Wound dressings

Abstract

Disclosed is a wound dressing comprising 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 comprising gel-forming fibers, and a superabsorbent layer, the superabsorbent layer being located between the backing layer and the second surface of the wound contact layer.

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 deal with exudate produced by the wound in a variety of ways. For example, some dressings are primarily foam-based and deal with exudate by absorbing the exudate and allowing the moisture trapped in the dressing to evaporate from the underside or top side of the dressing. Such dressings are designed to absorb exudate and wick it away by water vapor transmission, rather than absorbing and retaining it, thus maximizing the level of exudate management within the design constraints of the dressing. A disadvantage of such dressings is that the open structure of the foam allows unrestrained lateral spread of exudate across the dressing, saturating the entire surface of the dressing, which can result in maceration of healthy skin surrounding the wound.

[0003] A further disadvantage of the open foam structure is that when the dressing is placed under pressure, e.g., when pressed or when the dressing is subjected to force by the patient sitting, lying down, or turning over, exudate may be squeezed out of the porous open foam structure and come into contact with the wound and / or surrounding skin surface, resulting in maceration around the wound. In the case of chronic wounds, certain components of chronic wound exudate may further damage the wound. A further disadvantage of such dressings is the rapid loss of exudate by evaporation, which over time dries out the wound surface and impedes healing.

[0004] Other dressings, mainly gelling absorbent-based dressings, handle exudate by absorbing it and retaining it within the dressing. Although moisture within the absorbent may be lost by vapor transmission from the dressing, this is less likely than with foam absorbents, as the exudate is retained and immobilized within the gelling absorbent. The absorbent acts as a reservoir for the exudate, so it must have sufficient capacity to retain the exudate over the duration of the dressing's wear. 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 the thickness or weight per unit area of ​​the gelling absorbent layer and absorbency is not linear. This means that a careful balance must be struck between absorbency, conformability, and water vapor permeability.

[0005] EP2498829 describes a wound dressing that discloses an absorbent component for dressing a wound. The absorbent component includes a wound contact layer that includes gel-forming fibers bonded to a foam layer. A combination of a wound contact layer that absorbs exudate by gelation and inhibits lateral spread of the exudate and a foam layer that absorbs exudate but easily releases it by water vapor transmission shows a suitable approach to enhance fluid handling. Furthermore, the absorbent wound contact layer helps to control fluid handling by limiting the lateral spread of exudate in the foam and increasing the retention of exudate compared to when using foam alone. This can improve the water vapor transmission properties of the wound contact layer.

[0006] Gelling absorbents are particularly suitable for wounds with moderate exudation, as at low exudate levels the wound defect may dehydrate and adhere to the dressing, and at high exudate levels the fluid handling capabilities of the gelling wound contact layer may be insufficient.

[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. Known adhesive contact layers may be provided as a continuous layer that extends throughout the wound dressing and includes perforations, or as an adhesive contact layer that is provided only 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 provided in US10231874. This document discloses a wound contact layer that comprises 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. This is believed to be small enough to contribute to preventing tissue ingrowth into the wound dressing while allowing wound exudate to flow into the dressing. Other dressings that include a perforated adhesive layer include the applicant's existing Aquacel® Form Pro product. The product includes a perforated wound site adhesive layer with 1.5 mm diameter perforations to enhance breathability of the dressing.

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

[0009] The present invention provides a wound dressing according to 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 comprise 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 may comprise a plurality of perforations.

[0011] The adhesive layer may include a border region surrounding the wound contact layer. The perforations may have a diameter of 1.6 mm to 2.7 mm. In some embodiments, the perforations may preferably have a diameter of 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 so as to hold the wound contact layer in fixed relationship with 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 be via the perforations.

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

[0015] The perforations may have any desired shape. The shape may be common to all perforations. For example, the perforations may be rounded, for example circular or elliptical.

[0016] The perforations are arranged in a regular array including 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 between 3.9mm and 8.1mm. The spacing between the rows may be between 2.5mm and 5.1mm.

[0017] The adhesive may include a silicone adhesive. The adhesive layer may include an adhesive having a density of 70 g to 150 g per square meter.

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

[0019] The wound contact layer may include an outer edge. The wound contact layer may overlap and be adhered to the adhesive layer around 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 overlap in 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 including 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 include a superabsorbent layer. The superabsorbent layer may be in adhesive-free contact with the backing layer.

[0023] The superabsorbent layer may comprise a first surface facing the wound contact layer and a second surface facing the backing layer. The first surface of the superabsorbent layer may comprise 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 fibres. The superabsorbent layer may be located between the backing layer and the second surface of the wound contact layer.

[0026] The superabsorbent layer may have an outer profile. The wound contact layer may have an outer profile that corresponds to the outer profile of the superabsorbent layer. In other words, the outer profiles of the superabsorbent layer and the wound contact layer may be the same and perfectly aligned.

[0027] Thus, in one embodiment, there is provided 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, the wound contact layer comprising gel-forming fibres, and a superabsorbent layer. The superabsorbent layer is located between the backing layer and the second surface of the wound contact layer. The superabsorbent layer has an outer contour. The wound contact layer has an outer contour that corresponds to and is in register with the outer contour of the superabsorbent layer.

[0028] The wound dressing may further include a foam layer positioned between the backing layer and the second surface of the wound contact layer. The foam layer may have an outer foam layer contour positioned to correspond to the outer contour of the superabsorbent layer.

[0029] Thus, in one embodiment, there is provided 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, a wound contact bed comprising gel-forming fibres; and a superabsorbent layer located between the backing layer and the second surface of the wound contact layer. The superabsorbent layer has an outer contour. The wound contact layer has an outer contour that is positioned to and corresponds to the outer contour of the superabsorbent layer. The dressing comprises a foam layer located between the backing layer and the second surface of the wound contact layer. The foam layer has an outer contour that corresponds to and is positioned to the outer contour of the superabsorbent layer.

