Indicators (markers) of microcirculation stability (MCR) of the skin in symmetric areas of the head were studied in young (18-19-years-old) and elderly (60-80-years-old) male and female subjects. We performed synchronous MCR measurements of symmetrical areas of the head using laser Doppler flowmetry in 40 healthy volunteers (10 men and 10 women in each age group). Numerical values of stability markers (T1, T2, and ζ) and indicators of the right—left hemodynamic balance of the MCR (regression coefficients a1, a2, b1, b2) were obtained using the previously developed computational and experimental methods. The coefficients a2 and b2 that determine the contribution of the right MCR bed to the right—left hemodynamic balance were higher in elderly men than in young men, while in young and elderly women, no significant differences in the values of these coefficients were revealed. In young men, coefficients a2 and b2 were lower than in young women, while in elderly subjects, the sex differences in these coefficients were leveled. Young men have lower stability markers than women, while in elderly subjects, these stability markers were similar in men and women. No significant age and sex differences in the level of perfusion of the symmetrical temporal regions were found. The results attest to low stability of MCR in young men in comparison with young women and similar stability in old age, which, apparently, can be explained by the influence of sex hormones on the regulation of human cardiovascular functions.

The effect of intraperitoneal injection of LPS (pyrogenal, 100 μg/kg) on the asymmetry of the right—left hemodynamic balance of microcirculation (MCR) was studied in 10 male Wistar rats. Synchronous measurements of the MCR parameters of the outer surface of the symmetrical areas of the tail base were carried out by laser Doppler flowmetry. The coefficients of asymmetry of the regression relationships between changes in perfusion of each of the observation sides and the initial perfusion values of both the eponymous and opposite observation sides, as well as the mean values and coefficients of perfusion variation of the studied areas, were analyzed. Injection of pyrogenal changed parameters of the asymmetry of the right—left hemodynamic balance of MCR in comparison with the initial values. One hour after the injection of pyrogenal, the contribution of the left MCR bed to the right—left hemodynamic balance increased, and the right one decreased. At the same time, the value of the perfusion variation coefficient decreased on the left and increased on the right. The shift of the hemodynamic balance towards the left MCR bed led to significant increase in blood supply to the left MCR pool after pyrogenal injection. The results of the studies indicate a stress type of reaction of the animal body to the injected drug.

The indices of asymmetry of microcirculation in the skin of the temporal areas of the head in young male and female subjects were studied. In 20 healthy volunteers (10 men and 10 women, age 18-19 years), synchronous measurements of the microcirculation of the skin of the symmetrical temporal areas of the head were carried out by laser Doppler flowmetry. The coefficients of asymmetry of regression relationships between perfusion changes in each side and initial perfusion values in both the same and opposite sides, the distribution function of perfusion asymmetry coefficients, and variability of perfusion in the studied areas were analyzed. The sex differences of the measured characteristics of asymmetry were revealed. In men, the distribution functions of perfusion asymmetry are pointed, with positive excesses, and in women they were flat, with negative excesses. In female subjects, the contribution of the right microcirculatory bed to the right—left hemodynamic balance was higher. These findings support the hypothesis on greater plasticity of the female brain in comparison with the male brain.

Indicators (markers) of microcirculation stability of the temporal regions of the head in young male and female subjects were studied. In 20 healthy volunteers aged 18-19 years (10 men and 10 women), synchronous measurements of the microcirculation of symmetrical temporal regions of the head were performed by laser Doppler flowmetry. Numerical values of stability markers (T1, T2, ζ) and parameters a1, a2, b1, b2 of the differential equation system describing oscillatory processes in the microcirculation system of the studied regions were obtained using the computational and experimental methodology developed by us earlier. It is shown that the right-left hemodynamic balance of microcirculation in men is maintained at the expense of the balance between the change in blood flow on the right and the initial value of blood flow on the left (coefficient b1) and in women, by the balance between the change in blood flow on the left and the initial value of blood flow on the right (coefficient a2). In women, the contribution of the right channel of the microcirculation to the right-left hemodynamic is significantly higher than in men. In general, the quantitative indicators (markers) of the stability of the microcirculation of the temporal regions of the head in women were higher than in men, which attests to higher stress resistance of the female organism in comparison with the male.

