Haemodialysers and Associated Devices

Hoenich, Nicholas A.; Woffindin, C.; Ronco, Claudio

doi:10.1007/978-0-585-36947-1_7

Cited by 18 publications

(15 citation statements)

References 123 publications

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“…The widespread use of polysulfone membranes for high-flux hemodialysis has increased in recent years [22,23]. Here two synthetic polysulfone membranes were investigated in a comparative analysis regarding their convective and diffusive performance characteristics during chronic high-flux hemodialysis.…”

Section: Discussionmentioning

confidence: 99%

Enhanced Functional Performance Characteristics of a New Polysulfone Membrane for High-Flux Hemodialysis

Klingel

Ahrenholz²,

Schwarting

et al. 2002

Blood Purif

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Elimination of uremic solutes with molecular weights up to 60 kD, without significant loss of albumin is an important therapeutic goal to optimize outcomes in chronic hemodialysis patients. To characterize a newly developed polysulfone dialyzer (APS-650) a comparative analysis was performed with a highly advanced polysulfone dialyzer (F-60S) including 22 stable chronic hemodialysis patients. Diffusive clearances were determined, and albumin loss was calculated. The elimination profile of uremic solutes up to 32.0 kD was assessed in vivo by sieving coefficients, clearances, and reduction ratios of β₂-microglobulin (11.8 kD), myoglobin (17.2 kD), prolactin (23.0 kD), and α₁-microglobulin (32.0 kD). Hemocompatibility was tested in serial measurements of total white blood cell count, platelet count, C3a, and neutrophil elastase. No significant albumin loss was detected. Significantly higher sieving coefficients, clearances, and reduction ratios for proteins with molecular weight up to 32.0 kD were demonstrated with the newly developed polysulfone membrane. Both polysulfone membranes were equal concerning hemocompatibility parameters. The APS-650 dialyzer allowed optimized hemodialysis treatment with respect to clearance of medium-sized uraemic solutes by high-flux dialysis.

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Section: Discussionmentioning

confidence: 99%

Enhanced Functional Performance Characteristics of a New Polysulfone Membrane for High-Flux Hemodialysis

Klingel

Ahrenholz²,

Schwarting

et al. 2002

Blood Purif

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“…Oncotic pressure, which is exerted by the plasma proteins and opposes the hydrostatic transmembrane pressure, is implemented as a discontinuous local pressure drop at the skin-bulk interface. Because of the difficulty to induce in vitro a stable protein layer on the membrane [10], initial oncotic pressure from literature (25mmHg) was used [13,14]. Moreover, as hemoconcentration takes place in axial direction, the oncotic pressure is varying with hematocrit.…”

Section: Model Boundary Conditionsmentioning

confidence: 99%

“…Assuming a constant blood and dialysate inlet flow of 250 and 500mL/min, respectively, blood and dialysate outlet pressures of 10kPa (75mmHg) and 5Pa (0.04mmHg), respectively, and an initial oncotic pressure of 3.33kPa (25mmHg) [13,14], the pressure distribution renders an overall ultrafiltration flow of 45mL/min while no backfiltration occurs. As blood, with an initial viscosity of 3mPa.s, flows through the dialyzer, the water removal causes hemoconcentration.…”

Section: Microscopic Flow and Mass Transportmentioning

confidence: 99%

Computational fluid and mass transport on macro and micro scales in an artificial kidney

