DETERMINING PRESSURE

• US 20110054810A1
• Filed: 06/20/2008
• Published: 03/03/2011
• Est. Priority Date: 08/06/2007
• Status: Abandoned Application

• Current Assignee: Smith & Nephew PLC
• Original Assignee: Smith & Nephew PLC
• Inventors: Turner, Jake, Gordon, Benjamin
• Application Number:
  US12/672,065
• Publication Number:
  US 20110054810A1
• Time in Patent Office: Days
• US Class Current: 702/47
• CPC Class Codes: A61M 1/73 comprising sensors or indicators for physical values
• CPC Class Codes: A61M 1/74 Suction control underwater drainage A61M1/61
• 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 1/982 with means for detecting level of collected exudate
• CPC Class Codes: A61M 2205/3331 Pressure; Flow
• CPC Class Codes: A61M 2205/3365 Rotational speed

Abstract

A method and apparatus are disclosed for determining a pressure in a topical negative pressure (TNP) system. The method includes the steps of determining a pumping speed associated with a pump element of a TNP system, determining a flow rate in a flow path associated with the pump element and determining pressure in the flow path responsive to the pumping speed and flow rate.

Claims

1. A method of determining pressure in a topical negative pressure (TNP) system, comprising the steps of:

determining a pumping speed associated with a pump element of a TNP system;

determining a flow rate in a flow path associated with the pump element; and

determining pressure in the flow path in relation to the pumping speed and flow rate.

2. The method as claimed in claim 1, further comprising the steps of:

determining the flow rate by measuring flow rate via a flow meter.

3. The method as claimed in claim 1 wherein the flow rate comprises a load on the pump element.

4. The method as claimed in claim 1 wherein the step of determining the pumping speed comprises the steps of:

determining an electromotive force (EMF) generated by a free-wheeling element of the pump element; and

calculating the pumping speed responsive to the generated EMF.

5. The method as claimed in claim 1, further comprising the steps of:

determining if the determined pressure is within a predetermined operating range; and

generating at least one of an audible and visible alarm cue if the determined pressure exceeds an upper range limit or falls below a lower range limit.

6. The method as claimed in claim 1 further comprising the steps of:

periodically varying pump speed responsive to the determined pressure;

re-determining the flow rate subsequent to each step of varying pump speed; and

re-determining pressure in the flow path.

7. The method as claimed in claim 1 wherein the step of determining pressure comprises the steps of:

determining pressure at an inlet location of the pump element.

8. The method as claimed in claim 1, further comprising determining pressure in the flow path by the steps of:

determining a pump speed or flow rate;

indexing a look-up table responsive to the determined pump speed or flow rate; and

determining a pressure by indexing a pressure value associated with a value of a remainder of the pump speed or flow rate in the indexed look-up table.

15. The method as claimed in claim 1, wherein determining pressure in the flow path comprises:

selecting a look-up table based on the determined pump speed; and

determining pressure by selecting a pressure value associated with the determined flow rate in the selected look-up table.

16. The method as claimed in claim 1, wherein determining pressure in the flow path comprises:

selecting a look-up table based on the determined flow rate; and

determining pressure by selecting a pressure value associated with the determined pump speed in the selected look-up table.

9. Apparatus for determining pressure in a topical negative pressure (TNP) system, comprising:

a pump element, that provides negative pressure in a flow path;

a flow meter arranged to determine a flow rate in the flow path; and

a processing unit configured to;

determines a pumping speed associated with the pump element; and

determines pressure in the flow path in relation to the pumping speed and flow rate.

17. The apparatus as claimed in claim 9 wherein the processing unit is configured to determine pressure in the flow path by the steps comprising:

select a look-up table based on the determined pump speed; and

determine pressure by selecting a pressure value associated with the determined flow rate in the selected look-up table.

18. The apparatus as claimed in claim 9 wherein the processing unit is configured to determine pressure in the flow path by the steps comprising:

select a look-up table based on the determined flow rate; and

determine pressure by selecting a pressure value associated with the determined pump speed in the selected look-up table.

10. The apparatus as claimed in claim 10 wherein the flow path comprises:

a connection tube connecting the pump element to a canister of the TNP system; and

an aspirant tube connected to the canister and locatable at a wound site.

11. The apparatus as claimed in claim 10, further comprising:

a pulse width modulation (PWM) generator that provides an output signal which provides a drive voltage for the pump element and which receives a control signal that selectively disconnects the pump element from the drive voltage.

12. The apparatus as claimed in any one of claim 10, further comprising:

the processing unit calculates an electromotive force (EMF) generated by a free-wheeling rotor element and calculates pumping speed responsive to the EMF.

13. (canceled)

14. (canceled)