Method and apparatus for leak detection in blood circuits combining external fluid detection and air infiltration detection

• US 20030126910A1
• Filed: 01/04/2002
• Published: 07/10/2003
• Est. Priority Date: 01/04/2002
• Status: Active Grant

• Current Assignee: Nxstage Medical Incorporated (Fresenius Medical Care AG)
• Original Assignee: Nxstage Medical Incorporated (Fresenius Medical Care AG)
• Inventors: Burbank, Jeffrey H.
• Granted Patent: US 7,040,142 B2
• Time in Patent Office: Days
• US Class Current: 73/40
• CPC Class Codes: A61M 1/3659 Cannulae pertaining to extracorporeal circulation
• CPC Class Codes: A61M 1/367 Circuit parts not covered by the preceding subgroups of group A61M1/3621
• CPC Class Codes: A61M 2205/15 Detection of leaks
• CPC Class Codes: G01M 3/26 by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors

Abstract

One of the most significant safety concerns in the automation of extracorporeal blood treatments such as dialysis is the risk of blood leakage. Extracorporeal blood treatment systems draw blood at such a high rate that a loss of integrity in the blood circuit can be catastrophic. There are a number of mechanisms for detecting and preventing leaks, but none is perfect. According to the present invention, the probability of a leak, its seriousness, the amount of time the leak condition has persisted without a response, and other factors may be used to control escalation of multiple types of alarms. In a simple embodiment, for example, there may be a staged audio signal that has a certain loudness and tonal quality when a leak is first detected and becomes more conspicuous as time goes by without a reset response from a user.

Claims

1. A method of detecting leaks in an extracorporeal blood circuit, comprising the steps of:

detecting fluid outside a first portion of a blood circuit;

detecting air inside a second portion of a blood circuit located remote from said first portion such that fluid is not detectable from said second portion;

generating an alarm signal responsively to a result of either or both of said steps of detecting.

2. A method as in claim 1, wherein said first step of detecting includes providing a fluid sensor below said circuit first portion and sensing a presence of blood with said sensor.

3. A method as in claim 1, wherein said second step of detecting includes applying a positive gauge pressure to said circuit during a first time and applying a negative pressure to said blood circuit during a second time.

4. A method as in claim 1, wherein said step of generating includes generating an alarm if either of said first and second steps of detecting results in an indication of a leak.

5. A method as in claim 1, wherein said second step of detecting includes periodically reversing a flow in said blood circuit.

6. A method as in claim 1, wherein said second step of detecting includes positioning a funnel with a fluid detector under a blood processing machine.

7. A method as in claim 1, wherein said second portion includes tubing linking a patient to a blood processing machine.

8. A method as in claim 7, wherein said first portion includes a portion of said blood circuit at least partially housed by a blood processing machine.

9. A method as in claim 8, wherein said step of detecting fluid includes directing a flow of fluid by gravity by means of a funnel to a fluid detector.

10. A leak detection system for an extracorporeal blood circuit, comprising:

a fluid detector located in a position to capture leaking blood from a first portion of said blood circuit;

a mechanism in said blood circuit to, at least periodically, create a negative pressure in all portions of a patient side of said blood circuit such that any leaks in said all portions will result in infiltration of air;

an air infiltration detector located to detect air infiltrating said second portion;

an alarm connected to both said air infiltration detector and said fluid detector and configured to generate an alarm signal if either said air infiltration detector or said fluid detector indicates a leak.

11. A device as in claim 10, further comprising a container positioned with respect to said fluid detector to guide blood leaking from said blood circuit toward said fluid detector.

12. A device as in claim 10, wherein said mechanism includes a device adapted to reverse flow in said blood circuit.

13. A device as in claim 12, wherein said device adapted to reverse flow includes a reversing valve.

14. A device as in claim 13, further comprising a funnel-shaped container positioned with respect to said fluid detector to guide blood leaking from said blood circuit toward said fluid detector located at a bottom of said container.

15. A device as in claim 14, wherein said funnel-shaped container is built into a housing of a blood processing machine of which said blood circuit is a part.

16. A device as in claim 10, wherein said air infiltration detector is a detector of the presence of air in said blood circuit.

17. A device for detecting leaks in a blood circuit, comprising:

a first leak detector that detects leaks by sensing blood outside said blood circuit, said first leak detector being located to detect leaks from a first portion of said blood circuit located remote from a patient;

a second leak detector that detects leaks by sensing air infiltration into lines under negative pressure;

said second leak detector being configured to detect leaks in lines connecting said patient to said first portion;

a mechanism that insures that at least part of said lines are under negative pressure at least part of the time during a treatment such that a detectable air infiltration indicates a presence of a leak in said lines;

an alarm device that outputs an alarm signal responsively to a detection of a leak by said first or second leak detector.

18. A device as in claim 17, wherein said second leak detector includes a fluid sensor below said circuit first portion.

19. A device as in claim 17, wherein said mechanism includes a flow-reversing valve in said blood circuit effective to reverse flow in said lines.

20. A device as in claim 17, where in said first leak detector is located below said first portion, said device further comprising a flow director to concentrate leaking fluid toward said first leak detector.

21. A method of detecting a fluid leak from a fluid processing machine, comprising the steps of:

detecting infiltration of air into a fluid circuit;

detecting leakage of fluid from said fluid circuit;

generating an alarm responsively to said first and second steps of detecting.

22. A method as in claim 21, wherein said step of generating includes generating an alarm when either of said steps of detecting indicates a leak.

23. A method as in claim 21, wherein said first step of detecting is restricted to detecting infiltration into a first part of said fluid circuit and said second step of detecting is restricted to detecting fluid leaking from a second part of said fluid circuit, said first and second parts having separate respective portions.

