The Experts below are selected from a list of 126 Experts worldwide ranked by ideXlab platform
Stephen R. Ash - One of the best experts on this subject based on the ideXlab platform.
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Treatment of severe tricyclic antidepressant overdose with extracorporeal sorbent detoxification
Advances in renal replacement therapy, 2002Co-Authors: Stephen R. Ash, Donald E. Blake, Howard Levy, Mohammed Akmal, Rita A. Mankus, James M. Sutton, David R. Emery, John C. Scanlon, David J. CarrAbstract:Abstract Tricyclic overdose can be a medical emergency, and therapy with intravenous bicarbonate is not always successful in preventing cardiac toxicity or coma. Mortality in patients developing these complications is from 1% to 15%. Extracorporeal detoxification with sorbents has been used in treatment of patients with very high drug levels and declining clinical condition. Ten patients with serious drug overdose caused by tricyclics failed to respond quickly to standard therapy and were in stage 3-4 encephalopathy. Nine of these patients were on respirator support, 5 had hypotension, and 6 had QRS widening. Average level was 1,423 μg/L at presentation. Enteral activated charcoal and intravenous (IV) bicarbonate were initiated in the emergency room. The patients were treated for 3 to 4 hours with the Liver Dialysis Unit, a hemodiabsorption device using a cellulosic Plate Dialyzer and sorbent suspension as dialysate. Inflow and outflow blood levels indicated that the hemodetoxifier removed modest amounts of the tricyclics, metabolites, and other consumed drugs. The clinical improvement of the patients was dramatic, with patients reaching stage 0 or 1 encephalopathy during the treatment. Ventilator support was removed at the end of treatment for 3 patients who had not already developed pneumonia, and for others was prolonged up to 48 hours because of pneumonia, rather than mental status. Average length of stay in the intensive care unit (ICU) was 4.8 days (range 1 to 7 days). None of the patients died despite their high risk for ventricular arrhythmias, seizures, and death. Clinical improvement may have been attributable to removal of free drug from the blood or to removal of drug metabolites. © 2002 by the National Kidney Foundation, Inc.
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Push-pull sorbent based pheresis for treatment of acute hepatic failure: the BioLogic-detoxifier/plasma filter System.
ASAIO journal (American Society for Artificial Internal Organs : 1992), 1998Co-Authors: Stephen R. Ash, Donald E. Blake, David J. Carr, K. D. HarkerAbstract:The BioLogic-DTe® (detoxifier) System is an extracorporeal blood treatment device that uses the membranes of a cellulosic Plate Dialyzer to propel blood in and out through a single lumen access (on a 12 sec cycle) and circulates a suspension of powdered charcoal and cation exchanger through the dialysate spaces to absorb many soluble toxins in the treatment of hepatic failure. The BioLogic-DTPF (detoxifier/plasma filter) System adds two Gambro plasma filters downstream from the Plate Dialyzer, which allows most of the blood plasma to pass out of the blood, contact powdered charcoal in a suspension, and then return to the blood during each 12 sec cycle (creating push-pull sorbent based pheresis). A roller pump exchanges charcoal suspension between the plasma filter case and a 700 ml bag of powdered charcoal suspension. At a blood flow rate of 150-200 ml/min, 100 ml/min of plasma moves bidirectionally through the plasma filter membranes. Direct contact of plasma with charcoal outside the plasma filter membranes removes creatinine with a clearance rate equal to plasma flow (100 ml/min); clearance of strongly protein bound toxins, such as unconjugated bilirubin, is lower (10-40 ml/min). In this article, the authors explain the mechanisms of operation of this system and present in vitro tests that define its chemical efficiency. Also described are potential problems, tests that indicate the severity of these problems, and monitors and algorithms to detect or avoid these problems in clinical use of the system. The results of the treatment of two patients with acute hepatic failure and coma using the BioLogic-DTPF System are reviewed.
