U.S. patent number 3,867,939 [Application Number 05/381,733] was granted by the patent office on 1975-02-25 for disposable, sterile temperature control applicator pad for medical application.
This patent grant is currently assigned to Moore-Perk Corporation. Invention is credited to Francis C. Moore, Leon R. Perkinson.
United States Patent |
3,867,939 |
Moore , et al. |
February 25, 1975 |
DISPOSABLE, STERILE TEMPERATURE CONTROL APPLICATOR PAD FOR MEDICAL
APPLICATION
Abstract
A disposable pad for controlling body temperature at selected
areas of application includes a flexible fluid conduit for passage
of source fluids, whether hot or cold, and a soft, absorbent,
flexible covering with a surface which will neither stick nor slide
when applied, for example, to an open wound. The absorbent covering
may act either as an applicator of medicaments in combination with
the conduit for temperature control, or it may be wetted with a
sterile fluid to enhance the heat transfer relation between the
conduit and area of application, or it may act as an absorbent
bandage or dressing or as a surgical sponge.
Inventors: |
Moore; Francis C.
(Indianapolis, IN), Perkinson; Leon R. (Indianapolis,
IN) |
Assignee: |
Moore-Perk Corporation
(Indianapolis, IN)
|
Family
ID: |
26944206 |
Appl.
No.: |
05/381,733 |
Filed: |
July 23, 1973 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
254715 |
May 18, 1972 |
|
|
|
|
Current U.S.
Class: |
604/291;
607/104 |
Current CPC
Class: |
A61F
7/02 (20130101); A61F 2007/026 (20130101); A61F
2007/0261 (20130101); A61F 2007/0059 (20130101); A61F
2007/005 (20130101) |
Current International
Class: |
A61F
7/00 (20060101); A61f 007/00 () |
Field of
Search: |
;128/254,400,399,402,403,296,156,287,290 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Gaudet; Richard A.
Assistant Examiner: Yasko; J.
Attorney, Agent or Firm: Dawson, Tilton, Fallon &
Lungmus
Parent Case Text
RELATED APPLICATIONS
This is a continuation-in-part of our copending, co-owned
application, Ser. No. 254,715, filed May 18, 1972, now abandoned.
Claims
We claim:
1. An article for applying heat or cold to a human body comprising:
a flexible, liquid-tight conduit adapted to pass a hot or a cold
fluid between an inlet and an outlet therein, said conduit being
conformable to an area of application of the human body to overlie
the same; and a covering engaging at least one side of said conduit
including a core of soft, flexible absorbent material, an exterior
layer of flexible tear-resistant grid material providing a
plurality of closed boundaries each defining an aperture, said grid
material overlying said core material, and means bonding said grid
material to the exterior surface of said core material, said
covering being characterized in being substantially free of lint
and loose threads, in providing a nonsticking, non-sliding surface
when applied to open wounds, and in quickly absorbing liquid with
which it is brought into contact; and means holding said covering
in engagement with said conduit.
2. The article of claim 1 wherein said bonding means comprises a
layer of thin thermoplastic film material interposed between said
absorbent core material and said layer of grid material and heat
sealed therebetween to bond said materials into a unitary covering
with said intermediate film separated from itself within the
boundaries defined by said grid material.
3. The article of claim 1 wherein said covering is provided to
overlie both sides of said conduit to substantially surround the
same except for the inlet and outlet thereof.
4. The article of claim 1 wherein said conduit includes first and
second layers of thermoplastic material heat-sealed together to
provide a liquid-tight, continuous fluid conduit between said
inlets and said outlet thereof.
5. The article of claim 1 wherein said grid material is a thin
layer of spun-bonded nylon, the apertures therein being
sufficiently small to hold drops of water when separate from said
article, yet large enough to permit rapid passage of liquid
therethrough when said article is brought into contact with a
liquid.
6. The article of claim 1 wherein said core material is soft
fibrous crepe paper of facial quality.
7. The article of claim 2 wherein said bonding material is a sheet
of polyethylene film having a thickness in the range of 0.0002 in.
to 0.0010 in.
8. The article of claim 7 wherein said conduit is a layer formed of
laminated films secured together to form a liquid-tight continuous
conduit between the inlet and outlet thereof and wherein said
covering overlies both sides of said conduit layer.
