Combined hemofiltration and hemodialysis system

• US 5,114,580 A
• Filed: 06/20/1990
• Issued: 05/19/1992
• Est. Priority Date: 06/20/1989
• Status: Expired due to Term

• Current Assignee: Board of Regents of The University of Washington (University of Washington)
• Original Assignee: Board of Regents of The University of Washington (University of Washington)
• Inventors: Cole, James J., Ahmad, Suhail, Jensen, William
• Primary Examiner(s): Jones, W. Gary
• Application Number:
  US07/540,747
• Time in Patent Office: 699 Days
• Field of Search: 210/85, 210/86, 210/94, 210/98, 210/103, 210/143, 210/188, 210/195.2, 210/205, 210/206, 210/257.2, 210/321.65, 210/321.71-321.9, 210/416.1-416.5 , 210/417, 210/929, 210/646, 210/651, 210/739, 210/805, 210/806, 210/137, 210/321.6, 604/4-6, 604/250-255, 417/20, 417/470-475
• US Class Current: 210/646
• CPC Class Codes: A61M 1/1666 by dissolving solids
• CPC Class Codes: A61M 1/168 Sterilisation or cleaning before or after use
• CPC Class Codes: A61M 1/1682 both machine and membrane module, i.e. also the module blood side
• CPC Class Codes: A61M 1/1684 Checking the module characteristics before reuse
• CPC Class Codes: A61M 1/169 using chemical substances
• CPC Class Codes: A61M 1/30 Single needle dialysis ; Reciprocating systems, alternately withdrawing blood from and returning it to the patient, e.g. single-lumen-needle dialysis or single needle systems for hemofiltration or pheresis
• CPC Class Codes: A61M 1/302 having a reservoir for withdrawn untreated blood
• CPC Class Codes: A61M 1/303 having a reservoir for treated blood to be returned
• CPC Class Codes: A61M 1/306 Pressure control, e.g. using substantially rigid closed or gas buffered or elastic reservoirs
• CPC Class Codes: A61M 1/3417 using distinct filters for dialysis and ultra-filtration
• CPC Class Codes: A61M 1/3427 back through the membrane, e.g. by inverted trans-membrane pressure [TMP]
• CPC Class Codes: A61M 1/3437 downstream of the filter, e.g. post-dilution with filtrate
• CPC Class Codes: A61M 1/3643 Priming, rinsing before or after use
• CPC Class Codes: A61M 1/3644 Mode of operation
• CPC Class Codes: A61M 1/3646 Expelling the residual body fluid after use, e.g. back to the body
• CPC Class Codes: A61M 1/3649 using dialysate as priming or rinsing liquid
• CPC Class Codes: A61M 1/365 through membranes, e.g. by inverted trans-membrane pressure [TMP]
• CPC Class Codes: A61M 2205/705 Testing of filters for leaks blood in dialysate A61M1/1692
• CPC Class Codes: A61M 2205/707 Testing of filters for clogging
• CPC Class Codes: A61M 60/113 in other functional devices, e.g. dialysers or heart-lung machines
• CPC Class Codes: A61M 60/279 : Peristaltic pumps, e.g. roller pumps
• CPC Class Codes: A61M 60/37 : Haemodialysis, haemofiltration or diafiltration
• CPC Class Codes: A61M 60/446 : the axis of both movements being parallel, e.g. roller screw actuators or cylindrical cam transmissions
• CPC Class Codes: A61M 60/554 : of blood pressure
• CPC Class Codes: A61M 60/851 : Valves
• CPC Class Codes: A61M 60/892 : Active valves, i.e. actuated by an external force
• CPC Class Codes: A61M 60/894 : Passive valves, i.e. valves actuated by the blood
• CPC Class Codes: Y10S 210/929 : Hemoultrafiltrate volume measurement or control processes

Abstract

A hemodialysis system has a blood circuit and a hemofiltrate circuit interconnected at a hemofilter and an air collection chamber. If an infusion of sterile fluid to the returning blood is needed during the dialysis treatment, filtrate in the filtrate circuit is pumped back into the blood circuit. This is also done to purge the blood circuit of blood and return it to the patient at the conclusiion of a dialysis treatment. A blood pump in the blood circuit incorporates a flexible vessel in conjunction with pinch valves which self expand in a controlled manner from a compressed condition to fill with blood from the patient in a suction stroke controlled by the patient'"'"'s blood delivery rate. Compression of the vessel by an external member then forces the blood through the rest of the blood circuit.

