Measurement Of Blood Flow Rate Research Articles

Quantification of whole-organ individual and bilateral renal metabolic rate of oxygen.

Renal metabolic rate of oxygen (rMRO2 ) is a potentially important biomarker of kidney function. The key parameters for rMRO2 quantification include blood flow rate (BFR) and venous oxygen saturation (SvO2 ) in a draining vessel. Previous approaches to quantify renal metabolism have focused on the single organ. Here, both kidneys are considered as one unit to quantify bilateral rMRO2 . A pulse sequence to facilitate bilateral rMRO2 quantification is introduced. To quantify bilateral rMRO2 , measurements of BFR and SvO2 are made along the inferior vena cava (IVC) at suprarenal and infrarenal locations. From the continuity equation, these four parameters can be related to derive an expression for bilateral rMRO2 . The recently reported K-MOTIVE pulse sequence was implemented at four locations: left kidney, right kidney, suprarenal IVC, and infrarenal IVC. A dual-band variant of K-MOTIVE (db-K-MOTIVE) was developed by incorporating simultaneous-multi-slice imaging principles. The sequence simultaneously measures BFR and SvO2 at suprarenal and infrarenal locations in a single pass of 21 s, yielding bilateral rMRO2 . SvO2 and BFR are higher in suprarenal versus infrarenal IVC, and the renal veins are highly oxygenated (SvO2 >90%). Bilateral rMRO2 quantified in 10 healthy subjects (8 M, 30 ± 8 y) was found to be 291 ± 247 and 349 ± 300 (μmolO2 /min)/100 g, derived from K-MOTIVE and db-K-MOTIVE, respectively. In comparison, total rMRO2 from combining left and right was 329 ± 273 (μmolO2 /min)/100 g. The present work demonstrates that bilateral rMRO2 quantification is feasible with fair reproducibility and physiological plausibility. The indirect method is a promising approach to compute bilateral rMRO2 when individual rMRO2 quantification is difficult.

Efficacy of Dynamics-based Features for Machine Learning Classification of Renal Hemodynamics.

Different machine learning approaches for analyzing renal hemodynamics using time series of arterial blood pressure and renal blood flow rate measurements in conscious rats are developed and compared. Particular emphasis is placed on features used for machine learning. The test scenario involves binary classification of Sprague-Dawley rats obtained from two different suppliers, with the suppliers' rat colonies having drifted slightly apart in hemodynamic characteristics. Models used for the classification include deep neural network (DNN), random forest, support vector machine, multilayer perceptron. While the DNN uses raw pressure/flow measurements as features, the latter three use a feature vector of parameters of a nonlinear dynamic system fitted to the pressure/flow data, thereby restricting the classification basis to the hemodynamics. Although the performance in these cases is slightly reduced in comparison to that of the DNN, they still show promise for machine learning (ML) application. The pioneering contribution of this work is the establishment that even with features limited to hemodynamics-based information, the ML models can successfully achieve classification with reasonably high accuracy.

Measurement of blood flow rate by ultrasonic sensor system

Measurement of blood flow rate by ultrasonic sensor system

Эффективность озонотерапии и ультразвука при регенерации инфицированной раны в эксперименте

The aim of the study. To study the regeneration processes in infected wounds against the background of long-standing diabetes mellitus with topical ozone therapy and ultrasound. Material and methods. The experimental study included 35 animals (rats of the Wistar population). Among them, a total of 30 had long-standing diabetes mellitus and 5 were healthy rats modelled with an infected wound. The animals were divided into groups depending on the chosen treatment method. The first group was comprised of 10 rats treated with daily topical ozone therapy and low-frequency ultrasound. The rats from the second group only received topical ozone therapy and the wound was treated with “Autry 6000”. The rats of the third group received standard daily treatment with 1% dioxidin solution. In group IV rats (n=5) without DM, the simulated infected wound was treated daily with 1% dioxidin solution. Evaluation of treatment effectiveness was performed based on the results of wound planimetry, measurement of blood flow rate at the border between healthy tissue and the wound as well as histological examination data. Results. Based on the research conducted, the effectiveness of combined treatment using topical ozone therapy and low-frequency ultrasound has been proved. This method of treatment normalises blood flow rate at the border between healthy tissue and the infected wound, reduces wound healing time and accelerates the processes of wound cleansing from purulent exudate, filling of the wound with granulation tissue as well as formation of marginal epithelisation. Conclusion. In connection with the same pathogenetic pattern of the infected wound in both rats with long-standing diabetes mellitus and that in a diabetes mellitus patient, it is advisable to use the new topical wound treatment methods including ozone therapy and ultrasound.

