U.S. patent application number 12/047910 was filed with the patent office on 2009-09-17 for vacuum wound therapy wound dressing with variable performance zones.
This patent application is currently assigned to TYCO HEALTHCARE GROUP LP. Invention is credited to Ronald F. Vitaris.
Application Number | 20090234306 12/047910 |
Document ID | / |
Family ID | 40810299 |
Filed Date | 2009-09-17 |
United States Patent
Application |
20090234306 |
Kind Code |
A1 |
Vitaris; Ronald F. |
September 17, 2009 |
VACUUM WOUND THERAPY WOUND DRESSING WITH VARIABLE PERFORMANCE
ZONES
Abstract
A dressing for an open wound includes a cover layer dimensioned
for positioning relative to a wound bed. The cover layer permits an
evacuation of the space around the wound bed such that a
sub-atmospheric pressure may be established to stimulate healing
and facilitate the removal of fluid from the wound. Multiple
performance zones in the cover layer allow the wound dressing to
remain in position through repeated cycles of evacuation without
placing undue strain on the wound bed. An outer peripheral zone may
include a high peal-strength adhesive while an intermediate zone
may include a shear resistant adhesive. A central zone may be
devoid of any coating to maximize moisture transmission through
cover layer.
Inventors: |
Vitaris; Ronald F.;
(Worcester, MA) |
Correspondence
Address: |
Tyco Healthcare Group LP;d/b/a Covidien
15 Hampshire Street
Mansfield
MA
02048
US
|
Assignee: |
TYCO HEALTHCARE GROUP LP
Mansfield
MA
|
Family ID: |
40810299 |
Appl. No.: |
12/047910 |
Filed: |
March 13, 2008 |
Current U.S.
Class: |
604/304 ; 602/48;
604/313; 604/543 |
Current CPC
Class: |
A61F 13/025 20130101;
A61F 2013/00217 20130101; A61F 2013/0054 20130101; A61F 2013/00174
20130101; A61F 2013/00902 20130101; A61F 13/0253 20130101; A61F
2013/00646 20130101; A61F 2013/00263 20130101; A61F 13/0243
20130101; A61F 2013/00246 20130101; A61F 2013/00855 20130101; A61F
13/0206 20130101; A61F 13/00068 20130101; A61F 13/0226 20130101;
A61F 13/00063 20130101; A61F 2013/00536 20130101; A61F 13/0256
20130101; A61F 13/022 20130101; A61F 2013/00804 20130101; A61F
13/0213 20130101; A61F 13/0216 20130101; A61F 2013/00285
20130101 |
Class at
Publication: |
604/304 ; 602/48;
604/543; 604/313 |
International
Class: |
A61M 27/00 20060101
A61M027/00; A61F 15/00 20060101 A61F015/00; A61M 35/00 20060101
A61M035/00; A61F 13/02 20060101 A61F013/02 |
Claims
1. A cover layer for a wound dressing for use in vacuum wound
therapy, the cover layer comprising: a central zone defined by a
portion of a moisture vapor permeable membrane devoid of any
coating deterring the transmission of moisture through the
membrane; a peripheral zone substantially surrounding the central
zone, the peripheral zone adapted to provide a seal around a
perimeter of a wound bed; and at least one intermediate zone at
least partially disposed between the central zone and the
peripheral zone, the at least one intermediate zone comprising a
substance for imparting a therapeutic effect to the wound bed.
2. The cover layer according to claim 1, wherein the peripheral
zone includes a high peal-strength adhesive.
3. The cover layer according to claim 1, wherein the at least one
intermediate zone comprises a first intermediate zone including a
shear-resistant adhesive
4. The cover layer according to claim 3, wherein the at least one
intermediate zone further comprises a second intermediate zone
including a medicament delivery coating.
5. The cover layer according to claim 3, wherein the at least one
intermediate zone further comprises a second intermediate zone
including a hydrogel.
6. The cover layer according to claim 3, wherein the at least one
intermediate zone further comprises a second intermediate zone
including at least one of an anti-infective agent, an
antimicrobial, antibiotic, analgesic, healing factor, vitamins,
growth factors, debridement agents, or nutrients.
