WO2021070049A1

WO2021070049A1 - Low-profile superabsorbent dressing

Info

Publication number: WO2021070049A1
Application number: PCT/IB2020/059371
Authority: WO
Inventors: Timothy Mark Robinson; Christopher Brian Locke
Original assignee: Kci Licensing, Inc.
Priority date: 2019-10-08
Filing date: 2020-10-06
Publication date: 2021-04-15

Abstract

A dressing includes a foam layer including a non-patient-facing surface. The non-patient-facing surface includes a plurality of depressions therein. A plurality of superabsorbent deposits is positioned in the plurality of depressions.

Description

LOW-PROFILE SUPERABSORBENT DRESSING

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims the benefit of priority to U.S. Provisional Application No. 62/912,233, filed on October 8, 2019, which is incorporated herein by reference in its entirety.

BACKGROUND

[0002] The present disclosure relates to dressings for treating wounds. Many wounds exude fluid (e.g., blood, pus, etc.). Dressings for such wounds may include absorbent materials or other features that attempt to manage the fluid, for example with the goal of absorbing all fluid from a wound.

[0002] Conventional absorbent dressings are bulky, which may create difficulty in applying the dressings and inconvenience for patients. To address these issues, some dressings may include superabsorbent materials which swell when absorbing fluid. However, the swelling of the superabsorbent material may cause a change in shape of the dressing, which may be visually unattractive and/or uncomfortable for patients. In some cases, the superabsorbent material may be prevented from swelling to absorb a maximum capacity of fluid by other structures in the dressing. Accordingly, a need exists for a flexible, conformable, non-bulky, high-fluid-capacity dressing for wound treatment.

SUMMARY

[0003] One embodiment of the present disclosure is a dressing. The dressing includes a foam layer including anon-patient-facing surface. The non-patient-facing surface includes a plurality of depressions therein. A plurality of superabsorbent deposits is positioned in the plurality of depressions.

[0004] In some embodiments, the dressing includes a polyurethane drape layer coupled to the foam layer. The plurality of superabsorbent deposits are positioned between the foam layer and the polyurethane drape layer. The dressing may also include a perforated fdm layer coupled to the foam layer with the foam layer positioned between the perforated film layer and the superabsorbent deposits.

[0005] In some embodiments, a first superabsorbent deposit of the plurality of superabsorbent deposits is positioned in a first depression of the plurality of depressions and a volume of the first depression is greater than a volume of the first superabsorbent deposit when the first superabsorbent deposit is dry. The volume of the first depression may be approximately equal to the volume of the first superabsorbent deposit when the first superabsorbent deposit absorbs an amount of fluid. [0006] In some embodiments, each of the plurality of depressions has a hemispherical shape. The depression may be arranged in an array. In some embodiments, the plurality of depressions are formed as a plurality of channels. The depressions may be extend in parallel directions along the dressing.

[0007] In some embodiments, the perforated film layer includes polyvinylidene diflouoride. In some embodiments, the perorated film layer has a thickness of approximately 125 microns and includes a plurality of perforations having diameters in a range between approximately 0.1 microns and approximately 0.2 microns. In some embodiments, the foam material includes an open-cell hydrophilic foam. In some embodiments, the superabsorbent deposits include at least one of acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, sodium polyacrylate, polyacrylamide copolymer, ethylene maleic anhydride copolymer, cross-linked carboxymethylcellulose, polyvinyl alcohol copolymers or cross-linked polyethylene oxide.

[0008] Another implementation of the present disclosure is a method. The method includes providing a mixture into a mold. The mold includes a plurality of protrusions. The mixture is configured to form into a foam material in the mold as a result of a chemical reaction. The method includes removing the foam material from the mold, with the foam material formed to include a plurality of depressions corresponding to the plurality of protrusions of the mold, and depositing a superabsorbent material in the plurality of depressions.

[0010] The protrusions may be hemispherically-shaped and/or include a plurality of ridges. In some embodiments, depositing the superabsorbent material in the plurality of depressions comprises filling the plurality of depressions with the superabsorbent material. In some embodiments, a volume of the superabsorbent material is less than a volume of the plurality of depressions when the superabsorbent material is dry.

[0011] In some embodiments, the method also includes coupling a drape to the mold such that the superabsorbent material is between the foam material and the drape. The method may include coupling the drape to a tube coupleable to a pump with the tube fluidly communicable with the foam material. The method may also include providing an adhesive around a perimeter of the drape. The adhesive is configured to adhere to skin.

[0012] In some embodiments, the method includes coupling the foam material to a perforated film. In some embodiments, the method includes providing a support structure in the mold. The foam may be configured to bond to the support structure as a result of the chemical reaction. The foam material may include a hydrophilic open-celled foam. [0013] Another implementation of the present disclosure is a dressing. The dressing includes a foam that includes a depression in a first surface of the foam material, a superabsorbent deposit positioned in the depression, and an outer film layer coupled to the foam such that the superabsorbent deposit is between the foam and the outer film layer.

