Wound dressing material

Abstract

Disclosed is a wound dressing comprising a wound contact layer, a backing layer, an intermediate layer positioned between the backing layer and the wound contact layer and including a first surface facing the wound contact layer and a second surface facing the backing layer, the first surface of the intermediate layer being directly or indirectly adhered to the wound contact layer and the second surface not adhered to the backing layer, and a wound site adhesive layer provided in a peripheral region of the backing layer for adhering the backing layer to a wound site.

Description

[Technical field]

[0001] The present invention relates to an absorbent wound dressing. [Background technology]

[0002] It is known to manufacture wound dressings for use on exuding wounds. Such dressings manage the exudate from the wound in a variety of ways. For example, some dressings, primarily based on foam, manage the exudate by absorbing the exudate and allowing the water absorbed by the dressing to evaporate through the lining or top of the dressing. Such dressings are not designed to absorb and retain the exudate, but rather to absorb it and wick it away by water vapor transmission in order to maximize the level of exudate management within the design limits. A disadvantage of such dressings is that the open structure of the foam material does not prevent the exudate from spreading laterally across the dressing, resulting in saturation of the entire surface of the dressing, which can lead to maceration of healthy skin surrounding the wound.

[0003] A further disadvantage of the open structure of the foam material is that when the dressing is subjected to pressure, for example when compression is applied or when the patient sits, lies down, turns over and exerts force on the dressing, exudate may be forced out of the porous open foam material structure and come into contact with the wound and / or surrounding skin surface resulting in softening of the wound periphery and, in the case of chronic wounds, further wound destruction due to damage caused by certain components of chronic wound exudate. A further disadvantage of such dressings is that exudate may be lost rapidly through evaporation, which may cause the wound surface to dry out over time and impede healing.

[0004] Other dressings, mainly those based on gelling absorbents, manage exudate by absorbing it and retaining it within the dressing. Although moisture within the absorbent can be lost by vapor transmission from the dressing, the exudate is retained within the gelling absorbent and is therefore less likely to be lost than with foam absorbents. The absorbent acts as a reservoir for exudate and must have sufficient capacity to retain the exudate while the dressing is worn. This affects the amount of absorbent required in the wound dressing, which of course affects the overall thickness and conformability of the dressing. Furthermore, for gelling absorbents in general, and fibrous gelling absorbents in particular, the relationship between absorbency and the thickness or weight per unit area of ​​the gelling absorbent layer is not linear. This means that a careful balance must be achieved between absorbency, conformability, and water vapor transmission.

[0005] EP2498829 describes a wound dressing disclosing an absorbent component for wound dressings, the absorbent component comprising a wound contact layer comprising gel-forming fibres bonded to a foam layer. The combination of a wound contact layer that gels and absorbs exudate, inhibiting the lateral spread of the exudate, with a foam layer that absorbs exudate but releases it easily by water vapour transmission has been shown to be an effective way to enhance liquid handling capacity. Furthermore, the absorbent wound contact layer helps to control the liquid handling properties by limiting the lateral spread of exudate within the foam and increasing the retention of exudate compared to using the foam alone. As a result, the water vapour transmission properties of the wound contact layer may be improved.

[0006] Gelling absorbents are particularly suitable for wounds with moderate exudate, as low exudate levels may cause the wound to become dehydrated and adhere to the dressing, and high exudate levels may not provide sufficient liquid handling capabilities for the gelling wound contact layer.

[0007] Known wound dressings may include an adhesive contact layer (sometimes referred to as a wound site adhesive layer) that adheres the wound dressing to the patient's skin. The known adhesive contact layer may be provided as a continuous layer that extends across the entire wound dressing and includes perforations, or as an adhesive contact layer that is only provided at the border of the dressing and may or may not include perforations. An example of a wound dressing with a perforated adhesive contact layer is described in US10231874. This document discloses a wound contact layer that includes a perforated polyurethane film coated with a skin-compatible adhesive. The perforations are disclosed to be of any desired shape and have a size range of 0.025 mm to 1.2 mm, which is believed to be small enough to allow wound exudate to flow into the dressing while preventing tissue ingrowth into the dressing. Other dressings that include a perforated adhesive layer include the applicant's existing Aquacel® FORM PRO product. The product contains a wound site adhesive layer with 1.5mm diameter perforations to enhance breathability of the dressing.

[0008] The present invention aims to provide an improved absorbent wound dressing. Summary of the Invention

[0009] The present invention provides a wound dressing as claimed in the accompanying claims.

[0010] In a first aspect, disclosed herein is a wound dressing comprising a backing layer, a wound contact layer, and a wound site adhesive layer for adhering the wound dressing to a wound site. The wound contact layer may have a first surface for direct contact with the wound bed and a second surface facing the backing layer. The wound site adhesive layer may be perforated and include a plurality of perforations.

[0011] The adhesive layer may include a border region surrounding the wound contact layer. The diameter of the perforations may be 1.6 mm to 2.7 mm. In some embodiments, the diameter of the perforations may be preferably 2.1 mm to 2.3 mm, more preferably 2.2 mm.

[0012] The adhesive layer may be confined to a border area surrounding the wound contact layer. In some embodiments, the adhesive layer may overlap the wound contact layer. The adhesive layer may adhere to the wound contact layer to hold the wound contact layer in a fixed relationship relative to the backing layer and / or the wound site.

[0013] In some embodiments, the adhesive layer may extend continuously across the first surface of the wound contact layer, such that contact between the wound contact layer and the wound may occur via the perforations.

[0014] The perforations may be uniformly distributed throughout the adhesive layer. In some embodiments, the perforations in the border regions may be different from the perforations in the central region corresponding to the wound contact layer. The perforations between the central region and the border regions may differ in size, shape, distribution (pattern) or number. The perforations in the border regions may be uniform. The perforations in the central region may be uniform. The perforations may be of a common size. The common size may be of a common diameter. Thus, for example, the perforations may all be 2.2 mm in diameter.

[0015] The perforations can be of any shape. The shape may be common to all the perforations. The perforations may be circular, for example elliptical.

[0016] The perforations are arranged in a regular array consisting of rows and columns. The center-to-center spacing of the columns may be greater than the spacing between the rows. Adjacent rows may be laterally offset from one another. The spacing between the columns may be greater than or equal to 3.9 mm and less than or equal to 8.1 mm. The spacing between the columns may be greater than or equal to 2.5 mm and less than or equal to 5.1 mm.

[0017] The adhesive may comprise a silicone adhesive. The adhesive layer may comprise an adhesive having a density of 70 grams or more and 150 grams or less per square meter.

[0018] The adhesive layer may have an inner edge that defines a central window (sometimes referred to as a central area) through which the wound contact layer may be exposed.

[0019] The wound contact layer may have an outer edge and the adhesive layer may be overlapped and adhered to the periphery of the wound contact layer. The width of the overlap between the inner edge of the adhesive layer and the outer edge of the wound contact layer may vary around the periphery of the wound contact layer.

[0020] The overlap may include one or more corner regions and one or more edge regions of the wound contact layer and the adhesive layer. The width of the overlap in the corner regions may be greater than the width of the overlap in the adjacent edge regions.

[0021] The one or more corner regions may include an inner edge having a first radius of curvature and an outer edge having a second radius of curvature. The first radius of curvature may be greater than the second radius of curvature.

[0022] The backing layer may be adhered to the adhesive layer. The wound dressing may further comprise a superabsorbent layer. The superabsorbent layer may be in adhesive-free contact with the backing layer.

[0023] The superabsorbent layer may have a first surface facing the wound contact layer and a second surface facing the backing layer. The first surface of the superabsorbent layer may include an adhesive layer.