A new non-invasive method for assessing stability of functioning of the human regional circulatory system was developed. The method includes synchronous measurements of the level of cutaneous blood microcirculation of symmetrical areas of paired human organs by laser Doppler flowmetry and subsequent mathematical analysis of Dopplerograms using an original computational and experimental technique based on a mathematical model developed by us in the form of a system of differential equations describing experimental patterns of left—right asymmetry of oscillatory processes in the human regional circulatory system. The proposed method allows evaluating the reserve capabilities of the regional circulatory system in a patient and increases informative value of studies. This non-invasive method can be used in clinical practice to perform a personalized assessment of the stability of regional blood circulation and predict the risks of vascular pathologies.

In this study, we conducted a comparative analysis of the responses to hypoxia of microcirculation (MCR) parameters of the temporal areas of the head in male and female subjects. The study was conducted in 20 healthy volunteers aged 18–19 (10 male and 10 female). The state of short-term hypoxia was induced using a ReOxy Cardio normobaric device (S.A. Aimediq, Luxembourg). Synchronous measurements of MCR parameters of symmetrical temporal regions of the head in the basal state and immediately after short-term hypoxic exposure were carried out by laser Doppler flowmetry. Statistical characteristics of perfusion of both sides of the measurement and correlation characteristics of the relationships between changes in the MCR parameters of the symmetric sides of the observation were evaluated. The results show sex differences in reactions to hypoxic effects. In 80% of men, hypoxia led to an increase in left perfusion; in 20%, to a decrease. In women, the opposite pattern was observed: in 10%, perfusion on the left increased, and in 90%, it decreased. The results of the research revealed the features of left–right asymmetry in the regulation of MCR parameters of the temporal regions of the heads of males and females. The physiological mechanisms underlying the differences in the regulation of MCR parameters of the symmetrical regions of the male and female brain require further study.

Purpose. To study the effect of short-term hypoxic exposure on correlation between microcirculatory parameters (MCR) of symmetric areas of the human head. Materials and methods. MCR parameters of 10 healthy male volunteer were measured by laser Doppler flowmetry method. Short-term hypoxic exposure was produced according to the hypoxic test method using the ReOxy Cardio unit (S. A. Aimediq). We assessed the perfusion metrics left and right areas of interest, neurogenic, myogenic, respiratory and cardiac contributors to vascular tone and correlations between baseline parameters and after hypoxic exposure. Results. We revealed the specificity of regional circulation system rearranging induced by hypoxic load. The specificity is caused by functional asymmetry of correlations between different vascular tone contributors in symmetrical head areas. Strong correlation declining under the hypoxic loads between baseline perfusion on left/right was found. The perfusion changes of symmetrical temporal areas under the hypoxic loads correlate negatively with the baseline perfusion of both the same and the opposite side. Conclusion. Short-term hypoxic load rearranges the balance of different vascular tone contributors regulatory role in MCR of symmetric head areas to maintain the sustainable activity of the whole MRC.

— A new computational and experimental method for assessing the stability of oscillatory processes occurring in the microcirculation (MCR) system is proposed. The technique is based on the analysis of the stability of a differential equations system describing fluctuations in the MCR parameters of blood in symmetrical temporal head regions of humans. Using this technique, we have investigated the change in the stability of MCR parameters of the symmetrical temporal head regions under hypoxic conditions. The study has involved 10 healthy male volunteers (18–19 years). The state of short-term hypoxia has been induced using a normobaric ReOxy Cardio device (S.A. Aimediq, Luxembourg) certified in the Russian Federation for obtaining hypoxic and hyperoxic gas mixtures based on biofeedback with a built-in pulse oximetric sensor (Masimo Rad-5, United States). Synchronous measurements of MCR parameters of symmetrical temporal head regions at the basal state and immediately after short-term hypoxic exposure have been carried out by the method of laser Doppler flowmetry (LDF) using a two-channel LAKK–02 device (LAZMA Research and Development enterprise, Russia). It has been shown that short-term hypoxic effects change the numerical values of the stability parameters in all subjects within the boundaries of stability levels. However, the response to hypoxic exposure has been very individual in different subjects. The proposed method allows for personalized assessments of the fitness level and resistance to hypoxic influences in different subject groups.

