Negative pressure wound therapy (NPWT) dressings

Abstract

The present disclosure generally relates to a negative pressure wound therapy (NPWT) dressing (100) configured to be connected to a negative pressure source; the NPWT dressing comprises, from top to bottom, a backing layer (101), a liquid spreading layer (102), an absorbent pad (103) comprising one or more pad-forming layers (103a-c), a spacer fabric layer (104), and a viscous skin contact layer (105); the backing layer (101) and the adhesive skin contact layer (105) are arranged to extend beyond the contour of the liquid spread layer (102), the absorbent pad (103) and the spacer fabric layer (104) to form a boundary portion (106), wherein the spacer fabric layer (104) comprises a top layer (104a), a bottom layer (104b) and an interconnection layer (104c) arranged between the top layer (104a) and the bottom layer (104b); the interconnection layer (104c) comprises a plurality of pile filaments (107) extending between a top layer (104a) and a bottom layer (104b), where the top layer (104a) of the spacer fabric layer (104) is defined by a peripheral edge, and where at least one of the liquid spread layer (102) and the pad forming layer (103a-c) of the absorbent pad (103) is arranged to overlap the peripheral edge of the top layer of the spacer fabric layer (104). The present disclosure also relates to a system comprising the NPWT dressing and a method for manufacturing the NPWT dressing.

Description

Technical Field

[0001] The present disclosure generally relates to a negative pressure wound therapy (NPWT) dressing. The invention also relates to a system including such an NPWT dressing and a method of manufacturing an NPWT dressing. Background Art

[0002] Negative pressure wound therapy (NPWT) is a technique for promoting the healing of, for example, surgical, acute, and chronic wounds by applying sub-atmospheric pressure to the wound using a negative pressure pump. Wound healing is achieved by applying negative pressure, such as a vacuum, to the wound through a dressing or covering applied to the wound. Excess wound exudate is thus drawn out, which increases blood flow to the area and promotes the formation of granulation tissue. The NPWT technique also enables the wound to be less externally disturbed and can transport excess fluid away from the wound site.

[0003] So far, the NPWT technique has been mainly applied to patients in a hospital environment. However, recent product developments have enabled the use of this technique by patients in a home environment.

[0004] In a home environment, a portable NPWT device that can be carried by a patient is generally preferred. A portable NPWT device typically includes an absorbent dressing configured to be connected to a negative pressure source by way of a conduit.

[0005] Absorbent dressings for negative pressure wound therapy typically include a spacer fabric material.

[0006] The spacer fabric material is a three-dimensional knitted fabric that includes a top layer and a bottom layer connected by a layer of pile filaments or threads. The pile filaments extending between the top layer and the bottom layer ensure a defined distance is established between the top layer and the bottom layer.

[0007] The spacer fabric layer is compression-resistant and configured to withstand the pressure applied to the dressing during use. After pressure has been applied to the dressing, the spacer fabric material is configured to immediately return to its original shape after the force is removed. In addition, the spacer fabric material ensures that negative pressure can be transmitted to the wound area both under wet and dry conditions.

[0008] However, during the manufacture of an NPWT dressing, the various components of the dressing are typically cut before assembling the dressing. When cutting through the spacer fabric layer, the interconnecting pile filaments extending between the top layer and the bottom layer may lose their anchoring to the top layer or the bottom layer and may protrude outwardly, i.e., project laterally from the spacer fabric material.

[0009] This can cause problems when the dressing is assembled with other dressing components, especially with the backing layer (i.e., the top layer of the dressing).

[0010] If the dressing is a so-called border dressing, i.e., a dressing in which the backing layer and sometimes the wound contact layer extend beyond the profile of the other layers (such as the spacer fabric layer and the absorbent layer) to form a border portion, the protruding fluff filaments may pierce and damage the backing layer of the dressing.

[0011] The backing layer is typically a thin polymer film and is particularly prone to forming small holes. If such small holes are formed in the backing layer, air may leak into the system, causing the treatment to be impeded or even fail. In addition, since rupture of the backing layer usually results in the dressing having to be discarded, the wearing time of the dressing is shortened.

[0012] In view of the above, there is a need for improvements in dressings for negative pressure wound therapy, particularly improvements in the wearing time of such dressings and in preventing damage to the backing layer, so as to achieve stable and reliable negative pressure wound therapy. Summary of the Invention

[0013] In view of the above problems, an object of the present disclosure is to provide improvements in dressings for NPWT applications, particularly improvements in providing an improved wearing time and in preventing tearing of the backing layer, so that the treatment of the entire NPWT system and application works in an effective manner.

[0014] According to a first aspect, there is provided a negative pressure wound therapy (NPWT) dressing configured to be connected to a negative pressure source; the NPWT dressing comprises, from top to bottom, a backing layer, a liquid distribution layer, an absorbent pad comprising one or more pad-forming layers, a spacer fabric layer, and an adhesive skin contact layer; the backing layer and the adhesive skin contact layer are arranged to extend beyond the profile of the liquid distribution layer, the absorbent pad, and the spacer fabric layer to form a border portion, wherein the spacer fabric layer comprises a top layer, a bottom layer, and an interconnecting layer disposed between the top layer and the bottom layer; the interconnecting layer comprises a plurality of fluff filaments extending between the top layer and the bottom layer, wherein the top layer of the spacer fabric layer is defined by a peripheral edge, and wherein at least one of the liquid distribution layer and the plurality of pad-forming layers of the absorbent pad is arranged to overlap the peripheral edge of the top layer of the spacer fabric layer.

[0015] The present invention is based on the recognition that if at least one covering layer, i.e., at least one of the pad-forming layers of the liquid distribution layer or the absorbent pad, overlaps the peripheral edge of the top layer of the spacer fabric, the backing layer can be prevented from being pierced by the fluff filaments of the interconnecting layer of the spacer fabric layer.

[0016] The top layer and the bottom layer of the spacer fabric are typically co-extensive, i.e., the top layer and the bottom layer have the same surface area. Thus, the liquid backing layer or the pad-forming layer of the absorbent pad will also overlap the peripheral edge of the bottom layer of the spacer fabric layer.

[0017] When the spacer fabric is cut into a certain shape before dressing assembly, the tufted filaments extending between the top layer and the bottom layer may lose their anchoring to the top layer and / or the bottom layer. The tufted filaments can protrude outwards, i.e., in the lateral direction, rather than protruding between the top layer and the bottom layer in a defined and "organized" manner. In this regard, the backing layer configured to extend beyond the edges of the spacer fabric layer and other layers (the liquid distribution layer and the pad-forming layer) may be damaged by the laterally extending tufted filaments. The tufted filaments are typically hard and thin and can create small micropores in the thin backing layer, especially in the area near the peripheral edge of the pad-forming layer.

[0018] The overlapping arrangement of the liquid distribution layer and / or the pad-forming layer ensures that the laterally protruding tufted filaments are shielded, thereby protecting the backing layer from being punctured.

[0019] Therefore, the wearing time of the dressing can be increased because the dressing does not need to be discarded before it reaches its full absorption capacity.

[0020] In addition, stable and reliable negative pressure wound therapy is achieved because failures due to air leakage caused by the damaged backing layer are avoided.

[0021] The dressing of the present disclosure is a so-called "border dressing". The border dressing attaches to the skin at the adhesive border portion or over the entire surface of the adhesive skin contact layer of the dressing. For a border dressing, the separation of the dressing can start at the edge of the absorbent pad. During the use of the dressing, for example when the patient moves or bends, the backing layer is subjected to tension. The backing layer typically extends obliquely from the edge of the absorbent pad, and the absorbent pad is usually much thicker than the backing layer. In this way, air cavities can form around the edge of the pad. When the backing layer is stretched, the air cavities increase, which may cause the dressing to separate from the skin. The accumulation of fluid in the air cavities further impairs the wearing time of the dressing. The mechanical tension on the backing layer may also cause shear stress on the adhesive skin contact layer, which in turn leads to separation.

[0022] To solve this problem, the backing layer can be preformed into a certain shape before being assembled with other dressing components, i.e., the liquid distribution layer, the absorbent pad, the spacer fabric layer, and the adhesive skin contact layer.

[0023] Thus, in an embodiment, the backing layer has a central portion and an edge portion surrounding the central portion, wherein the central portion has a preformed shape complementary to at least the shape of the absorbent pad, and wherein the edge portion forms part of the border portion.

[0024] By preforming the backing layer into a shape that matches at least the absorbent pad, the backing layer will conform to the edges of these dressing layers. Accordingly, the backing layer is arranged adjacent to these edges such that there is substantially no or only a minimal gap formed at the periphery of the pad forming layer. Accordingly, the tension formed near the edges of the absorbent pad and the liquid spreading layer is significantly reduced. Accordingly, the risk of separation from the skin and the risk of pressure build-up around the edges of the pad are reduced.

