Wound care dressings have a wide variety of functions and applications. One subset of wound dressings consist of a flexible, permeable mesh backed with a pressure-sensitive adhesive (PSA) which is placed over a wound (unsutured or as an adjunct to sutures). The mesh is permeable, and the PSA is pattern-coated to allow a polymerizable adhesive, typically cyanoacrylate, to penetrate the mesh and form a barrier over the mesh and wound. Such a dressing is known, for example, from US2005182443A1.
US20210212676A1 and US2018303967A1 both disclose similar dressings. US20210212676A1 additionally discloses that the mesh comprises windows for drainage of wound exudate away from the wound. A flap is provided to cover the openings and provide access for wound inspection. US2018303967A1 discloses that the mesh is adhered to the skin partially by traces of soluble pressure sensitive adhesive. After application, the soluble pressure sensitive adhesive is dissolved by wound exudate, creating a drainage channel to convey wound exudate away from the wound. Absorbent pads may be provided on a periphery of the mesh to absorb the wound exudate.
It is possible to incorporate antimicrobial agents into cyanoacrylate. However, the drawbacks to this include poor stability of the formulation and a reduced efficacy of the antimicrobial effect, as the antimicrobial agent may be trapped and unable to destroy the bacteria. Where an antimicrobial agent is provided on the mesh prior to coating with a PSA, this also has drawbacks as the impregnated mesh makes the manufacturing process more complicated, the subsequent application of the PSA reduces the potency and/or availability of the antimicrobial agent which can result in inconsistent potencies depending on how much liquid adhesive is applied to the mesh, and the antimicrobial agent may interfere with the initiation of the cyanoacrylate.
Viewed from a first aspect, the present disclosure provides a dressing for application onto a wound. The dressing comprises: a porous mesh comprising a wound-facing side coated with an adhesive for adhering the porous mesh to the skin, the porous mesh being configured for application of a polymerizable adhesive such that after application the polymerized adhesive and porous mesh together form a barrier covering the wound. The dressing also comprises an absorbent patch disposed on the wound-facing side of the porous mesh and arranged to overlie the wound during use.
Thus, the dressing, in particular the absorbent patch, prevents contact between the polymerizable adhesive and the wound, which may reduce irritation and foreign body reactions caused by adhesive penetration at the wound. The present dressing also allows for the absorption of wound exudate from the covered wound by the absorbent patch, which can prevent the exudate from interfering with polymerization of the adhesive, thus improving the formation of the barrier. In addition, the absorbent patch may prevent the exudate from escaping from the dressing after application of the polymerizable adhesive, resulting in a longer lasting dressing and barrier.
In addition, as the polymerizable adhesive is not applied directly to the wound site, the present dressing may cause less damage to the healed tissue at the wound site during removal of the dressing.
In some cases, the absorbent patch comprises a gel-forming material. In some cases, the absorbent patch, for example the gel-forming material, may comprise any one or more of a biosynthetic material, a hydrogel, a foam, or a hydrocolloid. Biosynthetic materials can include alginate, collagen, hyaluronic acid, honey and chitosan, cellulose. The gel-forming material may be provided in a gel-forming layer of the absorbent patch. The gel-forming material may advantageously provide a more effective wound-healing environment compared to prior art dressings. In particular, the gel-forming material may maintain a moist wound environment within the barrier provided by the porous mesh and polymerized adhesive. Such a sealed, moist environment may promote wound healing by the body's own enzymes. Chitosan, cellulose and hyaluronic acid are particularly effective at providing enhanced wound healing effects.
In some examples the adhesive and/or the absorbent patch comprises a medicament. The medicament may be for any combination of: preventing colonization of the dressing, infection control, wound healing and cosmesis. The medicament may be an antimicrobial agent. The present dressing allows medicaments to be more easily incorporated into the wound contacting material or absorbent patch to aid prevention of colonization of the dressing, infection control, wound healing, cosmesis. Silver, chitosan and honey are examples of antimicrobial agents which are particularly advantageous.
In some examples the medicament is provided on a wound facing side of the absorbent patch. This may shield the medicament from the polymerizable adhesive and prevent interference between the medicament and the polymerizable adhesive, which may otherwise cause instability in the polymerizable adhesive and/or reduced effectiveness of the medicament. In some examples, the medicament is present in the adhesive in a range of between Oppm and about 5000 ppm (e.g., between 0 ppm and 5000 ppm), preferably between about 200 ppm and about 1 000 ppm (between 200 ppm and 1 000 ppm).