[0024] In a second aspect, disclosed herein is a wound dressing comprising a backing layer, a wound contact layer having a first surface in direct contact with the wound bed and a second surface facing the backing layer, and a superabsorbent layer.

[0025] The wound contact layer may comprise gel-forming fibers. The superabsorbent layer may be disposed between the backing layer and the second surface of the wound contact layer.

[0026] The wound contact layer may further include a foam layer disposed between the backing layer and the second surface of the wound contact layer. The foam layer may be disposed between the wound contact layer and the superabsorbent layer.

[0027] The superabsorbent layer may comprise fibres, optionally non-woven fibres. The superabsorbent layer may consist exclusively of non-woven fibres. The non-woven fibres may be polyacrylate fibres.

[0028] The superabsorbent layer has a thickness of at least 1.5 mm and at most 2.5 mm, and may optionally be 2 mm.

[0029] The superabsorbent layer may have a first surface facing the wound contact layer and a second surface facing the backing layer. The first surface of the superabsorbent layer may include an intralayer adhesive. The intralayer adhesive may be, for example, a continuous layer, a perforated layer, a liquid or a spread coat adhesive. The intralayer adhesive may be a web including a continuous or interrupted layer of adhesive interposed between each adjacent layer and activated to bond the layers together. The intralayer adhesive may be thermally activated, for example by application of heat and pressure during the lamination process. The intralayer adhesive may include a web of strands or dots of adhesive.

[0030] The second surface of the superabsorbent layer may be configured to be movable relative to the backing layer. The superabsorbent layer may be in contact with the backing layer. The contact between the superabsorbent layers may allow for relative movement, such as sliding contact or differential expansion contact.

[0031] The backing layer may include an adhesive border region surrounding the non-adhesive central region. The superabsorbent layer may be disposed entirely within the non-adhesive central region such that it is not adhered to the backing layer.

[0032] The foam layer may have a first wound-facing surface and a second backing layer-facing surface. The first surface of the foam layer may include a first adhesive layer of foam material. The second surface of the foam layer may include a second adhesive layer of foam material. The foam layer and the superabsorbent layer may be adhered.

[0033] The foam layer may include a polyurethane foam. The foam layer may include an aliphatic foam or a methylene diphenyl disocyanate foam.

[0034] The foam layer may have a thickness of at least 1.3 mm and at most 3.2 mm, optionally 2.5 mm.

[0035] The wound contact layer may comprise cellulose fibres. The wound contact layer may comprise carboxymethyl cellulose fibres. The wound contact layer may have a thickness of 1 mm or more and 1.5 mm or less. The basis weight of the wound contact layer may be 70 gsm or more and 150 gsm or less, optionally 70 gsm.

[0036] The backing layer may comprise a polyurethane material. The backing layer may have a thickness of 30 microns.

[0037] In a third aspect, disclosed herein is a wound dressing comprising a wound contact layer, a backing layer, and an intermediate layer located between the backing layer and the wound contact layer. The wound contact layer may have a first surface facing the wound contact layer and a second surface facing the backing layer.

[0038] The first surface of the intermediate layer may be directly or indirectly adhered to the wound contact layer, and the second surface may be unadhered to the backing layer.

[0039] The dressing may further comprise a wound site adhesive layer disposed on a peripheral region of the backing layer for adhering the backing layer to the wound site.

[0040] The intermediate layer may be adhered directly or indirectly to the wound contact layer.

[0041] The wound contact layer may not be provided with a window, in other words the wound contact layer may be devoid of windows.

[0042] Thus, in one embodiment, a wound dressing is provided which comprises a wound contact layer, a backing layer, an intermediate layer located between the backing layer and the wound contact layer and including a first surface facing the wound contact layer and a second surface facing the backing layer, wherein the first surface of the intermediate layer is directly or indirectly adhered to the wound contact layer and the second surface is not adhered to the backing layer, and a wound site adhesive layer provided in a peripheral region of the backing layer and adhering the backing layer to the wound site, wherein the wound contact layer has no windows.

[0043] The wound contact layer may include gel-forming fibres.

[0044] Thus, in one embodiment, there is provided a wound dressing comprising a wound contact layer, a backing layer, an intermediate layer located between the backing layer and the wound contact layer and including a first surface facing the wound contact layer and a second surface facing the backing layer, the first surface of the intermediate layer being directly or indirectly adhered to the wound contact layer and the second surface not adhered to the backing layer, and a wound site adhesive layer being provided in a peripheral region of the backing layer for adhering the backing layer to a wound site, and the wound contact layer comprising gel-forming fibres.

[0045] The wound dressing may further comprise an adhesive for adhering the intermediate layer to the wound contact layer. The adhesive may be referred to as an intralayer adhesive or binder layer. The adhesive may comprise a spread coat adhesive.

[0046] The intermediate layer may comprise a superabsorbent layer. The superabsorbent layer may have a contour and the wound contact layer may have a corresponding contour that matches the contour of the superabsorbent layer. In other words, the contours of the superabsorbent layer and the wound contact layer may be the same and perfectly aligned.

[0047] Thus, in one embodiment, there is provided a wound dressing comprising a wound contact layer, a backing layer, an intermediate layer located between the backing layer and the wound contact layer and including a first surface facing the wound contact layer and a second surface facing the backing layer, the first surface being directly or indirectly adhered to the wound contact layer and the second surface not adhered to the backing layer, and a wound site adhesive layer provided in a peripheral region of the backing layer for adhering the backing layer to the wound site, the intermediate layer comprising a superabsorbent layer, the superabsorbent layer having an outer shape and the wound contact layer having a corresponding outer shape that matches the outer shape of the superabsorbent layer.

[0048] The superabsorbent layer may comprise polyacrylate fibres (SAF).The superabsorbent layer may comprise SAF and the wound contact layer may comprise gel forming fibres.

[0049] Thus, in one embodiment, there is provided a wound dressing comprising a wound contact layer, a backing layer, an intermediate layer located between the backing layer and the wound contact layer and comprising a first surface facing the wound contact layer and a second surface facing the backing layer, the first surface being directly or indirectly adhered to the wound contact layer and the second surface not adhered to the backing layer, and a wound site adhesive layer provided in a peripheral region of the backing layer for adhering the backing layer to a wound site, the intermediate layer comprising a superabsorbent layer, the superabsorbent layer comprising polyacrylate fibres (SAF), and the wound contact layer comprising gel-forming fibres.

[0050] The superabsorbent layer may have a thickness of 1.5 mm or more and 2.5 mm or less. Thus, in one embodiment, there is provided a wound dressing comprising a wound contact layer, a backing layer, an intermediate layer located between the backing layer and the wound contact layer and comprising a first surface facing the wound contact layer and a second surface facing the backing layer, the first surface being directly or indirectly adhered to the wound contact layer and the second surface not adhered to the backing layer, and a wound site adhesive layer provided in a peripheral area of ​​the backing layer for adhering the backing layer to a wound site, the intermediate layer comprising the superabsorbent layer, the superabsorbent layer having a thickness of 1.5 mm or more and 2.5 mm or less.

[0051] The wound site adhesive layer may be provided with perforations having a diameter of at least 1.6mm and up to 2.7mm, optionally 2.2mm.

[0052] Thus, in one embodiment, there is provided a wound dressing comprising a wound contact layer, a backing layer, an intermediate layer located between the backing layer and the wound contact layer and including a first surface facing the wound contact layer and a second surface facing the backing layer, the first surface being directly or indirectly adhered to the wound contact layer and the second surface not adhered to the backing layer, and a wound site adhesive layer provided in a peripheral region of the backing layer for adhering the backing layer to a wound site, the wound site adhesive layer including perforations having a diameter of at least 1.6 mm and not more than 2.7 mm, optionally 2.2 mm.

