Patent Publication Number: US-2022218892-A1

Title: Low-profile fluid conductors with moisture management features

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of priority to U.S. Provisional Application No. 62/878,804, filed on Jul. 26, 2019, which is incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The invention set forth in the appended claims relates generally to tissue treatment systems and more particularly, but without limitation, to low-profile distribution components for providing negative-pressure therapy. 
     BACKGROUND 
     Clinical studies and practice have shown that reducing pressure in proximity to a tissue site can augment and accelerate growth of new tissue at the tissue site. The applications of this phenomenon are numerous, but it has proven particularly advantageous for treating wounds. Regardless of the etiology of a wound, whether trauma, surgery, or another cause, proper care of the wound is important to the outcome. Treatment of wounds or other tissue with reduced pressure may be commonly referred to as “negative-pressure therapy,” but is also known by other names, including “negative-pressure wound therapy,” “reduced-pressure therapy,” “vacuum therapy,” “vacuum-assisted closure,” and “topical negative-pressure,” for example. Negative-pressure therapy may provide a number of benefits, including migration of epithelial and subcutaneous tissues, improved blood flow, and micro-deformation of tissue at a wound site. Together, these benefits can increase development of granulation tissue and reduce healing times. 
     There is also widespread acceptance that cleansing a tissue site can be highly beneficial for new tissue growth. For example, a wound or a cavity can be washed out with a liquid solution for therapeutic purposes. These practices are commonly referred to as “irrigation” and “lavage”. “Instillation” is another practice that generally refers to a process of slowly introducing fluid to a tissue site and leaving the fluid for a prescribed period of time before removing the fluid. For example, instillation of topical treatment solutions over a wound bed can be combined with negative-pressure therapy to further promote wound healing by loosening soluble contaminants in a wound bed and removing infectious material. As a result, soluble bacterial burden can be decreased, contaminants removed, and the wound cleansed. 
     While the clinical benefits of negative-pressure therapy and/or instillation therapy are widely known, improvements to therapy systems, components, and processes may benefit healthcare providers and patients. 
     BRIEF SUMMARY 
     New and useful systems, apparatuses, and methods for treating tissue in a negative-pressure therapy environment are set forth in the appended claims. Illustrative embodiments are also provided to enable a person skilled in the art to make and use the claimed subject matter. 
     For example, in some embodiments, a low-profile elongate fluid conductor may include a first end and a second end. The first end may be configured to be coupled to a negative-pressure source and the second end may be coupled with a dressing. The fluid conductor may include a first fluid pathway and a second fluid pathway, wherein each of the first fluid pathway and the second fluid pathway extend from the first end to the second end of the fluid conductor. The fluid conductor may further include an aperture proximate the first end of the fluid conductor. The aperture may be disposed on a side of the fluid conductor configured to face a patient of the fluid conductor. The aperture may provide a controlled flow into the second fluid pathway. The second fluid pathway may be fluidly coupled to the first fluid pathway proximate the second end of the fluid conductor. If negative pressure is applied to the first fluid pathway, the second fluid pathway and the aperture are configured to draw fluid from the ambient environment through the aperture, into the second fluid pathway, and toward the second end of the fluid conductor. 
     In some embodiments, at least a portion of the side of the fluid conductor configured to face the patient may comprise a material having a high moisture-vapor transmission rate that can permit evaporated moisture to pass into the second fluid conductor. 
     For example, an apparatus for conducting fluid may comprise a first layer, a second layer, and a third layer. The second layer may have a first aperture. The third layer may have a second aperture and a third aperture. The first layer, the second layer, and the third layer may be sealed to form a first fluid pathway and a second fluid pathway in a stacked relationship, with the second layer between the first fluid pathway and the second fluid pathway. The first aperture may fluidly couple the first fluid pathway and the second fluid pathway. The first aperture may be fluidly coupled to the second aperture. The third aperture may be disposed at a first end of the second fluid pathway. The apparatus may further comprise a first spacer layer configured to support the first fluid pathway, and a port fluidly coupled to the first fluid pathway. 
     In more specific examples, upon the application of a negative pressure, the second fluid pathway and the third aperture are configured to draw fluid through the third aperture, into the second fluid pathway, and toward the second aperture. 
     In another example, an apparatus for coupling a dressing to a negative-pressure source may comprise a first fluid conductor having a first end and a second end, and a second fluid conductor having a first end and a second end, wherein the first fluid conductor and the second fluid conductor are in a stacked relationship. A first aperture may be located at the second end of the first fluid conductor. The first aperture may fluidly couple the first fluid conductor and the second fluid conductor. A second aperture may be located at the second end of the second fluid conductor. The second aperture may be configured to fluidly couple the first fluid conductor and the second fluid conductor to the dressing. A third aperture may be located at the first end of the second fluid conductor. The third aperture may be configured to fluidly couple the second fluid conductor to the ambient environment. The apparatus may further comprise a first spacer layer configured to support the first fluid conductor, and a port configured to fluidly couple the first fluid conductor to the negative-pressure source. 
     In another example, an apparatus for coupling a dressing to a negative-pressure source may comprise a first layer, a second layer, and an intermediate layer sealed to form a first fluid conductor between the first layer and the intermediate layer and a second fluid conductor between the second layer and the intermediate layer. The apparatus may further comprise a first spacer layer configured to support the first fluid conductor. A first aperture may be disposed in the intermediate layer configured to fluidly couple the first fluid conductor to the second fluid conductor. A second aperture may be disposed in the second layer configured to fluidly couple the first fluid conductor to the dressing. A third aperture may be disposed in the second layer configured to fluidly couple the second fluid conductor to the ambient environment. The first fluid conductor may be fluidly coupled to the negative-pressure source. 
     In another example, an apparatus for managing fluid in a system for treating a tissue site may comprise a top layer, an intermediate layer, a base layer, an applicator, and a bridge. The top layer may include a film having a plurality of cells having closed ends extending from a surface of the top layer. The intermediate layer may include a film coupled to the top layer and covering the plurality of cells forming a first seal around the perimeter. The first seal may form a first fluid pathway between the top layer and the intermediate layer. The base layer may include a film coupled to the intermediate layer forming a second seal around the perimeter. The second seal may form a second fluid pathway between the intermediate layer and the base layer. The applicator may be at one end of the first and second fluid pathways. The applicator may have a first aperture formed in a first end of the intermediate layer, and a second aperture formed in a first end of the base layer. The first aperture may expose a portion of the plurality cells to define a recessed space in the first fluid pathway. The recessed space may be configured to be fluidly coupled to the tissue site. The first aperture may also fluidly couple the first fluid pathway to the second fluid pathway. The second aperture may be fluidly coupled with the first aperture. The bridge may extend from the applicator to the other end of the first and second fluid pathways. The bridge may have a port formed in the top layer and a third aperture formed in the base layer. The port may be configured to fluidly couple the first fluid pathway to a negative-pressure source. The third aperture may be configured to fluidly couple the second fluid pathway to an ambient environment. Upon the application of negative pressure, the second fluid pathway and the third aperture may be configured to draw fluid from the ambient environment through the third aperture, into the second fluid pathway, and toward the tissue site. 
     In yet another example, an apparatus for managing fluid in a system for treating a tissue site may comprise a top layer, an intermediate layer, a base layer, a first aperture, a second aperture, a third aperture, and a port. The top layer may include a film having a plurality of cells having closed ends extending from a bottom surface of the top layer. The intermediate layer may include a film coupled to the top layer and covering the plurality of cells forming a first fluid conductor between the top layer and the intermediate layer. The base layer may include a film coupled to the intermediate layer forming a second fluid conductor between the intermediate layer and the base layer. The first aperture may be formed in a first end of the intermediate layer, wherein the first aperture may expose a portion of the plurality cells to define a recessed space in the first fluid conductor. The recessed space may be configured to be fluidly coupled to the tissue site. The first fluid conductor may be fluidly coupled to the second fluid conductor through the first aperture. The second aperture may be formed in a first end of the base layer, wherein the second aperture may be fluidly coupled with the first aperture. The third aperture may be formed in a second end of the base layer, wherein the third aperture may be configured to fluidly couple the second fluid conductor to an ambient environment. The port may be formed in a second end of the top layer, wherein the port may be configured to fluidly couple the first fluid conductor to a negative-pressure source. If negative pressure is applied to the first fluid conductor, the second fluid conductor and the third aperture may be configured to draw fluid from the ambient environment through the third aperture, into the second fluid conductor, and toward the tissue site. 
     In yet another example, an apparatus for providing negative-pressure treatment may comprise a first layer, a second layer, a first spacer layer, and a second spacer layer. The first layer may comprise a first film. The second layer may comprise a second film having a first aperture and a second aperture. The first spacer layer may comprise a film having a plurality of standoffs, wherein the standoffs extend toward the second layer. The second spacer layer may comprise a film having a third aperture concentric with the second aperture and a plurality of standoffs, wherein at least some of the standoffs extend toward the first spacer layer. The first layer, the first spacer layer, the second spacer layer, and the second layer may be assembled in a stacked relationship to form a first fluid conductor between the first spacer layer and the second spacer layer, and a second fluid conductor between the second spacer layer and the second layer. 
     In more specific examples, if negative pressure is applied to the first fluid conductor, fluid can be drawn through the first aperture, into the second fluid conductor, and toward the second aperture. 
     In other more specific examples, the second film may have a high moisture-vapor transmission rate and may be configured to permit vapor pass through the second layer into the second fluid conductor. 
     Objectives, advantages, and a preferred mode of making and using the claimed subject matter may be understood best by reference to the accompanying drawings in conjunction with the following detailed description of illustrative embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a functional block diagram of an example embodiment of a therapy system that can provide negative-pressure treatment and instillation treatment in accordance with this specification; 
         FIG. 2  is a schematic diagram of an example embodiment of the therapy system of  FIG. 1  configured to apply negative pressure and treatment solutions to a tissue site; 
         FIG. 3A  is a segmented perspective bottom view of an example of a bridge that may be associated with some embodiments of the therapy system of  FIG. 1 ; 
         FIG. 3B  is a schematic view of an applicator that may be associated with some embodiments of the bridge of  FIG. 3A ; 
         FIG. 3C  is a schematic view of another example of an applicator that may be associated with some embodiments of the bridge of  FIG. 3A ; 
         FIG. 3D  is a schematic view of another example of an applicator that may be associated with some embodiments of the bridge of  FIG. 3A ; 
         FIG. 4A  is a schematic view of additional details that may be associated with various examples of support features in a bridge; 
         FIG. 4B  is a schematic view of the support features of  FIG. 4A  taken along section  4 B- 4 B, illustrating additional details that may be associated with some examples; 
         FIG. 4C  is a schematic view of the example support features of  FIG. 4A  taken along section  4 C- 4 C, illustrating additional details that may be associated with some embodiments; 
         FIG. 5A  is a schematic view of additional details that may be associated with some embodiments of a bridge in the therapy system of  FIG. 1 ; 
         FIG. 5B  is a schematic view taken along section  5 B- 5 B of  FIG. 5A , illustrating additional details that may be associated with some embodiments; 
         FIGS. 6A, 6B, and 6C  illustrate other examples of features that may be associated with some embodiments of a bridge in the therapy system of  FIG. 1 ; 
         FIG. 7  is a schematic diagram of the bridge of  FIG. 3A  applied to a tissue site with negative pressure; 
         FIG. 8  is a perspective bottom view of another example of a bridge that may be associated with some embodiments of the therapy system of  FIG. 1 ; 
         FIG. 9A  and  FIG. 9B  are segmented perspective views of the bridge of  FIG. 8 ; 
         FIG. 10  is an assembly view of another example of a bridge that may be associated with some example embodiments of the therapy system of  FIG. 1 ; 
         FIG. 11A  is a segmented view of an assembled portion of the bridge in the example of  FIG. 10 , illustrating additional details that may be associated with some embodiments; 
         FIG. 11B  is a segmented perspective view of portion of the bridge in the example of  FIG. 10 , illustrating additional details that may be associated with some embodiments; 
         FIG. 12A  is a schematic view of an example configuration of fluid pathways in the bridge of  FIG. 10  as assembled, illustrating additional details that may be associated with some embodiments; 
         FIG. 12B  is a schematic view taken along line  12 B- 12 B of  FIG. 12A ; 
         FIG. 12C  is a schematic view taken along line  12 C- 12 C of  FIG. 12A ; 
         FIG. 13A  is a schematic view of another example configuration of fluid pathways in the bridge of  FIG. 10  as assembled, illustrating additional details that may be associated with some embodiments; 
         FIG. 13B  is a schematic view taken along line  13 B- 13 B of  FIG. 13A ; 
         FIG. 13C  is a schematic view taken along line  13 C- 13 C of  FIG. 13A ; 
         FIG. 14  is an assembly view of another example of a bridge; 
         FIG. 15A  is a schematic view of an example configuration of fluid pathways in the bridge of  FIG. 14  as assembled, illustrating additional details that may be associated with some embodiments; 
         FIG. 15B  is a schematic view taken along line  15 B- 15 B of  FIG. 15A ; 
         FIG. 15C  is a schematic view taken along line  15 C- 15 C of  FIG. 15A ; 
         FIG. 15D  is a schematic view taken along line  15 D- 15 D of  FIG. 15A ; 
         FIG. 16  is an assembly view of another example of a bridge; 
         FIG. 17A  is a schematic view of an example configuration of fluid pathways in the bridge of  FIG. 16  as assembled, illustrating additional details that may be associated with some embodiments; 
         FIG. 17B  is a schematic view taken along line  17 B- 17 B of  FIG. 17A ; 
         FIG. 17C  is a schematic view taken along line  17 C- 17 C of  FIG. 17A ; 
         FIG. 18  is an assembly view of another example of a bridge; 
         FIG. 19A  is a schematic view of an example configuration of fluid pathways in the bridge of  FIG. 18  as assembled, illustrating additional details that may be associated with some embodiments; 
         FIG. 19B  is a schematic view taken along line  19 B- 19 B of  FIG. 19A ; 
         FIG. 19C  is a schematic view taken along line  19 C- 19 C of  FIG. 19A ; 
         FIG. 20  is an assembly view of another example of a bridge; 
         FIG. 21  is an assembled section view of the bridge of  FIG. 20 . 
