The most common failures of a temporary or permanent skin substitute are thought to be lack of early adherence and infection. AWBAT® is a porous silicone-nylon membrane utilizing porcine Type 1 collagen peptides. It is designed to acutely adhere to the wound by using collagen peptides that are not crosslinked to the silicone-nylon membrane. Without steric hindrance, it is expected to enable a quick collagen-fibrin interaction to achieve clotting and acute adherence within the three-dimensional nylon structure. AWBAT®’s increased porosity is expected to reduce the potential for fluid accumulation beneath the dressing and minimize associated fluid pressure that might force the skin substitute from the wound bed, thus also improving acute adherence capabilities.

Utilizing "State-of-the-Art" proprietary technology, AWBAT® has precise hole sizes and numbers of pores to provide what we believe is an optimal balance of porosity and occlusiveness. These properties are intended to minimize fluid accumulation beneath the skin substitute, thereby minimizing the possibility of proliferation of bacteria endogenous to the wound, which would increase healing rates. The increased porosity also allows for better transfer of water soluble antimicrobials through the skin substitute and into the wound. The design of AWBAT® is patent protected (Patent Pending # 12049321).

A moist wound environment (4, 14) is very important to maximize wound healing and minimize infection complications; however, fluid accumulation beneath a skin substitute can compromise adherence and provide a site for endogenous bacteria to proliferate. Therefore, it is important that a dressing simultaneously allow moisture retention, gaseous transfer, and exudate drainage. This is accomplished through a precision silicone membrane design.

Gases, such as oxygen, carbon dioxide and water vapor, diffuse through solid yet thin silicone membranes, which have been successfully used as membrane oxygenators (15). The thickness of the silicone membrane for successful transfer of gases, per the Lande-Edwards Membrane Oxygenator, is 0.001 inch or less. Both Biobrane® (9) and AWBAT® have this similar silicone thickness, allowing for gaseous transmission while maintaining the ability to control water vapor loss.

While a solid silicone membrane is necessary to control water vapor loss, in order to minimize fluid accumulation beneath a skin substitute and allow for exudate removal wound dressings need to be porous. Biobrane® was designed and is manufactured with holes of approximately 1.5 mm diameter punctured through the silicone-nylon membrane at approximately 0.5 inch centers. While this allows for some drainage, complications of fluid accumulation beneath the dressing, leading to suppuration requiring "windowing" and antimicrobial intervention, have been reported (16). The patent-pending design of AWBAT® creates pores in the silicone membrane without damaging or disrupting the three-dimensional nylon structure. It is believed that a continuous nylon structure over the entire wound surface will better enable tissue ingrowth and uniform healing with minimal scarring. The pores in AWBAT® are spaced and sized in a fashion to increase the porosity 500% to 1000% over Biobrane®, with the intent to further minimize fluid accumulation beneath the skin substitute and the associated complications.

The best initial defenses against infection of a superficial partial thickness wound are: the proper preparation of the wound and a wound covering that sufficiently acts as a bacterial barrier, which the thickness of the silicone membrane in AWBAT® provides.

It is believed that when dressings such as these are applied to clean, surgically debrided or excised hemostatic wounds, antimicrobial impregnation is not commonly necessary.

Some clinicians have recently looked to antimicrobial activity as a safeguard against infection, and many recently developed dressings contain silver ion as an antimicrobial agent. While Biobrane®, at approximately 1.2% porosity, was not designed specifically to address the potential desire for antimicrobial permeability, AWBAT® is more accommodating. AWBAT®-S, designed with 6% porosity, is 500% more permeable to water-soluble antimicrobials such as Sulfamylon®. AWBAT®-D and AWBAT®-M, with 12% porosity, are 1000% more permeable. Diffusion of antimicrobials is directly related to the concentration gradient of the antimicrobial across the skin substitute and the skin substitute’s porosity. The ability to treat endogenous microbes without removal of the skin substitute by diffusing antimicrobials through the skin substitute is highly desirable. It is believed that use of a water-soluble antimicrobial over AWBAT® in "borderline" contaminated wounds could control the proliferation of endogenous bacteria without necessitating removal of the dressing.

