SYSTEMS AND METHODS FOR WOUND PROTECTION AND EXUDATE MANAGEMENT
The present invention provides systems and methods for protecting a wound and managing exudate released from the wound comprising a dressing having a support cushion for surrounding the wound and periwound region; a wicking strip for application in the periwound region between the support cushion and the wound; and a reservoir for application over the wicking strip, the wicking strip configured to transfer exudate from the wound to the reservoir, where the exudate is sequestered. Various alternative embodiments are described in which the wicking strip may be custom-fit to approximate an irregular wound margin, to apply a preferred pressure gradient to the periwound regions, to periodically apply fluids to the wound bed or to apply negative pressure wound therapy. Methods of applying the dressing also are provided.
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This application is a continuation under 35 U.S.C. §120 of U.S. patent application Ser. No. 13/305,569, filed Nov. 28, 2011 and entitled “Systems and Methods for Wound Protection and Exudate Management,” the entire contents of which are incorporated by reference herein, which is a continuation of U.S. patent application Ser. No. 12/416,826, filed Apr. 1, 2009, now U.S. Pat. No. 8,067,662 and entitled “Systems and Methods for Wound Protection and Exudate Management,” the entire contents of which are incorporated by reference herein.II. FIELD OF THE INVENTION
This application generally relates to systems and methods for promoting the healing of wounds, and particularly to systems and methods for promoting the healing of wounds that generate exudate.III. BACKGROUND OF THE INVENTION
Wounds occur when the integrity of tissue is compromised, affecting one or more layers of the epidermis or underlying tissue. Acute wounds may be caused by an initiating event, such as a accident-related injury, surgical procedure or by operation of an infectious disease, and generally take the form of punctures, abrasions, cuts, lacerations, or burns. Chronic wounds are wounds that generally do not heal within three months, due to one or more of ischemia of the vessels supplying the tissue, venous hypertension or compromise of the immune response, such as observed, for example, with venous ulcers, diabetic ulcers and pressure ulcers. Depending on etiology, such as diabetes, venous insufficiency, or cardiovascular failures, acute wounds may become recalcitrant and even chronic.
The introduction of bacteria from external sources into the wound typically causes inflammation that activates the patient's immune response, in turn causing white blood cells, including neutrophil granulocytes, to migrate towards the source of inflammation. While they fight pathogens, such neutrophils also release inflammatory cytokines and enzymes that damage cells. In particular, the neutrophils produce an enzyme called myeloperoxidase that in turn is metabolized to produce reactive oxygen species that kill bacteria. Collaterally, such enzymes and reactive oxygen species damage cells in the margin surrounding the wound, referred to as the “periwound,” thereby preventing cell proliferation and wound closure by damaging DNA, lipids, proteins, the extracellular matrix and cytokines that facilitate healing. Because neutrophils remain in chronic wounds for longer than in acute wounds, they contribute to higher levels of inflammation. Moreover, the persisting inflammatory phase in chronic wounds contributes to exudate (fluid that flows from the wound) with high concentrations of matrix metalloproteases (MMPs). Excess MMPs results in degradation of extracellular matrix protein. In addition to damaging the wound, exudate damages the periwound tissue exposed to it as well. In particular, exudate that flows out of the wound and onto periwound region may damage the fragile skin, which is already compromised due to the patients underlying etiology, such as diabetes. Such damage may degrade the periwound skin and cause its breakdown and turn it into a wound. Thus, exudate flow onto the periwound region will cause many complications, including, the potential for increasing the size of the wound and prolonging its healing. Such damage to the skin in the periwound region (periwound skin) makes it more susceptible to tearing and resultant intense pain as dressings or devices adhered to them are removed. Other complications include infection of the periwound region and intense itching.
Patients suffering from chronic wounds frequently report experiencing severe and persistent pain associated with such wounds, which may arise from necrosis of and/or nerve damage of the skin and underlying tissue. Treatment for such pain often consists of low dose analgesics, while topical antibiotics and/or debridement, which seeks to remove necrotic tissue from the wound, may be used to control the bacterial load at the wound site.
Conventional wound treatment also typically involves covering the wound with a dressing to prevent further contamination and infection, to retain moisture, and to absorb exudate. While exudate contains biochemical compounds that benefit wound healing as noted above, its excessive amount in wound or its presence in the periwound region facilitates degradation of tissue, and the exudate additionally serves as a growth medium for bacteria. The consistency of exudate varies, depending on the type of wound and the stage of healing. For example, exudate may be watery, extremely viscous, or somewhere in between. Moreover, the sizes of wounds can vary greatly, as can their care.
Although a wide variety of dressings have been developed, few previously-known wound treatment systems properly manage exudate, e.g., removing a sufficient amount of exudate from the wound site, while protecting the periwound region from damaging contact with the exudate. Moreover, conventional systems typically do not address the pain created by the wound treatment system, particularly where the wound treatment system continuously contacts the wound. For example, gauze, which is applied directly onto a wound, is capable of absorbing only a limited amount of exudate, and readily transports excess exudate onto the periwound region, causing maceration and damage. Moreover, the gauze typically is in direct contact with the wound and adheres to it, so that normal motion of the patient results in rubbing, itching and discomfort. In addition, removal of the gauze at periodic intervals is painful and frequently disrupts any healing that may have occurred.