[0053] The wound dressing may further comprise a foam layer located between the wound contact layer and the backing layer, the foam layer conforming to a contour of the superabsorbent layer and having a foam layer contour conforming to a contour of the superabsorbent layer.

[0054] Thus, in one embodiment, a wound dressing comprises a wound contact layer, a backing layer, an intermediate layer located between the backing layer and the wound contact layer and including a first surface facing the wound contact layer and a second surface facing the backing layer, the first surface being directly or indirectly adhered to the wound contact layer and the second surface not adhered to the backing layer, and a wound site adhesive layer provided on a peripheral region of the backing layer for adhering the backing layer to a wound site, the intermediate layer comprising a superabsorbent layer, the superabsorbent layer having an outer shape, the wound contact layer having a corresponding outer shape that matches the outer shape of the superabsorbent layer, and the wound dressing further comprises a foam material layer located between the wound contact layer and the backing layer, the foam material layer corresponding to and having a matching foam material layer outer shape.

[0055] The foam layer may be disposed between the wound contact layer and the first surface of the superabsorbent layer. The foam layer may be adhered to the wound contact layer.

[0056] The wound site adhesive layer may include a border region of adhesive surrounding a central region in which the wound contact layer is located. The border region may partially cover the wound contact layer. The adhesive layer may have an inner edge defining a central window through which the wound contact layer is exposed.

[0057] Those skilled in the art will understand that, unless mutually exclusive, features described in connection with any aspect, embodiment, or example of the present disclosure may be applied mutatis mutandis to other aspects, embodiments, or examples of the present disclosure. Furthermore, unless mutually exclusive, any feature described herein may be applied to any aspect and / or combined with other features described herein. [Brief description of the drawings]

[0058] In order that the invention may be more clearly understood, one or more embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings in which:

[0059] [Figure 1] FIG. 1 shows an exploded view of a wound dressing according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 shows an exploded view of a wound dressing according to another embodiment of the present invention. [Diagram 3] FIG. 3 shows the perforation pattern of the wound site adhesive layer. [Figure 4] FIG. 4 shows a further example of a wound dressing. [Diagram 5] FIG. 5 is an example of a plan view of a wound dressing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0060] In the following detailed description, numerous specific details are set forth to provide a thorough understanding of various embodiments and inventive concepts. However, those skilled in the art will appreciate that the invention may be practiced without these specific details or with known equivalents of these specific details, that the invention is not limited to the described embodiments, and that the invention may be practiced in various alternative embodiments. It will also be appreciated that well-known methods, procedures, components, and systems may not have been described in detail.

[0061] The wound dressings described herein are absorbent wound dressings with multiple layers for absorbing exudate from the wound. The wound dressings may be comprised of a backing layer, a superabsorbent layer, a wound contact layer, and a wound site adhesive layer. In some embodiments, the dressings may also include a transmission layer. However, the layers or combinations of layers described herein comprise inventive aspects in themselves and may be used independently of other layers described in combination herein. Thus, for example, a perforated wound site adhesive layer may or may not be utilized in a dressing with a superabsorbent layer. In other examples, a dressing with a superabsorbent layer may be used in the absence of a wound site adhesive layer or a wound site adhesive layer with perforations. Nevertheless, providing a dressing with a backing layer, a superabsorbent layer, a wound contact layer, and a perforated wound site adhesive layer may be particularly advantageous with various components that provide synergistic effects on the performance of the dressing in terms of adhesion (e.g., wear time), absorbency, and versatility.

[0062] In addition to the layers described above, the wound dressings described herein and in accordance with embodiments of the present disclosure may further include one or more additional layers, such as, for example, a foam layer and / or an intralaminar adhesive layer. The additional layers may be provided to improve the performance of the dressing in one or more of liquid absorption, compatibility, retention, retention rate, and liquid handling capabilities. The wound dressing may also incorporate a release layer that protects the adhesive layer prior to use and helps maintain the sterility of the wound dressing during application of the dressing to the wound.

[0063] Wound dressings are typically described as multiple layers provided in a laminated configuration, with a wound contact layer positioned adjacent the wound in use and a backing layer provided as an outer layer defining the exterior surface of the dressing. In the present disclosure, the various layers are generally arranged concentrically, although this is not necessarily the case and in some embodiments the layers may be stacked on top of one another asymmetrically.

[0064] Each layer is described herein in relation to the backing layer and the wound site. Thus, each layer located between the wound site and the backing layer may include a first surface facing inwardly toward the wound site and a second surface facing the backing layer facing outwardly from the wound site.

[0065] One or more layers may be provided only in certain regions. For example, a wound site adhesive layer may be provided only in the peripheral or border regions of the dressing, with the central region not including a wound site adhesive layer. Additionally, some of the layers may be disposed only within the central region of the dressing, thereby being located inside the periphery.

[0066] In some embodiments, the wound dressing may include a wound contact layer, a backing layer, and an intermediate layer located between the backing layer and the wound contact layer. The intermediate layer may include a first surface facing the wound contact layer and a second surface facing the backing layer. The first surface of the intermediate layer may be directly or indirectly adhered to the wound contact layer. The second surface may be adhered or non-adhered to the backing layer to prevent or allow lateral movement therebetween and to help control moisture transmission through the backing layer.

[0067] The intermediate layer may comprise a superabsorbent layer or a foam layer. The wound dressing comprises a plurality of intermediate layers, with a first intermediate layer being in non-adhesive contact with the backing layer and indirectly adhered to the wound contact layer via a second intermediate layer. This may be advantageous, for example, when the backing layer is a superabsorbent layer.

[0068] Adhering the first intermediate layer of the wound dressing to the bottom layer while providing a non-adhesive connection between the intermediate layer and the backing layer allows for lateral movement and relative differential expansion and / or contraction between the intermediate and backing layers. Providing this freedom of movement reduces or prevents the possibility of mechanical deformation, such as interlaminar stresses and wrinkling with the backing layer, that may occur during manufacturing (e.g., during EtO sterilization, particularly if the backing layer is a PU film and / or the adjacent intermediate layer is a superabsorbent layer) or during use of the dressing.

[0069] In some embodiments, the top first intermediate layer may be provided in direct adhesive contact with the backing layer, which may be advantageous, for example, when the first intermediate layer is a foam material.

[0070] The wound dressing may further comprise a wound site adhesive layer disposed on a peripheral region of the backing layer for adhering the backing layer to the wound site.

[0071] In some embodiments, the wound dressing may include a wound contact layer, a backing layer, and a number of intermediate layers positioned between the backing layer and the wound contact layer. The intermediate layers may include a superabsorbent layer and, optionally, a foam material layer. The multiple intermediate layers may be adhered to one another, for example, as a laminate. The laminated intermediate layers may be adhered to one another. The adhesive may include a spread coat adhesive.

[0072] The inclusion of a foam layer may improve the absorbency of the dressing and subsequent diffusion of fluid, leading to an improved MTVR.

[0073] In some embodiments, the wound dressing may include a backing layer, a wound contact layer having a first surface for direct contact with the wound bed and a second surface facing the backing layer. The wound contact layer may include gel-forming fibers. The wound dressing may further include a superabsorbent layer. The superabsorbent layer may be disposed between the backing layer and the second surface of the wound contact layer.

[0074] The inclusion of a superabsorbent layer in the gelling wound contact layer can enhance the liquid absorption, retention, retention and liquid handling capabilities of the wound dressing, particularly by including a gelling wound contact layer that maintains a moist wound healing environment and allows the superabsorbent layer to extract more liquid than conventional dressings that have a superabsorbent layer.

[0075] In some embodiments, the wound dressing may include a backing layer, a wound contact layer having a first surface for direct contact with the wound bed and a second surface facing the backing layer, and a perforated wound site adhesive layer for adhering the wound dressing to the wound site.

