US20100036334A1 - Wound Dressing of Continuous Fibers - Google Patents

Abstract

A method for treating a wound that includes incorporating a wound dressing comprising a plurality of fibers, each fiber having a length of at least two (2) inches, into a wound to cause the walls of the wound to remain apart and allow the wound to heal from the inside to the outside, and removing the wound exudate.

Description

CROSS REFERENCE TO RELATED APPLICATIONS
• This application claims priority to, and the benefit of, U.S. Provisional Application Ser. No. 61/188,370 filed on Aug. 8, 2008 by Heagle, 61/096,105 filed on Sep. 11, 2008 by Corley, and 61/147,179 filed on Jan. 26, 2009 by Watson. The entire contents of each of these are hereby being incorporated by reference herein.
BACKGROUND
• 1. Technical Field
• The present disclosure relates generally to wound dressings, and in particular to a wound dressing including an assembly or tow of continuous long fibers for receiving and retaining wound fluids in the treatment of acute and chronic wounds.
• 2. Background of Related Art
• Wound dressings are generally placed over a wound to protect and promote healing of the wound. In the case of exuding wounds, such as pressure sores, ulcers and burns, it is customary to provide a dressing having a packing or filler material for receiving, retaining or conveying the wound exudate as it is produced. Exudates may be conveyed from the wound bed, at least in part, due to wicking characteristics of the wound filler. Thus, the wound filler promotes healing by removing potentially harmful bacteria from the wound bed, and also prevents damage to the surrounding skin that can be caused by an excessively moist environment.
• The dressing filler may capture the excess exudates for subsequent removal, e.g., when the dressing is replaced with a new dressing. Some materials, such as cotton, tend to shed fibers or fibrils (e.g., very short or irregular fibers jutting out from the main fiber structure) into the wound. These fibers may tend to remain in the wound when the dressing is changed. Removing these stray fibers can be a labor intensive procedure that may further damage the wound, and neglecting to remove these stray fibers may cause irritation and otherwise inhibit natural healing of the wound.
• One technique that may utilize a dressing with an absorbent filler is known as negative wound pressure therapy (NWPT). The absorbent material may be positioned in a reservoir over the wound where a negative pressure may be maintained. The reservoir subjects the wound to a sub-atmospheric pressure to effectively draw wound fluid, including liquid exudates, from the wound without the continuous use of a vacuum pump. Hence, vacuum pressure may be applied once, or in varying intervals depending on the nature and severity of the wound. This technique has been found to promote blood flow to the area, stimulate the formation of granulation tissue and encourage the migration of healthy tissue over the wound. An NWPT apparatus may also serve to draw exudates from the absorbent material out of the dressing without requiring that the entire dressing be changed. When an NWPT procedure is complete, however, the absorbent material must be removed and is thus subject to the difficulties that may be caused by stray fibers. Accordingly, an absorbent filler suitable for use in wound dressings including those wound dressings adapted for use in advanced wound therapy procedures such as NWPT would be helpful.
SUMMARY
• According to one aspect of the disclosure, a method for treating a wound includes using a wound dressing comprising a plurality of fibers, each fiber having a length of at least two (2) inches. The method entails incorporating the wound dressing into a wound to keep the sides of the wound apart, and removing the wound exudate.
• According to another aspect of the disclosure, a wound dressing apparatus is configured to promote the healing of a wound, and may be used in conjunction with an NWPT system. The apparatus includes a wound cover for defining a reservoir over a wound in which a negative pressure may be maintained by forming a substantially fluid-tight seal around the wound, a vacuum source in fluid communication with the reservoir and suitable for providing an appropriate negative pressure to the reservoir to stimulate healing of the wound, and a packing structure positioned between the wound and the wound cover. The packing structure includes a core of filler material substantially surrounded by a sheath of contact material. The filler material is adapted for receiving wound fluids, and may be adapted for transporting wound fluids from the wound. The sheath of contact material is adapted for direct contact with the wound, and is permeable to wound fluids to permit passage of wound fluids through the core.
• The packing structure may define an elongate tube, and may exhibit a plurality of longitudinally spaced separation features adapted for dividing the packing structure. A pod defined between adjacent separation features may assume a closed configuration such that the sheath of contact material extends along opposite lateral edges of the pod. The separation features include a perforated tear line extending laterally across the packing structure and may be spaced apart from adjacent separation features by a distance of from about 50% to about 300% of a width of the packing feature.
• In some embodiments of the disclosure, the contact material may comprise a directionally-apertured film, and the filler material may comprise a polypropylene tow. The sheath may comprise upper and lower sheets of the directionally-apertured film having a seal around a periphery to encapsulate the filler between the upper and lower sheets, and each of the upper and lower sheets may be arranged such that a male side of the directionally-apertured film is oriented toward the interior of the packing structure to encourage exudate flow into the packing structure. Other non-adherent materials are also envisioned. Alternatively, one of the upper and lower sheets may be arranged such that a male side of the directionally-apertured film is oriented toward the interior of the packing structure, and the other of the upper and lower sheets may be arranged such that a male side of the directionally-apertured film is oriented toward the exterior of the packing structure to encourage exudate flow through the packing structure. The packing structure may comprise upper and lower sheets of contact material having a seal around a periphery to encapsulate the filler material between the upper and lower sheets. Furthermore, the packing structure may comprise at least one interior seal to define a central pod that is encircled by at least one ring-shaped pod toward a circumferential region of the packing structure. A separation feature may be included on the seal. A plurality of progressively larger ring-shaped pods toward the circumferential region of the packing structure may be defined by a plurality of generally concentric interior seals.
• The filler may include a foam layer adjacent one of the upper and lower sheets of contact material, and a tow layer adjacent the foam layer. A foam layer may be disposed on each side of the tow layer, and a hole may be formed in the foam layer to promote the flow of wound fluids through the packing structure.
• According to another aspect of the disclosure, a wound dressing for use with wounds includes a core of filler material, and a sheath of contact material substantially surrounding the core. The core of filler material is adapted for receiving wound fluids, and may also be adapted for transporting wound fluids from the wound. The contact material is adapted for positioning in direct contact with the wound, and the sheath is permeable to permit passage of the wound fluids into and through the core. A plurality of longitudinally spaced separation features is adapted for dividing the wound dressing, and adjacent separation features define a pod there between. A plurality of pods may be arranged to define a two dimensional array. The contact material may comprise a directionally-apertured film, and the filler material may comprise a polypropylene tow.
• According to still another aspect of the disclosure, a wound dressing for use with wounds includes a core of filler material comprising a polypropylene tow, a sheath of contact material substantially surrounding the core and comprising a directionally-apertured film, and a seal at a periphery of the sheath of contact material encapsulating the core within the sheath of contact material.
• According to another aspect of the disclosure, a wound filler for use with a negative wound pressure therapy apparatus, e.g., may include a wound dressing for defining a reservoir over a wound in which a negative pressure may be maintained by forming a substantially fluid-tight seal around the wound, a vacuum source in fluid communication with the reservoir and being suitable for providing an appropriate negative pressure to the reservoir to help stimulate healing of the wound, and a wound filler matrix disposed within the wound dressing. The wound filler matrix defines a length along a longitudinal axis and comprises at least one continuous fiber configured in a plurality of loop segments traversing the longitudinal axis. The wound filler matrix further includes a connecting segment extending along the longitudinal axis and connected to at least some of the loop segments. The connecting segment may maintain the integrity of the at least one continuous fiber thereby facilitating placement and removal from the wound bed. The connecting segment may be connected to each loop segment. The connecting segment may be adapted to be severed to provide a segment of the wound filler matrix to accommodate wounds of various sizes and types. The connecting segment may be dimensioned to define a handle segment extending longitudinally beyond the at least one continuous fiber.
• The connecting segment and the at least one continuous fiber may comprise different material. The at least one continuous fiber may include multifilaments. The at least one continuous fiber of the wound filler matrix may be non-absorbent, and may include an additive.
