Pump Assemblies and Wound Therapy Devices

Abstract

A gradient pressure wound therapy device (50) includes a pump assembly (10). The pump assembly (10) includes a diaphragm (12) containing a magnetic material (16), an electromagnetic actuator (18) switchable between two or more operating states, and a valve device (24), the valve device including an inlet valve (26) and an outlet valve (28) for introducing and / or removing fluid from a fluid chamber (30) of the pump assembly (10). The actuator (18) is configured to enable the diaphragm (12) to move relative to the actuator (18) between a first position corresponding to a first operating state of the actuator (18) and a second position corresponding to a second operating state of the actuator (18).

Description

Technical Field

[0001] The present invention relates to a pump assembly and a wound treatment device, and in particular to a pump assembly for a gradient pressure wound treatment device and a device comprising the pump assembly. Background Art

[0002] Gradient pressure wound therapy (positive or negative) is a known method of treating various wound types. Typically, this involves applying a pressure differential between the sealing area of ​​a wound dressing and the surrounding environment to aid wound healing, such as by removing edema, increasing blood flow, mechanical contraction of the wound, increasing the formation of granulation tissue, and / or actively removing excess exudate from the wound. This type of wound therapy is particularly effective for the treatment of open wounds, non-traumatic and chronic wounds.

[0003] The pressure differential is applied by introducing or removing gas within the sealed area of ​​the wound dressing. Such systems typically use a pump (at least initially) to achieve the desired pressure level within the wound dressing. The pump may be run throughout the treatment or periodically throughout the treatment, or may be used before relying on the seal between the wound dressing and the surrounding environment to maintain the desired pressure level during the treatment. Typically, a membrane or diaphragm pump is used, which uses the reciprocating movement of a diaphragm (and suitable valve means) to pump gas into or out of the wound dressing.

[0004] Recently, some systems have been developed by which the movement of the diaphragm can be controlled using electromagnets appropriately mounted on the diaphragm, similar to a voice coil / speaker arrangement. In such systems, permanent magnets are used to provide a constant magnetic field with which the electromagnets can interact. Specifically, the interaction between the constant magnetic field and the magnetic field induced by the electromagnets is used to cause a corresponding movement of the diaphragm. The direction of movement is controlled by periodically switching the orientation of the field induced by the electromagnets, causing the diaphragm to move back and forth to provide the desired pumping action.

[0005] Advantageously, such a system reduces the number of components that need to be physically coupled to one another, thereby reducing frictional losses in the system and increasing overall efficiency. However, strong permanent magnets must be used in order to provide the necessary constant magnetic field to move the electromagnet and diaphragm as required. This is problematic from a weight and size perspective, resulting in a bulky and heavy pump assembly.

[0006] It would therefore be advantageous to provide a pump assembly for a wound therapy device which does not suffer from these disadvantages.

[0007] It is therefore an object of one or more embodiments of the present invention to overcome or at least partially alleviate the problems associated with the prior art. Summary of the invention

[0008] According to one aspect of the present invention, there is provided a gradient pressure wound therapy device comprising a pump assembly, the pump assembly comprising a diaphragm, an electromagnetic actuator and a valve arrangement; wherein the actuator is fixedly positioned within the device and spatially separated from the diaphragm; and the actuator is configured to induce a magnetic field in at least one operating state for moving the diaphragm between a first position and a second position relative to the actuator.

[0009] According to one aspect of the present invention, a gradient pressure wound therapy device is provided, which includes a pump assembly, which includes: a diaphragm including a magnetic material; an electromagnetic actuator capable of switching between two or more operating states, at least one of the two or more operating states including a state in which the actuator induces a magnetic field for moving the diaphragm; and a valve device including an inlet valve and an outlet valve, wherein the inlet valve and the outlet valve are configured to allow fluid to be introduced into and / or discharged from a fluid chamber of the pump assembly; wherein the actuator is fixedly located in the device and spatially separated from the diaphragm; and the actuator is configured to enable the diaphragm to move relative to the actuator between a first position corresponding to a first operating state of the actuator and a second position corresponding to a second operating state of the actuator.

[0010] Advantageously, having a fixed electromagnet eliminates the need to provide a sufficiently strong magnetic field to move the electromagnet itself. This allows the size of any permanent magnet to be significantly reduced. In the present invention, the improvement achieved is that, where a permanent magnet is included, the permanent magnet can be provided in the form of a magnetic material that forms part (or all) of the diaphragm. This reduces the size and weight of the pump assembly as a whole. In some cases, it may be beneficial to provide a system in which the pump assembly is integrated with the wound dressing itself. Obviously, having a large and heavy pump is not suitable for such an application, and therefore reducing the size and weight of the pump assembly would be advantageous. In addition, in this way, a wound treatment device can be provided in which the only moving part required is the diaphragm. For example, the reduction in the number of moving parts further achieves improvements in efficiency and noise.

[0011] As used herein and throughout the specification, the term "gradient pressure wound therapy device" is intended to encompass a wound therapy device in which a pressure differential (positive or negative) is applied between a sealed area of ​​a wound dressing and the surrounding environment.

[0012] As used herein, negative pressure wound therapy is a treatment technique that uses a suction dressing to remove excess exudate and promote healing of acute or chronic wounds. A vacuum of -50 mmHg to -200 mmHg or -75 mmHg to -150 mmHg, typically -80 mmHg to -130 mmHg, -100 mmHg to -130 mmHg, or generally about -125 mmHg of negative pressure is applied to the wound.

[0013] For positive pressure wound therapy, a net positive pressure is applied to the wound, which may include providing suction and irrigation of the wound simultaneously. Positive pressure wound therapy may be performed at the wound at a positive pressure of up to 50% of atmospheric pressure, typically at a low positive pressure of up to 20% of atmospheric pressure, more typically up to 10% of atmospheric pressure. Positive pressure wound therapy is known and is mentioned in US20180140755.

[0014] As used herein and throughout the specification, the term "spatially separated" may refer to an arrangement in which the actuator and the diaphragm are not connected, coupled, or otherwise attached in any way, for example, an arrangement in which there is an air gap between the actuator and the diaphragm. Rather, with the actuator fixed in position relative to the device, the diaphragm is free to move relative to the actuator, and the actuator does not physically act on the diaphragm to move the diaphragm between the first and second positions. Rather, as described herein, the diaphragm moves under the influence of the magnetic field induced by the actuator, or equivalently, moves under the influence of the removal of the induced magnetic field.

