U.S. patent application number 16/428643 was filed with the patent office on 2019-11-21 for wound dressing of continuous fibers.
The applicant listed for this patent is Smith & Nephew Inc.. Invention is credited to Kevin Corley, David G. Heagle, Kristin L. Watson.
Application Number | 20190350765 16/428643 |
Document ID | / |
Family ID | 41653603 |
Filed Date | 2019-11-21 |
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United States Patent
Application |
20190350765 |
Kind Code |
A1 |
Heagle; David G. ; et
al. |
November 21, 2019 |
WOUND DRESSING OF CONTINUOUS FIBERS
Abstract
A method for treating a wound that includes incorporating a
wound dressing comprising a plurality of fibers, each fiber having
a length of at least two (2) inches, into a wound to cause the
walls of the wound to remain apart and allow the wound to heal from
the inside to the outside, and removing the wound exudate.
Inventors: |
Heagle; David G.; (Taunton,
MA) ; Corley; Kevin; (Reading, MA) ; Watson;
Kristin L.; (North Attleboro, MA) |
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Applicant: |
Name |
City |
State |
Country |
Type |
Smith & Nephew Inc. |
Memphis |
TN |
US |
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|
Family ID: |
41653603 |
Appl. No.: |
16/428643 |
Filed: |
May 31, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15169608 |
May 31, 2016 |
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16428643 |
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14326295 |
Jul 8, 2014 |
9474654 |
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15169608 |
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13569905 |
Aug 8, 2012 |
8777911 |
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14326295 |
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12537284 |
Aug 7, 2009 |
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13569905 |
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61147179 |
Jan 26, 2009 |
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61096105 |
Sep 11, 2008 |
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61188370 |
Aug 8, 2008 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61F 2013/0054 20130101;
A61F 13/02 20130101; A61F 13/00068 20130101; A61M 1/0088 20130101;
A61F 13/00995 20130101; A61F 2013/00412 20130101; A61F 2013/00357
20130101; A61F 2013/00536 20130101; A61F 13/00042 20130101; A61F
2013/00519 20130101; A61F 13/00063 20130101; A61F 2013/00174
20130101; A61F 2013/00238 20130101; A61F 2013/00565 20130101; A61F
2013/00842 20130101; A61M 1/0023 20130101; A61F 2013/00348
20130101; A61F 13/0216 20130101; A61F 2013/0057 20130101; A61F
2013/00557 20130101 |
International
Class: |
A61F 13/00 20060101
A61F013/00; A61M 1/00 20060101 A61M001/00; A61F 13/02 20060101
A61F013/02 |
Claims
1-52. (canceled)
53. A wound therapy apparatus, comprising: a wound dressing
configured to be placed over a wound, the wound dressing configured
to form a substantially fluid-tight seal around the wound, the
wound dressing comprising: an elongate tube having a length
extending in a longitudinal direction, the elongate tube
comprising: a sheath; and a core surrounded by the sheath, the core
comprising an elongate sleeve comprising a fibrous material.
54. The wound therapy apparatus according to claim 53, wherein the
elongate sleeve comprises a length extending along the length of
the elongate tube.
55. The wound therapy apparatus according to claim 53, wherein the
fibrous material comprises a mesh.
56. The wound therapy apparatus according to claim 53, wherein the
core comprises nylon.
57. The wound therapy apparatus according to claim 53, wherein the
sheath comprises an upper sheet and a lower sheet which are
attached to each other, encapsulating the core.
58. The wound therapy apparatus according to claim 57, wherein the
upper and lower sheets are attached by a heat seal, an adhesive
bond, or an ultrasonic weld.
59. The wound therapy apparatus according to claim 53, wherein the
wound dressing further comprises a cover layer.
60. The wound therapy apparatus according to claim 59, wherein the
cover layer comprises a moisture vapor permeable membrane.
61. The wound therapy apparatus according to claim 59, wherein the
cover layer is transparent.
62. The wound therapy apparatus according to claim 53, wherein the
wound dressing further comprises a foam layer.
63. The wound therapy apparatus according to claim 53, further
comprising a source of negative pressure configured to be in fluid
communication with the wound dressing, the source of negative
pressure configured to provide negative pressure to the wound.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 15/169,608 filed on May 31, 2016, titled
"WOUND DRESSING OF CONTINUOUS FIBERS", which is a continuation of
U.S. patent application Ser. No. 14/326,295 filed on Jul. 8, 2014,
titled "WOUND DRESSING OF CONTINUOUS FIBERS", which is a
continuation of U.S. patent application Ser. No. 13/569,905 filed
on Aug. 8, 2012, titled "WOUND DRESSING OF CONTINUOUS FIBERS",
which is a continuation of U.S. patent application Ser. No.
12/537,284 filed on Aug. 7, 2009, titled "WOUND DRESSING OF
CONTINUOUS FIBERS", now abandoned, which claims the benefit of
priority under 35 U.S.C .sctn. 119(e) to U.S. Provisional
Application No. 61/147,179 filed on Jan. 26, 2009, titled "WOUND
FILLER MATRIX WITH CONTINUOUS FIBER", U.S. Provisional Application
Ser. No. 61/096,105 filed on Sep. 11, 2008, titled "WOUND CONTACT
LAYER AND FILLER," and U.S. Provisional Application Ser. No.
61/188,370 filed on Aug. 8, 2008, titled "METHOD FOR TREATING A
WOUND." The disclosures of all these prior applications are hereby
incorporated herein by reference in their entireties and are to be
considered a part of this specification.
BACKGROUND
Technical Field
[0002] The present disclosure relates generally to wound dressings,
and in particular to a wound dressing including an assembly or tow
of continuous long fibers for receiving and retaining wound fluids
in the treatment of acute and chronic wounds.
Background of Related Art
[0003] Wound dressings are generally placed over a wound to protect
and promote healing of the wound. In the case of exuding wounds,
such as pressure sores, ulcers and burns, it is customary to
provide a dressing having a packing or filler material for
receiving, retaining or conveying the wound exudate as it is
produced. Exudates may be conveyed from the wound bed, at least in
part, due to wicking characteristics of the wound filler. Thus, the
wound filler promotes healing by removing potentially harmful
bacteria from the wound bed, and also prevents damage to the
surrounding skin that can be caused by an excessively moist
environment.
[0004] The dressing filler may capture the excess exudates for
subsequent removal, e.g., when the dressing is replaced with a new
dressing. Some materials, such as cotton, tend to shed fibers or
fibrils (e.g., very short or irregular fibers jutting out from the
main fiber structure) into the wound. These fibers may tend to
remain in the wound when the dressing is changed. Removing these
stray fibers can be a labor intensive procedure that may further
damage the wound, and neglecting to remove these stray fibers may
cause irritation and otherwise inhibit natural healing of the
wound.
[0005] One technique that may utilize a dressing with an absorbent
filler is known as negative wound pressure therapy (NWPT). The
absorbent material may be positioned in a reservoir over the wound
where a negative 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. This technique has been found to promote
blood flow to the area, stimulate the formation of granulation
tissue and encourage the migration of healthy tissue over the
wound. An NWPT apparatus may also serve to draw exudates from the
absorbent material out of the dressing without requiring that the
entire dressing be changed. When an NWPT procedure is complete,
however, the absorbent material must be removed and is thus subject
to the difficulties that may be caused by stray fibers.
Accordingly, all absorbent filler suitable for use in wound
dressings including those wound dressings adapted for use in
advanced wound therapy procedures such as NWPT would be
helpful.
SUMMARY
[0006] According to one aspect of the disclosure, a method for
treating a wound includes using a wound dressing comprising a
plurality of fibers, each fiber having a length of at least two (2)
inches. The method entails incorporating the wound dressing into a
wound to keep the sides of the wound apart, and removing the wound
exudate.
[0007] According to another aspect of the disclosure, a wound
dressing apparatus is configured to promote the healing of a wound,
and may be used in conjunction with an NWPT system. The apparatus
includes a wound cover for defining a reservoir over a wound in
which a negative pressure may be maintained by forming a
substantially fluid-tight seal around the wound, a vacuum source in
fluid communication with the reservoir and suitable for providing
an appropriate negative pressure to the reservoir to stimulate
healing of the wound, and a packing structure positioned between
the wound and the wound cover. The packing structure includes a
core of filler material substantially surrounded by a sheath of
contact material. The filler material is adapted for receiving
wound fluids, and may be adapted for transporting wound fluids from
the wound. The sheath of contact material is adapted for direct
contact with the wound, and is permeable to wound fluids to permit
passage of wound fluids through the core.
