U.S. patent application number 17/665674 was filed with the patent office on 2022-07-14 for wound dressing.
The applicant listed for this patent is ADVANCED MEDICAL SOLUTIONS LIMITED. Invention is credited to Colin BRADFORD, Brian John HAMERSLAGH.
Application Number | 20220218539 17/665674 |
Document ID | / |
Family ID | |
Filed Date | 2022-07-14 |
United States Patent
Application |
20220218539 |
Kind Code |
A1 |
BRADFORD; Colin ; et
al. |
July 14, 2022 |
WOUND DRESSING
Abstract
The present invention relates to wound dressings which are
particularly useful (but not necessarily exclusively) on moderate
to heavily exuding wounds comprising: an absorbent pad having a
first major face comprised of absorbent material and configured for
wound contact, and a second major face opposed to the first major
face; and a backing layer bonded to the second major face of the
pad; wherein the pad and the backing layer are sized such that the
backing layer extends beyond the periphery of the pad, thereby
defining a margin; wherein the margin of the backing layer is
provided with a first adhesive for adhering the backing layer to
skin; and wherein a layer of second, low trauma adhesive is
provided on, and in direct contact with, the first major face of
the pad for adhering the pad to a wound, said layer of second, low
trauma adhesive being configured to allow passage of exudate from
the wound to the absorbent pad.
Inventors: |
BRADFORD; Colin; (Keighley,
GB) ; HAMERSLAGH; Brian John; (Higher Runcorn,
GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ADVANCED MEDICAL SOLUTIONS LIMITED |
Winsford |
|
GB |
|
|
Appl. No.: |
17/665674 |
Filed: |
February 7, 2022 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15672571 |
Aug 9, 2017 |
11266548 |
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17665674 |
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International
Class: |
A61F 13/537 20060101
A61F013/537; A61F 13/02 20060101 A61F013/02; A61L 15/58 20060101
A61L015/58; A61L 15/60 20060101 A61L015/60 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 10, 2016 |
GB |
1613744.0 |
Claims
1. A wound dressing comprising: an absorbent pad having a first
major face comprised of absorbent material and configured for wound
contact, and a second major face opposed to the first major face;
and a backing layer bonded to the second major face of the pad;
wherein the pad and the backing layer are sized such that the
backing layer extends beyond the periphery of the pad, thereby
defining a margin; wherein the margin of the backing layer is
provided with a first adhesive for adhering the backing layer to
skin; and wherein a layer of second, low trauma adhesive is
provided on, and in direct contact with, the first major face of
the pad for adhering the pad to a wound, said layer of second, low
trauma adhesive being configured to allow passage of exudate from
the wound to the absorbent pad.
2. The wound dressing according to claim 1, wherein the second
adhesive is selected from silicone-based adhesives, sheet
hydrogels, polyurethane-based adhesives and modified
polyolefin-based adhesives.
3. The wound dressing according to claim 1, wherein the second
adhesive is a silicone-based adhesive.
4. The wound dressing according to claim 1, wherein the layer of
second, low trauma adhesive is a discontinuous layer.
5. The wound dressing according to claim 4, wherein the
discontinuous layer of second, low trauma adhesive has an open area
of greater than 50%.
6. The wound dressing according to claim 1, wherein the layer of
second, low trauma adhesive is printed onto the first major face of
the pad.
7. The wound dressing according to claim 1, wherein the second
adhesive has a peel strength of 0.1 to 1.0N/2.5 cm.
8. The wound dressing according to claim 1, wherein the first
adhesive has a peel strength of 3.0 to 7.0N/2.5 cm.
9. The wound dressing according to claim 1, wherein the first
adhesive is selected from acrylic-based adhesives, aqueous-based
adhesives, and hydrocolloids.
10. The wound dressing according to claim 1, wherein the margin of
the backing layer and/or the first major face of the pad is
provided with an antimicrobial agent.
11. The wound dressing according to claim 10, wherein the
antimicrobial agent is selected from silver, silver compounds,
iodine, iodine compounds, or polyhexamethylene biguanide
(PHMB).
12. The wound dressing according to claim 1, wherein the margin of
the backing layer and/or the first major face of the pad is
provided with an anti-biofilm agent.
13. A wound dressing substantially as hereinbefore described with
reference to the figures.
