Patent Description:
Negative pressure wound therapy (NPWT) is a technique that promotes healing of e.g. surgical, acute, and chronic wounds by the application of a sub-atmospheric pressure to the wound, using a negative pressure pump. The NPWT technique also permits less outside disturbance of the wound as well as for transportation of excess fluids away from the wound site. Generally, the NPWT technique has until now mainly been applied to a patient while in a hospital environment. However, recent product development now allows the technique to be used by a patient in a home environment.

When an NPWT device is used in such a home environment, it may be possible that the NPWT device is not operated and monitored by professional users, as compared to when the NPWT device is used in the mentioned hospital environment. Thus, it is desirable to further simplify the operational use of the NPWT device, for minimizing any errors in use and handling.

Introducing the NPWT device in the home environment may in some situations have further implications on the patient and/or e.g. a partner of the patient. Specifically, when the negative pressure pump is operating, the pump may generate a noise that may be perceived as disturbing for the patient and/or the partner of the patient.

One example of an NPWT device trying to mitigate this problem is disclosed in <CIT>, where a direct current (DC) motor-driven pump comprised within a housing of the NPWT device is operated to achieve the negative pressure. In <CIT>, a vibration damping tape, e.g., visco-elastic damping tape, may be applied to an outer surface of the pump to reduce vibration and its associated noise. The pump may also be contained within a sub-housing arranged within the housing of the NPWT device, where the sub-housing may be hollow or formed entirely of open cell molded foam, e.g., used as a silencer to provide sound mitigation by reducing the sound energy of during operation of the pump.

The solution presented in <CIT>, specifically by arranging the pump within the mentioned sub-housing, generally reduces the level of noise generated during operation of the NPWT device. However, to achieve a desirable noise mitigating effect it will be necessary to introduce a substantial amount of the foam within the housing of the NPWT device, in turn result in a bulky NPWT device. Accordingly, there appears to be desirable to provide for other measures in mitigating the generated noise, while still ensuring that the NPWT device is safe to operate within the mentioned home environment.

Further attention is drawn to <CIT>, presenting a medical suction pump that comprises a pump housing, a pump assembly arranged in the pump housing and serving to generate an under pressure, and a device for sound damping. The device for sound damping has at least two elastic bearings for elastically supporting the pump assembly relative to the pump housing, wherein the bearings are arranged spaced apart from each other.

In view of above-mentioned and other drawbacks of the prior art, it is an object of the present disclosure to provide improvements in relation to efficient and safe operation of a NPWT device operating to establish a negative pressure within the sealed space formed by a wound cover in relation to a wound site.

According to an aspect of the present disclosure, it is therefore provided a removable enclosure for a mobile negative pressure wound therapy (NPWT) device as defined by claim <NUM>.

The present disclosure is based upon the realization that further measures are needed to ensure that the operation of the NPWT device does not disturb the patient and/or e.g. a partner of the patient. This is of specific importance during nighttime, when even in comparison low-level noise can be disturbing for the patient, and possibly the patient's partner if sharing the same bedroom. This is line with the present disclosure solved by providing the patient with a removable enclosure for the NPWT device, where the intention is to use the removable enclosure when the extra sound mitigation is needed. Nighttime usage of the removable enclosure is thus just an example of when such extra sound mitigation is advantageously applied. The combination of the forming the two housing sections from a combination of an outer shell material and an inner insulation material has surprisingly shown to greatly reduce the noise level of the NPWT device to such an extent that the patient and/or the partner of the patient do not perceived to be disturbed, even in a normal situation where the negative pressure pump is operation in an irregular manner (meaning that the noise level will be fluctuating over time).

It is generally desirable, but in some embodiments not absolutely necessary, to form the inner insulation material to match a shape of the NPWT device. The NPWT device will in such an embodiment have a "snug fit" to the inner insulation material, similar to how a camera may be positioned in a specifically adapted camera case. The combined insulation material for the first and the second housing section may in such an embodiment be formed to have a hollow portion towards the center of the removable enclosure, where the hollow portion matches the shape of the NPWT device.

