Patent Description:
Embodiments of the present invention relate generally to wound treatment apparatuses including a wound dressing and a fluidic connector for use therewith.

The treatment of open or chronic wounds that are too large to spontaneously close or otherwise fail to heal by means of applying negative pressure to the site of the wound is well known in the art. Negative pressure wound therapy (NPWT) systems currently known in the art commonly involve placing a cover that is impermeable or semi-permeable to fluids over the wound, using various means to seal the cover to the tissue of the patient surrounding the wound, and connecting a source of negative pressure (such as a vacuum pump) to the cover in a manner so that negative pressure is created and maintained under the cover. It is believed that such negative pressures promote wound healing by facilitating the formation of granulation tissue at the wound site and assisting the body's normal inflammatory process while simultaneously removing excess fluid, which may contain adverse cytokines bacteria. However, further improvements in NPWT are needed to fully realize the benefits of treatment.

Many different types of wound dressings are known for aiding in NPWT systems. These different types of wound dressings include many different types of materials and layers, for example, gauze, pads, foam pads or multi-layer wound dressings. One example of a multi-layer wound dressing is the PICO dressing, available from Smith & Nephew, which includes a superabsorbent layer beneath a backing layer to provide a canister-less system for treating a wound with NPWT. The wound dressing may be sealed to a suction port providing connection to a length of tubing, which may be used to pump fluid out of the dressing and/or to transmit negative pressure from a pump to the wound dressing.

To provide a canister-less system for treating a wound with negative pressure, a filter to prevent wound fluid from escaping a wound dressing or a suction port and entering a pump, may be required to be included in the wound dressing or the suction port. At the same time, it would desirable that such filter allows uninterrupted air flow such that the negative pressure from a pump is transmitted to the wound site. However, accumulation of wound fluid under the filter, especially under the negative pressure, may obstruct air flow through filters, and thus compromise the benefit of NPWT. Accordingly, there is a need to provide for an improved apparatus, method, and system for filter for the treatment and closure of wounds. <CIT> discloses a wound dressing, a method of manufacturing a wound dressing, and a method of treating a patient. 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.

Embodiments of the present disclosure relate to wound treatment apparatuses, wound treatment devices and methods of treating a wound. In some embodiments of the wound treatment apparatuses described herein, a three-dimensional filter element is utilized with a wound dressing comprising an absorbent material. Wound treatment apparatuses may also comprise a fluidic connector that may be used in combination with the three-dimensional filter element and the wound dressing described herein. In some embodiments, a three-dimensional filter element is incorporated into a fluidic connector so that the fluidic connector and the three-dimensional filter are part of an integral or integrated fluidic connector structure that delivers negative pressure to the wound dressing and prevents wound exudate from escaping from the wound dressing. These and other embodiments as described herein are directed to overcoming particular challenges involved with preventing wound exudate or wound fluid from escaping a wound dressing under negative pressure.

According to some embodiments there is provided a wound treatment apparatus comprising:.

The wound treatment apparatus of the preceding paragraph or in other embodiments can include one or more of the following features. In some embodiments, the three-dimensional filter element spans the aperture in the cover layer. The recess may be a through-hole which extends through the entire thickness of the absorbent layer. The three-dimensional filter element may be at least partially cylindrically shaped or cuboid-shaped. The three-dimensional filter element may have a height greater than <NUM>. In some embodiments, the three-dimensional filter element further comprises a filter layer. The filter layer may be oleophobic. In some embodiments, the three-dimensional filter element further comprises a spacer core, wherein the spacer core is at least partially enclosed by the filter layer. The spacer core may comprise cellulose. In some embodiments, the three-dimensional filter element is adhered to the fluidic connector. The three-dimensional filter element may extend below the fluidic connector. In some embodiment, the wound dressing further comprises a wound contact layer, a transmission layer, and/or a source of negative pressure.

According to the invention there is provided a wound treatment apparatus according to claim <NUM>.

The wound treatment apparatus of the preceding paragraph or in other embodiments can include one or more of the following features. In some embodiments, the three-dimensional filter element extends along at least a portion of the thickness of the absorbent layer. The absorbent layer may comprise a recess extending vertically through a thickness of the absorbent layer at least partially, and three-dimensional filter element may extend vertically along at least a portion of the thickness of the absorbent layer within the recess. In some embodiments, the three-dimensional filter element may be above the absorbent layer. The three-dimensional filter element may spans the aperture in the cover layer. The three-dimensional filter element may be at least partially cylindrically shaped or cuboid-shaped. The three-dimensional filter element may have a height greater than <NUM>. In some embodiments, the three-dimensional filter element further comprises a filter layer. The filter layer may be oleophobic. In some embodiments, the three-dimensional filter element further comprises a spacer core, wherein the spacer core is at least partially enclosed by the filter layer. The spacer core may comprise cellulose. In some embodiments, the three-dimensional filter element is adhered to the fluidic connector. The three-dimensional filter element may extend below the fluidic connector. In some embodiment, the wound dressing further comprises a wound contact layer, a transmission layer and/or a source of negative pressure.

Other embodiments of an apparatus for use with wound treatment, devices, kits and associated methods are described below.

Other features and advantages of the present invention will be apparent from the following detailed description of the invention, taken in conjunction with the accompanying drawings of which:.

Preferred embodiments disclosed herein relate to wound therapy for a human or animal body. Therefore, any reference to a wound herein can refer to a wound on a human or animal body, and any reference to a body herein can refer to a human or animal body. The term "wound" as used herein, in addition to having its broad ordinary meaning, includes any body part of a patient that may be treated using negative pressure. Wounds include, but are not limited to, open wounds, incisions, lacerations, abrasions, contusions, burns, diabetic ulcers, pressure ulcers, stoma, surgical wounds, trauma and venous ulcers or the like. Treatment of such wounds can be performed using negative pressure wound therapy, wherein a reduced or negative pressure can be applied to the wound to facilitate and promote healing of the wound. It will also be appreciated that the fluidic connector and methods as disclosed herein may be applied to other parts of the body, and are not necessarily limited to treatment of wounds.

Certain embodiments of this application related to a wound treatment apparatus employing a wound dressing and a fluidic connector, and to methods of using the same. Certain embodiments of this application relate to a fluidic connector and methods of using the same.

