Systems and methods for controlling blood flow and waste fluid removal during hemofiltration

• US 6,595,943 B1
• Filed: 02/25/2000
• Issued: 07/22/2003
• Est. Priority Date: 02/14/1997
• Status: Expired due to Term

• Current Assignee: Nxstage Medical Incorporated (Fresenius Medical Care AG)
• Original Assignee: Nxstage Medical Incorporated (Fresenius Medical Care AG)
• Inventors: Burbank, Jeffrey
• Primary Examiner(s): Sykes, Angela D.
• Assistant Examiner(s): Bianco, Patricia
• Application Number:
  US09/513,915
• Time in Patent Office: 1,243 Days
• Field of Search: 604/4.01, 604/5.01, 604/5-2-, 604/6.09, 604/6.1, 604/611, 604/6.01, 604/6.16, 604/403-16, 422/44, 210/645-47, 210/650-52, 210/739, 210/741, 210/744, 210/767, 210/790, 210/805, 210/85, 210/87-90, 210/97, 210/98, 210/252-53, 210/257--25, 210/258-262, 210/256, 210/321.6, 210/321-1-3, 210/929, 210/416.1, 210/417-20, 210/194, 210/195--19
• US Class Current: 604/5.01
• 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 1/342 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 1/36224 with sensing means or components thereof
• CPC Class Codes: A61M 1/36225 with blood pumping means or components thereof
• 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 2205/502 : User interfaces, e.g. screens or keyboards
• 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 39/0208 : Subcutaneous access sites for injecting or removing fluids transcutaneous access sites A61M39/0247; implantable infusion devices A61M5/14276

Abstract

During hemofiltration, blood is conveyed from an individual through a blood line into a hemofilter to remove waste fluid. Waste fluid is conveyed from the hemofilter through a waste removal line at a waste removal rate. Waste fluid pressure is sensed in the waste removal line. A controller adjusts the waste removal rate to maintain waste fluid pressure at a predetermined set value.

Claims

1. A hemofiltration system comprising an extracorporeal circuit for circulating blood from an individual through a hemofilter to remove waste, the extracorporeal circuit including a blood line coupled to the hemofilter and adapted to draw blood from the individual, a blood pump to convey blood through the blood line from the individual into the hemofilter at a blood flow rate, a waste removal line to convey waste fluid from the hemofilter, a sensor in the blood line to sense blood pressure, and a controller coupled to the sensor and the blood pump to adjust the blood flow rate to maintain blood pressure at a predetermined set value.

2. A system according to claim 1

wherein the controller generates an alarm output based upon variance between sensed blood pressure and the predetermined set value.

3. A system according to claim 2

wherein the alarm output terminates operation of the blood pump.

4. A method for carrying out hemofiltration comprising the steps of

conveying blood from the individual at a blood flow rate through a blood line into a hemofilter to remove waste fluid,

conveying waste fluid from the hemofilter through a waste removal line,

sensing blood pressure in the blood line, and

adjusting the blood flow rate to maintain blood pressure at a predetermined set value.

5. A method according to claim 4

further including the step of generating an alarm output based upon variance between sensed blood pressure and the predetermined set value.

6. A method according to claim 5

wherein the alarm output terminates operation of the blood pump.

7. A hemofiltration system, comprising:

a filter;

an arterial blood line connectable to a patient access and adapted to convey blood from said patient access to a filter;

a venous blood line connectable to said patient access and adapted to convey blood from said filter to patient access; and

a pump configured to convey blood through said arterial blood line, a sensor to sense pressure in said arterial blood line, and a controller connected to receive a pressure signal from said sensor and to control a rate of flow of said pump;

said controller being configured to maintain a constant pressure in said arterial blood line by regulating a speed of said pump in response to said pressure signal.

8. A system as in claim 7, wherein said controller is configured to slow said rate of flow when said pressure drops.

9. A system as in claim 8, wherein said controller is configured to speed up said rate of flow when said pressure increases.

10. A system as in claim 7, wherein said controller is configured to control said rate of flow by controlling a speed of said pump.

11. A system as in claim 7, wherein said controller is a microcomputer programmed to compare said pressure signal with a predetermined value.

12. A system as in claim 7, wherein said controller is configured such that when said patient access becomes clogged, said rate of flow is slowed.