Abstract:
Occlusive dressing system, which comprises an endless, elongated, flexible, adhesive barrier, adapted to be arranged in a closed configuration, whereby to bound and define a surface area, and an impermeable sealing film adapted to overlie said surface area and to isolate it from the environment, when superimposed to said barrier arranged in said configuration, said barrier forming a gas-tight seal with said sealing film when the two are applied to and pressed against one another. A spreading mechanism that alows a single person to spread the sealing film over the occluding barrier and to detach the film from the main roll and ports (inlet and outlet) that can be placed across the barrier or the occluding film.

Description:
FIELD OF THE INVENTION 
   This invention relates to an occlusive dressing system, for use in skin therapy. 
   BACKGROUND OF THE INVENTION 
   The goal of any medical dressing is to promote the natural healing and/or regeneration processes by providing the tissues with the optimal conditions for the healing phenomenon. 
   The dressings may be divided into two general groups:
         (a) open dressings, where a rather free exchange of matter (e.g. gases, fluids, germs) may take place between the wound and the external environment; and   (b) occlusive dressing, where an impermeable barrier separates the wound and its immediate environment from the external environment and the atmosphere.       

   Basically, the occlusive dressings are made of impermeable films and the peripheries of their undersurface are coated with a thin layer of pressure sensitive, biocompatible adhesive. The dressings may contain various medicines in a form of thick gels, ointments or granules or even the film itself may be impregnated or medicated with the desired medicine. The open dressings are mostly made of porous or fibrous materials such as knotted fiber, gauze or non-woven cottons, wool or other natural or synthetic substances. Their contact with the wound surface may produce favorable healing conditions depending on the dressing nature and the exchange equilibrium with the external environment. 
   Obviously the occlusive dressings offer a better opportunity to control the wounds immediate environment, and to protect it from harmful external factors. The drawbacks of these dressings are their cost and complexity of application. 
   PCT Application No. WO 85/01439 discloses a protective waterproof covering for an animal body. The covering is a thin, flexible, lightweight waterproof material such as polyethylene and is shaped to conform to that part of the body to be covered. The covering has means for attachment to the body. The coverings may be attached using pressure sensitive adhesive applied about the edge region of the covering or by using elasticized bands. 
   EP-A 0 117 714 A2 discloses a device for protecting a wound comprising a pad of skin-protective and skin-curative adhesive material to which is secured a foldable sheet of liquid-impermeable material of larger area than the pad, marginal areas of said sheet being provided with a sealing means, and said sheet being located and dimensioned so that said sheet when folded over on itself is sealed in liquid-tight fashion around its edges to define a compartment. 
   PCT Application No. WO 96/15745 discloses a wound treatment device for attachment to a patient&#39;s skin surface which comprises a wound attachment portion lying in contact with a patient&#39;s skin surface, a wound treatment portion defining a wound treatment area on the patient&#39;s skin surface and a transition portion for coupling the attachment portion to the wound treatment portion which includes a membrane connected to the attachment portion proximate to the patient&#39;s skin surface and connected to a standoff included in the wound treatment portion. 
   DE-A-1963375 discloses a touch-free protection system for sensitive skin areas, characterized in that a distancing material comprising a gap or gaps is applied by using its self-adhesive property between a cover and a skin region. 
   PCT Application No. WO 85/01439 discloses a protective waterproof covering for an animal body. The covering is a thin, flexible, lightweight waterproof material such as polyethylene and is shaped to conform to that part of the body to be covered. The covering has means for attachment to the body. The coverings may be attached using pressure sensitive adhesive applied about the edge region of the covering or by using elasticized bands. 
   EP-A 0 117 714 A2 discloses a device for protecting a wound comprising a pad of skin-protective and skin-curative adhesive material to which is secured a foldable sheet of liquid-impermeable material of larger area than the pad, marginal areas of said sheet being provided with a sealing means, and said sheet being located and dimensioned so that said sheet when folded over on itself is sealed in liquid-tight fashion around its edges to define a compartment. 
   PCT Application No. WO 96/15745 discloses a wound treatment device for attachment to a patient&#39;s skin surface which comprises a wound attachment portion lying in contact with a patient&#39;s skin surface, a wound treatment portion defining a wound treatment area on the patient&#39;s skin surface and a transition portion for coupling the attachment portion to the wound treatment portion which includes a membrane connected to the attachment portion proximate to the patient&#39;s skin surface and connected to a standoff included in the wound treatment portion. 