         FIG. 22  is an assembly view of another example of a bridge; 
         FIG. 23  is an assembly view of another example of a bridge; 
         FIG. 24  is an assembly view of another example of a bridge; and 
         FIG. 25  is a schematic view of the bridge of  FIG. 14  applied to a tissue site. 
     
    
    
     DESCRIPTION OF EXAMPLE EMBODIMENTS 
     The following description of example embodiments provides information that enables a person skilled in the art to make and use the subject matter set forth in the appended claims, but it may omit certain details already well known in the art. The following detailed description is, therefore, to be taken as illustrative and not limiting. 
     The example embodiments may also be described herein with reference to spatial relationships between various elements or to the spatial orientation of various elements depicted in the attached drawings. In general, such relationships or orientation assume a frame of reference consistent with or relative to a patient in a position to receive treatment. However, as should be recognized by those skilled in the art, this frame of reference is merely a descriptive expedient rather than a strict prescription. 
       FIG. 1  is a simplified functional block diagram of an example embodiment of a therapy system  100  that can provide negative-pressure therapy with instillation of topical treatment solutions to a tissue site in accordance with this specification. 
     The term “tissue site” in this context broadly refers to a wound, defect, or other treatment target located on or within tissue, including, but not limited to, bone tissue, adipose tissue, muscle tissue, neural tissue, dermal tissue, vascular tissue, connective tissue, cartilage, tendons, or ligaments. A wound may include chronic, acute, traumatic, subacute, and dehisced wounds, partial-thickness burns, ulcers (such as diabetic, pressure, or venous insufficiency ulcers), flaps, and grafts, for example. The term “tissue site” may also refer to areas of any tissue that are not necessarily wounded or defective, but are instead areas in which it may be desirable to add or promote the growth of additional tissue. For example, negative pressure may be applied to a tissue site to grow additional tissue that may be harvested and transplanted. 
     The therapy system  100  may include a source or supply of negative pressure, such as a negative-pressure source  105 , and one or more distribution components. A distribution component is preferably detachable and may be disposable, reusable, or recyclable. A dressing, such as a dressing  110 , and a fluid container, such as a container  115 , are examples of distribution components that may be associated with some examples of the therapy system  100 . As illustrated in the example of  FIG. 1 , the dressing  110  may comprise or consist essentially of a tissue interface  120 , a cover  125 , or both in some embodiments. 
     A fluid conductor is another illustrative example of a distribution component. A “fluid conductor,” in this context, broadly includes a tube, pipe, hose, conduit, or other structure with one or more lumina or open pathways adapted to convey a fluid between two ends. A tube, for example, is generally an elongated, flexible structure with a cylindrical lumen, but the geometry and rigidity may vary. Moreover, some fluid conductors may be molded into or otherwise integrally combined with other components. Distribution components may also include or comprise interfaces or fluid ports to facilitate coupling and de-coupling other components. In some embodiments, for example, a dressing interface may facilitate coupling a fluid conductor to the dressing  110 . For example, such a dressing interface may be a SENSAT.R.A.C.™ Pad, available from Kinetic Concepts, Inc. of San Antonio, Tex. 
     The therapy system  100  may also include a regulator or controller, such as a controller  130 . Additionally, the therapy system  100  may include sensors to measure operating parameters and provide feedback signals to the controller  130  indicative of the operating parameters. As illustrated in  FIG. 1 , for example, the therapy system  100  may include a first sensor  135  and a second sensor  140  coupled to the controller  130 . 
     The therapy system  100  may also include a source of instillation solution. For example, a solution source  145  may be fluidly coupled to the dressing  110 , as illustrated in the example embodiment of  FIG. 1 . The solution source  145  may be fluidly coupled to a positive-pressure source, such as a positive-pressure source  150 , a negative-pressure source, such as the negative-pressure source  105 , or both in some embodiments. A regulator, such as an instillation regulator  155 , may also be fluidly coupled to the solution source  145  and the dressing  110  to ensure proper dosage of instillation solution (e.g. saline) to a tissue site. For example, the instillation regulator  155  may comprise a piston that can be pneumatically actuated by the negative-pressure source  105  to draw instillation solution from the solution source during a negative-pressure interval and to instill the solution to a dressing during a venting interval. Additionally or alternatively, the controller  130  may be coupled to the negative-pressure source  105 , the positive-pressure source  150 , or both, to control dosage of instillation solution to a tissue site. In some embodiments, the instillation regulator  155  may also be fluidly coupled to the negative-pressure source  105  through the dressing  110 , as illustrated in the example of  FIG. 1 . 
     In some examples, a bridge  160  may fluidly couple the dressing  110  to the negative-pressure source  105 , as illustrated in  FIG. 1 . The therapy system  100  may also comprise a flow regulator, such as a regulator  165 , fluidly coupled to a source of ambient air to provide a controlled or managed flow of ambient air. In some embodiments, the regulator  165  may be fluidly coupled to the tissue interface  120  through the bridge  160 . In some embodiments, the regulator  165  may be positioned proximate to the container  115  and/or proximate a source of ambient air, where the regulator  165  is less likely to be blocked during usage. 
     Some components of the therapy system  100  may be housed within or used in conjunction with other components, such as sensors, processing units, alarm indicators, memory, databases, software, display devices, or user interfaces that further facilitate therapy. For example, in some embodiments, the negative-pressure source  105  may be combined with the controller  130 , the solution source  145 , and other components into a therapy unit. 
     In general, components of the therapy system  100  may be coupled directly or indirectly. For example, the negative-pressure source  105  may be directly coupled to the container  115  and may be indirectly coupled to the dressing  110  through the container  115 . Coupling may include fluid, mechanical, thermal, electrical, or chemical coupling (such as a chemical bond), or some combination of coupling in some contexts. For example, the negative-pressure source  105  may be electrically coupled to the controller  130  and may be fluidly coupled to one or more distribution components to provide a fluid path to a tissue site. In some embodiments, components may also be coupled by virtue of physical proximity, being integral to a single structure, or being formed from the same piece of material. 
     A negative-pressure supply, such as the negative-pressure source  105 , may be a reservoir of air at a negative pressure or may be a manual or electrically-powered device, such as a vacuum pump, a suction pump, a wall suction port available at many healthcare facilities, or a micro-pump, for example. “Negative pressure” generally refers to a pressure less than a local ambient pressure, such as the ambient pressure in a local environment external to a sealed therapeutic environment. In many cases, the local ambient pressure may also be the atmospheric pressure at which a tissue site is located. Alternatively, the pressure may be less than a hydrostatic pressure associated with tissue at the tissue site. Unless otherwise indicated, values of pressure stated herein are gauge pressures. References to increases in negative pressure typically refer to a decrease in absolute pressure, while decreases in negative pressure typically refer to an increase in absolute pressure. While the amount and nature of negative pressure provided by the negative-pressure source  105  may vary according to therapeutic requirements, the pressure is generally a low vacuum, also commonly referred to as a rough vacuum, between −5 mm Hg (−667 Pa) and −500 mm Hg (−66.7 kPa). Common therapeutic ranges are between −50 mm Hg (−6.7 kPa) and −300 mm Hg (−39.9 kPa). 
     The container  115  is representative of a container, canister, pouch, or other storage component, which can be used to manage exudates and other fluids withdrawn from a tissue site. In many environments, a rigid container may be preferred or required for collecting, storing, and disposing of fluids. In other environments, fluids may be properly disposed of without rigid container storage, and a re-usable container could reduce waste and costs associated with negative-pressure therapy. 
     A controller, such as the controller  130 , may be a microprocessor or computer programmed to operate one or more components of the therapy system  100 , such as the negative-pressure source  105 . In some embodiments, for example, the controller  130  may be a microcontroller, which generally comprises an integrated circuit containing a processor core and a memory programmed to directly or indirectly control one or more operating parameters of the therapy system  100 . Operating parameters may include the power applied to the negative-pressure source  105 , the pressure generated by the negative-pressure source  105 , or the pressure distributed to the tissue interface  120 , for example. The controller  130  is also preferably configured to receive one or more input signals, such as a feedback signal, and programmed to modify one or more operating parameters based on the input signals. 
     Sensors, such as the first sensor  135  and the second sensor  140 , are generally known in the art as any apparatus operable to detect or measure a physical phenomenon or property, and generally provide a signal indicative of the phenomenon or property that is detected or measured. For example, the first sensor  135  and the second sensor  140  may be configured to measure one or more operating parameters of the therapy system  100 . In some embodiments, the first sensor  135  may be a transducer configured to measure pressure in a pneumatic pathway and convert the measurement to a signal indicative of the pressure measured. In some embodiments, for example, the first sensor  135  may be a piezo-resistive strain gauge. The second sensor  140  may optionally measure operating parameters of the negative-pressure source  105 , such as a voltage or current, in some embodiments. Preferably, the signals from the first sensor  135  and the second sensor  140  are suitable as an input signal to the controller  130 , but some signal conditioning may be appropriate in some embodiments. For example, the signal may need to be filtered or amplified before it can be processed by the controller  130 . Typically, the signal is an electrical signal, but may be represented in other forms, such as an optical signal. 
     The tissue interface  120  can be generally adapted to partially or fully contact a tissue site. The tissue interface  120  may take many forms, and may have many sizes, shapes, or thicknesses, depending on a variety of factors, such as the type of treatment being implemented or the nature and size of a tissue site. For example, the size and shape of the tissue interface  120  may be adapted to the contours of deep and irregular shaped tissue sites. Any or all of the surfaces of the tissue interface  120  may have an uneven, coarse, or jagged profile. 
     In some embodiments, the tissue interface  120  may comprise or consist essentially of a manifold. A manifold in this context may comprise or consist essentially of a means for collecting or distributing fluid across the tissue interface  120  under pressure. For example, a manifold may be adapted to receive negative pressure from a source and distribute negative pressure through multiple apertures across the tissue interface  120 , which may have the effect of collecting fluid from across a tissue site and drawing the fluid toward the source. In some embodiments, the fluid path may be reversed or a secondary fluid path may be provided to facilitate delivering fluid, such as fluid from a source of instillation solution, across a tissue site. 
     In some illustrative embodiments, a manifold may comprise a plurality of pathways, which can be interconnected to improve distribution or collection of fluids. In some illustrative embodiments, a manifold may comprise or consist essentially of a porous material having interconnected fluid pathways. Examples of suitable porous material that can be adapted to form interconnected fluid pathways (e.g., channels) may include cellular foam, including open-cell foam such as reticulated foam; porous tissue collections; and other porous material such as gauze or felted mat that generally include pores, edges, and/or walls. Liquids, gels, and other foams may also include or be cured to include apertures and fluid pathways. In some embodiments, a manifold may additionally or alternatively comprise projections that form interconnected fluid pathways. For example, a manifold may be molded to provide surface projections that define interconnected fluid pathways. 
     In some embodiments, the tissue interface  120  may comprise or consist essentially of reticulated foam having pore sizes and free volume that may vary according to needs of a prescribed therapy. For example, reticulated foam having a free volume of at least 90% may be suitable for many therapy applications, and foam having an average pore size in a range of 400-600 microns (40-50 pores per inch) may be particularly suitable for some types of therapy. The tensile strength of the tissue interface  120  may also vary according to needs of a prescribed therapy. For example, the tensile strength of foam may be increased for instillation of topical treatment solutions. The 25% compression load deflection of the tissue interface  120  may be at least 0.35 pounds per square inch, and the 65% compression load deflection may be at least 0.43 pounds per square inch. In some embodiments, the tensile strength of the tissue interface  120  may be at least 10 pounds per square inch. The tissue interface  120  may have a tear strength of at least 2.5 pounds per inch. In some embodiments, the tissue interface may be foam comprised of polyols, such as polyester or polyether, isocyanate, such as toluene diisocyanate, and polymerization modifiers, such as amines and tin compounds. In some examples, the tissue interface  120  may be reticulated polyurethane foam such as found in GRANUFOAM™ dressing or V.A.C. VERAFLO™ dressing, both available from Kinetic Concepts, Inc. of San Antonio, Tex. 