[0015] The optional features set out below may be applied to any aspects of the invention.

[0016] In various embodiments, the device comprises a negative pressure wound therapy device. In such embodiments, the pump assembly is operable, in use, to remove gas from within an applied wound dressing so as to create a pressure differential between the wound dressing and the surrounding environment. In other embodiments, the device comprises a positive pressure wound therapy device. In such embodiments, the pump assembly is operable to introduce gas into an applied wound dressing so as to create a pressure differential between the wound dressing and the surrounding environment.

[0017] The actuator may be configured to move the diaphragm toward or away from the actuator when in the first operating state or the second operating state. For example, in some embodiments, the actuator is configured so that the actuator can move the diaphragm toward or away from the actuator after switching between the first operating state and the second operating state.

[0018] In some embodiments, the actuator is configured to move the diaphragm from the first position to the second position along a first direction after switching from the first operating state to the second operating state. The first direction may be away from the actuator. In some embodiments, the actuator is configured to move the diaphragm from the second position to the first position along a second direction after switching from the second operating state to the first operating state. The second direction may be toward the actuator.

[0019] In some embodiments, the electromagnetic actuator is operable to induce a first magnetic field in a first operating state. In such embodiments, the electromagnetic actuator can be configured to induce a second magnetic field in a second operating state. The first magnetic field and the second magnetic field can be opposite magnetic fields. For example, the first and second magnetic fields can act in opposite directions. In some embodiments, the actuator is configured to move the diaphragm in a first direction toward a first position under the influence of the first magnetic field, and to move the diaphragm in a second direction toward a second position under the influence of the second magnetic field.

[0020] Alternatively, the electromagnetic actuator may be operable to induce a magnetic field only in a first operating state. For example, the actuator may be configured to cause the diaphragm to move in a first direction towards a first position under the influence of a magnetic field. The actuator may be configured to cause the diaphragm to move in a second direction towards a second position in the absence of a magnetic field. Such movement may be provided by a biasing force provided by or applied to the diaphragm.

[0021] Therefore, a particularly preferred embodiment provides a gradient pressure wound therapy device, which includes a pump assembly, which includes: a diaphragm including a magnetic material; an electromagnetic actuator capable of switching between two or more operating states, at least one of the two or more operating states including a state in which the actuator induces a magnetic field for moving the diaphragm; and a valve device including an inlet valve and an outlet valve, wherein the inlet valve and the outlet valve are configured to allow fluid to be introduced into and / or discharged from a fluid chamber of the pump assembly; wherein the actuator is fixedly located in the device and spatially separated from the diaphragm; and the actuator is configured to enable the diaphragm to move relative to the actuator between a first position corresponding to a first operating state of the actuator and a second position corresponding to a second operating state of the actuator; wherein the electromagnetic actuator is operable to induce a magnetic field only in the first operating state.

[0022] Another particularly preferred embodiment provides a gradient pressure wound therapy device, which includes a pump assembly, the pump assembly including: a diaphragm including a magnetic material; an electromagnetic actuator capable of switching between two or more operating states, at least one of the two or more operating states including a state in which the actuator induces a magnetic field for moving the diaphragm; and a valve device including an inlet valve and an outlet valve, the inlet valve and the outlet valve being configured to allow fluid to be introduced into and / or discharged from a fluid chamber of the pump assembly; wherein the actuator is fixedly located within the device and spatially separated from the diaphragm; and the actuator is configured to enable the diaphragm to move relative to the actuator between a first position corresponding to a first operating state of the actuator and a second position corresponding to a second operating state of the actuator; wherein the electromagnetic actuator is operable to induce a magnetic field only in the first operating state; wherein the actuator is configured to enable the diaphragm to move in a first direction toward a first position under the influence of a magnetic field, and wherein the actuator is configured to enable the diaphragm to move in a second direction toward a second position in the absence of a magnetic field.

[0023] Another particularly preferred embodiment provides a gradient pressure wound therapy device, which includes a pump assembly, the pump assembly including: a diaphragm including a magnetic material; an electromagnetic actuator capable of switching between two or more operating states, at least one of the two or more operating states including a state in which the actuator induces a magnetic field for moving the diaphragm; and a valve device including an inlet valve and an outlet valve, the inlet valve and the outlet valve being configured to allow fluid to be introduced into and / or discharged from a fluid chamber of the pump assembly; wherein the actuator is fixedly located within the device and is spatially separated from the diaphragm; and the actuator is configured to The diaphragm is caused to move relative to the actuator between a first position corresponding to a first operating state of the actuator and a second position corresponding to a second operating state of the actuator; wherein the electromagnetic actuator is operable to induce a magnetic field only in the first operating state; wherein the actuator is configured to enable the diaphragm to move along a first direction toward a first position under the influence of the magnetic field, wherein the actuator is configured to enable the diaphragm to move along a second direction toward a second position in the absence of a magnetic field; and wherein the movement of the diaphragm along the second direction is provided by a biasing force provided by or applied to the diaphragm.

[0024] In some embodiments, the device can be configured so as to provide a biasing force for biasing the diaphragm toward a "rest" position. The rest position can correspond to the first position or the second position. In other embodiments, the rest position can correspond to a third position. The third position can be an intermediate position between the first position and the second position.

[0025] In some embodiments, the biasing force can be provided by the diaphragm itself. For example, in some embodiments, the diaphragm can include a flexible and / or elastic material, such as a polymer material or a flexible metal material, for example, which is configured to provide a biasing force after the diaphragm is stretched or contracted (e.g., by deflection of the diaphragm under operation of an actuator). In other embodiments, the device can include a biasing member configured to apply a biasing force to the diaphragm.

[0026] The magnetic material of the diaphragm may comprise a soft magnet or a hard magnet. The magnetic material of the diaphragm may comprise a permanent magnet material. The advantage of a hard / permanent magnet is that it can respond to the magnetic field generated by the actuator by both attraction and repulsion, whereas a soft magnetic material can only respond by attraction.

[0027] The magnetic material of the diaphragm may include ferromagnetic or ferrimagnetic materials. In some embodiments, the diaphragm may include aluminum, iron, cobalt, nickel, manganese, zinc, or alloys thereof. In some embodiments, the diaphragm may include rare earth elements, such as neodymium, or samarium, or alloys thereof.