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Hemodiabsorption in Treatment of Acute Hepatic Failure and Chronic Cirrhosis with Ascites
Artificial organs, 1994Co-Authors: Stephen R. AshAbstract:: Hemodiabsorption is a selective chemical removal process during which blood passes through dialysis membrane packages surrounded by a suspension of fine sorbent particles. The BioLogic-DT system contains charcoal and cation exchangers in a suspension that passes through dialysate spaces of a cellulosic membrane Plate Dialyzer. The system has proven effective in treatment of patients with serious drug overdose and has demonstrated positive effects in treatment of stage 4 coma due to hepatic failure. Recently, the charcoal in this system has been preloaded with branch chain amino acids to return these acids to patients while aromatic amino acids are removed. Further improvements include addition of osmotically active agents to the priming fluid and sorbent to increase blood oncotic pressure and transfer of ascitic fluid to blood while ultrafiltration transfers fluid out of the blood. Clinical testing of these improvements is now beginning in patients with ascites and encephalopathy due to chronic hepatic insufficiency and cirrhosis. Future improvements will include protein permeable membranes to increase removal of protein-bound toxins and addition of hepatic cells downstream from the hemodiabsorption unit.
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Effect of sorbent-based dialytic therapy with the BioLogic-DT on an experimental model of hepatic failure.
ASAIO journal (American Society for Artificial Internal Organs : 1992), 1993Co-Authors: Stephen R. Ash, Donald E. Blake, David J. Carr, J. B. Rainier, A. A. Demetriou, J. RozgaAbstract:An experimental model of hepatic failure in the dog has been developed in which the liver is devascularized in two stages. Under general anesthesia, a portacaval shunt is created, ligatures placed around the hepatic and gastroduodenal arteries, and the dog recovered. Two days later under general anesthesia, the ligatures are pulled, converting hepatic insufficiency to hepatic failure. Five control animals developed hypotension, severe lactic acidosis, hypoglycemia, and increasing liver enzyme levels during 6 hrs of follow-up. The BioLogic-DT system includes a cellulosic Plate Dialyzer with a suspension of powdered charcoal and cation exchangers as dialysate. Five animals were treated with the BioLogic-DT for 6 hrs after creation of hepatic failure. These animals were more stable physiologically, developed less lactic acidosis and less enzyme elevation, and maintained high normal blood glucose levels. The results help explain the clinical improvement demonstrated in patients with hepatic failure treated by the BioLogic-DT, and confirm that many of the toxins of hepatic failure are dialyzable and bound by simple sorbents such as charcoal and cation exchangers.
Ahmet R Ozdural - One of the best experts on this subject based on the ideXlab platform.
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Prediction of overall mass transfer coefficients in continuous Dialyzers: comparison of pseudo steady state approximation and unsteady state solution
Desalination, 2009Co-Authors: A. Alkan-sungur, Ahmet R OzduralAbstract:This work describes the determination of carboxylic acid overall mass transfer coefficients in a circulating flow experimental set-up composed of a flat Plate Dialyzer and a concentrate reservoir. Sodium acetate and sodium propionate were used as the sodium salts of carboxylic acids. By referring to the model generated concentrate reservoir concentration vs. time data, we focused our attention on the quantitative justification of the previously published equation of ours that could be implemented as a new tool in the determination of overall mass transfer coefficients in dialysis processes. Furthermore, the present study was undertaken for the comparison of unsteady state case, i.e. rigorous solution, predicted overall mass transfer coefficients against a simpler expression based on a pseudo steady state approximation. Contrary to the concentrate side, single pass flow was used on the diffusate side where the receiving liquid was deionized water. It was found that the overall mass transfer coefficient values, K for both solutes increased with the increase of the flow rate. The K values calculated by rigorous solution, i.e. taking into account the unsteady state effects, were always higher than those obtained via pseudo steady state approximation.