     The thickness of the tissue interface  120  may also vary according to needs of a prescribed therapy. For example, the thickness of the tissue interface may be decreased to reduce tension on peripheral tissue. The thickness of the tissue interface  120  can also affect the conformability of the tissue interface  120 . In some embodiments, a thickness in a range of about 5 millimeters to 10 millimeters may be suitable. 
     The tissue interface  120  may be either hydrophobic or hydrophilic. In an example in which the tissue interface  120  may be hydrophilic, the tissue interface  120  may also wick fluid away from a tissue site, while continuing to distribute negative pressure to the tissue site. The wicking properties of the tissue interface  120  may draw fluid away from a tissue site by capillary flow or other wicking mechanisms. An example of a hydrophilic material that may be suitable is a polyvinyl alcohol, open-cell foam such as V.A.C. WHITEFOAM™ dressing available from Kinetic Concepts, Inc. of San Antonio, Tex. Other hydrophilic foams may include those made from polyether. Other foams that may exhibit hydrophilic characteristics include hydrophobic foams that have been treated or coated to provide hydrophilicity. 
     In some embodiments, the tissue interface  120  may be constructed from bioresorbable materials. Suitable bioresorbable materials may include, without limitation, a polymeric blend of polylactic acid (PLA) and polyglycolic acid (PGA). The polymeric blend may also include, without limitation, polycarbonates, polyfumarates, and capralactones. The tissue interface  120  may further serve as a scaffold for new cell-growth, or a scaffold material may be used in conjunction with the tissue interface  120  to promote cell growth. A scaffold is generally a substance or structure used to enhance or promote the growth of cells or formation of tissue, such as a three-dimensional porous structure that provides a template for cell growth. Illustrative examples of scaffold materials include calcium phosphate, collagen, PLA/PGA, coral hydroxy apatites, carbonates, or processed allograft materials. 
     In some embodiments, the cover  125  may provide a bacterial barrier and protection from physical trauma. The cover  125  may also be constructed from a material that can reduce evaporative losses and provide a fluid seal between two components or two environments, such as between a therapeutic environment and a local external environment. The cover  125  may comprise or consist of, for example, an elastomeric film or membrane that can provide a seal adequate to maintain a negative pressure at a tissue site for a given negative-pressure source. The cover  125  may have a high moisture-vapor transmission rate (MVTR) in some applications. For example, the MVTR may be at least 250 grams per square meter per twenty-four hours in some embodiments, measured using an upright cup technique according to ASTM E96/E96M Upright Cup Method at 38° C. and 10% relative humidity (RH). In some embodiments, an MVTR up to 5,000 grams per square meter per twenty-four hours may provide effective breathability and mechanical properties. 
     In some example embodiments, the cover  125  may be a polymer drape, such as a polyurethane film, that is permeable to water vapor but impermeable to liquid. Such drapes typically have a thickness in the range of 25-50 microns. For permeable materials, the permeability generally should be low enough that a desired negative pressure may be maintained. The cover  125  may comprise, for example, one or more of the following materials: polyurethane (PU), such as hydrophilic polyurethane; cellulosics; hydrophilic polyamides; polyvinyl alcohol; polyvinyl pyrrolidone; hydrophilic acrylics; silicones, such as hydrophilic silicone elastomers; natural rubbers; polyisoprene; styrene butadiene rubber; chloroprene rubber; polybutadiene; nitrile rubber; butyl rubber; ethylene propylene rubber; ethylene propylene diene monomer; chlorosulfonated polyethylene; polysulfide rubber; ethylene vinyl acetate (EVA); co-polyester; and polyether block polymide copolymers. Such materials are commercially available as, for example, Tegaderm® drape, commercially available from 3M Company, Minneapolis Minn.; polyurethane (PU) drape, commercially available from Avery Dennison Corporation, Pasadena, Calif.; polyether block polyamide copolymer (PEBAX), for example, from Arkema S.A., Colombes, France; and Inspire 2301 and Inpsire 2327 polyurethane films, commercially available from Expopack Advanced Coatings, Wrexham, United Kingdom. In some embodiments, the cover  125  may comprise INSPIRE 2301 having an MVTR (upright cup technique) of 2600 g/m 2 /24 hours and a thickness of about 30 microns. 
     An attachment device may be used to attach the cover  125  to an attachment surface, such as undamaged epidermis, a gasket, or another cover. The attachment device may take many forms. For example, an attachment device may be a medically-acceptable, pressure-sensitive adhesive configured to bond the cover  125  to epidermis around a tissue site. In some embodiments, for example, some or all of the cover  125  may be coated with an adhesive, such as an acrylic adhesive, which may have a coating weight of about 25-65 grams per square meter (g.s.m.). Thicker adhesives, or combinations of adhesives, may be applied in some embodiments to improve the seal and reduce leaks. Other example embodiments of an attachment device may include a double-sided tape, paste, hydrocolloid, hydrogel, silicone gel, or organogel. 
     The solution source  145  may also be representative of a container, canister, pouch, bag, or other storage component, which can provide a solution for instillation therapy. Compositions of solutions may vary according to a prescribed therapy, but examples of solutions that may be suitable for some prescriptions include hypochlorite-based solutions, silver nitrate (0.5%), sulfur-based solutions, biguanides, cationic solutions, and isotonic solutions. 
     In operation, the tissue interface  120  may be placed within, over, on, or otherwise proximate to a tissue site. If the tissue site is a wound, for example, the tissue interface  120  may partially or completely fill the wound, or it may be placed over the wound. The cover  125  may be placed over the tissue interface  120  and sealed to an attachment surface near a tissue site. For example, the cover  125  may be sealed to undamaged epidermis peripheral to a tissue site. Thus, the dressing  110  can provide a sealed therapeutic environment proximate to a tissue site, substantially isolated from the external environment, and the negative-pressure source  105  can reduce pressure in the sealed therapeutic environment. In some embodiments, the regulator  165  may control the flow of ambient air to purge fluids and exudates from the sealed therapeutic environment. 
     The fluid mechanics of using a negative-pressure source to reduce pressure in another component or location, such as within a sealed therapeutic environment, can be mathematically complex. However, the basic principles of fluid mechanics applicable to negative-pressure therapy and instillation are generally well-known to those skilled in the art, and the process of reducing pressure may be described illustratively herein as “delivering,” “distributing,” or “generating” negative pressure, for example. 
     In general, exudate and other fluid flow toward lower pressure along a fluid path. Thus, the term “downstream” typically implies something in a fluid path relatively closer to a source of negative pressure or further away from a source of positive pressure. Conversely, the term “upstream” implies something relatively further away from a source of negative pressure or closer to a source of positive pressure. Similarly, it may be convenient to describe certain features in terms of fluid “inlet” or “outlet” in such a frame of reference. This orientation is generally presumed for purposes of describing various features and components herein. However, the fluid path may also be reversed in some applications, such as by substituting a positive-pressure source for a negative-pressure source, and this descriptive convention should not be construed as a limiting convention. 
     Negative pressure applied across the tissue site through the tissue interface  120  in the sealed therapeutic environment can induce macro-strain and micro-strain in the tissue site. Negative pressure can also remove exudate and other fluid from a tissue site, which can be collected in container  115 . 
     In some embodiments, the controller  130  may receive and process data from one or more sensors, such as the first sensor  135 . The controller  130  may also control the operation of one or more components of the therapy system  100  to manage the pressure delivered to the tissue interface  120 . In some embodiments, controller  130  may include an input for receiving a desired target pressure and may be programmed for processing data relating to the setting and inputting of the target pressure to be applied to the tissue interface  120 . In some example embodiments, the target pressure may be a fixed pressure value set by an operator as the target negative pressure desired for therapy at a tissue site and then provided as input to the controller  130 . The target pressure may vary from tissue site to tissue site based on the type of tissue forming a tissue site, the type of injury or wound (if any), the medical condition of the patient, and the preference of the attending physician. After selecting a desired target pressure, the controller  130  can operate the negative-pressure source  105  in one or more control modes based on the target pressure and may receive feedback from one or more sensors to maintain the target pressure at the tissue interface  120 . 
     In some embodiments, the controller  130  may have a continuous pressure mode, in which the negative-pressure source  105  is operated to provide a constant target negative pressure for the duration of treatment or until manually deactivated. Additionally or alternatively, the controller may have an intermittent pressure mode. For example, the controller  130  can operate the negative-pressure source  105  to cycle between a target pressure and atmospheric pressure. In some examples, the target pressure may be set at a value of 135 mmHg for a specified period of time (e.g., 5 min), followed by a specified period of time (e.g., 2 min) of deactivation. The cycle can be repeated by activating the negative-pressure source  105 , which can form a square wave pattern between the target pressure and atmospheric pressure. 
     In some example embodiments, the increase in negative pressure from ambient pressure to the target pressure may not be instantaneous. For example, the negative-pressure source  105  and the dressing  110  may have an initial rise time, which can vary depending on the type of dressing and therapy equipment being used. For example, the initial rise time for one therapy system may be in a range of about 20-30 mmHg/second and in a range of about 5-10 mmHg/second for another therapy system. If the therapy system  100  is operating in an intermittent mode, the repeating rise time may be a value substantially equal to the initial rise time. 
     In other examples, a target pressure can vary with time in a dynamic pressure mode. For example, the target pressure may vary in the form of a triangular waveform, varying between a negative pressure of 50 and 135 mmHg with a rise time set at a rate of +25 mmHg/min. and a descent time set at −25 mmHg/min. In other embodiments of the therapy system  100 , the triangular waveform may vary between negative pressure of 25 and 135 mmHg with a rise time set at a rate of +30 mmHg/min and a descent time set at −30 mmHg/min. 
     In some embodiments, the controller  130  may control or determine a variable target pressure in a dynamic pressure mode, and the variable target pressure may vary between a maximum and minimum pressure value that may be set as an input prescribed by an operator as the range of desired negative pressure. The variable target pressure may also be processed and controlled by the controller  130 , which can vary the target pressure according to a predetermined waveform, such as a triangular waveform, a sine waveform, or a saw-tooth waveform. In some embodiments, the waveform may be set by an operator as the predetermined or time-varying negative pressure desired for therapy. 
       FIG. 2  is a schematic diagram of an example embodiment of the therapy system  100  configured to apply negative pressure and treatment solutions to a tissue site  205 . Some components of the therapy system  100  may be housed within or used in conjunction with other components, such as processing units, alarm indicators, memory, databases, software, display devices, or user interfaces that further facilitate therapy. For example, in some embodiments, the negative-pressure source  105  may be combined with the controller  130  and other components into a therapy unit, such as a therapy unit  210  illustrated in  FIG. 2 . The therapy unit  210  may be, for example, a V.A.C.ULTA™ Therapy Unit available from Kinetic Concepts, Inc. of San Antonio, Tex. 
     In the example of  FIG. 2 , the tissue site  205  is at least partially defined by a wound edge  215 , which extends through an epidermal layer  220  and a dermal layer  225  and reaches into a hypodermis, or subcutaneous tissue  230 . The therapy system  100  may be used to treat a wound of any depth, as well as many different types of wounds, including open wounds, incisions, or other tissue sites. Treatment of the tissue site  205  may include removal of fluids originating from the tissue site  205 , such as exudates or ascites, or fluids instilled into the dressing to cleanse or treat the tissue site  205 , such as antimicrobial solutions. 
     In the example of  FIG. 2 , a conduit  235  fluidly couples the container  115  to another fluid conductor, such as the bridge  160 , which provides a fluid pathway between the conduit  235  and the tissue interface  120 . The bridge  160  in the example of  FIG. 2  is a substantially flat and flexible fluid conductor, but can also be compressed without occluding or blocking the fluid pathway between the conduit  235  and the tissue interface  120 . In some embodiments, the bridge  160  may comprise or be coupled to an applicator  240  adapted to be positioned in fluid communication with the tissue interface  120  through an aperture in the cover  125 . The cover  125  may be sealed to the epidermal layer  220  with an attachment device, such as an adhesive layer  245 . 
     In some embodiments, the applicator  240  may be integral to the bridge  160 . In other embodiments, the applicator  240  and the bridge  160  may be separate components that are coupled together to form a single device. In yet other embodiments, the applicator  240  and the bridge  160  may be separate components that may be used independently of each other in the therapy system  100 . 
     The bridge  160  may have a substantially flat profile, and an adapter  250  may be configured to fluidly couple the bridge  160  to a tube or other round fluid conductor, such as the conduit  235  illustrated in the example of  FIG. 2 . In some embodiments, the adapter  250  may have one or more sealing valves, which can isolate the conduit  235  if separated from the bridge  160 . 
     The example of  FIG. 2  also illustrates a configuration of the therapy system  100  in which the solution source  145  is fluidly coupled to the tissue interface  120  through a conduit  255  and a dressing interface  260 . 