[0030] The foam layer may be located between the wound contact layer and the superabsorbent layer.

[0031] The superabsorbent layer may comprise fibres, optionally non-woven fibres. The superabsorbent layer may comprise only non-woven fibres. The non-woven fibres may be polyacrylate fibres.

[0032] Thus, in one embodiment, there is provided 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 on the side of the backing layer, the wound contact layer comprising gel-forming fibres, and a superabsorbent layer located between the backing layer and the second surface of the wound contact layer. The superabsorbent layer comprises fibres. The superabsorbent layer comprises only non-woven fibres. The non-woven fibres are polyacrylate fibres.

[0033] The superabsorbent layer may have a thickness of from 1.5mm to 2.5mm, optionally 2mm.

[0034] Thus, in one embodiment there is provided 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, the wound contact layer comprising gel-forming fibres, and a superabsorbent layer located between the backing layer and the second surface of the wound contact layer, the superabsorbent layer having a thickness of between 1.5mm and 2.5mm, optionally 2mm.

[0035] The superabsorbent layer may include 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 adhesive, or a spread coat adhesive. The intralayer adhesive may be a web including continuous or broken layers of adhesive interposed between each adjacent layer and activated to bond the layers together. The intralayer adhesive may be heat 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.

[0036] 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, for example, sliding contact or differential expansion contact.

[0037] 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 the superabsorbent layer is not adhered to the backing layer.

[0038] The foam layer may include a first, wound-facing surface and a second, backing-facing surface. The first surface of the foam layer may include a foam first adhesive layer. The second surface of the foam layer may include a foam second adhesive layer. The foam layer and the superabsorbent layer may be adhered together.

[0039] The foam layer may comprise a polyurethane foam. The foam layer may comprise an aliphatic foam or a methylene diphenyl diisocyanate foam.

[0040] The foam layer may have a thickness of from 1.3 mm to 3.2 mm, optionally 2.5 mm.

[0041] 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 from 1mm to 1.5mm. The wound contact layer may have a basis weight of from 70gsm to 150gsm, optionally 70gsm.

[0042] The backing layer may comprise a polyurethane material. The backing layer may have a thickness of 30 microns.

[0043] The wound contact layer may be unfenestrated, in other words it may lack fenestration.

[0044] The dressing may further comprise a wound site adhesive layer for adhering the wound dressing to the wound site. The adhesive layer comprises a border region surrounding the wound contact layer. The adhesive layer may comprise perforations, the perforations having a diameter of 1.6 mm to 2.7 mm, optionally 2.2 mm.

[0045] Thus, in one embodiment there is provided 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, the wound contact layer comprising gel-forming fibres, and a superabsorbent layer located between the backing layer and the second surface of the wound contact layer. The dressing further comprises a wound site adhesive layer for adhering the wound dressing to the wound site. The adhesive layer comprises a border region surrounding the wound contact layer. The adhesive layer comprises perforations. The perforations have a diameter of 1.6mm to 2.7mm, optionally 2.2mm.

[0046] 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 comprise a first surface facing the wound contact layer and a second surface facing the backing layer.

[0047] 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.

[0048] The dressing may further include a wound site adhesive layer provided on a peripheral region of the backing layer for adhering the backing layer to the wound site.

[0049] The intermediate layer may be adhered directly or indirectly to the wound contact layer.

[0050] The wound dressing may further comprise an adhesive to adhere the intermediate layer to the wound contact layer. The adhesive may be referred to as an intralayer adhesive or a binder layer. The adhesive may comprise a spread coat adhesive.

[0051] The intermediate layer may include a superabsorbent layer.

[0052] The wound dressing may further include a foam layer located between the wound contact layer and the backing layer. The foam layer may be located between the wound contact layer and the first surface of the superabsorbent layer. The foam layer may be adhered to the wound contact layer.

[0053] 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.

[0054] Those skilled in the art will understand that, unless mutually exclusive, features described in connection with any one of the aspects, embodiments or examples 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 any other feature described herein. [Brief description of the drawings]

[0055] 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:

[0056] [Figure 1] FIG. 1 shows an exploded view of a wound dressing according to one embodiment of the present disclosure. [Diagram 2] FIG. 2 shows an exploded view of a wound dressing according to an alternative embodiment of the present disclosure. [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 a plan view showing an example of a wound dressing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0057] In the following detailed description, numerous specific details are set forth to provide a thorough understanding of various embodiments and the concepts of the present invention. However, those skilled in the art will understand that the present invention can be practiced without these specific details or with known equivalents of these specific details, that the present invention is not limited to the described embodiments, and that the present invention can be practiced in various alternative embodiments. It will also be understood that well-known methods, procedures, components, and systems may not be described in detail.

[0058] The wound dressings described herein are absorbent wound dressings having multiple layers for absorbing exudate from the wound. The wound dressings may include 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 may include their own inventive aspects that may be used independently of other layers described herein in combination. 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 having a backing layer, a superabsorbent layer, a wound contact layer, and a perforated wound site adhesive layer can be particularly advantageous, with the various components providing synergistic benefits to the performance of the dressing in terms of adhesion (e.g., wear time), absorbency, and versatility.

[0059] In addition to the layers mentioned above, the wound dressing described in accordance with the present specification and embodiments of the present disclosure may further include one or more additional layers, such as a foam layer and / or an intralaminar adhesive layer. The additional layers may be provided to enhance the performance of the dressing in terms of one or more of fluid absorbency, compatibility, retention, retention rate, and fluid handling capacity. 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 while the dressing is applied to the wound.

[0060] Wound dressings are generally described as multiple layers provided in a laminated configuration, with a wound contact layer positioned adjacent the wound during use and a backing layer provided as an outer layer defining the outer surface of the dressing. In the present disclosure, the various layers are generally arranged concentrically, although this need not be the case. In some embodiments, the layers may be asymmetrically laminated to one another.