Some previously-known approaches to wound treatment attempt to reduce adhesion between the wound and the dressing by applying additional substances. For example, the wound and dressing may be soaked in saline water to loosen adherence and/or soften any scabs that formed, thus facilitating removal of the dressing. Or, for example, antibiotic ointments such as polymyxin B sulfate or bacitracin can be applied to reduce sticking. However, such methods are not always satisfactory because soaking a particular wound in water or applying ointments may not be practicable or recommended.
Some previously-known dressings are promoted as being “non-stick” or “non-adherent,” such as TELFA™ and XEROFORM™, and other brands that may be composed of materials such as hydrocolloids, alginates, and hydrofilms. Regardless of the level of adherence of such dressings to the wound, continuous contact between the dressing and wound disturbs the fragile wound matrix, and may undermine the growth of blood vessels and epithelial cells in the wound bed. Such disturbance often occurs when the dressing is removed, or simply as a result of the contact between the bandaged area and the patient's environment. Pain is often concomitant with such disturbances. In addition, previously-known “non-stick” dressings usually do not absorb sufficient amounts of exudate, and thus require frequent monitoring and changing. These drawbacks add to the cost of use and limit the applicability of such previously-known wound treatment systems.
Previously-known dressings commonly have only a limited ability to manage wound exudate. As noted above, prolonged exposure of otherwise healthy skin to exudate may cause degradation of the periwound region. The moisture of the exudate may cause maceration, which is a softening of the skin that compromises its integrity and makes the skin in the periwound region vulnerable to physical insult and infection.
Some previously-known dressings attempt to manage exudate to address the foregoing issues, but provide either limited benefit and/or at a much higher perceived cost. For example, a foam dressing such as ALLEVYN® (marketed by Smith & Nephew, Largo, Fla., USA) is designed to absorb large amounts of exudate. However, use of this product is restricted to highly exuding wounds, because its highly absorptive properties can result in desiccation of wounds that are not highly exuding, thereby impeding healing. In addition, because foam used in that product cannot be conformed to the size and shape of the wound, the dressing typically overlaps with the periwound region. Consequently, exudate absorbed by the foam is transported throughout the foam and onto the periwound region, where prolonged exposure leads to maceration and degradation of the periwound region. Other previously-known dressings, such as ACQUACEL® hydrofiber dressing (available from ConvaTec, Inc., Princeton, N.J., USA) contact the wound bed, and are intended to absorb exudate and transfer and sequester the exudate in a layer disposed atop the wound. This and similar previously-known dressings do not entirely contain or absorb exudate. Moreover, like foam and other previously-known dressings, hydrofiber dressings essentially plug the wound surface, and create an osmotic environment in which the fluidic osmotic pressure within the wound bed approximates that of the surrounding tissue. Consequently, exudate is not sufficiently drawn from the wound, and its buildup in the wound may adversely affect the wound and periwound region. Furthermore, ALLEVYN®, ACQUACEL®, and similar previously-known dressings do not provide an adequate moisture vapor transfer rate (MVTR) away from the wound environment, thus creating the potential for an over-hydrated environment that hinders wound healing.
Other previously-known wound treatment systems, such as the V.A.C.® system, available from Kinetic Concepts, Inc. (San Antonio, Tex., USA), employ a mechanically operated contact-based dressing that continuously vacuums exudate from the wound bed. It and other dressings incorporating the concept of Negative Pressure Wound Therapy have proven particularly useful in healing large wounds, such as surgical wounds. However, such systems are costly, difficult to apply and time consuming. In addition, because such systems require insertion of a sponge (for the V.A.C.® system) or gauze (as commercialized by other wound care companies) directly into the wound bed, they likely cause considerable pain and discomfort for the patient, and may not be appropriate for many types of wounds.
Several previously-known dressings also have been developed that are promoted as “non-contact” dressings, which seek to prevent adhesion of the wound tissue to dressing, or to facilitate certain treatments that by their nature cannot contact the wound, e.g., thermal therapy. Such dressings are commonly formed as an inverted cup or a raised bandage that covers the wound without contacting it. Such previously-known dressings, however, also have failed to adequately heal wounds and protect the periwound region. Such non-contact dressings are provided in pre-formed shapes and sizes, and have limited deformability, thus limiting their ability to prevent exposure of the periwound skin to exudate. Additionally, the limited deformability of such previously-known dressings makes application of such dressings difficult or impossible to wounds on small surfaces or in areas with complex topology, such as the ankle or foot. Previously-known non-contact dressings also do not allow the pressure applied to the periwound region to be readily managed, and may result in the formation of pressure rings around the wound, thereby inducing ischemia in the wound and surrounding tissue. Finally, such previously-known dressings do not provide any mechanism to stimulate the flow of exudate, nor do they sequester exudate away from the wound in any appreciable volume. Such previously-known dressings also trap humidity over the wound and periwound region, leading to maceration, periwound degradation and impeded healing.IV. SUMMARY OF THE INVENTION
The present invention provides systems and methods for treatment of wounds by managing exudate and cushioning wounds from external pressure sources. The dressing of the present invention may be used for a wide range of chronic wounds, including venous ulcers, diabetic foots ulcers, pressure ulcers, and arterial ulcers. In addition, dressings constructed in accordance with the present invention may be advantageously used for surgical wounds to protect the incision site, particularly for surgical areas where skin is most vulnerable, such as split-thickness graft sites and cosmetic surgeries.