   DE-A-1963375 discloses a touch-free protection system for sensitive skin areas, characterized in that a distancing material comprising a gap or gaps is applied by using its self-adhesive property between a cover and a skin region. 
   Two inherent problems of the present occlusive dressings are: 
   (a) the difficulty in occluding efficiently the irregular body&#39;s topography especially where large areas are involved; and 
   (b) the limitation in changing the nature of the dressing&#39;s contents and the occluded wound&#39;s micro environment without disrupting or replacing the entire dressing. 
   This is the reason why the existing occlusive dressings are rather small and specific, and are designed to be used only in small and usually chronic wounds such as pressure sores, legs ulcers and stomal wounds. At present, in addition to the traditional cotton gauze dressings, there exists a plethora 
   of other kinds of dressings made of natural or synthetic materials each designed to provide a specific factor or component to the healing process. Even if we were to assume that each dressing&#39;s claims are truly fulfilled, the complex healing process and its ever-changing demands require a close monitoring and selection of a new appropriate dressing from the ever-growing dressing&#39;s armamentarium to satisfy the new demands. 
   It is a purpose of this invention to overcome the drawbacks of existing occlusive dressing systems. 
   In particular, it is a purpose of this invention to provide an occlusive dressing system which can conform to and occlude any area of the body of a patient regardless of his size, shape, location or skin irregularities. 
   It is another purpose of this invention to provide such a system which may contain any medicament, other desired substances or a specific physical environment in the form of solids, gels, ointments, liquids, gases or electrical and magnetic fields. 
   It is a further purpose of the invention to provide such a system the contents of which may be changed as desired and thus increase, decrease, change or replace, without disrupting or changing the dressing itself. 
   It is a still further purpose of this invention to provide such a system which permits the physical features of the dressing to be designed to promote specific biological activities in the occluded micro-environment of the affected area. 
   It is a still further purpose of the invention to provide such a system which permits to control and modify the environment occluded and contained by the dressing without its disruption. 
   Other purposes and advantages of the invention will appear as the description proceeds. 
   SUMMARY OF THE INVENTION 
   The occlusive dressing system according to the invention comprises an endless, elongated, flexible, adhesive barrier, adapted to be arranged in a closed configuration, whereby to bound and define a surface area, and an impermeable sealing film adapted to overlie said surface area and to isolate it from the environment, when superimposed to said barrier arranged in said configuration, said barrier forming a gas-tight seal with said sealing film when the two are applied to and pressed against one another. 
   The term “endless”, with reference to the adhesive barrier, is to be construed as meaning that the barrier is substantially longer than required for making any single dressing. The condition that the barrier is “adhesive” means that its outer surface is adhesive and sealing. Therefore, the barrier may be made of adhesive and sealing material, e.g., an adhesive plastic or adhesive gel or paste, or it can be made of a flexible material that is not adhesive, but is covered with an adhesive and sealing layer. The two juxtaposed ends of the barrier will adhere to one another either end-to-end or side-to-side as the case may be, and thus the barrier may be gas-tight. 
   In a preferred form of the invention, the dressing system of the invention comprises means for providing, when open, a communication between the external environment and the space underlying said sealing film. Said communication means preferably comprise at least one valve or port connected to conduit means which have an inlet/outlet in said space underlying said sealing film and an inlet/outlet outside said space. 