[0061] Each layer may be 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 to the wound site and toward the wound site, and a second surface facing outwardly from the wound site and toward the backing layer.

[0062] One or more layers may be present only in certain regions. For example, a wound site adhesive layer may be present only in the peripheral or border regions of the dressing, with the central region not including a wound site adhesive layer. Additionally, some layers may be located only in the central region of the dressing, thereby being located inside the peripheral edge.

[0063] 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 attached to the wound contact layer. The second surface may be attached or unattached to the backing layer, thereby preventing or allowing lateral movement therebetween and helping to control moisture transmission through the backing layer.

[0064] The intermediate layer may include a superabsorbent layer or a foam layer. The wound dressing may include multiple intermediate layers. The first intermediate layer, which is the top layer, is in non-adhesive contact with the backing layer and indirectly adheres to the wound contact layer via the second intermediate layer. This may be advantageous, for example, when the backing layer is a superabsorbent layer.

[0065] The adhesion of the first intermediate layer to the underlying layer of the wound dressing provides a non-adhesive connection between the intermediate layer and the backing layer while allowing lateral movement and relative differential expansion and / or contraction between the intermediate layer and the backing layer. Providing such freedom of movement can reduce or prevent correlation stresses with the backing layer and the potential for mechanical deformation (e.g., wrinkling) that may occur during manufacturing (e.g., during EtO sterilization, particularly when the backing layer is a PU film and / or the adjacent intermediate layer is a superabsorbent layer) or during use of the dressing.

[0066] In some embodiments, the top first intermediate layer may be in direct adhesive contact with the backing layer, which may be advantageous, for example, when the first intermediate layer is a foam layer.

[0067] The wound dressing may further include a wound site adhesive layer provided on a peripheral region of the backing layer for adhering the backing layer to the wound site.

[0068] In some embodiments, the wound dressing may include a wound contact layer; a backing layer, and multiple intermediate layers positioned between the backing layer and the wound contact layer. The intermediate layers may include a superabsorbent layer and, optionally, a foam layer. The multiple intermediate layers may be adhered together, for example, as a laminate. The laminated intermediate layers may be adhered together. The adhesive may include a spread coat adhesive.

[0069] The inclusion of a foam layer can improve the absorbency of the dressing and may also help improve the MTVR by aiding in the subsequent diffusion of fluids.

[0070] 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 located between the backing layer and the second surface of the wound contact layer.

[0071] The provision of a superabsorbent layer in conjunction with a gelling wound contact layer may enhance the fluid absorption, retention, retention and fluid handling capabilities of the wound dressing, particularly by including a gelling wound contact layer, which maintains a moist wound healing environment and allows for greater fluid extraction by the superabsorbent layer compared to conventional dressings with a superabsorbent layer.

[0072] 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.

[0073] The perforations can improve the adhesion of the wound dressing, improve its absorbency, and increase the versatility of the dressing.

[0074] The adhesive layer may include a border region surrounding the wound contact layer and may optionally extend throughout the entire dressing. The perforations may have a diameter of 1.6 mm to 2.7 mm. This size is much larger than is commonly known in the prior art. The provision of perforations of this size provides unexpected advantages in balancing the adhesiveness and absorption rate of the dressing. In general, increasing the percentage of the overall open area provided by the perforations increases the absorption rate while decreasing the adhesiveness.

[0075] Applicants have found that having perforations of approximately 2.2 mm provides an exemplary perforation size that balances absorption rate and adhesion. Reducing the perforation size below 2.2 mm increases the effect of surface tension, while increasing the perforation size further reduces adhesion but provides little increase in absorption rate.

[0076] Moreover, the uniform distribution of perforations throughout the dressing can simplify the manufacturing process of the dressing. Thus, the size of the perforations can include a compromise between the performance requirements of the dressing's boundary region, where breathability is emphasized, and the performance requirements of the wound contact portion, where the interface between the dressing and the wound bed is emphasized. FIG. 1 shows an exploded view of a wound dressing 10 according to an embodiment of the present invention. As shown, the wound dressing 10 may include, in order, a backing layer 12, a superabsorbent layer 14, a foam layer 16, a wound contact layer 18, and a wound site adhesive layer 20. The order of the various layers may be interchanged in some embodiments. For example, the foam layer 16 and the superabsorbent layer 14 may be interchanged to provide a wound dressing including, in order from top to bottom, the backing layer 12, the foam layer 16, the superabsorbent layer 14, the wound contact layer 18, and the wound site adhesive layer 20. Additionally, although the present disclosure relates primarily to wound dressings including a foam layer, it is contemplated that some of the teachings disclosed herein apply equally to embodiments in which the foam layer 16 is omitted.

[0077] As shown, the superabsorbent layer 14 may have an outer contour and the wound contact layer 18 may have a corresponding outer contour positioned to the outer contour of the superabsorbent layer 14. The foam layer 16 may have a corresponding foam outer contour positioned to the outer contour of the superabsorbent layer 14. Additionally, the wound contact layer 18 may be imperforate, in other words, lacking fenestrations.

[0078] Figure 2 illustrates an alternative arrangement of a wound dressing 210. The wound dressing 210 includes 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 illustrated in Figure 2 may be swapped in some embodiments, and the foam layer 16 may be omitted.

[0079] Figure 4 shows an alternative wound dressing 410 without a wound site adhesive layer, where the different layers share the same footprint and are typically used with an additional bandage, such as a compression bandage, or tape to be positioned in place. Figure 4 also shows intralayer adhesives 24, 26 that may be used in any of the dressings disclosed herein to adhere adjacent layers together.

[0080] As will be appreciated, 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 peripheral border wound site adhesive layer 22, whereas in Figure 2, the wound site adhesive layer 220 extends continuously throughout the dressing and is located below the wound contact layer 18. The backing layer 12, superabsorbent layer 14, foam 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 apply to either or both of the wound dressings 10 and 210. Also, as discussed above, it will be appreciated that the locations of the foam layer 16 and superabsorbent layer 14 may be interchanged in each dressing.

