Wireless pressure monitor for negative pressure treatment systems

Abstract

A wireless pressure sensor device for placement in a tissue site being treated with negative pressure wound therapy. The sensor monitors pressure at the tissue site and transmits data to a pump unit via a wireless connection, where it is used to control the delivery of negative pressure. The pressure sensor device may comprise a pressure sensor to measure the pressure in the interior of the pressure sensor device, and a second pressure sensor to measure a gauge pressure between the interior and exterior of the pressure sensor device.

Description

PA102060W002WIRELESS PRESSURE MONITOR FOR NEGATIVE PRESSURE TREATMENT SYSTEMSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority to U.S. Provisional Application No. 63 / 719,268, filed on November 12, 2024, which is incorporated herein by reference in its entirety.TECHNICAL FIELD

[0002] The following disclosure relates to monitoring the pressure at a tissue site bed during negative pressure treatment, and specifically to the use of a pressure sensor located at the tissue site to monitor that pressure.BACKGROUND

[0003] Clinical studies and practice have shown that reducing pressure in proximity to a tissue site can augment and accelerate growth of new tissue at the tissue site. The applications of this phenomenon are numerous, but it has proven particularly advantageous for treating wounds.Regardless of the etiology of a wound, whether trauma, surgery, or another cause, proper care of the wound is important to the outcome. Treatment of wounds or other tissue with reduced pressure may be commonly referred to as “negative -pressure therapy,” but is also known by other names, including “negative pressure wound therapy,” “reduced-pressure therapy,” “vacuum therapy,” “vacuum-assisted closure,” and “topical negative-pressure,” for example. Negative-pressure therapy may provide a number of benefits, including migration of epithelial and subcutaneous tissues, improved blood flow, and microdeformation of tissue at a wound site. Together, these benefits can increase development of granulation tissue and reduce healing times.

[0004] The effectiveness of negative pressure treatment is dependent on delivery of the desired pressure to the tissue site being treated. It is therefore helpful to be able to measure the pressure at the tissue site accurately. Existing pressure monitoring systems can be inaccurate or unreliable. For example, pressure differences may exist within a tissue site such that the common approach of monitoring at the point at which negative pressure is coupled into a wound dressing may not reflect the actual pressure at the bed of the tissue site. Also, wired pressure sensors can be unreliable and inconvenient due to the need for wires between a control system and the sensor.

[0005] There is therefore a need for an improved method and apparatus for monitoring pressure delivered to a tissue site.BRIEF SUMMARY

[0006] Aspects of the disclosure are set out in the following numbered clauses.

[0007] 1. A wireless pressure sensor device for use in a negative pressure treatment system, the sensor device comprising: a housing having a sealed interior space and a port; a first pressure sensor for sensing a pressure differential between the port and the sealed interior space of the housing; asecond pressure sensor for sensing the absolute pressure in the sealed interior space; a processor for obtaining measurements from at least the first and second pressure sensors; and a wireless communication interface for communicating data relating to the obtained measurements between the sensor device and a pump unit of the negative pressure treatment system via a wireless connection.

[0008] 2. A wireless pressure sensor device according to clause 1, wherein the data comprises pressure values measured by the first and second pressure sensors.

[0009] 3. A wireless pressure sensor device according to clause 1, wherein the data comprises the result of a calculation based on the pressure values measured by the first and second pressure sensors.

[0010] 4. A wireless pressure sensor device according to clause 3, wherein the calculation is the sum of the pressure values measured by the first and second pressure sensors to calculate the absolute pressure at the port.

[0011] 5. A wireless pressure sensor device according to any preceding clause, wherein the interior space is sealed from the port by at least part of the first pressure sensor.

[0012] 6. A wireless pressure sensor device according to any preceding clause, wherein the port is an opening in the housing.

[0013] 7. A wireless pressure sensor device according to any preceding clause, wherein the device further comprises at least one additional sensor for sensing a characteristic of a tissue site where the device is located.

[0014] 8. A wireless pressure sensor device according to any preceding clause, wherein the housing includes a removable battery cover which can be removed to position a battery within the interior space, the removable battery cover being sealed to the remainder of the housing when in a closed position.

[0015] 9. A negative pressure treatment system comprising a wireless pressure sensor device according to any of clauses 1 to 8, and a pump unit comprising: a source of negative pressure; a pump unit wireless communications interface configured to receive data from the wireless pressure sensor device via a wireless connection; and a processor configured to control the source of negative pressure based on the received data.

