DIALYSIS FLUID MEASUREMENT SYSTEMS USING CONDUCTIVE CONTACTS

• US 20090012452A1
• Filed: 07/05/2007
• Published: 01/08/2009
• Est. Priority Date: 07/05/2007
• 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: Chan, William, Perry, Mark, Lasso, Angel M., Hogard, Michael E., Roger, Rodolfo G., Busby, Donald, Slepicka, James S., Kienman, Richard
• Granted Patent: US 8,287,724 B2
• Time in Patent Office: Days
• US Class Current: 604/29
• CPC Class Codes: A61M 1/152 Details related to the interface between cassette and machine
• 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 1/155 with treatment-fluid pumping means or components thereof
• CPC Class Codes: A61M 1/1561 at least one cassette surface or portion thereof being flexible, e.g. the cassette having a rigid base portion with preformed channels and being covered with a foil
• CPC Class Codes: A61M 1/1565 Details of valves
• CPC Class Codes: A61M 1/1607 before use, i.e. upstream of dialyser
• CPC Class Codes: A61M 1/28 Peritoneal dialysis ; Other peritoneal treatment, e.g. oxygenation
• 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 2205/13 with means for the detection of operative contact with patient, e.g. lip sensor
• CPC Class Codes: A61M 2205/3368 Temperature
• CPC Class Codes: A61M 5/16831 Monitoring, detecting, signalling or eliminating infusion flow anomalies low-level float-valves causing cut-off A61M5/40; indicating or recording presence, absence or direction of flow in general G01P13/0066
• CPC Class Codes: A61M 5/16854 by monitoring line pressure
• CPC Class Codes: G01N 27/10 Investigation or analysis specially adapted for controlling or monitoring operations or for signalling

Abstract

A dialysis system instrument includes a dialysis instrument, a disposable pumping and valving cassette apparatus operable with pumping and valving actuators of the dialysis instrument, the disposable cassette including an electronic cell and electronics associated with the electronic cell, the electronics configured to determine an electrical property of a solution flowing through the electronic cell of the disposable apparatus.

Claims

1. A dialysis system comprising:

a dialysis instrument;

a disposable pumping cassette apparatus operable with a pumping actuator of the dialysis instmment, the disposable cassette including an electronic cell; and

electronics associated with the electronic cell, the electronics configured to determine an electrical property of a solution flowing through the electronic cell of the disposable apparatus.

2. The dialysis system of claim 1, wherein the dialysis system is of a type selected from the group consisting of:

peritoneal dialysis, hemodialysis and colorectal dialysis.

3. The dialysis system of claim 1, wherein the electronics are further configured to use the electronic cell to determine if the solution has been mixed properly.

4. The dialysis system of claim 3, the electronics operable with the dialysis instrument upon determining that the solution has not been mixed properly to cause at least one of:

(i) an alarm to be sounded;

(ii) a visual message to be posted;

(iii) a pump to be stopped;

(iv) a line to be occluded; and

(v) a valve to be closed.

5. The dialysis system of claim 1, wherein the electronics are further configured to use the electronic cell to identify the solution as one from the group consisting of:

a dialysis fluid, a parenteral compounding fluid, an intravenous infusion fluid and a chemotherapeutic compounding fluid.

6. The dialysis system of claim 1, wherein the electronics are further configured to use the electronic cell to determine at least one of:

(i) whether a connection between the dialysis instrument and a patient has been disconnected;

(ii) a temperature of the solution; and

(iii) a leaking valve.

7. The dialysis system of claim 1, wherein the electronic cell includes a first electrode and a second electrode in fluid communication with the solution.

8. The dialysis system of claim 7, wherein the first and second electrodes are at least one of:

(i) formed of stainless steel;

(ii) insert molded within the disposable apparatus;

(iii) attached to the disposable apparatus by way of adhesive bonding;

(iv) formed of electrically conductive plastic;

(v) printed in a spaced apart relationship on a surface of the disposable apparatus;

(vi) attached to the cassette of the disposable apparatus;

(vii) attached to a section of tubing of the disposable apparatus;

(viii) tapered to mate with tapered apertures of the disposable apparatus;

(ix) invasive relative to the solution; and

(x) protected against faulty connection with the instrument.