14. A process for manufacturing a wound dressing, the process
comprising the steps of: (a) providing a backing layer; (b)
providing a pad of absorbent material having a first major face
comprised of absorbent material and configured for wound contact,
and a second major face opposed to the first major face; and (c)
bonding the second major face of the pad of absorbent material to
the backing layer; wherein the pad is provided with a layer of
second, low trauma adhesive on, and in direct contact with, the
first major face of the pad.
15. The process for manufacturing a wound dressing according to
claim 14, wherein the first major face of the pad of absorbent
material is provided with the layer of second, low trauma adhesive
prior to bonding the second major face of the pad of absorbent
material to the backing layer.
Description
[0001] The present invention relates to wound dressings for use
particularly (but not necessarily exclusively) on moderate to
heavily exuding wounds. The wound dressings of the present
application have particular (but again not necessarily exclusive)
application to wounds on moving body parts (such as the knee, elbow
etc.).
[0002] Absorbent wound dressings for moderate to heavily exuding
wounds typically take the form of so-called "island dressings"
comprising an absorbent pad configured for direct wound contact,
and an adhesive backing layer extending beyond the periphery of the
pad and thereby defining an adhesive border, said border being
configured to adhere the dressing to the skin surrounding a wound
and to provide a protective barrier to the wound.
[0003] Some island dressings can, however, have poor adherence
properties, since adhesive material may only be provided around the
adhesive border region, rather than on the entire body-contacting
portion of the dressing. As a result, a significant proportion of
the dressing is not adhesive.
[0004] In order to ameliorate this issue, in addition to the border
region of the backing layer being provided with an adhesive, the
pad of an island dressing may be provided with wound contacting
adhesive in order to adhere the pad itself to a wound. Conventional
practice in the construction of such dressings is for the pad to be
part of a laminate construction comprising, in addition to the pad
itself, a film layer which is adhesively bonded (e.g. by means of
an acrylic adhesive) to the face of the pad remote from the backing
layer and which carries the layer of wound contacting adhesive.
Such dressings are typically manufactured by a process including
the following steps: [0005] (i) providing the film, on one face
thereof, with a layer of adhesive for bonding the film to the pad
and, on the other face thereof, with the layer of the wound
contacting adhesive; [0006] (ii) perforating the film and
associated adhesive layers; [0007] (iii) bonding the adhesive pad
to the backing layer; and [0008] (iv) bonding the film to the
adhesive pad.
[0009] Adhesives suitable for use as the wound contacting adhesive
may be impervious to fluid, and hence perforation step (ii) is used
in order to provide passages (i.e. "open areas") for exudate to be
transmitted from the wound, through the film layer, and to the
absorbent pad.
[0010] Such dressings have better adhesive properties than those
without a wound contacting adhesive on the pad, but do have a
number of disadvantages.
[0011] Removal of dressings comprising further adhesive film layers
can cause pain and/or wound damage (trauma) on removal, since the
adhesive on the wound-contacting pad can pull relatively fragile
granulating tissue (i.e. new tissue formed during the wound healing
process) away from the wound.
[0012] Additionally, such dressings are difficult to manufacture,
since perforation of the film layer coated with adhesive on both
major surfaces thereof is difficult. Since the adhesive sticks to
the perforation tool and as a result either the perforated piece
may not be removed properly or the adhesive gradually builds up on
the perforation tool and eventually causes jamming.
[0013] Additionally, perforation of the film layer has practical
limits in terms of the degree of "open areas" achievable, thereby
limiting the effectiveness of the wound dressing in wound exudate
uptake. Perforated film layers are typically able to attain an open
area of at most about 20% with greater open areas the film becomes
too flimsy to handle in a manufacturing process.
[0014] It is an object of the invention to obviate or mitigate the
disadvantages mentioned above.
[0015] According to a first aspect of the present invention there
is provided a wound dressing comprising: [0016] an absorbent pad
having a first major face comprised of absorbent material and
configured for wound contact, and a second major face opposed to
the first major face; and [0017] a backing layer bonded to the
second major face of the pad; [0018] wherein the pad and the
backing layer are sized such that the backing layer extends beyond
the periphery of the pad, thereby defining a margin; [0019] wherein
the margin of the backing layer is provided with a first adhesive
for adhering the backing layer to skin; and [0020] wherein a layer
of second, low trauma adhesive is provided on, and in direct
contact with, the first major face of the pad for adhering the pad
to a wound, said layer of second, low trauma adhesive being
configured to allow passage of exudate from the wound to the
absorbent pad.