<FIG> illustrate embodiments of a negative pressure wound treatment system <NUM> employing a wound dressing <NUM> in conjunction with a fluidic connector <NUM>. Here, the fluidic connector <NUM> may comprise an elongate conduit, more preferably a bridge <NUM> having a proximal end <NUM> and a distal end <NUM>, and an applicator <NUM> at the distal end <NUM> of the bridge <NUM>. An optional coupling <NUM> is preferably disposed at the proximal end <NUM> of the bridge <NUM>. A cap <NUM> may be provided with the system (and can in some cases, as illustrated, be attached to the coupling <NUM>). The cap <NUM> can be useful in preventing fluids from leaking out of the proximal end <NUM>. The system <NUM> may include a source of negative pressure such as a pump or negative pressure unit <NUM> capable of supplying negative pressure. The pump may comprise a canister or other container for the storage of wound exudates and other fluids that may be removed from the wound. A canister or container may also be provided separate from the pump. In some embodiments, such as illustrated in <FIG>, the pump <NUM> can be a canisterless pump such as the PICO™ pump, as sold by Smith & Nephew. The pump <NUM> may be connected to the coupling <NUM> via a tube <NUM>, or the pump <NUM> may be connected directly to the coupling <NUM> or directly to the bridge <NUM>. In use, the dressing <NUM> is placed over a suitably-prepared wound, which may in some cases be filled with a wound packing material such as foam or gauze. The applicator <NUM> of the fluidic connector <NUM> has a sealing surface that is placed over an aperture in the dressing <NUM> and is sealed to the top surface of the dressing <NUM>. Either before, during, or after connection of the fluidic connector <NUM> to the dressing <NUM>, the pump <NUM> is connected via the tube <NUM> to the coupling <NUM>, or is connected directly to the coupling <NUM> or to the bridge <NUM>. The pump is then activated, thereby supplying negative pressure to the wound. Application of negative pressure may be applied until a desired level of healing of the wound is achieved.

With reference initially to <FIG>, treatment of a wound with negative pressure in certain embodiments of the application uses a wound dressing <NUM> capable of absorbing and storing wound exudate in conjunction with a flexible fluidic connector <NUM>. In some embodiments, the wound dressing <NUM> may be substantially similar to wound dressings and have the same or similar components as those described throughout International Patent Publication <CIT>, <CIT>, <CIT> and <CIT> Al. In other embodiments (not shown), the wound dressing may simply comprise one or more backing layers configured to form a sealed chamber over the wound site. 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 <NUM>. 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 <NUM> 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 <NUM> is sealed over the wound site, negative pressure may be transmitted from a pump or other source of negative pressure through a flexible tubing via the fluidic connector <NUM> to the wound dressing <NUM>, through the wound packing material, and finally to the wound site. This negative pressure draws wound exudate and other fluids or secretions away from the wound site.

As shown in <FIG>, the fluidic connector <NUM> preferably comprises an enlarged distal end, or head <NUM> that is in fluidic communication with the dressing <NUM> as will be described in further detail below. In one embodiment, the enlarged distal end has a round or circular shape. The head <NUM> is illustrated here as being positioned near an edge of the dressing <NUM>, but may also be positioned at any location on the dressing. For example, some embodiments may provide for a centrally or off-centered location not on or near an edge or corner of the dressing <NUM>. In some embodiments, the dressing <NUM> may comprise two or more fluidic connectors <NUM>, each comprising one or more heads <NUM>, in fluidic communication therewith. In a preferred embodiment, the head <NUM> may measure <NUM> along its widest edge. The head <NUM> forms at least in part the applicator <NUM>, described above, that is configured to seal against a top surface of the wound dressing.

<FIG> illustrates a cross-section through a wound dressing <NUM> similar to the wound dressing <NUM> as shown in <FIG> and described in International Patent Publication <CIT>, along with fluidic connector <NUM>. The wound dressing <NUM>, which can alternatively be any wound dressing embodiment disclosed herein or 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 <NUM> may be placed to as to form a sealed cavity over the wound site. In a preferred embodiment, the dressing <NUM> comprises a top or cover layer, or backing layer <NUM> attached to an optional wound contact layer <NUM>, both of which are described in greater detail below. These two layers <NUM>, <NUM> are preferably joined or sealed together so as to define an interior space or chamber. This interior space or chamber may comprise additional structures that may be adapted to distribute or transmit negative pressure, store wound exudate and other fluids removed from the wound, and other functions which will be explained in greater detail below. Examples of such structures, described below, include a transmission layer <NUM> and an absorbent layer <NUM>.

As illustrated in <FIG>, the wound contact layer <NUM> 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 <NUM> has a lower surface <NUM> and an upper surface <NUM>. The perforations <NUM> preferably comprise through holes in the wound contact layer <NUM> which enable fluid to flow through the layer <NUM>. The wound contact layer <NUM> helps prevent tissue ingrowth into the other material of the wound dressing. Preferably, the perforations are small enough to meet this requirement while still allowing fluid to flow therethrough. For example, perforations formed as slits or holes having a size ranging from <NUM> to <NUM> are considered small enough to help prevent tissue ingrowth into the wound dressing while allowing wound exudate to flow into the dressing. In some configurations, the wound contact layer <NUM> may help maintain the integrity of the entire dressing <NUM> while also creating an air tight seal around the absorbent pad in order to maintain negative pressure at the wound.

Some embodiments of the wound contact layer <NUM> may also act 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 lower surface <NUM> of the wound dressing <NUM> whilst an upper pressure sensitive adhesive layer may be provided on the upper surface <NUM> 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, it may be helpful to adhere the wound dressing <NUM> to the skin around a wound site. In some embodiments, the wound contact layer may comprise perforated polyurethane film. The lower surface of the film may be provided with a silicone pressure sensitive adhesive and the upper surface may be provided with an acrylic pressure sensitive adhesive, which may help the dressing maintain its integrity. In some embodiments, a polyurethane film layer may be provided with an adhesive layer on both its upper surface and lower surface, and all three layers may be perforated together.

A layer <NUM> of porous material can be located above the wound contact layer <NUM>. This porous layer, or transmission layer, <NUM> 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 <NUM> preferably 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 <NUM> should preferably 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 <NUM> may be formed of a material having a three dimensional structure. For example, a knitted or woven spacer fabric (for example Baltex <NUM> weft knitted polyester) or a non-woven fabric could be used.

In some embodiments, the transmission layer <NUM> 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 <NUM>/<NUM> textured polyester, and a bottom layer (that is to say, a layer which lies proximate to the wound bed in use) which is a <NUM> 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 <NUM> 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 <NUM> (that is to say perpendicular to the channel region formed between the top and bottom spacer layers, the 3D fabric may be 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 <NUM>/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 <NUM> of absorbent material is provided above the transmission layer <NUM>. The absorbent material, which comprise a foam or non-woven natural or synthetic material, and which may optionally comprise a super-absorbent material, forms a reservoir for fluid, particularly liquid, removed from the wound site. In some embodiments, the layer <NUM> may also aid in drawing fluids towards the backing layer <NUM>.

