Patent Description:
NPWT is a therapeutic technique used to promote healing in acute or chronic tissue wounds. NPWT systems are configured to apply a negative pressure to a wound, through a dressing that is connected to the wound (e.g., to the skin surrounding the wound). The negative pressure may be utilized to remove infectious materials, and to help promote wound closure and healing. In order to maintain adequate pressure at the wound site, the dressing must form an airtight seal with the patient's tissue. In some instances, it may be desirable to remove the dressing from the wound during treatment to inspect the state of the wound and assess healing progress. This process requires removal of the dressing from the patient, which may degrade the adhesive used to secure the dressing and renders the dressing unusable. It would be desirable to provide a device that allows for inspection of the wound without sacrificing the dressing.

The invention is defined by the independent claim appended hereto. A selection of optional features of the invention is set out in the dependent claims. <CIT> discloses relevant technical background.

Referring generally to the Figures, a dressing with a removable and resealable reclosure system for a negative pressure wound therapy (NPWT) system is shown. The dressing is structured to engage the NPWT system with a patient's skin or other tissue and to provide a substantially airtight seal in an area surrounding the wound. According to an illustrative embodiment, the dressing is a multi-layer dressing that includes a patient interface layer that is structured to bond to the tissue surrounding the wound area, and an upper cover that is applied over the patient interface layer to centrally over the wound site <NUM> and covers the wound site <NUM>. In other embodiments, the dressing <NUM> may only cover a portion of the wound site <NUM> (e.g., a single leg of an incision, a first portion of an irregularly shaped wound, etc.).

According to an illustrative embodiment, the dressing <NUM> is used with and/or is part of an NPWT system <NUM>. As shown in <FIG>, the closure dressing <NUM> includes a track pad <NUM> and tubing that is structured to fluidly couple the dressing <NUM> to a negative pressure source <NUM> (e.g., a vacuum pump, etc.) to communicate negative pressure to the wound site <NUM> through the closure dressing <NUM>. The track pad <NUM> is coupled to an upper cover <NUM> of the dressing <NUM>, at an intermediate position (e.g., central position, etc.) along the upper cover <NUM>. The track pad <NUM> includes an airtight connection mechanism that fluidly connects a patient facing side of the upper cover <NUM> to the tubing. The NPWT system <NUM> may further include a canister, disposed between the negative pressure source <NUM> and the track pad <NUM> to capture any fluid (e.g., wound exudate, antiseptic, instillation fluid, etc.) that is pulled away from the wound site <NUM>. In other embodiments, the dressing <NUM> may be used independently from the NPWT system <NUM>, as a standalone wound dressing.

As shown in <FIG>, the closure dressing <NUM> includes a patient interface layer <NUM>, a touch fastener <NUM>, and the upper cover <NUM>. The touch fastener <NUM> includes a first fastening layer <NUM> and a second fastening layer <NUM>. In other embodiments, the dressing <NUM> may include additional, fewer, and/or different layers. <FIG> shows an exploded view of the dressing <NUM>. As shown in <FIG>, an outer surface <NUM> (e.g., wound facing surface, etc.) the patient interface layer <NUM> is bonded (e.g., adhered) or otherwise coupled to the wound site <NUM> (e.g., the periwound tissue, skin surrounding the wound, etc.). An inner surface <NUM> of the patient interface layer <NUM> is bonded or otherwise coupled to first fastening layer <NUM>. The patient interface layer <NUM> may be permanently affixed to the first fastening layer <NUM> such that the first fastening layer <NUM> cannot be removed without damaging the patient interface layer <NUM>. For example, the first fastening layer <NUM> may be bonded to the patient interface layer <NUM> using glue, epoxy, and/or another suitable adhesive product (e.g., a pressure sensitive adhesive, etc.). In another embodiment, the first fastening layer <NUM> may be laminated to the patient interface layer <NUM>. Similarly, the second fastening layer <NUM> is bonded or otherwise coupled to a first side <NUM> (e.g., inner side, inner surface, wound-facing surface, etc.) of the upper cover <NUM> and may be permanently affixed to the upper cover <NUM>.

