Isonatric dialysis biofeedback in hemodiafiltration with online regeneration of ultrafiltrate (HFR): rationale and study protocol for a randomized controlled study.

Dialysate sodium prescription has major implications for hemodialysis tolerance but also for dialyzed patients' cardiovascular morbidity as a determinant factor of blood pressure. Biofeedback systems have been developed to drive dialysate conductivity in order to reach a prescribed serum sodium concentration, indirectly evaluated by a dialysate or an ultrafiltrate conductivity measurement. A biofeedback system using hemodiafiltration with online regeneration of ultrafiltrate (HFR) has been specially developed with an isonatric mode maintaining an equal serum sodium concentration between start and end of the dialysis session, combined with ultrafiltration and conductivity profiles. We hypothesized that using this biofeedback in an isonatric mode would have a beneficial effect on blood pressure and dialysis tolerance. The study protocol has been approved by our ethics committee and is presented herein.