Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Biocides; animal or insect repellents or attractants
Utility Patent
1998-08-20
2001-01-02
Clardy, S. Mark (Department: 1616)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Biocides; animal or insect repellents or attractants
C424S402000, C424S409000, C424S443000, C424S445000, C424S446000
Utility Patent
active
06168800
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to a medical dressing and more specifically to a multi-layer island dressing which directly contacts a wound with a broad spectrum antimicrobial agent.
BACKGROUND OF INVENTION
During wound healing, a properly designed and applied dressing can be of tremendous benefit in promoting healing and ensuring comfort. However, if a wound is contaminated with microorganisms such as bacteria or fungi, the natural healing process may be greatly reduced.
The natural healing process includes an inflammatory response wherein wound exudate containing neutrophils and monocytes emigrates into injured tissue. Neutrophil infiltration usually ceases within a few days if wound contamination has not occurred. However, substantial wound contamination will provoke a persistent neutrophil-rich inflammatory response. Additional neutrophils will be attracted to such contaminated wounds to cleanse the wounded area. If excessive microorganisms have lodged in the wound bed, neutrophils may cause further tissue damage by attempting to clear the contaminants with the release of enzymes and toxic oxygen products. As such, it is beneficial to apply an antimicrobial agent to the wound site to minimize neutrophil infiltration.
Heretofore, several methods have been used in wound management including, directly applying antimicrobial agents in a carrier ointment or the ingesting of systemic antibiotics. Systemic antibiotics do not necessarily treat the wound itself, but they prevent the spread of infection. It should be noted that in a contaminated wound blood-borne antibiotics are of limited value because tissues that are dead and without a blood supply are inaccessible to systemic antimicrobials. Even viable areas of localized infection are soon walled off from surrounding tissues and therefore are not treatable with ingested antibiotics.
It is known that ointments containing an antimicrobial agent in a liquid or white petrolatum vehicle may be effective in preventing infection when spread directly on the wound. However, these ointments are very greasy and remnants of the ointment may stay in the wound bed thereby slowing the healing process.
Several medical dressings have been proposed which provide an absorbent layer incorporating an antimicrobial agent therein. The absorbent material collects the increased exudate from a contaminated wound site while inhibiting growth of bacteria that may be washed from the wound site into the absorbent material. However, in these dressings the absorbent material is not in direct contact with the wound site. For example, U.S. Pat. Nos. 5,106,362 and 5,167,613 propose dressings with the incorporation of an antimicrobial agent into an absorbent material, but these dressings are only effective on that bacteria which is physically washed into the absorbent material.
If bacteria growth is not inhibited the inflammatory response will continue and in some dressings the absorbent material inserts are unable to accommodate the excess fluids. When this occurs excess exudate is allowed to seep back to the wound bed with no defense for inhibiting the growth of bacteria. The inability to retain excess fluid may be exhibited in the dressing described in U.S. Pat. No. 4,499,896.
U.S. Pat. No 3,929,135 discloses an absorptive structure having a polymeric film comprising tapered capillaries which allow fluid to flow through the capillaries but reduce backflow seepage of exudate to the wound site. This one-way porous film may help contain the excess exudate but does not provide any antimicrobial defenses in a contaminated wound.
U.S. Pat. No. 4,728,323 discloses a substrate coated with an antimicrobially effective film of silver salt, but does not provide absorbent means for excess wound exudate that usually occurs in an infected or contaminated wound. Similarly, U.S. Pat. Nos. 5,614,310 and 4,643,180 provide for dressings having an antimicrobial agent dispersed in an adhesive material which is coated on another surface but these dressings may leave a residue in the wound that inhibits the healing process.
U.S. Pat. Nos. 4,341,207 and 4,997,425 disclose dressings which apply an absorbent material directly to the wound wherein the absorbent material incorporates an antimicrobial agent. However, the possibility of absorbent materials adhering to the healing tissue during scab formation detracts from using these dressings. When the dressing is removed, the healing process may be hindered by causing a reinjury which may produce a larger and unsightly scar.
U.S. Pat. No. 5,681,579 describes a dressing having an antimicrobial agent mixed in with a hydrocolloid material which may be subsequently incorporated into a polymer film or coated on a polymeric surface. However, there is the acknowledged disadvantage of using hydrocolloids, that being they are known to breakdown and may even produce a residue of varying colors and/or a possible foul odor. These adverse results could be confused with an infectious process or more important hide a serious wound infection.
Accordingly, what is needed is a wound dressing that contacts the wound site directly with an antimicrobial agent without leaving residue from foreign material such as adhesive or absorbent material in the wound bed, provides an absorbent material to collect exudate discharge from the wound which does not directly contact the wound surface, prevents backflow of exudate from the absorbent material to the wound bed, and provides a waterproof/bacteria barrier to protect the wound from external contaminants.
SUMMARY OF INVENTION
Terms
For purposes of this invention, the terms and expressions below, appearing in the specifications and claims, are intended to have the following meanings:
“Wound” as used herein means a surgical incision, laceration or any other injury that needs to be protected by the present invention.
“Semipermeable film” as used herein means a film that is permeable to water vapor and oxygen but is impermeable to liquids and bacteria.
“Exudate” as used herein means fluid, cells or other substances that have been slowly exuded, or discharged, from cells or blood vessels through small pores or breaks in cell membranes.
The present invention meets the aforementioned needs by providing an interactive island dressing that optimizes the healing environment by introducing an antimicrobial agent that directly contacts the wound bed, will not mask a serious wound infection or leave residue from foreign materials such as adhesive or absorbent material in the wound bed. In addition this interactive dressing provides for a continuous second layer which prevents contamination from exterior sources such as liquids or bacteria but still allows for offgasing of wound healing gases and water vapor. The first and second layer are joined to form a fluid reservoir wherein an absorbent material insert is positioned and sealed therein to accommodate excess wound exudate. The absorbent material is maintained away from direct contact with the wound. The interactive island dressing is secured to the wound area by an outer layer having a bottom surface coated with adhesive on at least opposing peripheral margins extending beyond the absorbent assembly.
It is a further object of the present invention to provide a non-absorbent, non-adhering porous polymeric film which is impregnated with an antimicrobial agent wherein the antimicrobial agent is incorporated directly into the polymer's molecular structure and will not wash or wear off, in contrast to a surface coating of antimicrobial agent.
It is still a further object of the present invention to provide a first layer comprising a non-absorbent, non-adhering one-way porous polymeric film having a plurality of tapered protuberances. The one-way porous polymeric first layer is joined to a second layer to form a sealed fluid reservoir compartment having an absorbent material therein. The one-way pores have a generally funnel-like configuration and they narrow and extend in the direction of the interior of the fluid reservoir. This configuration allows wound
Dobos John A.
Mabry Ronald D.
Clardy S. Mark
Ellis Howard M.
Fuierer Marianne
Medwrap Corporation
Shelborne Kathryne E.
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