       FIG. 3A  is a segmented perspective bottom view of an example of the bridge  160 , illustrating additional details that may be associated with some embodiments. The bridge  160  of  FIG. 3A  generally has a low profile structure.  FIG. 3A  further illustrates features that may be associated with some embodiments of the applicator  240  of  FIG. 2 . The applicator  240  may be bulbous or any shape suitable for facilitating a connection to the dressing  110 . The bridge  160  in the example of  FIG. 3A  is generally long and narrow. An adapter, such as the adapter  250 , may fluidly couple the bridge  160  to a fluid conductor, such as the conduit  235 . In some examples, the conduit  235  may be a multi-lumen tube in which a central lumen  305  is configured to couple the bridge  160  to a negative-pressure source, and one or more peripheral lumens  310  are configured to couple the bridge  160  to a sensor, such as the first sensor  135 . 
     In some embodiments, the bridge  160  may comprise a liquid barrier formed from two layers. In  FIG. 3A , for example, a periphery of a first layer  315  may be coupled to a second layer  320  to form a fluid path between two ends of the bridge  160 , including the applicator  240 . In some embodiments, one or both of the first layer  315  and the second layer  320  may be formed from or include a film of liquid-impermeable material. In some examples, the first layer  315 , the second layer  320 , or both may be formed from the same material as the cover  125 . In some examples, the film forming the first layer  315 , the second layer  320 , or both may be a thin, flexible sheet. In some examples the film forming the first layer  315 , the second layer  320 , or both may be conformable. In some examples the film forming the first layer  315 , the second layer  320 , or both may have a low flexural modulus. In some examples the film forming the first layer  315 , the second layer  320 , or both may have an ultimate elongation of greater than 100%. In some examples, the film forming the first layer  315 , the second layer  320 , or both may be polymeric. In some examples, the film forming the first layer  315 , the second layer  320 , or both may be elastomeric. In some examples, the first layer  315 , the second layer  320 , or both may be transparent. In some examples, the first layer  315 , the second layer  320 , or both may be translucent. In some examples, the first layer  315 , the second layer  320 , or both may be opaque. The first layer  315  and the second layer  320  may be coupled around the periphery of the bridge  160  to form the sealed space by welding (RF or ultrasonic), heat sealing, or adhesive bonding, such as acrylics or cured adhesives. For example, the first layer  315  and the second layer  320  may be welded together around the periphery of the bridge  160  and may form a flange  325  around the periphery of the bridge  160  as a result of the weld. 
     The bridge  160  of  FIG. 3A  may further comprise at least one barrier or wall, such as a first wall  330 , between the first layer  315  and the second layer  320 . In some embodiments, the first wall  330  may extend from the end of the bridge  160  adjacent to the adapter  250  into the applicator  240  to form at least two sealed spaces or fluid pathways between the first layer  315  and the second layer  320  within the bridge  160 . In some examples, the bridge  160  may further comprise a second barrier, such as a second wall  335 , between the first layer  315  and the second layer  320 . In some embodiments, the second wall  335  also may extend from the end of the bridge  160  adjacent to the adapter  250  into the applicator  240 . In some example embodiments, the first wall  330  and the second wall  335  may comprise a polymeric film coupled to the first layer  315  and the second layer  320 . In some other example embodiments, the first wall  330  and the second wall  335  may comprise a weld (RF or ultrasonic), a heat seal, an adhesive bond, or a combination of any of the foregoing. In some embodiments, the first wall  330  and the second wall  335  may form distinct fluid pathways within the sealed space between the first layer  315  and the second layer  320 . In  FIG. 3A , for example, the first wall  330  and the second wall  335  define in part a first pathway  340 , a second pathway  345 , and a third pathway  350 . Each of the first pathway  340 , the second pathway  345 , and the third pathway  350  generally has a first end, a second end, and a longitudinal axis. In some embodiments, one or more of the fluid pathways may be fluidly coupled or configured to be fluidly coupled to the peripheral lumens  310 , which can provide a pressure feedback path to a sensor, such as the first sensor  135 . The third pathway  350  may be fluidly coupled to or configured to be fluidly coupled to the central lumen  305 . 
     In some example embodiments, the first pathway  340 , the second pathway  345 , and the third pathway  350  may be fluidly coupled to the conduit  235  through the adapter  250 . For example, the third pathway  350  may be fluidly coupled to the conduit  235  so that the third pathway  350  can deliver negative pressure to the tissue interface  120 . Each of the first pathway  340  and the second pathway  345  may be fluidly coupled to a separate one of the peripheral lumens  310 . In other embodiments, the first pathway  340  and the second pathway  345  both may be fluidly coupled to a common space within the adapter  250 , which can be fluidly coupled to one or more of the peripheral lumens  310 . In some example embodiments, the first pathway  340 , the second pathway  345 , and the third pathway  350  may terminate within the applicator  240 . In some embodiments, the first pathway  340 , the second pathway  345 , and the third pathway  350  may be in fluid communication with each other within the applicator  240  for delivering and sensing negative pressure associated with the tissue interface  120 . 
     The bridge  160  may comprise an opening or aperture, such as an aperture  355 , adapted to fluidly couple the sealed space of the bridge  160  to the tissue interface  120 . In  FIG. 3A , for example, the aperture  355  is disposed in the applicator  240 . A recessed space  360  within the bridge  160  can be adapted to be in fluid communication with the tissue interface  120  through the aperture  355  in use. In the example of  FIG. 3A , the portions of first layer  315  and the second layer  320  at least partially define the recessed space  360  within the sealed space of the applicator  240 . In some example embodiments, the first wall  330  and the second wall  335  may extend only partially into the recessed space  360  so that the ends of the first wall  330  and the second wall  335  are exposed by the aperture  355  as shown in the example of  FIG. 3A . In some embodiments, the first pathway  340  and the second pathway  345  may be in fluid communication with the recessed space  360 . The third pathway  350  may also be in fluid communication with the recessed space  360  and can be adapted to deliver negative pressure to the tissue interface  120  through the recessed space  360 . In some example embodiments (not shown), the first wall  330  and the second wall  335  may extend beyond the aperture  355  so that less of the first pathway  340  and the second pathway  345  are exposed to negative pressure delivered to the tissue interface  120  to prevent or reduce occlusions and/or blockages. 
     The bridge  160  may further comprise a means for supporting fluid paths under pressure. In some embodiments, the means of support may comprise a plurality of support features, such as a flexible projections, standoffs, nodes, cells, porous textile, porous foam, or some combination of features disposed in a fluid path. For example, the bridge  160  of  FIG. 3A  comprises a plurality of supports  365 . Adjacent to the aperture  355 , the supports  365  may be adapted to come in direct contact with the tissue interface  120  in some examples. Support features such as the supports  365  can provide a cushion to prevent the sealed spaces of the bridge  160  from collapsing as a result of external forces. In some example embodiments, the supports  365  may come in contact with the second layer  320 , and in some other example embodiments, the top portion of the supports  365  may be coupled to the second layer  320 . In some example embodiments, the supports  365  may be disposed only in the applicator  240 , and other support features may be disposed in the bridge  160  between the applicator  240  and the conduit  235 . 
     The bridge  160  of  FIG. 3A  may also comprise an affixation surface  370  surrounding the aperture  355 , which can be coupled to the dressing  110  or directly to a tissue site in some examples. In some embodiments, a top drape (not shown) may be utilized to cover the applicator  240  for additional protection and support over the applicator  240  if applied to a tissue site. In some embodiments, a top drape may also be utilized to cover any adhesive that might be exposed. In some embodiments, a top drape may be similar to the cover  125 . For example, a top drape may comprise or consist essentially of a polymer, such as a polyurethane film. 
       FIG. 3B  is a schematic view of the applicator  240  of  FIG. 3A , taken along line  3 B- 3 B, illustrating additional details that may be associated with some embodiments. For example, some embodiments of the support features may be formed by sealing a spacer layer  375  to the first layer  315 . In the example of  FIG. 3B , each of the supports  365  comprises a standoff  380  in the spacer layer  375 . In some embodiments, the standoffs  380  may be formed by blisters, bubbles, cells or other raised formations that extend above or below a base  385  of the spacer layer  375 , for example. In some examples, the standoffs  380  may be vacuum-formed regions of the spacer layer  375 . 
     The base  385  may be sealed to the first layer  315 , and the standoffs  380  may extend from the first layer  315  toward the aperture  355  of the second layer  320  as illustrated in  FIG. 3B . At least some of the supports  365  may be configured to come in direct contact with the tissue interface  120  through the aperture  355 . 
     In some embodiments, the base  385  may be sealed to the first layer  315  so that the first layer  315  closes the standoffs  380 . For example, the base  385  may be heat-sealed to the first layer  315  while the standoffs  380  may be vacuum-formed simultaneously. In other examples, the seal may be formed by adhesion between the first layer  315  and the spacer layer  375 . Alternatively, the first layer  315  and the spacer layer  375  may be adhesively bonded to each other. 
     In general, the supports  365  are structured so that they do not completely collapse from apposition forces resulting from the application of negative pressure and/or external forces to the bridge  160 . In some examples, the first layer  315  and the spacer layer  375  may be formed from separate sheets or film brought into superposition and sealed, or they may be formed by folding a single sheet onto itself with a heat-sealable surface facing inward. Any one or more of the first layer  315 , second layer  320 , and the spacer layer  375  also may be a monolayer or multilayer structure, depending on the application or the desired structure of the support features. 
     In some example embodiments, the standoffs  380  may be substantially airtight to inhibit collapsing of the standoffs  380  under negative pressure, which could block the flow of fluid through the bridge  160 . For example, in the embodiment of  FIG. 3B , the standoffs  380  may be substantially airtight and have an internal pressure that is an ambient pressure. In another example embodiment, the standoffs  380  may be inflated with air or other suitable gases, such as carbon dioxide or nitrogen. The standoffs  380  may be inflated to have an internal pressure greater than the atmospheric pressure to maintain their shape and resistance to collapsing under pressure and external forces. For example, the standoffs  380  may be inflated to a pressure up to about 25 psi above the atmospheric pressure. 
     In some embodiments, the first layer  315 , the second layer  320 , and the spacer layer  375  may each have a thickness within a range of 400 to 600 microns. For example, the first layer  315 , the second layer  320 , and the spacer layer  375  may be formed from thermoplastic polyurethane film having a thickness of about 500 microns. In some example embodiments, each may have a thickness of about 200 μm to about 600 μm. In some embodiments, a thickness of about 500 μm or about 250 μm may be suitable. 
     In some embodiments, one or more of the first layer  315 , the second layer  320 , and the spacer layer  375  may have a different thickness. For example, the thickness of the second layer  320  may be up to 50% thinner than the thickness of the spacer layer  375 . If the fabrication process comprises injection molding, portions of the spacer layer  375  defining the standoffs  380  may have a thickness between about 400 μm and about 500 μm. However, if the standoffs  380  are fabricated by drawing a film, the spacer layer  375  proximate a top portion of the standoffs  380  may have a thickness as thin as 50 μm. 
     After the standoffs  380  have been fabricated, the walls of the standoffs  380  may have a thickness relative to the thickness of base  385 . The relative thickness may be defined by a draw ratio, such as the ratio of the average height of the standoffs  380  to the average thickness of the spacer layer  375 . In some example embodiments, the standoffs  380  may have a generally tubular shape, which may have been formed from the spacer layer  375  having various thicknesses and draw ratios. In some example embodiments, the spacer layer  375  may have an average thickness of 500 μm and the standoffs  380  may have an average height in a range between about 2.0 mm and 5.0 mm. Consequently, the standoffs  380  may have a draw ratio ranging from about 4:1 to about 10:1 for heights of 2.0 and 5.0 mm, respectively. In another example embodiment, the draw ratio may range from about 5:1 to about 13:1 where the thickness of the spacer layer  375  is an average of about 400 μm. In yet other example embodiments, the draw ratio may range from about 3:1 to about 9:1 where the thickness of the spacer layer  375  is an average of about 600 μm. In some embodiments, the standoffs  380  may have an average height in a range between about 1.0 mm and 4.0 mm, depending on the thickness of the spacer layer  375 . The spacer layer  375  may have varying thicknesses and flexibilities, but is substantially non-stretchable so that the standoffs  380  maintain a generally constant volume if sealed to the first layer  315 . Additionally, the standoffs  380  can support a load without bursting and can recover their original shape after a load is removed. 
