Patent Publication Number: US-11382797-B2

Title: Breathable interface system for topical reduced pressure

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 15/369,242, filed Dec. 5, 2016, which is a continuation of U.S. patent application Ser. No. 14/925,784, filed Oct. 28, 2015, now U.S. Pat. No. 9,526,660, which is a continuation of U.S. patent application Ser. No. 14/191,150, filed Feb. 26, 2014, now U.S. Pat. No. 9,198,802, which is a continuation of U.S. patent application Ser. No. 13/430,088, filed Mar. 26, 2012, now U.S. Pat. No. 8,680,359, which is a continuation of U.S. application Ser. No. 13/015,209, filed Jan. 27, 2011, now U.S. Pat. No. 8,148,595, which is a continuation of U.S. patent application Ser. No. 12/069,245, filed Feb. 8, 2008, now U.S. Pat. No. 7,880,050, which claims the benefit of U.S. Provisional Application No. 60/900,463, filed Feb. 9, 2007, the disclosures which are hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present application relates generally to systems and methods for providing reduced pressure tissue treatment to open wounds and other tissue sites. More particularly, the present application relates to a breathable interface systems for topical reduced pressure. 
     2. Description of Related Art 
     Clinical studies and practice have shown that providing a reduced pressure in proximity to a tissue site augments and accelerates the growth of new tissue at the tissue site. The applications of this phenomenon are numerous, but application of reduced pressure has been particularly successful in treating wounds and tissue sites. This treatment (frequently referred to in the medical community as “negative pressure wound therapy,” “reduced pressure therapy,” or “vacuum therapy”) provides a number of benefits, including faster healing, and increased formulation of granulation tissue. 
     Reduced pressure tissue treatment has recently been popularized by Kinetic Concepts, Inc. of San Antonio, Tex., through its commercially available VAC reduced pressure tissue treatment systems product line. In general, such reduced pressure tissue treatment systems comprise a pad-based dressing, which is applied to the tissue and is sometimes referred to as the “tissue interface” or the “wound interface.” 
     Current dressings, however, have several disadvantages. They are difficult to apply to small wounds, and often lead to maceration of the wound periphery. Traditionally, dressings have been rather cumbersome, limiting many patient activities. Simply sitting on or rolling onto a dressing may cause significant patient discomfort. Moreover, these actions may compress the dressing and interfere with the application of reduced pressure to a manifold at the tissue site. 
     BACKGROUND OF THE INVENTION 
     Summary 
     The problems presented with these conventional dressings are solved by an improved breathable interface system for topical reduced pressure. In one illustrative embodiment, a reduced pressure tissue treatment system is provided and includes an applicator having an aperture, a first pad section, and a second pad section. The second pad section substantially covers the aperture and is positioned substantially adjacent the first pad section. A fabric layer is located at least partially between the second pad section and the drape, and the fabric layer includes a woven or non-woven fabric made from a fiber material. A drape substantially covers the first pad section, the second pad section, the fabric layer, and the applicator. A reduced pressure source is in fluid communication with at least one of the first pad section and the fabric layer for providing reduced pressure to the aperture. 
     In another illustrative embodiment, a reduced pressure tissue treatment system includes an applicator having an aperture, a first pad section, and a second pad section substantially covering the aperture and positioned substantially adjacent to the first pad section. A fabric layer is located at least partially between the first pad section and the applicator, and the fabric layer further is located at least partially between the second pad section and the applicator. A drape substantially covers the first pad section, the second pad section, the fabric layer, and the applicator. A reduced pressure source is in fluid communication with at least one of the first pad section and the fabric layer for providing reduced pressure to the aperture. 
     In yet another illustrative embodiment, a reduced pressure tissue treatment system includes an applicator having an aperture, a first pad section, and a second pad section substantially covering the aperture and positioned substantially adjacent to the first pad section. A fabric layer is located at least partially between the first pad section and the drape, and the fabric layer further is located at least partially between the second pad section and the drape. A drape substantially covers the first pad section, the second pad section, the fabric layer, and the applicator. A reduced pressure source is in fluid communication with at least one of the first pad section and the fabric layer for providing reduced pressure to the aperture. 
