Evaluation of Intradialytic Solute and Fluid Kinetics

Abstract

A mathematical model of solute kinetics for the improvement of hemodialysis treatment is presented. It includes a two-compartment description of the main solutes and a three-compartment model of body fluids (plasma, interstitial and intracellular). The main model parameters can be individually assigned a priori, on the basis of body weight and plasma concentration values measured before beginning the session. Model predictions are compared with clinical data obtained in vivo during 11 different hemodialysis sessions performed on 6 patients with a profiled sodium concentration in the dialysate and a profiled ultrafiltration rate. In all cases, the agreement between the time pattern of model solute concentrations in plasma and the in vivo data proves fairly good as to urea, sodium, chloride, potassium and bicarbonate kinetics. Only in two sessions was blood volume directly measured in the patient, and in both cases the agreement with model predictions was good. In conclusion, the model allows a priori computation of the amount of sodium removed during hemodialysis, and makes it possible to predict the plasma volume changes and plasma osmolarity changes induced by a given sodium concentration profile in the dialysate and by a given ultrafiltration profile. Hence, it can be used to improve clinical tolerance to the dialysis session taking the characteristics of individual patients into account, in order to minimize intradialytic hypotension.

Effect of a plasma sodium biofeedback system applied to HFR on the intradialytic cardiovascular stability. Results from a randomized controlled study

“…In the last 20 years, the mathematical modelling of sodium kinetics has been developed and validated in many studies [10–14]. Even if nowadays there are technological premises to simplify the daily use of profiling, their routine application is still scarce.…”

“…Colì et al developed a new mathematical model of sodium profiling, named ‘Profiler’, in order to predict the intradialytic sodium removal [10–13]. The model takes into account blood flow, pre-dialysis plasma sodium (Na + ) and urea concentration, creating coupled ultrafiltration and sodium conductivity profiles in order to achieve the planned weight loss (WL) and reach the desired target post-dialysis plasma sodium concentration.…”

Sodium Prescription in the Prevention of Intradialytic Hypotension: New Insights into an Old Concept

“…The Profiler was successfully validated in experiments and proved to give accurate descriptions of solute kinetics during the dialysis session, maintaining the strategy to increase the ECV/ICV ratio [31]. Considering that there are osmotic sodium and non-osmotic body sodium stores, the Profiler mathematical model was revised and the intracellular sodium compartment was included in the model with a detailed description of interstitial elastance and interstitial fluid pressure [32,33]. The model forecasts the sodium mass balance during the 4-h dialysis.…”

Mathematical Modeling of Cardiovascular System Dynamics Using a Lumped Parameter Method

“…For example, some models assume that the microcirculation is a resistor [24,33] whose value is nearly 1 PRU, and others use a multibranched approximation for the microcirculation [31,32]. The microcirculation is especially important in hemodialysis simulation [45][46][47] and microgravity modeling of the circulation [23,48].…”

“…By contrast, Heldt et al [23] In the hemodialysis simulations using a lumped model done by Ursino's group [45][46][47], mass transfer in the blood-tissue-dialysate system was simulated with a model having three compartments: intracellular, interstitial, and plasma compartments. Fluid exchange between the intracellular and interstitial compartments depends on the osmotic concentration, whereas the hydraulic and osmotic pressure gradients at the capillary compartment determine fluid exchange between the interstitial fluid and plasma.…”