Stretchability, flexibility and conformability of a skin substitute are important to the clinician, particularly when the wound is irregularly contoured. The stretchability and flexibility of the dressing is not only critically important during application over joints but also critically important during rehabilitation when movement is desired. The nylon component and the thinness of the silicone membrane in AWBAT® allows for these properties. Many wound dressings lacking these qualities become stiff, inflexible, or "cast-like," and other dressings can shrink or become degraded by wound proteases.

Some wound coverings have been known to use glutaradehyde and other cross-linking agents such as cyanuric chloride and dodecylamine. AWBAT® is manufactured with no cross-linking agents.

Dressings should be sterile, hypoallergenic, nontoxic and nonpyrogenic. Some skin substitutes, such as fresh and frozen allograft, cannot guarantee sterility. Cadaver allograft has the potential to transmit AIDS and hepatitis. As both glutaraldehyde and formaldehyde are useful as sterilizing agents and reduce the antigenicity of biological tissues (19), porcine xenograft has been treated with glutaraldehyde to improve its shelf life and sterility safety margins; however, in the crosslinking process the physical properties of the product, such as adherence, have been compromised. Biobrane® has proven to be safe, with the exception of rare allergic reactions (20).

Production of AWBAT® is controlled to maximize safety and sterility (Table 2), including collagen application methods that eliminate the crosslinking agents used with Biobrane®, cyanuric acid and dodecylamine.

Occlusive dressings that appropriately cover exposed nerve endings and provide moist wound healing environments characteristically reduce pain. Elimination or reduction of dressing changes are also significant benefits to pain management. AWBAT® is a semi-occlusive temporary skin substitute, designed to remain in place for the life of the wound, and is expected to reduce pain, provide patient comfort, and enable quicker rehabilitation and ambulation.

AWBAT® is transparent to allow the clinician to observe the healing process at the wound surface. The ability to detect suppuration and implement immediate corrective action such as antimicrobial therapy is a distinct advantage over products lacking transparency.

AWBAT® is designed to be sterile and stable at room temperature for three years in an unaltered package.

The ultimate cost of any skin substitute includes not only the product but also the length and complexity of patient care, including the expenses of dressing changes, complications, and hospital stay. AWBAT® is designed to remain in place on superficial burns, donor sites and meshed autografts for the life of the wound.

The ability to easily secure a skin substitute with staples, sutures or steri-strips, and the ability to easily remove it in whole pieces when necessary, is desirable. AWBAT® has a stretchable, conformable silicone-nylon component that can be easily attached by the clinician. The silicone-nylon membrane also has sufficient strength to enable removal without tearing.

AWBAT® consists of a thin medical-grade silicone membrane approximately 0.001", which is physically bonded to one of two types of finely-knitted nylon fabric, which are then bonded with collagen peptides. AWBAT® can be fabricated into gloves. It has a long shelf shelf life at room temperature.

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Products with properties of a skin substitute containing xenogenic components (collagen, chondrotin sulfate, hyaluronic acid, growth factors, etc.) or cells (fibroblast, epidermal - living or dead). Current examples are TransCyte®, Biobrane®, Integra®, and other sophisticated wound dressing products.

AWBAT® does not contain any antimicrobial agent. It is designed to be applied to completely debrided hemostatically secure wounds. In those circumstances, AWBAT® is intended to adhere to the wound, prevent desiccation, and provide a moist environment that facilitates healing.

AWBAT® is a porous wound dressing and is designed to be able to be used in combination with water soluble antimicrobials.

The design of AWBAT®'s porosity intends to limit the potential for fluid or purulence accumulation beneath the membrane. If there is a situation of fluid accumulation, and if the area is very limited, incision of the AWBAT® directly over the area of fluid accumulation/purulence and removal of the contents by gently rolling toward the incision may be performed, leaving the adherent AWBAT® undisturbed. If a large area is involved and the AWBAT® is non-adherent, it should be completely removed and appropriate wound care instituted. Re-application of AWBAT® is based on clinical judgment, but will not be successful on contaminated or infected wounds.