Sodium transport with different dialysis ultrafiltration schedules using a bio-feedback module (BFB).

rationale for sodium transport with diVerent dialysis dialysate diVerence, is computed continuously during the schedules, we assume that the removal of the amount session [33]. The ‘apparent plasma conductivity’ has been of sodium and water equal to that loaded during the shown to indicate the concentration of sodium participating intersession can be considered the target of adequate in the transport [33]. Sodium mass transfer is then calculated treatment. Clinical experience, moreover, shows that as: TmNa=(Qd+Qf◊CDFout◊10.3)‐(Qd◊CDin ◊10.3), this target is generally associated with good cardiovas- where: Qd=dialysate flow rate (ml/min), Qf=ultrafiltration cular stability [15‐18]. Several dialysis schedules have flow rate (ml/min), CDFout=outlet dialysate conductivity used sodium modelling and profiling of dialysate (mS/cm), CDin=inlet dialysate conductivity (mS/cm) and sodium concentration to achieve this goal. Modelling 10.3 is the ratio between sodium concentration and conductand profiling take into account the interaction between ivity in the bicarbonate dialysate. In ‘automatic BFB mode’, once the final target is prescribed changes in convection and diVusion (short dialysis, for PC, the BFB computer defines first, at the beginning of high ultrafitration flow rate, high surface area of the session, an intermediate target, to be reached threemembranes, etc.) [19‐27]. In routine clinical work, quarters way through the session, which is 10% higher than however, during the session, they cannot be easily the PC prescribed for the end of the session (PCf ). The matched with sodium plasma concentration, or with dialysate concentration is then increased to reach the interthe eVective dialysance or the actual ultrafiltration flow mediate target, then decreased to the final PCf. The pathway rate. A new dialysis module (bio-feedback, BFB), designed at the beginning of the session for dialysate changes recently designed by Hospal RD, allows monitoring of is then validated by actual measurements of ultrafiltration electrolyte transport, assessed from continuous meas- flow rate, dialysance and PC. Computing is based on a urements of conductivity and dialysance; it can calcu- single-pool modelling program [23,40]. Moreover, dialysate conductivity is also matched with ultrafiltration flow rate late plasma sodium concentration from dialysate