[0021] In the context of the present invention, the term "low
trauma" is intended to qualify that the second adhesive has a
suitable adhesive strength to adhere the pad directly to a wound,
but which does not have an adhesive strength which would cause
significant pain and/or wound damage (trauma) upon removal.
Suitably, the second adhesive may have a peel strength of
0.1-1.0N/2.5 cm. (Peel strengths for the purposes of the present
application are determined by using a strip comprising the
adhesively coated substrate, the strip having a width of 25 mm and
a length of 120-130 mm. For the purpose of testing, the strip is
peeled from a clean stainless steel surface and the peel strength
is determined using a Lloyds LRX Tensometer with a 50N load
cell).
[0022] The wound dressings of the present invention offer
advantages over prior art dressings, since adhesive is provided
both around the margin of the backing layer and also on the
adhesive pad itself (collectively referred to hereinafter as the
"body-contacting surface" of the wound dressing). This allows for
good adherence of the wound dressing to a patient. Such dressings
have particular application to wounds on moving body parts (such as
the knee, elbow etc.), where strong adhesion is required to
maintain the dressing fixed to the body.
[0023] Furthermore, the use of low trauma adhesive on the absorbent
pad ensures that pain and/or wound damage (trauma) upon removal is
mitigated.
[0024] Adhesives suitable for use as the second, low trauma
adhesive may be impervious to fluid, thereby restricting flow of
wound exudate to the absorbent pad on which the second adhesive is
applied. To ameliorate this issue, the layer of second, low trauma
adhesive may be a discontinuous (i.e. incomplete) layer.
Discontinuous layers thereby facilitate passage of wound exudate
therethrough and thereby improve uptake of wound exudate by the
pad. Such a discontinuous layer may, for example, take the form of
a reticulated (net-like) pattern or could take the form of a series
of adhesive dots provided on the surface of the pad. Other
arrangements will be readily appreciated by those of skill in the
art.
[0025] The discontinuous layer of second, low trauma adhesive may
have an open area of greater than 30% (e.g. greater than 50%) since
difficulties with production of apertured films does not apply when
the adhesive is provided directly on the pad. The open area may be
greater than 30% and may, for example, be 30-60%. This compares
with prior art constructions, such as those involving a perforated
film adhesive wound-contacting layer, which typically have an open
area of only 20%. It will therefore be appreciated that wound
dressings according to the present invention which include a
discontinuous layer of second adhesive offer particularly improved
wound exudate uptake properties as compared with the prior art.
[0026] The layer of second, low trauma adhesive is preferably
printed onto the first major face of the pad.
[0027] The second adhesive may be selected from silicone-based
adhesives, sheet hydrogels, polyurethane-based adhesives and
modified polyolefin-based adhesives. Adhesives from this list may
be selected to have the required low trauma characteristics
suitable for use in adhering absorbent pads directly to wounds,
while not causing substantial pain and/or wound damage (trauma)
upon removal.
[0028] The second adhesive is preferably a silicone-based adhesive,
since such adhesives do not lose tack (i.e. adhesive strength) when
wet. It will be appreciated that the wound-contacting pad, on which
the second adhesive is applied, may encounter significant levels of
wound exudate in use. It follows that employing an adhesive which
maintains tack in such an environment provides particular
advantages in providing adhesive wound dressings for use in such
applications.
[0029] Particularly preferred wound dressings utilise
silicone-based second adhesive layers having an open area of
greater than 50% in a reticulated or dotted pattern. Such dressings
are particularly advantageous in terms of low-trauma properties,
since the relatively large open area equates to reduced adhesive
coverage (as compared with wound dressings employing perforated
adhesive film layers, which typically have open layers of at most
20%), thereby ameliorating issues with pulling fragile granulating
tissue from the wound upon dressing removal.
[0030] Suitable medical grade silicone adhesives for use in the
present invention are obtainable as two part systems from companies
such as Bayer or Wacker. For use in the invention, the two part
systems are mixed together, printed or coated onto substrate, and
then cured by heat.