The material of the absorbent layer <NUM> may also prevent liquid collected in the wound dressing <NUM> from flowing freely within the dressing, and preferably acts so as to contain any liquid collected within the dressing. The absorbent layer <NUM> 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 <NUM> may typically be manufactured from ALLEVYN™ foam, Freudenberg <NUM>-<NUM>-<NUM> and/or Chem-Posite™11C-<NUM>. In some embodiments, the absorbent layer <NUM> may comprise a composite comprising superabsorbent powder, fibrous material such as cellulose, and bonding fibers. In a preferred embodiment, the composite is an airlaid, thermally-bonded composite.

An aperture, hole, or orifice <NUM> is preferably provided in the backing layer <NUM> to allow a negative pressure to be applied to the dressing <NUM>. The fluidic connector <NUM> is preferably attached or sealed to the top of the backing layer <NUM> over the orifice <NUM> made into the dressing <NUM>, and communicates negative pressure through the orifice <NUM>. A length of tubing may be coupled at a first end to the fluidic connector <NUM> and at a second end to a pump unit (not shown) to allow fluids to be pumped out of the dressing. Where the fluidic connector is adhered to the top layer of the wound dressing, a length of tubing may be coupled at a first end of the fluidic connector such that the tubing, or conduit, extends away from the fluidic connector parallel or substantially to the top surface of the dressing. The fluidic connector <NUM> may be adhered and sealed to the backing layer <NUM> using an adhesive such as an acrylic, cyanoacrylate, epoxy, UV curable or hot melt adhesive. The fluidic connector <NUM> may be formed from a soft polymer, for example a polyethylene, a polyvinyl chloride, a silicone or polyurethane having a hardness of <NUM> to <NUM> on the Shore A scale. In some embodiments, the fluidic connector <NUM> may be made from a soft or conformable material.

Preferably the absorbent layer <NUM> includes at least one through hole <NUM> located so as to underlie the fluidic connector <NUM>. The through hole <NUM> may in some embodiments be the same size as the opening <NUM> in the backing layer, or may be bigger or smaller. As illustrated in <FIG> a single through hole can be used to produce an opening underlying the fluidic connector <NUM>. 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 absorbent layer and the obscuring layer in registration with each respective fluidic connector. Although not essential to certain embodiments of the present disclosure the use of through holes in the super-absorbent layer may provide a fluid flow pathway which remains unblocked in particular when the absorbent layer is near saturation.

The aperture or through-hole <NUM> is preferably provided in the absorbent layer <NUM> beneath the orifice <NUM> such that the orifice is connected directly to the transmission layer <NUM>. This allows the negative pressure applied to the fluidic connector <NUM> to be communicated to the transmission layer <NUM> without passing through the absorbent layer <NUM>. 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 <NUM>, or alternatively a plurality of apertures underlying the orifice <NUM> may be provided. In further alternative embodiments, additional layers such as another transmission layer or an obscuring layer such as described in International Patent Publication <CIT> may be provided over the absorbent layer <NUM> and beneath the backing layer <NUM>.

The backing layer <NUM> is preferably gas impermeable, but moisture vapor permeable, and can extend across the width of the wound dressing <NUM>. The backing layer <NUM>, 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 backing layer <NUM> and a wound site where a negative pressure can be established. The backing layer <NUM> is preferably sealed to the wound contact layer <NUM> in a border region 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 backing layer <NUM> 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 backing layer <NUM> preferably comprises two layers; a polyurethane film and an adhesive pattern spread onto the film. The polyurethane film is preferably moisture vapor permeable and may be manufactured from a material that has an increased water transmission rate when wet. In some embodiments the moisture vapor permeability of the backing layer increases when the backing layer becomes wet. The moisture vapor permeability of the wet backing layer may be up to about ten times more than the moisture vapor permeability of the dry backing layer.

The absorbent layer <NUM> may be of a greater area than the transmission layer <NUM>, such that the absorbent layer overlaps the edges of the transmission layer <NUM>, thereby ensuring that the transmission layer does not contact the backing layer <NUM>. This provides an outer channel of the absorbent layer <NUM> that is in direct contact with the wound contact layer <NUM>, which aids more rapid absorption of exudates to the absorbent layer. Furthermore, this outer channel 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. As illustrated in <FIG>, the absorbent layer <NUM> may define a smaller perimeter than that of the backing layer <NUM>, such that a boundary or border region is defined between the edge of the absorbent layer <NUM> and the edge of the backing layer <NUM>.

As shown in <FIG>, one embodiment of the wound dressing <NUM> comprises an aperture <NUM> in the absorbent layer <NUM> situated underneath the fluidic connector <NUM>. In use, for example when negative pressure is applied to the dressing <NUM>, a wound facing portion of the fluidic connector may thus come into contact with the transmission layer <NUM>, which can thus aid in transmitting negative pressure to the wound site even when the absorbent layer <NUM> is filled with wound fluids. Some embodiments may have the backing layer <NUM> be at least partly adhered to the transmission layer <NUM>. In some embodiments, the aperture <NUM> is at least <NUM>-<NUM> larger than the diameter of the wound facing portion of the fluidic connector <NUM>, or the orifice <NUM>.

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

Turning now to the fluidic connector <NUM>, preferred embodiments comprise a sealing surface <NUM>, a bridge <NUM> (corresponding to bridge <NUM> in <FIG>) with a proximal end <NUM> and a distal end <NUM>, and a filter <NUM>. The sealing surface <NUM> preferably forms the applicator previously described that is sealed to the top surface of the wound dressing. In some embodiments a bottom layer of the fluidic connector <NUM> may comprise the sealing surface <NUM>, such as layer <NUM> in <FIG> below. The fluidic connector <NUM> may further comprise an upper surface vertically spaced from the sealing surface <NUM>, which in some embodiments is defined by a separate upper layer of the fluidic connector such as layer <NUM> in <FIG> below. In other embodiments the upper surface and the lower surface may be formed from the same piece of material. In some embodiments the sealing surface <NUM> may comprise at least one aperture <NUM> therein to communicate with the wound dressing. In some embodiments the filter <NUM> may be positioned across the opening <NUM> in the sealing surface, and may span the entire opening <NUM>. The sealing surface <NUM> may be configured for sealing the fluidic connector to the cover layer of the wound dressing, and may comprise an adhesive or weld. In some embodiments, the sealing surface <NUM> may be placed over an orifice in the cover layer with optional spacer elements <NUM> configured to create a gap between the filter <NUM> and the transmission layer <NUM>. In other embodiments, the sealing surface <NUM> may be positioned over an orifice in the cover layer and an aperture in the absorbent layer <NUM>, permitting the fluidic connector <NUM> to provide air flow through the transmission layer <NUM>. In some embodiments, the bridge <NUM> may comprise a first fluid passage <NUM> in communication with a source of negative pressure, the first fluid passage <NUM> comprising a porous material, such as a 3D knitted material, which may be the same or different than the porous layer <NUM> described previously. The bridge <NUM> is preferably encapsulated by at least one flexible film layer <NUM>, <NUM> having a proximal and distal end and configured to surround the first fluid passage <NUM>, the distal end of the flexible film being connected the sealing surface <NUM>. The filter <NUM> is configured to substantially prevent wound exudate from entering the bridge, and spacer elements <NUM> are configured to prevent the fluidic connector from contacting the transmission layer <NUM>. These elements will be described in greater detail below.