[0028] In some embodiments, the diaphragm can be formed of a non-magnetic material. In such embodiments, the magnetic material of the diaphragm can include a magnetic component attached to, coupled to, or otherwise fixed to the non-magnetic material. The magnetic component can include a thin film layer or coating. In some embodiments, the diaphragm includes a magnetic coating applied to the non-magnetic material.

[0029] In some embodiments, the electromagnetic actuator may be configured to periodically switch between a first operating state and a second operating state. In this way, the actuator may be operable to cause a pumping action of the diaphragm, thereby periodically moving between the first and second positions. In use, the periodic switching between the first and second operating states may be performed by periodic switching of the direction of the current supplied to the actuator, or by periodic switching of the supply current on and off. The electromagnetic actuator may be operable to periodically switch between the first and second operating states at a rate of up to 500 Hz, up to 1000 Hz or up to 2000 Hz, and / or the electromagnetic actuator may be operable to periodically switch between the first and second operating states at a rate of, for example, at least 500 Hz, or at least 1000 Hz, or at least 1500 Hz, or at least 2000 Hz.

[0030] The device may be configured to achieve a pressure differential of up to 200 mmHg between the wound dressing and the environment. In particular, the device may be configured to achieve a vacuum of -50 mmHg to -200 mmHg; -75 mmHg to -150 mmHg; -80 mmHg to -130 mmHg; -100 mmHg to -130 mmHg, or about -125 mmHg. The electromagnetic actuator may need to operate (e.g., to cause cyclical movement of the diaphragm) for a period of no more than 60 seconds, or no more than 30 seconds, or no more than 15 seconds to achieve the desired pressure differential; and / or the electromagnetic actuator may need to operate for more than 15 seconds, or more than 30 seconds, or more than 45 seconds, or more than 60 seconds to achieve the desired pressure differential.

[0031] In some embodiments, the diaphragm is configured to translate between a first position and a second position, i.e., to move as a whole between the first and second positions. In some embodiments, the diaphragm is configured to deflect between the first and second positions by operation of an actuator. In such embodiments, the diaphragm can be fixed as a whole within the pump assembly and / or the device. For example, in some embodiments, the diaphragm can be fixed at its peripheral edge. The diaphragm can deflect between a concave shape and a convex shape. The first position can correspond to a concave shape and the second position can correspond to a convex shape.

[0032] The diaphragm may be configured to move (eg deflect) up to 5 mm, or up to 10 mm, or up to 20 mm; and / or it may be configured to move, for example, at least 5 mm, or at least 10 mm, or at least 15 mm, or at least 20 mm.

[0033] The diaphragm can be constructed so that its movement causes a corresponding volume change of the fluid chamber of up to 5 mm 3 , or up to 10mm 3 , or up to 20mm 3 ; and / or the diaphragm may be configured to move, for example, at least 5 mm 3 , or at least 10mm 3 , or at least 15mm 3 , or at least 20mm 3 .

[0034] The diaphragm may be substantially circular. A (substantially) circular diaphragm may comprise a diameter of up to 25 mm, or up to 50 mm, or up to 100 mm; and / or it may comprise a diameter; and / or it may comprise, for example, a diameter of at least 25 mm, or at least 50 mm, or at least 75 mm, or at least 100 mm. In some alternative embodiments, the shape of the diaphragm may be substantially oval, square, rectangular, or polygonal. The diaphragm may comprise an irregular shape. In such embodiments, the diaphragm may have a length and / or width within any of the above ranges.

[0035] A wound treatment device may include a wound dressing. The wound dressing may include a dressing body formed of an absorbent material, which may be positioned in contact with a wound during use. The dressing body may be configured to absorb exudate from a wound with the aid of the action of a pump assembly. For example, the dressing body may include an absorbent foam material. The foam material may include a superabsorbent foam material. The dressing body may be formed of a hydrocolloid material that may gel in the presence of exudate. The hydrocolloid material may include one or more layers of absorbent material and gelling fibers. The outer surface of the dressing may be composed of a film layer (e.g., polyurethane) so that moisture vapor / moisture vapor can leave the dressing at a higher rate. This combination will allow the wound treatment device to manage fluids without the need for a tank. This may be referred to as a "tankless" or "tank-free" system. In a variation, the wound dressing may be fluidically connected to a tank into which exudate removed from the wound may be extracted. The dressing may include an adhesive layer for providing a seal between the dressing and the user's skin during use. The adhesive layer may define an interior region of the wound dressing.

[0036] The pump assembly may be fluidly connected to the interior area of ​​the wound dressing for introducing gas into the wound dressing and / or for removing gas from the wound dressing to control the pressure within the wound dressing. The pump assembly may be fluidly connected to the interior area of ​​the wound dressing via a tube or conduit.

[0037] The inlet valve and the outlet valve may preferably comprise one-way valves.

[0038] For example, the wound dressing can have a thickness of 1 mm to 20 mm, or 2 mm to 10 mm, or 3 mm to 7 mm. The wound dressing can be composed of one or more layers, including an outer covering layer, an absorbent layer, fibers capable of forming a gel / gel-forming fibers, an adhesive layer, a wound contact layer, a distribution layer, and combinations thereof. The wound dressing can include one or more absorbent layers. The absorbent layer can be a foam or a superabsorbent. If foam is used, the foam can also serve as a distribution layer. The wound dressing can include an outer covering layer and one or more absorbent layers and a silicone gel wound contact layer. The wound dressing can include an outer covering layer and one or more absorbent layers combined with gel-forming fibers. The gel-forming fibers are usually in direct contact with the wound, so no additional wound contact layer is required, i.e., the silicone gel wound contact layer does not require a silicone gel layer.

[0039] Gel-forming fibers include hygroscopic fibers that become moist and smooth or gel-like after absorbing wound exudate. Gel-forming fibers can be the type that maintains its structural integrity when absorbing exudate, or can be the type that loses its fiber form and becomes amorphous or structureless gel. Gel-forming fibers are preferably sodium carboxymethylcellulose fibers, chemically modified cellulose fibers, alkyl sulfonate-modified cellulose fibers (such as those described in WO2012 / 061225), pectin fibers, alginate fibers, chitosan fibers, hyaluronic acid fibers, or other polysaccharide fibers or fibers derived from / derived from gum. Cellulose fibers preferably have a degree of substitution of at least 0.05 carboxymethyl groups per glucose unit. Gel-forming fibers preferably have an absorptive capacity (measured according to the free expansion method) of at least 2 grams of 0.9% saline solution per gram of fiber.

