Pressure-stable, trimmable wound care product for necrotic ulcers

Abstract

The present invention relates to a cut-to-size wound care product comprising a wound contact layer, a first fluid-permeable nonwoven layer, and a second fluid-permeable nonwoven layer. Between the first and second layers is an inflatable layer. This inflatable layer contains an aqueous saline solution and superabsorbent fibers. The superabsorbent fibers are embedded in a textile composite with at least one type of support fiber. This wound care product is seamless and exhibits excellent pressure stability.

Description

Technical Field of invention

[0001] The invention relates to a textile, multi-layered wound care product suitable for treating various wounds, particularly ulcers, and especially ulcers on the sole of the foot. Due to its special structure, the wound care product is able to perform a physical-autolytic debridement, thereby gently removing necrotic tissue from the wound and initiating wound closure. Background of the invention

[0002] Wound dressings for moist wound care are generally known from the state of the art.

[0003] One variant is described in WO 2011 / 141454 A1. This is a wound dressing similar to a wound pad or compress, which can be applied to a wound or used for packing deep wounds. This product contains an absorbent / irrigating core with a circumferential weld seam, which is pre-treated by the manufacturer with a saline aqueous solution. This causes the superabsorbent material to swell and become gel-like. This gives the absorbent / irrigating core a dual function in wounds with high exudate: wound secretions, including their constituents such as germs, are actively absorbed and retained by the absorbent / irrigating core, while the core simultaneously releases the saline aqueous solution onto the wound, thus creating or maintaining a moist wound environment.This supports wound cleansing and positive wound conditioning, thus positively influencing healing. This is known as interactive wet dressing therapy, which is particularly suitable for poorly healing wounds, clinically infected wounds, or chronic wounds of various origins, such as diabetic gangrene, pressure ulcers, or leg ulcers. However, wound dressings of this type have the disadvantage that they are not designed to be adapted to the size of the wound (e.g., cut to size) once manufactured. This is because cutting the dressing would sever the outer barrier, including the welded seam, causing the gel to ooze out. Cutting the dressing while dry and subsequently adding liquid is also not possible, as the superabsorbent particles would fall out after cutting and, in the worst case, remain in the wound.Even without cutting the product, the weld seam can tear under high pressure, causing the gel or superabsorbent polymer (SAP) particles to leak out. Therefore, such a state-of-the-art product is not suitable for treating sole ulcers, which are common in diabetics, or can only be used if the patient avoids putting weight on the affected area, for example, by lying down or elevating the affected leg. Otherwise, the dressing risks bursting as soon as the patient shifts their weight onto the foot being treated. Treatment while lying down or using crutches is stressful for the patient. Prolonged lying down increases the risk of thrombosis, and crutches are perceived as excessively burdensome, especially by elderly patients.

[0004] The information provided regarding WO 2011 / 141454 A1 applies almost identically to the wound dressing of WO 2016 / 156619 A1. This dressing is also intended for moist wound healing and is supplied as a sheet material consisting of several layers joined only at the edges by a welded seam. The layers can otherwise shift against each other, for example, during body movements, resulting in a flexible arrangement. This wound dressing is also not cuttable and is not suitable for use on the sole of the foot.

[0005] While the aforementioned products can be used to treat ulcers, such as leg ulcers, a common problem arises: because the products cannot be cut to the size of the wound, they inevitably extend beyond it. Furthermore, since they are applied moist, the healthy skin surrounding the wound will swell with increasing application time. This undesirable effect is known as maceration and, in the worst-case scenario, can lead to an enlargement of the wound.

[0006] Further state of the art is known from DE202013104893U1, DE102013105063, AU2012236039 and EP3315145.

[0007] Consequently, there is a need for a wound dressing suitable for treating various wounds, especially ulcers, including those on the sole of the foot. This dressing should be cut to size, remove necrotic tissue, and create a moist wound environment to promote wound closure, all without restricting the patient's mobility during treatment. Furthermore, it should prevent maceration of the wound edges. Summary of the invention

[0008] The task outlined above is solved by providing a

[0009] The cut-to-size wound care product comprises the following components a) a first fluid-permeable layer made of nonwoven fabric, b) a second fluid-permeable layer made of nonwoven fabric, c) a swelling layer in the form of a nonwoven fabric with superabsorbent, polymer-containing fibers located between the first and second layers, wherein the superabsorbent fibers are present in a felt with at least one other type of fiber, d) an aqueous saline solution embedded in the swelling layer, which has a pH < 7.0 in the embedded state and which can be released onto a wound during wound treatment, wherein the first layer, the swelling layer and the second layer have an identical cut and lie completely against each other without overhang, and wherein the wound care product is designed seamlessly.

[0010] Alternatively, the wound care product can consist of the components mentioned above.

[0011] Due to the described design, the wound dressing according to the invention can be cut to the size of the wound, and if application to the sole of the foot is intended, the patient remains mobile during treatment. Furthermore, any potential overhang of the dressing beyond the sole of the foot is prevented, so that, for example, wearing shoes remains possible. When body weight is shifted onto the dressing, the wound is more thoroughly rinsed with the saline solution, and when weight is subsequently relieved (weight is shifted to the other leg), most of the solution is reabsorbed by the dressing. This results in a repetitive physical-autolytic debridement, which can remove cell debris, pus, and, above all, necrotic tissue. Simultaneously, in the case of a wound infection, pathogens are flushed from the wound and absorbed by the dressing, where they are retained.Together with the moist wound environment, optimal conditions are created to stimulate the healing of chronic wounds in particular and to improve the quality of life of the affected patients. Detailed description of the invention

[0012] The term "cuttable" means that a product or material can be deliberately reduced to a size intended by the user before application using a commercially available mechanical tool such as scissors, without the product or material losing any function and without any undesirable (partial or complete) disintegration of the product or material.