• In another embodiment, a wound dressing apparatus includes a cover layer adapted to cover a wound to provide a microbial barrier over the wound and a wound filler matrix for receiving wound fluids. The wound filler matrix may include a continuous fiber arranged in a tow configured by passing a connecting segment through the fiber to gather the fiber into a plurality of loop segments.
BRIEF DESCRIPTION OF THE DRAWINGS
• The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present disclosure and, together with the detailed description of the embodiments given below, serve to explain the principles of the disclosure.
• FIG. 1A is a cross sectional view of a wound dressing apparatus formed in accordance with the present disclosure;
• FIG. 1B is a cross sectional view of an alternate wound dressing apparatus formed in accordance with the present disclosure;
• FIGS. 2A through 2I are partial orthogonal views depicting various configurations for a wound filler as depicted inFIGS. 1A and 1B;
• FIGS. 3A through 3G are schematic views depicting various co-extrusion arrangements for individual fibers as depicted inFIGS. 2A through 2I;
• FIGS. 4A through 4F are schematic views depicting various cross sections of the individual fibers ofFIGS. 2A through 2I;
• FIG. 5 is a cross sectional view of a wound dressing apparatus including a packing structure formed in accordance with another aspect of the present disclosure;
• FIGS. 6A through 6C are partial perspective views depicting various configurations for the packing structure ofFIG. 5.
• FIG. 7A is a top plan view an alternate embodiment of a packing structure;
• FIG. 7B is a cross sectional view of the packing structure ofFIG. 4A;
• FIG. 7C is a perspective view of a male side of a directionally-apertured film;
• FIG. 8A is a top plan view of another alternate embodiment of a packing structure;
• FIG. 8B is a cross sectional view of the packing structure ofFIG. 5A;
• FIGS. 9A-9F are cross sectional schematic views illustrating a manufacturing process used for the assembly of another alternate embodiment of a packing structure;
• FIGS. 10A-10C are cross sectional views of alternate embodiments of a packing structure;
• FIG. 11 is a top plan view of alternate embodiment of a packing structure;
• FIG. 12 is a schematic view depicting an embodiment of a wound filler matrix of the present disclosure;
• FIG. 12A is a cross-sectional view of the wound filler matrix taken along thelines12A-12A ofFIG. 12;
• FIG. 12B is a cross-sectional view similar to the view ofFIG. 2A of an alternate embodiment of the wound filler matrix; and
• FIGS. 13A through 13I are opartial orthogonal views depicting various configurations for a multifilament fiber of the wound filler matrix of the present disclosure.
DETAILED DESCRIPTION
• The present disclosure relates to treatment of a wound using a wound dressing comprising a plurality of fibers, each fiber having a length of at least two (2) inches and in one embodiment, at least 4 inches and in other embodiments, at least 6 inches, and at least 8 inches. The method of treatment entails incorporating the wound dressing into a wound to keep the sides of the wound apart, and removing the wound exudate.
• In more detail, the fiber of the wound dressing may be any fiber having a length of at least two (2) inches. Included within the suitable fibers are natural fibers and man-made fibers.
• Examples of suitable fibers are natural fibers produced by plants, animals and/or geologic processes. For example, natural fibers include alginates, chitosan, rayon, vegetable fibers, which may be generated from arrangements of cellulose and bound together by lignin as in cotton, hemp, jute, flax, ramie and sisal, for example. Also, wood fibers are derived from tree sources and include groundwood, thermomechanical pulp (TMP) and bleached or unbleached kraft or sulfite (sulphite) pulps formed by a manufacturing process wherein lignin is removed to free the fibers from the wood structure. Animal fibers consist largely of proteins and include spider silk, sinew, catgut, wool and hair such as cashmere, mohair and angora, and chitosan for instance. There are also mineral sources for natural fibers such as woolastinite, attapulgite, halloysite, and asbestos.
• Suitable man-made fibers include regenerated fibers and synthetic fibers. Regenerated fibers are those fabricated from natural materials by processing these materials to form a fiber structure. For example, regenerated fibers may be derived from the pure cellulose in cotton and wood pulp to form such products as rayon and cellulose acetates. Fibers may also be regenerated from mineral sources such as glass or quartz to form fiberglass or optical fibers. Ductile metals such as copper gold or silver may be drawn to form metallic fibers, and more brittle materials such as nickel aluminum or iron may be extruded or deposited.
• Synthetic fibers are made entirely from synthetic materials such as petrochemicals, and are usually stronger than either natural or regenerated fibers. Synthetic fibers (as well as regenerated acetate fibers) tend to be thermoplastic, i.e., they are softened by heat. Therefore, these fibers may be shaped at high temperatures to add such features as pleats, creases and complex cross sections. Synthetic fibers may be formed from materials such as polyamide nylon, polyethylene terephthalatae (PET) or polybutylene teraphalate (PBT) polyester, phenol-formaldehyde (PF), polyvinyl alcohol (PVOH), polyvinyl chloride (PVC) and polyolefins such as polypropylene (PP) and polyethylene (PE).
• The fibers of the wound dressing may be gathered. Gathering of the fibers may be achieved by any known manner. For example, gathering of fibers may be achieved by any one or more of the following methods. The fibers may be gathered by entangling the fibers; or interningling the fibers; or wrapping the fibers with yarn; or thermally bonding the fibers; or ultrasonically treating the fibers; or radio frequency (RF) bonding; or adhering; or tying; or combinations of the methods; and the like.
• Furthermore the fibers may be absorbent or non-absorbent with respect to the wound exudate.
• The fibers may have a denier of about 3 to about 25 deniers per fiber, in one embodiment, and, in another embodiment, from about 3 to about 16 deniers per fiber.
• The fibers may be crimped by any known technique such as, for example, by steam jet crimping, air jet crimping, stuffer box crimping, or self crimping.
• The fibers may be treated to increase the properties of wicking and/or hydrophobicity, by any known technique. For example, the fibers may be treated with PHOBOL 7811 aqueous fluorochemical dispersion, available from Huntsman Chemicals. The dispersion may be applied to the fiber using a dip and squeeze padder or similar application method. The concentration of the dispersion can be adjusted by dilution with water to adjust the level of dispersion applied to the fibers. If desired, other suitable treatments include the use of hydrophobic aqueous binders such asAIRFLEX140 available from Air Products, silicones, and a polyurethane such as RU41-773 available from Stahl.
• It is also possible to improve the wicking and/or hydrophobicity properties of the fibers by using a melt additive such as HYD-REPEL, available from Goulston Technologies, which increases the water repellency property of the fibers. All of the fiber may be treated or a core/sheath fiber may be produced with the HYD-REPEL melt additive in the sheath.
• The fibers herein may be lofted or opened to increase apparent density or volume, by any known technique. For example, one suitable method is described in U.S. Pat. No. 3,328,850. It is described therein that a material which in the present document, is a fiber, may be opened by passing the fiber to the nip of a pair of rolls, one of which has a smooth rubbery surface. The rolls are moving at a speed faster than the speed of the fibers, and the fibers leaving the nip are passed through an air-spreading zone, in which the fibers are confined between two parallel walls. The fibers are subjected to streams of air from the walls. This is only one suitable manner of lofting or opening the fibers. Any other means for lofting or opening the fibers may be utilized
• The fibers may be combined with, or treated with, any additive or agent that enhances the healing of the wound. For example, agents such as polyhexamethylene biguanide (PHMB), or any other medicaments, antimicrobials, wound healing agents, and/or wound debriding agents, may be used to decrease the incidence of infection or otherwise promote healing of the wound. Other agents include those used in slow release treatments wherein the agent is released from the fiber into the wound over a period of time.
• The fibers may contain additional active ingredients or agents such as, for example, a therapeutic agent, an organoleptic agent and a pharmaceutical agent including, for example, an anti-microbial agent, in growth factor, an analgesic, a tissue scaffolding agent, a wound debriding agent, a hemostatic agent, an anti-thrombogenic agent, an anesthetic, an anti-inflammatory agent, an anticancer agent, a vasodilation substance, a wound healing agent, an angiogenic agent, an angiostatic agent, an immune boosting agent, a skin sealing agent, combinations thereof and the like.
• Suitable anti-microbial agents that can be used include, but are not limited to, anti-microbial metal ions, a chlorhexidine, a chlorhexidine salt, a triclosan, a polymoxin, a tetracycline, an amino glycoside (e.g., gentamicin or Tobramycin™), a rifampicin, a bacitracin, an erythromycin, a neomycin, a chloramphenicol, a miconazole, a quinolone, a penicillin, a nonoxynol 9, a fusidic acid, a cephalosporin, a mupirocin, a metronidazole, a secropin, a protegrin, a bacteriolcin, a defensin, a nitrofurazone, a mafenide, an acyclovir, a vanocmycin, a clindamycin, a lincomycin, a sulfonamide, a norfloxacin, a pefloxacin, a nalidizic acid, an oxalic acid, an enoxacin acid, a ciprofloxacin, combinations thereof and the like. In certain embodiments, a preferred anti-microbial agent can include at least one of polyhexamethylene biguanide (PHMB), a PHMB derivative such as, for example, a biodegradable biguanide (e.g., polyethylene hexaniethylene biguanide (PEHMB)), clilorhexidine gluconate, chlorohexidine hydrochloride, ethylenediaminetetraacetic acid (EDTA), variations of EDTA such as, for example, disodium EDTA or tetrasodium EDTA, combinations thereof and the like. In further exemplary embodiments, the antimicrobial agent can be PHMB.