   Optionally, said dressing system may further comprise a stabilizing and carrier matrix and/or a releasing system, as hereinafter defined and explained. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
       FIG. 1  illustrates in perspective view a section of a sealing barrier which is adhesive or coated with adhesive according to an embodiment of the invention; 
       FIG. 2  illustrates in perspective view a portion of a sealing film according to the invention; 
       FIG. 3  schematically illustrates, in top, plane view, a dressing according to one embodiment of the invention, applied to the wound or other affected area; 
       FIG. 4  schematically illustrates in plane view a valve applicable to an adhesive barrier according to the invention; 
       FIGS. 5   a  and  5   b  illustrate in schematic perspective view an adapter for applying a valve to a dressing according to an embodiment of the invention, wherein: 
       FIG. 5   a  is an adapter for the port passing under or over the sealing barrier; 
       FIG. 5   b  illustrates the application of a valve or port through a flat adapter to the sealing film itself; 
       FIG. 6   a  illustrates in schematic partial cross-section a dressing according to an embodiment of the invention applied to a skin surface; 
       FIG. 6   b  illustrates in schematic partial cross-section a dressing according to an embodiment of the invention applied to a skin surface; 
       FIG. 7  is a schematic top, plane view similar to that of  FIG. 3 , but illustrating another embodiment of the invention; 
       FIGS. 8   a ,  8   b  and  8   c  schematically and fragmentarily illustrate another embodiment of the invention, respectively in plane view, in perspective view from the outside of the wound or affected area and from the inside thereof; 
       FIG. 8   d  is an adapter for a conduit or a valved port to be placed on top of the occlusive film instead of passing through the barrier. 
       FIGS. 9   a  and  9   b  schematically illustrate two systems for modifying the atmosphere in the space between the occlusive dressing and the affected area according to embodiments of the invention; 
       FIG. 9   c  schematically illustrates a systems for changing the electrical field in the wound and permitting controlled ionophoresis; 
       FIG. 10  is a top, plane view similar to  FIG. 3  but illustrating another embodiment of the invention; 
       FIG. 11   a  illustrates in schematic perspective view a portion of a conduit according to the invention, made of two sheets of plastic material welded at the seam; and 
       FIG. 11   b  illustrates in schematic partial cross-section a leaf valve according to an embodiment of the invention that may be made of two flexible plastic sheets welded together. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  schematically illustrates an adhesive barrier  10  according to an embodiment of the invention, which barrier is constituted by a ribbon of plastic coated with any adhesive matter such as para or pale crepe rubber or poly(alkyl-acrylate) as described in “ Remington&#39;s Pharmaceutical Sciences” , Mack Publishing Company, 1990, page 1898, and other similar manuscripts, covered by a film  11  which protects said adhesive matter and is removed prior to the utilization of said barrier. Said barrier having, in the embodiment illustrated, a circular cross-section. Other cross-sections can of course be used and, as explained hereinafter, in some embodiments the barrier may be hollow or tube-like. 
   The barrier may consist of any material that is flexible and preferably sufficiently plastic and manageable to be used as explained hereinafter, and that is adhesive to the sealing film, hereinafter described, and adhesive, conforms and seals to skin irregularities and non-irritant and in general harmless to the human skin. An example of such a material is a biocompatible adhesive gel (such as RTV silicon or thick Vaseline paste). Alternatively, as has been said, the barrier may consist of a flexible, non-adhesive material, coated with an adhesive layer. An example of such a material is a soft, 3–10 millimeter thick foam cord, strip or band, of any suitable material, such as rubber, polyisoprene, RTV or silicon, coated with a thick layer of adhesive, such as described hereinbefore. Barriers made of such materials intimately conform to any skin irregularities and may surround any desired shape or size of affected surface. 
     FIG. 2  schematically illustrates a film spreader which an impermeable, sealing film  111  in the form of a rolled sheet. 
   The film can be made of any impermeable, preferably but not necessarily transparent, material, e.g., a synthetic polymer such as Saran, polyurethane, nylon or polyethylene. Said film may further consist of an electrically conductive material such as aluminum foil or carbon/metal impregnated plastic sheet. The roll of the film may for instance be rolled around a central rod  112 , or a bow  114  with two grasping clips at the ends  115  and  116 , when  116  may slide along the bow shaft, and the free edge strengthened and straightened by a rigid back  113  that allows a single user to spread the film easily. The bow with the clips may be replaced by any other rigid grasping rod or forceps that holds the free edge of the film. 
