DIALYSIS SYSTEM HAVING NON-INVASIVE FLUID VELOCITY SENSING

• US 20090101550A1
• Filed: 10/22/2007
• Published: 04/23/2009
• Est. Priority Date: 10/22/2007
• Status: Active Grant

• Current Assignee: Baxter Healthcare SA (Baxter International Inc.), Baxter International Inc.
• Original Assignee: Baxter Healthcare SA (Baxter International Inc.), Baxter International Inc.
• Inventors: Jablonski, Mark, Rohde, Justin, Busby, Donald, Muller, Matthew
• Granted Patent: US 8,858,787 B2
• Time in Patent Office: Days
• US Class Current: 210/87
• CPC Class Codes: A61M 1/1524 the interface providing means for actuating on functional elements of the cassette, e.g. plungers
• CPC Class Codes: A61M 1/154 with sensing means or components thereof
• CPC Class Codes: A61M 1/155 with treatment-fluid pumping means or components thereof
• CPC Class Codes: A61M 1/1565 Details of valves
• 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 1/1613 Profiling or modelling of patient or predicted treatment evolution or outcome
• CPC Class Codes: A61M 1/1645 with mechanically linked peristaltic dialysis fluid pumps one upstream, the other one downstream of the dialyser
• CPC Class Codes: A61M 1/1647 with flow rate measurement of the dialysis fluid, upstream and downstream of the dialyser
• CPC Class Codes: A61M 1/1658 Degasification
• CPC Class Codes: A61M 1/288 Priming priming in extracorporeal blood circuits A61M1/3643
• 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 1/3403 Regulation parameters
• CPC Class Codes: A61M 1/341 by measuring the filtrate rate or volume
• CPC Class Codes: A61M 1/3413 Diafiltration
• 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 1/362265 Details of valves
• 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 1/3649 : 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 1/3656 : Monitoring patency or flow at connection sites; Detecting disconnections
• CPC Class Codes: A61M 2205/12 : with interchangeable cassettes forming partially or totally the fluid circuit
• CPC Class Codes: A61M 2205/18 : with alarm
• CPC Class Codes: A61M 2205/3306 : Optical measuring means
• CPC Class Codes: A61M 2205/3313 : used specific wavelengths
• CPC Class Codes: A61M 2205/3334 : Measuring or controlling the flow rate
• CPC Class Codes: A61M 2205/3368 : Temperature
• CPC Class Codes: A61M 2205/50 : with microprocessors or computers
• CPC Class Codes: A61M 2230/20 : Blood composition characteristics
• CPC Class Codes: G01F 1/708 : Measuring the time taken to traverse a fixed distance

Abstract

A dialysis system includes a dialyzer; a blood pump coupled operably to a dialyzer; a dialysate inlet pump couple operably to a dialysate inlet of the dialyzer; a dialysate outlet pump coupled operably to a dialysate outlet of the dialyzer; a first non-invasive fluid velocity sensor positioned to sensor of inlet flowrate of dialysate pumped to the dialysate inlet by the dialysate inlet pump; and a second non-invasive fluid velocity sensor positioned to sense an outlet flowrate of dialysate pumped from the dialysate outlet by the dialysate outlet pump.

Claims

1. A dialysis system comprising:

a dialyzer;

a blood pump coupled operably to the dialyzer;

a dialysate inlet pump coupled operably to a dialysate inlet of the dialyzer;

a dialysate outlet pump coupled operably to a dialysate outlet of the dialyzer;

a first non-invasive fluid velocity sensor positioned to sense an inlet velocity of dialysate pumped to the dialyzer inlet by the dialysate inlet pump; and

a second non-invasive fluid velocity sensor positioned to sense an outlet velocity of dialysate pumped from the dialyzer outlet by the dialysate outlet pump.

2. The dialysis system of claim 1, wherein the first and second non-invasive fluid velocity sensors are of a type selected from the group consisting of:

optical, laser and heat pulse.

3. The dialysis system of claim 1, which includes at least one of a heparin pump and a saline pump connected to a blood circuit, the blood circuit including the blood pump and a blood side of the dialyzer, and at least one of:

(i) an additional non-invasive fluid velocity sensor positioned to sense a velocity of heparin pumped by the heparin pump; and

(ii) an additional non-invasive fluid velocity sensor positioned to sense a velocity of saline pumped by the saline pump.

