Systems and methods for controlling operation of negative pressure wound therapy apparatus

• US 9,408,954 B2
• Filed: 08/17/2012
• Issued: 08/09/2016
• Est. Priority Date: 07/02/2007
• Status: Active Grant

• Current Assignee: Smith & Nephew PLC
• Original Assignee: Smith & Nephew PLC
• Inventors: Gordon, Benjamin, Turner, Jake, Hartwell, Edward, Jacob, Stephen, Wrench, Nathan, Vernon-Harcourt, Edward, Harris, David
• Primary Examiner(s): Zalukaeva, Tatyana
• Assistant Examiner(s): TREYGER, ILYA Y
• Application Number:
  US13/589,021
• Publication Number:
  US 20130150813A1
• Time in Patent Office: 1,453 Days
• US Class Current: 1/1
• CPC Class Codes: A61M 1/60 Containers for suction drainage, adapted to be used with an external suction source containers not adapted for subjection to vacuum A61M1/69
• CPC Class Codes: A61M 1/78 Means for preventing overflow or contamination of the pumping systems combined with drainage containers A61M1/60
• CPC Class Codes: A61M 1/784 by filtering, sterilising or disinfecting the exhaust air, e.g. swellable filter valves
• CPC Class Codes: A61M 1/96 Suction control thereof
• CPC Class Codes: A61M 1/962 having pumping means on the suction site, e.g. miniature pump on dressing or dressing capable of exerting suction
• CPC Class Codes: A61M 1/982 with means for detecting level of collected exudate
• CPC Class Codes: A61M 1/984 portable on the body
• CPC Class Codes: A61M 2205/15 Detection of leaks
• CPC Class Codes: A61M 2205/18 with alarm
• CPC Class Codes: A61M 2205/3331 Pressure; Flow
• CPC Class Codes: A61M 2205/3334 Measuring or controlling the flow rate
• CPC Class Codes: A61M 2205/3365 Rotational speed
• CPC Class Codes: A61M 2205/42 Reducing noise
• CPC Class Codes: A61M 2205/50 with microprocessors or computers
• CPC Class Codes: A61M 2205/502 User interfaces, e.g. screens or keyboards
• CPC Class Codes: A61M 2205/7536 allowing gas passage, but preventing liquid passage, e.g. liquophobic, hydrophobic, water-repellent membranes
• CPC Class Codes: A61M 2205/8206 battery-operated
• CPC Class Codes: A61M 2209/088 on the body

Abstract

Methods and apparatuses for detecting full waste canister and/or fluid flow path blockage conditions are disclosed. Also disclosed are methods and apparatuses for controlling a pump. In some embodiments, flow of fluid can be restricted in a portion of the fluid flow path. A controller can be configured to compare a difference in pressure values upstream and downstream of a fluid flow restrictor to a pressure difference threshold, and determine based on the comparison whether to activate an alarm indicating the full waste canister condition or the fluid flow path blockage condition. The controller can be additionally or alternatively configured to determine a fluid flow using a flow meter, open a selectable valve in response to a comparison of the fluid flow with a fluid flow threshold, determine fluid flow after opening the valve, and determine based on the fluid flow after opening the valve whether to activate the alarm.

Claims

1. A method of detecting a full waste canister condition and a fluid flow path blockage condition in a negative pressure wound therapy apparatus, the method comprising:

providing reduced pressure through a fluid flow path configured to be fluidically connected to a wound dressing, wherein the fluid flow path comprises a conduit and a waste canister;

determining a fluid flow rate in the fluid flow path,

detecting a presence of a blockage condition in the fluid flow path based on the determined flow rate; and

in response to detecting the presence of a blockage condition, determining whether the detected blockage condition comprises a full waste canister condition or a blocked conduit condition by opening and closing a valve positioned in the fluid flow path; and

providing an indication of a presence of the full waste canister condition or the blocked conduit condition.

2. The method of claim 1, further comprising:

providing the indication of the presence of the full canister condition or the blocked conduit condition with at least one of a visual indication, an audio indication, or a vibration indication.

