Transparent peel and place dressing for negative-pressure therapy

Abstract

To provide a novel and useful system, a device, and a method for treating a tissue site in a negative pressure therapy environment.SOLUTION: A dressing for treating a tissue site with negative pressure may comprise a first polymer film having multiple fluid restriction parts, and a second polymer film comprising multiple standoffs disposed adjacent to the first polymer film. The first polymer film and the second polymer film may be substantially transparent to allow observation of the tissue site. In some embodiments, at least some of the standoffs may be offset from the fluid restriction parts. The second polymer film may comprise fluid passages adjacent to the standoffs in some examples.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention described in the appended claims generally relates to tissue treatment systems, and more particularly, but not limited to, transparent dressings for negative pressure therapy.

Background Art

[0002] Clinical studies and clinical practice have shown that reducing the pressure proximal to a tissue site can enhance and accelerate the growth of new tissue at that tissue site. Although there are many applications of this phenomenon, it has been found to be particularly advantageous for treating wounds. Whether it is a trauma, surgery, or another cause, regardless of the etiology of the wound, proper care of the wound is important for the outcome. Treatment by reducing the pressure on a wound or other tissue can generally be referred to as "negative pressure therapy", but is also known by other names including, for example, "negative pressure wound therapy", "decompression therapy", "vacuum therapy", "vacuum-assisted closure", and "local negative pressure". Negative pressure therapy can provide several benefits, including the migration of epithelial and subcutaneous tissues, improvement of blood flow, and micro-deformation of tissues at the wound site. Collectively, these benefits can promote the development of granulation tissue and shorten the healing time.

[0003] It is also widely accepted that cleaning of tissue sites can be very beneficial for the growth of new tissue. For example, a wound or cavity can be flushed with a liquid solution for therapeutic purposes. These actions are generally referred to as "irrigation" and "lavage", respectively. "Instillation" is another action that generally refers to the process of introducing a fluid into a tissue site at a low rate and leaving the fluid for a predetermined period before removing the fluid. For example, instillation of a topical treatment solution across a wound bed in combination with negative pressure therapy can further promote wound healing by relaxing soluble contaminants and removing infectious substances at the wound bed. As a result, the soluble bacterial load can be reduced, contaminants can be removed, and the wound can be cleaned.

[0004] The clinical benefits of negative pressure therapy and / or infusion therapy are well known, but improvements in treatment systems, components, and processes can benefit healthcare providers and patients.

Summary of the Invention

[0005] New and useful systems, devices, and methods for treating tissue sites in a negative pressure therapy environment are described in the appended claims. Exemplary embodiments are also provided that enable one of ordinary skill in the art to manufacture and use the claimed subject matter.

[0006] For example, in some embodiments, the dressing may comprise a thin, flexible, transparent manifold material that facilitates treatment using negative pressure and also enables observation of the tissue site during treatment. In some examples, the dressing may comprise a laminated structure having a transparent manifolding means and a fenestrated interface layer. Additionally or alternatively, the interface layer may be embossed or textured to provide two or more manifolding layers and means for imparting micro-strain to the tissue site. In some embodiments, the structure may be joined or fused together by various means including the use of adhesives, welding, or heat adhesion where heat is applied together to the frame laminate layers.

[0007] In some embodiments, the manifold material may be formed from a polyurethane film that is vacuum formed with an array of standoffs. The spacing between the standoffs may vary and may be increased to promote branching and light transmissivity. Additionally or alternatively, the material between the standoffs may be perforated in some instances. For example, in some embodiments, small holes (about 1 millimeter) can be formed in the material by a thermal perforation process. In other instances, a few large perforations may be formed. The dressing may further include a fluid-impermeable cover having an opening or fluid port, and a spacer material may be disposed between the manifold material and the cover to prevent the manifold material from being drawn into or pushed into the opening or fluid port during treatment.

[0008] Some examples may further include a fully or partially light-occlusive, highly breathable polyurethane or other film cover that can be removed to observe the tissue site through the dressing. For example, a screen layer may be assembled to the top cover and may be coated with a resealable adhesive, such as a pattern-coated silicone or polyurethane gel, that is highly breathable and can be removed and repositioned as desired to observe the tissue site through the other layers.

