Concurrent Control of Sodium and Bicarbonate Serum Concentrations Using a Four-Stream Hemodialysis Fluid Delivery System

Background: Previously, two reports proposed a four-stream dialysis fluid delivery system consisting of an acid concentrate, a base concentrate, a sodium chloride concentrate, and product water for correcting dysnatremias and metabolic acid-base disorders separately, by hemodialysis. Methods: This report describes a new method for the clinical use of the previously reported four-stream dialysis fluid delivery system to treat concurrently dysnatremias and metabolic acid-base disturbances by hemodialysis. Pumps attached to each concentrate are designed to control its flow rate. Formulas were derived to determine the flow rate of each of the pumps controlling the flows of the product water (W), the base concentrate (B), and the sodium chloride concentrate (S) for any prescribed combination of sodium and bicarbonate concentrations is the final dialysis fluid. In this scheme, the flow rate of the acid concentrate (A), the concentrations of its contents in the final dialysis fluid remain constant. The flow rate ratio W:S:B:A remains also constant at 45 (i.e., 45X). Results: The formulas were entered in an EXCEL flow sheet which determines the flow rate ratio W:S:B:A for any desired combination of sodium and bicarbonate concentrations in the dialysis fluid. The upper and lower limits of the concentrations of sodium and bicarbonate in the dialysis fluid were computed. The system has not been applied clinically. Measurements of any electrolyte concentrations have not been made. Discussion: This system makes the treatment of profound dysnatremias, metabolic acid-base disorders, and combined dysnatremias and metabolic acid-base disorders feasible. The clinical application of the system demands prior in vitro or ex vivo studies plus fastidious and expert attention to ensure safe and dependable application.