[0076] Perforations improve the adhesion of the wound dressing, improve absorbency and increase the versatility of the dressing.

[0077] The adhesive layer includes a border region surrounding the wound contact layer and can optionally extend throughout the entire dressing. The perforations may be 1.6 mm or more and 2.7 mm or less in diameter. Perforations of this size are much larger than those generally known in the art and may provide unexpected advantages in balancing the adhesiveness and absorbency of the dressing. In general, increasing the percentage of the overall open area provided by the perforations increases the rate of absorption and decreases the adhesive strength.

[0078] Applicants have found that perforations of about 2.2 mm provide an exemplary perforation size that balances absorption rate and adhesion, with perforation sizes less than 2.2 mm increasing the effects of surface tension and larger perforation sizes further decreasing adhesion with little or no increase in absorption rate.

[0079] Additionally, uniform distribution of perforations throughout the dressing may simplify the manufacturing process of the dressing. Thus, the size of the perforations may include a compromise between the performance requirements of the boundary regions of the dressing, where breathability is the primary concern, and the wound contact area, where the interface between the dressing and the wound bed is most critical. FIG. 1 illustrates an exploded view of a wound dressing 10 according to an embodiment of the present invention. As illustrated, the wound dressing 10 may be comprised of, in order, a backing layer 12, a superabsorbent layer 14, a foam material layer 16, a wound contact layer 18, and a wound site adhesive layer 20. In some embodiments, the order of the various layers may be reversed, for example, the foam material layer 16 and the superabsorbent layer 14 may be reversed to provide a wound dressing including, in order from top to bottom, the backing layer 12, the foam material layer 16, the superabsorbent layer 14, the wound contact layer 18, and the wound site adhesive layer 20. Additionally, although the present disclosure is primarily directed to wound dressings including a foam material layer, it is believed that some of the teachings disclosed herein apply equally to embodiments in which the foam material layer 16 is omitted. As shown, the superabsorbent layer 14 has a contour and the wound contact layer 18 may have a corresponding contour that matches the contour of the superabsorbent layer 14. The foam layer 16 may match the contour of the superabsorbent layer 14 and may have a foam layer contour that matches the contour of the superabsorbent layer 14. Additionally, the wound contact layer 18 may not be windowed. In other words, the wound contact layer 18 may not be windowed.

[0080] Figure 2 shows an alternative arrangement in which a wound dressing 210 is comprised of a backing layer 12, a superabsorbent layer 14, a foam layer 16, a wound contact layer 18, and a wound site adhesive layer 220. As with Figure 1, the order of the various layers shown in Figure 2 may be swapped in some embodiments, and the foam layer 16 may be omitted.

[0081] Figure 4 shows an alternative wound dressing 410 that does not have a wound site adhesive layer, where the different layers share a common footprint and are typically used with additional dressings such as compression dressings or tapes to be placed in place. Also shown in Figure 4 are intralayer adhesives 24, 26 that can be used in any of the dressings disclosed herein to adhere adjacent layers together.

[0082] As can be seen, the difference between the wound dressings shown in Figures 1 and 2 relates to the wound site adhesive layers 22, 220. In the embodiment of Figure 1, the wound dressing 10 is provided with a wound site peripheral boundary adhesive layer 22, whereas in Figure 2, it includes a continuous wound site adhesive layer 220 that extends the entire length of the dressing and underlies the wound contact layer 18. The backing layer 12, superabsorbent layer 14, foam material layer 16, and wound contact layer 18 may be similar in both the embodiments of Figures 1 and 2. Thus, the description of each layer provided herein may be applicable to either or both of the wound dressings 10 and 210. It will also be understood that, as discussed above, the positions of the foam material layer 16 and the superabsorbent layer 14 may be interchanged within each dressing.

[0083] The wound site adhesive layer 20, 220 shown in Figures 1 and 2 extends radially inwards from the outermost edge 12a of the backing layer 12 and thus the wound dressing 10 towards the central region and the wound contact layer 18. The outermost regions of the wound site adhesive layers 20, 220 provided in the border region contact the backing layer 12 and allow the backing layer 12 to be directly adhered to the patient around the wound site. The backing layer 12 is thus adhered adjacent to the wound site and sealed, forming a shell onto which other wound dressing layers are applied.

[0084] The wound site adhesive layer 20 of FIG. 1 comprises a radially outer edge 20a coinciding with the peripheral edge 12a of the backing layer 12 and extends inwardly to terminate at an inner edge 20b that defines a central region of the dressing. Moreover, the inner edge 20b may be located radially inwardly of the corresponding outer edge 18a of the wound contact layer 18 such that the two layers overlap when viewed in plan. Thus, the wound contact layer 18 may include an edge portion that contacts and adheres to the wound site adhesive layer 20 provided by the adhesive edge. The overlap is provided to ensure that the wound contact layer 18 is positioned against the backing layer 12 and the wound bed, such that the wound contact layer 18 remains in position after the wound dressing 10 is applied to the wound site. In contrast, the wound site adhesive layer 220 of FIG. 2 does not include a radially inner edge and extends over the entire extent of the wound contact layer 18. However, the central and border regions may be configured with different perforation size patterns, as described further below.

[0085] The choice between providing a border-only wound site adhesive layer 20 or a full wound site adhesive layer 220 is application dependent and depends on the exudate level of the wound in which the dressing is to be placed. Thus, for dressings to be used with low to moderate exudate levels, a full wound site adhesive layer 220 is selected, and for dressings to be used with high exudate levels, a border-only wound site adhesive layer 20 is selected to maximize exudate absorption.

[0086] In wounds with high exudate levels, perforations allow fluid to migrate to the superabsorbent layer 14, while the use of silicone adhesive layer 220 can prevent wound adhesion in areas with low exudate levels (it will be appreciated that wounds can have a variety of etiologies). The dressings disclosed herein may be particularly useful where prevention of pressure sores and / or peri-wound skin protection is required.

[0087] In some dressings, the wound contact layer may be pre-hydrated with saline to provide moisture to the wound and support autolytic debridement.

[0088] The wound site adhesive layer 20 may be any suitable pressure sensitive adhesive known in the art, such as hydrocolloid, polyurethane, rubber adhesive, acrylic adhesive, or silicone adhesive. Acrylic adhesives are known to provide moderate adhesion to human skin, but are not typically repositionable. Silicone adhesives also adhere well to human skin, but are hydrophobic and therefore may provide a barrier to exudates and limit the Moisture Transmission Vapor Rate (MTVR). Thus, the use of perforations 22 with silicone adhesives may be particularly advantageous. The silicone adhesive may be any suitable silicone adhesive, such as Dow Corning 9900, Dow Corning 9800, Dow Corning 1020, or Wacker 2117, Wacker SilPUran 2114, etc. The basis weight of the adhesive layer may range from 70 gsm or more to 200 gsm or less. For example, the basis weight may be 70 gsm, 80 gsm, 100 gsm, 130 gsm, 150 gsm, or 200 gsm. The thickness of the adhesive may range from 20 microns to 40 microns. For example, the thickness may be 20 microns, 25 microns, 30 microns, or 40 microns. In a preferred embodiment, the adhesive layer may have a coat thickness of about 25 microns and a coat weight of 100 gsm.

[0089] The wound site adhesive layers 20 and 220 of Figures 1 and 2 may be provided with perforations 22. The perforations 22 may be provided to improve the performance of the dressing 10, 210. The improved performance may relate to the rate of exudate absorption, the duration of adhesion of the dressing, i.e., wear time, and the versatility of the dressing 10, 210, i.e., the range of exudate levels over which the dressing can be used.