     Other objects, features, and advantages of the illustrative embodiments will become apparent with reference to the drawings and the detailed description that follow. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded view of the breathable interface system according to an illustrative embodiment of the invention; 
         FIG. 2  is a perspective view of the breathable interface system without a drape according to an illustrative embodiment of the invention; 
         FIG. 3  is a bottom view of an applicator of a breathable interface system of  FIGS. 1 and 2  according to an illustrative embodiment of the invention; 
         FIG. 4  is cross-sectional view of the breathable interface system along lines  4 - 4  of  FIG. 2  according to an illustrative embodiment of the invention; 
         FIG. 5  is cross-sectional view of the breathable interface system according to another illustrative embodiment of the invention; 
         FIG. 6  is cross-sectional view of the breathable interface system according to another illustrative embodiment of the invention; 
         FIG. 7  is a schematic diagram of a reduced pressure tissue treatment system having a breathable interface system according to an illustrative embodiment of the invention; 
         FIG. 8  is a chart that compares the results of pressure transmission experiments on a conventional dressing and a breathable interface system according to an illustrative embodiment of the present invention; and 
         FIG. 9  is a chart that compares response times when subjected to intermittent application of reduced pressure under dry conditions of a conventional dressing and a breathable interface system according to an illustrative embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT 
     In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration specific preferred embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is understood that other embodiments may be utilized and that logical, structural, mechanical, electrical, and chemical changes may be made without departing from the spirit or scope of the invention. To avoid detail not necessary to enable those skilled in the art to practice the invention, the description may omit certain information known to those skilled in the art. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims. 
     The term “reduced pressure” as used herein generally refers to a pressure less than the ambient pressure at a tissue site that is being subjected to treatment. In most cases, this reduced pressure will be less than the atmospheric pressure at which the patient is located. Alternatively, the reduced pressure may be less than a hydrostatic pressure of tissue at the tissue site. Although the terms “vacuum” and “negative pressure” may be used to describe the pressure applied to the tissue site, the actual pressure applied to the tissue site may be significantly less than the pressure normally associated with a complete vacuum. Reduced pressure may initially generate fluid flow in the tube in the area of the tissue site. As the hydrostatic pressure around the tissue site approaches the desired reduced pressure, the flow may subside, and the reduced pressure is then maintained. Unless otherwise indicated, values of pressure stated herein are gauge pressures. 
     The term “tissue site” as used herein refers to a wound or defect located on or within any tissue, including but not limited to, bone tissue, adipose tissue, muscle tissue, neural tissue, dermal tissue, vascular tissue, connective tissue, cartilage, tendons, or ligaments. The term “tissue site” may further refer to areas of any tissue that are not necessarily wounded or defective, but are instead areas in which it is desired to add or promote the growth of additional tissue. For example, reduced pressure tissue treatment may be used in certain tissue areas to grow additional tissue that may be harvested and transplanted to another tissue location. 
     Referring to  FIGS. 1-3 , an illustrative embodiment of a breathable interface system  100  is shown. In this embodiment, the breathable interface system  100  includes a first pad section  102 , a second pad section  104 , and a fabric layer  106 , all positioned between a drape  108  and an applicator  110 . The breathable interface system  100  generally has one end  116  that is located substantially adjacent to or over a tissue site and another end  114  that is located distally away from end  116 , in one example. Nearer to end  114 , the fabric layer  106  may be positioned or located at least partially between the applicator  110  and the first pad section  102 . Nearer to end  116 , the fabric layer  106  may be positioned or located at least partially between the second pad section  104  and the drape  108 . The fabric layer  106  extends along a portion of a top surface  124  of the second pad section  104  between the second pad section  104  and the drape  108 . Once the fabric layer  106  reaches a side  120  of the second pad section  104  it transitions near the area  118  between the side  120  of the second pad section  104  and the side  122  of the first pad section  102  to extend along a portion of the bottom surface  126  of the first pad section  102  between the first pad section  102  and the applicator  110 . 
       FIG. 2  is an illustrative embodiment of a breathable interface system  200  without the drape  108  placed on top of the first pad section  102 , second pad section  104 , and fabric layer  106  for illustration purposes. The fabric layer  106  can be seen extending over the top surface  124  of the second pad section  104  and beneath the bottom surface  126  of the first pad section  102 .  FIG. 3  is an illustrative embodiment of the applicator  110  including an aperture  302  that extends through the applicator  110  substantially near the end  116  of the applicator  110 . The aperture  302  preferably is located near a tissue site to enable fluid to flow from the tissue site to the first pad section  102 , second pad section  104 , fabric layer  106 , and reduced pressure conduit  112  of the breathable interface systems herein described. 