     In some example embodiments, any one or more of the first layer  315 , the second layer  320 , and the spacer layer  375  may be formed from a non-porous, polymeric film that may comprise any flexible material that can be manipulated to form suitable support features, including various thermoplastic materials, e.g., polyethylene homopolymer or copolymer, polypropylene homopolymer or copolymer, etc. Non-limiting examples of suitable thermoplastic polymers may include polyethylene homopolymers, such as low density polyethylene (LDPE) and high density polyethylene (HDPE), and polyethylene copolymers such as, e.g., ionomers, EVA, EMA, heterogeneous (Zeigler-Natta catalyzed) ethylene/alpha-olefin copolymers, and homogeneous (metallocene, single-cite catalyzed) ethylene/alpha-olefin copolymers. Ethylene/alpha-olefin copolymers are copolymers of ethylene with one or more comonomers selected from C 3  to C 20  alpha-olefins, such as 1-butene, 1-pentene, 1-hexene, 1-octene, methyl pentene and the like, in which the polymer molecules comprise long chains with relatively few side chain branches, including linear low density polyethylene (LLDPE), linear medium density polyethylene (LMDPE), very low density polyethylene (VLDPE), and ultra-low density polyethylene (ULDPE). Various other materials may also be suitable, such as polypropylene homopolymer or polypropylene copolymer (e.g., propylene/ethylene copolymer), polyesters, polystyrenes, polyamides, polycarbonates, etc. In some example embodiments, one or more of the first layer  315 , the second layer  320 , and the spacer layer  375  may be formed from a polyether polyurethane film having a thickness in a range from about 68 microns to about 85 microns available under the part number 58240 from Avery Dennison Medical of Mentor, Ohio. In some embodiments, this polyether polyurethane film may have a thickness of about 80 microns. In some example embodiments, one or more of the first layer  315 , the second layer  320 , and the spacer layer  375  may be formed from a polyether polyurethane film having a thickness in a range from about 2.7 mil (about 68.58 microns) to about 3.3 mil (83.82 microns) available under the product number Argomed 18410D from Schweitzer-Mauduit International, Inc. of Alpharetta, Ga. In some embodiments, the polyether polyurethane film may have a thickness of about 3 mil (about 76.2 microns). In some embodiment, these polyether polyurethane films may have a durometer (Shore A) of about 88 psi (about 606.74 kPa), an ultimate tensile strength of about 8200 psi (56.54 MPa), and an ultimate elongation of 650%. 
     In some embodiments, the polymeric film may possess sufficient tensile strength to resist stretching under apposition forces created by negative-pressure therapy. The tensile strength of a material is the ability of material to resist stretching as represented by a stress-strain curve where stress is the force per unit area, i.e., Pascals (Pa), newtons per square meter (N/m 2 ), or pounds per square inch (psi). The ultimate tensile strength (UTS) is the maximum stress the material can withstand while being stretched before failing or breaking. Many materials display a linear elastic behavior defined by a linear stress-strain relationship often extending up to a nonlinear region represented by the yield point, i.e., the yield strength of a material. For example, high density polyethylene (HDPE) has a high tensile strength and low-density polyethylene (LDPE) has a slightly lower tensile strength, which are suitable materials for the sheets of non-porous, polymeric film as set forth above. Linear low density polyethylene (LLDPE) may also be suitable for some examples because the material stretches very little as the force is increased up to the yield point of the material. Thus, the standoffs  380  or other support features can be configured to resist collapsing (or stretching) when subjected to an external force or pressure. For example, HDPE has a UTS of about 37 MPa and may have a yield strength that ranges from about 26-33 MPa depending on the thickness of the material, while LDPE has somewhat lower values. 
     In some example embodiments, one or more of the first layer  315 , the second layer  320 , and the spacer layer  375  may comprise or consist essentially of a thermoplastic polyurethane (TPU) film that is permeable to water vapor but impermeable to liquid. The film may be in various degrees breathable and may have MVTRs that are proportional to their thickness. For example, the MVTR may be at least 300 g/m 2  per twenty-four hours in some embodiments. For permeable materials, the permeability generally should be low enough to maintain a desired negative pressure for the desired negative-pressure treatment. 
     In some example embodiments, the thermoplastic polyurethane film may be, for example, a Platilon® thermoplastic polyurethane film available from Convestro LLC, which may have a UTS of about 60 MPa and may have a yield strength of approximately 11 MPa or greater than about 10 MPa depending on the thickness of the material. Therefore, in some example embodiments, it is desirable that the non-porous, polymeric film may have a yield strength greater than about 10 MPa, depending on the type and thickness of material. A material having a lower yield strength may be too stretchable and, therefore, more susceptible to breaking with the application of small amounts of compression and/or apposition forces. 
       FIG. 3C  is a schematic view of another example of the applicator  240 , illustrating details that may be associated with some embodiments. In the example of  FIG. 3C , the applicator  240  has more than one spacer layer  375 . At least some of the support features may be formed by sealing the base  385  of at least one of the spacer layers  375  to the second layer  320 . Some of the supports  365  may extend from the second layer  320  toward the first layer  315  around the recessed space  360 . In the example of  FIG. 3C , all of the supports  365  around the recessed space  360  extend from the second layer  320  toward the first layer  315 . At least some of the supports  365  may also extend from the first layer  315  toward the aperture  355  in the recessed space  360 . 
       FIG. 3D  is a schematic view of another example of the applicator  240 , illustrating additional details that may be associated with some embodiments. In the example of  FIG. 3D , some of the supports  365  around the recessed space  360  extend from the second layer  320  toward the first layer  315 , and some of the supports  365  around the recessed space  360  also extend from the first layer  315  toward the second layer  320 . Some of the supports  365  also extend from the first layer  315  toward the aperture  355  in the recessed space  360 . 
       FIG. 4A  is a schematic view of additional details that may be associated with various examples of support features in the bridge  160 . For example,  FIG. 4A  illustrates a sealed region  405  between the standoffs  380 . In some embodiments, the sealed region  405  may be formed by sealing portions of the spacer layer  375  to the first layer  315  or the second layer  320 . In the example of  FIG. 4A , the sealed region  405  may be formed by sealing the base  385  to the first layer  315  around the standoffs  380 . As illustrated in the example of  FIG. 4A , the standoffs  380  may have a circular edge proximate to the sealed region  405 . In other embodiments, the standoffs  380  may have edges with other suitable shapes, such as rectangular, triangular, or hexagonal, or some combination of shapes. Additionally or alternatively, one or more of the standoffs  380  may be embossed with projections or nodes, such as the nodes  410  illustrated in the example of  FIG. 4A . 
     The standoffs  380  in adjacent rows or columns may be staggered so that the standoffs  380  may be nested or packed together, as illustrated in the example of  FIG. 4A . In other embodiments, the standoffs  380  may be arranged in other patterns suitable for the particular therapy being utilized. For example, the rows and columns of the standoffs  380  may be arranged in line to form an aligned, rectangular pattern so that there is more spacing between the standoffs  380 . Increasing the spacing between the standoffs  380  may increase fluid flow within the fluid pathways of the bridge  160 , whereas a nested arrangement may restrict fluid flow within the fluid pathways. For example, the standoffs  380  can be aligned to increase fluid flow of negative pressure being applied to a tissue interface and facilitate the removal of fluids and exudates within the recessed space  360 . A nested pattern can facilitate pressure sensing within the recessed space  360  while impeding the inflow of fluids and exudates, which can reduce the possibility of blockage. 
     In some embodiments, distribution of the standoffs  380  may be characterized by a pitch, which can be defined by the center to center distance between each of the standoffs  380 . For example, a pitch of about 1 mm to about 10 mm may be suitable for some configurations. In some embodiments, the pitch may be between about 2 mm and about 3 mm. Because the sealed region  405  can define an end of the standoffs  380 , including a diameter of a circular end, and the pitch of the standoffs  380 , the area of the spacer layer  375  having the standoffs  380  may also be determined as a percentage. For example, if each of the standoffs  380  has a diameter of about 1.0 mm and the pitch is about 2.0 mm, the coverage percentage is about 22% of the area of the spacer layer  375 . In another example, if the diameter of each of the standoffs  380  is about 2.0 mm and the pitch is about 5.0 mm, the coverage percentage is about 14% of the area of the spacer layer  375 . In yet another example, if the diameter of each of the standoffs  380  is about 1.5 mm, the pitch is about 2.0 mm, and the standoffs  380  are more tightly arranged such that there are about 28.5 standoffs in a 10 mm 2  section of the spacer layer  375 , the coverage percentage is about 51% of the area of the spacer layer  375 . Depending on the diameter, pitch, and arrangement of the standoffs  380 , the coverage percentage may range between about 10% and about 60% of the surface area of the spacer layer  375 . Support features having other shapes also may have a coverage percentage in generally the same range. 
     The size and pitch of the standoffs  380  also may be varied to effect change in the fluid flows through the fluid passageways. For example, the diameter and pitch of the standoffs  380  can be increased to increase fluid flow of negative pressure being applied to a tissue interface and facilitate the removal of fluids and exudates within the recessed space  360 . The diameter, pitch, or both may be decreased to restrict fluid flow, which can reduce blockages, and facilitate pressure sensing within the recessed space  360 . 
       FIG. 4B  is a schematic view of the support features of  FIG. 4A  taken along section  4 B- 4 B, illustrating additional details that may be associated with some examples. In some embodiments, the standoffs  380  may have a hemispherical profile, as illustrated in the example of  FIG. 4B . In other example embodiments, the standoffs  380  may be profiles that are conical, cylindrical, tubular having a flattened or hemispherical end, or geodesic. The standoffs  380  may be tubular in some embodiments, formed with generally parallel walls extending from the base  385  to a hemispherical or flat top portion of the standoffs  380 . Alternatively, the walls of the standoffs  380  may taper or expand outwardly from the base  385 . In some embodiments, the standoffs  380  that are generally hemispherical or tubular in shape may have a diameter between about 1.0 mm and about 10 mm. In some other embodiments, the standoffs  380  may have a diameter between about 2.0 mm and about 5.0 mm. 
       FIG. 4C  is a schematic view of the example support features of  FIG. 4A  taken along section  4 C- 4 C, illustrating additional details that may be associated with some embodiments. In the example of  FIG. 4C , the nodes  410  can be configured to contact the tissue interface  120  to enhance fluid flow to a tissue site. The nodes  410  may be flexible or rigid. In some embodiments, the nodes  410  may be formed from a substantially gas impermeable material, such as silicone. In other embodiments, the nodes  410  may be formed from a semi-gas permeable material. The nodes  410  may be formed from the same material as the spacer layer  375 , and may be an integral part of the spacer layer  375 . In some embodiments, the nodes  410  may be solid, while in other embodiments the projections may be hollow to increase flexibility. The nodes  410  may form a plurality of channels and/or voids to distribute reduced pressure and allow for fluid flow among the nodes  410 . The nodes may be dimensioned to provide local load points evenly distributed at a tissue interface. The pattern and position of the nodes  410  may be uniform or non-uniform. The nodes may have different profiles, including, for example, the shape of a spike, cone, pyramid, dome, cylinder or rectangle. 
       FIG. 5A  is a schematic view of additional details that may be associated with some embodiments of the bridge  160 . For example, in  FIG. 5A  one or more passageways  505  may be formed between the supports  365 . 
       FIG. 5B  is a schematic view taken along section  5 B- 5 B of  FIG. 5A , illustrating additional details that may be associated with some embodiments. For example, as seen in  FIG. 5B , at least some of the standoffs  380  may be fluidly coupled through the passageways  505 . The passageways  505  and the standoffs  380  can form a closed chamber. In some examples, a closed chamber may be formed by all of the standoffs  380  in a row fluidly coupled by the passageways  505  as shown in  FIG. 5A  and  FIG. 5B . The closed chambers may be formed in alternating rows as also shown in  FIG. 5A . The formation of closed chambers with the standoffs  380  can distribute apposition forces more equally. 
       FIGS. 6A, 6B, and 6C  illustrate other examples of features that may be associated with some embodiments of the bridge  160 . In  FIG. 6A , the first layer  315  and the spacer layer  375  define a nested arrangement of the supports  365 . The example of  FIG. 6A  further illustrates that at least some of the supports  365  may additionally or alternatively have different sizes. For example, some of the supports  365  may have a diameter in the range between about 1 mm and about 10 mm, and some of the supports  365  may have a diameter in the range between about 1 mm and about 3 mm. In some embodiments, a wall  605  may be disposed between the some of the supports  365 . For example, the wall  605  in the example of  FIG. 6A  is disposed between the supports  365  having different sizes. The supports  365  having a larger diameter and pitch may increase fluid flow to facilitate the removal of fluids and exudates within the recessed space  360  in some embodiments. In some embodiments, the supports  365  having a smaller diameter and pitch may restrict fluid flow to facilitate pressure sensing within the recessed space  360  while impeding the inflow of fluids and exudates into the first pathway  340 . The arrangement and dimensions of the supports  365  may be tailored to manage the delivery of negative pressure to the tissue interface  120  and the measurement of pressure within the recessed space  360 . 
       FIG. 7  is a schematic diagram of the bridge  160  of  FIG. 3A  applied to the tissue site  205  with negative pressure. The tissue interface  120  may be in fluid communication with the recessed space  360  through the aperture  355 . The affixation surface  370  may be coupled to the cover  125  to seal and fluidly couple the recessed space  360  to the tissue interface  120 . In the example of  FIG. 7 , the first wall  330  and the second wall  335  partially define the first pathway  340 , the second pathway  345 , and the third pathway  350  between the first layer  315  and the second layer  320 . 
     Within the recessed space  360 , the standoffs  380  can extend from the first layer  315  toward the tissue interface  120  and may be adapted to come in direct contact with the tissue interface  120  if negative pressure is applied to the bridge  160 . Negative pressure can compress the bridge  160 , and the first layer  315  and the second layer  320  can collapse toward each other because of the vacuum created within the standoffs  380 . Although the standoffs  380  may change shape or flatten somewhat under negative pressure, the volume of the standoffs  380  remains substantially constant and can maintain fluid flow through the third pathway  350 . The standoffs  380  can also provide a cushion to help prevent the sealed spaces of the bridge  160  from collapsing as a result of external forces. The standoffs  380  disposed in the third pathway  350  may be sized and arranged in a pattern that may increase fluid flow of negative pressure being applied to the tissue interface  120  to facilitate the removal of fluids and exudates within the recessed space  360 . The standoffs  380  disposed in the first pathway  340  and the second pathway  345  may be sized and arranged in a pattern to facilitate pressure sensing within the recessed space  360  while impeding the inflow of fluids and exudates into the first pathway  340  and the second pathway  345  to reduce blockage conditions. 