Dressings constructed in accordance with the present invention also may advantageously used to treat acute wounds and to protect the wound from further trauma, such as occurs in industrial accidents and in the battle field settings. In particular, dressings in accordance with the present invention may be applied to reduce contact pressure on the wound bed. In a battlefield setting, for example, this aspect of the invention may be particularly valuable, since a bandaged wound may still have debris or shrapnel in it, and the dressing can be applied to prevent such contaminants from being pushed further into the wound during evacuation of the wounded subject.
In accordance with one aspect of the present invention, a system is provided for managing exudate released from a wound that is surrounded by a periwound region, the system including: a support cushion that surrounds the wound and the periwound region; a wicking strip configured to be applied in the periwound region between the support cushion and the margin of the wound; and a reservoir that is disposed over the wicking strip to absorb and sequester exudate from the wicking strip. The wicking strip may include a substantially hydrophobic film on the surface that contacts the periwound region, so that exudate is absorbed through a lateral surface of the wicking strip exposed to the wound bed, but exudate entering the wicking strip does not contact or cause maceration of the periwound tissue located beneath the hydrophobic film. Preferably, the hydrophobic layer may also serve as an adhesive that adheres the wicking strip to the periwound tissue at the margin of the wound.
In some embodiments, the support cushion includes a high-profile portion configured to accommodate the reservoir; and a low-profile portion configured to suspend the reservoir over the wound. The high-profile and low-profile portions of the support cushion may be hydrophobic; the wicking strip and the reservoir may be hydrophilic; the high-profile portion may inhibit lateral flow of exudate out of the reservoir; and the low-profile portion may inhibit lateral flow of exudate out of the wicking strip. In some embodiments, the support cushion also may include a plurality of slits to enhance conformability of the cushion to complex patient topology, and to allow the transfer of moisture vapor from the skin on which the support cushion rests.
Some embodiments further may include a cover secured to the reservoir; and a biocompatible adhesive for securing the cover to the support cushion, so that the adhesive urges the reservoir into engagement with the wicking strip. The wicking strip may have a length and a height, such that the height varies along the length to modulate or provide a gradient in the pressure applied to the periwound region. A biocompatible adhesive may secure the support cushion around the wound and the periwound region; and a biocompatible adhesive may secure the wicking strip in the periwound region between the wound and the support cushion.
In some embodiments, the reservoir may include a first hydrophilic layer, a non-stretchable mesh or scrim, and a second hydrophilic layer. In other embodiments, the reservoir may include a vent or vents that control humidity over the wound. Further, the reservoir or support cushion may include a port or ports for applying negative pressure within the dressing to provide negative pressure wound therapy, or through which a lavage solution may be periodically injected and withdrawn.
In accordance with another aspect of the invention, a method for managing exudate from a wound surrounded by a periwound region is provided, and includes: surrounding the wound and the periwound region with a support cushion; applying a wicking strip in the periwound region between the support cushion and the wound; and applying a reservoir over the wicking strip, wherein the wicking strip transfers exudate from the wound to the reservoir. In some embodiments, the method includes substantially filling the periwound region between the support cushion and the wound with the wicking strip.
In other methods of the present invention, the support cushion may include a vertically profiled portion, with the method further including fitting the reservoir within the profiled portion of the support cushion to suspend the reservoir over the wound. In such embodiments, the support cushion may be hydrophobic and the wicking strip and the reservoir may be hydrophilic, or optionally a combination of hydrophobic and hydrophilic materials, the method further including inhibiting lateral flow of exudate out of the reservoir and the wicking strip.
Still other methods of the present invention are designed to stimulate exudate flow by arranging the reservoir to compress the wicking strip, thereby applying a mild pressure in the periwound region that encourages exudate to migrate out of the wound and into the wicking strip. The wicking strip also may have a length and a height that varies along the length, such that the variation in height induces a pressure gradient in the periwound region when the reservoir is urged into engagement with the wicking strip. In some methods, the pressure gradient may be induced by applying a compression wrap over the dressing. A medication may be applied to the wound before applying the reservoir.
