METHOD AND CONTROL SYSTEM FOR A WOUND THERAPY APPARATUS

Abstract

The present invention relates to a method (10) and control system (100) for monitoring operation of a pressure gradient wound therapy apparatus (200). A parameter indicative of a rate of change of pressure within the applied wound dressing (202) is measured, and a rate of change of pressure within the applied wound dressing (202) in is determined in dependence on the measured parameter. The rate of change of pressure corresponds to a leak level and is used to control the wound therapy apparatus (200) in accordance with one or more predetermined actions such that an appropriate action is taken for a given leak level.

Claims

1. A method for monitoring operation of a pressure gradient wound therapy apparatus, the method comprising: measuring a parameter indicative of a rate of change of pressure within the applied wound dressing; determining a rate of change of pressure within the applied wound dressing in dependence on the measured parameter, the rate of change of pressure corresponding to a leak level; comparing the determined rate of change of pressure to a plurality of leak thresholds to categorise the leak level into one of a plurality of leak level categories; and controlling the wound therapy apparatus in accordance with one or more predetermined actions in dependence on the leak level category.

2. The method as claimed in claim 1, comprising categorising the leak level into leak level categories corresponding to one or more of: a no leak category; a minor leak category; and a major leak category.

3. The method as claimed in claim 2, wherein one or more further leak level categories, including a medium or intermediate leak level category between a minor leak category and a major leak category.

4. The method as claimed in claim 1, comprising controlling an operating level of a component of the wound therapy apparatus in dependence on the leak level category.

5. The method as claimed in claim 4, wherein the component comprises a pump assembly of the wound therapy apparatus.

6. The method as claimed in claim 5, wherein, the operating level comprises a power output or motor speed of the pump assembly.

7. The method as claimed in claim 1, comprising outputting an indication to a user of the apparatus in dependence on the leak level category.

8. The method as claimed in claim 7, wherein the indication includes one or more of illuminating a light, controlling an associated display, and activating an alert to inform the user of the apparatus of the presence of a leak.

9. The method as claimed in claim 1, comprising controlling the wound therapy apparatus in accordance with one or more different instructions in dependence on the leak level category.

10. The method as claimed in claim 9, comprising: controlling the wound therapy apparatus in accordance with a first set of instructions in dependence on a determination of a leak level in a first leak level category; and controlling the wound therapy apparatus in accordance with a second set of instructions in dependence on a determination of a leak level in a second leak level category.

11. The method as claimed in claim 10, comprising controlling the wound therapy apparatus in accordance with a third set of instructions in dependence on a determination of a leak level in a third leak level category.

12. The method as claimed in claim 11, comprising controlling the wound therapy apparatus in accordance with a fourth set of instructions in dependence on a determination of a leak level in a fourth leak level category.

13. The method as claimed in claim 12, comprising: taking no action in dependence on a determination of a leak level in a no leak category; outputting an indication to a user of the apparatus in dependence on a determination of a leak level in a minor leak level category; controlling an operating level of a pump assembly of the wound therapy apparatus in dependence on a determination of a leak level in a medium leak level category; and preventing operation of the pump assembly in dependence on a determination of a leak level in a major leak level category.

14. The method as claimed in claim 1, comprising: comparing the rate of change of pressure to a first leak threshold and categorising the corresponding leak level in a first leak level category if the rate of change of pressure is below the first leak threshold; and categorising the corresponding leak level in a second leak level category if the rate of change of pressure is above the first leak threshold.

15. The method as claimed in claim 14, comprising: comparing the rate of change of pressure to a second leak threshold and categorising the corresponding leak level in a second leak level category if the rate of change of pressure is below the second leak threshold but above the first leak threshold; comparing the rate of change of pressure to a third leak threshold and categorising the corresponding leak level in a third leak level category if the rate of change of pressure is below the third leak threshold but above the second leak threshold; and categorising the corresponding leak level in a fourth leak level category if the rate of change of pressure is above the third leak threshold.

16. The method as claimed in claim 1, comprising comparing the determined rate of change of pressure with a rate of change of pressure observed at one or more preceding time periods.

17. The method as claimed in claim 16, comprising obtaining an average rate of change of pressure observed at a plurality of preceding time periods, and comparing the determined rate of change of pressure with the average rate of change of pressure observed at the plurality of preceding time periods.