[0081] The wound site adhesive layer 20, 220 shown in Figures 1 and 2 extends radially inward from the outermost edge 12a of the backing layer 12, and therefore the wound dressing 10, towards the central region and the wound contact layer 18. The outermost areas of the wound site adhesive layer 20, 220 provided at the border region contact the backing layer 12 so that the backing layer 12 can be directly adhered to the periphery of the patient's wound site. In this manner, the backing layer 12 is adhered and sealed adjacent to the wound site, providing an envelope onto which the other wound dressing layers are applied.

[0082] The wound site adhesive layer 20 of FIG. 1 includes 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 the central region of the dressing. Furthermore, the inner edge 20b may be located radially inward 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 an adhesive interface. This overlap may be provided to ensure that the wound contact layer 18 is positioned relative to the backing layer 12 and wound bed such that the wound contact layer 18 is held in place when 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 completely across the entire wound contact layer 18. The central and border regions, on the other hand, may include patterns of different perforation sizes, as further described below.

[0083] The choice of whether to have a border-only wound site adhesive layer 20 or a full wound site adhesive layer 220 may be application specific and may be determined by the exudate level of the wound being dressed. Thus, for dressings used with low to moderate exudate levels, a full wound site adhesive layer 220 may be selected. For dressings used with high exudate levels, a border-only wound site adhesive layer 20 may be selected to maximize exudate absorption.

[0084] In wounds with high exudate levels, perforations may allow fluid to migrate into the superabsorbent layer 14, while the use of silicone adhesive layer 220 helps prevent adhesion of the wound to areas of low exudate (it will be appreciated that wounds may have mixed etiologies).The dressings disclosed herein may be particularly useful where pressure sore prevention and / or skin protection around the wound is required.

[0085] In some dressings, the wound contact layer may be pre-hydrated with saline to replenish fluids to the wound and support autolytic debridement.

[0086] 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 generally not repositionable. Silicone adhesives also provide good adhesion to human skin, but are hydrophobic and may provide a barrier to exudates and limit moisture transmission vapour rate (MTVR). Therefore, 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 adhesive layer may have a base weight in the range of 70 gsm to 200 gsm. For example, the base weight may be 70 gsm, 80 gsm, 100 gsm, 130 gsm, 150 gsm, or 200 gsm. The thickness of the adhesive may be 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.

[0087] The wound site adhesive layers 20 and 220 of Figures 1 and 2 may include 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 adhesion duration of the dressing, i.e., wear time, and the versatility of the dressing 10, 210, i.e., the range of exudate levels the dressing may be used with.

[0088] More specifically, the wear time of the wound dressing may be increased by increasing the Trans Epidermal Water Loss (TEWL) in the border areas where moisture such as sweat tends to accumulate more, causing the dressing to break down. The perforations on the wound contact layer may increase the moisture vapor transmission rate (MVTR) of the adhesive layer 20, 220 by absorbing exudate through the perforations and then transferring it to the outer layer.

[0089] As mentioned above, the embodiment of Figure 2 shows perforations 22 extending throughout the entire extent 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).

[0090] 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. Therefore, perforations 22 may be used under the wound contact layer 18 to reduce the contact area with the wound. This may allow for greater amounts of exudate to be extracted over a longer period of time in a suitable wound contact layer 18 and superabsorbent layer 14 combination. This problem may be mitigated by using a hydrophobic wound contact adhesive such as silicone.

[0091] Furthermore, by selecting the correct size of the perforations 22, one can ensure that the wound dressing 10, 210 will be effective over a wide range of exudate levels, meaning that a single dressing can be used on a wider range of wounds.

[0092] As mentioned above, the selection of the size of the perforations can be complicated by the fact that there are multiple requirements for the perforations. For perforations 22 between the backing layer 12 and the skin, it is required to find a balance between breathability and adhesion to increase the wear time. For perforations 22 between the wound contact layer 18 and the wound bed, there is a balance between the fluid handling properties of the perforations 22 and maintaining hygiene at the wound site by preventing the adhesion of the wound contact layer to the wound bed. To address this design conflict, some wound dressings may have different perforations in different areas of the wound dressing to meet the various requirements. However, having different perforations in different areas makes the manufacturing process of the wound site adhesive layer more complicated.

[0093] Applicants have found that controlling the size of the perforations between 1.6mm and 2.7mm provides a good balance between the wear time of the dressing and the control of exudate absorption. This size is significantly larger than the perforations disclosed in US10231874, briefly discussed in the Background section. More specifically, as discussed above, Applicants have found that a more preferred range of perforations is 2.1mm to 2.3mm, and most preferably 2.2mm. It will be understood that the sizes of the perforations 22 provided herein are nominal values ​​and may be subject to normal manufacturing tolerances.

[0094] Perforations 22 are generally through holes 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, may be exposed through the perforations 22 while being able to adhere to the wound site via the adhesive layer 20, 220.

[0095] The perforations 22 may be of any suitable shape and may be provided in any suitable pattern or distribution. In some embodiments, the shape of the perforations 22 may be rounded, for example circular or elliptical. Providing round perforations may be advantageous in manufacturing. In particular, when the perforations are formed with a punch, round holes are less likely to result in residual adhesion of cut-out portions (which may be referred to as slugs) compared to shapes in which the cut-out features sharp apexes or corners. However, it will be understood that the size and shape of the perforations 22 may differ from one another.

[0096] The distribution of the perforations 22 may be region specific or continuous across the extent of the wound adhesive layer 20. The distribution, and optionally the size and optionally the shape, may be uniform across a given area of ​​the wound dressing. For example, the perforations 22 may be equally spaced with a first spacing between adjacent perforations 22 in the border area and equally spaced with a second spacing across the wound contact layer 18. In other embodiments, the perforations 22 may be uniformly distributed across the entire extent of the wound site adhesive layer 18.