[0008] The packing structure may define an elongate tube, and may
exhibit a plurality of longitudinally spaced separation features
adapted for dividing the packing structure. A pod defined between
adjacent separation features may assume a closed configuration such
that the sheath of contact material extends along opposite lateral
edges of the pod. The separation features include a perforated tear
line extending laterally across the packing structure and may be
spaced apart from adjacent separation features by a distance of
from about 50% to about 300% of a width of the packing feature.
[0009] In some embodiments of the disclosure, the contact material
may comprise a directionally-apertured film, and the filler
material may comprise a polypropylene tow. The sheath may comprise
upper and lower sheets of the directionally-apertured film having a
seal around a periphery to encapsulate the filler between the upper
and lower sheets, and each of the upper and lower sheets may be
arranged such that a male side of the directionally-apertured film
is oriented toward the interior of the packing structure to
encourage exudate flow into the packing structure. Other
non-adherent materials are also envisioned. Alternatively, one of
the upper and lower sheets may be arranged such that a male side of
the directionally-apertured film is oriented toward the interior of
the packing structure, and the other of the upper and lower sheets
may be arranged such that a mate side of the
directionally-apertured film is oriented toward the exterior of the
packing structure to encourage exudate flow through the packing
structure. The packing structure may comprise upper and lower
sheets of contact material having a seal around a periphery to
encapsulate the filler material between the upper and lower sheets.
Furthermore, the packing structure may comprise at least one
interior seal to define a central pod that is encircled by at least
one ring-shaped pod toward a circumferential region of the packing
structure. A separation feature may be included on the seal. A
plurality of progressively larger ring-shaped pods toward the
circumferential region of the packing structure may be defined by a
plurality of generally concentric interior seals.
[0010] The filler may include a foam layer adjacent one of the
upper and lower sheets of contact material, and a tow layer
adjacent the foam layer. A foam layer may be disposed on each side
of the tow layer, and a hole may be formed in the foam layer to
promote the flow of wound fluids through the packing structure.
[0011] According to another aspect of the disclosure, a wound
dressing for use with wounds includes a core of filler material,
and a sheath of contact material substantially surrounding the
core. The core of filler material is adapted for receiving wound
fluids, and may also be adapted for transporting wound fluids from
the wound. The contact material is adapted for positioning in
direct contact with the wound, and the sheath is permeable to
permit passage of the wound fluids into and through the core. A
plurality of longitudinally spaced separation features is adapted
for dividing the wound dressing, and adjacent separation features
define a pod there between. A plurality of pods may be arranged to
define a two dimensional array. The contact material may comprise a
directionally-apertured film, and the filler material may comprise
a polypropylene tow.
[0012] According to still another aspect of the disclosure, a wound
dressing for use with wounds includes a core of filler material
comprising a polypropylene tow, a sheath of contact material
substantially surrounding the core and comprising a
directionally-apertured film, and a seal at a periphery of the
sheath of contact material encapsulating the core within the sheath
of contact material.
[0013] According to another aspect of the disclosure, a wound
filler for use with a negative wound pressure therapy apparatus,
e.g., may include a wound dressing for defining a reservoir over a
wound in which a negative pressure may be maintained by forming a
substantially fluid-tight seal around the wound, a vacuum source in
fluid communication with the reservoir and being suitable for
providing an appropriate negative pressure to the reservoir to help
stimulate healing of the wound, and a wound filler matrix disposed
within the wound dressing. The wound filler matrix defines a length
along a longitudinal axis and comprises at least one continuous
fiber configured in a plurality of loop segments traversing the
longitudinal axis. The wound filler matrix further includes a
connecting segment extending along the longitudinal axis and
connected to at least some of the loop segments. The connecting
segment may maintain the integrity of the at least one continuous
fiber thereby facilitating placement and removal from the wound
bed. The connecting segment may be connected to each loop segment.
The connecting segment may be adapted to be severed to provide a
segment of the wound filler matrix to accommodate wounds of various
sizes and types. The connecting segment may be dimensioned to
define a handle segment extending longitudinally beyond the at
least one continuous fiber.
[0014] The connecting segment and the at least one continuous fiber
may comprise different material. The at least one continuous fiber
may include multifilaments. The at least one continuous fiber of
the wound filler matrix may be non-absorbent, and may include an
additive.
[0015] In another embodiment, a wound dressing apparatus includes a
cover layer adapted to cover a wound to provide a microbial barrier
over the wound and a wound filler matrix for `receiving wound
fluids. The wound filler matrix may include a continuous fiber
arranged in a tow configured by passing a connecting segment
through the fiber to gather the fiber into a plurality of loop
segments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] 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.
[0017] FIG. 1A is a cross sectional view of a wound dressing
apparatus formed in accordance with the present disclosure;
[0018] FIG. 1B is a cross sectional view of an alternate wound
dressing apparatus formed in accordance with the present
disclosure;
[0019] FIGS. 2A through 2I are partial orthogonal views depicting
various configurations for a wound filler as depicted in FIGS. 1A
and 1B;
[0020] FIGS. 3A through 3G are schematic views depicting various
co-extrusion arrangements for individual fibers as depicted in
FIGS. 2A through 2I;
[0021] FIGS. 4A through 4F are schematic views depicting various
cross sections of the individual fibers of FIGS. 2A through 2I;
[0022] FIG. 5 is a cross sectional view of a wound dressing
apparatus including a packing structure formed in accordance with
another aspect of the present disclosure;
[0023] FIGS. 6A through 6C are partial perspective views depicting
various configurations for the packing structure of FIG. 5.
[0024] FIG. 7A is a top plan view an alternate embodiment of a
packing structure;
[0025] FIG. 7B is a cross sectional view of the packing structure
of FIG. 4A;
[0026] FIG. 7C is a perspective view of a male side of a
directionally-apertured film;
[0027] FIG. 8A is a top plan view of another alternate embodiment
of a packing structure;
[0028] FIG. 8B is a cross sectional view of the packing structure
of FIG. 5A;
[0029] FIGS. 9A-9F are cross sectional schematic views illustrating
a manufacturing process used for the assembly of another alternate
embodiment of a packing structure;
[0030] FIGS. 10A-10C are cross sectional views of alternate
embodiments of a packing structure;
[0031] FIG. 11 is a top plan view of alternate embodiment of a
packing structure;
[0032] FIG. 12 is a schematic view depicting an embodiment of a
wound filler matrix of the present disclosure;
[0033] FIG. 12A is a cross-sectional view of the wound filler
matrix taken along the lines 12A-12A of FIG. 12;
[0034] FIG. 12B is a cross-sectional view similar to the view of
FIG. 2A of an alternate embodiment of the wound filler matrix;
and
[0035] FIGS. 13A through 13I are opartial orthogonal views
depicting various configurations for a multifilament fiber of the
wound filter matrix of the present disclosure.
DETAILED DESCRIPTION
[0036] The present disclosure relates to treatment of a wound using
a wound dressing comprising a plurality of fibers, each fiber
having a length of at least two (2) inches and in one embodiment,
at least 4 inches and in other embodiments, at least 6 inches, and
at least 8 inches. The method of treatment entails incorporating
the wound dressing into a wound to keep the sides of the wound
apart, and removing the wound exudate.
[0037] In more detail, the fiber of the wound dressing may be any
fiber having a length of at least two (2) inches. Included within
the suitable fibers are natural fibers and man-made fibers.
[0038] Examples of suitable fibers are natural fibers produced by
plants, animals and/or geologic processes. For example, natural
fibers include alginates, chitosan, rayon, vegetable fibers, which
may be generated from arrangements of cellulose and bound together
by lignin as in cotton, hemp, jute, flax, ramie and sisal, for
example. Also, wood fibers are derived from tree sources and
include groundwood, thermomechanical pulp (TMP) and bleached or
unbleached kraft or sulfite (sulphite) pulps formed by a
manufacturing process wherein lignin is removed to free the fibers
from the wood structure. Animal fibers consist largely of proteins
and include spider silk, sinew, catgut, wool and hair such as
cashmere, mohair and angora, and chitosan for instance. There are
also mineral sources for natural fibers such as woolastinite,
attapulgite, halloysite, and asbestos.
[0039] Suitable man-made fibers include regenerated fibers and
synthetic fibers. Regenerated fibers are those fabricated from
natural materials by processing these materials to form a fiber
structure. For example, regenerated fibers may be derived from the
pure cellulose in cotton and wood pulp to form such products as
rayon and cellulose acetates. Fibers may also be regenerated from
mineral sources such as glass or quartz to form fiberglass or
optical fibers. Ductile metals such as copper gold or silver may be
drawn to form metallic fibers, and more brittle materials such as
nickel aluminum or iron may be extruded or deposited.