[0016] 10. A negative pressure treatment system according to clause 9, wherein the pump unit further comprises a third pressure sensor for measuring ambient pressure at the location of the pump unit, and wherein the processor is configured to control the source of negative pressure based at least in part on the ambient pressure.

[0017] 11. A negative pressure treatment system according to clause 9 or clause 10, wherein the processor is configured to control the source of negative pressure based on a calculation of the pressure at the tissue site relative to the ambient pressure.

[0018] 12. A negative pressure treatment system according to clause 11 , wherein the pressure at the tissue site is calculated at least in part at the pressure sensor device.

[0019] 13. A negative pressure treatment system according to clause 11 , wherein the pressure at the tissue site is calculated at the pump unit based on data received from the pressure sensor device indicating the pressure sensed by the first and the second pressure sensor and on data received from the third pressure sensor.

[0020] 14. A negative pressure treatment system according to any of clauses 9 to 13, wherein the wireless pressure sensor device is not physically connected to other elements of the system.

[0021] 15. A negative pressure treatment system according to any of clauses 9 to 14, wherein the wireless connection is provided via a wireless electronic device, wherein the pressure sensor device is in wireless communication with the wireless electronic device using a first link, and the wireless electronic device is in wireless communication with the pump unit using a second link.

[0022] 16. A negative pressure treatment system according to clause 15, wherein the first and second links use the same protocol.

[0023] 17. A negative pressure treatment system according to clause 15, wherein the first and second links use different protocols.

[0024] 18. A negative pressure treatment system according to any of clauses 9 to 17, the system comprising a plurality of wireless pressure sensor devices according to any of clauses 1 to 8.

[0025] 19. A method of controlling delivery of negative pressure to a tissue site, the method comprising the steps of: obtaining pressure measurements at the tissue using a pressure sensor device positioned at the tissue site, the pressure measurements comprising the pressure in a sealed interior space of the pressure sensor device and a gauge pressure between the sealed interior space and a port of the pressure sensor device; transmitting data relating to the pressure measurements from the pressure sensor device to the pump unit via a wireless connection; controlling a source of negative pressure for providing negative pressure to the tissue site based on the data received at the pump unit from the pressure sensor device.

[0026] 20. A method according to clause 19, further comprising controlling the source of negative pressure based on a measurement of ambient pressure local to the source of negative pressure.

[0027] 21. A method according to clause 19 or clause 20, wherein the source of negative pressure is controlled based on a calculation of the pressure at the tissue site relative to the measured local ambient pressure.

[0028] 22. A wireless pressure sensor device for use in a negative pressure treatment system, the sensor device comprising: a housing having a sealed interior space and a port; wherein part of the housing is formed from a flexible bellows, wherein an outside surface of the bellows is exposed to fluid external to the housing through the port such that the bellows can move depending on the pressure differential between the sealed interior space and the outside surface of the bellows; a first pressure sensor for sensing a pressure in the sealed interior space; a processor for obtaining measurements from at least the first pressure sensor; and a wireless communication interface forcommunicating data relating to the obtained measurements between the sensor device and a pump unit of the negative pressure treatment system via a wireless connection.

[0029] 23. A wireless pressure sensor device according to clause 22, wherein the port is an opening in the housing.

[0030] 24. A wireless pressure sensor device according to clause 22 or clause 23, wherein the device further comprises at least one additional sensor for sensing a characteristic of a tissue site where the device is located.

[0031] 25. A wireless pressure sensor device according to any of clauses 22 to 24, wherein the housing includes a removable battery cover which can be removed to position a battery within the interior space, the removable battery cover being sealed to the remainder of the housing when in a closed position.

[0032] 26. A negative pressure treatment system comprising a wireless pressure sensor device according to any of clauses 22 to 25, and a pump unit comprising: a source of negative pressure; a pump unit wireless communications interface configured to receive data from the wireless pressure sensor device via a wireless connection; and a processor configured to control the source of negative pressure based on the received data.

[0033] 27. A negative pressure treatment system according to clause 26, wherein the pump unit further comprises a pressure sensor for measuring ambient pressure at the location of the pump unit, and wherein the processor is configured to control the source of negative pressure based at least in part on the ambient pressure.

[0034] 28. A negative pressure treatment system according to clause 26 or clause 27, wherein the processor is configured to control the source of negative pressure based on a calculation of the pressure at the tissue site relative to the ambient pressure.