9. The dialysis system of claim 7, wherein the electronics include a source configured to provide one of a current and a voltage signal to at least one of the first and second electrodes, and a measuring device configured to determine a resistance of the solution between the first and second electrodes by measuring the other of the current voltage signal.

10. The dialysis system of claim 9, wherein at least one of:

(i) the signal has a frequency of about 10,000 Hz or less;

(ii) the measured resistance is proportional to a conductivity of said medical fluid;

(iii) the electronics are configured to calculate a conductivity of the solution by applying an algorithm to the measured resistance;

(iv) the conductivity is linearly proportional to a concentration of a substance within the solution; and

(v) a second meter connected to the first and second electrodes and configured to protect the system against or to alert the system of a faulty connection between at least one of the first and second electrodes and the instrument.

11. The dialysis system of claim 10, the algorithm accounting for a temperature of the solution.

12. The dialysis system of claim 1, the electronics configured to perform a matching check using the electrical property of the solution.

13. The dialysis system of claim 12, wherein the matching check is at least one of:

(i) used to determine whether the solution includes a particular substance;

(ii) used to compare a conductivity of the solution with an acceptable range of conductivities; and

(iii) performed by comparing the concentration to at least one value in a look-up table stored in a database.

14. The dialysis system of claim 1, the electronics configured to sense whether an expected step change in conductivity occurs after a period of time to determine if the solution can be delivered to a patient.

15. A dialysis system comprising:

a dialysis instrument;

a disposable cassette operable with the dialysis instrument, the disposable cassette including a rigid structure, the rigid structure including first and second apertures each defined by a non-uniform wall;

first and second conductive contacts having non-uniform shapes that mate with the non-uniform walls of the first and second apertures; and

electronics operable with the first and second contacts to determine at least one of;

(i) a patient access disconnection;

(ii) a temperature of a medical fluid flowing through the cassette; and

(iii) a conductivity of the medical fluid flowing through the cassette.

16. The dialysis system of claim 15, wherein the electronics are operable with the first and second contacts to detect at least two of:

(i) a patient access disconnection;

(ii) a temperature of a medical fluid flowing through the cassette; and

(iii) a conductivity of the medical fluid flowing through the cassette.

17. The dialysis system of claim 15, wherein the electronics are operable with the first and second contacts to detect each of:

(i) a patient access disconnection;

(ii) a temperature of a medical fluid flowing through the cassette; and

(iii) a conductivity of the medical fluid flowing through the cassette.

18. The dialysis system of claim 15, wherein the non-uniform shapes of the contacts and the non-uniform walls are at least one of:

(i) tapered and (ii) stepped.

19. The dialysis system of claim 15, which includes a sterile barrier placed between the contacts and the defining walls of the disposable cassette.

20. The dialysis system of claim 15, wherein the rigid structure of the disposable cassette is one of:

(i) part of a valve and flowpath portion of the cassette; and

(ii) includes first and second ports extending from the cassette.

21. The dialysis system of claim 15, wherein the dialysis system is of a type selected from the group consisting of:

peritoneal dialysis, hemodialysis and colorectal dialysis.

22. The dialysis system of claim 15, wherein the electronics include a source configured to provide one of a current and a voltage signal to at least one of the first and second electrodes, and a measuring device configured to measure a resistance of the solution between the first and second electrodes.

23. The dialysis system of claim 22, wherein at least one of:

(i) the signal has a frequency of about 10,000 Hz or less;

(ii) the measured resistance is proportional to a conductivity of said medical fluid;

(iii) the electronics are configured to calculate a conductivity of the solution by applying an algorithm to the measured resistance;

(iv) the conductivity is linearly proportional to a concentration of a substance within the solution; and

(v) a second meter connected to the first and second electrodes and configured to protect the system against or to alert the system of a faulty connection between at least one of the first and second electrodes and the instrument.