[0013] The term "medically acceptable material" as used in the invention is a non-toxic, lint-free and stable substance that, under normal conditions, does not decompose into polar or non-polar substances and cannot be broken down to any significant extent by the secretions of animal or bacterial cells.

[0014] The term "atraumatic" means that a wound care product does not bond firmly with the wound, i.e., it does not dry out in the wound or become embedded in it, and that the product can be removed painlessly without disrupting the healing process.

[0015] The term "configured for application to a wound" means that the wound care product is intended for application to a wound for a therapeutic purpose in the sense of wound treatment.

[0016] Ringer's solution is an aqueous solution containing sodium chloride, potassium chloride, and calcium chloride (specifically 8.6 g NaCl, 0.3 g KCl, and 0.33 g CaCl₂ per liter of water), which is essentially isotonic (osmolarity of approximately 308 mOsm / L). Ringer's solution is generally sterilized before use.

[0017] In the context of the present invention, "proximal" means that a material or substance occupies a position within a wound care product such that, during its use in wound care, it is positioned towards the wound. This is the case, for example, with a wound contact layer.

[0018] "Distal" in the context of the present invention means that a material or substance occupies a position within a wound care product such that, within this product, it is arranged away from the wound during application in wound care, as is the case, for example, with a backing (final support layer).

[0019] "SAF" is an abbreviation for superabsorbent fibers. These fibers are capable of absorbing many times their own weight in polar liquids and can be combined with other fibers to form a stable fiber composite.

[0020] "Additional fiber" refers to a fiber that differs from superabsorbent fibers (SAF) and is therefore not itself a SAF.

[0021] "Moisture Vapor Transmission Rate" or "MVTR" refers to a measurement that indicates the permeability of water vapor through a specific material in g / m² / 24h. The MVTR can be determined using the standard DIN EN 13726-2 (June 2002).

[0022] The wound care product according to the invention consists of at least three layers: a first layer, a swelling layer, and a second layer. All three of these layers have an identical cut, so that they lie against each other without any overlap. Minor production-related deviations (tolerances) are possible, however, without impairing the function. In such cases, one or two layers may protrude up to 5 mm beyond another layer or layers.

[0023] Pressure resistance is achieved through the product's construction, with the composition of the swelling layer—comprising a felt made of SAF and additional fibers—and the resulting elimination of a weld seam being crucial. Seamless means, in particular, that the product has no weld seam. In this way, the required pressure resistance values ​​can be achieved. Accordingly, the wound care product reacts to mechanical pressure only through elastic and therefore reversible deformation. It is therefore preferable for the wound care product to exhibit pressure resistance of at least 8 kg / 100 cm², preferably 20 kg / 100 cm², even better at least 50 kg / 100 cm², and ideally 120 kg / 100 cm².

[0024] Pressure resistance can be tested using the following procedure: 1) Provide a wound care product treated with aqueous saline solution, sterilized within the last 14 days. 2) Place the (unwrapped) product in a commercially available, transparent zip-top bag. 3) Apply the weight force to be tested within one second. 4) Hold the weight force for one second. 5) Release the weight force within two seconds. 6) Repeat steps 3 to 5 so that the weight force is applied a total of ten times. 7) Remove the product from the bag. 8) Visually inspect both the product and the inside of the bag for detached fibers or leaked gel.

[0025] If no detached fibers or leaked gel are visible on the product itself or inside the bag, the test is considered passed for the corresponding weight force.

[0026] Preferably, the wound care product is designed in such a way that, due to its elastic properties and pressure resistance, it can be folded or folded over by 90°, or even better by 180°, along an actual or (in the case of an asymmetrical design) imaginary center line, without any plastic deformation occurring.

[0027] The first and second layers can include other components besides the aforementioned nonwoven fabric, such as different fiber arrangements, as long as these do not disintegrate after cutting. Preferably, the first and second layers consist entirely of nonwoven fabric, since nonwovens are particularly resistant to fiber breakage, even after the material has been cut.

[0028] The swelling layer contains superabsorbent fibers (SAFs), in particular superabsorbent fibers containing a superabsorbent polymer. The superabsorbent polymer preferably comprises an acrylate-containing polymer or an acrylate copolymer. The SAFs can have a fiber diameter of, for example, 50 to 500 µm. A fiber diameter of 100 to 200 µm is preferred, as this diameter allows for an ideal water-to-fiber ratio. This enables a larger quantity, for example, 15 ml, of an aqueous saline solution to be released from the swelling layer to the wound and subsequently reabsorbed. This mechanism is based, in part, on chemical-physical processes such as diffusion, in which clean saline solution migrates towards the wound and rinsed wound exudate migrates towards the swelling layer.Secondly, the saline solution is partially forced out under mechanical pressure and reabsorbed by the swelling layer when the pressure is released. Methods for providing and adjusting the SAF are explained in more detail elsewhere.

[0029] The invention comprises a cuttable wound care product, whereby cutting is understood to mean that all layers of the product are simultaneously severed. Typically, cutting will result in a section being removed from the overall product, thus reducing its surface area. However, it is also possible to simply make an incision in the product in order to bend or fold it along the incision edge. This can be advantageous in certain cases when treating wounds on fingers or toes, as the product can then be adapted particularly well to the body's contours.If the wound care product is used as a tamponade, it can be shortened by cutting to adapt to the depth of the cavity being treated. This represents a significant advantage over previously used tamponade products: Conventional products are either not cuttable or, if they are, there is a risk of organic tissue growing into the product structure. In practice, attempts are often made to counteract this by soaking the required amount of a standard dressing material (such as gauze) with hydrophobic ointment and then inserting it into the cavity. Given the frequent need for daily dressing changes in cavities, the workload associated with this approach is enormous for medical personnel.

[0030] The wound care product is preferably flat, meaning it has a flat distal upper surface and an equally flat proximal underside, making it ideally suited for wound coverage and ensuring a flush fit with the wound edges. "Flat" means that each layer has no significant raised areas or depressions. Both the first and second layers can function as the underside or wound contact layer, respectively. This allows the product to be easily draped onto or within a wound. The flat underside enhances atraumatic properties and reduces wound irritation.

