Patent ID: 12186160

DETAILED DESCRIPTION

The preferred embodiment of the dressing according to the invention described inFIG.1comprises:a film1which is impermeable to fluids and permeable to water vapour, and the entire surface of which is covered by,a perforated reinforcement3coated on the face thereof in contact with said impermeable film with an adhesive and on the other face thereof with an adhesive silicone gel, the latter face being partially covered by,an absorbent pad4,a fluid distribution layer2inserted between said impermeable film1and said perforated reinforcement3.

The surface area of said dressing, the shape thereof, the surface area of the border and of the absorbent pad4are dependent on the type of wounds to be treated. A person skilled in the art is capable of defining, for each need, the optimum surface areas of each of the components.

The surface area of the border can be increased to improve the ability of the dressing according to the invention to adhere to the patient's skin.

The adhesiveness of the perforated reinforcement3can also be modified by varying:the dimension of the holes (length, width or diameter) which can vary between 0.1 mm and 8 mm, preferably between 1.0 mm and 3 mm,the distribution thereof in relation to each other (e.g. positioning at 45°, at 60° or at) 90°,the density thereof in number per unit of surface area, defined by an opening rate represented by the ratio between the open surface area relative to the total surface area.

Usually, the surface area of the distribution layer2is equivalent to that of the absorbent pad4placed next to the latter. However, said distribution layer2can advantageously extend beyond said absorbent pad4in order to improve the breathability of the dressing at the border and discharge the moisture released by sudation at the border.

Said distribution layer2can also have a surface area less than that of the pad4so as to obtain a breathability that is certainly sufficient, but not excessive so as not to risk drying the bed of the wound.

The different layers of the dressing according to the invention can be produced and assembled by any means known to a person skilled in the art.

Preferably, the film which is impermeable to fluids and permeable to water vapour1can be obtained by blown film extrusion, by flat extrusion, by solvent-phase liquid coating on a substrate based on paper or synthetic film both coated with an anti-adherent layer.

Preferably, the perforated reinforcement3coated on both faces thereof with one or more medically acceptable adhesives can be obtained by coating both faces, for example by coating or steeping in a bath, of a perforated knit type open textile or a unitary net made of thermoplastic material, or perforating a film of a nonwoven previously coated on both faces thereof with one of more medically acceptable adhesives. The open knit can be obtained by so-called “warp” knitting. The unitary material net can be obtained by extrusion casting followed by hot stretching after perforation. The film can be obtained by blown film extrusion, by flat extrusion, or by liquid coating in solvent phase on a carrier. The nonwoven can be obtained by so-called melt blown or spunbound technology if the selected fibres are thermoplastic or by so-called spunlace technology in the case of nonwoven materials containing non-thermoplastic fibres.

All the materials cited in the present application can be advantageously combined with functional agent for treating the wound such as antimicrobial, disinfectant, and-odour, wound treatment activating and/or detergent products.

A corona treatment as described by the applicant in the document WO 2015044535 A1 can be advantageously applied to the silicone adhesive on the surface intended to be bonded thereto (pad4and/or breathable impermeable film1)

EXAMPLES

Example 1: Demonstration of the Specific Effect of a Distribution Layer2on Breathability

In order to demonstrate the effect of the distribution layer2on the breathability of a construction according to the invention, the applicant constructed assemblies comprisinga film which is impermeable to fluids and permeable to water vapour1, and the entire surface of which is covered by,a perforated reinforcement3coated on the face thereof in contact with said impermeable film,a fluid distribution layer2inserted between said impermeable film and said perforated reinforcement (except for control sample).

The perforated reinforcement3was a polyurethane film, coated on one face with acrylic adhesive and on the other face with silicone adhesive, then perforated and assembled with polyurethane films1with and without (control) insertion of a distribution layer2.

In the assembly obtained, assembled disks of overall diameter 42 mm were cut, optionally comprising a diffusion disk, bonded at the centre thereof, of diameter arbitrarily defined as 24 mm, then subjected to the breathability measurement test in liquid contact (MVTR) as per the EN 13726-2:2002 period for a 4 h duration.

The perforated reinforcement3was manufactured by the applicant under the reference Acrysil 150 703731, perforated with holes at 60°, diameter 2.4 mm and 15% opening rate.

The distribution layers2evaluated are:a 45 g/m2polyester nonwoven (reference Sontara Spunlace Style 8000 distributed by Jacob Holm Industries).a polyurethane foam of thickness 1.5 mm (reference Vilmed 6217 manufactured by Freudenberg).an absorbent nonwoven (reference Vilmed M1556 manufactured by Freudenberg).

The films which are impermeable to fluids and permeable to water vapour1used were:A film of thickness 15 μm (reference Inspire 2350, manufactured by Transcontinental Advanced Coating Ltd).A film of thickness 30 μm (reference Inspire 2301, manufactured by Transcontinental
Advanced Coating Ltd).