[0035] 29. A negative pressure treatment system according to any of clauses 26 to 28, wherein the wireless pressure sensor device is not physically connected to other elements of the system.

[0036] 30. A negative pressure treatment system according to any of clauses 26 to 29 the system comprising a plurality of wireless pressure sensor devices according to any of clauses 22 to 25.

[0037] 31. A negative pressure treatment system according to any of clauses 26 to 29, wherein the wireless connection is provided via a wireless electronic device, wherein the pressure sensor device is in wireless communication with the wireless electronic device using a first link, and the wireless electronic device is in wireless communication with the pump unit using a second link.

[0038] 32. A negative pressure treatment system according to clause 31, wherein the first and second links use the same protocol.

[0039] 33. A negative pressure treatment system according to clause 31, wherein the first and second links use different protocols.

[0040] 34. A method of controlling delivery of negative pressure to a tissue site, the method comprising the steps of: obtaining pressure measurements at the tissue using a pressure sensor devicepositioned at the tissue site, the pressure measurements comprising the pressure in a sealed interior space of the pressure sensor device, wherein the volume of the sealed interior space is dependent on the pressure differential between the sealed interior space and the pressure exterior to the pressure sensor device; transmitting data relating to the pressure measurements from the pressure sensor device to the pump unit via a wireless connection; controlling a source of negative pressure for providing negative pressure to the tissue site based on the data received at the pump unit from the pressure sensor device.

[0041] 35. A method according to clause 34, wherein the volume of the sealed interior space is varied by movement of a flexible bellows forming part of a housing of the pressure sensor device.

[0042] 36. A method according to clause 34 or clause 35, further comprising controlling the source of negative pressure based on a measurement of ambient pressure local to the source of negative pressure.

[0043] 37. A method according to any of clauses 34 to 36, wherein the source of negative pressure is controlled based on a calculation of the pressure at the tissue site relative to the measured local ambient pressure.BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure l is a block diagram of an example embodiment of a therapy system that can provide negative-pressure treatment and instillation treatment in accordance with this specification;

[0045] Figure 2 is a schematic diagram of a negative pressure treatment apparatus with pressure monitoring via a second lumen;

[0046] Figure 3 is a schematic diagram of a negative pressure treatment apparatus including a pressure sensor device at a tissue site;

[0047] Figure 4 is a schematic of an example of a pressure sensor device;

[0048] Figure 5 is a chart of example measurements using pressure sensor devices disclosed herein;

[0049] Figure 6 is a schematic diagram of an example of a pressure sensor device;

[0050] Figure 7 is a schematic diagram of an example of a pressure sensor device including a valve;

[0051] Figure 8 is a schematic diagram of an example of a pressure sensor device including a flexible bellows; and

[0052] Figure 9 is a block diagram of components of a pump unit and a pressure sensor device.DESCRIPTION OF EXAMPLE EMBODIMENTS

[0053] The following description of examples provides information that enables a person skilled in the art to make and use the subject matter set forth in the appended claims, but it may omit certain details already well-known in the art. The following detailed description is, therefore, to be taken as illustrative and not limiting.

[0054] Figure 1 is a block diagram of an example therapy system 100 that can provide negativepressure therapy with instillation of topical treatment solutions to a tissue site in accordance with this specification.

[0055] The term “tissue site” in this context broadly refers to a wound, defect, or other treatment target located on or within tissue, including, but not limited to, bone tissue, adipose tissue, muscle tissue, neural tissue, dermal tissue, vascular tissue, connective tissue, cartilage, tendons, or ligaments. A wound may include chronic, acute, traumatic, subacute, and dehisced wounds, partial thickness bums, ulcers (such as diabetic, pressure, or venous insufficiency ulcers), flaps, and grafts, for example. The term “tissue site” may also refer to areas of any tissue that are not necessarily wounded or defective but are instead areas in which it may be desirable to add or promote the growth of additional tissue. For example, negative pressure may be applied to a tissue site to grow additional tissue that may be harvested and transplanted. The surface of the patient within the tissue site being treated will be referred to as the tissue site bed.

[0056] The therapy system 100 includes a negative-pressure source 102, a dressing 104, and a container 106. The dressing 104 comprises a tissue interface 108 and a cover 110 such that negative pressure can be coupled from the negative pressure source 102 and maintained at the tissue site under the cover 110. The tissue interface 108 is optional but typically comprises a manifold to distribute negative pressure and fluids across the tissue site bed and facilitate removal of fluids from the tissue site. The tissue interface 108 may be an open cell foam. The tissue interface 108 may be sized and shaped to fit the contours of the tissue site or may be compressed to fit the tissue site and held in place by the cover 110. The cover is typically an elastomeric self-adhesive film, for example a polyurethane film, and is typically formed of a breathable, but liquid impermeable, material.

