Advanced modeling of highflux hemodialysis

Raff, Manfred; Welsch, Melanie; Göhl, H.; Hildwein, Helmut; Storr, Markus; Wittner, Bernd

doi:10.1016/s0376-7388(02)00552-5

Cited by 19 publications

(10 citation statements)

References 6 publications

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“…Due to Raff [46], the blood side and dialysate side mass transfer coefficients K B and K D depend on module geometry, fluid properties and operating conditions:…”

Section: Dialysis Simulation Experiments In Vitromentioning

confidence: 99%

High performance thin-film nanofibrous composite hemodialysis membranes with efficient middle-molecule uremic toxin removal

Shen

Zhu

et al. 2017

Journal of Membrane Science

119

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Membrane structure design is critical for the development of high-performance hemodialysis membranes. Here, a thin-film nanofibrous composite (TFNC) membrane, consisting of a two-tier composite structure, i.e., an ultrathin hydrophilic separation layer of chemically cross-linked polyvinyl alcohol (PVA), and an electrospun polyacrylonitrile (PAN) nanofibrous supporting layer, was demonstrated as the hemodialysis membrane for the first time. The optimized PVA/PAN TFNC membrane exhibited high permeability (~ 290.5 L/m 2 h at 0.1 MPa) and excellent selectivity which should be attributed to its unique structure with ultrathin separation layer and highly porous supporting layer. In addition, the TFNC membrane also possessed excellent overall mechanical properties, good hydrophilicity and comparable hemocompatibility properties (protein adsorption, platelet adhesion, complement activation, hemolysis ratio). The hemodialysis simulation experiments on optimized TFNC membrane showed that 82.6% of urea and 45.8% of lysozyme were cleaned and 98.8% of bovine serum albumin (BSA) was retained. The TFNC membranes exhibited excellent hemodialysis performances, especially for the middle-molecule uremic toxin removal, which was more efficient than conventional hemodialysis membranes reported so far, suggesting PVA/PAN TFNC membranes as promising alternatives for hemodialysis applications.

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“…Due to Raff [46], the blood side and dialysate side mass transfer coefficients K B and K D depend on module geometry, fluid properties and operating conditions:…”

Section: Dialysis Simulation Experiments In Vitromentioning

confidence: 99%

High performance thin-film nanofibrous composite hemodialysis membranes with efficient middle-molecule uremic toxin removal

Shen

Zhu

et al. 2017

Journal of Membrane Science

119

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“…To simulate middle molecule removal in low flux dialysers or large molecule removal in high flux dialysers, some additional aspects should be implemented. Since relative larger molecules are mainly transported by convection, the influence of the sieving coefficient must be considered (Ross 1974, Legallais et al 2000, Raff et al 2003. Furthermore, the accumulation of larger molecules near the membrane causes concentration polarization to develop (Legallais et al 2000, Raff et al 2003.…”

Section: Discussionmentioning

confidence: 99%

Optimisation of solute transport in dialysers using a three-dimensional finite volume model

Eloot¹,

Vierendeels²,

Verdonck³

2006

Computer Methods in Biomechanics and Biomedical Engineering

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Dialyser manufacturers only provide limited information about mass removal under well-defined flow and solute conditions in commercially available dialysers for hemodialysis. This computational study aimed at assessing the solute transport efficiency in a dialyser for different geometries (fiber lengths and diameters). A three-dimensional finite volume model of a single fiber in a high flux polysulphone dialyser (Fresenius F60) was developed. Different equations describe blood and dialysate flow (Navier-Stokes), radial filtration flow (Darcy) and solute transport (convection-diffusion). Fluid and membrane properties were derived from in vitro and in vivo tests as well as from literature data. Urea (MW60) was used as marker to simulate small molecule removal, while middle molecule transport was modelled using vitamin B12 (MW1355) and inulin (MW5200). Keeping the fluid velocity in a single fiber constant, fiber diameter and length were changed in a wide range for evaluation of solute removal efficiency. Clearances were found enhanced by 13% (urea), 50% (vitamin B12) and 89% (inulin) for a fiber twice as long as a standard one and by 5.5% (vitamin B12) and 21% (inulin) for a fiber diameter of 150 mum instead of 200 mum. The impact of fiber dimensions was more pronounced for the middle molecules compared to urea.

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“…To validate the computational model, we compared hydrodynamic parameters (transmembrane pressure and filtration volume) with previous in vitro [10] and clinical observations. Solute transport parameters (extraction ratio, effluent/plasma ratio and clearance) were compared with the results of a previous study under similar treatment conditions [11].…”

Section: Methodsmentioning

confidence: 99%

Effects of Dialysate Flow Configurations in Continuous Renal Replacement Therapy on Solute Removal: Computational Modeling

Kim¹,

Cruz

Garzotto

et al. 2013

Blood Purif

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Background/Aims: Continuous renal replacement therapy (CRRT) is commonly used for critically ill patients with acute kidney injury. During treatment, a slow dialysate flow rate can be applied to enhance diffusive solute removal. However, due to the lack of the rationale of the dialysate flow configuration (countercurrent or concurrent to blood flow), in clinical practice, the connection settings of a hemodiafilter are done depending on nurse preference or at random. Methods: In this study, we investigated the effects of flow configurations in a hemodiafilter during continuous venovenous hemodialysis on solute removal and fluid transport using computational fluid dynamic modeling. We solved the momentum equation coupling solute transport to predict quantitative diffusion and convection phenomena in a simplified hemodiafilter model. Results: Computational modeling results showed superior solute removal (clearance of urea: 67.8 vs. 45.1 ml/min) and convection (filtration volume: 29.0 vs. 25.7 ml/min) performances for the countercurrent flow configuration. Countercurrent flow configuration enhances convection and diffusion compared to concurrent flow configuration by increasing filtration volume and equilibrium concentration in the proximal part of a hemodiafilter and backfiltration of pure dialysate in the distal part. In clinical practice, the countercurrent dialysate flow configuration of a hemodiafilter could increase solute removal in CRRT. Nevertheless, while this configuration may become mandatory for high-efficiency treatments, the impact of differences in solute removal observed in slow continuous therapies may be less important. Under these circumstances, if continuous therapies are prescribed, some of the advantages of the concurrent configuration in terms of simpler circuit layout and simpler machine design may overcome the advantages in terms of solute clearance. Conclusion: Different dialysate flow configurations influence solute clearance and change major solute removal mechanisms in the proximal and distal parts of a hemodiafilter. Advantages of each configuration should be balanced against the overall performance of the treatment and its simplicity in terms of treatment delivery and circuit handling procedures.

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Advanced modeling of highflux hemodialysis

Cited by 19 publications

References 6 publications

High performance thin-film nanofibrous composite hemodialysis membranes with efficient middle-molecule uremic toxin removal

High performance thin-film nanofibrous composite hemodialysis membranes with efficient middle-molecule uremic toxin removal

Optimisation of solute transport in dialysers using a three-dimensional finite volume model

Effects of Dialysate Flow Configurations in Continuous Renal Replacement Therapy on Solute Removal: Computational Modeling

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