U.S. patent number 3,896,802 [Application Number 05/462,471] was granted by the patent office on 1975-07-29 for flexible flocked dressing.
This patent grant is currently assigned to American Cyanamid Company. Invention is credited to Bernard Leo Williams.
United States Patent |
3,896,802 |
Williams |
July 29, 1975 |
Flexible flocked dressing
Abstract
A wound surface is protected by a wound dressing consisting of a
moisture permeable elastomeric film whose moisture permeability is
in the order of that of the intact human skin to which is
adhesively flocked a layer of tissue compatible and tissue
absorbable fibers, such as polyglycolic acid. All tissue contacting
material is absorbable by living tissue so that any material which
is trapped within the wound is absorbable.
Inventors: |
Williams; Bernard Leo
(Martinville, NJ) |
Assignee: |
American Cyanamid Company
(Stamford, CT)
|
Family
ID: |
23836528 |
Appl.
No.: |
05/462,471 |
Filed: |
April 19, 1974 |
Current U.S.
Class: |
602/43;
602/48 |
Current CPC
Class: |
A61F
13/00046 (20130101); A61F 13/00038 (20130101); A61L
15/64 (20130101); A61L 15/26 (20130101); A61L
15/26 (20130101); C08L 67/04 (20130101); A61F
2013/00561 (20130101); A61F 2013/00876 (20130101); A61F
2013/51411 (20130101); A61F 2013/00727 (20130101); A61F
2013/00157 (20130101); A61F 2013/00263 (20130101); A61F
2013/00519 (20130101); A61F 2013/530992 (20130101); A61F
2013/0091 (20130101); A61F 2013/51186 (20130101); A61F
2013/51355 (20130101) |
Current International
Class: |
A61F
13/00 (20060101); A61L 15/16 (20060101); A61L
15/26 (20060101); A61L 15/64 (20060101); A61F
13/15 (20060101); A61L 015/00 () |
Field of
Search: |
;128/149,153-157,325
;161/64 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Trapp; Lawrence W.
Attorney, Agent or Firm: Walker; Samuel Branch
Claims
I claim:
1. A wound dressing for the surface of living tissue from which at
least part of the skin has been removed and which tissue is subject
to moisture loss, and bacterial contamination, which dressing is
sufficiently flexible that it will conform and adapt to the surface
of the tissue to minimize pools of fluid or air between the
dressing and the tissue surface, which pools generate problems of
infection, and which has a permeability to moisture of the order of
that of the intact human skin (approximately 2.2 mg/sq. cm./hr.)
which comprises: an elastomeric layer which elastomeric layer has
adhesively flocked to its surface a layer of fibers and which
fibers are of a tissue compatible material which is substantially
absorbed by living tissue within about 90 days, and which fibers
maintain their integrity for at least about 3 days.
2. A wound dressing for the surface of living tissue from which at
least part of the skin has been removed and which tissue is subject
to moisture loss, and bacterial contamination, which dressing is
sufficiently flexible that it will conform and adapt to the surface
of the tissue to minimize pools of fluid or air between the
dressing and the tissue surface, which pools generate problems of
infection, and which has a permeability to moisture of the order of
that of the intact human skin (approximately 2.2 mg/sq. cm./hr.),
which comprises: an elastomeric layer of the order of 2 mils thick,
and which elastomeric layer has adhesively flocked to its surface a
layer of fibers of the order of 1 to 12 denier, and about 10 to 30
mils long, and which are predominantly at about right angles to the
elastomeric layer, and which fibers are of a tissue compatible
material which is substantially absorbed by living tissue within
about 90 days, and which fibers maintain their integrity for at
least about 3 days.
3. The wound dressing of claim 2 in which the tissue compatible
material is a polymer subject to hydrolytic degradation to
non-toxic, tissue compatible absorbable components, said polymer
having glycolic acid ester linkages.
4. The wound dressing of claim 3 in which the tissue compatible
material is homopolymeric polyglycolic acid.
5. The wound dressing of claim 3 in which the tissue compatible
material is a polymer of 3-methyl-1,4 dioxane-2,5-dione.
