Negative pressure wound therapy (NPWT) dressing

Abstract

The present disclosure generally relates to a negative pressure wound therapy (NPWT) dressing (100) comprising a backing layer (101) and an adhesive skin contact layer (102); the adhesive skin contact layer (102) is configured to releasably adhere the dressing (100) to a skin surface, the backing layer (101) comprising a coupling member (104); and the coupling member (104) comprising tubing (105) configured to connect the dressing (100) to a negative pressure source and a remote fluid collection means.

Description

Technical Field

[0001] The present disclosure generally relates to negative pressure wound therapy (NPWT) dressings. The invention similarly relates to systems and kits containing such dressings.

Background Art

[0002] Negative pressure wound therapy (NPWT) is a technique for promoting the healing of, for example, surgical, acute, and chronic wounds by applying a sub-atmospheric pressure to the wound using a negative pressure pump. The healing of the wound is achieved by applying a negative pressure such as a vacuum through a dressing or cover applied over the wound. This draws out excess wound exudate, thus increasing blood flow to the area and promoting the formation of granulation tissue. The NPWT technique also enables the reduction of external interference with the wound and transports excess fluid away from the wound site.

[0003] NPWT technology has hitherto been mainly applied to patients while they are in a hospital environment. However, recent product development has made it possible for patients to use this technology in a home environment.

[0004] In a hospital environment, the wound to be treated is generally an open cavity wound that is first filled with a wound filler such as gauze or foam. The wound can then be sealed with an adhesive film and connected to a vacuum pump via a drain or port. The size of the foam, gauze, and / or adhesive film dressing can be adapted and cut according to the size, shape, or type of the wound. The application procedure is generally carried out by a caregiver. The negative pressure pumps used in such systems are generally large and generally have a large capacity for treating large amounts of wound exudate. Such systems generally include fluid collection means such as a canister located remotely from the dressing. The wound exudate discharged from the wound is transferred by tubing to the canister for fluid collection.

[0005] Within a home environment, a portable NPWT device that a patient can carry around is generally preferred. A portable NPWT device generally includes an absorbent dressing configured to be connected to a negative pressure source using tubing. The pumps used in such devices are generally relatively small and have more limited capacity.

[0006] In most portable NPWT systems, the dressing serves as the only means of collecting wound exudate. When dealing with large amounts of wound exudate, the dressing can quickly become saturated. This can negatively affect the dressing's ability to remain on the skin. That is, the wearing time of the dressing is shortened. As a result, the dressing needs to be discarded and replaced with a new one.

[0007] Therefore, with respect to dressings for use in negative pressure wound therapy, there is a need for improvement, specifically with regard to the ability of the dressing to handle wound exudate so as to improve the wearing time of the dressing.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0009] In view of the above problems, an object of the present disclosure is to improve dressings for use in the field of NPWT, specifically to improve the wearing time of the dressing and its ability to handle wound exudate so that the entire NPWT system and the applied treatment function efficiently.

Means for Solving the Problems

[0010] According to a first aspect of the present disclosure, in a negative pressure wound therapy (NPWT) dressing comprising a backing layer, an adhesive skin contact layer, and an absorbent structure disposed between the backing layer and the adhesive skin contact layer; the adhesive skin contact layer is configured to adhesively attach the dressing to the skin surface in a removable manner, and the backing layer includes a coupling member configured to connect the dressing to a negative pressure source and a remote fluid collection means. There is provided a negative pressure wound therapy (NPWT) dressing including a liquid spreading layer disposed between the absorbent structure and the backing layer.

[0011] The present disclosure is based on the recognition that providing a liquid spreading layer between the absorbent structure and the backing layer provides several advantages in terms of liquid handling and distribution. The liquid spreading layer improves the spreading and distribution of wound exudate within the dressing, thereby forming a larger surface area through which the exudate can be evaporated (through the backing layer). Thus, the larger surface area of the liquid spreading layer can act to more efficiently remove excess exudate and keep the wound site relatively dry.

[0012] Furthermore, the liquid spreading layer improves the distribution of potential "backflow" exudate, i.e., exudate flowing in the opposite direction (from the tubing into the dressing). For example, this can occur when the dressing is disconnected from the negative pressure source and / or the remote fluid collection means. The liquid spreading layer ensures that such backflow of exudate is spread over a large surface rather than flowing back towards the wound site in one location.

[0013] The present disclosure is also based on the recognition that an appropriate balance between the wound exudate stored by the dressing and the wound exudate removed from the dressing (to remote fluid collection means) can be achieved using an absorbent structure along with liquid spreading. As a result, the wearing time of the dressing is improved. The dressing of the present disclosure includes tubing configured to connect the dressing to remotely located fluid collection means. In other words, the wound exudate is stored by the dressing and removed from the dressing simultaneously. The dressing is designed not only to ensure efficient distribution of the liquid within the dressing but also to ensure transfer of a substantial amount of liquid away from the dressing using the tubing.

[0014] In an embodiment, at least a portion of the absorbent structure and the backing layer include an opening disposed under a bonding member, where the liquid spreading layer is not provided with an opening.

[0015] The opening serves to ensure fluid communication between the wound site and the tubing of the dressing and thus also between the wound site and remotely located fluid collection means.

[0016] The liquid spreading layer is not provided with such an opening to prevent potential gelling particles and relatively large, unwanted microparticles of exudate from entering the tubing of the dressing. Within the region below the bonding member of the dressing, the liquid spreading layer is configured to transfer liquid from within the dressing through the tubing to remotely located fluid collection means.

[0017] In an embodiment, the liquid spreading layer is configured to extend over at least 90% of the surface area of the absorbent structure.

[0018] Thus, the liquid spreading layer is a continuous layer that extends substantially over the entire absorbent structure. This is aimed at ensuring efficient spreading of the liquid over a large surface and improving evaporation of the liquid from the dressing.

[0019] In an embodiment, the liquid spreading layer is hydrophilic and porous.

[0020] Thus, liquid can be transferred through the layer from inside the covering material towards the tubing of the covering material and thus efficiently transferred to remote fluid collection means such as a canister.

[0021] In an embodiment, the liquid spreading layer comprises a non-woven fabric.

[0022] The non-woven fabric imparts suitably balanced rigidity to the layer and the covering material, as the layer and the covering material. The liquid spreading layer of the non-woven fabric has the ability to distribute fluid over most of the material and transfer exudate in a controlled manner to tubing connecting the remotely located fluid collection means and the covering material.

[0023] In an embodiment, the absorbent structure is 10 - 20 mg / cm 2 preferably 13 - 17 mg / cm 2 and contains superabsorbent particles in an amount.

[0024] The inventors have found that this range is beneficial from the perspective of achieving an appropriate balance between the liquid retained in the covering material and the liquid removed from the covering material using the tubing. Such a superabsorbent layer 103a absorbs exudate at a "reasonable" level. If too much SAP is included, the SAP layer may swell and absorb too much and too rapidly. This can have the effect of the covering material serving as the sole or at least dominant means for fluid collection. In the context of the present disclosure, the balance between remotely located fluid collection means, such as a canister, and the covering material (which is also considered a fluid collection means) is preferably 50:50, for example at least 40:60 or 60:40. As described above, this balance is important for improving the wearing time of the covering material.

[0025] In an embodiment, the absorbent structure comprises a first liquid spreading layer, a superabsorbent layer and a second liquid spreading layer, and the superabsorbent layer is disposed between the first and second liquid spreading layers.

[0026] The first liquid spreading layer is configured to absorb and distribute liquid flowing from the wound site. The first liquid spreading layer can distribute and spread wound exudate evenly across a large surface area so that it can be absorbed by the superabsorbent layer. The second liquid distribution layer distributes exudate from the superabsorbent layer in such a way that the exudate is spread across a large area before it is evaporated from the backing layer or transported by tubing to remote fluid collection means.

[0027] The absorbent structure, together with the liquid spreading layer on top of the absorbent structure, is configured to optimize the distribution of wound exudate within the dressing and ensure the removal of a substantial amount of exudate using tubing configured to connect the dressing to remotely located fluid collection means. The absorbent structure is designed to achieve an appropriate liquid distribution balance between the dressing, which serves as a fluid “compartment” for holding and storing liquid, and the remote fluid collection means.