[0031] In the present invention, the layer of second
wound-contacting adhesive is in direct contact with the pad, by
which we mean that the whole area of the low trauma adhesive is in
contact with the absorbent pad. This means that there is no
requirement to use further film or other intermediate layers as a
carrier for the wound-contacting adhesive, thereby reducing the
number of component parts in the dressing. Direct contact also
allows alternative manufacturing options for the wound dressings of
the present invention as compared with the prior art, thereby
ameliorating the aforementioned difficulties in relation to
manufacturing.
[0032] According to a second aspect of the present invention there
is provided a process for manufacturing a wound dressing, the
process comprising the steps of: [0033] (a) providing a backing
layer; [0034] (b) providing a pad of absorbent material having a
first major face comprised of absorbent material and configured for
wound contact, and a second major face opposed to the first major
face; and [0035] (c) bonding the second major face of the pad of
absorbent material to the backing layer; [0036] wherein the pad is
provided with a layer of second, low trauma adhesive on, and in
direct contact with, the first major face of the pad.
[0037] The first major face of the pad of absorbent material may be
provided with the layer of second, low trauma adhesive prior to, or
after, bonding the second major face of the pad of absorbent
material to the backing layer. Preferably the layer of second, low
trauma adhesive is provided on the bad prior to bonding. Such a
method is particularly beneficial, since the backing layer and pad
may be manufactured separately, and then bonded together in order
to complete the dressing.
[0038] Provision of both the first and second adhesive may be
achieved using methods customary to those in the art, including via
use of a rotary screen printer, gravure roller, knife over roller,
transfer coating, etc. The layer of second, low trauma adhesive is
preferably printed onto the first major face of the pad.
[0039] The backing layer of the wound dressings of the present
invention may be comprised of any suitable material customary to
those of skill in the art. The backing layer may be comprised of a
flexible material. Suitable materials for use as the backing layer
include semi-permeable polyurethane films, semi-permeable membranes
or non-woven fabrics. Typically, the backing layer should be
comprised of material suitable for providing a waterproof and/or
microbial barrier layer over the absorbent pad.
[0040] The margin defined by the relative sizing of the pad and
backing layer may completely encircle the pad, thereby defining a
border.
[0041] As mentioned above, the backing layer is also provided with
an adhesive (herein referred to as the "first adhesive"). The first
adhesive need not be a "low trauma" adhesive, as with the second
adhesive, since it is not intended to contact the fragile tissue of
a wound directly, but is instead intended to contact relatively
strong, intact skin surrounding the wound. As a result, issues with
pain and wound damage (trauma) on removal of the dressing are
reduced, thereby enabling use of stronger adhesives. Suitably, the
first adhesive may have a peel strength of 3.0-7.0N/2.5 cm. The
first adhesive may be selected from acrylic-based adhesives,
aqueous-based adhesives, and hydrocolloids. Suitable acrylic
adhesives are available under the designations "National Starch
380-2819", "Gelva Adhesive 788" and "Gelva Adhesive 737".
[0042] The margin of the backing layer and/or the first major face
of the pad may be provided with an antimicrobial and/or
anti-biofilm agent. Suitable antimicrobial agents include silver,
silver compounds, iodine, iodine compounds, or polyhexamethylene
biguanide (PHMB).
[0043] When antimicrobial agents are used in conjunction with
acrylic- or aqueous-based adhesives on the margin of the backing
layer, ionic species having antimicrobial properties are able to
elute from the margin thereby giving an antimicrobial effect.
Provision of antimicrobial on the border thereby assists in
preventing ingress of micro-organisms into a wound.
[0044] The absorbent pad may be comprised of absorbent polyurethane
foam. Polyurethane foam for use in the invention may be produced by
procedures that are entirely conventional in the art.
[0045] If the foam is the only absorbent in the dressing, then a
suitable thicknesses will be 3-5 mm. If the dressing contains a
superabsorbent, the foam can be as thin as 1.5 mm.
[0046] Bonding of the components of the dressing (e.g. the backing
layer and pad) may be achieved by any suitable means. Thus, for
example, an entire surface of the backing layer may be provided
with a layer of adhesive which functions to provide the first
adhesive on the margin of the backing layer and which also
functions to bond the absorbent pad and the backing layer
together.
