pH AND BUFFER MANAGEMENT SYSTEM FOR HEMODIALYSIS SYSTEMS

Abstract

Systems and methods for managing the pH of a dialysate fluid during hemodialysis therapy. The systems and methods adjust dialysate pH and buffer concentration to generate a predetermined total bicarbonate buffer concentration in a dialysate entering a dialyzer.

1 . A system for infusing a buffer into a dialysate, comprising:
 a dialysate flow loop for circulating a dialysate through a dialyzer, wherein acid or base equivalents are added to the dialysate during operation of the dialysate flow loop;   a urea sensor that measures or allows for the calculation of urea content of the dialysate in at least one portion of the dialysate flow loop;   an infusate system configured to add a bicarbonate buffer component or unbuffered sodium bicarbonate to the dialysate; and   a controller for controlling an amount of the bicarbonate buffer component or unbuffered sodium bicarbonate for addition to the dialysate to generate a predetermined total bicarbonate buffer concentration in the dialysate entering the dialyzer.   
     
     
         2 . The system of  claim 1 , wherein the system further comprises a dialysate regeneration unit, the dialysate regeneration unit for removing a waste species from the dialysate. 
     
     
         3 . The system of  claim 2 , wherein the dialysate regeneration unit contains urease for converting urea to ammonium carbonate. 
     
     
         4 . The system of  claim 2 , wherein the dialysate regeneration unit modifies the total bicarbonate buffer concentration of the dialysate entering the dialysate regeneration unit or modifies the pH of the dialysate entering the dialysate regeneration unit. 
     
     
         5 . The system of  claim 4 , wherein the dialysate exiting the dialysate regeneration unit comprises a concentration of bicarbonate buffer that is less than the predetermined total bicarbonate buffer concentration. 
     
     
         6 . The system of  claim 1 , wherein the controller determines the total bicarbonate buffer concentration of the dialysate in a first portion of the dialysate flow loop based at least in part upon a urea concentration of the dialysate in a second portion of the dialysate flow loop. 
     
     
         7 . The system of  claim 1 , wherein the controller controls a pH of the dialysate in a first portion of the dialysate flow loop based at least in part upon a urea concentration of the dialysate in a second portion of the dialysate flow loop. 
     
     
         8 . The system of  claim 6 , wherein the system further comprises a dialysate regeneration unit, the dialysate regeneration unit for removing a waste species from the dialysate and releasing a bicarbonate buffer component, unbuffered sodium bicarbonate, carbon dioxide or combinations thereof to the dialysate. 
     
     
         9 . The system of  claim 6 , wherein the second portion of the dialysate flow loop is between an outlet of the dialyzer and an inlet of the dialysate regeneration unit and the first portion of the dialysate flow loop is between an outlet of the dialysate regeneration unit and an inlet of the dialyzer. 
     
     
         10 . The system of  claim 6 , wherein the controller determines a total buffer concentration in the first portion of the dialysate flow loop and operates the infusate system at a rate to add a bicarbonate buffer component or unbuffered sodium bicarbonate to the dialysate to generate dialysate having the predetermined total bicarbonate buffer concentration. 
     
     
         11 . The system of  claim 1 , further comprising a pH-buffer sensor for determining a bicarbonate ion concentration and a pH of the dialysate in at least one point of the dialysate flow loop. 
     
     
         12 . The system of  claim 11 , wherein information from the pH-buffer sensor is used to determine the amount of bicarbonate buffer component or unbuffered sodium bicarbonate added by the infusate system. 
     
     
         13 . A system for modifying a pH of a dialysate, comprising:
 a dialysate flow loop for circulating a dialysate through a dialyzer, wherein acid or base equivalents are added to the dialysate during operation of the dialysate flow loop;   a pH-buffer management system for adding or generating a pH-buffer modifying solution to the dialysate, wherein the pH-buffer management solution has a different pH from the dialysate; and   a controller for calculating an amount of the pH-buffer modifying solution for addition to the dialysate to adjust the dialysate to be of a predetermined pH and bicarbonate buffer concentration.   
     
     
         14 . The system of  claim 13 , wherein the controller determines the pH and bicarbonate buffer concentration of a dialysate in a first portion of the dialysate flow loop based at least in part upon a urea content of the dialysate in a second portion of the dialysate flow loop. 
     
     
         15 . The system of  claim 13 , further comprising a urea sensor that measures or allows for the calculation of urea content of the dialysate in at least one portion of the dialysate flow loop. 
     
     
         16 . The system of  claim 13 , wherein the dialysate comprises a bicarbonate buffer component or unbuffered sodium bicarbonate. 
     
     
         17 . The system of  claim 14 , wherein the pH-buffer management system generates the pH-buffer modifying solution from a feed solution, and the pH-buffer management system does not substantially modify the total bicarbonate buffer concentration of the feed solution. 
     
     
         18 . The system of  claim 11 , wherein the pH-buffer management system comprises a bipolar electrodialysis system. 
     
     
         19 . The system of  claim 18 , wherein the bipolar electrodialysis system comprises an anode, a cathode, a first flow channel and a second flow channel, and a feed solution flowing through the first flow channel generates the pH-buffer modifying solution. 
     
     
         20 . The system of  claim 19 , further comprising a cation exchange membrane interposed between the first flow channel and the second flow channel, a first bipolar membrane interposed between the first flow channel and the anode and a second bipolar membrane interposed between the second flow channel and the cathode, wherein the first and second bipolar membranes comprise a cation exchange membrane and an anion exchange membrane. 
     
     
         21 . The system of  claim 20 , wherein the cation exchange membrane of the first bipolar membrane is oriented toward the first flow channel and an anion exchange membrane of the second bipolar membrane is oriented toward the second flow channel. 
     
     
         22 . The system of  claim 19 , wherein a base concentrate is generated from a fluid flowing through the second flow channel during operation of the bipolar electrodialysis system. 
     
     
         23 . The system of  claim 22 , wherein the base concentrate is circulated through the second flow channel using a base concentrate reservoir and a base concentrate pump. 
     
     
         24 . The system of  claim 13 , wherein the pH-buffer management system comprises a pump to deliver an acid solution as the pH-buffer modifying solution with the proviso that the acid solution does not comprise a substantial amount of a bicarbonate buffer component or an unbuffered sodium bicarbonate. 
     
     
         25 . The system of  claim 24 , wherein the acid solution comprises hydrochloric acid, phosphoric acid, acetic acid or citric acid. 
     
     
         26 . The system of  claim 1 , wherein the system is controlled compliant. 
     
     
         27 . The system of  claim 1 , wherein the system selectively meters fluid into and out of the dialysate flow loop. 
     
     
         28 . The system of  claim 1 , wherein the system selectively meters fluid into and out of the dialysate flow loop using any one of a control pump, a water pump, a salination pump, an acid concentrate pump, a replacement fluid pump, and combinations thereof. 
     
     
         29 . The system of  claim 1 , wherein the system provides for bi-directional flow. 
     
     
         30 . The system of  claim 13 , wherein the system is controlled compliant. 
     
     
         31 . The system of  claim 13 , wherein the system selectively meters fluid into and out of the dialysate flow loop. 
     
     
         32 . The system of  claim 13 , wherein the system selectively meters fluid into and out of the dialysate flow loop using any one of a control pump, a water pump, a salination pump, an acid concentrate pump, a replacement fluid pump, and combinations thereof. 
     
     
         33 . The system of  claim 13 , wherein the system provides for bi-directional flow.