9. The article of claim 8 wherein the outer edges of said
thermoplastic bonding film and said grid materials extending beyond
the periphery of said conduit layer and said core materials to bond
said article into a unitary product by heat-sealing the peripheral
edges of said exterior grid materials together about the respective
borders while permitting access to said inlet and outlets in said
conduit layer.
10. The article of claim 1 wherein said conduit is formed from
superposed layers of thermoplastic film material heat-sealed
together to form a liquid-tight continuous conduit between the
inlet and outlet thereof and further providing apertures in the
heat-sealed areas thereof to permit fluid to pass through said
conduit layer while maintaining a liquid-tight conduit.
11. A medical applicator for applying heat or cold to a selected
area of the body comprising: a central conduit layer of flexible
laminated material forming a liquid-tight continuous conduit
between an inlet and an outlet therein; first and second layers of
soft fibrous, highly-absorbent core material located respectively
on either side of said conduit layer; first and second exterior
layers of tear-resistant flexible grid sheet material having a
plurality of interconnected filaments in spaced locations covering
respectively the exposed surfaces of said core material and
providing a plurality of closed boundaries each defining an
aperture; and first and second layers of adhesive means attaching
said first and second grid layers respectively to the outer
surfaces of said core material; and means securing said grid
materials together about said conduit layer.
12. The article of claim 11 wherein said adhesive means comprises a
layer of thin polyethylene for heat-sealing the exterior grid
layers to their associated core material while separating between
the boundaries defined by said grid materials over at least a
substantial portion thereof to permit the transmission of fluid
through the grid material into the core material.
13. The article of claim 12 wherein said conduit layer further
includes a plurality of apertures therein to permit the passage of
liquid transversely therethrough while maintaining a liquid-tight
conduit.
14. The article of claim 11 wherein said core material is
needle-punched rayon.
15. The article of claim 11 wherein said adhesive means includes a
sheet of polyethylene having a thickness in the range 0.0002 to
0.0010 in. and wherein said sheets of polyethylene and said grid
materials extend beyond the outer periphery of said conduit layer
and said core material to form a heat sealed peripheral border
about said article.
16. A medical applicator for applying heat or cold to a selected
area of the body comprising: a central fluid conduit forming a
continuous liquid-tight conduit between an inlet and an outlet; a
covering of soft fibrous, highly-absorbent core material covering
said conduit; a layer of exterior tear-resistant flexible grid
sheet material having a plurality of interconnected filaments in
spaced relation covering the outer surface of said core material
and providing a plurality of closed boundaries each defining an
aperture; a first polyethylene film interposed between said grid
material and said core material; and a second polyethylene film
surrounding said grid material, each of said films having a
thickness in the range 0.0002 in. to 0.0010 in., said grid and said
core materials being heat-sealed together with said polyethylene
film, the exterior layer of polyethylene film covering and sealing
to the outer surface of said grid material, both of said
polyethylene films being opened within the apertures defined by
said grid material to permit liquid to permeate said grid material
and be absorbed by said core material rapidly, said article being
characterized in having a non-sticking yet non-sliding surface when
applied to a wound or incision.
17. A sterile, disposable medical applicator for applying heat or
cold to a selected area of the human body comprising: a central
conduit layer of flexible laminated material forming a liquid-tight
continuous conduit between an inlet and an outlet therein; first
and second layers of soft fibrous, highly-absorbent core material
located respectively on either side of said conduit layer, first
and second exterior layers of tear-resistant flexible grid material
having a plurality of interconnected filaments so as to be porous
and covering respectively the exposed surfaces of said core
material; first and second layers of plastic bonding material for
heat-sealing said exterior grid layers to their associated core
material layers under the application of heat and pressure while
separating between boundaries defined by said grid materials over
at least a substantial portion thereof to permit the transmission
of fluid through the grid material into the core material, said
core materials being attached directly to the associated surface of
said central conduit layer through the embedding of fibers therein
under the application of heat and pressure while forming said
conduit.
18. The article of claim 17 wherein said central core material
comprises first and second layers of thermoplastic material
laminated together along spaced continuous boundaries defining the
width of said conduit.
