Wound dressing and method of treatment

Abstract

A wound dressing, a method of manufacturing a wound dressing, and a method of treating a patient are disclosed. The wound dressing may include an absorbent layer for absorbing wound exudate; and an obscuring element for at least partially obscuring a view of wound exudate absorbed by the absorbent layer in use.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application
where A is the absorption of light radiation at the particular wavelength.

Using this formula, using light at a wavelength of 460 nm, the percentage of absorption reduction was calculated as shown in Table 3 below.

	TABLE 3
		Absorption	Appropriate masking
	Sample	reduction at 460 nm	observed
	Sample 1	34%	No
	Sample 2	77%	Yes - partial
	Sample 3	69%	Yes - complete

It has been found that materials that reduce light absorption by about 50% or more will provide enough partial or complete masking of wound exudate (as judged by the inventors). Of course a complete masking element wound preferably require a means for a clinician to judge the spread of wound exudate in the dressing below the masking element, e.g. the masking element not completely covering the entire dressing. Alternatively a partial masking element may allow a clinician to judge the spread of exudate in the dressing below without additional means.

It will be understood that the wetting of a masking material (by exudate for example) will also affect the masking performance of the masking element, since hydrophilic materials will allow chromophore-carrying species to travel through them more easily. As such, the absorption reduction rate should also be tested on wet materials.

The inventors also tested the above-mentioned Samples 1, 2 and 3 for their masking properties by measuring CIE L*a*b* values (a known 3-dimensional model for representing colour space). The analysis employed Jasco software using the range 380 to 780 nm, stard observed 2(deg), lightsource D65, colour matching JIS Z8701-1999.

Table 4 below shows the L*a*b* values found when Samples 1, 2 and 3 were respectively placed over a black background. The results for the black background alone and a white background are also shown.

TABLE 4
	CIE L*a*b*	Appropriate
	values recorded	masking
Sample	L*	a*	b*	observed?
Black	0	0	0	n/a
background
Sample 1 (on black)	36.59	3.76	−1.80	No
Sample 2 (on black)	71.76	−0.20	−1.08	Yes - partial
Sample 3 (on black)	70.64	−0.25	−1.23	Yes - complete
White background	100	0	0	n/a

Generally, samples which lead to an increase in L* value will provide a lighter colour tone than the reference surface, which is the main contributor to masking a dark colour. From the values above, apt partial masking materials will yield an L* value above 50, or more aptly above 70.

However, completely opaque masking layers, such as for example a tinted polymeric film, may cover the area to be masked with a darker tone altogether, in which case the measure of L* is not relevant.

Once again these values should also be considered on wet material, for the reasons stated above.

In addition, the dressing of the disclosure may be arranged to prevent shear stress between layers from causing damage to the dressing. This is because the layers are generally not adhered together, other than the top film 102 and wound contact layer 101 being adhered in the border region 110. Thus even if friction or other energy from shear movement occurs, the energy is dissipated by the layers prior to reaching the patient.

The wound facing surface of a wound dressing may be provided with a release coated protector (not shown in the figures), for example a silicon-coated paper. The protector covers the wound contacting side of the dressing prior to application to a patient, and can be peeled away at the time of use.

Various modifications to the detailed arrangements as described above are possible. For example, dressings according to the present disclosure do not require each of the specific layers as described above with respect to FIG. 1. Dressings may include only one layer, or any combination of the layers described above. Alternatively or additionally, the materials of the layers described above may be combined into a single layer or sheet of material to perform the functions of each layer by a single layer.

As noted above, each of the layers described may be used to give one or more function to the wound dressing. As such, each of the layer materials may be used separately or in any combination such that each material provides the given function.

The wound contact layer described above is an optional layer. If used, a wound contact layer may be of any suitable material, such as polyethylene (or polyurethane as described above) or other suitable polymer, and may be perforated for example by a hot pin process, laser ablation process, ultrasound process or in some other way so as to be permeable to fluids.

Although the dressing described above has been described having a border region and a central region this need not be the case. The dressing may be provided without an adhesive layer for attachment to the skin of a patient. Rather, another means may be provided for locating the dressing at the correct position over a wound, such as adhesive tape or a tied bandage.

The relative widths of the various layers may be all the same or different to those as shown in the figures.

The dressing pad assembly may optionally be arranged with layers so that odour control is placed between two layers of different rates of absorptions. The odour control layer can be a charcoal cloth (knitted, woven, felt, non-woven), or any other textile, foam, gel, net or mesh impregnated with odour-control materials. Such odour control materials can be cyclodextrins, zeolites, ion-exchange resins, oxidising agents, activated charcoal powder. It is also possible to use said odour-control materials dispersed in any layer of the pad assembly, and not as a discrete layer.

The dressing may optionally include a means of partially obscuring the top surface. This could also be achieved using a textile (knitted, woven, or non-woven) layer without openings, provided it still enables fluid evaporation from the absorbent structure. It could also be achieved by printing a masking pattern on the top film, or on the top surface of the uppermost pad component, using an appropriate ink or coloured pad component (yarn, thread, coating) respectively. Another way of achieving this would be to have a completely opaque top surface, which could be temporarily opened by the clinician for inspection of the dressing state (for example through a window), and closed again without compromising the environment of the wound.

The dressing may optionally be arranged such that it has enhanced compatibility with body movement. This could also be achieved using a different shape for the sub-areas, such as diamonds, triangles, or a plurality of such shapes tessellated across the area of the dressing. Alternatively, preferential folding lines may be scored within the thickness of the dressing material, and thus define independent sub-areas for adapting to movement.

Alternatively, the layers could be bonded using an elastic material, such as a viscoelastic adhesive, which would allow shear between the layers but refrain them from becoming separated and shifting across the pad.

A dressing may optionally be arranged that provides enhanced protection against mechanical forces. Other ways of achieving this include:

• • Incorporation of pressure-relieving components within other layers of the dressing, such as within the foam layer (e.g. moulding the foam around a 3-D structure capable of spreading load)
  • Incorporation of pressure-absorbing component within other layers of the dressing (e.g. beads of viscoelastic material incorporated in the superabsorbent layer)

A dressing assembly may optionally be arranged where the flowing properties are being provided by given material layers, and where the respective position of these layers provides additional properties on top of those from the individual layers. Alternative arrangement of layers than that described above may still provide some of the properties sought.

For example, placing the shielding layer (106) below the superabsorbent layer (105) would still allow protection from point pressure, but would lose the masking ability of this layer, and would probably affect the transmission of fluid between the foam layer (103) and the superabsorbent layer (105).

Another example is the placement of the odour control layer or component further away from the wound: this can be seen as beneficial because some types of odour control work differently depending on whether they are wet or dry. Placing a colour-less odour control component towards the top of the dressing (anywhere above (105)) could provide odour control properties without the visual impact that a black layer of charcoal cloth would have.

It can also be envisaged that several properties are combined within one layer, for example superabsorbent and odour control components could be incorporated in the foam structure. The only remaining optional properties to provide in this case would be protection and masking, which could be achieved by placing a layer (106) directly above such a modified foam if needed.

Interestingly, the fluid handling properties of an embodiment where the superabsorbing function is located within the lowest part of the dressing pad may not be as beneficial as those of an embodiment where the functions are held in separate layers, and the fluid is directed from one layer to another.

In another embodiment, the shielding layer 106 is of the same dimensions as 105, and clinical judgment of the exudate spread can be made by observing the spread of exudate through the masking layer. This embodiment has the advantage of completely masking unsightly exudate from the superabsorbent layer.

Alternatively or additionally, the shielding layer can be provided with full masking capability, and windows provided at discrete points of the layer for enabling judgement of the exudate spread below such layer. Examples of such windows are illustrated in FIGS. 12a and 12b. The dressing 1200 shown in FIG. 12a includes a masking layer 1202 and crescent-shaped windows 1204 provided in the masking layer to extend through the layer allowing visibility of the dressing therebelow. The dressing 1210 of FIG. 12b includes a masking layer 1212 and a number of holes 1214 therethrough acting as windows for viewing the state of the dressing therebelow. FIG. 12c shows another dressing 1220 including a masking layer 1222 with windows 1224. With the dressings 1200, 1210, 1220 the progress of exudate spread over the dressing and towards the edge of the dressing can be monitored. In other alternatives instructions may be given to change the dressing when the exudate reaches a predetermined distance from the edge of the dressing, such as 5 mm from the dressing edge or 7 mm from the dressing edge, etc. Alternatively a ‘traffic light’ system may be implemented whereby an electronic indicator shows green, amber or red light to indicate the spread of exudate in the dressing. Alternatively or additionally, another suitable indicator may be used for indicating the spread of exudate over the dressing.

In another embodiment, odour control is not provided by a separate layer (i.e. no layer 104), but instead the odour-control material (activated charcoal, cyclodextrin, ion exchange resin, or other) is dispersed throughout another layer. This can be envisaged within the foam (103), the superabsorbent structure (105), or as a coating onto the masking layer (106).

In addition or alternatively, the obscuring layer may be coated with or formed from a material with size-exclusion properties to help with masking the exudate from view. For example, such a layer could have its lowermost side (the side closer to the wound) coated with materials such as zeolites or clays such as bentonite or sepiolite (the charged surface of which will tend to attract proteins and protein derivatives containing chromophores), other inorganic powders or molecular sieves (e.g. amberlite), proteins (albumin, haemoglobin components with molecular weight 15 to 70 KDa), ionic complexes such as hemes (molecular weight 600 to 850 g/mol), which have the function of immobilising species above a certain size or molecular weight. For example, species having molecular weight above 100 g/mol.

The shielding layer may be coated with or be formed of a hydrophilic compound (e.g. polyesters, polyurethanes, polyureas, polysaccharides, etc.) for assisting in wicking moisture towards the surface of the dressing, helping breathability of the dressing.

The shielding layer may be combined with a cover layer, such as an opaque or dark pigmented top layer.

The shielding layer (acting as a masking layer) may be combined with an absorbent layer, for example by providing an absorbent layer that has been dyed, for example with a dark blue pigment to the fibres of a non-woven or airlaid material.

The shielding layer (acting as a pressure relieving layer) may be combined with an absorbent layer. For example a fibrous superabsorber layer may be provided with a high density of fibres for spreading point pressure. Alternatively a hydrophilic foam may be moulded around pressure-redistributing structures of pillars or arrays of an elastomer material, for example.

Odour control can be combined with absorbency by dispersing particles of activated charcoal or other odour-catching material in a hydrophilic foam at time of reaction, or dispersing it throughout an air-laid material as a powder, or introducing it in the master batch of absorbent polymer used to manufacture fibres which will then be used in an air-laid.

As such, odour control, absorbency and pressure redistribution could be included in a single layer, and if this material was dyed, masking could also be performed.

The layers described herein may each be provided directly adjacent another layer or with further layers therebetween.

A wound dressing may be formed by bringing together a layer of absorbent material with a layer of obscuring material.

