US3491753A

US3491753A - Medical dressings

Info

Publication number: US3491753A
Application number: US790918A
Authority: US
Inventors: William Frank Milton; Harvey Brockenshaw; John Leathley Shaw
Original assignee: Price Brothers and Co Ltd
Current assignee: Price Brothers and Co Ltd
Priority date: 1969-01-14
Filing date: 1969-01-14
Publication date: 1970-01-27
Anticipated expiration: 1987-01-27

Description

Jan. 27, 1970 l I W. F. MILTON ETAL 3,491,753

, MEDICAL DRESSINGS Filed Jan. 14, 1969 2 Sheets-Sheet 1 Jan. 27, 1910 w, F. MILTON ET AL- MEDICAL DRESSINGS 2 Sheets-Sheet 2 Filed Jan. 14, 1969 FIG. 6.

United States Patent 3,491,753 MEDllCAL DRESSINGS William Frank Milton, Harvey Brockenshaw, and John Leathley Shaw, Wellington, Somerset, England, assignors to Price Brothers and Co. Limited Continuation-impart of application Ser. No. 570,611,

Aug. 5, 1966. This application Jan. 14, 1969, Ser.

Int. Cl. A61f 15/00 US. Cl. 128-156 10 Claims ABSTRACT OF THE DISCLOSURE A medical dressing, particularly suitable for use as an emergency burns dressing, comprises a sterile body of polyurethane foam material having interconnected cells and physical characteristics of density, indentation hardness, porosity and cell count within certain ranges, the foam body being contained in a sealed package to maintain sterility pending use.

The present application is a continuation-in-part of our earlier application No. 570,611 filed Aug 5, 1966, and now abandoned.

The present invention relates to medical dressings of a kind intended particularly but not exclusively for use in the treatment of burns.

Proposals have been made for the use of a foam pad or mattress in the treatment of burns, a patient being allowed to rest upon such a mattress or pad as part of the treatment. Recovery of the patient from the burn is aided by the exposure to air and the support of the foam material, the foam material permitting free access of air to the wound.

It has now been found that the structure of the foam influences strongly the efliciency of the foam in treatment of burns. More specifically we have now found certain foams provide the patient with sufficient support and comfort whilst simultaneously accelerating the healing process and minimizing the risk of infection. Polyurethane foams having interconnecting cells and the following combination of physical properties have been prepared and found to be successful in providing these improved results.

Property: Range of values Density ozs./cu. ft 20-30 Indentation hardness kg 18-26 Porosity cu. ft./min 514 Cell count per inch 40-50 The term indentation hardness as used herewith means the indentation hardness which as defined in British Standard No. 3667, part I (1963) as amended by Amendment No. 1 of Sept. 10, 1965, as published by the British Standards Institution, 2 Part St., London, England, this being a standard parameter employed in the art in defining the quality and structure of polyurethane foam. The indentation hardness index is the load in kilogrammes required to produce, under specified conditions, an indentation in the sample equivalent in depth to 50% of the initial thickness of the sample. Complete details of suitable testing apparatus and procedure are to be found in said British specification No. 3,667 and the disclosure of such specification, so far as material here, is to be taken as included in the present specification.

The term porosity as used herein means porosity as determined by the following method:

A circular slab of foam of cm. diameter and 1" thickness is placed in a suitable holder. Air is drawn through the sample and through an airflow meter, and the differential pressure across the sample is indicated on an inclined manometer.

"ice

The airflow is adjusted to a pressure of 0.5" W.G., and the resulting air flow, as indicated in cubic feet per minute, represents the porosity.

The term cell count means cell count per linear inch.

Polyurethane foam having such characteristics is able to hold the extensive exudate from serious burns whilst simultaneously having a sufficient porosity to air that exudate evaporates sutficiently fast to prevent saturation of the foam. It is important to prevent saturation, such as occurs by capillary action when a fibrous dressing is used, because in the saturated condition infection can travel easily from one area of the burn to another. With foams having interconnected cells similar capillary forces exist tending to disseminate the exudate from the burn throughout the foam but within the ranges specified for the physical characteristics of the foam these are balanced by the evaporative forces. It is the attainment of this balance, enabling the foam to receive the total exudate whilst simultaneously keeping the foam locally permeated only, which is the basis of the present invention.