[0028] In an embodiment, the absorbent structure is embossed.

[0029] The embossed absorbent structure improves the fluid handling characteristics of the dressing and contributes to a balanced and more controlled spreading of wound exudate from within the dressing to the canister. Further, the embossed absorbent structure enables the dressing to maintain its shape and thinness while also having flexibility.

[0030] Generally, the backing layer and the adhesive skin contact layer are configured to extend beyond the perimeter of the absorbent structure and form an edge portion along the contour of the absorbent structure. In a preferred embodiment, the adhesive skin contact layer includes a plurality of apertures within a region below the absorbent structure, but does not include apertures in the region forming the edge portion.

[0031] The aperture serves to improve the absorption of wound exudate into the covering material and is thus disposed within the area where absorption occurs. The area of the absorption layer forming the edge portion of the covering material preferably does not contain apertures. In this way, adhesion to the skin is enhanced and the residual capacity of the covering material is thereby extended.

[0032] The covering material further includes a permeable layer disposed between the adhesive skin contact layer and the absorbent structure, and the permeable layer includes a spacer fabric.

[0033] The permeable layer facilitates the transmission of negative pressure from the negative pressure source to the wound site.

[0034] In an embodiment, the covering material includes a plurality of adhesive strips between the absorbent structure and the permeable layer.

[0035] The adhesive strips are configured to stop the flow of exudate towards the binding member and the tubing. As mentioned above, the covering material of the present disclosure preferably has a structure that allows for a proper and substantially equal balance between the covering material and the fluid collection means disposed remotely therefrom.

[0036] The adhesive strips prevent the exudate from flowing too quickly towards the fluid collection means disposed remotely, thus allowing the full absorption capacity of the covering material to be utilized. Thus, the adhesive strips can contribute to the desired distribution of wound exudate between the covering material and, for example, a remotely disposed canister.

[0037] In an embodiment, the backing layer has a water vapor transmission rate (MVTR) in the range of 500 to 3500 g / m 2 / 24 h, preferably in the range of 600 to 2700 g / m 2 / 24 h as measured by NWSP070,4RO(15).

[0038] The water vapor transmission rate (MVTR) is the rate at which the backing layer (and by extension, the coating material as well) evaporates moisture. It is generally known that absorbent dressings for exudative wounds require a backing layer with a very high water vapor transmission rate (MVTR). In contrast to what is known in the art, the inventors have recognized that, unexpectedly, a backing layer with a low MVTR has an associated positive effect when such a dressing is applied in negative pressure wound therapy. A backing layer having an MVTR in the range of 500 - 3500 g / m 2 / 24h improves negative pressure wound treatment and system stability, has a positive effect on the negative pressure source, i.e., the pump, and the negative pressure source does not need to function so powerfully during treatment. The MVTR range defined above also ensures that excess moisture is efficiently removed from the dressing and wound healing is promoted. Further, by providing a liquid spreading layer below the backing layer, it is possible to "compensate" for the low water vapor transmission rate (MVTR) of the backing layer.

[0039] In an embodiment, the tubing includes a fluid conduit configured to remove fluid derived from the dressing and an air conduit configured to supply air to the fluid conduit and / or the dressing.

[0040] The inflow of a small amount of controlled air can be beneficial for more efficiently withdrawing fluid from the wound site and transporting the fluid to remotely located fluid collection means, such as a canister. The introduction of air can dissipate potential exudate blockages or liquid columns formed within the tubing.

[0041] According to a second aspect, - the negative pressure wound treatment (NPWT) dressing described above, - a negative pressure source, - remotely located fluid collection means fluidly connected to the negative pressure source and the dressing, A negative pressure wound treatment (NPWT) system is provided that includes.

[0042] In an embodiment, the remote fluid collection means is a canister, and the canister and the negative pressure source are disposed inside the same device; the device includes a housing, the negative pressure source is disposed within the housing, and the canister is detachably connected to the housing.

[0043] The detachable configuration enables a user or caregiver to remove the canister, empty the collected liquid, and then reattach the canister to the negative pressure source.

[0044] In an embodiment, the NPWT system includes means for supplying air to the dressing at a flow rate of 2 - 7 ml / min during operation.

[0045] As described above, a small and controlled inflow of air can be beneficial for more efficiently withdrawing fluid from the wound site and transporting the fluid to a remotely located fluid collection means, such as a canister. Air can be supplied to the dressing using tubing (e.g., an air conduit) at a controlled relatively low rate in such a way that problems associated with liquid columns and blockages in the tubing are prevented. In this way, the desired pressure level is transmitted to the wound site. In a negative pressure wound therapy system, there is generally a hydrostatic pressure difference introduced by gravity between the pressure inside the canister and the pressure at the wound site. This is due to the height difference between the canister and the wound site. Changes in hydrostatic pressure can affect the ability to provide an appropriate negative pressure level at the wound site. These problems may be solved by supplying a low air flow rate or by leakage of air. Further, if too much air is introduced, this can negatively affect the stability of the system and generally the pump is operated more frequently.

[0046] According to a third aspect, there is provided a kit comprising a negative pressure wound therapy (NPWT) dressing as described above.

[0047] Further features and attendant advantages of the present disclosure will become apparent upon consideration of the appended claims and the following description. Those skilled in the art will recognize that, without departing from the scope of the present disclosure, different features of the present disclosure can be combined to create embodiments other than those described below.

[0048] Various aspects of the present disclosure, including its specific features and advantages, will be readily understood from the following detailed description and the accompanying drawings.

Brief Description of the Drawings

[0049]

Figure 1a

Figure 1b

Figure 1c

Figure 2

Figure 3

Figure 4

Figure 5a

Figure 5b

Figure 5c

Figure 6a

Figure 6b

Figure 7

[0050] The present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which presently preferred embodiments of the disclosure are shown. However, the disclosure may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Throughout, like reference numerals mean like elements.

[0051] Figures 1a and 1b show a negative pressure wound therapy (NPWT) covering material 100 according to an exemplary embodiment of the present disclosure. The NPWT covering material 100 includes a backing layer 101, an adhesive skin contact layer (see 102 in Figure 1b), and an absorbent structure 103 disposed between the backing layer 101 and the adhesive skin contact layer; the adhesive skin contact layer is configured to adhere the covering material 100 to the skin surface, and the backing layer 101 includes a coupling member 104 including tubes 105 configured to connect the covering material 100 to a negative pressure source and a remote fluid collection means, and the covering material 100 includes a liquid spreading layer 106 disposed between the absorbent structure 103 and the backing layer 101.

[0052] As used herein, the term "negative pressure wound treatment dressing" means a dressing for use in negative pressure wound treatment. In the context of the present disclosure, "negative pressure wound treatment" means a treatment that utilizes a negative pressure source (e.g., a vacuum pump) to remove excess fluid from a wound. The wound can be an open wound or can also be a closed wound, i.e., a surgical incision, and thus the term encompasses the field of use of the term "topical negative pressure (TNP) treatment", which is often used in connection with incisions.

[0053] The NPWT dressing 100 of the present disclosure includes an absorbent structure that can also be referred to as a "wound pad". The NPWT dressing is generally referred to as a "bordered dressing". The backing layer 101 and the adhesive skin contact layer are arranged to extend beyond the contour of the absorbent structure 103 to form a border portion 108.

[0054] As used herein, the term "skin surface" means the skin of the wearer. The skin can include a wound to be treated, such as an open wound or a closed wound.

[0055] The NPWT dressing 100 of the present disclosure is adapted for use within an NPWT system that includes remote fluid collection means. As used herein, the term "remote fluid collection means" means that the fluid collection means is located at a certain distance from the dressing, such as between the dressing and the negative pressure source, or is connected to the negative pressure source. In an embodiment, the negative pressure source and the fluid collection means are arranged within the same NPWT device.

[0056] As best shown in FIGS. 1b and 1c, at least a portion of the absorbent structure 103 and the backing layer 101 include an opening 107 that is disposed beneath the bonding member 104, and the liquid spreading layer 106 is lacking in openings.

[0057] The opening 107 ensures fluid communication between the wound site and the fluid collection means disposed remotely therefrom. It also enables the transmission of negative pressure to the wound site. The coupling member 104 is over the opening 107 in the backing layer (as best shown in FIG. 1c). In FIG. 1c, the absorbent structure 103 includes three layers, each containing one opening. However, it is equally conceivable that only one layer of the absorbent structure 103, or two layers, may have openings.