[0040] Synthetic fibers are made entirely from synthetic materials
such as petrochemicals, and are usually stronger than either
natural or regenerated fibers. Synthetic fibers (as well as
regenerated acetate fibers) tend to be thermoplastic, i.e., they
are softened by heat. Therefore, these fibers may be shaped at high
temperatures to add such features as pleats, creases and complex
cross sections. Synthetic fibers may be formed from materials such
as polyamide nylon, polyethylene terephthalatae (PET) or
polybutylene teraphalate (PBT) polyester, phenol-formaldehyde (PF),
polyvinyl alcohol (PVOH), polyvinyl chloride (PVC) and polyolefins
such as polypropylene (PP) and polyethylene (PE).
[0041] The fibers of the wound dressing may be gathered. Gathering
of the fibers may be achieved by any known manner. For example,
gathering of fibers may be achieved by any one or more of the
following methods. The fibers may be gathered by entangling the
fibers; or intermingling the fibers; or wrapping the fibers with
yarn; or thermally bonding the fibers; or ultrasonically treating
the fibers; or radio frequency (RF) bonding; or adhering; or tying;
or combinations of the methods; and the like.
[0042] Furthermore the fibers may be absorbent or non-absorbent
with respect to the wound exudate.
[0043] The fibers may have a denier of about 3 to about 25 deniers
per fiber, in one embodiment, and, in another embodiment, from
about 3 to about 16 deniers per fiber.
[0044] The fibers may be crimped by any known technique such as,
for example, by steam jet crimping, air jet crimping, stuffer box
crimping, or self crimping.
[0045] The fibers may be treated to increase the properties of
wicking and/or hydrophobicity, by any known technique. For example,
the fibers may be treated with PHOBOL 7811 aqueous fluorochemical
dispersion, available from Huntsman Chemicals. The dispersion may
be applied to the fiber using a dip and squeeze padder or similar
application method. The concentration of the dispersion can be
adjusted by dilution with water to adjust the level of dispersion
applied to the fibers. If desired, other suitable treatments
include the use of hydrophobic aqueous binders such as AIRFLEX 140
available from Air Products, silicones, and a polyurethane such as
RU41-773 available from Stahl.
[0046] It is also possible to improve the wicking and/or
hydrophobicity properties of the fibers by using a melt additive
such as HYD-REPEL, available from Goulston Technologies, which
increases the water repellency property of the fibers. All of the
fiber may be treated or a core/sheath fiber may be produced with
the HYD-REPEL melt additive in the sheath.
[0047] The fibers herein may be lofted or opened to increase
apparent density or volume, by any known technique. For example,
one suitable method is described in U.S. Pat. No. 3,328,850. It is
described therein that a material which in the present document, is
a fiber, may be opened by passing the fiber to the nip of a pair of
rolls, one of which has a smooth rubbery surface. The rolls are
moving at a speed faster than the speed of the fibers, and the
fibers leaving the nip are passed through an air-spreading zone, in
which the fibers are confined between two parallel walls. The
fibers are subjected to streams of air from the walls. This is only
one suitable manner of lofting or opening the fibers. Any other
means for lofting or opening the fibers may be utilized
[0048] The fibers may be combined with, or treated with, any
additive or agent that enhances the healing of the wound. For
example, agents such as polyhexamethylene biguanide (PHMB), or any
other medicaments, antimicrobials, wound healing agents, and/or
wound debriding agents, may be used to decrease the incidence of
infection or otherwise promote healing of the wound. Other agents
include those used in slow release treatments wherein the agent is
released from the fiber into the wound over a period of time.
[0049] The fibers may contain additional active ingredients or
agents such as, for example, a therapeutic agent, an organoleptic
agent and a pharmaceutical agent including, for example, an
anti-microbial agent, in growth factor, an analgesic, a tissue
scaffolding agent, a wound debriding agent, a hemostatic agent, an
anti-thrombogenic agent, an anesthetic, an anti-inflammatory agent,
an anticancer agent, a vasodilation substance, a wound healing
agent, an angiogenic agent, an angiostatic agent, an immune
boosting agent, a skin sealing agent, combinations thereof and the
like.
[0050] Suitable anti-microbial agents that can be used include, but
are not limited to, anti-microbial metal ions, a chlorhexidine, a
chlorhexidine salt, a triclosan, a polymoxin, a tetracycline, an
amino glycoside (e.g., gentamicin or Tobramycin.TM.), a rifampicin,
a bacitracin, an erythromycin, a neomycin, a chloramphenicol, a
miconazole, a quinolone, a penicillin, a nonoxynol 9, a fusidic
acid, a cephalosporin, a mupirocin, a metronidazole, a secropin, a
protegrin, a bacteriolcin, a defensin, a nitrofurazone, a mafenide,
an acyclovir, a vanocmycin, a clindamycin, a lincomycin, a
sulfonamide, a norfloxacin; a pefloxacin, a nalidizic acid, an
oxalic acid, an enoxacin acid, a ciprofloxacin, combinations
thereof and the like. In certain embodiments, a preferred
anti-microbial agent can include at least one of polyhexamethylene
biguanide (PHMB), a PHMB derivative such as, for example, a
biodegradable biguanide (e.g., polyethylene hexamethylene biguanide
(PEHMB)), chlorhexidine gluconate, chlorohexidine hydrochloride,
ethylenediaminetetraacetic acid (EDTA), variations of EDTA such as,
for example, disodium EDTA or tetrasodium EDTA, combinations
thereof and the like. In further exemplary embodiments, the
antimicrobial agent can be PHMB.
[0051] The method for treating wounds using the fibers herein is
comprised as follows.
[0052] (a) Providing a wound dressing comprising a plurality of
fibers, each fiber having a length of at least two (2) inches, and
in one embodiment, at least four (4) inches, and in other
embodiments, at least 6 inches, and at least 8 inches;
[0053] (b) Incorporating into the wound to be treated an amount of
the wound dressing that is sufficient to cause the walls of the
wound to remain apart thereby allowing the wound to heal from the
inside to the outside of the wound; and
[0054] (c) Removing exudate from the wound.
[0055] In respect of the method herein for treating a wound, the
fibers of the wound dressing may be absorbent or non-absorbent with
respect to the wound exudate.
[0056] Moreover, as described herein, the fibers of the wound
dressing may have a denier of about 3 to about 25 deniers per
fiber; or may be treated to have increased volume; or may be
treated to have increased wicking ability; or may be crimped; or
may be lofted; or may be combined with, or treated with, an
additive, such as PHMB, that reduces infection of the wound.
[0057] In the method herein, the wound dressing comprising the
fibers herein, is incorporated into a wound in any amount that is
sufficient to cause the walls of the wound to remain apart thereby
allowing the wound to heal from the inside to the outside of the
wound. In one embodiment, the amount of the wound dressing
incorporated into the wound ranges from about 25% based on the
volume of the wound to an amount of wound dressing that exceeds the
volume of the wound. In another embodiment, the amount of the wound
dressing incorporated into the wound ranges from about 50% to about
100% of the volume of the wound and in another embodiment, the
wound dressing is incorporated into the wound in an amount equal to
the wound volume.
[0058] In another embodiment, the wound dressing that is
incorporated into the wound exerts pressure against the walls of
the wound.
[0059] In the method herein, it is required that the wound exudate
be removed from the wound. The wound exudate may be removed from
the wound by any known technique. In one embodiment, where the
fibers of the wound dressing are non-absorbent in respect of the
wound exudate, the wound exudate may be removed by any type vacuum
technique such as negative pressure wound therapy (NPWT). In
another embodiment, where the fibers of the wound dressing are
absorbent in respect of the wound exudate, the wound exudate may be
removed by removing the wound dressing containing the absorbed
wound exudate from the wound. In this instance, removal of the
wound dressing containing the absorbed wound exudate, may be
followed by incorporating a new wound dressing comprised of
absorbent fibers, as needed.
[0060] In one embodiment, an example of a technique that may be
utilized with a wound dressing comprising a non-absorbent fiber is
known as negative pressure wound therapy (NPWT). The wound dressing
comprising non-absorbent fibers may be positioned in a reservoir
above a wound where a negative pressure may be maintained. The
reservoir subjects the wound to a sub-atmospheric pressure to
effectively draw wound fluid, including liquid wound exudate, from
the wound without the continuous use of a vacuum pump. Vacuum
pressure may be applied once, or in varying intervals, depending on
the nature and severity of the wound.
[0061] Various crimping and bulking methods are contemplated to
permit individual fibers or a plurality of fibers to separate in
areas such that the fibers may receive and transport wound fluids.