Claims

1. A hemodialysis system comprising:

a blood pump having a blood outlet and a blood inlet for connection to a patient via an arterial route;

a hemofilter having a blood inlet connected to said blood outlet of the pump, and having a blood outlet and a filtrate outlet;

a hemodialyzer having a blood outlet, a blood inlet connected to said blood outlet of the hemofilter, and a dialysate inlet and outlet;

a filtrate reservoir;

an air-removal and filtrate pump having an outlet connected to said reservoir and having an inlet;

an air collection chamber having a blood inlet connected to said blood outlet of the hemodialyzer, a blood outlet for connection to a patient via a venous route, and an air removal outlet;

tube and valve means selectively connecting and disconnecting said inlet of the air-removal and filtrate pump with said filtrate outlet of the hemofilter and air removal outlets; and

means for introducing an anti-coagulant to said air collection chamber.

2. A hemodialysis system according to claim 1 in which additional tube and valve means selectively connect said blood outlet of said blood pump with said reservoir.

3. A blood pumping system for a hemodialysis circuit comprising:

a flexible vessel connected to flexible ingress and egress tubes for entry and discharge of blood from a patient, said vessel and tubes being adapted to self return to their original shapes when released after being collapsed;

ingress and egress pinch valve mechanisms arranged for selectively collapsing said ingress and egress tubes, respectively;

compression means for selectively collapsing said vessel during a compression stroke to discharge blood into said egress tube when said egress tube is open and said ingress tube is collapsed, said compression means also having a return stroke permitting said vessel to return to its original shape to create a suction in said ingress tube when said egress tube is collapsed and said ingress tube is open; and

control means operatively connected to said valve mechanisms and compression means for operating in a cycle wherein said ingress tube is open and said egress tube is closed during said return stroke, wherein said ingress tube is closed and said egress tube is open during said compression stroke, and wherein, said ingress tube is closed before said egress tube is opened at the start of said compression stroke.

4. A hemodialysis method comprising:

circulating a patient'"'"'s blood from and back to the patient in a closed primary blood circuit through a hemofilter, hemodialyzer, and air extraction chamber arranged in series;

collecting filtrate from the hemofilter in a reservoir located in a closed secondary circuit connected to said primary circuit; and

pumping air from said air extraction chamber to said reservoir through said secondary circuit to remove all air from the circulating blood before return to the patient.

5. A hemodialysis method according to claim 4 in which collected filtrate is returned to said circuit.

6. A hemodialysis method according to claim 4 in which collected filtrate is returned to the circuit via the air collection chamber.

7. A hemodialysis method according to claim 4 in which an anti-coagulant is introduced to said air collection chamber to prevent blood coagulation in said circuit.

8. A hemodialysis method comprising:

introducing blood from a patient into an external blood circuit connected to the patient;

isolating equal volumetric increments of the introduced blood in a flexible vessel in said external circuit;

linearly compressing said vessel each time only that it contains one of said increments, and advancing the respective increment along said external circuit while the vessel is being compressed;

filtering the advancing increments and thereby removing excess fluid as filtrate; and

diffusing solutes from each increment as its advances further along said external circuit for return to the patient.

9. A hemodialysis method according to claim 8 in which said filtering of the advancing increments of blood comprises removing and storing excess fluid from the blood, and returning some of said stored excess fluid to said external circuit from time to time to control the fluid content of the blood.

10. A method according to claim 8 in which said filtrate is collected in a filtrate circuit, and in which some of said filtrate is returned from said filtrate circuit to said external circuit when dialysis has been completed to displace the blood remaining in said external circuit and thereby return such blood to the patient.

11. A hemodialysis method comprising:

circulating blood during a treatment period from a patient through an external circuit and back to the patient;

filtering excess fluid from the circulating blood and collecting the excess fluid filtrate;

diffusing urea from the circulating blood; and

displacing the blood remaining in said external circuit at the close of said treatment period with the collected filtrate to return such blood to the patient.