[0057] The therapy system 100 may also include a controller 112 to control delivery of negative pressure by the negative pressure source 102. A first pressure sensor 114 may be included to detect pressure in the container 106, and a second pressure sensor 116 may be included to detect the pressure delivered by the negative pressure source 102. These pressure sensors 114, 116 may be utilised by the controller 112 to control the negative pressure source 102. Other sensors may also be provided to monitor operating parameters of the system.

[0058] The therapy system 100 may also include a source of instillation solution. For example, a solution source 118 may be fluidly coupled to the dressing 104 and a pump 120 may be utilised to transfer liquid from the source 118 to the dressing 110. An instillation regulator 122 may be provided to control instillation of liquid. The instillation may also be controlled by controller 112.

[0059] The components of therapy system 100 may be combined into integrated elements and may be co-packaged or provided separately.

[0060] The controller 112 comprises a microprocessor or computer programmed to operate one or more components of the therapy system 100, such as the negative pressure source 102. The controller 112 may be a microcontroller, which generally comprises an integrated circuit containing a processor core and a memory programmed to directly or indirectly control the one or more elements of the therapy system 100. A function of the controller 112 is to control the negative pressure source 102 todeliver the desired negative pressure to the tissue site for which signals from one or more of the pressure sensors 114, 116 may be utilised in addition to settings made by the user.

[0061] In operation, the tissue interface 108 is placed within, over, on, or otherwise proximate to a tissue site and may partially or completely fill the tissue site. The cover 110 is placed over the tissue interface 108 and sealed to an attachment surface near a tissue site. For example, the cover 110 may be sealed to undamaged tissue (e.g. epidermis) peripheral to the tissue site. Thus, the dressing 104 can provide a sealed therapeutic environment proximate to the tissue site, substantially isolated from the external environment, and the negative-pressure source 102 can reduce pressure in the sealed therapeutic environment.

[0062] In conventional negative pressure systems, the negative pressure at the tissue site may be monitored using a pressure sensor located to sense pressure at the pump unit such as the first sensor 114 discussed above. The first sensor 114 may be fluidly coupled to the tissue site either via the same lumen used to apply negative pressure to the tissue site, or via a separate lumen which is coupled to the tissue site, for example by using a multi-lumen tube. The accuracy of such an arrangement can be limited due to the presence of liquid in the lumen between the sensor and the tissue site. Furthermore, the actual pressure at the point of coupling into the tissue site may be different to the pressure at the tissue site bed.

[0063] Figure 2 is a schematic diagram of selected components of a negative pressure treatment system of the type shown in Figure 1 using a conventional arrangement for monitoring negative pressure at the tissue site. Pressure at the tissue site is monitored using one or more pressure sensors 114a, 114b located at the pump unit 206. A controller 112 is electrically coupled to negative pressure source 102 such that the controller 112 can control the negative pressure supplied by the negative pressure source 102. The negative pressure source 102 is fluidly coupled to a canister 200 which in turn is fluidly coupled to the tissue site 202 by a lumen 204. A first pressure sensor 114a is fluidly coupled to the tissue site 202 via a second lumen 206, and a second pressure sensor 114b is fluidly coupled to monitor the pressure delivered to the canister 200 by the negative pressure source 102. Only one of the two pressure sensors 114a, 114b may be provided in some examples. In conventional systems the pressure sensors 114a and / or 114b are used by the controller 112 to control the negative pressure source 102 to deliver the desired negative pressure to the tissue site 202.

[0064] Pressure sensor 114a measures the pressure at the end 208 of the lumen 206, where it opens into the tissue site under the cover 110. This pressure at that point may not be representative of the pressure at the tissue site bed, which may be different due to the tissue interface 108 and the presence of liquids (for example exudate or instilled liquid) in the tissue site. This difference may be particularly significant for very large tissue sites, for example systems for treating abdominal sites. In such systems the tissue site, and tissue interface, may extend over a large area of the abdomen, and deep into gutters at the sides of the abdominal cavity. There can therefore be significant distance andobstruction between the end 208 of the lumen 206 and the tissue site bed which is where it is desired to monitor the actual pressure.

