Estimation of absolute blood volume in hemodialysis patients: A numerical algorithm for assessing blood volume increase after dialysate bolus infusion

Leszek Pstras, Simon Krenn, Jacek Waniewski, Michael Schmiedecker, Sebastian Mussnig, Janosch Niknam, Peter Wabel, Christopher Clemens Mayer, Daniel Schneditz, Manfred Hecking

Research output: Contribution to journalArticlepeer-review

Abstract

Objective
A feasible method has recently been proposed for estimating absolute blood volume (ABV) in hemodialysis (HD) patients based on intradialytic infusion of a dialysate bolus and visual assessment of the subsequent increase in relative blood volume (RBV) tracked by the dialysis machine. The aim of this study was to develop a method for more objective determination of such RBV increase to improve the accuracy of ABV estimation.

Methods
We proposed a numerical algorithm consisting of interpolation and polynomial fitting of RBV signals, which we evaluated on data from 64 HD sessions in 48 patients with 240 mL of dialysate infused approximately 1 h into HD. The estimated ABV values were compared with those from a simple two-point method described previously as well as with the values calculated using the Nadler formula and the Lemmens-Bernstein-Brodsky formula.

Results
Compared to the simple method, the improved method provided higher (more plausible) estimates of ABV (median 4.79 vs 4.53 L, p < 0.001) and specific ABV (median 68.5 vs 66.4 mL/kg, p < 0.001). The improved method also provided much lower intra-patient variability of ABV estimated in different sessions of the same week (median spread 180 vs 462 mL, p < 0.001) and showed narrower limits of agreement with both Nadler and Lemmens-Bernstein-Brodsky formulae.

Conclusion
The proposed numerical method constitutes a substantial improvement over the simple method by averaging the noise and short-term variability in RBV signals.

Significance
More accurate estimates of ABV in HD patients could aid in managing their fluid status.
Original languageEnglish
Article number105440
Pages (from-to)1-9
Number of pages9
JournalBiomedical Signal Processing and Control
Volume88
Issue numberPart A
Early online date10 Oct 2023
DOIs
Publication statusPublished - Feb 2024

Research Field

  • Medical Signal Analysis

Keywords

  • Absolute blood volume
  • Fluid status
  • Hemodilution
  • Relative blood volume
  • Ultrafiltration

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