Dialysate sodium delivery can alter chronic blood pressure management

Low dialysate sodium concentrations can reduce postdialysis thirst and serum sodium activity, but patients typically experience dialysis hypotension, fatigue, disequilibrium, and cramps. "High-sodium" hemodialysis minimizes dialysis disequilibrium but increases the serum sodium activity of most patients. Programmed "variable-sodium" dialysis can minimize dialysis discomfort but may also alter the sodium kinetics from those of "high-sodium" dialysis. We designed a cross-over study with random order assignment to determine whether a "variable-sodium" dialysis program could reduce the blood pressure of dialysis patients without increasing dialysis morbidity. Dialysis with a dialysate sodium of 140 mEq/L was compared with dialysis with a programmed exponential decrease of dialysate sodium from 155 mEq/L to 135 mEq/L. Dialysate sodium was then held constant at 135 mEq/L for the final half hour of dialysis. Eighteen patients completed the 7-month study, each receiving 3.5 months of experimental and 3.5 months of standard therapy. Programmed "variable-sodium" dialysis resulted in a reduction in antihypertensive drug use without alterations in predialysis blood pressure, interdialytic weight gain, ultrafiltration tolerance, or the frequency of symptomatic dialysis cramps or hypotension. Patients did, however, have lower postdialysis standing blood pressures and higher postdialysis target weights during programmed "variable-sodium" dialysis.