Fluid Dynamics Analysis by CT Imaging Technique of New Sorbent Cartridges for Extracorporeal Therapies

2019 ◽  
Vol 48 (1) ◽  
pp. 18-24
Author(s):  
Anna Lorenzin ◽  
Mauro Neri ◽  
Massimo de Cal ◽  
Giordano Pajarin ◽  
Giuseppe Mansi Montenegro ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Blood Flow ◽  
Pressure Drop ◽  
Flow Rate ◽  
Imaging Technique ◽  
Blood Purification ◽  
Ct Imaging ◽  
Flow Profile ◽  
In Vitro Test

Background: Recent innovations in biomaterials technology have led to the development of innovative sorbents adopted as adsorbing devices in the field of extracorporeal blood purification therapies. As removal mechanism, adsorption allows to remove specific molecules, selectively binding them to sorbent materials. In addition to the material properties, a quintessential aspect influencing device properties is blood flow distribution within the sorbent particles. Objectives: In order to adequately characterize the potential adsorbing properties for an effective blood purification therapy, an in vitro study assessing the fluid dynamics inside 3 new cartridges, HA130, HA230 and HA330 (Jafron, Zhuhai City, ­China) was conducted through CT imaging technique. ­Methods: The cartridges were placed in vertical position in the CT ­gantry. Dye solution was circulated through the cartridges at 250 mL/min, longitudinal sections, 0.5 cm thick, were recorded for 60 s. Furthermore, an in vitro test was conducted to build pressure drop profiles. Blood was circulated at a different flow rate, 100–400 mL/min, step 50 mL/min. Pre and post cartridges pressures were acquired and pressure drop calculated. Results: Sequential images demonstrated an excellent distribution of the flow inside the cartridges. Average flow velocity was 0.37 cm/s for the 3 cartridges. HA130 had a homogeneous flow profile along the entire length of the device; HA230 and HA330 showed minimal differences between central and peripheral regions. Pressure drop profiles resulted linear, increasing proportionally with blood flow rate and packing density. Conclusions: We may conclude that the structural and functional design of the studied cartridges is adequate for haemoperfusion with no channelling phenomena. This ensures maximum and optimal utilization of the sorbent contained in the devices.

scholarly journals Estimation Methods for Viscosity, Flow Rate and Pressure from Pump-Motor Assembly Parameters

Sensors ◽  
2020 ◽  
Vol 20 (5) ◽  
pp. 1451
Author(s):  
Martin Elenkov ◽  
Paul Ecker ◽  
Benjamin Lukitsch ◽  
Christoph Janeczek ◽  
Michael Harasek ◽  
...  
Keyword(s):  
Blood Flow ◽  
Flow Rate ◽  
Pressure Difference ◽  
Mean Squared Error ◽  
Blood Flow Rate ◽  
Estimation Methods ◽  
In Vitro Test ◽  
Motor Speed ◽  
Term Operation

Blood pumps have found applications in heart support devices, oxygenators, and dialysis systems, among others. Often, there is no room for sensors, or the sensors are simply unreliable when long-term operation is required. However, control systems rely on those hard-to-measure parameters, such as blood flow rate and pressure difference, thus their estimation takes a central role in the development process of such medical devices. The viscosity of the blood not only influences the estimation of those parameters but is often a parameter that is of great interest to both doctors and engineers. In this work, estimation methods for blood flow rate, pressure difference, and viscosity are presented using Gaussian process regression models. Different water–glycerol mixtures were used to model blood. Data was collected from a custom-built blood pump, designed for intracorporeal oxygenators in an in vitro test circuit. The estimation was performed from motor current and motor speed measurements and its accuracy was measured for: blood flow rate r2 = 0.98, root mean squared error (RMSE) = 46 mL.min−1; pressure difference r2 = 0.98, RMSE = 8.7 mmHg; and viscosity r2 = 0.98, RMSE = 0.049 mPa.s. The results suggest that the presented methods can be used to accurately predict blood flow rate, pressure, and viscosity online.

scholarly journals Distribution of Artificial Thrombi Candidates Through Patient-Specific Aortic-Arch Phantoms under Pulsatile Flow Conditions

2021 ◽  
Author(s):  
Marco Testaguzza ◽  
Mehdi Benhassine ◽  
Haroun Frid ◽  
Laurence Gebhart ◽  
Karim Zouaoui Boudjeltia ◽  
...  
Keyword(s):  
Aortic Arch ◽  
Pulsatile Flow ◽  
Patient Specific ◽  
Flow Profile ◽  
In Vitro Test ◽  
Flow Conditions ◽  
Test Bed ◽  
Arch Models ◽  
Artificial Emboli