An air jet crimping process may be used wherein a fiber is directed
past turbulent streams of compressed air to entangle the individual
fibers into a multitude of loops and convolutions. A steam jet
crimping process may also be used wherein a fiber is directed past
turbulent streams of a high temperature steam to not only produce
loops and convolutions, but also to heat set these same loops and
convolutions. Another crimping process is known as stuffer box
crimping. Stuffer box crimping is a process by which a fiber may be
forcibly fed into a crimping chamber having a restricted exit.
Subsequent portions of the fiber entering the crimping chamber will
impart a force causing the fiber to buckle inside the chamber
until, upon emergence from the chamber, the fiber retains a crimp
therein. Any of these crimping processes may be used.
[0062] It is advantageous to utilize as the wound dressing a
plurality of fibers with each fiber having a length of at least two
(2) inches, in the method described herein for treating a wound.
Individual fibers having a length of at least two (2) inches will
have less tendency to separate from the rest of the fibers. This
will minimize loose fibers that might remain in the wound, and
which could cause inflammation or other impairments of the wound
healing. The fibers having a length of at least two (2) inches can
be gathered to further minimize the possibility of loose fibers
remaining in the wound.
[0063] Furthermore, the fibers having a length of at least two (2)
inches can be modified for example. by crimping or chemical
treatment to provide optimum wound properties that are important to
wound healing. These include wound exudate flow, wound exudate
retention, conformance to wound, an antimicrobial properties.
[0064] Referring to FIG. 1, a wound dressing apparatus according to
the present disclosure is depicted generally as 10 for use on a
wound "w" surrounded by healthy skin "s." The apparatus 10 includes
a contact layer 18 placed in contact with the wound "w," a wound
dressing 100 placed into the wound "w" over the contact layer 18
and a cover layer 22 placed in contact with the skin "s" to cover
the wound dressing 100 and wound "w."
[0065] Contact layer 18 may be formed from perforated film
permitting exudates to be drawn through the contact layer 18 into
the wound dressing 100. Passage of wound fluid through the contact
layer 18 may be substantially unidirectional such that exudates do
not tend to flow back into the wound "w." Unidirectional flow may
be encouraged by directional apertures. such as cone-shaped
formations protruding from the film material (see, e.g. FIG. 7).
Arranging the contact layer 18 such that the formations protrude in
the direction of the wound dressing 100 allows for exudates to
encounter the film as an array of cone-shaped formations in the
direction away from the wound "w" and as an array of collecting
basins in the direction toward the wound "W." Unidirectional flow
may also be encouraged by laminating the contact layer 18 with
materials having absorption properties differing from those of
contact layer 18. A non-adherent material may be selected such that
contact layer 18 does not tend to cling to the wound "w" or
surrounding tissue when it is removed. One material that may be
used as a contact layer 18 is sold under the trademark
XEROFORM.RTM. by Tyco Healthcare Group LP (d/b/a Covidien).
[0066] Wound Dressing 100 is positioned in the wound "w" over the
contact layer 18 and is intended to receive and retain wound
exudates. Wound dressing 100 is conformable such that it may assume
the shape of any wound "w" and may be packed up to any level, e.g.
up to the level of healthy skin "s" or to overfill the wound such
that wound dressing 100 protrudes over the healthy skin "s."
[0067] As discussed in greater detail below, the wound dressing 100
may be formed from an assembly of fibers each of which fibers
having a length of at least 2 inches.
[0068] Cover layer 22 may assume a variety of forms typically used
to cover a wound "w" in wound care applications. For example, cover
layer 22 may be formed from a flexible polymeric or elastomeric
film having an adhesive coating on an underside to fasten the film
to the surrounding skin "s." Thus cover layer 22 may serve as a
microbial barrier to help prevent contaminants from entering the
wound "w." In disclosed embodiments, cover layer 42 may be formed
from a moisture vapor permeable membrane to promote the exchange of
oxygen and moisture between the wound "w" and the atmosphere. A
membrane that provides a sufficient moisture vapor transmission
rate (MVTR) is a transparent membrane sold under the trade name
POLYSKIN.RTM.II by Tyco Healthcare Group LP (d/b/a Covidien). A
transparent membrane helps permit a visual assessment of wound
conditions to be made without requiring removal of the cover layer
22. Alternatively, cover layer 22 may comprise an impermeable
membrane 22.
[0069] Referring now to FIG. 1B, the wound dressing 100 of the
present disclosure may also be used in any wound dressing
applications such as a negative pressure wound therapy (NPWT)
apparatus 24. Such an apparatus 24 may include a wound dressing
having a contact layer 18 and wound dressing 100, as described with
reference to FIG. 1A. Cover layer 22 may be particularly adapted
for such an application. For instance, cover layer 22 may include a
substantially continuous band of a biocompatible adhesive at the
periphery 26 such that the adhesive forms a substantially
fluid-tight seal with the surrounding skin. Thus, cover layer 22
may act as both a microbial barrier to help prevent contaminants
from entering the wound "w," and also a fluid barrier to help
maintain the integrity of a vacuum reservoir 28.
[0070] A vacuum port 30 having a flange 34 may also be included to
facilitate connection of the reservoir 28 to a vacuum system. The
vacuum port 30 may be configured as a rigid or flexible,
low-profile component, and may be adapted to receive a vacuum tube
or fluid conduit 36 in a releasable and fluid-tight manner. An
adhesive on the underside of flange 34 may provide a mechanism for
affixing the vacuum port 30 to the cover layer 22, or alternatively
flange 34 may be positioned within reservoir 28 (not shown) such
that an adhesive on an upper side of the flange 34 affixes the
vacuum port 30. However the vacuum port 30 is affixed to the cover
layer 22, a hollow interior of the vacuum port 30 provides fluid
communication between the fluid conduit 36 and the reservoir 28.
Vacuum port 30 may be provided as a pre-affixed component of cover
layer 22, as a component of fluid conduit 36 or entirely
independently. Alternatively, vacuum port 30 may be eliminated if
other provisions are made for providing fluid communication with
the fluid conduit 36.
[0071] Fluid conduit 36 extends from the vacuum port 30 to provide
fluid communication between the reservoir 28 and collection
canister 40. Any suitable conduit may be used for fluid conduit 36
including those fabricated from flexible elastomeric or polymeric
materials. Fluid conduit 36 may connect to the vacuum port 30, the
canister 40, or other apparatus components by conventional
air-tight means such as friction fit, bayonet coupling, or barbed
connectors, for example. The conduit connections may be made
permanent, or alternatively a quick-disconnect or other releasable
means may be used to provide some adjustment flexibility to the
apparatus 10.
[0072] Collection canister 40 may comprise any container suitable
for containing wound fluids. For example, a rigid bottle may be
used as shown, or alternatively a flexible polymeric pouch may be
appropriate. Collection canister 40 may contain an absorbent
material to help consolidate or help contain the wound drainage or
debris. For example, super absorbent polymers (SAP), silica gel,
sodium polyacrylate, potassium polyacrylamide or related compounds
may be provided within canister 40. At least a portion of canister
40 may be transparent or translucent to assist in evaluating the
color, quality and/or quantity of wound exudates. A transparent or
translucent canister may thus assist in determining the remaining
capacity of the canister or when the canister should be
replaced.
[0073] Leading from collection canister 40 is another section of
fluid conduit 36 providing fluid communication with vacuum source
50. Vacuum source 50 generates or otherwise provides a negative
pressure to the NPWT apparatus 24. Vacuum source 50 may comprise a
peristaltic pump, a diaphragmatic pump or other mechanism that is
biocompatible and draws fluids, e.g. atmospheric gasses and wound
exudates, from the reservoir 28 appropriate to help stimulate
healing of the wound "w." In disclosed embodiments, the vacuum
source 40 is adapted to produce a sub-atmospheric pressure in the
reservoir 28 ranging between about 20 mmHg and about 500 mmHg, more
specifically, between about 75 mmHg to about 125 mmHg. One suitable
peristaltic pump is the Kangaroo PET Eternal Feeding Pump
manufactured by Tyco Healthcare Group LP (d/b/a Covidien).
[0074] Referring now to FIG. 2A, the wound dressing 100 of the
present disclosure may generally assume the form of a bundle,
assembly or tow of fibers each of which fibers having a length of
at least 2 inches. The fibers 102 may be arranged 50 as to be
generally non-intersecting along their length. Although not
necessarily parallel, the fibers 102 may be generally free from
entanglement or interlacing. At least one gathering feature 104 may
be included to permit the bundle to help resist separation of
fibers 102. A single gathering feature 104 may be formed from a
separate fiber wrapped or tied around the bundle to compress the
bundle in a localized region. Alternatively, gathering features 104
may be placed intermittently along the bundle, as shown in FIG. 2B,
to help secure the tow at multiple locations, or separate fibers
may be wrapped helically around the bundle as in FIG. 2C to form
gathering feature 106.
