The invention relates to a device and method for treating wounds. More specifically, the present invention relates to a therapeutic wound contact device.
Wound healing is a basic reparative process of the human body. It has been known throughout time that dressing wounds with appropriate materials aids the body's natural regenerative process. Historically, such materials have been made from cotton fibers; e.g. gauze. These dressings are beneficial to the healing process because they insulate damaged tissue from external contaminants and because they remove potentially deleterious wound exudates.
Numerous studies suggest that wound healing depends on the interplay of complex mechanisms involving cell proliferation, migration and adhesion coupled with angiogenesis. Application of traditional gauze or other essentially flat materials are essentially sub-optimal with respect to these mechanisms. Wound healing studies In-vitro carried out in cell culture vehicles that permit cellular function. It is therefore desirable in the practice of wound healing to provide the equivalent of cell culture or a bioreactor system to allow the optimal interplay of cell functions of proliferation, migration and adhesion. Additionally, it is essential to incorporate other bodily functions that encourage the supply of fibronectins, plasma proteins, oxygen, platelets, growth factors, immunochemicals and so forth.
As science and medicine have advanced, the technology incorporated into wound healing devices has improved substantially. Highly absorbent wound dressings capable of absorbing many times their weight in liquids are available. Systems that temporarily seal wounds and utilize suction to remove exudates have found widespread utilization. Dressings incorporating anti-microbial agents and biologic healing agents are common. Devices that provide a moist wound environment for improved healing have been found to be useful.
In spite of the technological gains in wound healing devices and dressings, millions of people still suffer from the chronic wounds. Such chronic wounds are debilitating and can last for years, greatly diminishing the individual's quality of life. Often such wounds result in the loss of a limb. Individuals may even die from complications such as infection.
As such, there is dire need for more effective wound healing devices and methods.
To provide for improved wound healing, the present invention is a wound contact material, a method for making the wound contact material, and a method of treatment employing the wound contact material.
According to an exemplary embodiment of the present invention, a therapeutic device for promoting the healing of a wound in a mammal is provided. The device comprises a permeable substrate or structure having a plurality of depressions formed in a surface thereof, wherein said surface having said depressions is disposed in surface contact with the wound.
According to a further exemplary embodiment of the present invention, a therapeutic device for promoting the healing of a wound in a mammal is provided. The device comprises a permeable structure having a plurality of wound surface contact elements disposed between end portions of the structure, and a plurality of voids defined by the contact elements.
According to an additional exemplary embodiment of the present invention, a therapeutic device for promoting the healing of a wound in a mammal, the device comprising a permeable structure comprising a plurality of fibers coupled to one another having a plurality of wound surface contact elements disposed between end portions of the structure and a plurality of voids defined by the contact elements is provided.
According to a yet further exemplary embodiment of the present invention, a therapeutic device for promoting the healing of a wound in a mammal, the device comprising a polyester felt having a plurality of wound surface contact elements disposed between end portions of the structure and a plurality of voids defined by the contact elements is provided.
According to an additional exemplary embodiment of the present invention, a method of manufacturing a therapeutic device for promoting the healing of a wound in a mammal comprises the steps of providing a molten substrate material providing a mold defining a plurality of depressions and a plurality of contact elements and applying the molten substrate material to the mold.
According to an even further exemplary embodiment of the present invention, a method of manufacturing a therapeutic device for promoting the healing of a wound in a mammal comprises the steps of providing a permeable structure and forming a plurality of depressions into a surface of the permeable structure.
According to another exemplary embodiment of the present invention, a method of treating a wound comprises the steps of providing a permeable structure comprising i) a plurality of wound surface contact elements disposed between end portions of the structure, and ii) a plurality of voids defined by the contact elements, and applying the permeable structure to at least one surface of the wound and applying a force to the structure to maintain the structure in intimate contact with the wound surface.
These and other aspects and objects will become apparent from the following description.
The invention is best understood from the following detailed description when read in connection with the accompanying drawings. It is emphasized that, according to common practice, the various features of the drawings are not to scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity. Included in the drawings are the following Figures:
A wound dressing with a discontinuous contact layer surface has the advantages of promoting tissue growth with wound surface contact elements and permitting tissue growth by providing void volume for the subsequent tissue growth within the discontinuities. Desirably, the structure of the contact material is sufficiently physically rugged to resist flattening when forces required to press the material against the wound surface are applied to the material.
