Hemodialysis apparatus with degassing means for the dialysis solution

• US 4,530,759 A
• Filed: 05/21/1984
• Issued: 07/23/1985
• Est. Priority Date: 09/02/1978
• Status: Expired due to Fees

• Current Assignee: Fresenius AG (Fresenius SE & Co. KGaA)
• Original Assignee: Fresenius AG (Fresenius SE & Co. KGaA)
• Inventors: Schal, Wilfried
• Primary Examiner(s): Sadowski, David
• Application Number:
  US06/613,005
• Time in Patent Office: 428 Days
• Field of Search: 210/96.2, 210/97, 210/104, 210/109, 210/137, 210/149, 210/181, 210/188, 210/195.2, 210/257.2, 210/258, 210/321, 210/416, 210/433.2, 210/927, 210/929, 137/99, 417/26, 417/45
• US Class Current: 210/104
• CPC Class Codes: A61M 1/16 with membranes
• CPC Class Codes: A61M 1/1607 before use, i.e. upstream of dialyser
• CPC Class Codes: A61M 1/1609 after use, i.e. downstream of dialyser
• CPC Class Codes: A61M 1/1639 linked by membranes
• CPC Class Codes: A61M 1/1692 Detection of blood traces in dialysate
• CPC Class Codes: A61M 2205/3331 Pressure; Flow
• CPC Class Codes: A61M 2205/3368 Temperature
• CPC Class Codes: A61M 2205/3379 Masses, volumes, levels of fluids in reservoirs, flow rates
• CPC Class Codes: A61M 2205/50 with microprocessors or computers
• CPC Class Codes: A61M 2205/705 Testing of filters for leaks blood in dialysate A61M1/1692
• CPC Class Codes: Y10S 210/929 Hemoultrafiltrate volume measurement or control processes

Abstract

The ultra-filtration in a hemodialysis operation is controlled by a control apparatus which is connected to a balancing device (1) and to a dosing device (9) to form a closed loop control circuit for the metered supply of dialysis concentrate into the balancing device and for the metered supply of fresh dialysis solution into the dialyzer. The closed loop control circuit controls the alternating supply of fresh dialysis solution into one chamber of a balancing device and the withdrawal of used-up dialysis solution from the other chamber of the balancing device. The closed loop control circuit also controls a pump for the metered withdrawal of used-up dialysis solution out of the dialysis circulatory system. The dosing device operates as a proportionality device to produce fresh dialysis solution from water and dialysis concentrate whereby the concentrate is dosed and the dialysis solution is also dosed or metered.

Claims

1. In a hemodialysis apparatus, wherein fresh dialysis solution is supplied to a dialyzer (4) by fresh dialysis solution supply means (50, 51, 52, 53) and spent dialysis solution is removed from the dialyzer (4) by a withdrawal device (67), the improvement comprising reduced pressure closed loop circuit balancing means (22, 23) for balancing a batch of fresh dialysis solution against an equal batch of spent dialysis solution, valve and conduit means operatively connecting said supply means to said balancing means and said withdrawal device to said dialyzer and to said balancing means for supplying batches of fresh dialysis solution through the balancing means to the dialyzer while discharging corresponding batches of spent dialysis solution from the dialyzer through the balancing means, first degassing means (100) operatively interposed between said supply means and said balancing means for degassing said fresh dialysis solution, second degassing means (47) operatively interposed between said dialyzer and said balancing means for degassing spent dialysis solution supplied to said balancing means so that only batches of degassed fresh dialysis solution and of degassed spent dialysis solution are balanced relative to each other, further conduit means (68) operatively interconnecting said first (100) and second (47) degassing means, and suction pump means (54) operatively connected in said further conduit means (68) for causing a further reduced pressure in said further conduit means (68), said further reduced pressure being larger than said first mentioned reduced pressure for drawing air separated from said spent dialysis solution in said second degassing means (47) through said further conduit means (68).

2. The apparatus of claim 1, wherein said first degassing means for the degassing of fresh dialysis solution comprise a recirculating path for a repeated degassing of fresh dialysis solution, said recirculating path comprising said pump means (54) having a suction inlet and a pressure outlet, gas separator means (56) operatively connected with an inlet to the pressure outlet of said pump means (54), pressure maintaining valve means (61) connected to one side thereof to a fresh dialysis solution outlet of said gas separator means (56), and flow impedance means (55) operatively connected in series between said pressure maintaining valve means in a throughflow direction and to the suction inlet of said pump means (54) for connecting the fresh dialysis solution outlet of said gas separator means (56) to the suction inlet of said pump means (54), supply conduit means (50) for feeding not yet degassed, fresh dialysis solution into the supply means, said supply conduit means (50) being operatively connected to a junction between said pressure maintaining valve means (61) and said flow impedance means (55), further supply conduit means operatively connected to said pressure maintaining valve means (61), said flow impedance means (55) providing a flow impedance value such that at the suction inlet of said pump means (54) a negative pressure is maintained, said pressure maintaining valve means (61) providing in said further supply conduit means a positive pressure relative to atmospheric pressure, whereby fresh dialysis solution is recirculated through said pressure maintaining valve means (61) in a closed loop flow circuit during pauses between charging work strokes of said balancing means (22, 23) for an effective degassing of fresh dialysis solution.