Furthermore, since the operation of the NPWT device is in the mentioned home environment and not supervised by a skilled operator (such as e.g. a nighttime nurse), it is necessary to ensure that a sound indicative of a state of the NPWT device is still allowed to propagate to an outside of the removable enclosure. This is line with the present disclosure solved by introducing a sound duct extending through the outer shell material and the inner insulation material. The sound duct will thus at one end be positioned towards the NPWT device, and at the other end facing out of the removable enclosure. The end positioned towards the NPWT device is preferably arranged in relation to an area at the NPWT device where a volume of the sound generated by the sound generating device is as large as possible. Such an area may for example be defined by a sound outlet provided in a surface of the NPWT device, where the sound outlet possibly could be arranged to coincide with a position of the sound generating device at a printed circuit board (PCB) of the NPWT device.

It may however as an alternative be possible to allow the sound generating device to use a housing of the NPWT device to form part of the sound generating device. In such an embodiment it may thus be desirable to arrange the sound duct to engage and/or contact with the housing of the NPWT device.

To further heighten the sound mitigation effect of using the removable enclosure it may be desirable to ensure that the first housing section and the second housing section are adapted to at least partly overlap and to completely encloses the NPWT device. It is of course necessary to ensure that the conduit is allowed to pass through e.g. a wall of the first and/or the second housing section of the removable enclosure. Thus, the conduit should not be interpreted as forming part of the NPWT device. Rather, the conduit forms together with the NPWT device and a wound cover part of a wound treatment system as will be discussed below in relation to the detailed description.

In one embodiment it may be possible to arranged each of the first and the second housing section as an open box having five sides (an open top with a bottom and four walls). The second housing section may be made slightly larger as compared to the first housing section, where the openings are arranged towards each other when joined and where the first housing section is arranged partly within the second housing section. The first and the second housing section will thus together form a closed box, where one section can be seen as a lid and the other section as a bottom. It is as such desirable to arrange the lid to tightly fit to the bottom such that a minimal amount of noise is released at an interface between the bottom and the lid.

To ensure that the conduit is allowed to pass through the wall of the first and/or the second housing section of the removable enclosure it may accordingly be desirable to arrange the opening for passage conduit as a slot within the wall of the first and/or second housing section of the removable enclosure. The opening within the wall may alternatively be formed as a slit or a notch. The slot/slit/notch is desirably selected to ensure that the conduit is not "squeezed". Typically, a squeezed conduit could potentially reduce a suction power of the NPWT device.

It may in some embodiments be desirable to also introduce a slot within a wall of the second housing section, wherein the slots align when the first housing section and the second housing section are joined together. Such an embodiment may be implemented with a desire to ensure that the NPWT device is "correctly" positioned within the removable enclosure, ensuring that the NPWT device is tightly fitted within the removable enclosure and align with possible hollow portions of the respective first and second housing sections.

It may generally be desirable to select the outer shell material to be of paper or plastic. From a cost perspective it may be suitable to select a paper material, such as for example of cardboard. An outer shell material formed as a sandwich structure comprising a paper interior has shown specifically suitable to provide the noise mitigating effects as desired in accordance to the present disclosure. In one embodiment a thickness of the outer shell material is at least <NUM>.

As mentioned above, it is generally desirable to form the inner insulation material to match the shape of the NPWT device, thereby maximizing a volume of the inner insulation material provided within the removable enclosure when the removable enclosure is closed around the NPWT device. One type of suitable inner insulation material is a polymer material, such as for example having a cell structure. A possible suitable inner insulation material may as such be a foam material.

To achieve a desirable amount of noise damping it is in one embodiment preferred to select a thickness of the inner insulation material to be at least <NUM>, preferably at least <NUM>. The thickness of the inner insulation material may also as an alternative be selected depending on desired amount of attenuation of the noise from the negative pressure pump during its operation. In a preferred embodiment the attenuation of the noise from the negative pressure pump is at least <NUM> dBa, preferably at least <NUM> dBa.

As discussed above and defined in accordance to the present disclosure, the sound duct extending through the outer shell material and the inner insulation material of the second housing section. It may in some embodiments be desirable to reduce any sound damping effect of the inner insulation material by arranging the sound duct to comprise a duct material that is selected to be different from the inner insulation material. That is, if for example the inner insulation material is a foam material, the foam material may dampen sound waves propagating through the sound duct. Arranging a wall of the sound duct to have more dense material properties may greatly reduce such a dampening effect. However, the fact that the duct material that is selected to be different from the inner insulation material should be interpreted in the broadest sense, also including an embodiment where a material property of the inner insulation material has been altered. As an example of such an alteration, it could for example be possible to heat treat the inner insulation material at a surface towards the sound duct.