As shown in <FIG>, the first fastening layer <NUM> and the second fastening layer <NUM> are "sandwiched" or otherwise disposed in between the patient interface layer <NUM> and the upper cover <NUM>, or other components of the dressing. As shown in <FIG>, the first fastening layer <NUM> and the second fastening layer <NUM> extend along all the sides of the dressing <NUM> and extend along a perimeter of an opening <NUM> in the patient interface layer <NUM>. In the embodiment of <FIG>, the first fastening layer <NUM> and the second fastening layer <NUM> circumscribe the opening <NUM> in the patient interface layer <NUM>. In other embodiments, the first fastening layer <NUM> and the second fastening layer <NUM> are disposed along only a portion of the perimeter of the opening <NUM> (e.g., along only two sides of the closure dressing <NUM>, three sides, etc.).

The patient interface layer <NUM> is configured to engage with a patient's skin or tissue in the area surrounding the wound and to form a substantially airtight seal between the wound site <NUM> and the external environment. As shown in <FIG>, the outer surface <NUM> of the patient interface layer <NUM> is bonded to and sealingly engaged with the wound site <NUM>. The inner surface <NUM> of the patient interface layer <NUM> is coupled to the first side <NUM> of the upper cover. The patient interface layer <NUM> may be made from a polymer film (e.g., a polyurethane film), a medical textile (e.g., Asahi nylon), and/or another suitable material. The patient interface layer <NUM> may include a suitable low tack adhesive (e.g., silicone or polyurethane gel) to facilitate bonding with the tissue at the wound site <NUM> (or surrounding the wound site <NUM>). The adhesive may be applied to the outer surface <NUM> of the patient interface layer <NUM> proximate to an outer perimeter of the patient interface layer <NUM>, and/or at any other suitable location along the outer surface <NUM>. In some embodiments, the adhesive may be distributed evenly across the outer surface <NUM>. In other embodiments, the patient interface layer <NUM> is a double-sided adhesive layer that includes a pressure sensitive adhesive on both the inner surface <NUM> and the outer surface <NUM>.

In some embodiments, the patient interface layer <NUM> may be substantially the same shape and have the same area as the upper cover <NUM>. As shown in <FIG>, the patient interface layer <NUM> defines an opening <NUM> that is disposed centrally along the patient interface layer <NUM> (e.g., a central position, in the middle of the patient interface layer <NUM>, etc.). The opening <NUM> provides fluid communication between the wound site <NUM> (e.g., wound) and an absorbent material in the upper cover <NUM>. In other embodiments, the patient interface layer <NUM> includes a plurality of openings extending across the patient interface layer <NUM>. It will be appreciated that the size, shape, and number of openings may be different in various alternative embodiments.

The upper cover <NUM> (e.g., top cover, etc.) substantially encloses the area above the wound site <NUM> and provides a fluid connection between the NPWT system (e.g., vacuum pump) and the wound site <NUM>. As shown in <FIG>, the upper cover <NUM> includes a drape <NUM>, a track pad <NUM> (e.g., a negative pressure interface, etc.), and an absorbent material <NUM>. The drape <NUM> defines a recessed area <NUM> (e.g., pocket, cavity, etc.) at a central position along the drape <NUM> that is sized to receive the absorbent material <NUM> therein. The track pad <NUM> is coupled to the drape <NUM> at the recessed area <NUM> and provides the fluid connection between the drape <NUM> and the tubing for the NPWT system. The drape <NUM> may be a Tagaderm™ layer (e.g., a transparent or partially transparent medical dressing) made from a thin high moisture vapor transmission rate (MVTR) adhesive coated polyurethane film such as Inspire <NUM>/<NUM> or another polyurethane or polyethylene film. The drape <NUM> may be at least partially coated in adhesive, for example, on the wound-facing side of the drape <NUM> (e.g., the first side <NUM> of the upper cover <NUM>), in order to bond the drape <NUM> to the second fastening layer <NUM> and/or the absorbent material <NUM>.

As shown in <FIG>, the absorbent material <NUM> (e.g., layer, sheet, etc.) is disposed within the recessed area <NUM> and coupled to the wound facing side of the drape <NUM>. The absorbent material <NUM> is configured to absorb wound exudate and/or other fluids (e.g., instillation fluids, antiseptics, etc.) and remove them from the wound site <NUM>. In at least one embodiment, the absorbent material <NUM> is made from a superabsorbent laminate such as may be commercially available from Gelok. In other embodiments, the absorbent material <NUM> includes a printed absorbent polymer.