12. A hemodialysis method comprising:

circulating blood during a treatment period from a patient through an external circuit and back to the patient;

filtering excess fluid from the circulating blood by a hemofilter in said external circuit and collecting the excess fluid filtrate in a filtrate reservoir within a filtrate circuit in a sterile environment;

dialyzing the circulating blood at a dialyzer in said external circuit; and

displacing the blood remaining in said external blood circuit at the close of said treatment period with the collected excess fluid filtrate to return such remaining blood to the patient.

13. A method according to claim 12 including the following additional steps:

disconnecting the external circuit from the patient and closing the external circuit;

introducing a cleaning agent on the dialysate side of said dialyzer; and

passing said cleaning agent through the dialyzer membrane into said external circuit.

14. A method according to claim 13 including the following additional steps:

removing said cleaning agent and introducing a sterilant to said external circuit; and

removing said sterilant in preparation for a dialysis treatment by dialysis of the sterilant through said dialyzer membrane.

15. A hemodialysis system comprising:

a hemodialyzer;

a flexible vessel adapted to self-expand to its original shape after being deformed by compression;

a closed blood circuit for passing blood from a patient to said vessel and from said vessel to the hemodialyzer, and for returning blood from the hemodialyzer to the patient, said blood circuit having an ingress valve between said vessel and the patient, and an egress valve between said vessel and the hemodialyzer;

apparatus for alternately compressing and releasing said vessel in alternating compression and release strokes; and

control means for starting each compression stroke after a predetermined operation of said vessel responsive to flow of blood from the patient in accordance with the patient'"'"'s own blood delivery rate, and for controlling the start of each release stroke, said control means being operatively associated with said valves for opening said ingress valve and closing said egress valve preliminary to the start of each release stroke, and for closing the ingress valve and opening the egress valve preliminary to the start of each compression stroke.

16. A system according to claim 15 in which said control means includes a sensor normally contacting said vessel and adapted to deactivate said apparatus during said release stroke whenever the release stroke progresses beyond the expansion of the vessel.

17. A hemodialysis system comprising;

a hemodialyzer;

a blood flow circuit for connection to a patient including a flexible vessel and flexible input and output tubes leading to said vessel from the patient and leading from the vessel to said hemodialyzer, said vessel and tubes having a self return characteristic when collapsed; and

squeeze means external to said tubes and external to said vessel for selectively collapsing them in a pumping cycle wherein said vessel collapses in a pumping stroke and expands in a suction stroke, wherein a portion of said input tube is collapsed as an input valve prior to the start of said pumping stroke and is released for expansion at the beginning of said suction stroke, and wherein a portion of said output tube is collapsed as an output valve at the beginning of said suction stroke and is released for expansion at the beginning of said pumping stroke; and

control means for activating said squeeze means to start said pumping stroke only when said vessel contains a preset volume of blood.

18. A blood pumping system comprising:

a blood pumping system for a hemodialysis circuit comprising;

a flexible vessel connected to flexible ingress and egress tubes for entry and discharge of blood from a patient, said vessel and tubes being adapted to self return to their original shapes when released after being collapsed;

ingress and egress pinch valve mechanisms arranged for selectively collapsing said ingress and egress tubes, respectively;

compression means including a rotary combination crank and cam member, a compression shoe engaging said vessel, and a link pivotally connected to said member and shoe for linearly reciprocating said shoe responsive to turning of said crank and cam member to alternately move said shoe in a vessel compressing stroke and a vessel expansion stroke; and

pinch valve mechanisms including rockers with pinch elements at one end of the rockers and cam followers at the other end thereof engaging said crank and cam member while it turns to responsively pinch and release portions of said tubes by said pinch elements in a cycle wherein said ingress tube is open and said egress tube is closed during said expansion stroke and wherein said ingress tube is closed and said egress tube is open during said compression stroke.

19. A hemodialysis system comprising:

a hemofilter having a membrane with a blood side and a filtrate side;

a hemodialyzer having a membrane with a blood side and a dialysate side;

an air removal station;

a reservoir connected by a filtrate circuit to said filtrate side of the hemofilter and to the top of said station;

pump means for circulating blood in a blood circuit from a patient to said blood sides and back to the patient via said station; and

circulating means for circulating air through said filtrate circuit to said reservoir from the circulating blood in said blood circuit at said station, and for circulating filtrate to said reservoir through said filtrate circuit.