4. The dialysis system of claim 1, which includes a logic implementor programmed to integrate signals from the first non-invasive fluid velocity sensor to determine a total amount of dialysate delivered during a treatment.

5. The dialysis system of claim 1, which includes a logic implementor programmed to subtract an output from the first non-invasive fluid velocity sensor from an output of the second non-invasive fluid velocity sensor to determine an amount of ultrafiltration removal from a patient during a treatment.

6. The dialysis system of claim 5, wherein the outputs are totaled outputs or instantaneous outputs.

7. The dialysis system of claim 1, which includes a bypass line positioned to selectively enable the dialysate inlet pump to pump dialysate past both the non-invasive fluid velocity sensors to calibrate the sensors.

8. The dialysis system of claim 7, wherein the bypass line is positioned from a junction between the first non-invasive fluid velocity sensor and the dialysate inlet to a junction between the dialysate outlet and the second non-invasive fluid velocity sensor.

9. The dialysis system of claim 7, which includes a calibration mode in which in the bypass line is opened to calibrate the first and second non-invasive fluid velocity sensors and a therapy mode in which the bypass line is closed.

10. The dialysis system of claim 1, wherein the dialysate inlet and dialysate outlet pumps are peristaltic pumps or membrane pumps.

11. A dialysis system comprising:

a dialysate inlet pump configured to pump dialysate to a dialyzer;

a dialysate outlet pump configured to pump dialysate from the dialyzer;

a dialysis instrument configured to actuate the dialysate inlet and outlet pumps, the instrument including a first non-invasive fluid velocity sensor and a second non-invasive fluid velocity sensor; and

a disposable dialysate carrying unit operable with the dialysis instrument, the disposable unit including a to-dialyzer pathway, at least a portion of which having a known cross-sectional area, the to-dialyzer portion when placed in the dialysis instrument positioned to operate with the first non-invasive fluid velocity sensor,

the disposable unit further including a from-dialyzer pathway, at least a portion of which having a known cross-sectional area, the from-dialyzer portion when placed in the dialysis instrument positioned to operate with the second non-invasive fluid velocity sensor.

12. The dialysis system of claim 11, wherein the known cross-sectional area is rectangular, square or circular.

13. The dialysis system of claim 11, wherein the known cross-sectional area is formed via a rigid piece of the disposable unit.

14. The dialysis system of claim 13, wherein the disposable unit includes at least one of:

(i) a flexible sheet operable with at least one valve actuator of the instrument;

(ii) a flexible sheet operable with at least one of the dialysate inlet and outlet pumps;

(iii) peristaltic pump tubing operable with at least one of the inlet and outlet pumps; and

(iv) at least one supply bag.

15. The dialysis system of claim 11, wherein the known cross-sectional area is formed via the instrument, the instrument configured to apply negative pressure to a sheeting of the disposable unit at the known cross-sectional area of the disposable dialysate carrying unit.

16. The dialysis system of claim 11, wherein the to-dialyzer pathway is positioned upstream or downstream of the dialysate inlet pump.

17. The dialysis system of claim 11, wherein the from-dialyzer pathway is positioned upstream or downstream of the dialysate outlet pump.

18. The dialysis system of claim 11, which includes a logic implementer programmed to perform at least one of:

(i) integrate signals from the first non-invasive fluid velocity sensor to determine a total amount of dialysate delivered during a treatment; and

(ii) subtract an output from the first non-invasive fluid velocity sensor from an output of the second non-invasive fluid velocity sensor to determine an amount of ultrafiltration removed from a patient during the treatment.

