoli volume cause the increment of the pleural pressure in the vascular cavities that induces an exponential growth of the pulmonary resistance. Furthermore, this growth of the pulmonary resistance provokes the augmentation of pressure in some organs and its reduction in others. We found that patient with covid-19 having a prior history of cardiovascular diseases is exposed to a severe case of inflammation/damage of certain organs than those with no history of cardiovascular disease.

Formation and informative content of photoplethysmographic signal under the conditions of controllable external compression

The physical nature and quantitative characteristics of the photoplethysmographic (PPG) signal under conditions of external compression of the studied tissue area are theoretically investigated. Dependences of the constant and variable components of the PPG signal on the applied pressure are revealed, which have maxima at certain compression values. The physical model of the PPG signal formation process takes into account the optical and mechanical properties of biological tissues. The model is based on the consideration of the diffuse propagation of light in a two-component scattering medium (blood + surrounding tissues) and employs the Kubelka – Munk two-stream theory; in this case, the amount of blood in the tissues is determined by the conditions of mechanical equilibrium and the laws of tissue deformation.
 It is shown that the developed model correctly describes the observed qualitative features of the PPG signal, and the condition for the best agreement between theoretical and experimental curves allows real-time determination of the peripheral microcirculation quantitative characteristics (mean value and amplitude of the blood pressure fluctuations in precapillaries, erythrocyte concentration, average degree of blood oxygenation, the vessel walls elasticity, etc.). The developed methods for determining the blood circulation parameters can be used as the basis for inexpensive and effective express methods of research and medical diagnostics, which are especially useful in mass surveys or in environmental monitoring.

The concentration of lidocaine in the blood after intravenous and epidural administration with extensive hepatic resections

The aim of the work: to identify the concentration of lidocaine in patients’ blood during an extensive hepatic resection, with its intravenous and epidural administration in dynamics for intra- and postoperative analgesia, to evaluate its analgesic effect and toxicity potential. Materials and methods. The study included 27 patients, who underwent hepatic resection with preservation of 30–60 % of the parenchyma. For all patients, multicomponent intraoperative anesthesia was used. Depending on the adjuvant, patients were divided into two groups: the main group (group 1) consisted of 7 patients who received intravenous (IV) administration of lidocaine, and a comparison group of 20 patients (group 2) whose complex anesthesia was supplemented with thoracic epidural anesthesia (EDA). To solve the tasks was to develop and validate a rapid, sensitive and robust method for the detection and quantification of lidocaine in human plasma using purification by coagulation and ultracentrifugation with cooling followed Liquid chromatography with Orbitrap HRMS method. The method showed a dynamic linear range of 0.1 to 1000 ng/mL with a linearity expressed by the regression coefficient (R2) and a value of 0.9947. The quantitation limit (LOQ) was found to be 1 ng/mL and the detection limit (LOD) 0.3 ng/mL. Recovery accuracy and repeatability were satisfactory. Finally, the method was applied to 54 real human plasma. Results and Discussion. 2 hours after the surgery, there was a tendency (P = 0.29) for a higher concentration of lidocaine in the blood by 28.8 % after epidural administration of lidocaine compared with intravenous administration (1.84 μg/ml in group 1, 2.37 µg/ml – in group 2, p = 0.29), with no fundamental difference 14 hours after surgery (2.62 µg/ml and 2.85 µg/ml, p = 0.76). Epidural administration of the drug was also accompanied by a tendency to increase the frequency of hemodynamic disorders, which was reflected in an increase in the dose of norepinephrine, which was intended to correct blood circulation parameters, by 1.3 times (total dose in group 1 (158.4±58.1) ng, group 2 – (206.9±76.4) ng, p = 0.14). No life-threatening toxic reactions were noticed in any of the cases. The use of lidocaine as an adjuvant for intra- and postoperative analgesia by intravenous and epidural administration with extensive hepatic resections, in most cases, does not lead to an increase of the drug compound in the blood higher than the generally accepted toxic content is. The content of the drug in the blood can be exceeded with epidural administration compared with intravenous administration. The analgesic effect of intravenous lidocaine is not lower than the epidural and may even last longer until the first administration of a narcotic analgesic after surgery for pain relief. However, epidural block is accompanied by intraoperative hemodynamic instability and an increase in the total dose of norepinephrine to correct blood circulation parameters.