24. A dialysis system comprising:

a dual chamber dialysate supply;

a disposable cassette operable with the supply, the disposable cassette including first and second electrodes positioned to contact the dialysate as it flows through the disposable cassette;

a source configured to impart an electrical signal to the dialysate;

electronics configured to measure an electrical property of the medical fluid as it flows passed the electrodes of the disposable cassette; and

processing configured to (i) use the measured electrical property and an algorithm to calculate a conductivity value and (ii) use the calculated conductivity value to determine if the dialysate has been mixed properly in the dual chamber supply.

25. The dialysis system of claim 24, wherein the dialysis system is of a type selected from the group consisting of:

peritoneal dialysis, hemodialysis and colorectal dialysis.

26. The dialysis system of claim 24, which includes a temperature sensor coupled operably to at least one of the electrodes, the processing further configured to determine a temperature of the dialysate.

27. The dialysis system of claim 24, which includes a patient access needle, the processing further configured to use the measured electrical property or a different measured electrical property to determine whether the patient access has been disconnected.

28. The dialysis system of claim 24, wherein the measured electrical property is resistance and the different measured electrical property is impedance.

29. The dialysis system of claim 24, wherein the algorithm is based on at least one of:

(i) a geometry of the electrodes;

(ii) a spacing of the electrodes; and

(iii) a positioning the electrodes relative to a pathway of the cassette operable with the electrodes.

30. A medical fluid system comprising:

a supply of medical fluid;

a pump configured to pump the medical fluid from the supply to a patient;

a disposable apparatus operable with the supply and the pump, the disposable apparatus including a pathway having first and second electrodes positioned to contact the medical fluid as it flows through the pathway;

a source configured to impart an electrical signal to the medical fluid;

electronics configured to measure an electrical property of the medical fluid as it flows passed the electrodes of the disposable cassette; and

processing configured to use the measured electrical property and an algorithm based on at least one of (i) a geometry of the electrodes;

(ii) a spacing of the electrodes; and

(iii) a positioning the electrodes relative to the pathway to calculate a conductivity value.

31. The medical fluid system of claim 30, wherein the pump is of a type selected from the group consisting of:

(i) an infusion pump;

(ii) a peristaltic pump; and

(iii) a membrane pump; and

(iv) a piezoelectric pump.

32. The medical fluid system of claim 30, wherein the first and second electrodes are at least one of:

(i) formed of stainless steel;

(ii) insert molded within the disposable apparatus;

(iii) attached to the disposable apparatus by way of adhesive bonding;

(iv) formed of electrically conductive plastic;

(v) printed in a spaced apart relationship on a surface of the disposable apparatus;

(vi) attached to a disposable cassette of the disposable apparatus;

(vii) attached to a section of tubing of the disposable cassette;

(viii) non-uniform to mate with non-uniform apertures of the disposable apparatus; and

(ix) invasive relative to the medical fluid.

33. The medical fluid system of claim 30, wherein the signal is characterized by at least one of:

(i) being a voltage signal;

(ii) being a current signal;

and (iii) having a frequency of about 10,000 Hz or less.

34. The medical fluid system of claim 30, wherein the measured electrical property is resistance.

35. The medical fluid system of claim 30, wherein the conductivity value is linearly proportional to a concentration of a substance within the solution.

36. The medical fluid system of claim 30, wherein the processing is further configured to compare the conductivity value with a range of acceptable conductivity values.

37. The medical fluid system of claim 36, the processing operable upon determining that the conductivity value is outside the range of acceptable conductivity values to cause at least one of:

(i) an alarm to be sounded;

(ii) a visual message to be posted;

(iii) the pump to be stopped;

(iv) a pathway to be occluded; and

(v) a valve to be closed.

38. The medical fluid system of claim 30, wherein the geometry of the electrodes relevant to the algorithm includes a shape of a surface of the electrodes facing that the medical fluid contacts.

39. The medical fluid system of claim 30, wherein the positioning of the electrodes relevant to the algorithm includes how far across the fluid pathway the electrodes extend.

40. The medical fluid system of claim 30, the processor further configured to use the conductivity value to determine one of:

(i) whether the medical fluid is a correct medical fluid;

(ii) whether the medical fluid has a proper dosage of a component fluid; and

(iii) whether the medical fluid has been mixed properly.