Quantitative Monitoring of Dynamic Blood Flows Using Coflowing Laminar Streams in a Sensorless Approach

Determination of blood viscosity requires consistent measurement of blood flow rates, which leads to measurement errors and presents several issues when there are continuous changes in hematocrit changes. Instead of blood viscosity, a coflowing channel as a pressure sensor is adopted to quantify the dynamic flow of blood. Information on blood (i.e., hematocrit, flow rate, and viscosity) is not provided in advance. Using a discrete circuit model for the coflowing streams, the analytical expressions for four properties (i.e., pressure, shear stress, and two types of work) are then derived to quantify the flow of the test fluid. The analytical expressions are validated through numerical simulations. To demonstrate the method, the four properties are obtained using the present method by varying the flow patterns (i.e., constant flow rate or sinusoidal flow rate) as well as test fluids (i.e., glycerin solutions and blood). Thereafter, the present method is applied to quantify the dynamic flows of RBC aggregation-enhanced blood with a peristaltic pump, where any information regarding the blood is not specific. The experimental results indicate that the present method can quantify dynamic blood flow consistently, where hematocrit changes continuously over time.

High-dynamic-range blood flow rate measurement in a large-diameter vessel.

We propose a new, to the best of our knowledge, compound technique to measure high-dynamic-range blood flow rate in a large-diameter vessel, which combines the dynamic scattering light (DLS) and the laser speckle contrast imaging (LSCI) methods, possessing the advantages of the high temporal resolution of DLS and the robust property of LSCI. By controlling the second-order spatial correlations of the laser speckle through two imaging systems, the speckle temporal intensity autocorrelation function g2(t) and the decorrelation time τc are directly measured using a high-speed camera. It turns out the enhanced spatial second-order correlation helps to measure the blood flow with higher dynamic range and that the measured parameter β and the blood flow dynamics n were accurately determined. For further improvement the dynamic range, the modified LSCI method was adopted, and the decorrelation time as a function of blood flow rate was constructed. It reveals the feasibility of measuring the high flow rate in large-diameter vessels and provides significant guidance for the future biomedical study of the myocardial perfusion in coronary artery bypass grafting, ghost imaging, and ghost cytometry.

Blood Flow Velocity Pulsatility and Arterial Diameter Pulsatility Measurements of the Intracranial Arteries Using 4D PC-MRI

4D phase contrast magnetic resonance imaging (PC-MRI) allows for the visualization and quantification of the cerebral blood flow. A drawback of software that is used to quantify the cerebral blood flow is that it oftentimes assumes a static arterial luminal area over the cardiac cycle. Quantifying the lumen area pulsatility index (aPI), i.e. the change in lumen area due to an increase in distending pressure over the cardiac cycle, can provide insight in the stiffness of the arteries. Arterial stiffness has received increased attention as a predictor in the development of cerebrovascular disease. In this study, we introduce software that allows for measurement of the aPI as well as the blood flow velocity pulsatility index (vPI) from 4D PC-MRI. The internal carotid arteries of seven volunteers were imaged using 7 T MRI. The aPI and vPI measurements from 4D PC-MRI were validated against measurements from 2D PC-MRI at two levels of the internal carotid arteries (C3 and C7). The aPI and vPI computed from 4D PC-MRI were comparable to those measured from 2D PC-MRI (aPI: mean difference: 0.03 (limits of agreement: −0.14 – 0.23); vPI: 0.03 (−0.17–0.23)). The measured blood flow rate for the C3 and C7 segments was similar, indicating that our proposed software correctly captures the variation in arterial lumen area and blood flow velocity that exists along the distal end of the carotid artery. Our software may potentially aid in identifying changes in arterial stiffness of the intracranial arteries caused by pathological changes to the vessel wall.

