Extracorporeal circuits for performing hemofiltration employing pressure sensing without an air interface

• US 6,589,482 B1
• Filed: 02/25/2000
• Issued: 07/08/2003
• Est. Priority Date: 02/14/1997
• Status: Expired due to Term

• Current Assignee: Nxstage Medical Incorporated (Fresenius SE & Co. KGaA), Nstage Medical, Inc.
• Original Assignee: Nxstage Medical Incorporated (Fresenius SE & Co. KGaA)
• Inventors: Treu, Dennis M., Burbank, Jeffrey H., Brugger, James M
• Primary Examiner(s): Sykes, Angela D.
• Assistant Examiner(s): Bianco, Patricia
• Application Number:
  US09/512,927
• Time in Patent Office: 1,229 Days
• Field of Search: 604/4.01, 604/5.01, 604/5.02, 604/5.04, 604/6.01, 604/6.04, 604/6.09, 604/6.1, 604/6.11, 604/6-5-, 422/44, 422/48, 422/82.13, 422/105-106, 422/112, 210/645-7, 210/650-652, 210/739, 210/741, 210/744, 210/767, 210/782, 210/85, 210/97, 210/103-4, 210/252-3, 210/255-6, 210/257--25, 210/258-60, 210/261-262, 210/282, 210/287-89, 210/321.6, 210/321-1-3, 210/929, 210/416.1, 210/418, 128/904, 128/920, 128/923-4, 128/898
• US Class Current: 422/44
• CPC Class Codes: A61M 1/1639 linked by membranes
• CPC Class Codes: A61M 1/34 Filtering material out of the blood by passing it through a membrane, i.e. hemofiltration or diafiltration
• CPC Class Codes: A61M 1/3401 Cassettes therefor
• CPC Class Codes: A61M 1/3403 Regulation parameters
• CPC Class Codes: A61M 1/341 by measuring the filtrate rate or volume
• CPC Class Codes: A61M 1/342 Adding solutions to the blood, e.g. substitution solutions for preventing coagulation A61M1/3672
• CPC Class Codes: A61M 1/3441 Substitution rate control as a function of the ultrafiltration rate
• CPC Class Codes: A61M 1/3444 in which the collected ultra-filtrate expels an equal volume of substitution fluid from a reservoir
• CPC Class Codes: A61M 1/3448 by mechanically linked pumps in both ultra-filtrate and substitution flow line
• CPC Class Codes: A61M 1/3458 having electrolytes not present in the dialysate
• CPC Class Codes: A61M 1/361 before treatment
• CPC Class Codes: A61M 1/3612 after treatment
• CPC Class Codes: A61M 1/362223 the interface being evacuated interfaces to enhance contact
• CPC Class Codes: A61M 1/36226 Constructional details of cassettes, e.g. specific details on material or shape
• CPC Class Codes: A61M 1/362262 Details of incorporated reservoirs
• CPC Class Codes: A61M 1/362265 Details of valves
• CPC Class Codes: A61M 1/3626 Gas bubble detectors
• CPC Class Codes: A61M 1/3639 Blood pressure control, pressure transducers specially adapted therefor
• CPC Class Codes: A61M 1/3646 Expelling the residual body fluid after use, e.g. back to the body
• CPC Class Codes: A61M 1/367 Circuit parts not covered by the preceding subgroups of group A61M1/3621
• CPC Class Codes: A61M 2205/126 : with incorporated membrane filters
• CPC Class Codes: A61M 2205/128 : with incorporated valves
• CPC Class Codes: A61M 2205/15 : Detection of leaks
• CPC Class Codes: A61M 2205/3331 : Pressure; Flow
• CPC Class Codes: A61M 2205/3334 : Measuring or controlling the flow rate
• CPC Class Codes: A61M 2205/35 : Communication
• CPC Class Codes: A61M 2205/3553 : remote, e.g. between patient's home and doctor's office
• CPC Class Codes: A61M 2205/3569 : sublocal, e.g. between console and disposable
• CPC Class Codes: A61M 2205/505 : Touch-screens; Virtual keyboard or keypads; Virtual buttons; Soft keys; Mouse touches
• CPC Class Codes: A61M 2205/60 : with identification means
• CPC Class Codes: A61M 2205/6018 : providing set-up signals for the apparatus configuration
• CPC Class Codes: A61M 2205/6072 : Bar codes
• CPC Class Codes: A61M 2209/06 : Packaging for specific medical equipment
• CPC Class Codes: A61M 39/0208 : Subcutaneous access sites for injecting or removing fluids transcutaneous access sites A61M39/0247; implantable infusion devices A61M5/14276
• CPC Class Codes: Y10S 210/929 : Hemoultrafiltrate volume measurement or control processes