18. The method as claimed in claim 1, wherein the parameter indicative of the rate of change of pressure within the applied wound dressing comprises a pressure value, and the method comprises: obtaining a first pressure value corresponding to the pressure within an applied wound dressing within a first time period; comparing the first pressure value with a second pressure value corresponding to the pressure within the applied wound dressing within a preceding time period to determine the rate of change of pressure within the applied wound dressing.

19. The method as claimed in claim 18, comprising obtaining a plurality of pressure values within the first time period, and obtaining an average of the plurality of pressure values obtained within the first time period to obtain the first pressure value.

20. The method as claimed in claim 18, comprising determining a rate of change of pressure within the wound dressing as follows: $Rate of change of pressure = .Math. \frac{P_{m} - P_{m - 1}}{T_{m} - T_{m - 1}} .Math.$ where P.sub.m is the first pressure value, P.sub.m-1 is the second pressure value, T.sub.m corresponds to a time stamp of the first time period, and T.sub.m-1 corresponds to a time stamp of the preceding time period.

21. The method as claimed in claim 1, comprising measuring the or each parameter indicative of a rate of change of pressure only when a pump assembly of the wound therapy apparatus is inactive.

22. The method as claimed in claim 1, wherein the parameter indicative of the rate of change of pressure within the applied wound dressing comprises, or is calculated from, a time value; and wherein the time value corresponds to the time between successive operating cycles of a pump assembly of the wound therapy apparatus.

23. The method as claimed in claim 22, comprising: measuring a time value corresponding to the time between the end of a first operating cycle of the pump assembly and the start of a second operating cycle of the pump assembly; and comparing the time value with a second time value corresponding to the length of time of an operating cycle of the pump assembly to determine a ratio of the time for which the pump assembly is not operating and the time for which the pump assembly is operating.

24. A control system control system for monitoring operation of a pressure gradient wound therapy apparatus, the control system comprising one or more controllers, the control system being configured to: receive an input signal indicative of a parameter indicative of a rate of change of pressure within the applied wound dressing; determine a rate of change of pressure within the applied wound dressing in dependence on the parameter, the rate of change of pressure corresponding to a leak level; compare the determined rate of change of pressure to a plurality of leak thresholds to categorise the leak level into one of a plurality of leak level categories; and output a control signal to control the wound therapy apparatus in accordance with one or more predetermined actions in dependence on the leak level category.

25. The wound therapy apparatus of claim 24, comprising a negative pressure wound therapy apparatus.

Description

DESCRIPTION OF THE FIGURES

[0114] In order that the invention may be more clearly understood one or more embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings, of which:

[0115] FIG. 1A is a flowchart illustrating an embodiment of a method of the invention;

[0116] FIG. 1B is a flowchart illustrating a further embodiment of a method of the invention;

[0117] FIG. 2 is a further flowchart illustrating an embodiment of a method of the invention;

[0118] FIG. 3 is a schematic view illustrating an embodiment of a control system of the invention;

[0119] FIG. 4 is a schematic view illustrating an embodiment of a wound therapy apparatus of the invention;

[0120] FIG. 5 is a flowchart illustrating a further embodiment of a method of the invention; and

[0121] FIG. 6 is a flowchart further illustrating the method shown in FIG. 5.

DETAILED DESCRIPTION

[0122] Embodiments disclosed herein relate to apparatus and methods of treating a wound with reduced or positive pressure (typically negative pressure), including pump and wound dressing components and devices. The devices and components may include a wound overlay and packing materials, which may be collectively referred to interchangeably herein as “dressings” or “wound dressings”.

[0123] As disclosed herein the present invention may comprise an apparatus for providing pressure gradient wound therapy to a wound, comprising: the technology disclosed herein, a wound dressing described herein; and a source of positive or negative pressure.

[0124] As used herein the expression “wound” may include an injury to living tissue may be caused by a cut, blow, or other impact, typically one in which the skin is cut or broken. A wound may be a chronic or acute injury. Acute wounds occur as a result of surgery or trauma. They move through the stages of healing within a predicted timeframe. Chronic wounds typically begin as acute wounds. The acute wound can become a chronic wound when it does not follow the healing stages resulting in a lengthened recovery. It is believed that the transition from acute to chronic wound can be due to a patient being immuno compromised.