Preferably, the fluid passage <NUM> is constructed from a compliant material that is flexible and that also permits fluid to pass through it if the spacer is kinked or folded over. Suitable materials for the fluid passage <NUM> include without limitation foams, including open-cell foams such as polyethylene or polyurethane foam, meshes, 3D knitted fabrics, non-woven materials, and fluid channels. In some embodiments, the fluid passage <NUM> may be constructed from materials similar to those described above in relation to the transmission layer <NUM>. Advantageously, such materials used in the fluid passage <NUM> not only permit greater patient comfort, but may also provide greater kink resistance, such that the fluid passage <NUM> is still able to transfer fluid from the wound toward the source of negative pressure while being kinked or bent.

In some embodiments, the fluid passage <NUM> may be comprised of a wicking fabric, for example a knitted or woven spacer fabric (such as a knitted polyester 3D fabric, Baltex <NUM>®, or Gehring <NUM>®) or a nonwoven fabric. These materials selected are preferably suited to channeling wound exudate away from the wound and for transmitting negative pressure and/or vented air to the wound site, and may also confer a degree of kinking or occlusion resistance to the fluid passage <NUM>. In some embodiments, the wicking fabric may have a three-dimensional structure, which in some cases may aid in wicking fluid or transmitting negative pressure. In certain embodiments, including wicking fabrics, these materials remain open and capable of communicating negative pressure to a wound area under the typical pressures used in negative pressure therapy, for example between <NUM> to <NUM> mmHg. In some embodiments, the wicking fabric may comprise several layers of material stacked or layered over each other, which may in some cases be useful in preventing the fluid passage <NUM> from collapsing under the application of negative pressure. In other embodiments, the wicking fabric used in the fluid passage <NUM> may be between <NUM> and <NUM>; more preferably, the wicking fabric may be between <NUM> and <NUM> thick, and may be comprised of either one or several individual layers of wicking fabric. In other embodiments, the fluid passage <NUM> may be between <NUM>-<NUM> thick, and preferably thicker than <NUM>. Some embodiments, for example a suction adapter used with a dressing which retains liquid such as wound exudate, may employ hydrophobic layers in the fluid passage <NUM>, and only gases may travel through the fluid passage <NUM>. Additionally, and as described previously, the materials used in the system are preferably conformable and soft, which may help to avoid pressure ulcers and other complications which may result from a wound treatment system being pressed against the skin of a patient.

Preferably, the filter element <NUM> is impermeable to liquids, but permeable to gases, and is provided to act as a liquid barrier and to ensure that no liquids are able to escape from the wound dressing <NUM>. The filter element <NUM> may also function as a bacterial barrier. Typically the pore size is <NUM>. Suitable materials for the filter material of the filter element <NUM> include <NUM> 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 <NUM> micron MMT-<NUM> prior to <NUM> micron MMT-<NUM>. 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 over the orifice. For example, the filter element <NUM> may be molded into the fluidic connector <NUM>, or may be adhered to one or both of the top of the cover layer and bottom of the suction adapter <NUM> 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 <NUM>. 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 <NUM> to more than <NUM> micrometers. Microporous membranes are available in both hydrophilic (water filtering) and hydrophobic (water repellent) forms. In some embodiments of the invention, filter element <NUM> comprises a support layer and an acrylic co-polymer membrane formed on the support layer. Preferably the wound dressing <NUM> according to certain embodiments of the present invention uses microporous hydrophobic membranes (MHMs). Numerous polymers may be employed to form MHMs. For example, the MHMs may be formed from one or more of 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 <NUM> 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 <NUM> or may be sandwiched between microporous hydrophobic membranes within the filter element. The filter element <NUM> thus enables gas to be exhausted through the orifice. Liquid, particulates and pathogens however are contained in the dressing.

The wound dressing <NUM> may comprise spacer elements <NUM> in conjunction with the fluidic connector <NUM> and the filter <NUM>. With the addition of such spacer elements <NUM> the fluidic connector <NUM> and filter <NUM> may be supported out of direct contact with the absorbent layer <NUM> and/or the transmission layer <NUM>. The absorbent layer <NUM> may also act as an additional spacer element to keep the filter <NUM> from contacting the transmission layer <NUM>. Accordingly, with such a configuration contact of the filter <NUM> with the transmission layer <NUM> and wound fluids during use may thus be minimized.

<FIG> illustrate various embodiments of the head <NUM> of the fluidic connector <NUM>. Preferably, the fluidic connector <NUM> illustrated in <FIG> is enlarged at the distal end to be placed over an orifice in the cover layer and the aperture in the absorbent layer of a wound dressing, for example wound dressing <NUM> of <FIG>, and may form a "teardrop" or other enlarged shape. <FIG> illustrates a fluidic connector <NUM> with a substantially triangular head <NUM>. <FIG> illustrates a fluidic connector <NUM> with a substantially pentagonal head <NUM>. <FIG> illustrates a fluidic connector <NUM> with a substantially circular head <NUM>.

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

After the skin surrounding the wound site <NUM> is dry, and with reference now to <FIG>, the wound dressing <NUM> may be positioned and placed over the wound site <NUM>. Preferably, the wound dressing <NUM> is placed with the wound contact layer over and/or in contact with the wound site <NUM>. In some embodiments, an adhesive layer is provided on the lower surface of the wound contact layer, which may in some cases be protected by an optional release layer to be removed prior to placement of the wound dressing <NUM> over the wound site <NUM>. Preferably, the dressing <NUM> is positioned such that the fluidic connector <NUM> is in a raised position with respect to the remainder of the dressing <NUM> so as to avoid fluid pooling around the port. In some embodiments, the dressing <NUM> is positioned so that the fluidic connector <NUM> 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 <NUM> are preferably smoothed over to avoid creases or folds.

With reference now to <FIG>, the dressing <NUM> is connected to the pump <NUM>. The pump <NUM> is configured to apply negative pressure to the wound site via the dressing <NUM>, and typically through a conduit. In some embodiments, and as described herein, a fluidic connector <NUM> may be used to join the conduit <NUM> from the pump to the dressing <NUM>. Where the fluidic connector is adhered to the top layer of the wound dressing, a length of tubing may be coupled at a first end of the fluidic connector such that the tubing, or conduit, extends away from the fluidic connector parallel to the top of the dressing. In some embodiments the conduit may comprise a fluidic connector. It is expressly contemplated that a conduit may be a soft bridge, a hard tube, or any other apparatus which may serve to transport fluid. Upon the application of negative pressure with the pump <NUM>, the dressing <NUM> 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 <NUM>. In some embodiments, the pump <NUM> may be configured to detect if any leaks are present in the dressing <NUM>, such as at the interface between the dressing <NUM> and the skin surrounding the wound site <NUM>. Should a leak be found, such leak is preferably remedied prior to continuing treatment.