[0031] Furthermore, the wound care product is preferably round or elliptical (when viewed from above). Compared to rectangular shapes, this has the advantage that the product, even in its uncut state, already resembles the shape of most chronic wounds, which (unlike, for example, cuts) in most cases have a circular appearance. In addition, it has been shown that round or elliptical shapes can be fixed to the sole of the foot better and more permanently and are less bothersome to the wearer than other shapes, such as rectangular designs with rounded corners, which are frequently used for abrasions. Rectangular designs also have the disadvantage that, with continuous mechanical stress—such as during walking—they quickly begin to detach from the skin at the corners. The corners then tend to curl up, leading to an unwanted raised area and potentially causing pressure pain on the sole of the foot.

[0032] In the case of deep tissue defects – so-called cavities – the wound care product according to the invention can be packed into the wound. In addition to the aforementioned advantages of wound care, this has the further effect of preventing the cavity from closing prematurely at the level of the epidermis, instead allowing tissue regrowth to occur from the center (from the base of the wound bed) to the periphery (towards the skin surface). Otherwise, premature wound closure could lead to an abscess and significantly complicate further treatment.

[0033] The wound care product according to the invention contains a swelling layer in the form of a nonwoven fabric with superabsorbent, polymer-containing fibers, wherein the superabsorbent fibers are combined with at least one other type of fiber (additional fiber) in a felt-like composite. The purpose of these additional fibers is to provide the swelling layer with sufficient tear and tensile strength as well as dimensional stability in a moist state and to avoid the need for an (external) seam. Since the superabsorbent fibers are combined with the additional fiber in a felt-like composite, they form a stable fiber structure even after cutting. The absence of a seam significantly increases pressure resistance.

[0034] With regard to the source layer, the additional fiber ("other fiber") can be a fiber type of synthetic, natural, or semi-synthetic origin, with SAFs being explicitly excluded. Examples of suitable fibers of synthetic origin are polyolefin-based fibers such as polyester and polyamide. Within the polyester group, polyethylene terephthalate is particularly suitable. Examples of suitable fibers of natural origin include cotton and flax. An example of a fiber of semi-synthetic origin is lyocell. Natural and semi-synthetic fibers together form the group of cellulose-containing fibers, provided they contain cellulose.

[0035] The additive fiber is present together with the SAF in a felt, preferably a needle-punched felt. This means that the two fiber types are matted together. The felt can be produced as a wet felt or as a dry felt. Production as a dry felt is preferred, as this prevents the SAF from drying out again. The dry felt can be provided as a needle-punched felt, a bonded felt, or a thermally bonded melt felt. In a needle-punched felt, the additive fibers and the SAF are mechanically needled together to form a felt. In a bonded felt, the two fiber types are bonded together by adding an adhesive (mainly through chemical interaction). The adhesive used should not be water-soluble after curing, as otherwise it could degrade due to the action of the aqueous salt solution.In a melt-filled felt, the additional fiber is selected from the melt-filled fiber range and bonded to the SAF (which possess inherent melt-filled fiber properties) using thermal energy. Preferably, the fibers of the swelling layer are in the form of needle-punched felt. A swelling layer in the form of needle-punched felt offers the advantage of compatibility with all sterilization methods, as it exhibits excellent resistance to heat, pressure, steam, radiation, and ethylene oxide. Furthermore, the needle-punched felt form allows for great flexibility in fiber selection and offers a very long shelf life, even after extended storage.

[0036] The swelling layer constructed in this way can be easily cut without the SAF and the additional fiber separating from each other, and without superabsorbent particles, such as those frequently used in absorbent wound dressings, falling out of the swelling layer at the cut site. Furthermore, it enables permanent attachment to the other layers of the wound care product. For example, it is possible to bond the swelling layer to the nonwoven fabric of the first and second layers on its distal and proximal sides, even if these layers contain different materials than the swelling layer. One method for obtaining such a laminate is described in Example 1.

[0037] The wound care product according to the invention is ideally suited for moist wound healing. "Suitable for moist wound healing" or "for moist wound healing" means that the product can be used without further preparation or modification, such that moist wound healing begins immediately upon application. Consequently, the wound care product can be stored in a moist state between manufacture and use without any impairment of its structural integrity.

[0038] The saline solution contained in the swelling layer rinses the wound, thereby dissolving deposits such as fibrin, supporting the autocatalytic decomposition of necrotic tissue, and removing microorganisms. Excess matrix metalloproteinases are flushed from the wound, and stalled healing processes are restarted. The moist environment also generally accelerates wound closure.

[0039] When applied to the sole of the foot, the movement stimulates venous blood drainage, which is particularly important for chronic wounds caused by venous congestion (e.g., leg ulcers, also known as "open leg"). Because the product's shape can be adjusted to the wound by trimming, it prevents the product from extending beyond the wound and thus avoids maceration of the surrounding skin, despite the moist wound dressing. Furthermore, this design makes the product significantly more comfortable to wear under a compression bandage or stocking, such as those used for pressure ulcers to alleviate pathological venous congestion.

[0040] The wound care product according to the present invention is ideally suited for the treatment, particularly for moist wound healing, of slow-healing or non-healing and chronic wounds. This includes, in particular, the following types of wounds: diabetic foot ulcers, venous leg ulcers, arterial leg ulcers, mixed leg ulcers, and pressure ulcers. These wounds are frequently characterized by the presence of slough (e.g., fibrin deposits) and necrosis. Furthermore, the inhibited healing process appears to be associated with an imbalance of the necessary signaling molecules, enzymes (e.g., matrix metalloproteinases), and molecular inhibitors in the wound. Irrigation of the wound during moist wound healing eliminates the previously prevailing chemical imbalance and allows an environment conducive to wound healing to be established. In this way, the previously inhibited healing process is restarted.As already mentioned, the wound care product according to the invention can in most cases be combined with compression therapy to eliminate venous congestion as the underlying ulcer-causing problem.