[0025] While this construction can improve the wearing time of the dressing, it also exacerbates the problem outlined above, namely that the backing layer can be pierced and damaged by the protruding fluff filaments. This problem is particularly exacerbated if the backing layer is arranged adjacent to the spacer fabric.

[0026] The overlap of the liquid spreading layer and / or the pad forming layer with respect to the spacer fabric layer ensures that this problem is avoided.

[0027] In an exemplary embodiment, the spacer fabric layer has a thickness t1, and at least one of the liquid spreading layer and the pad forming layer of the absorbent pad is arranged to overlap the peripheral edge by a distance d1, where the distance d1 corresponds to 0.7t1 to 4.0t1, preferably 1.0t1 to 2.0t1.

[0028] A distance d1 within these ranges ensures that the problem of damaging the backing layer is overcome or at least significantly reduced. Furthermore, a distance within these ranges ensures an effective transfer of negative pressure between the negative pressure source and the wound site. If the overlap is too large, the transfer of negative pressure and the applied treatment may be reduced.

[0029] In an exemplary embodiment, the NPWT dressing further includes a coupling member configured to connect the dressing to a negative pressure source, wherein the backing layer and at least a portion of the absorbent pad include an opening under the coupling member; the liquid spreading layer has no opening.

[0030] Openings are typically provided in the absorbent pad to facilitate the transfer of negative pressure. The fact that the liquid spreading layer does not contain any openings prevents gelling particles and unwanted larger particles from entering the coupling member and the tubing connected to the coupling member.

[0031] In an exemplary embodiment, the liquid spreading layer is a continuous layer extending over the entire surface area of the absorbent pad.

[0032] The liquid spreading layer improves the spreading of liquid over a large surface area such that moisture can evaporate through the backing layer in a more efficient manner.

[0033] When the dressing of the present disclosure is used in an NPWT system that includes a remote fluid collection device (such as a canister), a portion of the wound exudate will be conveyed from the dressing to the canister (typically through a tube that connects the dressing to the canister and a negative pressure source). In such cases, the liquid spreading layer ensures that any potential backflow of exudate from the canister to the wound site is spread over a large surface area rather than flowing back to the wound site at a single point. Thus, the wound site is kept relatively dry.

[0034] In an exemplary embodiment, the liquid spreading layer is a nonwoven layer.

[0035] The nonwoven liquid spreading layer helps to drive fluid away from the wound site and the wound pad while ensuring that the maximum capacity of the absorbent dressing can be utilized.

[0036] In addition, the nonwoven layer imparts a properly balanced rigidity to the layer and the dressing itself. More particularly, the nonwoven layer protects the underlying backing layer from being punctured.

[0037] In an exemplary embodiment, the absorbent pad includes a first liquid distribution layer, a superabsorbent layer, and a second liquid distribution layer, where the superabsorbent layer is disposed between the first liquid distribution layer and the second liquid distribution layer, and where either the first liquid distribution layer or the second liquid distribution layer is a nonwoven layer.

[0038] The first liquid distribution layer is configured to absorb and distribute the liquid flowing out from the wound site. The first liquid distribution layer can evenly distribute and spread the wound exudate over a large surface area such that the wound exudate can be absorbed by the superabsorbent layer. The second liquid distribution layer distributes the exudate from the superabsorbent layer such that the exudate is spread over a large area before evaporating from the backing layer.

[0039] In embodiments where the NPWT system further includes a remote fluid collection device (such as a canister), the construction of the absorbent pad ensures an even distribution of liquid within the dressing while also being able to convey the wound exudate to the remote fluid collection device through a tube.

[0040] The absorbent pad, together with the liquid distribution layer covering the absorbent pad, is configured to optimize the distribution of wound exudate within the dressing. In cases where the NPWT dressing is connected to a remote fluid collection device, the construction of the absorbent pad ensures that a large amount of exudate is transferred to the remotely located fluid collection device in a controlled manner. Thus, the absorbent pad is designed to achieve an appropriate balance of liquid distribution between the dressing and the remote fluid collection device, and both the absorbent pad and the remote fluid collection device can act as fluid "compartments" for holding and storing liquid.

[0041] In an exemplary embodiment, both the liquid spreading layer and the nonwoven layer of the absorbent pad are arranged to overlap the peripheral edge of the spacer fabric layer.

[0042] This arrangement can enhance the protection against piercing and rupture of the backing layer.

[0043] In an exemplary embodiment, each of the liquid distribution layer and the absorbent pad of the absorbent pad forms a layer arrangement that overlaps with the peripheral edge of the top layer of the spacer fabric layer.

[0044] This arrangement can improve the shielding of the laterally extending tuft filaments of the interconnecting layer of the spacer fabric. Therefore, the protection against rupture of the backing layer is significantly enhanced.

[0045] In an exemplary embodiment, the combined thickness of the liquid distribution layer and the absorbent pad is greater than the thickness t1 of the spacer fabric layer.

[0046] The combined thickness of the liquid distribution layer and the absorbent pad is significantly greater than the spacer fabric layer and its interconnecting tuft filaments.

[0047] Therefore, a buffering effect is achieved at the peripheral edge of the spacer fabric layer, which prevents the tuft filaments from reaching the covered backing layer.

[0048] In an exemplary embodiment, the dressing includes a conduit, wherein a first distal end of the conduit is connected to a coupling member, and a second distal end of the conduit is configured to be connected to a negative pressure source, wherein the conduit includes a fluid conduit configured to remove fluid from the dressing and an air conduit configured to supply air to the fluid conduit and / or the dressing.

[0049] A small, controlled inflow of air can facilitate more effective extraction of fluid from the wound site and transport of the fluid to a remotely located fluid collection device, such as a canister. The introduction of air can address potential exudate blockages or liquid columns formed in the conduit.

[0050] According to another aspect, there is provided a negative pressure wound therapy (NPWT) system, comprising:

[0051] - a negative pressure wound therapy (NPWT) dressing as described above,

[0052] - a negative pressure source, and

[0053] - a remotely located fluid collection device that is fluidly connected to the negative pressure source and the dressing.

[0054] Thus, the NPWT system includes two exudate storage devices, namely the absorbent pad and the remotely located fluid collection device, such as a canister. This helps to avoid exudate saturation within the dressing, which can ultimately lead to a loss of adhesion to the skin. Providing the remotely located fluid collection device can therefore increase the wearing time of the dressing, as there are two independent fluid handling systems in the NPWT system.

[0055] In an exemplary embodiment, the remotely located fluid collection device is a canister, and wherein the canister and the negative pressure source are arranged within the same device.

[0056] The device is typically portable and may include a housing in which a negative pressure source is disposed. A canister may be removably connected to the housing.

[0057] The removable configuration enables a user or caregiver to remove the canister and empty the collected liquid, and then reattach the canister to the negative pressure source again.

[0058] In an exemplary embodiment, the system may include means for supplying air to the dressing at a rate of 2 ml / min to 7 ml / min during operation.

[0059] A small, controlled air inflow can facilitate more efficient extraction of fluid from the wound site and delivery of the fluid to a remotely located fluid collection device, such as a canister. Avoiding potential blockages in the tubing connecting the dressing to the negative pressure source and the remotely located fluid collection device and ensuring that the desired pressure level is transmitted to the wound site can also be advantageous. In a negative pressure wound therapy system, there is typically a hydrostatic pressure difference introduced by gravity between the pressure in the canister and the pressure at the wound site. This is due to the height difference between the canister and the wound site. Variations in hydrostatic pressure can affect the ability to provide the correct negative pressure level at the wound site. Providing a small air flow or air leak addresses these issues. Additionally, if too much air is introduced, this can have a negative impact on the stability of the system and the pump typically has to be started at a higher frequency.

[0060] According to yet another aspect, there is provided a method for manufacturing a negative pressure wound therapy (NPWT) dressing, wherein the method comprises:

[0061] a) providing a backing layer,

[0062] b) disposing a liquid spreading layer in contact with the backing layer,

[0063] c) disposing an absorbent pad in contact with the liquid spreading layer, the absorbent pad comprising one or more pad-forming layers,

[0064] d) disposing a spacer fabric layer in contact with the absorbent pad, wherein the spacer fabric layer comprises a top layer, a bottom layer, and an interconnecting layer disposed between the top layer and the bottom layer; the interconnecting layer comprises a plurality of tufted filaments extending between the top layer and the bottom layer, wherein the top layer of the spacer fabric layer is defined by a peripheral edge,

[0065] e) disposing an adhesive skin contact layer in contact with the spacer fabric layer,

[0066] wherein the adhesive skin contact layer and the backing layer are arranged to extend beyond the profiles of the liquid spreading layer, the absorbent pad, and the spacer fabric layer to form a boundary portion, and

[0067] wherein at least one of the liquid spreading layer and the pad-forming layer of the absorbent pad is arranged to overlap the peripheral edge of the top layer of the spacer fabric layer.

