A diffusion-adjusted regional blood flow model to predict solute kinetics during haemodialysis

Objective.To provide an exact solution for variable-volume multicompartment kinetic models with linear volume change, and to apply this solution to a 4-compartment diffusion-adjusted regional blood flow model for both urea and creatinine kinetics in hemodialysis.Methods.A matrix-based approach applicable to linear models encompassing any number of compartments is presented. The procedure requires the inversion of a square matrix and the computation of its eigenvaluesλ, assuming they are all distinct. This novel approach bypasses the evaluation of the definite integral to solve the inhomogeneous ordinary differential equation.Results.For urea two out of four eigenvalues describing the changes of concentrations in time are about 105times larger than the other eigenvalues indicating that the 4-compartment model essentially reduces to the 2-compartment regional blood flow model. In case of creatinine, however, the distribution of eigenvalues is more balanced (a factor of 102between the largest and the smallest eigenvalue) indicating that all four compartments contribute to creatinine kinetics in hemodialysis.Interpretation.Apart from providing an exact analytic solution for practical applications such as the identification of relevant model and treatment parameters, the matrix-based approach reveals characteristic details on model symmetry and complexity for different solutes.

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Cardiac output and urea kinetics in dialysis patients: Evidence supporting the regional blood flow model

Kidney International ◽

10.1038/ki.1996.438 ◽

1996 ◽

Vol 50 (4) ◽

pp. 1273-1277 ◽

Cited By ~ 22

Author(s):

Titiola O. George ◽

Adrian Priester-Coary ◽

George Dunea ◽

Daniel Schneditz ◽

Nauman Tarif ◽

...

Keyword(s):

Blood Flow ◽

Cardiac Output ◽

Flow Model ◽

Regional Blood Flow ◽

Dialysis Patients ◽

Urea Kinetics ◽

Blood Flow Model

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Dosing intermittent haemodialysis in the intensive care unit patient with acute renal failure--estimation of urea removal and evidence for the regional blood flow model

Nephrology Dialysis Transplantation ◽

10.1093/ndt/gfm938 ◽

2008 ◽

Vol 23 (7) ◽

pp. 2286-2298 ◽

Cited By ~ 11

Author(s):

N. S. Kanagasundaram ◽

T. Greene ◽

A. B. Larive ◽

J. T. Daugirdas ◽

T. A. Depner ◽

...

Keyword(s):

Intensive Care Unit ◽

Renal Failure ◽

Blood Flow ◽

Acute Renal Failure ◽

Intensive Care ◽

Intensive Care Unit Patient ◽

Flow Model ◽

Regional Blood Flow ◽

Intermittent Haemodialysis ◽

Blood Flow Model

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110 Patient-Specific Cerebral Regional Blood Flow Model Using Quantitative Magnetic Resonance Angiography to Predict Stump Pressure

Neurosurgery ◽

10.1093/neuros/nyy303.110 ◽

2018 ◽

Vol 65 (CN_suppl_1) ◽

pp. 83-84

Author(s):

Daniel Li ◽

Meide Zhao ◽

Sepideh Amin-Hanjani ◽

Robert Kufahl ◽

Xinjian Du ◽

...

Keyword(s):

Blood Flow ◽

Magnetic Resonance ◽

Magnetic Resonance Angiography ◽

Flow Model ◽

Regional Blood Flow ◽

Patient Specific ◽

Quantitative Magnetic Resonance ◽

Stump Pressure ◽

Blood Flow Model

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Is intercompartmental urea clearance during hemodialysis a perfusion term? A comparison of two pool urea kinetic models.

Journal of the American Society of Nephrology ◽

10.1681/asn.v651360 ◽

1995 ◽

Vol 6 (5) ◽

pp. 1360-1370

Author(s):

D Schneditz ◽

B Fariyike ◽

R Osheroff ◽

N W Levin

Keyword(s):

Blood Flow ◽

Cell Membrane ◽

Membrane Permeability ◽

Flow Model ◽

Regional Blood Flow ◽

The Body ◽

Membrane Model ◽

Cell Membrane Permeability ◽

Cell Membrane Model ◽

Blood Flow Model

Analyses of intradialytic and postdialytic urea profiles call for models that consider delayed urea transfer from different parts of the body to the blood. There are two different approaches to the problem. In the classical cell membrane model it is assumed that the two compartments refer to the serial (s) arrangement of extracellular and intracellular volumes, whereas in the regional blood flow model the two compartments are identified as parallel (p) organ systems with high or low perfusion. In the cell membrane model, delayed urea removal from peripheral body compartments is governed by intercompartmental clearance (Kc) which is a function of cell membrane permeability, whereas in the regional blood flow model delayed urea removal is related to low perfusion (QL) of the large muscle/skin/bone compartment. Both models were compared in a set of 16 high-efficiency hemodialysis treatments. Modeled volumes (Vm,s = 31.2 +/- 9.5 L; Vm,p = 30.0 +/- 8.3 L) and modeled dose of hemodialysis (Kt/Vm,s = Kt/Vm,p = 1.12 +/- 0.33) were the same for both models. However, volumes modeled by either technique were significantly lower than anthropometric volumes (V alpha = 35.0 +/- 6.4 L). These data suggest that at this point the two models are experimentally indistinguishable. Moreover, the main system parameters of both models, Kc (0.54 +/- 0.16 L/min) and QL (0.63 +/- 0.15 L/min) showed a strong linear dependence (QL = 0.921 Kc + 0.139, r2 = 0.884), whereas no relation could be found between Kc and Vm. Therefore, delayed transport that has up to now been characterized by membrane permeability may also be explained by peripheral perfusion.

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