The Immediate Effects of the Manual Therapy Traction Manipulations on Parameters of Cardiorespiratory System Functioning

The aim of this study was to determine the changes in the cardiorespiratory system activity under the influence of traction manipulations in the thoracic spine. The study involved 26 adults, including 18 women aged 39.6 ± 12.1 years and 8 men aged 36.3 ± 8.3 years. The mean age of patients was 38.6 ± 11.2 years. The work used an integral method of studying the cardiorespiratory system - spiroarteriocardiorhythmography (SAKR). SACR registration was performed before and after traction manipulations in the thoracic spine directly in the procedure of manual therapy. The study of the immediate effect of traction manipulations of SMT in the thoracic spine on the cardiorespiratory system allowed establishing the main significant effects: decrease in HR (min^-1) from 85.1 (77.1; 94.2) to 79.5 (69.8; 87.6), p=0.000, decrease in duration of QTC (s) from 0.419 (0.404; 0.434) to 0.413 (0.401; 0.427), p=0.012, decrease in CO (dm³) from 5.2 (4.6; 5.8) to 4.9 (4.4; 5.6), p=0.000, SI (dm³/m²) from 3.05 (2.75; 3.30) to 2.90 (2.62; 3.20), p=0.000, increase in Vexp (L/s) from 0.28 (0.22; 0.34) to 0.31 (0.25; 0.39), p=0.030. The obtained data suggest that the main effects of traction manipulations on the thoracic spine are associated more with the changes in hemodynamic parameters of blood circulation due to activation of expiratory muscles and chest mobility, when the suction mechanisms of the chest and cardiovascular function of diaphragm are activated.

Effect of Melatonin on the Expression of LYVE-1 Receptor in Liver Sinusoidal Endothelial Cells of Mice with the Light-Induced Functional Pinealectomy Model.

Intragastric administration of melatonin in physiological doses (1 mg/kg body weight) for 14 days to C57BL/6 mice with light-induced functional pinealectomy model (24-h lighting for 14 days) results in an increase in the LYVE-1 expression area by 2.4 times and a significant increase in receptor concentration (1.6% decrease in staining brightness) in liver sinusoidal endothelial cells in comparison with animals kept under continuous lighting and not treated with the hormone, which indicates the formation of stability of the endothelial barrier in the organ. Melatonin treatment also enhanced lymphatic drainage in all it links (including interstitial non-vascular pathways and lymphatic vessels) and improved structural and functional parameters of blood circulation and lymph flow in the organ, which created conditions for reducing metabolic load on structural elements of the liver.

Персонализированная математическая модель сердечно-сосудистой системы с механизмом барорефлекса

Patient’s physical activity is one of the most important indicators that influences the cardiovascular conditions. The baroreflex is the mechanism that contribute to the regulation of arterial blood pressure. It maintains an optimal level of the arterial pressure as a response to changes in the patient’s activity. This work considers the developed mathematical model describing the cardiovascular system from the point of view of global distributions of parameters: pressures, flows and volumes in the parts of the cardiovascular system. It was shown that the model reproduces normal blood circulation, heart failure and pediatric circulation with an accuracy that meets the goals of modeling. Blood pressure automated regulation mechanism represents changes that occur during an increased level of activity for a healthy patient. The heart rate during the state of rest is about 80 bpm; the mean arterial pressure is 104 mm Hg and the flow rate in the system is 5.4 l/min. During the physical activity the heart rate increases to 130 bpm; the mean arterial pressure is 108 mm Hg and the flow rate in the system is 8 l/min. A comparison was made for the four most important parameters of blood circulation. It has been established that the model reproduced the parameters of blood circulation with sufficient accuracy: the relative error was less than 6 %. The developed model can be used in personalized medicine for individual modeling for the patient’s blood circulation with account taken of various parameters of the patient: age, physique, diseases, and different levels of physical activity. For the further research, the model can be supplemented with a ventricular assist device during the heart failure state with purpose to study interactions in the biotechnical system.