[0068] In an exemplary embodiment, the backing layer may be preformed into a shape complementary to at least the absorbent pad before or simultaneously with step b) of disposing the liquid dispersion layer in contact with the backing layer.

[0069] Thus, the backing layer will conform to the edges of the absorbent pad, thereby reducing the tension on the backing layer and preventing the formation of gaps around the edges of the absorbent pad.

[0070] In addition to preventing separation from the skin, when the dressing is assembled with other dressing layers, the preforming of the backing layer also prevents the formation of folds in the backing layer.

[0071] In an exemplary embodiment, the backing layer is preformed by:

[0072] a) bringing the backing layer into contact with a molding tool having a shape complementary to at least the absorbent pad, and

[0073] b) applying a vacuum to the backing layer.

[0074] Applying the vacuum enables the backing layer to be stretched and drawn into the molding tool, thereby adopting a shape corresponding to the molding tool. More particularly, the central portion of the backing layer will adopt a shape corresponding to the molding tool; i.e., at least the shape of the absorbent pad. Typically, the molding tool has a shape complementary to the absorbent pad and the liquid dispersion layer.

[0075] This improves the ability of the backing layer to conform to the peripheral edges of the absorbent pad.

[0076] In an exemplary embodiment, steps b)-d) of disposing the liquid dispersion layer, the absorbent pad, and the spacer fabric layer are performed simultaneously with bringing the backing layer into contact with a molding tool having a shape complementary to at least the absorbent pad, and preferably a vacuum is applied to the backing layer simultaneously.

[0077] Thus, the preformed shape of the backing layer is fixed, and the backing layer will conform to the peripheral edges of the absorbent pad.

[0078] Further features and advantages of the present disclosure will become apparent when the appended claims and the following description are studied. Those skilled in the art will appreciate that, without departing from the scope of the present disclosure, different features of the present disclosure can be combined to produce embodiments other than those described hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS

[0079] Various aspects of the present disclosure, including its particular features and advantages, will be readily understood from the following detailed description and the accompanying drawings, in which:

[0080] Figure 1 A negative pressure wound therapy (NPWT) dressing according to an exemplary embodiment of the present disclosure is shown.

[0081] Figure 2 shows Figure 1 an exploded view of the NPWT dressing of

[0082] Figure 3a shows Figure 1 a cross-sectional view of the NPWT dressing of

[0083] Figure 3b and Figure 3c shows Figure 3a an enlarged view of the dressing of

[0084] Figure 4a shows a NPWT dressing having a structure similar to that of the NPWT dressing of Figure 3a but in which the spacer fabric layer has the same outer dimensions as the absorbent pad and the liquid distribution layer.

[0085] Figure 4b and Figure 4c shows Figure 4a an enlarged view of the dressing of

[0086] Figure 5 Conceptually shows a negative pressure wound therapy (NPWT) system according to an exemplary embodiment of the present disclosure.

[0087] Figure 6 shows the test instrument used in Example 2. Detailed Description

[0088] The present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which the presently preferred embodiments of the disclosure are shown. However, the disclosure may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness and to fully convey the scope of the disclosure to those skilled in the art. Like reference numerals refer to like elements throughout.

[0089] Figure 1 - Figure 3 shows a NPWT dressing according to an exemplary embodiment of the present disclosure.

[0090] As Figure 2 , Figure 3a and Figures 4a - 4bAs best shown in, the NPWT dressing 100 includes, from top to bottom, a backing layer 101, a liquid distribution layer 102, an absorbent pad 103 including one or more pad forming layers 103a-c, a spacer fabric layer 104, and an adhesive skin contact layer 105; the backing layer 101 and the adhesive skin contact layer 105 are arranged to extend beyond the profiles of the liquid distribution layer 102, the absorbent pad 103, and the spacer fabric layer 104 to form a border portion 106, wherein the spacer fabric layer 104 includes a top layer 104a, a bottom layer 104b, and an interconnecting layer 104c disposed between the top layer 104a and the bottom layer 104b; the interconnecting layer 104c includes a plurality of tufted filaments 107 extending between the top layer 104a and the bottom layer 104b, wherein the top layer 104a of the spacer fabric layer 104 is defined by a peripheral edge, and wherein at least one of the liquid distribution layer 102 and the one or more pad forming layers 103a-c of the absorbent pad 103 is arranged to overlap the peripheral edge of the top layer of the spacer fabric layer 104.

[0091] As used herein, the term "negative pressure wound therapy dressing" refers to a dressing for negative pressure wound therapy. In the context of the present disclosure, "negative pressure wound therapy" refers to a therapy that utilizes a negative pressure source (such as a vacuum pump) to remove excess fluid from a wound. The wound can be an open wound or a closed wound, i.e., a surgically closed incision, and thus the term also includes "topical negative pressure therapy (TNP)" applications, which is a term commonly used in the context of closed incisions.

[0092] A "spacer fabric layer" is a three-dimensional knitted fabric that includes a top layer and a bottom layer connected by an interconnecting layer of tufted filaments. The tufted filaments extend between the top layer and the bottom layer and ensure that a defined distance is established between the layers. The top layer of the spacer fabric layer is arranged away from the patient's skin in use. The bottom layer of the spacer fabric layer is arranged close to the patient's skin in use.

[0093] The spacer fabric layer is not limited to a particular material. In an exemplary embodiment, the spacer fabric layer includes polyester. The tufted filaments of the interconnecting layer can be polyester monofilament fibers.

[0094] If the spacer fabric layer has a square or rectangular shape, the "peripheral edge" of the top layer of the spacer fabric layer can represent a pair of transverse edges and a pair of longitudinal edges. The spacer fabric layer (and the dressing) is not limited to a square or rectangular shape, but can be circular, oval, or any other conceivable shape. The peripheral edge defines the boundary of the spacer fabric layer.

[0095] The liquid distribution layer or one or more pad forming layers overlap the peripheral edge of the top layer of the spacer fabric layer. The top layer generally coextends with the bottom layer. Thus, the liquid distribution layer or one or more pad forming layers also overlap the peripheral edge of the bottom layer of the spacer fabric layer.

[0096] Figures 4a - 4cShows an NPWT dressing having a structure similar to the dressing of the present disclosure, but wherein the spacer fabric layer 104' has the same outer dimensions as the overlying absorbent pad 103' and the liquid distribution layer 102'.

[0097] As Figure 4b and Figure 4c Best shown in the enlarged views of, some of the tufted filaments 107' of the spacer fabric layer 104' project laterally towards the backing layer 101', which covers and overlaps the peripheral edges of the spacer fabric layer 104' (as well as the absorbent pad 103' and the liquid distribution layer 102').

[0098] Thus, the tufted filaments 107' have lost their attachment to the top layer 104a' and / or the bottom layer 104b' of the spacer fabric layer. This can occur, for example, when the spacer fabric layer is cut into a certain shape during the assembly of the dressing components.

[0099] As a result, as Figure 4b and Figure 4c Shown, the typically very fine and sharp laterally projecting tufted filaments 107' pierce the backing layer 101 and project through the layer, creating small holes, typically micropores. When this occurs, the NPWT dressing usually has to be discarded. The negative pressure source, i.e., the vacuum pump, has to work harder, and the battery will be depleted. Therefore, the applied negative pressure wound therapy usually has to be stopped because air will leak into the system. As a result, the wearing time of the dressing is significantly reduced.

[0100] As Figures 3a - 3c Best shown in, by arranging at least one of the one or more pad forming layers 103a - c of the liquid distribution layer 102 and the absorbent pad 103 such that the at least one layer overlaps the peripheral edge of the top layer 104a of the spacer fabric layer 104, the above problems are overcome or at least significantly reduced.

[0101] As described above, since the top layer 104a co - extends with the bottom layer 104b of the spacer fabric layer 104, the one or more pad forming layers 103a - c of the liquid distribution layer 102 and / or the absorbent pad 103 also typically overlap the bottom layer 104b of the spacer fabric layer 104.

[0102] With this structure, the tufted filaments 107 are prevented from piercing the backing layer 101.

[0103] As can be seen in Figures 3a - 3c the backing layer 101 is arranged adjacent to and conforms to the peripheral edges of the liquid distribution layer 102 and the absorbent pad 103 such that there are substantially no gaps.

[0104] The backing layer 101 may have a central portion and an edge portion surrounding the central portion, wherein the central portion has a preformed shape complementary to the shape of at least the absorbent pad 103, and wherein the edge portion of the backing layer 101 forms part of the boundary portion 106 of the dressing.