• The method for treating wounds using the fibers herein is comprised as follows.
• (a) Providing a wound dressing comprising a plurality of fibers, each fiber having a length of at least two (2) inches, and in one embodiment, at least four (4) inches, and in other embodiments, at least 6 inches, and at least 8 inches;
• (b) Incorporating into the wound to be treated an amount of the wound dressing that is sufficient to cause the walls of the wound to remain apart thereby allowing the wound to heal from the inside to the outside of the wound; and
• (c) Removing exudate from the wound.
• In respect of the method herein for treating a wound, the fibers of the wound dressing may be absorbent or non-absorbent with respect to the wound exudate.
• Moreover, as described herein, the fibers of the wound dressing may have a denier of about 3 to about 25 deniers per fiber; or may be treated to have increased volume; or may be treated to have increased wicking ability; or may be crimped; or may be lofted; or may be combined with, or treated with, an additive, such as PHMB, that reduces infection of the wound.
• In the method herein, the wound dressing comprising the fibers herein, is incorporated into a wound in any amount that is sufficient to cause the walls of the wound to remain apart thereby allowing the wound to heal from the inside to the outside of the wound. In one embodiment, the amount of the wound dressing incorporated into the wound ranges from about 25% based on the volume of the wound to an amount of wound dressing that exceeds the volume of the wound. In another embodiment, the amount of the wound dressing incorporated into the wound ranges from about 50% to about 100% of the volume of the wound, and in another embodiment, the wound dressing is incorporated into the wound in an amount equal to the wound volume.
• In another embodiment, the wound dressing that is incorporated into the wound exerts pressure against the walls of the wound.
• In the method herein, it is required that the wound exudate be removed from the wound. The wound exudate may be removed from the wound by any known technique. In one embodiment, where the fibers of the wound dressing are non-absorbent in respect of the wound exudate, the wound exudate may be removed by any type vacuum technique such as negative pressure wound therapy (NPWT). In another embodiment, where the fibers of the wound dressing are absorbent in respect of the wound exudate, the wound exudate may be removed by removing the wound dressing containing the absorbed wound exudate from the wound. In this instance, removal of the wound dressing containing the absorbed wound exudate, may be followed by incorporating a new wound dressing comprised of absorbent fibers, as needed.
• In one embodiment, an example of a technique that may be utilized with a wound dressing comprising a non-absorbent fiber is known as negative pressure wound therapy (NPWT). The wound dressing comprising non-absorbent fibers may be positioned in a reservoir above a wound where a negative pressure may be maintained. The reservoir subjects the wound to a sub-atmospheric pressure to effectively draw wound fluid, including liquid wound exudate, from the wound without the continuous use of a vacuum pump. Vacuum pressure may be applied once, or in varying intervals, depending on the nature and severity of the wound.
• Various crimping and bulking methods are contemplated to permit individual fibers or a plurality of fibers to separate in areas such that the fibers may receive and transport wound fluids. An air jet crimping process may be used wherein a fiber is directed past turbulent streams of compressed air to entangle the individual fibers into a multitude of loops and convolutions. A steam jet crimping process may also be used wherein a fiber is directed past turbulent streams of a high temperature steam to not only produce loops and convolutions, but also to heat set these same loops and convolutions. Another crimping process is known as stuffer box crimping. Stuffer box crimping is a process by which a fiber may be forcibly fed into a crimping chamber having a restricted exit. Subsequent portions of the fiber entering the crimping chamber will impart a force causing the fiber to buckle inside the chamber until, upon emergence from the chamber, the fiber retains a crimp therein. Any of these crimping processes may be used.
• It is advantageous to utilize as the wound dressing a plurality of fibers with each fiber having a length of at least two (2) inches, in the method described herein for treating a wound. Individual fibers having a length of at least two (2) inches will have less tendency to separate from the rest of the fibers. This will minimize loose fibers that might remain in the wound, and which could cause inflammation or other impairments of the wound healing. The fibers having a length of at least two (2) inches can be gathered to further minimize the possibility of loose fibers remaining in the wound.
• Furthermore, the fibers having a length of at least two (2) inches can be modified for example, by crimping or chemical treatment to provide optimum wound properties that are important to wound healing. These include wound exudate flow, wound exudate retention, conformance to wound, an antimicrobial properties.
• Referring toFIG. 1, a wound dressing apparatus according to the present disclosure is depicted generally as10 for use on a wound “w” surrounded by healthy skin “s.” Theapparatus10 includes acontact layer18 placed in contact with the wound “w,” a wound dressing100 placed into the wound “w” over thecontact layer18 and acover layer22 placed in contact with the skin “s” to cover the wound dressing100 and wound “w.”
• Contact layer18 may be formed from perforated film permitting exudates to be drawn through thecontact layer18 into the wound dressing100. Passage of wound fluid through thecontact layer18 may be substantially unidirectional such that exudates do not tend to flow back into the wound “w.” Unidirectional flow may be encouraged by directional apertures, such as cone-shaped formations protruding from the film material (see, e.g.FIG. 7). Arranging thecontact layer18 such that the formations protrude in the direction of the wound dressing100 allows for exudates to encounter the film as an array of cone-shaped formations in the direction away from the wound “w” and as an array of collecting basins in the direction toward the wound “w.” Unidirectional flow may also be encouraged by laminating thecontact layer18 with materials having absorption properties differing from those ofcontact layer18. A non-adherent material may be selected such thatcontact layer18 does not tend to cling to the wound “w” or surrounding tissue when it is removed. One material that may be used as acontact layer18 is sold under the trademark XEROFORM® by Tyco Healthcare Group LP (d/b/a Covidien).
• Wound Dressing100 is positioned in the wound “w” over thecontact layer18 and is intended to receive and retain wound exudates. Wound dressing100 is conformable such that it may assume the shape of any wound “w” and may be packed up to any level, e.g. up to the level of healthy skin “s” or to overfill the wound such that wound dressing100 protrudes over the healthy skin “s.”
• As discussed in greater detail below, the wound dressing100 may be formed from an assembly of fibers each of which fibers having a length of at least 2 inches.
• Cover layer22 may assume a variety of forms typically used to cover a wound “w” in wound care applications. For example,cover layer22 may be formed from a flexible polymeric or elastomeric film having an adhesive coating on an underside to fasten the film to the surrounding skin “s.” Thus coverlayer22 may serve as a microbial barrier to help prevent contaminants from entering the wound “w.” In disclosed embodiments,cover layer22 may be formed from a moisture vapor permeable membrane to promote the exchange of oxygen and moisture between the wound “w” and the atmosphere. A membrane that provides a sufficient moisture vapor transmission rate (MVTR) is a transparent membrane sold under the trade name POLYSKIN® II by Tyco Healthcare Group LP (d/b/a Covidien). A transparent membrane helps permit a visual assessment of wound conditions to be made without requiring removal of thecover layer22. Alternatively,cover layer22 may comprise animpermeable membrane22.
• Referring now toFIG. 1B, the wound dressing100 of the present disclosure may also be used in any wound dressing applications such as a negative pressure wound therapy (NPWT)apparatus24. Such anapparatus24 may include a wound dressing having acontact layer18 and wound dressing100, as described with reference toFIG. 1A.Cover layer22 may be particularly adapted for such an application. For instance,cover layer22 may include a substantially continuous band of a biocompatible adhesive at theperiphery26 such that the adhesive forms a substantially fluid-tight seal with the surrounding skin “s.” Thus,cover layer22 may act as both a microbial barrier to help prevent contaminants from entering the wound “w,” and also a fluid barrier to help maintain the integrity of avacuum reservoir28.
• Avacuum port30 having aflange34 may also be included to facilitate connection of thereservoir28 to a vacuum system. Thevacuum port30 may be configured as a rigid or flexible, low-profile component, and may be adapted to receive a vacuum tube orfluid conduit36 in a releasable and fluid-tight manner. An adhesive on the underside offlange34 may provide a mechanism for affixing thevacuum port30 to thecover layer22, or alternativelyflange34 may be positioned within reservoir28 (not shown) such that an adhesive on an upper side of theflange34 affixes thevacuum port30. However thevacuum port30 is affixed to thecover layer22, a hollow interior of thevacuum port30 provides fluid communication between thefluid conduit36 and thereservoir28.Vacuum port30 may be provided as a pre-affixed component ofcover layer22, as a component offluid conduit36 or entirely independently. Alternatively,vacuum port30 may be eliminated if other provisions are made for providing fluid communication with thefluid conduit36.