[0125] Chronic wounds may include for example: venous ulcers (such as those that occur in the legs), which account for the majority of chronic wounds and mostly affect the elderly, diabetic ulcers (for example, foot or ankle ulcers), peripheral arterial disease, pressure ulcers, or epidermolysis bullosa (EB).

[0126] Examples of other wounds include, but are not limited to, abdominal wounds or other large or incisional wounds (either as a result of surgery, trauma, stemiotomies, fasciotomies, or other conditions), dehisced wounds, acute wounds, chronic wounds, subacute and dehisced wounds, traumatic wounds (such as from orthopaedic trauma), flaps and skin grafts, lacerations, abrasions, contusions, burns, diabetic ulcers, pressure ulcers, stoma, surgical wounds, trauma and venous ulcers, broken bones or the like.

[0127] Wounds may also include a deep tissue injury. Deep tissue injury is a term proposed by the National Pressure Ulcer Advisory Panel (NPUAP) to describe a unique form of pressure ulcers. These ulcers have been described by clinicians for many years with terms such as purple pressure ulcers, ulcers that are likely to deteriorate and bruises on bony prominences.

[0128] The technology disclosed can be used on an acute or chronic wound.

[0129] Wounds are believed to be more susceptible to infection under the following circumstances. If the wounds are chronic wounds, or if an object which caused the wound was dirty or contained bacteria, or from a bite, or contains remnant or a whole object that caused the wound, or a wound that is large or deep, or jagged edges to the wound, or elderly, or chronic because by their nature a wound site is open; and/or if the patient has: diabetes type 1 or type 2, is elderly, or has a compromised immune system.

[0130] Pressure gradient wound therapy may also be useful for treating second- and third-degree burns, as well as being useful for laparotomy surgery i.e., a large incision through an abdominal wall to gain access into the abdominal cavity.

[0131] In general, the invention relates to a method 10, 10′ and a control system 100 for monitoring (and in embodiments controlling) operation of a pressure gradient wound therapy apparatus, e.g. wound therapy apparatus 200.

[0132] FIG. 1A illustrates a first embodiment of a method 10.

[0133] At step 12, a first pressure value corresponding to the pressure within an applied wound dressing within a first time period is obtained. The first pressure value is obtained using one or more sensors, for example pressure sensors associated with a wound dressing of the wound therapy apparatus. The one or more sensors may be embedded within the wound dressing, and/or may be arranged about a periphery of the wound dressing, and/or may be associated with a pump assembly of the wound therapy apparatus.

[0134] The first pressure value can be an absolute pressure value within the applied wound dressing, or a relative pressure value within the applied wound dressing for example with reference to atmospheric pressure or to a desired or optimum pressure value for the wound dressing.

[0135] In an extension of method 10, step 12 comprises obtaining a plurality of pressure values within the first time period. Here, an average of the plurality of pressure values is calculated to obtain the first pressure value.

[0136] At step 14, the method 10 comprises comparing the first pressure value with a second pressure value corresponding to the pressure within the applied wound dressing within a preceding time period.

[0137] Again, the second pressure value is obtained using the one or more sensors. Similarly, the second pressure value can be an absolute pressure value within the applied wound dressing, or a relative pressure value within the applied wound dressing for example with reference to atmospheric pressure or to a desired or optimum pressure value for the wound dressing.

[0138] By performing this comparison at step 14, the method 10 is used to determine a rate of change of pressure within the applied wound dressing, specifically using Equation 1, repeated here as follows:

[00003] $\begin{matrix} Rate of change of pressure = .Math. \frac{P_{m} - P_{m - 1}}{T_{m} - T_{m - 1}} .Math. & [Equation 1] \end{matrix}$

[0139] where P.sub.m is the first pressure value, P.sub.m-1 is the second pressure value, T.sub.m corresponds to a time stamp of the first time period, and T.sub.m-1 corresponds to a time stamp of the preceding time period.

[0140] The rate of change of pressure corresponds to a leak level of the wound dressing. For instance, a high rate of change of pressure may correspond to the presence of a significant leak.

[0141] At step 16, the method 10 comprises comparing the determined rate of change of pressure to a plurality of leak thresholds. In doing so, the method may be used to categorise the leak level into one of a plurality of leak level categories. For instance, the plurality of leak level categories can include a no leak category; a minor leak category; and a major leak category. In the illustrated embodiment, the method 10 comprises at step 16 categorising the leak level into one of four categories, corresponding to a no leak category, a minor leak category, a medium leak category and a major leak category.