[0040] The gel-forming fibres are preferably chemically modified cellulose fibres in the form of a fabric, particularly carboxymethylated cellulose fibres as described in PCT WO00 / 01425 to Azko Nobel UK Ltd., and may be provided by a layer of gel-forming fibres preferably located in the port of the cover layer or as a fibrous layer in the conduit of a wound dressing. When present in the conduit, the fibrous layer may also serve to retain the conduit to enable fluid to pass if the conduit becomes kinked or restricted by a user lying or leaning on it. The carboxymethylated cellulose fabric preferably has a degree of substitution (as defined in WO00 / 01425) in the range of 0.12 to 0.35, more preferably in the range of 0.20 to 0.30, as measured according to infrared spectroscopy, and is made by carboxymethylating a woven or non-woven cellulose fabric so that absorbency is increased. Particularly preferred fabrics have an absorbent capacity in the range of 10 g / g sodium / calcium chloride as defined above to 30 g / g sodium / calcium chloride, measured according to the method described in BS EN 13726-1 (2002) "Test methods for primary wound dressings", section 3.2 "Free swell absorbent capacity". Particularly preferred fabrics have an absorbent capacity in the range of 15 g / g to 25 g / g, most preferably a sodium / calcium chloride absorbent capacity in the range of 15 g / g to 20 g / g, measured according to the above method.

[0041] The cellulosic fabric is preferably composed of cellulosic fibers only, but may contain a certain proportion of non-cellulosic textile fibers or gel-forming fibers. Cellulosic fibers are of known types and may include continuous filament yarns and / or staple fibers. Carboxymethylation is generally carried out by contacting the fabric with an alkali and a carboxymethylating agent such as chloroacetic acid in an aqueous system. The fabric is preferably of the nonwoven type to reduce falling into the wound when the dressing is cut. Preferably, the fabric is hydroentangled and therefore includes a series of microscopic pores.

[0042] If present, the absorbent layer of wound dressing can absorb exudate from wound and allow fluid to pass through it. The absorbent layer can include any absorbent that can absorb exudate and allow fluid to pass through it, such as foam, sponge or fiber-based material, and preferably, the absorbent layer is provided by gel-forming fiber with the same type or different types as those mentioned above. Gel-forming fiber is hygroscopic fiber, and it becomes moist smooth or gelatinous when absorbing wound exudate, thereby reducing the trend of surrounding fiber adhesion on wound. Gel-forming fiber is preferably spun sodium carboxymethylcellulose fiber, chemically modified cellulose fiber, alkyl sulfonate modified cellulose fiber (such as those described in WO2012 / 061225), pectin fiber, alginate fiber, chitosan fiber, hyaluronic acid fiber or other polysaccharide fiber or the fiber derived from / derived from gum. Cellulose fiber preferably has the degree of substitution of at least 0.05 carboxymethyl group per glucose unit, more preferably slightly substituted, thereby limiting the absorbency of fiber. The gel-forming fibers preferably have an absorbent capacity (measured by the method described above) of at least 2 grams of 0.9% saline solution per gram of fiber but less than 30 grams of 0.9% saline solution per gram of fiber. The gel-forming fibers are preferably carboxymethylated cellulose fibers as described in PCT WO00 / 01425 to AzkoNobel UK Ltd., which describes a lightly carboxymethylated cellulose fabric. The gel-forming fibers are preferably lightly carboxymethylated in order to reduce the tendency of the absorbent layer to form gel masses and block the passage for fluid from the wound (e.g., the passage through the absorbent layer, the port, and to the distal end of the catheter).

[0043] Preferably, the absorbent layer (if present) has windows / perforations to assist in applying negative pressure to the wound and maintaining the passage of fluid from the wound through the absorbent layer. However, typically, windows are only provided in the inner absorbent layer. The outer absorbent layers (including those in direct contact with the wound) generally do not have mechanically increased perforations, however, they may include openings between fibers.

[0044] Although the absorbent layer may be in direct contact with the wound, preferably the dressing comprises a wound contact layer located between the wound and the absorbent layer. It is possible that the wound contact layer is capable of absorbing exudate from the wound and transferring it to the absorbent layer. Like the absorbent layer, it is possible that the wound contact layer is capable of allowing fluid to pass therethrough so that pressure (positive or negative) can be applied to the wound and a passage of fluid / exudate from the wound to the distal end of the catheter can be maintained.

[0045] For example, the wound contact layer may comprise gel-forming fibres (eg, of the type discussed herein), or a silicone gel.

[0046] Preferably, the wound contact layer comprises gel forming fibres. The gel forming fibres may be of the same or similar type as those comprising the absorbent layer, but the wound contact layer may be reinforced to enhance its integrity and that of the dressing. For example, the wound contact layer may be of the type described in EP 1904011 and comprises gel forming fibres in the form of a pad having longitudinal stitches made of cellulose or nylon or polyolefin yarns to increase the integrity of the layer. Preferably, the wound contact layer is porous to maintain a passage of fluid / exudate from the wound to the distal end of the catheter.

[0047] The outer covering layer of the dressing is provided as a bacterial and viral barrier layer, which preferably blocks the ingress of liquids and air, but allows moisture to pass through. In this way, the outer covering layer enhances the overall fluid handling capacity of the dressing by allowing moisture to escape through the covering layer while being able to apply pressure (positive or negative) to the wound. The outer covering layer is, for example, a material having a density of at least 10,000 g·m -2 / 24h or from 10,000g·m -2 / 24h to 50,000g·m -2 The cover layer may be in the form of a polyurethane film, for example Epurex 912 T / 129 manufactured by Covestro or Inspire 2350 manufactured by Coveris or Medifilm 426 manufactured by Mylan.

[0048] The cover layer may be provided with a port for connection to a catheter. The port is preferably located in the cover layer and overlaps the absorbent layer close to the periphery of the absorbent layer so that the port is not directly vertically aligned with the center of the dressing (or the wound when in use). This helps the exudate to spread throughout the extent of the absorbent layer.