We studied sex-related features of the microcirculation response of symmetrical areas of the human head to hypoxic loads. In 20 healthy volunteers (10 male and 10 female), short-term hypoxia was modeled using the ReOxy Cardio device (S. A. Aimediq). Microcirculation parameters were synchronously measured by laser Doppler flowmetry in the initial state and immediately after short-term hypoxic exposure. 3D graphs were constructed and regression equations were formulated that describe the relationships between changes in microcirculation on both sides of the measurement. Using a new method of geometric zoning, it was shown that the direction of reactions to hypoxia of the left microcirculatory bed is opposite in subjects of different sexes. In 80% male subjects, hypoxia led to an increase in perfusion on the left, in 20% - to a decrease. In female subjects, the picture was opposite: perfusion decreased in 90% and increased in 10% subjects. It can be assumed that these differences in the reactions of microcirculation to hypoxia in men and women are an additional confirmation of different structural and functional organization of the male and female brain, which leads to different resistance of males and females to external disturbing influences. The results of the study can be used in medical practice to develop methods for personalized assessments of circulatory disorders and differentiated approaches to the treatment of men and women with cardiovascular diseases.

A new computational and experimental method for estimating the stability of oscillatory processes in the regional circulatory system, based on the analysis of fluctuations in blood microcirculation indices in symmetrical regions of the human upper limbs, was proposed. Synchronous measurements of microcirculation indices of symmetrical regions of the upper limbs were carried out in five healthy volunteers using laser Doppler flowmetry. The sensors were fixed on the outer surface of symmetrical areas of the lower parts of the right and left shoulders at points located 3 cm above the elbow bend. Regression equations describing the relationship between synchronous changes in the microcirculation parameters of symmetrical regions of the upper limbs and their initial values of left and right sides of measurement are presented. It was established that changes in the amplitudes of microcirculation fluctuations in the symmetrical region of the upper limbs depend on the initial values of these indices not only on the same side, but also on the opposite side of observation. It was demonstrated that changes in the microcirculation indices correlate negatively with instantaneous perfusion values on the same side of the measurement and positively with instantaneous perfusion values of the opposite side of the measurement. The ranges of numerical values of the model parameters, under which there are stable modes of functioning of the regional circulatory system, were calculated. These results can be used in medical practice, since the model allows estimation of the state of the regional circulatory system in patients, and prediction of the probabilities of the transition of this system into pathological modes and critical states.

Изучена нелинейная динамика флуктуаций микрокровотока симметричных областей верхних конечностей человека в исходном и возмущенном состоянии. Возмущением являлись физические нагрузки, которые представляли собой махи левой или правой рукой в положении стоя в течение 1 мин. Измерения показателей микроциркуляции были проведены у пяти здоровых добровольцев методом лазерной допплеровской флоуметрии. Флоуметрические датчики фиксировали на наружной поверхности симметричных областей нижних частей правого и левого плеча в точках, расположенных на 3 см выше локтевого сгиба. Оценивали: показатель Херста, размерность Хаусдорфа, геометрические характеристики фазовых портретов, а также статистические показатели перфузии. Было показано, что возмущающие воздействия приводят к изменениям параметров нелинейной динамики микроциркуляции верхних конечностей, которые характеризуются повышением уровня персистентности той стороны, на которой совершались возмущающие воздействия, повышением фрактальной размерности хаоса при левых возмущениях, а также инверсной динамикой лево-правосторонней асимметрии аттракторов.