• Fluid conduit36 extends from thevacuum port30 to provide fluid communication between thereservoir28 andcollection canister40. Any suitable conduit may be used forfluid conduit36 including those fabricated from flexible elastomeric or polymeric materials.Fluid conduit36 may connect to thevacuum port30, thecanister40, or other apparatus components by conventional air-tight means such as friction fit, bayonet coupling, or barbed connectors, for example. The conduit connections may be made permanent, or alternatively a quick-disconnect or other releasable means may be used to provide some adjustment flexibility to theapparatus10.
• Collection canister40 may comprise any container suitable for containing wound fluids. For example, a rigid bottle may be used as shown, or alternatively a flexible polymeric pouch may be appropriate.Collection canister40 may contain an absorbent material to help consolidate or help contain the wound drainage or debris. For example, super absorbent polymers (SAP), silica gel, sodium polyacrylate, potassium polyacrylamide or related compounds may be provided withincanister40. At least a portion ofcanister40 may be transparent or translucent to assist in evaluating the color, quality and/or quantity of wound exudates. A transparent or translucent canister may thus assist in determining the remaining capacity of the canister or when the canister should be replaced.
• Leading fromcollection canister40 is another section offluid conduit36 providing fluid communication withvacuum source50. Vacuumsource50 generates or otherwise provides a negative pressure to theNPWT apparatus24. Vacuumsource50 may comprise a peristaltic pump, a diaphragmatic pump or other mechanism that is biocompatible and draws fluids, e.g. atmospheric gasses and wound exudates, from thereservoir28 appropriate to help stimulate healing of the wound “w.” In disclosed embodiments, thevacuum source40 is adapted to produce a sub-atmospheric pressure in thereservoir28 ranging between about 20 mmHg and about 500 mmHg, more specifically, between about 75 mmHg to about 125 mmHg. One suitable peristaltic pump is the Kangaroo PET Eternal Feeding Pump manufactured by Tyco Healthcare Group LP (dibla Covidien).
• Referring now toFIG. 2A, the wound dressing100 of the present disclosure may generally assume the form of a bundle, assembly or tow of fibers each of which fibers having a length of at least 2 inches. Thefibers102 may be arranged so as to be generally non-intersecting along their length. Although not necessarily parallel, thefibers102 may be generally free from entanglement or interlacing. At least onegathering feature104 may be included to permit the bundle to help resist separation offibers102. Asingle gathering feature104 may be formed from a separate fiber wrapped or tied around the bundle to compress the bundle in a localized region. Alternatively, gathering features104 may be placed intermittently along the bundle, as shown inFIG. 2B, to help secure the tow at multiple locations, or separate fibers may be wrapped helically around the bundle as inFIG. 2C to form gatheringfeature106.
• A tow may be enclosed with a self-sealing, non-woven mesh or other porous sheet to form gatheringfeature108. A self-sealinggathering feature108 may be an elastic or slightly undersized band such thatfibers102 may be inserted through an open end of the band to be constrained under compression. Alternatively, gathering features108 may include an adhesive component such that a flat strip may be wrapped around the tow and the flat strip may be affixed by adhering either to itself or to thefibers102 with the adhesive component. As depicted inFIG. 2E, agathering feature110 may be formed with a substantial length of a non-woven mesh or a porous sheet to enclose a substantial length of the tow.
• As depicted inFIGS. 2F through 2I, thefibers102 may be arranged or constructed as shown to help permit the tow to resist separation offibers102.Fibers102 may be twisted as in a rope to provide a gathering feature112 (FIG. 2F), orfibers102 may be entangled by various processes to form a gathering feature114 (FIG. 2G). Jets of steam, air or water may be directed at localized regions in the tow to entanglefibers102 and providegathering feature114. Another entangling process involves needles used in a manner similar to needle punching to entanglefibers102. A gathering feature116 (FIG. 2H) may be provided simply by bondingfibers102 with an adhesive, or by incorporating a binding material having a lower melting temperature than thefibers102. By heating the tow, the binding material may melt and bind the fibers together upon cooling. A binding material may be provided along with one or more of the individual fibers in a co-extrusion such as a core-sheath arrangement, as described in greater detail below. As depicted inFIG. 2I, agathering feature118 may also be provided by crimping fibers to provide some degree of entanglement, as described in greater detail below. It is also envisioned that the arrangement offibers102 may include two or more of the features shown inFIGS. 2A through 2I.
• Referring toFIGS. 3A through 3G, two or more distinct polymers may be co-extruded to generate a fiber with specialized characteristics. For example, afiber120 exhibiting a concentric sheath-core arrangement is depicted inFIG. 3A. Acore polymer122 is surrounded by asheath polymer124. As discussed above,sheath polymer124 may exhibit a lower melting temperature thancore polymer122 such that thesheath polymer124 may be melted to provide a binder forfibers102. Other applications for a sheath-core arrangement may include providing a high strengthstructural core polymer122 and asheath polymer124 with surface characteristics appropriate to help promote wicking of wound fluid or to accept any of the beneficial polymer additives discussed below. Afiber126 exhibiting an eccentric sheath-core arrangement is depicted inFIG. 3B including an off-center core polymer128 andcorresponding sheath polymer130. This arrangement may be used to provide a self-crimpingfiber126 when thecore polymer128 andsheath polymer130 are provided with differing shrinkage characteristics when subject to a temperature change. When heated, thefibers126 may curl into a helix that is retained when the fiber is cooled, thus developing a crimp or bulk in an otherwiseflat fiber126. Such a self-crimping procedure may be further facilitated by using a side-by-side arrangement as depicted inFIG. 3C.Fiber132 is similar tofiber126, but differs in thatcore polymer134 andsheath polymer136 each occupy a portion of the outer surface of thefiber132. With a proper polymer selection, the side-by-side arrangement offiber132 may yield higher levels of latent crimp than the eccentric sheath-core arrangement offiber126.
• As shown inFIG. 3D, a fiber138 having a pie-wedge arrangement may include alternatingwedges comprising polymers140 and142. The wedges may be split into the component wedges upon mechanical agitation. This may assist in forming agathering feature114 as discussed above with reference toFIG. 2G. The component wedges may yield localized areas of microfibers to assist in entangling the fiber138. Afiber144 exhibiting a hollow pie wedge arrangement including a hollow center core is depicted inFIG. 3E.Fiber144 may require less agitation to split intocomponent polymers146,148.
• With reference toFIG. 3F,fiber150 exhibits an islands-in-the-sea arrangement where one or more “island”polymers152 are surrounded by a soluble “sea”polymer154. This arrangement may provide for very fine strands ofisland polymers152 to be effectively handled by manufacturing equipment. Once theisland polymers152 are in place, the soluble sea polymer is dissolved away. As many as about 37 ormore island polymers152 having a denier of about 0.04 (roughly 2 microns in diameter) may thus be handled effectively as asingle fiber150.
• Afiber156 exhibits a “three island” arrangement, as depicted inFIG. 3G. This arrangement includes threeisland polymers158 surrounded by asea polymer160.Fiber156 may be used in a manner similar tofiber150 exhibiting an islands-in-the-sea arrangement, but may be more commonly used in a manner similar tofibers120,126 and132 described above exhibiting a sheath-core arrangement.Fiber156 may be described as including threecore polymers158 collectively having an increased surface area to discourage de-lamination from a potentiallyincompatible sheath polymer160.
• Referring toFIGS. 4A through 4F,individual fibers102 may exhibit various cross sections to enhance a wicking capability or another characteristic ofwound filler100. A solid round cross section as depicted inFIG. 4A may be a standard for most synthetic fibers due to a relatively low cost when compared to another modified cross sections below. Afiber162 is depicted inFIG. 4B having a void164 in its cross section. Void164 runs the entire length of thefiber162 yielding a reduced density and rigidity offiber162 and permitting air to be trapped within. Such a cross section may facilitate crimping, entangling and/or lofting processes.
• A multi-lobal cross section may also be used as depicted inFIG. 4C.Tri-lobal fiber168 exhibits threearms170 projecting from a central region offering rigidity and resilience to the wound dressing100. A ribbon cross section as exhibited byfiber174 depicted inFIG. 4D may be described as exhibiting a bi-lobal arrangement. A ribbon cross section offers a bending direction and shape well suited for segmented fibers which may be split into micro-fibers as described above with reference toFIGS. 3D and 3E. Such a cross section may be split into micro-fiber components with relatively minor agitation when compared to other cross sections.
• Highly modifiedcross section fibers178 as depicted inFIG. 4E are sold under the trade name 4DG™ by Fiber Innovation Technology, Inc.Deep channels180 of various sizes and configurations are provided along a longitudinal axis of thefiber178 to help promote capillary wicking with its relatively large surface area. Fibers172 having a 4DG™ cross section have demonstrated a capability to transport up to 2 liters of water per hour per gram of fiber.