[0075] A tow may be enclosed with a self-sealing, non-woven mesh or
other porous sheet to form gathering feature 108. A self-sealing
gathering feature 108 may be an elastic or slightly undersized band
such that fibers 102 may be inserted through an open end of the
band to be constrained under compression. Alternatively, gathering
features 108 may include an adhesive component such that a flat
strip may be wrapped around the tow and the flat strip may be
affixed by adhering either to itself or to the fibers 102 with the
adhesive component. As depicted in FIG. 2E, a gathering feature 110
may be formed with a substantial length of a non-woven mesh or a
porous sheet to enclose a substantial length of the tow.
[0076] As depicted in FIGS. 2F through 2I the fibers 102 may be
arranged or constructed as shown to help permit the tow to resist
separation of fibers 102. Fibers 102 may be twisted as in a rope to
provide a gathering feature 112 (FIG. 2F), or fibers 102 may be
entangled by various processes to form a gathering feature 114
(FIG. 2G). Jets of steam, air or water may be directed at localized
regions in the tow to entangle fibers 102 and provide gathering
feature 114. Another entangling process involves needles used in a
manner similar to needle punching to entangle fibers 102. A
gathering feature 116 (FIG. 2H) may be provided simply by bonding
fibers 102 with an adhesive, or by incorporating a binding material
having a lower melting temperature than the fibers 102. By heating
the tow, the binding material may melt and bind the fibers together
upon cooling. A binding material may be provided along with one or
more of the individual fibers in a co-extrusion such as a
core-sheath arrangement, as described in greater detail below. As
depicted in FIG. 2I, a gathering feature 118 may also be provided
by crimping fibers to provide some degree of entanglement, as
described in greater detail below. It is also envisioned that the
arrangement of fibers 102 may include two or more of the features
shown in FIGS. 2A through 2I.
[0077] Referring to FIGS. 3A through 3G, two or more distinct
polymers may be co-extruded to generate a fiber with specialized
characteristics. For example, a fiber 120 exhibiting a concentric
sheath-core arrangement is depicted in FIG. 3A. A core polymer 122
is surrounded by a sheath polymer 124. As discussed above, sheath
polymer 124 may exhibit a lower melting temperature than core
polymer 122 such that the sheath polymer 124 may be melted to
provide a binder for fibers 102. Other applications for a
sheath-core arrangement may include providing a high strength
structural core polymer 122 and a sheath polymer 24 with surface
characteristics appropriate to help promote wicking of wound fluid
or to accept any of the beneficial polymer additives discussed
below. A fiber 126 exhibiting an eccentric sheath-core arrangement
is depicted in FIG. 3B including an off-center core polymer 128 and
corresponding sheath polymer 130. This arrangement may be used to
provide a self-crimping fiber 126 when the core polymer 128 and
sheath polymer 130 are provided with differing shrinkage
characteristics when subject to a temperature change. When heated,
the fibers 126 may curl into a helix that is retained when the
fiber is cooled, thus developing a crimp or bulk in an otherwise
flat fiber 126. Such a self-crimping procedure may be further
facilitated by using a side-by-side arrangement as depicted in FIG.
3C. Fiber 132 is similar to fiber 126, but differs in that core
polymer 134 and sheath polymer 136 each occupy a portion of the
outer surface of the fiber 132. With a proper polymer selection,
the side-by-side arrangement of fiber 132 may yield higher levels
of latent crimp than the eccentric sheath-core arrangement of fiber
126.
[0078] As shown in FIG. 3D, a fiber 138 having a pie-wedge
arrangement may include alternating wedges comprising polymers 140
and 142. The wedges may be split into the component wedges upon
mechanical agitation. This may assist in forming a gathering
feature 114 as discussed above with reference to FIG. 20. The
component wedges may yield localized areas of microfibers to assist
in entangling the fiber 138. A fiber 144 exhibiting a hollow pie
wedge arrangement including a hollow center core is depicted in
FIG. 3E. Fiber 144 may require less agitation to split into
component polymers 146, 148.
[0079] With reference to FIG. 3F, fiber 150 exhibits an
islands-in-the-sea arrangement where one or more "island" polymers
152 are surrounded by a soluble "sea" polymer 154. This arrangement
may provide for very fine strands of island polymers 152 to be
effectively handled by manufacturing equipment. Once the island
polymers 152 are in place, the soluble sea polymer is dissolved
away. As many as about 37 or more island polymers 152 having a
denier of about 0.04 (roughly 2 microns in diameter) may thus be
handled effectively as a single fiber 150.
[0080] A fiber 156 exhibits a "three island" arrangement, as
depicted in FIG. 30. This arrangement includes three island
polymers 158 surrounded by a sea polymer 160. Fiber 156 may be used
in a manner similar to fiber 150 exhibiting an islands-in-the-sea
arrangement, but may be more commonly used in a manner similar to
fibers 120, 126 and 132 described above exhibiting a sheath-core
arrangement. Fiber 156 may be described as including three core
polymers 158 collectively having an increased surface area to
discourage de-lamination from a potentially incompatible sheath
polymer 160.
[0081] Referring to FIGS. 4A through 4F, individual fibers 102 may
exhibit various cross sections to enhance a wicking capability or
another characteristic of wound filler 100. A solid round cross
section as depicted in FIG. 4A may be a standard for most synthetic
fibers due to a relatively low cost when compared to another
modified cross sections below. A fiber 162 is depicted in FIG. 4B
having a void 164 in its cross section. Void 164 runs the entire
length of the fiber 162 yielding a reduced density and rigidity of
fiber 162 and permitting air to be trapped within. Such a cross
section may facilitate crimping, entangling and/or lofting
processes.
[0082] A multi-lobal cross section may also be used as depicted in
FIG. 4C. Tri-lobal fiber 168 exhibits three arms 170 projecting
from a central region offering rigidity and resilience to the wound
dressing 100. A ribbon cross section as exhibited by fiber 174
depicted in FIG. 4D may be described as exhibiting a bi-lobal
arrangement. A ribbon cross section offers a bending direction and
shape well suited for segmented fibers which may be split into
micro-fibers as described above with reference to FIGS. 3D and 3E.
Such a cross section may be split into micro-fiber components with
relatively minor agitation when compared to other cross
sections.
[0083] Highly modified cross section fibers 178 as depicted in FIG.
4E are sold under the trade name 4DG.TM. by Fiber Innovation
Technology, Inc. Deep channels 180 of various sizes and
configurations are provided along a longitudinal axis of the fiber
178 to help promote capillary wicking with its relatively large
surface area. Fibers 172 having a 4DG.TM. cross section have
demonstrated a capability to transport up to 2 liters of water per
hour per gram of fiber.
[0084] A fiber 184 having a bowtie cross section as depicted in
FIG. 4F may be well suited for use in a self-crimping fiber as
described above with reference to FIG. 3B and FIG. 3C. Polymers
with differing thermal characteristics may be arranged such that
the centers of mass of the two polymers are separated by a
relatively greater distance than other cross sections. A fiber 184
thus arranged may exhibit enhanced stretch recovery of the helical
coils formed by heating and subsequently cooling the fiber 184.
[0085] Self crimping may be accomplished with an eccentric
core-sheath arrangement of polymers described above with reference
to FIG. 3B or a side-by-side arrangement as described with
reference to FIG. 3C. Another option to produce a self crimping tow
is to combine full fibers of differing thermal characteristics in a
creeling process. The crimped tow may be opened, i.e., the crimped
fibers may be separated or spaced, to produce a particular texture
or bulk. The crimped tow may be opened by air jets, or by
longitudinal stretching and relaxing of the tow with a threaded
roll assembly.
[0086] Referring now to FIG. 5, a negative wound pressure therapy
apparatus according to the present disclosure is depicted generally
as 200. Apparatus 200 includes a wound dressing assembly 202
defining reservoir 28 in fluid communication with vacuum source 50
as described above with reference to FIG. 1B. Wound dressing
assembly 202 includes an elongate wound packing structure 210
comprising a core 212 substantially surrounded by a sheath 214. The
core 212 may be formed from a dressing or filler material adapted
for receiving and/or transporting wound exudates, and may include
any material or structure described above with reference to FIG. 1A
for use with wound dressing 100. The sheath 214 may be formed from
a contact material 214 adapted for positioning in contact with the
wound "w," and may include any material or structure described
above with reference to FIG. 1A for use with contact layer 18. The
sheath 214 is permeable to permit passage of wound fluids into and
out of the core 212 of filler material. The packing structure 210
may be embodied as an elongate tube arranged to follow a winding
path to substantially fill the wound "w" and conform to the
particular geometry of the wound "w." Such an elongate tube may be
provided in continuous lengths that may be conveniently cut at the
time wound dressing assembly 202 is applied to accommodate the
particular size of the wound "w." Such an arrangement may not
require separate and independent sizing and subsequent application
of a wound contact layer 18 and wound dressing 100.