   The components of the occlusive dressing system are used to create an occlusive dressing in the following manner:
         (a) A first end of the endless elongated flexible adhesive barrier is placed close to the wounded or other affected area (the terms “wound” or “wounded area”, as used hereinafter, should be construed as comprising any area which it is desired, for any reason—not necessarily the presence of a wound—to enclose to protect or treat with the occlusive dressing), preferably at the periphery thereof, and is placed around and preferably close to said periphery until it completely encircles it; it is then cut (though, of course, it could have been cut before putting it in place):
           i) to a length appropriate to enable the cut end to be juxtaposed to said first end of said barrier, and the two ends are joined by pressing one to another lightly; or   ii) to a slightly greater length thereof to enable the cut end to lay side by side juxtaposed to said first end of said barrier, and the two ends are joined by pressing one to the other lightly;   iii) or in the case of an adhesive barrier materials such as putty or paste, RTV silicon or thick Vaseline paste they can be squeezed-extracted from their tube or syringe like container and spread in an abundant quantity (more than 1 cc. for a length of 1 cm. of the barrier) to encircle completely the desired area and constructing the adhesive barrier, thus forming a continuous, closed configuration surrounding the wounded area and generally a borderline area extending to some extent beyond said wounded area (the area thus surrounded by said closed configuration will be called hereinafter “the occluded area”). In some cases, when the wounded area is too large, said barrier may border only part of the affected area crossing the wounded area and occluding only part of the entire area.   
           (b) A portion of an impermeable sealing film, large enough completely to overlap the occluded area, generally separated from a film supply, such as a roll thereof, is superimposed to said barrier by spreading it manually or by using a specially designed “film spreader” and film container. As said, the film may be contained in a container that will allow it to roll out by pulling its free edge while holding the container. The container may contain or be replaced by a central pole around which the roll of the film can rotate. The free edge of the film can be strengthened with a rigid spreading back on an arc or bow with two grasping clips or a long jawed forceps that permits its orderly spreading using one hand. The container&#39;s edge at the film opening may be serrated or sharpened to permit its cutting. The cutting of the film from the entire roll may be eased by a small roller that while traveling along the serrated or sharpened edge cuts the film. Two rigid spreading backs may be used consecutively if more than one area should be covered. In this case one forceps-like rigid back is secured to the opening of the film container, the film passing through the jaws is held by the other similar forceps-like spreader and pulled out. To cut off the film one may use the serrated jaws of the spreader, a roller traveling along the holding jaws or any other cutting, shearing or perforating means along the jaw that is secured to the film container. The freed spreader is then inserted behind the first spreader (secured to the container) that becomes the spreader that will pull out the film.       

   The film is pressed lightly onto the adhesive barrier, thus pressing the latter onto the skin surface or other surface that it is wished to protect by means of the dressing. The film adheres to the barrier and the barrier adheres to said surface, whereby the occluded area is occluded essentially completely. The adhesive barrier and the film itself should not interfere or react in an undesirable manner with the patient&#39;s skin or other substances within the occluded area or with operations carried out therein. The complete seal of the occluded area allows to apply to it any form of medicines or substances, even liquids and gases. 
   A dressing resulting from a dressing system according to an embodiment of the invention is illustrated in  FIG. 3 .  FIG. 3  is a top, schematic view, illustrating an occlusive dressing placed around a wound or a burn of an irregular shape. Shaded area  12  represents a wound or burn. Numeral  13  indicates the adhesive barrier and outer line  14  represents the outer limits of the sealing film which is adhered to adhesive barrier  13 . 
   Any number of specially designed inlet and/or outlet valves may be placed at any point along the adhesive barrier, whereby to allow to introduce any desired substances or electrical or other probes into the space circumscribed at the periphery by the barrier and between the wounded area and the film, (hereinafter, “the occluded space”) and/or to dilute, exchange or replace the contents of said occluded space. Said valves may be separate from the adhesive barrier and be connected with it when the dressing is applied, or may be integral with it or built-in, viz. constitute a component of the barrier. The insertion of a separate valve in the dressing through the barrier or the film may require the assistance of an adapter, unless the barrier is thick or flexible enough for a valve conduit to pass through it without interfering with the barrier&#39;s function. The valves may allow a continuous flow of any fluid, including thin or thick and more or less viscous liquids and/or gases over the desired occluded area. The valves may be one- or two-way valves and may be closed, if so desired, to maintain the occluded contents unchanged. 
   Low (vacuum) or high pressure pumps may be connected to the valves controlling the inside pressure or partial gases pressure. Electrical sources, to provide electrical current between the occluded materials and the patient&#39;s body, may be added to form an ionophoresis chamber or magnetic fields. The nature, structure and positioning of these valves and adapters should not interfere with the occluding properties of the adhesive barrier and/or of the sealing film, and of the whole occluding dressing. 