[0014] The outer film layer may be configured to allow evaporation through the outer film layer. The foam may be configured to contact a wound of a patient. In some embodiments, the dressing includes a perforated film coupled to the foam, the foam is positioned between the perforated film and the superabsorbent deposit, and the perforated film layer is configured to contact a wound of a patient.

[0015] In some embodiments, the dressing includes a thermo-formed support configured to resist deformation of the depression.

[0016] Another implementation of the present disclosure is a negative pressure wound therapy system. The system includes a pump, a tube coupled to the pump, and a dressing coupled to the tube. The dressing includes a foam layer having a non-patient-facing surface. The non-patient-facing surface includes a plurality of depressions therein. A plurality of superabsorbent deposits are positioned in the plurality of depressions.

[0017] In some embodiments, the dressing includes a drape coupled to the foam layer such that the plurality of superabsorbent deposits positioned are positioned between the foam layer and the drape.

In some embodiments, a connection pad is coupled to the drape and to the tube. The connection pad may be configured to place the foam layer in pneumatic communication with the tube.

[0018] In some embodiments, the dressing includes a perforated film coupled to the foam layer.

The foam layer is positioned between the perforated film and the superabsorbent deposits.

[0019] In some embodiments, a first superabsorbent deposit of the plurality of superabsorbent deposits is positioned in a first depression of the plurality of depressions. A volume of the first depression may be greater than a volume of the first superabsorbent deposit when the first superabsorbent deposit is dry. In some embodiments, the volume of the first depression is approximately equal to the volume of the first superabsorbent deposit when the first superabsorbent deposit absorbs an amount of fluid.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG. 1 is a cross-sectional side view of a dressing, according to an exemplary embodiment.

[0021] FIG. 2 is a cross-sectional side view of a variation of the dressing of FIG. 1, according to an exemplary embodiment. [0022] FIG. 3 is a cross-sectional side view of the dressing of FIG. 1 used with a negative pressure therapy system, according to an exemplary embodiment.

[0023] FIG. 4 is a top view of the dressing of FIG. 1, according to an exemplary embodiment.

[0024] FIG. 5 is a top view of the dressing of FIG. 1, according to an exemplary embodiment.

[0025] FIG. 6 is a flowchart of a process of manufacturing the dressing of FIG. 1, according to an exemplary embodiment.

DETAILED DESCRIPTION

[0026] Referring now to FIG. 1, a dressing 100 is shown, according to an exemplary embodiment. The dressing 100 includes a foam layer 102 having a patient-facing surface 104 and a non-patient facing surface 106, a perforated fdm layer 108 positioned along the patient-facing surface 104 of the foam layer 102, an outer film layer (shown as drape 110) positioned along the non-patient facing surface 106 of the foam layer 102, and multiple superabsorbent deposits 112 positioned between the drape 110 and the non-patient facing surface 106 of the foam layer 102. The dressing 100 is configured to be positioned over a wound of a patient, to draw fluid exuded by the wound across the perforated film layer 108 and the foam layer 102 to the superabsorbent deposits 112, to absorb and store the fluid at the superabsorbent deposits 112, and, in some embodiments, to allow the fluid to evaporate from the superabsorbent deposits 112 to the ambient air through the drape 110.

[0027] The perforated film layer 108 may be a hydrophilic membrane, for example a highly hydrophilic membrane. The perforated film layer 108 may include a microporous film, for example made of polyvinylidene difluoride (PVdF) and, in some embodiments, treated to be hydrophilic. The perforated film layer 108 may include perforations that are large enough to draw water molecules through the perforated film layer 108 while also small enough to prevent ingrowth of healing tissue to the dressing 100. For example, the perforations may be between approximately 0.1 microns and 0.2 microns in diameter. The perforated film layer 108 may have a thickness of approximately 125 microns. In various embodiments, the perforated film layer 108 may include a 0.45-micron-pore-size nylon membrane sold under the tradename Magna™ by GVS, a PVdF 0.22 -micron-pore-size membrane sold under the tradename Durapore® by Merck, or a 0.7-micron-pore-size GF/F grade glass microfiber sold under the tradename Whatman® by GE Healthcare Life Sciences. The perforated film layer 108 may be made of a material having a low moisture vapor transmission rate (MVTR), for example less than approximately 250g/m²/day, or having a high MVTR, for example greater than approximately 250g/m²/day (e.g., a hydrophilic polyurethane). The perforations increase the MVTR of the perforated film layer 108 to have a high MVTR (e.g., greater than approximately 250g/m²/day) and typically a very high MVTR (e.g., greater than approximately 1000g/m²/day (upright cup method).

