0
views
0
recommends
+1 Recommend
1 collections
    0
    shares
      • Record: found
      • Abstract: found
      • Article: found

      A Kinetic Model of Inorganic Phosphorus Mass Balance in Hemodialysis Therapy

      Read this article at

      ScienceOpenPublisherPubMed
      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          Background: There is growing evidence that inorganic phosphorus (iP) accumulation in tissues (dTiP/dt) is a risk factor for cardiac death in hemodialysis therapy (HD). The factors controlling iP mass balance in HD are dietary intake (GiP), removal by binders (JbiP) and removal by dialysis (JdiP). If iP accumulation is to be minimized, it will be necessary to regularly monitor and optimize GiP, JbiP and JdiP in individual patients. We have developed a kinetic model (iPKM) designed to monitor these three parameters of iP mass balance in individual patients and report here preliminary evaluation of the model in 23 HD patients. Methods: GiP was calculated from PCR measured with urea kinetics; JdiP was calculated from the product of dialyzer plasma water clearance (K<sub>pwiP</sub>) and time average plasma iP concentration (TACiP) and treatment time (t); a new iP concentration parameter (nTAC<sub>iP</sub>, the TACiP normalized to predialysis CoiP) was devised and shown to be a highly predictable function of the form nTAC<sub>iP</sub> = 1 – α(1 – exp[–βK<sub>pwiP</sub>· t/ViP]), where the coefficients α and β are calculated for each patient from 2 measure values for nTAC<sub>iP</sub>, K<sub>pwiP</sub>·t/ViP early and late in dialysis; we measured 8–10 serial values for nTAC<sub>iP</sub>, K<sub>pwiP</sub>· t/ViP over a single dialysis in 23 patients; the expression derived for iP mass balance is ΔTiP = 12(PCR) – [K<sub>pwiP</sub>(t) (N/7)][CoiP(1 – α(1 – exp[–β(Kt/ViP)]))] – k<sub>b</sub>·Nb. Results: Calculated nTAC<sub>iP</sub> = 1.01(measured nTAC<sub>iP</sub>), r = 0.98, n = 213; calculated JdiP = 0.66(measured total dialysate iP) + 358, n = 23, r = 0.88, p < 0.001. Evaluation of 10 daily HD patients (DD) and 13 3 times weekly patients with the model predicted the number of binders required very well and showed that the much higher binder requirement observed in these DD patients was due to much higher NPCR (1.3 vs. 0.96). Conclusion: These results are very encouraging that it may be possible to monitor the individual effects of diet, dialysis and binders in HD and thus optimize these parameters of iP mass balance and reduce phosphate accumulation in tissues.

          Related collections

          Most cited references 1

          • Record: found
          • Abstract: found
          • Article: not found

          Phosphate kinetics during hemodialysis: Evidence for biphasic regulation.

          Hyperphosphatemia in the hemodialysis population is ubiquitous, but phosphate kinetics during hemodialysis is poorly understood. Twenty-nine hemodialysis patients each received one long and one short dialysis, equivalent in terms of urea clearance. Phosphate concentrations were measured during each treatment and for one hour thereafter. A new model of phosphate kinetics was developed and implemented in VisSim. This model characterized additional processes involved in phosphate kinetics explaining the departure of the measured data from a standard two-pool model. Pre-dialysis phosphate concentrations were similar in long and short dialysis groups. Post-dialysis phosphate concentrations in long dialysis were higher than in short dialysis (P < 0.02) despite removal of a greater mass of phosphate (P < 0.001). In both long and short dialysis serum phosphate concentrations initially fell in accordance with two-pool kinetics, but thereafter plateaued or increased despite continuing phosphate removal. Implementation of an additional regulatory mechanism such that a third pool liberates phosphate to maintain an intrinsic target concentration (1.18 +/- 0.06 mmol/L; 95% confidence intervals, CI) explained the data in 24% of treatments. The further addition of a fourth pool hysteresis element triggered by critically low phosphate levels (0.80 +/- 0.07 mmol/L, CI) yielded an excellent correlation with the observed data in the remaining 76% of treatments (cumulative standard deviation 0.027 +/- 0.004 mmol/L, CI). The critically low concentration correlated with pre-dialysis phosphate levels (r=0.67, P < 0.0001). Modeling of phosphate kinetics during hemodialysis implies regulation involving up to four phosphate pools. The accuracy of this model suggests that the proposed mechanisms have physiological validity.
            Bookmark

            Author and article information

            Journal
            BPU
            Blood Purif
            10.1159/issn.0253-5068
            Blood Purification
            S. Karger AG
            978-3-8055-7535-5
            978-3-318-00939-2
            0253-5068
            1421-9735
            2003
            2003
            22 January 2003
            : 21
            : 1
            : 51-57
            Affiliations
            aRenal Research Institute, New York, N.Y., bClinical Research Laboratory, Fresenius Medical Care, Walnut Creek, Calif., cResearch Service Department of Veterans Affairs, Northern California Health Care System, Mather, Calif., and Division of Nephrology, University of California, Davis, Calif., USA
            Article
            67866 Blood Purif 2003;21:51–57
            10.1159/000067866
            12566662
            © 2003 S. Karger AG, Basel

            Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher. Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug. Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.

            Page count
            Figures: 6, Tables: 1, References: 13, Pages: 7
            Product
            Self URI (application/pdf): https://www.karger.com/Article/Pdf/67866
            Categories
            Paper

            Comments

            Comment on this article