The present foams may be adapted for use in a wide variety of medical dressings as will be more fully described hereinafter. It is important, however, to maintain the foam sterile pending use and accordingly the package for the medical dressing should be sealed. Preferably, the dressing is sealed Within its packaging means and the whole then sterilized by exposure to gamma radiation. The present invention therefore includes also particular packaging arrangements for the dressings and shapes of the dressing themselves. Certain of the present dressings are moreover particularly useful where a large number of persons have suddenly to be treated, or where treatment is required for persons prior and during their transit to a hospital.

A principal object of the present invention is accordingly to provide an improved medical dressing of foam material particularly suitable for the treatment of burns.

It is a further object of the present invention to provide a med-ical dresing of a foam material having means whereby it can be secured on a patient where required.

It is also an object of the invention to provide a medical dressing of foam material which is adapted for use as a transit dressing.

An additional object of the invention is to provide a medical dressing for embracing one or more limbs and/ or the torso of a patient, the dressing having securement means which do not involve application of pressure to the patient.

A still further object of the invention is to provide an improved polyurethane foam medical dressing.

Thus in a general aspect the present invention provides a medical dressing comprising a sterile body of polyurethane foam material having the physical characteristics hereinbefore described and sealed packaging means containing the body of foam material, the packaging means being sealed to maintain sterility of the body of foam material pending use.

If desired, the foam may be sprayed with silicone solution to reduce risk of adhesion or impregnated with a medicament. The foam material can be provided with a backing material on one side thereof, suitably a fabric, for example, cotton or crepe material, or a plastics sheet material having permeability characteristics similar to those of the foam material, or an impermeable plastics sheet depending on the precise nature of the burn or other aflliction to be treated.

Any convenient means for securing the dressing in a desired position on a patient can be provided or employed, as long as use of the securing means imposes no undue stresses and strains upon the patient. This latter requirement is particularly important where burns are involved, since these leave the skin of the patient in a sensitive state,

both in the burnt zones and surrounding unburnt areas. The securing or fastening means can be such as to connect with itself, as in the case of tapes and buckles, stud fasteners or interconnecting fabric fasteners of the socalled touch-and-clo-se type (marketed under the registered trademark Velcro) where connectible parts are disposed at opposed edges of the dressing. The securing means can instead be such as to adhere to the skin of the patient on opposed sides or all round the affected area.

The former kind of fastener is preferably provided at the edges of the dressing so as to reduce or obviate lines of pressure on the patient, and can be secured to the body of the dressing by the backing material. This kind of fastener is particularly suited for larger dressing, as for use in hospitals or in transit of patients to hospitals. The kind using adhesives is more appropriate to smaller dressings such as may be kept available as in first aid kits for use at home or in the factory or relatively small burns.

Other objects and advantages of the invention will appear from the following description.

In the drawings:

FIGURE 1 is a sectional side view of a first medical dressing in accordance with the invention, the dressing being shown within its sterile packaging;

FIGURE 2 is an end view of a second dressing in accordance with the invention, the dressing being shown in a position partially withdrawn from its packaging;

FIGURE 3 is a view of the dressing of FIGURE 2 in position of use;

FIGURE 4 is a view resembling FIGURE 3 of a further form of dressing in accordance with the invention, a different securing means being used;

FIGURE 5 is a sectional side view of a dressing similar to that of FIGURE 1, but with a different backing material for the foam body; and

FIGURE 6 is a sectional side view of a still further form of dressing in which the backing is intended to be attached in situ to the foam body.

Referring to the drawings, FIGURE 1 shows a medical dressing 10 including a rectangular pad 11 of polyurethane foam material.