6. The wound dressing of claim 2 in which the tissue compatible
material is a polymer of N-acetyl-D-glucosamine.
7. A sterile wound dressing package comprising an interiorly
sterile strippable laminate container having therein
a wound dressing for the surface of living tissue from which at
least part of the skin has been removed and which tissue is subject
to moisture loss, and bacterial contamination, which dressing is
sufficiently flexible that it will conform and adapt to the surface
of the tissue to minimize pools of fluid or air between the
dressing and the tissue surface, which pools generate problems of
infection, and which has a permeability to moisture of the order of
that of the intact human skin (approximately 2.2 mg/sq. cm./hr.)
which comprises:
an elastomeric layer which elastomeric layer has adhesively flocked
to its surface a layer of fibers and which fibers are of a tissue
compatible material which is substantially absorbed by living
tissue within about 90 days, and which fibers maintain their
integrity for at least about 3 days.
8. A method for protecting the surface of living tissue during a
healing process which comprises: during a preliminary period,
covering and protecting the surface of damaged tissue by emplacing
thereon
a wound dressing for the surface of living tissue from which at
least part of the skin has been removed and which tissue is subject
to moisture loss, and bacterial contamination, which dressing is
sufficiently flexible that it will conform and adapt to the surface
of the tissue to minimize pools of fluid or air between the
dressing and the tissue surface, which pools generate problems of
infection, and which has a permeability to mositure of the order of
that of the intact human skin (approximately 2.2 mg/sq. cm./hr.),
which comprises: an elastomeric layer of the order of 2 mils thick,
and which elastomeric layer has adhesively flocked to its surface a
layer of fibers of the order of 1 to 12 denier, and about 10 to 30
mils long, and which are predominantly at about right angles to the
elastomeric layer, and which fibers are of a tissue compatible
material which is substantially absorbed by living tissue within
about 90 days, and which fibers maintain their integrity for at
least about 3 days,
permitting granulation tissue to regenerate thereunder to give a
clean wound closed by said dressing,
stripping off said dressing to expose granulation tissue,
then autografting living skin to said exposed granulation
tissue.
9. The process of claim 8 in which the tissue compatible material
is homopolymeric polyglycolic acid.
Description
BACKGROUND OF THE INVENTION
The primary concerns is with the treatment of human patients and,
to some extent, animals, which have incurred severe burns or tissue
damage which leaves a substantially exposed wound. One purpose is
to convert the contaminated and open wound to a clean and closed
wound in the shortest time possible.
It has been customary to use cadaver skin or porcine skin among
others to protect wounds and to aid in the development of
granulation tissue prior to autografting.
The wound dressing should decrease pain, reduce protein loss,
reduce evaporative heat and water losses from the wound surface and
prevent further contamination. It is desirable that the use of the
dressing results in decreasing existing bacterial growth in the
wound. At times a bleeding wound or wound losing plasma rapidly is
present as a part of a larger wound and the dressing should aid in
minimizing blood or plasma loss. It is desirable that the dressing
remain flexible and adherent to the wound at all times and be
sufficiently flexible to permit at least some flexing of the wound
surface. The desired degree of flexing to some extent varies with
the location of the wound. For example, a wound surface adjacent a
joint should preferably have greater flexibility than a wound
adjacent a less flexed area such as the chest or back.
In general, the requirements for a wound dressing, particularly a
burn dressing, are known and recognized.
DESCRIPTION OF THE PRIOR ART
The use of polyglycolic acid is disclosed in a series of patents
and applications to Schmitt, et al.:
U.S. Pat. No. 3,297,033, Schmitt and Polistina, Jan. 10, 1967,
SURGICAL SUTURES, discloses polyhydroxy-acetic ester absorbable
sutures. The material is also called polyglycolic acid, and is
disclosed as permitting small quantities of comonomers to be
present, such as dl-lactic acid, its optically active forms,
homologs and analogs. A small quantity is recognized by the art as
up to 15%, as shown by U.S. Pat. No. 2,668,162, Lowe, Feb. 2, 1954,
PREPARATION OF HIGH MOLECULAR WEIGHT POLYHYDROXY-ACETIC ESTER.