In some embodiments, the absorbent material <NUM> may be formed from or otherwise include a superabsorbent polymer in the form of granules. The superabsorbent polymer may include Luquasorb <NUM> or <NUM>, such as may be commercially available from BASF. The granules may be contained in a water-soluble carrier polymer. One example of the water-soluble carrier polymer is polyvinylpyrrolidone (PVP). The superabsorbent polymer and the water-soluble polymer may be formed into a slurry or a suspension using an organic solvent. The organic solvent may include propanone or propanol and may aid in delivery of the absorbent material <NUM> to the drape <NUM> or another carrier (e.g., an absorbent foam manifold disposed within the recessed area <NUM>). In some embodiments, to increase the softness of the superabsorbent granules, a plasticizer may be added to the slurry. In one embodiment, the plasticizer may be water. In some embodiments, the slurry to form the absorbent material <NUM> may have a formulation of <NUM> parts by mass of PVP, <NUM> parts by mass of a superabsorbent polymer, <NUM> part by mass of glycerol, and <NUM> parts by mass of propanone. In some embodiments, to plasticize the granules, <NUM> part to <NUM> parts by mass of water may be added to the slurry mixture. In other embodiments, a water-soluble polymer superabsorbent precursor, such as acrylic acid or <NUM>-acrylamido-<NUM>-methyl-propanesulfonic acid (AMPS), with suitable UV curing additives, may replace the superabsorbent polymer. Such a precursor may be a relatively low viscosity solution and can be printed onto at least one of the drape <NUM> or a separate carrier and exposed to UV light to form a soft gel, eliminating the need for a plasticizer. In some embodiments, the water-soluble polymer superabsorbent precursor may be similar to that used for preparing hydrogel coatings.

By way of example, the slurry mixture may be applied to the wound-facing side of the drape <NUM> to form an absorbent layer. In some embodiments, the slurry may be applied to the drape <NUM> through standard printing methods, such as silk screen printing, gravure printing, or by x-y plotter printing. The absorbent layer may be applied in a variety of different shapes such as circles, squares, hexagons, hoops/halos, stars, crosses, a range of lines, or any combination of shapes. The absorbent layer may be substantially evenly distributed on the drape <NUM> within the recessed area <NUM>. In some embodiments, the absorbent material <NUM> may include a flexible plasticized hydrophilic polymer matrix having a substantially continuous internal structure. In some embodiments, the absorbent material <NUM> may include a combination of different materials.

The touch fastener <NUM> is disposed between the patient interface layer <NUM> and the upper cover <NUM> and is configured to detachably couple the patient interface layer <NUM> to the upper cover <NUM>. The touch fastener <NUM> is structured to form a substantially airtight and liquid tight seal between the patient interface layer <NUM> and the upper cover <NUM>. In the embodiments of <FIG>, the touch fastener <NUM> includes a first fastening layer <NUM> and a second fastening layer <NUM> that are structured to releasably and resealably couple the upper cover <NUM> (e.g., drape <NUM>) to the patient interface layer <NUM>.

As shown in <FIG>, the first fastening layer <NUM> and the second fastening layer <NUM> each include a plurality of lineal fastening strips that extend along the sides of the dressing <NUM> and circumscribe the opening <NUM> in the patient interface layer <NUM>. The fastening strips of the first fastening layer <NUM> are substantially aligned with the fastening strips of the second fastening layer <NUM>. In the embodiment of <FIG>, the first fastening layer <NUM> and the second fastening layer <NUM> each includes four fastening strips to encompass all four sides of the opening <NUM>. In other embodiments, the shape, position, and/or number of fastening strips may be different.

