Is Na+ modeling necessary in high flux dialysis?

One important pathogenic factor in dialysis hypotension is the drop in plasma osmolality. Increasing the dialysate Na+ concentration decreases hypotensive episodes. The authors studied 39 patients being treated with high flux dialysis. During a 9 week period, the patients were on a standard Na+ dialysate (Na+ = 140 meq/L) basal period (B); 9% (Na+ = 149 meq/L) linear (L); step drop (S); and exponential drop (E). The Na+ program was changed weekly at random. The results obtained with the three Na+ modeling programs were similar. We compared the periods with and without Na+ modeling: no differences were found in weight gained interdialysis, mean blood pressure predialysis and postdialysis, and hemoconcentration. Serum Na+ levels were significantly higher predialysis and postdialysis for those patients on Na+ modeling. Hypotensive episodes and cramps decreased 50% with Na+ modeling. The amount of hypertonic and normal saline given during dialysis was markedly reduced. Na+ modeling should always be used in patients being maintained on high flux dialysis.