Alternatively a wound dressing may be formed by bringing together a layer of absorbent material with a layer of protective material.

Alternatively a wound dressing may be formed by bringing together a layer of absorbent material with a cover layer.

Alternatively a wound dressing may be formed by bringing together a layer of absorbent material with a fluid transmission layer with a layer of activated charcoal material therebetween.

Any of the methods above may include bringing layers together with adhesive over part or all of a layer. The method may be a lamination process.

Alternatively a wound dressing may be formed by bringing together layers as described with respect to FIG. 1, in a contiguous laminar stack, and adhering the top film to the wound contact layer in a border region.

Alternatively a wound dressing may be formed by forming a sheet of material for absorbing wound exudate, the sheet comprising at least one of a foam, an odour capturing material, an absorbent material, and a shielding material for masking or pressure spreading.

The dressing of the disclosure may be manufactured by continuous production techniques. For example, a sheet or sheets of suitable material may be run through rollers to enable the adhesion of one layer to another. Alternatively, pre-cut pad component shapes can be placed onto a web of one of the adhesive film or net components, before being encapsulated by the another adhesive film or net component. Then the dressing may be stamped out by cutting through the material in the desired shape and packaged.

In use, a wound dressing of the present disclosure would be applied to a wound site of a patient with the surface of the wound contacting side of the dressing facing the wound site. The wound dressing would then be monitored over a predetermined time period to assess the extent of exudate present in the dressing. The dressing may be any of the examples and embodiments described herein.

The dressing may be monitored at predetermined intervals or at predetermined time(s) of the day. For example, the dressing may be monitored every 6 hours, or once every morning, lunchtime and evening, for example, or as required by the specific patient.

A method for determining the saturation of a wound dressing with wound exudate comprises:

• • viewing a wound dressing at predetermined intervals to assess the extent of exudate present in the wound dressing.

The dressing may be any of the dressings described herein.

With the above-described arrangements one or more advantages over known dressings may be achieved.

The disclosure described contains elements which lead to a combination of properties that is not currently being met by existing devices.

In particular, the combination of an effective odour-control layer, held between two absorbent layers of differential absorption power, yields an absorbent structure which does not require a barrier layer to remain efficient against odours.

The odour-removing layer is not bonded to adjacent layers. Because of this, the available surface area of active pores of the odour layer is not diminished. That is, in known dressings including an odour resistant layer of activated charcoal, the material is carbonised to insert carbon into the surface porosity of the layer. The layer is then adhered to an adjacent layer, thus coating some of the porous surface area with adhesive, and reducing the total surface porosity.

The present disclosure comprising a shaped pad and dressing border, working as more independent sub-units of the dressing than what can be seen for a standard square shape, yields better conformability with movement than standard shapes. The dressing remains conformable with the skin and comfortable to wear, allowing the patient to move whilst wearing the dressing, and without creating detrimental traction on the pen-wound skin, which could lead to slowing of wound healing.

Some embodiments of the present disclosure also help to reduce the unsightly appearance of a dressing during use, by using materials that impart partial masking of the dressing surface. The masking should preferably only be partial, to allow clinicians to access the information they require by observing the spread of exudate across the dressing surface. This property, which is very important in helping patients live better with their treatment, had not been achieved until now for absorbent, breathable dressings. The partial masking nature of the obscuring layer enables a skilled clinician to perceive a different colour caused by exudate, blood, by-products etc. in the dressing allowing for a visual assessment and monitoring of the extent of spread across the dressing. However, since the change in colour of the dressing from its clean state to a state with exudate contained is only a slight change, the patient is unlikely to notice any aesthetic difference. Reducing or eliminating a visual indicator of wound exudate from a patient is likely to have a positive effect on their health, reducing stress for example. Also, some embodiments of the present disclosure provide a mean of relieving point pressure that may be applied to the wound area, by introducing a breathable, shear resistant layer that does not have to be in contact with the skin. This construction maximises the absorbency capacity of the dressing by not replacing some of the absorbent area with pressure-relieving areas. Breathability of the part of the dressing in contact with the skin is also maximise, as the breathable wound contact layer, lower part of the pad, and film, are not impaired by the use of another structure in contact with the skin.

By providing an odour control layer between a foam and an absorber layer, this can help in allowing only excess fluid towards the absorber layer, whilst keeping the foam layer sufficiently moist to create a moist wound healing environment. This is because the odour layer does not draw fluid away from the foam layer at the same speed at which an absorbent layer would. The transfer of fluid from the foam layer to the absorbent layer is therefore slowed down (relative to having a foam layer directly adjacent an absorber layer). Therefore, only excess fluid is taken into the odour layer, thereby assisting in the foam layer maintaining some degree of moisture and not drying out.

That is, the absorption rate of the outer layer should aptly be higher than the absorption rate of the lower layer (closer to the wound).

Prior to the invention of the embodiments disclosed herein, it was generally believed that the wetting of activated charcoal would destroy the function of the material of performing odour capturing. As such, activated charcoal layers have been used as an outer layer protected from liquid by a barrier layer. However the inventors found that as long as the activated charcoal layer is not soaked in liquid the activated charcoal can perform sufficiently well as an odour removing layer.

When the layer of absorbent material folds over the edges of any other lower layers, the absorbent layer helps to prevent fluid from being squeezed from the dressing at the dressing edge region, thereby causing leakage. Various known dressings previously suffered from the risk of delamination of layers caused by fluid being squeezed towards the edge of the dressing, being driven between the layers and possibly escaping at the edge of the dressing. This may occur for example in a border region where a wound contact layer meets a cover layer, and any intermediate layers of the dressing are adjacent that border region. Aptly an absorbent layer including a superabsorber material is useful in preventing the release of any liquid, especially in the direction of the border region or edge of the dressing.

Alternative materials can be used for the absorbent layer to provide the fluid locking and leak prevention properties, for example:

• • absorbent or superabsorbent non-woven materials, which can be made of fibrous modified cellulose, fibrous modified chitosan, fibrous hydrophilic polyesters, fibrous cellulose, fibrous chitosan, fibrous polysaccharides
  • absorbent or superabsorbent foams, which can be blown hydrophilic polyurethane foam, comprising superabsorbent particles or fibres; foams of hydrophilic polyvinylacetate
    absorbent or superabsorbent gels or solids, which can be hydrocolloid polymer structures, additionally comprising superabsorbent particles or fibres.

Additionally, any of the dressing embodiments disclosed herein can be used in with a source of negative pressure, such as a pump. Any of the dressing embodiments disclosed herein can also be used with a pump and a fluid or waste collection canister that can be put in fluid communication with the pump and the dressing so that the pump draws fluid or waste from the wound into the collection canister.

Additionally, in any embodiments, the pump can be a piezoelectric pump, a diaphragm pump, a voice coil actuated pump, a constant tension spring actuated pump, a manually actuated or operated pump, a battery powered pump, a DC or AC motor actuated pump, a combination of any of the foregoing, or any other suitable pump.

FIGS. 15A-B illustrate cross sections through a wound dressing 2100 according to an embodiment of the disclosure. A plan view from above the wound dressing 2100 is illustrated in FIG. 16 with the line A-A indicating the location of the cross section shown in FIGS. 15A and 15B. It will be understood that FIGS. 15A-B illustrate a generalized schematic view of an apparatus 2100. It will be understood that embodiments of the present disclosure are generally applicable to use in TNP therapy systems. Briefly, negative pressure wound therapy assists in the closure and healing of many forms of “hard to heal” wounds by reducing tissue oedema; encouraging blood flow and granular tissue formation; removing excess exudate and may reduce bacterial load (and thus infection risk). In addition, the therapy allows for less disturbance of a wound leading to more rapid healing. TNP therapy systems may also assist on the healing of surgically closed wounds by removing fluid and by helping to stabilize the tissue in the opposed position of closure. A further beneficial use of TNP therapy can be found in grafts and flaps where removal of excess fluid is important and close proximity of the graft to tissue is required in order to ensure tissue viability.

The wound dressing 2100, which can alternatively be any wound dressing embodiment disclosed herein including without limitation wound dressing 100 or have any combination of features of any number of wound dressing embodiments disclosed herein, can be located over a wound site to be treated. The dressing 2100 forms a sealed cavity over the wound site. It will be appreciated that throughout this specification reference is made to a wound. In this sense it is to be understood that the term wound is to be broadly construed and encompasses open and closed wounds in which skin is torn, cut or punctured or where trauma causes a contusion. A wound is thus broadly defined as any damaged region of tissue where fluid may or may not be produced. Examples of such wounds include, but are not limited to, incisions, lacerations, abrasions, contusions, burns, diabetic ulcers, pressure ulcers, stoma, surgical wounds, trauma and venous ulcers or the like.

In some embodiments, it may be preferable for the wound site to be filled partially or completely with a wound packing material. This wound packing material is optional, but may be desirable in certain wounds, for example deeper wounds. The wound packing material can be used in addition to the wound dressing 2100. The wound packing material generally may comprise a porous and conformable material, for example foam (including reticulated foams), and gauze. Preferably, the wound packing material is sized or shaped to fit within the wound site so as to fill any empty spaces. The wound dressing 2100 may then be placed over the wound site and wound packing material overlying the wound site. When a wound packing material is used, once the wound dressing 2100 is sealed over the wound site, TNP is transmitted from a pump through the wound dressing 2100, through the wound packing material, and to the wound site. This negative pressure draws wound exudate and other fluids or secretions away from the wound site.

It is envisaged that the negative pressure range for the apparatus embodying the present disclosure may be between about −20 mmHg and −200 mmHg (note that these pressures are relative to normal ambient atmospheric pressure thus, −200 mmHg would be about 560 mmHg in practical terms). In one embodiment, the pressure range may be between about −40 mmHg and −150 mmHg. Alternatively a pressure range of up to −75 mmHg, up to −80 mmHg or over −80 mmHg can be used. Also in other embodiments a pressure range of below −75 mmHg could be used. Alternatively a pressure range of over −100 mmHg could be used or over −150 mmHg.

It will be appreciated that according to certain embodiments of the present disclosure, the pressure provided may be modulated over a period of time according to one or more desired and predefined pressure profiles. For example such a profile may include modulating the negative pressure between two predetermined negative pressures P1 and P2 such that pressure is held substantially constant at P1 for a pre-determined time period T1 and then adjusted by suitable means such as varying pump work or restricting fluid flow or the like, to a new predetermined pressure P2 where the pressure may be held substantially constant for a further predetermined time period T2. Two, three or four or more predetermined pressure values and respective time periods may be optionally utilized. Other embodiments may employ more complex amplitude/frequency wave forms of pressure flow profiles may also be provided e.g. sinusoidal, sore tooth, systolic-diastolic or the like.