[0065] Figure 3 shows a negative pressure treatment system in which the actual pressure at the tissue site bed can be sensed and used to control the negative pressure source 102. By sensing the actual pressure at the tissue site bed, the pressure at that location can be controlled more accurately thus improving the match between the planned therapy and what is actually delivered to the tissue site.

[0066] As with the system of Figures 1 and 2, a pump unit 310 includes a negative pressure source 102 which is controlled by controller 112 to deliver negative pressure to container 300, which is coupled to the tissue site by tube 302. In this example tube 302 is a single-lumen tube and there is no additional lumen for monitoring pressure at the tissue site. Pressure sensor 114b may be provided to monitor the pressure delivered to the container 300. A pressure sensor device 304 is located at the tissue site bed to monitor the pressure at that location. The pressure sensor device 304 is in communication with the controller 112 by a wireless connection 306. The wireless connection may be provided by any appropriate protocol, for example Bluetooth or WiFi, or other protocols as discussed in more detail below. The pressure sensor device 304 may be paired with the pump unit 310 as appropriate for the particular wireless protocol utilised. The pairing process ensures that the pressure measurements are reported to the correct pump unit for the tissue site being monitored. The pressure sensor device 304 is a separate, standalone, component of the system which can be positioned in any desired location within the tissue site. As discussed herein, this provides advantages of previous systems in which sensors are provided within, or attached to, other elements of the systems and are therefore limited in where pressure can be sensed.

[0067] The pressure sensor device 304 monitors the pressure at the tissue site bed and communicates that pressure, optionally with other data, to the controller 112 via the wireless connection 306. The system may also include a further pressure sensor 308 for monitoring ambient (atmospheric) pressure at the location of the treatment system. As explained in greater detail below, the ambient pressure may be utilised in conjunction with measurements of the pressure sensor device 304 to determine the actual pressure at the tissue site bed.

[0068] The pressure device 304 can be located in the tissue site such that the pressure it measured as the desired location, thereby removing the need to adjust for differences between the measurement location and the treatment location. More than one pressure sensor device 304 may be used with a single pump unit, for example to monitor pressure at different locations within the tissue site. The controller 112 may be configured to utilise measurements from the pressure sensors 304 and control the negative pressure source 102 as most suits a particular system or tissue site. For example, the pump unit could be configured to control based on the average measurement of a number of pressure sensor devices 304, or the highest or lowest values.

[0069] Figure 4 shows a schematic diagram of elements of the pressure sensor device 304. A housing 400 is provided which is biocompatible to allow the device 304 to be positioned within tissuesites. The device 304 may be provided as a sterilised device or may be sterilised prior to use. In accordance with known construction techniques, the electronic components of the pressure sensor device 304 are mounted on a PCB 401 which is mounted securely within the housing 400, but any appropriate structure may be utilised. In this disclosure the principle electronic components of the sensor device 304 will be discussed, but as will be appreciated other components are also required to provide a functional device, which components can be provided as is known in the relevant technical field.

[0070] A pressure sensor 402 is mounted on PCB 401 and positioned to seal against the inner side of the housing 400 around sensing port 403. The seal may be provided by the pressure sensor itself, or using any appropriate seal which allows the pressure sensor 402 to sense the pressure at pressure sensing port 403 while keep the interior of the housing sealed. Pressure sensor 402 is a gauge type sensor which measures the differential pressure between two positions. In this example the pressure sensor is oriented to measure the pressure between the pressure sensing port 403 and the interior of the housing 400.

[0071] An absolute pressure sensor 404 is also provided to measure the pressure within the housing 400.

[0072] The pressure sensors 402 and 404 are electrically connected to the electronic system of the pressure sensor device 304, for example a processor and a communications interface, such that measurements can be communicated to the controller 112 via a wireless connection. The pressure sensor device 304 may be configured to communicate raw values for the pressure sensors, processed values, or to perform initial calculations before transmitting values to the controller 112. Any appropriate communication technique may be utilised. For example, the values could be transmitted immediately upon measurement or could be batched and transmitted as a set intermittently or conditionally upon a particular event occurring. For example, data may be transmitted after a certain period of time, or in response to a measurement passing a certain threshold.

[0073] The values from the pressure sensors 402 and 404 can be utilised to calculate the absolute pressure at the tissue site bed. Utilising the relevant reference numerals as subscripts to indicate the location of the value, P403 = P402 + P404. This can be stated as the pressure at sensing port 403 is equal to the gauge pressure measured by the sensor 402 plus the pressure inside the housing 400 as measured by the absolute sensor 404. As discussed above, the pressure sensor device 304 may be configured to transmitted individual values representing P402 and P404 to the controller 112 or may be configured to perform the noted calculation and transmit the resulting value.