19. A dialysis system comprising:

a dialysate inlet pump configured to pump dialysate to a dialyzer;

a dialysate outlet pump configured to pump dialysate from the dialyzer;

a dialysis instrument configured to actuate the dialysate inlet and outlet pumps, the instrument including a first non-invasive fluid velocity sensor and a second non-invasive fluid velocity sensor; and

a disposable dialysate carrying unit operable with the dialysis instrument, the disposable unit including a to-dialyzer pathway, at least a portion of which is configured to make dialysate flow laminar ahead of a sensing area of the to-dialyzer pathway, the to-dialyzer sensing area operable with the first non-invasive fluid velocity sensor when the unit is placed in the dialysis instrument,

the disposable unit further including a from-dialyzer pathway, at least a portion of which is configured to make dialysate flow laminar ahead of a sensor area of the from-dialyzer pathway, the from-dialyzer sensing area operable with the first non-invasive fluid velocity sensor when the unit is placed in the dialysis instrument.

20. The dialysis system of claim 19, wherein at least one of the laminar flow portions is configured to produce dialysate flow having a Reynolds number of less than one-thousand.

21. The dialysis system of claim 19, wherein at least one of the laminar flow portions includes a section having an entrance length prior to the respective sensing area equal to or greater than 0.02*a hydraulic diameter of the laminar flow portion*a Reynolds number of dialysate flow through the laminar flow portion.

22. The dialysis system of claim 19, which includes a logic implementer configured to perform at least one of:

(i) integrate signals from the first non-invasive fluid velocity sensor to determine a total amount of dialysate delivered during a treatment; and

(ii) subtract an output from the first non-invasive fluid velocity sensor from an output of the second non-invasive fluid velocity sensor to determine an amount of ultrafiltration removed from a patient during the treatment.

23. A dialysis flow control system comprising:

a dialysate line;

a plurality of air detectors in the dialysate line, the air detectors spaced apart a known distance;

an air pump configured to inject a volume of air into dialysate line; and

a control element configured to receive a signal from each of the air detectors, the control element further configured (i) to determine a difference of time that the volume of air injected by the air pump takes to pass between the air detectors and (ii) to determine a velocity of dialysis fluid flowing through the dialysate line by dividing the known distance between the air detectors by the difference in time.

24. The dialysis flow control system of claim 23, the air pump valved to inject air selectively into the dialysate line at either side of the air detectors, such that in a peritoneal dialysis treatment, the velocity of the fluid can be measured going to and coming from the patient.

25. The dialysis flow control system of claim 24, a cross-sectional area of at least a section of the dialysis line between the air detectors being known, the control element further configured to determine a to- and from-patient flowrates by dividing the to- and from-velocities by the known cross-sectional area.

26. The dialysis control system of claim 25, the control element further configured to determine at least one of:

(a) a total volume of dialysis fluid delivered to the patient by integrating the to-patient flowrate over a delivery time;

(b) a total volume of dialysis fluid removed from the patient by integrating the from-patient flowrate over a removal time, and (c) a total volume of ultrafiltration removed from the patient by subtracting total volume of dialysis fluid delivered from the total amount of dialysis fluid removed.

27. The dialysis control system of claim 23, the dialysate line a to-dialyzer line, and which includes a from-dialyzer line, a plurality of additional air sensors positioned in the from-dialyzer line, the air pump valved to selectively inject air into the to- and from-dialyzer lines, the control element further configured to receive a signal from each of the additional from-dialyzer line air detectors and to perform elements (i) and (ii) for dialysis fluid flowing through the from-dialyzer line.

28. The dialysis control system of claim 27, cross-sectional areas of at least a section of each of the to- and from-dialyzer lines between respective air detectors being known, the control element further configured to determine to- and from-dialyzer flowrates by dividing the to- and from-dialyzer velocities by the respective cross-sectional areas of the to- and from-dialyzer line sections.

29. The dialysis control system of claim 28, the control element further configured to determine at least one of:

(a) a total volume of dialysis fluid delivered to the patient by integrating the to-dialyzer flowrate over a delivery time;

(b) a total volume of dialysis fluid removed from the patient by integrating the from-dialyzer flowrate over a removal time, and (iii) a total volume of ultrafiltration removed from the dialyzer by subtracting the total volume of dialysis fluid delivered from the total amount of dialysis fluid removed.

30. The dialysis control system of claim 23, the air pump configured to pull air from at least one of (i) an air trap and (ii) a filtered line.

31. The dialysis control system of claim 30, the filtered line in valved communicate with the air trap.

32. The dialysis control system of claim 23, the air trap provided in a disposable pumping cassette.