[0097] FIG. 3 is a schematic diagram of a wound site adhesive layer 320 including a uniformly arranged 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 a plan view. Each cell LC of the diamond lattice (only one of which is highlighted) may include a perforation 22 at each vertex and may have a major axis and a minor axis. The major axis is longer than the minor axis. In the embodiment shown in FIG. 3, the major axis extends horizontally and the minor axis extends vertically, however this is not conclusive and does not indicate any orientation related to how the wound dressing 10, 210 may be applied. The perforated adhesive layer 320 shown in FIG. 3 includes curved peripheral edges, however this is not limited thereto and the wound dressing 10, 210 and wound site adhesive layer 22 may be any shape.

[0098] To provide a grid arrangement of the perforations 22, the perforations 22 are arranged in a number of equally spaced rows R i, and several equally spaced columns C j where i and j are integers. i and column C j Each of the C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, C11, C12, C13, C14, C15, C16, C17, C18, C20, C21, C32, C43, C54, C65, C76, C87, C98, C10, C11, C12, C13, C24, C14, C15, C26 ...24, C12, C13, C24, C14, C15, C j are axially offset from each other (relative to the longitudinal axis of the row). j The spacing between the perforations 22 in the row R i The spacing between the perforations may be smaller than that in the

[0099] Column C j The spacing between the centers of the rows R i Column C j The spacing is 3.9mm~8.1mm, row R i The spacing between the lattices may be 2.5 mm to 5.1 mm. When considered as the aforementioned diamond lattice, the lines of the lattice may be inclined with respect to the horizontal as indicated by α.

[0100] 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. The perforations 22 may be manufactured using any suitable known technique. One conventional technique involves drilling holes in the adhesive sheet before it is laminated to the wound dressing 10, 210. Another technique involves laser cutting the perforations.

[0101] As mentioned above, in some embodiments, the wound dressing 10, 210 may include a uniform distribution of similarly sized perforations in the area of ​​the wound contact layer 18 and may include different sized perforations or no perforations in the peripheral area of ​​the dressing 10, 210. Similarly, if the central wound contact layer area is adhesive free, then the peripheral area may be provided with a uniform distribution of perforations.

[0102] However, the manufacture of a wound site adhesive layer 20 with a non-uniform or topic-specific distribution / size / shape requires a more complicated manufacturing process. The manufacture of the adhesive layer 320 may be simpler and cheaper if the perforations 22 are provided with the same size and distribution so that the adhesive layer can be provided in a larger sheet or roll and then laminated together with other layers in the dressing 10, 210. However, providing a uniform distribution of perforations 22 in terms of size, shape and / or layout may be detrimental to the performance requirements mentioned above in terms of exudate absorption rate and wear time control.

[0103] Returning to Figures 1 and 2, as mentioned above, the coat weight of the wound site adhesive layer 20, 220 may be between 70 gsm and 200 gsm. For example, the base 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 the coat weight of the adhesive and the adhesive strength. However, applicants have found that for different formulations of adhesive, there are different plateaus where increasing adhesive strength is achieved with increasing coat weight. Furthermore, increasing the coat weight of the adhesive in turn increases the thickness, which increases the likelihood that the adhesive edge of the wound dressing will mechanically deform (i.e., turn over or roll up). Applicants have found that coat weights towards the lower end of the 70-100 gsm range, such as 70 gsm, provide a reasonable balance between adhesive performance and thickness to reduce internal mechanical stresses of the wound dressing.

[0104] Although not shown, the wound dressing may include a release layer that covers the wound site adhesive layer 20 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.

[0105] As discussed above in relation to FIG. 1, the border region of the wound site adhesive layer may partially overlap the wound contact layer 18 such that the wound contact layer 18 is held in a fixed relationship to the backing layer 12 via the adhesive layer. This 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 may be generally similar around the periphery of the wound contact layer 18 such that the overlap has a constant width. In other embodiments, the width of the overlap may vary around the periphery. In some embodiments, the dressing may be polygonal, e.g., quadrilateral / rectangle / square, in plan view, 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, such that the overlap is greater in the corner regions.

[0106] 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 region where the wound contact layer 518 is exposed. The wound contact layer 518 includes an outer edge 518'.

[0107] The dressing is generally square in plan view with the wound contact layer edge 518' including a first radius R1 that is less than the inner edge radius R2 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 with the same radius of curvature. The increased overlap in the corner regions may allow for a stronger bond between the wound contact layer 18 and the adhesive layer 20 without significantly compromising the absorbency of the dressing.

[0108] In the embodiment shown in FIG. 5, the dressing 510 may comprise a backing layer measuring 85 mm×85 mm (±5 mm) in plan view. The radius of curvature of the edge 20′ of the adhesive layer may be between 10 mm and 15 mm, preferably around 12.5 mm. The radius of curvature of the edge 518′ of the wound contact layer may be between 7.5 mm and 12.5 mm, preferably around 10 mm, but in any case smaller than the radius of curvature of the edge 520′ of the adhesive layer. The width of the overlap away from the corner region may be constant. In the embodiment shown in FIG. 5, the width of the overlap w is between 10 mm and 20 mm, preferably around 15 mm. The width of the exposed opening of the wound contact layer in the adhesive layer may be between 30 mm and 40 mm. The width of the wound contact layer may be between 45 mm and 50 mm.

[0109] The increase in curvature of the corners of the inner edge of the adhesive layer can be approximately 3-6% compared to dressings with a constant radius of curvature.

[0110] While the above dimensions are for a particular embodiment, it will be understood that the ratios of the various measurements may apply to other dressings. Additionally, although the dressings are shown as having substantially straight sides, the sides may include a general curvature while being distinct from the corner regions.

