Sodium fluxes during hemodialysis.

Abstract

Three sets of experiments were performed to determine the effect of the dialysate sodium concentration on the sodium balance of patients undergoing maintenance hemodialysis. First, patients were treated with three different dialysate bath sodium concentrations: 125-132 mEq/l (n = 7), 135-140 mEq/l (n = 11) and 145-150 mEq/l (n = 6). We demonstrated that the pretreatment plasma sodium concentration was independent of the sodium concentration of the dialysate used. Second, the plasma sodium concentration available for diffusion during the treatment was calculated from the plasma sodium concentration and the plasma proteins. The accuracy of this calculation was demonstrated by comparing the predicted value with the concentration of sodium measured in an ultrafiltrate obtained at minimal filtration fraction. Third, the sodium fluxes using a hypernatremic or hyponatremic dialysate were calculated for 100 ml of plasma going through the dialyzer. At steady state, no significant differences in net sodium fluxes were demonstrated between hyper- and hyponatremic dialysis.