7. The cover layer according to claim 1, wherein the moisture vapor
permeable membrane extends to a periphery of the cover layer to
constitute a backing layer, the peripheral zone defined by a layer
of adhesive bonded to the backing layer.
8. The cover layer according to claim 1, wherein the peripheral
zone and the at least one intermediate zone are arranged
concentrically with respect to the central zone.
9. The cover layer according to claim 1, further comprising a port
for permitting access to a vacuum reservoir defined under the cover
layer for a vacuum tube.
10. A wound dressing apparatus for use in a vacuum wound therapy
procedure, which comprises: a contact layer adapted for positioning
adjacent a wound bed; an absorbent filler positioned adjacent the
contact layer within the wound bed for collecting liquids exuding
from the wound bed; a cover layer positioned over the wound bed
defining a vacuum reservoir there between and permitting access of
a vacuum tube to the vacuum reservoir, the cover layer comprising a
peripheral zone to provide a seal around the wound bed, at least
one intermediate zone for imparting a therapeutic effect to the
wound bed, and a central zone formed from a moisture vapor
permeable membrane.
11. The wound dressing apparatus according to claim 10, wherein the
contact layer is formed from a conical apertured film.
12. The wound dressing apparatus according to claim 10, wherein the
absorbent filler material comprises polyolefin filaments arranged
in a multi-strand bundle.
13. The wound dressing apparatus according to claim 10, further
comprising a vacuum system in fluid communication with the vacuum
reservoir.
14. The wound dressing apparatus according to claim 13, wherein the
vacuum system includes a vacuum source, a collection canister and a
one-way valve.
Description
BACKGROUND
[0001] 1. Technical Field
[0002] The present disclosure relates generally to a wound dressing
for treating an open wound with a vacuum wound therapy treatment.
In particular, the disclosure relates to a dressing having a cover
layer employing a plurality of zones of variable performance
characteristics to promote healing of the wound.
[0003] 2. Background of Related Art
[0004] The body's natural wound healing process is a complex series
of events beginning at the moment of injury. Initially the body
reacts by delivering proteins and other factors to the wound
through the blood stream to minimize the damage. Blood clots to
prevent blood loss while cells engulf bacteria and debris to carry
it away from the wound site. Next, the body begins to repair itself
in a stage of healing often referred to as the proliferate phase.
This phase is characterized by the deposition granulation tissue in
the wound bed. Granulation tissue provides a base structure over
which cells may migrate inwardly from the periphery to close the
wound. Finally the process ends as collagen gives strength to new
tissue over time often forming a scar.
[0005] One technique for promoting the natural healing process,
particularly, but not exclusively during the proliferate phase, is
known as vacuum wound therapy (VWT). Application of a reduced
pressure, e.g. sub-atmospheric, to a localized reservoir over a
wound has been found to assist in closing the wound. The reduced
pressure may be effective to promote blood flow to the area to
stimulate the formation of granulation tissue and the migration of
healthy tissue over the wound in the natural process. Also a
reduced pressure may assist in removing fluids exuding from the
wound, which may inhibit bacterial growth. This technique has
proven effective for chronic or non-healing wounds, but has also
been used in for other purposes such as post-operative wound
care.
[0006] The general VWT protocol provides for the introduction of a
filler material into the wound to absorb exudates. The filler
material may comprise such materials as non-reticulated foams,
non-woven fabrics or gauze. The wound and the filler material may
then covered by moisture vapor permeable cover layer that permits
oxygen exchange with the environment, which may be essential for
wound healing. The cover layer often includes an adhesive periphery
that forms a substantially fluid tight seal with the healthy skin
surrounding the wound. The cover layer thus defines a vacuum
reservoir over the wound where a reduced pressure may be maintained
over time by individual or cyclic evacuation procedures.