U.S. Pat. No. 3,463,158, Schmitt and Polistina, Aug. 26, 1969,
POLYGLYCOLIC ACID PROSTHETIC DEVICES, discloses surgical uses of
polyglycolic acid, and incorporates definitions of some terms.
U.S. Pat. No. 3,620,218, Schmitt and Polistina, Nov. 16, 1971,
CYLINDRICAL PROSTHETIC DEVICES OF POLYGLYCOLIC ACID, lists many
uses of polyglycolic acid.
U.S. Pat. No. 3,736,646, Schmitt and Epstein, June 5, 1973, METHOD
OF ATTACHING SURGICAL NEEDLES TO MULTIFILAMENT POLYGLYCOLIC ACID
ABSORBABLE SUTURES, discloses surgical elements of a copolymer
containing from 15 to 85 mol percent glycolic acid and 85 to 15 mol
percent lactic acid.
U.S. Pat. No. 3,739,773, Schmitt and Polistina, June 19, 1973,
POLYGLYCOLIC ACID PROSTHETIC DEVICES, claims particularly bone
pins, plates, nails and screws of polyglycolic acid.
U.S. application Ser. No. 365,656, Schmitt and Polistina, May 31,
1973, SURGICAL DRESSINGS OF ABSORBABLE POLYMERS, now U.S. Pat. No.
3,875,937 Apr. 8, 1975, discloses additional subject matter on
surgical dressings of polyglycolic acid.
U.S. Pat. No. 3,739,773, supra, lists a number of U.S. patents on
methods for preparing polyglycolic acid and starting materials
therefor.
In U.S. Pat. No. 3,620,218, supra, in Column 2 are listed a number
of medical uses of polyglycolic acids, including in Column 2; line
52, knitted or woven fibrillar products, including velours, and
mentioning specifically in line 53, burn dressings; line 57, felt
or sponge for liver hemostasis; line 63, foam as absorbable
prosthesis; and in lines 74 and 75, burn dressings (in combination
with other polymeric films).
The use of gauzes, felts, and knitted fabrics as a wound dressing
is quite conventional. The use of collagenous products as a sponge
or pad has been disclosed. The requirements for surgical dressings
are varied and more satisfactory dressings than presently available
are constantly in demand.
U.S. Pat. No. 3,526,224, R. M. Potts, Sept. 1, 1970, DRESSING,
discloses an occlusive dressing designed to act as a synthetic skin
which has an elastomeric polyurethane film having a water vapor
transmission rate of 150 to 500 g/m.sup.2 /24 hrs. laminated to a
knitted velour fabric. A tricot fabric of 30 denier textured 6.6
nylon yarn is suggested. The pile or nap side of the knitted velour
forms the wound-contacting side of the dressing.
Studies are being made by and for governmental agencies on burn
protection. One such "Development of a Synthetic Polymer Burn
Covering" prepared by Dynateck R/D Company, for the Office of Naval
Research, June 1973, National Technical Information Service
AD-761,631 discloses the use of polymeric films, including lactic
acid polymers, and 75/25 lactic/glycolic copolymers, and the
disadvantages of flat, solvent cast films. A normal insensible
water loss from the human body is given as 2.2 mg/hr cm.sup.2,
quoting Treger, "Physical Functions of the Skin", Academic Press,
New York.
The complete disclosures of the above patents and articles are
hereby herein incorporated by this reference thereto.
SUMMARY OF THE INVENTION
This invention relates to a wound dressing, particularly adapted
for major burns in humans in which at least a part of the skin has
been destroyed or removed and which underlying tissue is subject to
moisture and liquid loss and bacterial contamination which dressing
comprises an exterior surface of an elastomeric material such as
polyurethane which has a moisture permeability of the order of that
of the intact human skin and to which is adhesively flocked a layer
of fibers of a tissue compatible and absorbable material which
fibers are preferably predominantly at about right angles to the
elastomeric layer and which are so spaced as to permit the invasion
of granulation tissue and which can be removed from the granulation
tissue without pulling off such granulation tissue and with minimum
damages to the developing granulation tissue to leave a bed for
autografting or other subsequent treatment.