[0041] Particularly suitable means for fixing the wound care product according to the invention to the wound site or in a deep wound (cavity) are secondary dressings such as adhesive films, gauze, bandages, and adhesive tape. Among these means, adhesive films are preferred because they—like the wound care product itself—can be cut to size without losing their function or fraying. Furthermore, adhesive films reduce evaporation and, even when applied to the sole of the foot, do not impede the patient's walking. In addition, adhesive films can be made waterproof, thereby protecting the wound care product from unwanted external influences (e.g., during showering).

[0042] The nonwoven fabric of the first and / or second layer can be thermally bonded and thus contain thermally bonded fibers. This increases bond strength and allows for the production of lighter nonwovens, resulting in material savings. Water permeability is maintained. The thermally bonded nonwoven can contain thermoplastic fibers. Examples include polypropylene (PP), polyvinyl chloride (PVC), polyethylene (PE), polyester (PET), polyacrylic (PC), polyacrylonitrile (PAN), polyamide (PA), polyurethane (PU), viscose (CV), and blends of two or more of these fiber types. Furthermore, thermoplastic additives can be included. PET is an example of a thermoplastic additive.

[0043] To produce a suitable thermally bonded nonwoven fabric, the fibers, laid in a loose web, can be heated to their melting point, causing them to bond together. This can be achieved through calender bonding (also called thermobonding) or hot air bonding (also called thermofusion), with calender bonding proving particularly effective for polypropylene (PP) fibers.

[0044] When using fibers that are not suitable for thermal bonding in their pure form, bonding fibers can be added to enable thermal bonding nonetheless. Thus, the thermally bonded nonwoven can contain not only thermoplastic fibers and thermoplastic additives but also other fiber types such as cotton or viscose. These fibers are preferably of natural origin or semi-synthetic fibers such as viscose.

[0045] Heat transfer for thermal bonding can occur via conduction, convection, or radiation. Calendering and hot air bonding are particularly suitable. This type of bonding transforms a loose fiber fleece into a solid, durable nonwoven fabric. The risk of fibers detaching and entering the wound is thus significantly reduced.

[0046] The SAFs in the swelling layer can comprise or consist of a polymer containing acrylate. This can be a polyacrylamide, a polyacrylamide derivative, or an acrylamide copolymer. According to a preferred embodiment of the invention, the SAFs in the swelling layer of the wound care product contain a cross-linkable polymer. An example of cross-linkable polymers from which SAFs can be obtained or which can form a component of SAFs are acrylate-containing polymers.

[0047] The SAF (swelling material) in the swelling layer of the wound care product preferably contains a cross-linked polymer. Preferably, the cross-linking is based on the formation of ester bonds. The cross-linked polymer can be cross-linked or cross-linkable by these ester bonds. The degree of cross-linking determines the flexibility or resistance of the SAF (flexural strength) in the presence of the aqueous saline solution. The higher the degree of cross-linking, the more viscous the gel-like consistency of the SAF, which can exist as hydrogels in the presence of water or other aqueous fluids such as wound exudate. Simultaneously, the load-bearing capacity of the swelling layer, and thus of the wound care product as a whole, increases with the degree of cross-linking.

[0048] The cross-linking bonds can be acrylate bonds. Cross-linking can occur via radical or cationic polymerization mechanisms or other esterification or transesterification mechanisms such as Michael addition. Radical polymerization is preferred. Polyacrylamides can be cross-linked by being treated in an acidic environment. Depending on the desired reaction rate, the pH can be less than 6.0, less than 5.0, or less than 4.0. For example, the pH can range from 3.0 to 6.0, 1.0 to 5.0, or 0.0 to 4.0.

[0049] In this context, the SAFs can contain a polymer that is 5 to 50% cross-linked, preferably 10 to 40%. For acrylic-containing polymers, the degree of cross-linking can be determined based on the amount of acrylic groups cross-linked via ester bonds within the polymer. A degree of cross-linking of 50% would thus mean that half of the acrylic groups are cross-linked.

[0050] Furthermore, the SAFs may contain a copolymer, which may be an acrylic copolymer.

[0051] One possible example is poly(acrylic acid-co-acrylamide) / polyvinyl alcohol. This can be spun directly into SAF.

[0052] The cross-linking of SAF does not preclude its needle-punching with at least one other fiber type (an additional fiber that is not SAF) to form a needle-punched felt. Cross-linking can take place either before or after needle-punching, although it is recommended to perform it before needle-punching, as this allows for more precise control of the degree of cross-linking. Thermal bonding can follow needle-punching, and these three processes (cross-linking, needle-punching, and thermal bonding) synergistically complement each other, resulting in a swelling layer that exhibits excellent moisture retention, moisture release, and outstanding mechanical strength, even after cutting by the end user or caregivers.

[0053] The ratio between SAF and additive fibers in the source layer can be, for example, as follows: 20 wt.% to 80 wt.% SAF and 80 wt.% to 20 wt.% additive fibers. Preferably, the proportion of SAF in the source layer is 20 wt.% to 60 wt.%, more preferably 20 wt.% to 40 wt.%, with the remaining proportion being made up of the additive fibers. One possible embodiment contains 25 wt.% SAF and 75 wt.% polyolefin-based fibers in the source layer.