As illustrated in FIGS. 15A-B a lower surface 2101 of the wound dressing 2100, which, again, can be any wound dressing embodiment disclosed herein including without limitation dressing embodiment 100 or have any combination of features of any number of wound dressing embodiments disclosed herein, can be provided by an optional wound contact layer 2102. The wound contact layer 2102 can be a polyurethane layer or polyethylene layer or other flexible layer which is perforated, for example via a hot pin process, laser ablation process, ultrasound process or in some other way or otherwise made permeable to liquid and gas. The wound contact layer has a lower surface 2101 and an upper surface 2103. The perforations 2104 are through holes in the wound contact layer which enables fluid to flow through the layer. The wound contact layer helps prevent tissue ingrowth into the other material of the wound dressing. The perforations are small enough to meet this requirement but still allow fluid through. For example, perforations formed as slits or holes having a size ranging from 0.025 mm to 1.2 mm are considered small enough to help prevent tissue ingrowth into the wound dressing while allowing wound exudate to flow into the dressing. The wound contact layer helps hold the whole wound dressing together and helps to create an air tight seal around the absorbent pad in order to maintain negative pressure at the wound. The wound contact layer also acts as a carrier for an optional lower and upper adhesive layer (not shown). For example, a lower pressure sensitive adhesive may be provided on the underside surface 2101 of the wound dressing whilst an upper pressure sensitive adhesive layer may be provided on the upper surface 2103 of the wound contact layer. The pressure sensitive adhesive, which may be a silicone, hot melt, hydrocolloid or acrylic based adhesive or other such adhesives, may be formed on both sides or optionally on a selected one or none of the sides of the wound contact layer. When a lower pressure sensitive adhesive layer is utilized this helps adhere the wound dressing to the skin around a wound site.

A layer 2105 of porous material can be located above the wound contact layer. This porous layer, or transmission layer, 2105 allows transmission of fluid including liquid and gas away from a wound site into upper layers of the wound dressing. In particular, the transmission layer 2105 ensures that an open air channel can be maintained to communicate negative pressure over the wound area even when the absorbent layer has absorbed substantial amounts of exudates. The layer should remain open under the typical pressures that will be applied during negative pressure wound therapy as described above, so that the whole wound site sees an equalized negative pressure. The layer 2105 is formed of a material having a three dimensional structure. For example, a knitted or woven spacer fabric (for example Baltex 7970 weft knitted polyester) or a non-woven fabric could be used. Other materials could of course be utilized, and examples of such materials are described below with respect to FIGS. 37-41.

In some embodiments, the transmission layer comprises a 3D polyester spacer fabric layer including a top layer (that is to say, a layer distal from the wound-bed in use) which is a 84/144 textured polyester, and a bottom layer (that is to say, a layer which lies proximate to the wound bed in use) which is a 100 denier flat polyester and a third layer formed sandwiched between these two layers which is a region defined by a knitted polyester viscose, cellulose or the like monofilament fiber. Other materials and other linear mass densities of fiber could of course be used.

Whilst reference is made throughout this disclosure to a monofilament fiber it will be appreciated that a multistrand alternative could of course be utilized.

The top spacer fabric thus has more filaments in a yarn used to form it than the number of filaments making up the yarn used to form the bottom spacer fabric layer.

This differential between filament counts in the spaced apart layers helps control moisture flow across the transmission layer. Particularly, by having a filament count greater in the top layer, that is to say, the top layer is made from a yarn having more filaments than the yarn used in the bottom layer, liquid tends to be wicked along the top layer more than the bottom layer. In use, this differential tends to draw liquid away from the wound bed and into a central region of the dressing where the absorbent layer helps lock the liquid away or itself wicks the liquid onwards towards the cover layer where it can be transpired.

Preferably, to improve the liquid flow across the transmission layer (that is to say perpendicular to the channel region formed between the top and bottom spacer layers, the 3D fabric is treated with a dry cleaning agent (such as, but not limited to, Perchloro Ethylene) to help remove any manufacturing products such as mineral oils, fats and/or waxes used previously which might interfere with the hydrophilic capabilities of the transmission layer. In some embodiments, an additional manufacturing step can subsequently be carried in which the 3D spacer fabric is washed in a hydrophilic agent (such as, but not limited to, Feran Ice 30 g/l available from the Rudolph Group). This process step helps ensure that the surface tension on the materials is so low that liquid such as water can enter the fabric as soon as it contacts the 3D knit fabric. This also aids in controlling the flow of the liquid insult component of any exudates.

A layer 2110 of absorbent material is provided above the transmission layer 2105. The absorbent material which may be a foam or non-woven natural or synthetic material and which may optionally include or be super-absorbent material forms a reservoir for fluid, particularly liquid, removed from the wound site and draws those fluids towards a cover layer 2140. With reference to FIGS. 15A and 15B, a masking or obscuring layer 2107 can be positioned beneath the cover layer 2140. In some embodiments, the masking layer 2107 can have any of the same features, materials, or other details of any of the other embodiments of the masking layers disclosed herein, including but not limited to having any viewing windows or holes. Additionally, the masking layer 2107 can be positioned adjacent to the cover layer, or can be positioned adjacent to any other dressing layer desired. In some embodiments, the masking layer 2107 can be adhered to or integrally formed with the cover layer. In some embodiments the masking layer 2107 may optionally contain a hole (not shown) directly adjacent to the port 2150 to improve air flow through the layer.

The material of the absorbent layer also prevents liquid collected in the wound dressing from flowing in a sloshing manner. The absorbent layer 2110 also helps distribute fluid throughout the layer via a wicking action so that fluid is drawn from the wound site and stored throughout the absorbent layer. This helps prevent agglomeration in areas of the absorbent layer. The capacity of the absorbent material must be sufficient to manage the exudates flow rate of a wound when negative pressure is applied. Since in use the absorbent layer experiences negative pressures the material of the absorbent layer is chosen to absorb liquid under such circumstances. A number of materials exist that are able to absorb liquid when under negative pressure, for example superabsorber material. The absorbent layer 2110 may typically be manufactured from ALLEVYN™ foam, Freudenberg 114-224-4 and/or Chem-Posite™ 11C-450.

In some embodiments, the absorbent layer is a layer of non-woven cellulose fibers having super-absorbent material in the form of dry particles dispersed throughout. Use of the cellulose fibers introduces fast wicking elements which help quickly and evenly distribute liquid taken up by the dressing. The juxtaposition of multiple strand-like fibers leads to strong capillary action in the fibrous pad which helps distribute liquid. In this way, the super-absorbent material is efficiently supplied with liquid. Also, all regions of the absorbent layer are provided with liquid.

The wicking action also assists in bringing liquid into contact with the upper cover layer to aid increase transpiration rates of the dressing.

The wicking action also assists in delivering liquid downwards towards the wound bed when exudation slows or halts. This delivery process helps maintain the transmission layer and lower wound bed region in a moist state which helps prevent crusting within the dressing (which could lead to blockage) and helps maintain an environment optimized for wound healing.

In some embodiments, the absorbent layer may be an air-laid material. Heat fusible fibers may optionally be used to assist in holding the structure of the pad together. It will be appreciated that rather than using super-absorbing particles or in addition to such use, super-absorbing fibers may be utilized according to certain embodiments of the present disclosure. An example of a suitable material is the Product Chem-Posite™0 11 C available from Emerging Technologies Inc (ETi) in the USA.

Optionally, according to some embodiments of the present disclosure, the absorbent layer may include synthetic stable fibers and/or bi-component stable fibers and/or natural stable fibers and/or super-absorbent fibers. Fibers in the absorbent layer may be secured together by latex bonding or thermal bonding or hydrogen bonding or a combination of any bonding technique or other securing mechanism. In some embodiments, the absorbent layer is formed by fibers which operate to lock super-absorbent particles within the absorbent layer. This helps ensure that super-absorbent particles do not move external to the absorbent layer and towards an underlying wound bed. This is particularly helpful because when negative pressure is applied there is a tendency for the absorbent pad to collapse downwards and this action would push super-absorbent particle matter into a direction towards the wound bed if they were not locked away by the fibrous structure of the absorbent layer.

The absorbent layer may comprise a layer of multiple fibers. Preferably, the fibers are strand-like and made from cellulose, polyester, viscose or the like. Preferably, dry absorbent particles are distributed throughout the absorbent layer ready for use. In some embodiments, the absorbent layer comprises a pad of cellulose fibers and a plurality of super absorbent particles. In additional embodiments, the absorbent layer is a non-woven layer of randomly orientated cellulose fibers.

Super-absorber particles/fibers may be, for example, sodium polyacrylate or carbomethoxycellulose materials or the like or any material capable of absorbing many times its own weight in liquid. In some embodiments, the material can absorb more than five times its own weight of 0.9% W/W saline, etc. In some embodiments, the material can absorb more than 15 times its own weight of 0.9% W/W saline, etc. In some embodiments, the material is capable of absorbing more than 20 times its own weight of 0.9% W/W saline, etc. Preferably, the material is capable of absorbing more than 30 times its own weight of 0.9% W/W saline, etc.

Preferably, the particles of superabsorber are very hydrophilic and grab the fluid as it enters the dressing, swelling up on contact. An equilibrium is set up within the dressing core whereby moisture passes from the superabsorber into the dryer surrounding area and as it hits the top film the film switches and the fluid vapor starts to be transpired. A moisture gradient is established within the dressing to continually remove fluid from the wound bed and ensure the dressing does not become heavy with exudate.

Preferably the absorbent layer includes at least one through hole located so as to underly the suction port. As illustrated in FIGS. 15A-B a single through hole can be used to produce an opening underlying the port 2150. It will be appreciated that multiple openings could alternatively be utilized. Additionally should more than one port be utilized according to certain embodiments of the present disclosure one or multiple openings may be made in the super-absorbent layer in registration with each respective port. Although not essential to certain embodiments of the present disclosure the use of through holes in the super-absorbent layer provide a fluid flow pathway which is particularly unhindered and this is useful in certain circumstances.

Where an opening is provided in the absorbent layer the thickness of the layer itself will act as a stand-off separating any overlying layer from the upper surface (that is to say the surface facing away from a wound in use) of the transmission layer 2105. An advantage of this is that the filter of the port is thus decoupled from the material of the transmission layer. This helps reduce the likelihood that the filter will be wetted out and thus will occlude and block further operation.

Use of one or more through holes in the absorption layer also has the advantage that during use if the absorbent layer contains a gel forming material, such as superabsorber, that material as it expands to absorb liquid, does not form a barrier through which further liquid movement and fluid movement in general cannot pass. In this way each opening in the absorbent layer provides a fluid pathway between the transmission layer directly to the wound facing surface of the filter and then onwards into the interior of the port.