[0058] Since the liquid spreading layer 106 does not contain any openings, gelling particles and relatively large unwanted microparticles are prevented from entering the tubing 105 of the covering 100.

[0059] The liquid spreading layer 106 is configured to extend over at least 90% of the surface area of the absorbent structure 103.

[0060] Preferably, the liquid spreading layer 106 is configured to extend over the entire surface area of the absorbent structure 103. Thus, the liquid spreading layer 106 and the absorbent structure 103 have the same outer dimensions and cross-sectional area.

[0061] The liquid spreading layer 106 is configured to improve the spreading of wound exudate and create a larger surface area through which moisture can evaporate through the backing layer 101.

[0062] The liquid spreading layer 106 is preferably a hydrophilic and porous layer. In this way, exudate can be efficiently transferred from the wound site through the liquid spreading layer 106 to the tubing 105.

[0063] The liquid spreading layer 106 can be a fibrous material. In an embodiment, the liquid spreading layer 106 includes a nonwoven fabric.

[0064] The nonwoven liquid spreading layer 106 has the ability to distribute fluid over most of the material and transfer exudate in a controlled manner to the tubing 105 that connects the remotely disposed fluid collection means to the covering.

[0065] The liquid spreading layer 106 helps to move fluid away from the wound site and away from the absorbent structure 103, while ensuring that the maximum absorbency of the absorbent dressing is utilized.

[0066] The liquid spreading layer 106 is also beneficial for spreading potential exudate flowing from the tubing 105 towards the dressing, i.e., exudate flowing in the "wrong" direction. Backflow of exudate can occur when the person wearing the dressing disconnects the dressing from the negative pressure source and fluid collection means. For example, a patient may disconnect the NPWT dressing when taking a shower or changing clothes. The liquid spreading layer 106 ensures that such backflow of exudate is spread rather than flowing back towards the wound site in one spot. In this way, the wound site can be kept relatively dry.

[0067] The liquid spreading layer 106 may comprise a meltblown, spunbond or spunlace nonwoven fabric. Examples of suitable polymers for use in the nonwoven fabric include polyethylene, polyester, polypropylene and other polyolefin homopolymers and copolymers. For example, a nonwoven web comprising thermoplastic fibers of polypropylene and polyethylene fibers or mixtures thereof may be used. The web may have a high thermoplastic fiber content and may contain at least 50%, for example at least 70%, thermoplastic fibers. The nonwoven fabric may be, for example, a mixture of polyester and viscose in a ratio of 70:30. The basis weight of the nonwoven fabric may be in the range of 10 - 80 g / m 2 , for example 20 - 50 g / m 2 . The liquid spreading layer may also be a spunbond - meltblown or spunbond - meltblown - spunbond (SMS) web.

[0068] The liquid spreading layer 106 preferably has the ability to absorb wound exudate flowing from the absorbent structure. In embodiments, the liquid spreading layer 106 has an absorbency of at least 10 g / g when measured by the standard test method NWSP10.1.

[0069] In an embodiment, the absorbent covering material has a retention capacity of 300 to 700 mg / cm 2 , preferably 400 to 600 mg / cm 2 when measured by the test method described in Example 2.

[0070] The inventors have found that the retention capacity of the covering material is important to ensure a balanced liquid distribution between two fluid collection means (the covering material and, for example, a canister). A balanced distribution of liquid between the two fluid collection means is crucial to ensure the utilization of the maximum absorption capacity of the covering material as well as to optimize the wearing time of the covering material.

[0071] The absorbent structure 103 is configured to absorb wound exudate and efficiently distribute such wound exudate. The absorbent structure 103 functions as a temporary reservoir for holding and distributing the exudate while also ensuring a controlled transport of the liquid towards the tubing 105 (and the fluid collection means located remotely from the covering material).

[0072] The absorbent structure 103 may include one or more layers, where at least one of these layers includes a superabsorbent layer containing a superabsorbent polymer (SAP).

[0073] "Superabsorbent polymer", i.e., "SAP", is a polymer that can absorb up to 300 times its own weight in an aqueous fluid. Superabsorbent polymers are composed of water-swellable and water-insoluble polymers that have the ability to absorb large amounts of fluid when forming hydrogels. Superabsorbent polymers for use in accordance with the present disclosure can be inorganic or organic crosslinked hydrophilic polymers such as polyvinyl alcohol, polyethylene oxide, crosslinked polyacrylate, and the like. Generally, superabsorbent polymers (SAP) contain sodium acrylate. The SAP material is in the form of particles, fibers, flakes, or the like. Preferably, the SAP material is in the form of superabsorbent polymer (SAP) particles. The size of the superabsorbent particles can be in the range of 45 to 850 μm, preferably 150 to 600 μm.

[0074] The absorbent structure can contain superabsorbent particles in an amount of 10 to 20 mg / cm 2 , preferably 13 to 17 mg / cm 2 of the amount.

[0075] This range is beneficial because it allows the absorbent structure to absorb exudate at a "reasonable" level. If too much SAP is included, the SAP layer may swell and absorb too much and too quickly. This can result in the effect that the coating material serves as the sole or at least dominant fluid collection means. In connection with the present disclosure, the balance between the coating material and a remotely located fluid collection means, such as a canister, is preferably 40:60 to 60:40. The inventors have found that such a distribution can be maintained for up to 9 days of treatment without the need to replace the coating material (see Example 1).

[0076] Preferably, the absorbent structure includes at least one superabsorbent layer 103a and at least one liquid spreading layer.

[0077] As shown in FIG. 1c, the absorbent structure 103 includes three layers 103a-c.

[0078] At least one of these layers is a liquid spreading layer. In an embodiment, the lowermost layer of the absorbent structure 103 is the liquid spreading layer 103b. Exudate entering the liquid spreading layer 103b from the wound site is evenly distributed before entering the other layers of the absorbent structure 103, thus creating a larger surface area towards the superabsorbent layer 103a and the other layers of the absorbent structure 103 when present.

[0079] The absorbent structure includes a first liquid spreading layer 103b, a superabsorbent layer 103a, and a second liquid spreading layer 103c, and the superabsorbent layer 103a is disposed between the first and second liquid spreading layers (103b, 103c).

[0080] The first and / or second liquid spreading layer can include any material having the ability to efficiently distribute exudate. For example, the first and / or second liquid spreading layer includes a nonwoven material.

[0081] Preferably, the first liquid spreading layer 103b is disposed below the superabsorbent layer 103a and has a greater liquid spreading ability than the second liquid spreading layer 103c. Thus, an absorbent structure with a liquid spreading gradient is achieved, which affects the ability of the absorbent structure 103 to hold and remove liquid from and within the covering material.

[0082] For example, the first liquid spreading layer 103b may include a nonwoven fabric. The nonwoven fabric may have a basis weight in the range of 20 - 50 g / m 2 (gsm), for example 30 - 40 g / m 2 (gsm). The thickness of the liquid spreading layer 103b can be 0.2 - 1.2 mm, for example 0.2 - 0.6 mm. The thickness is measured under dry conditions.

[0083] The second liquid spreading layer 103c can be a thin fabric or nonwoven layer. Generally, the spreading ability of the upper layer 103c is lower than that of the lower liquid spreading layer 103b.

[0084] Layer 103c also helps prevent leakage of SAP particles from the superabsorbent layer 103a. The SAP particles of the superabsorbent layer 103a chemically bond with the exudate entering the superabsorbent layer 103a, thereby forming an aqueous gel. Layer 103c prevents the gelled particles from moving towards the backing layer 101 and towards the bonding member 104 including the tubing 105. Thus, unwanted blockage by the gel particles inside the tubing 105 is prevented. Preferably, layer 103c is a liquid spreading layer and helps create a larger indirect surface of the distributed liquid towards the backing layer 101 of the covering material 100. Layer 103c or 103b also serves as a "support layer" and serves as a carrier during the manufacturing process.

[0085] The various layers of the absorbent structure create a composite liquid absorption and retention structure, and improved liquid distribution is observed. Specifically, a controlled distribution of the exudate being held and removed respectively was observed.

