Systems and methods for controlling operation of a reduced pressure therapy system

• US 8,905,985 B2
• Filed: 11/02/2011
• Issued: 12/09/2014
• Est. Priority Date: 09/20/2010
• Status: Active Grant

• Current Assignee: Smith & Nephew PLC
• Original Assignee: Smith & Nephew PLC
• Inventors: Allen, Julie, Askem, Ben Alan, Collinson, Sarah Jenny, Hughey, Richard Thomas, Nicolini, Derek
• Primary Examiner(s): Zalukaeva, Tatyana
• Assistant Examiner(s): Mensh, Andrew J
• Application Number:
  US13/287,959
• Publication Number:
  US 20120136325A1
• Time in Patent Office: 1,133 Days
• Field of Search: 604/319, 604/317, 604/318, 604/326
• US Class Current: 604/319
• CPC Class Codes: A61F 13/05 specially adapted for use with sub-pressure or over-pressure therapy, wound drainage or wound irrigation, e.g. for use with negative-pressure wound therapy [NPWT]
• CPC Class Codes: A61F 2013/00174 possibility of applying pressure
• CPC Class Codes: A61M 1/73 comprising sensors or indicators for physical values
• CPC Class Codes: A61M 1/732 Visual indicating means for vacuum pressure
• CPC Class Codes: A61M 1/74 Suction control underwater drainage A61M1/61
• CPC Class Codes: A61M 1/743 by changing the cross-section of the line, e.g. flow regulating valves A61M1/7413 takes precedence
• CPC Class Codes: A61M 1/75 Intermittent or pulsating suction A61M1/63, A61M1/772 take precedence
• CPC Class Codes: A61M 1/80 Suction pumps A61M1/64, A61M1/71, A61M60/00 take precedence
• CPC Class Codes: A61M 1/90 Negative pressure wound therapy devices, i.e. devices for applying suction to a wound to promote healing, e.g. including a vacuum dressing
• CPC Class Codes: A61M 1/96 Suction control thereof
• CPC Class Codes: A61M 1/966 having a pressure sensor on or near the dressing
• CPC Class Codes: A61M 1/985 the dressing itself forming the collection container
• CPC Class Codes: A61M 2205/15 Detection of leaks
• CPC Class Codes: A61M 2205/18 with alarm
• CPC Class Codes: A61M 2205/3344 Measuring or controlling pressure at the body treatment site
• CPC Class Codes: A61M 2205/42 Reducing noise
• CPC Class Codes: A61M 2205/8212 with means or measures taken for minimising energy consumption
• CPC Class Codes: A61M 39/22 Valves or arrangement of valves A61M39/02, A61M39/0247, A61M39/16 take precedence; regulating valves in infusion systems A61M5/16881; in devices worn by the patient for the reception of urine, faeces, catamenial or other discharge, or in colostomy devices A61F5/4405
• 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 5/48 having means for varying, regulating, indicating or limiting injection pressure A61M5/142 takes precedence ; monitoring pressure in infusion systems A61M5/16854

Abstract

Negative pressure wound therapy apparatuses and dressings, and systems and methods for operating such apparatuses for use with dressings are disclosed. In some embodiments, controlling the delivery of therapy can be based on monitoring and detecting various operating conditions. An apparatus can have a controller configured to monitor the duty cycle of a source of negative pressure and, based on the monitored duty cycle, determine whether a leak is present. The controller can be configured to provide an indication that a leak is present. For example, the controller can be configured to suspend and/or pause the delivery of therapy, and to restart the delivery of therapy due to a timeout, request from a user, etc. In addition, the controller can be configured to pause and/or restart the delivery of therapy upon a request from the user, such as in response to the user operating a switch.

Claims

1. An apparatus for applying negative pressure to a wound, comprising:

a source of negative pressure configured to be coupled to a dressing configured to be placed over the wound and to create a substantially fluid impermeable seal over the wound; and

a controller configured to;

activate the source of negative pressure to establish a desired negative pressure level under the dressing;

deactivate the source of negative pressure when a pressure level under the dressing has reached the desired negative pressure level;

in response to detecting a loss of negative pressure under the dressing due to a leak, periodically activate the source of negative pressure to restore the desired negative pressure level under the dressing;

monitor a plurality of duty cycles of the source of negative pressure over a plurality of time durations;

update a duty cycle metric of the source of negative pressure in response to comparing each duty cycle of the plurality of duty cycles to a duty cycle threshold; and

in response to determining that the duty cycle metric exceeds an overload threshold, indicate that the leak has a flow rate that exceeds a flow threshold.

26. The apparatus of claim 1, wherein the controller is configured to:

increment a counter when the controller determines that a duty cycle exceeds the duty cycle threshold; and

decrement the counter when the controller determines that the duty cycle does not exceed the duty cycle threshold.

27. The apparatus of claim 1, wherein the controller is further configured to continuously monitor the plurality of duty cycles over a plurality of consecutive and equal time durations.