• Afiber184 having a bowtie cross section as depicted inFIG. 4F may be well suited for use in a self-crimping fiber as described above with reference toFIG. 3B andFIG. 3C. Polymers with differing thermal characteristics may be arranged such that the centers of mass of the two polymers are separated by a relatively greater distance than other cross sections. Afiber184 thus arranged may exhibit enhanced stretch recovery of the helical coils formed by heating and subsequently cooling thefiber184.
• Self crimping may be accomplished with an eccentric core-sheath arrangement of polymers described above with reference toFIG. 3B or a side-by-side arrangement as described with reference toFIG. 3C. Another option to produce a self crimping tow is to combine full fibers of differing thermal characteristics in a creeling process. The crimped tow may be opened, i.e., the crimped fibers may be separated or spaced, to produce a particular texture or bulk. The crimped tow may be opened by air jets, or by longitudinal stretching and relaxing of the tow with a threaded roll assembly.
• Referring now toFIG. 5, a negative wound pressure therapy apparatus according to the present disclosure is depicted generally as200.Apparatus200 includes awound dressing assembly202 definingreservoir28 in fluid communication withvacuum source50 as described above with reference toFIG. 1B.Wound dressing assembly202 includes an elongatewound packing stricture210 comprising acore212 substantially surrounded by asheath214. Thecore212 may be formed from a dressing or filler material adapted for receiving and/or transporting wound exudates, and may include any material or structure described above with reference toFIG. 1A for use with wound dressing100. Thesheath214 may be formed from acontact material214 adapted for positioning in contact with the wound “w,” and may include any material or structure described above with reference toFIG. 1A for use withcontact layer18. Thesheath214 is permeable to permit passage of wound fluids into and out of thecore212 of filler material. The packingstructure210 may be embodied as an elongate tube arranged to follow a winding path to substantially fill the wound “w” and conform to the particular geometry of the wound “w.” Such an elongate tube may be provided in continuous lengths that may be conveniently cut at the timewound dressing assembly202 is applied to accommodate the particular size of the wound “w.” Such an arrangement may not require separate and independent sizing and subsequent application of awound contact layer18 and wounddressing100.
• Referring now toFIGS. 6A through 6C, various configurations contemplated for a packing structure for use in NWPT apparatus200 (FIG. 5) are depicted. As depicted inFIG. 6A, packingstructure210 defines an elongate tube having a length “L” extending in a longitudinal direction and a maximum width “A” extending in a lateral direction. The oblong cross section of packingstructure210 is substantially consistent along the length “L” of thepacking structure210. Other cross sections may be appropriate such as a round, hexagonal or other polygonal shapes. Thesheath214 may be formed by an extrusion or similar process providing for a seamless circumference around thecore212.
• Packing structure220, depicted inFIG. 6B, includes a core offiller material222 substantially surrounded by a sheath ofcontact material224. A plurality of longitudinally spaced separation features226 provide for dividing thepacking structure220. Aseparation feature226 may comprise a perforated tear line extending laterally across packingstructure220, which a clinician may use to cut or tear away a portion of thepacking structure220 such that packingstructure220 has an appropriate length to fill a wound “w” of a particular size. Separation features226 may be spaced apart, for example, by a distance “D” of from about 50 percent to about 300 percent of a width “B” of thepacking feature220.
• A series ofpods228 may be defined between adjacent separation features226. Eachpod228 may have an open configuration wherein the core offiller material222 extends between adjacent pods through the separation features226. A portion of the dressingmaterial222 may thus be exposed across a lateral edge of thepacking structure220 when anadjacent pod226 is removed. Alternatively, eachpod228 may have a closed configuration where in the core offiller material222 is interrupted in the vicinity of theseparation feature226. For example, the sheath ofcontact material224 may be sealed to itself on the interior of packingstructure220 in the vicinity of theseparation feature226, such that the sheath ofcontact material224 extends along opposite lateral edges of thepods228. Such an arrangement ofclosed pods228 may provide an area of increased flexibility in the vicinity of theseparation feature226 when compared to a central region of thepods228. An area of increased flexibility may facilitate placement of packingstructure220 in a winding arrangement within the wound “w.”
• Referring now toFIG. 6C, packingstructure230 includes a core offiller material232 substantially surrounded by a sheath ofcontact material234. Aseparation feature236 may comprise a slit or series of longitudinally spaced slits extending laterally across packingstructure230.Slits236 may extend partially into thefiller232 such that the packingstructure230 is less resistant to cutting or tearing in the vicinity of theslits236. The sheath ofcontact material234 may be arranged with anoverlap238. Overlap238 may facilitate application of a longitudinal adhesive bond, ultrasonic weld or similar seal to facilitate assembly of packingstructure230.
• Referring now toFIG. 7A andFIG. 7B, packingstructure240 includes a core offiller material242 substantially surrounded by a sheath ofcontact material244. The sheath ofcontact material244 includes upper andlower sheets244U and244L of contact material with aheat seal246 formed around the periphery of thesheath244 to encapsulate thefiller242 therein. An adhesive bond, ultrasonic weld; or similar seal may be incorporated as an alternative or in combination withheat seal246 to encapsulate thefiller242.Packing structure240 is a generally round, saucer or puck shaped capsule, but may alternatively be formed into a variety of shapes including spheres, cylinders, cubes, tetrahedrons and other polygonal shapes.
• Filler242 assumes the form of a polypropylene tow. A tow may be described as a loose, essentially untwisted strand of a large number of unidirectional synthetic fibers. Continuous filament polypropylene fibers may be arranged to form a loosely entangled ball to form afiller142 capable of receiving wound exudates. The tow may be crimped, bulked or lofted to influence the absorptive, wicking or comfort characteristics of thefiller142. Various such processes and arrangements for the tow offiller242 are described above with reference toFIGS. 2A through 4F.
• Sheath244 is formed from a non-adherent, directionally-apertured polyolefin film such as those manufactured by Tredegar Film Products, Corp. of Richmond, Va. These films are safe for contact with a wound “w” and permit fluid to flow into thefiller242. Unidirectional flow is encouraged through such a film by apertures formed at the peak of cone-shaped formations in the film material that project in one direction. Such a film will thus have a male side, as depicted inFIG. 7C, and an opposite female side. Fluid flow is encouraged across the film from the female side to the male side and discouraged in the opposite direction.Sheath244 may be arranged such that the male side of such a film faces the interior of packingstructure240 from all directions. Fluid is thus encouraged to flow into thefiller242 regardless of the orientation in which thepacking structure240 is placed in the wound “w.” Alternatively, thelower sheet244L ofsheath244 may be oriented such that the male side faces the interior of thepacking structure240, while theupper sheet244U ofsheath244 is oriented such that the male side faces the exterior of thepacking structure240. This arrangement encourages unidirectional flow through theentire packing structure240. By placingpacking structure240 into the wound “w” with an orientation such that thelower sheet244L in contact with the wound “w,” wound fluids may be encouraged to flow into packingstructure240 by the directional apertures in thelower sheet244L, and subsequently wicked throughfiller242 to theupper sheet244U where the directional apertures encourage flow out of thepacking structure240. Wound fluids may then be removed fromwound dressing assembly202 byvacuum source50 and deposited in canister40 (FIG. 5). Regardless of the orientation of upper andlower sheets244U and244L,sheath244 should be pliable and soft when heat sealed such that packingstructure240 does not cause pain to the patient when placed inside a wound “w.”
• Referring now toFIG. 8A andFIG. 8B, packingstructure250 includes a core offiller material252 substantially surrounded by a sheath ofcontact material254. A plurality of ring-shaped interior heat seals256 are formed in a generally concentric arrangement between discrete segments of thefiller material252, thus dividing thepacking structure250 into a number of pods. Acentral pod258 lies in the center of thepacking structure250, and is encircled by progressively larger ring-shapedpods260,262 toward the circumferential regions of thepacking structure250. Anexterior heat seal264 is formed around the periphery of packingstructure250 to close theoutermost pod262. Aperforated ring268 is formed on each of the interior heat seals256 to provide a separation feature for the pods.
• Although packingstructure250 is depicted as including only threedistinct pods258,260 and262, any number of pods may be formed into such an arrangement to form a packing structure of any desired size. Heat seals256,264 may have a width “X” of about 1 cm or less, and may be separated by a distance “Y” of about 1 inch to about 2 inches. In use, when the size of a particular wound “w” is assessed, outer pods, e.g.262, may be removed using perforatedring268 to permit packingstructure250 to assume an appropriate size for the wound “w.”
• To manufacture a structure such as packingstructure240 and250, a mold “m” may be formed as depicted schematically (in cross-section) inFIG. 9A. The mold “n” may include indentations “i” on an upper surface thereof, which are sized and spaced appropriately to form a desired number of pods. The mold depicted inFIG. 9A may be used to form a packing structure with four distinct pods including a central pod and three surrounding ring shaped pods.