[0090] More specifically, the wear time of the wound dressing may be extended by increasing the transepidermal water loss (TEWL) at the boundary region where the accumulation of moisture, e.g., sweat, is greater and may cause the dressing to fail. Perforations on the wound contact layer allow the exudate to be absorbed through the perforations and then transferred to the outer layer, increasing the moisture vapor transmission rate (MVTR) of the adhesive layer 20, 220.

[0091] As mentioned above, in the embodiment of Figure 2, the perforations 22 extend the entire length of the wound contact layer 18 such that the wound contact layer 18 is exposed to the wound through the perforations 22. Providing perforations 22 throughout the wound contact layer helps to control the flow of exudate from the wound into the wound contact layer 18 and superabsorbent layer 14 (if present).

[0092] For example, a low or reduced rate of exudate may cause the wound to become dehydrated and the wound contact layer 18 to adhere to the wound. Thus, the use of perforations 22 under the wound contact layer 18 may reduce the contact area with the wound. This, combined with a suitable wound contact layer 18 and superabsorbent layer 14, may allow for greater amounts of exudate to be extracted over a longer period of time. This issue may be mitigated by using a hydrophobic wound contact adhesive, such as silicone.

[0093] Furthermore, by selecting the appropriate size of the perforations 22, it is possible to ensure that the wound dressing 10, 210 is effective over a wide range of exudate levels, allowing a single dressing to be used on a wider range of wounds.

[0094] As mentioned above, the selection of the size of the perforations can be complicated due to multiple requirements for the perforations. When providing perforations 22 between the backing layer 12 and the skin, a balance must be struck between breathability and adhesion to allow for a long wear time. When providing perforations 22 between the wound contact layer 18 and the wound bed, a balance must be struck between the fluid handling properties of the perforations 22 and maintaining the health of the wound site by preventing the wound contact layer from adhering to the wound bed. To address this design conflict, some wound dressings can meet the various requirements by providing different perforations in different areas of the wound dressing. However, providing different perforations in different areas makes the manufacturing process of the wound site adhesive layer more complicated.

[0095] Applicant has discovered that by controlling the perforation size between 1.6 mm and 2.7 mm, which is significantly larger than the perforations disclosed in US10231874, briefly discussed in the Background section, a good balance between dressing wear time and exudate absorption control can be obtained. More specifically, as noted above, Applicant has discovered that a more preferred range of perforations is between 2.1 mm and 2.3 mm, with 2.2 mm being the most preferred. It will be understood that the sizes of perforations 22 provided herein are nominal values ​​and may be subject to normal manufacturing tolerances.

[0096] The perforations 22 are typically perforations or openings that extend through the thickness of the wound site adhesive layer 20, 220 such that adjacent overlying layers, such as the backing layer 12 and / or wound contact layer 18, can be exposed through the perforations 22 while still being adhered to the wound site via the adhesive layer 20, 220.

[0097] The perforations 22 can be of any suitable shape and can be provided in any suitable pattern or distribution. In some embodiments, the shape of the perforations 22 can be round, such as circular or elliptical. Providing round perforations can be advantageous for manufacturing purposes, as round holes tend to produce less residual cut-out deposits (sometimes referred to as slugs) than shapes with sharp apexes or corners in the cut-out, particularly when punched. However, it will be appreciated that the size and shape of the perforations 22 can vary from one another.

[0098] The distribution of the perforations 22 may be area specific or continuous across the extent of the wound adhesive layer 20. The distribution, and any size and any shape, may be uniform across a specific area of ​​the wound dressing. For example, the perforations 22 may be equally spaced with a first distance between adjacent perforations 22 at the border area and equally spaced a second distance across the wound contact layer 18. In other embodiments, the perforations 22 may be uniformly distributed across the entire wound site adhesive layer 18.

[0099] FIG. 3 shows a schematic diagram of a wound site adhesive layer 320 including a uniform distribution of perforations 22. The perforations 22 are arranged along intersecting lines L1-L4 that form a diamond lattice across the extent of the adhesive layer 320 in plan view. Each cell LC of the diamond lattice (only one of which is highlighted) includes a perforation 22 at each vertex and has a long axis and a short axis, the long axis being longer than the short axis. In the embodiment shown in FIG. 3, the long axis extends horizontally and the short axis extends vertically, however this is not critical and does not indicate any orientation related to how the wound dressing 10, 210 is applied. The perforated adhesive layer 320 shown in FIG. 3 includes a curved periphery, but is not limited thereto, and the wound dressing 10, 210 and wound site adhesive layer 22 may be of any shape.

[0100] To achieve a grid-like arrangement of the perforations 22, the perforations 22 may be arranged in a number of equally spaced rows Ri and a number of equally spaced columns Cj, where i and j are integers. Each of the rows Ri and columns Cj is made up of a linear array of equally spaced perforations 22. Adjacent columns Cj are axially offset from each other (with respect to the longitudinal axis of the columns) such that the odd-numbered columns of perforations 22 form a first column R1 and the even-numbered columns of perforations 22 form a second column R2 that is offset along another line from the first column R1. The spacing between the perforations 22 in a column Cj may be smaller than the spacing between the perforations in a row Ri.

[0101] The center-to-center spacing of the columns, Cj, may be greater than the center-to-row spacing, Ri. The column spacing, Cj, may be greater than or equal to 3.9 mm and less than or equal to 8.1 mm, and the row spacing, Ri, may be greater than or equal to 2.5 mm and less than or equal to 5.1 mm. Considered as a diamond lattice as described above, the lines of the lattice may be inclined with respect to the horizontal, as indicated by α.

[0102] The wound site adhesive layer 20, 220 may be provided as a separate layer that is laminated to the wound dressing during the manufacturing process. Manufacturing of the perforations 22 may be accomplished using any suitable known technique. One conventional technique involves drilling holes in the adhesive sheet prior to lamination to the wound dressing 10, 210. Another technique involves laser cutting of the perforations.

[0103] As mentioned above, in some embodiments, the wound dressing 10, 210 may have a uniform distribution of similarly sized perforations in the wound contact layer 18 area, and may include different sized perforations or no perforations at all in the peripheral areas of the dressing 10, 210. Similarly, the peripheral areas may have a uniform distribution of perforations if the central wound contact layer area is free of adhesive.

[0104] However, the manufacture of a wound site adhesive layer 20 having a non-uniform or locally specific distribution, size, shape, requires a more complicated manufacturing process. The manufacture of the adhesive layer 320 may be easier and less expensive if a common size and distribution of perforations 22 is provided, and the adhesive layer can be provided in a larger sheet or roll that can then be laminated with other layers in the dressing 10, 210. However, a uniform distribution of perforations 22 in terms of size, shape, and / or layout may adversely affect the above-mentioned performance requirements of controlling exudate absorption rate and wear time.

[0105] Returning to Figures 1 and 2, as discussed above, the coat weight of the wound site adhesive layer 20, 220 may be from 70 gsm to 200 gsm. For example, the basis weight may be 70 gsm, 80 gsm, 100 gsm, 125 gsm, 130 gsm, 150 gsm, or 200 gsm. Generally, in the prior art, there is a trend between adhesive coat weight and adhesive strength, but applicants have found that different adhesive formulations have different plateaus where increased coat weight achieves improved adhesion. Furthermore, as the adhesive coat weight increases, the thickness increases, making it more likely that the adhesive edge of the wound dressing will mechanically deform, i.e., fold or roll up. Applicants have found that a coat weight closer to the lower end of the range, e.g., 70 gsm, e.g., 70 gsm to 100 gsm, provides a suitable balance between adhesive performance and thickness, and reduces mechanical stresses within the wound dressing.

[0106] Although not shown in the drawings, the wound dressing may also include a release layer which covers and maintains the sterility of the wound site adhesive layer 20 prior to use and during application to the wound site, as is well known in the art.