In still other embodiments, the method further may secure a cover to the support cushion with a biocompatible adhesive so that the adhesive urges the reservoir into engagement with the wicking strip. The method may further include securing the support cushion around the wound and the periwound region with a biocompatible adhesive; and securing the wicking strip in the periwound region between the wound and the support cushion with a biocompatible adhesive.
In accordance with yet another aspect of the present invention, a kit for use in managing exudate from a wound surrounded by a periwound region is provided and includes: a support cushion for surrounding the wound and the periwound region; a wicking strip configured to be applied in the periwound region between the support cushion and the margin of the wound; a reservoir configured to be applied over, and in engagement with, the wicking strip; a backing upon which the support cushion, wicking strip, and reservoir are mounted; and printed instructions for using the support cushion, wicking strip, and reservoir on a patient.
The present invention provides systems and methods for protecting and promoting wound healing by managing exudate released by the wound. Among other things, the systems and methods provide a wound dressing that allows a wound to remain moist, while at the same time transferring excess exudate away from the wound and periwound region to a separately located reservoir. In this manner, the wound does not come into prolonged contact with excess exudate and periwound will not come in contact with any exudate, and thus both are protected from maceration or bacterial action that degrades tissue and skin. Unlike previously-known dressings, a dressing constructed in accordance with the principles of the present invention includes a reservoir that is elevated above the wound, and thus does not continuously contact the wound. This arrangement promotes wound healing by reducing the disruption of the wound bed (and pain) caused by periodic replacement of previously-known dressings, such as gauze, which adhere to the wound bed.
The systems and methods of the present invention also allow the flow of exudate from the wound to be managed by manipulating the amount and profile of pressure applied to the periwound skin, which also is expected to enhance the rate of healing of the wound.
An overview of an exemplary embodiment of a system for exudate management constructed in accordance with the principles of the present invention is first described, as well as a method of applying and using that system. Further details on the individual components employed in the system of the present invention, and alternative embodiments and methods, are described.
Overview of System
Referring now to
Support cushion 20 preferably comprises a closed cell polyolefin foam and is designed to surround wound W and periwound region P, i.e., the region of epidermis E extending from the wound margin, to protect the wound and elevate reservoir 40 and cover 50 above the wound bed. In the exemplary embodiment of
Wicking strip 30, which preferably comprises an open-cell polyurethane foam, overlays periwound region P between the margin of wound W and flange 22 of support cushion 20. In the embodiment of
Still referring to
Cover 50, preferably a breathable material, overlays reservoir 40. Layer 51 of adhesive preferably is used to removably secure reservoir 40 to cover 50. Alternatively, reservoir 40 may be removably fastened to cover 50 using a removable fastening system, such as hook and pile arrangement. In addition, layer 27 of adhesive, or a removable fastening system, is used to secure cover 50 to the upper surface of sidewall 21 of support cushion 20, so that cover 50 and/or reservoir 40 may be periodically removed from dressing 10 to inspect the wound, to apply topical medications or other substances to the wound, e.g., moisturizing ointments, growth factors, nutrients, and/or antibiotics, or to replace wicking strip 30 or reservoir 40. In other embodiments, cover 50 and/or reservoir 40 are left in place over the wound while dressing 10 is applied to the patient.
As described in greater detail below, the components of dressing 10 may each be provided with one or more non-stick liners to facilitate handling of the different components of the system, e.g., while placing support cushion 20 on epidermis E. The liners may be removed as appropriate to expose the adhesive layers and secure components to epidermis E or to each other.
Referring now to
As depicted in
Multiple features of dressing 10 both enhance the healing of wound W and protect periwound region P from maceration and degradation. Among other things, although reservoir 40 is arranged to protect the wound from the environment and absorb exudate, it is suspended over and thus is not in continuous contact with the wound. This feature may both reduce any pain experienced by the patient and promote healing. For example, initially placing reservoir 40 (and the other components of dressing 10) does not require touching the wound bed itself, resulting in significantly less pain than, for example, than the V.A.C.® or systems similar to it described above that rely on inserting a sponge or gauze directly into the wound. Wicking strip 30 and/or reservoir 40 also may readily be removed without disrupting re-epithelialization of the wound. Moreover, because reservoir 40 sequesters the exudate, when reservoir 40 is removed to observe the wound, exudate does not flow onto the adhesive used to secure cover 50 to support cushion 20. This arrangement allows wicking strip 30 and/or reservoir 40 to be replaced and for cover 50 to be re-secured to support cushion 20, without having to replace the entire dressing. By contrast, removing previously known dressings (which contact the wound) often disrupts re-epithelialization and allow exudate to flow onto the adhesive, requiring the entire wrap to be discarded and a new one applied.
It is noted that although reservoir 40 is designed to be suspended over, rather than in contact with the wound, occasions may arise where the reservoir will contact the wound. For example, if sufficient pressure is applied directly onto cover 50 and reservoir 40, the reservoir may deflect sufficiently to contact the wound for as long as that pressure is applied. Such temporary contact is not believed to significantly impede the healing of the wound, and the durometer and resiliency of support cushion 20 preferably is selected to provide adequate support for cover 50 and reservoir 40 in the expected range of applications.