Intrauterine growth restriction alters nutrient metabolism in the intestine of porcine offspring

BackgroundIntrauterine growth restriction (IUGR) has negative impacts on the postnatal survival, growth and development of humans and animals, with not only on newborns but also adulthood. However, the characteristics for nutrient digestion and absorption in IUGR offspring are still largely unknown. Therefore, the normal birth weight (NBW) and IUGR growing pigs were used in this study to investigate their differences in nutrient utilization, with an expectition for further nutritional optimization of the IUGR offspring during their later life.MethodsTwelve IUGR and 12 NBW growing pigs were fitted with catheters in their portal vein to measure blood flow rate as well as nutrients and metabolites in plasma. The digestibilities of nutrients in different intestinal segments, and bacterial fermentation in the large intestine were examined to reveal the characteristics of nutrients utilization in IUGR versus NBW pigs.ResultsThe rate of portal venous blood flow did not differ beween IUGR and NBW pigs. Plasma concentrations of total cholesterol, triglycerides and glucose were much lower but those of urea were higher in the portal vein of IUGR pigs, compared with the NBW pigs. The ileal digestibility of dry matter, gross energy and starch were lower in IUGR pigs than in NBW pigs. IUGR increased hindgut microbial diversity and bacterial fermentation activity in the caecum. In vitro cross-fermentation of ileal digesta by caecal microbes of NBW and IUGR pigs showed that gas production was much higher for IUGR ileal digesta regardless of the source of caecal inocula.ConclusionIUGR impairs the nutrient digestion and absorption in small intestine, reduces caecal microbial diversity and promotes bacterial fermentation in the large intestine during the growing phase. These findings aid in our understanding of nutrient metabolism in IUGR pigs and provide the basis for future nutritional interventions.

Autoregulatory Efficiency Assessment in Kidneys Using Deep Learning.

A convolutional deep neural network is employed to assess renal autoregulation using time series of arterial blood pressure and blood flow rate measurements in conscious rats. The network is trained using representative data samples from rats with intact autoregulation and rats whose autoregulation is impaired by the calcium channel blocker amlodipine. Network performance is evaluated using test data of the types used for training, but also with data from other models for autoregulatory impairment, including different calcium channel blockers and also renal mass reduction. The network is shown to provide effective classification for impairments from calcium channel blockers. However, the assessment of autoregulation when impaired by renal mass reduction was not as clear, evidencing a different signature in the hemodynamic data for that impairment model. When calcium channel blockers were given to those animals, however, the classification again was effective.

Numerical simulation of blood nanofluid flow over three different geometries by means of gyrotactic microorganisms: Applications to the flow in a circulatory system

Biomedical engineers, medical scientists, and clinicians are expressing a notable interest in the measurement of blood flow rate because it is used to detect cardiovascular diseases such as atherosclerosis and arrhythmia. Several researchers have adopted various non-Newtonian fluid models to investigate blood flow in the circulatory system. Because many non-Newtonian fluid models like Herschel Buckley, Powell-Eyring fluid, tangent hyperbolic fluid, and Williamson fluid exhibit the characteristics of blood. The tangent hyperbolic fluid model expresses the rheological characteristics of blood more accurately due to its shear-thinner properties. This work is performed to express the significance of the induced magnetic field and gyrotactic microorganisms on the flow of tangent hyperbolic nanofluid over a plate, wedge and stagnation point of the plate. Suitable self-similarity variables are employed to convert the fluid transport equations into ordinary differential equations which have been solved with the use of the Runge-Kutta-Fehlberg (RKF) approach. The impacts of active parameters on transport properties of the fluid are illustrated with graphs and tables. The growing magnetic parameter lessens the blood nanofluid velocity over three geometries. Blood nanofluid has a higher heat transfer rate over a stagnation point compared with other two geometries. Blood nanofluid temperature augments for uplifting the thermophoresis parameter. Peclet number shows a high impact on microorganisms density in a blood nanofluid. This exploration can provide a clear view regarding the heat and mass transfer behavior of blood flow in a circulatory system and various hyperthermia treatments like treatment of cancer.

