OPTIMIZED CONVECTIVE VOLUME IN ONLINE HEMODIAFILTRATION

Authors

  • František Lopot General University Hospital, Department of Medicine, Prague-Strahov & 1st Medical Faculty, Institute of biophysics and medical informatics, Charles University, Prague https://orcid.org/0000-0001-9955-0261
  • Vratislav Fabián Faculty of Electrical Engineering, Department of Physics, Czech Technical University in Prague, Czech Republic https://orcid.org/0000-0002-6390-0116

DOI:

https://doi.org/10.14311/CTJ.2020.3.01

Abstract

Hemodiafiltration (HDF) adds convective elimination of middle molecules (MM), proportional to filtered volume (Vconv) on the top of diffusion-based elimination of small molecules (SM) by conventional hemodialysis (HD). Studies, both observational and randomized controlled ones, performed so far generally indicated positive impact of higher Vconv on all-cause mortality in HDF patients, although the magnitude of Vconv at which HDF becomes apparently superior to HD differed widely among the studies. Also the issue of a suitable anthropometric parameter by which the Vconv should be normalized has not yet been solved. Data from the ESHOL study seems to indicate that patient´s body surface area (BSA) could well be used for this—mortality was decreasing with increasing Vconv/BSA with a bottom plateau starting at about 15 L/m2. We have therefore devised a formula and a graph for determination of Vconv which fulfils the requirement Vconv/BSA= 15. Assuming maximum feasible and safe filtration fraction QF/QB= 0.3, the Vconv actually defines the necessary blood flow (QB) to reach Vconv/BSA= 15 as QB=15·BSA/(0.3·t) (t – session time). It is also possible to check what QB is needed in terms of sufficient diffusion-based transport (target Kt/V) and compare both QB values to see if adequate combined elimination of both SM and MM can be achieved at the same time and under what conditions, respectively.         

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Published

2020-09-30

Issue

Section

Original Research