Optimization of Na content of dialysis fluid.

The design of a dialysate recirculating llop permitted assessment of dialysate/blood Na+ dialysate concentration of 136.6 mEq/l (Donnan effect). Sodium and water removal using different Na+ dialysate concentrations have been assessed. With an Na+ dialysate concentration of 130 mEq/l plasma clearance of Na+ and H2O are equal, NNa/NH2O=128-142. Using a dialysate Na+ concentration of 162 mEq/l, NNa/NH2O=40-61, i.e., Na+ clearance is much lower than H2O clearance. The average patient requires removal of 2 liters H2O and 200 mEq Na+, i.e., NNa/NH2O=100. This corresponds to an Na+ dialysate concentration of 145 mEq/l. The incidence of hypotensive episodes during dialysis will be reduced if NNa/NH2O ratios (Na+ dialysate concentrations) are individualized for hemodialysis patients.