However, it may also be possible to line the sound duct with a material that has a lower sound dampening effect as compared to the inner insulation material, such as by providing an in comparison thin plastic film to the inner insulation material. As an alternative, the duct material may also or instead comprise a paper or plastic tube section. Using a paper tube section may have advantages from an environmental perspective. In a preferred embodiment a diameter of the sound duct is at least <NUM>, preferably at least <NUM>. The sound duct may have a circular cross section, but the cross section may of course be of any other shape (rectangular, triangular, etc.).

Turning now to the drawings and to <FIG> in particular, there is conceptually illustrated a wound treatment system <NUM>, comprising a NPWT device <NUM> in accordance with the present disclosure. The wound treatment system <NUM> further comprises a wound cover <NUM>, the wound cover <NUM> being adapted to create a sealed space <NUM> defined in part by a wound surface <NUM>, such as at the skin of a user/person, at or around a wound of the user/person. Additionally, the NPWT device <NUM> is fluidly connected to the wound cover <NUM> using e.g. a conduit <NUM>. The conduit <NUM> may be of any suitable flexible conduit fabricated from elastomeric and/or polymeric materials.

The NPWT device <NUM> in turn comprises a negative pressure pump <NUM> adapted for establishing a negative pressure when the negative pressure pump <NUM> is operable, i.e. in an active state. The negative pressure pump <NUM> may be any type of pump that is biocompatible and maintains or draws adequate and therapeutic vacuum levels. Preferably, the negative pressure level to be achieved is in a range between about -<NUM> mmHg and about -<NUM> mmHg. In a possible embodiment of the present disclosure, a negative pressure range between about -<NUM> mmHg and about -<NUM> mmHg is used. In a possible embodiment of the present disclosure, the negative pressure pump <NUM> is either a diaphragm pump or a peristaltic pump, or the like, in which the moving parts draw the mentioned fluid from the wound cover <NUM>.

The negative pressure pump <NUM> is fluidly connected to a canister <NUM>, the canister <NUM> also forming part of the NPWT device <NUM>. The canister <NUM> may be formed from e.g. molded plastic or the like, and possibly being a detachable component of the NPWT device <NUM>. As mentioned above, the canister <NUM> is preferably at least partly transparent/translucent to permit viewing into the interior of the canister <NUM> to assist the user in determining the remaining capacity of the canister <NUM>.

For ease of understanding of the following discussion of the present disclosure, it should be understood that the expressions "negative pressure", "sub-atmospheric pressure", "reduced pressure", as used interchangeably herein, generally refer to a pressure less than a local ambient pressure, such as the ambient pressure in a local environment external to a sealed therapeutic environment provided by a wound cover or dressing. In many cases, the local ambient pressure may also be the atmospheric pressure at which a patient is located. Unless otherwise indicated, values of pressure stated herein are gauge pressures. Similarly, references to increases in negative pressure typically refer to a decrease in absolute pressure, while decreases in negative pressure typically refer to an increase in absolute pressure.

An inlet port <NUM> is formed at the canister <NUM>, for allowing connection to the conduit <NUM>. The inlet port <NUM> may also be formed elsewhere at the NPWT device <NUM>, however still fluidly connected to the canister <NUM>. The connection between the inlet port <NUM> and the conduit <NUM> is a sealed connection, thus ensuring that no leakage is formed at the inlet port <NUM> during normal operation of the NPWT device <NUM>. The conduit <NUM> is preferably releasably connected to the inlet port <NUM> through conventional means including a friction fit, bayonet coupling, snap fit, barbed connector, or the like. The inlet port <NUM> may be molded/formed from the same material and/or at the same time as forming the canister <NUM>.

The NPWT device <NUM> further comprises a battery <NUM> for powering the NPWT device <NUM>. The battery <NUM> may preferably be of the rechargeable type but may alternatively be arranged to be disposable and thus to be changed once discharged. A specifically adapted battery pack may be used in relation to some embodiment of the present disclosure.