[0105] Typically, the central portion has a preformed shape complementary to the shapes of the liquid distribution layer 102 and the absorbent pad 103.

[0106] As used herein, the term "complementary to the shapes of the liquid distribution layer and the absorbent pad" means that the central portion of the backing layer has outer dimensions that are substantially the same as the outer dimensions of the liquid distribution layer and the absorbent pad, i.e., width and length. The depth of the backing layer in the central portion corresponds to the thickness of the liquid distribution layer and the absorbent pad, and preferably also corresponds to the thickness of the spacer fabric layer.

[0107] This arrangement prevents the formation of gaps in the regions around the peripheral edges of the absorbent pad and the liquid distribution layer.

[0108] Such gaps may lead to the separation of the dressing from the skin, thereby compromising the wearing time of the dressing. However, the tight adhesion of the backing layer to these dressing layers also exacerbates the problem of backing layer piercing.

[0109] As Figure 3b shown, the spacer fabric layer has a thickness t1, and at least one of the layers 103a-c of the liquid distribution layer and the absorbent pad 103 may be arranged to overlap the peripheral edge by a distance d1, where the distance d1 corresponds to 0.7t1 to 4.0t1, preferably 1.0t1 to 2.0t1.

[0110] The thickness t1 is measured under dry conditions and without the application of pressure.

[0111] The thickness t1 of the spacer fabric layer corresponds to the combined thickness of the top layer, the interconnecting layer, and the bottom layer.

[0112] The thickness t1 of the spacer fabric layer may be 1.5 mm to 4 mm, preferably 2 mm to 3 mm. The basis weight of the spacer fabric layer may be 150 gsm to 500 gsm, for example 200 gsm to 350 gsm.

[0113] The interconnecting layer of the pile filaments may have a fineness of 200 to 500 denier, for example 250 to 350 denier.

[0114] Between 0.7t1 and 4.0t1, preferably between 1.0t1 and 2.0t1, the distance d1 prevents the backing layer from being ruptured by the tufted filaments of the spacer fabric and also ensures that a large part of the spacer fabric layer is used for the transmission of negative pressure. If the overlap is too large, the transmission of negative pressure and the effect of the applied treatment may be reduced. The overlap is generally greater than the length of the tufted filaments of the interconnecting layer 104c of the spacer fabric layer 104.

[0115] As Figure 2 As best shown in

[0116] and FIG. 3, the NPWT dressing may further include a coupling member 108 configured to connect the dressing to a negative pressure source, wherein the backing layer 101 and at least a portion of the absorbent pad 103 include an opening 109 below the coupling member 108; the liquid distribution layer 102 has no opening. Figure 2 In

[0117] the absorbent pad 103 includes three layers, each layer including an opening. However, it is also conceivable that openings are provided only in one or two layers of the absorbent pad 103.

[0118] The fact that the liquid distribution layer 102 does not contain any openings prevents gelling particles and undesired larger particles from entering the conduit 110 of the dressing 100.

[0119] In embodiments where the NPWT system includes a remote fluid collection device (such as a canister), it also prevents potential backflow of exudate.

[0120] If a person wearing the dressing disconnects the dressing from the negative pressure source and the canister, backflow of exudate may occur, i.e., exudate flows from the conduit to the dressing. For example, if the patient wants to take a shower or change clothes, he / she can disconnect the NPWT dressing. The liquid layer 102 ensures that such backflow of exudate is spread out rather than flowing back to the wound site at one point. In this way, the wound site can be kept relatively dry.

[0121] As Figure 2 and shown in FIG. 3, the liquid distribution layer 102 may be configured to extend over the entire surface area of the absorbent pad 103.

[0122] The liquid distribution layer 102 preferably extends across and covers the opening 109 in the absorbent pad 103.

[0123] In an exemplary embodiment, the liquid spreading layer 102 and the absorbent pad 103 have the same outer dimensions.

[0124] The liquid spreading layer 102 is configured to improve the spreading of wound exudate and create a larger surface area from which moisture can evaporate through the backing layer 101.

[0125] The liquid spreading layer 102 is preferably a hydrophilic and porous layer. The liquid spreading layer 102 can be a fibrous material.

[0126] In an embodiment, the liquid spreading layer 102 is a non-woven layer.

[0127] The non-woven layer provides rigidity to the dressing, and in the case where the non-woven layer is arranged to overlap the peripheral edge of the top layer of the spacer fabric layer, the non-woven layer enhances the protection of the backing layer and prevents the piercing or rupture of the backing layer.

[0128] In addition, the non-woven liquid spreading layer 102 has the ability to distribute fluid throughout most of the material and transfer exudate to a conduit connecting the dressing to a remotely located fluid collection device (if present) in a controlled manner. The liquid spreading layer 102 helps to drive fluid away from the wound site and the absorbent pad 103 while ensuring that the maximum capacity of the absorbent dressing can be utilized.

[0129] The liquid spreading layer 102 can include meltblown, spunbonded, or hydroentangled non-woven fabrics. Examples of suitable polymers for non-woven fabrics are polyethylene, polyester, polypropylene, and other polyolefin homopolymers and copolymers. For example, a non-woven web comprising thermoplastic fibers including polypropylene and polyethylene fibers or mixtures thereof can be used. The web can have a high content of thermoplastic fibers and contain at least 50%, such as at least 70%, of thermoplastic fibers. The non-woven fabric can be a mixture of polyester and fiber gum, for example in a ratio of 70:30. The basis weight of the non-woven fabric can be in the range of 10 g / m 2 to 80 g / m 2 and, for example, 20 g / m 2 to 50 g / m 2 The liquid spreading layer can also be a spunbond-meltblown web or a spunbond-meltblown-spunbond (SMS) web.

[0130] The absorbent pad 103 can include one or more layers, at least one of which is a superabsorbent layer comprising a superabsorbent polymer (SAP).

[0131] "Superabsorbent polymer" or "SAP" is a polymer that can absorb up to 300 times its own weight in an aqueous fluid. Superabsorbent polymers are composed of water-swellable and water-insoluble polymers that are capable of absorbing large amounts of fluid when forming hydrogels. The superabsorbent polymers used according to the present disclosure can be inorganic or organic crosslinked hydrophilic polymers such as polyvinyl alcohol, polyethylene oxide, crosslinked polyacrylate, etc. Generally, the superabsorbent (SAP) includes sodium acrylate. The SAP material can be in the form of granules, fibers, sheets, etc. Preferably, the SAP material is in the form of superabsorbent polymer (SAP) granules. The size of the superabsorbent granules can range from 45 μm to 850 μm, preferably from 150 μm to 600 μm.

[0132] Preferably, the absorbent pad includes at least one superabsorbent layer 103b and at least one liquid distribution layer.

[0133] As shown in Figure 3, the absorbent pad 103 can include a first liquid distribution layer 103a, a superabsorbent layer 103b, and a second liquid distribution layer 103c, wherein the superabsorbent layer 103b is disposed between the first liquid distribution layer 103a and the second liquid distribution layer 103c.

[0134] Preferably, the first liquid distribution layer 103a or the second liquid distribution layer 103c is a non-woven fabric layer.

[0135] The absorbent pad 103 is configured to absorb wound exudate and distribute such wound exudate in an effective manner. In embodiments where the NPWT system includes a canister, the absorbent pad 103 can be used as a temporary reservoir to hold and distribute the exudate while also ensuring a controlled delivery of the liquid towards the canister via the tubing.

[0136] The exudate entering the liquid distribution layer 103a from the wound site is evenly distributed before reaching the superabsorbent layer 103b, thereby creating a larger surface area towards the superabsorbent layer 103b.

[0137] In an exemplary embodiment, the first liquid distribution layer 103a is disposed below the superabsorbent layer 103b and has a greater liquid spreading ability than the second liquid distribution layer 103c. Thus, an absorbent pad with a liquid spreading gradient is obtained, and the liquid spreading gradient affects the ability of the absorbent pad 103 to hold liquid in the dressing and remove liquid from the dressing, respectively.

[0138] For example, the first liquid distribution layer 103a can include a non-woven fabric. The grammage of the non-woven fabric can range from 20 to 50 gsm, for example, from 30 to 40 gsm.

[0139] The second liquid distribution layer 103c can be a thin fabric or nonwoven layer. Generally, the spreading ability of the upper second liquid distribution layer 103c is lower than that of the lower first liquid distribution layer 103a.

[0140] Layer 103c is also used to prevent the leakage of SAP particles from the superabsorbent layer 103b. The SAP particles of the superabsorbent layer 103b chemically bind to the exudate that enters the superabsorbent layer 103b, thereby forming an aqueous gel. Layer 103c prevents the gelled particles from moving towards the backing layer 101 and towards the coupling member 108 including the conduit 110. This prevents the undesired blockage of the gel particles within the conduit 110. The liquid distribution layer 103c creates a greater indirect surface for distributing liquid towards the backing layer 101 of the dressing 100. Layer 103c can also be used as a "support layer" and as a carrier during the manufacturing process.