[0111] 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 for direct contact with the wound bed and a second surface facing the backing layer 12. As shown in Figures 1 and 2, the superabsorbent layer 14 may be located between the backing layer 12 and the second surface of the wound contact layer 18.

[0112] 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 it and retaining it within the dressing. Although water in the gelling absorbent may 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 therefore must have sufficient capacity to retain the exudate throughout the duration of the dressing. This affects the amount of absorbent required in the wound dressing and of course the overall thickness and conformability of the dressing. Furthermore, in general, gelling absorbents, particularly fibrous gelling absorbents, do not have a linear relationship between the thickness or weight per unit area of ​​the gelling absorbent layer and absorbency. This means that a trade-off is required between absorbency, conformability, and water vapor transmission in conventional gelling absorbents.

[0113] The applicant's patent EP2498829 provides an absorbent element for wound dressings having a wound contact layer comprising gel-forming fibres bonded to a foam layer in such a way that the wound contact layer, which absorbs exudate by gelling and inhibits its lateral spread, is combined with a foam layer which absorbs exudate but readily releases it by water vapour transmission. At the priority date of EP2498829, it was believed that the presence of the gel forming the wound contact layer would limit the lateral spread of exudate in the foam, increase the retention of exudate compared to the use of foam alone and improve the water vapour transmission properties of the wound contact layer.

[0114] The present invention provides an extension of the concept described in EP2498829, in which instead of a foam layer that absorbs exudate and releases it by water vapor transmission, a superabsorbent layer is provided in conjunction with the foam layer. The applicants have discovered that instead of using a foam layer that absorbs exudate and releases it by water vapor transmission, a superabsorbent material is used to absorb and retain exudate, thereby improving the exudate removal rate and wear time of the wound dressing while limiting the lateral spread of exudate. Thus, the present invention provides a dressing that increases fluid handling and retention while preventing lateral spread of exudate. In this way, the use of a superabsorbent layer in conjunction with a gelling absorbent allows a larger amount of fluid to be trapped without relying on water vapor release from the dressing. This leads to an improvement in dressings in general, but may be particularly advantageous when the dressing is covered, for example when a pressure bandage is used in conjunction with the dressing, reducing the MVTR.

[0115] Superabsorbent polymers are known in the art for their fluid absorption and retention properties and are utilized in various industries. Generally, superabsorbent layers are available in two forms: SAF, which is a superabsorbent (e.g., polyacrylate) fiber, and SAP, which is a superabsorbent (e.g., polyacrylate) polymer. The wound dressing of the present disclosure may comprise a superabsorbent layer containing either or both SAF and SAP, but in a preferred embodiment, the superabsorbent layer contains only SAF. Providing an SAF-only superabsorbent layer allows for cutting of the wound dressing prior to use, which is not possible with SAP or SAF / SAP blends due to the particulate nature of SAP. Furthermore, it has been found that the use of an SAF-only superabsorbent layer can improve compatibility, especially when used in laminate dressings where intralayer adhesives are used as described below.

[0116] The use of SAF also improves fluid retention performance compared to dressings and SAPs that do not include a superabsorbent layer. Table 1 below shows comparative data for a dressing including a prior art gelling absorbent / foam dressing combination (Sample 1) and prototype dressings including i) a gelling wound contact layer combined with an unrestricted SAP layer (Sample 2) where the wound contact layer and superabsorbent layer are free to move relative to one another, ii) a gelling wound contact layer combined with a laminated gelling wound contact layer and SAP layer, and iii) a gelling wound contact layer combined with a laminate of a gelling wound contact layer and an SAF layer.

[0117] [Table 1] TIFF2025507488000002.tif45166

[0118] Table 1 shows the fluid retention properties of dressings without a superabsorbent layer and dressings with various SAP and SAF layers.

[0119] As can be seen from Table 1, the use of laminated SAF can provide increased levels of absorbency per unit area and improved fluid retention when compared to laminated SAP products.

[0120] In a preferred embodiment, the superabsorbent layer may comprise a blend of sodium polyacrylate and polyester fibers. The ratio of superabsorbent fibers to polyester fibers may be between 40:60 and 55:45. In some preferred embodiments, the superabsorbent layer may be constructed in a ratio of 40:60. Although the small amount of superabsorbent fibers has a limited effect on the conformability or fluid handling capacity of the dressing, the small amount of superabsorbent fibers may prevent distortion of the layer dressing during subsequent manufacturing steps, especially during sterilization of the dressing.

[0121] The superabsorbent layer may comprise nonwoven fibers and may have a thickness of 1.5 mm to 2.5 mm. In some preferred embodiments, the thickness may optionally be 2 mm. The thickness of the superabsorbent layer may be determined by balancing patient comfort, compatibility, and fluid handling performance.

[0122] 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 level and feel 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.

[0123] The foam layer 16 is preferably a hydrophilic foam such as polyurethane, more preferably a hydrophilic open celled foam such as that available from Freudenberg, Filtrona, especially Filtrona 30W. Typically the foam has a thickness of 0.25mm to 5mm, preferably 1mm to 4.0mm, most preferably 1.5mm to 3mm. The foam layer preferably has an absorbency of 10 to 20g / g as measured by the free swell absorbency method (BS EN 13726-1:2002).

[0124] The foam layer may have a thickness of 1.3 mm to 3.2 mm, optionally 2.5 mm. The foam may be polyurethane (PU). In one advantageous embodiment, the aliphatic polyurethane foam may be 1.5 mm or 3 mm thick. In another advantageous embodiment, the MDI polyurethane foam may be 1.5 mm or 3 mm thick.