28. The apparatus of claim 1, wherein the indication comprises deactivating the source of negative pressure.

29. The apparatus of claim 1, wherein the controller is further configured to:

if upon expiration of a first time interval, the pressure level under the dressing has not reached the desired negative pressure level, deactivate the source of negative pressure for a second time interval; and

upon expiration of the second time interval, activate the source of negative pressure to attempt to generate the desired negative pressure level under the dressing.

30. The apparatus of claim 29, wherein the controller is further configured to vary the second time interval based on a number of times the pressure level under the dressing has not reached the desired negative pressure level.

31. The apparatus of claim 30, wherein the controller is further configured to double the second time interval provided that a resulting value does not exceed a second interval threshold.

32. The apparatus of claim 30, wherein the controller is further configured to:

deactivate the source of negative pressure when the pressure level under the dressing has reached the desired negative pressure level; and

activate the source of negative pressure when the pressure level under the dressing rises above a negative pressure threshold, wherein the desired negative pressure level corresponds to a pressure that is more negative than the negative pressure threshold.

45. The apparatus of claim 1, wherein the apparatus does not comprise a waste canister.

2. An apparatus for applying negative pressure to a wound, comprising:

a source of negative pressure configured to be coupled to a dressing configured to be placed over the wound and to create a substantially fluid impermeable seal over the wound; and

a controller configured to;

activate the source of negative pressure to establish a desired negative pressure level under the dressing;

deactivate the source of negative pressure when a pressure level under the dressing has reached the desired negative pressure level;

in response to detecting a loss of negative pressure under the dressing due to a leak, periodically activate the source of negative pressure to restore the desired negative pressure level under the dressing;

monitor a duty cycle of the source of negative pressure; and

based at least on part on the monitored duty cycle, provide an indication that the leak has a flow rate that exceeds a flow threshold.

33. The apparatus of claim 2, wherein the duty cycle reflects an amount of time the source of negative pressure is active during a period of time.

34. The apparatus of claim 2, wherein the controller is further configured to:

monitor a number of duty cycles that exceed a duty cycle threshold; and

provide the indication if the number of duty cycles that exceed the duty cycle threshold exceeds an overload threshold.

35. The apparatus of claim 34, wherein the controller is configured to monitor the number of duty cycles that exceed the duty cycle threshold by:

incrementing a counter when the controller determines that a duty cycle exceeds the duty cycle threshold; and

decrementing the counter when the controller determines that the duty cycle does not exceed the duty cycle threshold.

36. The apparatus of claim 2, wherein the controller is further configured to monitor the duty cycle once per minute.

37. The apparatus of claim 2, wherein the controller is further configured to monitor the duty cycle by determining the duty cycle upon expiration of each time period of a plurality of time periods.

38. The apparatus of claim 2, wherein the indication comprises deactivating the source of negative pressure.

39. The apparatus of claim 2, wherein the controller is further configured to:

if upon expiration of a first time interval, a pressure level under the dressing has not reached the desired negative pressure level, deactivate the source of negative pressure for a second time interval; and

upon expiration of the second time interval, activate the source of negative pressure to attempt to generate the desired negative pressure level under the dressing.

40. The apparatus of claim 39, wherein the controller is further configured to vary the second time interval based on a number of times the pressure level under the dressing has not reached the desired negative pressure level.

41. The apparatus of claim 40, wherein the controller is further configured to double the second time interval provided that a resulting value does not exceed a second interval threshold.

42. The apparatus of claim 39, wherein the controller is further configured to:

deactivate the source of negative pressure when the pressure level under the dressing has reached the desired negative pressure level; and

activate the source of negative pressure when the pressure level under the dressing rises above a negative pressure threshold, wherein the desired negative pressure level corresponds to a pressure that is more negative than the negative pressure threshold.

43. The apparatus of claim 2, wherein the controller is further configured to deactivate the source of negative pressure if the duty cycle exceeds a duty cycle threshold without the pressure level under the dressing reaching the desired negative pressure level.

44. The apparatus of claim 2, wherein the controller is further configured to:

monitor a total elapsed time since an initial activation of the negative pressure source; and

disable the activation of the source of negative pressure when the total elapsed time reaches a lifetime threshold.

46. The apparatus of claim 2, wherein the apparatus does not comprise a waste canister.

3. A method for operating a source of negative pressure, comprising:

delivering negative pressure to a dressing positioned over a wound from the source of negative pressure;

stopping the delivery of negative pressure when a pressure level under the dressing has reached a desired negative pressure level;

periodically restarting the delivery of negative pressure to the dressing in response to detecting a loss of negative pressure under the dressing due to a leak;

monitoring a duty cycle of the source of negative pressure; and

based at least in part of the monitored duty cycle, providing an indication that the leak has a flow rate that exceeds a flow threshold.

4. The method of claim 3, wherein the duty cycle reflects an amount of time the source of negative pressure is active during a period of time.

