Automated control mechanisms in a hemodialysis apparatus

• US 10,537,671 B2
• Filed: 02/28/2017
• Issued: 01/21/2020
• Est. Priority Date: 04/14/2006
• Status: Active Grant

• Current Assignee: Deka Products Limited Partnership
• Original Assignee: Deka Products Limited Partnership
• Inventors: Wilt, Michael J., van der Merwe, Dirk A., Dale, James D., Tracey, Brian D., Grant, Kevin L., Demers, Jason A., Flynn, Catharine N.
• Primary Examiner(s): Brewster, Hayden
• Application Number:
  US15/445,683
• Publication Number:
  US 20170326282A1
• Time in Patent Office: 1,057 Days
• Field of Search: 210 85, 210 962, 210141, 210645, 210646
• 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 1/1561 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 1/15625 the reservoirs acting as balance chambers
• CPC Class Codes: A61M 1/16 with membranes
• CPC Class Codes: A61M 1/1605 Physical characteristics of the dialysate fluid
• CPC Class Codes: A61M 1/1639 linked by membranes
• CPC Class Codes: A61M 1/1656 Apparatus for preparing dialysates
• CPC Class Codes: A61M 1/166 Heating for sterilisation A61M1/1686
• CPC Class Codes: A61M 1/1664 with temperature control
• CPC Class Codes: A61M 1/1666 by dissolving solids
• CPC Class Codes: A61M 1/267 used for pumping
• CPC Class Codes: A61M 1/287 Dialysates therefor
• 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 1/362263 Details of incorporated filters
• CPC Class Codes: A61M 1/362265 Details of valves
• CPC Class Codes: A61M 1/362266 Means for adding solutions or substances to the blood
• CPC Class Codes: A61M 1/3638 with a vapour trap
• CPC Class Codes: A61M 1/3672 Means preventing coagulation
• CPC Class Codes: A61M 2205/12 : with interchangeable cassettes forming partially or totally the fluid circuit
• CPC Class Codes: A61M 2205/128 : with incorporated valves
• CPC Class Codes: A61M 2205/15 : Detection of leaks
• CPC Class Codes: A61M 2205/18 : with alarm
• CPC Class Codes: A61M 2205/3317 : Electromagnetic, inductive or dielectric measuring means
• CPC Class Codes: A61M 2205/3324 : PH measuring means
• CPC Class Codes: A61M 2205/3331 : Pressure; Flow
• CPC Class Codes: A61M 2205/3337 : Controlling, regulating pressure or flow by means of a valve by-passing a pump
• CPC Class Codes: A61M 2205/3368 : Temperature
• CPC Class Codes: A61M 2205/502 : User interfaces, e.g. screens or keyboards
• CPC Class Codes: A61M 2205/52 : with memories providing a history of measured variating parameters of apparatus or patient
• CPC Class Codes: A61M 60/113 : in other functional devices, e.g. dialysers or heart-lung machines
• CPC Class Codes: A61M 60/268 : the displacement member being flexible, e.g. membranes, diaphragms or bladders
• CPC Class Codes: A61M 60/37 : Haemodialysis, haemofiltration or diafiltration
• CPC Class Codes: A61M 60/43 : using vacuum at the blood pump, e.g. to accelerate filling
• CPC Class Codes: A61M 60/523 : using blood flow data, e.g. from blood flow transducers
• CPC Class Codes: A61M 60/531 : using blood pressure data, e.g. from blood pressure sensors
• 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: F04B 13/02 : of two or more fluids at the same time
• CPC Class Codes: F04B 43/00 : Machines, pumps, or pumping installations having flexible working members pumps or pumping installations specially adapted for elastic fluids F04B45/00
• CPC Class Codes: F04B 43/0733 : with fluid-actuated pump inlet or outlet valves; with two or more pumping chambers in series
• CPC Class Codes: F04B 45/02 : having bellows
• CPC Class Codes: F04B 49/06 : Control using electricity regulating by means of floats actuating electric switches F04B49/04
• CPC Class Codes: F04B 49/22 : by means of valves F04B49/03 takes precedence
• CPC Class Codes: F04B 53/06 : Venting
• CPC Class Codes: F04B 53/10 : Valves; Arrangement of valves
• CPC Class Codes: F04B 53/16 : Casings; Cylinders; Cylinder liners or heads; Fluid connections
• CPC Class Codes: F04B 7/02 : the valving being fluid-actuated
• CPC Class Codes: F04B 7/0216 : and having an oscillating movement
• CPC Class Codes: F04B 9/109 : having plural pumping chambers
• CPC Class Codes: F17D 3/00 : Arrangements for supervising or controlling working operations
• CPC Class Codes: Y10T 137/0324 : With control of flow by a condition or characteristic of a fluid
• CPC Class Codes: Y10T 137/0379 : By fluid pressure
• CPC Class Codes: Y10T 137/2521 : Flow comparison or differential response
• CPC Class Codes: Y10T 137/85978 : With pump
• CPC Class Codes: Y10T 137/86139 : Serial