     In an illustrative embodiment, any hydrogel or bonding agent may be applied to the aperture  302  and the applicator  110  for sealing or contact purposes with a tissue site. The second pad section  104  is generally positioned to substantially cover the aperture  302 , between the drape  108  and the applicator  110  as shown in  FIGS. 4 and 6 . In  FIG. 5 , the aperture  302  may be substantially covered by the fabric layer  106  as described herein. The size of the aperture  302  may vary to accommodate larger wounds, but in one embodiment, a size of about 10 to about 20 mm is advantageous for small wounds. 
     Referring to  FIG. 4 , an illustrative embodiment of the breathable interface system  100  is shown. The aperture  302  is shown disposed through the applicator  110 . In addition, the breathable interface system  100  may further include an interface  402  that facilitates fluid communication between the first pad section  102  and/or fabric layer  106  and the reduced pressure conduit  112 . Referring to  FIG. 5 , another illustrative embodiment of the breathable interface system  500  is shown. The breathable interface system  500  may include a different arrangement of the first pad section  102 , second pad section  104 , and fabric layer  106  between the drape  108  and the applicator  110 . In this illustrative embodiment, the fabric layer  106  is located between the bottom surface  126  of the first pad section  102  and the bottom surface  128  of the second pad section  104  and the top surface  132  of the applicator  110 . The first pad section  102  and second pad section  104  are located or positioned on top of the fabric layer  106 . In this illustrative embodiment, the fabric layer  106  substantially covers the aperture  302 . Referring to  FIG. 6 , yet another illustrative embodiment of the breathable interface system  600  is shown. In this illustrative embodiment, the fabric layer  106  is located between the top surface  124  of the second pad section  104  and the top surface  130  of the first pad section  102  and the bottom surface  136  of the drape  108 . 
     In any of the breathable interface systems  100 ,  200 ,  500 , and  600 , the reduced pressure conduit  112  may be located in direct contact with the first pad section  102  and/or the fabric layer  106 . The reduced pressure conduit  112  may be placed in direct contact with the first pad section  102  or the fabric layer  106  by directly inserting it into either of the first pad section  102  or the fabric layer  106  near the end  114  of the breathable interface system  100 . In another illustrative embodiment, the breathable interface systems  100 ,  200 ,  500 , and  600  may further include the interface  402  as shown in  FIG. 4  for facilitating the fluid communication and flow between the first pad section  102  and/or fabric layer  106  and the reduced pressure conduit  112 . In yet another illustrative embodiment, the reduced pressure conduit  112  may not be in direct contact with the first pad section  102  and/or fabric layer  106 , but may otherwise be in fluid communication with the first pad section  102  and/or fabric layer  106 . 
     In one illustrative embodiment, the side  120  of the second pad section  104  extends between the top surface  124  and a bottom surface  128  of the second pad section  104 . The bottom surface  128  of the second pad section  104  may have a surface area that may cover substantially all or a portion of the top surface  132  of the end  116  of the applicator  110 . Additionally, the side  122  of the first pad section  102  extends between the top surface  130  and the bottom surface  126  of the first pad section  102 . The bottom surface  126  of the first pad section  102  may have a surface area that may cover substantially all or a portion of the end  114  of the top surface  132  of the applicator  110 . 
     The applicator  110  may be any size desirable to adequately provide effective covering and functionality to a tissue site as described herein. In one aspect, the applicator  110  includes a bottom surface  134  that may preferably contact the tissue site. The end  116  of the applicator  110  may have a surface area of a different shape than the end  114  of the applicator  110 . For example, the surface area of the end  116  as shown in  FIG. 1  shows a surface area of a substantially circular shape. Nevertheless, the shape of the end  116  of the applicator  110  may any desirable shape, symmetric, asymmetric, or otherwise, to provide the covering of a tissue site and functionality as herein described. In one illustrative embodiment, the end  114  of the applicator  110  may have a surface area that approximates a rectangular shape; however, the end  114  of the applicator  110  may also be any desirable shape, symmetric, asymmetric, or otherwise, to provide the covering and functionality as herein described. 