In some examples the absorbent patch may comprise a liner portion and an absorbent portion. The liner portion may be substantially impermeable, particularly substantially water-impermeable. The liner portion may be in contact with the porous mesh, and the absorbent portion may face the wound. The liner portion may help to prevent the polymerizable adhesive from reaching the wound during application, and may also help prevent wound exudate from reaching the mesh before, during and after application of the polymerizable adhesive. In addition, if the absorbent patch comprises a medicament, as described above, the liner portion may help to separate the polymerizable adhesive from the medicament during application of the polymerizable adhesive.
In some cases the porous mesh extends beyond an outer perimeter of the absorbent patch. The porous mesh may extend beyond the absorbent patch by at least 1 centimetre. In some cases the porous mesh may extend beyond the absorbent patch by less than 1 centimetre. In some cases, the porous mesh may circumscribe the absorbent patch. In this way, the porous mesh is adhered to the skin by the polymerizable adhesive about the entire periphery of the absorbent patch, providing a sealed wound-healing environment. In examples, the adhesive on the porous mesh may also circumscribe the absorbent patch, and may extend beyond the absorbent patch by at least 1 centimetre. In this way, the dressing can be secured to the skin by the adhesive before application of the polymerizable adhesive.
The dressing may comprise a releasable liner releasably attached to the wound facing side of the porous mesh and covering the absorbent patch. The releasable liner may comprise a central portion overlying a portion of the porous mesh and absorbent patch, and one or more peripheral portions separable from the central portion. One or both of the peripheral portions may partially overlie the absorbent patch, or may be spaced from the absorbent patch. The porous mesh may comprise an initiator for curing the polymerizable adhesive after application the polymerized adhesive to the porous mesh. The absorbent patch may comprise any of polyurethane, silicone or calcium.
There is also provided a kit for dressing a wound. The kit comprises: a dressing as described above, and a liquid polymerizable adhesive. In examples, the kit may comprise a dispenser containing the polymerizable adhesive. In examples, the dispenser further comprises a polymerization rate accelerator or modifier. In some examples the polymerizable adhesive comprises cyanoacrylate, in particular a formulation of 2-octylcyanoacrylate. In some examples, the polymerizable adhesive comprises a light cure acrylate, for example a UV-curable adhesive.
There is also provided a method of preparing a dressing for application onto a wound comprising: providing a porous mesh comprising a wound-facing side, the porous mesh being configured for application of a polymerizable adhesive such that after application the polymerized adhesive and the porous mesh together form a barrier covering the wound, at least partially coating the wound-facing side of the porous mesh with the adhesive, and applying an absorbent patch to the wound-facing side of the porous mesh, such that the absorbent patch is arranged to overlie the wound during use. At least one of the adhesive and/or the absorbent patch comprises a medicament.
The method may comprise dissolving the medicament into the adhesive prior to adhering adhesive to the porous mesh.
When the medicament is dissolved in the adhesive, it may be present in a concentration of between Oppm and about 5000 ppm (e.g., between 0 ppm and 5000 ppm), preferably between about 200 ppm and about 1 000 ppm (e.g., between 200 ppm and 1000 ppm).
Embodiments of the invention are further described hereinafter with reference to the accompanying drawings, in which:
The mesh 40 is porous to permit a liquid polymerizable adhesive to penetrate the mesh 40, as described further hereinafter. The mesh 40 can be formed in a number of ways, for example as a woven layer or as an interconnected lattice of fibres. The absorbent patch is absorbent to wound exudate. As explained further below, the absorbent patch 60 may comprise a liner portion and an absorbent portion. The liner portion may help to prevent the liquid polymerizable adhesive from reaching the wound, and may additionally or alternatively help prevent wound exudate from leaving the wound area during application of the dressing. As shown in
In particular, as shown in
As shown in
The absorbent patch 60 is provided on the wound-facing side 44 of the mesh 40 and partially covers the PSA 50. The absorbent patch 60 is flexible to conform to the contours of the skin 5. The absorbent patch 60 is designed to completely cover the wound 7. For example, a wound having a length of up to 58 cm may be dressed by an absorbent patch 60 with a length of at least 60 cm. The absorbent patch 60 can be provided in a range of shapes and thicknesses as required. For example, while a rectangular absorbent patch is shown in the Figures, it would be apparent this was not essential, and the absorbent patch 60 may have an obround profile, or other shape. By providing the absorbent patch 60 on the wound-facing side of the mesh 40, exudate from the wound 7 is absorbed directly into the absorbent patch 60, substantially eliminating the risk of exudate penetrating through to the top side 42 of the mesh 40 (see
The absorbent patch 60 typically comprises a material suitable for wound contact. The absorbent patch 60 comprises a material capable to absorbing wound exudate. By way of example, the absorbent patch 60 may contain a gel-forming material, for example any combination of: a hydrocolloid, an alginate, a cellulose, a foam, or a hydrogel. Gel-forming materials preferably react with the wound exudate to gradually increase the moisture level within the wound environment, encouraging moist wound healing. In some examples, the absorbent patch 60 may comprise polyurethane or silicone. For example, any of a polyurethane foam, a silicone foam, or an alginate fibrous patch or foam may provide suitable absorbent patches 60.