A gas impermeable, but moisture vapor permeable, cover layer 2140 can extend across the width of the wound dressing, which can be any wound dressing embodiment disclosed herein including without limitation dressing embodiment 100 or have any combination of features of any number of wound dressing embodiments disclosed herein. The cover layer, which may for example be a polyurethane film (for example, Elastollan SP9109) having a pressure sensitive adhesive on one side, is impermeable to gas and this layer thus operates to cover the wound and to seal a wound cavity over which the wound dressing is placed. In this way an effective chamber is made between the cover layer and a wound site where a negative pressure can be established. The cover layer 2140 is sealed to the wound contact layer 2102 in a border region 2200 around the circumference of the dressing, ensuring that no air is drawn in through the border area, for example via adhesive or welding techniques. The cover layer 140 protects the wound from external bacterial contamination (bacterial barrier) and allows liquid from wound exudates to be transferred through the layer and evaporated from the film outer surface. The cover layer 2140 typically comprises two layers; a polyurethane film and an adhesive pattern spread onto the film. The polyurethane film is moisture vapor permeable and may be manufactured from a material that has an increased water transmission rate when wet.

The absorbent layer 2110 may be of a greater area than the transmission layer 2105, such that the absorbent layer overlaps the edges of the transmission layer 2105, thereby ensuring that the transmission layer does not contact the cover layer 2140. This provides an outer channel 2115 of the absorbent layer 2110 that is in direct contact with the wound contact layer 2102, which aids more rapid absorption of exudates to the absorbent layer. Furthermore, this outer channel 2115 ensures that no liquid is able to pool around the circumference of the wound cavity, which may otherwise seep through the seal around the perimeter of the dressing leading to the formation of leaks.

In order to ensure that the air channel remains open when a vacuum is applied to the wound cavity, the transmission layer 2105 must be sufficiently strong and non-compliant to resist the force due to the pressure differential. However, if this layer comes into contact with the relatively delicate cover layer 2140, it can cause the formation of pin-hole openings in the cover layer 2140 which allow air to leak into the wound cavity. This may be a particular problem when a switchable type polyurethane film is used that becomes weaker when wet. The absorbent layer 2110 is generally formed of a relatively soft, non-abrasive material compared to the material of the transmission layer 2105 and therefore does not cause the formation of pin-hole openings in the cover layer. Thus by providing an absorbent layer 2110 that is of greater area than the transmission layer 2105 and that overlaps the edges of the transmission layer 2105, contact between the transmission layer and the cover layer is prevented, avoiding the formation of pin-hole openings in the cover layer 2140.

The absorbent layer 2110 is positioned in fluid contact with the cover layer 2140. As the absorbent layer absorbs wound exudate, the exudate is drawn towards the cover layer 2140, bringing the water component of the exudate into contact with the moisture vapor permeable cover layer. This water component is drawn into the cover layer itself and then evaporates from the top surface of the dressing. In this way, the water content of the wound exudate can be transpired from the dressing, reducing the volume of the remaining wound exudate that is to be absorbed by the absorbent layer 2110, and increasing the time before the dressing becomes full and must be changed. This process of transpiration occurs even when negative pressure has been applied to the wound cavity, and it has been found that the pressure difference across the cover layer when a negative pressure is applied to the wound cavity has negligible impact on the moisture vapor transmission rate across the cover layer.

An orifice 2145 is provided in the cover film 2140 to allow a negative pressure to be applied to the dressing 2100. A suction port 2150 is sealed to the top of the cover film 2140 over the orifice 2145, and communicates negative pressure through the orifice 2145. A length of tubing 2220 may be coupled at a first end to the suction port 2150 and at a second end to a pump unit (not shown) to allow fluids to be pumped out of the dressing. The port may be adhered and sealed to the cover film 2140 using an adhesive such as an acrylic, cyanoacrylate, epoxy, UV curable or hot melt adhesive. The port 2150 is formed from a soft polymer, for example a polyethylene, a polyvinyl chloride, a silicone or polyurethane having a hardness of 30 to 90 on the Shore A scale.

An aperture or through-hole 2146 is provided in the absorbent layer 2110 beneath the orifice 2145 such that the orifice is connected directly to the transmission layer 2105. This allows the negative pressure applied to the port 2150 to be communicated to the transmission layer 2105 without passing through the absorbent layer 2110. This ensures that the negative pressure applied to the wound site is not inhibited by the absorbent layer as it absorbs wound exudates. In other embodiments, no aperture may be provided in the absorbent layer 2110, or alternatively a plurality of apertures underlying the orifice 2145 may be provided.

As shown in FIG. 15A, one embodiment of the wound dressing 2100 comprises an aperture 2146 in the absorbent layer 2100 situated underneath the port 2150. In use, for example when negative pressure is applied to the dressing 2100, a wound facing portion of the port 150 may thus come into contact with the transmission layer 2105, which can thus aid in transmitting negative pressure to the wound site even when the absorbent layer 2110 is filled with wound fluids. Some embodiments may have the cover layer 2140 be at least partly adhered to the transmission layer 2105. In some embodiments, the aperture 2146 is at least 1-2 mm larger than the diameter of the wound facing portion of the port 2150, or the orifice 2145.

A filter element 2130 that is impermeable to liquids, but permeable to gases is provided to act as a liquid barrier, and to ensure that no liquids are able to escape from the wound dressing. The filter element may also function as a bacterial barrier. Typically the pore size is 0.2 μm. Suitable materials for the filter material of the filter element 2130 include 0.2 micron Gore™ expanded PTFE from the MMT range, PALL Versapore™ 200R, and Donaldson™ TX6628. Larger pore sizes can also be used but these may require a secondary filter layer to ensure full bioburden containment. As wound fluid contains lipids it is preferable, though not essential, to use an oleophobic filter membrane for example 1.0 micron MMT-332 prior to 0.2 micron MMT-323. This prevents the lipids from blocking the hydrophobic filter. The filter element can be attached or sealed to the port and/or the cover film 2140 over the orifice 2145. For example, the filter element 2130 may be molded into the port 2150, or may be adhered to both the top of the cover layer 2140 and bottom of the port 2150 using an adhesive such as, but not limited to, a UV cured adhesive.

It will be understood that other types of material could be used for the filter element 2130. More generally a microporous membrane can be used which is a thin, flat sheet of polymeric material, this contains billions of microscopic pores. Depending upon the membrane chosen these pores can range in size from 0.01 to more than 10 micrometers. Microporous membranes are available in both hydrophilic (water filtering) and hydrophobic (water repellent) forms. In some embodiments of the disclosure, filter element 2130 comprises a support layer and an acrylic co-polymer membrane formed on the support layer. Preferably the wound dressing 2100 according to certain embodiments of the present disclosure uses microporous hydrophobic membranes (MHMs). Numerous polymers may be employed to form MHMs. For example, PTFE, polypropylene, PVDF and acrylic copolymer. All of these optional polymers can be treated in order to obtain specific surface characteristics that can be both hydrophobic and oleophobic. As such these will repel liquids with low surface tensions such as multi-vitamin infusions, lipids, surfactants, oils and organic solvents.

MHMs block liquids whilst allowing air to flow through the membranes. They are also highly efficient air filters eliminating potentially infectious aerosols and particles. A single piece of MHM is well known as an option to replace mechanical valves or vents. Incorporation of MHMs can thus reduce product assembly costs improving profits and costs/benefit ratio to a patient.

The filter element 2130 may also include an odor absorbent material, for example activated charcoal, carbon fiber cloth or Vitec Carbotec-RT Q2003073 foam, or the like. For example, an odor absorbent material may form a layer of the filter element 2130 or may be sandwiched between microporous hydrophobic membranes within the filter element.

The filter element 2130 thus enables gas to be exhausted through the orifice 2145. Liquid, particulates and pathogens however are contained in the dressing.

In FIG. 15B, an embodiment of the wound dressing 2100 is illustrated which comprises spacer elements 2152, 2153 in conjunction with the port 2150 and the filter 2130. With the addition of such spacer elements 2152, 2153, the port 2150 and filter 2130 may be supported out of direct contact with the absorbent layer 2110 and/or the transmission layer 2105. The absorbent layer 2110 may also act as an additional spacer element to keep the filter 2130 from contacting the transmission layer 2105. Accordingly, with such a configuration contact of the filter 2130 with the transmission layer 2105 and wound fluids during use may thus be minimized. As contrasted with the embodiment illustrated in FIG. 15A, the aperture 2146 through the absorbent layer 2110 may not necessarily need to be as large or larger than the port 2150, and would thus only need to be large enough such that an air path can be maintained from the port to the transmission layer 2105 when the absorbent layer 2110 is saturated with wound fluids.

In particular for embodiments with a single port 2150 and through hole, it may be preferable for the port 2150 and through hole to be located in an off-center position as illustrated in FIGS. 15A-B and in FIG. 16. Such a location may permit the dressing 2100 to be positioned onto a patient such that the port 2150 is raised in relation to the remainder of the dressing 2100. So positioned, the port 2150 and the filter 2130 may be less likely to come into contact with wound fluids that could prematurely occlude the filter 2130 so as to impair the transmission of negative pressure to the wound site.

FIG. 25 shows a plan view of a suction port 2150 according to some embodiments of the disclosure. The suction port comprises a sealing surface 2152 for sealing the port to a wound dressing, a connector portion 2154 for connecting the suction port 2150 to a source of negative pressure, and a hemispherical body portion 2156 disposed between the sealing surface 2152 and the connector portion 2154. Sealing surface 2152 comprises a flange that provides a substantially flat area to provide a good seal when the port 2150 is sealed to the cover layer 2140. Connector portion 2154 is arranged to be coupled to the external source of negative pressure via a length of tube 2220.

According to some embodiments, the filter element 2130 forms part of the bacterial barrier over the wound site, and therefore it is important that a good seal is formed and maintained around the filter element. However, it has been determined that a seal formed by adhering the filter element 2130 to the cover layer 2140 is not sufficiently reliable. This is a particular problem when a moisture vapor permeable cover layer is used, as the water vapor transpiring from the cover layer 2140 can affect the adhesive, leading to breach of the seal between the filter element and the cover layer. Thus, according to some embodiments of the disclosure an alternative arrangement for sealing the filter element 2130 to stop liquid from entering the connector portion 2154 is employed.

FIG. 26 illustrates a cross section through the suction port 2150 of FIG. 25 according to some embodiments of the disclosure, the line A-A in FIG. 25 indicating the location of the cross section. In the suction port of FIG. 26, the suction port 2150 further comprises filter element 2130 arranged within the body portion 2156 of the suction port 2150. A seal between the suction port 2150 and the filter element 2130 is achieved by molding the filter element within the body portion of the suction port 2150.

FIG. 27 illustrates a cross section through the suction port 2150 of FIG. 25 according to some embodiments of the disclosure that can be used with any dressing embodiment disclosed herein. In the suction port of FIG. 27, the filter element 2130 is sealed to the sealing surface 2152 of the suction port 2150. The filter element may be 2D sealed to the sealing surface using an adhesive or by welding the filter element to the sealing surface.

By providing the filter element 2130 as part of the suction port 2150, as illustrated in FIGS. 26 and 27, the problems associated with adhering the filter element to the cover layer 2140 are avoided allowing a reliable seal to be provided. Furthermore, providing a sub-assembly having the filter element 2130 included as part of the suction port 2150 allows for simpler and more efficient manufacture of the wound dressing 2100.