The fibers themselves are absorbable by living tissue so that any
of the fibers which are trapped within the wound are absorbed by
the living tissue without deleterious effects.
The present wound dressing may be used on almost any type of wound
in which the skin is broken and body fluids, particularly blood and
serum, are released by the wound. It is primarily designed for
major burns in which a substantial area of the skin of a human is
destroyed, a third degree burn, leaving underlying tissues which
are either contaminated, or subject to contamination by bacteria,
or other contaminants, and which wound is of such a size that
immediate protection of the tissue surface is required. It is
desirable to change the wound from a contaminated and open wound to
a clean and closed wound in the shortest time possible, to decrease
pain, and to minimize protein loss, reduce evaporative heat and
water losses, and prevent further contamination during the time
required for the underlying tissues to build up a granulating
surface which will accept a skin autograft.
By skin autograft is meant skin taken from another area of the
subject, and which is living so that when placed on the granulating
tissue, the skin will graft to the granulating tissue and grow
providing a skin surface at the wound area. With rare exceptions,
the skin of any other subject will be rejected and not graft to the
wounded subject. The subject's own skin grafts to properly prepared
granulating tissue and will grow so as to enlarge the skin covered
area. With major burns, a sufficiently large portion of the subject
may be burned so that sites for donor skin are limited and it is
necessary to protect burned areas for a prolonged period until
graft donor sites can regenerate and be used for a subsequent
graft.
The generalized subject of burn treatment of this type is fairly
well recognized as are many of the requirements for such a wound
dressing. The medical profession recognizes the need for
improvements in burn site protection during burn treatment.
Survivability after major burns has been improving -- the present
invention contributes towards such improvement.
The use of a synthetic tissue absorbable dressing eliminates many
disadvantages of prior art dressings, particularly as to
availability, and represents a substantial step forward in burn
treatment.
The dressing should conform to the surface of the tissue.
Conformation comprises an assessment of the suppleness, resiliency,
anad dressing's ability to mimic the topography of the wound in
such a fashion that there is a minimum gap between the tissue and
the dressing which minimizes air gaps and pools of liquid. If pools
of liquid build up, whether of serum or blood, such pools become
sites for the growth of undesirable microorganisms. If the dressing
conforms adequately to the surface of the wound, the body's own
defense mechanisms are effective up to the zone of contact with the
dressing, and bacterial contamination is minimized. In many
instances, the body's defense mechanisms can clean a protected
contaminated wound and permit the growth of granulation tissue even
though the wound was initially contaminated.
In modern hospital technology, any area not known to be surgically
clean must be regarded as contaminated or at least suspect, and
treated as if contaminated.
For proper protection of the tissue surface, the gross escape of
liquids such as serum or blood needs to be prevented by the
dressing and the tissue needs to be protected from the atmosphere,
but at the same time just as natural skin permits the escape of a
certain amount of moisture, a wound dressing must permit the escape
of at least some moisture to prevent the dressing from being lifted
by the underlying flow of fluids. If the rate of moisture loss is
too high, there is a cooling effect from the heat required to
convert the liquid to vapor; and electrolytes, proteins, and other
materials in the underlying fluid concentrate and crust on the
surface, or under the dressing, which leads to complications. It is
desirable that the permeability be of at least approximately that
of the intact human skin (which is found to be about 2.2 mg./sq.
cm./hr.) and may be several times this value. A permeability of 4.7
mg./sq. cm./hr. has been found effective under many conditions. The
values are approximate as different skin areas lose moisture at a
different rate and, depending upon the temperature of the subject,
the temperature of the atmosphere, the movement of ambient air and
under other variables, the natural skin has a considerable range of
skin moisture loss. The natural skin is adaptable to a wide range
of environmental conditions so that if the wound dressing has a
moisture loss which is approximately that of the intact human skin
and remains within this range of acceptable conditions, the
underlying tissues are protected and regenerate. There is a fine
and, perhaps, unascertainable line between the regenerative
processes of the tissue when protected from adverse effects and the
increase that might be caused by dressing characteristics and
environmental factors. It is not necessary to ascribe the rate of
healing to any special set of factors. It is merely found that by
using the present wound dressing, rapid healing is encouraged.