The Relationship between the Blood Flow Volume of the Arteriovenous Fistula and its Early Effect on the Pulmonary Artery Pressure and the Left Ventricular Dimensions and Functions

Abstract Background Cardiovascular complications are leading cause of the death in hemodialysis patients. One of these complications is pulmonary hypertension which complicates chronic renal failure in 12–45% of cases and causes an increase in all-cause mortality of 2-3 folds in the dialysis population. Another complication is left ventricular hypertrophy which is a strong predictor of morbidity and mortality in patients with ESRD. Arteriovenous fistulas increase cardiac output and lead to significant increases in both the mass and the diameter of the left ventricular wall in the long-term duration. There is evidence that A-V fistula creation is a major risk factor for developing a new onset Congestive Heart Failure Aim of the Work Our study aimed to assess the relationship between blood flow volume of arteriovenous fistula (AVF) and its effect on the Pulmonary Artery Pressure (PAP) and the Left Ventricular (LV) dimensions and functions and to find out the cut off value of the AVF blood flow volume above which the cardiac dimensions and functions start to get affected. Methods and Results The study included 50 individuals selected from Internal Medicine and Nephrology outpatient clinics and inpatient wards at Ain Shams University Hospitals during the period from November 2016 until October 2018 who underwent full echocardiography studies once at the beginning of the study and once after 3 months and also underwent Duplex sonography on arteriovenous fistula to measure blood flow rate. The results showed that after 3 months the only significant changes were the ejection fraction (P-value of 0.029), the fractional shortening (P-value of 0.009), and the E/A ratio (p-value of 0.005). Also, the results showed a correlation between AVF blood flow volume and LV internal dimensions. Left ventricular end-diastolic diameter (LVEDD) and Left ventricular end-systolic diameter (LVESD) increased significantly in patients with AVF blood flow volume of 1010 ml/min or above and 1120 ml/min or above respectively. Surprisingly, PASP showed no statistically significant change in our study. Conclusion Our study concluded that high flow AVF affect cardiac dimensions and functions. We proved that a cut off value of AVF blood flow volume affecting LV dimensions and functions can be reached and in our study, a value of 1010 ml/min or above affected the LVEDD and a value of 1120 ml/min or above affected the LVESD. Surprisingly, in our study, the PASP did not show a positive correlation with AVF blood flow volume.

Integrating Patient-Specific Electrocardiogram Signals and Image-Based Computational Fluid Dynamics Method to Analyze Coronary Blood Flow in Patients during Cardiac Arrhythmias

PurposeThe aim of this study was to use the computational fluid dynamics (CFD) method, patient-specific electrocardiogram (ECG) signals, and computed tomography three-dimensional image reconstruction technique to investigate the blood flow in coronary arteries during cardiac arrhythmia.MethodsTwo patients with premature ventricular contraction-type cardiac arrhythmia and one with atrial fibrillation-type cardiac arrhythmia were investigated. The inlet velocity of the coronary artery in simulation was applied with the measured velocity profile of the left ventricular outflow tract (LVOT) from the Doppler echocardiography. The measured patient central aortic blood pressure waveform was employed for the coronary artery outlet in simulation. The no-slip boundary condition was applied to the arterial wall.ResultsFor the patient with irregular cardiac rhythms (Case I), the coronary blood flow rate under the shortened and lengthened cardiac rhythms were 0.66 and 0.96 mL/s, respectively. In Case II, the maximum velocity at the LVOT under a normal heartbeat was found to be 101 cm/s, whereas the average value was 73 cm/s. In Case III, the patient was also diagnosed with a congenital stenosis problem at the myocardial bridge (MCB) at the LAD. The measured blood flow rate at the MCB of the LAD for the three heartbeats in Case III was found to be 0.68, 1.08, and 1.14 mL/s.ConclusionThe integration of patient-specific ECG signals and image-based CFD methods can clearly analyze hemodynamic information for patients during cardiac arrhythmia. The cardiac arrhythmia can reduce the blood flow in the coronary arteries.