3. The method of claim 1, wherein the valve is configured to admit ambient air into the fluid flow path.

7. The method of claim 1, wherein detecting a presence of a blockage condition in the fluid flow path comprises:

comparing the determined fluid flow rate to a fluid flow rate threshold; and

detecting the presence of a blockage condition when the fluid flow rate is less than the fluid flow rate threshold.

8. The method of claim 1, wherein detecting a presence of a blockage condition in the fluid flow path comprises:

comparing the determined fluid flow rate to a fluid flow rate threshold;

determining a pressure in the fluid flow path;

calculating a pressure difference between the determined pressure and a pressure setting;

comparing the calculated pressure difference to a threshold pressure difference; and

detecting the presence of a blockage condition when the fluid flow rate is less than the fluid flow rate threshold and the calculated pressure difference is less than the threshold pressure difference.

9. The method of claim 1, wherein determining whether a detected blockage condition comprises a full waste canister condition or a blocked conduit condition comprises:

determining a pressure in the fluid flow path before opening the valve;

determining a pressure in the fluid flow path after opening the valve;

comparing the determined pressures; and

determining that the detected blockage condition comprises a full waste canister condition when the determined pressures are approximately equal to each other and comprises a blocked conduit condition when the determined pressures are otherwise not approximately equal to each other.

10. The method of claim 1, further comprising:

restricting fluid flow through the fluid flow path via at least one of a fixed area flow restrictor or a variable area flow restrictor;

calculating a pressure difference between the fluid pressures upstream and downstream of the restriction;

detecting a presence of a blockage condition in the fluid flow path based partly on the calculated pressure difference; and

in response to detecting the presence of a blockage condition, determining whether a detected blockage condition comprises a full waste canister condition or a blocked conduit condition by comparing the pressure difference to a pressure difference threshold.

4. A negative pressure wound therapy apparatus comprising:

a negative pressure source configured to provide negative pressure to a wound dressing through a flow path, wherein the flow path comprises a conduit and a waste canister;

a valve located in the flow path; and

a controller configured to;

determine a fluid flow rate in the flow path;

detect a presence of a blockage condition in the flow path based on the determined fluid flow rate;

in response to detecting the presence of the blockage condition, determine whether the detected blockage condition comprises a full waste canister condition or a blocked conduit condition by causing the valve to open and close; and

provide an indication of the presence of the full canister condition or the blocked conduit condition.

5. The negative pressure wound therapy apparatus of claim 4, wherein the valve is configured to admit ambient air into the flow path.

6. The apparatus of claim 4, wherein the indication comprises one of a visual indication, an audio indication, or a vibration indication.

11. The apparatus of claim 4, wherein the controller is further configured to detect the presence of a blockage condition in the flow path based partly on the determined flow rate by:

comparing the fluid flow rate to a fluid flow rate threshold; and

detecting the presence of a blockage condition when the fluid flow rate is less than the fluid flow rate threshold.

12. The apparatus of claim 4, further comprising a pressure sensor configured to measure pressure in the flow path, and wherein the controller is further configured to detect the presence of a blockage condition by:

comparing the fluid flow rate to a fluid flow rate threshold;

determining a pressure in the flow path;

calculating a difference between the pressure and a pressure setting;

comparing the calculated difference to a threshold pressure difference; and

detecting the presence of a blockage condition when the fluid flow rate is less than the fluid flow rate threshold and the calculated difference is less than the threshold pressure difference.

13. The apparatus of claim 4, further comprising a pressure sensor configured to measure pressure in the flow path, and wherein the controller is further configured to determine whether a detected blockage condition comprises a full waste canister condition or a blocked conduit condition by:

determining a pressure in the flow path before opening the valve;

determining a pressure in the flow path after opening the valve;

comparing the determined pressures; and

determining that the detected blockage condition comprises a full waste canister condition when the determined pressures are approximately equal to each other and comprises a blocked conduit condition when the determined pressures are otherwise not approximately equal to each other.