[Electrolyte balance and acid-base equilibrium in high ultrafiltration hemodiafiltration]

Electrolyte and acid-base balance was evaluated in 14 high UF (124 +/- 7 ml/min) hemodiafiltration sessions. The dialysate contained (in mEq/l): Na 138-140, K 2-3, Ca 3.5, Mg 0.5-0.7, Cl 106-110, acetate 38 or acetate 3 and bicarbonate 35-38. The fluid, infused in postdilutional mode, was 23.5 +/- 21 per session (session length 203 +/- 22 minuti), 80% containing Na 138, K 2, Ca 3.5, Mg 1, Cl 109.5, acetate 35 and 20% Na 145, HCO3 100, Cl 45. The balance was: negative for Na (-255 +/- 220 mEq), for K (-74 +/- 22 mEq) and for Mg (-166 +/- 141 mg), positive for Ca (215 +/- 147 mg) and for acetate (590 +/- 15 and 966 +/- 412 mmol); the electrolytes and bicarbonate plasma values were within of close to normal limits during the session. An unphysiological feature was the positive balance of acetate which, though, was metabolized during the interdialytic period as to return to normal predialytic values. Therefore, in high UF HDF, the above combination of dialysate and reinfusate allows a reasonable electrolyte and acid-base balance; however, bicarbonate should be the only buffer in order to avoid unphysiological levels of other buffers in the biological fluids.