Method and apparatus for controlled ultrafiltration during hemodialysis

A method of hemodialytic ultrafiltration in a device utilizing a continuous loop dialysate flow path having a hemodialyzer, a first receptacle and a second receptacle comprising:

• supplying blood to and removing blood from said hemodialyzer;
• supplying fresh dialysate to said first receptacle and withdrawing spent dialysate from said second receptacle at substantially equivalent rates;
• withdrawing fresh dialysate at variable flow rates from said first receptacle and supplying same to said hemodialyzer;
• withdrawing spent dialysate, including any ultrafiltrate, at variable flow rates from said hemodialyzer and delivering same to said second receptacle;
• maintaining the dialysate levels in said receptacles at relatively constant, pre-determined levels;
• and
• withdrawing a controlled amount of dialysate from either of said receptacles to thereby effect a withdrawal of ultrafiltrate from the patient's blood into said flow path to substantially balance the amount of dialysate withdrawn therefrom.

A method of liquid infusion into a patient utilizing an apparatus with a dialysate flow path comprising a fluid-separation device with a liquid permeable membrane therein, a first receptacle and a second receptacle, said method comprising:

• supplying blood to and removing blood from said device;
• supplying fresh liquid to said first receptacle and withdrawing spent liquid from said second receptacle at substantially equivalent rates;
• withdrawing fresh liquid at variable flow rates from said first receptacle and supplying same to said device;
• withdrawing spent liquid at variable flow rates from said device and delivering same to said second receptacle;
• maintaining the liquid levels in said receptacles at relatively constant, pre-determined levels;
• and
• supplying a controlled amount of infusate to the fresh liquid upstream of said device to thereby effect an infusion of infusate into the patient's blood from said flow path.

An apparatus for controlling ultrafiltration during hemodialysis comprising a dialysate flow path having a fresh dialysate supply line for connection to a source of fresh dialysate and a spent dialysate removal line for connection to drain means, said flow path including, between said supply line and said removal line:

• a hemodialyzer for the dialysis and ultrafiltration of blood including inlet and outlet blood ports, an inlet dialysate port for the entry of fresh dialysate and an outlet dialysate port for the exit of spent dialysate;
• a dialysate reservoir connected to said supply line for the delivery of fresh dialysate thereinto;
• a first receptacle positioned in the flow path between said reservoir and the inlet dialysate port of said hemodialyzer;
• a first controlled flow rate pump for withdrawing fresh dialysate from said reservoir at a controlled rate and delivering same to said first receptacle;
• a first variable rate pump for withdrawing fresh dialysate from said first receptacle at a controlled rate and delivering same to said hemodialyzer;
• first sensing means for sensing the volume of fresh dialysate in said first receptacle and for controlling the flow rate of said first variable pump to maintain the volume of fresh dialysate therein at a relatively constant, pre-determined level;
• a second receptacle positioned in the flow path between said outlet dialysate port of said hemodialyzer and said removal line;
• a second variable rate pump for withdrawing spent dialysate, including any ultrafiltrate from said hemodialyzer at said controlled rate and delivering same to said second receptacle;
• second sensing means for sensing the volume of spent dialysate in said second receptacle and for controlling the flow rate of said second variable pump to maintain the volume of spent dialysate therein at a relatively constant, pre-determined level;
• a second controlled flow rate pump for withdrawing spent dialysate from said second receptacle at said controlled rate and delivering same to said removal line;
• and
• an ultrafiltrate removal pump positioned in the flow path between the output side of said first controlled flow rate pump and the intake side of said second controlled flow rate pump for withdrawing a controlled amount of dialysate from the dialysate flow path between and including of said receptacles to thereby cause said first and second variable rate pumps to respectively change flow rates to seek the equilibrium of said pre-determined levels and exert a zero negative pressure, relative to patient blood pressure, in the dialysate section of said hemodialyzer to effect a withdrawal of ultrafiltrate from the patient's blood into said dialysate flow path to substantially balance the amount of dialysate withdrawn therefrom.

Hemodialysis ultrafiltration apparatus comprising a dialysate flow path including:

• a hemodialyzer;
• means for supplying blood to and removing blood from said hemodialyzer;
• a first receptacle;
• a second receptacle;
• first means for supplying fresh dialysate to said first receptacle and for withdrawing spent dialysate from said second receptacle at substantially equivalent and fixed rates;
• second means for variably withdrawing fresh dialysate from said first receptacle and supplying same to said hemodialyzer and for variably withdrawing spent dialysate, including any ultrafiltrate, from said hemodialyzer and delivering same to said second receptacle;
• control means associated with said receptacles and said first and said second means for maintaining the dialysate levels in said receptacles at relatively constant, pre-determined levels;
• and
• ultrafiltrate removal means for withdrawing a controlled amount of dialysate from the dialysate flow path between and including said receptacles to thereby effect a withdrawal of ultrafiltrate from the patient's blood into said flow path to substantially balance the amount of dialysate withdrawn therefrom.

Liquid infusion apparatus comprising a liquid flow path including:

• a flow-separation device with a liquid permeable membrane therein;
• means for supplying blood to and removing blood from said device;
• a first receptacle;
• a second receptacle;
• first means for supplying fresh liquid to said first receptacle and for withdrawing spent liquid from said second receptacle at substantially equivalent and fixed rates;
• second means for variably withdrawing fresh liquid from said first receptacle and supplying same to said device and for variably withdrawing spent liquid from said device and delivering same to said second receptacle;
• control means associated with said receptacles and said first and said second means for maintaining the liquid levels in said receptacles at relatively constant, pre-determined levels;
• and
• infusate delivery means for supplying a controlled amount of infusate to the fresh liquid upstream of said device to thereby effect an infusion of infusate into the patient's blood from said flow path.