Over the lower major face of the pad 11 is secured a rectangular piece 12 of a previous woven cotton backing fabric, the backing being of greater area than the pad so as to have portions 13 extending on two opposed sides of the pad. On the face of each of the portions 13 is provided a layer of adhesive material 14 capable of adhering to itself or to the skin of a patient. The adhesive material is preferably of the pressure-sensitive kind. Strips of

paper

15, 16 overlie the adhesive layers and overlappingly extend to protect the upper major face of the foam pad 11. The paper strips 15, 16 can be peeled off from the adhesive material layer 14 before use, this action being facilitated by the overlap, which leaves an edge of one of the strips unsecured. The edge of the other strip underlying the overlapped portion is folded back at 17 so as to provide an unsecured portion for this other strip. Thus by peeling off the strips from the centre, the dressing can be obtained ready for application, and secured in place all Without the need for touching either the pad or the adhesive layers.

Dressings of this general kind can have a wide variety of shapes and sizes. The pads and backing sheets can for example be circular. The thickness of the pad is of the order of but can be more when the dressing has a large area and substantial cushioning of the wound is required.

The sterility of the dressing pending use is ensured by sealed packaging comprising thin plastics sheet material 18 peripherally sealed around the dressing at 19. The dressing may be placed between the two layers of plastics sheet material in the sterile condition prior to scaling but preferably scaling is effected and the whole package subsequently sterilized as by exposure to gamma radiation.

Referring now to FIGURES 2 and 3 of the drawings, a second dressing 20 according to the invention comprises a sheet 21 of polyurethane foam material of approximately /:t" thickness. The sheet is rectangular and its size is sufficient for a cocoon to be formed around the trunk or one or both arms or legs of a patient. The foam sheet 21 is stored pending use in ro-lled form within a sealed container 22 from which the sheet is shown somewhat projecting in FIGURE 2. The container may be of plastics material and may be opened for removal for use of the dressing as by a peripheral tear strip removable to free the edge 23 of the container. So that no pressure need be applied to the patient whilst the dressing is being secured, the operation is carried out by bringing toge her the edges of a single major face of the sheet. Thus, where the sheet surrounds a limb, instead of overlapping and pressing down the inner face at one longitudinal edge of the sheet over the outer face at the other longitudinal edge, which would apply pressure to the limb, the inner faces of the two edges are made to engage and to extend outwardly of the cocoon formed by the rest of the bandage as shown in FIGURE 3.

To this end a plurality of tabs or short strips 24 of Velcro hook material or the like is provided along one edge of the sheet, with the strips projecting beyond this edge. Similarly shaped strips of Velcro loop material are arranged to project beyond the opposite edge of the sheet. The strips can be secured by adhesive or stitching but one side of the foam sheet 20 can be provided with a backing layer 26 of cotton fabric and the

strips

24, 25 can then be secured as by stitching to this fabric backing. The operative faces of both the strips are in any event arranged to face in the same direction with other portions of these faces secured to the side of the foam sheet which will be outward in use.

Thus the sheet 20 can be unrolled when removed from the container, the patients limb or torso placed upon it and the dressing secured by bringing up the edges and pressing together the effective surfaces of the fastener strips. Although the

tabs

24, 25 could be replaced by tapes for tying, by tapes providing pressure-sensitive adhesive faces, or by lengths of touch-and-close or adhesive fastener along the entire edges of the sheet, the use of spaced touch-and-close fasteners as described is preferred as these provide a readily releasable but firm anchoring of the two sides of the dressing without the use of undue pressure to effect the anchorage or the application of localised lines of pressure on the patient after such anchorage has been effected. In a further dressing according to the invention separate fasteners can be supplied for securing the foam sheet. As shown in FIGURE 4, suitable fasteners 30 comprise heads 31 with a pair of deformable metal strips 32 extending therefrom. The strips, which preferably have tapered ends, are pushed through the two edges 33 of an unbacked foam sheet 34 brought together in the same relation as indicated in FIG- URE 3 and the strip ends are bent over to secure the edges together between the head and the bent over ends. It will be evident that the fastening means allows a large dressing to be simply cut down in size whenever the intended use makes this appropriate.

Sterility of the transit dressings of FIGURES 2, 3 and 4 is again secured preferably by exposure to gamma radiation of scaled packages containing the dressings. Irradiation in two cycles is preferred with dosages respectively of 1.3 megarads and 1.2 megarads. The total exposure of 2.5 megarads ensures absolute sterility whilst the package does not become radioactive.