In at least one embodiment, first fastening layer <NUM> and the second fastening layer <NUM> each include a pair of fastening strips that extend along a longest dimension of the opening <NUM>. For example, as shown in <FIG>, the first fastening layer <NUM> may include only two fastening strips, including a first fastening strip <NUM> extending along a first side <NUM> of the opening <NUM>, and a second fastening strip <NUM> positioned on a second side <NUM> of the opening <NUM> that is opposite from the first side <NUM>. The first fastening strip <NUM> and the second fastening strip <NUM> may be substantially parallel to one another and may be oriented in a direction that is substantially parallel to a longest dimension of the opening <NUM> and/or a longest dimension of the patient interface layer <NUM>. In this implementation, a thick gel adhesive may be applied to the patient interface layer <NUM> and/or drape <NUM>, along gaps formed between the ends of the first fastening strip <NUM> and the second fastening strip <NUM>. The gel adhesive or other bonding agent is configured to be repositionable and replaceable. In other words, the gel adhesive may be tacky and may be pushed to other locations along the patient interface layer <NUM> and/or pulled away from the patient interface layer <NUM> without damaging the patient interface layer <NUM>. According to an illustrative embodiment, the gel adhesive is a hydrogel having a water activity within a range between approximately <NUM> and <NUM>, a solution uptake within a range between approximately <NUM>% and <NUM>%, a tack force within a range between approximately <NUM> and <NUM>, and a coat weight within a range between approximately, <NUM>/m2 and <NUM>/m2. In other embodiments, the properties of the hydrogel may be different. In another embodiment, the gel adhesive may include a silicone adhesive, DermaTac™ (e.g., a silicone and/or acrylic hybrid drape), and/or a hydrophilic gel adhesive, or another suitably tacky adhesive. Among other benefits, using a gel adhesive or other bonding agent in combination with the fastening strips (e.g., on a short end of the dressing <NUM>) reduces the force required to separate (e.g., peel back, remove, etc.) the upper cover <NUM> from the patient interface layer <NUM>. The arrangement of fastening strips and gel adhesive may differ in various alternative embodiments. For example, the fastening strips may be used on three sides of the opening <NUM> in the patient interface layer <NUM> and the gel adhesive may be using on the fourth, open side.

The touch fastener <NUM> may be any type of selectively resealable and reclosable mechanical interlock that can provide a substantially airtight and liquid tight seal between the upper cover <NUM> and the patient interface layer <NUM>. For example, the touch fastener <NUM> may be a Velcro-style hook and loop fastener that includes (i) a male fastening strip and (ii) a female fastening strip that is structured to couple to the male fastening strip in response to an applied pressure between the male fastening strip and the female fastening strip. For example, in the embodiment of <FIG>, the second fastening layer <NUM> may include at least one male fastening strip that is engageable with a female fastening strip of the first fastening layer <NUM> by pressing the male fastening strip into the female fastening strip, such that at least a portion of the male fastening strip extends into (e.g., protrudes into, is received within, etc.) the female fastening strip.

<FIG> shows a close up view of the joint that is formed between an upper fastening strip <NUM> of the first fastening layer <NUM> and a lower fastening strip <NUM> of the second fastening layer <NUM>, according to an illustrative embodiment. As shown, upper fastening strip <NUM> and the lower fastening strip <NUM> are the same and/or have a substantially similar structure. In other embodiments, the structure of the upper fastening strip <NUM> and/or the lower fastening strip <NUM> may be different. In the embodiment of <FIG>, the lower fastening strip <NUM> includes a base wall <NUM> having a first, outer surface <NUM>, and a second, inner surface <NUM>. The lower fastening strip <NUM> also includes a plurality of stems <NUM> (e.g., rails, protrusions, etc.) coupled to the base wall <NUM> along the first surface <NUM> and extending outwardly from (e.g., away from) the first surface <NUM> toward the upper fastening strip <NUM>. Each stem <NUM> extends laterally across the first surface <NUM>, between opposing sides of the lower fastening strip <NUM>. In the embodiment of <FIG>, the stems <NUM> are spaced in approximately equal intervals along a longitudinal direction (e.g., perpendicular to the lateral direction) between opposing ends of the lower fastening strip <NUM>. In other embodiments, the number and arrangement of stems <NUM> may be different.