[0028] The perforated fdm layer 108 may also substantially prevent bacteria from passing therethrough in either direction. In some embodiments, a wound-facing side of the perforated fdm layer 108 may be coated (provided) with an antibacterial substance such as charcoal to neutralize bacteria at the perforated fdm layer 108. In some embodiments, the perforated fdm layer 108 is formed as an integral skin on the foam layer 102 (e.g., formed between a mold and the foam during casting of the foam).

[0029] Although the perforated fdm layer 108 is shown as included with the dressing 100 in FIG. 1, in other embodiments the perforated fdm layer 108 may be omitted from the dressing 100.

[0030] The foam layer 102 may be polyurethane foam, for example a hydrophilic polyurethane foam. In some embodiments, the foam layer has a thickness in a range of approximately two millimeters to approximately three millimeters. The foam layer 102 may include an open-celled hydrophilic foam, an open-celled hydrophobic foam, or a closed-cell hydrophilic foam. In some embodiments, the free volume of the foam layer is less than approximately 50%. In some embodiments, the tensile strength of the foam layer is greater than approximately 40 kPa. In some embodiments, the foam layer 102 includes hydrophilic polymers such as poly- acrylics, esters, amides, and alcohols that contain polar groups such as hydroxyl, carboxylic, sulphonic acid and esters, amines and amides.

[0031] As shown in FIG. 1, the non-patient facing surface 106 (i.e., the top surface in the orientation of FIG. 1) of the foam layer 102 includes multiple depressions 114 therein. That is, the foam layer 102 is reduced in thickness at multiple locations of the foam layer 102, such that concave regions (i.e., the depression 114) are formed on the non-patient facing surface 106. In the example shown, the depressions 114 have a depth of approximately one-third of a thickness of the foam layer 102. In other embodiments, various depths are possible to tailor the dressing 100 to provide various fluid handling dynamics (e.g., a depth of approximately one-half, two-thirds, etc. of the thickness of the foam layer 102).

[0032] The depressions 114 may each have a substantially hemispherical shape. In some embodiments, the depressions 114 are formed as channels (e.g., having a length longer than a width). Various shapes and combinations of various shapes are possible. FIGS. 4-5 illustrates two possible arrangements of the depressions 114, described in detail below.

[0033] In the examples shown herein, the depressions 114 are formed during a casting process for the foam layer 102 in which the foam layer 102 is formed in a mold. The mold includes multiple protrusions corresponding to the multiple depressions 114. The foam layer 102 may be formed by inserting a mixture into the mold, where the mixture (e.g., a liquid) is configured to undergo a chemical reaction to form the foam material of the foam layer 102. As the mixture transforms into the foam layer 102, the foam layer 102 takes the shape of a space within the mold, i.e., such that protrusions of the mold create depression in the foam layer 102. In some embodiments, the protrusions are positioned only one side of the mold, and the foam layer 102 is cast direction into the cross-sectional shape shown in FIG. 1. In other embodiments, the protrusions are positioned on two opposing sides of the mold, such that the foam is cast and then sliced in half (along a width of the foam) to create the foam layer 102 with the cross-sectional shape shown in FIG. 1.

[0034] As shown in FIG. 1, superabsorbent deposits 112 are positioned in the depressions 114. The superabsorbent deposits 112 may include one or more of various superabsorbent materials, for example acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, sodium polyacrylate (e.g., as sold under the tradename Luquasorb® 1161 by BASF), polyacrylamide copolymer, ethylene maleic anhydride copolymer, cross-linked carboxymethylcellulose, polyvinyl alcohol copolymers, cross- linked polyethylene oxide, etc. In some embodiments, the superabsorbent material is reduced to a fine powder and combined with a mix of water and isopropyl alcohol (IP A) to form a paste (e.g., with a superabsorbentwaterlPA ratio of approximately 1:15:6). The paste may take up to 60 minutes to fully form, and adjustments may be made by adding more IPA to reduce viscosity or adding more water to increase viscosity. The paste may be printed (deposited) in the depressions 114 to form the superabsorbent deposits 112, for example using a 3 -axis automated glue dispenser. In some cases, superabsorbent particles may be plasticized with water to soften the hard particles to a gel or paste which may be readily processed by the dispenser. In some cases, the paste is formed without a carrier polymer, which may increase the activity and concentration of the superabsorbent material. The isopropyl alcohol may act to modify the viscosity of the paste and act as a drying aid. In various embodiments, water-soluble organic solvents of different volatilities (e.g., ketones, ethers, esters) may be used in addition to or instead of IPA to control the drying rate of the superabsorbent deposits 112 and/or suppress swelling of the superabsorbent material to control/reduce paste viscosity.