Dressing 10 also encourages the flow of exudate from the wound, and thus reduces the bacterial load of the exudate in contact with the wound bed. Without wishing to be limited by theory, the inventors believe that the flow of exudate from the wound may stimulate healing. First, dressing 10 encourages exudate flow by continuously wicking exudate out of the wound, thereby providing a lower osmotic pressure at the wound than in the surrounding tissue. This osmotic pressure differential encourages exudate to flow from the surrounding tissue into the wound to attempt to equalize the osmotic pressure. In contrast, conventional dressings that directly contact the wound typically do not generate an osmotic pressure differential. In addition, because dressing 10 absorbs exudate from the wound and promotes replenishment of exudate, the bacterial load of the exudate in contact with the wound bed remains relatively low. Dressing 10 also is configured to allow a variety of different types of pressure to be applied to the periwound region, depending on the type of wound, as described in greater detail below with respect to
Additionally, dressing 10 is well-suited for use in treating pressure sores that may be acquired by patients whose skin may be damaged by, for example, continuously lying in bed without sufficient movement. Such pressure sores may occur where skin is thin, has reduced integrity, and/or where bone and skin are close together, without sufficient intervening muscle or fat. Support cushion 20 rests on regions of epidermis E that surround the wound, thus protecting the wound from the type of pressure that initially caused the wound. Support cushion 20 may be formed of a supple, easily bendable material that does not create a pressure ring around the wound. In some embodiments, support cushion 20 is formed of a polyolefin that distributes pressure, inhibiting that pressure from concentrating in one region.
Overview of Method
First, at step 61, the caregiver obtains support cushion 20, wicking strip 30, reservoir 40, and cover 50, e.g., a kit as described below with respect to
At step 63, wicking strip 30 is applied within the periwound region between the margin of the wound and support cushion 20. For example, wicking strip 30 will include a non-stick liner covering layer 31, and this liner will be removed to expose the adhesive. A first end of wicking strip 30 then is applied and adhered to a first portion of the periwound region, e.g., just overlapping the margin of the wound. The free end of the wicking strip then is spiraled around the wound, with subsequent portions of wicking strip 30 adhered to adjacent portions of the periwound region, for example, as illustrated in
At step 64, reservoir 40 and cover 50 (which is preferably pre-adhered to reservoir 40) then are applied over wicking strip 30. For example, the non-stick liner may be removed from layer 27 disposed on the upper surface of side wall 21, and reservoir 40 inserted into support cushion 20 so that the exposed adhesive on support cushion 20 adheres to cover 50, as illustrated in
At step 65, compression wrap 70 optionally is wrapped over dressing 10 to apply a desired pressure onto the dressing and wound, e.g., as illustrated in
For example, if using an elastic compression wrap to compress dressing 10 against a venous leg ulcer, the wrap may be stretched beyond a specified proportion of its native length, and then secured in that stretched configuration. The physician optionally may apply other wraps on dressing 10, such as gauze or Unna Boot or both. Such intervening layers of material also may be applied with compression, as appropriate.
Some wound sites located on broad surfaces, such as the torso, may not easily be wrapped with a compression wrap, in which case the differential heights between the support cushion, reservoir and wicking strip of dressing 10 may be adjusted to provide sufficient pressure to stimulate the flow of exudate. For example, as described herein after with respect to the embodiment of
Optionally, a medication or other substance may be applied to the wound or periwound region during any appropriate step in method 60. For example, the wound and periwound region may be cleaned, dried, and/or debrided or moisturized before applying support cushion 20 to the epidermis. Or, for example, a wound dressing such as PROMOGRAN PRISMA™ collagen and silver dressing (available from Systagenix Wound Management, London, UK), or Dermagraft® (available from Advanced BioHealing, La Jolla, Calif., USA), or Apligraf® (available from Organogenesis, Inc., Canton, Mass., USA), and other similar collagen or biological dressings, may be applied to the wound after applying wicking strip 30, but before applying reservoir 40 and cover 50. Other substances may be used, such as time-release topical medicines.
Further details of the construction of the individual components of dressing 10, and alternative embodiments, are now provided.
Support Cushion 20
In some embodiments, support cushion 20 is of unitary construction, with sidewall 21 and flange 22 being formed from different portions of the same piece of material. Alternatively, sidewall 21 and flange 22 may be individually constructed and then heat-fused or adhesively bonded together, thus allowing the materials, thicknesses, and other characteristics of sidewall 21 and flange 22 to be selected tailored for specific applications. For example, it may be preferable to form sidewall 21 using a relatively thick layer of a large-cell hydrophobic material and flange 22 using a relatively thin layer of a small-cell hydrophobic material. Such a combination of materials and thicknesses imparts support cushion 20 with sufficient flexibility to be conformable to substantially any body part, e.g., an arm, leg, neck, or torso, while maintaining a sufficient level of hydrophobicity to prevent exudate from leaking onto the periwound region. Examples of suitable hydrophobic materials for use in support cushion 20 include polyolefin, foams, and silicone-based materials, in open cell or closed cell forms. Any suitable adhesive or bonding procedure can be used to adhere sidewall 21 to flange 22.