[0054] According to the invention, the source layer, the first layer, and the second layer are bonded together across their entire surface (i.e., over the entire area of ​​the respective top and bottom surfaces). The surfaces can be adhesively bonded, with the adhesive bond being either direct (directly adjacent) or indirect – for example, by inserting further intermediate layers such as a perforated double-sided adhesive film or a porous melt film (thermoplastic). The layers can be adhesively joined, for example, by an adhesive or bonding agent. The adhesive bond or layer can be present in the finished product as a cohesive layer, meaning that the particles of the adhesive (atoms, molecules, etc.) within it attract each other. Preferably, this is a hot melt adhesive or hot melt bonding agent.Examples of possible hot melt adhesives include copolymers and polyolefin-based hot melt adhesives such as polyester or polyester derivatives like copolyester. These types of hot melt adhesives are ideally suited for permanently bonding nonwoven layers, especially those containing synthetic fibers. Furthermore, they are generally technically compatible with subsequent heat sterilization. The melting point can even be below the subsequent sterilization temperature, as the product is already contained within an outer packaging during sterilization, which provides the finished product with additional stability. Thus, the melting point of the hot melt adhesive or the hot melt adhesive bond can be, for example, between 45 °C and 120 °C, preferably between 45 °C and 70 °C. If required – for example, through the use of copolyester – maximum melting points of up to 140 °C and sometimes even higher can be achieved.It is recommended to sterilize the wound care product in a moist state (i.e., with the aqueous saline solution it contains), as low sterilization temperatures (e.g., 120 °C) may be sufficient in this way, provided that an adequate exposure time is ensured.

[0055] The aforementioned hot melt adhesives can be supplied to the melting process in various starting materials. They can be provided in particle, mesh, or film form. Particle or mesh form is preferred because it does not restrict the mobility of the resulting product. Particles also offer the advantage of free-flowing properties. Films and meshes are particularly suitable when different hot melt adhesives are to be combined. Such combinations can lead to particularly strong adhesive bonds, where one of the adhesives fixes the respective layers during the manufacturing process, and the other adhesive (with a higher melting point) reacts during the sterilization process, further strengthening the initial bond without requiring any additional thermal energy during the process.

[0056] The layers of the wound care product—especially the first layer, the swelling layer, and the second layer—can be laminated. This can be achieved by bonding them together using thermal energy and / or adhesives. Using adhesives that do not require heating also results in a laminate, which in this case is a cold laminate. It is recommended to apply the aforementioned hot melt adhesive between the layers to increase the durability of the resulting laminate. The required temperatures depend on the materials being treated and can range, for example, from 45 to 160 °C. An exposure time of 2 seconds to 10 minutes is usually sufficient. The optimal exposure time varies depending on the chosen temperature but will, in most cases, range from 2 to 30 seconds.

[0057] The layers of the wound care product, cohesively joined in this way, have the advantage of forming a continuous bond that holds the layers together even after the product has been cut. Preferably, this continuous bond is a full-surface adhesive bond, particularly preferably a full-surface adhesive bond, and ideally a full-surface hot melt adhesive bond. Conversely, methods that only join the individual layers along their edges (e.g., conventional welding) do not result in a product that can be cut.

[0058] Other ways to connect the layers include anchoring fibers from one layer into an adjacent layer. In this way, two layers can be joined together, for example, by weaving or felting.

[0059] The wound care product can be cut into two or more segments. All segments obtained in this way can be used in wound care. The segments obtained by cutting are able to release the aqueous saline solution stored in the swelling layer to the wound, thereby rinsing and cleaning it.

[0060] Another aspect of the invention relates to a cuttable, flat wound care product in which the first layer, the swelling layer, and the second layer are joined together flatly via a fusion bond, wherein the fusion bond contains or consists of a fused polyolefin or fused copolymer. Such a laminate can advantageously be cut without fraying at the cut edges.

[0061] A particular advantage of the cuttable, flat wound care product according to the invention is that the rinsing effect emanating from the wound care product is enhanced or intensified by repeated reversible (non-plastic) deformation or repeated pressure compression of the wound care product. In practice, this can be achieved, for example, by applying the wound care product to the sole of the foot and subsequently subjecting it to repeated pressure loading and unloading while walking. In this way, when the foot bears weight, the wound care product is compressed, and the portion of the aqueous saline solution not firmly bound to the SAF (semollients) is partially squeezed out of the wound care product. As soon as the patient lifts their foot and the wound care product expands again, a portion of the released saline solution (along with dissolved substances, pathogens, etc.) is reabsorbed.This process occurs repetitively while walking, allowing for a particularly intensive rinsing of the wound.

[0062] Another option, for example in the treatment of a leg ulcer, is to apply the wound care product and then wrap it with a compression bandage. The compression bandage acts as a counterweight for the so-called venous muscle pump. During muscle contraction, the wound care product is compressed between the body surface and the compression bandage. During the subsequent muscle relaxation, the wound care product can expand again. This muscle contraction occurs involuntarily during walking. If a patient is bedridden, suitable exercises can alternatively be performed while lying down – for example, under the guidance of a physiotherapist. In the cases mentioned here, a beneficial, enhanced flushing effect also occurs.

[0063] In this context (enhanced rinsing effect), the terms repeated reversible deformation or repeated pressure compression can mean that the wound care product is capable of enhanced wound rinsing when it is deformed or compressed at least three times, essentially returning to its original shape each time without additional support. Enhanced rinsing is understood as the delivery of a greater volume of aqueous saline solution (e.g., to a wound or measuring device) compared to purely passive mass exchange (without deformation or compression) along the concentration gradient. The wound care product may, for example, be saturated with aqueous saline solution to 80% of its maximum absorption capacity in its initial state.

[0064] In the context of the invention, the wound care product is able to generate a muscle-driven pumping effect during wound treatment to irrigate the wound to be treated with the aqueous saline solution contained in the swelling layer, particularly when walking, if the product is fixed to the sole of the foot.

[0065] The intensified rinsing effect achieved in this way allows for extremely gentle cleaning of the wound from necrosis and fibrin deposits, which usually avoids the need for invasive surgical cleaning using a scalpel, sharp spoon, etc., which is stressful for the patient.

[0066] Preferably, the enhanced rinsing effect simultaneously represents an enhanced absorption / rinsing effect, which is accompanied by increased uptake of substances drawn from the wound. For example, microorganisms flushed from the wound are retained in the swelling layer and removed during the next dressing change.