[0141] The respective layers of the absorbent pad form a complex liquid absorption and retention structure, thereby improving liquid handling and distribution. In embodiments where the NPWT system includes a remote fluid collection device, a controllable distribution of exudate retention within the dressing and removal of exudate from the dressing is achieved.

[0142] The absorbent pad 103 can be embossed. In other words, the surface of the absorbent pad 103 is structured and can include a plurality of depressions and ridges (not shown). This is beneficial because the absorbent pad 103 including multiple layers may become hard and thick as the basis weight increases. Embossing enables the absorbent pad to maintain its shape while being flexible. The embossed absorbent pad 103 also improves the liquid spreading or liquid distribution ability.

[0143] The superabsorbent layer 103b can be an airlaid superabsorbent layer. In an embodiment, the airlaid superabsorbent layer 103b includes superabsorbent particles, cellulose fibers, and bicomponent fibers.

[0144] For example, the airlaid superabsorbent layer can include:

[0145] - 30 wt% to 50 wt%, preferably 35 wt% to 50 wt% of superabsorbent particles

[0146] - 30 wt% to 50 wt%, preferably 40 wt% to 50 wt% of cellulose fibers

[0147] - 3 wt% to 10 wt%, preferably 5 wt% to 8 wt% of bicomponent fibers

[0148] - 3 wt% to 8 wt% of polyethylene.

[0149] Such a superabsorbent layer can improve the liquid handling performance and properly distribute the liquid. In addition, it prevents gel blockage and prevents the absorbent pad from collapsing when handling a large amount of fluid.

[0150] The bicomponent fibers act as an adhesive to provide integrity to the SAP layer, especially in the wet state. The bicomponent fibers can be made of polyethylene and polyethylene terephthalate (PE / PET).

[0151] In an exemplary embodiment, the absorbent pad 103 may include an additional pad-forming layer (not shown).

[0152] To provide additional protection and prevent the backing layer from being pierced by the pile filaments of the spacer fabric layer, both the liquid distribution layer 102 and the nonwoven layer of the absorbent pad 103 may be arranged to overlap the peripheral edge of the top layer 104a of the spacer fabric layer 104.

[0153] Thus, at least two nonwoven layers are arranged to overlap the peripheral edge of the top layer of the spacer fabric.

[0154] As Figure 2 and Figures 3a - 3c shown, each pad-forming layer of the liquid distribution layer 102 and the absorbent pad 103 is arranged to overlap the peripheral edge of the top layer 104a of the spacer fabric layer 104.

[0155] This arrangement enhances the protection of the backing layer.

[0156] The combined thickness of the liquid distribution layer 102 and the absorbent pad 103 is preferably greater than the thickness t1 of the spacer fabric layer 104c.

[0157] Thus, the pile filaments are prevented from extending through the thicker overlapping absorbent pad and liquid distribution layer.

[0158] The thickness of the absorbent pad can be 2 mm to 10 mm, such as 3 mm to 6 mm. The thickness is measured under dry conditions.

[0159] The thickness of the liquid distribution layer can be 0.1 mm to 2 mm, such as 0.2 mm to 1 mm. The thickness is measured under dry conditions.

[0160] As Figure 1 best shown in, the dressing may include a conduit 110, wherein a first distal end of the conduit 110 is connected to the coupling member 108 and a second distal end is configured to be connected to a negative pressure source, wherein the conduit 110 includes a fluid conduit 110a configured to remove fluid from the dressing and an air conduit 110b configured to supply air to the fluid conduit 110a and / or the NPWT dressing 100.

[0161] The NPWT dressing 100 of the present disclosure is preferably adapted for use in an NPWT system including a remote fluid collection device.

[0162] As used herein, the term "remote fluid collection device" means a fluid collection device that is arranged at a distance from the dressing, such as between the dressing and the negative pressure source or connected to the negative pressure source. The negative pressure source and the remote fluid collection device may be arranged in the same NPWT device. Typically, the remote fluid collection device is a canister.

[0163] The conduit 110 is configured to transmit negative pressure to the dressing and the wound site.

[0164] The conduit 110 and / or the coupling member 108 may be any suitable flexible conduit made of an elastomeric material and / or a polymeric material. The conduit is attached to the coupling member 108. The conduit 110 may be fixedly attached to the coupling member 108 or detachably attached to the coupling member 108.

[0165] The coupling member 108 generally includes an attachment portion configured to attach to the backing layer of the dressing. The coupling member may be adhesively attached to the backing layer. The coupling member may also include a fluid inlet and a fluid outlet that are configured to connect to the conduit 110, i.e., to the air conduit 110b and the fluid conduit 110a respectively.

[0166] The coupling member may have the structure defined in the EP application with application number 13152841.6.

[0167] The first distal end of the conduit 110 may be connected to a first connector portion 111a. The first connector portion 111a may be configured to connect to a second connector portion (not shown) associated with the remote fluid collection device (i.e., the canister) and, in an embodiment, to the negative pressure source.

[0168] In the various embodiments described above, the backing layer generally includes or consists of a polymer film. The polymer film may include polyurethane, polyamide, and / or polyethylene. The backing layer may also be a laminate of a polyester-based nonwoven material and at least one polymer film.

[0169] Preferably, the backing layer includes polyurethane. The backing layer may be a polyurethane film.

[0170] The thickness of the backing layer may be in the range of 10 μm to 40 μm, preferably 15 μm to 30 μm.

[0171] The backing layer is the outermost layer of the dressing and is configured to face away from the wearer's skin. The backing layer may also be referred to as the top layer of the dressing.

[0172] As measured by ISO 527-3 / 2 / 20, the backing layer may have a tensile strength of 30 MPa to 70 MPa, preferably 35 to 55 MPa, in the machine direction (MD) and / or the cross-machine direction (CD). The tensile strength is measured using 15 mm wide strips.

[0173] Preferably, the backing layer 101 has sufficient "strength" to withstand the forces applied to the backing layer during patient movement, while also allowing flexibility and a sufficient degree of stretchability.

[0174] Tensile strength within the above range can prevent tearing or rupture of the backing layer. However, the backing layer must still be flexible enough to allow the dressing to conform to the user's movement or to the bending of a joint (such as the knee).

[0175] A thin layer of an adhesive (such as a polyacrylate adhesive) can be applied to the backing layer to attach the backing layer to the adhesive skin contact layer and / or the liquid spreading layer beneath the backing layer.

[0176] In the various embodiments described above, the adhesive skin contact layer preferably comprises a polysiloxane-based adhesive, such as a polysiloxane gel.

[0177] An adhesive skin contact layer comprising a polysiloxane gel is skin-friendly and easy to remove without causing trauma. It adheres well to the skin so that the dressing stays in place, but is configured to maintain its adhesiveness upon repeated removal and reapplication.

[0178] As shown, for example Figure 3a the adhesive skin contact layer 105 can comprise two layers. For example, the adhesive skin contact layer 105 can comprise a polymer film 105a and a polysiloxane gel layer 105b; the polysiloxane gel layer 105b is arranged to contact the skin of the wearer.

[0179] The polymer film 105a is preferably a breathable film. The polymer film can comprise, for example, polyethylene, polyamide, polyester or polyurethane. Preferably, the polymer film comprises polyurethane.

[0180] The thickness of the polymer film can be from 15 μm to 100 μm, such as from 20 μm to 80 μm, preferably from 20 μm to 60 μm.

[0181] Examples of suitable polysiloxane gels for the adhesive skin contact layer 105 include two-component RTV systems such as Q72218 (Dow Corning) and SilGel 612 (Wacker Chemie AG) mentioned herein, and NuSil polysiloxane elastomers. In an embodiment of the present invention, the adhesive can comprise a polysiloxane gel having a softness (penetration) of 8 mm to 22 mm, such as 12 mm to 17 mm, which softness is measured by a method based on ASTM D 937 and DIN 51580, which method is described in European patent application No. 14194054.4.

[0182] The thickness of the adhesive skin contact layer is typically at least 20 μm. Generally, the thickness of the adhesive skin contact layer is from 100 μm to 200 μm.

[0183] In a preferred embodiment, and as best shown in FIG. 3, the adhesive skin contact layer 105 includes a plurality of perforations 119 in the area under the absorbent pad 103, but there are no perforations in the area forming the boundary portion 106.

[0184] The absence of perforations in the boundary portion 106 of the dressing is beneficial to improving the adhesion at the boundary of the dressing, thereby enhancing the retention ability of the dressing.

[0185] In an embodiment where the adhesive skin contact layer 105 includes a polymer film 105a and a polysiloxane gel layer 105b, the perforations 119 extend through the polymer film 105a and the polysiloxane gel layer 105b.

