title: A novel mathematical method based on urea kinetic modeling for computing the dialysis dose.
abstract: A novel normalized single pool urea kinetic model (nspUKM) for the quantification of the urea removal, dialyzer urea clearance and urea generation rate during a dialysis session, is presented. Its major goal is the computation of an accurate estimate of the fractional dialyzer urea clearance (dKt/V), which is denoted nKt/V, in contrast to the equilibrated Kt/V (eKt/V). This work clarifies the significance of dKt/V as a complement to eKt/V in hemodialysis (HD) prescription and quantification. This new model emerges from a generalization of the standard single pool urea kinetic model (spUKM) of the US National Cooperative Dialysis Study (NCDS), identified as gspUKM. Due to their significance, the standard single pool Kt/V (spKt/V) and the eKt/V are also analyzed from gspUKM in this work, with the aim of achieving a better interpretation of the results. Indices nKt/V, eKt/V and spKt/V have been compared with the dKt/V computed from a published and validated two-pool urea kinetic model (2pUKM). We present the results obtained from a clinical study carried out on a group of 30 end stage renal disease (ESRD) patients. The limits of agreement (mean+/-2S.D. (standard deviation) of the difference) between nKt/V and 2pKt/V were -0.077+/-0.72% (percentage of the dKt/V mean), while between eKt/V and 2pKt/V were -13.75+/-17.39% and between spKt/V and 2pKt/V were -1.61+/-6.54%. These scores prove that the nspUKM model is able to provide a very accurate estimate of 2pKt/V and thus dKt/V, even with high flux (HF) HD. The presented method joins the simplicity of single-pool models to the accuracy of double-pool models, when the target is the identification of the dialyzer urea clearance, urea removal and urea generation rate, although it does not provide a good prediction of the urea dynamics. Finally, we think that our analytical and experimental findings throw light on the behavior and applicability of the different Kt/V indices analyzed.
authors.affiliation: Biomedical Engineering Group, Escuela Superior de Ingenieros, Universidad de Sevilla, Camino de los Descubrimientos s/n, 41092 Seville, Spain. mprado@supercable.es
authors.forename: Manuel
authors.initials: M
authors.lastname: Prado
authors.forename: Laura
authors.initials: L
authors.lastname: Roa
authors.forename: Alfonso
authors.initials: A
authors.lastname: Palma
authors.forename: José Antonio
authors.initials: JA
authors.lastname: Milán
mesh_terms: D001806:Blood Urea Nitrogen; D006801:Humans; D007676:Kidney Failure, Chronic / Q000628:therapy*; D007700:Kinetics; D006435:Renal Dialysis; D014508:Urea / Q000302:isolation & purification*
chemical_list: D014508:Urea