     Preferably, the bottom surface  136  of the drape  108  covers and secures the first pad section  102 , fabric layer  106 , and second pad section  104  to the top surface  132  of the applicator  110 . In one aspect, the applicator  110  and drape  108  are sealed together substantially around the perimeter or periphery of their respective shapes. Preferably, the applicator  110  and drape  108  isolate the tissue site from its surrounding environment and maintain a reduced pressure at the tissue site when reduced pressure is applied as described herein. The applicator  110  may be secured to drape  108  with any suitable bonding agent, such as an acrylic adhesive or hydrogel. In addition, the applicator  110  may be joined to the drape  108  by other commonly known means, such as bonding, adhesives, welding, fastening, and sintering, for example. Typically, a hydrogel or other tissue-friendly bonding agent may be applied to the tissue side or bottom surface  134  of the applicator  110 , which is then placed into the tissue site or in contact with the perimeter of the tissue site to secure the dressing to the tissue site. 
     In an illustrative embodiment, the first pad section  102  and second pad section  104  may be a material known in the art to be suitable for reduced pressure tissue treatment, the size and shape of which may be varied to accommodate tissue sites of various size and shape as described herein. Preferably, the first pad section  102  and second pad section  104  include a plurality of flow channels or pathways to facilitate the distribution of reduced pressure or fluids to or from the tissue site. In one illustrative embodiment, the first pad section  102  and second pad section  104  are porous foam that includes interconnected cells or pores that act as flow channels. In addition to the above, the first pad section  102  and second pad section  104  may be a material such as an open cell, reticulated foam that is formed from a range of polymers, including without limitation polyurethane, polyolefin, vinyl acetate, polyvinyl alcohol, and their copolymers. Additionally, the first and second pad section  102 ,  104  may be woven or non-woven materials, including 3-dimensional fabric structures. The pads may also be made from a sintered polymer, including materials such as sintered polyolefin, ethylene vinyl acetate, and fluoropolymer. The first pad section  102  and second pad section  104  may also be any other type of open-cell, reticulated foam, such as GranuFoam® and Whitefoam™ that are manufactured by Kinetic Concepts, Inc. of San Antonio, Tex. If open-cell foam is used, the porosity may vary, but is preferably about 400 to 600 microns. Alternatively, gauze or any other material suited to a particular biological application may be used to construct first pad section  102  and second pad section  104 . In a certain illustrative embodiment, first pad section  102  and second pad section  104  may be constructed as a single, unitary pad. In another illustrative embodiment, first pad section  102  and second pad section  104  may be a multi-component or multi-layered pad section. Preferably, the thicknesses of the first pad section  102  and second pad section  104  is from about 1 mm to about 50 mm, and in one implementation from about 5 mm to about 20 mm, although any thicknesses may be used. 
     In an illustrative embodiment, the fabric layer  106  may be a woven or non-woven fabric material known in the art, the size and shape of which may be varied to accommodate tissue sites of various size and shape as described herein. It may be constructed from any fiber material that maintains its structural integrity when exposed to fluids, such as polyamide, polyolefin, nylon, polyester, a polyamide coated with polyurethane, any polymeric mesh, a non-woven (air layed) melt blown polymer, or flexible sintered polymer. The fabric layer  106  may also be a fabric covered with adhesive or hydrogel to facilitate bonding to the tissue site, where the fabric layer  106  extends beyond the applicator  110 . The material may be woven together to form a layer of appropriate dimensions, or it may be any type of open cell mesh construction of appropriate dimensions. As illustrated in  FIG. 1 , the fabric layer  106  may also be folded and include stitching  140  to provide additional channels and structural support. A folded fabric layer may be stitched lengthwise down the middle, as depicted in  FIG. 2 , around the edges, or any combination thereof. As an alternative to stitching, a folded fabric layer may be secured with an acrylic adhesive or any other suitable bonding agent. The fabric layer  106  may also include several overlapping layers joined together by any known means. Preferably, the thicknesses of the fabric layer  106  is from about 1 mm to about 50 mm, and more preferably about 5 mm to about 20 mm, although any thicknesses may be used. 