[0142] FIG. 2 illustrates the categorisation step 16 of method 10 in more detail.

[0143] Specifically, at step 20a the determined rate of change of pressure is compared to a first leak threshold. If the comparison indicates that the determined rate of change of pressure is less than or equal to the first leak threshold, the method 10 moves to step 20b where the leak level is categorised as no leak. Method 10 then moves to step 20c wherein the appropriate action is identified as “no action”.

[0144] If, however, the comparison at step 20a indicates that the determined rate of change of pressure is greater than the first leak threshold, the method 10 moves to step 22a where the determined rate of change of pressure is compared to a second leak threshold. If the comparison indicates that the determined rate of change of pressure is less than or equal to the second leak threshold, the method 10 moves to step 22b where the leak level is categorised as a minor leak. Method 10 then moves to step 22c wherein the appropriate action is identified as to output an indication of the leak to a user as described herein.

[0145] If, however, the comparison at step 22a indicates that the determined rate of change of pressure is greater than the second leak threshold, the method 10 moves to step 24a where the determined rate of change of pressure is compared to a third leak threshold. If the comparison indicates that the determined rate of change of pressure is less than or equal to the third leak threshold, the method 10 moves to step 24b where the leak level is categorised as a medium leak. Method 10 then moves to step 24c wherein the appropriate action is identified as to control a pump assembly of the wound therapy apparatus as described herein, for example to compensate for the leak.

[0146] If, however, the comparison at step 24a indicates that the determined rate of change of pressure is greater than the third leak threshold, the method 10 moves to step 26a, where it is confirmed that determined rate of change of pressure is greater than the third leak threshold. If so, the method 10 moves to step 26b where the leak level is categorised as a major leak. In such instances, an appropriate action is identified which here comprises preventing further operation of the pump assembly. This prevents the pump assembly being operated where it would not be able to provide the required pressure level due to the significance of the leak, thereby preventing excessive energy consumption and/or wear.

[0147] Following the categorisation step 16, the method 10 moves to step 18 which comprises controlling the wound therapy apparatus in accordance with one or more predetermined actions in dependence on the leak level category—e.g. the appropriate actions identified in step 16.

[0148] FIG. 1B illustrates a second embodiment of a method 10′ in accordance with the invention.

[0149] At step 12′, a time value is measured. Specifically, the method 10′ comprises measuring a time value corresponding to the time between successive operating cycles of a pump assembly of the wound therapy apparatus. Here, the pump assembly of the apparatus is configured to activate upon the pressure level inside the wound dressing reaching a first threshold level (e.g. an activation threshold level) and deactivate upon the pressure level inside the wound dressing reaching a second threshold level (e.g. a deactivation level). Accordingly, at step 12′ a time value corresponding to the time between the end of a first operating cycle of the pump assembly (e.g. upon deactivation of the pump assembly) and the start of a second operating cycle of the pump assembly (e.g. upon subsequent activation of the pump assembly) is measured. This time value then corresponds to the time taken for the pressure level within the wound dressing to change (e.g. drop) from the second threshold level to the first threshold level when the pump assembly is deactivated.

[0150] At step 14′, the measured time value is compared with a second time value corresponding to the length of time of an operating cycle of the pump assembly to determine a rate of change of pressure in the applied wound dressing. Specifically, the measured time value is compared with the second time value to obtain a ratio of the time for which the pump assembly is not operating and the time for which the pump assembly is operating, the ratio being indicative of a rate of change of pressure in the applied wound dressing.

[0151] Step 16′ comprises comparing the determined rate of change of pressure to a plurality of leak thresholds. This is performed in the same way as step 16 of method 10 as discussed above and illustrated in FIG. 2.

[0152] Following the categorisation step 16′, the method 10′ moves to step 18′ which comprises controlling the wound therapy apparatus in accordance with one or more predetermined actions in dependence on the leak level category—e.g. the appropriate actions identified in step 16′.

[0153] FIG. 3 illustrates an embodiment of a control system 100, which includes a controller 102 having a processor 104.