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

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

Further details of dressings and other apparatuses that may be used with the, fluidic connectors described herein include, but are not limited to, dressings described in International Patent Publication <CIT> and <CIT>.

<FIG> illustrate an embodiment of a flexible port or fluidic connector <NUM>. <FIG> illustrates a perspective exploded view the fluidic connector <NUM> that may be used to connect a wound dressing to a source of negative pressure. The fluidic connector <NUM> comprises a top layer <NUM>, a spacer layer <NUM>, a filter element <NUM>, a bottom layer <NUM>, and a conduit <NUM>. The conduit optionally comprises a coupling <NUM>. In some embodiments the conduit may comprise a fluidic connector. It is expressly contemplated that a conduit may be a soft bridge, a hard tube, or any other apparatus which may serve to transport fluid. The distal end of the fluidic connector <NUM> (the end connectable to a dressing) is depicted as having an enlarged circular shape, although it will be appreciated that any suitable shape may be used and that the distal end need not be enlarged. For example, the distal end can have any of the shapes shown in <FIG> above.

The bottom layer <NUM> may comprise an elongate bridge portion <NUM>, an enlarged (e.g., rounded or circular) sealing portion <NUM>, and an orifice <NUM>. In some embodiments a plurality of orifices may be provided in the bottom layer. Some embodiments of the rounded sealing portion <NUM> may comprise a layer of adhesive, for example a pressure sensitive adhesive, on the lower surface for use in sealing the fluidic connector <NUM> to a dressing. For example, the fluidic connector may be sealed to a cover layer of the dressing. The orifice <NUM> in the bottom layer <NUM> of the port <NUM> may be aligned with an orifice in the cover layer of the dressing in order to transmit negative pressure through the dressing and into a wound site.

The top layer <NUM> may be substantially the same shape as the bottom layer in that it comprises an elongate bridge <NUM> and an enlarged (e.g., rounded or circular) portion <NUM>. The top layer <NUM> and the bottom layer <NUM> may be sealed together, for example by heat welding. In some embodiments, the bottom layer <NUM> may be substantially flat and the top layer <NUM> may be slightly larger than the bottom layer <NUM> in order to accommodate the height of the spacer layer <NUM> and seal to the bottom layer <NUM>. In other embodiments, the top layer <NUM> and bottom layer <NUM> may be substantially the same size, and the layers may be sealed together approximately at the middle of the height of the spacer layer <NUM>. In some embodiments, the elongate bridge portions <NUM>, <NUM> may have a length of <NUM> (or about <NUM>) or more, more preferably a length of <NUM> (or about <NUM>) or more and in some embodiments, may be about <NUM> (or <NUM>) long. Some embodiments of the entire fluidic connector, from a proximal-most edge of the top and bottom layers to a distal-most edge of the top and bottom layers, may be between <NUM> and <NUM> (or about <NUM> to about <NUM>) long, more preferably about <NUM> and <NUM> (or between about <NUM> and about <NUM>) long, for example about <NUM> long. In some embodiments, the elongate bridge portions may have a width of between <NUM> and <NUM> (or between about <NUM> and about <NUM>), and in one embodiment, is about <NUM> wide. The ratio of the length of the elongate bridge portions <NUM>, <NUM> to their widths may in some embodiments exceed <NUM>:<NUM>, and may more preferably exceed <NUM>:<NUM> or even <NUM>:<NUM>. The diameter of the circular portion <NUM>, <NUM> may be about <NUM> in some embodiments.

The bottom and top layers may comprise at least one layer of a flexible film, and in some embodiments may be transparent. Some embodiments of the bottom layer <NUM> and top layer <NUM> may be polyurethane, and may be liquid impermeable.

The fluidic connector <NUM> may comprise a spacer layer <NUM>, such as the 3D fabric discussed above, positioned between the lower layer <NUM> and the top layer <NUM>. The spacer layer <NUM> may be made of any suitable material, for example material resistant to collapsing in at least one direction, thereby enabling effective transmission of negative pressure therethrough. Instead of or in addition to the 3D fabric discussed above, some embodiments of the spacer layer <NUM> may comprise a fabric configured for lateral wicking of fluid, which may comprise viscose, polyester, polypropylene, cellulose, or a combination of some or all of these, and the material may be needle-punched. Some embodiments of the spacer layer <NUM> may comprise polyethylene in the range of <NUM>-<NUM> grams per square meter (gsm) (or about <NUM> to about <NUM> gsm), for example <NUM> (or about <NUM>) gsm. Such materials may be constructed so as to resist compression under the levels of negative pressure commonly applied during negative pressure therapy.

The spacer layer <NUM> may comprise an elongate bridge portion <NUM>, an enlarged (e.g., rounded or circular) portion <NUM>, and may optionally include a fold <NUM>. In some embodiments, the elongate bridge portion may have dimensions in the same ranges as the bridge portions of the upper and lower layers described above though slightly smaller, and in one embodiment is about <NUM> long and <NUM> wide. Similarly, the diameter of the circular portion <NUM> may be slightly smaller than the diameters of the enlarged ends <NUM>, <NUM>, and in one embodiment is about <NUM>. Some embodiments of the spacer layer <NUM> may have adhesive on one or both of its proximal and distal ends (e.g., one or more dabs of adhesive) in order to secure the spacer layer <NUM> to the top layer <NUM> and/or the bottom layer <NUM>. Adhesive may also be provided along a portion or the entire length of the spacer layer. In other embodiments, the spacer layer <NUM> may be freely movable within the sealed chamber of the top and bottom layers.

The fold <NUM> of the spacer layer may make the end of the fluidic connector <NUM> softer and therefore more comfortable for a patient, and may also help prevent the conduit <NUM> from blockage. The fold <NUM> may further protect the end of the conduit <NUM> from being occluded by the top or bottom layers. The fold <NUM> may, in some embodiments, be between <NUM> and <NUM> (or between about <NUM> and about <NUM>) long, and in one embodiment is <NUM> (or about <NUM>) long. The spacer layer may be folded underneath itself that is toward the bottom layer <NUM>, and in other embodiments may be folded upward toward the top layer <NUM>. Other embodiments of the spacer layer <NUM> may contain no fold. A slot or channel <NUM> may extend perpendicularly away from the proximal end of the fold <NUM>, and the conduit <NUM> may rest in the slot or channel <NUM>. In some embodiments the slot <NUM> may extend through one layer of the fold, and in others it may extend through both layers of the fold. The slot <NUM> may, in some embodiments, be <NUM> (or about <NUM>) long. Some embodiments may instead employ a circular or elliptical hole in the fold <NUM>. The hole may face proximally so that the conduit <NUM> may be inserted into the hole and rest between the folded layers of spacer fabric. In some embodiments, the conduit <NUM> may be adhered to the material of the fold <NUM>, while in other embodiments it may not.

