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.

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.

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.

Mass Transfer Modelling in an Acoustic-Assisted Osmotic Process

2006 ◽  
Vol 258-260 ◽  
pp. 600-609 ◽  
Author(s):  
Susana Simal ◽  
J.A. Cárcel ◽  
J. Bon ◽  
Á. Castell-Palou ◽  
Carmen Rosselló
Keyword(s):  
Mass Transfer ◽  
Sucrose Solution ◽  
Mutual Effect ◽  
Water Losses ◽  
Solute Transfer ◽  
Mass Fluxes ◽  
Mechanical Waves ◽  
Pork Loin ◽  
Diffusional Model ◽  
Mass Transfers

Ultrasounds are mechanical waves that produce different effects when travelling through a medium, some related to mass transfer (i.e. microstirring at the interface, the so called "sponge effect" and cavitations). Thus, ultrasound appears to be a way to reduce both the internal and external resistances in osmotic food drying processes. In this study, the influence of the ultrasounds on water and solute transports during osmotic processes of drying is evaluated. Two different systems have been studied, apple slabs immersed in 30ºBrix sucrose solution, and pork loin slabs in sodium chloride saturated brine. The mathematical modelling of the mass transfers has been carried out by assuming diffusional mechanism and considering the mutual effect between the two mass transfers, the water losses and solute gains. The mass transfer curves in the osmotic process of apple drying in sucrose solution were satisfactorily simulated by using a diffusional model considering independent mass fluxes. Nevertheless, this model did not allow for the accurate simulation of the water losses in the system constituted by pork-loin in saline solution. When the mass fluxes were considered mutually affected, the simulation was accurate for both cases water and solute transfer.

Turbulent Boundary Layers With Mass Transfer by the Dorodnitsyn Finite Element Method

1987 ◽  
Vol 54 (1) ◽  
pp. 197-202 ◽  
Author(s):  
C. A. J. Fletcher ◽  
R. W. Fleet
Keyword(s):  
Mass Transfer ◽  
Finite Element ◽  
Boundary Layers ◽  
Adverse Pressure Gradient ◽  
Skin Friction Coefficient ◽  
Turbulent Boundary Layers ◽  
Element Formulation ◽  
Surface Mass ◽  
Surface Mass Transfer ◽  
Good Agreement

The Dorodnitsyn finite element formulation is extended to cover incompressible, two-dimensional turbulent boundary layers with surface mass transfer in the normal direction. The method is shown to give accurate and economical answers with only eleven points spanning the boundary layer. Good agreement is obtained when the computational solutions are compared with the experimental results of McQuaid [13] for skin friction coefficient, displacement and momentum thickness and velocity profiles. Zero and adverse pressure gradient and discontinuous injection cases have been considered.

scholarly journals Balancing pulmonary blood flow: Theory, in vitro measurements, and clinical correlation of systemic-to-pulmonary shunt banding

2016 ◽  
Vol 152 (5) ◽  
pp. 1343-1352.e2 ◽  
Author(s):  
Cori R. Atlin ◽  
Christoph Haller ◽  
Osami Honjo ◽  
Anusha Jegatheeswaran ◽  
Glen S. Van Arsdell
Keyword(s):  
Blood Flow ◽  
Pulmonary Blood Flow ◽  
Flow Theory ◽  
Clinical Correlation ◽  
Pulmonary Shunt ◽  
In Vitro Measurements

A Combined Heat Clearance Method for Tissue Blood Flow Measurement

1991 ◽  
Vol 113 (4) ◽  
pp. 438-445 ◽  
Author(s):  
Sarit Abramovich-Sivan ◽  
Vili Benary ◽  
Thalia Kaspi ◽  
Solange Akselrod
Keyword(s):  
Blood Flow ◽  
Pulse Method ◽  
Continuous Method ◽  
Tissue Blood Flow ◽  
Experimental Systems ◽  
In Vitro Measurements ◽  
On Line ◽  
Heat Clearance

Tissue Blood Flow is measured by applying a combined procedure of two independent approaches based on heat clearance: the Pulse Decay Method and the Continuous Method. The Pulse Method allows absolute assessment of tissue BF with no need for calibration, and can be applied only if the tissue BF is steady during the period of measurement. On the other hand, the Continuous Method enables the observation of rapid changes in tissue BF, and can be applied under non steady-state conditions. Using the combined method, a continuous quantitative measurement of transient changes in tissue BF can be obtained. For this purpose, we have developed two experimental systems consisting of independent electronic units: a Pulse Unit and a Continuous Unit. A micro-computer with dedicated software controls the operation of the electronic units and calculates tissue BF on-line. In vitro measurements are performed and demonstrate the reliability of the methods. In vivo measurements in rat brain tissue are also performed and include physiological and pharmacological changes of local tissue BF. The results of the two heat clearance methods correlate well with tissue BF values measured by a third independent method, the Hydrogen Clearance Method.

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 Blood flow limitations of solute transport across the visceral peritoneum.

1997 ◽  
Vol 8 (12) ◽  
pp. 1946-1950
Author(s):  
M Kim ◽  
J Lofthouse ◽  
M F Flessner
Keyword(s):  
Mass Transfer ◽  
Blood Flow ◽  
Tissue Level ◽  
Local Blood Flow ◽  
Doppler Flowmetry ◽  
Flow Reduction ◽  
Visceral Peritoneum ◽  
Blood Flow Reduction ◽  
Effective Exchange ◽  
Liver Surface

In a previous study, no limitations to urea transfer across the parietal peritoneum were demonstrated with decreases in local blood flow of 70%. It was hypothesized that the visceral peritoneum would have similar characteristics. To address this problem at the tissue level, diffusion chambers were affixed to the serosal side of the stomach, cecum, or liver of anesthetized rats (n = 6 each tissue), and solutions containing 14C urea were placed in the chamber. During each experiment, the local chamber blood flow was measured with laser Doppler flowmetry, and, simultaneously, the disappearance of the tracer versus time was determined under three conditions: control, after 60 to 70% blood flow reduction, and postmortem (flow = 0). The results showed no difference in the urea mass transfer coefficient (MTC; mean +/- SEM; cm/min x 10[3]) between control and blood flow reduction for the stomach (4.0 +/- 0.4 versus 3.6 +/- 0.3) or for the cecum (4.6 +/- 0.3 versus 4.0 +/- 0.3). However, the MTC was significantly decreased by local blood flow reduction in the liver (5.4 +/- 0.2 versus 2.6 +/- 0.2). Postmortem data demonstrated significant reductions in the MTC with blood flow equal to zero. It is concluded that a 60 to 70% blood flow reduction from control values does not limit solute transperitoneal transfer in the hollow viscera but causes significant changes in the mass transfer across the liver surface. Because the liver makes up only a small portion of the effective exchange area, overall transperitoneal solute transfer should not be greatly affected by significant decreases in blood flow.

Sign in / Sign up

Export Citation Format

Share Document