     The drape  108  may be a flexible material having a sufficiently high moisture vapor transmission rate (“MTVR”) to preclude tissue maceration, typically greater than 600 mg/m 2 /day. In one aspect, plastics and thermoplastics are an example of suitable materials for the drape  108 . And like the drape  108 , the applicator  110  generally is constructed from any flexible material having a sufficiently high MTVR to preclude maceration of the tissue site, such as plastics and thermoplastics. 
     The reduced pressure conduit  112  may represent any conduit tubing, line, or path through which a gas, liquid, gel, or other fluid may be carried, and may have more than one internal lumen. While the reduced pressure conduit  112  may be inflexible, it is preferred that it be flexible enough for ease of use and comfort for a patient. The reduced pressure conduit is configured for connection to a reduced pressure source to provide delivery of reduced pressure. 
     In an illustrative embodiment, the breathable interface systems  100 ,  200 ,  500 , and  600  may be lightweight, low-profile interface systems for low-severity, small tissue sites, but the principles are readily extendable by a person of ordinary skill in the art to larger, more extensive tissue sites, as well as numerous other types of tissue treatments. 
     Referring again to  FIGS. 1-6 , the aperture  302  is placed over a tissue site and the reduced pressure source  704  delivers a reduced pressure through the reduced pressure conduit  112  to the breathable interface systems  100 ,  200 ,  500 , and  600 . The aperture  302  may be a single aperture as shown, or any number or plurality of holes, openings, apertures, slits, or the like desirable for providing distribution of reduced pressure and fluid transmission between the tissue site and the first pad section  102 , second pad section  104 , and fabric layer  106 . As described above, the first pad section  102  and second pad section  104  may include pathways or channels that permit the reduced pressure to be distributed throughout the breathable interface systems  100 ,  200 ,  500 , and  600 , and that permit fluids to be removed from a tissue site through the aperture  302 . The weave or mesh structure of the fabric layer  106  provides additional fluid pathways that are less susceptible to collapsing under compressive loads that may be applied to the breathable interface systems  100 ,  200 ,  500 , and  600 , such as those encountered when a patient rolls in bed or otherwise moves causing compression of the dressing. The additional fluid pathways also reduce the time required to distribute reduced pressure to a tissue site. As detailed below, testing has shown that pressure changes by a reduced pressure source are communicated to the tissue site much more quickly with a dressing configured like that of the breathable interface systems  100 ,  200 ,  500 , and  600 . 
     Referring to  FIG. 7 , an illustrative embodiment of a reduced pressure tissue treatment system  700  incorporating the novel features of the breathable interface system is shown. The reduced pressure tissue treatment system  700  includes a breathable interface system  701  similar to the other breathable interface system described herein, which is applied to a tissue site  702  for treatment. Breathable interface system  100  is fluidly connected to a reduced pressure source  704  by a reduced pressure conduit  112 . In certain embodiments, the reduced pressure tissue treatment system  700  may also include a canister  706  for collecting fluid and other non-gaseous exudates extracted from the tissue site  702 . 
     Referring to  FIG. 8 , a chart that compares the results of pressure transmission tests on a conventional dressing and a breathable interface system  100  as substantially described above is shown. In the tests, reduced pressure was applied to and water was pumped through each breathable interface system  100  while the breathable interface system  100  was subjected to a range of compressive forces. Pressure measurements were taken on both sides of the compressive forces to determine the performance of each specimen. The results, as shown in  FIG. 8 , demonstrate that a breathable interface system  100  as described above enables pressure communication across the compressive load to a much greater extent that a conventional dressing. 