[0154] The processor 104 is operably coupled to an electrical input 106 for receiving an input signal 114. In use, the input signal 114 comprises data indicative of a first pressure value corresponding to the pressure within an applied wound dressing within a first time period. The input signal 114 may be received directly from a pressure sensor 215 (FIG. 4) associated with the wound dressing.

[0155] The controller includes memory device 110 electrically coupled to the processor 104 and includes instructions 112 stored therein. The instructions 112 may relate to operating instructions for controlling the operation of the wound therapy apparatus. In use, the processor 104 is configured to access the memory device 110 and execute the instructions 112 in order to generate a control signal 116 for controlling operation of the wound therapy apparatus. The control signal 116 is output via electrical output 108.

[0156] As discussed, the controller 102 is configured to receive the input signal 114 from a pressure sensor 215 (FIG. 4) associated with the wound dressing. The processor 104 is configured to analyse the input signal 114 to determine a rate of change of pressure within the wound dressing. Specifically, the processor 104 is configured to extract a first pressure value from the input signal 114 and compare the first pressure value with a second pressure value corresponding to the pressure within the applied wound dressing within a preceding time period to determine a rate of change of pressure within the applied wound dressing. The rate of change of pressure is indicative of a leak level from the wound dressing, so can be used to determine the significance or severity of any leaks present.

[0157] The comparison may be performed as per equation 1—repeated here as follows:

[00004] $\begin{matrix} Rate of change of pressure = .Math. \frac{P_{m} - P_{m - 1}}{T_{m} - T_{m - 1}} .Math. & [Equation 1] \end{matrix}$

[0158] where P.sub.m is the first pressure value, P.sub.m-1 is the second pressure value, T.sub.m corresponds to a time stamp of the first time period, and T.sub.m-1 corresponds to a time stamp of the preceding time period.

[0159] With the determined rate of change of pressure, the processor 104 is configure to compare the determined rate of change of pressure to a plurality of leak thresholds. The plurality of leak thresholds may be stored within the memory device 110, for example. On the basis of this comparison, the processor 104 categorises the leak level associated with the determined rate of change of pressure into one of a plurality of leak level categories. In the illustrated embodiment, the plurality of leak level categories include a no leak category; a minor leak category; a medium leak category; and a major leak category. As discussed herein, different actions may be appropriate depending on the leak level category.

[0160] Finally, the processor 104 is configured to generate and output a control signal 116 for controlling operation of the wound therapy apparatus in accordance with one or more predetermined actions. For example, depending on leak level category the processor 104 can output a control signal 116 for controlling operation of a pump assembly of the apparatus—e.g. to either control an operating characteristic of the pump, to prevent further operation of the pump, to output an indication to the user of the leak level or of the operating state of the pump, etc. —as appropriate for the level of leak from the wound dressing.

[0161] FIG. 4 illustrates a pressure gradient wound therapy apparatus 200 in accordance with the invention. The apparatus 200 includes a wound dressing 202 which may, for example be of the type available from ConvaTec Ltd. under the Avelle trade mark. The wound therapy apparatus 200 additionally includes a pump assembly 204 which may likewise, without pressure sensor 215, be of the type available from ConvaTec Ltd. under the Avelle trade mark.

[0162] The wound dressing 202 comprises a dressing body 206 and a peripheral adhesive layer 208. The dressing body 206 comprises an absorbent material and is positioned in contact with a wound, in use. The dressing body 206 is configured to absorb exudate from the wound, aided by the action of the pump assembly 204 creating a pressure differential between the interior of the wound dressing 202 and the surrounding environment. Here, the exudate is retained within the dressing body 206. Specifically, the dressing body 206 is formed of a hydrocolloid material which gels in the presence of exudate. This may be referred to as a “canister-less” system. In a variant, exudate removed from the wound may instead be withdrawn into an accompanying canister rather than being retained within the dressing body 206 itself. The adhesive layer 208 provides a seal between the dressing 202 and the user's skin, in use, defining an interior region of the wound dressing 202 about the wound.

[0163] The wound dressing 202 is fluidly connected to a pump 212 of the pump assembly 204 via a tube 210 which may likewise be of the type available from ConvaTec Ltd. under the Avelle trade mark. For positive pressure wound therapy, the pump 212 is configured to provide a source of air or other gas to be supplied to the interior portion of the wound dressing 202 to thereby increase the pressure within the wound dressing 202 relative to the surrounding environment. For negative pressure wound therapy, the pump 212 is configured to withdraw air from the interior portion of the wound dressing 202 to reduce the pressure within the wound dressing 202 relative to the surrounding environment.