[0007] An aspect of concern in a VWT treatment is the management of
forces generated in the dressing when a vacuum is applied. Such
forces may cause the separation of the dressing from the skin,
thereby limiting the effect of the VWT treatment and increasing the
probability that microorganisms will infect the wound. Also, such
forces may damage newly forming granulation tissue. The application
of a vacuum can deform a flexible cover layer such that it
compresses the filler and increases its tendency to adhere to the
wound bed. Additionally, the deformation of the cover layer creates
transverse shear forces along the skin-adhesive interface at the
peri-wound area. These shear forces can cause the dressing to shift
and/or pull away from the skin where gaps and wrinkles may develop.
Such movement, and the mentioned results thereof, can inhibit the
dressing's ability to provide a seal that is suitable for both the
maintenance of a vacuum and for prohibiting the infiltration of
contamination.
[0008] Adhesives applied to a cover layer to strengthen or
reinforce the dressing's attachment to the skin may diminish the
moisture vapor permeability of the dressing affecting its ability
to permit oxygen exchange with the environment. Diminished moisture
vapor permeability could also lead to the accumulation of moisture
at the skin-adhesive interface. Permitting such an accumulation
undermines the dressing's adhesion to the skin at the peri-wound
area, thereby reducing the wear-time of the dressing, the
effectiveness of the treatment and the health of the peri-wound
area. Accordingly a need exists for a dressing suitable for use in
a VWT procedure.
SUMMARY
[0009] The present disclosure describes a dressing for use in a
vacuum wound therapy procedure to promote healing of a wound. The
dressing includes a cover layer having a plurality of zones of
variable performance characteristics. A central zone is defined by
a portion of a moisture vapor permeable membrane devoid of any
coating that would otherwise inhibit the transmission of moisture
through the membrane. A peripheral zone adjacent a periphery of the
cover layer is adapted to provide a seal around the perimeter of
the wound. At least one intermediate zone is disposed between the
central zone and the peripheral zone to impart a therapeutic effect
or benefit to the wound.
[0010] The peripheral zone may include a high peal-strength
adhesive while a first intermediate zone may include a
shear-resistant adhesive. A second intermediate zone may include a
coating adapted for medicament delivery, a hydrogel for maintaining
a moist wound environment, or at least one of an anti-infective
agent, an antimicrobial, antibiotic, analgesic, healing factor,
vitamins, growth factors, debridement agents or nutrients.
[0011] The moisture variable permeable membrane may extend to a
periphery of the cover layer so as to constitute a backing layer
for the attachment of an adhesive defining the peripheral zone. The
peripheral zone and at least one intermediate zone may be arranged
concentrically with respect to the central zone. The cover layer
may also include a port for permitting access to a vacuum reservoir
defined beneath the cover layer for a vacuum tube.
[0012] According to another aspect of the disclosure a wound
dressing apparatus for use in a vacuum wound therapy procedure
includes a contact layer and a filler material positioned in a
wound bed and covered by a cover layer. The cover layer defines a
vacuum reservoir above the wound bed and permits access of a vacuum
tube to the vacuum reservoir. The cover layer includes a peripheral
zone to provide a seal around the wound bed, at least one
intermediate zone for imparting a therapeutic effect or benefit to
the wound bed, and a central zone formed from a moisture vapor
permeable membrane.
[0013] The contact layer may be formed from a conical apertured
film to promote unidirectional flow of exudates from the wound. The
absorbent filler material may include polyolefin filaments arranged
in a multi-strand bundle. Also, a vacuum system in fluid
communication with the vacuum reservoir may include a vacuum
source, a collection canister and a one-way valve.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] 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.
[0015] FIG. 1 is an exploded perspective view of a vacuum wound
therapy system in accordance with the present disclosure;
[0016] FIG. 2A is a perspective view of the vacuum wound therapy
system of FIG. 1 assembled for use on a patient;
[0017] FIGS. 2B and 2C depict alternate assemblies of the vacuum
wound therapy system;
[0018] FIG. 3A is a reverse angle perspective view of the cover
layer of FIG. 1;
[0019] FIG. 3B depicts an alternate embodiment of the cover
layer;
[0020] FIG. 4A is a cross sectional view of the vacuum wound
therapy system of FIG. 1 in a first condition exhibiting a vacuum
reservoir; and
[0021] FIG. 4B depicts the vacuum wound therapy system in a second
condition wherein the vacuum reservoir is evacuated.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0022] The wound dressing of the present disclosure promotes
healing of a wound by providing a reservoir over the wound where a
reduced 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. The use of a wound dressing in this manner
has been found to promote healing by reducing the probability of
infection, stimulating the deposition of granulation tissue and
other beneficial processes. The wound dressing of the present
disclosure includes a cover layer having multiple performance zones
to enhance the effect of a vacuum wound therapy treatment.