[0035] In other embodiments, to form the superabsorbent deposits 112, the superabsorbent material(s) may be formed into a slurry and printed (deposited) on the perforated film layer 108. In some embodiments, the superabsorbent material(s) is formed into a slurry with polyethylene oxide (PEO) to bind the superabsorbent material(s) together. The PEO may be dissolved into a non-aqueous solvent, such as an alcohol (e.g., ethanol) or ketone (e.g., propanone) into which particles of the superabsorbent material(s) may be dispersed, which may vary the absorption or drying rate of the superabsorbent deposits 112. In some embodiments, another water-soluble or swelling carrier may be used instead of or in addition to PEO, for example pyrrolidone and polyvinyl alcohol. Various PEOs may be used to adjust hardness of the superabsorbent deposits 112. In some embodiments, a disintegrant may be added to the slurry or paste to enable a more rapid deployment and increase water absorption rates of the superabsorbent deposits 112. In some embodiments, activated carbon or other ion exchange additives may be added to the slurry or paste, which may increase the absorption capacity of the superabsorbent. In some embodiments, the superabsorbent deposits 112 may adhere to the foam layer 102 due to an adherent property of the slurry or paste (i.e., without an added binding agent that may slow absorption). For example, the superabsorbent material may partially penetrate the adjacent surface when swollen, such that when the superabsorbent material dries it remains locked or bonded to the adjacent surface(s)/substrate(s). In some embodiments, a binding agent is included.

[0036] The superabsorbent deposits 112 may thereby be positioned in the depression 114. In some embodiments, the superabsorbent deposits 112 have a volume that is less than a volume of the depressions 114 when the superabsorbent deposits 112 are dry. In such a case, an open volume is left in each depression 114 as the superabsorbent deposit 112 only occupies a portion of the depression 114. As the superabsorbent deposit 112 absorbs fluid, the superabsorbent deposit may increase in size to, at some amount of fluid absorption, match the size of the depression 114. That is, the superabsorbent deposit 112 swells substantially fill the depression 114 (e.g., as shown in FIG. 1).

The superabsorbent deposits 112 are thereby allowed to absorb fluid and swell without increasing a thickness of the dressing 100 and without protruding from or otherwise distorting an external surface of the dressing 100.

[0037] In some cases, the superabsorbent deposits 112 may also swell to a size larger than the volume of the depression 114, which may be achieved by stretching/deforming the drape 110 and/or compressing the foam layer 102.

[0038] Additionally, the superabsorbent deposits 112 are exposed to a relatively large surface area of the foam layer 102 when positioned in the depression 114 as to compare to being positioned on a flat (planar) surface of a foam material. For example, as shown in FIG. 1, the superabsorbent deposits 112 may be in contact with the foam material all but the top sides of the superabsorbent deposits 112. The increased surface area contact may facilitate an increased rate of fluid flow between the foam layer 102 and the superabsorbent deposits 112, thereby improving the fluid handling properties of the dressing 100. The increased surface area contact may also increase the reliability and strength of a bond between the superabsorbent deposits 112 and the foam layer 102 formed as the superabsorbent deposits 112 partially penetrate the surface of the depression 114, then dry to bond with the surface of the depression 114. This may reduce or eliminate a reason to include of a binding agent with the superabsorbent deposits 112. The lateral migration of the superabsorbent deposits 112 is substantially prevented by this increased bond and the geometry of the depression 114. When dry (e.g., substantially lacking of fluid), the deposits 112 are contracted (non-swollen) and contained in the depressions 114. The deposits 112 may remain dry during distribution and application until fluid from a wound is absorbed by the deposits 112.

[0039] The drape 110 is positioned over the depression 114 and confines the superabsorbent deposits 112 in the depression 114. The drape 110 may be made of a film having a high moisture vapor transfer rate (e.g., greater than approximately 250g/m²/day), thereby facilitating evaporation of fluid from the superabsorbent deposits 112 to the ambient air through the drape 110. The drape 110 may be adhered to the perforated film layer 108 (e.g., by an adhesive coated on the drape 110 and/or the perforated film layer 108), or heat bonded to the perforated film layer 108. In embodiments where the perforated film layer 108 is formed as an integral skin, the drape 110 is coupled to the foam layer 102 (e.g., heat bonded, adhered).

[0040] In some embodiments, the drape 110 is configured to stretch to allow the superabsorbent deposits 112 to expand towards the drape 110 (i.e., away from a wound) and to deform the drape 110 when the superabsorbent deposits 112 absorb fluid and expand beyond a volume of the depressions 114. The superabsorbent deposits 112 may thereby be allowed to expand to a substantially maximum size to substantially maximize the fluid capacity of the superabsorbent deposits 112. For example, the drape 110 may be made of a thermoplastic polyurethane, for example as sold under the trade name Elasthane™ by DSM or sold under the trade name Dureflex® by Covestro, or copolyamide or copolyester. The drape 110 may be between approximately 10 microns and 60 microns thick. The drape 110 may be coupled to the foam layer 102 by thermo-bonding or using an adhesive. The drape 110 thereby facilitates evaporation of fluid out of the dressing 100 while also preventing ingress of contaminants to the dressing 100 and the wound.