The MVTR breathability observed for each of these constructions is stated in [Table 1] below.

TABLE 1ControlAssemblyAssemblyAssemblyassemblywithwithwith(with no diffusionpolyesterpolyurethaneabsorbentlayer)nonwovenfoamnonwovenPU film544214224140582083915 μmg/m2/24 hg/m2/24 hg/m2/24 hg/m2/24 hPU film2945766494431144830 μmg/m2/24 hg/m2/24 hg/m2/24 hg/m2/24 h

It is thus observed, surprisingly, that inserting a diffusion layer2between the perforated reinforcement3and the film1, makes it possible to increase, by 160% to 290% depending on the cases, the breathability of the complex.

Even more surprisingly, the breathability increases very substantially if the distribution layer2tends to swell on absorbing the liquid (case of Vilmed 6217 foam), then inducing a deformation elongation of the film1since it is not bonded; this then results in greater breathability of the film1by elongation, increase in the exchange surface area, and reduction in thickness.

Example 2: Demonstration of the Effect of a Distribution Layer2on the Breathability of a Dressing According to the Invention

The assemblies of example 1 are produced identically on the 15 μm film1, but an absorbent polyurethane foam disk is bonded to the perforated reinforcement3, on the silicone adhesive side, to represent the absorbent pad4.

The absorbent polyurethane foam pad4used has a thickness of 2 mm (reference MC F03 manufactured by Advanced Medical Solutions Group Plc).

The assembled disks, of diameter 42 mm, optionally comprising a distribution layer2of diameter 24 mm, are subjected to the breathability measurement test in liquid contact (MVTR) as per the EN 13726-2:2002 period for a 4 h duration.

The MVTR breathability observed for each of these constructions is stated in [Table 2] below.

TABLE 2ControlAssemblyAssemblyAssemblyassemblywithwithwith(with no diffusionpolyesterpolyurethaneabsorbentlayer)nonwovenfoamnonwovenPU film541413767.6119641713615 μmg/m2/24 hg/m2/24 hg/m2/24 hg/m2/24 h

It is thus observed that adding an absorbent pad4reduces the overall MVTR of the dressing slightly, but the effect due to inserting the distribution layer2is not cancelled.

Example 3: Effect of the Variation of the Surface Area of the Distribution Layer2on the Breathability of a Dressing According to the Invention

Assemblies according to example 1 with a 15 μm film1were produced by varying the diameter, therefore the surface area of the distribution layer2.

The distribution layer2evaluated was a 45 g/m2polyester nonwoven (reference Sontara Spunlace Style 8000 distributed by Jacob Holm Industries).

The assembled disks, of diameter 42 mm, optionally comprising a distribution layer2of variable diameter (12, 18, 24 & 30 mm) were subjected to the breathability measurement test in liquid contact (MVTR) as per the EN 13726-2:2002 period for a 4 h duration.

The results obtained are shown in [FIG.2].

It is thus observed that the distribution layer2fully fulfils its role, the moisture being evaporated over a greater surface area of film1.

Consequently, it is possible to vary the MVTR breathability by merely varying the surface area of the distribution layer2. In some cases, it may be desirable to have a maximum breathability to prevent an accumulation of exudates at the wound and thus tissue maceration. On the other hand, in some cases, it is necessary to limit the breathability of the dressing to prevent drying of the wound bed and thus promote wound healing.

Example 4: Effect of the Variation of the Opening Rate of the Perforated Reinforcement3on the Breathability of a Dressing According to the Invention

Assemblies according to example 1, comprising a 15 μm film1, were constructed by varying the perforation design of the perforated reinforcement3so as to generate perforations having different diameters and opening rates.

Assemblies, of diameter 42 mm, optionally comprising a distribution disk3of diameter 24 mm, are subjected to the breathability measurement test in liquid contact (MVTR) as per the EN 13726-2:2002 period for a 4 h duration.

The results obtained are shown in [FIG.3].

It is observed that, without a distribution layer2, the breathability remains closely dependent on the opening rate of the perforated reinforcement3. Conversely, in the presence of the distribution layer2, the MVTR is virtually stable according to the opening rate and therefore the adhesive power of the dressing according to the invention.

Consequently, unlike the dressing according to the prior art, the dressing according to the invention makes it possible to readily modify the breathability of the dressing without modifying the opening rate of the perforated product and therefore without modifying the adhesive power thereof on the patient. Conversely, it is possible to modulate the adhesive power of the dressing on the skin and/or the absorbent pad4on the perforated reinforcement3(by modifying the opening rate of the perforated reinforcement3and/or the size of the borders) without modifying the overall breathability of the finished dressing.

Additionally, it is thus possible to modulate and optimise the two features of breathability and adhesive power completely independently unlike the dressings of the prior art.