The fluidic connector <NUM> may have a filter element <NUM> located adjacent the orifice <NUM>, and as illustrated is located between the lower layer <NUM> and the spacer layer <NUM>. The filter element <NUM> may be positioned across the opening or orifice of the fluidic connector <NUM>. The filter element <NUM> is impermeable to liquids, but permeable to gases. The filter element may be similar to the element described above with respect to <FIG>, and as illustrated may have a round or disc shape. The filter element <NUM> can act as a liquid barrier, to substantially prevent or inhibit liquids from escaping from the wound dressing, as well as an odor barrier. The filter element <NUM> may also function as a bacterial barrier. In some embodiments, the pore size of the filter element <NUM> can be approximately <NUM>. Suitable materials for the filter material of the filter element include <NUM> micron Gore™ expanded PTFE from the MMT range, PALL Versapore™ 200R, and Donaldson™ TX6628. The filter element <NUM> thus enables gas to be exhausted through the orifice. Liquid, particulates and pathogens however are contained in the dressing. 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 <NUM> micron MMT-<NUM> prior to <NUM> micron MMT-<NUM>. This prevents the lipids from blocking the hydrophobic filter. In some embodiments, the filter element <NUM> may be adhered to one or both of top surface of the bottom layer <NUM> and the bottom surface of the spacer layer <NUM> using an adhesive such as, but not limited to, a UV cured adhesive. In other embodiments, the filter <NUM> may be welded to the inside of the spacer layer <NUM> and to the top surface of the bottom layer <NUM>. The filter may also be provided adjacent the orifice on a lower surface of the bottom layer <NUM>. Other possible details regarding the filter are disclosed in <CIT>.

The proximal end of the fluidic connector <NUM> may be connected to the distal end of a conduit <NUM>. The conduit <NUM> may comprise one or more circular ribs <NUM>. The ribs <NUM> may be formed in the conduit <NUM> by grooves in a mold during the manufacturing of the conduit. During heat welding of the upper and lower layers <NUM>, <NUM> melted material from those layers may flow around the ribs <NUM>, advantageously providing a stronger connection between the conduit <NUM> and the layers. As a result, it may be more difficult to dislodge the conduit <NUM> out from between the layers during use of the fluidic connector <NUM>.

The proximal end of the conduit <NUM> may be optionally attached to a coupling <NUM>. The coupling <NUM> may be used to connect the fluidic connector <NUM> to a source of negative pressure, or in some embodiments to an extension conduit which may in turn be connected to a source of negative pressure. As explained in more detail below with respect to Figures 8A and 8B, the proximal end of the conduit <NUM>, which is inserted into the spacer fabric <NUM>, may be shaped in such a way to reduce the possibility of occlusion. For example, some embodiments may have a triangular portion cut out of the end of the conduit, and other embodiments may have a plurality of holes therethrough.

<FIG> illustrates an embodiment of a wound dressing <NUM> with a fluidic connector <NUM> such as described above with respect to <FIG> attached to the dressing. The fluidic connector <NUM> may be the fluidic connector described above in <FIG>. The fluidic connector <NUM> may comprise a conduit <NUM> and a coupling <NUM> for connecting the fluidic connector to a source of negative pressure or to an extension conduit. Although in this depiction the fluidic connector <NUM> is connected over a circular window in the obscuring layer of the dressing <NUM>, in other embodiments the fluidic connector <NUM> may be connected over a maltese cross in the obscuring layer. In some embodiments, the maltese cross may be of a larger diameter than the fluidic connector <NUM> and may be at least partially viewable after the fluidic connector <NUM> is attached to the dressing <NUM>. Further details regarding the dressing <NUM> and other dressings to which the fluidic connector can be connected are described in International Patent Publications <CIT> and <CIT>. Further details regarding wound dressings and fluidic connectors can be found in <CIT>, published as <CIT>.

A negative pressure wound therapy system according to the invention includes a three- dimensional filter element to prevent or inhibit wound fluid or exudate from escaping from a wound dressing. In some embodiments, the three-dimensional filter element may be placed within the wound dressing and/or the fluidic connector, and replace the filter element such as the filter element <NUM> described in relation to <FIG>, or the filter element <NUM> described in relation to <FIG>. In some embodiments, a negative pressure wound therapy system may contain both the three-dimensional filter element and the filter element such as the filter element <NUM> described in relation to <FIG> or the filter element <NUM> described in relation to <FIG>.

The three-dimensional filter element may have a substantial thickness or height perpendicular to a width, a length, and/or a diameter, and thus define three-dimensional shape, as compared with the filter elements <NUM> or <NUM>, which are relatively flatter and have minimal thickness or height. Thus, the three-dimensional filter may have more surface area than a two-dimensional filter having a same cross-sectional area. For example, a cylindrical three-dimensional filter element having a cross-sectional radius of r and a height of h may have a surface area of 2πrh (side wall) + πr<NUM> (bottom surface), while a circular two-dimensional filter having a radius r will only have a surface area of πr<NUM>. The increased surface area of the three-dimensional filter may allow improved filtering capacity and better air flow even when the filter is partially blocked. Such advantage of three-dimensional filters is further depicted in <FIG>, wherein a NPWT system <NUM> having a two-dimensional filter <NUM>, and another NPWT system <NUM> having a three dimensional filter <NUM> are schematically shown. In <FIG>, the NPWT systems <NUM> and <NUM> without negative pressure applied are shown on the left, while the NPWT systems <NUM> and <NUM> under negative pressure are shown on the right. As shown in <FIG>, the three-dimensional filter element <NUM> may be configured to maintain its height under negative pressure, thereby maintain its increased surface area.

<FIG> illustrates a cross-sectional view through an embodiment of a negative pressure wound therapy apparatus having a wound dressing <NUM> along with a fluidic connector <NUM>. Each of the wound dressing <NUM> and the fluidic connector <NUM> may be constructed similar to the wound dressing <NUM> and the fluidic connecter <NUM> shown in and described in relation to <FIG> or elsewhere in the specification, respectively, except as noted below. Thus, the references numerals used to designate the various components of the wound dressing <NUM> and the fluidic connector <NUM> are identical to those used for identifying the corresponding components of the wound dressing <NUM> and the fluidic connector <NUM>.