Abstract

A hemodialysis apparatus comprising diaphragm pumps for the movement of both dialysate and blood, and under the control of a controller, is capable of detecting blood flow conditions that give rise to an alarm and implement procedures to adjust, pause, or halt the pumping of dialysate and/or blood. The controller can direct the application of a time-varying pressure to fluid in the control chamber of a blood pump, and monitor the resulting pressure waveform during a fill stroke of the blood pump. A deviation of the measured pressure variation from an expected value can give rise to an alert to a user and to the initiation of an adjustment, pause, or cessation of the dialysate pump'"'"'s activity.

Claims

1. A system for controlling fluid flow in a hemodialysis apparatus comprising:

a dialysate pump constructed and arranged to receive a fluid from a dialysate outlet of a dialyzer;

a blood pump comprising a reciprocating diaphragm constructed and arranged to deliver blood from an extracorporeal blood circuit to a blood inlet of the dialyzer, a pumping chamber of the blood pump separated from a control chamber of the blood pump by a flexible diaphragm, the control chamber constructed and arranged to contain a control fluid at a positive or a negative pressure to operate the diaphragm;

a pressure sensor constructed and arranged to measure a pressure of the control fluid contained in the control chamber of the blood pump;

a controller adapted and programmed to receive information from the pressure sensor, and programmed to operate a valve connecting a source of the control fluid to the control chamber of the blood pump;

wherein the controller is adapted and programmed to control the valve to generate a time-varying pressure waveform of the control fluid in the control chamber during a fill-stroke of the blood pump and to monitor a resulting pressure variation in the control chamber, and

wherein the controller is adapted and programmed to initiate a procedure to pause or stop the dialysate pump if a magnitude of the measured pressure variation deviates from a pre-determined value, the procedure comprising alerting a user of a fault condition and waiting a pre-determined time period for a user response to correct the fault condition before pausing or stopping the dialysate pump.

2. The system of claim 1, wherein the controller is adapted and programmed to compare the resulting pressure variation in the control chamber with a target pressure variation, and wherein a deviation between the resulting pressure variation and the target pressure variation that is greater than a pre-determined difference value causes the controller to initiate the procedure to pause or stop the dialysate pump.

3. The system of claim 1, wherein the controller is adapted and programmed to compare the measured pressure in the control chamber with a target pressure during time periods when an absolute value of the applied pressure is decreasing, and wherein a deviation between the measured pressure and the target pressure that is greater than a pre-determined difference value causes the controller to initiate the procedure to pause or stop the dialysate pump.

4. The system of claim 2, wherein the comparison by the controller comprises calculating a cross-correlation value between the measured pressure variation and the target pressure variation, and wherein a cross-correlation value that is less than a pre-determined cross-correlation value causes the controller to initiate the procedure to pause or stop the dialysate pump.