[0067] Furthermore, it can be provided that, after cutting the wound care product according to the invention, the structural integrity of the remaining area intended for wound care is maintained, so that, due to the felt structure of the swelling layer, no fibrous or particulate components of the cut wound care product, in particular no superabsorbent fibers, are released. Such a wound care product is therefore lint-free, even after being cut immediately before application.

[0068] In the wound care product according to the invention, the pH value of the aqueous saline solution can be adjusted to less than 7.0 by an acid group contained in the superabsorbent fibers, preferably acrylic acid. This acid group can be part of the polymer contained in or from which the superabsorbent fibers are composed. The polymer can be polyacrylic acid. The advantage is that further acidifying components can be omitted, and a slightly acidic pH value, which promotes healing in the vast majority of wounds, can be achieved. Preferably, the pH value of the aqueous saline solution adjusted by the aforementioned acid group is in the range of 4.5 to 6.9. Particularly preferably, the pH value is in the range of 5.0 to 6.5.

[0069] Furthermore, it is preferably provided that the first layer, the swelling layer, and the second layer exhibit substantially identical lateral expansion upon liquid absorption. Substantially identical lateral expansion means that the surface area of ​​these layers increases to the same extent as they absorb moisture, whereby slight differences in area of ​​up to 5%, preferably up to 3%, between the adjacent layers are possible and included. The expansion can be determined according to standard AATCC™ 135. Regarding any potential shrinkage after liquid release, the same applies analogously with respect to the reduction in the surface area of ​​the layers.

[0070] The advantage of essentially the same surface area change of the three layers upon contact with liquid is that, as a result of moisture absorption, the wound care product does not deform (e.g., curvature or protrusion) and the planar shape is maintained.

[0071] In this context, the first layer, the swelling layer, and the second layer can have the same or substantially the same coefficient of thermal lateral expansion, which refers to the area expansion. Differences of up to 5%, preferably up to 3%, between the adjacent layers are included as tolerances. An identical or substantially identical coefficient of thermal lateral expansion offers an advantage during heat sterilization of the wound care product. Otherwise, undesirable deformation of the product can occur during sterilization, and sterilization must be carried out using other (usually more complex or expensive) methods, such as irradiation or fumigation with ethylene oxide.

[0072] Identical or essentially identical expansion, or thermal expansion, can be achieved by using multiple layers of materials that exhibit the same or very similar expansion behavior. For example, synthetic fibers show very similar expansion and shrinkage behavior both among themselves and compared to cotton.

[0073] According to the invention, the swelling layer of the wound care product comprises at least one other type of fiber or at least one additional fiber besides SAF. Advantageously, this is a cellulose-containing fiber such as lyocell or a polyolefin-based fiber containing, for example, PE.

[0074] Lyocell fibers have the advantage of excellent moisture retention capacity, which surpasses even the already high capacity of cotton. Thus, lyocell fibers synergistically support the SAF (substrate-absorbing membrane), giving the swelling layer the necessary structural strength and keeping the SAF in place within the swelling layer.

[0075] Furthermore, with regard to the wound care product according to the invention, it is possible that the nonwoven fabric of the first and / or second layer contains viscose and polyester or consists of these polymers. The polyester content in the nonwoven fabric can be, for example, 30 to 50 percent by mass. The addition of the hydrophobic polyester creates a hygroscopic gradient from both the first and second layers, which conducts fluid through these two layers towards the swelling layer. Simultaneously, the aqueous saline solution from the swelling layer can pass through the first and second layers and then reach the wound without being retained in the first or second layer.

[0076] Furthermore, it is possible for the first and second layers to consist of an identical material or material mixture and / or have the same basis weight. These materials or material mixtures can be those listed in the last paragraph. Using identical materials for both layers guarantees that both layers have the same properties. This is especially true if they have the same basis weight. In this way, user errors are avoided, such as placing the wrong or suboptimal side on the wound. Additionally, such a setup offers the advantage when packing a cavity that all wound walls (regardless of their spatial position) are contacted and treated with identical material, resulting in a consistent treatment effect with every application.

[0077] Generally, the nonwoven fabric of the first and / or second layer can have a basis weight of 15 to 50 g / m² in its dry state, for example, 18 to 45 g / m². The basis weight can be determined according to the standard DIN EN 12127. It has been shown that layers with such properties combine very good structural strength with high permeability to liquids. The layers remain resilient even after being cut to size, but do not impede the desired absorption / irrigation effect of the wound care product.

[0078] The wound care product according to the invention can have different external shapes and dimensions. For the treatment of an (external) wound, a shape that is flat on both sides (i.e., both proximally and distally) is recommended. For the treatment of ulcers on the sole of the foot, it is also advantageous to design the wound care product with a low profile. Such a wound care product hardly or not at all disturbs the patient's usual daily routine, since the patient can wear the product under socks and in shoes and even walk with it. Such a low profile is 1.5 mm to 6 mm. If the wound care product only has the minimum structure of a first layer, swelling layer, second layer, and optional adhesive layers, the profile can be even more advantageously 1.7 mm to 3 mm, preferably 1.7 mm to 2.5 mm, and particularly preferably 1.8 mm to 2.2 mm.The specified height ranges refer to the dry composite described in the present application (i.e., without aqueous saline solution) consisting of a first layer, a swelling layer, and a second layer, and also without optional release liners or other packaging material. The height of the product treated with aqueous saline solution can increase by approximately 10% (depending on the applied volume). Consequently, the wound care product in its moist state would, for example, have a height of 1.7 mm to 6.6 mm, better 1.9 mm to 3.3 mm, even better 1.9 mm to 2.8 mm, and best 2 mm to 2.4 mm.