[0164] The pump assembly 204 additionally includes indicators 214a, 214b, 214c consisting of lights which may be illuminated in dependence on the operational state of the pump 212 or indeed under instruction from the control system 100.

[0165] The apparatus 200 is controllable via control system 100.

[0166] Specifically, electrical input 106 of the controller 102 is operatively coupled to a pressure sensor 215 associated with the wound dressing 202. The pressure sensor 215 is provided within the pump assembly 204 and is configured to determine the pressure level within the wound dressing 202. The input signal 114 received from the pressure sensor 215 comprises data indicative of a first pressure value corresponding to the pressure within the wound dressing 202.

[0167] As discussed above, the processor 104 is configured to analyse the input signal 114 to determine a rate of change of pressure within the wound dressing 202 and compare the first pressure value with a second pressure value corresponding to the pressure within the applied wound dressing 202 within a preceding time period to determine a rate of change of pressure within the applied wound dressing 202 corresponding to a leak level from the wound dressing 202. From this, the leak level is then categorised and depending on the determined category for the observed leak level, the processor 104 is configured to generate and output the control signal 116 to the pump assembly 204 to control operation of the pump assembly 204 in accordance with one or more predetermined actions. For instance, the processor 104 can output a control signal 116 to an operating characteristic of the pump 212—e.g. to moderate its power output or a speed of a motor associated with the pump 212—or to prevent further operation of the pump 212. Additionally or alternatively, the processor 104 can output the control signal 116 to the pump assembly 204 to control operation of the indicators 214a, 214b, 214c to indicate to the user of the leak level or of the operating state of the pump 212.

[0168] Although shown separate in FIG. 4, it will be appreciated that in some embodiments two or more of the control system 100, wound dressing 202 and pump assembly 204 may be provided as a single unit, e.g. with the control system 100 and/or pump assembly 204 integrated within the wound dressing 202.

[0169] It will be appreciated that FIGS. 3 and 4 show a control system 100 and wound therapy apparatus 200, respectively, suitable for performing the method 10 shown in FIG. 1. However, it will further be appreciated that a similar arrangement may be used to perform the method 10′ of FIG. 2. Further, the control system 100 and wound therapy apparatus 200 may equally be operable to perform the method 300 of FIGS. 5 and 6 (discussed hereinbelow).

[0170] For instance, the processor 104 may be operable to receive an input signal 114 comprising data indicative of a time value corresponding to the time between successive operating cycles of the pump assembly 204 of the wound therapy apparatus 200. In such instances, the processor 104 may be configured to receive the input signal directly from a sensor (e.g. pressure sensor 215 or another sensor associated with the pump assembly 204) monitoring operation of the pump assembly 204. Alternatively, for instance where the control system 100 is operable to control operation of the pump assembly 204, the time value may be measured directly via the processor 104.

[0171] In this alternative arrangement, the processor 104 may be configured to analyse the input signal 114 (or use the directly measured time value) to determine a rate of change of pressure within the wound dressing. Specifically, the processor 104 is configured to determine the time between the end of a first operating cycle of the pump assembly 204 and the start of a second operating cycle of the pump assembly 204, and compare this time value with a second time value corresponding to the length of time of an operating cycle of the pump assembly 204 to determine a rate of change of pressure in the applied wound dressing 202. The rate of change of pressure is indicative of a leak level from the wound dressing 202, so can be used to determine the significance or severity of any leaks present.

[0172] With the determined rate of change of pressure, the processor 104 is configured to compare the determined rate of change of pressure to a plurality of leak thresholds as described herein to categorise the leak level associated with the determined rate of change of pressure into one of a plurality of leak level categories, and is configured to control operation of the wound therapy apparatus 200 in accordance with that categorisation as described herein.

[0173] FIGS. 5 and 6 illustrate a further embodiment of a method 300 in accordance with the invention.

[0174] The pump unit (e.g. the pump assembly 204) is initially provided in an “off” state (step 302). A user may activate the pump unit, for example, by pressing (and optionally holding) a button on the pump unit (step 304). The pump (e.g. pump 212) of the pump unit subsequently activates at step 306, here to reduce pressure within the applied wound dressing.