[0041] In some embodiments, the drape 110 includes an adhesive border configured to adhere to the skin of a patient to secure the dressing 100 over a wound. The dressing 100 may include acrylic adhesives with a bond strength greater than approximately 5N/25mm. The adhesive border may be configured to secure the dressing 100 to the patient for multiple days (e.g., seven days).

[0042] Referring now to FIG. 2, another embodiment of the dressing 100 is shown. In the embodiment of FIG. 2, the dressing 100 includes the foam layer 102, the drape 110, and the superabsorbent deposits 112 of FIG. 1. In the embodiment of FIG. 2, the perforated film layer 108 is omitted, and the foam layer 102 is configured to directly contact a wound (e.g., configured to prevent ingrowth of tissue to the foam layer 102, etc.).

[0043] In the example of FIG. 2, the dressing 100 includes a support structure 200. The support structure 200 is positioned between the foam layer 102 and the drape 110, the foam layer 102 positioned between the support structure 200 and the perforated film layer 108. The support structure 200 is configured to resist deformation of the depressions 114 (e.g., due to bending of the dressing, external forces on the dressing, internal forces caused by fluid handling, etc.), thereby preserving space for the superabsorbent deposits 112 in the depressions 114. The support structure may be a thermo-formed polyurethane, for example having a thickness of approximately 0.1 millimeters. In some embodiments, the support structure 200 is adhered to the foam layer 102. In some embodiments, the foam 102 is direct casted onto the support structure 200. The support structure 200 may be coupled to the drape 110 with an adhesive (e.g., an acrylic adhesive). In some embodiments, the support structure 200 is not directly adhered to the drape 110.

[0044] As shown in FIG. 2, the support structure 200 has openings aligned with the depression 114 and may extend downwards into the depression 114 (e.g., wells, tubes, etc. extending downwards into the depression 114). In some embodiments, the support structure 200 extends to a bottom end of each depressions 114, half-way along a depth of each depression, etc. The support structure 200 may thereby have protrusions corresponding to the shapes of the depressions 114 (and to the shape of protrusions of a mold use to form the foam layer 102), while having openings therethrough. The support structure 200 thereby allows the superabsorbent deposits 112 to expand towards the drape 110 and to fill the space defined by the depressions 114. The superabsorbent deposits can occupy space defined by the openings of the support structure 200. The support structure 200 may thereby provide an increased capacity for the dressing 100 and/or a more consistent capacity of dressings 100 applied across various anatomical features of various surface geometries. The support structure 200 may be flexible, with a Young’s modulus in a range between approximately 1 MPa and approximately 5 MPa.

[0045] Referring now to FIG. 3, another embodiment of the dressing 100 is shown, according to an exemplary embodiment. In the example of FIG. 3, the dressing 100 is included in negative pressure wound therapy (NPWT) system 300. The NPWT system 300 includes the dressing 100, a connection pad 302 coupled to the dressing 100, a tube 304 coupled to the connection pad 302, and a pump 306 coupled to the tube. The pump 306 is fluidly communicable with the dressing 100 via the tube 304 and the connection pad 302. The pump 306 is operable to remove air from the foam layer 102 via the connection pad 302 and the tube 304 to establish a negative pressure (relative to atmospheric pressure) at the foam layer 102. When the dressing 100 is coupled over a wound, a negative pressure can thereby be established at the wound which may facilitate wound healing.

[0046] The dressing 100 of the NPWT system 300 may also include various manifolding structures and other layers or components configured to facilitate airflow in the dressing 100 and the establishment and maintenance of a negative pressure at the wound. The dressing may include a silicone and acrylic adhesive border configured to provide a substantially airtight seal between the drape 110 and the patient’s skin. It should be understood that various additional layers, materials, structures may be included with dressing 100 while maintaining the advantages of the depressions 114 and the superabsorbent deposits 112 positioned therein.

[0047] Referring now to FIGS. 4-5, top views of dressings 100 are shown, according to exemplary embodiments. FIGS. 4 and 5 show two possible arrangements of the depressions 114 and the deposits 112 on the dressing 100. FIG. 4 shows the depressions 114 as multiple hemispherical recesses arranged in rows along the dressing 100, while FIG. 5 shows the depressions 114 as linear channels arranged along the dressing 100. For example, eight columns of four depression 114 are shown in FIG. 4, while FIG. 5 shows the depressions 114 formed as six linear channels. In other embodiments, other numbers of depressions 114 may be included (e.g., two, four, ten, twenty, forty, one-hundred, two-hundred, one thousand, etc.). The depressions 114 of FIGS. 4-5 may be reliably formed in a casting process, due to the smooth rounded edges of the depressions 114. The diameter of the depressions 114 may be in a range between approximately one millimeter and approximately three millimeters.

