Phosphate dialytic removal: enhancement of phosphate cellular clearance by biofiltration (with acetate-free buffer dialysate).

Phosphate dialytic removal (PDR) depends in part on the type (acetate or bicarbonate) and the concentration of the buffer dialysate. Plasma phosphate reduction or PDR during a dialysis treatment is the algebraic sum, of phosphate cellular flux (removal or captation) and of phosphate tissular precipitation. High bicarbonate levels induce an intracellular shift of phosphate, thus not available for dialytic removal. On the contrary, acidosis prevents P shifting into the intracellular space, thus more P is available for dialytic removal. In order to evaluate cellular phosphate sequestration (CPS) we tested PDR in a crossover study. Three children were dialyzed (18 sessions) successively using either biofiltration with free buffer dialysate and a constant bicarbonate fluid infusion rate (BF) or using sequential biofiltration (SBF) with an initial controlled acidosis period realized by bicarbonate reinjection fluid rate modelling. PDR was higher in SBF (32 +/- 4 mmol/session) than in BF (24 +/- 6 mmol/session). SBF seemed to be efficient against CPS; it clearly demonstrates that bicarbonate modelling is a promising dialytic approach to enhance PDR. The real clinical relevance of these biological results needs clinical long-term evaluation.