Abstract

An extracorporeal fluid circuit for performing hemofiltration defines within a flexible panel a flow channel that is free of an air interface. The flexible panel includes an in-line sensor region through which fluid pressure in the flow channel can be measured by an external sensor. The systems and methods enable sensing fluid pressure through the in-line sensor region using the external sensor. The flow channel can convey, e.g., waste from the hemofilter or replacement fluid for return to the individual.

Claims

1. A hemofiltration system, comprising:

a hemofilter;

a first panel comprising first and second sheets of material sealed to form a first fluid pathway and a first chamber, the first fluid pathway passing a volume of a waste fluid to the first chamber, the first fluid pathway and first chamber free of an air interface;

a second panel comprising first and second sheets of material sealed to form a second fluid pathway and a second chamber, the second fluid pathway passing a volume of a replacement fluid to the second chamber, the second fluid pathway and second chamber free of an air interface, wherein the first and second panels are arranged in overlapping fashion and aligned so that the first chamber overlays the second chamber to form a structure so that the first fluid from the first chamber is displaced as the second fluid fills the second chamber;

a sensor operatively associated with at least one of the first or second panels to measure fluid pressure in the first or second fluid pathway; and

an extracorporeal circuit for circulating blood from an individual through the hemofilter to remove waste and to return blood and replacement fluid to the individual after removal of waste while the first and second panels operate to balance the volume of removed waste fluid with the volume of replacement fluid.

2. A system according to claim 1

wherein the flexible panel includes two flexible sheets having a pattern of seals forming the flow channel and in-line sensor region between the two flexible sheets.

3. A system according to claim 1

wherein the flexible panel includes an in-line pump region to convey fluid in the flow channel in response to peristaltic pressure externally applied to the flexible panel.

4. A system according to claim 3

wherein the in-line sensor region is located in an upstream flow direction from the in-line pump region.

5. A system according to claim 3

wherein the in-line sensor region is located in a downstream flow direction from the in-line pump region.

6. A system according to claim 1

wherein the flexible panel includes a clamping region to occlude the flow channel in response to force externally applied to the flexible panel.

7. A system according to claim 1

wherein the flow channel conveys waste from the hemofilter.

8. A system according to claim 1

wherein the flow channel conveys replacement fluid for return to the individual.

9. A method for hemofiltration of a patient'"'"'s blood, comprising the steps of:

providing an extracorporeal fluid circuit comprising a hemofilter, a first panel comprising first and second sheets of material sealed to form a first fluid pathway and a first chamber, the first fluid pathway and first chamber free of an air interface, and a second panel comprising first and second sheets of material sealed to form a second fluid pathway and a second chamber, the second fluid pathway and second chamber free of an air interface, wherein the first and second panels are arranged in overlapping fashion and aligned so that the first chamber overlays the second chamber;

attaching the patient to the extracorporeal fluid circuit to access the patient'"'"'s blood;

circulating blood from the patient through the hemofilter to remove waste and to return blood and replacement fluid to the patient after removal of waste while the first and second panels operate to balance the volume of removed waste fluid with the volume of replacement fluid; and

measuring fluid pressure in the first or second fluid pathway using a sensor operatively associated with at least one of the first or second panels.

10. A method according to claim 9

including the step of pumping fluid in the flow channel by externally applying peristaltic pressure to the flexible panel.

11. A method according to claim 10

wherein the sensing step senses fluid pressure downstream of where peristaltic pressure is applied.

12. A method according to claim 10

wherein the sensing step senses fluid pressure upstream of where peristaltic pressure is applied.

13. A method according to claim 9

including the step of occluding the flow channel by externally applying force to the flexible panel.

14. A method according to claim 9

wherein the flow channel conveys waste from the hemofilter.

15. A method according to claim 9

wherein the flow channel conveys replacement fluid for return to the individual.