This is the first study on synchronous changes in microcirculation in the symmetrical organs of humans during asymmetric physical loads of the upper limbs. The study was conducted in healthy volunteers by the method of laser Doppler flowmetry (LDF). LDF signal transducers were fixed symmetrically on the lower parts of the right and left shoulders (3 cm above the elbow bend). Physical loads included the left or right arm swings in standing position for 1 min. Measurements were made in three states: (1) initial state, (2) immediately after physical activity, and (3) 5 min after loads. The changes in the mean perfusion value and the components of amplitude-frequency spectrum of blood flow fluctuations (myogenic, neurogenic, respiratory, and cardiac) were evaluated in both sides of the body. We observed the asymmetry of changes in microcirculation parameters after physical loads. It is shown that both left and right swings change the microcirculation parameters of both the left and right sides, and the changes on the left are more pronounced than on the right. A nonlinear relationship was observed between the changes in microcirculation parameters of symmetrical areas of paired organs and heart rate. Our data illustrate the specific regulation patterns of microcirculation blood flow in paired organs, which is associated with functional asymmetry. The physiological mechanisms of this asymmetry require further experimental and clinical research.

This study explored the nonlinear dynamics of the variability of microcirculatory blood flow signals in symmetrical areas of human upper limbs in the resting state and during perturbation. The perturbation was physical activity, that is, swinging of left or right arm in an upright position for 1 min. Laser Doppler flowmetry was used to measure the microflow in five healthy volunteers. Signal sensors were fixed symmetrically on the lower parts of the right and left shoulders (3 cm above the elbow bend). The Hurst index, the Hausdorf dimension, the geometric properties of the phase portraits, and the statistical characteristics of perfusion were estimated. Overall, the results indicate that perturbation effects lead to changes in the parameters of nonlinear dynamics of microcirculation in the upper limbs, which are characterized by an increased level of persistence of the arm side that experienced a perturbation, by an increased fractal dimension of chaos in the left arm when perturbations occurred, as well as the inverse dynamics of the left–right asymmetry of the attractors.

The reactions of microcirculation parameters of symmetrical areas of the human head to hypoxic loads were studied. The study was conducted in 10 healthy male volunteers aged 18-19 years. Short-term hypoxia was modeled using a ReOxy Cardio normobaric device (S. A. Aimediq). Synchronous measurements of microcirculation parameters in symmetrical temporal regions of the head at the basal state and immediately after short-term hypoxic exposure were carried out by the method of laser Doppler flowmetry. We evaluated statistical characteristics of perfusion of both sides, as well as regression characteristics of the relationship between changes in the microcirculation parameters and the initial values of these parameters. It was shown that the reaction of the microcirculation parameters in symmetrical regions of the head to hypoxia depends on the initial microcirculation parameters in ipsi- and contralateral sides. 3D graphs were constructed and regression equations describing these relationships were formulated. A new method of geometric sensing is proposed, which allows predicting the direction of reactions to hypoxic effects. The obtained data illustrate the specificity of regulation of microcirculation of paired organs determined by the presence of functional asymmetry. A new method of geometric zoning is proposed, which allows solving the problems of personalized assessments of the state of the microcirculation system in patients.

The first mathematical model of regulation of parameters of microcirculation in vessels of symmetrical areas of paired human organs is formulated. The model is based on experimental and computational studies of synchronous changes in the parameters of microcirculation of vessels of symmetrical organs in humans under asymmetric physical loads on the upper limbs. Measurements were carried out on healthy volunteers by laser Doppler flowmetry (LDF). LDF signal sensors were installed on symmetrical sides of the lower parts of the right and left arms at points located 3 cm above the elbow bend. Physical activity was left- or right-hand swings in a standing position for 1 min. Synchronous measurements of the average perfusion values on the left and right and their changes under the influence of physical activity were performed in the daytime every 3 h for five days. Further, the dependence of changes in microcirculation parameters on their initial values was studied by the method of multiple regression analysis. The obtained regression model was the basis of a mathematical model formulated in the form of a system of linear differential equations. The equations describing oscillatory processes of microcirculation in symmetric regions of paired organs are derived. The conditions for the ranges of numerical values of the model parameters under which there are stable modes of functioning of the microcirculation system of symmetric regions of paired human organs are formulated.