Prescribing Dialysate Sodium in Maintenance Hemodialysis Patients: What Can Conductivity Monitoring Contribute?

Sodium management during hemodialysis session is based on the dialysate sodium (Na_D) prescription by the physician. However, the conflicting results of studies concerning the relationship between Na_D and mortality, and the sometimes significant difference between the Na_D prescribed and its actual value, are barriers to issuing on the optimal Na_D value. In the absence of any rational justification for preferring high or low dialysate sodium, prescribing Na_D remains empirical and quite intuitive.

From a clinical perspective, several arguments suggest prescribing the change in natremia (ΔNa) to be achieved at the end of the dialysis session rather than the Na_D value. Conductivity monitoring allows to calculate an online estimate (Na_Cond) of natremia and makes the hemodialysis monitor able to automatically adjust Na_D to achieve a Na_Cond target. From a technical standpoint, prescribing a Na_Cond-change target (ΔNa_Cond) rather than a Na_Cond target has the major advantage that the ΔNa_Cond value obtained at the end of the session may be unaffected by any lack of accuracy in the Na_D value. Key-Messages: Prescribing a target change (ΔNa) in natremia appears to be more rational and clinically relevant than prescribing a dialysate sodium. Conductivity monitoring makes it easier to implement this prescription in everyday clinical practice.