Hemodialysis system having a flow path with a controlled compliant volume

Abstract

Systems and methods for the performance of kidney replacement therapy having or using a dialyzer, control components, sorbent cartridge and fluid reservoirs configured to be of a weight and size suitable to be worn or carried by an individual requiring treatment are disclosed. The system for performing kidney replacement therapy has a controlled compliance dialysis circuit, where a control pump controls the bi-directional movement of fluid across a dialysis membrane. The dialysis circuit and an extracorporeal circuit for circulating blood are in fluid communication through the dialysis membrane. The flux of fluid moving between the extracorporeal circuit and the dialysis circuit is modified by the rate at which the control pump is operating such that a rate of ultrafiltration and convective clearance can be controlled. The system provides for the monitoring of an inlet and outlet conductivity of the sorbent cartridge to provide a facility to quantify or monitor the removal of urea by the sorbent cartridge.

1 - 17 . (canceled) 
     
     
         18 . A method comprising:
 conveying blood from a subject through an extracorporeal circuit and a dialyzer and returning the blood to the subject;   conveying a dialysate through a dialysis circuit such that the dialysate moves from a sorbent cartridge, to the dialyzer and back to the sorbent cartridge, where at least one waste species diffuses from the blood to the dialysate through the dialysis membrane and the sorbent cartridge substantially removes at least one impurity or waste species from the dialysate; and   wherein the dialysate is conveyed through a microbial filter prior to entering the dialyzer.   
     
     
         19 . The method of  claim 18 , wherein the dialysate is conveyed through the microbial filter after the dialysate is conveyed through the sorbent cartridge. 
     
     
         20 . The method of  claim 18 , further comprising one or more of:
 a) using a pump to add a cation solution to the dialysate; and   b) using a pump to add a bicarbonate solution to the dialysate;   
       wherein the cation solution or bicarbonate solution is added to the dialysate prior to conveying the dialysate through the microbial filter. 
     
     
         21 . The method of  claim 20 , further comprising using an ultrafiltrate pump to move fluid between the dialysis circuit and the extracorporeal circuit, wherein a flux of fluid moving between the dialysis circuit and the extracorporeal circuit is changed by the rate at which the ultrafiltrate pump is operated. 
     
     
         22 . The method of  claim 21 , wherein the ultrafiltrate pump is a control pump, and further comprising operating the ultrafiltrate pump to add fluid from a control reservoir to the dialysis circuit in an influx direction via a conduit or operating the ultrafiltrate pump to remove fluid from the dialysis circuit to the control reservoir in an efflux direction via the conduit, and intermittently switching the ultrafiltrate pump between the efflux direction to move fluid across the dialysis membrane from the extracorporeal circuit to the dialysis circuit and the influx direction to move fluid across the dialysis membrane from the dialysis circuit to the extracorporeal circuit.