For adequate conformation, the wound dressing must be flexible so
that it can conform to the topography of the wound and at the same
time it must be sufficiently flexible that as the tissues move, the
wound dressing can move with them. For instance, if the skin
adjacent to a joint is injured, flexing of the joint and movement
of the underying tissues requires that the wound dressing have some
flexibility. The minimum required flexibility is exceeded by the
present dressing and the dressing is sufficiently flexible for
tissue movement over joints and other areas.
Basically, the tissue-contacting portion of the dressing is a flock
of tissue compatible material which is substantially absorbed by
living tissue within a period of about 90 days and which fibers
maintain their integrity for at least about 3 days.
A flock of fibers of the order of 0.5 to 12 denier and from 10 to
30 mils long which are flocked onto an elastomeric layer gives
protection to the wound surface.
It is desirable that the fibers be absorbable by living tissue as
characteristics of a flocked surface are such that some fibers are
not tightly held, and some of the fibers may remain in the wound,
and non-absorbable materials can be the source of undesirable side
effects.
A preferred tissue absorbable polymer is polyglycolic acid, such as
described in the Schmitt patents above and which is meeting with
commercial success as a suture. Polymers in which tissue absorption
results from the hydrolytic degradation of glycolic acid ester
linkages give good results. Because strength of the fibers is not a
major requirement, a copolymer containing considerable lactic acid
makes a good dressing. Such polymers are disclosed in U.S. Pat. No.
3,736,646, supra.
A polymer having an ordered configuration of glycolic acid units
and lactic acid units which is tissue absorbable is described at
length in Ser. No. 435,365, Jan. 24, 1974, Augurt, Rosensaft, and
Perciaccante, UNSYMMETRICALLY SUBSTITUTED
1,4-DIOXANE-2,5-DIONES.
Another absorbable polymer which may be used for the graft is
poly(N-acetyl-D-glucosamine) such as described in U.S. Ser. No.
441,717 filed Feb. 11, 1974, Richard Carl Capozza,
POLY(N-ACETYL-D-GLUCOSAMINE) PRODUCTS.
The important thing about the tissue absorbable polymer is that it
be of a material which is not deleterious to living human tissue
and that it be spinnable as a fiber which forms a fine structure
such that blood and other fluids do not flow rapidly therethrough
and it has sufficient strength to maintain its integrity during the
manufacture of a flock and that it maintains its integrity in
contact with the tissue long enough for granulation tissue to form
and yet is absorbable within a reasonable length of time, for
instance, about 90 days, so that it does not remain as a foreign
body after the wound has healed.
The above two patent applications, the disclosures of which are
herein incorporated by this reference thereto, give examples of
such materials.
Inasmuch as the useful characteristics of such materials are
largely as a function of size, shape and structure, these materials
may be substituted for the polyglycolic acid fibers described in
more detail in the following examples.
The fibers which conveniently are spun in about 1 to about 12
denier are adhesively flocked to the elastomeric backing layer. By
using an electrostatic charge, as is conventional in flocking
systems, the fibers are caused to stand on end and are
predominantly at right angles to the elastomeric layer. The fibers
may be adhesively united to the elastomeric layer by using the
adhesive characteristics of the elastomeric layer as it is formed.
More conveniently, when the elastomeric layer is formed, a separate
adhesive layer is placed thereon and the flocked fibers are placed
on such adhesive layer and caused to stand on end
elastrostatically.
The elastomeric layer may be any material which is permeable to
moisture, has a low Young's modulus and is thus readily conformable
to the wound surface. A particularly useful material is
polyurethane. A soft, flexible elastomeric layer of polyurethane of
the order of 2 mils thick provides a barrier to excessive water
loss, is permeable to moisture within the range of that of the
intact human skin, which is approximately 2.2 mg./sq. cm./hr., to
two to four times this value, which permits moisture to pass
through the backing layer at such a rate that formation of liquid
pools under the dressing is minimized, and yet the water loss is
within a desirable range as regards heat loss and concentration of
dissolved components in the body fluids which are underneath the
dressing.