Abstract Ischemic Stroke is the most frequent type of stroke and is subject to many studies investigating prevention means. Avoiding the difficulties and ethical problems of experimental in-vivo research, in-vitro testing is a convenient way of studying in controlled conditions the morphological impact and mechanical aspects of emboli dynamics. This in-vitro study was performed with two realistic silicone aortic-arch phantoms submitted to physiological pulsatile flow conditions. In the in-vitro test bed, using automatic image tracking and analysis, it was made possible detecting and tracking artificial spherical emboli candidates circulating in the anatomic aortic-arch models under a realistic based-patient blood flow profile. The emboli trajectories as well as their repartition in the different supra-aortic branches are presented for the two aortic-arch geometries obtained from CT scans. Through a statistical analysis performed with several artificial emboli sizes, the experimental study shows that the repartition percentages of the emboli closely follow the flowrate repartition percentages for both aortic-arch models, suggesting that higher flowrates lead to higher concentrations of emboli in a given artery. Sets of human thrombi were also injected and the repartition percentages have been established, giving the same trend as for artificial emboli.

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.

The effect of pressure drop stabilization in arteries during variations in blood flow rate

1993 ◽  
Vol 148 (3) ◽  
pp. 285-294 ◽  
Author(s):  
V. M. KHAYUTIN ◽  
V. P. NIKOLSKY ◽  
A. N. ROGOZA ◽  
E. V. LUKOSHKOVA
Keyword(s):  
Blood Flow ◽  
Pressure Drop ◽  
Flow Rate ◽  
Blood Flow Rate ◽  
Effect Of Pressure

Abstract 372: The Endothelial Glycocalyx Promotes Homogenous Blood Flow Distribution within the Microvasculature

2016 ◽  
Vol 36 (suppl_1) ◽  
Author(s):  
P Mason McClatchey
Keyword(s):  
Fluid Dynamics ◽  
Blood Flow ◽  
Blood Viscosity ◽  
Tissue Perfusion ◽  
Microvascular Perfusion ◽  
Endothelial Glycocalyx ◽  
Heterogeneous Distribution ◽  
Disease States

Introduction: Impaired tissue oxygenation is observed in many disease states including congestive heart failure, diabetes, cancer and aging. Decreased tissue perfusion and heterogeneous distribution of blood flow in the microvasculature contributes to this pathology. The physiological mechanisms regulating homogeneity/heterogeneity of microvascular perfusion are presently unknown. We hypothesized that microfluidic properties of the glycocalyx would promote perfusion homogeneity. Methods: To test our hypothesis, we used established empirical formulations for modelling blood viscosity in vivo (blood vessels) and in vitro (glass tubes). We first assess distribution of blood flow in idealized arteriolar networks. We next simulated distribution of blood flow at an idealized capillary bifurcation. Finally, we simulated velocity profiles and pressure gradients within the vessel lumen with varying glycocalyx properties using a computational fluid dynamics approach. Results: We found that transit time heterogeneity (as assessed by STD to mean ratio) was increased approximately 9x (6.9x-10.6x) using in vitro formulations of blood viscosity relative to in vivo formulations. This effect was mathematically accounted for by increased effective blood viscosity in smaller arterioles. We also found that distribution of blood flow at an idealized microvascular bifurcation was more symmetric using the in vivo formulation than the in vitro formulation (approximately 2x greater disparity between flow in downstream vessels). This effect was mathematically accounted for by an increased hematocrit dependence of blood viscosity. Both the diameter- and hematocrit-based changes in blood viscosity were entirely predictable from fluid dynamics simulations incorporating a space-filling, semi-permeable glycocalyx layer. Summary: Our simulations indicate that the mechanical properties of the endothelial glycocalyx promote homogeneous microvascular perfusion. Conclusions: The literature provides evidence of both glycocalyx degradation and impaired tissue perfusion in the same disease states. Preservation or restoration of normal glycocalyx properties may be a viable strategy for improving tissue perfusion in a wide variety of diseases.

scholarly journals A Systematic Review for the Design of In Vitro Flow Studies of the Carotid Artery Bifurcation