While the suction port 2150 has been described in the context of the wound dressing 2100 of FIG. 15, it will be understood that the embodiments of FIGS. 26 and 27 are applicable to any wound dressing for applying a negative pressure to a wound disclosed herein or otherwise, wherein wound exudate drawn from the wound is retained within the dressing. According to some embodiments of the disclosure, the suction port 2150 may be manufactured from a transparent material in order to allow a visual check to be made by a user for the ingress of wound exudate into the suction port 2150.

The wound dressing 2100 and its methods of manufacture and use as described herein may also incorporate features, configurations and materials described in the following patents and patent applications that are all incorporated by reference in their entireties herein: U.S. Pat. Nos. 7,524,315, 7,708,724, and 7,909,805; U.S. Patent Application Publication Nos. 2005/0261642, 2007/0167926, 2009/0012483, 2009/0254054, 2010/0160879, 2010/0160880, 2010/0174251, 2010/0274207, 2010/0298793, 2011/0009838, 2011/0028918, 2011/0054421, and 2011/0054423; as well as U.S. application Ser. No. 12/941,390, filed Nov. 8, 2010, Ser. No. 29/389,782, filed Apr. 15, 2011, and Ser. No. 29/389,783, filed Apr. 15, 2011. From these incorporated by reference patents and patent applications, features, configurations, materials and methods of manufacture or use for similar components to those described in the present disclosure may be substituted, added or implemented into embodiments of the present application.

In operation the wound dressing 2100 is sealed over a wound site forming a wound cavity. A pump unit (illustrated in FIG. 42 and described in further detail below) applies a negative pressure at a connection portion 2154 of the port 2150 which is communicated through the orifice 2145 to the transmission layer 2105. Fluid is drawn towards the orifice through the wound dressing from a wound site below the wound contact layer 2102. The fluid moves towards the orifice through the transmission layer 2105. As the fluid is drawn through the transmission layer 2105 wound exudate is absorbed into the absorbent layer 2110.

Turning to FIG. 16 which illustrates a wound dressing 2100 in accordance with an embodiment of the present disclosure one can see the upper surface of the cover layer 2140 which extends outwardly away from a centre of the dressing into a border region 2200 surrounding a central raised region 2201 overlying the transmission layer 2105 and the absorbent layer 2110. As indicated in FIG. 16 the general shape of the wound dressing is rectangular with rounded corner regions 2202. It will be appreciated that wound dressings according to other embodiments of the present disclosure can be shaped differently such as square, circular or elliptical dressings, or the like.

The wound dressing 2100 may be sized as necessary for the size and type of wound it will be used in. In some embodiments, the wound dressing 2100 may measure between 20 and 40 cm on its long axis, and between 10 to 25 cm on its short axis. For example, dressings may be provided in sizes of 10×20 cm, 10×30 cm, 10×40 cm, 15×20 cm, and 15×30 cm. In some embodiments, the wound dressing 2100 may be a square-shaped dressing with sides measuring between 15 and 25 cm (e.g., 15×15 cm, 20×20 cm and 25×25 cm). The absorbent layer 2110 may have a smaller area than the overall dressing, and in some embodiments may have a length and width that are both about 3 to 10 cm shorter, more preferably about 5 cm shorter, than that of the overall dressing 2100. In some rectangular-shape embodiments, the absorbent layer 2110 may measure between 10 and 35 cm on its long axis, and between 5 and 10 cm on its short axis. For example, absorbent layers may be provided in sizes of 5.6×15 cm or 5×10 cm (for 10×20 cm dressings), 5.6×25 cm or 5×20 cm (for 10×30 cm dressings), 5.6×35 cm or 5×30 cm (for 10×40 cm dressings), 10×15 cm (for 15×20 cm dressings), and 10×25 cm (for 15×30 cm dressings). In some square-shape embodiments, the absorbent layer 2110 may have sides that are between 10 and 20 cm in length (e.g., 10×10 cm for a 15×15 cm dressing, 15×15 cm for a 20×20 cm dressing, or 20×20 cm for a 25×25 cm dressing). The transmission layer 2105 is preferably smaller than the absorbent layer, and in some embodiments may have a length and width that are both about 0.5 to 2 cm shorter, more preferably about 1 cm shorter, than that of the absorbent layer. In some rectangular-shape embodiments, the transmission layer may measure between 9 and 34 cm on its long axis and between 3 and 5 cm on its short axis. For example, transmission layers may be provided in sizes of 4.6×14 cm or 4×9 cm (for 10×20 cm dressings), 4.6×24 cm or 4×19 cm (for 10×30 cm dressings), 4.6×34 cm or 4×29 cm (for 10×40 cm dressings), 9×14 cm (for 15×20 cm dressings), and 9×24 cm (for 15×30 cm dressings). In some square-shape embodiments, the transmission layer may have sides that are between 9 and 19 cm in length (e.g., 9×9 cm for a 15×15 cm dressing, 14×14 cm for a 20×20 cm dressing, or 19×19 cm for a 25×25 cm dressing).

It will be understood that according to embodiments of the present disclosure the wound contact layer is optional. This layer is, if used, porous to water and faces an underlying wound site. A transmission layer 2105 such as an open celled foam, or a knitted or woven spacer fabric is used to distribute gas and fluid removal such that all areas of a wound are subjected to equal pressure. The cover layer together with the filter layer forms a substantially liquid tight seal over the wound. Thus when a negative pressure is applied to the port 2150 the negative pressure is communicated to the wound cavity below the cover layer. This negative pressure is thus experienced at the target wound site. Fluid including, air and wound exudate is drawn through the wound contact layer and transmission layer 2105. The wound exudate drawn through the lower layers of the wound dressing is dissipated and absorbed into the absorbent layer 2110 where it is collected and stored. Air and moisture vapor is drawn upwards through the wound dressing through the filter layer and out of the dressing through the suction port. A portion of the water content of the wound exudate is drawn through the absorbent layer and into the cover layer 2140 and then evaporates from the surface of the dressing.

As discussed above, when a negative pressure is applied to a wound dressing sealed over a wound site, in some dressing embodiments disclosed herein, fluids including wound exudate are drawn from the wound site and through the transmission layer 2105 toward the orifice 2145. Wound exudate is then drawn into the absorbent layer 2110 where it is absorbed. However, some wound exudate may not be absorbed and may move to the orifice 2145. Filter element 2130 provides a barrier that stops any liquid in the wound exudate from entering the connection portion 2154 of the suction port 2150. Therefore, unabsorbed wound exudate may collect underneath the filter element 2130. If sufficient wound exudate collects at the filter element, a layer of liquid wilt form across the surface of filter element 2130 and the filter element will become blocked as the liquid cannot pass through the filter element 2130 and gases will be stopped from reaching the filter element by the liquid layer. Once the filter element becomes blocked, negative pressure can no longer be communicated to the wound site, and the wound dressing must be changed for a fresh dressing, even though the total capacity of the absorbent layer has not been reached.

In a preferred embodiment, the port 2150, along with any aperture 2146 in the absorbing layer 2110 situated below it, generally aligns with the mid-longitudinal axis A-A illustrated in FIG. 16. Preferably, the port 2150 and any such aperture 2146 are situated closer to one end of the dressing, contrasted with a central position. In some embodiments, the port may be located at a corner of the dressing 2100, which again can be any dressing embodiment disclosed herein including without limitation dressing embodiment 100. For example, in some rectangular embodiments, the port 2150 may be located between 4 and 6 cm from the edge of the dressing, with the aperture 146 located 2 to 3 cm from the edge of the absorbent layer. In some square embodiments, the port 2150 may be located between 5 to 8 cm from the corner of the dressing, with the aperture 2146 located 3 to 5 cm from the corner of the absorbent layer.

Certain orientations of the wound dressing may increase the likelihood of the filter element 130 becoming blocked in this way, as the movement of the wound exudate through the transmission layer may be aided by the effect of gravity. Thus, if due to the orientation of the wound site and wound dressing, gravity acts to increase the rate at which wound exudate is drawn towards the orifice 2145, the filter may become blocked with wound exudate more quickly. Thus, the wound dressing would have to be changed more frequently and before the absorbent capacity of the absorbent layer 2110 has been reached.

In order to avoid the premature blocking of the wound dressing 2100 by wound exudate drawn towards the orifice 2145 some embodiments of the disclosure include at least one element configured to reduce the rate at which wound exudate moves towards the orifice 2145. The at least one element may increase the amount of exudate that is absorbed into the absorbent layer before reaching the orifice. 2145 and/or may force the wound exudate to follow a longer path through the dressing before reaching the orifice 2145, thereby increasing the time before the wound dressing becomes blocked.

FIG. 17 shows a plan view of a wound dressing including baffle elements that reduce the rate at which wound exudate moves towards the orifice according to one embodiment of the disclosure. The wound dressing illustrated in FIG. 17 is similar to that shown in FIGS. 15 and 16, but includes a number of baffle elements 2310 disposed across the central raised region 2201. The baffle elements 2310 form barriers in the central region of the dressing, which arrest the movement of wound exudate towards the orifice.

Embodiments of baffle elements that may be used in the wound dressing described herein are preferably at (east partly flexible, so as to permit the wound dressing to flex and conform with the skin of the patient surrounding the wound site. When so present in the wound dressing, the baffle elements are preferably constructed so as to at least partially prevent liquid from flowing directly to the wound dressing port or orifice and its associated filter, if so provided. The baffle elements thus increase the distance that liquids may require to reach the port, which may help in absorbing these fluids into the absorbent or superabsorbent material of the wound dressing.

According to some embodiments of the disclosure, the baffle element may comprise a sealing region in which the absorbent layer 2110 and transmission layer 2105 are absent and cover layer 2140 is sealed to the wound contact layer 2101. Thus, the baffle element presents a barrier to the motion of the wound exudate, which must therefore follow a path that avoids the baffle element. Thus the time taken for the wound exudate to reach the orifice is increased.

In some embodiments, the baffle elements may be an insert of a substantially non-porous material, for example a closed-cell polyethylene foam, placed inside the dressing. In some cases, it may be preferable to place such an inserted baffle element in a sealing region where one or more of the absorbent layer 2110 and/or transmission layer 2105 are absent. A sealant, for example a viscous curing sealant such as a silicone sealant, could be placed or injected as a thin strip so as to form a baffle element that is substantially liquid impermeable. Such a baffle element could be placed or infected into a region of the transmission layer 2105 and/or absorbent layer 2110, or also a sealing region where the absorbent layer 2110 and/or transmission layer 2105 are absent.