[0048] It should be understood that the embodiments of FIGS. 4-5 are shown for example purposes and that many variations on size, shape, placement, number, etc. of the depressions 114 and superabsorbent deposits 112 are possible. For example, the depressions 114 may be formed as polyhedrons, linear or curved channels, ring-shaped channels, etc., and combinations thereof. The depressions 114 and the superabsorbent deposits 112 may be arranged to guide fluid to desired areas of the dressing 100, to tailor conformability of the dressing (i.e., as the dressing may be more flexible in areas unoccupied by the superabsorbent material), and to adjust a fluid capacity of the dressing 100.

[0049] Referring now to FIG. 6, a flowchart of a process 600 for manufacturing the dressing 100 is shown, according to an exemplary embodiment. The process 600 can be adopted to provide for manufacture of the various embodiments of the dressing 100 described herein. In some embodiments, the dressing 100 is manufactured using a process other than process 600.

[0050] At step 602, a mold is provided. The mold has multiple protrusions along an interior surface of the mold. For example, the mold may include a box shape, where a lid or bottom of the box includes protrusions. The protrusions may be hemispherical, hemi-cylindrical, or other prisms, shapes, irregular forms, etc. in various embodiments. In some embodiments, a diameter, width, height, and/or other dimension of the protrusions is between approximately 1 mm and approximately 3 mm. The shape of an interior volume defined by the mold may thereby correspond to the shape of the foam layer 102 described above. The mold may be formed from polyethylene, stainless steel, and/or polytetrafluoroethylene. [0051] At step 604, a mixture is provided into the mold. The mixture (e.g., a liquid) may include one or more (e.g., two, three, four, etc.) chemicals configured to react to form the material of the foam layer 102, for example include chemicals that form the foam and a catalyst, for example through an exothermic reaction. In some embodiments, a release liner is provided in the mold to facilitate release of the foam from the mold. In some embodiments, the support structure 200 is provided in the mold with the mixture.

[0052] At step 606, a reaction is facilitated in which the mixture forms a foam having a shape defined by the mold. For example, the mold may be clamped, sealed, closed, etc. to allow the mixture to react and form a foam having a pore size, density, size, shape, etc. defined by the amount of the materials provided at step 604 and the shape/dimensions of the mold. In an embodiment where the support structure 200 is provided in the mold, the foam may bind to the support structure at step 200. Step 606 may include waiting for at least a predetermined duration of time to allow for completion of the reactions needed to form the foam.

[0053] At step 608, the foam is removed from the mold. In some embodiments, removal of the foam from the mold is aided by a release liner included between the foam and one or more surfaces of the mold. Step 608 may include trimming boundaries of the foam or other post-processing of the molded foam. A foam layer 102 as described in detail can thereby be produced, including depressions 114 as described above. The mold may be prepared for reuse (i.e., for another iteration of steps 602- 606).

[0054] At step 610, superabsorbent particles are deposited in depressions in the foam layer. The superabsorbent deposits 112 may include one or more of various superabsorbent materials, for example acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, sodium polyacrylate (e.g., as sold under the tradename Luquasorb® 1161 by BASF), polyacrylamide copolymer, ethylene maleic anhydride copolymer, cross-linked carboxymethylcellulose, polyvinyl alcohol copolymers, cross- linked polyethylene oxide, etc. In some embodiments, the superabsorbent material is reduced to a fine powder and combined with a mix of water and isopropyl alcohol (IP A) to form a paste (e.g., with a superabsorbentwaterlPA ratio of approximately 1:15:6). The paste may take up to 60 minutes to fully form, and adjustments may be made by adding more IPA to reduce viscosity or adding more water to increase viscosity. At step 610, the paste may be printed (deposited) in the depressions 114 to form the superabsorbent deposits 112, for example using a 3 -axis automated glue dispenser. In some cases, superabsorbent particles may be plasticized with water to soften the hard particles to a gel or paste which may be readily processed by the dispenser. In some cases, the paste is formed without a carrier polymer, which may increase the activity and concentration of the superabsorbent material. The isopropyl alcohol may act to modify the viscosity of the paste and act as a drying aid. In various embodiments, water-soluble organic solvents of different volatilities (e.g., ketones, ethers, esters) may be used in addition to or instead of IPA to control the drying rate of the superabsorbent deposits 112 and/or suppress swelling of the superabsorbent material to control/reduce paste viscosity.