19. The article of claim 18 wherein one of said layers of said
central core material has a thickness in the range 10-25 mils and
the other layer has a thickness of about 1.2 mils, the thicker
layer being adapted for placement exterior of the application area
to reduce heat loss through conduction to the environment.
20. A disposable medical applicator for applying heat or cold to a
body comprising: a flexible, liquid-tight central conduit adapted
to pass a hot or a cold fluid between an inlet or an outlet therein
and being conformable to an area of application to the human body
to overlie the same; a covering engaging at least one side of said
conduit including a core of soft, flexible absorbent material, an
exterior layer of flexible tear-resistant, porous grid material
overlying said core material; means bonding said grid material to
the exterior surface of said core material, said covering being
characterized in being substantially free of lint and loose
threads, in providing a non-sticking, non-sliding surface when
applied to open wounds, and in quickly absorbing liquid with which
it is brought into contact; and a reflective layer on a side of
said conduit opposite a covering thereof to reduce heat loss from
said conduit through radiation, all of said elements being united
into a unitary article.
Description
BACKGROUND AND SUMMARY
The present invention relates to a temperature controlled
applicator or pad which may be applied to a selected area of
application of the body as a covering or dressing; or in the
treatment of a wound, incision, bruise, burn or sprain; or as a
covering for an organ either in situ or after removal, as in a
transplant, to induce hypothermia in the organ. The most common use
for such a device is a cold pad applied to a wound or incision to
reduce edema; however, recent developments have shown the utility
of applying heat selectively to areas of the body where an open
wound or incision may be near. For example, the application of heat
to the vaginal area of a woman after birth of a child has been
found to be of significant comfort to her. In any such application
the primary concern is, of course, to minimize the threat of
surface infection. In addition, however, it is important that there
be no loose threads or lint associated with the applicator pad
which may work its way into the opening. Since it is an applicator
for direct contact with open wounds exuding fluid, it is highly
desirable that the applicator have a nonsticking, yet non-sliding
surface, and one which will stay in place without being too
slippery.
One type of temperature control pad presently in commercial use is
made of pliable vinyl, having a continuous, serpentine conduit
formed in it which is adapted to couple with hoses supplying a
heated or cooled liquid. Water is normally used as the source of
heat or cold. These pads are especially designed for use with a
companion heating and cooling unit, and the same pad is used over
and over again until it is either damaged or wears out. Hence, in
order to prevent cross-contamination, the pad must be sterilized.
These pads are difficult to sterilize and they may become
contaminated during storage between use. Hence, they are currently
used almost exclusively where infection is not likely to occur, and
they are not used for the application of medication. In addition,
these pads to not possess the advantages described in more detail
below, that are contained in the present invention in that the
present invention has a highly absorbent covering and therefore
serves the dual function of a surgical sponge when applied to an
open wound or an incision, as well as a temperature control
applicator. Further, a liquid solution may be added to the present
applicator to enhance the thermal conductivity between the source
of heat or cold and the area of application. This property further
permits the direct application, in combination with a temperature
control device, for applying saline solution, anti-bacterial
agents, or any other medicating or treating solution that an
attending physician may think desirable.
Another type of known hot/cold pack uses two chemicals, packaged in
a single container but separated, which, when mixed together for
use, either produce an exothermic or heat-absorbing chemical
reaction. This type of thermal applicator has the disadvantages
that the temperature is difficult to control, the applicator packs
are almost impossible to use in a wet, yet sterile condition, and
the time during which the desired temperature is maintained is
relatively short--of the order to 30 to 45 minutes. Further, with
this type of applicator, it has been found difficult as a practical
matter to have on hand packs of all the various desired sizes.
In our co-owned application for GAS-PERMEABLE LAMINATE AND METHOD
OF FORMING THE SAME, Ser. No. 134,504, filed Apr. 15, 1971, which
is a continuation-in-part application of Ser. No. 693,886, filed
Dec. 27, 1967, we disclosed a gas-permeable reinforced laminate
which is suitable for use as a surgical drape or the like and which
includes a reinforcing layer of loosely-woven cloth, a layer of
porous paper material, and an intermediate layer of plastic film
for bonding the reinforcing layer to the paper. In the preferred
embodiment of that application, a surgical drape is formed with a
central layer of scrim material, two intermediate side layers of
bonding plastic film, and exterior layers of the paper
material.