5. The system of claim 4, wherein the calculated cross-correlation value comprises a phase-insensitive cross-correlation value.

6. The system of claim 4, wherein the controller is adapted and programmed to initiate the procedure to pause or stop the dialysate pump only if the calculated cross-correlation value is less than the pre-determined cross-correlation value for two or more consecutive blood pump fill-strokes.

7. The system of claim 4, wherein the controller is adapted and programmed to calculate a filtered or averaged cross-correlation value during a fraction of a pump fill-stroke period and re-calculate one or more additional filtered or averaged cross-correlation values during one or more successive fractions of the fill-stroke period, and wherein the controller is further adapted and programmed to compare a highest valued filtered or averaged cross-correlation value during said fill-stroke period with a pre-determined filtered or averaged cross-correlation value to determine whether to initiate the procedure to pause or stop the dialysate pump.

8. The system of claim 1, wherein the time-varying pressure waveform comprises a sinusoidal pressure waveform.

9. The system of claim 1, wherein the valve comprises a variable restriction valve.

10. The system of claim 9, wherein the source of control fluid comprises a source of positively or negatively pressurized gas.

11. The system of claim 1, wherein the dialysate pump comprises a reciprocating diaphragm, and wherein the pre-determined value is based on a pressure Aduring a normal or full-flow pumping condition.

12. The system of claim 1, wherein the controller is adapted and programmed to pause or stop the dialysate pump while allowing the blood pump to continue to operate if a flow metric based on the deviation of the magnitude of the measured pressure variation from the pre-determined value exceeds a pre-determined flow metric value.

13. The system of claim 1, wherein the controller is adapted and programmed to calculate a flow metric comprising a measure of a variation of a peak-to-peak magnitude of the measured pressure.

14. The system of claim 13, wherein the controller is adapted and programmed to normalize the measured variation of the peak-to-peak magnitude to an expected or pre-determined peak-to-peak pressure variation, or a peak-to-peak pressure variation obtained during a nominal or full flow condition.

15. The system of claim 1, wherein the controller is adapted and programmed to calculate a flow metric based on a cross-correlation of a desired, expected or nominal pressure and the measured pressure.

16. The system of claim 15, wherein the flow metric is based on a phase insensitive cross-correlation of the desired, expected or nominal pressure and the measured pressure.

17. The system of claim 15, wherein the controller is adapted and programmed to set the flow metric to a correlation number derived from the cross-correlation while the diaphragm of the blood pump is moving, and to hold the flow metric at a value reached before the diaphragm reaches an end of its stroke.

18. The system of claim 15, wherein the controller is adapted and programmed to set the flow metric to a maximum average correlation number during a single pump stroke.

19. The system of claim 15, wherein the controller is adapted and programmed to display for a user the flow metric during the course of each blood pump fill-stroke.

20. A system for controlling fluid flow in a hemodialysis apparatus comprising:

a dialysate pump constructed and arranged to receive a fluid from a dialysate outlet of a dialyzer;

a blood pump comprising a reciprocating diaphragm constructed and arranged to deliver blood from an extracorporeal blood circuit to a blood inlet of the dialyzer, a pumping chamber of the blood pump separated from a control chamber of the blood pump by a flexible diaphragm, the control chamber constructed and arranged to contain a control fluid at a positive or a negative pressure in contact with the diaphragm;

a pressure sensor constructed and arranged to measure a pressure of the control fluid contained in the control chamber of the blood pump;

a controller adapted and programmed to receive information from the pressure sensor, and programmed to operate a valve connecting a source of the control fluid to the control chamber of the blood pump;

wherein the controller is adapted and programmed to control the valve to generate a time-varying pressure waveform of the control fluid in the control chamber during a fill-stroke of the blood pump and to monitor a resulting pressure variation in the control chamber, and

wherein the controller is adapted and programmed to initiate a procedure able to select from;

adjusting, pausing, and stopping the dialysate pump if a magnitude of the measured pressure variation deviates from a pre-determined value.