As mentioned above, slits 28 may enhance the flexibility and breathability of support cushion 20, e.g., to allow support cushion 20 to more readily conform to various body parts and to allow humidity in the regions of the epidermis underlying support cushion 20 to escape, thus reducing maceration. Slits 28 may be simple “cuts” that extend through support cushion 20, e.g., through sidewall 21 and flange 22, without removing material. Alternatively, slits 28 may be apertures formed by removing material from sidewall 21 and/or flange 22. Slits 28 may be formed in any appropriate size, shape, density, or pattern. For example, slits 28 may extend in a single direction, as illustrated in
Alternatively, support cushion 20 of the present invention may comprises a spacer fabric, such as the polyester/nylon spacer fabric designated style DNB69, available from Apex Mills, Inward, N.Y., USA. Such materials are hydrophobic, but include an open weave that is highly breathable, thereby permitting moisture to readily evaporate from the patient's skin during prolonged use, while preventing maceration.
In the embodiment illustrated in
To accommodate such free-form embodiments of the support cushion, it may be desirable for reservoir 40 and cover 50 to have a basket-like configuration, such as described in detail below with respect to
In still other embodiments (not illustrated), support cushion 20 may be an annular structure filled with a fluid, e.g., air or water, a gel, an expanded plastic, or fibers. Such structure may be formed of molded plastic, welded polymer, or a laminate.
Wicking Strip 30
In the embodiment illustrated in
In the embodiment of
Likewise, wicking strip 30 may have a variable width along its length, as depicted in
As illustrated in FIGS. 4 and 5A-5C, the wicking strip may have a relatively even width along its length. However, the wicking strip of the present invention also may be provided in a variety of other shapes and sizes, depending on the intended application.
In still other embodiments (not illustrated), the wicking strip is pre-formed into an annular form. If the inner boundary of such an annular form does not come sufficiently close to the border of the wound to protect the periwound region, then additional pieces of wicking strip may be applied in the gap between the annular form and the margin of the wound.
As illustrated in
Referring again to
Intervening layer 43 enhances the strength and stiffness of reservoir 40, making it more difficult to inadvertently deflect reservoir 40 downward to contact the wound. Intervening layer 43 may be, for example, a substantially non-stretchable mesh or scrim, such as a metallic, nylon, or polyester-based mesh.
In some embodiments, layers 41, 42, and 43 are co-selected to enable reservoir 40 to form a dome-like shape as it absorbs exudate and swells, while still maintaining contact with ledge 23 and sidewall 21 of support cushion 20. For example, intervening layer 43 may be formed to have a larger diameter than the diameter defined by the sidewall 21 of support cushion 20. As reservoir 40 absorbs exudate and swells, this difference in diameter allows intervening layer 43 to buckle upward.
Referring now to
Cover 50 is made of a soft, occlusive material that provides an antibacterial barrier between the wound and the environment, and also allows humidity to escape from reservoir 40 and vent 44. One example of a suitable material for cover 50 is Intelicoat 2327, available from Intelicoat Technologies (South Hadley, Mass., USA). The material may be coated or intercalated with any suitable antibacterial or antimicrobial agent to combat or prevent infection.Additional Alternative Embodiments
Referring now to
Support cushion 70 and wicking strip 80 preferably include a layer of adhesive on the lower surface, similar to layer 25 in the embodiment of
In the embodiment of the invention depicted in
In the embodiment of
Support cushion 90 and wicking strip 100 preferably include a layer of adhesive on the lower surface, similar to layer 25 in the embodiment of
In the embodiment of the invention depicted in
It should be understood that the dressing of
Referring now to
In addition, because the dressing of the present invention, when assembled and applied to a patient, provides an essentially closed system (other than by permitting excess humidity to dissipate through the breathable cover), it is also possible for a dressing constructed in accordance with the present invention to be employed in negative pressure wound therapy. For example, rather than using syringe 115 in the embodiment of
With respect to
Referring now to
Support cushion 131 preferably comprises a closed cell polyolefin foam and is designed to surround wound W and periwound region P, i.e., the region of epidermis E extending from the wound margin, to protect the wound and elevate reservoir 133 and cover 134 above the wound bed. In the embodiment of
Wicking strip 132, which preferably comprises an open-cell polyurethane foam, overlays periwound region P between the margin of wound W and opening 136 of support cushion 131. In the embodiment of
Still referring to
Cover 134 is preferably a breathable material and overlays reservoir 133, and includes a layer of adhesive along the circumference of its lower surface that may be used to removably secure reservoir 133 in engagement with epidermis E and to adhere cover 133 to epidermis E. In accordance with one aspect of the present invention, cover 134 includes plurality of holes 139 that permit the reservoir and cover to be correctly aligned with the wicking strip and support cushion during application. In particular, holes 139 permit the caregiver to sight through the holes during application of the cover and reservoir to confirm proper positioning of the cover and reservoir relative to support cushion 131.