[0079] Examples of other possible shapes include cushion-shaped and cylindrical. The cushion-shaped version provides a particularly good padding effect. This is perceived as especially comfortable by patients with wounds located on the ankle, for example. The cylindrical version is particularly advantageous for tunnel-shaped wounds and cavities, as any protruding end can simply be cut off. This prevents premature superficial wound closure with underlying encapsulation and subsequent abscess formation.

[0080] Regarding shape, the wound care product can be round, rectangular, square, oval, or diamond-shaped when viewed from above. The surface area can range from 50 cm² to 500 cm², with larger surfaces offering the advantage of being able to be cut to the specific size of the wound.

[0081] The swelling layer of the wound care product preferably contains the aqueous saline solution in an amount that does not exhaust its absorption capacity. This means that the swelling layer is preferably unsaturated. In this way, the swelling layer, or the wound care product itself, can absorb further fluid such as wound exudate or blood. Thus, the swelling layer, or alternatively the entire wound care product, can be saturated with the aqueous saline solution to a maximum of 50%, 60%, 70%, 80%, 90%, or 95%.

[0082] Which of these values ​​is most suitable depends on the type of wound being treated. The more a wound is covered with deposits (e.g., fibrin deposits), necrotic tissue, or biofilm, the more it will benefit from intensive irrigation. In such cases, high saturation levels of 80% or more are recommended. Conversely, highly exuding, non-infected wounds can be treated with product variants that have a lower saturation level in the range of 50% to 70%.

[0083] The specified saturation values ​​are explained below using an example: If the swelling layer can absorb a maximum of 100 ml of an aqueous salt solution (osmotic value in the isotonic range, i.e., 9 g NaCl per liter of H2O), then the swelling layer is 50% saturated after absorbing 50 ml.

[0084] Furthermore, the specified saturation values ​​can also refer to a wound care product with the three main layers (first layer, swelling layer, second layer and optional intermediate adhesive layers) or to the entire wound care product, which may also have additional layers as needed.

[0085] Furthermore, it may be determined that the wound care product is not suitable or compatible with negative pressure wound therapy, for example because it does not have a port through which negative pressure can be applied to the product or a wound below the product.

[0086] Within the scope of the present invention, it is possible that the wound care product contains no superabsorbent particles. Preferably, it contains no particles at all that could fall out after the product is cut. This excludes adhesive particles that can be used during the manufacturing of the product, as these bond with the other materials and do not impede the desired effect of being cuttable. Active ingredient particles that dissolve in the aqueous saline solution are also not excluded from the concept of the invention.

[0087] The salt present in the aqueous salt solution can be NaCl. Preferably, the aqueous salt solution is isotonic. Such an isotonic salt solution has essentially the same osmotic pressure as human blood. Small deviations of 1% in Pascals above or below this value are tolerable and also fall under the definition of an isotonic solution.

[0088] The aqueous salt solution can contain not only NaCl but also other salts such as KCl or salt combinations such as KCl and NaCl. A preferred type of aqueous salt solution is Ringer's solution, which contains CaCl₂ in addition to NaCl and KCl and is isotonic.

[0089] An isotonic solution offers the advantage that the unprotected cells in the open area of ​​the wound being treated are not exposed to osmotic stress. Furthermore, the supply of minerals contained in the saline solution has a positive effect on cell metabolism. Human cells are thus able to absorb minerals from their environment via membrane-bound proteins such as aquaporins.

[0090] The aqueous saline solution incorporated into the swelling layer can migrate from the swelling layer into the other layers of the wound care product. In particular, the aqueous saline solution may be present in the first and second layers. This does not impair the product's functionality. In fact, the passage of the solution through the first and / or second layer, at the latest after application to or within the wound, is desirable. When determining the amount of solution required to wet the swelling layer, the absorption capacity of the other layers can be taken into account.

[0091] The invention will now be explained in more detail with reference to exemplary drawings, whereby the variants shown can be modified depending on the intended use with the help of the technical information contained in this document.

[0092] Figure 1Figure 1 shows a cross-sectional embodiment of the wound care product according to the invention, which is ideally suited for use as a tamponade (i.e., for packing cavities and deep wounds).

[0093] Figure 2 shows the product of Figure 1 in a tailored form under supervision.

[0094] In the Figures 1 and 2A wound care product (5) according to the invention is shown, comprising a second fluid-permeable layer (1) made of nonwoven fabric, which is attached to the swelling layer (3) by means of an adhesive layer (2). Within the swelling layer is a fiber composite containing needled superabsorbent fibers and additive fibers, the additive fibers being non-superabsorbent. The swelling layer (3) is treated with an aqueous saline solution (not shown). Below the swelling layer (3) is the first fluid-permeable layer (4). The swelling layer (3) and the first layer (4) are joined together by means of an adhesive layer (2). In the illustration of Figure 2 The wound care product (5) is cut in the middle into two halves (segments). The structural unity and functionality of each half are preserved. Examples

[0095] The invention is explained in more detail below using exemplary embodiments: Example 1: Production of a wound care product for use as a tamponade

[0096] First, a swelling layer (4) was provided as a continuous length of material. A first liquid-permeable layer (4) in the form of a polypropylene nonwoven fabric was applied to the underside of the swelling layer (4). A second liquid-permeable layer (1), also consisting of a polypropylene nonwoven fabric, was applied to the top side of the swelling layer. To bond the layers together, adhesive particles in the form of biodegradable polyester were applied between the layers. The adhesive particles were then bonded together in a subsequent thermal curing process.

[0097] This was achieved through thermal treatment in a drying oven at a temperature exceeding 120°C, followed by roller compression. The resulting three-layer laminate had a basis weight of 260 g / m² and a thickness of 2.3 mm. In the next step, the laminate was wound onto a roll and fed from this roll into a converting machine, where square sections measuring 10 cm x 10 cm were cut from the laminate.