[0125] Six prototype dressings were made to demonstrate the effectiveness of the gelling wound contact layer and the superabsorbent layer. Each of the dressings included a ConvaTec® Hydrofibre® wound contact layer with a base weight of 150 gsm and a polyurethane 30 micron backing layer. In addition to the wound contact and backing layers, each of the prototypes included 2.5 mm PU foam or 1.5 mm MDI foam. Prototypes 1 and 2 did not include a superabsorbent layer. Prototypes 3 and 4 included an SAF layer immediately below the backing layer, followed by their respective foam layer and wound contact layer. Prototypes 5 and 6 included a foam layer immediately below the backing layer, followed by the wound contact layer. Thus, the order of the foam layer and SAF layer was reversed for prototypes 3 and 4, and prototypes 5 and 6. Five samples were tested for each prototype.

[0126] Table 2 shows the fluids absorbed and retained by the prototype wound dressings, as well as the retention rates. The last two columns indicate which foam was used (X indicates foam use).

[0127] [Table 2] TIFF2025507488000003.tif47168

[0128] A comparison of the absorbency and retention of dressings without and with an SAF layer is shown in Table 2.

[0129] As can be seen from the data provided in Table 2, all dressings have high retention, with the presence of a superabsorbent layer improving absorbency. The position of the foam has limited effect on retention. The thicker 2.5mm PU foam increases absorbency, while the MDI foam increases retention. Further increasing the thickness of the foam layer, for example to 3mm, may further improve absorbency. However, increasing the foam thickness has been shown to decrease retention, as shown by the 2.5mm PU foam having lower retention than the 1.5mm thick MDI foam.

[0130] As mentioned above, the wound contact layer is fibrous and contains gel-forming fibres. In contrast to polymeric layers, fibrous layers have the advantage in particular of being capable of gel blocking, limiting the lateral spread of exudate. Furthermore, exudate is rapidly absorbed and retained under pressure.

[0131] Fibers suitable for use in the wound contact layer of the present disclosure include hydrophilic fibers that become wet, slippery, and gel upon uptake of wound exudate, thereby reducing the tendency of surrounding fibers to adhere to the wound. The fibers may be of the type that retains structural integrity upon absorption of exudate, or may be of the type that loses its fibrous form upon absorption of exudate, becoming a structureless gel or solution.

[0132] 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 also be pectin fibres, alginate fibres, in particular as described in WO94 / 17227 or EP433354 or EP476756, or alginate and polysaccharide composite fibres as described in EP0892863, chitosan fibres, hyaluronic acid fibres or fibres derived from other polysaccharide fibres or gums. The cellulosic 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 an absorbency of at least 15 g / g, more preferably at least 25 g / g or 50 g / g, either water or saline, measured by the free swelling water absorbency method. The degree of substitution of the carboxymethylated cellulose gel-forming fibers is preferably at least 0.2 carboxymethyl groups per cellulose unit, more preferably 0.3 to 0.5.

[0133] The gel-forming fibers are preferably mixed to give a wound contact layer containing fibers of different absorbency or characteristics. The wound contact layer may be natural or synthetic, but may contain other fibers, such as woven fibers, preferably cellulosic fibers, such as viscose rayon, polyhedral viscose, cotton, regenerated cellulose, etc., which have higher absorbency than most woven fibers. Typically, woven fibers have an absorbency of less than 1g / g, as measured by the free swell water absorption test. The wound contact layer may be made from a nonwoven fibrous web formed by any method, such as needle punched, spunlaced, wet laid, dry laid, meltblown, or felted. The web may then be stitch bonded with reinforcing fibers or threads to provide additional strength to the layer, so that the layer retains its structure when saturated with exudate. Furthermore, the stitch-bonded structure may provide the dressing with high absorbency or extensibility depending on the nature of the reinforcing fibers and yarns used, and the stitch-bonded pattern. The wound contact layer is preferably 20 microns to 5 mm thick, more preferably 2 mm to 3 mm thick, and even more preferably 1 mm to 2 mm thick. In some embodiments, the thickness may be, for example, 1 mm or 1.5 mm.

[0134] The basis weight of the wound contact layer can affect the fluid handling capacity of the wound dressing, and typically, increasing the basis weight can beneficially increase absorbency.Surprisingly, the applicants have found that reducing the basis weight of a dressing that includes a superabsorbent layer, particularly a SAF superabsorbent layer, has minimal effect on fluid absorption and fluid retention.To demonstrate this, four prototypes of wound dressings were made to determine the level of basis weight when used with a superabsorbent layer. The four prototypes shown in Table 4 include a first wound dressing with a 100 gsm wound contact layer and no superabsorbent layer, a second wound dressing with a 70 gsm wound contact layer, 2.5 mm polyurethane foam, and 2 mm SAF superabsorbent layer, a third wound dressing with a 100 gsm SAF wound contact layer, 2.5 mm polyurethane foam, and 2 mm SAF superabsorbent layer, and a fourth wound dressing with a 70 gsm wound contact layer, 2.5 mm polyurethane foam, and 2 mm SAF superabsorbent layer. The wound contact layer was ConvaTec's Hydrofiber®. The first sample was a prior art Aquacel® foam product with a 100 gsm Hydrofiber® layer bonded to PU foam. Table 4 below summarizes the fluid absorption and retention test results for n=5.

[0135] [Table 4] TIFF2025507488000004.tif73148

[0136] Table 4 - Fluid absorbency and retention of various wound dressings with different wound contact base layers, without a superabsorbent layer and with a SAF superabsorbent layer.

[0137] As can be seen, when using SAF superabsorbent layers in combination with foams, increasing the base weight has little effect on the absorbency and retention of the wound dressing. However, providing a lower base weight can help reduce the interlaminar stress and associated deformation of the wound dressing. Therefore, in some preferred embodiments, a 70gsm wound contact layer can be used. Furthermore, a lower base weight can result in a thinner dressing. Also, 70gsm can be the minimum practical for manufacturing, since lower weights lack strength.

[0138] As previously described in connection with Figures 1 and 2, the dressing may include a backing layer on which the wound contact layer and the superabsorbent layer are provided. The backing layer may be breathable to allow water vapor release from the dressing while preventing 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 include blown polyurethane 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 supplied by Covestro AG, or Transcontinental Coatings Inspire 2301. The backing layer may have a thickness of 25 microns to 35 microns, preferably 30 microns. Preferably, the film layer may have an MVTR (liquid contact) of at least 10,000 / m2 / 24hrs.