In some embodiments, the lower fastening strip <NUM> and/or upper fastening strip <NUM> include a hook portion (e.g., flange, ledge, etc.) coupled to an outer, free end of each stem <NUM>. For example, as shown in <FIG>, each stem <NUM> includes shoulder portions <NUM> (e.g., shoulders, etc.) extending outwardly from an upper end of the stem <NUM> at an oblique angle relative to a central axis of the stem <NUM>. The shoulder portions <NUM> extend away from an upper end of the stem <NUM> in an at least partially longitudinal direction toward the space between adjacent stems <NUM>. In other embodiments, the shape and/or position of the hook portion of the stem <NUM> may be different. For example, <FIG> show an example lower fastening strip <NUM> that includes stems <NUM> having an outer hook portion <NUM> that extends in a substantially perpendicular direction relative to the body of each stem <NUM> (e.g., substantially parallel to the first surface <NUM>). Together, the stem <NUM> and the hook portion <NUM> form a substantially "T" shaped protrusion that is structured to engage and interlock with the "T" shaped protrusions of an upper fastening strip <NUM>. In other words, the combination of the stems <NUM> and hook portion <NUM> provide a direct mechanical connection between the lower fastening strip <NUM> and the upper fastening strip <NUM>. In other embodiments, the shape of the hook portion may be different. As shown in <FIG>, pressing the upper fastening strip <NUM> into the lower fastening strip <NUM> (e.g., against the lower fastening strip <NUM>) engages the stems <NUM> with the spaces formed between adjacent ones of the stems <NUM> in the upper fastening strip <NUM>. The hooked portions of the lower fastening strip <NUM> interlock the hooked portions of the upper fastening strip <NUM>. According to an illustrative embodiment, the stems <NUM> are formed onto the fastening strips using a micro-profile extrusion process from a flexible plastic material such as polyethylene or another suitable plastic.

In at least one embodiment, the first fastening layer <NUM> and/or the second fastening layer <NUM> is a hybrid closure that includes both a non-adhesive-based mechanical fastener (e.g., stems <NUM>) and an adhesive material interposed between adjacent mechanical fastener portions. As shown in <FIG>, the lower fastening strip <NUM> and the upper fastening strip <NUM> each include an adhesive <NUM> or other bonding agent disposed on the base wall <NUM>, within valleys between adjacent ones of the stems <NUM>. The adhesive <NUM> is positioned to engage with an outer end surface <NUM> of a respective one of the stems from an opposing fastening strip, which helps to distribute the adhesive <NUM> and provides a more robust seal between the upper fastening strip <NUM> and the lower fastening strip <NUM>. In other embodiments, the adhesive <NUM> may be applied to different areas of the fastening strips. The adhesive <NUM> may be a pressure sensitive adhesive material and/or another suitable adhesive product (e.g., silicone, polyurethane gel, etc.).

Among other benefits, the touch fastener <NUM> structure provides a resealable and reclosable connection between the patient interface layer <NUM> and the upper cover <NUM> (see <FIG>). As shown in <FIG>, the touch fastener <NUM> is structured such that the upper fastening strip <NUM> can be pulled apart from (e.g., uncoupled from) the lower fastening strip <NUM> by peeling back one end of the upper fastening strip <NUM>. This causes the stems <NUM> to pull away from the adhesive material and past the mechanical interlock formed by the hooked portion of the stems <NUM>.

<FIG> show another example embodiment of a negative pressure wound dressing <NUM> with a selective viewing access and reclosure system in various states of use. As shown in <FIG>, the dressing <NUM> may be provided to a clinician and/or other user as a single unitary structure, with the touch fastener <NUM> pre-applied in between the upper cover <NUM> and the patient interface layer <NUM>. Among other benefits, preassembly of the dressing <NUM> ensures proper alignment between the upper fastening strips and the lower fastening strips, and the most robust connection between adjacent dressing layers.

To apply the dressing <NUM> to a patient, a clinician or other user simply removes a backing layer from an outer surface of the patient interface layer <NUM> and applies the exposed surface of the patient interface layer <NUM> to the tissue. The negative pressure source may then be activated to reduce the pressure in the space above the wound site, in between the wound and the upper cover <NUM>, which compresses the absorbent layer. As shown in <FIG>, when examination of the wound site is required, the clinician can stop the NPWT therapy (e.g., can deactivate the negative pressure source, decouple the pressure source from the dressing <NUM>, etc.) and begin peeling back the upper cover <NUM> (e.g., drape <NUM>) from one end of the dressing <NUM> (e.g., the short end as shown in <FIG>). In the embodiment shown, the short end of the upper cover <NUM> is secured to the patient interface layer <NUM> using a thick gel adhesive product <NUM>. The long ends of the upper cover <NUM> are secured to the patient interface layer <NUM> using the touch fastener <NUM>. In other embodiments, the touch fastener <NUM> may be used without the gel adhesive, by positioning additional sections of the touch fastener <NUM> to the short ends of the upper cover <NUM> and patient interface layer <NUM>.