Autoinhibition of Mouse Von Willebrand Factor: Addressing the Species Compatibility between VWF and Gpibα in Humans and Mice

Introduction: The usage of mouse models to investigate thrombosis and hemostasis has now spanned several decades, with the advent of genetic manipulation elucidating the roles of platelet receptors, secondary messengers, and coagulation factors to name a few. While there are many similarities between humans and mice, the vast differences in physical parameters of blood circulation and coagulation should not be ignored. The incompatibility of mouse platelet receptor glycoprotein (GP)Ibα with human von Willebrand factor (VWF) has been well documented, yet human GPIbα can interact with mouse plasma VWF under shear. In light of the recently discovered autoinhibitory module (AIM) in modulating the activity of human VWF, here we seek to address the role of the AIM in species compatibility between these two interacting proteins.Methods: Recombinant human and mouse VWF fragments containing the A1 domain and either intact or truncated AIM, followed by a poly-histidine tag, were expressed from stably transfected mammalian cells. Recombinant human and mouse GPIbα ligand-binding domain (LBD) (residues 1-290, mature protein numbering) were similarly expressed bearing a biotin acceptor sequence and poly-histidine tag. Stable cell lines co-expressing E. coli biotin ligase were used to express and biotinylate the LBD protein before purification. All proteins were purified by nickel-affinity chromatography followed by size exclusion chromatography. Bio-layer interferometry was performed on an Octet QK e using streptavidin biosensors to capture biotinylated GPIbα LBD fragments. Data was analyzed using a 2:1 heterogeneous ligand binding model for kinetic parameters, and steady state affinity (K D) was calculated either from binding responses at the end of the association phase, or from predicted equilibria from the aforementioned model. Human or mouse washed platelets were isolated by centrifugation, followed by pelleting the PRP in the presence of PGE-1. Platelets were resuspended to 150,000/ μL in modified Tyrode's buffer, and aggregation was monitored in a light transmission aggregometer.Results: Consistent with earlier reports, human AIM-A1 protein (VWF residues 1238-1493), at concentrations below 1 μM, showed no appreciable binding to human GPIbα LBD. Conversely, human truncated AIM-A1 protein (tAIM-A1, residues 1261-1472) exhibited a K D of 348 nM towards the LBD. Mouse tAIM-A1 proteins showed enhanced binding to mouse LBD (K D = 214 nM), but mouse AIM-A1 is able to bind to mouse LBD with a K D of 716 nM, which is considerably higher than the affinity of the human-human pair of tens of μM (Figure 1).Given the increased affinity of mouse AIM-A1 to mouse LBD, we reasoned that the mouse AIM may be less stable than the human counterpart. A chimeric AIM-A1 protein, in which human AIM sequences flank mouse A1 (human residues 1238-1271, mouse 1272-1458, and human 1459-1493), was generated. The chimeric AIM-A1 showed little binding to mouse LBD. However, this protein can still aggregate washed platelets from both species and bind to gain-of-function human GPIbα, indicating it still is a folded domain capable to recognizing its cognate receptor, mouse GPIbα (Figure 2).The isolated mouse AIM-A1 fragments are capable of inducing robust mouse and human platelet aggregation for washed platelets in a dose dependent manner. It had been previously demonstrated that in platelet rich plasma, ristocetin has no effect on mouse VWF. However, washed mouse platelets incubated with 60 nM of mouse AIM-A1 followed by addition of 1.5 mg/mL ristocetin was able to agglutinate the platelets (Figure 2). These results suggest that these proteins may be used to help elucidate the signaling pathways of GPIb-IX-V complex in mice.Conclusion: In agreement with previous reports, we observe that in general mouse AIM-A1 is more active than human AIM-A1 in its propensity to bind to GPIbα. On the aspect that human VWF in incompatible with mouse platelets, we observed that mouse LBD has lower affinity for human tAIM-A1 than human LBD does for mouse tAIM-A1. These findings altogether suggest that there are likely differences in activation forces for each species AIM, and that the GPIbα-A1 interactions, in terms of their mechanical and thermodynamic properties, are somewhat unique, and perhaps optimized, for each species. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Basic principles of infusion therapy: fundamentals of fluid and electrolyte balance