[0074] In medical applications it is common to utilise pressures relative to the local ambient pressure (which is typically also the local atmospheric pressure). Since the pressure sensor device 304 is positioned within the tissue site and isolated from ambient pressure the device cannot measure or compensate for variation in the local ambient pressure to provide the preferred measurement. An ambient pressure sensor 308 may therefore be provided at the pump system 310 to measure theambient pressure local to the pump system 310 (which is typically the local atmospheric pressure) and can be used to adjust the measured values. The pressure at sensing port 403 can then be calculated as P403 = P402 + P404 -P308- This calculation provides the pressure at the sensing port 403 relative to the local ambient pressure. For this measurement, values less than zero indicate a pressure less than local ambient pressure, which is the normal operating regime for a negative pressure treatment system.

[0075] Figure 5 shows a graph of the various pressures discussed above to demonstrate their relationships. Figure 5 is intended to demonstrate the relationship of the values and they lead to measurement of the wound pressure, but the chart should be considered schematic and certain details may be lost. For example, in the region between 4 and 6 hours the internal pressure can be expected to reduce towards the wound pressure, but the change cannot be seen at the scale of Figure 5. In the example the wound pressure was controlled to oscillate between -125mmHg and -25mmHg. In this example the ambient pressure remains constant at OmmHg and so does not affect the calculations, but if that value changed it would be accounted for by the calculations discussed herein. The gauge pressure P402 (between the sensing port 403 and the interior of the pressure sensor device 304) trends towards atmospheric pressure while the wound pressure is less than the internal pressure by a decrease in the internal pressure P404 while the wound pressure remains constant. As shown by the line for P403 (wound pressure) the changes in internal pressure are compensated by the calculation process such that the wound pressure is calculated oscillating between -25 and -125mmHg.

[0076] In this example at the start the internal pressure in the pressure sensor device 304 is above atmospheric pressure as the pressure increased as the device was sealed, for example by the fitment of a battery compartment cover. Once the wound pressure has reduced to below atmospheric pressure the internal pressure then decreases towards the wound’s pressure due to a small leak in the device’s housing which allows air to pass out of, or into, the device. While the wound pressure is close to the internal pressure there is little further change of internal pressure, as the pressure differential to move air through the leak is small.

[0077] Figure 6 shows a cross-section of an example construction of a pressure sensor device 304 according to the current disclosure. As discussed previously the device comprises a housing 600 within which is mounted a PCB carrying various electronic components providing the functionality of the device. In particular, pressure sensor 602 senses the gauge pressure between the pressure at the sensor port 604 and the interior of the housing 600. Pressure sensor 605 senses the absolute pressure within the housing 600. A battery 606 is mounted within a battery compartment formed within the housing and closed by battery cover 608. A seal 610 is provided to seal the battery compartment to prevent entry of fluids while the pressure sensor is positioned at a tissue site. The housing 600 and battery cover 608 provide a sealed device, apart from the sensor port 604 the periphery of which is sealed to the pressure sensor 602. The pressure sensor device can therefore be positioned within a tissue site without contaminating the interior of the device, which may allow easier cleaning and reuse.

[0078] Figure 7 is a schematic cross-section of a pressure sensor device which is variation of the device shown in Figure 6. This example has the same features as the device of Figure 6, but a oneway valve 700 is also provided which permits air to easily leave the interior of the sensor device. In particular over-pressure created by fitting of the battery cover 608 is prevented because air is pushed out through the valve 700 if the interior pressure is greater than the pressure outside of the device. Similarly, when the device is placed in a tissue site and the pressure is reduced air can freely exit the interior of the device. If the tissue site pressure then increases, the pressure differential keeps the valve 700 closed and also creates a force to pressure the battery cover 608 pressed against the seal 610 to ensure the seal is good.

[0079] The interior of the sensor device can be evacuated using the valve to a pressure below that expected during operation of the device such that it is only required to measure positive pressures (pressure sensor 602 being a gauge pressure sensor measuring the difference in pressure between the interior of the device and the sensor pot 604) which may provide an improved selection of sensors compared to having to measure positive and negative gauge pressures.