In examples, the absorbent patch 60 may comprise an absorbent material, for example a fibrous patch, such as cellulose fibre or cotton, for example a gauze or surgical sponge. The absorbent patch 60 may have a permeable coating facing the wound to permit absorption of exudate into the absorbent patch 60. The permeable coating on the absorbent patch 60 may allow the dressing 10 to be easily separated from the healed wound when the dressing 10 is removed.
In examples, the absorbent patch 60 comprises a liner portion 62 directed towards the mesh 40, and an absorbent portion 64 directed towards the wound 7. The absorbent portion 64 may additionally have a permeable coating facing the wound. The absorbent patch 60 may comprise an adhesive, on one or both sides, for adhering to the mesh 40 and/or to the wound 7 and skin 5. The absorbent portion 64 of the absorbent patch 60 may comprise an absorbent material, such as cellulose fibre or cotton, for example a gauze or surgical sponge.
In one specific example, the absorbent portion 64 may comprise an absorbent adhesive, for example a hydrocolloid-containing adhesive. Such an absorbent adhesive may limit break down upon saturation to assist in creating optimal skin and wound healing conditions while maintaining a high fluid handling capacity. In various examples, the absorbent patch 60 may contain an integrated hydrocolloid formulation. The hydrocolloid formulation may be provided in the absorbent portion 64 of the absorbent patch 60, or elsewhere, for example as a separate component of the absorbent patch 60.
The absorbent patch 60 may have a thickness between 100 μm and 4000 μm, preferably between about 300 μm and about 2000 μm, more preferably between about 800 μm and about 1500 μm.
The absorbent patch 60 may comprise a transfer tape, for example the MED 2191 H Transfer Tape manufactured by Avery Dennison™. The transfer tape may comprise a liner and an absorbent adhesive. The absorbent adhesive may have a high fluid handling capacity. The absorbent adhesive may include an hydrocolloid formulation. The liner of the transfer tape can be removed prior to assembly of the hydrocolloid layer to the mesh 40.
In some examples one or more medicaments, such as an antimicrobial, may also be incorporated into the absorbent patch 60 or the PSA 50. The medicament(s) may act to aid any combination of: preventing bacterial colonization of the dressing, infection control, wound healing and cosmesis. Silver is a suitable antimicrobial which may be present in the absorbent patch 60 and/or in the PSA 50. Where the antimicrobial is present in the absorbent patch 60 this may be in the form of a silver alginate foam, a polyurethane foam with silver, a silicone foam with silver, or a hydrocolloid gel with silver. Where the antimicrobial is present in the PSA 50, this can be achieved by dissolving the antimicrobial into the PSA 50 prior to coating the porous mesh 40 with any adhesive. Dissolving the antimicrobial into the PSA 50 before application of the PSA 50 to the mesh 40 advantageously reduces the complexity of the process to prepare a dressing 10. Concentrations of up to about 5000 ppm of silver, in particular SmartSilver® WC-10, have been found to be suitable for use with the presently described PSA 50. Preferably, the silver is present in concentrations between about 200ppm and about 1000 ppm in the PSA 50. It would be apparent that pure metallic silver nanoparticles in aqueous polymer solution, such as is found in ACM-5 and WC-10, is merely one example of a suitable antimicrobial agent suitable for use with the present dressing.
Table 1 below shows exemplary time-kill data for various strains of bacteria using a silver PSA 50 coated porous mesh 40 compared to a porous mesh 40 coated with regular PSA 50. Test procedures were according to The American Association of Textile Chemists and Colorists (AATCC) 100, Antibacterial Finishes on Textile Materials: Assessment of (2012) and in compliance with the ISO 13485:2016 standard.