[0049] The conduit of the dressing is preferably a transparent channel fixed to the outside of the cover layer at the proximal end of the conduit so as to surround the port in the cover layer from above. The conduit of the dressing may include a connector at its distal end for connecting the dressing to a pressure source (positive or negative pressure), such as a pump. Preferably, the connector is a Luer lock to facilitate secure connection to the pump and maintain the pressure within the wound dressing when the pump is temporarily disconnected. The connector preferably includes a one-way lock to help maintain the applied pressure. To prevent collapse, the conduit may include an inner tube composed of nylon fibers to maintain the conduit open to the fluid.

[0050] The dressing may also include a distribution layer, such as a pressure distribution layer, between the absorbent layer and the outer cover layer, which is permeable to gas and liquid, in particular moisture, and helps the exudate to reach a larger area of ​​the absorbent layer by allowing the exudate to diffuse under the action of the distribution layer. The distribution layer also serves to even out the negative pressure applied to the wound across the dressing. The distribution layer preferably distributes the exudate and the negative pressure over the dressing. In this way, the absorption of exudate by the absorbent layer can be maximized before the exudate leaves the absorbent layer and activates the indicator device, and the transmission of negative pressure to the wound is optimized. The distribution layer is preferably a foam layer, such as a polyester foam of type XD4200AS manufactured by Caligen or another suitable reticulated foam.

[0051] The dressing may also include additional optional layers, such as an adhesive layer for adhering the dressing to the skin around the wound to form a fluid seal. The adhesive layer may be applied to the side of the dressing closest to the wound and may have perforations to aid in the transport of exudate and fluid through the dressing. The adhesive layer may also be applied to any other layer to provide an island structure, such as to a cover layer.

[0052] According to another aspect of the present invention, a pump assembly is provided, which is optionally used in a gradient pressure wound therapy device, the pump assembly comprising a diaphragm, an electromagnetic actuator and a valve device; wherein, in use, the actuator is fixedly located in the device and spatially separated from the diaphragm; and the actuator is configured to induce a magnetic field in at least one operating state, for moving the diaphragm between a first position and a second position relative to the actuator.

[0053] According to another aspect of the present invention, a pump assembly for a gradient pressure wound therapy device is provided, the pump assembly comprising: a diaphragm comprising a magnetic material; an electromagnetic actuator capable of switching between two or more operating states, at least one of the two or more operating states comprising a state in which the actuator induces a magnetic field for moving the diaphragm; and a valve arrangement comprising an inlet valve and an outlet valve, the inlet valve and the outlet valve being configured to allow fluid to be introduced into and / or discharged from a fluid chamber of the pump assembly; wherein, in use, the actuator is fixedly positioned within the device and spatially separated from the diaphragm; and the actuator is configured to enable the diaphragm to move relative to the actuator between a first position corresponding to a first operating state of the actuator and a second position corresponding to a second operating state of the actuator.

[0054] The definitions described above and the optional features described above in connection with aspects of the present invention relating to gradient pressure wound therapy devices are therefore equally applicable to these aspects of the present invention relating to pump assemblies. For example, in some embodiments, the pump assembly comprises a pump assembly for a negative pressure wound therapy device as described above, and the diaphragm is configured / structured as discussed herein to move in the above-mentioned directions, for example, after switching between operating states. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In order to more clearly understand the present invention, one or more embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings, in which:

[0056] Figure 1 is a schematic diagram of one embodiment of a pump assembly of the present invention;

[0057] Figure 2A , 2B and 2C is Figure 1 a schematic diagram of the pump assembly, illustrating the operational use of the pump assembly; and

[0058] Figure 3 is a schematic diagram of one embodiment of a gradient pressure wound therapy device of the present invention. DETAILED DESCRIPTION

[0059] Embodiments disclosed herein relate to apparatus and methods for treating wounds with reduced pressure or positive pressure (typically negative pressure), including pumps and wound dressing components and devices. The devices and components may include wound coverings and packaging materials, which are collectively referred to herein interchangeably as "dressings" or "wound dressings".

[0060] As disclosed herein, the present invention may include an apparatus for providing gradient pressure wound therapy to a wound, the apparatus comprising: the technology disclosed herein; a wound dressing described herein; and a positive or negative pressure source.

[0061] As used herein, the term "wound" may include damage to living tissue that may be caused by cutting, hitting or other impacts, a typical one being where the skin is cut or broken. Wounds may be chronic injuries or acute injuries. Acute wounds are the result of surgery or trauma. They undergo multiple healing stages within a predicted time frame. Chronic wounds usually begin as acute wounds. When acute wounds do not follow these healing stages, acute wounds may become chronic wounds, which leads to prolonged recovery. It is believed that the transition from acute wounds to chronic wounds may be due to impaired immune function of the patient.

[0062] Chronic wounds may include, for example: venous ulcers (such as those occurring in the legs), which account for the majority of chronic wounds and mostly affect the elderly; diabetic ulcers (e.g., foot or ankle ulcers); peripheral arterial disease; pressure ulcers; or epidermolysis bullosa (EB).

[0063] Examples of other wounds include, but are not limited to, abdominal wounds or other large or incisional wounds (due to surgery, trauma, sternotomy, fasciotomy, or other conditions), dehisced wounds, acute wounds, chronic wounds, subacute and dehisced wounds, traumatic wounds (e.g., from plastic surgery), flaps and skin grafts, lacerations, abrasions, contusions, burns, diabetic ulcers, decubitus / pressure ulcers, ostomies, surgical wounds, traumatic and venous ulcers, fractures, etc.

[0064] The wound may also include 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. For many years, clinicians have used terms such as purple pressure ulcers, ulcers that may worsen, and bruises over bony prominences to describe these ulcers.

[0065] The disclosed technology can be used on acute wounds or chronic wounds.

[0066] Wounds are believed to be more susceptible to infection if: 1. the wound is chronic; 2. if the object that caused the wound is dirty or contained bacteria; 3. if the wound resulted from a bite; 4. if the wound contains remnants or intact objects that caused the wound; 5. if the wound is large or deep; 6. if the wound has jagged edges; 7. if the wound is in an elderly person; 8. if the wound is chronic because the wound site is open in nature; and / or 9. if the patient: has type 1 or type 2 diabetes; 10. if the patient is elderly; 11. if the patient has a compromised immune system.

[0067] Gradient pressure wound therapy can also be used to treat second- and third-degree burns, and for laparotomy, i.e., a large incision through the abdominal wall to access the abdominal cavity.

[0068] In general, the present invention relates to a pump assembly 10 and a gradient pressure wound therapy device 50 including the pump assembly 10 .

