Dressing

Details Dressing Dressing

2001-09-13

2004-11-23

Calvert, John J. (Department: 3761)

Surgery: splint, brace, or bandage

Bandage structure

C602S043000

Reexamination Certificate

active

06822132

ABSTRACT:

This invention relates to a multi-ply dressing which can be used especially at pressure points, on blisters and open blisters on the heel, on the ball of the thumb and on the fingers.
Pressure points, blisters and open blisters on the heel, on the ball of the thumb and on the fingers are customarily cared for with conventional plaster products consisting of a textile carrier material, a pressure sensitive adhesive layer and a nonwoven wound contact material.
Proven products of this type are available for example from Beiersdorf, for example under the name of Hansaplast® elastic or Hansaplast® classic.
Plasters of this type, however, have some disadvantages in use:
Friction in the shoe causes gradual detachment of the plaster
Soiling of the carrier material on prolonged wearing
Little cushioning
Pressure points at the edge of the plaster
Painful removal
Modern wound management products such as hydrocolloids (see for example “Hydrokolloide” by R. Lipmann in “Medical Device & Diagnostic Industry”, June 1999), which were developed for colostomy and professional wound management applications, are increasingly used for pressure points and blisters.
Wound management products based on hydrocolloids have advantages over traditional plasters. They generate a moist wound healing medium which stops the wound drying out and creates an optimal medium for rapid wound healing. Further advantages are the inconspicuity in use, secure adherence, absorption of exudate (from a blister for example), good cushioning and painless removability.
Typical compositions of the first commercially available hydrocolloids for wound management products comprise:
Low molecular weight polyisobutylene (40% by weight),
Pectin (20% by weight),
Sodium carboxymethylcellulose=CMC (20% by weight)
Gelatin (20% by weight)
Modern hydrocolloid formulations, known as integrated formulations, as available for example from Coloplast, are based on styrene-isoprene-styrene block polymers with hydrocarbon resins as tackifiers, mineral oil as a plasticizer and also CMC as an absorbent.
These formulations with SIS as scaffold formers contain glassy domains (styrene blocks) and thermoplastic domains (isoprene blocks). At room temperature, the glassy domains provide a kind of three-dimensional crosslinking structure, which disappears at higher temperature.
Hydrocolloids possess good wet tack even under moist conditions, so that they are very useful as blister plasters on the heel and palm of the hand, an application site involving a relatively high moisture loss from the skin.
EP 0 264 299 B1 discloses a dressing consisting of a water absorbent sealing pad which in turn is formed of one or more hydrocolloids. The hydrocolloid or hydrocolloids are dissolved in or mixed with a binder.
The pad is firmly and completely enclosed by a watertight cover layer. According to the invention, the pad is beveled at least along the outer periphery such that the thickness at the edge does not exceed about one quarter of its maximum thickness.
Hydrogels are macromolecular, natural or synthetic materials which contain a high level of hydrophilic groups and are consequently capable of absorptively binding water. The water absorption capacity of many hydrogels is the multiple of their own weight in the water-free state.
Hydrogels are used in wound management in various forms, since they protect wounds against drying out, absorb wound exudate, serve as a matrix for active substances of all kinds and also as a basis for colonization with autologous or heterologous skin cells.
Hydrogels may be used in the form of foams, inter alia. Foams for managing skin wounds or surgical wounds are known per se to one skilled in the art. Polyurethane foams or collagen foams are used in the main.
Self-adhesive gel foams are likewise known to one skilled in the art. They are generally readily fixable on the skin, but usually have the disadvantage that their water absorption capacity and their water retention capacity are substantially limited.
Also known are hydrophilic foams of polyurethane gels. WO 88/01878 A1 describes self-adhesive polyurethane foams or polyurethane foam gels which can contain copolymerized methacrylate units among others. These foam gels are produced by adding water.
Polyurethane gels based on a polyurethane matrix and high molecular weight polyols are also described in EP 0 057 839 B1. Self-adhesive sheet materials comprising polyurethane gels are known from EP 0 147 588 B1. The polyurethane gels disclosed in these last two references cited are unfoamed.
The self-adhesive gels have isocyanate indexes of 15 to 70 (EP 0 147 588 A2).
EP 0 196 364 A2 describes hydrophilic polyurethane foams which may be filled with water absorbent polymers based on a copolymer of acrylic acid and potassium acrylate and are intended for medical purposes. The polyurethane is prepared on the basis of MDI. The polyether used has a minimum functionality of two hydroxyl groups, preferably two to three hydroxyl groups in each case. The NCO/OH ratio is stoichiometric. The polyurethane is accordingly not gellike. It can be foamed with pressurized air or with other gases which do not react with isocyanate or by means of low-boiling solvents. Absorbent and polyetherpolyol are mixed in a ratio of about 3:1. The foam has adhesive properties on wounds, which have to be completely eliminated by means of an aluminized veil in order that the foam may be used for wound treatment.
Foam wound contact materials as obtainable for example from Beiersdorf under the name of Cutinova® thin and Cutinova® hydro are described inter alia in DE 42 33 289 A1, in DE 196 18 825 A1 and WO 97/43328.
According to these references, the polyurethane gel foam consists of a polyaddition product of a polyetherpolyol (Levagel® from Bayer AG) with an aromatic or aliphatic diisocyanate (Desmodur® Bayer AG), into which a polyacrylate superabsorbent powder (Favor®, Stockhausen) has been incorporated. The polyurethane gel can be made weakly or strongly self-adherent to skin depending on the ratio of OH equivalents of the polyol to reactive isocyanate groups.
The sheetlike polyurethane gel foam from 1 to 6 mm in thickness is covered by a polyurethane foam on one side. Plasters of appropriate size are punched out of the bale material. The wound contact material thus produced surprisingly abheres completely on absorption of wound fluid and, in the process, does not show the tendency, known from hydrocolloids, to disintegrate on pronounced swelling, which may lead to residues of the hydrocolloid to remain in the wound.
The punched-out large-area wound contact materials are very useful for managing chronic or slow-healing wounds of patients who have to be treated in hospital.
In the case of smaller minor injuries or blistering due to pressure points on the hand, ball and heel, however, this product construction has some disadvantages.
The product tends to curl under mechanical loading, owing to its punching edges. The open punching edges prove to be a disadvantage on contact with moisture, since they provide a way for water to get into the absorbent layer and cause swelling and abhering of the polyurethane gel.
Finally, blister management additionally utilizes traditional plasters (for example the Hansaplast® classic fabric plaster from Beiersdorf) which are only contingently useful as blister plasters for the care of pressure points or damaged horny skin on highly contoured parts of the body.
Disadvantages prove to be the low elasticity and the tendency for the carrier material to curl up at the edges of the plaster when subjected to mechanical loading in the course of prolonged wear. Additionally, the plaster is substantially wetted through in the course of daily ablutions or hand washing and loses adhesion.
Traditional plasters are visually very conspicuous, hinder movements and impair the wear comfort in shoes.
It is an object of the present invention to provide a dressing which is capable of absorbing exudate from pressure points, which is well cushioned, which has a sufficient transmission rate for moisture

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