     FIGS. 4 and 5  illustrate a valve  15 , separate of the adhesive barrier, having a conduit  16 , and an adapter  17  therefor, respectively. Adapter  17  has a substantially flat or moderately curved side  18 , which is to be placed along the periphery of the occluded area, and a preferably curved side  19 , which is to contact the adhesive barrier. Further, it has an opening  20  through which conduit  16  passes. 
   An additional embodiment of a conduit is illustrated in  FIG. 11   a  in a schematic perspective view. Said conduit consists of two plastic strips welded to each other along both of each of their ends, to form a flat conduit and a leaf valve. Said conduit is coated on its outside surfaces by a layer of adhesive. Thus, said conduit may be placed onto the skin and pressed lightly thereto, prior to the placement of the occlusive dressing as described above. 
   An additional embodiment of a valve according to the invention is a leaf valve which is well known in the art. An example of such a leaf valve is illustrated in  FIG. 11   a  in a schematic partial cross-section. Said valve consists of a conduit  120 , inside which are two flaps  121  and  122 . Said flaps are connected at their ends to the inside surface of said conduit, on two opposite sides, one on each side, and their free end are both positioned in the same direction, roughly parallel to the length axis of said conduit. Thus, upon applying pressure on flowing matter in the direction of the arrow, a passage may open between said flaps and matter can flow through the conduit in said direction. Upon applying pressure on flowing matter in the opposite direction to said arrow, said matter forces said flaps one towards the other to form a closure of passage which prevents the flow of said matter through said conduit beyond the position of said flaps. 
     FIG. 5   b  illustrates an adapter for a conduit or a valved port to be placed on top of the occluding film instead of passing through the barrier. Said adapter connects and directs, seals and stabilizes the passage of the conduit tangentially through the film. 
     FIG. 6   a  illustrates the resulting assembly in cross-section perpendicular to the occluded area. In this embodiment, the adhesive barrier is not made of an adhesive material, but is coated with a layer of adhesive  21  over a non-adhesive body  22 . Such a coating may be omitted on side  19 , if the adhesive properties of the adhesive barrier are sufficient to seal it against the adapter. The sealing film is shown at  23 , and the surface of the skin at  24 . The remaining numerals are the same as in  FIGS. 4 and 5 . 
     FIG. 6   b  illustrates similarly to  FIG. 6   a  the resulting assembly in cross-section perpendicular to the occluded area. The flat conduit is shown at  125 , and a layer of adhesive  119  between the barrier and the conduit may be coated on the barrier, on the conduit, on both the barrier and the conduit, or said layer may be omitted if the adhesive properties of the adhesive barrier are sufficient to seal it against the conduit. The remaining numerals are the same as in  FIG. 6   a.    
     FIG. 7  is a top view illustrating an occlusive dressing system placed around a wound or burn of an irregular shape, wherein shaded area  25  represents a wound or burn,  26  indicates an adhesive barrier, line  27  represents the outer edge of the sealing film and numeral  28  indicates valves connected to the adhesive barrier or the film  20 , optionally by means of adapters, not shown in the drawing. 
     FIGS. 8   a ,  8   b  and  8   c  illustrate a segment of an endless, elongated, flexible adhesive barrier  30  which comprises valves that are integral therewith, viz. are components thereof. Numeral  31  indicates the wounded area, and  32  a valve having a conduit  33  with an outlet  34 . These outlets may be in the form of semi-circular flaps incised into the tube forming valve-like flaps.  FIG. 8   a  is a fragmentary top view of said barrier  30 , which is hollow and tube-like, as seen in  FIGS. 8   b  and  8   c .  FIG. 8   b  is a fragmentary perspective view from above and outside the occluded area looking inwards and  FIG. 8   c  is a fragmentary perspective view from above and inside the occluded area looking outwards.  FIG. 8   d  illustrates an adapter for a conduit or a valved port to be placed on top of the occluding film instead of passing through the barrier. 
