Clinical Validation of a Predictive Modeling Equation for Sodium

Abstract

Changes in plasma sodium (Na) concentration during hemodialysis were predicted by changes in Na concentration of the dialysate at equilibrium with the plasma, according to the formula C't = CD - (CD - C'0) [(V0 - QFt)/V0]A/QF, where C'0 and C't are the Na concentration of the dialysate at equilibrium with the plasma at times 0 and t, respectively; QF is the ultrafiltration flow rate; V0 is the initial total body water; and CD is the Na dialysate concentration. This modeling involves only one parameter, A, which is the effective sodium dialysance and depends on the dialyzer, the QF, the plasma water flow rate, and the actual Donnan coefficient. Parameter A was evaluated after 1 h of dialysis. Seven routine 4-h dialysis sessions were performed in which the Na concentration of dialysate at equilibrium with the plasma was measured at varying times. The mean (+/- SEM) difference between predicted and measured values was delta C = 0.5 +/- 0.2 mmol/L. These data support the validity of the model that allows the monitoring of Na dialysate concentration to obtain a prescribed Na plasma concentration at the end of a dialysis session.

Dialysate sodium management in hemodialysis and online hemodiafiltration: The single‐pool kinetic model revisited

“…The single-pool kinetic model was first developed from the sodium-fluid balance. 3,27,28 As shown in the Appendix (equations [a26]-[a28]), this single-pool model requires the following three assumptions: (1) the pool of cellular sodium does not vary; (2) the pool of all osmotically active cellular solutes as a whole does not vary; and (3) natremia is proportional to tonicity.…”

Quenching the Thirst in Dialysis Patients

“…The various nonpsychogenic dipsogenic fac tors include hypernatraemia, progressive rise in urea, ele vated angiotensin II levels and probably oropharyngeal factors [9], Treatment strategies that have been tried to ameliorate the interdialytic symptoms include sequential change in dialysate sodium concentration, sequential UF, hypertonic dialysate with increased sodium content and recently sodium modeling [10]. Sodium modeling is a pro grammed means of varying the dialysate concentration during treatment [11], The study clearly demonstrates that progressive reduction of dialysate sodium by linear sodium modeling from 137 to 128 mEq/1. when used with a computerized UF program, allows adequate UF with absolute haemodynamic stability, alleviates intradialytic complications and ameliorates interdialytic thirst.…”

Estimation of Mass Transfer Through a Hemodialyzer: Theoretical Approach and Clinical Applications

“…1f of Appendix 1 can be written for a period of duration t : where c 0 and c t are the plasma water sodium concentrations at the beginning and at the end of the period, respectively, and where V 0 is the value of total body water at the beginning of the period. Equation 22 allows for the calculation of the adequate dialysate sodium concentration for reaching, at the end of the session, the value c t of natremia fixed by the physician (13).…”