• A flat sheet ofsheath material254L maybe placed over the mold “m” (FIG. 9B) with a male side facing up. A directionally-apertured film such as those manufactured by Tredegar Film Products may be provided with, or marked with a distinguishing color on each side such that a proper orientation of the sheet may be verified. The sheet ofsheath material254L may then be drawn into the indentations “i” (FIG. 9C). Airflow may be directed through the mold “m” to draw in thesheath material254L, or thesheath material254L may be urged into place by any other suitable means.
• Next, thefiller material252 may be positioned in the indentations “i” over thesheath material254L, and may be arranged to overfill the indentations as depicted inFIG. 9D. A central indentation “i” may accommodate an entangled mass of polypropylene tow while surrounding indentations “i” may be conveniently filled by a twisted or spun rope of the tow material arranged in a circular fashion.
• Another sheet of thesheath material254U may be placed over thefiller252, and may be drawn downward into the intermediate spaces between the indentations in the mold “m” (FIG. 9E). The male side of the tipper sheet ofsheath material254U may face downward toward the filler, and toward the male side of the lower sheet ofsheath material254L. An appropriate heat sealer “h” (FIG. 9F) having appropriately sized heat sealing rings may then be pressed down into each of the intermediate spaces to form interior heat seals256, and another heat sealing ring may similarly formexterior heat seal264. The heat sealing rings may include a Teflon® or similar coating such that thesheath material254U does not tend to stick to the heat sealing rings. The heat sealing rings may alternately be applied individually, or the heat seals256,264 may be replaced by seals formed with a laser or ultrasonic welding mechanism that traverses a path around thefiller252 to encapsulate thefiller252.
• Once thefiller252 has been encapsulated, the filler and the sheath material may be removed from the mold “m” for further processing. For example, the structure may be delivered to another apparatus for formingperforated rings268 to complete the packing structure. Alternatively, the mold “m” or the heat sealer “h” may include a perforating mechanism (not shown) to formperforated rings268 along with the formation of the heat seals256,264.
• A variety of other embodiments of a packing structure may be formed with minor variations to the process described above. For example, thefiller252 may not necessarily overfill the indentations “i,” but may be fill the indentations “i” up to the level of the top surface of the mold “m.” Also, the upper layer ofsheath material254U may be replaced with a material that is dissimilar to the lower layer of sheath material. For example, the lower layer ofsheath material254L may be formed of a directionally-apertured polyolefin film while the upper layer may be formed of a porous or nonporous sheet of a polypropylene.
• Referring now toFIG. 10A, packingstructure260 includes a core offiller material262 substantially surrounded by a sheath ofcontact material264. Similarly tosheath244 discussed above with reference toFIG. 7B, the sheath ofcontact material264 includes upper andlower sheets264U and264L of contact material with aseal246 formed around the periphery to encapsulate thefiller262 therein. The upper andlower sheets264U and264L may be formed from a directionally-apertured film and may be oriented as discussed above.Filler262 may be distinguished in thatfiller262 is formed from at least two distinct materials.
• Filler262 comprises a layer of polypropylene tow is designated262T, and a layer foam is designated262F.Tow layer262T may take any form discussed above with reference toFIG. 7A, andfoam layer262F may be formed from a resilient, open-cell foam such as polyurethane, polyester or polyolefin foam.Foam layer262F may be effective to receive wound fluids from the wound, and may also readily release the wound fluids such that they may be removed from a dressingassembly202 by a vacuum source50 (seeFIG. 5).Foam layer262F exhibits uniform compression when subject to the evacuation cycles of an NWPT treatment such that potentially painful pressure points in thepacking structure260 are managed and the periphery of the wound “w” may be drawn inward evenly. Thefoam layer262F may be positioned adjacent thelower sheet264L ofsheath264 as depicted inFIG. 10A to provide a cushion to the wound bed. Alternative structures include apacking structure270, which may include afiller272 having afoam layer272F on each side of atow layer272T.Packing structure280, also includes afiller282 having afoam layer282 on each side of atow layer282T. Ahole282H is formed in eachfoam layer282 to promote the flow of exudates through the packingstructure280.
• Referring now toFIG. 11, packingstructure290 includes a core offiller material292 substantially surrounded by sheath ofcontact material294. Aseal296 is formed in the sheath ofcontact material294 such that a plurality ofpods298 are formed in a two dimensional array.Pods298 may vary in size, but are preferably about 1.25 inches in length by about 1.25 inches in width or smaller to provide acustomizable packing structure290. Depending on the particular dimensions of a wound “w”unnecessary pods298 may be cut away to accommodate smaller wounds “w,” orpods298 may be folded onto one another along theseal296 to accommodate deeper wounds “w.” Perforations (not shown) may be formed in thesheath294 along theseal296 to provide a separation feature to facilitate removal ofunnecessary pods298. Alternatively,sheath294 may be free of perforations to increase the strength and integrity of packingstructure290 inside a wound “w.” A separation feature may thus be provided by creating aseal296 wide enough to be readily cut by a clinician without inadvertently cutting into the core offiller292. A packingstructure290 without perforations helps to insureindividual pods298 do not inadvertently become detached from the packingstructure290, and thus decreases the probability that apod290 will be inadvertently left in the wound “w.”
• According to another aspect of the disclosure, awound filler matrix300 of the present disclosure as depicted inFIG. 12 incorporates at least one continuous fiber comprising either natural or man-made filaments to form a structure suitable for conveying, transferring, and/or absorbing exudates. As indicated above, continuous filaments include those relatively long strands of a synthetic material such as nylon, rayon, etc., which may offer a smooth continuous outer surface substantially free of the protruding fibrils commonly associated with natural materials such as cotton. Because of the relatively smooth surfaces, structures such as fabrics or yarns formed from continuous filaments have a substantially lower tendency to become attached to a healing wound bed than do structures formed from natural filaments. Also, because of the relatively long length, continuous filaments have a substantially lower tendency to become separated from a structure and be inadvertently deposited in a wound as the dressing is changed.
• Thewound filler matrix300 of the present disclosure may generally assume the form of a bundle, assembly, or tow of a continuous fiber. As illustrated inFIG. 12, thewound filler matrix300 defines a length along longitudinal axis “x” about which at least onefiber301 is disposed.Fiber301 may be configured in a plurality ofloop segments303 which are arranged to traverse longitudinal axis “x.” A connectingsegment305 extends along longitudinal axis “x” and is connected to at least several, possibly, all of theloop segments303.Connecting segment305 may be parallel or coincident to longitudinal axis “x”.Connecting segment305 may be stitched, pulled; tied, gathered, adhered (FIG. 12A) or otherwise passed through (FIG. 12B) and aboutfiber301 to shapeloop segments303 and provide the structure tomatrix300.Connecting segment305 may extend beyond the effective length offiber301 thereby providing allextension307 or handle which may be grasped by the clinician to facilitate placement and/or removal of thewound filler matrix100 relative to the wound bed. The connectingsegment305 prevents the filament(s) and/or fibril(s) of the fiber from releasing frommatrix300 thereby minimizing the potential of the filaments remaining in the wound “w” upon removal of the material therefrom.
• Wound filler matrix300 may be severed at any predetermined longitudinal location to accommodate wounds of various sizes. With this arrangement, multiple size wounds may be accommodated with asingle matrix300. In addition, woundfiller matrix300 may be cut to provide a specific dimensioning to accommodate a specific wound type, e.g., for a tunneling or deep wound. It may be desirable to sever the matrix at a location along the longitudinal axis (e.g., location “k”) such that aportion305aof connectingsegment305 extends from the last loop. This may facilitate placement and/or subsequent removal of the reducedmatrix segment300a.Wound filler matrix300 may be severed at several locations along the longitudinal axis “x” depending on the overall length of thewound filler matrix300 provided and the wound type and/or size.
• Thefibers301 ofwound filler matrix300 may be formed from mono- or multi-filaments302. A monofilament, or a single strand of material of a sufficient thickness to be directly woven intomatrix300. A multifilament is more than one strand of material that has been twisted, bonded, or otherwise placed together to form a fiber as illustrated above inFIGS. 2A-2I. Each of the embodiments offiber301 depicted inFIGS. 13A-13I correspond to the multifilimant arrangements ofFIGS. 2A-2I, and may be arranged in the sinusoidal configuration depicted inFIG. 12 and attached via a connectingsegment305.