24. A method as in claim 21, wherein said first step of detecting includes generating a negative pressure in said fluid circuit.

26. A method as in claim 21, wherein said fluid is blood.

27. A method as in claim 21, wherein said fluid processing machine is an extracorporeal blood processing machine.

25. A method as in claim 25, wherein said step of generating includes reversing a flow of fluid.

28. A method of detecting a leak from a blood circuit of an extracorporeal blood treatment machine, comprising the steps of:

detecting leakage of blood from respective portions of a blood circuit;

said step of detecting including detecting different physical effects resulting from respective conditions associated with one or more leaks;

said respective portions including parts that are non-overlapping.

29. A method as in claim 28, wherein said step of detecting includes triggering an indicator of a leak responsively to a result of either of said respective different physical effects.

30. A method as in claim 29, further comprising at least one of clamping a fluid line, stopping a pump, or actuating a flow controller responsively to said indicator.

31. A method as in claim 29, further comprising triggering an alarm responsively to said indicator.

32. A method as in claim 28, wherein said different physical effects include the infiltration of air into a blood circuit and the presence of blood outside said blood circuit.

33. A method as in claim 32, further comprising controlling an output device responsively to said indicator.

34. A method as in claim 32, further comprising at least one of clamping a fluid line, stopping a pump, or actuating a flow controller responsively to said indicator.

35. A method as in claim 32, further comprising outputting an alarm signal responsively to said indicator.

36. A method as in claim 35, wherein said step of detecting includes triggering an indicator of a leak responsively to a result of either of said respective different physical effects.

37. A method as in claim 36, wherein said different physical effects include the infiltration of air into a blood circuit and the presence of blood outside said blood circuit.

38. A method as in claim 28, wherein said different physical effects include the infiltration of air into a blood circuit by periodically generating a negative pressure in said blood circuit and the presence of blood outside said blood circuit.

39. A method as in claim 38, wherein said step of generating includes reversing a flow of blood.

40. A method as in claim 28, wherein said different physical effects include the infiltration of air into a blood circuit by periodically reversing a flow of blood in said blood circuit using a reversing valve and the presence of blood outside said blood circuit.

41. A method as in claim 40, wherein said presence is detected using a sensor located inside a housing of said extracorporeal blood treatment machine.

42. A method as in claim 40, wherein said presence is detected by guiding and concentrating a leaking flow of blood toward a fluid sensor.

43. A device for detecting a fluid leak from a fluid processing machine, comprising the steps of:

an air detection sensor located to detect infiltration of air into a fluid circuit of said fluid processing machine;

a fluid detector located to detect a leakage of fluid from said fluid circuit;

an alarm connected to said sensor and said fluid detector and configured to output an alarm signal responsively to signals therefrom.

44. A device as in claim 43, wherein said alarm is adapted to output said alarm signal when either said sensor or said fluid detector indicates a leak.

45. A device as in claim 43, wherein said sensor is located to detect infiltration into a first part of said fluid circuit and said fluid detector is located to detect fluid from a second part of said fluid circuit, said first and second parts having separate respective portions.

46. A device as in claim 43, further comprising a mechanism adapted to generate a negative pressure in said fluid circuit to cause air to infiltrate into a breach in said fluid circuit.

47. A device as in claim 46, wherein said mechanism is adapted to reverse a direction of flow of fluid in said fluid circuit.

48. A device as in claim 43, wherein said fluid circuit is a blood circuit.

49. A device as in claim 43, wherein said fluid processing machine is an extracorporeal blood processing machine.

50. A device for detecting a leak from a blood circuit of an extracorporeal blood treatment machine, comprising the steps of:

respective detectors located to detect leaks of blood from respective portions of a blood circuit;

at least two of said respective detectors including sensors configured to detect different physical effects correlated with one or more blood leaks;

said respective portions including parts that are non-overlapping.

51. A device as in claim 50, further comprising an output device connected to receive signals from said respective detectors and to output a signal responsively thereto.

52. A device as in claim 51, further comprising at least one of a fluid line clamp, a pump, and an actuator of a flow controller, connected to be controlled by said output device responsively to said signal.

53. A device as in claim 51, further comprising an alarm connected to be triggered by said signal.

54. A device as in claim 50, wherein said different physical effects include the infiltration of air into a blood circuit and the presence of blood outside said blood circuit.

55. A device as in claim 54, further comprising an alarm connected to receive signals from said respective detectors and to output a signal responsively thereto.

56. A device as in claim 54, further comprising an output device connected to receive signals from said respective detectors and to output a signal responsively thereto and at least one of a fluid line clamp, a pump, and an actuator of a flow controller, connected to be controlled by said output device responsively to said signal.

57. A device as in claim 54, further comprising an output device connected to receive signals from said respective detectors and to output a signal responsively thereto and an alarm connected to generate an output responsively to said signal.

58. A device as in claim 57, wherein said output device and detectors are configured such that said signal indicates a leak if either of either of said respective different physical effects indicates a leak.

59. A device as in claim 58, wherein said different physical effects include the infiltration of air into a blood circuit and the presence of blood outside said blood circuit.

60. A device as in claim 59, wherein at least one of said detectors includes an air sensor and a mechanism adapted to periodically generate a negative pressure in said blood circuit such that air infiltrates said blood circuit through any openings therein.

61. A device as in claim 60, wherein said mechanism includes a mechanism adapted to reverse flow.

62. A device as in claim 50, further comprising a reversing valve, said different physical effects include the infiltration of air into said blood circuit caused by periodically reversing a flow of blood in said blood circuit using said reversing valve.

63. A device as in claim 62, wherein said detectors include a fluid sensor located inside a housing of said extracorporeal blood treatment machine.

64. A device as in claim 63, further comprising a flow guide adapted to guide and concentrate a leaking flow of blood toward said fluid sensor.