[0069] Figure 1 A first embodiment of a pump assembly 10 is shown. The pump assembly 10 includes a diaphragm 12, an electromagnetic actuator 18, and a valve device 24. As discussed herein, the diaphragm 12 is configured to move under the operation of the actuator 18 to control the introduction and / or removal of fluid into the fluid chamber 30. Specifically, the actuator 18 is configured to switch between two (or more) operating states during use, wherein at least one operating state corresponds to the actuator 18 inducing a magnetic field F1, F2 ( Figure 2A , 2B ) to control the state of movement of the diaphragm 12. In this way, the operation of the actuator 18 can be used to control the pressure inside the connected wound dressing 52 (see Figure 3 ).

[0070] The diaphragm 12 includes a resilient member 14 which, in this embodiment, is annular and is secured to the fluid chamber 30 at its peripheral edge. As shown, when the diaphragm 12 is secured in this manner, the resilient member 14 defines a portion of the wall of the fluid chamber 30 such that movement of the resilient member 14 in the manner described herein acts to increase or decrease the volume of the fluid chamber 30. The diaphragm 12 also includes a layer of magnetic material 16 applied to the outer surface of the resilient member 14. As discussed in detail herein, in use, the magnetic material 16 is induced to move in response to an applied magnetic field F1, F2 ( Figure 2A and 2B ) moves under the influence of the diaphragm 12, thereby causing the diaphragm 12 to flex between the first position and the second position, thereby causing the pumping action.

[0071] The actuator 18 includes a coil 22 disposed around a support member 20. The support member 20 may be formed from any suitable material, and the present invention is not limited in this sense. For example, in various embodiments, the support member may include a magnetic material. Opposite ends of the coil 22 are electrically coupled to a power source (not shown) for controlling the current through the coil 22. In use, the direction of the current through the coil 22 determines the direction of the induced magnetic field. In the illustrated embodiment, the coil 22 is electrically coupled to the power source, and in one embodiment, the power source can alternately change the direction of the current through the coil 22. In this way, the actuator 18 is configured to induce a magnetic field in two opposite directions, such as a magnetic field F1 in a first direction corresponding to a first operating state of the actuator 18, and a magnetic field F2 in an opposite second direction corresponding to a second operating state of the actuator 18 (as shown in FIGS. 1 and 1 , respectively). Figure 2A and 2BIn an alternative embodiment, the actuator 18 is configured to induce a magnetic field in only one direction. In this case, the first operating state corresponds to a state in which the magnetic field is "on" (e.g., as shown in FIG. 1 ). Figure 2A ), and the second operating state corresponds to a state where the magnetic field is "off" (e.g., as Figure 2C shown).

[0072] In use, the actuator 18 is advantageously fixed in position within the device 50 at a set distance from the fluid chamber 30 and from the diaphragm 12 in the rest position. Only the flexural movement of the diaphragm 12 between the first and second positions causes the pumping action of the pump assembly 10. This is in contrast to prior art devices in which an electromagnetic actuator may be mounted to the diaphragm and may be moved by interaction with permanent magnets disposed about the actuator. Advantageously, the reduced number of moving parts and reduced size of the permanent magnets inherently provide benefits in terms of efficiency, weight and size savings compared to prior art devices.

[0073] The valve arrangement 24 is comprised of an inlet valve 26 and an outlet valve 28. The opening and closing of the inlet valve 26 and the outlet valve 28 are controlled by the operation of the diaphragm 12, as described herein. It will be appreciated that the inlet valve 26 and the outlet valve 28 comprise one-way valves.

[0074] In the illustrated arrangement, the inlet valve 26 is configured to allow only fluid, particularly gas extracted from a connected wound dressing (e.g., wound dressing 52), to be introduced into the fluid chamber 30 of the pump assembly 10. Similarly, the outlet valve 28 is configured to allow only fluid (gas) to be discharged from the fluid chamber 30 to the environment. This configuration is suitable for use in situations where the pump assembly 10 is used in a negative pressure wound therapy device. However, it should be understood that the inlet valve 26 can alternatively be configured to allow gas to be introduced from the environment into the fluid chamber 30, and the outlet valve can alternatively be fluidly coupled to a wound dressing (e.g., wound dressing 52) and configured to allow gas from within the fluid chamber 30 to be provided to the wound dressing. This alternative arrangement is suitable for use in a positive pressure wound therapy device.

[0075] Figure 2A , 2B 2C illustrate operational use of the pump assembly 10 .

[0076] exist Figure 2AIn the configuration shown, the actuator 18 is in a first operating state. Here, a current is directed in the coil 22 in a first direction, thereby inducing a first magnetic field F1 around the actuator 18. The direction of the magnetic field F1 is such that the magnetic layer 16 of the diaphragm 12 is attracted toward the actuator 18. In this way, the diaphragm 12 as a whole is sucked and pulled in a first direction D1 (upward in the orientation shown in the figure). Since the diaphragm 12 is fixed at its periphery, the diaphragm 12 presents a concave shape, which effectively increases the volume of the fluid chamber 30. This increase in volume has the effect of reducing the internal pressure of the fluid chamber 30, thereby causing the inlet valve 26 to open and allow fluid to be drawn in through the inlet valve 26. As described herein, in the illustrated embodiment, the inlet valve 26 is fluidly connected to the wound dressing 52, allowing gas within the wound dressing 52 to be drawn into the fluid chamber 30. At the same time, the outlet valve 28 remains closed to ensure that the only fluid entering the fluid chamber 30 is the gas drawn from the wound dressing 52.

[0077] Go to Figure 2B , in one embodiment, the actuator 18 is switched to a second operating state. In this state, the current through the coil 22 is reversed, thereby inducing a second magnetic field F2 around the actuator 18 that is oriented opposite to the magnetic field F1. The direction of the magnetic field F2 is such that the magnetic layer 16 of the diaphragm 12 is repelled in a direction away from the actuator 18. As a result, the diaphragm 12 is pushed in a second direction D2 (downward in the orientation shown in the figure). This causes the diaphragm to assume a convex shape, thereby effectively reducing the volume of the fluid chamber 30. This causes the pressure within the fluid chamber 30 to increase significantly, thereby causing the outlet valve 28 to open to allow fluid (i.e., gas previously aspirated from the wound dressing 52) to be discharged from the fluid chamber 30 into the surrounding environment. At the same time, during the "downward stroke" of the diaphragm 12, the inlet valve 26 remains closed to prevent gas from re-entering the wound dressing 52.