Eloot¹,

Verdonck²

2005

Modelling in Medicine and Biology VI

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The evaluation of dialyzer geometry was obtained by investigating transport processes and fluid properties inside the dialyzer. With computational fluid dynamics (CFD), a macroscopic as well as a microscopic model of the dialyzer was developed.Blood and dialysate flow distributions were calculated in a macroscopic numerical model of a low flux hollow fiber dialyzer. Computer simulations were compared to flow field SPECT visualizations (Single Photon Emission Computerized Tomography). The derived local fluid velocities were further implemented in a three-dimensional microscopic computer model of a single hollow fiber with its surrounding membrane and dialysate compartment. Different equations govern blood and dialysate flow (Navier-Stokes), radial filtration flow (Darcy), and solute transport (convection-diffusion). Blood was modeled as a non-Newtonian fluid with a viscosity varying both in radial and axial direction. Dialysate flow was assumed as a laminar Newtonian flow with constant viscosity. The permeability characteristics of the asymmetrical polysulphone membrane were calculated from laboratory tests for forward and backfiltration.The model was calibrated and validated in order to accurately calculate water removal as well as mass transport of small (urea) and middle molecules (vitamin B12 and inulin). Furthermore, the present microscopic CFD model was used to investigate the impact on the mass removal of dialyzer geometry and flow distributions.

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“…Since the pre-and post-dialyzer pressure difference (¢P) is proportional to 1/n (where n = number of fibers in the dialyzer) according to the formula ¢P = 8 * Q B * Ë * L/n *  * r4 (where Q B = blood flow, Ë = viscosity, L = length of the dialyzer, r = radius of the dialyzer fiber) [4][5][6] and A (effective surface area of the dialyzer) is proportional to J (solute transport) according to the formula A = J/Ko * ¢C (where Ko = mass transfer coefficient and ¢C = difference in the solute concentration between the two sides of the membrane) [7], a progressive clotting of the fibers of the dialyzer will generate, probably with a similar kinetic, an increase in ¢P and a decrease in solute transport. A direct correlation between urea clearance and residual fiber bundle volume (a 10% decrease in the first is generated by a 20% loss in the second) was identified in a previous in vitro study [2].…”

Section: Methods and Patientsmentioning

confidence: 99%

Does Monitoring of Pre-/Post-Dialyzer Pressure Difference Improve Efficiency in Intermittent Hemodialysis?

Gabutti

Colucci²,

Martella³

et al. 2003

Blood Purif

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Background: Continuous monitoring of pre-/post-dialyzer pressure difference (ΔP) is widely used in continuous renal replacement therapies to monitor extracorporeal circuit function. The aim of this study was to verify whether ΔP may help to identify chronic subclinical worsening of dialysis quality due to incomplete dialyzer clotting in intermittent hemodialysis. Methods: Nine chronic hemodialysis patients were enrolled in the study and dialyzed twice (high-flux polysulfone dialyzer) with ΔP and urea-clearance monitoring: the first session with a standard anticoagulation and the second without. To verify whether a visible clotting of the dialyzer precedes or follows a significant ΔP increase, we checked the dialyzers for the presence of red clots after a saline flush performed when a 50% increase in ΔP was registered. Results: In the second dialysis session after a 50% increase in ΔP (documented in 7/9 patients), all dialyzers, after saline flush, showed a visible fiber clotting but not a significant reduction (>15%) in urea clearance. In the majority of the patients (6/7), until a few minutes before complete occlusion of the extracorporeal circuit, the urea clearance did not change significantly (–8.9 ± 12.7%). Conclusions: The usual check of the presence or absence of red clots in the dialyzer at the end of the dialysis session is enough, in the absence of red clots, to ensure that dialyzer efficiency is maintained during the whole treatment. Contrary to what is applied in CRRT, a continuous monitoring of ΔP during intermittent hemodialysis would not significantly help to unmask unnoticed inefficient hemodialysis sessions.

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Haemodialysers and Associated Devices

Cited by 18 publications

References 123 publications

Enhanced Functional Performance Characteristics of a New Polysulfone Membrane for High-Flux Hemodialysis

Enhanced Functional Performance Characteristics of a New Polysulfone Membrane for High-Flux Hemodialysis

Computational fluid and mass transport on macro and micro scales in an artificial kidney

Does Monitoring of Pre-/Post-Dialyzer Pressure Difference Improve Efficiency in Intermittent Hemodialysis?

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