3. The apparatus of claim 2, wherein said gas separator means (56) define a gas discharge opening at a top portion thereof for discharging gas (at 57) out of said gas separator means (56), and wherein said fresh dialysis solution outlet of said gas separator means (56) is located at a bottom portion of said gas generator means (56) for transporting fresh dialysis solution from said fresh dialysis solution outlet to said balancing means.

4. The apparatus of claim 2, wherein said pressure maintaining valve means (61) comprise non-return valve means providing a one-way flow path toward the suction inlet of said pump means (54).

5. The apparatus of claim 2, wherein said gas separator means (56) comprise level sensor means for controlling a gas outlet.

6. The apparatus of claim 1, wherein said second degassing means (47) comprise controllable valve means (48) in said further conduit means (68), and float valve control means (49) in said second degassing means operatively connected to said controllable valve means (48) for connecting said further conduit means and the reduced pressure in said further conduit means (68) to said second degassing means (47) in response to a filling level in said second degassing means (47).

7. The apparatus of claim 1, further comprising heater means (58) operatively interposed between said first degassing means (100) and said balancing means for heating degassed fresh dialysis solution.

8. In a hemodialysis apparatus wherein fresh dialysis solution is supplied to a dialyzer (4) by fresh dialysis solution supply means and spent dialysis solution is removed from the dialyzer by a withdrawal device, the improvement comprising closed circuit balancing means (22, 23) for balancing a batch of fresh dialysis solution against an equal batch of spent dialysis solution;

valve means including valve control means and conduit means operatively connecting, said supply means to inlets of said balancing means, outlets of said balancing means to an inlet of said dialyzer, and said withdrawal device to an outlet of said dialyzer and to further inlets of said balancing means, for supplying batches of fresh dialysis solution through the balancing means to the dialyzer while discharging corresponding batches of spent dialysis solution from the dialyzer through the balancing means; and

degassing means (47) operatively interposed between said dialyzer and said balancing means for degassing spent dialysis solution before a batch of spent dialysis solution is returned to said balancing means for balancing against a corresponding batch of fresh dialysis solution, said apparatus further comprising pump means (67) operatively interposed between said degassing means (47) and said balancing means, a motor means (90) for said pump means (67) and sensor means (91,

     74) for sensing operation of said motor means, and wherein said balancing means comprise means defining two volumes and two flexible membranes, one membrane in each volume, separating each respective volume into two chambers, said sensor means sensing an end position of said flexible membranes resting against a chamber wall by deriving a switch-over signal from a supply circuit (91) connected to said motor means (90) for switching over said valve control means when a sharp rise in motor current occurs as a result of one of said flexible membranes reaching an end position.

9. The apparatus of claim 8, further comprising level sensor means (49) in said degassing means (47) for producing a control signal.

10. A hemodialysis apparatus for withdrawing ultrafiltrate from a dialyzer, comprising balancing means including means defining two balancing chambers (22, 23), a displaceable element (24, 25) in each chamber dividing each respective chamber into two volumes thereby, defining four volumes (22a, 22b;

23a, 23b), namely one volume in each chamber for fresh dialysis solution and one volume in each chamber for used dialysis solution, each volume having an inlet duct and an outlet duct and a valve (14, 15, 16, 17, 18, 19, 20,

     21) in each of said ducts, pump means (67) including pump motor means (90) for driving said pump means, said pump means being operatively connected to those of said ducts cooperating with said volumes for used dialysis solution, fresh dialysis solution supply means operatively connected to those of said ducts cooperating with said volumes for fresh dialysis solution, a pump motor current supply circuit including sensor means operatively connected to said pump motor means (90) for sensing pump motor current in response to a respective displaceable element (24,

     25) reaching an end position in a respective chamber whereby pump motor current rises, said sensor means including a threshold value switch means for producing a switch-over signal (74), said apparatus further comprising valve control circuit means operatively connected to said valves for controlling operation of said valves, said valve control circuit means having an input (74'"'"') operatively connected to receive said switch-over signal (74) from said threshold value switch means for controlling operation of said valves (14 to

     21).

11. The apparatus of claim 10, wherein said sensor means comprise a resistor in said motor current supply circuit.

12. The apparatus of claim 10, wherein said pump means are operatively connected to said inlet ducts of said volumes for used dialysis solution.