At the time of use, the wound should be debrided in accordance with
usual techniques and substantially dried so that there is no
standing liquid on the surface of the wound. Then, the soft flocked
surface of the wound dressing is placed in contact with the wound,
being sure that it conforms to the topography of the wound surface
so that there are no gaps or spaces between the tissue and the
dressing; with the dressing being held in place by adhesive tape,
additional bandages, or suturing. A low pressure bandage may be
used to hold the dressing in place, depending upon the location of
the dressing and the condition of the patient. The dressing is
permitted to remain in place for approximately seven days. If less
than 4 days in most subjects, there is not sufficient time for
adequate granulation tissue to grow under a dressing and if more
than 14 days, too much granulation tissue may grow and result in
scar tissue. At times a wound must have a first dressing applied
and be permitted to heal so that granulation tissue is formed in
part on the wound and then additional debridement or other
treatment is undertaken in other areas, requiring a second wound
dressing application to encourage the growth of additional
granulation tissue. There are times when many treatments are
required before the wound is in condition for autografting or
before skin for autografting becomes available. For major burns or
traumatic tissue damage, prolonged treatment may be required before
the wound is ready for final grafting.
In other instances, a wound may be fairly minimal and the present
wound dressing may be applied even though a less adequate wound
dressing could have been used and a single application permits
substantial healing. Different areas of the same wound may require
different treatment.
The present wound dressing in particular functions as a temporary
synthetic skin, giving a protective covering to any area of a body
from which the skin is removed and the underlying tissues are
exposed with the covering not interfering with normal physiological
processes conducive to wound healing and autograft
conditioning.
The composite structure provides both a good moisture barrier and
bacteria barrier. The conformability resulting from the elastomeric
backing permits conformation to nearly any wound topography while
the short fibers protruding from the flocked surface insure
intimate contact and wetting at the wound surface which provides an
intimate contact with the tissue absorbable fiber during the
healing process. Because the flocked surface is absorbable, there
is no problem resulting from biological rejection of the flocked
material and there can be no deleterious entrapment in regenerating
tissue in tangled fibers, as can be the case of a sponge or woven
web.
As shown in the attached drawing, a polyurethane such as described
in U.S. Pat. No. 3,582,423, Wang, June 1, 1971, PROCESS FOR COATING
POROUS SUBSTRATES, and sold as Helastic 13141 polyurethane, is cast
on a release coated paper to form a film with a thickness of 2
mils. The material is a reaction product of a hydroxy terminated
polyester such as diethylene glycol adipate and p,p'-methylene
dianilane and a mixture of 2,4- and 2,6-toluene diisocyanates, at
about 25% solids. The polyester type segmented polyurethane is
permitted to harden to form a water vapor permeable elastomer
layer, and then coated with an additional half a mil thickness of
the same polyurethane.
The polyurethane structure may be graphically described as:
NH.sub.2 --R.sub.1 -- NH--CO--NH--R.sub.2 --NH--CO--O--R.sub.3
--O--CO--NH--R.sub.2 --NH----CO--NH--R.sub.1 ].sub.n NH.sub.2
where, ##SPC1## ##EQU1## or --CH.sub.2 --CH.sub.2 --CH.sub.2
--CH.sub.2 -- O--CH.sub.2 --CH.sub.2 --CH.sub.2 --CH.sub.2
].sub.m
The polyurethane film is cast by pouring the resin dissolved in
solvent on a release paper such as a silicone coated release paper,
which is pulled through rollers set to leave about 4 mils of 25%
solids solution on the release paper, so that when dry a 2 mil
layer remains. After a second pass to leave an additional adhesive
coat which dries to about 0.5 mil thickness, there are flocked 2
denier polyglycolic acid fibers approximately 25 mils long with the
fibers being subjected to a strong electrostatic field, in
accordance with conventional procedures, to cause the fibers to
stand at approximately right angles to the field and, hence, at
right angles to the backing, while the polyurethane adhesive layer
cures. The thus formed flock is shaken and then blown with air to
remove any loose fibers, after which the flocked sheet is cut into
2 inch .times. 3 inch rectangles for individual dressings.