FIG. 20 illustrates a wound dressing, which can be any embodiment of a wound dressing disclosed herein, including a baffle element according to a further embodiment of the disclosure. A single baffle element 2610 provides a cup shaped barrier between the bulk of the absorbent layer 2110 and the orifice 2145. Thus wound exudate that is initially drawn from the wound site within the region defined by the baffle element 2610, must follow a path around the outside of the cup shaped barrier to reach the orifice 2145. As will be recognized, the baffle element 2610 reduces the effect of gravity on reducing the time taken for the wound exudate to move to the orifice 2145, as for most orientations of the wound dressing at least a part of the path taken by the wound exudate will be against the force of gravity.

The embodiments of FIGS. 17 and 20 have been described with respect to a wound dressing having a structure as shown in FIG. 15. However, it will be understood that the baffle elements could equally be applied to a wound dressing in which the transmission layer 2105 was absent.

FIG. 18 shows a plan view of a wound dressing including the at least one element according to one embodiment of the disclosure in which a number of baffle elements 2410 are provided that extend across the width of the central region 2201 of the wound dressing, with further baffle elements 2412 formed in a semi-circular path around the orifice 2145.

FIG. 19 illustrates the configuration of baffle elements 2410 according to some embodiments of the disclosure. The baffle element comprises a channel of absorbent material 2510 underlying the transmission layer 2105. A channel in the absorbent layer 2110 is located over the baffle element 2410 so that the transmission layer is in contact with the cover layer 2140 in the region of the baffle element 2410. Thus, wound exudate that is moving along a lower surface of the transmission layer 2105, and has therefore not been drawn into absorbent layer 2110, will come into contact with and be absorbed by the channel of absorbent material 2510.

Alternatively, or additionally, baffle elements may comprise one or more channels provided in the surface of the transmission layer 2105 underlying and abutting the absorbent layer 2110. In use, when negative pressure is applied to the wound dressing, the absorbent layer 2110 will be drawn into the channel. The channel in the transmission layer may have a depth substantially equal to the depth of the transmission layer, or may have a depth less than the depth of the transmission layer. The dimensions of the channel may be chosen to ensure that the channel is filled by the absorbent layer 2110 when negative pressure is applied to the wound dressing. According to some embodiments, the channel in the transmission layer comprises a channel of absorbent material in the transmission layer 2105.

The baffle elements may be formed into a range of shapes and patterns, for example FIGS. 28A to 28L illustrate wound dressings having a number of different exemplifying configurations of baffle elements. FIG. 28A illustrates a linear baffle element in a vertical configuration aligned in the direction of the port or orifice. FIG. 28B illustrates an X-shaped baffle element. FIGS. 28C-E illustrate embodiments of wound dressings with multiple baffle elements, aligned in a generally diagonal, horizontal, or vertical manner.

FIG. 28F illustrates baffle elements arranged in a six-armed starburst configuration, with a center portion left open. FIG. 28G illustrates a W-shaped baffle element on the wound dressing in a position distal to the port or orifice. In FIG. 28H, an 3-by-3 array of X-shaped baffle elements is provided on the wound dressing, although it will be understood that more or less X-shaped baffle elements may be used. FIG. 28I shows an embodiment with a plurality of rectangular bathe elements, and wherein one or more baffle elements are located underneath the port in the wound dressing. FIGS. 28J-K illustrate wound dressing embodiments with longer diagonal and horizontal baffle elements. In FIG. 28L, rectangular baffle elements are present on this embodiment of a wound dressing, wherein the baffle elements are of different sizes.

According to some embodiments of the disclosure, the at least one element comprises an array of vias, or troughs, in the transmission layer 2105. FIG. 29 illustrates a transmission layer 2105 that is perforated with diamond shaped vias 2210. The vias 2210 are arranged such that no linear pathway exists through the pattern of vias that does not intersect with one or more of the vias 2210.

When negative pressure is applied to the wound dressing, the absorbent layer 2110 is drawn into the vias 2210, increasing the area of the absorbent layer that comes into contact with wound exudate being drawn through the transmission layer 2105. Alternatively, the vias 2210 may be filled with further absorbent material for absorbing wound exudate being drawn through the transmission layer 2105. The vias may extend through the depth of the transmission layer 2105, or may extend through only part of the transmission layer.

Wound exudate moving through the transmission layer 2105 under the influence of gravity will fall through the transmission layer in a substantially linear manner. Any such linear pathways will, at some point, intersect with one of the vias 2210, and thus the exudate will be brought into contact with absorbent material within the vias 2210. Wound exudate coming into contact with absorbent material will be absorbed, stopping the flow of the wound exudate through the transmission layer 2105, and reducing the amount of unabsorbed wound exudate that may otherwise pool around the orifice. It will be appreciated that the vias are not limited to diamond shapes, and that any pattern of vias may be used. Preferably, the vias will be arranged to ensure that all linear paths through the transmission layer 2105 intersect with at least one via. The pattern of vias may be chosen to minimize the distance that wound exudate is able to travel though the transmission layer before encountering a via and being absorbed.

FIG. 21 illustrates a wound dressing in accordance with some embodiments of the disclosure in which the at least one element comprises an air channel 2710 connecting the central region 2201 of the wound dressing to the orifice 2145. In the embodiment of FIG. 21, the air channel 2710 extends from an edge region of the transmission layer 2105 and connects the transmission layer to the orifice 2145.

In use, wound exudate is drawn towards the orifice 2145 by the application of negative pressure at the suction port 2150. However, the air channel 2710 present a relatively long serpentine path to be followed by the wound exudate before it reaches the orifice 2145. This long path increases the time that negative pressure can be applied to the dressing before wound exudate traverses the distance between the transmission layer and the orifice and blocks the filter element 2130, thereby increasing the time the dressing can be in use before it must be replaced.

FIG. 22 illustrates a wound dressing in accordance with one embodiment of the disclosure in which the at least one element comprises air channels 2810 and 2812 connecting the central region 2201 of the wound dressing to the orifice 2145. Channels 2810 and 2812 are coupled to the transmission layer at substantially opposite corners of the central region 2201.

The wound dressing shown in FIG. 22 reduces the effect of gravity on the time taken for the orifice to become blocked. If the wound dressing is in an orientation in which wound exudate moves under the influence of gravity towards the edge region of the transmission layer connected to air channel 2810, the effect of gravity will be to move wound exudate away from the edge region of the transmission layer coupled to air channel 2812, and vice versa. Thus, the embodiment of FIG. 22 provides alternative air channels for coupling the negative pressure to the transmission layer such that, should one air channel become blocked a remaining air channel should remain open and able to communicate the negative pressure to the transmission layer 2105, thereby increasing the time before negative pressure can no longer be applied to the wound dressing and the dressing must be changed.

Further embodiments of the disclosure may comprise greater numbers of air channels connecting the transmission layer 2105 to the orifice.

According to some embodiments of the disclosure, two or more orifices may be provided in the cover layer 2140 for applying the negative pressure to the wound dressing. The two or more orifices can be distributed across the cover layer 2140 such that if one orifice becomes blocked by wound exudate due to the wound dressing being in a particular orientation, at least one remaining orifice would be expected to remain unblocked. Each orifice is in fluid communication with a wound chamber defined by the wound dressing, and is therefore able to communicate the negative pressure to the wound site.

FIG. 23 illustrates a wound dressing in accordance with a further embodiment of the disclosure. The wound dressing of FIG. 23 is similar to that of FIGS. 15A-B but includes two orifices 2145 and 2845 provided in the cover layer 2140. A fluid communication passage connects the two orifices such that a negative pressure applied to one of the orifices is communicated to the remaining orifice via the fluid communication passage. The orifices 2145, 2845 are located in opposite corner regions of the cover layer 2140. The fluid communication passage is formed using a flexible molding 2910 on the upper surface of the cover layer 2140. It will be appreciated that the flexible molding may be formed from other suitable means for example a strip of transmission or open porous foam layer placed on the cover layer 2140 between the orifices 2145 and 2845 and a further film welded or adhered over the strip thus sealing it to the cover layer and forming a passageway through the foam. A conduit may then be attached in a known manner to the sealing film for application of negative pressure.

In use, the wound dressing having two orifices is sealed over a wound site to form a wound cavity and an external source of negative pressure is applied to one of the orifices 2145, 2845, and the negative pressure will be communicated to the remaining orifice via the fluid communication passage. Thus, the negative pressure is communicated via the two orifices 2145, 845 to the transmission layer 2105, and thereby to the wound site. If one of the orifices 2145, 2845 becomes blocked due to wound exudate collecting at the orifice under the influence of gravity, the remaining orifice should remain clear, allowing negative pressure to continue to be communicated to the wound site. According to some embodiments, the transmission layer 2105 may be omitted, and the two orifices will communicate the negative pressure to the wound site via the absorbent layer 2110.

FIG. 24 illustrates a side view of the fluid communication passage of the embodiment of FIG. 23. Molding 2910 is sealed to the top surface of the cover layer 2140, and covering orifices 2145 and 2845. Gas permeable liquid impermeable filter elements 2130 are provided at each orifice. The molding 2910 is coupled to an external source of negative pressure via a tube element 2220.

According to some embodiments, a single filter element may be used extending underneath the length of the fluid communication passage and the two orifices. While the above example embodiment has been described as having two orifices, it will be understood that more than two orifices could be used, the fluid communication passage allowing the negative pressure to be communicated between the orifices.

FIG. 30 illustrates an alternative arrangement in which a single elongate orifice 2350 is provided in the cover layer 2140. First and second ends 2355, 2356 of the orifice 2350 are located in opposite corner regions of the cover layer 2140. A flexible molding 2360 is sealed around the orifice 2350 and allows negative pressure to be communicated through the cover layer 2140 along the length of the orifice 2350. The flexible molding 2360 may be formed by any suitable means as described above in relation to flexible molding 2910.

In use, the wound dressing is sealed over a wound site to form a wound cavity and an external source of negative pressure is applied to the orifice. If, due to the orientation of the wound dressing, wound exudate moves under the influence of gravity to collect around one end 2355 of the orifice 2350, a portion of the orifice 2350 near to the end 2355 will become blocked. However, a portion of the orifice near to the remaining end 2356 should remain clear, allowing continued application of negative pressure to the wound site.

As still further options the dressing can contain anti-microbial e.g. nanocrystalline silver agents on the wound contact layer and/or silver sulphur diazine in the absorbent layer. These may be used separately or together. These respectively kill micro-organisms in the wound and micro-organisms in the absorption matrix. As a still further option other active components, for example, pain suppressants, such as ibuprofen, may be included. Also agents which enhance cell activity, such as growth factors or that inhibit enzymes, such as matrix metalloproteinase inhibitors, such as tissue inhibitors of metalloproteinase (TIMPS) or zinc chelators could be utilized. As a still further option odor trapping elements such as activated carbon, cyclodextrine, zeolite or the like may be included in the absorbent layer or as a still further layer above the filter layer.