The dressing shown in FIGURE 5 is similar to that shown in FIGURE 1, except that the piece of cotton backing fabric 12 is replaced by a similarly shaped piece 35 of impermeable plastics sheet material, for example polyvinyl chloride sheet material of thickness 0.0035- 0.007, preferably 0.005; alternatively, sheets of polyurethane, polyethylene vinyl acetate, polyvinylidene chloride and other polyvinyl halides, polyolefines, polycarbonates, and polyesters for example polyethylene terephthalate. This plastics backing 35 is covered, as in FIG- URE 1, with adhesive 14 and overlying paper strips 15, 16. On account of the impermeable nature of backing 35, this dressing is less suitable for treatment of serious burns since evaporation can take place only through the side faces of pad 11. It is therefore preferably used for treatment of small burns or afiiictions of other nature.

The dressing shown in FIGURE 6 is again generally similar to that of FIGURE 1, except that the piece of cotton backing fabric 12 is replaced by a strip of impermeable adhesive-coated plastics sheet material 36 contained loose within the sealed package indicated generally at 37. This strip may suitably again be polyvinyl chloride sheet material and is covered completely by overlying overlapping paper strips 38. Thus in use the package is broken open, the paper strips 39, peeled off and the adhesive coated-surface of the plastics sheet applied to the pad 11 of foam material, either before or after that pad is applied to the affected area.

The strip 36 is substantially narrower than the width of pad 11; hence, although it is itself impermeable, the pad is only partially covered and inhibition of evaporation is substantially less than with the dressing of FIG- URE 5.

In place of a single adhesive-coated backing strip the packaged assembly may of course contain two or even more of such strips an it will be appreciated that by appropriate selection of the size of pad 11 and width of strips 36 the portion of the pad covering the burn can be left entirely unbacked, so providing optimum conditions for evaporation of exudate.

Sterility of the dressings of FIGURES 5, 6 is again secured by exposure to gamma radiation of the sealed packages as previously described.

For all of the dressings of FIGURES 1 to 6 a particularly suitable foam is a polyether-based polyurethane foam having interconnecting cells and the following physical properties:

Property: Value Density ozs./cu. ft 26-28 Indentation Hardness kg 21-24 Porosity cu. ft./min -12 Cell count per cubic inch 45 As mentioned above, dressings embodying the invention can comprise foam sheets of any convenient size and shape, Conveniently, a range of sizes and shapes can be provided so as to suit the parts of the human body. The provision of such a range of sizes and shapes allows the human body to be swathed from head to fo ot in the dressings. The use of touch-and-close fastening means allows latitude of adjustment so that it is unnecessary to provide a very large number of different sizes of dressings; the fastener allows a dressing of one particular size to be used on persons of different body size.

When such a dressing is applied to the burnt part of the body of a patient the healing process commences immediately. As the foam material is pervious to air, air is able to reach the wound through the foam and any discharge from the wound is drawn off by capillary or other action, for example, as a result of pressure differences. Movement of the body against the foam cells stimulates circulation in the body tissues and healing is thus further assisted. It is to be noted that the foam should be of sufiicient thickness to cushion the wound from physical shocks. Foams of approximately /2" thickness have been found suitable for use as transit dressings.

The structure of the foam is such as to afford the essential degree of absorption of exudate from the wound and the protection from further injury or trauma while the patient is in transit. Bacteriological controls are preferably applied to ensure that the dressing is supplied sterile and can be maintained in a sterile condition without the need for any special precautions.

Variations and modifications may be made within the scope of the claims and portions of the improvements may be used without others.

We claim:

1. A medical dressing comprising a sterile body of foam material in the form of a generally rectangular thick sheet and packaging means containing the body, the packaging means being sealed to maintain sterility of the body pending use, said sheet having substantial thickness for use as a transit dressing and being of such length, width and flexibility as to wrap but once about a major portion of a patients body, such as the torso and/or limbs, and provide outwardly extending longitudinal edge portions which may be brought together and fastened face-to-face to secure the sheet around the portion of the patients body to which the sheet is applied, and fastener means to secure the outwardly extending longitudinal portions of the sheet together in face-to-face engagement.