     The flow of water was set to approximately 20 mls/hr and a compressive force from approximately 0 N to about 500-930 N was applied to the conventional dressing and the breathable interface system  100 . The y-axis  802  represents the amount of reduced pressure or vacuum measured at either the pump or the dressing/breathable interface system  100 . The x-axis  804  represents the duration of time expired from the start of the tests. Line  806  represents the magnitude of the reduced pressure at the pump for the conventional dressing and the line  808  represents the magnitude of the reduced pressure at the opposite side of the dressing. As can be seen from  FIG. 8 , a compressive force of approximately 900 N was applied to the conventional dressing and the amount of measurable reduced pressure was approximately 0 mm Hg. at the dressing, as shown by line  808 . At the start of event  814 , the compressive force was released, thus the amount of measurable reduced pressure at the dressing increased to approximately 120 mm Hg. At the end of event  814 , a compressive force was applied at a magnitude of 525 N and the amount of measurable reduced pressure dropped back to approximately 0 mm Hg. During this same event, the measurable reduced pressure at the pump side of the dressing, as shown by line  806 , stayed at approximately 125 mm Hg. This shows that with a conventional dressing under compressive force, the amount of reduced pressure through the dressing is approximately 0 mm Hg. Similarly, at events  816 ,  818 , and  820 , compressive forces were released and reapplied at approximately 250 N. It can be seen from  FIG. 8 , that essentially the same results followed. Namely, as soon as a compressive force was applied, the measurable amount of reduced pressure through the conventional dressing dropped to 0 mm Hg, or near 0 mm Hg. 
     Conversely, line  810  represents the magnitude of the reduced pressure at the pump for the breathable interface system  100  and the line  812  represents the magnitude of the reduced pressure at the opposite side of the dressing. As described above, a compressive force of approximately 900 N was applied to the conventional dressing and the amount of measurable reduced pressure was approximately 50 mm Hg at the dressing, as shown by line  812 . At the start of event  814 , the compressive force was released, thus the amount of measurable reduced pressure at the dressing increased to approximately 120 mm Hg. At the end of event  814 , a compressive force was applied at a magnitude of 525 N and the amount of measurable reduced pressure was reduced to approximately 50 mm Hg. During this same event, the measurable reduced pressure at the pump side of the dressing, as shown by line  810 , stayed at approximately 125 mm Hg. This shows that with a breathable interface system  100  under compressive force, the amount of reduced pressure is still substantial. Similarly, at events  816 ,  818 , and  820 , compressive forces were released and reapplied at approximately 250 N. It can be seen from  FIG. 8 , that even better results followed. Namely, as soon as a compressive force of approximately 250 N was applied, the measurable amount of reduced pressure through the conventional dressing increased to between approximately 70 mm Hg and 100 mm Hg. 
     Referring to  FIG. 9 , another chart is shown that compares response times of a conventional dressing and a breathable interface system  100  as substantially described above in  FIG. 8  when subjected to intermittent application of reduced pressure under dry conditions. The response times illustrated in  FIG. 9  demonstrate that a conventional dressing responds much more slowly than the breathable interface system  100  described above when subjected to these conditions. 
     Pressure measurements were taken on both sides of the compressive forces to determine the response times of a conventional dressing compared with the breathable interface system  100  described above. The results, as shown in  FIG. 9 , demonstrate that a breathable interface system  100  as described above enables faster response times to the intermittent application and release of reduced pressure. The y-axis  902  represents the amount of reduced pressure or vacuum measured at either the pump or the dressing/breathable interface system  100 . The x-axis  904  represents the duration of time expired from the start of the tests. Line  906  represents the magnitude of the reduced pressure measured at the pump for the conventional dressing and the line  908  represents the magnitude of the reduced pressure at the opposite side of the dressing. Line  910  represents the magnitude of the reduced pressure measured at the pump for the breathable interface system  100  and the line  912  represents the magnitude of the reduced pressure measured at the opposite side of the breathable interface system  100 . 
     As can be seen from  FIG. 9 , a reduced pressure is cycled on and off between approximately 0 mm Hg and 125 mm Hg. The lines  906  and  910  fairly closely match each other showing that there is little difference of measurable reduced pressure during the tests at the pump side of the dressing/breathable interface system  100  during the cycling of the reduced pressure. At the other side of the dressing, line  908  shows a lag time in achieving the applied reduced pressure at the conventional dressing. This can be seen as line  908  has an arc to its shape representing the gradual building of reduced pressure before it attains full reduced pressure. Conversely, line  912  shows sharp transitions when the reduced pressure is cycled on and off, thus representing that the breathable interface system  100  provides for improved fluid transmission and response to reduced pressure than conventional dressings. 
     It should be apparent from the foregoing that an invention having significant advantages has been provided. While the invention is shown in only a few of its forms, it is not just limited but is susceptible to various changes and modifications without departing from the spirit thereof.