FIG. 31 illustrates a first, upper surface 3700 and a further, lower surface 3702 of a transmission layer 2105 according to an embodiment of the present disclosure. In the embodiment illustrated in FIG. 31 fibers 3703 of a woven layer extend between the first surface 3700 and the further surface 3702. It will be appreciated that according to further embodiments of the present disclosure if a foam layer is used as a transmission layer 2105 the connected strands forming the foam will act as spacer elements. As illustrated in FIG. 31 in a relaxed mode of operation, that is to say when in use, no negative pressure is applied to the wound dressing or negative pressure is applied to the wound dressing but no external force acts on the wound dressing then the fibers 3703 extend substantially perpendicular to the upper and lower surfaces keeping the surfaces in a spaced apart substantially parallel configuration.

FIG. 32 illustrates the transmission layer 2105 when an external force is exerted on the outside of the dressing. The external force can be a compressive force indicated by arrow A and/or a lateral force illustrated by arrow B in FIG. 32. As indicated either a compressive force or a lateral force acts to cause the fibers 3703 to lean to one side. This causes the upper and lower surfaces to become laterally offset with respect to each other as well as causing the thickness of the layer to reduce from a separation distance r indicated in FIG. 31 in a relaxed mode of operation to a compression distance c illustrated in FIG. 32. The reduction in thickness effectively provides some “give” in the dressing even when the dressing is subject to negative pressure. It will be appreciated that the forces acting on the dressing may occur throughout the whole of the surface area of the dressing or only in one or more particular regions. In such a situation regions of the dressing can be in a relaxed mode of operation and further regions can be in a compressed mode of operation. As illustrated in FIG. 32 when a force is exerted on the transmission layer the fibers separating the upper and lower surfaces tend to lean to one side sharing a common lean angle.

Throughout this specification reference will be made to a relaxed mode of operation and a forced mode of operation. It is to be understood that the relaxed mode of operation corresponds to a natural state of the material either when no negative pressure is applied or when negative pressure is applied. In either situation no external force, caused for example by motion of a patient or an impact is in evidence. By contrast a forced mode of operation occurs when an external force whether compressive, lateral or other is brought to bear upon the wound dressing. Such forces can cause serious damage/prevent healing or a wound.

FIG. 33 illustrates how certain embodiments of the present disclosure can also operate to offset load forces. As illustrated in FIG. 33 if a force is exerted over a contact area 3900 in an upper surface 3700 of the transmission layer 2105 then this force is transmitted across and through the transmission layer and is exerted over a larger dissipation area 3901 against an underlying wound site. In the case of use of a 3D knit as a transmission layer this is because the relatively stiff spacer elements provide at least some lateral stiffness to the layer.

FIG. 34 illustrates the transmission layer 2105 and absorbent layer 2110 of some embodiments in more detail. The absorbent layer 2110 is located proximate to the upper surface 3700 of the transmission layer 2105 and is unbonded thereto according to certain embodiments of the present disclosure. When unbonded the absorbent layer 2110 is also able to move laterally with respect to the underlying transmission layer when a lateral or shear force is applied to the wound dressing. Also the absorbent layer is able to further compress when a compressive force illustrated in FIG. 35 acts on the wound dressing. As illustrated in FIG. 35 the absorbent layer 2110 decreases in thickness under a compressive force from a non-compressed thickness x illustrated in FIG. 34 to a compressed distance y illustrated in FIG. 35. The compressive force also acts to offset the upper and lower surfaces of the transmission layer as described above thus enhancing the “give” of the dressing. The ability for an upper surface 4201 to translate laterally with respect to a lower surface 4202 of the absorbent layer under a lateral or shearing force exerted on the wound dressing is illustrated in more detail in FIG. 36. This lateral motion causes the thickness x of the absorbent layer 2110 to reduce and the upper surface and lower surface of the absorbent layer to be offset with respect to each other. This effect can itself be sufficient to prevent shear forces exerted on the whole or part of the wound dressing from being transferred to an underlying wound bed. As can the corresponding effect in the transmission layer. However a combination enhances the cushioning effect. If the wound bed comprises a skin graft region the reduction of shear forces can be particularly advantageous.

It is to be noted that in use the dressing may be used “up-side down”, at an angle or vertical. References to upper and lower are thus used for explanation purposes only.

FIG. 37 illustrates a cross-section, of a portion of an embodiment of a dressing shown in FIGS. 15A-16. In particular, FIG. 37 illustrates a magnified view of the wound contact layer 2102 which includes a lower surface 2101 and multiple perforations 2104 formed as through holes. An upper surface 2104 of the wound contact layer abuts a first layer 2300 of the transmission layer 2105. A further, upper, layer 2301 of the transmission layer 2105 is spaced apart from the first layer. The first and further layers of the transmission layer are kept apart in a spaced apart relationship by multiple mono-filament fiber spacers 2302 which act as resilient flexible pillars separating the two layers of the transmission layer. The upper layer 2301 of the transmission layer is adjacent a lower surface of the absorbent 2110 which, for example, is formed as a pad of fibrous cellulose material interspaced with super-absorbent particulate matter.

FIG. 38 illustrates the lower layer of the 3D fabric transmission layer in more detail. The 3D fabric layer 2105 is formed as a lower and upper knitted layer given a loft by the knitted structure. Rows of the knitted stitches may be referred to as a course of stitches. Columns of stitches may be referred to as a whale. A single monofilament fiber is knitted into the 3D fabric to form the multiple separating strands.

As illustrated in FIG. 38 there are apertures or openings formed between interlocked stitches in the lower layer of the transmission layer 2105. In use, wound exudate including liquid and semi-solid e.g. viscous slurry, suspensions of biological debris or the like and solid material will pass upwards through the perforations 2104 in the wound contact layer and through the openings in the inter knitted structure of the first layer 2300 of the transmission layer. The openings between the interconnected stitches have an average open area ranging from around 2250 microns to 450 microns. The particular open area in the first layer of the transmission layer will be determined by the materials and method of manufacture of the lower layer. FIG. 39 illustrates how an open area of openings in the further layer above the first layer (that is to say further away from the wound) can include openings which have a greater open area than the openings in the lower layer. In this way as wound exudate which includes semi-solid and solid matter moves from the wound bed at the wound site upwards into the wound dressing any particulate matter which is of a size small enough to pass through the relative small openings 2400 in the lower layer will certainly be able to pass through the larger area openings 2501 in the upper area. This helps avoid debris in the form of solid material collecting in the interstitial region between the monofilament fibers between the upper and lower layer. As shown in FIG. 39, the upper layer 2301 may include openings 2500 similar to the openings 2400 in the lower layer 2300. However, during the knitting process the upper surface is knitted so that larger open area openings 2501 are interspersed across the whole surface of the upper layer. As illustrated in FIG. 39 the larger open area openings 2501 can have an open range considerably larger (shown between 2700 to 800 microns). The lower layer 2300 thus acts to some extent as a filtering layer having openings 2400 which enable gas and liquid to pass freely therethrough but to prevent solid and semi-solid particulate matter which is too large from passing in to the interstitial region in the transmission layer 2105. This helps keep a flowpath along the transmission layer open.

By providing openings in an upper layer in the transmission layer which have a greater open area than any openings in the lower area build-up of solid particulate matter in the interstitial region between the upper and lower layers of the transmission layer is avoided since any solid or semi-solid matter will flow along the channel and eventually be enabled to pass upwards through the larger openings where the material is taken up by the super-absorber/absorbent material.

The absorbent layer 2110 holds liquid collected during the application of negative pressure therapy. By having this layer in fluid communication with, and preferably in contact with, the layer of the transmission layer, the region of the transmission layer 2105 is kept at a moist environment. This helps avoid build-up and crusting of the exudate during use.

FIG. 40 illustrates an alternative material which could be utilized as the transmission layer in a wound dressing. In particular, FIG. 40 illustrates a lower surface of a 3D knit material which may be utilized as the transmission layer. Openings 2600 are formed in the surface which enables wound exudate and air to pass from the wound through a wound contact layer which would be located on the surface shown in FIG. 20 and through those openings. FIG. 41 illustrates an upper surface of the material shown in FIG. 40 and illustrates how larger openings 2700 may be formed in the upper surface.

Whilst certain embodiments of the present disclosure have so far been described in which the transmission layer is formed as a 3D knit layer, e.g., two layers spaced apart by a monofilament layer, it will be appreciated that certain embodiments of the present disclosure are not restricted to the use of such a material. In some embodiments, as an alternative to such a 3D knit material one or more layers of a wide variety of materials could be utilized. In each case, according to embodiments of the present disclosure, the openings presented by layers of the transmission layer are wider and wider as one moves away from the side of the dressing which, in use will be located proximate to the wound. In some embodiments, the transmission layer may be provided by multiple layers of open celled foam. In some embodiments, the foam is reticulated open cell foam. Preferably, the foam is hydrophilic or able to wick aqueous based fluids. The pore size in each layer is selected so that in the foam layer most proximate to the wound side in use the pores have a smallest size. If only one further foam layer is utilized that includes pore sizes which are greater than the pore sizes of the first layer. This helps avoid solid particulate being trapped in the lower layer which thus helps maintain the lower layer in an open configuration in which it is thus able to transmit air throughout the dressing. In certain embodiments, two, three, four or more foam layers may be included. The foam layers may be integrally formed, for example, by selecting a foam having a large pore size and then repeatedly dipping this to a lesser and lesser extent into material which will clog the pores or alternatively, the transmission layer formed by the multiple foam layers may be provided by laminating different types of foam in a layered arrangement or by securing such layers of foam in place in a known manner.

According to certain embodiments of the present disclosure, the transmission layer is formed by multiple layers of mesh instead of foam or 3D knit materials. For example, fine gauze mesh may be utilized for a wound facing side of the transmission layer and a Hessian mesh having a larger pore size may be located on a distal side of the gauze mesh facing away from the wound in use. The one, two, three or more layers of mesh can be secured together in an appropriate manner, such as being stitched or adhered together or the like. The resultant mat of fibers provides a transmittal layer through which air can be transmitted in the dressing but by selecting the opening sizes in the meshes as one moves through the dressing away from the wound contact side, the accumulation of solid particulate matter in lower layers can be avoided.

FIG. 42 illustrates an embodiment of a TNP wound treatment comprising a wound dressing 2100 in combination with a pump 2800. As stated above, the wound dressing 2100 can be any wound dressing embodiment disclosed herein including without limitation dressing embodiment 100 or have any combination of features of any number of wound dressing embodiments disclosed herein. Here, the dressing 2100 may be placed over a wound as described previously, and a conduit 2220 may then be connected to the port 2150, although in some embodiments the dressing 2100 may be provided with at least a portion of the conduit 2220 preattached to the port 2150. Preferably, the dressing 2100 is provided as a single article with all wound dressing elements (including the port 2150) pre-attached and integrated into a single unit. The wound dressing 2100 may then be connected, via the conduit 2220, to a source of negative pressure such as the pump 2800. The pump 2800 can be miniaturized and portable, although larger conventional pumps may also be used with the dressing 2100. In some embodiments, the pump 2800 may be attached or mounted onto or adjacent the dressing 2100. A connector 2221 may also be provided so as to permit the conduit 2220 leading to the wound dressing 2100 to be disconnected from the pump, which may be useful for example during dressing changes.