[0023] The attached figures illustrate exemplary embodiments of the
present disclosure and are referenced to describe the embodiments
depicted therein. Hereinafter, the disclosure will be described in
detail by explaining the figures wherein like reference numerals
represent like parts throughout the several views.
[0024] Referring initially to FIG. 1, a vacuum wound therapy system
according to the present disclosure is depicted generally as 10 for
use on a wound "w" surrounded by healthy skin "s." The vacuum wound
therapy system 10 includes a vacuum system 12 in fluid
communication with a vacuum reservoir 14 (FIG. 4A) defined by or
within the wound dressing 16. The vacuum system 12 includes a
vacuum source 18 coupled to the dressing 16 through a one-way valve
20 and a vacuum tube 24. A collection canister 28 is provided for
wound drainage and debris. The vacuum system 12 is adapted to
provide a reduced pressure to the vacuum reservoir 14 appropriate
to stimulate healing of the wound. A more detailed description of
an appropriate vacuum system 12 is found in commonly assigned U.S.
Patent Application Publication 2007/0066946, the entire contents of
which are incorporated herein by reference.
[0025] Wound dressing 16 generally includes a contact layer 34,
filler 38 and a cover layer 40 defining a plurality of performance
zones. A backing layer 44 may be coated with various materials in a
juxtaposed relation to define a peripheral zone 48, a first
intermediate zone 52, a second intermediate zone 56 and a central
zone 58 (FIG. 3A). Alternatively, each zone may comprise an
independent layer positioned adjacent the wound bed "w." Each layer
is described in greater detail below.
[0026] Contact layer 34 may be sufficiently conformable to be
positioned in direct contact with an irregularly shaped surface of
a wound bed "w." A thin film of polyethylene or other suitable
non-adherent material may form the contact layer 34 to limit the
adherence of filler 38 and other substances to the wound "w."
Apertures or perforations in the film permit fluids to pass through
the contact layer 34, allowing for the sub-atmospheric pressure to
penetrate into the wound "w" and for exudates to flow freely out of
the wound "w." By selecting an appropriate film material, the
passage of wound exudate through contact layer 34 may be controlled
so as to be substantially unidirectional to prevent wound exudate
from flowing back into the wound. To promote a unidirectional flow,
a conical apertured film, such as those provided by Tredegar Film
Products of Richmond, Va., may be selected for forming contact
layer 20. This type of film is arranged with apertures positioned
at the peaks of cone shaped formations in the film material such
that exudate encounters the film as an array of micro-funnels in
one direction and an array of collecting basins in the other.
Unidirectional flow of exudates may also be promoted by the
selection of other materials including a lamination of layers
having varying absorptive characteristics. One exemplary material,
which may be used as a contact layer is sold under the trademark
XEROFLO.RTM. by Kendall Corp., a division of Covidien.
[0027] Filler 38 may be arranged over contact layer 34 to fill
wound "W" to the level of the surrounding healthy skin "s," or
alternatively the wound "w" may be overfilled with filler 38. An
absorbent material such as non-woven gauze or reticulated foam may
be used for filler 38 to trap any exudate that migrates through
contact layer 34. An antimicrobial dressing sold under the
trademark KERLIX.TM. AMD.TM. by Kendall Corp., a division of
Covidien, may be suitable for use as filler 38. To prevent adhesion
to the wound "w," the filler 38 may also comprise a material
configured such that its fibers do not tend to protrude through
apertures of contact layer 34 where they may become engulfed by
newly forming granulation tissue. One particular type of material
exhibiting this characteristic is often referred to as "tow." The
manufacturing process for synthetic fibers often includes an
extrusion of an indeterminate length of continuous filaments, which
are spun together to form fibers. Continuous lengths of un-spun
filaments may be arranged in multi-strand bundles which are
referred to as tow. A single length of tow formed from a
hydrophobic material such as polyolefin may be laid in the wound
bed "w" to form filler 38. This arrangement allows for a complete
removal of filler 50 when the dressing 16 is changed without
re-injuring the wound "w."