21. The system of claim 20, wherein the controller is adapted and programmed to compare the resulting pressure variation in the control chamber with a target pressure variation, and wherein a deviation between the resulting pressure variation and the target pressure variation that is greater than a pre-determined difference value causes the controller to initiate the procedure able to select from:

adjusting, pausing, and stopping the dialysate pump.

22. The system of claim 20, wherein the controller is adapted and programmed to compare the measured pressure in the control chamber with a target pressure during time periods when an absolute value of the applied pressure is decreasing, and wherein a deviation between the measured pressure and the target pressure that is greater than a pre-determined difference value causes the controller to initiate the procedure able to select from:

adjusting, pausing, and stopping the dialysate pump.

23. The system of claim 21, wherein the comparison by the controller comprises calculating a cross-correlation value between the measured pressure variation and the target pressure variation, and wherein a cross-correlation value that is less than a pre-determined cross-correlation value causes the controller to initiate the procedure able to select from:

adjusting, pausing, and stopping the dialysate pump.

24. The system of claim 23, wherein the calculated cross-correlation value comprises a phase-insensitive cross-correlation value.

25. The system of claim 23, wherein the controller is adapted and programmed to initiate the procedure able to select from:

adjusting, pausing, and stopping the dialysate pump only if the calculated cross-correlation value is less than the pre-determined cross-correlation value for two or more consecutive blood pump fill-strokes.

26. The system of claim 23, wherein the controller is adapted and programmed to calculate a filtered or averaged cross-correlation value during a fraction of a pump fill-stroke period and re-calculate one or more additional filtered or averaged cross-correlation values during one or more successive fractions of the fill-stroke period, and wherein the controller is further adapted and programmed to compare a highest valued filtered or averaged cross-correlation value during said fill-stroke period with a pre-determined filtered or averaged cross-correlation value to determine whether to initiate the procedure able to select from:

adjusting, pausing, and stopping the dialysate pump.

27. The system of claim 20, wherein the time-varying pressure waveform comprises a sinusoidal pressure waveform.

28. The system of claim 20, wherein the valve comprises a variable restriction valve.

29. The system of claim 28, wherein the source of control fluid comprises a source of positively or negatively pressurized gas.

30. The system of claim 20, wherein the dialysate pump comprises a reciprocating diaphragm, and wherein the pre-determined value is based on a pressure over a period of time generated by the blood pump during a normal or full-flow pumping condition.

31. The system of claim 20, wherein the controller is adapted and programmed to be able to selectively pause or stop the dialysate pump while allowing the blood pump to continue to operate if a flow metric based on the deviation of the magnitude of the measured pressure variation from the pre-determined value exceeds a pre-determined flow metric value.

32. The system of claim 20, wherein the controller is adapted and programmed to calculate a flow metric comprising a measure of a variation of a peak-to-peak magnitude of the measured pressure.

33. The system of claim 32, wherein the controller is adapted and programmed to normalize the measured variation of the peak-to-peak magnitude to an expected or pre-determined peak-to-peak pressure variation, or a peak-to-peak pressure variation obtained during a nominal or full flow condition.

34. The system of claim 20, wherein the controller is adapted and programmed to calculate a flow metric based on a cross-correlation of a desired, expected or nominal pressure and the measured pressure.

35. The system of claim 34, wherein the flow metric is based on a phase insensitive cross-correlation of the desired, expected or nominal pressure and the measured pressure.

36. The system of claim 34, wherein the controller is adapted and programmed to set the flow metric to a correlation number derived from the cross-correlation while the diaphragm of the blood pump is moving, and to hold the flow metric at a value reached before the diaphragm reaches an end of its stroke.

37. The system of claim 34, wherein the controller is adapted and programmed to set the flow metric to a maximum average correlation number during a single pump stroke.

38. The system of claim 34, wherein the controller is adapted and programmed to display for a user the flow metric during the course of each blood pump fill-stroke.