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Sorbent Membranes: Determination of Sorption Capacity and True Membrane Permeability
Artificial Organs, 2008Co-Authors: Ahmet R Ozdural, Erhan PiskinAbstract:Sorbent membranes are designed to meet the requirements for extracorporeal treatment of body fluids. These membranes offer the possibility of combining hemodialysis and hemoperfusion in a single device. Transport of solutes with both sorption and dialysis occurs simultaneously in a sorbent membrane Dialyzer. In an effort to determine the sorption capacity and true membrane permeability (by dialysis only) of sorbent membranes, in vitro data were obtained for creatinine. The individual effects of dialysis and sorption on the rate of removal of solutes and their dependence upon flow rate in a sorbent membrane Dialyzer were determined from the data of solute vessel concentration vs time. Experiments were carried out with a continuous flow, flat-Plate Dialyzer and Enka AG sorbent membranes have been selected for evaluation. It was found that sorption plays an important role in the creatinine removal. However, as the time increases, sorption becomes relatively less important and the creatinine removal becomes dominated by dialysis.
Muhammad Kahshan - One of the best experts on this subject based on the ideXlab platform.
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A mathematical model of blood flow in a permeable channel: application to flat Plate Dialyzer
Physica Scripta, 2020Co-Authors: Muhammad Kahshan, Mohammad Rahimi-gorjiAbstract:This article presents the theoretical study of the physiological phenomenon brought up by filtration of a non-Newtonian Casson fluid between two parallel permeable membranes. This situation corresponds to blood filtration process in a flat Plate hemoDialyzer (FPH). Seepage of fluid across the membrane is considered in accordance with the Darcy's law and the equations of motion governing the flow are modeled. Using the low Reynolds number and long membrane length assumption, equations of motion are solved exactly. Equations describing velocity and pressure filed and various flow variables are derived and effects of wall slip parameter, wall filtration coefficient and the yield stress are presented graphically. A strong influence of these parameters is observed on the flow in an FPH. Theoretical values of the membrane filtration coefficient and mean pressure drop in an FPH are calculated and they are found to be in close agreement with the corresponding available empirical and experimental values in the literature. For certain limiting range of physical parameters, derived solutions reveal that the axial flow rate of Casson fluid in an FPH decays at an exponential rate. This is a physically valid and widely admitted result, used by several researchers in studying the blood filtration process in renal tubules of mammalian kidneys. Since the presented solutions in this article are reduced to their corresponding Newtonian fluid flow solutions between permeable membrane, therefore, it is concluded that a wide range of applications in physiology and engineering can be covered up by the present investigation.
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A Jeffrey Fluid Model for a Porous-walled Channel: Application to Flat Plate Dialyzer.
Scientific reports, 2019Co-Authors: Muhammad Kahshan, Abdul M. SiddiquiAbstract:Creeping motion of a Jeffrey fluid in a small width porous-walled channel is presented with an application to flow in flat Plate hemoDialyzer. Darcy's law is used to characterize the fluid leakage through channel walls. Using suitable physical approximations, approximate analytical solution of equations of motion is obtained by employing perturbation method. Expressions for velocity field and the hydrostatic pressure are obtained. Effects of filtration coefficient, the inlet pressure and Jeffrey fluid parameters on the flow characteristics are discussed graphically. The derived results are used to study the flow of filtrate in a flat plat hemoDialyzer. Using the derived solutions, theoretical values of the filtration rate and the mean pressure difference in the hemoDialyzer are calculated. On comparing the computed results with the available experimental data, a reasonable agreement between the two is found. It is concluded that the presented model can be used to study the hydrodynamical aspects of the fluid flow in a flat Plate hemoDialyzer.