     The standoffs  380  may have a variety of shapes, and may be sized and arranged in different patterns within the sealed space to enhance the delivery of negative pressure to the tissue interface  120  for a specific type of tissue site while optimizing pressure sensing and measurement of the negative pressure within the recessed space  360 . 
       FIG. 8  is a perspective bottom view of another example of the bridge  160  having a low-profile structure that may be associated with some embodiments of the therapy system  100 . As illustrated in the example of  FIG. 8 , the first wall  330  and the second wall  335  may extend lengthwise through the bridge  160  between the recessed space  360  and the adapter  250 . 
       FIG. 9A  and  FIG. 9B  are segmented perspective views of the bridge  160  of  FIG. 8 , illustrating additional details that may be associated with some examples.  FIG. 9A  is a bottom perspective view of an example of the applicator  240 , illustrating a configuration having a circular profile.  FIG. 9B  is a top perspective view of an example of the adapter  250 , which may have an elbow connector of semi-rigid material in some embodiments. 
     The aperture  355  of  FIG. 9A  is generally circular and opens to the recessed space  360 . The supports  365  of  FIG. 9A  may have a generally elongated and arcuate profile and may be arranged in a generally concentric pattern within the recessed space  360 . Some embodiments of the supports  365  may also comprise surface features, such as the nodes  410 . The supports  365  disposed in the center of the recessed space  360  may be more aligned with the third pathway  350  to increase fluid flow of negative pressure being applied to the tissue interface  120  and facilitate the removal of fluids and exudates within the recessed space  360 . In some embodiments, some of the supports  365  may be disposed around the aperture  355  to form a semicircular path opposite the third pathway  350 , including spaces or gaps  805  between the supports  365 . The semicircular alignment of the supports  365  may be positioned within the recessed space  360  to minimize contact with the flow of fluids passing through from the tissue interface  120  to the third pathway  350  if negative pressure is applied. Additionally, the gaps  805  may be sufficiently small for further restricting fluid flow into the first pathway  340  and the second pathway  345 , as indicated by the dashed arrows. The gaps  805  can facilitate pressure sensing within the recessed space  360  while impeding the inflow of fluids and exudates into the first pathway  340  and the second pathway  345  to reduce the possibility of blockage. In some embodiments, a portion of the perimeter of the aperture  355  may be welded to an outer ring of the supports  365  to further restrict fluid flow to the first pathway  340  and the second pathway  345  and further impede the inflow of fluids and exudates without inhibiting pressure sensing within the recessed space  360 . 
       FIG. 10  is an assembly view of another example of the bridge  160  having a low-profile structure that may be associated with some embodiments of the therapy system  100 . As illustrated in the example of  FIG. 10 , the bridge  160  comprises two spacer layers—a spacer layer  1005  and a spacer layer  1010 —disposed between the first layer  315  and the second layer  320 . Standoffs  380  may be formed in each of the spacer layer  1005  and the spacer layer  1010 . In the example of  FIG. 10 , the standoffs  380  in the spacer layer  1005  are configured to extend toward the spacer layer  1010 , and the standoffs  380  in the spacer layer  1010  are configured to extend toward the spacer layer  1005 . The first layer  315  may have a passage  1015 , and the spacer layer  1005  may have a passage  1020 , through which fluids may flow to the adapter  250 . The passage  1015  may be concentric with the passage  1020 . The first layer  315  and the spacer layer  1005  may additionally have a passage  1025  and a passage  1030 , respectively, which may also be fluidly coupled to the adapter  250 . The passage  1025  may be concentric with the passage  1030 . The bridge  160  may further comprise a fluid exit bond  1035 , which can prevent leakage of fluids flowing through the passage  1015  and the passage  1020 . The spacer layer  1010  may further have an aperture  1040  concentric with the aperture  355  of the second layer  320 . The second layer  320  may have an aperture  1045 . In some embodiments, the aperture  1045  may have a diameter in a range of about 0.01 millimeters to about 2.5 millimeters. In some embodiments, the aperture  1045  may have a diameter less than 0.01 millimeters. In some embodiments, the aperture  1045  may have a diameter greater than 2.5 millimeters. A hydrophobic filter  1050  may be disposed over the aperture  1045 . 
     As further shown in  FIG. 10 , the passage  1015  and the passage  1025  may be located proximate a first end of the first layer  315 , the passage  1020  and the passage  1030  may be located proximate a first end of the spacer layer  1005 , the aperture  1040  may be located proximate a second end of the spacer layer  1010 , the aperture  1045  may be located proximate a first end of the second layer  320 , and the aperture  355  may be located proximate a second end of the second layer  320 . 
     In some embodiments, the second layer  320  may be a film having a high MVTR in some applications. For example, the MVTR may be at least 250 grams per square meter per twenty-four hours in some embodiments, measured using an upright cup technique according to ASTM E96/E96M Upright Cup Method at 38° C. and 10% relative humidity (RH). In some embodiments, an MVTR up to 5,000 grams per square meter per twenty-four hours may provide effective breathability and mechanical properties. In some embodiments, the second layer  320  may comprise or consist essentially of a polymer film, such as Inspire 2301 and Inpsire 2304 polyurethane films, commercially available from Expopack Advanced Coatings, Wrexham, United Kingdom. In some embodiments, the second layer  320  may comprise INSPIRE 2301 having an MVTR (upright cup technique) of 2600-2700 g/m 2 /24 hours and a thickness of about 30 microns. In some embodiments, the second layer  320  may comprise INSPIRE 2304 having an MVTR (upright cup technique) of 2600 g/m 2 /24 hours and a thickness of about 30 microns. The second layer  320  may be oriented to permit moisture-vapor transmission through the second layer  320  toward the first layer  315 . 
     In some embodiments, a bridge cover  1055  may provide additional protection and support over a portion of the bridge  160 . In some embodiments, the bridge cover  1055  may also cover any adhesive that might be exposed after applying the bridge  160  to a tissue site. In some embodiments, the bridge cover  1055  may be similar or analogous to the cover  125 . For example, the bridge cover  1055  may be a polymer, such as a polyurethane film. 
       FIG. 11A  is a segmented view of an assembled portion of the bridge  160  in the example of  FIG. 10 , illustrating additional details that may be associated with some embodiments. As illustrated in the example of  FIG. 11A , the first layer  315 , second layer  320 , the spacer layer  1005 , and the spacer layer  1010  may be assembled in a stacked relationship. For example, the first layer  315  may be coupled to the spacer layer  1005 , the second layer  320  may be coupled to the spacer layer  1010 , and a periphery of the spacer layer  1005  may be coupled to a periphery of the spacer layer  1010  to form the flange  325 . The spacer layer  1005  and the spacer layer  1010  can be coupled to form a liquid barrier defining a fluid path along a longitudinal axis of the bridge  160 . 
     Some embodiments of the bridge  160  may additionally comprise at least one barrier or wall, such as a first wall  1105 , interior to the flange  325 . The first wall  1105  may be formed by coupling the spacer layer  1005  and the spacer layer  1010 . For example, the spacer layer  1005  may be welded to the spacer layer  1010  to form the first wall  1105 . In some embodiments, the first wall  1105  may extend lengthwise through the bridge  160  into the applicator  240  to form at least two fluid paths between the spacer layer  1005  and the spacer layer  1010  within the bridge  160 . In some examples, the bridge  160  may further comprise a second barrier, such as a second wall  1110 . The second wall  1110  may be formed by coupling the spacer layer  1005  and the spacer layer  1010 . In some embodiments, the second wall  1110  also may extend lengthwise through the bridge  160  into the applicator  240 . In some example embodiments, the first wall  1105  and the second wall  1110  may comprise a polymeric film coupled between the first layer  315  and the second layer  320 . In some other example embodiments, the first wall  1105  and the second wall  1110  may comprise a weld (RF or ultrasonic), a heat seal, an adhesive bond, or a combination of any of the foregoing. 
     In some embodiments, barriers or walls interior to the flange  325  may form fluid pathways between the spacer layer  1005  and the spacer layer  1010 . For example, in  FIG. 11A , the first wall  1105  and the second wall  1110  cooperate with the flange  325  to form a first fluid conductor  1115 , a second fluid conductor  1120 , a third fluid conductor  1125 , and a fourth fluid conductor  1127 . In some applications, the first fluid conductor  1115  and the second fluid conductor  1120  may be coupled to a sensor to measure pressure. The third fluid conductor  1125  may be coupled to a negative-pressure source and the fourth fluid conductor  1127  may be coupled to the third fluid conductor  1125  through the aperture  1040 . In some example embodiments, the first fluid conductor  1115  and the second fluid conductor  1120  may have a height having a value in a range between about 0.25 mm and about 3 mm. In some example embodiments, the first fluid conductor  1115  and the second fluid conductor  1120  may have a width having a value in a range between about 1 mm and about 7.5 mm. Thus, the first fluid conductor  1115  and the second fluid conductor  1120  may have a cross-sectional area having a value in a range between about 0.17 mm 2  and 16.77 mm 2 . In some embodiments, the first fluid conductor  1115  and the second fluid conductor  1120  may have a cross-sectional area having a value in a range between about 0.1 mm 2  and 18 mm 2 . 
     In some examples, each of the first wall  1105  and the second wall  1110  may extend an angular distance around the proximal end of the applicator  240  and cooperate with blocking walls of the flange  325 , such as blocking walls  1130 , to form extensions of the first fluid conductor  1115  and the second fluid conductor  1120 . The extensions may be fluidly coupled to the recessed space  360 . In the example of  FIG. 11A , the first fluid conductor  1115  and the second fluid conductor  1120  are fluidly coupled to the recessed space  360  through passages, such as a through-hole  1135  and a through-hole  1140 , respectively. In some examples, at least some of the supports may be disposed in one or both of the first fluid conductor  1115  and the second fluid conductor  1120 . For example, some of the supports may be formed by the standoffs  380  disposed between the flange  325  and the first wall  1105 , and between the flange  325  and the second wall  1110 . Additionally or alternatively, the thickness of the spacer layer  1010  may be increased to provide additional structural support to the first fluid conductor  1115  and the second fluid conductor  1120 . In some examples, the first fluid conductor  1115  and the second fluid conductor  1120  may comprise or be formed by tubes through or along the bridge  160 . Some configurations may not have the first fluid conductor  1115  or the second fluid conductor  1120 , or may have only one of the first fluid conductor  1115  and the second fluid conductor  1120 . 
     Each of the first wall  1105  and the second wall  1110  can extend at least partially around the proximal end of the applicator  240  that form the first fluid conductor  1115  and the second fluid conductor  1120 . For example, in some embodiments each of the first wall  1105  and the second wall  1110  can extend from about 45° to about 315° from the center of the third fluid conductor  1125  where the third fluid conductor  1125  is in fluid communication with the recessed space  360 . In some embodiments, the angular distance may be different for each of the first fluid conductor  1115  and the second fluid conductor  1120 . For example, the angular distance for each of the first fluid conductor  1115  and the second fluid conductor  1120  may be about 60° and 210°, respectively, from the third fluid conductor  1125 . 
     In some example embodiments, the through-hole  1135  and the through-hole  1140  may be separated from each other by an angular distance of at least 90°, extending around the applicator  240  in a direction away from the third fluid conductor  1125 . The spacing and disposition of the through-hole  1135  and the through-hole  1140  from each other, and from the third fluid conductor  1125 , can allow the first fluid conductor  1115  and the second fluid conductor  1120  to better avoid the flow of fluids passing through from the tissue interface  120  to the third fluid conductor  1125  when negative pressure is applied. Additionally, the through-hole  1135  and the through-hole  1140  may be sufficiently small for further restricting fluid flow into the first fluid conductor  1115  and the second fluid conductor  1120 . In some embodiments, the through-hole  1135  and the through-hole  1140  may have a cross-sectional area having a value in a range between about 0.17 mm 2  and 16.77 mm 2 . In some embodiments, the through-hole  1135  and the through-hole  1140  may have a cross-sectional area having a value in a range between about 0.1 mm 2  and 18 mm 2  to further restrict fluid flow to the first fluid conductor  1115  and the second fluid conductor  1120  and impede the inflow of fluids and exudates without inhibiting pressure sensing within the recessed space  360 . 
     As further shown in  FIG. 11A , in some examples, at least some of the supports  365  may be disposed in the third fluid conductor  1125 . For example, some of the supports  365  may be formed by the standoffs  380  disposed between the first wall  1105  and the second wall  1110 . 