20. A hemodialysis system according to claim 19 in which anti-coagulant introducing means is connected to said station.

21. A hemodialysis system according to claim 19 in which said circulating means comprises a reversible pump, a pinch valve between said pump and said hemofilter, and a pinch valve between said pump and said station, whereby filtrate can be pumped from said hemofilter to said reservoir, or filtrate can be pumped from said reservoir to said blood circuit at said station or to said blood circuit at said hemofilter via the membrane of the hemofilter.

22. A hemodialysis system according to claim 21 in which said circulating means includes a reversible pump, and said filtrate circuit also connects with said blood circuit at the outlet side of said pump means by a branch having a pinch valve and a pressure sensor located between said pinch valve and said pump means.

23. A hemodialysis system comprising:

a blood pump having a blood outlet and a blood inlet for connection to a patient via an arterial route;

a hemofilter having a blood inlet connected to said blood outlet of the pump, and having a blood outlet and a filtrate outlet;

a hemodialyzer having a blood outlet, a blood inlet connected to said blood outlet of the hemofilter, and a dialysate inlet and outlet;

a filtrate reservoir;

an air-removal and filtrate pump having an outlet connected to said reservoir and having an inlet;

an air extraction chamber having a blood inlet connected to said blood outlet of the hemodialyzer, a blood outlet for connection to a patient via a venous route, and an air removal outlet;

tube and valve means selectively connecting and disconnecting said inlet of the air-removal and filtrate pump with said filtrate outlet of the hemofilter and air removal outlets; and

means for introducing an anti-coagulant to said air extraction chamber;

said pumps being selectively reversible to pump filtrate from said reservoir to the hemofilter and/or air extraction chamber to enable return of the blood in the system to the patient via the arterial and venous routes at the close of a hemodialysis treatment.

24. A hemodialysis method comprising:

circulating a patient'"'"'s blood from and back tot he patient in a circuit through a hemofilter, hemodialyzer, and air extraction chamber arranged in series;

collecting filtrate from the hemofilter in a reservoir;

extracting air from said air extracting chamber and collecting it in said reservoir to remove air from the circulating blood before return to the patient;

and returning some of the collected filtrate from the reservoir to the circuit at the close of dialysis such as to return the patient'"'"'s blood in the circuit to the patient.

25. A hemodialysis method comprising:

introducing blood from a patient into an external blood circuit connected to the patient;

isolating volumetric increments of the introduced blood in a flexible vessel in said external circuit;

linearly compressing said vessel each time only that it contains one of said increments, and advancing the respective increment along said external circuit while the vessel is being compressed;

filtering the advancing increments and thereby removing excess fluid as filtrate;

collecting said filtrate in a filtrate circuit;

diffusing solutes from each increment as its advances further along said external circuit for return to the patient; and

returning some of said filtrate from said filtrate circuit to said external circuit when dialysis has been completed to displace the blood remaining in said external circuit and thereby return such blood to the patient.

26. A hemodialysis system comprising:

a blood circuit;

a filtrate circuit connected to said blood circuit;

means for introducing blood from a patient into said blood circuit and for returning blood from said blood circuit to the patient;

means for isolating equal volumetric increments of the introduced blood in a flexible vessel in said blood circuit;

means for compressing said vessel each time, and only each time, that it contains one of said increments so that the respective increment is advanced along said blood circuit;

filtering means for filtering the advancing increments to remove excess fluid as filtrate;

means for collecting said filtrate in said filtrate circuit;

means for selectively returning some of said filtrate from said filtrate circuit to said blood circuit for selectively controlling the amount of fluid in the blood returned to the patient.

27. A hemodialysis system according to claim 26 in which means are provided for diffusing solutes from each said increment as it advances along said blood circuit from said filtering means for return to the patient.

28. A hemodialysis system comprising:

a blood circuit;

a filtrate circuit connected to said blood circuit;

means for introducing blood from a patient into said blood circuit;

means for isolating equal volumetric increments of the introduced blood in a flexible vessel in said blood circuit;

means for linearly compressing said vessel each time, and only each time, that it contains one of said increments, and advancing the respective increment along said blood circuit while the vessel is being compressed;

means for filtering the advancing increments to remove excess fluid as filtrate;

means for collecting said filtrate in said filtrate circuit;

means for diffusing solutes from each increment as it advances further along said blood circuit for return to the patient; and

means for selectively returning some of said filtrate from said filtrate circuit to said blood circuit.