Title:
DISPOSABLE, STERILE TEMPERATURE CONTROL APPLICATOR PAD FOR MEDICAL APPLICATION
United States Patent 3867939


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)
Application Number:
05/381733
Publication Date:
02/25/1975
Filing Date:
07/23/1973
Assignee:
MOORE-PERK CORPORATION
Primary Class:
Other Classes:
607/104
International Classes:
A61F7/02; A61F7/00; (IPC1-7): A61F7/00
Field of Search:
128/254,400,399,402,403,296,156,287,290
View Patent Images:
US Patent References:
3678933SURGICAL SPONGE OR BANDAGE1972-07-25Moore et al.
3446208POROUS POLYOLEFIN GAUZE1969-05-27Fukuda
3331728Perforate film-fiber laminate1967-07-18Lane
3092112Therapeutic compress1963-06-04Zelony
2923298Unitary non-adherent dressings1960-02-02Dockstader et al.
2726658Therapeutic cooling devices for domestic and hospital use1955-12-13Chessey
2250325Thermal device1941-07-22Barnes
2198989Wet compress1940-04-30Cooley
2110022Cover1938-03-01Kliesrath



Primary Examiner:
Gaudet, Richard A.
Assistant Examiner:
Yasko J.
Attorney, Agent or Firm:
Dawson, Tilton, Fallon & Lungmus
Parent Case Data:


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°-400° 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° and 400° 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° F. to around 125° 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.