[0087] Referring now to FIGS. 6A through 6C, various configurations
contemplated for a packing structure for use in NWPT apparatus 200
(FIG. 5) are depicted. As depicted in FIG. 6A, packing structure
210 defines an elongate tube having a length "L" extending in a
longitudinal direction and a maximum width "A" extending in a
lateral direction. The oblong cross section of packing structure
210 is substantially consistent along the length "L" of the packing
structure 210. Other cross sections may be appropriate such as a
round, hexagonal or other polygonal shapes. The sheath 214 may be
formed by an extrusion or similar process providing for a seamless
circumference around the core 212.
[0088] Packing structure 220, depicted in FIG. 6B, includes a core
of filler material 222 substantially surrounded by a sheath of
contact material 224. A plurality of longitudinally spaced
separation features 226 provide for dividing the packing structure
220. A separation feature 226 may comprise a perforated tear line
extending laterally across packing structure 220, which a clinician
may use to cut or tear away a portion of the packing structure 220
such that packing structure 220 has an appropriate length to fill a
wound "w" of a particular size. Separation features 226 may be
spaced apart, for example, by a distance "D" of from about 50
percent to about 300 percent of a width "B" of the packing feature
220.
[0089] A series of pods 228 may be defined between adjacent
separation features 226. Each pod 228 may have an open
configuration wherein the core of filler material 222 extends
between adjacent pods through the separation features 226. A
portion of the dressing material 222 may thus be exposed across a
lateral edge of the packing structure 220 when an adjacent pod 226
is removed. Alternatively, each pod 228 may have a closed
configuration where in the core of filler material 222 is
interrupted in the vicinity of the separation feature 226. For
example, the sheath of contact material 224 may be sealed to itself
on the interior of packing structure 220 in the vicinity of the
separation feature 226, such that the sheath of contact material
224 extends along opposite lateral edges of the pods 228. Such an
arrangement of closed pods 228 may provide an area of increased
flexibility in the vicinity of the separation feature 226 when
compared to a central region of the pods 228. An area of increased
flexibility may facilitate placement of packing structure 220 in a
winding arrangement within the wound "w."
[0090] Referring now to FIG. 6C, packing structure 230 includes a
core of filler material 232 substantially surrounded by a sheath of
contact material 234. A separation feature 236 may comprise a slit
or series of longitudinally spaced slits extending laterally across
packing structure 230. Slits 236 may extend partially into the
filler 232 such that the packing structure 230 is less resistant to
cutting or tearing in the vicinity of the slits 236. The sheath of
contact material 234 may be arranged with an overlap 238. Overlap
238 may facilitate application of a longitudinal adhesive bond,
ultrasonic weld or similar seal to facilitate assembly of packing
structure 230.
[0091] Referring now to FIG. 7A and FIG. 7B, packing structure 240
includes a core of filler material 242 substantially surrounded by
a sheath of contact material 244. The sheath of contact material
244 includes upper and lower sheets 244U and 244L of contact
material with a heat seal 246 formed around the periphery of the
sheath 244 to encapsulate the filler 242 therein. An adhesive bond,
ultrasonic weld; or similar seal may be incorporated as an
alternative or in combination with heat seal 246 to encapsulate the
filler 242. Packing structure 240 is a generally round, saucer or
puck shaped capsule, but may alternatively be formed into a variety
of shapes including spheres, cylinders, cubes, tetrahedrons and
other polygonal shapes.
[0092] Filler 242 assumes the form of a polypropylene tow. A tow
may be described as a loose, essentially untwisted strand of a
large number of unidirectional synthetic fibers. Continuous
filament polypropylene fibers may be arranged to form a loosely
entangled ball to form a filler 142 capable of receiving wound
exudates. The tow may be crimped, bulked or lofted to influence the
absorptive, wicking or comfort characteristics of the filler 142.
Various such processes and arrangements for the tow of filler 242
are described above with reference to FIGS. 2A through 4F.
[0093] Sheath 244 is formed from a non-adherent,
directionally-apertured polyolefin film such as those manufactured
by Tredegar Film Products, Corp. of Richmond, Va. These films are
safe for contact with a wound "w" and permit fluid to flow into the
filler 242. Unidirectional flow is encouraged through such a film
by apertures formed at the peak of cone-shaped formations in the
film material that project in one direction. Such a film will thus
have a male side, as depicted in FIG. 7C, and an opposite female
side. Fluid flow is encouraged across the film from the female side
to the male side and discouraged in the opposite direction. Sheath
244 may be arranged such that the male side of such a film faces
the interior of packing structure 240 from all directions. Fluid is
thus encouraged to flow into the filler 242 regardless of the
orientation in which the packing structure 240 is placed in the
wound "w." Alternatively, the lower sheet 244L of sheath 244 may be
oriented such that the male side faces the interior of the packing
structure 240; while the upper sheet 244U of sheath 244 is oriented
such that the male side faces the exterior of the packing structure
240. This arrangement encourages unidirectional flow through the
entire packing structure 240. By placing packing structure 240 into
the wound "w" with an orientation such that the lower sheet 244L in
contact with the wound "w," wound fluids may be encouraged to flow
into packing structure 240 by the directional apertures in the
lower sheet 244L, and subsequently wicked through filler 242 to the
upper sheet 244U where the directional apertures encourage flow out
of the packing structure 240. Wound fluids may then be removed from
wound dressing assembly 202 by vacuum source 50 and deposited in
canister 40 (FIG. 5). Regardless of the orientation of upper and
lower sheets 244U and 244L, sheath 244 should be pliable and soft
when heat sealed such that packing structure 240 does not cause
pain to the patient when placed inside a wound "w."
[0094] Referring now to FIG. 8A and FIG. 8B, packing structure 250
includes a core of filler material 252 substantially surrounded by
a sheath of contact material 254. A plurality of ring-shaped
interior heat seals 256 are formed in a generally concentric
arrangement between discrete segments of the filler material 252,
thus dividing the packing structure 250 into a number of pods. A
central pod 258 lies in the center of the packing structure 250,
and is encircled by progressively larger ring-shaped pods 260, 262
toward the circumferential regions of the packing structure 250. An
exterior heat seat 264 is formed around the periphery of packing
structure 250 to close the outermost pod 262. A perforated ring 268
is formed on each of the interior heat seals 256 to provide a
separation feature for the pods.
[0095] Although packing structure 250 is depicted as including only
three distinct pods 258, 260 and 262, any number of pods may be
formed into such an arrangement to form a packing structure of any
desired size. Heat seals 256, 264 may have a width "X" of about 1
cm or less, and may be separated by a distance "Y" of about 1 inch
to about 2 inches. In use, when the size of a particular wound "w"
is assessed, outer pods, e.g. 262, may be removed using perforated
ring 268 to permit packing structure 250 to assume an appropriate
size for the wound "w."
[0096] To manufacture a structure such as packing structure 240 and
250, a mold "m" may be formed as depicted schematically (in
cross-section) in FIG. 9A. The mold "m" may include indentations
"i" on an upper surface thereof, which are sized and spaced
appropriately to form a desired number of pods. The mold depicted
in FIG. 9A may be used to form a packing structure with four
distinct pods including a central pod and three surrounding ring
shaped pods.
[0097] A flat sheet of sheath material 254L may be placed over the
mold "m" (FIG. 9B) with a male side facing up. A
directionally-apertured film such as those manufactured by Tredegar
Film Products may be provided with, or marked with a distinguishing
color on each side such that a proper orientation of the sheet may
be verified. The sheet of sheath material 254L may then be drawn
into the indentations "i" (FIG. 9C). Airflow may be directed
through the mold "m" to draw in the sheath material 254L, or the
sheath material 254L may be urged into place by any other suitable
means.
[0098] Next, the filler material 252 may be positioned in the
indentations "i" over the sheath material 254L, and may be arranged
to overfill the indentations as depicted in FIG. 90. A central
indentation "i" may accommodate an entangled mass of polypropylene
tow while surrounding indentations "i" may be conveniently filled
by a twisted or spun rope of the tow material arranged in a
circular fashion.