As shown in <FIG>, after inspecting the wound site, the clinician can reattach the upper cover <NUM> to the patient interface layer <NUM> by aligning the fastening strips of both the first fastening layer <NUM> and the second fastening layer <NUM>. The clinician may then press down on the upper cover <NUM> to engage the fastening strips of each fastening layer and to thereby engage the mechanical connection of the fastening strips. Finally, the clinician may secure the short end of the upper cover <NUM> by pressing the short end of the upper cover <NUM> into the thick gel adhesive on the patient interface layer <NUM>, before restarting the NPWT therapy (e.g., activating the negative pressure source), as shown in <FIG>.

Referring to <FIG>, a flow diagram of a method <NUM> of making a resealable and reclosable dressing is shown, according to an illustrative embodiment. The method <NUM> includes providing a patient interface layer such as a thin film layer, at operation <NUM>. Operation <NUM> may further includes cutting an opening (e.g., hole) in the patient interface layer, at a central position along the patient interface layer. Operation <NUM> may further include applying an adhesive product (e.g., a pressure sensitive adhesive) to at least one side of the patient interface layer.

In operation <NUM>, a first fastening layer is joined to the patient interface layer. Operation <NUM> may include providing the first fastening layer; for example, by providing a plurality of fastening strips, and applying an adhesive product to a backing of the fastening strips and/or to select areas of the patient interface layer (e.g., along a perimeter of the opening). Operation <NUM> may further include applying the fastening strips of the first fastening layer to the patient interface layer. In at least one embodiment, operation <NUM> includes applying fastening strips on each side of the opening.

In other embodiments, operation <NUM> includes applying the fastening strips along only a portion of the perimeter of the opening. For example, operation <NUM> may include positioning a first fastening strip of the first fastening layer along a direction that is substantially parallel to a longest dimension of the opening and adhering the first fastening strip to the patient interface layer on a first side of the opening. Operation <NUM> may further include adhering a second fastening strip to a second side of the opening opposite from the first side. Operation <NUM> may additionally include applying a gel adhesive to the patient interface layer to substantially fill a gap between the first fastening strip and the second fastening strip (e.g., between ends of the first fastening strip and the second fastening strip, such that the fastening strips and gel adhesive together circumscribe the opening).

In operation <NUM>, an upper cover is provided that is sized to cover the opening. Operation <NUM> may include cutting a drape made from Tagaderm™ or another thin film layer to substantially match the size of the patient interface layer. Operation <NUM> may further include forming a recessed area into the drape using a press operation and/or a heat treating operation. Operation <NUM> may additionally include placing an absorbent material into the recessed area and/or adhering the absorbent material to the drape using an adhesive material. Operation <NUM> may also include incorporating a negative pressure coupling (e.g., track pad, etc.) into the drape.

In operation <NUM>, a second fastening layer is joined to the upper cover. Operation <NUM> may include providing the second fastening layer; for example, by providing a plurality of fastening strips, and applying an adhesive product to a backing of the fastening strips and/or to select areas of the drape that are aligned with the first fastening layer. Operation <NUM> may further include applying (e.g., adhering) the fastening strips of the second fastening layer to the drape.

Claim 1:
A negative pressure wound dressing with a selective viewing access and reclosure system, comprising:
a patient interface layer (<NUM>) defining an opening (<NUM>) configured for placement about a patient area of treatment;
a top layer (<NUM>) sized to cover the opening (<NUM>) and comprising a negative pressure interface (<NUM>);
a touch fastener (<NUM>) disposed between the patient interface layer (<NUM>) and the top layer (<NUM>), the touch fastener (<NUM>) configured to detachably couple the patient interface layer (<NUM>) to the top layer (<NUM>) and form a substantially airtight seal between the patient interface layer (<NUM>) and the top layer (<NUM>); and
a negative pressure source (<NUM>) coupled to the negative pressure interface (<NUM>) on the top layer (<NUM>).