• Thefilaments102 ofwound filler matrix100 may take a wide variety of forms. Materials may be classified generally into two basic types including natural fibers and man-made fibers. Further, natural and man-made fibers include both absorbent and non-absorbent varieties as within the purview of those skilled in the art. Natural fibers are those produced by plants, animals and/or geologic processes. For example, natural fibers include vegetable fibers, which may be generated from arrangements of cellulose and bound together by lignin as in cotton, hemp, jute, flax, ramie and sisal, for example. Also, wood fibers are derived from tree sources and include groundwood, thermomechanical pulp (TMP) and bleached or unbleached kraft or sulfite (sulphite) pulps formed by a manufacturing process wherein lignin is removed to free the fibers from the wood structure. Animal fibers consist largely of proteins and include spider silk, sinew, catgut, wool and hair such as cashmere, mohair and angora, for instance. There are also mineral sources for natural fibers such as wollastinite, attapulgite, halloysite, and asbestos.
• Man-made fibers include regenerated fibers and synthetic fibers. Regenerated fibers are those fabricated from natural materials by processing these materials to form a fiber structure. For example, regenerated fibers may be derived from the pure cellulose in cotton and wood pulp to form such products as Rayon and cellulose acetates. Fibers may also be regenerated from mineral sources such as glass or quartz to form fiberglass or optical fibers. Ductile metals such as copper gold or silver may be drawn to form metallic fibers, and more brittle materials such as nickel aluminum or iron may be extruded or deposited.
• Synthetic fibers are made entirely from synthetic materials such as petrochemicals, and are usually stronger than either natural or regenerated fibers. Synthetic fibers (as well as regenerated acetate fibers) tend to be thermoplastic, i.e., they are softened by heat. Therefore, these fibers may be shaped at high temperatures to add such features as pleats, creases and complex cross sections. Synthetic fibers may be formed from materials such as polyamide nylon, polyethylene terephthalatae (PET) or polybutylene teraphalate (PBT) polyester, phenol-formaldehyde (PF), polyvinyl alcohol (PVOH), polyvinyl chloride (PVC) and polyolefins such as polypropylene (PP) and polyethylene (PE).
• Connecting segment305 ofwound filler matrix300 may also take a wide variety of forms including the types and materials described above.Connecting segment305 may be formed from the same or a different material as fiber101.
• Various suppliers may produce filaments as described above, as any commercial fiber or suture material may advantageously be employed inwound matrix300. A non-exhaustive list of materials includes, but are not limited to, polymers and polymer blends selected from the group consisting of polyolefins (such as polyethylene and polypropylene including atactic, isotactic, syndiotactic, and blends thereof as well as, polyisobutylene and ethylene-alphaolefins copolymers, and fluorinated polyolefin such as polytetrafluoroethylene); polyesters (such as polyethylene terephthalate and polybutylene terephthalate); acrylic polymers and copolymers; inodacrylics; vinyl halide polymers and copolymers (such as polyvinyl chloride); polyvinyl ethers (such as polyvinyl methyl ether); polyvinylidene halides (such as polyvinylidene fluoride and polyvinylidene chloride); polyacrylonitrile; polyvinyl ketones; polyvinyl aromatics (such as polystyrene); polyvinyl esters (such as polyvinyl acetate); copolymers of vinyl monomers with each other and olefins (such as etheylene-methyl methacrylate copolymers, acrylonitrile-styrene copolymers, ABS resins and ethylene-vinyl acetate copolymers); polyamides (such as nylon 4, nylon 6, nylon 6.6, nylon 610, nylon 11, nylon 12 and polycaprolactam); alkyd resins; polycarbonates; polyoxymethylenes; polyimides; polyethers; epoxy resins; aramids, polyurethanes; rayon; rayon-triacetate; and spandex.
• Various polymer additives may be applied to individual mono- or multi-filaments102, any of the filaments described above or amatrix300 to enhance the healing of wound “w.” For example, agents such as polyhexamethylene biguanide (PHMB) or other medicaments, antimicrobials, wound healing agents and wound debriding agents may be used to decrease the incidence of infection or otherwise promote healing of the wound “w.” Such agents may include those agents for use in slow release treatments wherein the agent is released from the matrix material into the wound over time. Hydrolysis stabilizers may be incorporated to control the release of an agent or to maintain the integrity of the tow. Also, wetting agents may be applied to promote a moist wound environment.
• Other additives may facilitate the removal ofmatrix100 from the wound. For example, silicone or floropolymers such as PTFE may be added to providefilaments102 with a slicker surface. A slicker surface may help allow the tow to conform comfortably to the shape of the wound “w.” Still other additives may facilitate construction of thewound filler matrix100 such as compatibilizers and adhesion promoters. Still other additives such as phase change materials, nanoparticles, UV-absorbers and sunblocks, stain resistant agents or flame retardants may find additional utility when in awound matrix300.
• There are various types of manufacturing processes for the combination of multifilaments with one another to form the fiber. It may be convenient to supply each of the filaments to be combined coiled onto a spool to help provide the capability of continuous feeding of substantial lengths of the coiled filaments. The spools are normally mounted in an array which is commonly referred to as a creel. A creel may include a plurality of spindles projecting in a vertical direction from a base frame to accept spools with an internal void, such that the spools may spin about the spindles to pay Out a length of the filament. Such a manufacturing process provides an opportunity to combine filaments to produce a tow with specific characteristics. One or more of the spools may simply be stocked with a filament having differing characteristics than other spools on the creel.
• Filaments of differing denier per filament, e.g., 3, 11, or 18 denier per filament, may be combined to produce a fiber with a specific total denier, e.g., from about 1000 to about 10,000. The denier per filament may be conveniently adjusted to control fluid flow properties and the resiliency ofmatrix100 when subject to application or removal pressure. Also, an exact number of filaments having a relatively low melting temperature may be incorporated into a creeling process to provide precise control over the adhesive properties that such filaments may provide when melted. Mixing of different polymers such as polypropylene with high tenacity PET is contemplated to control tow characteristics such as strength and wicking capability of a tow. A single filament or any number of filaments coated with an additive or healing agent described above may be incorporated into a fiber to promote healing of the wound “w.” Any number of combinations of any of the filaments described above in any quantity may be assembled to produce a tow with the exact characteristics desired.
• Also, other materials or similar materials arranged in a differing manner may be inserted into a fiber in a creeling process. For instance, porous membrane tubes may be inserted into or over a multifilament fiber to provide a bonding feature. Also twisted filaments, filaments with differing crimp patterns, or crimp patterns with differing spacing may be combined to form a fiber for use asmatrix300.
• Various crimping and bulking methods are contemplated to permit the fiber of a tow to separate in areas such that the tow may receive and transport wound fluids. An air jet, or steam jet crimping process, or any of the crimping processes described above may be used to impart an S- or Z-type crimp to the fiber. These S- and Z-type crimps refer to a direction of crimping such that the crimped fiber form a zig-zag pattern that resembles either letter “S” or letter “Z.”
• Self crimping may be accomplished with an eccentric core-sheath arrangement of polymers described above with reference toFIG. 3B or a side-by-side arrangement as described with reference toFIG. 3C. Another option to produce a self crimping fiber is to combine full filaments of differing thermal characteristics in a creeling process. The crimped fiber may be opened, i.e., the loop segments of crimped fiber may be separated or spaced, to produce a particular texture or bulk. The loop segments of crimped fiber may be opened by air jets, or by longitudinal stretching and relaxing of the fiber with a threaded roll assembly.
• An embodiment of the present disclosure comprises a multifilament fiber tow formed from primarily round cross section polypropylene filaments with a denier per filament from about 6 to about 10, e.g., about 8. The fiber may be crimped with either an S or Z-type crimp, and the loop segments may be lofted or opened by air jets or by stretching and relaxing. The fiber may be creeled from multi-filament yarns including a sufficient number of individual filaments to exhibit a yarn denier of about 300. About 100 spools of the about 300 denier yarns may be creeled to form a total tow denier of about 30,000. The yarns on about 30 of the spools may be treated with an antimicrobial such as PHMB, while the yarns on the remaining about 270 spools may be untreated. The fiber may be encapsulated in a spun polypropelene non-woven web to minimize the effect of loose filaments protruding from the tow. Alternatives include a similar fiber subject to air jet entanglement rather than encapsulation, and also a fiber in which substantially all of the yarns or filaments are treated with PHMB.
• One-piece removal of such a tow from a wound “w” may be thus ensured where dressing material remaining in the wound “w” might otherwise go unnoticed.
• Although the foregoing disclosure has been described in some detail by way of illustration and example, for purposes of clarity or understanding, it will be obvious that certain changes and modifications may be practiced within the scope of the appended claims. For example, it is envisioned that thewound filler matrix300 may be used independent of the other components of the wound dressing10 or may be used in combination withcover layer22 and/orcontact layer18.Wound filler matrix300 may be used as a wound bandage in the absence of negative pressure therapy, e.g., as a wound covering in a conventional application. Other uses are also envisioned.