[0055] In other embodiments, to form the superabsorbent deposits 112, the superabsorbent material(s) may be formed into a slurry and printed (deposited) on the perforated fdm layer 108. In some embodiments, the superabsorbent material(s) is formed into a slurry with polyethylene oxide (PEO) to bind the superabsorbent material(s) together. The PEO may be dissolved into a non-aqueous solvent, such as an alcohol (e.g., ethanol) or ketone (e.g., propanone) into which particles of the superabsorbent material(s) may be dispersed, which may vary the absorption or drying rate of the superabsorbent deposits 112. In some embodiments, another water-soluble or swelling carrier may be used instead of or in addition to PEO, for example pyrrolidone and polyvinyl alcohol. Various PEOs may be used to adjust hardness of the superabsorbent deposits 112. In some embodiments, a disintegrant may be added to the slurry or paste to enable a more rapid deployment and increase water absorption rates of the superabsorbent deposits 112. In some embodiments, activated carbon or other ion exchange additives may be added to the slurry or paste, which may increase the absorption capacity of the superabsorbent. In some embodiments, the superabsorbent deposits 112 may adhere to the foam layer 102 due to an adherent property of the slurry or paste (i.e., without an added binding agent that may slow absorption). For example, the superabsorbent material may partially penetrate the adjacent surface when swollen, such that when the superabsorbent material dries it remains locked or bonded to the adjacent surface(s)/substrate(s). In some embodiments, a binding agent is included.

[0056] In various embodiments, the superabsorbent particles are partially swollen during step 610, and may be added to the depressions to entirely fill the depressions or to partially fill the depressions (e.g., approximately three-quarters full, approximately one-half full, approximately one-quarter full, etc.). The superabsorbent particles may then dry over time and shrink as a result, thereby occupying less of the volume defined by depressions. The superabsorbent is thereby deposited in the depression of the foam layer at step 610.

[0057] At step 612, the foam (including the superabsorbent deposits) is coupled to a drape and/or to a perforated film layer or other wound contact layer, for example drape 110 and perforated film layer 108 described in detail above. The foam may be coupled to the drape and/or a perforated film layer using an adhesive (e.g., acrylic adhesive) or using heat bonding, radio-frequency welding, etc. In some embodiments, the drape and the wound contact layer are coupled together to form a pouch to contain the foam. In some embodiments, other components, layers, materials, etc. are added to the dressing at step 612. For example, in embodiments where the support structure is not added into the mold at step 604, the support structure may be coupled to the foam at step 612. The dressing 100 can thus be formed following process 600. In some embodiments, the process 600 also includes coupling the dressing 100 to a connection pad, tube, and/or pump to manufacture a NPWT system, for example as shown in FIG. 3.

[0058] As utilized herein, the terms “approximately,” “about,” “substantially”, and similar terms are intended to have a broad meaning in harmony with the common and accepted usage by those of ordinary skill in the art to which the subject matter of this disclosure pertains. It should be understood by those of skill in the art who review this disclosure that these terms are intended to allow a description of certain features described and claimed without restricting the scope of these features to the precise numerical ranges provided. Accordingly, these terms should be interpreted as indicating that insubstantial or inconsequential modifications or alterations of the subject matter described and claimed are considered to be within the scope of the disclosure as recited in the appended claims.

[0059] It should be noted that the term “exemplary” and variations thereof, as used herein to describe various embodiments, are intended to indicate that such embodiments are possible examples, representations, or illustrations of possible embodiments (and such terms are not intended to connote that such embodiments are necessarily extraordinary or superlative examples).

[0060] The term “coupled” and variations thereof, as used herein, means the joining of two members directly or indirectly to one another. Such joining may be stationary (e.g., permanent or fixed) or moveable (e.g., removable or releasable). Such joining may be achieved with the two members coupled directly to each other, with the two members coupled to each other using a separate intervening member and any additional intermediate members coupled with one another, or with the two members coupled to each other using an intervening member that is integrally formed as a single unitary body with one of the two members. If “coupled” or variations thereof are modified by an additional term (e.g., directly coupled), the generic definition of “coupled” provided above is modified by the plain language meaning of the additional term (e.g., “directly coupled” means the joining of two members without any separate intervening member), resulting in a narrower definition than the generic definition of “coupled” provided above. Such coupling may be mechanical, electrical, or fluidic.

[0061] References herein to the positions of elements (e.g., “top,” “bottom,” “above,” “below”) are merely used to describe the orientation of various elements in the FIGURES. It should be noted that the orientation of various elements may differ according to other exemplary embodiments, and that such variations are intended to be encompassed by the present disclosure.

[0062] Although the figures and description may illustrate a specific order of method steps, the order of such steps may differ from what is depicted and described, unless specified differently above. Also, two or more steps may be performed concurrently or with partial concurrence, unless specified differently above. All such variations are within the scope of the disclosure.

Claims

WHAT IS CLAIMED IS:

1. A dressing, comprising: a foam layer comprising a non-patient-facing surface, the non-patient-facing surface comprising a plurality of depressions therein; and a plurality of superabsorbent deposits positioned in the plurality of depressions.

2. The dressing of Claim 1, comprising a polyurethane drape layer coupled to the foam layer, wherein the plurality of superabsorbent deposits are positioned between the foam layer and the polyurethane drape layer.

3. The dressing of Claim 1, wherein: a first superabsorbent deposit of the plurality of superabsorbent deposits is positioned in a first depression of the plurality of depressions; and a volume of the first depression is greater than a volume of the first superabsorbent deposit when the first superabsorbent deposit is dry.