[0098] The products were then processed using a packaging machine. In the packaging machine, the previously dry products were spread out on a liquid-tight packaging film. Aqueous saline solution was added in an amount that did not exceed the maximum absorption capacity of the products (approximately 31 ml). This was followed by sealing with an upper packaging film (liquid-tight), so that the wound care products (5) were enclosed between the lower and upper films. The resulting pouch containing the products was then steam sterilized at 120°C. The now moist wound care products (5) were then stored sterile in the pouch, which also served as part of the packaging material. The sterile products (5) obtained in this way can be used for packing wounds (e.g., cavities) after removal from the pouch. Example 2: Cutting wound care products

[0099] The wound care product (5) according to Example 1 was cut in half approximately in the middle (i.e., about 5 cm from the left and right edges, respectively) using standard scissors. The cutting process was effortless and required no special force. The cut edges were visually inspected. No fraying or loose fibers were observed. The cut surfaces were flat, smooth, and straight.

[0100] Furthermore, the layers of the cutouts continued to form a stable bond and showed no tendency towards separation, disintegration, or delamination. Therefore, each individual cutout was suitable for use in wound care. Example 3: Measurement of the maximum pressure load

[0101] A moist wound dressing product (5), approximately two weeks old, was prepared according to Example 1 – but in a circular shape – and placed in a commercially available transparent plastic zip-lock bag. The bag was sealed and placed in a calibration device from Sensomative for the subsequent test procedure. The wound dressing product (5) was circular (in plan view) with a diameter of 4.5 cm. Load cycles were then performed, in which a weight force of 188.5 N (corresponding to approximately 19 kg) was applied to the entire surface of the product within 1 second. The weight force was maintained for one second and then reduced to 0 N within 2 seconds. Ten load cycles were performed. The procedure took place at a temperature between 22 °C and 23 °C.The force of gravity was transferred using an inflatable shell made of synthetic, airtight material, which was integrated into the calibration device. The shell was pneumatically inflated during the load cycles.

[0102] After completion of the stress test, the product (5) was removed from the system. Both the product (5) and the bag were visually inspected. No material breakage was detected. All layers (1, 3, 4) of the product (5) were structurally intact. After removing the product (5) from the bag, no torn fibers or leaked gel were visible on the product (5), nor were any detached or leaked materials found inside the bag. Only a small amount of the aqueous saline solution remained in the bag.

Claims

1. Trimmable wound care product (9) containing a) a first liquid-permeable layer (4) comprising a nonwoven, b) a second liquid-permeable layer (1) comprising a nonwoven, c) a swelling layer (3) between the first layer (4) and the second layer (1) and in the form of a nonwoven comprising superabsorbent, polymer-containing fibres, the superabsorbent fibres being present in a felt with at least one other fibre type, d) an aqueous saline solution which is stored in the swelling layer (3), which has a pH < 7.0 during storage and which can be delivered to a wound during a wound treatment, wherein the first layer (4), the swelling layer (3) and the second layer (1) are identically trimmed and lie against each other full face-to-full face without any overhang, and wherein the wound care product (9) is seamless.

2. Trimmable wound care product (9) according to Claim 1, wherein the wound care product (9) has a pressure resistance to a pressure of at least 8 kg / 100 cm2, such that the action of such a pressure merely causes elastic deformation of the wound care product (9).

3. Trimmable wound care product (9) according to Claim 1 or 2, wherein the other fibre type is selected from the group consisting of: cellulose-containing fibre, polyester-containing fibre, preferably polyethylene terephthalate, and / or polyamide and wherein the other fibre type is needled with the superabsorbent, polymer-containing fibres, such that it is present in a needle felt.

4. Trimmable wound care product (9) according to any of the preceding claims, wherein the nonwoven of the first layer (4) and / or of the second layer (1) contains thermally consolidated fibres.

5. Trimmable wound care product (9) according to Claim 4, wherein the thermally consolidated fibres contain or consist of one or more polymers selected from polypropylene, polyvinyl chloride, polyethylene, polyethylene terephthalate, polycarbonate, polyamide, polyurethane, polystyrene, and mixtures thereof.

6. Trimmable wound care product (9) according to any of the preceding claims, wherein the superabsorbent fibres in the swelling layer (3) contain a polymer, preferably an acrylate-containing polymer or an acrylate copolymer, which is crosslinkable, the crosslinkability being preferably based on the formation of ester bonds.

7. Trimmable wound care product (9) according to any of the preceding claims, wherein the first layer (4), the swelling layer (3) and the second layer (1) are in the form of a laminate.

8. Trimmable wound care product (9) according to any of the preceding claims, wherein the first layer (4), the swelling layer (3) and the second layer (1) are inseparably bonded to each other face-to-face, the layers being preferably joined together by means of a hot-melt adhesive and the hot-melt adhesive preferably containing or consisting of a polyolefin or copolymer.

9. Trimmable wound care product (9) according to any of the preceding claims, wherein the structural integrity of the wound care product (9) is maintained on trimming, such that the felt structure of the swelling layer does not release fibrous or particulate constituents of the wound care product (9), in particular superabsorbent fibres.

10. Trimmable wound care product (9) according to any of the preceding claims, wherein the nonwoven of the first layer (4) and / or of the second layer (1) in the dry state has a basis weight of 15 g / m2 to 50 g / m2.

11. Trimmable wound care product (9) according to any of the preceding claims, wherein the wound care product (9) has a height of 1.7 mm to 6.6 mm.

12. Trimmable wound care product (9) according to any of the preceding claims, wherein the swelling layer is saturated with the aqueous saline solution to an extent of not more than 95%.

13. Trimmable wound care product (9) according to any of the preceding claims, wherein the aqueous saline solution contains NaCl, KCl and CaCl.

14. Trimmable wound care product (9) according to any of the preceding claims, wherein the pH of the aqueous saline solution stored in the swelling layer is in the range from 4.5 to 6.9.

15. Trimmable wound care product (9) according to any of the preceding claims, wherein the first layer (4) and the second layer (1) consist of an identical material or an identical material blend.

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