In our U.S. Pat. No. 3,678,933, for SURGICAL SPONGE OR BANDAGE,
issued July 25, 1972, we disclose a bandage for surgical use which
includes a central core of soft, flexible absorbent material, first
and second exterior layers of flexible grid material and first and
second layers of thermoplastic film material interposed between the
core material and the layers of grid material and heat sealed to
bond the materials into a unitary article. This article is
characterized in being substantially free of lint and loose
threads, and provides a non-sticking surface when applied to
wounds. It is also highly absorbent.
In the present invention, a continuous fluid conduit is preferably
formed by heat sealing sheets of thermoplastic material together so
as to form a conduit layer having a continuous serpentine or
meandering flexible tubular conduit for conducting the hot or cold
fluid, such as water. The conduit layer can conform easily to the
contour of the application area of the body. The laminated portions
of the forming sheets of the conduit may be perforated or slotted,
depending upon the configuration of the conduit, so that liquids
may permeate the conduit layer while leaving the conduit itself
leakproof.
The conduit layer is provided with a highly-absorbent covering
which may be formed by placing soft fibrous paper sheet material,
an intermediate film of thermoplastic sheet material, and an
exterior layer of a grid material, such as a cotton scrim or
spun-bonded nylon in overlying relation and applying heat and
pressure. Such covering material may be placed on both sides of the
conduit layer. The thermoplastic sheet material and the outer grid
material may be cut to slightly larger dimensions to form a
peripheral border, leaving room for an inlet and an outlet
connection, which when heat sealed together, will form the
applicator into a unit. When heat and pressure are applied to
superposed layers as indicated, the intermediate thermoplastic
sheet material melts and separates from itself to form apertures
defined by the filaments of the grid material. This intermediate
plastic layer further bonds the grid material to the absorbent core
material and gathers about the filaments of the exterior grid in
wrapping, covering engagement to form an outer surface which will
not stick to a wound yet is not slippery and hence will not slide
from the wound when applied. The plastic material gathers itself
about the grid material and traps loose filaments or threads of the
grid material as well as any lint from the absorbent core, thereby
preventing the introduction of such lint or filament into an open
wound.
An important characteristic of the covering is the fast rate of
absorption of fluid. This is a highly desirable property since the
article may then be used as a surgical sponge as well as a
temperature control device. Further, the article has the
characteristic that it will not permit absorbed fluids (whether
fluids exuded from a wound or medicaments applied to the
applicator) to bleed or pass back into the wound to any substantial
degree. We have observed, for example, that if an article is
constructed according to our invention has absorbed liquid and is
then placed on a dry surface, it will leave only a very small
amount of surface moisture and will not yield any significant
amount of fluid under normal use conditions. The grid material adds
great tear resistance and mechanical strength to the article to
prevent tearing or rupture by shearing of the conduit layer. This
permits the use of thinner plastic materials in forming the conduit
layer and thus enhances the thermal conductivity of the
applicator.
The applicator of the present invention may be made of low-cost
materials, as disclosed within, to reduce the overall cost, and it
is easily sterilized during manufacture according to conventional
technique. Thus, by providing a low-cost applicator, it is a
disposable item; and this renders it highly attractive to hospital
personnel since it does not have to be re-sterilized after use.
Other features and advantages of the present invention will be
apparent to persons skilled in the art from the following detailed
description of a preferred embodiment accompanied by the attached
drawing.
THE DRAWING
FIG. 1 illustrates the superposition of the various layers and
components for making an applicator according to the present
invention;
FIG. 2 is a somewhat diagrammatic plan view of one embodiment of a
conduit layer incorporated into the applicator of FIG. 1;
FIG. 3 illustrates the superposition of various components for an
alternate applicator constructed according to the present
invention;
FIG. 4 is a diagrammatic side view illustrating one method of
making the applicator; and
FIG. 5 is a plan view of a conduit layer for the embodiment of FIG.
3.
DETAILED DESCRIPTION
Turning now to FIG. 1, reference numeral 10 generally designates a
central conduit layer which will be described in more detail below.
