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Kidney Week

Abstract: TH-PO246

New Approach for Intradialytic Estimation of Absolute Blood Volume During Ultrafiltration

Session Information

Category: Dialysis

  • 801 Dialysis: Hemodialysis and Frequent Dialysis


  • Abohtyra, Rammah M., The University of Texas Permian Basin, Odessa, Texas, United States
  • Schneditz, Daniel, Medizinische Universitat Graz, Graz, Steiermark, Austria
  • Vincent, Tyrone, Colorado School of Mines, Golden, Colorado, United States

Managing blood and fluid volumes in chronic kidney disease (CKD) patients plays an essential role in dialysis therapy to replace kidney function. The study aims to develop an estimation approach to provide predictable information on blood and fluid volumes during a regular dialysis routine.


The method utilizes a nonlinear fluid volume model, a mathematical optimization technique, and the Unscented Kalman Filter (UKF). The method relies on anthropometric patient information (pre-dialysis weight, assumed dry weight), bounded parameter assumptions, and actual, on-line treatment information (UF-rate and hematocrit (H) or related measures of hemoconcentration). The method does not require a specific UF-rate or volume infusion protocols. Data collected were used where UF was varied to examine intravascular volume dynamics.


The method was applied to 20 data sets of ten patients and provided comparable results compared to a previous method. Average blood volumes of 5.3±0.55L, plasma volumes of 4.1±0.64L, interstitial fluid volumes of 17.3±3.3L, and red blood cell volumes of 1.2±0.14L were estimated. We show that by implementing the estimated parameters, the measured H can be precisely predicted.


The method is comparable with a previous method and uses a short data segment for estimation.

Figure 1. Predicted H trajectories (red lines) for measured profiles (black circles) during 20 treatments for 10 patients.

Modeled vs actual H measurements (black circles) with UF rates; estimated blood volume (Vb) estimations.


  • Government Support – Non-U.S.