       FIG. 11B  is a segmented perspective view of portion of the bridge  160  in the example of  FIG. 10 , illustrating additional details that may be associated with some embodiments.  FIG. 11B  further illustrates an example of the adapter  250  and the conduit  235  coupled to the bridge  160 . Each of the first fluid conductor  1115  and the second fluid conductor  1120  may be fluidly coupled directly to the conduit  235  in some examples. In other examples, both of the first fluid conductor  1115  and the second fluid conductor  1120  may be fluidly coupled to a single space (not shown) within the adapter  250 , which can be fluidly coupled to the conduit  235 . 
     In the example of  FIG. 11A  and  FIG. 11B , both the first fluid conductor  1115  and the second fluid conductor  1120  are fluidly separate from and parallel to the third fluid conductor  1125  and the fourth fluid conductor  1127 . The parallel orientation can minimize the vertical profile of the bridge  160 , while still being resistant to collapsing under pressure that could block fluid flow through the fluid pathways. 
       FIG. 12A  is a schematic view of an example configuration of fluid pathways in the bridge  160  of  FIG. 10  as assembled, illustrating additional details that may be associated with some embodiments. In the example of  FIG. 12A , the bridge  160  has four rows of the supports  365 , and the supports  365  forming outside rows are offset or staggered from the supports  365  forming the two inside rows.  FIG. 12B  is a schematic view taken along line  12 B- 12 B, and  FIG. 12C  is a schematic view taken along line  12 C- 12 C. The supports  365  may have a variety of shapes, and may be sized and arranged in different patterns within the third fluid conductor  1125 . For example, as illustrated in the examples of  FIG. 12B  and  FIG. 12C , some of the supports  365  may extend from the spacer layer  1005  away from the first layer  315  and some of the supports  365  may extend from the spacer layer  1010  away from the second layer  320 . In some embodiments, some of the supports  365  may be opposingly aligned. For example, at least some of the supports  365  can extend from the spacer layer  1005  towards some of the supports  365  extending from the spacer layer  1010 , and some of the supports  365  in opposition may contact each other. In some embodiments, the bridge  160  may include more than one row of the supports  365 . Each of the first wall  1105  and the second wall  1110  cooperate with the flange  325  to form the first fluid conductor  1115  and the second fluid conductor  1120 . In some embodiments, some of the supports  365  may be disposed within one or both of the first fluid conductor  1115  and the second fluid conductor  1120 . As further shown in  FIG. 12B  and  FIG. 12C , the first wall  1105 , the second wall  1110 , the spacer layer  1010 , and the second layer  320  may cooperate for form the fourth fluid conductor  1127 . Thus, the fourth fluid conductor  1127  may be between the spacer layer  1010  and the second layer  320 . 
     The supports  365  disposed in the third fluid conductor  1125  may have a larger diameter and pitch than the supports  365  in the first fluid conductor  1115  and the second fluid conductor  1120 , and may increase fluid flow to facilitate the removal of fluids and exudates within the recessed space  360 . The supports  365  in the first fluid conductor  1115  and the second fluid conductor  1120  may have a noticeably smaller diameter and pitch than the supports  365  in the third fluid conductor  1125 , and may restrict fluid flow to facilitate pressure sensing within the recessed space  360  while impeding the inflow of fluids and exudates into the first fluid conductor  1115  and the second fluid conductor  1120 . The arrangement and dimensions of the supports  365  may be tailored to manage the delivery of negative pressure to the tissue interface  120  and the measurement of pressure within the recessed space  360 . 
       FIG. 13A  is a schematic view of another example configuration of fluid pathways in the bridge  160  of  FIG. 10  as assembled, illustrating additional details that may be associated with some embodiments.  FIG. 13B  is a schematic view taken along line  13 B- 13 B, and  FIG. 13C  is a schematic view taken along line  13 C- 13 C. The example of  FIG. 13A  includes four rows of the supports  365 , which are aligned both horizontally and vertically rather than being offset or staggered with each other. In some embodiments, the first fluid conductor  1115  and the second fluid conductor  1120  may be opened and supported by increasing the thickness of the spacer layer  1010 . 
       FIG. 14  is an assembly view of another example of the bridge  160 . In the example of  FIG. 14 , some of the standoffs  380  extend from the spacer layer  1010  away from the second layer  320  and some of the standoffs  380  may extend from the spacer layer  1010  toward the second layer  320 . In some embodiments, the standoffs  380  that extend from the spacer layer  1010  toward the second layer  320  may be smaller in diameter than the standoffs  380  that extend from the spacer layer  1010  away from the second layer  320 . In some embodiments, the standoffs  380  that extend from the spacer layer  1010  toward the second layer  320  may have a length less than a length of the standoffs  380  that extend from the spacer layer  1010  away from the second layer  320 . As illustrated in  FIG. 14 , in some embodiments, the number of the standoffs  380  that extend from the spacer layer  1010  toward the second layer  320  may be less than the number of standoffs  380  that extend from the spacer layer  1010  away from the second layer  320 . In some embodiments, a plurality of standoffs  380  that extend toward the second layer  320  may be located in the spacer layer  1010  at the end of the spacer layer  1010  proximate the aperture  1045 . 
       FIG. 15A  is a schematic view of an example configuration of fluid pathways in the bridge  160  of  FIG. 14  as assembled. In the example of  FIG. 15A , the bridge  160  has four rows of the supports  365 , and the supports  365  forming outside rows are offset or staggered from the supports  365  forming the two inside rows.  FIG. 15B  is a schematic view taken along line  15 B- 15 B,  FIG. 15C  is a schematic view taken along line  15 C- 15 C, and  FIG. 15D  is a schematic view taken along line  15 D- 15 D. The supports  365  may have a variety of shapes, and may be sized and arranged in different patterns within the third fluid conductor  1125 . For example, as illustrated in the examples of  FIG. 15B ,  FIG. 15C , and  FIG. 15D , some of the supports  365  may extend from the spacer layer  1010  away from the second layer  320  and some of the supports  365  may extend from the spacer layer  1010  toward the second layer  320 . In some embodiments, as illustrated in  FIG. 15B  and  FIG. 15C , the supports  365  that extend from the spacer layer  1010  toward the second layer  320  may be symmetrically disposed proximate a longitudinal plane A of the bridge  160 . In some embodiments, as illustrated in  FIG. 15D , the supports  365  in spacer layer  1010  may alternate between extending toward the second layer  320  and away from the second layer  320 . As illustrated in  FIG. 15B ,  FIG. 15C , and  FIG. 15D , the supports  365  that extend from the spacer layer  1010  toward the second layer  320  may be disposed within the fourth fluid conductor  1127 . The supports  365  that extend from the spacer layer  1010  toward the second layer  320  may be configured to prevent or reduce collapse of the fourth fluid conductor  1127  upon the application of negative pressure. 
       FIG. 16  is an assembly view of another example of the bridge  160 . In the example of  FIG. 16 , the bridge  160  may comprise a spacer layer  1600  disposed between the spacer layer  1010  and the second layer  320 . Standoffs  380  may be formed in the spacer layer  1600 . In the example of  FIG. 16 , the standoffs  380  in the spacer layer  1600  are configured to extend toward the second layer  320 . The spacer layer  1600  may have an aperture  1605  concentric with the aperture  355  of the second layer  320  and the aperture  1040  of the spacer layer  1010 . 
       FIG. 17A  is a schematic view of an example configuration of fluid pathways in the bridge  160  of  FIG. 16  as assembled. In the example of  FIG. 17A , the bridge  160  has four rows of the supports  365 , and the supports  365  forming outside rows are offset or staggered from the supports  365  forming the two inside rows.  FIG. 17B  is a schematic view taken along line  17 B- 17 B, and  FIG. 17C  is a schematic view taken along line  17 C- 17 C. The supports  365  may have a variety of shapes, and may be sized and arranged in different patterns within the third fluid conductor  1125 . For example, as illustrated in the examples of  FIG. 17B  and  FIG. 17C , some of the supports  365  may extend from the spacer layer  1600  away from the spacer layer  1010  and toward the second layer  320 . In some embodiments, at least some of the supports  365  can extend from the spacer layer  1010  away from some of the supports  365  extending from the spacer layer  1600 . Additionally, at least some of the supports  365  extending from the spacer layer  1010  may have an end that is open and at least some of the supports  365  extending from the spacer layer  1600  may have an end that is open, wherein at least some of the open ends of the supports  365  extending from the spacer layer  1010  abut at least some of the open ends of the supports  365  extending from the spacer layer  1600 . In some embodiments, at least some of the supports  365  extending from the spacer layer  1010  and at least some of the supports  365  extending from the spacer layer  1600  cooperate to form a sealed space. As illustrated in  FIG. 17B  and  FIG. 17C , the supports  365  that extend from the spacer layer  1600  may be disposed within the fourth fluid conductor  1127 . The supports  365  that extend from the spacer layer  1600  may be configured to prevent or reduce collapse of the fourth fluid conductor  1127  upon the application of negative pressure. 
       FIG. 18  is an assembly view of another example of the bridge  160 . In the example of  FIG. 18 , the bridge  160  may further include a third layer  1800  and a spacer layer  1805 . The third layer  1800  may be disposed between the spacer layer  1010  and the second layer  320 . The spacer layer  1805  may be disposed between the third layer  1800  and the second layer  320 . The third layer  1800  may have an aperture  1810  concentric with the aperture  355  of the second layer  320  and the aperture  1040  of the spacer layer  1010 . The spacer layer  1805  may have an aperture  1815  concentric with the aperture  355  of the second layer  320 , the aperture  1810  of the third layer  1800 , and the aperture  1040  of the spacer layer  1010 . 
     The third layer  1800  may be formed from or include a film of liquid-impermeable material. In some examples, the third layer  1800  may be formed from the same material as the first layer  315 . In some examples, the third layer  1800  may be formed from the same material as the cover  125 . The spacer layer  1805  may be formed of a variety of materials and configurations that are open to pressure and fluid flow, particularly in the form of air. In some examples, the spacer layer  1805  may be hydrophobic to discourage ingress of exudate, and should resist blocking under compression. Additionally or alternatively, anti-clotting agents may be bound to the spacer layer  1805 . Examples of materials suitable for some embodiments of the spacer layer  1805  may include reticulated foam (preferably having a thickness in a range of about 3 millimeters to about 5 millimeters), felted and compressed reticulated foam (preferably having a thickness in a range of about 2 millimeters to about 4 millimeters), combinations of foam and textiles (such as various textiles manufactured by Milliken &amp; Company), or coated or treated foam (such as plasma treated). Additionally or alternatively, the spacer layer  1805  may comprise or consist essentially of a low-profile 3D polyester textile, such as textiles manufactured by Baltex. 
       FIG. 19A  is a schematic view of an example configuration of fluid pathways in the bridge  160  of  FIG. 18  as assembled.  FIG. 19B  is a schematic view taken along line  19 B- 19 B, and  FIG. 19C  is a schematic view taken along line  19 C- 19 C. As illustrated in the examples of  FIG. 19B  and  FIG. 19C , the first wall  1105 , the second wall  1110 , the second layer  320 , and the third layer  1800  may cooperate to form the fourth fluid conductor  1127 . Thus, the fourth fluid conductor  1127  may be between the second layer  320  and the third layer  1800 . The spacer layer  1805  may support the fourth fluid conductor  1127  and may be configured to prevent or reduce collapse of the fourth fluid conductor  1127  upon the application of negative pressure. 
       FIG. 20  is an assembly view of another example of the bridge  160 . In the example of  FIG. 20 , the bridge  160  may comprise a spacer layer  2000  disposed between the first layer  315  and the third layer  1800 . The spacer layer  2000  may be formed of a variety of materials and configurations that are open to pressure and fluid flow, particularly in the form of air and exudate of varying viscosity. In some examples, the spacer layer  2000  may be hydrophobic to discourage collection and clotting of exudate, and should resist blocking under compression. Additionally or alternatively, anti-clotting agents may be bound to the spacer layer  2000 . In some embodiments, the spacer layer  2000  may be less hydrophobic than the spacer layer  1805 . Additionally or alternatively, the spacer layer  2000  may have a higher stiffness modulus than the spacer layer  1805 . Examples of materials suitable for some embodiments of the spacer layer  2000  may include reticulated foam (preferably having a thickness in a range of about 3 millimeters to about 8 millimeters), combinations of foam and textiles (such as various textiles manufactured by Milliken &amp; Company), or coated or treated foam (such as plasma treated). Additionally or alternatively, the spacer layer  2000  may comprise or consist essentially of a low-profile 3D polyester textile, such as textiles manufactured by Baltex. 
       FIG. 21  is an assembled section view of the bridge  160  of  FIG. 20 . For example, the first layer  315 , the second layer  320 , and the third layer  1800  may be welded or bonded together to form two longitudinal chambers that run the length of the bridge  160 . In the example of  FIG. 21 , edges of the first layer  315  and the second layer  320  are sealed to edges of the third layer  1800  to form the third fluid conductor  1125  and the fourth fluid conductor  1127  in a stacked relationship. The third layer  1800  is disposed between and fluidly separates the third fluid conductor  1125  and the fourth fluid conductor  1127 . The spacer layer  2000  is configured to support the third fluid conductor  1125 , separating a central portion of the first layer  315  and the third layer  1800 . The spacer layer  2000  may be configured to prevent or reduce collapse of the third fluid conductor  1125  upon the application of negative pressure. The spacer layer  1805  is configured to support the fourth fluid conductor  1127 , separating the second layer  320  and the third layer  1800 . The spacer layer  1805  may be configured to prevent or reduce collapse of the fourth fluid conductor  1127  upon the application of negative pressure. 