First and second covering layers, designated generally respectively
by reference numerals 11 and 12 are provided on either side of the
central conduit layer 10. The various materials are shown in FIG. 1
in a separated relation for clarity. Each of the covering layers
11, 12 may be similarly formed. Thus, the covering layer 11
includes a first layer of highly absorbent, soft, flexible core
material 13 adjacent the conduit layer 10, a thin sheet of
thermoplastic material 14, and an exterior layer of grid material
15. The covering layer 12 similarly includes a layer of core
material 16, a sheet of thermoplastic material 17 and an exterior
layer of grid material 18.
The layers of core material 13, 16 may be formed from a plurality
of sheets of highly absorbent, porous, fibrous, soft paper of the
quality used in facial tissue. Depending, then, upon the intended
application there may be one or two superposed layers of such
absorbent paper forming each of the core layers 13, 16 so as to
provide a greater amount of paper within a given unit area without
decreasing the absorbency of the core material. Other suitable
highly absorbent soft flexible materials that have been found
satisfactory for use as a core material include fibrous rayon of
the type that is used in place of cotton for swabbing, or a highly
absorbent, open-cell urethane foam. A non-woven material found
satisfactory is bleached, crimped, needle-punched rayon such as
identified as BFL-35A and manufactured by The Barwove Company,
Inc., of Little Falls, New Jersey. Alternatively, this
needle-punched product could be made of 50 percent bleached rayon
and 50 percent bleached cotton. In either case, it is highly water
absorbent, soft and flexible.
The film sheets of thermoplastic material 14, 17 are preferably
polyethylene having a thickness between 0.0002 and 0.0008 inches,
although thicknesses of up to 0.002 inch may be used successfully.
Best results have been obtained using polyethylene films having a
thickness of 0.0002 in. These films are especially effective as the
intermediate plastic layers since a primary function they perform
is to bond the outer grid material to the absorbent core material
into an integral unit. It has been found preferable to use a porous
polyethylene film sold under the trademark Delnet by the Hercules
Co. of Wilmington, Delaware.
The covering layers are formed under the application of heat and
pressure to the superposed layers, preferrably, of spun-bonded
nylon, polyethylene film and needle-punched rayon. The exact
temperatures and pressures depend on the materials and their
thicknesses, but normally temperatures in the range
200.degree.-400.degree. F. will cause the desired melting of the
polyethylene which forms a bond between the grid and core
materials.
During the application of pressure and heat in the prelamination of
the covering layers, the exterior grid layers 15, 18 provide a
number of closed boundaries beyond which the melting, separating
plastic films 14, 17 will not withdraw from itself during
deformation. That is to say, the apertures in the exterior grid
material acts as a boundary to limit the separation of the plastic
film material as heat and pressure are applied to melt it. The
melting plastic film forms apertures within a large number of the
closed boundaries of the grid and gathers itself together in
wrapping, covering engagement about adjoining filaments of the
grid, thus at least partially encompassing the scrim material in a
plastic coating while advantageously collecting or gathering
together any loose filaments or threads from the scrim as well as
any lint on the outer surface of the adsorbent paper core material.
If it is desired to use a cotton scrim for the grid layers 15, 18,
then additional thin plastic layers such as the ones designated 14,
17 may be placed exterior of these grid layers so as to completely
encompass them and to provide a non-sticking, yet non-sliding
surface. When spunbonded nylon is used as the exterior grid
surface, the outer plastic layer just mentioned is not necessary
because a nonsticking, non-sliding surface can be obtained without
it.
It will be appreciated that the separating plastic sheet material
of the films 14, 17, provides a communication to the absorbent core
layers 13, 16 to promote the overall absorption properties of the
applicator; but it has been found that not all of the areas of
plastic enclosed by individual grids need be separated or opened in
order to achieve a very rapid absorption characteristic for the
applicator. Rather, substantial numbers of contiguous elemental
areas within the grid material may remain impermeable to fluid
without appreciably diminishing the absorption rate or the overall
retentive capacity of the applicator. That is, during manufacture,
the application of heat should be such as to result in a rupture or
separating of the thermoplastic film within the boundaries defined
by the grid material for a major portion of such zones in order to
effect a greater transmission of fluid to the absorbent material;
however, it is not essential that the plastic material separated at
each enclosed boundary defined by the grid material. This property
is enhanced if, to begin with, the polyethylene film is perforated
with tiny porous apertures as with Delnet.