The NPWT device <NUM> also comprises a control unit <NUM>, electrically connected to the battery <NUM> and adapted to control an operation of the negative pressure pump <NUM>. The control unit <NUM> may include a microprocessor, microcontroller, programmable digital signal processor or another programmable device. The control unit <NUM> may also, or instead, each include an application specific integrated circuit, a programmable gate array or programmable array logic, a programmable logic device, or a digital signal processor. Where the control unit <NUM> includes a programmable device such as the microprocessor, microcontroller or programmable digital signal processor mentioned above, the processor may further include computer executable code that controls operation of the programmable device.

In line with the present disclosure, the NPWT device <NUM> further comprises a control circuitry <NUM> provided externally from the control unit <NUM> and arranged to generally control the operation of the negative pressure pump <NUM>, specifically for ensuring that the operation of the negative pressure pump <NUM> may be swiftly terminated in case the NPWT device <NUM> starts to operate outside of what is considered to be a normal behavior, as has been discussed above.

In addition, the NPWT device <NUM> comprises at least one pressure sensor <NUM> arranged in fluid connection with the negative pressure pump <NUM>.

During use of the NPWT device <NUM>, the wound cover <NUM> is arranged at a wound site of the user/patient, forming the sealed space <NUM>. The conduit <NUM> is provided to fluidly connect the wound cover <NUM> to the inlet port <NUM> of the NPWT device <NUM>. The NPWT device <NUM> is then activated, e.g. by the user/patient, for example by pressing a start button. When activated, the negative pressure pump <NUM> will start to evacuate air through the canister <NUM>, the inlet port <NUM>, the conduit <NUM> and the sealed space <NUM> formed by the wound cover <NUM>. Accordingly, the negative pressure will be created within the sealed space <NUM>. In case a liquid has been formed at the wound site, this liquid from the wound site may at least partly be "drawn" from the wound site, through the conduit <NUM>, the inlet port <NUM> and into the canister <NUM>. The amount of liquid (possibly defined as exudate) that is drawn from the wound and collected in the canister will depend on the type of wound that is being treated as well as the type of wound dressing used. For example, in case an absorbent dressing is used, the liquid may be absorbed and collected both in the canister and the wound dressing, whereas if a dressing with no or little absorption capacity is used most or all of the liquid from the wound site may be collected in the canister. A suitable filter member (not shown in <FIG>) is arranged between the canister <NUM> and the negative pressure pump <NUM> to ensure that no fluid is allowed to pass to the negative pressure pump <NUM> from the canister <NUM>.

In other embodiments (not shown), the NPWT device may be void of a canister, wherein the negative pressure pump is fluidly connected to an absorbent dressing which function to absorb all liquid drawn from the wound.

The NPWT device <NUM> may also, as indicated above comprise a speaker element <NUM> and thereto connected circuitry for driving the speaker element <NUM>, where the speaker element <NUM> is connected to the control unit <NUM>. The speaker element <NUM> is generally used for informing the patient of a specific state of the NPWT device <NUM>, such as in case there is some form of problem relating to the operation of the NPWT device <NUM>. Such an example may for example be an unwanted leakage in relation to the conduit <NUM> and/or the wound cover <NUM> or unwanted blockage of the conduit <NUM>, where the unwanted leakage or blockage is identified by the control unit <NUM>. The speaker element <NUM> will then be activated and adapted to play a specific and thereto related sound to inform the patient. Further possible dedicated informative sounds may relate to the canister <NUM> being full, the NPWT device <NUM> operating in an irregular manner, the battery <NUM> getting close to completely discharged, etc..

Furthermore, the wound treatment system <NUM> comprises the removable enclosure <NUM> according to the present disclosure, for reducing a level of noise generated during operation of the NPWT device <NUM>, such as when the negative pressure pump <NUM> is activated.

With further reference to <FIG>, <FIG>, the removable enclosure <NUM> comprises a first housing section <NUM> and a second housing section <NUM>. In the illustration as is shown in <FIG>, <FIG>, the first housing section <NUM> is shown as a bottom portion of the removable enclosure <NUM> and the second housing section as a lid portion of the removable enclosure <NUM>. The removable enclosure <NUM> is in <FIG> shown to have a rectangular shape with flat sides. It is of course possible to select any shape or form to achieve the desired effect according to the present disclosure.

The first housing section <NUM>, the bottom portion of the removable enclosure <NUM>, is formed from and comprises an outer shell material <NUM> made from paper and an inner insulation material <NUM> made from a polymer material that has a cell structure, such as a foam material. Other materials may of course be used with the context and scope of the present disclosure.

