Method and apparatus for determining the quantity of oremic toxins removed by a hemodialysis treatment

A method for carrying out a controlled partial dialysate collection during a dialysis treatment and carrying out a recirculating disinfection cycle separately from said dialysis treatment in a hemodialysis device including a switching valve arrangement with an inlet port, a drain outlet port and a sampling outlet port, an element selected from the group consisting of a dialyzer and a shunt conduit connected upstream of said inlet port, and a dialysate fluid inlet arrangement connected upstream of said element selected from the group consisting of a dialyzer and a shunt conduit,

• said method comprising
• during said dialysis treatment:
• flowing used dialysate into said inlet port, alternatingly switching said valve arrangement so that said dialysate flowing into said inlet port alternatingly flows out of said drain outlet port during at least one drain period and out of said sampling outlet port during at least one sampling period, and collecting as a dialysate sample said dialysate flowing out of said sampling outlet port;
• and
• during said disinfection cycle connecting said outlet port to said fluid inlet arrangement, flowing disinfecting medium into said inlet port of said valve arrangement, and switching said valve arrangement so that said disinfecting medium flowing into said inlet port flows out of said sampling outlet port and to said fluid inlet arrangement.

A method of operating a hemodialysis apparatus including a dialysate inlet arrangement, a valve arrangement having an inlet port, a drain outlet port and a sampling outlet port, at least one of a dialyzer and a shunt conduit connected between said dialysate inlet arrangement and said inlet port of said valve arrangement, a dialysate sample collecting container and a recirculation branch conduit selectively connecting said sampling outlet port for fluid flow to said dialysate inlet arrangement and to said dialysate sample collecting container, comprising the following steps:

• during a dialysis treatment:
• flowing dialysate from said inlet arrangement through said dialyzer and into said inlet port, and then alternately flowing a first portion of said dialysate out of said sampling outlet port and into said dialysate sample collecting container during at least one sampling period and flowing a second portion of said dialysate out of said drain outlet port during at least one drain period;
• and
• during a recirculating disinfection cycle:
• flowing a disinfecting medium through said at least one of said dialyzer and said shunt conduit, into said inlet port, out of said sampling outlet port, through said recirculation branch conduit and to said dialysate inlet arrangement.

A hemodialysis apparatus for partial dialysate collection during a dialysis treatment and for recirculation disinfection during a disinfecting cycle, comprising a dialysate inlet arrangement, a used dialysate conduit, at least one of a dialyzer and a shunt conduit interposed between said inlet arrangement and said used dialysate conduit, a dialysate sample collection container, a recirculation fluid flow branch selectively connecting said used dialysate conduit to said dialysate inlet arrangement and to said dialysate sample collecting container, a drain conduit selectively connected to said used dialysate conduit,

• first means interposed between said used dialysate conduit and said recirculation fluid flow branch and said drain conduit for selectively directing a first portion of used dialysate from said used dialysate conduit to said recirculation fluid flow branch and a second portion of said used dialysate from said used dialysate conduit to said drain conduit during said dialysis treatment and for directing a disinfecting medium from said used dialysate conduit to said recirculation fluid flow branch during said disinfecting cycle, and
• second means interposed in said recirculation fluid flow branch for directing said first portion of said used dialysate into said dialysate sample collection container during said dialysis treatment and for directing said disinfecting medium into said dialysate inlet arrangement during said disinfecting cycle.