     FIGS. 9   a  and  9   b  illustrate the use of a dressing system according to the invention for introducing and eliminating fluids or gases through valves into and from the occluded space. Numeral  40  indicates a source of non-gaseous fluid; numeral  41  indicates a gas source; numerals  42  and  43  indicate dressings; numerals  44  and  45  indicate ducts leading from said non-gaseous fluid source and gas source, respectively, to said dressings; numeral  46  indicates a disposal container; numeral  47  indicates a duct leading from dressing  42  to disposal container  46 ; numerals  48  and  49  indicate inlet valves into the occluded spaces of dressings  42  and  43 ; and numerals  50  and  51  indicate free openings or outlet valves from the occluded spaces of dressings  42  and  43 . The gas source  41  may be replaced by a vacuum pump that creates a lower atmospheric pressure inside the dressing. The vacuum may be adjusted to high or low, continuous or alternating. 
     FIG. 9   c  illustrates the use of a dressing system according to the invention for providing an electrical field at the occluded area. Numeral  45  indicates an electrode passing through an inlet tube and numeral  46  indicates another electrode placed on the patient&#39;s body to close the circuit with the electrical or magnetic source. When using a conductive film, electrode  45  may be connected directly to the film, and the barrier should have electrical isolation properties thus, the electrical field being established between the film and the body (electrode  46 ). 
     FIG. 10  is a top view illustrating an occlusive dressing placed around a wound of an irregular shape, wherein numeral  52  represents the boundary of a wound,  53  is the adhesive barrier and the outer line  54  represents the outer edge of the sealing film which is adhered to the adhesive barrier. The hexagonal areas  55  represent stabilizing and carrier matrices, hereinafter described. 
   The dressing system according to the invention, being a general, multipurpose device, may include several additional features specifically designed to develop or enhance certain of its properties. Such features may include stabilizing and carrier matrices. Thus, medicines or materials with such a consistency that they do not stick and remain on the site of application, but allows them to slide downwards following the body curvatures, may be contained in a stabilizing or carrier matrix. These matrices, containing any number of desired bio-active components, could be placed on the treatment site, covered with the occlusive dressing and activated by infusing the appropriate activating liquids (such as solvents and irrigation liquids) through the inlet valves. 
   Said matrices may be in the form of fibrous nets, fibrous knotted nets, gauze, non-wovens, sponges or honeycomb or any other acceptable form and may be made of natural or synthetic, stable or degradable material, such as those described in “ Remington&#39;s Pharmaceutical Sciences” , Mack Publishing Company, 1990, pages 1895–1900 or other similar source manuscripts. 
   An electrophoretic releasing system may also be provided in a dressing according to the invention. In this system that is well known in the art, one electrical pole is connected to the occluded material and the other electrical pole is connected to the patient&#39;s body. Electrical current passing between the poles cause the transfer of ions or materials according to their electrical charges. The above phenomenon is known as ionophoresis. 
   The nature and structure of the aforementioned matrix material may be such as to absorb and direct the flow of the medicines and the solvents or irrigation fluids to the desired treatment target. It is possible to use this system as a time or quantity controlled release system, by changing the nature and density of the medicating substances and their solvents according to the change of the nature and structure of the matrices in order to use well known forces such as surface tension hydrophilic or hydrophobic forces or electrical field. 
   Electrical fields may be used also to control the movement of electrically charged molecules or particles to the desired treatment site. For this purpose one electrical pole is connected to the sealing film or carrier matrix and the other to the patient body. This electrophoretic releasing and transportation system, known also as “ionophoresis system”, helps to direct the desired medicaments to their targets and the occluding dressing of the invention is well designed to serve as such an electrophoretic chamber. 
   The following non-limitative examples illustrate some embodiments of the invention. 
   As will be appreciated by the skilled person, the invention can be exploited by using a very great variety of materials. For instance, the impermeable sealing film may be a saran, polyurethane, nylon or polyethylene film. The carrier matrix may be, e.g., a fibrous net, such as the Kerlix knotted net (manufactured by Knoll and others), or a 4×4-8 ply gauze (manufactured by Johnson &amp; Johnson), or a Softwick non-woven surgical sponge (also by Johnson &amp; Johnson and others), or a Nu-Gauze surgical sponge. Furthermore, the matrix may have different shapes, e.g., it may be honeycomb or hexagonal. Several different adhesives can be used, such as para or pale crepe rubber, poly isobutylene or polymethacrylate. Thus, as will be apparent to the skilled person, although illustrative and non-limitative examples of suitable materials have been given above, for the purpose of illustration, the invention is by no means limited to such or other materials and many occlusive dressing systems can be provided in many ways, without exceeding the scope of the invention.