2019 ◽  
Vol 11 (2) ◽  
pp. 111-127 ◽  
Author(s):  
A. M. Hoving ◽  
E. E. de Vries ◽  
J. Mikhal ◽  
G. J. de Borst ◽  
C. H. Slump
Keyword(s):  
Blood Flow ◽  
Carotid Artery ◽  
Flow Visualization ◽  
Design Process ◽  
Imaging Technique ◽  
Carotid Artery Disease ◽  
Imaging Techniques ◽  
Carotid Artery Bifurcation ◽  
Flow Parameters

Abstract Purpose In vitro blood flow studies in carotid artery bifurcation models may contribute to understanding the influence of hemodynamics on carotid artery disease. However, the design of in vitro blood flow studies involves many steps and selection of imaging techniques, model materials, model design, and flow visualization parameters. Therefore, an overview of the possibilities and guidance for the design process is beneficial for researchers with less experience in flow studies. Methods A systematic search to in vitro flow studies in carotid artery bifurcation models aiming at quantification and detailed flow visualization of blood flow dynamics results in inclusion of 42 articles. Results Four categories of imaging techniques are distinguished: MRI, optical particle image velocimetry (PIV), ultrasound and miscellaneous techniques. Parameters for flow visualization are categorized into velocity, flow, shear-related, turbulent/disordered flow and other parameters. Model materials and design characteristics vary between study type. Conclusions A simplified three-step design process is proposed for better fitting and adequate match with the pertinent research question at hand and as guidance for less experienced flow study researchers. The three consecutive selection steps are: flow parameters, image modality, and model materials and designs. Model materials depend on the chosen imaging technique, whereas choice of flow parameters is independent from imaging technique and is therefore only determined by the goal of the study.

Design and Optimization of the Restrictor of a Race Car

2015 ◽  
Author(s):  
Prithvi Raj Kokkula ◽  
Shashank Bhojappa ◽  
Selin Arslan ◽  
Badih A. Jawad
Keyword(s):  
Fluid Dynamics ◽  
Pressure Drop ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Air Flow ◽  
Intake Manifold ◽  
Maximum Pressure ◽  
Cross Sectional ◽  
Formula Sae

Formula SAE is a student competition organized by SAE International. The team of students design, manufacture and race a car. Restrictions are imposed by the Formula SAE rules committee to restrict the air flow into the intake manifold by putting a single restrictor of 20 mm. This rule limits the maximum engine power by reducing the mass flow rate flowing to the engine. The pull is greater at higher rpms and the pressure created inside the cylinder is low. As the diameter of the flow path is reduced, the cross sectional area for flow reduces. For cars running at low rpm when the engine requires less air, the reduction in area is compensated by accelerated flow of air through the restrictor. Since this is for racing purpose cars here are designed to run at very high rpms where the flow at the throat section reach sonic velocities. Due to these restrictions the teams are challenged to come up with improved restrictor designs that allow maximum pressure drop across the restrictor’s inlet and outlet. The design considered for optimizing a flow restrictor is a venturi type having 20 mm restriction between the inlet and the outlet complying with the rules set by Formula SAE committee. The primary objective of this work is to optimize the flow restriction device that achieves maximum mass flow and minimum pull from the engine. This implies the pressure difference created due to the cylinder pressure and the atmospheric pressure at the inlet should be minimum. An optimum flow restrictor is designed by conducting analysis on various converging and diverging angles and coming up with an optimum value. Venturi type is a tubular pipe with varying diameter along its length, through which the fluid flows. Law of governing fluid dynamics states that the “Velocity of the fluid increases as it passes through the constriction to satisfy the principle of continuity”. An equation can be derived from the combination of Bernoulli’s equation and Continuity equation for the pressure drop due to venturi effect. [1]. A Computational Fluid Dynamics (CFD) tool is used to calculate the minimum pressure drop across the restrictor by running a series of analysis on various converging and diverging angles and calculating the pressure drop. As a result, an optimum air flow restrictor is achieved that maximizes the mass flow rate and minimizes the engine pull.

Development of a 1D Model for Assessing the Aortic Root Pressure Drop With Viscosity and Compliance

2013 ◽  
Author(s):  
Hossein Mohammadi ◽  
Raymond Cartier ◽  
Rosaire Mongrain
Keyword(s):  
Blood Flow ◽  
Pressure Drop ◽  
Aortic Valve ◽  
Aortic Stenosis ◽  
Flow Rate ◽  
Aortic Root ◽  
Blood Flow Rate ◽  
Effective Orifice Area ◽  
Valvular Heart Diseases ◽  
1D Model