5. The method of claim 3, further comprising:

monitoring a number of duty cycles that exceed a duty cycle threshold; and

providing the indication that the leak has a flow rate that exceeds the flow threshold if the number of duty cycles that exceed the duty cycle threshold exceeds an overload threshold.

6. The method of claim 5, further comprising monitoring the number of duty cycles that exceed the duty cycle threshold by:

incrementing a counter when the duty cycle exceeds the duty cycle threshold; and

decrementing the counter when the duty cycle does not exceed the duty cycle threshold.

7. The method of claim 5, wherein the overload threshold comprises 30.

8. The method of claim 4, wherein the period of time comprises 1 minute.

9. The method of claim 5, wherein the duty cycle threshold comprises 9%.

10. The method of claim 3, further comprising monitoring the duty cycle once per minute.

11. The method of claim 3, wherein the monitoring comprises determining the duty cycle upon expiration of each time period of a plurality of time periods.

12. The method of claim 3, wherein providing the indication comprises deactivating the source of negative pressure.

13. The method of claim 3, further comprising deactivating the source of negative pressure if the duty cycle exceeds a duty cycle threshold without the pressure level under the dressing reaching the desired negative pressure level.

14. The method of claim 3, further comprising:

if upon expiration of a first time interval, the pressure level under the dressing has not reached the desired negative pressure level, deactivating the source of negative pressure for a second time interval; and

upon expiration of the second time interval, activating the source of negative pressure to attempt to generate the desired negative pressure level under the dressing.

15. The method of claim 13, further comprising varying the second time interval based on a number of times the pressure level under the dressing has not reached the desired negative pressure level.

16. The method of claim 14, wherein the varying comprises doubling the second time interval provided that a resulting value does not exceed a second interval threshold.

17. The method of claim 13, further comprising:

deactivating the source of negative pressure when the pressure level under the dressing has reached the desired negative pressure level; and

activating the source of negative pressure when the pressure level under the dressing rises above a negative pressure threshold, wherein the desired negative pressure level corresponds to a pressure that is more negative than the negative pressure threshold.

18. The method of claim 3, further comprising monitoring pressure under the dressing with a sensor.

19. The method of claim 3, wherein delivering negative pressure to the dressing positioned over the wound from the source of negative pressure comprises delivering the negative pressure in response to receiving a signal from a switch.

20. The method of claim 3, wherein providing the indication comprises activating an indicator.

21. The method of claim 20, wherein activating the indicator indicates a leak in a seal over the wound.

22. The method of claim 3, further comprising:

monitoring a total elapsed time since an initial activation; and

disabling the activation of the source of negative pressure when the total elapsed time reaches a lifetime threshold.

23. The method of claim 22, wherein the initial activation comprises an initial activation of the source of negative pressure.

24. The method of claim 22, wherein the lifetime threshold comprises 7 days.

25. A method of operating a source of negative pressure, comprising:

delivering negative pressure to a dressing positioned over a wound from the source of negative pressure, wherein the delivering comprises;

activating the source of negative pressure to attempt to generate a desired negative pressure level under the dressing and updating a first count of activations;

if upon expiration of a first time interval, negative pressure under the dressing has not reached the desired negative pressure level, deactivating the source of negative pressure for a second time interval, provided that the first count of activations is less than a first retry threshold;

if the first count of activations is not less than the first retry threshold, deactivating the source of negative pressure for a third time interval, resetting the first count of activations, and, upon expiration of the third time interval, activating the source of negative pressure to attempt to generate the desired negative pressure level under the dressing;

activating the source of negative pressure upon expiration of the second time interval to attempt to generate the desired negative pressure level under the dressing and updating the first count of activations;

deactivating the source of negative pressure when the negative pressure under the dressing has reached the desired negative pressure level, resetting the first count of activations, and monitoring negative pressure under the dressing;

when negative pressure under the dressing rises above a negative pressure threshold, activating the source of negative pressure and updating a second count of activations, wherein the desired negative pressure level corresponds to a pressure that is more negative than the negative pressure threshold;

if before expiration of a fourth time interval negative pressure under the dressing has reached the desired negative pressure level, deactivating the source of negative pressure, monitoring negative pressure under the dressing, and resetting the second count of activations;

if upon expiration of the fourth time interval negative pressure under the dressing has not reached the desired negative pressure level, deactivating the source of negative pressure for the second time interval, provided that the second count of activations is less than a second retry threshold;

if the second count of activations is not less that the second retry threshold, deactivating the source of negative pressure for the third time interval, resetting the second count of activations, and, upon expiration of the third time interval, activating the source of negative pressure to attempt to generate the desired negative pressure level under the dressing and updating the first count of activations;

continuously monitoring a duty cycle of the source of negative pressure;

tracking a number of duty cycles that exceed a duty cycle threshold; and

deactivating the source of negative pressure for a duration of the third time interval when the number of duty cycles that exceed the duty cycle threshold exceeds an overload threshold.