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Hydrodynamical Study of Micropolar Fluid in a Porous-Walled Channel: Application to Flat Plate Dialyzer
Symmetry, 2019Co-Authors: Muhammad Kahshan, Abdul M. SiddiquiAbstract:This article investigates the two-dimensional creeping flow of a non-Newtonian micropolar fluid in a small width permeable channel. Fluid is absorbed through permeable walls at a variable rate. This situation arises in filtration and mass transfer phenomena in industrial and engineering processes. The exact solution of the equations of motion is obtained. Graphs of the velocity profiles and pressure drop reveal the significant impact of the non-Newtonian nature of the micropolar fluid on the flow. The obtained solutions are used to discuss the hydrodynamical aspects of the physiological phenomenon of blood filtration in an artificial kidney, the flat Plate Dialyzer (FPD). Expressions for finding the ultrafiltration rate and mean pressure drop in an FPD are derived. Ultrafiltration rate and the mean pressure difference in an FPD are computed using derived expressions. A comparison of these with the existing empirical and experimental results shows a good agreement. For certain values of parameters, the derived form of the flow rate reveals that the axial flow rate in an FPD decays exponentially along the membrane length. This is a well-established and admitted result used by several researchers for studying the hydrodynamics of blood flow in renal tubules of kidneys. It is concluded that the presented model can be used to study the hydrodynamical aspects of blood flow in an FPD.
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Hydrodynamical study of flow in a permeable channel: Application to flat Plate Dialyzer
International Journal of Hydrogen Energy, 2019Co-Authors: Muhammad Kahshan, Mohammad Rahimi-gorjiAbstract:Abstract This article investigates the problem of creeping motion of a Newtonian fluid in a permeable slit. The seepage velocity at the slit walls is assumed to obey the Darcy's law whereas the tangential velocity is taken in accordance with the Beaver's and Joseph's slip boundary condition. Exact solution of the hydrodynamical equations is obtained using the separation of variables technique. Expressions describing various quantities of interests are also derived. The influence of slip parameter is observed on the velocity and pressure field. The obtained results are applied to the physiological problem of blood flow in a flat Plate Dialyzer. Using the available data in the literature, theoretical values of filtration coefficient and the mean pressure drop in a flat Plate Dialyzer are computed and found to be in good agreement with the corresponding available experimental values.
Mohammad Rahimi-gorji - One of the best experts on this subject based on the ideXlab platform.
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A mathematical model of blood flow in a permeable channel: application to flat Plate Dialyzer
Physica Scripta, 2020Co-Authors: Muhammad Kahshan, Mohammad Rahimi-gorjiAbstract:This article presents the theoretical study of the physiological phenomenon brought up by filtration of a non-Newtonian Casson fluid between two parallel permeable membranes. This situation corresponds to blood filtration process in a flat Plate hemoDialyzer (FPH). Seepage of fluid across the membrane is considered in accordance with the Darcy's law and the equations of motion governing the flow are modeled. Using the low Reynolds number and long membrane length assumption, equations of motion are solved exactly. Equations describing velocity and pressure filed and various flow variables are derived and effects of wall slip parameter, wall filtration coefficient and the yield stress are presented graphically. A strong influence of these parameters is observed on the flow in an FPH. Theoretical values of the membrane filtration coefficient and mean pressure drop in an FPH are calculated and they are found to be in close agreement with the corresponding available empirical and experimental values in the literature. For certain limiting range of physical parameters, derived solutions reveal that the axial flow rate of Casson fluid in an FPH decays at an exponential rate. This is a physically valid and widely admitted result, used by several researchers in studying the blood filtration process in renal tubules of mammalian kidneys. Since the presented solutions in this article are reduced to their corresponding Newtonian fluid flow solutions between permeable membrane, therefore, it is concluded that a wide range of applications in physiology and engineering can be covered up by the present investigation.
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Hydrodynamical study of flow in a permeable channel: Application to flat Plate Dialyzer
International Journal of Hydrogen Energy, 2019Co-Authors: Muhammad Kahshan, Mohammad Rahimi-gorjiAbstract:Abstract This article investigates the problem of creeping motion of a Newtonian fluid in a permeable slit. The seepage velocity at the slit walls is assumed to obey the Darcy's law whereas the tangential velocity is taken in accordance with the Beaver's and Joseph's slip boundary condition. Exact solution of the hydrodynamical equations is obtained using the separation of variables technique. Expressions describing various quantities of interests are also derived. The influence of slip parameter is observed on the velocity and pressure field. The obtained results are applied to the physiological problem of blood flow in a flat Plate Dialyzer. Using the available data in the literature, theoretical values of filtration coefficient and the mean pressure drop in a flat Plate Dialyzer are computed and found to be in good agreement with the corresponding available experimental values.