[0186] Figure 5 Conceptually shown is a negative pressure wound therapy (NPWT) system according to the present disclosure.

[0187] The negative pressure wound therapy (NPWT) system 200 includes the NPWT dressing 100 as described above. The dressing 100 is applied to the knee of a patient 117.

[0188] The NPWT system 200 includes

[0189] - the negative pressure wound therapy (NPWT) dressing 100 as described above,

[0190] - a negative pressure source

[0191] - a remote fluid collection device 113, the remote fluid collection device 113 being fluidly connected to the negative pressure source and the dressing 100.

[0192] The negative pressure source can be a negative pressure pump, which is adapted to establish a negative pressure when the negative pressure pump is in an activated state. The negative pressure pump can be any type of pump that is biocompatible and maintains or draws a sufficient and therapeutic vacuum level. Preferably, the negative pressure level to be achieved is in the range of between about -20 mmHg and about -300 mmHg. In an embodiment of the present disclosure, a negative pressure range between about -80 mmHg and about -180 mmHg, preferably between about -100 mmHg and -150 mmHg, more preferably between -110 mmHg and -140 mmHg is used.

[0193] The negative pressure pump can be a diaphragm type or a peristaltic type pump.

[0194] As used herein, the term "fluidly connected" should be construed broadly and can include, for example, any form of tubing, conduit, or passageway that provides a fluid connection / communication between a remote fluid collection device 113 and a negative pressure source and a dressing 100.

[0195] The remote fluid collection device 113 can be any type of fluid container, such as a canister. Alternatively, it can be an absorbent material present within the tubing of an NPWT dressing or an NPWT system, or a dressing or absorbent pad disposed between the dressing of the present disclosure and the canister. Generally, the remote fluid collection device 113 is a canister.

[0196] In Figure 5 it, the negative pressure source and the canister 113 are disposed within the same device 114. The negative pressure source is included within the housing 112 of the device 114. The device 114 is typically a portable device.

[0197] The canister 113 is preferably removably connected to the housing 112.

[0198] In other words, the canister 113 is releasably connected to the housing 112. The detachable connection can be by conventional means including friction fit, bayonet coupling, snap fit, barb connector, etc. The detachable configuration enables the user or caregiver to remove the canister 113 and empty the collected liquid, and then reattach the canister 113 to the housing 112 again.

[0199] The canister 113 can be formed of, for example, molded plastic, etc. The canister 113 is preferably at least partially transparent / translucent to enable observation of the interior of the canister 113, thereby helping the user to determine the remaining capacity of the canister 113.

[0200] For example, the internal volume of the canister 113 can be between 30 ml - 300 ml, such as between 40 ml - 150 ml. The internal volume of the canister 113 can vary according to the type of wound. In an embodiment, the canister 113 includes a liquid absorbent material. In a possible embodiment, at least 75% of the internal volume of the canister 113 is occupied by the liquid absorbent material.

[0201] The NPWT device 114 can be connected to the NPWT dressing 100 via a tubing 110.

[0202] In Figure 5 the illustrated embodiment, the NPWT system includes a connector unit 111 located at a position between the dressing 100 and the NPWT device 114. The connector unit 111 can include a first connector portion associated with the tubing of the canister and / or the negative pressure source (in Figure 1is shown as 111a) and a second connector portion (not shown). The first connector portion and the second connector portion are preferably detachably connected so that the dressing can be easily disconnected from the NPWT device 114. This is beneficial in a portable NPWT system because when the user is about to take a shower or for some other reason, he or she can decide to disconnect the dressing from the device 114.

[0203] In Figure 5 , the conduit 110 is a double conduit, while the conduit 115 between the NPWT device 114 and the connector unit 111 is a single conduit. The NPWT system is in no way limited to this configuration, but may include a single or double conduit between the NPWT device 114 and the dressing 100. The NPWT system is also not limited to using the connector unit 111. In an embodiment, the conduit 110 may be configured to extend all the way to the NPWT device 114.

[0204] The NPWT system 400 preferably includes means for supplying air to the dressing at a rate of 2 ml / min to 7 ml / min during operation.

[0205] Preferably, the means for supplying air to the dressing is configured to supply air at a rate of 2 - 7 ml, preferably 3 - 5 ml, under a negative pressure of - 80 mmHg to - 180 mmHg, preferably - 100 mmHg to - 150 mmHg, more preferably - 110 mmHg to - 140 mmHg.

[0206] In Figure 5 In the NPWT system 200 shown, ambient air is introduced into the system through the connector unit 111 (shown by arrow 116). For example, the first connector portion and / or the second connection portion may include an air filter (not shown) configured to control the supply of air to the dressing 100 and / or the first conduit 110. The first connector portion and / or the second connector portion may, for example, include an air inlet in which an air filter is arranged.

[0207] The air filter may include a hydrophobic and porous material, where the pore size is in the range of 2 μm to 20 μm, preferably in the range of 5 μm to 12 μm. The pore size of the filter is measured in the non - compressed state.

[0208] The air filter preferably includes polyethylene, preferably sintered polyethylene.

[0209] The air filter ensures that the air supply is in the range of 2 - 7 ml / min during operation, for example, under a negative pressure of - 80 mmHg to - 150 mmHg, for example, - 100 mmHg to - 130 mmHg.

[0210] It should be noted that air can be introduced into the system in alternative ways, and the air filter can be arranged at alternative positions in the system. In an embodiment, the regulation of the air supply can be controlled by the NPWT device 114.

[0211] During use, the dressing 100 is arranged at the wound site of the user / patient 117, forming a sealed space. Pipelines (110 and 115) are provided to fluidly connect the dressing 100 to the NPWT device 114, for example, to the inlet of the NPWT device 114. Then, the NPWT device 114 is started, for example, by a caregiver / user by pressing the start / pause button 118. Thereby starting the negative pressure pump. When started, the negative pressure pump will start to discharge air through the canister 113, the pipelines (110 and 115), and the sealed space formed by the dressing 100. Thus, a negative pressure will be generated within the sealed space. If there is wound fluid at the wound site, this fluid can be at least partially "drawn" from the wound site through the pipelines (110 and 115) into the canister 113. The amount of fluid, i.e., exudate, drawn from the wound and collected in the canister 113 will depend on the type of wound being treated and the type of wound dressing being used.

[0212] In the context of the present disclosure, a substantially equal balance between the liquid distributions is desired. A suitable filter member (not shown) can be arranged between the canister 113 and the negative pressure pump to ensure that no liquid can pass from the canister 113 to the negative pressure pump.

[0213] According to another aspect, a method for manufacturing a negative pressure wound therapy (NPWT) dressing is provided, wherein the method comprises:

[0214] a) providing a backing layer 101,

[0215] b) arranging a liquid spreading layer 102 in contact with the backing layer 101,

[0216] c) arranging an absorbent pad 103 in contact with the liquid spreading layer 102, the absorbent pad 103 comprising one or more pad-forming layers 103a-c,

[0217] d) arranging a spacer fabric layer 104 in contact with the absorbent pad 103, wherein the spacer fabric layer 104 comprises a top layer 104a, a bottom layer 104b, and an interconnecting layer 104c arranged between the top layer 104a and the bottom layer 104b; the interconnecting layer 104c has a height h1 and comprises a plurality of tufted filaments 107 extending between the top layer 104a and the bottom layer 104b, wherein the top layer 104a of the spacer fabric layer 104 is defined by a peripheral edge,

[0218] e) Arrange the adhesive skin contact layer 105 in contact with the spacer fabric layer 104, wherein the adhesive skin contact layer 105 and the backing layer 101 are arranged to extend beyond the contours of the liquid distribution layer 102, the absorbent pad 103, and the spacer fabric layer 104 to form a border portion 106, and

[0219] wherein at least one of the liquid distribution layer and the pad forming layer of the absorbent pad 103 is arranged to overlap the peripheral edge of the top layer 104a of the spacer fabric layer 104.

[0220] The method can be automatic, semi-automatic, or manual.

[0221] The various layers can be attached in a manner known in the art. For example, the layers can be adhesively attached. In an exemplary embodiment, hot melt adhesives (such as polyacrylates) are used to attach the dressing layers to each other. In the border portion 106, the backing layer 101 and the adhesive skin contact layer 105 can be adhesively attached.

[0222] The liquid distribution layer 102, the absorbent pad 103, and the spacer fabric layer 104 are typically cut into a certain shape prior to the process of manufacturing the NPWT dressing of the present disclosure.

[0223] To improve the conformity of the backing layer to the pad edge, the backing layer 101 can be preformed into a shape complementary to at least the shape of the absorbent pad 103 before or simultaneously with arranging the liquid distribution layer 102 in contact with the backing layer 101.