Each of the thermoplastic films 14, 17 should be under tension as
melting temperatures are approached. Preferably, the orientation
should be bi-directional as would occur during normal extrusion of
polyethylene films.
The effectiveness of the thermoplastic films as a bonding layer may
be increased if the film is surface-treated by flame or by corona
discharge in the same manner as conventionally employed to make the
plastic surface more receptive to inks and other decorative
material. Both surfaces of each film layer are preferably treated
in this manner; however, if only one surface is so treated, then it
should be the surface which engages the exterior grid layer. Delnet
material need not be so treated.
The exterior layers of grid material 15, 18 are placed against the
exterior surface of the plastic film layers 14, 17. The exterior
grid material 15, 18 may be a scrim or open network of
loosely-woven, spaced fibers formed into an orthogonal array or
grid. Preferably, spun-bonded nylon sold under the trademark Cerex
by Montsanto Co. of St. Louis, Missouri, is used because it is
highly resistant to tearing in all directions and it is resistant
to wetting when formed in single sheets.
When using spun-bonded nylon as the grid material, we prefer to
laminate the film of polyethylene (of the order of 0.0002 in.
thick) onto the spun-bonded mylon prior to forming the article as
shown in FIG. 1 under a process referred to as extrusion coating
wherein an extruded film of the poly is brought into contact with
the nylon, and the two are then calendered together. This has been
found to achieve a better attachment for the overall covering. In
this case, the outer sheets of polyethylene may be omitted.
In the case of a spun-bonded nylon grid, apertures may be small
enough so that if the grid is held separately, it will actually
hold water in amounts of a few drops. However, we have found that
when backed with the thin polyethylene sheet and absorbent core
material and treated as disclosed herein, the combination absorbs
liquid at a very high rate despite the resistance to wetting of the
grid; and these characteristics permit the grid to have even better
resistance to passing fluid back from the absorbent material that
in the case of a cotton scrim or other woven grid material due to
the larger apertures. It is preferred to have a non-woven grid
material for another reason, namely, that it is more resistant to
sticking when applied to an open wound.
The fibers or filaments of the grid material may be natural such as
cotton, hemp, flax or linen; or they may be synthetic such as nylon
or polyesters. Preferably, however, the grid is a thin, soft,
porous layer composed of wet-resistant fibers of natural or
synthetic material in closely spaced relation so that the fibers
facilitate conduction of a liquid to the core material without
themselves absorbing the liquid. Where the grid layer takes the
form of a scrim, the filaments may be interwoven, knitted or joined
together in any suitable manner.
Turning now to FIG. 2, the conduit layer 10 may be fabricated by
laminating two layers of thermoplastic material together so as to
form a continuous, water-tight conduit, generally designated by
reference numeral 20 which winds through the conduit layer in the
serpentine manner illustrated so that water or other control fluid
may flow through the conduit 20 in the direction of the arrows
between an input port 21 and an outlet 22. The two thermoplastic
sheets must, of course, be sealed about the edges, and there may be
a plurality of interior seals, indicated by the dashed lines 23 and
24 which are spaced laterally apart to define the conduit. Within
these sealed areas, there are a plurality of apertures designated
25 which extend through both of the plastic sheets forming the
conduit layer 10 and permit liquid to flow through the conduit
layer.
Alternatively, the conduit layer could be formed by heat-sealing
one thermoplastic material to a non-thermoplastic material such as
foil or Mylar, or it may be formed from two sheets of Mylar with a
heat-actuated adhesive applied to one sheet in the desired form of
conduits. Still another alternative is to lay a plastic tube in the
desired configuration.
Thus, with the double-covered embodiment of FIG. 1, the applicator
may be applied to a burn or wound and medication in liquid form or
a sterilizing solution may be poured on the exterior covering of
the applicator, and it will flow through the apertures 25 to the
interior absorbent core and be applied to the wound. Further,
sterilized water may be used in cases where better thermal
conductivity are required because heat is better conducted to or
from the skin when a wet applicator, as distinguished from a dry
applicator, is in contact with the skin.