[0099] Another sheet of the sheath material 254U may be placed over
the filler 252, and may be drawn downward into the intermediate
spaces between the indentations in the mold "m" (FIG. 9E). The male
side of the upper sheet of sheath material 254U may face downward
toward the filler, and toward the male side of the lower sheet of
sheath material 254L. An appropriate heat sealer "h" (FIG. 9F)
having appropriately sized heat sealing rings may then be pressed
down into each of the intermediate spaces to form interior heat
seals 256, and another heat sealing ring may similarly form
exterior heat seal 264. The heat sealing rings may include a
Teflon.RTM. or similar coating such that the sheath material 254U
does not tend to stick to the heat sealing rings. The heat sealing
rings may alternately be applied individually, or the heat seals
256, 264 may be replaced by seals formed with a laser or ultrasonic
welding mechanism that traverses a path around the filler 252 to
encapsulate the filler 252.
[0100] Once the filler 252 has been encapsulated, the filler and
the sheath material may be removed from the mold "m" for further
processing. For example, the structure may be delivered to another
apparatus for forming perforated rings 268 to complete the packing
structure. Alternatively, the mold "m" or the heat sealer "h" may
include a perforating mechanism (not shown) to form perforated
rings 268 along with the formation of the heat seals 256, 264.
[0101] A variety of other embodiments of a packing structure may be
formed with minor variations to the process described above. For
example, the filler 252 may not necessarily overfill the
indentations "i," but may be fill the indentations "i" up to the
level of the top surface of the mold "m." Also, the upper layer of
sheath material 254U may be replaced with a material that is
dissimilar to the lower layer of sheath material. For example, the
lower layer of sheath material 254L may be formed of a
directionally-apertured polyolefin film while the upper layer may
be formed of a porous or nonporous sheet of a polypropylene.
[0102] Referring now to FIG. 10A, packing structure 260 includes a
core of filler material 262 substantially surrounded by a sheath of
contact material 264. Similarly to sheath 244 discussed above with
reference to FIG. 7B, the sheath of contact material 264 includes
upper and lower sheets 264U and 264L of contact material with a
seal 246 formed around the periphery to encapsulate the filler 262
therein. The upper and lower sheets 264U and 264L may be formed
from a directionally-apertured film and may be oriented as
discussed above. Filler 262 may be distinguished in that filler 262
is formed from at least two distinct materials.
[0103] Filler 262 comprises a layer of polypropylene tow is
designated 262T, and a layer foam is designated 262F. Tow layer
262T may take any form discussed above with reference to FIG. 7A,
and foam layer 262F may be formed from a resilient, open-cell foam
such as polyurethane, polyester or polyolefin foam. Foam layer 262F
may be effective to receive wound fluids from the wound, and may
also readily release the wound fluids such that they may be removed
from a dressing assembly 202 by a vacuum source 50 (see FIG. 5).
Foam layer 262F exhibits uniform compression when subject to the
evacuation cycles of an NWPT treatment such that potentially
painful pressure points in the packing structure 260 are managed
and the periphery of the wound "w" may be drawn inward evenly. The
foam layer 262F may be positioned adjacent the lower sheet 264L of
sheath 264 as depicted in FIG. 10A to provide a cushion to the
wound bed. Alternative structures include a packing structure 270,
which may include a filler 272 having a foam layer 272F on each
side of a tow layer 272T. Packing structure 280, also includes a
filler 282 having a foam layer 282 on each side of a tow layer
282T. A hole 282H is formed in each foam layer 282 to promote the
flow of exudates through the packing structure 280.
[0104] Referring now to FIG. 11, packing structure 290 includes a
core of filler material 292 substantially surrounded by sheath of
contact material 294. A seal 296 is formed in the sheath of contact
material 294 such that a plurality of pods 298 are formed in a two
dimensional array. Pods 298 may vary in size, but are preferably
about 1.25 inches in length by about 1.25 inches in width or
smaller to provide a customizable packing structure 290. Depending
on the particular dimensions of a wound "w" unnecessary pods 298
may be cut away to accommodate smaller wounds "w," or pods 298 may
be folded onto one another along the seal 296 to accommodate deeper
wounds "w." Perforations (not shown) may be formed in the sheath
294 along the seal 296 to provide a separation feature to
facilitate removal of unnecessary pods 298. Alternatively, sheath
294 may be free of perforations to increase the strength and
integrity of packing structure 290 inside a wound "w." A separation
feature may thus be provided by creating a seal 296 wide enough to
be readily cut by a clinician without inadvertently cutting into
the core of filler 292. A packing structure 290 without
perforations helps to insure individual pods 298 do not
inadvertently become detached from the packing structure 290, and
thus decreases the probability that a pod 290 will be inadvertently
left in the wound "w."
[0105] According to another aspect of the disclosure, a wound
filler matrix 300 of the present disclosure as depicted in FIG. 12
incorporates at least one continuous fiber comprising either
natural or man-made filaments to form a structure suitable for
conveying, transferring, and/or absorbing exudates. As indicated
above, continuous filaments include those relatively long strands
of a synthetic material such as nylon, rayon, etc., which may offer
a smooth continuous outer surface substantially free of the
protruding fibrils commonly associated with natural materials such
as cotton. Because of the relatively smooth surfaces, structures
such as fabrics or yarns formed from continuous filaments have a
substantially lower tendency to become attached to a healing wound
bed than do structures formed from natural filaments. Also, because
of the relatively long length, continuous filaments have a
substantially lower tendency to become separated from a structure
and be inadvertently deposited in a wound as the dressing is
changed.
[0106] The wound filler matrix 300 of the present disclosure may
generally assume the form of a bundle, assembly, or tow of a
continuous fiber. As illustrated in FIG. 12, the wound filler
matrix 300 defines a length along longitudinal axis "x" about which
at least one fiber 301 is disposed. Fiber 301 may be configured in
a plurality of loop segments 303 which are arranged to traverse
longitudinal axis "x." A connecting segment 305 extends along
longitudinal axis "x" and is connected to at least several,
possibly, all of the loop segments 303. Connecting segment 305 may
be parallel or coincident to longitudinal axis "x". Connecting
segment 305 may be stitched, pulled; tied, gathered, adhered (FIG.
12A) or otherwise passed through (FIG. 12B) and about fiber 301 to
shape loop segments 303 and provide the structure to matrix 300.
Connecting segment 305 may extend beyond the effective length of
fiber 301 thereby providing an extension 307 or handle which may be
grasped by the clinician to facilitate placement and/or removal of
the wound filler matrix 100 relative to the wound bed. The
connecting segment 305 prevents the filament(s) and/or fibril(s) of
the fiber from releasing from matrix 300 thereby minimizing the
potential of the filaments remaining in the wound "w" upon removal
of the material therefrom.
[0107] Wound filler matrix 300 may be severed at any predetermined
longitudinal location to accommodate wounds of various sizes. With
this arrangement, multiple size wounds may be accommodated with a
single matrix 300. In addition, wound filler matrix 300 may be cut
to provide a specific dimensioning to accommodate a specific wound
type, e.g., for a tunneling or deep wound. It may be desirable to
sever the matrix at a location along the longitudinal axis (e.g.,
location "k") such that a portion 305a of connecting segment 305
extends from the last loop. This may facilitate placement and/or
subsequent removal of the reduced matrix segment 300a. Wound filler
matrix 300 may be severed at several locations along the
longitudinal axis "x" depending on the overall length of the wound
filler matrix 300 provided and the wound type and/or size.
[0108] The fibers 301 of wound filler matrix 300 may be formed from
mono- or multi-filaments 302. A monofilament, or a single strand of
material of a sufficient thickness to be directly woven into matrix
300. A multifilament is more than one strand of material that has
been twisted, bonded, or otherwise placed together to form a fiber
as illustrated above in FIGS. 2A-2I. Each of the embodiments of
fiber 301 depicted in FIGS. 13A-13I correspond to the multifilimant
arrangements of FIGS. 2A-2I, and may be arranged in the sinusoidal
configuration depicted in FIG. 12 and attached via a connecting
segment 305.
[0109] The filaments 102 of wound filler matrix 100 may take a wide
variety of forms. Materials may be classified generally into two
basic types including natural fibers and man-made fibers. Further,
natural and man-made fibers include both absorbent and
non-absorbent varieties as within the purview of those skilled in
the art. Natural fibers are those produced by plants, animals
and/or geologic processes. For example, natural fibers include
vegetable fibers, which may be generated from arrangements of
cellulose and bound together by lignin as in cotton, hemp, jute,
flax, ramie and sisal, for example. Also, wood fibers are derived
from tree sources and include groundwood, thermomechanical pulp
(TMP) and bleached or unbleached kraft or sulfite (sulphite) pulps
formed by a manufacturing process wherein lignin is removed to free
the fibers from the wood structure. Animal fibers consist largely
of proteins and include spider silk, sinew, catgut, wool and hair
such as cashmere, mohair and angora, for instance. There are also
mineral sources for natural fibers such as wollastinite,
attapulgite, halloysite, and asbestos.