Background. Infusion therapy (IT) is a method of managing the functions of the organism by influencing purposefully the morphological composition and physiological properties of blood through parenteral administration of organic and inorganic solutions. The main feature of IT is that the drug completely enters the bloodstream.
 Objective. To describe the main characteristics of fluid and electrolyte balance and the IT principles.
 Materials and methods. Analysis of the literature sources on this topic.
 Results and discussion. Fluid comprises about 60 % of the human body (in children – 70-80 %, in adults – 60 %, in elderly – 50-55 %). Total fluid includes intracellular and extracellular. The latter, in turn, is divided into intravascular, interstitial and transcellular. Water balance involves the balance of fluid entering the body and the fluid being excreted. The main sources of water are beverages and food, however, about 300 ml per day is formed endogenously during oxidation processes. The main ways of the fluid excretion are its excretion in urine and stool, and perspiration losses. To calculate the physiological need of water for an adult, the body weight should be multiplied by the coefficient of 30 (up to 65 years), 25 (65-75 years) or 20 (more than 75 years). IT should also take into account the pathological losses of water from fever, vomiting, diarrhea, the presence of large wounds or burns, as well as reduction of the need in water in renal or heart failure. Thus, physiological needs, fluid deficiency, fluid volume as a result of pathological loss should be added, and the oral rehydration subtracted from this sum to calculate IT volume. There are 3 degrees of dehydration severity: I degree – deficiency of 1-2 liters, thirst, oliguria; II degree – deficiency of 4-5 liters, thirst, oliguria, dry skin, mucous membranes and tongue, general weakness; III degree – deficiency of 7-8 liters, consciousness disorders, decrease in arterial pressure, shock. The first degree can be overcome by oral rehydration, the second degree – by 50 % of oral rehydration and 50 % of IT, the third degree – by 70-100 % of IT. IT solutions are divided into crystalloids, colloids, polyatomic alcohols and special drugs. Preparations of polyatomic alcohols include, in particular, Reosorbilact, Sorbilact, Xylate (“Yuria-Pharm”). Complications of IT are divided into complications associated with the violation of the technique of entering the bloodstream (injuries of blood vessels and adjacent organs, hematomas, foreign bodies in the vessels and heart, the solution misplacement out of the vascular space); complications associated with the violation of the technique of drug administration (thromboembolism, air and fat embolism); complications associated with the wrong rate of solutions’ administration (heart overload, hypervolemia, pulmonary edema, cerebral edema); complications associated with the characteristics of infusion solutions (partial hemolysis of blood cells, acid-base imbalance, disorders of blood osmolarity, local cooling of the heart); complications associated with the IT method; complications due to individual intolerance; infectious complications in case of violation of asepsis and antiseptics; infectious diseases. Criteria for IT security include the knowledge of the drug composition and understanding of the instructions for its use; multicomponentity; use of the minimum effective doses; monitoring of the excreted urine and other fluids and infused solutions; strict control of fluid balance and blood circulation parameters.
 Conclusions. 1. IT is an important tool in treatment of many diseases, which performs a wide range of tasks. 2. The IT solution should be chosen depending on the individual needs of the patient. 3. Criteria for IT safety include the knowledge of drug composition and instructions for its use; multicomponentity; use of the minimum effective doses; monitoring of excreted urine and infused solutions; control of fluid balance and blood circulation parameters.

Energy of blood circulation in primary reduction of myocardial contractility

The aim: to study the energy parameters of the circulatory system in heart failure in patients with acute coronary syndrome (ACS) against the background of coronary artery bypass grafting (CABG), depending on the degree of myocardial contractility decrease.Materials and methods. In 48 patients with ACS in the perioperative period energy parameters of blood circulation have been determined: flow power (FP), oxygen reserve (OR) and circulatory reserve (CR). FP reflects the useful power of the myocardium, OR – the correspondence of oxygen absorption by tissues to their needs, CR is an integral energy parameter. Patients have been divided into 2 groups: group CF1 (n = 18) – patients with an ejection fraction (EF) of less than 40 %, group CF2 (n = 30) – patients with EF of at least 40 %. The same treatment has been performed in both groups.Results. The initial energy parameters of circulation were significantly reduced, more so in the CF1 group. During treatment, FP, OR, and CR in the CF1 group increased more slowly than in the CF2 group, and remained significantly lower by the end of the study. The initial CR was highly correlated with the need for dobutamine, the duration of postoperative artificial blood circulation, and postoperative mechanical ventilation, so CR can also be used as a predictive criterion.Conclusions. Determination of energy indicators of blood circulation allows you to fully assess the state of the circulatory system, predict the course of its insufficiency and monitor the effectiveness of its treatment. The severe decrease in myocardial contractility, accompanied by a decrease in the EF to 40 % or lower, slows down the recovery of energy parameters of circulation and requires the search for more effective methods of intensive therapy