4. The dressing of Claim 3, wherein the volume of the first depression is approximately equal to the volume of the first superabsorbent deposit when the first superabsorbent deposit absorbs an amount of fluid.

5. The dressing of Claim 1, wherein each of the plurality of depressions has a hemispherical shape.

6. The dressing of Claim 5, wherein the depressions are arranged in an array.

7. The dressing of Claim 1, wherein the plurality of depressions are formed as a plurality of channels.

8. The dressing of Claim 7, wherein the channels extend in parallel directions along the dressing.

9. The dressing of Claim 1, comprising a perforated film layer coupled to the foam layer, the foam layer positioned between the perforated film layer and the superabsorbent deposits.

10. The dressing of Claim 9, wherein the perforated film layer comprises polyvinylidene diflouoride.

11. The dressing of Claim 9, wherein the perorated film layer has a thickness of approximately 125 microns and comprises a plurality of perforations having diameters in a range between approximately 0.1 microns and approximately 0.2 microns.

12. The dressing of Claim 1, wherein the foam material comprises an open-cell hydrophilic foam.

13. The dressing of Claim 1, wherein the superabsorbent deposits comprise at least one of acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, sodium polyacrylate, polyacrylamide copolymer, ethylene maleic anhydride copolymer, cross-linked carboxymethylcellulose, polyvinyl alcohol copolymers or cross-linked polyethylene oxide.

14. A method of manufacturing a dressing, comprising: providing a mixture into a mold, the mold comprising a plurality of protrusions, the mixture configured to form into a foam material in the mold as a result of a chemical reaction; removing the foam material from the mold, wherein the foam material comprises a plurality of depressions corresponding to the plurality of protrusions of the mold; and depositing a superabsorbent material in the plurality of depressions.

15. The method of Claim 14, wherein the protrusions are hemispherically-shaped.

16. The method of Claim 14, wherein the protrusions comprise a plurality of ridges.

17. The method of Claim 14, wherein depositing the superabsorbent material in the plurality of depressions comprises filling the plurality of depressions with the superabsorbent material.

18. The method of Claim 14, wherein a volume of the superabsorbent material is less than a volume of the plurality of depressions when the superabsorbent material is dry.

19. The method of Claim 14, comprising coupling a drape to the mold such that the superabsorbent material is between the foam material and the drape.

20. The method of Claim 19, comprising coupling the drape to a tube coupleable to a pump with the tube fluidly communicable with the foam material.

21. The method of Claim 20, comprising providing an adhesive around a perimeter of the drape, the adhesive configured to adhere to skin.

22. The method of Claim 14, comprising coupling the foam material to a perforated fdm.

23. The method of Claim 14, comprising providing a support structure in the mold, the foam configured to bond to the support structure as a result of the chemical reaction.

24. The method of Claim 14, wherein the foam material comprises a hydrophilic open-celled foam.

25. A dressing, comprising: a foam comprising a depression in a first surface of the foam material; a superabsorbent deposit positioned in the depression; and an outer film layer coupled to the foam such that the superabsorbent deposit is between the foam and the outer film layer.

26. The dressing of Claim 25, wherein the outer film layer is configured to allow evaporation through the outer film layer.

27. The dressing of Claim 25, wherein the foam is configured to contact a wound of a patient.

28. The dressing of Claim 25, comprising a perforated film coupled to the foam; wherein the foam is positioned between the perforated film and the superabsorbent deposit; and wherein the perforated film layer is configured to contact a wound of a patient.

29. The dressing of Claim 25, comprising a thermo-formed support configured to resist deformation of the depression.

30. A negative pressure wound therapy system, comprising: a pump; a tube coupled to the pump; a dressing coupled to the tube, the dressing comprising: a foam layer comprising a non-patient-facing surface, the non-patient-facing surface comprising a plurality of depressions therein; and a plurality of superabsorbent deposits positioned in the plurality of depressions.

31. The negative pressure wound therapy system of Claim 30, wherein the dressing comprises a drape coupled to the foam layer such that the plurality of superabsorbent deposits positioned are positioned between the foam layer and the drape.

32. The negative pressure wound therapy system of Claim 31, comprising a connection pad coupled to the drape and to the tube, the connection pad configured to place the foam layer in pneumatic communication with the tube.

33. The negative pressure wound therapy system of Claim 30, the dressing comprising a perforated film coupled to the foam layer, wherein the foam layer is positioned between the perforated film and the superabsorbent deposits.

34. The dressing of Claim 30, wherein: a first superabsorbent deposit of the plurality of superabsorbent deposits is positioned in a first depression of the plurality of depressions; and a volume of the first depression is greater than a volume of the first superabsorbent deposit when the first superabsorbent deposit is dry.

35. The dressing of Claim 34, wherein the volume of the first depression is approximately equal to the volume of the first superabsorbent deposit when the first superabsorbent deposit absorbs an amount of fluid.