It is desirable for the material to retain its structure when exposed to aqueous or other bodily fluids. Many traditional dressing materials soften as then moisten so that their geometry changes. The contact layer is permeable, permitting the underlying wound to breathe and allowing for fluids to be drawn from the wound. The contact layer should not be too absorbent as this might result in a loss of structure. The layer is comprised of base materials that are resistant to change in the presence of moisture and aqueous liquids.
In the current embodiment, the extent of the voids remaining above the wound surface is preferably at least 0.1 mm when the structure is pressed against the surface of the wound. The width of the voids, as defined by contact elements adjacent the voids, is preferably greater than 0.1 mm. A more preferred width is between about 0.5 to 10 mm and a more preferred height is between about 0.2 to 5 mm.
Wound healing is recognized as a complex process. When a wound contact material as described is forced against a wound surface, a number of biological processes are believed to occur. Mechanical stress is applied to the underlying tissue. The discontinuities in the contact surface impose a force resulting in a catenary shape on the tissue. These mechanical forces encourage cellular activities as well as angiogenesis, and the discontinuities begin to fill with granular tissue. Excess fluid is conveyed away from the wound and tissue develops in a manner and pattern whereby disruption of the newly developed tissue is minimized upon removal of the contact surface.
A fibrous substrate or structure has all the flexibilities provided by the textile arts. Fibrous textiles can be formed into a structure for the invention by a number of the methods known in the art. Among these methods are knitting, weaving, embroidering, braiding, felting, spunbonding, meltblowing, and meltspinning. Each of these methods can be further adapted to produce a material whose structure matches that of the present invention. The desired structure can be imparted during production of the structure by, for example, applying molten material directly to a mold as in meltblowing. Alternatively, the structure can be formed by working a formed structure after production by, for example, heat stamping or vacuum forming. Further, fibers can be mixed with an adhesive and sprayed onto a textured surface.
The versatility of fibrous textiles also extends to their easy adaptation to composite applications. Individual fiber materials may be varied to optimize a physical parameter such as rigidity or flexibility. Individual fiber materials can also be selected for their known ability to assist in wound healing. Examples of such fiber materials are calcium alginate, and collagen. Alternatively, fibers may be treated with known wound healing agents such as hyaluronic acid and antimicrobial silver. The ratio of the fiber materials can be varied to suit the requirements of the wound. According to one desirable aspect of the invention, different fibers with various wound healing properties may be added as desired.
Other fibrous structures that are anticipated as beneficial additions include:
1. Fluid absorbing fibers
2. Non-adsorbent fibers
3. Bio-absorbable fibers
4. Wicking fibers to wick fluid away from the surface of the wound
5. Fibers with known healing effects, such as calcium alginate
6. Bio-erodable fibers for the controlled release of curative agent
7. Conductive fibers for the delivery of an electric charge or current
8. Adherent fibers for the selective removal of undesirable tissues, substances or microorganisms
9. Non-adherent fibers for the protection of delicate tissue
An exemplary embodiment of the present invention is illustrated in
Another desirable embodiment of the present invention is illustrated in
Dimple voids 330 can be formed in a variety of regular or irregular shapes. Preferably, dimple voids are constructed so that they are not “undercut” such that each aperture circumference is smaller than the corresponding inner void circumference. An “undercut” or reticulated void structure can cause tissue disruption when the dressing 300 is removed because any tissue that has grown into the void may be torn away when the material is removed from the wound. Additionally, undercut or reticulated void structures are more likely to result in shedding of the dressing material into the newly developing wound tissue.
In one preferred embodiment, a base material for dressing 300 is Masterflo® manufactured by BBA group of Wakefield, Mass. In this exemplary embodiment, the base material has a thickness of about 1.0 mm. Dimple voids 330 are heat stamped into the base material having a depth of about 0.75 mm and a diameter of about 2 mm.
Because the contact layer is generally replaced every few days it is important to account for the possibility of alignment of newly formed tissue with the voids of a new contact layer. Thus, according to exemplary embodiments of the present invention 1) dimple voids 300 can be arranged randomly so that they don't line up with the new tissue growth after each dressing change, 2) different contact layers with different diameter dimples may be provided, or 3) a different spacing of the dimples can be used every time the material is changed.