The inner insulation material <NUM> is in turn pre-cut or otherwise shaped (such as by molding) to correspond to a shape of the (bottom of the) NPWT device <NUM>. As can be seen, the inner insulation material <NUM> is also pre-cut in relation to the conduit <NUM>, and further provided with a slot <NUM> to allow the conduit <NUM> to pass through a wall of the first housing section <NUM>.

The second housing section <NUM>, the lid portion of the removable enclosure <NUM>, is also formed from and comprises a corresponding outer shell material <NUM> made from paper and a corresponding inner insulation material <NUM> made from a polymer material that has a cell structure, such as a foam material. It is of course possible to use different materials for the lid portion as compared to the bottom portion.

The insulation material <NUM> of the second housing section <NUM> is also pre-cut or otherwise shaped to correspond to the shape of the (top of the) NPWT device <NUM>. It may however, depending on the amount of inner insulation material <NUM> provided in relation to the first housing section <NUM> to allow the inner insulation material <NUM> to be essentially flat and to be slightly compressed when the first <NUM> and the second <NUM> housing sections are joined together.

In <FIG> it is further suggested that also the second housing section <NUM> is provided with a slot <NUM>, that matches the slot <NUM> of the first housing section <NUM> when the first <NUM> and the second <NUM> housing sections are joined together.

In the illustration as shown in <FIG>, <FIG>, it is suggested that the second housing section <NUM> is completely separate from the first housing section <NUM> and allowed to extend at an outer surface of the outer shell material <NUM> of the first housing section <NUM> when the housing sections are joined together, similar to a shoe box. It may however be possible to allow the housing sections to be partly joined at all time, e.g. arranging the second housing section <NUM> in a hinged manner as compared to the first housing section <NUM>.

The second housing section <NUM> is further provided with an elongated sound duct <NUM> that extends from an inside of the second housing section <NUM>, through the inner insulation material <NUM> and out through the outer shell material <NUM>. One end of the elongated sound duct <NUM> is specifically positioned in such a manner that it with a sound outlet position <NUM> at the NPWT device <NUM> where sound from the speaker element <NUM> is "outputted", as is specifically illustrated in <FIG>. Outputting the sound from the speaker element <NUM> may be dependent on the implementation selected for the NPWT device <NUM>. In one embodiment, and as illustrated in <FIG>, the NPWT device <NUM> is provided with an opening <NUM> in a housing of the NPWT device <NUM>.

It may however as an alternative be possible to arrange the speaker element <NUM> (in the form of an actuator) to be connected to the housing of the NPWT device <NUM>, meaning that the housing of the NPWT device <NUM> will "vibrate" when the speaker element <NUM>. In such an embodiment it could be possible to arrange the first end of the sound duct <NUM> to be arranged to coincide with a suitable position of the housing of the NPWT device <NUM>. In <FIG> the sound duct <NUM> is presented in a preferred embodiment where the sound duct <NUM> is kept as "short as possible" and perpendicular to a flat outer surface of the second housing section <NUM>, thereby maximining the output of sound generated by the speaker element <NUM> to an outside of the removable enclosure <NUM>. It is however possible to arrange the sound duct <NUM> in any other way to achieve the general desired effect of the present disclosure.

Claim 1:
A removable enclosure (<NUM>) for a mobile negative pressure wound therapy (NPWT) device (<NUM>), the NPWT device comprising a negative pressure pump (<NUM>) arranged within a housing of the NPWT device and connected to a wound cover (<NUM>) using a conduit (<NUM>), wherein the removable enclosure comprises:
- a first housing section (<NUM>), and
- a second housing section (<NUM>),
wherein:
- the second housing section is arranged to join the first housing section to enclose the NPWT device,
- at least one of the first or the second housing section is provided with an opening (<NUM>, <NUM>) for passage of the conduit through a wall of the first housing section, and
- the first and the second housing section each comprises an outer shell material (<NUM>) and an inner insulation material (<NUM>),
characterized in that
- the second housing section is provided with a sound duct (<NUM>) extending through the outer shell material and the inner insulation material,
- the sound duct is positioned to propagate a sound emitted by a sound generating device (<NUM>) comprised with the NPWT device to an outside of the removable enclosure, and
- the sound emitted by the sound generating device is indicative of a state of the NPWT device.