[0080] Figure 8 shows a schematic cross-section of a further example pressure sensor device. In this example a single internal pressure sensor 605 is utilised to determine the actual pressure at the tissue site. The gauge pressure sensor is omitted in this example and a flexible bellows 800 seals across an opening 802 in the housing. Bellows 800 is configured to move in response to a pressure differential between the interior of the housing and the port 804. The pressure sensor device of Figure 8 may be simpler and lower cost to implement because only a single absolute pressure sensor is required in the pressure sensor device. However, accuracy may be reduced as liquids, such as wound exudate, may affect movement of the bellows, hence affecting the measurements. Similarly, calibrating the device to ensure the bellows movement is modelled accurately may be difficult and hard to perform to ensure calibration is not quickly lost. The pressure sensor 605 determines the tissue site pressure due to movement of the bellows 800 changing the volume and hence pressure within the housing. For this to provide an accurate measurement the bellows must be free to move to respond to changes in pressure and must do so predictably. Due to the environment at a tissue site neither of these may be possible due to impingement of liquids on the bellows. Furthermore, a change in pressure in the interior of the device (for example due to a leak) will affect the accuracy of the measurement as the sensor cannot distinguish between a pressure change due to movement of the bellows and due to air entering or leaving the interior of the device.

[0081] Figure 9 shows a simplified schematic diagram of the electronic elements of a pump unit 900 and pressure sensor device 902. The components included in Figure 9 are selected to explain the general structure and configuration of the system by reference to the main elements such that the skilled person can implement the examples using known techniques. The pump unit 900 comprises a negative pressure pump 904 for supplying negative pressure to a tissue site via a suitable fluidic connection. The pump 904 is controlled by processor 906 based on settings made by the user via userinterface 908, data held in memory 910, programming executed by the processor 906, sensors 912 (for example the ambient pressure sensor discussed hereinbefore), and measurements received via communications interface 914 from a pressure sensor device 902. Communications interface 914 is a wireless communication interface capable of establishing a wireless connection to a comparable interface 918 in one or more pressure sensor devices 902. Pressure sensor device 902 also comprises a processor 920, memory 922, and sensor(s) 924. In two examples the wireless connection may utilise Bluetooth or Wi-Fi technology to connect between the pump system 900 and pressure sensor device 902. The wireless connection could be unidirectional as it may only be necessary to communicate sensed values from the pressure sensor device 916 to the pump system 900, or the connection could be bidirectional. Any suitable communication technology can be utilised.

[0082] In an alternative example the wireless communication connection may be provided via a wireless electronic device, for example a mobile telephone. The pressure sensor device 916 may communicate with a wireless electronic device using an NFC protocol (or any suitable wireless protocol), and then the wireless electronic device may communicate with the pump system using the same or a different protocol. Such a system may allow the pump system to be positioned in a convenient location at a distance from the pressure sensor device, which distance would not allow a reliable direct wireless connection between the pressure sensor device and the pump unit. The wireless electronic device can be positioned in a convenient position closer to the pressure sensor device as it can be smaller and more portable than the pump unit to provide a link between the pressure sensor device and the pump unit. Such a configuration may be particularly beneficial where the pressure sensor device is positioned within a deep wound, such as an abdominal wound, where the patient’s body causes significant attenuation of the wireless signal. This avoids the need to increase the transmission power of the pressure sensor device which may increase the size and cost of the device.

[0083] In addition to the pressure sensor functionality discussed hereinbefore the pressure sensor devices discussed may also include other sensors such as temperature, humidity, pH, or any other sensor suitable for sensing parameters relevant to the operation of a negative pressure treatment system.

[0084] While shown in a few illustrative embodiments, a person having ordinary skill in the art will recognize that the systems, apparatuses, and methods described herein are susceptible to various changes and modifications that fall within the scope of the appended claims. Moreover, descriptions of various alternatives using terms such as “or” do not require mutual exclusivity unless clearly required by the context, and the indefinite articles “a” or “an” do not limit the subject to a single instance unless clearly required by the context. Components may also be combined or eliminated in various configurations for purposes of sale, manufacture, assembly, or use. For example, in some configurations the dressing 104, the container 106, or both may be eliminated or separated from othercomponents for manufacture or sale. In other example configurations, the controller 112 may also be manufactured, configured, assembled, or sold independently of other components.

[0085] The appended claims set forth novel and inventive aspects of the subject matter described above, but the claims may also encompass additional subject matter not specifically recited in detail. For example, certain features, elements, or aspects may be omitted from the claims if not necessary to distinguish the novel and inventive features from what is already known to a person having ordinary skill in the art. Features, elements, and aspects described in the context of some embodiments may also be omitted, combined, or replaced by alternative features serving the same, equivalent, or similar purpose without departing from the scope of the invention defined by the appended claims.