In fabricating the inventive applicator, the conduit layer 10 may
be prefabricated in the manner disclosed above. The covering layers
11, 12 are also pre-laminated. The three layers are then fed into a
press which heat seals the covering layers together about the
peripheral edges, the layers being dimensioned such that the
covering layers have a peripheral border about 3/8 inches larger on
all sides than the heating may be accomplished electrically or by
other conventional means. The platens of the press are heated to a
point sufficient to raise the plastic polyethylene films 14, 17 to
a melting temperature. This is normally between 200.degree. and
400.degree. F., the precise temperature depending upon the
thickness of the plastic layers, the exterior grid materials
employed, etc. The grid material, the core layers 13, 16 and the
central conduit layer 10 must be dimensionally stable at these
temperatures.
Turning now to the embodiment of FIG. 3, the covering layers 11, 12
are similar to those previously disclosed except that the
thermoplastic film layers 14a, 17a comprise the porous polyethylene
identified above. In addition, the conduit, designated 10a, is of a
slightly different configuration shown in FIG. 5, and disclosed in
more detail presently. In this embodiment, there is also includes a
perforated reflective polyethylene film, designated by reference
numeral 30, which is interposed between the covering layer 11 and
the conduit 10a. The function of this reflective layer 30 is to
minimize heat transfer through radiation from the conduit 10a to
the atmosphere. In this case, the cover 12 would be intended for
contact with the application area, so that the conduit layer 10a is
interposed between the application area and the reflective layer
30. The interposition of the reflective layer 30 has been found
most effective in heat applications, as compared with the use of
the pad as a cold applicator. The film 30 has an aluminized upper
surface 31, and it need not necessarily be perforated as
illustrated. It may be polyethylene or polyester film such as
Mylar. In the case of polyethylene, it should be adhesively secured
to the upper surface of the conduit 10a and the lower surface of
the absorbent core material 13, and not broken up as in the case of
the bonding films.
Turning now to FIG. 5, the conduit layer 10a is again formed of two
sheets of thermoplastic material, such as polyvinyl chloride; and
in this embodiment, the conduit layer is formed by pressing a
heated iron or platen into contact with the superposed layers.
Preferably however, a dielectric sealer with a high frequency
source of energy is used when polyvinyl chloride is employed for
the bonding films because this source selectively heats the
polyvinyl chloride. The configuration of the iron is such that it
includes two continuous sealed paths designated respectively 34 and
35, separated from each other to define the width of the conduit
and leading from an inlet aperture 36 laterally to the left in a
continuous manner and thence to the other side and again meandering
inwardly toward the center to the outlet aperture 37. The two
sheets may be perforated as at 38 to permit fluids to be
transmitted from one side of the conduit layer to the other, and it
also may be slit as at 39 to facilitate fluid transfer through the
layer without breaching the closed conduit for the heating or
cooling fluid.
The conduit layer may thus be separately formed by pressing a
heated platen or dielectric heater of the shape described onto the
superposed layers of polyvinyl chloride thereby bonding the two
layers together to form the conduit. The entire pad may then be
formed as already disclosed.
Another way to form the article with the conduit layer 10a is
illustrated in FIG. 4 wherein the heated platen of the desired
shape is generally designated by reference numeral 40, and a flat
base or support plate is designated 41. In this embodiment, the two
sheets comprising the conduit layer 10a are designated respectively
10b and 10c, and they are united at the same time the article is
formed. However, it is preferred to preform the coverings 11 and 12
as previously disclosed. In this embodiment, the covering layers
11, 12 are not provided with peripheral borders for uniting them
together; rather, the heat of the platen 40 forces the interior
surfaces of the absorbent core material layers 13, 16 into contact
with the outer surfaces of the films 10b, 10c, thereby to embed the
core material into the thermoplastic layers 10b, 10c continuously
throughout the previously described shapes 34, 35 which define the
conduit. Thus, the covering layers 11, 12 are directly adhered to
the conduit 10a, and the two sheets 10b, 10c are laminated together
to form the conduit 10a, all in a single step.
Under certain circumstances, particularly when it is desired to use
a cooling source of fixed capacity which is small enough to be
portable (for example, one that is capable of producing 400 Btu.
per hour, it has been found desirable to further enhance the
thermal insulation of the outer layer of the conduit 10a against
heat loss through conduction. We have found that heat loss to the
atmosphere through conduction may be minimized by adjusting the
thicknesses of the two layers 10b, 10c of the conduit 10a. For
example, if the outer layer has a thickness of about 10 mils or
greater (and up to about 25 mils) and the inner layer (that is, the
one closest to the application area) is of lesser thickness, for
example, about one mil thick. A central conduit layer such as this
may also be combined with a reflective layer of the type designated
30 in FIG. 3 to further minimize heat through radiation, as
disclosed above.