[0028] Cover layer 40 may be placed over the wound "W" enclosing
the contact layer and filler therein. The periphery of cover layer
40 extends laterally beyond the perimeter of the wound bed "w" so
as to contact the healthy skin "s" to form a seal over the wound
"w." As depicted in FIG. 2A, an opening 60 may be provided or
formed through the cover layer 40 to provide access for the vacuum
tube 44 to communicate with the vacuum reservoir 14, or the vacuum
tube 44 may be sealed under the periphery of the cover layer 40 as
depicted in FIG. 2B. Alternatively, a distinct portal member or
port 62 may be provided to facilitate fluid communication between
the vacuum system 12 and the vacuum reservoir 14 as depicted in
FIG. 2C. Port 62 may be configured as a rigid or semi rigid,
low-profile component adapted to receive the vacuum tube 24 in a
releasable and fluid-tight manner. The vacuum port 62 may be
configured to include a wide and flexible flange 64 about its
perimeter. The flange 64 permits an adhesive to be attached to
either an underside of flange 64 for securement to an outer surface
of cover layer 40, or to a top side of flange 64 to provide for
mounting to the underside of the cover layer 40.
[0029] Referring now to FIG. 3A, cover layer 40 includes multiple
performance zones 48, 52, 56 and 58 comprising various materials. A
backing layer 44 may extend to the periphery of the cover layer 40
to provide a substrate for various coatings or materials defining
the various performance zones 48, 52, 56 and 58. As depicted, each
of the performance zones 48, 52, 56 and 58 is a continuous band
arranged concentrically with respect to the others. The size, shape
and position of the zones, however, may be varied according to the
needs of the particular wound or treatment. For example, a cover
layer 40A as depicted in FIG. 3B may be provided comprising a first
intermediate zone 52 formed from a pattern of distinct shapes
surrounded by second intermediate zone 56A. The various coatings
may be laminated to the backing layer 44 or affixed by other
appropriate means. The various materials forming layer 40 are
described in greater detail herein below.
[0030] Backing layer 44 may be formed from a flexible polymeric
membrane to act as a fluid barrier to allow for a sub-atmospheric
pressure to be established in vacuum reservoir 14. The material's
flexibility accommodates the pressure changes associated with the
evacuation cycles in a VWT procedure. Backing layer 44 also serves
as a microbial barrier preventing contaminants from entering the
wound area. Preferably, the backing layer 44 is formed from a
moisture vapor permeable membrane to promote the exchange of oxygen
and moisture between the wound site and the atmosphere. A membrane
that provides a sufficient moisture vapor transmission rate (MVTR)
and is simultaneously impervious to liquid may be selected for use
as backing layer 44. Another preferred membrane characteristic is
the ability to stretch and conform to the compressed wound filler
or wound bed. A membrane's tendency for elongation when subjected
to a vacuum reduces the shear forces transitioned to the peri-wound
area. One exemplary material for use in backing layer 44 is a
transparent membrane sold under the trade name DURAFLEX.RTM. by
Deerfield Urethan, a Bayer Material Science Company. Other
materials which may be suitable for use in a backing layer include
the thin films marketed under the names POLYSKIN.RTM.II by Kendall
Corp., a division of Covidien, TEGADERM.TM. by 3M of St. Paul,
Minn. and OPSITE.TM. by Smith and Nephew PLC of London, UK. A
central zone 58 of the cover layer is defined by the area of the
backing layer 44 not covered with any material which would tend to
lessen the MVTR.