[0086] The absorbent structure 103 is preferably embossed. In other words, the surface of the absorbent structure 103 is structured and may include a plurality of depressions and protrusions (not shown). This is beneficial because the absorbent structure 103 including multiple layers can become firm and thick with an increase in basis weight. Embossing enables the absorbent structure to remain flexible while maintaining its shape and thickness.

[0087] The superabsorbent layer 103a can be an airlaid superabsorbent layer. In an embodiment, the airlaid superabsorbent layer 103a includes superabsorbent particles, cellulosic fibers, and bicomponent fibers.

[0088] For example, the airlaid superabsorbent layer can include the following: - 30 to 50% by weight, preferably 35 to 50% by weight of superabsorbent particles, - 30 to 50% by weight, preferably 40 to 50% by weight of cellulosic fibers, - 3 to 10% by weight, preferably 5 to 8% by weight of bicomponent fibers, - 3 to 8% by weight of polyethylene.

[0089] Such a superabsorbent layer enables improved liquid handling characteristics and proper liquid distribution. Further, it prevents gel blockage and prevents the absorbent structure from collapsing when dealing with large amounts of fluid.

[0090] The bicomponent fibers act as a binder and in particular maintain the shape of the SAP layer in the wet state. The bicomponent fibers may be made of polyethylene and polyethylene terephthalate (PE / PET).

[0091] The thickness of the superabsorbent layer 103a can be 0.8 to 2.5 mm, for example 1.4 to 2.2 mm, for example 1.8 to 2.0 mm. The thickness is measured under dry conditions.

[0092] In an embodiment, the absorbent structure 103 includes an additional layer.

[0093] The backing layer 101 and the adhesive skin contact layer 102 are configured to extend beyond the periphery of the absorbent structure 103 to form an edge portion 108 along the contour of the absorbent structure 103. In other words, the covering material includes a pad portion and an edge portion 108. The pad portion includes the absorbent structure 103 and the liquid spreading layer 106. Thus, the edge portion 108 is also configured to extend beyond the periphery of the liquid spreading layer 106. In an embodiment, the pad portion includes an additional layer.

[0094] In a preferred embodiment, the adhesive skin contact layer 102 includes a plurality of apertures 109 within a region below the absorbent structure 103, but no apertures are provided within the region forming the edge portion 108.

[0095] The absence of apertures in the edge portion of the covering material is beneficial for improving the adhesion at the edge portion 108 of the covering material and thus improving the residual capacity of the covering material.

[0096] The adhesive skin contact layer 102 is the lowermost layer of the covering material. The adhesive skin contact layer 102 is configured to adhesively attach the covering material to the skin surface in a removable manner. In other words, the adhesive skin contact layer 102 is configured to contact the skin or wound of the wearer. This layer can also be referred to as a "wound contact layer" or a "skin contact layer".

[0097] The adhesive skin contact layer 102 preferably contains a silicone-based adhesive, i.e., a silicone gel. The adhesive skin contact layer containing a silicone gel is gentle to the skin and can be easily removed without causing trauma. This adhesive skin contact layer has sufficient adhesive force to the skin in such a form that the covering material stays in place, and is configured to maintain its adhesive force even when removal and reattachment are repeated.

[0098] As shown in FIG. 1b, the adhesive skin contact layer 102 can include two layers. For example, the adhesive skin contact layer 102 can include a polymer-based film 102a and a silicone gel layer 102b, and the silicone gel layer 102b is configured to contact the skin of the wearer.

[0099] The polymer-based film 102a is preferably a breathable film and can include, for example, polyethylene, polyamide, polyester, or polyurethane. Preferably, the polymer-based film contains polyurethane. The thickness of the polyurethane film can be 15 to 100 μm, for example 20 to 80 μm, preferably 20 to 60 μm.

[0100] Examples of silicone gels suitable for use within the adherent skin contact layer 102 and / or within the silicone gel layer 102b include the two-component RTV systems described herein, such as Q72218 (Dow Corning) and SilGel612 (Wacker Chemie AG), as well as NuSil silicone elastomers. In embodiments of the present invention, the adhesive can include a soft silicone gel having a softness (penetration) of 8 - 22 mm, such as 12 - 17 mm, when measured by methods based on ASTM D 937 and DIN 51580, which are described in Patent Document 2 (European Patent Application No. 14194054.4). The thickness of the adherent skin contact layer is generally at least 20 μm. The thickness of the adherent skin contact layer may be 100 - 200 μm.

[0101] The adherent skin contact layer 102 includes a plurality of apertures 109. The apertures 109 extend through the polymeric film 102a (if present) and the silicone gel layer 102b.

[0102] The covering 100 can further include a permeable layer 110 disposed between the adherent skin contact layer 102 and the absorbent structure 103.

[0103] The permeable layer 110 can include a foam, a needle-punched nonwoven, a through-air bonded nonwoven, or a spacer fabric. The permeable layer 110 is not limited to a particular material, and any material configured to reliably transmit negative pressure to the wound area under both wet and dry conditions can be used. The permeable layer 110 ensures that fluid can be transported into the absorbent structure away from the wound site so that the skin can remain in a relatively dry state.

[0104] Preferably, the permeable layer 110 includes a spacer fabric. The spacer fabric is a three-dimensional material often utilized within negative pressure wound therapy (NPWT) coverings.

[0105] In an embodiment, the spacer fabric layer has a thickness of 1.5 to 4 mm, for example 2 to 3 mm. The thickness is measured under dry conditions. The basis weight of the spacer fabric is 150 to 500 g / m 2 (gsm), for example 200 to 350 g / m 2 (gsm), and can be.

[0106] The spacer fabric layer 110 generally includes a top layer, a bottom layer, and an interconnecting layer of pile filaments between the top layer and the bottom layer. The interconnecting layer of pile filaments can have a fineness of 200 to 500 denier, for example 250 to 350 denier.

[0107] The spacer fabric layer 110 has high compressive strength and is configured to withstand the pressure applied to the covering material during use. After the compressive force is applied to the covering material, the permeable layer 110 is configured to return to its original shape immediately after the force is removed.

[0108] In an embodiment, the covering material includes a plurality of adhesive strips 111 between the permeable layer 110 and the absorbent structure 103.

[0109] The adhesive strip 111 is configured to stop the flow of exudate towards the coupling member 104 and the tubing 105. As described above, the covering material 100 of the present disclosure preferably has a structure that allows for a proper and substantially equal balance between the covering material and the fluid collection means disposed remotely therefrom.

[0110] When wound exudate is flowing from the wound site, it is first dealt with by the permeable layer 110. When it exits from the permeable layer 110, the adhesive strip 111 serves to guide the exudate into the absorbent structure 103 above rather than flowing directly towards the tubing 105. Therefore, providing the adhesive strip 111 can contribute to the desired distribution of wound exudate between the remotely located canister and the covering material. The area below the opening 107 preferably does not contain any adhesive strip. This is to prevent clogging and obstruction of the tubing 105 and the coupling member 104.

[0111] "A plurality of strips" means that the covering material includes at least two adhesive strips. For example, the covering material can include 2 to 10, such as 2 to 6, adhesive strips depending on the size of the covering material.

[0112] The adhesive strip 111 can be arranged across the width of the covering material 100. Therefore, the adhesive strip can be arranged to extend between the side edges of the permeable layer 110 and / or the absorbent structure 103. The strip is preferably arranged at a right angle to the flow path of the exudate towards the tubing 105. Therefore, the adhesive strip 111 is arranged in such a way that the exudate flowing into the covering material always encounters the adhesive strip 111 when flowing towards the tubing 105.

[0113] The adhesive is preferably a hot melt adhesive. The width of the adhesive strip can be in the range of 3 to 25 mm, such as 5 to 15 mm, such as 6 to 10 mm.

[0114] The distance between the adhesive strips 111 can be 10 to 50 mm, such as 15 to 30 mm. The distance between the adhesive strips 111 can be affected by the size and shape of the covering material 100.

[0115] The permeable layer 110, the absorbent structure 103 and the liquid spreading layer 106 can be collectively referred to as the wound pad of the covering material.