Thermal radiation and Hall effects on peristaltic blood flow with double diffusion in the presence of nanoparticles

The aim of the present research work deals with the thermal radiation and hall effects on peristaltic blood flow with double diffusive convection of gold nanoparticles through an asymmetric channel under the long wavelength and low Reynolds number assumptions. Effect of thermal radiation and double diffusion is an important aspect of research due to its application in public health potential and hall effect can be used to measure blood flow rate because the blood contains ions that constitute an electric current. Theory of peristaltic motion, the heat flux of the linear approximation and the thermal radiation are employing on the flow problems. This approximation is possible only where the temperature difference is small in the fluid flow. The mathematical modelling of the present problem includes the partial differential equations and the basic governing equations which are solved by analytical approximation method known as Homotopy Analysis Method (HAM). Solutions are obtained for velocity, temperature, solutal (species) concentration and nanoparticle volume fraction profiles. Results for velocity profile, temperature profile, pressure rise, solutal (species) concentration profile and nanoparticle volume fraction profile for different physical parameters are discussed through graphs.

Hematocrit-insensitive Absolute Blood Flow Rate Measurement in 0.5-mm-diameter Flow Channel Using MEMS-based Laser Doppler Velocimeter with Signal Modification for Detecting Beat Frequency from Broad Power Spectrum

Hematocrit-insensitive Absolute Blood Flow Rate Measurement in 0.5-mm-diameter Flow Channel Using MEMS-based Laser Doppler Velocimeter with Signal Modification for Detecting Beat Frequency from Broad Power Spectrum

4D flow MRI—Automatic assessment of blood flow in cerebral arteries

Objective: With a 10-minute 4D flow MRI scan, the distribution of blood flow to individual arteries throughout the brain can be analyzed. This technique has potential to become a biomarker for treatment decisions, and to predict prognosis after stroke. To efficiently analyze and model the large dataset in clinical practice, automatization is needed. We hypothesized that identification of selected arterial regions using an atlas with a priori probability information on their spatial distribution can provide standardized measurements of blood flow in the main cerebral arteries. Approach: A new method for automatic placement of measurement locations in 4D flow MRI was developed based on an existing atlas-based method for arterial labeling, by defining specific regions of interest within the corresponding arterial atlas. The suggested method was evaluated on 38 subjects with carotid artery stenosis, by comparing measurements of blood flow rate at automatically selected locations to reference measurements at manually selected locations. Main results: Automatic and reference measurement ranged from 10 to 580 ml min−1 and were highly correlated (r = 0.99) with a mean flow difference of 0.61 ± 10.7 ml min−1 (p = 0.21). Out of the 559 arterial segments in the manual reference, 489 were correctly labeled, yielding a sensitivity of 88%, a specificity of 85%, and a labeling accuracy of 87%. Significance: This study confirms that atlas-based labeling of 4D flow MRI data is suitable for efficient flow quantification in the major cerebral arteries. The suggested method improves the feasibility of analyzing cerebral 4D flow data, and fills a gap necessary for implementation in clinical use.

Torsion Does Not Affect Early Vein Graft Patency in the Rat Femoral Artery Model.