     In other examples, a fourth layer (not shown) may be integrated to form a third chamber configured to deliver instillation solution or pressure sensing. The fourth layer may be comprised of a material similar to either of the first layer  315 , the second layer  320 , or the third layer  1800 , for example. In some embodiments, the third chamber may have a volume that is less than the volume of the third fluid conductor  1125 , and may be less than half the volume of the third fluid conductor  1125  in some examples. 
     Alternatively, in some embodiments of the bridge  160 , the third fluid conductor  1125  and the fourth fluid conductor  1127  may be disposed side-by-side instead of in a stacked relationship. A side-by-side configuration may be assembled with only two film layers in some examples. 
       FIG. 22  is an assembly view of another example of the bridge  160 . In the example of  FIG. 20 , the bridge  160  may comprise the first layer  315 , the spacer layer  2000 , the third layer  1800 , the spacer layer  1600 , and the second layer  320  in a stacked relationship. For example, the spacer layer  2000  may be disposed between the first layer  315  and the third layer  1800 , and the spacer layer  1600  may be disposed between the third layer  1800  and the second layer  320 . 
       FIG. 23  is an assembly view of another example of the bridge  160 . In the example of  FIG. 23 , the second layer  320  may include a window  2300 . A panel  2305  may be coupled to the second layer  320  to cover the window  2300 . For example, the panel  2305  may be coupled to the second layer  320  by adhesives or welding. The panel  2305  may be a film having a high MVTR in some applications. For example, the MVTR may be at least 250 grams per square meter per twenty-four hours in some embodiments, measured using an upright cup technique according to ASTM E96/E96M Upright Cup Method at 38° C. and 10% relative humidity (RH). In some embodiments, an MVTR up to 5,000 grams per square meter per twenty-four hours may provide effective breathability and mechanical properties. In some embodiments, the panel  2305  may comprise or consist essentially of a polymer film, such as Inspire 2301 and Inpsire 2304 polyurethane films, commercially available from Expopack Advanced Coatings, Wrexham, United Kingdom. In some embodiments, the panel  2005  may comprise INSPIRE 2301 having an MVTR (upright cup technique) of 2600-2700 g/m 2 /24 hours and a thickness of about 30 microns. In some embodiments, the panel  2305  may comprise INSPIRE 2304 having an MVTR (upright cup technique) of 2600 g/m 2 /24 hours and a thickness of about 30 microns. The panel  2305  may be oriented to permit moisture-vapor transmission through the panel  2305  toward the first layer  315 . In embodiments where the panel  2305  is utilized, the second layer  320  need not comprise a material that has a high MVTR. Instead, the second layer  320  may comprise or consist essentially of a film having a higher thickness for durability. In some embodiments, the second layer  320  may comprise or consist essentially of a polyurethane film having a thickness of about 80 microns. 
       FIG. 24  is an assembly view of another example of the bridge  160 . In the example of  FIG. 24 , the bridge  160  may further include a moisture offloading layer  2400 . In some embodiments, the moisture offloading layer  2400  may be coupled to the second layer  320  opposite to the first layer  315 . In some embodiments, the second layer  320  may be coated with the moisture offloading layer  2400 . The moisture offloading layer  2400  may be configured to contact the tissue site for wicking fluids from the periwound. 
     The moisture offloading layer  2400  may comprise or consist essentially of a non-woven material such as, for example, a polyester non-woven material such as, for example, Libeltex TDL4. In some embodiments, other non-woven structures may be used such as, for example, Libeltex TDL2, or laminations with fiber or foam structures. Further, other materials may be used, such as a polyurethane film having a high MVTR that may provide for evaporation of condensate. In other embodiments, the moisture offloading layer  2400  may comprise or consist essentially of materials that are hydrophilic in nature such as, for example, gels and foams that may be used to provide wicking and/or evaporation. For example, such materials may include one or more the following materials: hydrophilic polyurethane; cellulosics; hydrophilic polyamides; polyvinyl alcohol; polyvinyl pyrrolidone; hydrophilic acrylics; hydrophilic silicone elastomers; a thin, uncoated polymer drape; natural rubbers; polyisoprene; styrene butadiene rubber; chloroprene rubber; polybutadiene; nitrile rubber; butyl rubber; ethylene propylene rubber; ethylene propylene diene monomer; chlorosulfonated polyethylene; polysulfide rubber; EVA film; co-polyester; silicones; a silicone drape; a 3M Tegaderm® drape; polyether block polyamide copolymer (PEBAX), for example, from Arkema, France; Expopack 2327; or other appropriate material. In some embodiments, the moisture offloading layer  2400  may comprise or consist essentially of Softesse 8801 commercially available from DuPont, Wilmington, Del. 
       FIG. 25  is a schematic view of the bridge  160  of  FIG. 14  applied to the tissue site  205 . The third fluid conductor  1125  has a first end  2500  and a second end  2505 . The fourth fluid conductor  1127  has a first end  2510  and a second end  2515 . The passage  1015  and the passage  1025  may be disposed proximate the first end  2500  of the third fluid conductor  1125 . The passage  1020  and the passage  1030  may be disposed proximate the first end  2500  of the third fluid conductor  1125 . The aperture  1040  may be disposed proximate the second end  2505  of the third fluid conductor  1125 . The aperture  1045  may be disposed proximate the first end  2510  of the fourth fluid conductor  1127 , and the aperture  355  may be disposed proximate the second end  2515  of the fourth fluid conductor  1127 . As further shown in  FIG. 25 , the aperture  1040  may fluidly couple the third fluid conductor  1125  to the fourth fluid conductor  1127 . The dressing  110  may be fluidly coupled to the third fluid conductor  1125  and the fourth fluid conductor  1127  through the aperture  1040  and the aperture  355 , respectively. The aperture  1045  may fluidly couple the fourth fluid conductor  1127  to the ambient environment. The hydrophobic filter  1050  may be disposed in the fourth fluid conductor  1127 . Additionally, the adapter  250  may be fluidly coupled to the third fluid conductor  1127  through the aperture  1015  and the aperture  1020 . The adapter  250  may also be fluidly coupled to the first fluid conductor  1115  and the second fluid conductor  1120  through the aperture  1025  and the aperture  1030 . The adapter  250  may be fluidly coupled with the negative-pressure source  105  by conduit  235   
     As further shown in  FIG. 25 , the tissue interface  120  may be in fluid communication with the recessed space  360  through the aperture  355 . The affixation surface  370  may be coupled to the cover  125  to seal and fluidly couple the recessed space  360  to the tissue interface  120 . The bridge  160  may extend over and cover a portion of the epidermal layer  220  surrounding the tissue site  205 , such as a periwound  2520 . Moisture may evaporate from the periwound  2520  and pass through the second layer  320  into the fourth fluid conductor  1127  as shown by arrows E. Upon the application of negative pressure to the bridge  160 , fluid can be drawn from the tissue site  205 , into the recessed space  360 , and through the third fluid conductor  1125 , from the second end  2505  to the first end  2500  of the third fluid conductor  1125  (as shown by arrow N). 
     Additionally upon the application of negative pressure to the bridge  160 , fluid is drawn from the ambient environment outside the bridge  160 , through the aperture  1045 , through the hydrophobic filter  1050 , into the first end  2510  of the fourth fluid conductor  1127 , through the fourth fluid conductor  1127 , and toward the aperture  1040  and the aperture  355  at the second end  2515  of the fourth fluid conductor  1127  (as shown by arrow L). In addition to fluid drawn into the fourth fluid conductor  1127  through the aperture  1040 , the evaporated moisture from the periwound  2520  that passed into the fourth fluid conductor  1127  through the second layer  320  is drawn through the fourth fluid conductor  1127  toward the aperture  1040 , through the third fluid conductor  1125  and into the adapter  250 . In some embodiments, moisture from the periwound  2520  that has not evaporated through second layer  320  may be drawn into the bridge  160  through the aperture  1045  and removed through the bridge  160 . The aperture  1045  may provide a controlled flow through which moisture from the periwound  2520  can be removed from the periwound  2520 . In some embodiments, the aperture  1045  may be dimensioned to provide a controlled flow in a range of about 25 cc/minute at −125 mmHg to about 250 cc/minute at −125 mmHg. 
     In embodiments with the hydrophobic filter  1050 , the hydrophobic filter  1050  can prevent contents from the tissue site  205  from leaking out of the aperture  1045 . Additionally, the hydrophobic filter  1050  can filter air going into the bridge  160  through the aperture  1045 . The hydrophobic filter  1050  can prevent contamination inside and outside of the bridge  160 . 
     The systems, apparatuses, and methods described herein may provide significant advantages. In some embodiments, the film construction of the first layer  315  and the second layer  315  may allow the bridge  160  to be conformable. In some embodiments, the bridge  160  may have a tensile stress at break of about 60 MPa, a tensile stress at 50% strain in a range of about 4 MPa to about 7 MPa, and a tensile strain at break (ultimate elongation) of about 540%. The bridge  160  may be sufficiently flexible to conform to the shape the tissue site  205 . The bridge  160  may be sufficiently flexible or sized so that the bridge  160  may be folded to conform to a tissue site  205  to provide optimal negative pressure to the tissue site  205 . When placed under a patient, the bridge  160  may also able to conform to the shape of the patient. The ability of the dressing  160  to conform may reduce discomfort to the patient and may reduce or eliminate occurrences of pressure sores if the patient sits or lies on the bridge  160 . 
     The periwound  2520  ideally provides a barrier to the tissue site  205 , which aids in protecting and confining the area of healing so that the tissue site  205  does not spread or increase in size. The periwound  2520  can become compromised when it is in excessive contact with moisture (e.g., wound fluid and/or sweat) for prolonged periods, which can cause the periwound  2520  to become soft or soggy and break down. This prolonged exposure of the periwound  2520  to moisture and the resulting deterioration of the epidermal layer  220  is defined as maceration. Maceration can negatively affect the healing progress of the tissue site  205  and can cause pain and/or discomfort to the patient. Some embodiments of the bridge  160  can reduce or eliminate maceration of the periwound  2520  that is proximate the bridge  160 . For example, the evaporation of moisture from the periwound  2520  through the second layer  320  and into the fourth fluid conductor  1127  can reduce the moisture level at the periwound  2520 , which can reduce maceration of the periwound  2520 . Additionally, the ability to have fluid flow into the aperture  1045  and through the fourth fluid conductor  1127  of the bridge  160  aids in removing the moisture in the fourth fluid conductor  1127  that evaporated from the periwound  2520 . The controlled flow provided by aperture  1045  may further remove moisture directly from the periwound  2520  and surrounding tissue and may bring dryer air to proximate the periwound  2520 , which may further reduce the risk or occurrence of maceration. That is, the fluid drawn into the aperture  1045  from the ambient environment can evaporate moisture on the periwound  2520 , surrounding tissue, or other surfaces between the bridge  160  and the patient. Reducing the risk or occurrence of maceration can improve patient comfort. 
     Additionally, some embodiments of the bridge  160  with the aperture  1045  may result in more consistent fluid removal from and negative-pressure delivery to the tissue site  205 . For example, the aperture  1045 , and the controlled flow provided by the aperture  1045 , may aid in providing smoother negative pressure delivery to the tissue site over the course of negative-pressure therapy, as well as keeping the fluid and exudates removed from the tissue site  205  moving through the bridge  160  and therapy system  100  by providing a consistent open pathway. The bridge  160  with the aperture  1045  may reduce the risk of blockage of the third fluid conductor  1125 . 
     While shown in a few illustrative embodiments, a person having ordinary skill in the art will recognize that the systems, apparatuses, and methods described herein are susceptible to various changes and modifications that fall within the scope of the appended claims. For example, in some embodiments, the bridge  160  may include a plurality of apertures along the length of the second layer  320 , creating a plurality of inlets into the fourth fluid conductor  1127 . 
     Moreover, descriptions of various alternatives using terms such as “or” do not require mutual exclusivity unless clearly required by the context, and the indefinite articles “a” or “an” do not limit the subject to a single instance unless clearly required by the context. Components may be also be combined or eliminated in various configurations for purposes of sale, manufacture, assembly, or use. For example, in some configurations the dressing  110 , the container  115 , or both may be eliminated or separated from other components for manufacture or sale. In other example configurations, the controller  130  may also be manufactured, configured, assembled, or sold independently of other components. 
     The appended claims set forth novel and inventive aspects of the subject matter described above, but the claims may also encompass additional subject matter not specifically recited in detail. For example, certain features, elements, or aspects may be omitted from the claims if not necessary to distinguish the novel and inventive features from what is already known to a person having ordinary skill in the art. Features, elements, and aspects described in the context of some embodiments may also be omitted, combined, or replaced by alternative features serving the same, equivalent, or similar purpose without departing from the scope of the invention defined by the appended claims.