[0116] In an embodiment, the backing layer 101 has a water vapor transmission rate (MVTR) in the range of 500 to 3500 g / m 2 / 24 h, preferably in the range of 600 to 2700 g / m 2 / 24 h, for example, in the range of 1400 to 2600 g / m 2 / 24 h, as measured by NWSP070.4R0(15).

[0117] The backing layer 101 is the outermost layer of the covering material and is configured to face outward as seen from the skin of the wearer.

[0118] The "water vapor transmission rate (MVTR)" is the rate at which the backing layer allows moisture to penetrate from the backing layer. The water vapor transmission rate is measured by the standard method NWSP070.4R0(15). The MVTR is measured at a temperature of 38°C.

[0119] Surprisingly, this range has been shown to produce a positive effect when the covering material is used in negative pressure wound therapy. More stable treatment is observed with a relatively low frequency of operation of the negative pressure source, and yet the exudate fluid collected within the covering material can be successfully evaporated from the backing layer to the surrounding environment. Overall, this results in a positive effect from the viewpoints of battery consumption, noise reduction, and long-term and more stable wound treatment.

[0120] When the covering material 100 of the present disclosure is applied within an NPWT system including remotely located fluid collection means, wound exudate is withdrawn from the wound site to the fluid collection means using tubing 105.

[0121] For the continuous (or intermittent) removal of exudate through tubing, it is required to operate the NPWT source, i.e., the vacuum pump, at regular intervals. However, if the pump is operated too frequently and at a speed that is "more than necessary", this will result in negative consequences regarding noise and battery consumption. In the covering material 100 of the present disclosure, as demonstrated in Example 4 below, at least a 26% reduction in pump operation was observed.

[0122] In an embodiment, the backing layer 101 has a tensile strength in the machine direction (MD) and / or the machine cross direction (CD) of 30 to 70 MPa, preferably 35 to 55 MPa, as measured by ISO 527-3 / 2 / 20. The tensile strength is measured on a 15 mm wide strip.

[0123] Preferably, the backing layer 101 has sufficient "strength" to withstand the forces applied on the backing layer during the patient's movement and yet allow for flexibility and sufficient stretchability.

[0124] The inventors have discovered that the tensile strength of the backing layer also affects providing a stable and reliable treatment. The backing layer must have sufficient rigidity to prevent tearing or breaking of the backing layer during the patient's movement. For example, the thicker the absorbent structure, the more likely it is to rub against the backing layer at the edges, so the edges of the absorbent structure are particularly likely to break. If perforations or slits are formed in the backing layer, this may be accompanied by unwanted air leakage into the covering material and the system. As a result, the stability of the treatment and the system is impaired. However, the backing layer must still have sufficient flexibility to allow the covering material to adapt to the user's movement or the flexion of joints such as the knee.

[0125] The backing layer 101 generally includes a thermoplastic elastomer. The thermoplastic elastomer has the ability to stretch and contract up to a moderate elongation and return to its original shape when the stress is removed. Examples of suitable materials containing thermoplastic elastomers include polyurethane, polyamide, and polyethylene.

[0126] The backing layer may similarly be a laminate of a polyester nonwoven material and at least one polyurethane film.

[0127] Preferably, the backing layer contains thermoplastic polyurethane.

[0128] The thickness of the backing layer may be in the range of 10 - 40 μm, preferably 15 - 30 μm.

[0129] The backing layer 101 can include at least one film. For example, the backing layer can include two or more films. In an embodiment, the backing layer is a laminate formed by two or more films. A thin layer of an adhesive such as a polyacrylate adhesive can be applied to the backing layer to attach the backing layer to the adhesive skin contact layer or, if present, any other layer of the absorbent structure or covering. Within the framework of the present disclosure, the backing layer 101 includes at least one film containing a thermoplastic elastomer and an adhesive (such as polyacrylate) applied thereon. The adhesive can be applied in a continuous or discontinuous pattern.

[0130] As shown in FIG. 1a, the tubing 105 includes a fluid conduit 112 configured to remove fluid from the covering and an air conduit 113 configured to supply air to the fluid conduit 112 and / or the covering 100. Further, the tubing 105 is configured to transmit negative pressure to the covering and the wound site.

[0131] The tubing 105 and / or the coupling member 104 may be any suitable flexible tubing made of an elastomeric and / or polymeric material. The tubing is attached to the coupling member 104. In an embodiment, the tubing 105 is rigidly attached to the coupling member 104. In an alternative embodiment, the tubing 105 is detachably attached to the coupling member 104.

[0132] The coupling member 104 generally includes an attachment portion configured to be attached to the backing layer of the dressing. The coupling member may be attached to the backing layer by adhesion. The coupling member may similarly also include a fluid inlet and a fluid outlet configured to be connected to the tubing 105, i.e., the air conduit 113 and the fluid conduit 112, respectively.

[0133] The coupling member may have a structure as defined in Patent Document 1 (EP Application No. 13152841.6).

[0134] In an embodiment, the distal end of the tubing 105 is connected to a first connector portion 114. The first connector portion 114 is configured to be connected to a remote fluid collection means, i.e., a second connector portion associated with a canister, and in an embodiment, to a negative pressure source (see, for example, FIG. 3 which illustrates a second connector portion 123 associated with a canister). Further, the tubing 105 is configured to transmit negative pressure to the dressing and the wound site.

[0135] FIG. 2 conceptually shows a negative pressure wound therapy (NPWT) system according to the present disclosure.

[0136] A negative pressure wound therapy (NPWT) system 200 includes the NPWT dressing 100 according to the present disclosure. The dressing 100 is applied to the knee of a patient 115.

[0137] The NPWT system 200 includes the following: - The negative pressure wound therapy (NPWT) dressing 100 described above herein, and - A negative pressure source, and - A remote fluid collection means 117 fluidly connected to the negative pressure source and the covering material 100.

[0138] The negative pressure source is a negative pressure pump adapted to establish a negative pressure when the pump is in operation. The negative pressure pump can be any type of pump that is biocompatible and maintains or induces an appropriate and therapeutically effective vacuum level. Preferably, the negative pressure level to be achieved is in the range of about -2666.4 Pa (-20 mmHg) to about -39996.7 Pa (-300 mmHg). In embodiments of the present disclosure, a negative pressure range of about -10665.8 Pa (-80 mmHg) to about -23998.0 (-180), preferably about -13332.2 (-100) to -19998.4 Pa (-150 mmHg), more preferably -14665.5 (-110) to -18665.1 (-140 mmHg) Pa is used. In an embodiment, the negative pressure pump is a diaphragm type or peristaltic type pump.

[0139] As used herein, the term "fluidly connected" should be construed broadly and may include any form of tubing, conduit, or channel that provides fluid connection / communication between the remote fluid collection means 117 and the negative pressure source and the covering material 100.

[0140] The remote fluid collection means 117 can be any type of fluid container, such as a canister. Alternatively, it may be an absorbent material present inside the tubing of the NPWT covering material or NPWT system, or an absorbent structure disposed between the covering material or the covering material of the present disclosure and the canister. Generally, the remote fluid collection means 117 is a canister.

[0141] In FIG. 2, the negative pressure source is included inside the housing 116 of a portable negative pressure wound therapy (NPWT) device 118. The canister is preferably detachably connected to the housing 116.

[0142] In other words, the canister 117 is detachably connected to the housing 116. The detachable connection may be by conventional means including friction fit, bayonet connection, snap fit, connector with locking claws, etc. The detachable configuration enables the user or caregiver to remove the canister 117, empty the collected liquid, and then reattach the canister 117 to the housing 116.

[0143] The canister 117 can be formed from, for example, molded plastic. The canister 117 is preferably at least partially transparent / translucent so that the interior of the canister 117 can be inspected to assist the user in determining the remaining capacity of the canister 117.

[0144] For example, the internal volume of the canister 117 is 30 - 300 ml, such as 40 - 150 ml. The internal volume of the canister 117 can vary depending on the type of wound. In an embodiment, the canister 117 contains a liquid absorbent material. In a possible embodiment, at least 75% of the internal volume of the canister 117 is occupied by the liquid absorbent material.