Claims

Claims1. A wireless pressure sensor device for use in a negative pressure treatment system, the sensor device comprising:a housing having a sealed interior space and a port;a first pressure sensor for sensing a pressure differential between the port and the sealed interior space of the housing;a second pressure sensor for sensing the absolute pressure in the sealed interior space;a processor for obtaining measurements from at least the first and second pressure sensors; and a wireless communication interface for communicating data relating to the obtained measurements between the sensor device and a pump unit of the negative pressure treatment system via a wireless connection.

2. A wireless pressure sensor device according to claim 1, wherein the data comprises pressure values measured by the first and second pressure sensors.

3. A wireless pressure sensor device according to claim 1, wherein the data comprises the result of a calculation based on the pressure values measured by the first and second pressure sensors.

4. A wireless pressure sensor device according to claim 3, wherein the calculation is the sum of the pressure values measured by the first and second pressure sensors to calculate the absolute pressure at the port.

5. A wireless pressure sensor device according to claim 1, wherein the interior space is sealed from the port by at least part of the first pressure sensor.

6. A wireless pressure sensor device according to claim 1, wherein the port is an opening in the housing.

7. A wireless pressure sensor device according to claim 1, wherein the device further comprises at least one additional sensor for sensing a characteristic of a tissue site where the device is located.

8. A wireless pressure sensor device according to claim 1, wherein the housing includes a removable battery cover which can be removed to position a battery within the interior space, the removable battery cover being sealed to the remainder of the housing when in a closed position.

9. A method of controlling delivery of negative pressure to a tissue site, the method comprising the steps of:obtaining pressure measurements at the tissue using a pressure sensor device positioned at the tissue site, the pressure measurements comprising the pressure in a sealed interior space of the pressure sensor device and a gauge pressure between the sealed interior space and a port of the pressure sensor device;transmitting data relating to the pressure measurements from the pressure sensor device to the pump unit via a wireless connection;controlling a source of negative pressure for providing negative pressure to the tissue site based on the data received at the pump unit from the pressure sensor device.

10. A method according to claim 9, further comprising controlling the source of negative pressure based on a measurement of ambient pressure local to the source of negative pressure.

11. A method according to claim 9, wherein the source of negative pressure is controlled based on a calculation of the pressure at the tissue site relative to the measured local ambient pressure.

12. A wireless pressure sensor device for use in a negative pressure treatment system, the sensor device comprising:a housing having a sealed interior space and a port;wherein part of the housing is formed from a flexible bellows, wherein an outside surface of the bellows is exposed to fluid external to the housing through the port such that the bellows can move depending on the pressure differential between the sealed interior space and the outside surface of the bellows;a first pressure sensor for sensing a pressure in the sealed interior space;a processor for obtaining measurements from at least the first pressure sensor; anda wireless communication interface for communicating data relating to the obtained measurements between the sensor device and a pump unit of the negative pressure treatment system via a wireless connection.

13. A wireless pressure sensor device according to claim 12, wherein the port is an opening in the housing.

14. A wireless pressure sensor device according to claim 12, wherein the device further comprises at least one additional sensor for sensing a characteristic of a tissue site where the device is located.

15. A wireless pressure sensor device according to claim 12, wherein the housing includes a removable battery cover which can be removed to position a battery within the interior space, the removable battery cover being sealed to the remainder of the housing when in a closed position.

16. A negative pressure treatment system comprising a wireless pressure sensor device according to claim 12, and a pump unit comprising:a source of negative pressure;a pump unit wireless communications interface configured to receive data from the wireless pressure sensor device via a wireless connection; anda processor configured to control the source of negative pressure based on the received data.

17. A negative pressure treatment system according to claim 16, wherein the pump unit further comprises a pressure sensor for measuring ambient pressure at the location of the pump unit, and wherein the processor is configured to control the source of negative pressure based at least in part on the ambient pressure.

18. A negative pressure treatment system according to claim 16, wherein the processor is configured to control the source of negative pressure based on a calculation of the pressure at the tissue site relative to the ambient pressure.

19. A negative pressure treatment system according to claim 16, wherein the wireless pressure sensor device is not physically connected to other elements of the system.

20. A negative pressure treatment system according to claim 16 the system comprising a plurality of wireless pressure sensor devices according to claim 12.

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