FIGS. 43A-D illustrate the use of an embodiment of a TNP wound treatment system being used to treat a wound site on a patient. FIG. 43A shows a wound site 2190 being cleaned and prepared for treatment. Here, the healthy skin surrounding the wound site 2190 is preferably cleaned and excess hair removed or shaved. The wound site 2190 may also be irrigated with sterile saline solution if necessary. Optionally, a skin protectant may be applied to the skin surrounding the wound site 2190. If necessary, a wound packing material, such as foam or gauze, may be placed in the wound site 2190. This may be preferable if the wound site 2190 is a deeper wound.

After the skin surrounding the wound site 2190 is dry, and with reference now to FIG. 43B, the wound dressing 2100 may be positioned and placed over the wound site 2190. Preferably, the wound dressing 2100 is placed with the wound contact layer 2102 over and/or in contact with the wound site 2190. In some embodiments, an adhesive layer is provided on the lower surface 2101 of the wound contact layer 2102, which may in some cases be protected by an optional release layer to be removed prior to placement of the wound dressing 2100 over the wound site 2190. Preferably, the dressing 2100 is positioned such that the port 2150 is in a raised position with respect to the remainder of the dressing 2100 so as to avoid fluid pooling around the port. In some embodiments, the dressing 2100 is positioned so that the port 2150 is not directly overlying the wound, and is level with or at a higher point than the wound. To help ensure adequate sealing for TNP, the edges of the dressing 2100 are preferably smoothed over to avoid creases or folds.

With reference now to FIG. 43C, the dressing 2100 is connected to the pump 2800. The pump 2800 is configured to apply negative pressure to the wound site via the dressing 2100, and typically through a conduit. In some embodiments, and as described above in FIG. 42, a connector may be used to join the conduit from the dressing 2100 to the pump 2800. Upon the application of negative pressure with the pump 2800, the dressing 2100 may in some embodiments partially collapse and present a wrinkled appearance as a result of the evacuation of some or all of the air underneath the dressing 2100. In some embodiments, the pump 2800 may be configured to detect if any leaks are present in the dressing 2100, such as at the interface between the dressing 2100 and the skin surrounding the wound site 2190. Should a leak be found, such leak is preferably remedied prior to continuing treatment.

Turning to FIG. 43D, additional fixation strips 2195 may also be attached around the edges of the dressing 2100. Such fixation strips 2195 may be advantageous in some situations so as to provide additional sealing against the skin of the patient surrounding the wound site 2190. For example, the fixation strips 2195 may provide additional sealing for when a patient is more mobile. In some cases, the fixation strips 2195 may be used prior to activation of the pump 2800, particularly if the dressing 2100 is placed over a difficult to reach or contoured area.

Treatment of the wound site 2190 preferably continues until the wound has reached a desired level of healing. In some embodiments, it may be desirable to replace the dressing 2100 after a certain time period has elapsed, or if the dressing is full of wound fluids. During such changes, the pump 2800 may be kept, with just the dressing 2100 being changed.

With the some embodiments of the present disclosure, a wound dressing is provided that helps improve patient concordance with instructions for use, helps improve patients” quality of life, and also helps a clinician observe and monitor a patient's wound.

It will be clear to a person skilled in the art that features described in relation to any of the embodiments described above can be applicable interchangeably between the different embodiments. The embodiments described above are examples to illustrate various features of the present invention or inventions.

Throughout the description and claims of this specification, the words “comprise” and “contain” and variations of them mean “including but not limited to”, and they are not intended to (and do not) exclude other moieties, additives, components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the present disclosure are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

Claims

1. A wound dressing, comprising:

a wound contact layer;

a cover layer sealed to the wound contact layer;

an absorbent layer for absorbing wound exudate positioned between the wound contact layer and the cover layer; and

at least one layer positioned between the absorbent layer and the wound contact layer; wherein a dimension of the absorbent layer is larger than a dimension of the at least one layer such that a radially outer region of the absorbent layer forms an enclosure with the wound contact layer around the at least one layer;

wherein the dressing is shaped to include wound contact layer, cover layer, and absorbent layer are shaped in a conformable shape including a plurality of sub-areas, wherein the dressing conformable shape has rotational symmetry around a center point of the conformable shape, and the sub areas define areas of the dressing that are formable in different directions with respect to each other.

2. The wound dressing of claim 1, wherein the dressing comprises four sub-areas.

3. The wound dressing of claim 1, further comprising at least one of a wound contact layer, a foam layer, an odour controlling element, a shielding layer and a cover layer.

4. A wound dressing comprising:

a wound contact layer;

a cover layer sealed to the wound contact layer; and

an absorbent layer for absorbing wound exudate positioned between the wound contact layer and the cover layer; and

a masking layer for at least partially obscuring a view of wound exudate absorbed by the absorbent layer in use, the masking layer positioned between the absorbent layer and the cover layer;

wherein the wound contact layer, cover layer, and absorbent layer and masking layer are shaped in a conformable shape including a plurality of sub-areas, wherein the sub areas define areas of the wound dressing that are formable in different directions with respect to each other;

wherein the conformable shape has rotational symmetry around a center point of the conformable shape, and

wherein the conformable shape of the masking layer has a smaller dimension than the conformable shape of the absorbent layer whereby the masking layer is positioned over a central region of the absorbent layer and is not positioned over a radially outer border region of the absorbent layer.

5. The wound dressing of claim 4, wherein the conformable shape comprises four rounded lobes extending from a central portion of the dressing.

6. The wound dressing of claim 4, further comprising a masking layer for at least partially obscuring a view of wound exudate absorbed by the absorbent layer in use, the masking layer positioned between the absorbent layer and the cover layer.

7. The wound dressing of claim 6, wherein the masking layer is formed in the conformable shape including the plurality of sub-areas.

8. The wound dressing of claim 7, wherein the conformable shape of the masking layer has a smaller dimension than the conformable shape of the absorbent layer whereby the masking layer is positioned over a central region of the absorbent layer and is not positioned over a radially outer border region of the absorbent layer.

9. The wound dressing of claim 6 4, wherein the cover layer and the masking layer are permeable to one or both of gas and vapour.

10. The wound dressing of claim 9, wherein the masking layer comprises, or is coated with, a material having size-exclusion properties for selectively permitting or preventing passage of molecules of a predetermined size or weight, the molecules comprising proteins.

11. The wound dressing of claim 6 4, further comprising a shielding layer positioned above the absorbent layer, wherein the shielding layer comprises the masking layer, the shielding layer configured for spreading pressure applied to the wound dressing at a first area over a second area, wherein the second area is larger than the first area.

12. The wound dressing of claim 11, wherein the shielding layer increases the area over which a pressure applied to the dressing is transferred by 25% or more or of the initial area of application.

13. The wound dressing of claim 11, wherein the shielding layer comprises two or more sub-layers, wherein a first sub-layer comprises through holes and a further sub-layer comprises through holes and the through holes of the first sub-layer are offset from the through holes of the further sub-layer.

14. The wound dressing of claim 4, further comprising at least one layer positioned between the absorbent layer and the wound contact layer; wherein a dimension of the absorbent layer is larger than a dimension of the at least one layer such that a radially outer region of the absorbent layer forms an enclosure with the wound contact layer around the at least one layer.

15. The wound dressing of claim 14, wherein the at least one layer comprises a foam layer positioned between the absorbent layer and the wound contact layer.

16. The wound dressing of claim 14, wherein the at least one layer comprises an odour controlling element positioned between the absorbent layer and the wound contact layer.

17. The wound dressing of claim 4, wherein the wound contact layer carries an adhesive portion on a lower surface thereof, the adhesive portion for forming a substantially fluid tight seal over the wound site.

18. The wound dressing of claim 4, wherein the wound contact layer and cover layer are moisture vapor permeable.

19. The wound dressing of claim 18, further comprising a moisture vapor permeable adhesive sealing the cover layer and the wound contact layer around the a border region of the wound dressing.

20. The wound dressing of claim 4, wherein the cover layer comprises a translucent film having a moisture vapour permeability of 500 g/m²/24 hours or more.

21. The wound dressing of claim 4, wherein the wound dressing has a border region and a central region, wherein the cover layer is sealed to the wound contact layer within the border region, and wherein the absorbent layer is positioned within the central region.

22. The wound dressing of claim 1, wherein the plurality of sub-areas comprise four rounded lobes extending from a central portion of the dressing.

23. The wound dressing of claim 22, wherein a shape of the absorbent layer matches a shape of a border around the four rounded lobes.

24. The wound dressing of claim 23, further comprising a border region around the absorbent layer, wherein a width of the border region is approximately equal around the wound dressing.

25. The wound dressing of claim 1, wherein the at least one layer comprises a foam layer positioned between the absorbent layer and the wound contact layer.

26. The wound dressing of claim 1, wherein the at least one layer comprises an odour controlling element positioned between the absorbent layer and the wound contact layer.

27. A wound dressing comprising:

a wound contact layer;

a cover layer sealed to the wound contact layer;

an absorbent layer for absorbing wound exudate positioned between the wound contact layer and the cover layer; and

a masking layer for at least partially obscuring a view of wound exudate absorbed by the absorbent layer in use, the masking layer positioned between the absorbent layer and the cover layer;

wherein the wound contact layer, cover layer, absorbent layer and the masking layer are shaped in a conformable shape including a plurality of sub-areas, wherein the sub areas define areas of the wound dressing that are formable in different directions with respect to each other;

wherein the conformable shape has rotational symmetry around a center point of the conformable shape;

wherein the cover layer and the masking layer are permeable to one or both of gas and vapour;

wherein the masking layer comprises a material having size-exclusion properties for selectively permitting or preventing passage of molecules of a predetermined size or weight, the molecules comprising proteins.

28. The wound dressing of claim 27, wherein the conformable shape comprises four rounded lobes extending from a central portion of the dressing.

29. A wound dressing comprising:

a wound contact layer;

a cover layer sealed to the wound contact layer;

an absorbent layer for absorbing wound exudate positioned between the wound contact layer and the cover layer; and

a shielding layer positioned above the absorbent layer, the shielding layer configured for spreading pressure applied to the wound dressing at a first area over a second area, wherein the second area is larger than the first area;

wherein the wound contact layer, cover layer, and absorbent layer are shaped in a conformable shape including a plurality of sub-areas, wherein the sub areas define areas of the wound dressing that are formable in different directions with respect to each other;

wherein the conformable shape has rotational symmetry around a center point of the conformable shape;

wherein the shielding layer comprises two or more sub-layers, wherein a first sub-layer comprises through holes and a further sub-layer comprises through holes and the through holes of the first sub-layer are offset from the through holes of the further sub-layer.

30. The wound dressing of claim 29, wherein the conformable shape comprises four rounded lobes extending from a central portion of the dressing.