Comparative Analysis of Peripheral Blood Circulation Parameters in Long-Distance Swimmers at Middle Altitude and Under the Conditions of a Hypoxic Gas Environment

Comparative Analysis of Peripheral Blood Circulation Parameters in Long-Distance Swimmers at Middle Altitude and Under the Conditions of a Hypoxic Gas Environment

RESULTS OF A FIVE-YEARS FOLLOW-UP OF THE PHYSICAL PERFORMANCE OF YOUNG MALE SKIERS

The aim of the study was to assess physical performance over a five-years period in young male cross-country skiers living in the Russian North. Methods. Anthropometric data and parameters of blood circulation, respiration and energy expenditure were studied in 20 skiers aged 15-20 years in the Komi Republic. A bicycle ergometer with Oxycon Pro system (Germany) was the main assessment instrument. Tests were performed twice - at the beginning and in the end of a five-years period. Results. A statistically significant increase in body weight and body mass index, a decrease in heart rate (HR), systolic blood pressure, pulse pressure, double product (DP) and the vegetative Kerdo index at rest were observed indicating an increase in physical fitness. At a load of 200 W, a decrease in heart rate, DP, oxygen consumption and energy expenditure and an increase in efficiency were found suggesting economization of blood circulation and energy reactions during standard operation. However, at maximum load an increase in blood pressure from (185.0 ± 15.2) to (195.0 ± 11.6) mm Hg p = 0.038; a decrease in the maximum oxygen consumption from (67.4 ± 6.20) to (61.4 ± 7.21) ml / min x kg, p = 0.012; decreased oxygen consumption on the brink of anaerobic metabolism from (4,036 ± 594) to (3,623 ± 593) ml / min, P = 0.040; and heart rate on the brink of anaerobic metabolism from (171.0 ± 11.6) to (157.0 ± 16.5) bpm, p = 0.005 was revealed suggesting a decrease in the maximum functional capabilities of the body. Physiological costs of a unit of work for various indicators of blood circulation, respiration, and energy expenditure have not changed over a five-years period (p values varied from 0.082 to 0.935). Conclusions. The observed decrease in the level of physical performance by aerobic and anaerobic thresholds may suggest not only the beginning of age-related changes in the body of athletes in the North, but may also reflect possible negative impact of living conditions in the North.

PREDICTING THE OUTCOME OF CIRCULATORY FAILURE, OR THE USE OF ANALOGIES IN MEDICINE

The article offers a method for predicting the outcome and monitoring of intensive therapy of circulatory failure based on the assessment of energy parameters of blood circulation. Development of prognostic criteria for the course of circulatory failure. Electrodynamic modeling of the circulatory system has been applied, as a result of which a number of new parameters of the circulatory system have been introduced and a new look at the known ones is presented. The reference values of the proposed energy indicators have been determined in the study of blood circulation in 30 healthy volunteers. It has been found that the integral energy parameter of blood circulation - circulatory reserve (CR) - in healthy individuals is (617±145) mW/m2. In heart failure on the background of acute coronary syndrome and ejection fraction not more than 40 % CR is (184±58) mW/m2, over 40 % - (367±86) mW/m2, in vascular failure, requiring the correction of α1-agoiiists - (202±65) mW/m2, in the absence of this - (384±77) mW/m2, in blood loss 40 % of BCV and more - less 50 mW/m2. The level 100 mW/m2 is dangerous and reflects the high probability of death, 50 mW/m2 is incompatible with life. Electrodynamic modeling of the functioning of the circulatory system in different conditions allows us to deepen the understanding of the mechanisms of its autoregulation. Autoregulation of blood circulation in different conditions is a multi-factorial and difficult to-predict process and can only be evaluated by taking into account various combinations of its kinetic and dynamic indicators. Energy analysis of the functioning of the circulatory system allows to make an integral assessment of the effectiveness of autoregulation of blood circulation and its correction, as well as to predict the outcome of intensive therapy of circulatory insufficiency. A CR level below 100 mW/m2 is dangerous and predicts an adverse outcome of circulatory failure with a high probability. Key words: circulatory energy, heart failure, vascular failure, hypovolemia.