As illustrated in
Referring now to
One solution to the foregoing concern is construction for the reservoir and cover depicted in
Advantageously, cover 140 and reservoir 150 are preformed in specific sizes, e.g., small, medium and large diameters. During application of the inventive dressing to an irregularly shaped wound, the wicking strip and support cushion may be custom-fit from strip-shaped support cushion and wicking strips by wrapping the support cushion and wicking strip around the wound. A suitably sized cover 140 and reservoir 150 may then be selected from the preformed sizes such, when applied, that the outer edge of the reservoir sits atop at least the innermost rings (or spirals) of the support cushion. For example, if the wound is relatively small, the reservoir may extend to the outermost ring of the support cushion. On the other hand, if the wound is large, the reservoir may sit atop the innermost ring of the support cushion. Since for this embodiment it is not necessary to cut the outer edge of the reservoir, the gasket remains intact and prevents diffusion of exudate through the lateral edges of the reservoir. In addition, the basket provides mechanical support and protection for the reservoir against compressive loads, thus preventing exudate absorbed into the reservoir from being inadvertently released into the wound bed.
The components of a dressing constructed in accordance with the principles of the present invention, illustratively dressing 10 of
In the illustrated embodiment, foldable tabs 162 cut from backing 161 and/or pieces of excess material adhered to backing 161 may be used to secure the components of dressing 10 to backing 161 until they are needed. For example, the hole in support cushion 20 may be formed by cutting piece 163 from a layer of flange material, and then adhering that piece 163 to backing 161. Because piece 163 snugly fits into the hole of support cushion 20, the friction between piece 163 and support cushion 20 serves to removably retain support cushion 20 on backing 161 without the need for additional adhesive or tabs, until removed by the patient or caregiver. Similarly, reservoir 40 may be cut from the center of a larger piece 164 that is subsequently adhered to backing 161. Friction between reservoir 40 and piece 164 retains reservoir 40 frictionally engaged on backing 161 without the need for additional adhesive or tabs, until removed for use. Alternatively, tabs 162 may be used to secure all of the components onto backing 161.
Instructions for use 165 for applying the different components of dressing 10 to a patient may be printed on backing 161, e.g., instructions for implementing the method described with respect to
Kit 160 preferably further includes a pouch (not shown) in which backing 161 and dressing 10 are sealed until needed. Preferably, the pouch is transparent on at least its upper surface, allowing backing 161 and the other components to be viewed. Additionally, instructions for use 165 may be located on backing 161 so as to make possible reading of the instructions before opening the pouch. The pouch also may be constructed to aid retention of the components of dressing 10 on backing 161. Kit 160 preferably is sterilizable, e.g., may be sterilized after assembly, such that the contents of the pouch remain sterile until it is opened, e.g., immediately before the dressing is applied to a patient. The pouch preferably comprises a material that retains its integrity during conventional sterilizing procedures, e.g., exposure to gamma radiation, to an electron beam, or to ethylene oxide gas.
It is envisioned that a typical wound care treatment environment, such as a hospital, wound care outpatient clinic or doctor's office, may stock an inventory of kits 160 designed for use with different sizes or shapes of wounds. For example, a plurality of kits 160 may be manufactured having support cushion 20, wicking strip 30, reservoir 40, and cover 50 in a variety of sizes and shapes, according to different wound sizes and shapes with which they may be suitable for use. Alternatively, or in addition, individual components of the dressing, such as the wicking strips and reservoirs, may be individually packaged, for example to permit periodic replacement of the wicking strip or reservoir with greater frequency than the dressing as a whole. As a still further alternative, as described above, the wicking strip and support cushion may be individually packaged in a roll form, so that the dressing may be applied in a custom-fit manner, while cover and reservoir combinations, such as described above with respect to
The following commonly-owned patent publications describe additional materials and structures that may be used in various embodiments of the invention, and are each incorporated by reference herein in their entireties:
- U.S. Patent Publication No. 2006/0235347;
- U.S. Patent Publication No. 2007/0142757;
- U.S. Patent Publication No. 2007/0142761;
- U.S. Patent Publication No. 2007/0161937;
- U.S. Patent Publication No. 2007/0161938; and
- U.S. Patent Publication No. 2007/0191754.
While various illustrative embodiments of the invention are described above, it will be apparent to one skilled in the art that various changes and modifications may be made therein without departing from the invention. The appended claims are intended to cover all such changes and modifications that fall within the true spirit and scope of the invention.