Specified layers of sample were inoculated evenly with the challenge organism. After inoculation, samples were incubated at specified temperature for 24 hours. Immediately after inoculation, zero contact time samples were neutralized with appropriate neutralizer.
Serial dilutions were prepared and plated in duplicate using appropriate media. The 24 hour samples were processed similarly. All plates were incubated at 37±2° C. for 24-48 hours. After incubation the plates were enumerated and the percent reduction was calculated. Organisms were derived from an American Type Culture Collection (ATCC) organism, or an organism determined to be equivalent. Silver was present in a concentration of 600 ppm. For the MRSA, E. coli and P. aeruginosa samples, no Benzethonium Chloride was present on the mesh.
Staphylococcus
aureus, ATCC
E. coli, ATCC
As can be seen from Table 1, the microbial count was significantly reduced by the presence of silver in the mesh 40 before treatment with cyanoacrylate and by silver or cyanoacrylate in the cured sample. For MRSA without silver there was much less reduction for both the cyanoacrylate coated sample and the mesh alone. For E. coli the combination of silver and cyanoacrylate gave a synergistic effect which was not present in the sample without silver or with just cyanoacrylate alone. Table 1 supports the effect that silver combined with the PSA 50 increases the range and breath of microbial control for the porous mesh 40 alone and when covered with cyanoacrylate. The adhesion strength of silver PSA 50 coated mesh 40 was found to be comparable to regular PSA 50 coated mesh 40. Thus the present concentrations of silver in PSA 50 are able to reduce microbial count without compromising on the adhesion strength of the dressing 10.
One way of forming an absorbent patch 60 with a medicament is to attach silver ions onto fibres making up the absorbent patch 60. For example, calcium alginate fibres can be treated with one or more aqueous solutions of silver nitrate. The aqueous solutions allow for the silver ions in solution to be exchanged for calcium ions in the fibre which forms calcium alginate fibres containing silver ions. It would be apparent that other medicaments could be attached in a similar process. It would also be apparent that while an alginate patch is described, other patches or pads containing a medicament could be used, such as a polyurethane foam, a silicone foam or a hydrocolloid gel as described herein. Where the absorbent patch 60 is to contain a hydrocolloid containing silver, this can be achieved by adding a silver compound such as silver sulfadiazine to the hydrocolloid material before film casting.
As the polymerizable liquid 105 (see
Referring to
As illustrated in
Once the dressing 10 has been positioned and adhered to the skin 5 a liquid polymerizable adhesive 105 is applied and cured to form a barrier over and around the wound, as described above. After the dressing 10 has been adhered to the skin 5 and before the polymerizable adhesive 105 has been applied and cured, the absorbent patch 60 acts to absorb wound exudate and prevent the wound exudate from penetrating the mesh 40.
Accordingly, the absorbent patch 60 reduces mixing of the polymerizable adhesive 105 and wound exudate.
By providing an absorbent patch 60 between the mesh 40 and the wound 7, the present dressing 10 prevents direct contact between the polymerizable adhesive 105 and the wound 7, and thereby reduces potential irritation and foreign body reactions caused by the polymerizable adhesive 105 contacting the broken skin 5 of the wound 7. In addition, as the polymerizable adhesive 105 adheres to the skin only where the mesh 40 is in contact with the skin 5 (i.e., around the periphery of the absorbent patch 60), the healed tissue at the wound site is less damaged during removal of the dressing 10. Meanwhile, the barrier 49 extends across the entire mesh 40 and therefore the dressing 10 provides a sealed area enclosing the wound 7. In examples in which the absorbent patch contains a gel-forming material, the combination of the sealed area enclosing the wound 7 and a gel-forming material provided in the absorbent patch 60 creates an improved wound-healing environment.
Throughout the description and claims of this specification, the words “comprise” and “contain” and variations of them mean “including but not limited to”, and they are not intended to (and do not) exclude other moieties, additives, components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.
Features, integers, characteristics, or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.
This application is a continuation-in-part application of Ser. No. 17/859,164 filed Jul. 7, 2022, which is incorporated herein by reference in its entirety. This invention relates to a dressing for application onto a wound, and a kit comprising a dressing and a method of preparing a dressing.
Number | Date | Country | |
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Parent | 17859164 | Jul 2022 | US |
Child | 18108443 | US |