[0107] As previously described in connection with FIG. 1, the boundary region of the wound site adhesive layer overlaps the wound contact layer 18, so that the wound contact layer 18 is held in a fixed relationship to the backing layer 12 via the adhesive layer. The overlap may include a width defined as the distance between the outer edge 18a of the wound contact layer 18 and the inner edge 16a of the wound site adhesive layer 20. In some embodiments, the extent of the overlap is generally similar around the periphery of the wound contact layer 18, and the width of the overlap is constant. In other embodiments, the width of the overlap may vary along the periphery. In some embodiments, the dressing is a polygon, such as a rectangle / rectangle / square, when viewed in plan, and the overlap may include one or more corner regions. The corner regions may be defined in part by a radius of curvature. As shown in FIG. 5, in some embodiments, the radius of curvature of the adhesive layer may be larger than the radius of curvature of the wound contact layer, resulting in a larger overlap at the corner regions.

[0108] 5 shows a dressing 500 having a backing layer 512, a wound contact layer 518, and an adhesive layer 520. The backing layer 512 is defined by a peripheral edge 512' and extends across the entire width of the dressing. The adhesive layer 520 extends from the peripheral edge 512' of the backing layer to an inner edge 520', providing a central area where the wound contact layer 518 is exposed. The wound contact layer 518 includes an outer edge 518'.

[0109] The dressing is generally square in plan view, with the edge 518' of the wound contact layer having a first radius R1 that is smaller than the radius R2 of the inner edge of the adhesive layer. The relative difference between the corner radii R1 and R2 allows for an increased contact area between the wound contact layer 518 and the adhesive layer 520 compared to a dressing having the same radius of curvature. Increasing the overlap at the corner regions allows for increased adhesion between the wound contact layer 18 and the adhesive layer 20 without significantly adversely affecting the absorbency of the dressing.

[0110] In the embodiment shown in FIG. 5, the dressing 510 may include a backing layer that is 85 mm by 85 mm (+ / - 5 mm) in plan view. The edge 20' of the adhesive layer has a radius of curvature of 10 mm to 15 mm, preferably about 12.5 mm. The edge 518' of the wound contact layer has a radius of curvature of 7.5 mm to 12.5 mm, preferably about 10 mm, but in any case less than the radius of curvature of the edge 520' of the adhesive layer. The width of the overlap away from the corner regions may be constant. In the embodiment shown in FIG. 5, the overlap width W is 10 mm to 20 mm, preferably about 15 mm. The width of the wound contact layer exposing the opening in the adhesive layer may be 30 mm to 40 mm. The width of the wound contact layer may be 45 mm to 50 mm.

[0111] By increasing the curvature of the corners at the inner edge of the adhesive layer, an increase of about 3 to 6% can be expected compared to a coating with a constant radius of curvature.

[0112] While the above dimensions relate to a particular embodiment, it will be understood that the ratios of the various measurements are applicable to other coverings. Additionally, while the covering is shown as having substantially straight sides, the sides may be generally curved, with distinct corner regions.

[0113] As mentioned above, some embodiments may include a superabsorbent layer 14 as shown in Figures 1 and 2. The wound contact layer 18 may include a first surface that directly contacts the wound bed and a second surface that faces the backing layer 12. As shown in Figures 1 and 2, the superabsorbent layer 14 may be disposed between the backing layer 12 and the second surface of the wound contact layer 18.

[0114] The wound contact layer 18 may include gel-forming fibers. As mentioned in the Background section, dressings containing gelling absorbents are known in the art and manage exudate by absorbing the exudate and retaining it within the dressing. Moisture in the gelling absorbent may be lost by vapor transmission from the dressing, but because the exudate is retained within the gelling absorbent, it is less likely to be lost than with foam absorbents. The absorbent acts as a reservoir for exudate and therefore must have sufficient capacity to retain the exudate while the dressing is worn. This affects the amount of absorbent required in the wound dressing, which of course affects the overall thickness and conformability of the wound dressing. Furthermore, for gelling absorbents in general, and fibrous gelling absorbents in particular, the relationship between absorbency and the thickness or weight per unit area of ​​the gelling absorbent layer is not linear. This means that a trade-off must be made between absorbency, conformability, and water vapor permeability with conventional gelling absorbents.

[0115] The applicant's patent EP2498829 provides an absorbent component for a wound dressing, the wound contact layer being made of gel-forming fibres bonded to a foam layer, which combines a wound contact layer that absorbs exudate by gelling and inhibits the lateral spread of the exudate with a foam layer that absorbs exudate but releases it easily by water vapour transmission. The presence of the gel-forming wound contact layer was thought at the priority date of EP2498829 to limit the lateral spread of exudate within the foam, increase exudate retention compared to the use of the foam alone and improve the water vapour transmission properties of the wound contact layer.

[0116] The present invention is a development of the concept described in EP2498829, where instead of a foam layer absorbing exudate and releasing it by water vapor transmission, a superabsorbent layer is provided in combination with the foam layer. The applicant has discovered that using a superabsorbent material to absorb and retain exudate instead of using a foam layer to absorb exudate and release it by water vapor transmission can improve the exudate removal rate and wear time of the wound dressing while limiting the lateral diffusion of exudate. Thus, the present invention provides a dressing that increases fluid handling and retention while preventing lateral diffusion. Thus, the use of a superabsorbent layer in combination with a gelling absorbent allows more liquid to be trapped without relying on water vapor release from the dressing. This generally leads to an improvement in dressings, but can be particularly advantageous when the dressing is covered, for example when a compression dressing is used in combination with the dressing, reducing the MVTR.

[0117] Superabsorbent polymers are known in the art for their liquid absorption and retention properties and are utilized in a variety of industries. Superabsorbent layers are generally available in two forms: superabsorbent (e.g., polyacrylate) fibers (SAF) and superabsorbent (e.g., polyacrylate) polymers (SAP). The wound dressings of the present disclosure may be provided with a superabsorbent layer comprising either or both SAF and SAP, but in a preferred embodiment, the superabsorbent layer comprises only SAF. Providing a superabsorbent layer of only SAF allows for the wound dressing to be cut prior to use, which is not possible with SAP or SAF / SAP blends due to the particulate nature of SAP. Additionally, the use of a superabsorbent layer of only SAF has been found to improve compatibility, especially when used in laminate dressings where an intralayer adhesive is used as described below.

[0118] The use of SAF also improves fluid retention performance compared to dressings without SAP or superabsorbent layers. Table 1 below shows comparative data for a conventional gelling absorbent / foam dressing combination (Sample 1) and a prototype dressing that combines a gelling wound contact layer with: i) an unrestricted SAP layer (Sample 2) that allows the wound contact layer and superabsorbent to move freely relative to each other, ii) a laminated gelling wound contact layer and SAP layer, and iii) a laminated gelling wound contact layer and an SAF layer.

[0119] [Table 1]

[0120] Table 1 shows the liquid retention properties of dressings without a superabsorbent layer and dressings with various SAP and SAF layers.

[0121] As can be seen from Table 1, the use of laminated SAF results in greater absorbency per unit area and improved liquid retention compared to laminated SAP products.

[0122] In preferred embodiments, the superabsorbent layer may be comprised of a mixture of sodium polyacrylate and polyester fibers. The ratio of superabsorbent fibers to polyester fibers may range from 40:60 to 55:45. In some preferred embodiments, the superabsorbent layer may be comprised of a 40:60 ratio. The reduced amount of superabsorbent fibers prevents distortion of the layer dressing during subsequent manufacturing steps, particularly sterilization of the dressing, and has limited effect on the dressing's conformance and liquid handling capabilities.