1. A dressing for protecting a wound and managing exudate released from the wound, the wound having a margin and being surrounded by a periwound region, the dressing comprising:
- a support cushion configured to surround the wound and the periwound region;
- a wicking strip configured to be positioned in the periwound region between the support cushion and the margin of the wound; and
- a reservoir configured to be suspended over and in engagement with the wicking strip so that the wicking strip transfers exudate from the wound to the reservoir; and
- a cover configured to be positioned over the reservoir.
2. The dressing of claim 1, wherein the cover is configured to retain the reservoir in engagement with the wicking strip.
3. The dressing of claim 1, wherein the support cushion further comprises a sidewall and a flange, the flange defining a ledge to accept a portion of the reservoir.
4. The dressing of claim 3, wherein the support cushion comprises a hydrophobic material, the wicking strip and the reservoir comprise hydrophilic materials, and the sidewall, ledge and flange inhibit seepage of exudate out of the reservoir and wicking strip onto the periwound region.
5. The dressing of claim 1, wherein a plurality of slits are disposed in the support cushion.
6. The dressing of claim 1, further comprising a biocompatible adhesive for securing the support cushion around the periwound region.
7. The dressing of claim 1, wherein the wicking strip has a length and a height, and the height varies along the length such that engagement of the reservoir to the wicking strip induces a pressure gradient in the periwound region.
8. The dressing of claim 1, further comprising a biocompatible adhesive for securing the wicking strip in the periwound region between the margin of the wound and the support cushion.
9. The dressing of claim 1, wherein the reservoir comprises a first hydrophilic layer, a non-stretchable mesh or scrim, and a second hydrophilic layer.
10. The dressing of claim 1, wherein the cover comprises a breathable material.
11. The dressing of claim 10, wherein a vent is defined in the reservoir, the vent permitting humidity over the wound to escape.
12. The dressing of claim 1, wherein the reservoir further comprises a gasket disposed on its lateral face.
13. The dressing of claim 1, wherein the cover further comprises a basket configured to accept the reservoir.
14. The dressing of claim 1, wherein the wicking strip further comprises a spiral perforation that enable removal of a portion of the wicking strip to expose the margin of the wound.
15. The dressing of claim 1, wherein the wicking strip further comprises a plurality of circumferential and radially-directed perforations that enable removal of selected arcs of the wicking strip to approximate irregularities in the margin of the wound.
16. The dressing of claim 1, wherein the support cushion further comprises a tube that enables fluids to be injected into the dressing without removing the reservoir or cover.
17. The dressing of claim 1, wherein the cover further comprises a bellows configured to be depressed to periodically induce a negative pressure within the dressing.
18. The dressing of claim 1 wherein the support cushion comprises a spacer fabric.
19. A method for protecting a wound and managing exudate released from the wound, the wound having a margin surrounded by a periwound region, the method comprising:
- surrounding the wound and the periwound region with a support cushion;
- applying a wicking strip in the periwound region between the support cushion and the margin of the wound; and
- applying a reservoir over the wicking strip,
- wherein the wicking strip transfers exudate from the wound to the reservoir.
20. The method of claim 19, further comprising substantially filling the periwound region between the support cushion and the margin of the wound with the wicking strip.
21. The method of claim 18, wherein the support cushion includes a stepped profile that defines a ledge and a recess, the method further comprising fitting the reservoir within the recess so that the reservoir engages the ledge and is suspended over the wound.
22. The method of claim 21, wherein the support cushion comprises a hydrophobic material and the wicking strip and the reservoir comprise hydrophilic materials, the method further comprising inhibiting lateral flow of exudate out of the reservoir or the wicking strip onto the periwound region.
23. The method of claim 19, further complying stimulating exudate flow by urging the reservoir into engagement with the wicking strip to induce pressure in the periwound region.
24. The method of claim 23, wherein the wicking strip has a length and a height and the height varies along the length, and wherein the method further comprises applying the wicking strip in the periwound region to induce a pressure gradient in the periwound region when the reservoir is engaged to the wicking strip.
25. The method of claim 22, wherein urging the reservoir into engagement with the wicking strip further comprises applying a compression wrap over the dressing.
26. The method of claim 19, further comprising applying a medication to the wound before applying the reservoir.
27. The method of claim 19, further comprising securing a cover to the support cushion with a biocompatible adhesive.
28. The method of claim 27, further comprising:
- securing the support cushion around the wound and the periwound region with a biocompatible adhesive; and
- securing the wicking strip in the periwound region between the margin of the wound and the support cushion with a biocompatible adhesive.
29. A kit for a dressing for use in protecting a wound and managing exudate released from the wound, the wound having a margin surrounded by a periwound region, the kit comprising:
- a support cushion configured to surround the wound and the periwound region;
- a wicking strip configured for application in the periwound region between the support cushion and the margin of the wound;
- a reservoir configured to be applied over the wicking strip;
- a backing upon which the support cushion, wicking strip, and reservoir are mounted; and
- instructions for use printed on the backing, the instructions for use describing steps for assembling the dressing.
International Classification: A61F 13/02 (20060101); A61F 13/00 (20060101);