Abdul M. Siddiqui - One of the best experts on this subject based on the ideXlab platform.
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Application of Recursive Theory of Slow Viscoelastic Flow to the Hydrodynamics of Second-Order Fluid Flowing through a Uniformly Porous Circular Tube
Mathematics, 2020Co-Authors: Kaleemullah Bhatti, Abdul M. Siddiqui, Zarqa BanoAbstract:Slow velocity fluid flow problems in small diameter channels have many important applications in science and industry. Many researchers have modeled the flow through renal tubule, hollow fiber Dialyzer and flat Plate Dialyzer using Navier Stokes equations with suitable simplifying assumptions and boundary conditions. The aim of this article is to investigate the hydrodynamical aspects of steady, axisymmetric and slow flow of a general second-order Rivlin-Ericksen fluid in a porous-walled circular tube with constant wall permeability. The governing compatibility equation have been derived and solved analytically for the stream function by applying Langlois recursive approach for slow viscoelastic flows. Analytical expressions for velocity components, pressure, volume flow rate, fractional reabsorption, wall shear stress and stream function have been obtained correct to third order. The effects of wall Reynolds number and certain non-Newtonian parameters have been studied and presented graphically. The obtained analytical expressions are in agreement with the existing solutions in literature if non-Newtonian parameters approach to zero. The solutions obtained in this article may be considered as a generalization to the existing work. The results indicate that there is a significant dependence of the flow variables on the wall Reynolds number and non-Newtonian parameters.
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A Jeffrey Fluid Model for a Porous-walled Channel: Application to Flat Plate Dialyzer.
Scientific reports, 2019Co-Authors: Muhammad Kahshan, Abdul M. SiddiquiAbstract:Creeping motion of a Jeffrey fluid in a small width porous-walled channel is presented with an application to flow in flat Plate hemoDialyzer. Darcy's law is used to characterize the fluid leakage through channel walls. Using suitable physical approximations, approximate analytical solution of equations of motion is obtained by employing perturbation method. Expressions for velocity field and the hydrostatic pressure are obtained. Effects of filtration coefficient, the inlet pressure and Jeffrey fluid parameters on the flow characteristics are discussed graphically. The derived results are used to study the flow of filtrate in a flat plat hemoDialyzer. Using the derived solutions, theoretical values of the filtration rate and the mean pressure difference in the hemoDialyzer are calculated. On comparing the computed results with the available experimental data, a reasonable agreement between the two is found. It is concluded that the presented model can be used to study the hydrodynamical aspects of the fluid flow in a flat Plate hemoDialyzer.
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Hydrodynamical Study of Micropolar Fluid in a Porous-Walled Channel: Application to Flat Plate Dialyzer
Symmetry, 2019Co-Authors: Muhammad Kahshan, Abdul M. SiddiquiAbstract:This article investigates the two-dimensional creeping flow of a non-Newtonian micropolar fluid in a small width permeable channel. Fluid is absorbed through permeable walls at a variable rate. This situation arises in filtration and mass transfer phenomena in industrial and engineering processes. The exact solution of the equations of motion is obtained. Graphs of the velocity profiles and pressure drop reveal the significant impact of the non-Newtonian nature of the micropolar fluid on the flow. The obtained solutions are used to discuss the hydrodynamical aspects of the physiological phenomenon of blood filtration in an artificial kidney, the flat Plate Dialyzer (FPD). Expressions for finding the ultrafiltration rate and mean pressure drop in an FPD are derived. Ultrafiltration rate and the mean pressure difference in an FPD are computed using derived expressions. A comparison of these with the existing empirical and experimental results shows a good agreement. For certain values of parameters, the derived form of the flow rate reveals that the axial flow rate in an FPD decays exponentially along the membrane length. This is a well-established and admitted result used by several researchers for studying the hydrodynamics of blood flow in renal tubules of kidneys. It is concluded that the presented model can be used to study the hydrodynamical aspects of blood flow in an FPD.