[0224] In an exemplary embodiment, the backing layer 101 is preformed by:

[0225] a) bringing the backing layer 101 into contact with a molding tool having a shape complementary to at least the absorbent pad 103, and

[0226] b) applying a vacuum to the backing layer 101.

[0227] The molding tool can have a depth corresponding to the combined thickness of the backing layer, the liquid distribution layer, the absorbent pad, and the spacer fabric layer.

[0228] The molding tool can have a width and length corresponding to the width and length of the liquid distribution layer and the absorbent pad.

[0229] The surface of the molding tool corresponds to the shape of the central portion of the backing layer in which the liquid distribution layer, the absorbent pad, and the spacer fabric layer will be arranged.

[0230] Preferably, the molding tool includes foam. This is to prevent the backing layer from cracking during dressing assembly.

[0231] The step of applying a vacuum to the backing layer 101 draws the backing layer 101 into the molding tool such that the central portion of the backing layer 101 adopts the shape of the molding tool.

[0232] It is also conceivable to apply heat during step b) to improve the process of preforming the backing layer.

[0233] The steps b)-d) of arranging the liquid distribution layer 102, the absorbent pad 103, and the spacer fabric layer 104 can be carried out while bringing the backing layer 101 into contact with a molding tool having a shape complementary to at least the shape of the absorbent pad 103, and preferably while applying a vacuum to the backing layer 101 at the same time.

[0234] Applying a vacuum can stretch the backing layer and cause the backing layer to adopt a preformed shape that matches the shape of the absorbent pad and preferably also the liquid distribution layer.

[0235] According to yet another aspect, there is provided a kit comprising a negative pressure wound therapy (NPWT) dressing as described above and at least one additional component selected from a negative pressure source, a canister, a battery, and / or an adhesive tape.

[0236] The NPWT dressing preferably includes a pre-attached conduit 110. This enables rapid assembly of the components of the kit.

[0237] The kit may also include a negative pressure device 114. The negative pressure device 114 may include a negative pressure source and a canister.

[0238] The kit may include additional components such as an additional battery for powering the NPWT device 114 and an adhesive tape for improving the adhesion between the border portion of the dressing and the skin of the wearer.

[0239] The kit may be suitable for home care, but may also be advantageously used in a hospital or nursing facility environment. The NPWT device is adapted to be carried by a user, for example, in a pocket, a belt, a strap, or the like. The NPWT dressing and the other components of the kit can be easily assembled by the user.

[0240] The NPWT device 114 used in the kit (and NPWT system) of the present disclosure includes features and components necessary for controlling the operation. For example, the NPWT device may include a control unit electrically connected to a battery. Such a control unit may include a microprocessor, a microcontroller, a programmable digital signal processor, or another programmable device. Additionally, the NPWT device 114 may include at least one pressure sensor arranged in fluid connection with a negative pressure pump.

[0241] Example

[0242] Example 1: Evaluation of backing layer rupture in a comparative wear test

[0243] Wear tests were conducted using a dressing according to the present disclosure (having the general structure as shown) (hereinafter referred to as Dressing A) and a comparative dressing (having the general structure as shown) (hereinafter referred to as Dressing B). Figure 3a shown)(hereinafter referred to as Dressing B) for wear testing. Figure 4a shown)(hereinafter referred to as Dressing B) for wear testing.

[0244] The dressings are similar in structure, differing only in the arrangement of the spacer fabric layer.

[0245] Dressing A and Auxiliary Dressing B respectively include, from bottom to top, an adhesive skin contact layer (including a polyurethane film and a polysiloxane gel layer), a spacer fabric layer, an absorbent pad (including a non-woven liquid spreading layer, a superabsorbent layer, and a thin fabric layer), a non-woven liquid spreading layer, and a backing layer. Both dressings include pre-attached tubes, which include an air conduit and a fluid conduit.

[0246] In Dressing A, the absorbent pad and the liquid spreading layer are arranged to overlap the spacer fabric layer by 3 mm. This distance is measured from the outer peripheral edge of the top layer of the spacer fabric layer.

[0247] In Dressing B, the absorbent pad, the liquid spreading layer, and the spacer fabric layer extend together in length and width.

[0248] The thickness of the spacer fabric layer (in both Dressing A and B) is 2.4 mm.

[0249] The dressings were attached to the front knees of a number of test subjects with the legs bent at 120 degrees (the dressing tubes pointing upward). The tubes were connected to a portable negative pressure device through a connector (designated as 111 in Figure 5 ). The pump used was of the diaphragm type. A tank configured to store 50 mL of liquid (as disclosed in Figure 5 ) was connected to the pump. The connector portion attached to the distal end of the dressing tube included an air filter, and ambient air was introduced into the connector and the system such that air was supplied to the dressing in the range of 2 mL / min - 7 mL / min during operation (by means of the conduit).

[0250] The pump was started, and a negative pressure of 125 mmHg was applied to the dressing.

[0251] Dressing A was tested on 14 subjects, and Dressing B was tested on 10 subjects.

[0252] The dressings were worn on the knees of the test subjects for 72 hours, and the dressings were subjected to movement and stress. At the end of the test period, the micro-leakage of the dressings was evaluated, i.e., the micropores generated in the backing layer during wear.

[0253] To identify the formation of micropores in the backing layer, each dressing sample was wetted with a colored liquid from the outside of the backing layer. By virtue of the negative pressure applied in the wound pad, the liquid easily entered the pores formed in the backing layer and stained / colored the wound pad, which enabled visual identification of microleakage.

[0254] As shown in Table 1 below, significant improvement in preventing the rupture of the backing layer was observed using the dressing according to the present disclosure (Dressing A).

[0255]

[0256] Table 1: Micropore formation in the backing layer after 72 hours of wearing time

[0257] Example 2: Evaluation of backing layer rupture in a simulated wear test

[0258] A simulated wear test was also conducted, in which stress and flexion were repeatedly applied to the dressings (Dressing A and Auxiliary Dressing B) by Figure 6 the test instrument shown.

[0259] Test instrument 120 includes a plastic plate 121 having a cylindrical hinge 122, and the size of the cylindrical hinge 122 simulates a hinged joint, i.e., the knee. A polyurethane plastic film 123 was attached to the upper surface of the plate 121 to simulate the skin and achieve an airtight seal. The hinge was attached to a tensile tester to cycle the hinge at a consistent and predetermined speed.

[0260] The dressing 100 was applied with the hinge at an angle of 120 degrees.

[0261] The tubing was connected to the negative pressure device in the same manner as described in Example 1.

[0262] During operation, air was supplied to the dressing (through the catheter) in the range of 2 - 7 mL / min. The pump was started, and a negative pressure of 125 mmHg was applied to the dressing.

[0263] The hinge was cycled at a speed of 2000 mm / min, and the hinge was changed from a first position at an angle of 15 degrees to a second position at an angle of 180 degrees 250 times or until leakage occurred. The hinge remained in each position for one second. Five dressings in each dressing category (Dressing A and B respectively) were tested.

[0264] At predefined intervals between cycles (once every 10 cycles until 100 cycles, then once every 50 cycles), the microleakage of the dressing was studied, i.e., the small holes generated in the backing layer during wearing. To identify the rupture of the backing layer, as described above for Example 1, each dressing sample was wetted with a colored liquid from the outside of the backing layer.

[0265] As shown in Table 2 below, significant improvement in preventing rupture of the backing layer was observed using the dressing according to the present disclosure (Dressing A).

[0266]

[0267] Table 2: Micropore formation in the backing layer during simulated wear testing

[0268] Example 3: Negative pressure decay evaluation

[0269] Regarding Dressing A and Dressing B, negative pressure decay was measured after repeatedly opening and closing the negative pressure source. This was to apply stress to the backing layer and force the wound pad to repeatedly contact the backing layer.

[0270] The dressing was applied to a Plexiglas plate. The tubing was connected to the mobile negative pressure device in the same manner as described in Example 1.

[0271] A pressure sensor source was connected to the dressing to measure the negative pressure in the dressing and the system.

[0272] The pump was started, and a negative pressure of 125 mmHg was applied to the dressing. The negative pressure source was closed, and after 10 minutes, the micropores of the dressing were tested with a colored liquid from the outside of the backing layer in the same manner as described regarding Example 1.

[0273] This process was repeated 20 cycles at 125 mmHg and then 3 more cycles at 180 mmHg.

[0274] Five dressings in each dressing category (A and B) were evaluated.

[0275] Results similar to those in Example 2 regarding micropore formation in the backing layer were obtained (see Table 3 below).

[0276] For the dressings with the backing layer punctured (Dressing B), the negative pressure significantly decayed (see Table 3).