[0139] In some embodiments, the backing layer may be adhesive or may include an adhesive film that provides adhesion to the wound site. The adhesive may extend over the entire area of ​​the backing layer such that the backing layer adheres at the dressing's border around the wound site, and may also adhere to the top layer of the dressing stack, such as the superabsorbent layer. However, as described below, in some embodiments, the adjacent central area where the top layers of the dressing are placed and contacted may be adhesive-free, with only the backing layer adhering to the skin. It will be appreciated that the adhesive at the wound site may be applied directly to the backing layer or may be a separate sheet that is laminated to the backing layer.

[0140] The adhesive or adhesive film may comprise an acrylic adhesive as known in the art. The acrylic adhesive may have a density of 5 to 20 g / m 2 and may include a hexagonal pattern. The adhesive pattern may be selected to increase open area and breathability while providing sufficient surface area for attachment 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.

[0141] As described below, the wound dressing may include a laminated structure in which various layers are bonded together to prevent movement prior to use and application. Bonding the various layers together may be accomplished using any suitable technique, such as polymer-based melt layers, adhesives, flame lamination, direct lamination via foam casting, or ultrasonics. Additionally, intralayer adhesives 24, 26 as shown in FIG. 4 may be used to bond the various layers together.

[0142] The intralayer adhesive (which may also be referred to as a binder) may be, for example, a continuous layer, a perforated layer, a liquid adhesive, or a spread coat adhesive. The binder may be a web containing continuous or broken layers of adhesive that are inserted between each adjacent layer and activated to bond the layers together. The binder may be heat activated, for example, where heat and pressure are applied during the lamination process. The film may include a web of strands or dots of adhesive.

[0143] Spread coat adhesives are known in the art and relate to a method of dispersing a powder adhesive on a surface prior to lamination of the layers to provide a layer or adhesive. Spread coat adhesives may be used for some or all of the intralayer adhesives. For example, a spread coat adhesive may be used to adhere a superabsorbent layer to a foam, and an alternative adhesive technology may be used to adhere the foam to a wound contact layer.

[0144] 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 bonded to the backing layer, such that the backing layer and the top layer are free to move relative to each other. Thus, one or more of the internal layers of the wound dressing may include an area free of adhesive between the second surface of the superabsorbent layer and the backing layer. In such a case, the wound dressing may include an internal stack of layers, e.g., including a wound contact layer, a foam layer, and a superabsorbent layer, which are attached to the backing layer via the wound contact layer. As described above, the wound contact layer may be attached to the backing layer via a wound site contact layer.

[0145] 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 and the backing layer, or at least between the top layer and the backing layer, allows for relative contraction or expansion of each layer during manufacture of the dressing. This may allow for alternative and advantageous manipulations during manufacture of the dressing.

[0146] Such manufacturing steps may include sterilization of the dressing. In some embodiments, the wound dressing 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. If attached to the backing layer, deformation of the backing layer, such as wrinkling or distortion, may occur, resulting in an unsightly appearance. Therefore, it may be advantageous to provide some relative separation between layers.

[0147] One or more embodiments have been described above by way of example only. Many modifications are possible without departing from the scope of protection afforded by the appended claims.

Claims

1. A wound dressing material Backing layer; A wound contact layer having a first surface for direct contact with the wound bed and a second surface on the backing layer side; and Superabsorbent layer Includes, The wound contact layer comprises gel-forming fibers, The superabsorbent layer is located between the backing layer and the second surface of the wound contact layer. The superabsorbent layer is a wound dressing material comprising a blend of sodium polyacrylate fibers and polyester fibers.

2. The wound dressing according to claim 1, wherein the superabsorbent layer has an outer contour, and the wound contact layer has a corresponding outer contour positioned on the outer contour of the superabsorbent layer.

3. The wound dressing according to claim 1, further comprising a foam layer located between the backing layer and the second surface of the wound contact layer.

4. The wound dressing according to claim 3, wherein the backing layer comprises a polyurethane material.

5. The wound dressing material according to claim 3 or 4, wherein the foam layer is located between the backing layer and the superabsorbent layer.

6. The wound dressing material according to claim 1, wherein the superabsorbent layer includes nonwoven fibers.

7. The wound dressing material according to claim 6, wherein the superabsorbent layer comprises only the nonwoven fibers.

8. The wound dressing material according to claim 3, wherein the foamed layer is an aliphatic foam or a methylenediphenyl disocyanate foam.

9. The wound dressing material according to claim 3, wherein the foam is a polyurethane foam.

10. The wound dressing material according to claim 3, wherein the foam layer has a thickness of 1.3 mm to 3.2 mm, and optionally 2.5 mm.

11. The wound dressing material according to claim 1, wherein the wound contact layer includes cellulose fibers.

12. The wound dressing material according to claim 11, wherein the wound contact layer comprises carboxymethylated cellulose fibers.

13. The wound dressing material according to claim 11 or 12, wherein the backing layer comprises a polyurethane material.

14. The wound dressing according to claim 13, further comprising a foam layer located between the backing layer and the second surface of the wound contact layer.

15. The wound dressing material according to claim 1, wherein the wound contact layer has a thickness of 1 mm to 1.5 mm.

16. The wound dressing material according to claim 1, wherein the wound contact layer has a base weight of 70 gsm to 150 gsm, optionally 70 gsm.

17. The wound dressing according to claim 1, wherein the backing layer includes a polyurethane material.

18. The wound dressing material according to any one of claims 1 to 17, wherein the backing layer has a thickness of 30 microns.

19. The wound dressing material according to any one of claims 1 to 18, wherein the ratio of the sodium polyacrylate fiber and the polyester fiber is 40:60 to 55:45.

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