2. A medical dressing according to claim 1 in which fastener means are along the edge portions of the side of the sheet disposed inwardly towards the bod of the patient.

3. A medical dressing comprising a sterile body of foam material in the form of a generally rectangular sheet and packaging means containing the body, the packaging means being sealed to maintain sterility of the body pending use, said sheet having substantial thickness for use as a transit dressing and being of sufiicient width and length to surround the torso and/or limbs of a patient, said sheet being sufficiently flexible to be rolled upon itself into elongate cylindrical form, and said packaging means being tubular to receive the rolled sheet and retain the cylindrical form thereof and maintain the sterility of the sheet prior to removal for use, the foam material having interconnected cells and the cell count of about 40 to about 50 per cubic inch and porosity of about 5 to about 14 whereby the capillary dissemination of exudate through the foam on being applied to a burnt zone of a patients body is balanced by evaporation of exudate, thereby substantially confining exudate to the local portion only of the sheet adjacent the burnt zone.

4. A medical dressing as claimed in claim 1 in which the fastener means comprises a first series of tapes spaced along one of the edge portions and projecting therebeyond, and a second series of tapes spaced along the other of the edge portions and projecting therebeyond, the two series of tapes being spaced along the edge portions at registering positions and each tape of the first series being adapted to releasably engage the registering tape of the second series in the manner of a touch-and close fastener.

5. A medical dressing as claimed in claim 4 in which a flexible but substantially inextensible layer of backing material is secured over the major face of the sheet of foamed material, the tapes being secured to the backing ayer.

6. A medical dressing as claimed in claim 1 in which the sheet of foamed material is rolled into a generally cylindrical shape within the packaging means, with the major face of the sheet to be disposed towards the body portion inwards of the roll.

7. A medical dressing as claimed in claim 1 in which the thickness of the sheet of foam material is not less than one half of an inch.

8. A medical dressing as claimed in claim 1 in which the foam material has interconnected cells and a cell count of about 40 to about 50 per cubic inch and a porosity of about 5 to about 14 whereby the dissemination of exudate through the foam on being applied to a burnt area of a patients body is balanced by evaporation of exudate, thereby substantially con-fining exudate to the local portion only of the dressing adjacent the burnt zone.

9. A medical dressing comprising a sterile body of foam material and packaging means removably containing the body, the packaging means being sealed to maintain sterility of the body pending use and the foam material having interconnected cells and a cell count of about 40 to about 50 per cubic inch and porosity of about 5 to about 14 whereby the capillary dissemination of exudate through the foam on being applied to a burnt zone of a patients body is balanced by evaporation of exudate, thereby substantially confining exudate to the local portion only of the dressing adjacent the burnt zone, the sterile body of foam material being in the form of a pad having secured to one face thereof a backing of permeable material having on at least one end portion extending beyond the edge of the pad a pressure-sensitive adhesive coating and a removably protective strip covering said adhesive coating pending use.

10. A medical dressing comprising a sterile body of foam material and packaging means removably containing the body, the packaging means being sealed to maintain sterility of the body pending use and a foam material having interconnected cells and a cell count of about 40 to about 50 per cubic inch and porosity of about 5 to about 14 whereby the capillary dissemination of exudate through the foam on being applied to a burnt zone of a patients body is balanced by evaporation of exudate, thereby substantially confining exudate to the local portion only of the dressing adjacent the burnt zone, the sterile body of foam material being in the form of a pad having secured to one face thereof a backing of impermeable material having on at least one end portion extending beyond the edge of the pad a pressure-sensitive adhesive coating and a removably protective strip covering said adhesive coating pending use.

References Cited UNITED STATES PATENTS 2,740,402 4/1956 Scholl 128-156 3,214,501 10/1965 Strauss a 128-156 3,256,881 6/1966 Stenvall 128156 ADELE M. EAGER, Primary Examiner US. Cl. X.R.