[0047] Preferred features described above in relation to the first
aspect of the present invention also represent preferred features
of the second aspect of the present invention (and vice versa),
subject to a technical incompatibility that would prevent such a
combination of preferred features. Furthermore, it will be evident
to the skilled person that advantages set out above in respect of
the first aspect of the present invention are also offered by the
second aspect of the present invention.
[0048] The invention will now be further described, by way of
example only, with reference to the accompanying drawings, in
which:
[0049] FIG. 1 is a schematic sectional view of a wound dressing
embodying the first aspect of the present invention, as seen from a
side thereof; and
[0050] FIG. 2 is a schematic top-down view of the wound dressing
depicted in FIG. 1.
[0051] The figures illustrate a generally rectangular adhesive
wound dressing 1 of the "island" type, which has useful application
to moderate to heavily exuding wounds, particularly those on moving
body parts (such as the knee, elbow etc.).
[0052] The wound dressing 1 is a laminate construction comprising a
backing layer 3 having an absorbent pad layer 5 disposed centrally
thereon and bonded thereto in the manner described below. The
backing layer 3 is sized so as to extend beyond the periphery of
the pad 5, and thereby defines an exposed border region 3a
encircling the pad 5. The exposed border region 7 and the pad 5 are
both configured to adhere to the human body in the region of, and
surrounding, a wound as explained more fully below.
[0053] The absorbent pad 5 is comprised of polyurethane foam. The
pad 5 has a first major face 5a configured for wound contact and a
second major face 5b opposed thereto.
[0054] The wound-contacting face 5a of the absorbent pad 5 is
provided with a layer of a silicone-based adhesive 9, for adhering
the pad 5 to a wound. Silicone-based adhesives typically have
weaker adhesive strength than acrylic-based adhesives, and may be
described as "low trauma" adhesives since little (if any) pain
and/or wound damage (trauma) is experienced upon dressing
removal.
[0055] Silicone-based adhesive layers are impervious to liquid, and
so in order to facilitate wound exudate uptake by the pad 5, the
silicone-based adhesive layer 9 is present on the pad 5 as a
discontinuous layer, having so-called "open areas", i.e. openings
allowing passage of fluid therethrough.
[0056] The backing layer 3 is comprised of polyurethane film. The
backing layer 3 has a first major face 3a a second major face 3b
opposed thereto, with the entire first major face 3a being coated
with an acrylic-based pressure-sensitive adhesive 11 (see FIG.
1).
[0057] Bonding between the backing layer 3 and pad 5 is achieved by
pressing the second major face 5b of the pad 5 into contact with
the first major face 3a of the backing layer 3, thereby activating
the pressure-sensitive adhesive 11 provided on the backing layer
3.
[0058] Since adhesive 11 is applied across the entire surface of
the backing layer 3, the adhesive 11 on the exposed border region 7
remains exposed after bonding the relatively smaller absorbent pad
5 to the backing layer 3. This exposed adhesive 11 on the border
region 7 is therefore available to adhere the wound dressing to
skin when pressed into contact therewith.
[0059] In use, the wound dressing 1 may be placed against a wound,
with the pad 5 in direct contact with the fragile, granulating
wound tissue and the adhesive border 7 of the backing layer 3 being
in direct contact with intact skin encircling the wound. The
adhesive 11 on the border 7 of the backing layer 3 and the adhesive
9 on the pad 5 cooperate to adhere the dressing 1 to the body. The
relatively strong acrylic-based adhesive 11 adheres the border
region 7 of the backing layer to the intact skin encircling the
wound, while the silicone-based adhesive 9 of the pad 5 bonds to
the fragile granulating tissue of the wound.
[0060] The illustrated wound dressing is produced by a
manufacturing process involving the following steps: [0061] (i)
providing a backing layer comprising an acrylic-based adhesive on
an entire major face thereof; [0062] (ii) providing a pad of
absorbent material having a first major face comprised of absorbent
material and printed with silicone-based adhesive, and a second
major face opposed to the first major face; and [0063] (iii)
pressing the second major face of the pad of absorbent material
against the major face of the backing layer which is provided with
adhesive to effect bonding therebetween.
* * * * *