[0078] The actuator 18 periodically switches between these two modes of operation so that the pumping action of the diaphragm 12 removes (or in some embodiments introduces) gas from the coupled wound dressing 52 to achieve a desired pressure level within the dressing itself.

[0079] As mentioned above, through Figure 2A and 2C The illustrated embodiment achieves the same effect, wherein the actuator 18 is configured to induce a magnetic field in one direction only, whereby the first operating state corresponds to a magnetic field "on" state and the second operating state corresponds to a magnetic field "off" state.

[0080] In this configuration, the actuator is configured to move the diaphragm in a first direction toward a first position under the influence of a magnetic field (eg, Figure 2Aand in the absence of a magnetic field, as a result of a biasing force provided by or applied to the diaphragm, the diaphragm moves in a second direction toward Figure 2C Move to the second rest position.

[0081] Likewise, in this configuration, Figure 2A During the upward stroke shown, the internal pressure decreases, thereby drawing fluid into the fluid chamber 30, and when the current is no longer directed, the elasticity of the diaphragm pulls it toward Figure 2C 's rest position, thereby pushing it in direction D2 (downwards in the orientation shown in the figure).

[0082] This causes the diaphragm to assume a flat shape, effectively reducing the volume of the fluid chamber 30. This causes the pressure within the fluid chamber 30 to increase, which in turn causes the outlet valve 28 to open, allowing fluid (i.e., gas previously drawn from the wound dressing 52) to be discharged from the fluid chamber 30 into the surrounding environment. At the same time, during the "down stroke" of the diaphragm 12, the inlet valve 26 remains closed to prevent gas from re-entering the wound dressing 52.

[0083] It should be understood that by Figure 2B and Figure 2C The configuration of reciprocating movement to achieve a similar effect, although in this case, it can be used with Figure 2C Differently, the inlet valve 26 will be opened when there is no magnetic field, while the outlet valve 28 will be closed when there is no magnetic field.

[0084] Figure 3 A gradient pressure wound therapy device 50 according to the present invention is shown. The device 50 comprises a wound dressing 52, which may be of the type available under the trademark Avelle from ConvaTec Ltd. The device 50 additionally comprises a pump assembly 10.

[0085] In the illustrated embodiment, the wound dressing 52 includes a dressing body 54 and a peripheral adhesive layer 56. The dressing body 54 includes an absorbent material and is positioned in contact with the wound in use. The dressing body 54 is configured to absorb exudate from the wound with the help of the pump assembly 10 to generate a pressure difference between the interior of the wound dressing 52 and the surrounding environment. Here, the exudate is retained in the dressing body 54. Specifically, the dressing body 54 is formed of a hydrocolloid material that gels when exudate is present. This can be referred to as a "canless" system. In a variation, the exudate removed from the wound can be extracted into an attached canister instead of being retained in the dressing body 54 itself. The exudate removed from the wound can be extracted into the attached canister through a catheter. In use, the adhesive layer 56 provides a seal between the dressing 52 and the user's skin, thereby defining an internal area of ​​the wound dressing 52 around the wound.

[0086] As described herein, the wound dressing 52 is fluidly connected to the inlet valve 26 of the pump assembly 10 via a conduit 58, which may also be of the type available from ConvaTec Ltd. under the trademark Avelle. In this arrangement, the pump assembly 10 is configured to draw air from the interior of the wound dressing 52 to reduce the pressure within the wound dressing 52 relative to the surrounding environment. Specifically, as described herein, the pump assembly 10 is configured to draw air from the wound dressing 52 through the inlet valve 26 via the conduit 58 into the fluid chamber 30. The drawn air is then exhausted from the pump assembly 10 through the outlet valve 28. This process is repeated until a sufficient amount of air has been removed from the wound dressing 52 to achieve a desired pressure level in the wound dressing.

[0087] In an alternative arrangement, the wound therapy device 10 may include a positive pressure wound therapy device 10. In this case, the pump assembly 10 is configured to provide a source of air or other gas to be supplied to the interior of the wound dressing 52, thereby increasing the pressure within the wound dressing 52 relative to the surrounding environment. Specifically, the wound dressing 52 may alternatively be fluidly coupled to the outlet valve 28 of the pump assembly 10. Here, the pump assembly 10 is configured to draw air (or other gas) from the surrounding environment or other gas source into the fluid chamber 30 through the inlet valve 26 and then exhaust the drawn gas through the outlet 28 and allow the gas to enter the wound dressing 52 via the conduit 58. This process can be repeated until a sufficient amount of air / gas has been introduced into the wound dressing 52 to achieve a desired pressure level therein.

[0088] Unless specifically stated otherwise, or understood otherwise in the context of use, conditional language such as "may," "could," "might," or "might possibly" is generally intended to convey that some embodiments include and other embodiments do not include certain features, elements, and / or steps. Thus, such conditional language is generally not intended to imply that one or more embodiments require features, elements, and / or steps in any way, or that one or more embodiments must include logic for deciding, with or without user input or prompting, whether such features, elements, and / or steps are included in any particular embodiment or will be performed in any particular embodiment.

[0089] Each of the documents mentioned above is incorporated herein by reference.Except in the examples, or unless expressly indicated otherwise, all numerical quantities in this specification specifying amounts of material, dimensions of devices, and so forth, are to be understood as being modified by the word "about".

[0090] Unless otherwise indicated, each chemical or composition referred to herein should be interpreted as a commercial grade material, which may contain isomers, by-products, derivatives, and other such materials that are normally understood to be present in the commercial grade. One or more embodiments have been described above by way of example only. Numerous variations are possible without departing from the scope of protection provided by the appended claims.