Claims (52)

1. A method for treating a wound comprising:

(a) providing a wound dressing comprising a plurality of fibers, each fiber having a length of at least two inches;

(b) incorporating the wound dressing into the wound to be treated in an amount that is sufficient to cause the walls of the wound to remain apart thereby allowing the wound to heal from the inside to the outside of the wound; and

(c) removing exudate from the wound.

2. The method ofclaim 1 wherein the fibers are gathered by at least one technique selected from the group consisting of entangling, intermingling, wrapping with yarn, thermally bonding, ultrasonically treating, radio frequency (RF) bonding, adhering, typing, or combinations thereof.

3. The method ofclaim 1 wherein the fibers are absorbent or non-absorbent with respect to the wound exudate.

4. The method ofclaim 1 wherein the fibers are treated to increase the volume of the fibers.

5. The method ofclaim 1 wherein the fibers are treated to increase the wicking ability of the fibers.

6. The method ofclaim 1 wherein the fibers are crimped.

7. The method ofclaim 1 wherein the fibers are lofted.

8. The method ofclaim 1 wherein the fibers are combined with, or treated with, an agent that enhances the healing of the wound.

9. The method ofclaim 8 wherein the agent is selected from the group consisting of an antimicrobial, a medicament, a wound debriding agent, or mixtures thereof.

10. The method ofclaim 9 wherein the agent is an antimicrobial selected from the group consisting of an antimicrobial metal ion, a chiorhexidine, a chiorhexidine salt, a triclosan, a polymoxin, a tetracycline, an amino glycoside, a rifampicin, a bacitracin, an erythromycin, a neomycin, a chloramphenicol, a miconazole, a quinolone, a penicillin, a nonoxynol 9, a fusidic acid, a cephalosporin, a mupirocin, a metronidazole, a secropin, a protegrin, a bacteriolcin, a defensin, a nitrofurazone, a mafenide, an acyclovir, a vanocmycin, a clindamycin, a lincomycin, a sulfonamide, a norfloxacin, a pefloxacin, a nalidizic acid, an oxalic acid, an enoxacin acid, a ciprofloxacin, a polyhexamethylene biguanide (PHMB)) a PHMB derivative, a biodegradable biguanide, polyethylene hexamethylene biguanide (PEHMB)), chlorohexidine gluconate, clilorohexidine hydrochloride, ethylenediaminetetraacetic acid (EDTA), disodium EDTA, tetrasodium EDTA, and combinations thereof.

11. The method ofclaim 9 wherein the agent is an antimicrobial selected from the group consisting of polyethylene hexamethylene biguanide (PEHMB), polyhexamethylene biguanide (PHMB), a derivative of a polyhexamethylene biguanide, a chlorhexidine salt, and mixtures thereof.

12. The method ofclaim 1 wherein each fiber has a length of at least four inches.

13. The method ofclaim 1 wherein the fibers have a denier of about 3 to about 25 deniers per fiber.

14. The method ofclaim 1 wherein the amount of the wound dressing incorporated into the wound to be treated ranges from about 25%, based on the volume of the wound, to an amount that exceeds the volume of the wound.

15. The method ofclaim 14 wherein the amount of wound dressing incorporated into the wound ranges from about 50% to about 100%, based on the volume of the wound.

16. The method ofclaim 1 wherein the amount of wound dressing incorporated into the wound is equal to the volume of the wound.

17. The method ofclaim 1 wherein the wound dressing that is incorporated into the wound to be treated exerts pressure against the walls of the wound.

18. The method ofclaim 1 wherein the exudate is removed from the wound by vacuum.

19. The method ofclaim 1 wherein the fibers are non-absorbent with respect to the wound exudate, and the wound exudate is removed by a vacuum procedure.

20. The method ofclaim 19 wherein the vacuum procedure is negative pressure wound therapy.

21. The method ofclaim 1 wherein the fibers are absorbent with respect to the wound exudate, and the wound exudate is removed by removing the wound dressing that contains the absorbed wound exudate from the wound.

22. The method ofclaim 1 wherein each fiber has a length of at least six (6) inches.

23. The method ofclaim 1 wherein each fiber has a length of at least eight (8) inches.

24. An apparatus to promote the healing of an exuding wound comprising:

a wound cover for defining a reservoir over a wound in which a negative pressure may be maintained by forming a substantially fluid-tight seal around the wound;

a vacuum source in fluid communication with the reservoir, the vacuum source suitable for providing an appropriate negative pressure to the reservoir to stimulate healing of the wound; and

a packing structure positioned between the wound and the wound cover, the packing structure comprising a core of filler material substantially surrounded by a sheath of contact material, wherein the filler material is adapted for receiving wound fluids, and the contact material is adapted for positioning in direct contact with the wound, and being permeable to permit passage of the wound fluids.

25. The apparatus according toclaim 24, wherein the packing structure defines an elongate tube.

26. The apparatus according toclaim 25, wherein the packing structure further comprises a plurality of longitudinally spaced separation features adapted for dividing the packing structure, adjacent separation features defining a pod there between.

27. The apparatus according toclaim 26, wherein each of the pods is closed such that the sheath of contact material extends along opposite lateral edges of the pods.

28. The apparatus according toclaim 26, wherein the separation features comprise a perforated tear line extending laterally across the packing structure.

29. The apparatus according toclaim 26, wherein adjacent separation features are spaced apart by a distance of from about 50% to about 300% of a width of the packing feature.

30. The apparatus according toclaim 24, wherein contact material comprises a directionally-apertured film.

31. The apparatus according toclaim 30, wherein the sheath comprises upper and lower sheets of the directionally-apertured film having a seal around a periphery to encapsulate the filler between the upper and lower sheets, and wherein the each of the upper and lower sheets are arranged such that a male side of the directionally-apertured film is oriented toward the interior of the packing structure to encourage exudate flow into the packing structure.

32. The apparatus according toclaim 30, wherein the packing structure comprises upper and lower sheets of contact material having a seal around a periphery to encapsulate the filler between the upper and lower sheets, and wherein one of the upper and lower sheets is arranged such that a male side of the directionally-apertured film is oriented toward the interior of the packing structure, and the other of the upper and lower sheets is arranged such that a male side of the directionally-apertured film is oriented toward the exterior of the packing structure.

33. The apparatus according toclaim 30, wherein the filler material comprises a polypropylene tow adapted to convey the wound fluids.

34. The apparatus according toclaim 24, wherein the packing structure comprises upper and lower sheets of contact material having a seal around a periphery to encapsulate the filler between the upper and lower sheets.

35. The apparatus according toclaim 34, wherein the packing structure further comprises at least one interior seal to define a central pod encircled by at least one ring-shaped pod toward a circumferential region of the packing structure, the at least one interior seal including a separation feature thereon.

36. The apparatus according toclaim 35, wherein the at least one interior seal comprises a plurality of generally concentric seals defining a plurality of progressively larger ring-shaped pods toward the circumferential region of the packing structure.

37. The apparatus according toclaim 34, wherein the filler comprises a foam layer adjacent one of the upper and lower sheets of contact material, and a tow layer adjacent the foam layer.

38. The apparatus according toclaim 37, wherein a foam layer is disposed on each side of the tow layer.

39. The apparatus according toclaim 38, wherein a hole is formed in the foam layer to promote the flow of wound fluids through the packing structure.

40. A wound dressing for use with wounds comprising:

a core of filler material adapted for receiving wound fluids;

a sheath of contact material substantially surrounding the core, wherein the contact material is adapted for positioning in direct contact with the wound, and wherein the sheath is permeable to permit passage of the wound fluids into the core; and

a plurality of longitudinally spaced separation features adapted for dividing the wound dressing, adjacent separation features defining a pod therebetween.

41. The wound dressing according toclaim 40, wherein a plurality of pods are arranged to define a two dimensional array.

42. The wound dressing according toclaim 40, wherein the filler material comprises a polypropylene tow and the sheath of contact material comprises a directionally-apertured film.

43. A wound dressing for use with wounds comprising:

a core of filler material comprising a polypropylene tow;

a sheath of contact material substantially surrounding the core, the sheath of contact material comprising a directionally-apertured film; and

a seal at a periphery of the sheath of contact material encapsulating the core within the sheath of contact material.

44. A negative wound pressure therapy apparatus, comprising:

a wound dressing for defining a reservoir over a wound in which a negative pressure may be maintained by forming a substantially fluid-tight seal around the wound;

a vacuum source in fluid communication with the reservoir, the vacuum source suitable for providing an appropriate negative pressure to the reservoir to help stimulate healing of the wound; and

a wound filler matrix disposed within the wound dressing, the wound filler matrix defining a length along a longitudinal axis and comprising at least one continuous fiber configured in a plurality of loop segment traversing the longitudinal axis, the matrix including a connecting segment extending along the longitudinal axis and connected to at least some of the loop segments.

45. The apparatus according toclaim 44 wherein the connecting segment is connected to each loop segment.

46. The apparatus according toclaim 44 wherein the connecting segment is adapted to be severed to provide a segment of the wound filler matrix.

47. The apparatus according toclaim 44, wherein the connecting segment is dimensioned to define a handle segment extending longitudinally beyond the at least one continuous fiber.

48. The apparatus according toclaim 44, wherein the connecting segment and the at least one continuous fiber comprise different material.

49. The apparatus according toclaim 44, wherein the at least one continuous fiber comprises multifilaments.

50. The apparatus according toclaim 44, wherein the at least one continuous fiber of the wound filler matrix is non-absorbent.

51. The apparatus according toclaim 44, wherein the at least one continuous fiber of the matrix includes an additive.

52. A wound dressing apparatus, comprising:

a cover layer adapted to cover a wound to provide a microbial barrier over the wound; and

an absorbent matrix for receiving and retaining wound fluids, the absorbent matrix comprising a continuous fiber arranged in a tow configured by passing a connecting segment through the fiber to gather the fiber into a plurality of loop segments.

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