Energy of blood circulation during blood loss

The state of circulatory energy in blood loss has been studied in 44 patients with spleen injury. Kinetic (final diastolic and systolic volumes of the left ventricle, heart rate), dynamic (effective arterial and central venous pressure, total peripheral resistance), hemic (oxygen content in arterial and venous blood) parameters of blood circulation, as well as the level of lactate reflecting the degree of hypoxia were studied. The energy indicators of blood circulation were determined: the power consumed by tissues, the oxygen reserve (reflecting the correspondence of the oxygen consumed by tissues to their needs) and the integral energy indicator - circulatory reserve. It has been determined that with an increase in blood loss, the energy indicators of blood circulation decrease: the power consumed by tissues decrease to (48.0±6.1); (41.1±8.7) and (23.5±9.3) mW/m2, the oxygen reserve decrease to (0.43±0.04); (0.37±0.05) and(0.27+0.07), the circulatory reserve decrease to (229+93); (180±41) and (47±25) mW/m2 respectively at blood loss 20 %, 30 % and 40 % of blood volume. Apparently 20 % blood loss is the maximum amount of blood loss in relation to compensatory possibilities of autoregulation of blood circulation. 30 % blood loss causes more strain on the compensatory mechanisms, at 40 % blood loss the possibility of autoregulation is exhausted. All patients with blood loss up to 20 and up to 30 % of the blood volume survived in the future, with 40 % blood loss 30 % of patients could not be saved. In all deceased patients the circulatory reserve was below 50 mW/m2. It has been determined that a decrease in the circulatory reserve to 100 mW/m2 or lower is a serious threat to life and requires great intensive therapy for blood loss, the level of the circulatory reserve of 50 mW/m2 is not compatible with life, that is, it corresponds to irreversible hemorrhagic shock. Keywords: blood loss, hypovolemia, circulatory energy, blood flow power, oxygen reserve, circulatory reserve.

Comparative results of thyroid cryoablation in SHR and vistar rats

Introduction. Today, cryosurgery is considered as a promising minimally invasive approach to the treatment of benign nodules of thyroid gland. Blood circulation in the tissue can affect the effectiveness of cryoablation preventing decline of the temperature. This is true for the thyroid gland, which belongs to organs with a high blood circulation rate. The SHR rat can be used for modeling the processes of thyroid cryoablation in people with essential hypertension, which makes it possible to obtain calculated data on reaching the target freezing temperature in patients with arterial hypertension. Aim of the study – make a comparative assessment of histological characteristics of thyroid gland tissue in hypertensive SHR rats and normotensive Wistar rats after cryoablation. Materials and methods. In the experiments, SHR and Wistar rats weighing 250–280 g were used. Cryodestruction of the thyroid gland was carried out in intact animals and rats, which were administrated with a 0.1 % solution of propylthiouracil to induce diffuse thyroid hyperplasia. The operation was performed under general anesthesia. Cryotherapy was carried out for 40 s once on the left lobe of the thyroid gland using a copper cryoprobe, which was cooled to the temperature of liquid nitrogen. On day 21, the animals were taken out of the experiment; the thyroid gland were taken and used for histological studies. Results. It was found that at the site of cryotherapy in gland samples of animals of both lines on day 21, a cone-shaped zone of fibrosis was formed, in which the parenchyma of the gland was replaced by connective tissue with pronounced vascularization and insignificant lymphocytic-histiocytic infiltration. The mean area of fibrosis did not differ significantly between the groups of intact SHR and Wistar rats. After cryoablation of glands with administration of propylthiouracil, a decrease in the area of fibrotic changes was observed: in Wistar rats – by 2 times, in SHR rats – by 3–4 times. Conclusions. Parameters of blood circulation in arterial hypertension did not significantly affect the result of thyroid gland cryoablation in rats. However, after induction of tissue hyperplasia with propylthiouracil, an increase in gland resistance to cryodestruction is observed, which should be taken into account when choosing a cryotherapy regimen.