Claims

1. A tankless gradient pressure wound treatment device comprising a wound dressing and a pump assembly, the pump assembly comprising: A diaphragm including a magnetic material; an electromagnetic actuator switchable between two or more operating states, at least one of the two or more operating states comprising a state in which the electromagnetic actuator induces a magnetic field for moving the diaphragm; as well as a valve arrangement comprising an inlet valve and an outlet valve configured to allow fluid to be introduced into and / or exhausted from a fluid chamber of the pump assembly, wherein the electromagnetic actuator is fixedly located within the gradient pressure wound therapy device and spatially separated from the diaphragm; wherein the electromagnetic actuator is configured to move the diaphragm relative to the electromagnetic actuator between a first position corresponding to a first operating state of the electromagnetic actuator and a second position corresponding to a second operating state of the electromagnetic actuator, wherein the wound dressing comprises a dressing body formed of an absorbent material, the dressing body being positioned in contact with a wound in use, and the dressing body being configured to absorb exudate from the wound with the assistance of the action of the pump assembly, wherein the outer surface of the wound dressing is comprised of a film layer to enable moisture to leave the wound dressing at an increased rate, thereby allowing the gradient pressure wound therapy device to manage fluid without the need for a canister, wherein the electromagnetic actuator is fixed within the gradient pressure wound therapy device at a set distance from the fluid chamber and from the diaphragm in the rest position, and Therein, the wound dressing is fluidly connected to an inlet valve of a pump assembly via a conduit for introducing gas into the wound dressing and / or for removing gas from the wound dressing.

2. The gradient pressure wound therapy device according to claim 1, wherein: The electromagnetic actuator is operable to induce a magnetic field only in the first operating state, wherein the electromagnetic actuator is configured to enable the diaphragm to move along a first direction toward the first position under the influence of the magnetic field; wherein the electromagnetic actuator is configured to enable the diaphragm to move along a second direction toward the second position in the absence of a magnetic field, wherein the movement of the diaphragm along the second direction is provided by a biasing force provided by or applied to the diaphragm.

3. The gradient pressure wound therapy device of claim 1, wherein: The magnetic material of the diaphragm includes a permanent magnetic material.

4. The gradient pressure wound therapy device of claim 1, wherein: The dressing body includes a superabsorbent foam material.

5. The gradient pressure wound therapy device of claim 1, wherein: The dressing body is formed from a hydrocolloid material that is capable of gelling in the presence of exudate.

6. The gradient pressure wound therapy device of claim 5, wherein: The hydrocolloid material includes multiple layers of gelling fibers and absorbent material.

7. A gradient pressure wound therapy device according to any one of claims 1 to 6, wherein: The wound dressing comprises an adhesive layer for providing a seal between the wound dressing and the skin of a user during use; the adhesive layer defines an interior area of ​​the wound dressing; the pump assembly is fluidly connected to the interior area of ​​the wound dressing for introducing gas into the wound dressing and / or for removing gas from the wound dressing so as to control the pressure within the wound dressing.

8. The gradient pressure wound therapy device of claim 1, wherein: The wound dressing consists of an outer covering layer, an absorbent layer, gel-forming fibers, an adhesive layer, a wound contact layer and a distribution layer.

9. The gradient pressure wound therapy device of claim 1, wherein: The wound dressing comprises an outer cover layer, one or more absorbent layers, and a silicone gel wound contact layer.

10. The gradient pressure wound therapy device of claim 1, wherein: The wound dressing comprises an outer cover layer and one or more absorbent layers incorporating gel-forming fibers for direct contact with the wound.

11. The gradient pressure wound therapy device according to claim 8 or 10, wherein: The gel-forming fibers are sodium carboxymethylcellulose fibers, chemically modified cellulose fibers, alkyl sulfonate-modified cellulose fibers, pectin fibers, alginate fibers, chitosan fibers, hyaluronic acid fibers, or other polysaccharide fibers or fibers derived from gums.

12. The gradient pressure wound therapy device of claim 11, wherein: The gel-forming fibers have an absorbent capacity of at least 2 grams of a 0.9% saline solution per gram of fiber as measured by the free swell method.

13. The gradient pressure wound therapy device according to claim 8 or 10, wherein: The gel-forming fibers are cellulose fibers in the form of a fabric.

14. The gradient pressure wound therapy device of claim 13, wherein: The cellulose fibers are chemically modified cellulose fibers.

15. The gradient pressure wound therapy device of claim 13, wherein: The gel-forming fibers are carboxymethylated cellulose fibers having a degree of substitution in the range of 0.12 to 0.35 as measured by infrared spectroscopy.

16. The gradient pressure wound therapy device of claim 13, wherein: The fabric used for gel formation has an absorbency in the range of 10 g / g sodium / calcium chloride to 30 g / g sodium / calcium chloride measured according to the method described in section 3.2 "Free Swell Absorbent Capacity" of the Primary Wound Dressing Test Methods in BS EN 13726-1 (2002) standard published by the British Standards Institution.

17. The gradient pressure wound therapy device of claim 13, wherein: The fabric is of the non-woven type to reduce shedding into the wound when the wound dressing is cut.

18. The gradient pressure wound therapy device of claim 13, wherein: The fabric is hydroentangled and therefore comprises a series of microscopic scale pores.

19. The gradient pressure wound therapy device according to any one of claims 8 to 10, wherein: The absorbent layer of the wound dressing is capable of absorbing exudate from the wound and allowing fluid to pass therethrough.

20. The gradient pressure wound therapy device according to any one of claims 8 to 10, wherein: The absorbent layer is provided with windows to facilitate application of negative pressure to the wound and to maintain a passage for fluid from the wound through the absorbent layer.

21. The gradient pressure wound therapy device according to any one of claims 8 to 10, wherein: The outer covering layer of the wound dressing is a bacterial and viral barrier layer that prevents the ingress of liquids and air but allows moisture vapor to pass through.

22. The gradient pressure wound therapy device of claim 21, wherein: The outer cover layer has a moisture vapor transmission rate of at least 10,000 g·m 2 as measured according to the method described in the main wound dressing test methods in BS EN 13726-2 2002 standard published by the British Standards Institution, part 2 "Moisture Vapour Transmission Rate of Permeable Film Dressings". -2 / 24h moisture vapor transmission rate.

23. The gradient pressure wound therapy device of claim 22, wherein: The outer cover layer has a moisture vapor transmission rate of 10,000 g·m 2 at 10,000 g·m 2 measured according to the method described in the main wound dressing test methods in BS EN 13726-2 2002 standard published by the British Standards Institution, part 2 "Moisture Vapour Transmission Rate of Permeable Film Dressings". -2 / 24h to 50,000g·m -2 / 24h range of moisture vapor transmission rate.

24. A gradient pressure wound therapy device according to any one of claims 8-10, comprising a distribution layer located between the absorbent layer and the outer covering layer, the distribution layer being gas and liquid permeable and moisture vapour permeable and being used to help exudate reach a larger area of ​​the absorbent layer by allowing the exudate to diffuse under the action of the distribution layer.

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