[0123] The superabsorbent layer is comprised of nonwoven fibers and has a thickness of at least 1.5 mm and no more than 2.5 mm. In some preferred embodiments, the thickness may optionally be 2 mm. The thickness of the superabsorbent layer is determined by a balance of patient comfort, compatibility, and fluid handling performance.

[0124] [Foam material layer] As mentioned above, in addition to the superabsorbent layer 14 and the wound contact layer 18, the wound dressing 10, 210 may include a foam layer 16. The foam layer 16 may be provided to improve the comfort and tacticity of the wound dressing. As mentioned above, the foam layer 16 may be provided between the wound contact layer 18 and the superabsorbent layer 14, or between the superabsorbent layer 14 and the backing layer 12.

[0125] The foam layer 16 is preferably a hydrophilic foam such as polyurethane, more preferably a hydrophilic open cell foam available from Freudenberg or Filtrona, particularly Filtrona 30W. The foam typically has a thickness of from 0.25 to 5 mm, preferably from 1 to 4.0 mm, most preferably from 1.5 to 3 mm. The foam layer preferably has an absorbency of from 10 to 20 g / g, as measured by the free swell absorbency method (BS-EN 13726-1:2002).

[0126] The thickness of the foam layer may be 1.3 mm to 3.2 mm, optionally 2.5 mm. The foam may be polyurethane, PU. In one advantageous embodiment, the thickness of the aliphatic polyurethane foam may be 1.5 mm or 3 mm. In another advantageous embodiment, the thickness of the MDI polyurethane foam may be 1.5 mm or 3 mm.

[0127] Six prototype dressings were created to demonstrate the effectiveness of the gelling wound contact layer and superabsorbent layer. Each dressing consisted of a ConvaTec® Hydrofibre® wound contact layer with a basis weight of 150 gsm and a 30 micron polyurethane backing layer. In addition to the wound contact and backing layers, each prototype contained either a 2.5 mm PU foam or a 1.5 mm MDI foam. Prototypes 1 and 2 did not contain a superabsorbent layer. Prototypes 3 and 4 contained an SAF layer immediately beneath the backing layer, with a foam layer and wound contact layer, respectively. Prototypes 5 and 6 contained a foam layer immediately beneath the backing layer, with a wound contact layer, respectively. Thus, the order of the foam layer and SAF layer was swapped between prototypes 3 and 4, and between 5 and 6. Five samples were tested for each prototype.

[0128] Table 2 shows the fluid absorbed and retained (retention) by the prototype wound dressings. The last two columns indicate the foam material used (X indicates the use of a foam material).

[0129] [Table 2]

[0130] Table 2 shows a comparison of the absorbency and retention of dressings without and with an SAF layer.

[0131] As can be seen from the data in Table 2, all dressings show high retention, with the presence of a superabsorbent layer improving absorbency. The placement of the foam has only a limited effect on retention; the thicker 2.5mm PU foam improves absorbency, and the MDI foam improves retention. Further increasing the thickness of the foam layer (e.g., up to 3mm) can further increase absorbency. However, it has been found that retention decreases with increasing foam thickness, and generally the 2.5mm PU foam has lower retention than the thinner 1.5mm MDI foam.

[0132] As mentioned above, the wound contact layer is fibrous and includes gel-forming fibers. A fibrous layer, in contrast to a polymeric layer, has the advantage that it is particularly capable of forming a gel block that resists the lateral diffusion of exudate. Furthermore, exudate is rapidly absorbed and retained under pressure.

[0133] Fibers suitable for use in the wound contact layer of the present invention include hydrophilic fibers, which become wet, slippery, and gelatinous upon absorption of wound exudate, reducing the tendency of surrounding fibers to adhere to the wound. The fibers may be of a type that retains structural integrity upon absorption of exudate, or may be of a type that loses its fibrous shape upon absorption of exudate, becoming a structureless gel or solution.

[0134] The fibres are preferably chemically modified cellulose fibres, in particular spun sodium carboxymethylcellulose fibres or cellulose ethylsulfonate fibres. The carboxymethylcellulose fibres are preferably as described in PCT WO / 9312275 or GB93 / 01258. The fibres may be pectin fibres, alginate fibres, in particular those described in WO94 / 17227 or EP433354 or EP476756, or composite fibres of alginate and polysaccharides such as those described in EP0892863, chitosan fibres, hyaluronic acid fibres or fibres derived from other polysaccharide fibres or gums. The cellulose fibres preferably have a degree of substitution of at least 0.05 carboxymethyl groups per cellulose unit. Preferably, the gel-forming fibres used in the present invention have a water or saline absorbency of at least 15 g / g, more preferably at least 25 g / g or 50 g / g, as measured by the free swell absorption method. The degree of substitution of the carboxymethylated cellulose gel-forming fibers is preferably at least 0.2 carboxymethyl groups per cellulose unit, more specifically, from 0.3 to 0.5.

[0135] The gel-forming fibers are preferably mixed to form a wound contact layer that includes fibers of different absorbency or characteristics. The wound contact layer may include other fibers, such as natural or synthetic textile fibers, but preferably cellulosic fibers, such as viscose rayon, multilimbed viscose, cotton or regenerated cellulose, which are more absorbent than most textile fibers. The water absorption of the fibers is usually less than 1 g / g, as measured by the free swell absorbency test. The wound contact layer can be made from a nonwoven fibrous web that is either needle punched, spun laced, wet laid, dry laid, melt blown, or felted. The web is then stitch bonded with reinforcing fibers or yarns to give the layer additional strength and to ensure that the structure is maintained even when saturated with exudate. Furthermore, the stitch bonded structure may give the dressing high absorbency or some extensibility, depending on the nature of the reinforcing fibers and yarns used and the stitch bond pattern. The thickness of the wound contact layer is preferably between 20 microns and 5 mm, more preferably between 2 mm and 3 mm, and even more preferably between 1 mm and 2 mm, in some embodiments the thickness may be, for example, 1 mm or 1.5 mm.

[0136] The basis weight of the wound contact layer can affect the liquid handling capabilities of the wound dressing, with increased basis weight typically favorably increasing absorbency. Surprisingly, applicants have discovered that reducing the basis weight of dressings that include a superabsorbent layer, particularly a SAF superabsorbent layer, has minimal impact on liquid absorbency and liquid retention. To demonstrate this, four prototype wound dressings were tested to determine the level of basis weight to use for the superabsorbent layer. As shown in Table 4, the four prototypes include a first wound dressing that includes a 100 gsm wound contact layer without a superabsorbent layer, a second wound dressing that includes a 70 gsm wound contact layer, a 2.5 mm polyurethane foam material, and a 2 mm SAF superabsorbent layer, a third wound dressing that includes a 100 gsm SAF wound contact layer, a 2.5 mm polyurethane foam material, and a 2 mm SAF superabsorbent layer, and a fourth wound dressing that includes a 70 gsm wound contact layer, a 2.5 mm polyurethane foam material, and a 2 mm SAF superabsorbent layer. The wound contact layer was Hydrofiber® from ConvaTec. The first sample was a conventional Aquacel® foam product that contained a 100 gsm Hydrofiber® layer bonded to a PU foam. Table 4 below summarizes the results of the liquid absorption and retention tests for n=5.

[0137] [Table 4]

[0138] Table 4 - Fluid absorbency and retention of wound dressings without a superabsorbent layer and wound dressings with SAF superabsorbent layers with different wound contact base layers.

[0139] As can be seen, when a SAF superabsorbent layer is used in combination with a foam material, increasing the basis weight has minimal impact on the absorbency and retention of the wound dressing. However, lowering the basis weight reduces interlaminar stresses and associated deformation of the wound dressing, allowing the use of a 70gsm wound contact layer in some preferred embodiments. Additionally, lower basis weights can result in thinner dressings. 70gsm may be a reasonable minimum for manufacturing purposes, as lighter weights lack strength.