[0145] The NPWT device 118 can be connected to the dressing 101 using tubing 105. In the embodiment shown in FIG. 2, the NPWT system includes a connector unit 119 at the position between the dressing 100 and the NPWT device 118. The connector unit 119 can include a first connector portion (designated 114 in FIG. 1) and a second connector portion (see 123 in FIG. 3). The connector portions 114 and 123 are preferably detachably connected so that the dressing can be easily disconnected from the NPWT device 118. This is beneficial in a portable NPWT system as the user may decide to disconnect the dressing from the device 118 when they want to take a shower themselves or for some other reason.

[0146] In FIG. 2, the tubing 105 is a double conduit, while the tubing 120 between the NPWT device 118 and the connector unit 119 is a single conduit. The NPWT system is by no means limited to such a configuration, and may include a single conduit or a double conduit between the NPWT device 118 and the dressing 100. Similarly, the NPWT system is not limited to the use of the connector unit 119. The tubing 105 may be configured to extend all the way to the NPWT device 118 in an embodiment.

[0147] The NPWT system 200 preferably includes means for supplying air to the dressing at a flow rate of 2 to 7 ml / min during operation.

[0148] Preferably, the means for supplying air to the dressing is configured to supply air at a negative pressure of -10665.8 (-80) to -23998.0 Pa (-180 mmHg), preferably -13332.2 (-100) to -19998.4 Pa (-150 mmHg), more preferably -14665.5 (-110) to -18665.1 (-140 mmHg) at a rate of 2 to 7 ml, preferably 3 to 5 ml.

[0149] In the NPWT system 100 shown in FIG. 2, ambient air is introduced into the system using the connector unit 119 (indicated by the arrow 121). For example, the first and / or second connector portions (114 and 123) include an air filter (not shown) configured to control the supply of air into the dressing 100 and / or the tubing 105. The first and / or second connector portions (114 and 123) can include, for example, an intake port with an air filter disposed therein.

[0150] The air filter preferably includes a hydrophobic and porous material, where the pore size is in the range of 2 to 20 μm, preferably in the range of 5 to 12 μm. The pore diameter of the filter is measured in the uncompressed state.

[0151] The air filter preferably includes polyethylene, preferably sintered polyethylene.

[0152] The sintered polyethylene filter has a repeating linear molecular structure -CH2-CH2. This structure is inert with strong molecular bonds and is characterized by improved chemical resistance, lightweight, thermoplasticity, and excellent filtration characteristics. The sintered polyethylene filter is also environmentally friendly as it produces no toxic waste and can be rinsed and reused.

[0153] The air filter ensures that during operation, the supply of air is within the range of 2 to 7 ml / min at a negative pressure, for example, -10665.8 Pa (-80 mmHg) to -19998.4 Pa (-150 mmHg), for example, -13332.2 (-100 mmHg) to -17331.9 Pa (-130 mmHg).

[0154] It should be pointed out that air can be introduced into the system in an alternative form, and an air filter can be provided at an alternative location within the system. The regulation of the air supply can be controlled by the NPWT device 118 in an embodiment.

[0155] In use, the dressing 100 is placed on the wound site of the user / patient, forming a sealed space. Tubing (105 and 120) is provided to fluidly couple the dressing 100 to an NPWT device 118, such as an inlet port of the NPWT device 118. At this time, the NPWT device 118 is actuated by the user / patient, for example, by pressing a start / stop button 122. Thereby, the negative pressure pump is actuated. When actuated, the negative pressure pump will start to discharge air through the sealed space formed by the canister 117, the tubing (120 and 105), and the dressing 100. Thus, a negative pressure is created inside the sealed space. If liquid is formed at the wound site, this liquid from the wound site can be "drawn in" at least partially from the wound site through the tubing (105 and 120) into the canister 117. The amount of liquid, i.e., exudate, withdrawn from the wound and collected in the canister 117 depends on the wound being treated and the type of wound dressing used. Within the framework of the present disclosure, a substantially equal balance in the liquid distribution is desired. For the purpose of ensuring that no liquid can pass from the canister 117 to the negative pressure pump, a suitable filter member (not shown) can be disposed between the canister 117 and the negative pressure pump.

[0156] The canister 117 may include an inlet port to enable connection to the tubing 120. The connection between the inlet port and the tubing 120 is preferably a sealed connection, thus ensuring that no leakage is formed at the inlet port during normal operation of the NPWT device 118. The tubing 120 is preferably removably connected to the inlet port through conventional means including friction fit, bayonet coupling, snap fit, a connector with locking claws, etc. A similar sealed connection is also formed between the canister 117 and the negative pressure pump.

[0157] FIG. 3 shows a kit 300 according to an exemplary embodiment. The kit 300 includes at least one NPWT dressing 100 as described above.

[0158] The covering material includes the tubing 105. Preferably, the tubing 105 is pre - attached to the covering material, for example, using a coupling member 104 attached to the lining layer of the covering material 100. The fact that the tubing 105 is pre - attached enables rapid assembly of the system / kit components.

[0159] The distal end of the tubing 105 is connected to a first connector portion 114. The kit can further include a negative pressure source disposed inside the housing 116. The kit can similarly include a canister 117. The canister can include a second tubing 120. The distal end of the second tubing 120 can include a second connector portion 123. The second connector portion 123 is configured to be connected to the first connector portion 114 associated with the tubing 105 of the covering material 100. The kit 300 can include additional components such as an additional battery 124 for powering the NPWT device 118 and an adhesive strip 125 for improving the adhesion between the edge portion of the covering material and the user's skin.

[0160] The kit shown in FIG. 4 is adapted for home care but can be used equally advantageously in an environment such as a hospital or a care facility. The NPWT device is adapted to be carried by the user, for example, in a pocket, on a belt, a strap, or the like. The covering material 100 and the other components of the kit 300 can be easily assembled by the user.

[0161] The components of the kit 300 can vary. For example, one kit may include all of the above - described components, while another kit may include only two or three components.

[0162] The kit 300 can include a plurality of NPWT covering materials as described above, optionally packaged together with a plurality of adhesive strips.

[0163] Accordingly, the kit 300 includes the negative pressure wound treatment dressing described above and at least one additional component, where the additional component is selected from among a negative pressure source, the canister 117, the battery 124, and / or the adhesive strip 125.

[0164] The NPWT device 118 used within the kits (and within the NPWT systems) of the present disclosure includes the features and components necessary to control the operation of the device. For example, the NPWT device may include a control unit electrically connected to a battery. Such a control unit may include a microprocessor, a microcontroller, a programmable digital signal processor, or another programmable device. Additionally, the NPWT device 118 can include at least one pressure sensor disposed in fluid communication with a negative pressure pump.

Example

[0165] Example 1: Liquid Distribution Comparative Test To test the distribution of liquid between the dressing and the canister, a comparative test was conducted using three dressings (Dressing A, Dressing C, and Dressing D, respectively).

[0166] Dressing A included, from bottom to top, an adhesive skin contact layer including a polyurethane film and a silicone gel layer, a spacer fabric permeable layer, an absorbent structure (including a nonwoven liquid spreading layer, the above-described Airlaid SAP layer, and a tissue layer), a nonwoven liquid spreading layer, and a backing layer, respectively. Dressing C had the same layer structure as Dressing A, but had a higher basis weight of the absorbent structure, and the amount and retention capacity of the superabsorbent particles per 1 cm 2 were different.

[0167] Dressing D had the same overall layer structure but was different with respect to the absorbent structure. The absorbent structure of Dressing D included an absorbent layer containing 40 wt% superabsorbent fibers (SAF) and 60 wt% polyester (polyethylene terephthalate) fibers, as well as a nonwoven spreading layer. No superabsorbent particles were present within the absorbent structure of Dressing D.

[0168] All of the coverings (A, C, and D) included pre-attached tubing including air conduits and fluid conduits.

[0169] Furthermore, all of the coverings (A, C, and D) included a non-woven liquid spreading layer disposed over the absorbent structure. The non-woven liquid spreading layer included 50 wt% viscose fibers and 50 wt% bicomponent fibers. See Table 1 below for further details of the absorbent structure of the covering.

[0170] [Table 1]

[0171] Retention capacity was measured as described in Example 2 below.