[0175] At step 308, a check is performed to determine whether the target pressure has been reached within a time period of 20 s. This is performed using a pressure sensor (e.g. sensor 215) associated with the wound dressing. The target pressure may be any suitable pressure value, but in the illustrated embodiment is set at −80 mmHg. If the target pressure is not reached within 20 s an output is provided in the form of a flashing first (e.g. red/amber) LED on the pump unit (step 310). The first LED may be one of indicators 214a, 214b, 214c of pump assembly 204, for example. Here, the first LED is flashed at a frequency of 5 beats per second to inform the user that the pump unit has been unable to achieve the target pressure. At step 312, a further check is performed, this time to determine whether the target pressure has been reached within a time period of 30 s. If the target pressure is not reached within 30 s the first LED is flashed at a frequency of 1 beat per second (step 314) before the pump unit is then switched off (step 302). This scenario may correspond to where a leak from the wound dressing is so great, or one or more components of the pump unit have malfunctioned, for example, such that the pump unit cannot reach the desired pressure level.

[0176] If either of the checks at step 308 or 312 return a positive response—i.e. the target pressure level has been reached within the wound dressing, the method moves on to step 316 where the pump of the pump unit is turned off, and at step 318 an indicator symbol (e.g. one of indicators 214a, 214b, 214c of pump assembly 204) on the pump unit is turned on to indicate to a user that the target pressure level has been reached. The indicator symbol preferably comprises a second LED on the pump unit—e.g. a green LED which may be permanently illuminated when the pressure level inside the wound dressing is acceptable and the pump of the pump unit is off.

[0177] Step 320 begins the pressure monitoring process of method 300. Specifically, the pressure within the wound dressing is monitored to check it is at the target pressure level (−80 mmHg), or within a predetermined range of the target pressure level (±20 mmHg). A check is performed at step 322 to determine whether the pressure within the wound dressing has dropped below −60 mmHg. If not, the method 300 loops back to step 318 where the indicator symbol is kept “on” before returning to step 320.

[0178] If the pressure within the wound dressing has dropped below −60 mmHg, the method 300 moves to step 324 where the pump of the pump unit is turned on. The method then proceeds through a series of steps to categorise the leak level from the wound dressing and take appropriate action. As is described herein, method 300 comprises measuring a time value indicative of the rate of change of pressure within the applied wound dressing. Specifically, the method 300 comprises measuring the time between successive operations of the pump unit to determine and subsequently categorise the leak level from the wound dressing.

[0179] At step 326, a check is performed to determine whether it has been less than 90 s between operations of the pump. If not, it is inferred that the pressure within the wound dressing has stayed within an acceptable range for longer than 90 s and the leak level is thus categorised in a no (or “acceptable”) leak category. At step 328, the indicator symbol is turned on (or kept on) to indicate an acceptable or no leak scenario.

[0180] If it has been less than 90 s since the previous operation of the pump unit, the method 300 moves to step 330 where a further check is performed to determine whether it has been less than 60 s between operations of the pump 212. If not, it is inferred that the pressure within the wound dressing has stayed within an acceptable range for between 60-90 s and the leak level is thus categorised in a minor leak category. The method 300 then comprises a series of steps (332a, 332b, 332s) to determine the number of times the determined leak level has been categorised as a minor leak. If this number is 19 or less, the method moves to step 336, wherein the indicator symbol is turned on (or kept on), but the first LED is flashed, here at a frequency of 1 beat per second. This indicates to the user that the pump unit is taking action to maintain the pressure level within the wound dressing, but there is a minor leak present. The user may then take steps to address the leak. Following this, the method moves back to steps 320, 322 etc. to repeat the pressure checks. If the determined leak level has been categorised as a minor leak 20 times (step 334), the method moves back to 314 where the first (red/amber) LED is flashed and the pump unit turned off to prevent excessive wear and energy usage of the pump. The second (green) LED would also be turned off in this instance.