Torsion of vein grafts is a commonly cited reason for graft failure in clinical setting. Many microsurgery training courses have incorporated vein graft procedures in their curricula, and vein graft torsion is a common technical error made by the surgeons in these courses. To improve our understanding of the clinical reproducibility of practicing vein graft procedures in microsurgery training courses, this study aims to determine if torsion can lead to early vein graft failure in nonsurvival surgery rat models. Sprague-Dawley rats were divided into five cohorts with five rats per cohort for a total of 25 rats. Cohorts were labeled based on degree of vein graft torsion (0, 45, 90, 135, and 180 degrees). Torsion was created in the vein grafts at the distal arterial end by mismatching sutures placed between the proximal end of the vein graft and the distal arterial end. Vein graft patency was then verified 2 and 24 hours postoperation. All vein grafts were patent 2 and 24 hours postoperation. At 2 hours, the average blood flow rate measurements for 0, 45, 90, 135, and 180 degrees of torsion were 0.37 ± 0.02, 0.38 ± 0.04, 0.34 ± 0.01, 0.33 ± 0.01, and 0.29 ± 0.02 mL/min, respectively. At 24 hours, they were 0.94 ± 0.07, 1.03 ± 0.15, 1.26 ± 0.22, 1.41 ± 0.11, and 0.89 ± 0.15 mL/min, respectively. Torsion of up to 180 degrees does not affect early vein graft patency in rat models. To improve the clinical reproducibility of practicing vein graft procedures in rat models, we suggest that microsurgery instructors assess vein graft torsion prior to clamp release, as vessel torsion does not seem to affect graft patency once the clamps are removed.

Optogenetic interrogation of neurovascular coupling in the cerebral cortex of transgenic mice

Objective. We introduce an engineering approach to study spatiotemporal correlations between vasodynamics and the nearby neural activity in open-loop and closed-loop paradigms. Approach. We integrated optogenetic technology with optical coherence tomography to apply spatiotemporal patterns of optical neurostimulation to the cortex of transgenic optogenetic mice and measure blood flow-rate, velocity, and diameter changes of selected middle cerebral artery branches. Main results. The spatiotemporal characteristics of blood flow-rate, velocity, and vessel diameter responses to localized neurostimulation light pulses were measured. It was observed that the location of stimulation relative to the surrounding vascular topology had notable effects on temporal patterns of vasodynamic responses. This effect was studied by creating velocity, flow-rate, and diameter sensitivity maps for selected arteries. Generally, neural stimulation in the vicinity of downstream capillaries of an artery evoked a fast transient increase in the blood flow-rate, velocity, and vessel diameter which was followed by a long-lasting secondary peak-response. The temporal span of the flow-rate response was quasi-linearly proportional to the length of stimulation. When neural stimulation was delivered to the area in the vicinity of one daughter branch of an artery, in other branches, we observed some drop in blood velocity and/or flow-rate and concurring increase of the vessel diameter. To examine the reliability of the coupling between neural activity and regional blood flow, a closed-loop feedback controller was implemented which is capable of maintaining blood flow-rate at any desired level for relatively longer periods by continuously adjusting the width of stimulation pulses. Significance. The proposed approach opens new lines of research with potential applications in understanding the role of different cell types in the cerebrovascular regulatory mechanisms and the study of the adaptive process of angiogenesis in the cerebral cortex. The observation of incoherent responses of vessel diameter, blood flow-rate, and velocity suggests that such detailed information is necessary to obtain an accurate interpretation of the data acquired via hemodynamic based functional imaging techniques.

Glucose pump test can be used to measure blood flow rate of native arteriovenous fistula in chronic hemodialysis.

In chronic hemodialysis patients, the low flow of vascular access may leads to inadequate dialysis, increased rate of hospitalization, morbidity, and mortality. It was found that surveillance should be performed for native arteriovenous (AV) should not be performed for AV graft in various studies. However, surveillance was done in graft AV fistulas in most studies. Doppler ultrasonography (US) was suggested for surveillance of AV fistulas by the last vascular access guideline of National Kidney Foundation Disease Outcomes Quality Initiative (NKF KDOQI). The aim of study is to determine whether glucose pump test (GPT) is used for surveillance of native AV fistulas by using Doppler US as reference. In 93 chronic hemodialysis patients with native AV fistula, blood flow rates were measured by Doppler US and GPT. For GPT, glucose was infused to 16 mL/min by pump and was measured at basal before the infusion and 11 s after the start of the infusion by glucometer. Doppler US was done by an expert radiologist. Used statistical tests were Mann-Whitney U test, Friedman test, regression analysis, and multiple regression analysis. Median values of blood flow rates measured by GPT (707 mL/min) and by Doppler US (700 mL/min) were not different (Z = 0.414, P = 0.678). Results of GPT and Doppler US measurements were positive correlate by regression analysis. The mean GPT value of diabetic patients (n = 39; 908 mL/min) was similar to that of nondiabetic patients (n = 54; 751 mL/min; Z = 1.31, P = 0.188). GPT values measured at three different dialysis session did not differ from each other that by Friedman test (F = 0.92, P = 0.39). This showed that GPT was stable and reliable. Glucose pump test can be used to measure blood flow rate of native AV fistula. GPT is an accurate and reliable test.