As a surgical device, it is obviously desirable, almost mandatory,
that the wound dressing be sterile at the time of use. The wound
dressing may be sterilized by an appropriate sterilizing cycle
using ethylene oxide as a sterilizing agent. Radiation
sterilization may be used, as may heat sterilization.
If ethylene oxide is used to sterilize, it is convenient that the
ethylene oxide be diluted with carbon dioxide or a
chlorofluoroalkane to such an extent that the sterilizing gas is
non-explosive. For storage stability, it is desirable that the
wound dressing be protected from atmospheric influences. Because
the wound dressing contains hydrolyzable polyglycolic acid ester
linkages, the linkages can be hydrolyzed by ambient moisture under
room storage. The wound dressing requires that the flocked fiber
retain sufficient strength to be separated from the wound when the
dressing is changed. Preferably, it should retain strength at least
10 days to 2 weeks. It is desirable that such storage conditions be
used as to maintain the wound dressing in a dry environment so that
whether used immediately after packaging or after a storage period
of several years, the wound dressing has the same characteristics
and, hence, has known predictable attributes as far as the using
surgeon is concerned.
A good method of sterilizing and storage is the same as is used for
polyglycolic acid sutures on a commercial scale and as disclosed in
U.S. Pat. No. 3,728,839, Arthur Glick, Apr. 24, 1973, STORAGE
STABLE SURGICALLY ABSORBABLE POLYGLYCOLIC ACID PRODUCTS. As there
described, the polyglycolic acid product is stored in a moisture
proof envelope in which conveniently the product is packaged except
for one open side and sterilized using ethylene oxide diluted so as
to be non-explosive, and then while protecting sterility, the
product is vacuum dried and the envelope sealed. By having the foil
envelope hermetically sealed, as there taught, the wound dressing
may be maintained in a usable form with consistent characteristics
for a period of at least several years. Conveniently, but not
necessarily, the wound dressing may be placed between two sheets of
paper, or a single sheet of paper with a fold, so that the wound
dressing is held in flat condition between the sheets during
storage and service to the using surgeon.
A single envelope can be used, which, on stripping, releases the
wound dressing folded in a sheet of paper. Such a single envelope
package is shown in U.S. Pat. No. 3,017,990, Singerman, Jan. 23,
1962, STERILE PACKAGE FOR SURGICAL FABRIC.
For large sheets, the wound dressing may be folded, but for sheets
up to 3 inches .times. 5 inches it is conveniently placed in an
envelope large enough to hold the sheet flat. A plurality of sheets
may be packaged in a single envelope if desired. Single sheets of
about 3 inches .times. 5 inches are a surgically acceptable size,
with the wound dressing being cut to size if necessary by the
surgeon, or an assistant, at the time of use. For many surgical
procedures, a single sheet is all that is required. For major
burned areas, either a number of smaller sheets or a single layer
sheet of the wound dressing gives good results. A series of smaller
dressings gives more conformity on irregular areas. A single large
sheet reduces the number of seam lines. Conveniently, the wound
dressing is made available in sterile form in sheets 3 inches
.times. 5 inches, 3 inches .times. 12 inches, 3 inches .times. 18
inches, 3 inches .times. 24 inches and continuous rolls, about 12
inches wide. Other sizes and shapes can be provided to supply the
using surgeon with a choice of sizes, consistent with reasonable
inventory demands.
At the time of use, the enclosure is stripped open, the individual
dressing removed and placed in contact with the wound surface. For
burn areas with adjacent whole skin, the wound dressing may be held
in place by adhesive strips.
On burn test subjects, the wound is cleaned from burned tissue and
other contaminants, in accordance with conventional debriding
proceedings, and the wound covered by the wound dressing. After
approximately 7 days, the wound dressing is removed from the wound
gently to avoid stripping granulation tissue, and the wound is
ready for grafting, or additional treatment.
The treatment of the wound before applying the wound dressing may
include antibacterial agents, anesthetics, etc.
The time before dressing change varies with the location of the
wound, and the general condition of the patient. Some heal more
rapidly than others. The surgeon in charge must adapt the treatment
to the specific patient.
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