[0172] The pre-weighed covering was attached to a plexiglass plate sized larger than the covering area. The plexiglass plate had a hole for liquid inflow. The covering was positioned such that the liquid inflow came within the central portion of the covering. Each covering included tubing connected to the mobile type negative pressure device shown in Figure 2. The pump used was a diaphragm type pump. A canister configured to store 50 ml of liquid was used and connected to the pump disposed inside the housing disclosed in Figure 2. As described above, the covering and the NPWT device (including the canister and the pump) were connected by their respective connector portions. An air filter was placed inside the first connector portion associated with the tubing of the covering. Ambient air was introduced into the connector and into the system such that the air supply to the covering was within the range of 2 - 7 ml / min. The pump was operated and a negative pressure of -16665.3 Pa (-125 mmHg) was applied to the covering.

[0173] With a flow rate of 300 ml over 7 days (for coatings C and D) and 386 ml over 9 days (for coating A), test liquid (horse serum) was added to the center of each coating. The negative pressure inside the coating was maintained at -16665.3 Pa (-125 mmHg) throughout the entire test period. After the test period, the wet weights of the coatings and the canister were recorded. The distribution of the test liquid between each coating and the canister was calculated.

[0174] As can be seen in Figure 4, the liquid distribution between coating A and the canister was 61:39. For coating C, on the other hand, most of the liquid was retained within the coating (90%), with only 10% being transferred to the canister. Coating D had a liquid distribution of 34:66 (coating:canister).

[0175] After the test periods (7 days and 9 days respectively), photographs of the coatings were taken. As can be seen in Figure 5a, coating D had a relatively low liquid distribution within the coating structure. In other words, only a small part of the absorption capacity of the coating was utilized. Instead, more exudate was transferred to the canister.

[0176] Figure 5b shows coating C, where most of the coating was utilized. Although not clearly visible in this figure, the coating had a bulky and "fluffy" appearance.

[0177] Figure 5c shows coating A after 9 days of liquid exposure. Most of the coating was utilized to handle the liquid, yet at least 39% of the exudate could still be transferred to the canister. The desired liquid distribution between the fluid collection means (coating and canister) was thus achieved.

[0178] Example 2: Retention Capacity of the Coating Fluid retention capacity is defined as the ability of the coating to hold liquid.

[0179] First, the theoretical maximum absorption amount was evaluated for the coating samples. The maximum absorption capacity is the amount of liquid that the coating can absorb when exposed to excess test liquid and without any applied load.

[0180] Coated material samples A, C, and D were punched out from the central part of the coated material in a predetermined size (5×5 cm = 25 cm 2 ) so that all the layers present in the coated material were used in the test.

[0181] The area and weight of the coated material samples (A, C, and D) in the dry state were recorded. Each coated material sample was immersed in a sufficient amount of test liquid (horse serum) in a bowl. A fine mesh was placed on top of the sample and pushed down below the liquid surface with the adhesive skin contact layer facing the fine mesh. Each sample was covered with the test liquid throughout the absorption time and left to absorb for 60 minutes. When the absorption time was completed, the sample was vertically suspended at a corner of the coated material and drained for 120 seconds. The sample was allowed to absorb the liquid for 60 minutes. When the absorption time was completed, it was vertically held at a corner and the specimen was freely drained for 120 seconds (see the following figure). The maximum absorption capacity was recorded in units of grams of liquid for each sample.

[0182] After calculating the maximum absorption capacity, the same test as described above was conducted. The test liquid corresponding to 80% of the theoretical maximum absorption amount was absorbed by the sample. After 10 minutes of absorption time, a pressure equivalent to 16665.3 Pa (125 mmHg) was applied to the sample with the wound side of the sample facing down. The static pressure was maintained for 120 seconds. Then, the retention force was calculated as the weight of the horse serum retained in the sample after exposure to the static pressure. Thus, the retention ability is the ability of the product to retain the liquid under a specified amount of pressure. The retention abilities regarding coated materials A, C, and D are shown in Table 3 above.

[0183] Example 3: Effect of the liquid spreading layer in preventing backflow of liquid For the purpose of testing the ability of the covering material to address the backflow of exudate, which can be a problem when the covering material is disconnected from the NPWT device, a comparative test was prepared using the covering material (covering material A described above) according to an exemplary embodiment of the present disclosure and a reference covering material (covering material E). Covering material E had the same structure as covering material A, but lacked the liquid spreading layer of non-woven fabric between the backing layer and the absorbent structure. The tubing of each covering material was connected to a mobile negative pressure device using the same procedure as described in Example 1.

[0184] The canister was filled with approximately 52 ml of horse serum (excess liquid). When the negative pressure of -16665.3 Pa (-125 mmHg) stabilized, the canister was disconnected from the pump, and the excess liquid was backflowed into the covering material. As can be seen in FIGS. 6a and 6b, the backflow of exudate was distributed over a larger surface area in the covering material (covering material A) of the present disclosure, indicated as 100 in FIGS. 6a and 6b. In contrast, the backflow of exudate in covering material E (indicated as 601 in FIGS. 6a and 6b) did not spread significantly to a great extent, and a larger proportion of the exudate was directly backflowed towards the wound site. Thus, the liquid spreading layer contributes to the uniform spreading and distribution of exudate in both directions.

[0185] Example 4: System Stability Comparative Test A wearing test was conducted using two covering materials (covering material A and covering material B described above). Covering material A and covering material B had similar structures and differed only with respect to the backing layer. Both covering materials included pre-attached tubing containing an air conduit and a fluid conduit. The characteristics of the backing layer are listed in Table 2 below.

[0186]

Table 2

[0187] The dressing material was applied to the subject's anterior knee with the leg bent at 120 degrees (the tubing of the dressing material points upward). Using each of the connector parts shown in FIG. 2, the tubing was connected to a mobile negative pressure device. The pump used was a diaphragm pump. As disclosed in FIG. 1, a canister configured to store 50 ml of liquid was connected to the pump. The connector part attached to the distal end of the tubing of the dressing material included an air filter, and ambient air was introduced into the connector so that the supply of air to the dressing material (using an air conduit) would be within 2 - 7 ml / min during operation.

[0188] The pump was operated and a negative pressure of -16665.3 Pa (-125 mmHg) was applied to the dressing material. The time Toff between the operation of multiple pumps was recorded over the first 5 hours (0 - 5 hours and 3 - 5 hours respectively), which is an indication of the stability of the system and a means to ensure that no unwanted air is introduced into the system.

[0189] The test was conducted on 5 subjects and the average Toff was recorded over 0 - 5 hours and 3 - 5 hours.

[0190] The average Toff was 26 seconds for dressing material B and 35 seconds for dressing material A during the 0 - 5 hour period. This represents a 26% improvement. The improvement was even more significant during the 3 - 5 hour period, where Toff was 40% higher for the dressing materials of the present disclosure. The results are shown in FIG. 7 and Table 3 below. These results indicate that the properties of the backing layer affect the stability of negative pressure wound therapy. The system is stable and airtight, and the pump does not need to operate very powerfully.

[0191]

Table 3

[0192] The terms, definitions, and embodiments of all aspects of the present disclosure are applied with the necessary modifications to other aspects of the present disclosure.

[0193] Although the present disclosure has been described in connection with its specific exemplary embodiments, many different modifications, corrections, etc. will become apparent to those skilled in the art.