In some embodiments, such as shown in <FIG>, the fluidic connector <NUM> may include a three-dimensional filter element <NUM>. The three-dimensional filter element <NUM> may be positioned across the opening <NUM> in the sealing surface <NUM> of the fluidic connector <NUM>, and may span the entire opening <NUM> and/or the aperture <NUM> of the cover layer <NUM>. In some embodiments, the three-dimensional filter element <NUM> may located within the fluidic connector. In some embodiments, the filter element <NUM> may extrude out or extend out of the fluidic connector <NUM>. The extruded-out portion of the filter element <NUM> may pass and extend through the aperture <NUM> of the cover layer <NUM> and/or the aperture or through-hole <NUM> of the absorbent layer <NUM> of the dressing <NUM>. In some embodiments, the aperture or through-hole <NUM> may be a recess which only partially extends through the thickness of the absorbent layer <NUM>. The aperture, through-hole, and the recess <NUM> of the absorbent layer <NUM> are interchangeable variations of cut-outs in the absorbent layer <NUM>, and these terms may be used interchangeably hereinafter. In some embodiments, the sealing surface <NUM> may be placed over the orifice <NUM> in the cover layer with optional spacer elements <NUM> configured to offset the height or thickness of the three-dimensional filter element <NUM>, such that only predetermined portion of the three-dimensional filter <NUM> extends out of the sealing surface of the fluidic connector through the opening <NUM> and maintains a gap between the filter element <NUM> and the transmission layer <NUM>. In some embodiments, the filter element <NUM> may be entirely within the fluidic connector <NUM> and does not extend to the wound dressing <NUM>.

Alternatively, a three-dimensional filter may be placed at/on the wound dressing <NUM>. For example, in some embodiments, the three-dimensional filter may be placed within the aperture <NUM> of the cover layer <NUM> and the aperture <NUM> of the absorbent layer <NUM>. In some embodiments, the three-dimensional filter may be thinner than the depth of the aperture <NUM>, such that the three-dimensional filter is fully embedded in the aperture <NUM>. In some embodiments, the three-dimensional filter may be thicker than the depth of the aperture <NUM>, such that the three-dimensional filter element extrudes out from the absorbent layer/wound dressing through the aperture <NUM>. However, the three-dimensional filter element may be placed at any location relative to the absorbent layer <NUM>. In some embodiments, the three-dimensional filter may be placed above the absorbent layer <NUM>, or next to the side wall of the absorbent layer <NUM>.

The three-dimensional filter element may be fixed to the fluidic connector or the wound dressing element by any suitable means, such as glue or an adhesive, as explained below in further detail. In some embodiments, the three-dimensional filter element may be molded with the fluidic connector or the wound dressing as an integrated part.

The filter element <NUM> may be constructed to conform to the shape and the size of the opening <NUM> and/or the aperture in the wound dressing <NUM>. In some embodiments, the filter <NUM> may have the exact same shape and size with the aperture <NUM> and/or the opening <NUM>, such that wound exudate does not leak along the gap between the perimeter of the three-dimensional filter element <NUM> and the aperture <NUM> or the opening <NUM>. In some embodiments, the three-dimensional filter element has length or width greater than <NUM>, <NUM>, <NUM>, <NUM>, <NUM> or <NUM>. Also, the three-dimensional filer <NUM> may be constructed to have a height or thickness such that the gap between the three-dimensional filter and the bottom of the recess <NUM> or the transmission layer <NUM> may be maintained under negative pressure. For example, the height of the three-dimensional filter <NUM> may not be greater than the thickness of the absorbent layer <NUM> under negative pressure, such that the three-dimensional filter <NUM> does not reach the transmission layer <NUM> through the aperture <NUM> even when the absorbent layer <NUM> collapses under negative pressure. However, at the same time, the three- dimensional filter element may have a certain amount of thickness or height to have an advantage of having a three-dimensional structure described in this section or elsewhere in the specification. The three-dimensional filter <NUM> has a thickness greater than <NUM>. In some embodiments, the three-dimensional filter <NUM> may have a thickness greater than, for example, <NUM>, <NUM>, <NUM>, <NUM> or <NUM>. In some embodiments, the three-dimensional filter <NUM> may have a thickness or height greater than its length or width. In some embodiments, the three-dimensional filter <NUM> may have a thickness or height smaller than its length or width.

The three-dimensional filter may have any suitable shape. For example, in some embodiments, the filter element <NUM> may be cylindrical or cuboid. In some embodiments, the cross-section along the horizontal plane of the filter element <NUM> may have a circular, elliptical, square, rectangular, diamond, or any other suitable cross-sectional shape.

The three-dimensional filter element may include one or more filter layers constructed from filter materials forming the three-dimensional shape. In some embodiments, the three-dimensional filter element also includes an optional spacer to maintain the three-dimensional shape of the filter element. <FIG> illustrates a vertical cross-sectional view of an embodiment of a three-dimensional filter element <NUM> similar to the three-dimensional filter element <NUM> described in relation to <FIG> or any three-dimensional filter elements described in this section or elsewhere in the specification. The three-dimensional filter element <NUM> may include a filter layer <NUM> and a spacer material core <NUM>. In some embodiments, the filter layer <NUM> may at least partially enclose a spacer material core <NUM>, such that the filter layer is placed on the outside of the three-dimensional filter element to maximize filtering area, while the spacer material core inside allows air flow and supports the overall structure of the three-dimensional filter element. Having the spacer material core may also contribute to the ease of constructing the three-dimensional filter element, as it may be easier to apply the filter layer over the three-dimensional-structured spacer material core than building a three-dimensional structure solely with the filter material.

The filter layer <NUM> is impermeable to liquids, but permeable to gases, and may be constructed from any materials suitable for the filter element <NUM> described in relation to <FIG> or the filter element <NUM> described in relation to <FIG>. For example, the filter layer <NUM> may be constructed from <NUM> micron Gore™ expanded PTFE from the MMT range, PALL Versapore™ 200R, PALL Versapore™ 1200R 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 <NUM> micron MMT-<NUM> prior to <NUM> micron MMT-<NUM>. This prevents the lipids from blocking the hydrophobic filter. In some embodiments, the filter material <NUM> may be hydrophobic. A portion of the filter layer can be attached or sealed to the fluidic connector and/or the wound dressing. For example, the filter layer <NUM> may be molded into the fluidic connector, or may be adhered to one or both of the wound dressing and the suction adapter using an adhesive such as, but not limited to, a UV cured adhesive, as described further below in relation to <FIG>. The filter layer <NUM> of the three-dimensional filter element <NUM> may be constructed not to collapse substantially under negative pressure, such that it maintains the unobstructed air flow under the negative pressure.