Aging and some pathologies such as arterial hypertension, diabetes, hyperglycemia, and hyperinsulimenia cause some geometrical and mechanical changes in the aortic valve microstructure. Cupsal thickening and lost of extensibility (increasing stiffness) are the consequences of these changes in the aortic valve which have a negative impact on the function of the valve [1]. The most frequent form of diseases of the aortic valve is the calcific aortic stenosis which is responsible for 80% of the North American deaths due to valvular heart diseases [2]. In this pathology, calcified nodules on the valve leaflets occur which lead to the thickening and stiffening of the leaflets and restricting the natural motion of the valve which presents an increased resistance to forward blood flow during the ejection phase of the cardiac cycle. To reduce the mortality and morbidity from the aortic stenosis, clinical management and proper diagnosis are essential [3]. Tranvalvular pressure gradient (TPG) and the effective orifice area (EOA), the minimum cross sectional area of the blood flow across the stenosis, are the most commonly used indices for assessing the aortic stenosis [4]. Numerous studies have been done to relate the TPG across the stenosis to the blood flow rate and EOA. Gorlin (1951) was the first to establish a relationship between TPG and EOA [5]. Several studies have reported deviations in valve area calculation by using Gorlin formula. This formula was derived based on some assumptions such as rigid circular orifice, non viscous and steady flow, while valvular orifices are compliant and the flow through them is viscous and pulsatile [6]. Several corrections have been proposed. However, even with these improved formula, significant deviations are still reported [7]. Calark (1978), Bermejo et al (2002) and Garcia et al (2006), by presenting a theoretical model, tried to express TPG in terms of the blood flow rate and EOA [8–10]. None of these studies considered the effect of the aortic root compliance on TPG. Nobari et al reported that the stiffening of the aorta changes the pressure drop and affects the leaflets motion [11]. Therefore, the objective of this study is to develop a 1D model for assessing the aortic pressure drop for the transient viscous blood flow across the aortic stenosis, by taking into account the vessel wall compliance. The derived TPG will be expressed in terms of the surrogate variables which are anatomical and hemodynamic data meaningful and accessible for physicians.

Simultaneous Convective and Diffusive Mass Transfers in a Hemodialyser

1990 ◽  
Vol 112 (2) ◽  
pp. 212-219 ◽  
Author(s):  
Michel Y. Jaffrin ◽  
Luhui Ding ◽  
Jean Marc Laurent
Keyword(s):  
Mass Transfer ◽  
Blood Flow ◽  
Boundary Layers ◽  
Flow Rate ◽  
Local Blood Flow ◽  
Mass Fluxes ◽  
In Vitro Measurements ◽  
Mass Transfers ◽  
Good Agreement

The mass transfer in a hemodialyser in the presence of combined dialysis and ultrafiltration has been calculated by integration of mass fluxes across the boundary layers in blood and dialysate phase taking into account the partial rejection of solute as well as changes in local blood flow and ultrafiltration flux along the membrane. Clearances of creatinin, vitamin B12, and myoglobin have been calculated as a function of blood and ultrafiltrate flow rate and were found to be in good agreement with in vitro measurements. The data suggest the following empirical correlation for the hemodiafiltration clearance CL=CLD+0.46QF where QF is the ultrafiltration flow rate and CLD is the clearance at QF=0.

Microfabricated Cavities for Adhesive Capture of Stem Cells Under Flow

2007 ◽  
Author(s):  
Dooyoung Lee ◽  
Kuldeepsinh Rana ◽  
Karin Lee ◽  
Lisa A. DeLouise ◽  
Michael R. King
Keyword(s):  
Fluid Dynamics ◽  
Stem Cells ◽  
Computational Fluid Dynamics ◽  
Blood Flow ◽  
Shear Stresses ◽  
Computational Fluid Dynamics Cfd ◽  
Future Work ◽  
Flow Experiments

In previous work, we have described the adhesive capture of circulating stem cells to surfaces coated with adhesive selectin protein, both in vitro and in vivo. Here we describe PDMS surfaces microfabricated to contain an array of square 80 × 80 × 80 micron cavities. These cavities are intended to provide a local bioreactor environment to culture stem cells over extended periods of time, while sheltered from the higher shear stresses of the surrounding blood flow external of the cavities. In this paper we present in vitro flow experiments with polymeric, blood cell-sized microspheres, showing the creation of stable vortices within the microscale cavities. Computational fluid dynamics (CFD) was performed to predict the velocity field within the cavity, and for comparison with experimentally determined microsphere velocities. Future work will establish the ability to place local chemoattract molecules within the cavity interior, and the ability to accumulate viable stem cells within these cavities.

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