Automated diaphragm apparatus and method for controlling negative pressure hemodialysis treatment

• US 4,366,061 A
• Filed: 10/31/1980
• Issued: 12/28/1982
• Est. Priority Date: 01/23/1980
• Status: Expired due to Term

• Current Assignee: Cordis Dow Corp.
• Original Assignee: Cordis Dow Corp.
• Inventors: Landau, Julian I., Egler, Mark S., Papanek, Thomas H.
• Primary Examiner(s): SPEAR JR, FRANK
• Application Number:
  US06/203,075
• Time in Patent Office: 788 Days
• Field of Search: 210/85, 210/87, 210/96.2, 210/416.1, 210/321.3, 210/647, 210/188
• US Class Current: 210/647
• CPC Class Codes: A61M 1/16 with membranes
• CPC Class Codes: A61M 1/1601 Control or regulation
• CPC Class Codes: A61M 1/1615 using measurements made at different flow rates
• CPC Class Codes: A61M 1/1639 linked by membranes
• CPC Class Codes: A61M 1/165 with a dialyser bypass on the dialysis fluid line
• CPC Class Codes: A61M 2205/3331 Pressure; Flow
• CPC Class Codes: A61M 2205/3334 Measuring or controlling the flow rate
• CPC Class Codes: Y10S 210/929 Hemoultrafiltrate volume measurement or control processes

Abstract

This invention provides an automated single pass dialysate supply apparatus and a method for conducting hemodialysis treatments when the apparatus is used. The apparatus is of the closed circuit type and provides a pair of cylinders, each equipped with a hydraulically driven diaphragm, which supply fresh dialysate to and remove spent dialysate from an artificial kidney on an alternating time basis; the improvement resides in the means which sense the difference in time of arrival of the end of stroke of each diaphragm and automatically counteract these differences to either maintain or restore synchronization of the instant of end of stroke of each diaphragm in each half cycle of operation.

The hemodialysis treatment method permits operator presetting of the desired ultrafiltrate removal rate and insures maintenance of that preset rate throughout the hemodialysis treatment period.

Claims

1. An automated single pass negative pressure dialysate hemodialysis treatment circuit for automatically controlling hemodialyzer and dialysate operating parameters in response to operator set ultrafiltrate withdrawal rate comprising:

a hemodialyzer separated by a semipermeable membrane into a blood side and a dialysate side having inlet and outlet ports for removing water and impurities from the blood;

a first dialysate cylinder having hydraulically driven means separating said cylinder into two chambers as said means moves between the ends of said cylinder connected to a fresh/drain circuit for filling one of said chambers via a dialysate supply line with fresh dialysate as spent dialysate is removed from the other of said chambers to drain via a drain line and alternately connected to a kidney/spent circuit for filling one of said chambers with spent dialysate via a kidney spent dialysate removal line as fresh dialysate is removed from the other of said chambers and supplied to the inlet port of said kidney via a kidney dialysate supply line;

a second dialysate cylinder having hydraulically driven means separating said cylinder into two chambers as said means moves between the ends of said cylinder connected to said kidney/spent circuit during the time said first cylinder is connected to said fresh/drain circuit and alternately connected to said fresh/drain circuit during the time said first cylinder is connected to said kidney/spent circuit;

valve switching means associated with said first and said second cylinders connecting said cylinders alternately with one of said fresh/drain and said kidney/spent circuits;

dialysate flow control means connected into said kidney spent dialysate removal line intermediate said kidney dialysate outlet port and said valve switching means for controlling the rate of spent dialysate flow in said kidney spent dialysate removal line,

a degasifier connected into said kidney spent dialysate removal line intermediate said pump and said valve switching means in said kidney/spent circuit;

ultrafiltrate removal means connected into an above atmospheric portion of said circuit intermediate said valve switching means and means in said kidney dialysate supply line and means in said spent dialysate removal line which preserve said above atmospheric pressure in said above atmospheric circuit portion, and means for setting the rate of withdrawal of ultrafiltrate from said portion of said circuit;

sensing means for sensing the end of stroke of said hydraulically driven means in each of said first and said second cylinders and for converting said sensed instant into an electrical signal;

means for causing said valve switching means to simultaneously switch all valves controlling flow into and from each of said first and said second cylinders at the instant of arrival of the end of stroke of the second of said hydraulically driven means in said first and said second cylinders for alternating the existing connection of each of said cylinders with one of said fresh/drain and said kidney/spent circuits;

detecting means operatively connected to said electrical signal of said end of stroke sensing means for detecting the time difference between the instant of each said end of stroke of each of said hydraulically driven means and for converting said time difference into a flow rate electrical signal for supply to said pump means for altering the flow rate of said spent dialysate in said kidney spent dialysate removal line,

flow rate signal generator means for supplying to said pump means said flow rate signal at the delayed instant of the end of the succeeding half cycle of traverse to the same end of stroke from which the said detected time difference first occurred for causing said pump to adjust the rate of dialysate flow in said kidney spent dialysate removal line to thereby achieve synchronization of the instant of end of stroke of each of said hydraulically driven means in said cylinders.