ANALGESIA FOR AGED AND GERIATRIC PATIENTS DURING CARDIAC SURGERY WITH CARDIOPULMONARY BYPASS

Balanced perioperative multimodal analgesia using multiple synergistic agents minimizes side effects that can be caused by high doses of only one aesthetic agent. The aim of the work was to determine the efficacy of perioperative multimodal low-opioid analgesia as anesthetic assurance techniques in aged and geriatric patients during cardiac surgery with cardiopulmonary bypass.Materials and methods. The study included 18 patients (11 (61.1%) men and 7 (38.9%) women) aged from 63 to 76 years old (mean age 69.5±6.2 years), who underwent coronary artery bypass grafting with cardiopulmonary bypass support. The average body weight was 89.6±13.9 kg (75 to 115 kg). The anaesthesia consisted of intravenous (iv) administration of propofol in a dose of 1.52±0.05 mg/kg and fentanyl in a dose of 1 μg/kg. Muscle relaxation was achieved by injecting pipecuronium bromide in a dose of 0.1 mg/kg. Sevoflurane inhalation was used to maintain anesthesia. Before making incision, the subnarcotic dose of ketamine (0.5 mg / kg) and lidocaine 1 mg/kg bolus were added with simultaneous administration of the continuous infusion of the latter in a dose of 1.5-2 mg/kg per hour. For postoperative analgesia ketorolac tromethamine was used. The intensity of the pain syndrome was assessed using a 10-point visual-analog scale of pain. The level of endocrine-metabolic response was determined by measuring the dynamics of lactate and cortisol.Results. The average dose of fentanyl, which was used for the patient during the whole time of anaesthesia, was 1.09±0.03 μg / kg per hour (on average 358.3±27.1 μg for all time of surgery). During the extracorporeal circulation and in the early postoperative period, the blood circulation parameters in all patients examined corresponded to the hemodynamic profile of the operated pathology. Positive verbal contact with patients was recorded in 18.6±3.4 minutes after the end of anaesthesia. The level of cortisol in the early postoperative period was 479.3±26.4 nmol/l. The average values of the intraoperative level of lactate were 1.61±0.2 mmol/l. The mean pain level in the first postoperative day in the examined patients was 4.6 ± 1.2 (3-6) scores by VAS, one day after the operation – 2.6±1.1 (1.5-4) scores by the VAS.Conclusions. Multimodal low-opioid analgesia provides an adequate analgesic effect in aged and geriatric patients that is confirmed by the absence of hemodynamic and endocrine-metabolic disorders. The use of ketorolac as a component of multimodal low-opioid analgesia is an effective method for achieving adequate postoperative analgesia and contributes to reducing the side effects associated with the use of narcotic analgesics.

Quality of life of patients with critical lower limb ischemia after prolonged spinal cord stimulation

Background. Several previous studies have demonstrated that spinal cord stimulation (SCS) can reduce the amputation rate in patients with critical lower limb ischemia (CLLI) and improve blood circulation parameters of the lower limbs. However, there is a lack of studies on the long-term effects of SCS on the quality of life (QoL) of patients with CLLI. Aim. The present study aimed to assess QoL changes in patients with CLLI after SCS system implantation in the long run (i.e., 30–60 months).Methods. This study included 38 patients with CLLI (10 females, 28 males; age range: 39–83 years) who underwent surgery in 2012–2016. QoL was analyzed using the SF-36 questionnaire before and 30–60 months after SCS. The mortality and amputation rates and amputation levels of the patients were also analyzed. The SF-36 questionnaire scores were normalized according to the data of the respective sex and age groups in the general Russian population. The obtained scores were analyzed in their dynamics and compared with the scores of the general population.Results. The preoperative scores of three of four physical well-being QoL parameters of the patients significantly reduced compared with the scores of the general population (p < 0.001). However, the scores of mental well-being QoL parameters were close to those of the general population. The total physical well-being score reduced (37.9 ± 9.2 points), whereas the total mental well-being score was within the medium range (48.1 ± 8.3 points). At 30–60 months after SCS system implantation, 5 patients or their representatives were unavailable, 12 died, 3 underwent amputation at the tibial level, and 16 showed preserved support function of the legs (2 of these patients underwent toe amputation). SCS system failure was noted in 3 patients. Patients with preserved support function of the legs completed the SF-36 questionnaire at 30–60 months after SCS system implantation. All QoL parameter scores showed increases, and the total postoperative physical well-being score of these patients was close to that of the general population (46.3 ± 10.6 points, p = 0.050 compared with the preoperative score). However, the total mental well-being score of the patients was higher than that of the general population (57.9 ± 3.8 points, p = 0.041). Conclusion. SCS does not reduce the mortality rate in patients with CLLI compared with conservative therapy. However, it reduces the amputation rate in patients who survive. Significant positive changes in QoL persist for a long time after SCS system implantation in most patients. Funding: The study did not have sponsorship. Conflict of interest: Authors declare no conflict of interest.