The spacer material core <NUM> may be constructed from any soft spacer material that allows an air flow throughout. For example, in some embodiments, the spacer material core <NUM> may be constructed from materials suitable for the absorbent layer <NUM> described in relation to <FIG>, such as ALLEVYN™ foam, Freudenberg <NUM>-<NUM>-<NUM> and/or Chem-Posite™11C-<NUM>, Baltex <NUM>®, or fibrous material such as cellulose. The filter material <NUM> may be adhered to the spacer material core <NUM> using an adhesive such as, but not limited to, a UV cured adhesive. The spacer material core <NUM> may also be constructed from any soft spacer material that allows an air flow throughout. For example, in some embodiments, the spacer material core <NUM> may be constructed from materials suitable for the spacer layer <NUM>, the spacer element <NUM>, or any other spacers described elsewhere in the specification, such as a knitted polyester 3D fabric, Gehring <NUM>®, a fabric comprising comprise viscose, polyester, polypropylene, cellulose, or a combination of some or all of these.

A negative pressure wound therapy system including the three-dimensional filter element may be constructed in various ways. <FIG> illustrates different embodiments of a wound dressing and a fluidic connector having a three-dimensional filter element.

<FIG> illustrates a schematic view of an embodiment of the NPWT system <NUM> where the three-dimensional filter element <NUM> is attached to the fluidic connector <NUM>. In some embodiments, the filter element <NUM> may have a filter layer <NUM> with a flap portion <NUM>, and the flap portion <NUM> may adhere to the fluidic connector <NUM>, for example, using an adhesive <NUM>.

<FIG> illustrates a plan view of an embodiment of the fluidic connector <NUM>. The fluidic connector <NUM> may be constructed similar to the fluidic connector <NUM> shown in and described in relation to <FIG> or elsewhere in the specification, except that the fluidic connector <NUM> includes the three-dimensional filter element <NUM>, instead of the filter element <NUM>. Thus, the references numerals used to designate the various components of the fluidic connector <NUM> are identical to those used for identifying the corresponding components of the fluidic connector <NUM>.

As shown in <FIG>, in some embodiments, the filter element <NUM> may adhere to the fluidic connector <NUM> in a similar fashion to the filter element <NUM> adhering to the fluidic connector <NUM> as described in relation to <FIG>. For example, the filter element <NUM> may be located adjacent the orifice of the fluidic connector orifice <NUM>, and the flap portion <NUM> may be located between the lower layer <NUM> and the spacer layer <NUM>. The filter element <NUM> may be positioned across the opening or orifice <NUM> of the fluidic connector <NUM>. In some embodiments, the flap portion <NUM> of the filter element <NUM> may be adhered to one or both of the top surface of the bottom layer <NUM> and the bottom surface of the spacer layer <NUM> using an adhesive such as, but not limited to, a UV cured adhesive. In other embodiments, the flap portion <NUM> or the entire filter element <NUM> may be welded to the inside of the spacer layer <NUM> and to the top surface of the bottom layer <NUM>. The filter element <NUM> may also be provided adjacent the orifice on a lower surface of the bottom layer <NUM>.

In some embodiments, the filter element <NUM> may not include the flap portion <NUM>, and the mechanism to attach the filter element <NUM> to the fluidic connector <NUM> may not be limited to the above embodiment. For example, the filter element may be adhered or welded to any portion of the fluidic connector <NUM> using any suitable methods, so as to prevent wound fluid and exudate from the wound dressing leaks into the fluidic connector under negative pressure.

In some embodiments, the filter element <NUM> may further include a spacer material core within the space defined by the filter layer <NUM> as described above in relation to <FIG>. To construct such three-dimensional filters, in some embodiments, a filter material for the filter layer <NUM> may be cut into a thin strip and looped into a tube. Then, a spacer material may be cut into a disc using, for example, a clicker press, to form the spacer material core. Then, the tube of the filter material may be placed around the disc of the spacer material core and held in place with, for example, an adhesive, to provide an intermediate assembly. Then, a disc of the filter material may be prepared, and the disc of the filter material may be attached to the bottom of the intermediate assembly with, for example, an adhesive, to provide a three-dimensional filter element <NUM>. Then the filter element may be inserted into aperture of the lower layer of the fluidic connector <NUM> and fixed onto the lower layer of the fluidic connector <NUM>.

In some embodiments, a three-dimensional filter element may be placed within a wound dressing such as the wound dressing <NUM> described in relation with <FIG>. In such embodiments, each an absorbent layer and a top film may be cut to create a hole. Then a spacer layer may be placed on a wound contact layer sheet, followed by placement of the absorbent layer. The three-dimensional filter element may be put in place with the absorbent layer hole, and then the dressing may be covered by the top film sheet, in alignment with the hole of the absorbent layer. Holes of the absorbent layer and the top film sheet may be aligned for the fluidic connector attachment.

The three-dimensional filter element may be placed into the wound dressing in various methods. In some embodiments, such as shown in <FIG>, a filter material may be cut into a thin strip and looped into a tube, then slits may be cut into the top and bottom of the tube to form foldable flaps <NUM>. Then the tube may be inserted into the aperture <NUM> of absorbent layer <NUM> of the wound dressing, and the flaps may be folded and attached onto top and bottom side of the absorbent layer <NUM>, for example with an adhesive <NUM>. Then two pieces of the filter material <NUM>, for example in a square-shaped filter material, may cover each side of the tube. This assembly of the filter material and the absorbent layer can be then placed on top of a spacer layer and under a cover layer to form a wound dressing, and the fluidic connector <NUM> may be applied over the wound dressing.

In some embodiments, such as shown in <FIG>, a three-dimensional filter element may be constructed from multiple layers of the filter material. The filter material may be cut into discs <NUM>, which will be stacked and placed within the aperture <NUM> of the absorbent layer <NUM>. The filter material discs <NUM> may not be fixed or attached, as they can be contained within the area after a fluidic connector <NUM> is attached to the wound dressing <NUM> and cover the aperture <NUM>.

While <FIG> and associated descriptions have described locations of the three-dimensional filter within the NPWT system and how the three-dimensional filter can be attached to the wound dressing or the fluidic connector, these embodiments have been presented by way of example only, and locations of the three-dimensional filter within the NPWT system and method to provide and install the three-dimensional filter element are not limited by embodiments of <FIG> or any other embodiments described elsewhere in the specification. The three-dimensional filter element may be placed in any suitable location by any suitable methods so as to prevent the wound exudate from flowing out of the wound dressing. For example, the three-dimensional filter may be placed above the wound dressing or next to the wound dressing.

Claim 1:
A wound treatment apparatus comprising:
a wound dressing (<NUM>) comprising:
a cover layer (<NUM>) comprising an aperture; and
an absorbent layer positioned beneath the cover layer, the absorbent layer having a thickness;
a fluidic connector (<NUM>) configured to provide negative pressure to the wound dressing through the aperture in the cover layer; and
a three-dimensional filter element (<NUM>) configured to prevent wound exudate from exiting the wound dressing through the aperture of the cover layer when negative pressure is provided to the wound dressing wherein the filter element is impermeable to liquids, but permeable to gases,
wherein the three-dimensional filter element has a thickness greater than <NUM>.