[0031] At the periphery of the cover layer 40 is a peripheral zone
48 defined by a continuous layer of high peal-strength, pressure
sensitive adhesive. The adhesive forms a seal with the skin "s"
around the perimeter of the cover layer to prevent the ingress of
atmospheric fluids under the edges of the cover layer 40 when a
reduced pressure is established in the reservoir 14. The adhesive
defining the peripheral zone 48 is adapted to prevent the loss of
adhesion to the skin even when exposed to environmental factors
such as exudates from the wound "w" or body movements by the
patient. In general, the high peal-strength adhesive is adapted to
resist inadvertent lift-off, roll or "flagging," i.e., a failure of
the dressing to adhere to itself, at the edges of the cover layer.
The adhesive defining the peripheral zone 48 may include, for
example, those adhesives included with the dressing sold under the
trademark GELVA.RTM. Multipolymer Solutions by CYTEC Surface
Specialties Inc.
[0032] The high peal-strength adhesive defining peripheral zone 48
may be bonded to backing layer 44, or applied directly to the skin
"s" surrounding the wound bed "w." The adhesive should preferably
be non-irritating and non-sensitizing to the contacted skin, and
may be vapor moisture permeable to permit the contacted skin to
transmit moisture. Preferably, the peripheral zone 48 and first
intermediate zone 52 are positioned so as not to overlap the
contact layer 34 as seen in FIGS. 4A and 4B. This arrangement
facilitates the changing of certain individual components of the
dressing, such as filler 38 without removing the entire dressing
16.
[0033] Disposed between the peripheral zone 48 and central zone 58
are first and second intermediate zones 52 and 56 respectively.
First and second intermediate zones 52, 56 are defined by a layer
of a substance for imparting a therapeutic effect or benefit to the
wound "w." As indicated above, first and second intermediate zones
52, 56 may be arranged as continuous bands concentric with central
zone 58 as seen in FIG. 3A, as a pattern of distinct shapes as seen
in FIG. 3B, or any other convenient arrangement.
[0034] First intermediate zone 52 may, for example, be defined by a
layer of an adhesive that laterally stabilizes the dressing when a
reduced pressure is applied to evacuate the reservoir. As seen in
FIG. 4B, when the reservoir is evacuated, the cover layer may tend
to flatten against the wound "w." This may result in an outwardly
directed force in the dressing 16 which may tend to separate the
cover layer 40 from the skin "s." Also, the shear forces in the
cover layer 40 may be transmitted to the skin "s," pulling apart
newly forming granulation tissue and re-injuring the wound "w." To
counteract these tendencies, a shear-resistant adhesive may be
selected for use in first intermediate zone 52. Since many high
peal-strength adhesives are adapted primarily to resist upwardly
directed forces, i.e., those forces tending to lift the cover layer
from the skin, a high peal-strength adhesive defining the
peripheral zone 48 may be supplemented with an adhesive
particularly adapted to resist lateral forces defining the first
intermediate zone 52. A shear-resistant adhesive, such as GMS 1753
manufactured by CYTEC Surface Specialties Inc., that is moisture
vapor permeable and suitable for use on the skin, may be used to
define first intermediate zone 52.
[0035] Second intermediate zone 56 may be defined by a layer of a
distinct material for providing a therapeutic effect or benefit to
the wound. For example, second intermediate zone 56 may be adapted
for transdermal medicament delivery. A substance such as an
anti-infective agent, an antimicrobial, antibiotic, analgesic,
healing factor, vitamins, growth factors, debridement agents or
nutrients may be coated on portions of backing layer 108 to define
second intermediate zone 56. Alternatively, a hydrogel may be
selected for use in second intermediate zone 56 to maintain a moist
wound environment. As seen in FIG. 4B, second intermediate zone 56
may be in contact with filler 38 when the reservoir 14 is evacuated
to permit transfer beneficial agents thereto. Filler 38 and contact
layer 34 may be eliminated if appropriate allowing for second
intermediate zone 56 to contact the wound bed directly. It is also
contemplated that an additional attachment adhesive may be
beneficial for use in second intermediate zone 56.
[0036] 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.
* * * * *