Computer modeling in mechanics of circulation

Some cardiovascular pathology connected with variations in geometry, wall properties and microcirculatory disorders can be studied by computer simulations. The mathematical model that allows to calculate the parameters of blood circulation – velocities of blood and pressure, displacements of the artery walls - for a complex vascular tree in real time is proposed.The geometrical model is based on the detailed postmortem measurements on the systemic arterial trees (more than 1000 arterial segments). The aortic model consists of 32 aortic segments and 59 side branches of the aorta including the larger and medium vessels. Mathematical model of blood flow in the system is described by Womersley model of the pulsatile viscous flow in the viscoelastic tube using the pressure and volumetric rate continuity conditions at the bifurcations of arteries. The Windkessel and structured tree outflow boundary conditions at the outlets of the branches have been used. The solution has been found as superposition of the forward and backward running waves. Based on the model, blood circulation parameters were calculated in the aortic model (91 tubes). The calculation results correspond to in vivo measurements. It was shown most of the branches have zero wave reflection coefficients but the large branches like celiac, renal and iliac arteries could produce noticeable wave reflections. The smaller branches possess negative wave reflection coefficient and, thus, contribute to the blood suction effect and lower aortic resistance to the blood flow. It is shown, the individual geometry plays an essential role in the location of the positive and negative wave reflection sites along the aorta and, thus, in the pressure and flow patterns and blood distribution into the branches. The influence of occlusion of the iliac arteries, low/high wall rigidity, and total length of aorta are studied on different individual geometries. The model can be used for determination of the individual parameters for patient-specific cardiovascular models and further modeling of the outcomes of the surgical and therapeutic procedures.

STUDY OF RESULTS BETWEEN INITIAL AND FINAL SPECIFIC TESTS IN WOMEN WITH NORMAL PREGNANCY

PURPOSE: The aim of this study was to achieve a control model of basic functional indicators established by comparative analysis between the results of initial and final anthropometric and functional tests in women with normal pregnancy. METHODS: The research was done among 112 individuals, all Bulgarians, in the period 2015-2018, ages 21 to 31 years old. In order to fulfil the aim of the research we used: functional tests for assessing the effects of our original program build for the specific needs of pregnant women. The program content was branded under our family name: “Gym program for pregnant women Nesheva” and was validated in our doctoral thesis and then published in a book (under patent). RESULTS: During our original gymnastics program was registered data by specific tests and the analysis has shown that the average values (Mean ± SD) of the measured parameters, in the three periods of time (during the pregnancy) are statistically different (p <0.05), which is a natural process resulting from the changes taking place in the body of the woman with the progression of pregnancy. These values are interpreted as optimal prenatal weight gain, but probably gymnastics for pregnant women also favour the maintenance of normal values. Studied indicators are presented with the results of the Mean ± SD of the blood circulation parameters and the vital capacity of the pregnant women. CONCLUSIONS: The results in our study are in support to establishing a system for collecting and processing information on the clinical status, general and functional characteristics of pregnant women is a reliable basis for validating standards for regulated inclusion in physical activity programs in normal pregnancy. Indicators of blood circulation and vital capacity in relative resting conditions of pregnant women when enrolled in the gymnastics program are within the limit of normal.