scholarly journals Interrelation of cognitive functions and neural networks with blood flow velocity through the internal jugular vein in patients with chronic cerebral ischemia

2021 ◽  
Vol 40 (4) ◽  
pp. 107-112
Author(s):  
Vitaly F. Fokin ◽  
Roman B. Medvedev ◽  
Natalia V. Ponomareva ◽  
Rodion N. Konovalov ◽  
Olga V. Lagoda ◽  
...  
Keyword(s):  
Neural Networks ◽  
Blood Flow ◽  
Cerebral Ischemia ◽  
Flow Rate ◽  
Verbal Memory ◽  
Blood Flow Rate ◽  
Chronic Cerebral Ischemia ◽  
Venous Outflow ◽  
Jugular Veins ◽  
Internal Jugular Veins

Understanding age-related and functional changes in cerebral venous circulation is critical for the development of new preventive, diagnostic and therapeutic approaches to maintaining brain health in the elderly. Chronic cerebral ischemia is one of the widespread socially significant vascular diseases caused by a decrease in the level of blood circulation. To assess the role of venous outflow through the internal jugular veins in cognitive decline and neural networks in patients with chronic cerebral ischemia, 30 men and 40 women (average age 66.5 years), cognitive functions and organization of neural networks were studied at high and low levels of cerebral venous blood flow through the internal jugular veins. To assess the venous outflow, the systolic blood flow rate was measured by the internal jugular veins. A higher rate of venous outflow through internal jugular veins is associated with a more successful performance of the Luria test for verbal memory. A higher or lower blood flow rate affects the formation of neural networks of the brain. At a higher blood flow rate, the predominant areas of the resting neural networks (the passive mode network of the brain and the salient network) are localized in the frontal regions, at a low blood flow rate, the predominant neural network (frontal-parietal) is located in the left hemisphere. The state of faster and slower venous outflow forms neural networks using different neural formations that affect verbal memory. Reorganization of neural networks in this case, apparently, is the central mechanism responsible for cognitive decline in chronic cerebral ischemia (2 figs, 1 table, bibliography: 10 refs)

The Effect of Furosemide on the Intrarenal Blood Flow Distribution in the Dog

1972 ◽  
Vol 50 (8) ◽  
pp. 774-783 ◽  
Author(s):  
Serge Carrière ◽  
Michel Desrosiers ◽  
Jacques Friborg ◽  
Michèle Gagnan Brunette
Keyword(s):  
Blood Flow ◽  
Flow Rate ◽  
Urine Volume ◽  
Flow Distribution ◽  
Blood Flow Rate ◽  
Initial Distribution ◽  
Blood Flow Distribution ◽  
Intrarenal Blood Flow ◽  
Femoral Blood ◽  
Furosemide Administration

Furosemide (40 μg/min) was perfused directly into the renal artery of dogs in whom the femoral blood pressure was reduced (80 mm Hg) by aortic clamping above the renal arteries. This maneuver, which does not influence the intrarenal blood flow distribution, produced significant decreases of the urine volume, natriuresis, Ccreat, and CPAH, and prevented the marked diuresis normally produced by furosemide. Therefore the chances that systemic physiological changes occurred, secondary to large fluid movements, were minimized. In those conditions, however, furosemide produced a significant increase of the urine output and sodium excretion in the experimental kidney whereas Ccreat and CPAH were not affected. The outer cortical blood flow rate (ml/100 g-min) was modified neither by aortic constriction (562 ± 68 versus 569 ± 83) nor by the subsequent administration of furosemide (424 ± 70). The blood flow rate of the outer medulla in these three conditions remained unchanged (147 ± 52 versus 171 ± 44 versus 159 ± 54). The initial distribution of the radioactivity in each compartment remained comparable in the three conditions. In parallel with the results from the krypton-85 disappearance curves, the autoradiograms, silicone rubber casts, and EPAH did not suggest any change in the renal blood flow distribution secondary to furosemide administration.

The Effect of Hematocrit on the Clearance of Small Molecules during Hemodialysis

1983 ◽  
Vol 6 (3) ◽  
pp. 127-130 ◽  
Author(s):  
C. Woffindin ◽  
N.A. Hoenich ◽  
D.N.S. Kerr
Keyword(s):  
Blood Flow ◽  
Regression Analysis ◽  
Small Molecules ◽  
Flat Plate ◽  
Flow Rate ◽  
Distribution Curve ◽  
Blood Flow Rate ◽  
Hollow Fibre ◽  
Urea Clearance ◽  
Flow Rates

Data collected during the evaluation of a series of hemodialysers were analysed to see the effect of hematocrit on the clearance of urea and creatinine. All evaluations were performed on patients with a range of hematocrits with a mean close to 20%. The urea clearance of those in the upper half of the distribution curve (mean hematocrit 29.4%) was not significantly different from that of patients in the lower half of the distribution curve (mean hematocrit 16.9%) whether the clearance was studied at high or low blood flow rates and with hollow fibre or flat plate disposable hemodialysers. Likewise, there was no correlation between hematocrit and urea clearance by regression analysis. In contrast, the clearance of creatinine was affected by hematocrit being greater at lower hematocrit values. This difference was independent of blood flow rate and dialyser type and was confirmed by regression analysis.

