Effects of Dialysate Flow Configurations in Continuous Renal Replacement Therapy on Solute Removal: Computational Modeling
Open Access
- 22 January 2013
- journal article
- Published by S. Karger AG in Blood Purification
- Vol. 35 (1-3), 106-111
- https://doi.org/10.1159/000346093
Abstract
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.Keywords
This publication has 15 references indexed in Scilit:
- Evaluation of a New Polysulfone Hemofilter for Continuous Renal Replacement TherapyBlood Purification, 2011
- Effluent Volume in Continuous Renal Replacement Therapy Overestimates the Delivered Dose of DialysisClinical Journal of the American Society of Nephrology, 2011
- Understanding the linear correlation between diffusion coefficient and molecular weight. A model to estimate diffusion coefficients in acetonitrile solutionsElectrochemistry Communications, 2011
- Analysis of the mass transfers in an artificial kidney microchipJournal of Membrane Science, 2010
- Innovation in the Treatment of Uremia: Proceedings from the Cleveland Clinic Workshop: Blood–Membrane Interactions During DialysisSeminars in Dialysis, 2009
- Delivered dose of renal replacement therapy and mortality in critically ill patients with acute kidney injuryCritical Care, 2009
- Advanced modeling of highflux hemodialysisJournal of Membrane Science, 2003
- Air embolism during cardiopulmonary bypassPerfusion, 1995
- Effect of the Direction of Dialysate Flow on the Efficiency of Continuous Arteriovenous HaemodialysisBlood Purification, 1990
- Estimation of diffusion coefficients of proteinsBiotechnology & Bioengineering, 1980