[0194] By considering the drawings, the disclosure, and the appended claims, those skilled in the art can understand and achieve variations of the disclosed embodiments in practicing the present disclosure. Further, in the claims, the term "comprising (including ~)" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. As embodiments of the present invention, there are the following. [Aspect 1] In a negative pressure wound therapy (NPWT) dressing (100) including a backing layer (101), an adhesive skin contact layer (102), and an absorbent structure (103) disposed between the backing layer (101) and the adhesive skin contact layer (102); the adhesive skin contact layer (102) is configured to adhesively attach the dressing (100) to the skin surface in a detachable manner, and the backing layer (101) includes a coupling member (104) including a pipe (105) configured to connect the dressing (100) to a negative pressure source and a remote fluid collection means, wherein the dressing includes a liquid spreading layer (106) disposed between the absorbent structure (103) and the backing layer (101). A negative pressure wound therapy (NPWT) dressing (100), characterized in that. [Aspect 2] At least a part of the absorbent structure (103) and the backing layer (101) include an opening (107); the opening (107) is disposed under the coupling member (104); and the liquid spreading layer (106) is not provided with an opening. The negative pressure wound therapy (NPWT) dressing (100) according to Aspect 1. [Aspect 3] The liquid spreading layer (106) is configured to extend over at least 90% of the surface area of the absorbent structure (103). The negative pressure wound therapy (NPWT) dressing (100) according to Aspect 1 or 2. [Aspect 4] The liquid spreading layer (106) is a hydrophilic and porous layer. The negative pressure wound therapy (NPWT) dressing (100) according to any one of Aspects 1 to 3. [Aspect 5] The liquid spreading layer (106) includes a non-woven fabric. The negative pressure wound therapy (NPWT) dressing (100) according to any one of Aspects 1 to 4. [Aspect 6] The absorbent structure (103) contains superabsorbent particles in an amount of 10 to 20 mg / cm 2 , preferably 13 to 17 mg / cm 2 . The negative pressure wound therapy (NPWT) dressing (100) according to any one of Aspects 1 to 5. [Aspect 7] The absorbent structure (103) includes a first liquid spreading layer (103b), a superabsorbent layer (103a), and a second liquid spreading layer (103c), and the superabsorbent layer (103a) is disposed between the first and the second liquid spreading layers (103b, 103c). The negative pressure wound therapy (NPWT) dressing (100) according to any one of Aspects 1 to 6. [Aspect 8] The absorbent structure (103) is embossed. The negative pressure wound therapy (NPWT) dressing (100) according to any one of Aspects 1 to 7. [Aspect 9] The backing layer (101) and the adhesive skin contact layer (102) are configured to extend beyond the peripheral portion of the absorbent structure (103) to form an edge portion (108) along the contour of the absorbent structure (103). The adhesive skin contact layer (102) includes a plurality of apertures (109) within a region below the absorbent structure (103), but no apertures are provided within the region forming the edge portion (108). The negative pressure wound therapy (NPWT) dressing (100) according to any one of Aspects 1 to 8. [Aspect 10] The dressing (100) further includes a permeable layer (110) disposed between the adhesive skin contact layer (102) and the absorbent structure (103), and the permeable layer (110) includes a spacer fabric. The negative pressure wound therapy (NPWT) dressing (100) according to any one of Aspects 1 to 9. [Aspect 11] The dressing (100) includes a plurality of adhesive strips (111) between the absorbent structure (103) and the permeable layer (110). The negative pressure wound therapy (NPWT) dressing (100) according to Aspect 10. [Aspect 12] The backing layer (101) has a water vapor transmission rate (MVTR) in the range of 500 to 3500 g / m 2 / 24 h, preferably in the range of 600 to 2700 g / m2 / 24 h when measured by NWSP070.4R0(15). The negative pressure wound therapy (NPWT) dressing (100) according to any one of Aspects 1 to 11. [Aspect 13] The tubing (105) includes a fluid conduit (112) configured to remove fluid derived from the dressing, and an air conduit (113) configured to supply air to the fluid conduit (112) and / or the dressing (100). The negative pressure wound therapy (NPWT) dressing (100) according to any one of Aspects 1 to 12. [Aspect 14] - A negative pressure wound therapy (NPWT) dressing (100) according to any one of aspects 1 to 13, - A negative pressure source, - Remote fluid collection means (117) fluidly connected to the negative pressure source and the dressing (100), A negative pressure wound therapy (NPWT) system (200) comprising. [Aspect 15] The remote fluid collection means (117) is a canister, and the canister and the negative pressure source are arranged inside the same device (118); the device (118) includes a housing (116), the negative pressure source is arranged inside this housing, and the canister (117) is detachably connected to the housing (116). The negative pressure wound therapy (NPWT) system (200) according to aspect 14. [Aspect 16] A negative pressure wound therapy (NPWT) system (300) according to aspect 14 or 15, comprising means for supplying air to the dressing at a flow rate of 2 to 7 ml / min during operation. [Aspect 17] A kit (300) comprising a negative pressure wound therapy (NPWT) dressing (100) according to any one of aspects 1 to 13 and at least one additional component selected from a negative pressure source, a canister (117), a battery (124) and / or an adhesive strip (125).

Claims

1. In a negative pressure wound therapy (NPWT) dressing (100) comprising a backing layer (101), an adhesive skin contact layer (102), and an absorbent structure (103) disposed between the backing layer (101) and the adhesive skin contact layer (102); the adhesive skin contact layer (102) is configured to adhesively attach the dressing (100) to the skin surface in a removable manner, the backing layer (101) and the adhesive skin contact layer (102) extend beyond the periphery of the absorbent structure (103) to form an edge portion (108) along the contour of the absorbent structure (103), and the adhesive skin contact layer (102) includes a plurality of apertures (109) within a region below the absorbent structure (103), but no apertures are provided within the region forming the edge portion (108), the backing layer (101) includes a coupling member (104) including tubing (105) configured to connect the dressing (100) to a negative pressure source and a remote fluid collection means, and the dressing includes a liquid spreading layer (106) disposed between the absorbent structure (103) and the backing layer (101), at least a portion of the absorbent structure (103) and the backing layer (101) include an opening (107); the opening (107) is disposed under the coupling member (104); and no opening is provided in the liquid spreading layer (106), which is characterized by a negative pressure wound therapy (NPWT) dressing (100).

2. The negative pressure wound therapy (NPWT) dressing (100) according to claim 1, wherein the liquid spreading layer (106) is configured to extend over at least 90% of the surface area of the absorbent structure (103).

3. The negative pressure wound therapy (NPWT) dressing (100) according to claim 1 or 2, wherein the liquid spreading layer (106) is a hydrophilic and porous layer.

4. The negative pressure wound therapy (NPWT) dressing (100) according to any one of claims 1 to 3, wherein the liquid spreading layer (106) comprises a non-woven fabric.

5. The absorbent structure (103) contains superabsorbent particles in an amount of 10 to 20 mg / cm 2 The negative pressure wound therapy (NPWT) dressing (100) according to any one of claims 1 to 4.

6. The absorbent structure (103) includes a first liquid spreading layer (103b), a superabsorbent layer (103a), and a second liquid spreading layer (103c), and the superabsorbent layer (103a) is disposed between the first and second liquid spreading layers (103b, 103c). The negative pressure wound therapy (NPWT) dressing (100) according to any one of claims 1 to 5.

7. The absorbent structure (103) is embossed. The negative pressure wound therapy (NPWT) dressing (100) according to any one of claims 1 to 6.

8. The dressing (100) further includes a permeable layer (110) disposed between the adhesive skin contact layer (102) and the absorbent structure (103), and the permeable layer (110) includes a spacer fabric. The negative pressure wound therapy (NPWT) dressing (100) according to any one of claims 1 to 7.

9. The dressing (100) includes a plurality of adhesive strips (111) between the absorbent structure (103) and the permeable layer (110). The negative pressure wound therapy (NPWT) dressing (100) according to claim 8.

10. The backing layer (101) has a water vapor transmission rate (MVTR) in the range of 500 to 3500 g / m 2 / 24 h. The negative pressure wound therapy (NPWT) dressing (100) according to any one of claims 1 to 9.

11. The negative pressure wound therapy (NPWT) dressing (100) according to any one of claims 1 to 10, wherein the tubing (105) includes a fluid conduit (112) configured to remove fluid derived from the dressing and an air conduit (113) configured to supply air to the fluid conduit (112) and / or the dressing (100). **Claim 12** - A negative pressure wound therapy (NPWT) dressing (100) according to any one of claims 1 to 11; - A negative pressure source; - Remote fluid collection means (117) fluidly connected to the negative pressure source and the dressing (100); A negative pressure wound therapy (NPWT) system (200) comprising the above. **Claim 13** The negative pressure wound therapy (NPWT) system (200) according to claim 12, wherein the remote fluid collection means (117) is a canister, the canister and the negative pressure source are disposed inside the same device (118); the device (118) includes a housing (116) in which the negative pressure source is disposed, and the canister (117) is detachably connected to the housing (116). **Claim 14** The negative pressure wound therapy (NPWT) system (200) according to claim 12 or 13, comprising means for supplying air to the dressing at a flow rate of 2 to 7 ml / min during operation. **Claim 15** A kit (300) comprising a negative pressure wound therapy (NPWT) dressing (100) according to any one of claims 1 to 11 and at least one additional component selected from a negative pressure source, a canister (117), a battery (124), and / or an adhesive strip (125).

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