In one exemplary embodiment, dimple voids 330 can be partially filled with therapeutic substances. For example, antiseptic substances might be placed in voids 330 for treating infected wounds. Further, biologic healing agents could be delivered in the voids to improve the rate of new tissue formation. In yet another exemplary embodiment, the layer of dressing 300 could have a different function on each side. For example, one side of dressing 300 could be optimized for the growth of new tissue, while the other side could be optimized for the delivery of anti-microbial agents, for example.
Use of dimpled dressing 300 is illustrated by
After adequate removal of the necrotic tissue, the wound may still be considered infected and can be treated with the substrate including antimicrobial silver, for example, which is useful in killing bacteria, while the substrate and method of use facilitate the growth of new tissue.
The phase of wound healing where new tissue is forming is generally referred to as the proliferative phase. Once the wound is adequately healed in the proliferative phase and the bacterial load is adequately reduced, a substrate without antimicrobial silver and optionally with the addition of growth enhancing materials is used to facilitate the continued proliferation of new cells and tissue.
As described above, treatment with the present wound dressing invention comprises forcing the inventive dressing into intimate contact with the wound surface. Generally the force should be at least 0.1 psi. Various methods and systems for maintaining this intimate contact are contemplated. These methods and systems may include: applying an adhesive film over the inventive dressing and adjacent the wound surface; wrapping a bandage over the dressing and around the injured area; and securing a balloon or another inflatable bladder to the structure and inflating the bladder with air or a liquid. In one exemplary embodiment, the application of pressure to the bladder is provided intermittently. A conformable seal may be placed over the wound and contact structure, a rigid seal is then secured over the wound, contact structure imparting a force on the contact structure. A pressure is then applied between the rigid seal and the flexible seal forcing the contact structure against the wound surface. The intimate contact may be augmented by sealing the wound area with a conformable cover and applying suction. When suction is used, dimpled wound dressing 300 is particularly well-adapted for this application. In general the range of suction levels is between 0.25 psi and 5 psi. The suction use can be further improved by applying a wound packaging material to the back of the dressing. One such suitable wound packaging material is described in U.S. Provisional Patent Application No. 60/554,158, filed on Mar. 18, 2004.
The depressions 604 remain intact even when the device is placed in a wound and suction is applied. Additionally, where the material of the device is comprised of generally non-absorbent fibers, the material does not get soggy when in a wet wound. This allows the wound fluids to be pulled out of the wound by suction, for example, and additionally ensures that depressions 604 remain. It is critical that the depressions remain, so that voids exist where new tissue can grow filling the wound cavity.
While the above described configuration uses depressions having a dimpled shape, other 3 dimensional structures can be fabricated such that there is a void for tissue to grow in to. One such non-limiting alternative configuration would be a woven waffle pattern.
Case Study 1
Patient A is a 70 year old male with a Stage IV decubitus ulcer on the right hip with significant undermining. The contact structure of the present invention was applied to the wound and an adhesive film was placed over the wound and the contact structure. A suction of 1.1 psi was applied beneath the adhesive film to impart a force upon the contact structure. The suction was maintained generally continuously. The contact material was replaced every two to four days. After use of the device for 30 days the undermined portion of the wound had virtually healed and the area of the wound opening had decreased from 66 square cm to 45 square cm. A split thickness skin graft was applied to the wound.
Case Study 2
Patient B is a 50 year old male with a fracture of the right ankle with exposed bone. A plate was used to reduce the fracture and a rectus abdominus free flap was performed to cover the exposed bone and hardware. The flap only partially survived resulting in an open wound with exposed bone and hardware. The contact structure of the present invention was applied to the wound and an adhesive film was placed over the wound and the contact structure. A force was applied to the contact structure by the application of an ace bandage wrapped around the ankle or by the application of suction. The suction force was generally applied for about half of the day and the force of the bandage wrap was maintained for the remainder of the day. For a number of days, the bandage wrap was solely used to impart the force. When the force was imparted by suction a suction of between 1 and 2 psi was used. In less than 2 weeks new tissue had grown over the exposed hardware. In a period of 7 weeks the wound area was reduced from 50 square cm to 28 square cm.
While preferred embodiments of the invention have been shown and described herein, it will be understood that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions will occur to those skilled in the art without departing from the spirit of the invention. Accordingly, it is intended that the appended claims cover all such variations as fall within the spirit and scope of the invention.
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