[0277] Therefore, using the dressing according to the present disclosure (Dressing A), the backing layer was prevented from becoming ruptured after stress was applied to the dressing by repeatedly cycling the application and removal of negative pressure. In addition, no significant decay of the negative pressure was observed.

[0278]

[0279]

[0280] Table 3: Negative pressure decay and micropore formation in the backing layer

[0281] Example 4: Negative pressure distribution

[0282] System testing was performed to ensure that negative pressure was evenly distributed across the wound bed, even as the area of the spacer fabric layer decreased. The spacer fabric layer serves as a transfer layer for negative pressure in the dressing. Tests were performed to evaluate whether a smaller sized spacer fabric layer (Dressing A) would compromise negative pressure distribution.

[0283] Negative pressure was applied to the dressing located on a wound model (i.e., a Plexiglas plate). The Plexiglas plate was equipped with sensors for measuring negative pressure levels, as well as inlet holes for supplying test liquid to the dressing to simulate normal use. A peristaltic pump was used to supply the liquid from beneath the dressing (supplying the liquid at a defined flow rate). This method evaluated the negative pressure distribution from the pressure source to different parts of the dressing.

[0284] Testing was performed with 5 dressings in each dressing category (Dressings A and B respectively) over 96 hours.

[0285] The results, as shown in Table 5 below, indicate that both Dressing A and Dressing B were effective at transferring negative pressure. There was no significant difference in the negative pressure levels measured between Dressing A and Dressing B.

[0286] Dressing A Dressing B Negative pressure at the bottom of the dressing within 96 hours 122.5 mmHg 123.9 mmHg

[0287] Table 5: Negative Pressure Transfer

[0288] The terms, definitions, and implementations of all aspects of this disclosure apply, mutatis mutandis, to other aspects of this disclosure.

[0289] Although this disclosure has been described with reference to its specific exemplary implementations, many different changes, modifications, etc. will become apparent to those skilled in the art.

[0290] By the study of the drawings, the disclosure, and the appended claims, those skilled in the art can understand and implement variations of the disclosed implementations when practicing this disclosure. Further, in the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality.

Claims

1. A negative pressure wound therapy (NPWT) dressing (100), the NPWT dressing being configured to be connected to a negative pressure source; the NPWT dressing includes, from top to bottom, a backing layer (101), a liquid distribution layer (102), an absorbent pad (103) including one or more pad-forming layers (103a-c), a spacer fabric layer (104), and an adhesive skin contact layer (105); the backing layer (101) and the adhesive skin contact layer (105) are arranged to extend beyond the contours of the liquid distribution layer (102), the absorbent pad (103), and the spacer fabric layer (104) to form a border portion (106), wherein the spacer fabric layer (104) includes a top layer (104a), a bottom layer (104b), and an interconnecting layer (104c) disposed between the top layer (104a) and the bottom layer (104b); the interconnecting layer (104c) includes a plurality of tufted filaments (107) extending between the top layer (104a) and the bottom layer (104b), the top layer (104a) of the spacer fabric layer (104) being defined by a peripheral edge, and wherein at least one of the liquid distribution layer (102) and the pad-forming layers (103a-c) of the absorbent pad (103) is arranged to overlap the peripheral edge of the top layer (104a) of the spacer fabric layer (104).

2. The NPWT dressing (100) according to claim 1, wherein, The backing layer (101) has a central portion and an edge portion surrounding the central portion, wherein the central portion has a preformed shape complementary to at least the shape of the absorbent pad (103), and wherein the edge portion forms a part of the border portion (106).

3. The NPWT dressing (100) according to claim 1 or 2, wherein, The spacer fabric layer (104) has a thickness t1, and wherein at least one of the liquid distribution layer (102) and the pad-forming layers (103a-c) of the absorbent pad (103) is arranged to overlap the peripheral edge of the top layer (104a) by a distance d1, wherein the distance d1 corresponds to 0.7t1 to 4.0t1, preferably 1.0t1 to 2.0t1.

4. The NPWT dressing (100) according to claim 1, further comprising a coupling member (108), the coupling member being configured to connect the dressing to the negative pressure source, wherein the backing layer (101) and at least a portion of the absorbent pad (103) include an opening (109) below the coupling member (108); the liquid distribution layer (102) has no opening.

5. The NPWT dressing (100) according to any one of the preceding claims, wherein, The liquid distribution layer (102) is a continuous layer extending over the entire surface area of the absorbent pad (103).

6. The NPWT dressing (100) according to any one of the preceding claims, wherein, The liquid distribution layer (102) is a non-woven fabric layer.

7. The NPWT dressing (100) according to any one of the preceding claims, wherein The absorbent pad (103) includes a first liquid distribution layer (103a), a superabsorbent layer (103b), and a second liquid distribution layer (103c), wherein the superabsorbent layer (103b) is disposed between the first liquid distribution layer (103a) and the second liquid distribution layer (103c), and wherein either the first liquid distribution layer (103a) or the second liquid distribution layer (103b) is a nonwoven layer.

8. The NPWT dressing (100) according to any one of the preceding claims, wherein, Both the liquid spreading layer (102) and the nonwoven layer of the absorbent pad (103) are arranged to overlap the peripheral edge of the top layer (104a) of the spacer fabric layer (104).

9. The NPWT dressing (100) according to any one of the preceding claims, wherein, Each pad forming layer (103a-c) of the liquid spreading layer (102) and the absorbent pad (103) is arranged to overlap the peripheral edge of the top layer (104a) of the spacer fabric layer (104).

10. The NPWT dressing (100) according to claim 9, wherein, The combined thickness of the liquid spreading layer (102) and the absorbent pad (103) is greater than the thickness t1 of the spacer fabric layer (104c).

11. The NPWT dressing (100) according to any one of the preceding claims, wherein, The dressing includes a conduit (110), wherein a first distal end of the conduit (110) is connected to the coupling member (108), and a second distal end of the conduit (110) is configured to be connected to a negative pressure source, wherein the conduit (110) includes a fluid conduit (110a) configured to remove fluid from the dressing and an air conduit (110b) configured to supply air to the fluid conduit (110a) and / or the NPWT dressing (100).

12. A negative pressure wound therapy (NPWT) system (200) includes: - A negative pressure wound therapy (NPWT) dressing (100) according to any one of claims 1-11, - A negative pressure source, - A remote fluid collection device (113) that is fluidly connected to the negative pressure source and the dressing (100).

13. The NPWT system (200) according to claim 12, wherein, The remote fluid collection device (113) is a canister, and wherein the canister and the negative pressure source are arranged within the same device (114).

14. The NPWT system (200) according to claim 13, wherein, The system (200) includes means for supplying air to the dressing (100) at a rate of 2 ml / min to 7 ml / min during operation.

15. A method for manufacturing a negative pressure wound therapy (NPWT) dressing (100), wherein, The method includes: a) Providing a backing layer (101), b) Disposing the liquid spreading layer (102) in contact with the backing layer (101), c) Disposing the absorbent pad (103) in contact with the liquid spreading layer (102), the absorbent pad including one or more pad forming layers (103a-c), d) Disposing the spacer fabric layer (104) in contact with the absorbent pad (103), wherein the spacer fabric layer (104) includes a top layer (104a), a bottom layer (104b), and an interconnecting layer (104c) disposed between the top layer (104a) and the bottom layer (104b); the interconnecting layer (104c) includes a plurality of tufted filaments (107) extending between the top layer (104a) and the bottom layer (104b), wherein the top layer (104a) of the spacer fabric layer (104) is defined by a peripheral edge, e) The adhesive skin contact layer (105) is disposed in contact with the spacer fabric layer (104), wherein the adhesive skin contact layer (105) and the backing layer (101) are arranged to extend beyond the contours of the liquid distribution layer (102), the absorbent pad (103), and the spacer fabric layer (104) to form a border portion 106, and wherein at least one of the liquid distribution layer and the pad forming layer of the absorbent pad (103) is arranged to overlap the peripheral edge of the top layer (104a) of the spacer fabric layer (104).

16. The method according to claim 15, wherein, The backing layer (101) is preformed into a shape complementary to at least the shape of the absorbent pad (103) before or simultaneously with step b) of disposing the liquid distribution layer in contact with the backing layer (101).

17. The method according to claim 16, wherein, The backing layer (101) is preformed by the following steps a) bringing the backing layer (101) into contact with a molding tool having a shape complementary to at least the shape of the absorbent pad (103), and b) applying a vacuum to the backing layer (101).

18. The method according to claim 17 when dependent on claim 15, wherein, Steps b)-d) of disposing the liquid distribution layer (102), the absorbent pad (103), and the spacer fabric layer (104) are carried out simultaneously with bringing the backing layer (101) into contact with a molding tool having a shape complementary to the shapes of the liquid distribution layer (102) and the absorbent pad (103), and preferably a vacuum is simultaneously applied to the backing layer (101).

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