2. An automated hemodialysis treatment circuit in accordance with claim 1 wherein said hemodialyzer is a hollow fiber artificial kidney.

3. An automated hemodialysis treatment circuit in accordance with claim 1 wherein said circuit includes pressure sensing means in said spent dialysate removal line intermediate said pump and said outlet hemodialyzer port for sensing pressure changes in spent dialysate in said kidney/spent dialysate removal line and for converting said pressure change into an electrical signal for supply to said pump means to re-establish the rate of dialysate flow through said pump means at the instant prior to said detected change in said pressure.

4. An automated hemodialysis treatment circuit in accordance with claim 1 wherein said circuit includes a first sensing means consisting of a flow switch intermediate said fresh dialysate source and said valve switching means in said fresh dialysate supply line, and a second sensing means consisting of a flow switch in said kidney/spent circuit intermediate said pump and said valve switching means in said spent dialysate removal line.

5. An automated hemodialysis treatment circuit in accordance with claim 4 wherein said circuit includes pump means in said fresh/drain circuit intermediate said fresh dialysate source and upstream of said valve switching means in said fresh dialysate supply line.

6. An automated hemodialysis treatment circuit in accordance with claim 1 wherein said hydraulically driven means is a diaphragm.

7. A process for conducting a hemodialysis treatment by employing a hemodialyzer in a closed hydraulic circuit including dialysate delivery means arranged such that operator presetting of the rate of withdrawal of ultrafiltrate from said circuit induces automatically those operating parameters in the circuit which produce water removal from the blood so as to insure maintenance of the rate of water separation across the semipermeable membrane to enable continuous withdrawal of ultrafiltrate at the preset withdrawal rate comprising the steps of:

providing a closed hydraulic circuit including a first and second cylinder unit, each having hydraulically driven means separating each said cylinder into two chambers as said means moves between the ends of said cylinder,

a hemodialyzer separated by a semipermeable membrane into a blood side and a dialysate side having an inlet port and an outlet port,

switching means operatively connecting one of said units with said hemodialyzer and the other said unit with a fresh dialysate supply source on an alternating time basis such that one chamber in said first cylinder unit fills with fresh dialysates as spent dialysate is expelled from the other chamber in said unit to drain, and during that same time interval the other of said units is connected to said hemodialyzer such that one chamber in said second cylinder unit fills with spent dialysate as fresh dialysate is expelled from the other chamber in said unit to the inlet port of said hemodialyzer and said functions alternate after simultaneous valve switching occurs, fresh dialysate supply line means in said hydraulic circuit for supplying bubble-free fresh dialysate and spent dialysate line means for removing gas bubbles from said spent dialysate before said degasified spent dialysate enters a chamber in one of said first and said second cylinder unit,

and presettable means in said circuit interconnecting said hemodialyzer with one of said first and said second cylinder units for withdrawing ultrafiltrate therefrom, sensing the end of stroke of each said hydraulically driven means in each of said first and said second cylinder,

switching all valves controlling flow into and from each of said first and said second cylinders simultaneously at the instant of latest arrival of the end of stroke of said hydraulically driven means in said first and said second cylinders to thereby alternate connection between each of said cylinders and one of said fresh/drain and said kidney/spent circuits, detecting the time difference between the instant of each end of stroke of each of said hydraulically driven means,

converting said detected time difference into a flow rate electrical signal,

supplying said flow rate electrical signal to pump means located in said spent dialysate line at the delayed instant of the end of the succeeding half cycle of traverse to the same end of stroke location from which the said detected time difference first occurred, and repeating said time difference detection between the instant of said end of strokes of said hydraulically driven means in each said cylinder in subsequent cycles and after conversion of said time difference into flow control signals again supplying said signals to said pump means at similarly delayed instants in time for a sufficient number of half cycles to achieve synchronization of the instant of end of stroke of each of said hydraulically driven means in said cylinders.

8. A process in accordance with claim 7 wherein pressure changes in said spent dialysate in said spent dialysate removal line intermediate said pump and said outlet hemodialyzer port are sensed and converted into electrical signals and supplied to said pump means on a repetitive, continuous basis to thereby re-establish the rate of dialysate flow through said pump means at the instant prior to said sensed change in said pressure.