Detection of microembolic signals in the common carotid artery using Doppler sonography in the porcine model of acute heart failure treated by veno-arterial extracorporeal membrane oxygenation.

Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is a method used for the treatment most severe cases of decompensated heart failure. The purpose of this study was to evaluate the risk of the formation of microembolisms during VA-ECMO-based therapy. Heart failure was induced with simultaneous detection of microembolisms and the measurement of blood flow rate in the common carotid artery (CCA) without VA-ECMO (0 l/min) and at the VA-ECMO blood flow rate of 1, 2, 3 and 4 l/min. If embolisms for VA-ECMO 0 l/min and the individual regimes for VA-ECMO 1, 2, 3, 4 l/min are compared, a higher VA-ECMO flow rate is accompanied by a higher number of microembolisms. The final microembolism value at 16 min was for the VA-ECMO flow rate of 0 l/min 0.0 (0, 1), VA-ECMO l/min 7.5 (4, 19), VA-ECMO 2 l/min 12.5 (4, 26), VA-ECMO 3 l/min, 21.0 (18, 57) and VA-ECMO 4 l/min, 27.5 (21, 64). Such a comparison is statistically significant if VA-ECMO 0 vs. 4 l/min p<0.0001, 0 vs. 3 l/min p<0.01 and 1 vs. 4 l/min p<0.01 are compared. The results confirm that high VA-ECMO flow rates pose a risk with regards to the formation of a significantly higher number of microemboli in the blood circulation and that an increase in blood flow rates in the CCA corresponds to changes in the VA-ECMO flow rates.

Effects of a compound from the group of substituted thiadiazines with hypothermia inducing properties on brain metabolism in rats, a study in vivo and in vitro.

The aim of the present study was to examine how administration of a compound of 1,3,4- thiadiazine class 2-morpholino-5-phenyl-6H-1,3,4-thiadiazine, hydrobromide (L-17) with hypothermia inducing properties affects the brain metabolism. The mechanism by which L-17 induces hypothermia is unknown; it may involve hypothalamic central thermoregulation as well as act via inhibition of energy metabolism. We tested the hypothesis that L-17 may induce hypothermia by directly inhibiting energy metabolism. The study in vivo was carried out on Sprague-Dawley adult rats. Two doses of L-17 were administered (190 mg/kg and 760 mg/kg). Brain metabolites were analyzed in control and treated groups using magnetic resonance spectroscopy, along with blood flow rate measurements in carotid arteries and body temperature measurements. Further in vitro studies on primary cultures from rat hippocampus were carried out to perform a mitochondria function test of L-17 pre-incubation (100 μM, 30 min). Analysis of brain metabolites showed no significant changes in 190 mg/kg treated group along with a significant reduction in body temperature by 1.5°C. However, administration of L-17 in higher dose 760 mg/kg provoked changes in brain metabolites indicative of neurotoxicity as well as reduction in carotid arteries flow rate. In addition, a balance change of excitatory and inhibitory neurotransmitters was observed. The L-17 pre-incubation with cell primary cultures from rat brain showed no significant changes in mitochondrial function. The results obtained in the study indicate that acute administration of L-17 190 mg/kg in rats induces mild hypothermia with no adverse effects onto brain metabolism.