Anoxia and adenosine induce increased cerebral blood flow rate in crucian carp

1994 ◽  
Vol 267 (2) ◽  
pp. R590-R595 ◽  
Author(s):  
G. E. Nilsson ◽  
P. Hylland ◽  
C. O. Lofman
Keyword(s):  
Blood Flow ◽  
Flow Rate ◽  
Crucian Carp ◽  
Blood Flow Rate ◽  
Fold Increase ◽  
Liver Glycogen ◽  
Glycolytic Flux ◽  
Brain Blood Flow ◽  
Atp Production ◽  
The Brain

The crucian carp (Carassius carassius) has the rare ability to survive prolonged anoxia, indicating an extraordinary capacity for glycolytic ATP production, especially in a highly energy-consuming organ like the brain. For the brain to be able to increase its glycolytic flux during anoxia and profit from the large liver glycogen store, an increased glucose delivery from the blood would be expected. Nevertheless, the effect of anoxia on brain blood flow in crucian carp has never been studied previously. We have used epireflection microscopy to directly observe and measure blood flow rate on the brain surface (optic lobes) during normoxia and anoxia in crucian carp. We have also examined the possibility that adenosine participates in the regulation of brain blood flow rate in crucian carp. The results showed a 2.16-fold increase in brain blood flow rate during anoxia. A similar increase was seen after topical application of adenosine during normoxia, while adenosine was without effect during anoxia. Moreover, superfusing the brain with the adenosine receptor blocker aminophylline inhibited the effect of anoxia on brain blood flow rate, clearly suggesting a mediatory role of adenosine in the anoxia-induced increase in brain blood flow rate.

scholarly journals Patient-specific computational haemodynamics associated with surgical creation of an arteriovenous fistula

2021 ◽  
Author(s):  
George Hyde-Linaker ◽  
Pauline Hall Barrientos ◽  
Sokratis Stoumpos ◽  
Asimina Kazakidi
Keyword(s):  
Blood Flow ◽  
Flow Rate ◽  
Disease Patient ◽  
Blood Flow Rate ◽  
Fold Increase ◽  
Transitional Flow ◽  
Patient Specific ◽  
Venous Anastomosis ◽  
End Stage

Abstract Despite arteriovenous fistulae (AVF) being the preferred vascular access for haemodialysis, high primary failure rates (30-70%) and low one-year patency rates (40-70%) hamper their use. The haemodynamics within the vessels of the fistula change significantly following surgical creation of the anastomosis and can be a surrogate of AVF success or failure. Computational fluid dynamics (CFD) can crucially predict AVF outcomes through robust analysis of a fistula’s haemodynamic patterns, which is impractical in-vivo. We present a proof-of-concept CFD framework for characterising the AVF blood flow prior and following surgical creation of a successful left radiocephalic AVF in a 20-year-old end-stage kidney disease patient. The reconstructed vasculature was generated utilising multiple contrast-enhanced magnetic resonance imaging (MRI) datasets. Large eddy simulations were conducted for establishing the extent of arterial and venous remodelling. Following anastomosis creation, a significant 2-3-fold increase in blood flow rate was induced downstream of the left subclavian artery. This was validated through comparison with post-AVF patient-specific phase-contrast data. The increased flow rate yielded an increase in time-averaged wall shear stress (TAWSS), a key marker of adaptive vascular remodelling. We have demonstrated TAWSS and oscillatory shear distributions of the transitional-flow in the venous anastomosis are predictive of AVF remodelling.

scholarly journals In vivo / in vitro Correlation of Pharmacokinetics of Gentamicin, Vancomycin, Teicoplanin and Doripenem in a Bovine Blood Hemodialysis Model

2021 ◽  
Vol 12 ◽  
Author(s):  
M G Vossen ◽  
S Pferschy ◽  
C Milacek ◽  
M Haidinger ◽  
Mario Karolyi ◽  
...  
Keyword(s):  
Blood Flow ◽  
Renal Replacement Therapy ◽  
Protein Binding ◽  
Replacement Therapy ◽  
Flow Rate ◽  
Blood Flow Rate ◽  
Bovine Blood ◽  
Flow Rates ◽  
Dialysate Flow Rate

Background: Elimination of a drug during renal replacement therapy is not only dependent on flow rates, molecular size and protein binding, but is often influenced by difficult to predict drug membrane interactions. In vitro models allow for extensive profiling of drug clearance using a wide array of hemofilters and flow rates. We present a bovine blood based in vitro pharmacokinetic model for intermittent renal replacement therapy.Methods: Four different drugs were analyzed: gentamicin, doripenem, vancomicin and teicoplanin. The investigated drug was added to a bovine blood reservoir connected to a hemodialysis circuit. In total seven hemofilter models were analyzed using commonly employed flow rates. Pre-filter, post-filter and dialysate samples were drawn, plasmaseparated and analyzed using turbidimetric assays or HPLC. Protein binding of doripenem and vancomycin was measured in bovine plasma and compared to previously published values for human plasma.Results: Clearance values were heavily impacted by choice of membrane material and surface as well as by dialysis parameters such as blood flow rate. Gentamicin clearance ranged from a minimum of 90.12 ml/min in a Baxter CAHP-170 diacetate hemofilter up to a maximum of 187.90 ml/min in a Fresenius medical company Fx80 polysulfone model (blood flow rate 400 ml/min, dialysate flow rate 800 ml/min). Clearance of Gentamicin vs Vancomicin over the F80s hemofilter model using the same flow rates was 137.62 mL vs 103.25 ml/min. Doripenem clearance with the Fx80 was 141.25 ml/min.Conclusion: Clearance values corresponded very well to previously published data from clinical pharmacokinetic trials. In conjunction with in silico pharmacometric models. This model will allow precise dosing recommendations without the need of large scale clinical trials.

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