[0110] Man-made fibers include regenerated fibers and synthetic
fibers.
[0111] Regenerated fibers are those fabricated from natural
materials by processing these materials to form a fiber structure.
For example, regenerated fibers may be derived from the pure
cellulose in cotton and wood pulp to form such products as Rayon
and cellulose acetates. Fibers may also be regenerated from mineral
sources such as glass or quartz to form fiberglass or optical
fibers. Ductile metals such as copper gold or silver may be drawn
to form metallic fibers, and more brittle materials such as nickel
aluminum or iron may be extruded or deposited.
[0112] Synthetic fibers are made entirely from synthetic materials
such as petrochemicals, and are usually stronger than either
natural or regenerated fibers. Synthetic fibers (as well as
regenerated acetate fibers) tend to be thermoplastic, i.e., they
are softened by heat. Therefore, these fibers may be shaped at high
temperatures to add such features as pleats, creases and complex
cross sections. Synthetic fibers may be formed from materials such
as polyamide nylon, polyethylene terephthalatae (PET) or
polybutylene teraphalate (PBT) polyester, phenol-formaldehyde (PF),
polyvinyl alcohol (PVOH), polyvinyl chloride (PVC) and polyolefins
such as polypropylene (PP) and polyethylene (PE).
[0113] Connecting segment 305 of wound filler matrix 300 may also
take a wide variety of forms including the types and materials
described above. Connecting segment 305 may be formed from the same
or a different material as fiber 101.
[0114] Various suppliers may produce filaments as described above,
as any commercial fiber or suture material may advantageously be
employed in wound matrix 300. A non-exhaustive list of materials
includes, but are not limited to, polymers and polymer blends
selected from the group consisting of polyolefins (such as
polyethylene and polypropylene including atactic, isotactic,
syndiotactic, and blends thereof as well as, polyisobutylene and
ethylene-alphaolefins copolymers, and fluorinated polyolefin such
as polytetrafluoroethylene); polyesters (such as polyethylene
terephthalate and polybutylene terephthalate); acrylic polymers and
copolymers; modacrylics; vinyl halide polymers and copolymers (such
as polyvinyl chloride); polyvinyl ethers (such as polyvinyl methyl
ether); polyvinylidene halides (such as polyvinylidene fluoride and
polyvinylidene chloride); polyacrylonitrile; polyvinyl ketones;
polyvinyl aromatics (such as polystyrene); polyvinyl esters (such
as polyvinyl acetate); copolymers of vinyl monomers with each other
and olefins (such as etheylene-methyl methacrylate copolymers,
acrylonitrile-styrene copolymers, ABS resins and ethylene-vinyl
acetate copolymers); polyamides (such as nylon 4, nylon 6, nylon
6.6, nylon 610, nylon 11, nylon 12 and polycaprolactam); alkyd
resins; polycarbonates; polyoxymethylenes; polyimides; polyethers;
epoxy resins; aramids, polyurethanes; rayon; rayon-triacetate; and
spandex.
[0115] Various polymer additives may be applied to individual mono-
or multi-filaments 102, any of the filaments described above or a
matrix 300 to enhance the healing of wound "w." For example, agents
such as polyhexamethylene biguanide (PHMB) or other medicaments,
antimicrobials, wound healing agents and wound debriding agents may
be used to decrease the incidence of infection or otherwise promote
healing of the wound "w." Such agents may include those agents for
use in slow release treatments wherein the agent is released from
the matrix material into the wound over time. Hydrolysis
stabilizers may be incorporated to control the release of an agent
or to maintain the integrity of the tow. Also, wetting agents may
be applied to promote a moist wound environment.
[0116] Other additives may facilitate the removal of matrix 100
from the wound. For example, silicone or floropolymers such as PTFE
may be added to provide filaments 102 with a slicker surface. A
slicker surface may help allow the tow to conform comfortably to
the shape of the wound "w." Still other additives may facilitate
construction of the wound filler matrix 100 such as compatibilizers
and adhesion promoters. Still other additives such as phase change
materials, nanoparticles, UV-absorbers and sunblocks, stain
resistant agents or flame retardants may find additional utility
when in a wound matrix 300.
[0117] There are various types of manufacturing processes for the
combination of multifilaments with one another to form the fiber.
It may be convenient to supply each of the filaments to be combined
coiled onto a spool to help provide the capability of continuous
feeding of substantial lengths of the coiled filaments. The spools
are normally mounted in an array which is commonly referred to as a
creel. A creel may include a plurality of spindles projecting in a
vertical direction from a base frame to accept spools with an
internal void, such that the spools may spin about the spindles to
pay out a length of the filament. Such a manufacturing process
provides an opportunity to combine filaments to produce a tow with
specific characteristics. One or more of the spools may simply be
stocked with a filament having differing characteristics than other
spools on the creel.
[0118] Filaments of differing denier per filament, e.g., 3, 11, or
18 denier per filament, may be combined to produce a fiber with a
specific total denier, e.g., from about 1000 to about 10,000. The
denier per filament may be conveniently adjusted to control fluid
flow properties and the resiliency of matrix 100 when subject to
application or removal pressure. Also, an exact number of filaments
having a relatively low melting temperature may be incorporated
into a creeling process to provide precise control over the
adhesive properties that such filaments may provide when melted.
Mixing of different polymers such as polypropylene with high
tenacity PET is contemplated to control tow characteristics such as
strength and wicking capability of a tow. A single filament or any
number of filaments coated with an additive or healing agent
described above may be incorporated into a fiber to promote healing
of the wound "w." Any number of combinations of any of the
filaments described above in any quantity may be assembled to
produce a tow with the exact characteristics desired.
[0119] Also, other materials or similar materials arranged in a
differing manner may be inserted into a fiber in a creeling
process. For instance, porous membrane tubes may be inserted into
or over a multifilament fiber to provide a bonding feature. Also
twisted filaments, filaments with differing crimp patterns, or
crimp patterns with differing spacing may be combined to form a
fiber for use as matrix 300.
[0120] Various crimping and bulking methods are contemplated to
permit the fiber of a tow to separate in areas such that the tow
may receive and transport wound fluids. An air jet, or steam jet
crimping process, or any of the crimping processes described above
may be used to impart an S- or Z-type crimp to the fiber. These S-
and Z-type crimps refer to a direction of crimping such that the
crimped fiber form a zig-zag pattern that resembles either letter
"S" or letter "Z."
[0121] Self crimping may be accomplished with an eccentric
core-sheath arrangement of polymers described above with reference
to FIG. 3B or a side-by-side arrangement as described with
reference to FIG. 3C. Another option to produce a self crimping
fiber is to combine full filaments of differing thermal
characteristics in a creeling process. The crimped fiber may be
opened, i.e., the loop segments of crimped fiber may be separated
or spaced, to produce a particular texture or bulk. The loop
segments of crimped fiber may be opened by air jets, or by
longitudinal stretching and relaxing of the fiber with a threaded
roll assembly.
[0122] An embodiment of the present disclosure comprises a
multifilament fiber tow formed from primarily round cross section
polypropylene filaments with a denier per filament from about 6 to
about 10, e.g., about 8. The fiber may be crimped with either an S
or Z-type crimp, and the loop segments may be lofted or opened by
air jets or by stretching and relaxing. The fiber may be creeled
from multi-filament yarns including a sufficient number of
individual filaments to exhibit a yarn denier of about 300. About
100 spools of the about 300 denier yarns may be creeled to form a
total tow denier of about 30,000. The yarns on about 30 of the
spools may be treated with an antimicrobial such as PHMB, while the
yarns on the remaining about 270 spools may be untreated. The fiber
may be encapsulated in a spun polypropelene non-woven web to
minimize the effect of loose filaments protruding from the tow.
Alternatives include a similar fiber subject to air jet
entanglement rather than encapsulation, and also a fiber in which
substantially all of the yarns or filaments are treated with
PHMB.
[0123] One-piece removal of such a tow from a wound "w" may be thus
ensured where dressing material remaining in the wound "w" might
otherwise go unnoticed.
[0124] 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. For example, it is envisioned that the wound filler matrix
300 may be used independent of the other components of the wound
dressing 10 or may be used in combination with cover layer 22
and/or contact layer 18. Wound filler matrix 300 may be used as a
wound bandage in the absence of negative pressure therapy, e.g., as
a wound covering in a conventional application. Other uses are also
envisioned.
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