In the case in which the grid material is spun-bonded nylon and the
absorbent core is paper wadding, the absorption rate has been found
to be very high because the core is pressed into close contact with
the underside of the grid material and the thermoplastic film
separates within the closed boundaries of the spun-bonded nylon,
even though the apertures in spunbonded nylon are smaller than in
most cotton scrims.
An applicator thus formed has been found to provide a very rapid
absorption characteristic together with a high capacity for
absorbing and holding liquid. The finished product has a soft feel
to it, provides greater padding than cotton, has greater absorption
capabilities than gauze, and is highly resistant to passing
absorbed fluids back into a wound.
In order to form the applicator into an integral pad, the
individual film layers 14, 17 and the external grid materials 15,
18 may be cut to a slightly larger peripheral dimension so as to
form a border of about 3/8 in. During the application of heat and
pressure, then, this peripheral border will cause the two external
grid materials 15, 18 to be bonded together while permitting
openings for the inlet and outlet apertures to the central conduit
layer 10. Alternatively, the covering may be attached only to one
side of the conduit layer, or it may be wrapped around the conduit
layer and sewn about the three other sides, leaving room, of
course, for the inlet and outlet stubs.
In selecting the material for the conduit layer 10, it is preferred
to use a thermoplastic material which will form a liquid-tight
conduit, and the materials should be resistant to attack by
commonly used chemicals in medical applications, it should be
non-toxic, and easily sterilizable, capable of holding liquids in a
temperature range of 25.degree. F. to around 125.degree. F. for an
extended period of time without deterioration and without leaking.
We have found that sheets of thermoplastic polyethylene or
polyvinyl chloride having a thickness of approximately 0.003-0.010
in. is suitable.
As an alternative to the use of the thermoplastic bonding layers
14, 17, a suitable resin adhesive may be applied as by spraying it
on the wadding layer and then pressing the exterior grid layer
against the adhesive. One suitable adhesive is solid polyvinyl
acetate resin dissolved in denatured ethyl alcohol with a small
amount of ethyl acetate to keep the resin in solution. The formula
is Z8097 adhesive, as denoted and manufactured by Swift Chemical
Company of Chicago, Illinois.
In summary, the present invention provides for a thermal applicator
for medical uses which is flexible and will conform to the contour
of the portion of the body where application is desired. It permits
the application of either heat or cold to the body. One of the most
important advantages of the present invention is that it provides
an applicator which can be packaged in a sterile condition (for
example, gas sterilization) and remain sterile until the package is
opened for use. Once used, the cost of the applicator is small
enough so that it can be disposed of.
The applicators of the present invention can be fabricated to
different sizes and shapes so as to provide an extended range of
different size applicators, and they may be formed to any desired
shape to conform to any part of the anatomy. For example, they
could be formed into concave surfaces or diaper-shape or
otherwise.
The inventive applicator may be used either as a surgical pad for
application to an open wound or incision, and it has the desirable
characteristics of being highly absorbent, it will absorb any
liquid with which it comes into contact very rapidly, it will hold
such liquids without undue seepage of the liquids back into the
wound, and it provides a non-sticking, yet non-sliding contact
surface. The applicator of the present invention may also be used
as a bandage or wound covering; or it may simply be used as a
comfortable hot or cold applicator. In this respect, the present
invention permits the application of heat or cold through a wet
covering. Sterile water may be poured directly onto the applicator
before or after it is in place, thereby wetting the highly
absorbent layers 13, 16 and substantially enhancing the thermal
conductivity between the source of heat or cold and the body area
of application. Further, medication or a sterilizing medium in
liquid form may be applied in a similar manner.
Having thus described preferred embodiments of our invention,
persons skilled in the art will be able to modify the structure of
the applicator that has been illustrated and to substitute
equivalent materials for those which have been disclosed while
continuing to practice the principle of the invention; and it is,
therefore, intended that all such modifications and substitutions
be covered as they are embraced within the spirit and scope of the
appended claims.
* * * * *