[0181] Moving back to step 330, if it has been less than 60 s since the previous operation of the pump, the method 300 moves to step 340 where a further check is performed to determine whether it has been between 11-59 s since the previous operation of the pump. If so, it is inferred that the pressure within the wound dressing has stayed within an acceptable range for between 11-59 s and the leak level is thus categorised in a medium leak category. The method 300 then comprises a series of steps (342a, 342b, 342i) to determine the number of times the determined leak level has been categorised as a medium leak. If this number is 9 or less, the method moves to step 346, wherein the indicator symbol is turned on (or kept on), but the first LED is flashed, here at a frequency of 3 beats per second. This indicates to the user that the pump unit is taking action to maintain the pressure level within the wound dressing, but there is a medium leak present. This should prompt the user to take necessary steps to address the leak more urgently. Following this, the method moves back to steps 320, 322 etc. to repeat the pressure checks. If the determined leak level has been categorised as a medium leak 10 times (step 344), the method moves back to 314 where the first LED is flashed and the pump unit turned off to prevent excessive wear and energy usage of the pump. Again, the second (green) LED would also be turned off in this instance.

[0182] At step 350, a further check is performed to determine whether it has been less than 10 s since the previous operation of the pump. The outcome of this decision should always be “yes” given the checks performed at steps 326, 330 and 340. On the basis that is has been less than 10 s, it is inferred that the pressure within the wound dressing has only stayed within an acceptable range for less than 10 s and the leak level is thus categorised in a major leak category. The method 300 then comprises a series of steps (352a, 352b, . . . , 352d) to determine the number of times the determined leak level has been categorised as a major leak. If this number is 4 or less, the method moves to step 346, wherein the indicator symbol is turned on (or kept on), but the first LED is flashed, here at a frequency of 5 beats per second. This indicates to the user that the pump unit is taking action to maintain the pressure level within the wound dressing, but there is a major leak present that must be addressed as a matter of urgency. Following this, the method moves back to steps 320, 322 etc. to repeat the pressure checks. If the determined leak level has been categorised as a major leak 5 times (step 354), the method moves back to 314 where the first LED is flashed and the pump unit turned off to prevent excessive wear (e.g. of pump 212) and energy usage (e.g. of pump assembly 204).

[0183] In this way, method 300 controls the number of times the pump can be turned on (and hence the number of times the pump unit can operate) depending on the categorised leak level. This ensures that operation of the pump unit is limited more strongly for higher leak levels compared with lower leak levels. The different levels/frequencies at which the first LED is flashed dependent on leak level category is also designed to bring the leak level to the attention of the user—e.g. by flashing at a faster rate for higher leak levels. In an ideal scenario, a user would see the flashing indicator and take appropriate action to limit the leak from the wound dressing. If this is done in time—i.e. if this is done before 20 successive operations of the pump unit for a minor leak, before 10 successive operations of the pump unit for a medium leak, or before 5 successive operations of the pump unit for a major leak—the wound therapy apparatus may, as per method 300, continue to operate to provide the appropriate therapy. If, however, no appropriate action is taken to correct any leak, the method 300 ensures that the pump unit is prevented from operating so as to control the wear on, energy consumption of and noise generated by the wound therapy apparatus.

[0184] Conditional language, such as “can,” “could,” “might,” or “may,” unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements, and/or steps. Thus, such conditional language is not generally intended to imply that features, elements, and/or steps are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without user input or prompting, whether these features, elements, and/or steps are included or are to be performed in any particular embodiment.

[0185] Each of the documents referred to above is incorporated herein by reference. Except in Examples, or where otherwise explicitly indicated, all numerical quantities in this description specifying amounts of materials, device dimension, and the like, are to be understood as modified by the word “about.”

[0186] Unless otherwise indicated, each chemical or composition referred to herein should be interpreted as being a commercial grade material which may contain the isomers, by-products, derivatives, and other such materials which are normally understood to be present in the commercial grade.

[0187] The one or more embodiments are described above by way of example only. Many variations are possible without departing from the scope of protection afforded by the appended claims.

METHOD AND CONTROL SYSTEM FOR A WOUND THERAPY APPARATUS

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Cpc classification

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A61M2205/583

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A61M2205/3365

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A61M1/96

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A61M2205/3344

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A61M2205/0244

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A61F13/00068

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A61M2205/587

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A61M2205/581

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A61M2205/6063

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A61F13/0216

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A61M1/966

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A61M2205/276

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A61M2205/3331

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A61M2205/18

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A61M2205/15

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A61M1/985

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A61M1/00

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A61F13/00

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Abstract

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Description