[0140] As described above in connection with Figures 1 and 2, the dressing may include a backing layer provided with a wound contact layer and a superabsorbent layer. The backing layer is breathable and allows water vapor to escape from the dressing while preventing the ingress of contaminants to the wound site. The backing layer may be any suitable material and in some embodiments may include a polyurethane material, as known in the art. The backing layer may be constructed of blown or solvent cast polyurethane, the latter of which may reduce deformation and delamination during use. In some preferred embodiments, the backing layer may be Convestro 9147 or Transcontinental Coatings Inspire 2301 supplied by Covestro AG. The thickness of the backing layer is between 25 microns and 35 microns, preferably 30 microns. Preferably, the MVTR (liquid contact) of the film layer is at least 10,000 / m2 / 24 hours.

[0141] In some embodiments, the backing layer may be adhesive or may include an adhesive film to provide adhesion to the wound site. The adhesive may extend over the entire area of ​​the backing layer, so that the backing layer adheres to the boundary of the dressing around the wound site and also to the top layer of the dressing stack, such as the superabsorbent layer. However, as described below, in some embodiments, the backing layer is only adhered to the skin, and is free of adhesive in the central area where the top layer of the dressing sits and contacts. It will be appreciated that the wound site adhesive may be applied directly to the backing layer or may be a separate sheet laminated to the backing layer.

[0142] The adhesive or adhesive film may comprise an acrylic adhesive as known in the art. The acrylic adhesive may have a viscosity of 5 g / m 2 More than 20g / m 2 and may include a hexagonal pattern. The adhesive pattern may be selected to promote openness and breathability while still providing sufficient surface area for adhesion to contacting materials. It will be appreciated that the adhesive lines define hexagonal gaps so as not to create completely open channels within the layer.

[0143] As described below, the wound dressing may include a laminated structure in which the various layers are bonded together to prevent movement during use and prior to application. Bonding the various layers together may be accomplished using any suitable technique, such as polymer-based melt lamination, adhesives, flame lamination, direct lamination by foam casting, or ultrasonics. Additionally or alternatively, intralayer adhesives 24, 26 may be used to bond the various layers together, as shown in FIG. 4.

[0144] The intralayer adhesive (sometimes called a binder) may be, for example, a continuous layer, a perforated layer, a liquid, or a spread-coat adhesive. The binder may be a web containing a continuous or interrupted layer of adhesive that is inserted between each adjacent layer and activated to bond the layers. The binder may be heat activated, for example, by the application of heat and pressure during the lamination process. The film may be composed of a web of adhesive strands or dots.

[0145] Scattering coat adhesives are known in the art and relate to a method of providing a layer or adhesive by dusting a surface with a powdered adhesive prior to lamination of the layers. The scattering coat adhesive can be used for some or all of the intralayer adhesive. For example, a scattering coat adhesive can be used to adhere a superabsorbent layer to a foam material, and an alternative adhesive technology can be used to adhere the foam material to a wound contact layer.

[0146] In some embodiments, some of the adjacent layers may not include an intralayer adhesive. For example, as shown in Figures 1 and 2, the top layer of the stack, e.g., the superabsorbent layer, may not be adhered to the backing layer so that the backing layer and the top layer can move freely relative to each other. Thus, one or more of the internal layers of the wound dressing may be provided with an area free of adhesive between the second surface of the superabsorbent layer and the backing layer. In this case, the wound dressing includes an internal stack of layers including a wound contact layer, a foam material layer, and a superabsorbent layer, etc., which are attached to the backing layer via the wound contact layer. As mentioned above, the wound contact layer may be attached to the backing layer via a wound site contact layer.

[0147] In this manner, the inner stack is configured to be movable relative to the backing layer during manufacture and use. In particular, the separation between the inner stack, or at least its top layer and the backing layer, allows the respective layers to contract or expand relative to one another during manufacture of the dressing. This allows alternative and advantageous operations to be performed during manufacture of the dressing.

[0148] Such manufacturing steps may include sterilization of the dressing. In some embodiments, the wound dressings described herein may be sterilized using ethylene oxide technology. However, the use of ethylene oxide sterilization may result in relative movement of one or more layers of the inner stack, which, if adhered to the backing layer, may cause the backing layer to deform (e.g., wrinkle or warp), resulting in an unsightly appearance. Therefore, it may be advantageous to provide a relative separation between the layers.

[0149] The above-described embodiment or embodiments have been given by way of example only: many variations are possible without departing from the scope of protection afforded by the appended claims.

Claims

1. wound contact layer, Lining layer, an intermediate layer disposed between the backing layer and the wound contact layer, the intermediate layer having a first surface facing the wound contact layer and a second surface facing the backing layer, the first surface of the intermediate layer being directly or indirectly adhered to the wound contact layer and the second surface being not adhered to the backing layer; and a wound site adhesive layer disposed on a peripheral region of the backing layer for adhering the backing layer to a wound site; A wound dressing comprising:

2. The intermediate layer is directly or indirectly adhered to the wound contact layer.

2. The wound dressing of claim 1.

3. Further comprising an adhesive for ensuring adhesion between the intermediate layer and the wound contact layer, the adhesive comprising a binder layer; 3. The wound dressing of claim 2.

4. The intermediate layer is a superabsorbent layer. The wound dressing according to any one of claims 1 to 3.

5. The superabsorbent layer comprises polyacrylate fibers.

5. The wound dressing of claim 4.

6. the superabsorbent layer has a contour and the wound contact layer has a corresponding contour that matches the contour of the superabsorbent layer; 6. A wound dressing according to claim 4 or 5.

7. further comprising a foam layer disposed between the wound contact layer and the backing layer. A wound dressing according to any one of claims 1 to 6.

8. the foam material has a foam layer profile that corresponds to and matches the profile of said superabsorbent layer; A wound dressing according to claim 7 when dependent on claim 6.

9. the foam layer is disposed between the wound contact layer and the first surface of the superabsorbent layer; 9. A wound dressing according to claim 7 or 8.

10. The foam layer is adhered to the wound contact layer.

10. The wound dressing of claim 9.

11. The wound site adhesive layer includes a border region of adhesive surrounding a central region in which the wound contact layer is located. A wound dressing according to any one of claims 1 to 10.

12. The border region partially covers the wound contact layer.

12. The wound dressing of claim 11.

13. the adhesive layer has an inner edge defining a central window through which the wound contact layer is exposed; the wound contact layer has an outer edge and overlaps the adhesive layer around the periphery of the wound contact layer so as to be adhered thereto; the width of the overlap between the inner edge of the adhesive layer and the outer edge of the wound contact layer varies along the periphery of the wound contact layer; A wound dressing according to any one of claims 1 to 12.

14. the overlap includes one or more corner regions and one or more edge regions of the wound contact layer and the adhesive layer; The width of the overlap in the corner region is greater than the width of the overlap in the adjacent edge region.

14. The wound dressing of claim 13.

15. the one or more corner regions include an inner edge having a first radius of curvature and the outer edge includes a second radius of curvature, the first radius of curvature being greater than the second radius of curvature; 15. The wound dressing of claim 14.

16. The wound site adhesive layer extends continuously across the wound contact layer. A wound dressing according to any one of claims 1 to 11.

17. The wound site adhesive layer is perforated. A wound dressing according to any one of claims 1 to 16.

18. The diameter of the perforations is greater than or equal to 1.6 mm and less than or equal to 2.5 mm, and optionally the diameter is 2.2 mm.

18. The wound dressing of claim 17.

19. The wound contact layer is windowless. A wound dressing according to any one of claims 1 to 18.

20. The wound contact layer comprises gel-forming fibers. A wound dressing according to any one of claims 1 to 19.

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