[0009] In some embodiments, the dressing may further include other materials that may be beneficial for binding proteins and / or bacteria. For example, the primary interface layer may be made of a material such as polyurethane that may be less likely to bind proteins, and the primary manifold layer may be made of or coated with a material that can bind and retain bacteria.

[0010] More generally, a dressing for treating a tissue site using negative pressure may comprise a first polymer film having a plurality of fluid restriction portions and a second polymer film including a plurality of standoffs disposed adjacent to the first polymer film. The first polymer film and the second polymer film may be substantially transparent to enable observation of the tissue site. In some embodiments, at least a portion of the standoffs may be offset from the fluid restriction portions. The second polymer film may include, in some examples, a fluid passage adjacent to the standoffs.

[0011] Alternatively, other exemplary embodiments may include a cover and a tissue interface, the tissue interface including a first layer, a second layer, and a third layer. The first layer may include a plurality of standoffs and at least one fluid passage. The second layer may include a plurality of fluid restriction portions. The third layer may include a plurality of apertures and, in some examples, treatment apertures. The cover, the first layer, the second layer, and the third layer may be assembled in an overlapping relationship with the first layer and the second layer disposed between the cover and the third layer. At least a portion of the fluid restriction portions may be exposed through the treatment apertures, and the cover may have an aperture fluidly coupled to at least one fluid passage of the first layer. The standoffs may be disposed adjacent to the second layer. In some examples, the treatment apertures may form a frame around at least a portion of the fluid restriction portions. The cover, the first layer, the second layer, and the third layer may be substantially transparent in some embodiments. A spacer may be disposed between the aperture of the cover and the first layer. Additionally or alternatively, a visually occlusive screen may be removably disposed on the cover. In some examples, the cover and the third layer may surround the first layer and the second layer. In other examples, the first layer and the second layer may have an exposed outer periphery.

[0012] The objects, advantages, and preferred aspects of the claimed subject matter are best understood by reference to the following detailed description of exemplary embodiments in conjunction with the accompanying drawings.

Brief Description of the Drawings

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[0024] The following description of the exemplary embodiments provides information that enables one skilled in the art to make and use the subject matter recited in the appended claims, but may omit certain details that are already well known in the art. Accordingly, the following detailed description should be construed as illustrative and not restrictive.

[0025] Exemplary embodiments may also be described herein with reference to spatial relationships between various elements shown in the accompanying drawings or the spatial orientation of various elements. Generally, such relationships or orientations assume a reference system that is aligned with or relative to a patient in the position being treated. However, as will be appreciated by those skilled in the art, this reference system is not a strict definition and is merely for convenience of explanation.

[0026] FIG. 1 is a simplified functional block diagram of an exemplary embodiment of a treatment system 100 that can provide negative pressure therapy with infusion of a topical treatment solution to a tissue site, according to the present disclosure.

[0027] As used herein, the term "tissue site" broadly refers to a wound, defect, or other treatment target located on or within a tissue, including, but not limited to, bone tissue, adipose tissue, muscle tissue, nerve tissue, dermal tissue, vascular tissue, connective tissue, cartilage, tendon, or ligament. Wounds can include, for example, chronic, acute, traumatic, subacute, and lacerated wounds, partial thickness burns, ulcers (such as diabetic ulcers, pressure ulcers, or venous insufficiency ulcers), flap wounds, and grafted tissue. The term "tissue site" may also refer to any region of tissue where it may be desirable to add or promote the growth of additional tissue, rather than necessarily at the site of a wound or defect. For example, negative pressure can be applied to a tissue site to grow additional tissue that can be harvested and transplanted.

[0028] Therapy system 100 can include a source or supply of negative pressure, such as negative pressure source 105, and one or more distribution components. The distribution components can preferably be detachable and can be made disposable, reusable, or recyclable. Dressings, such as dressing 110, and fluid containers, such as container 115, are examples of distribution components that can be associated with some embodiments of therapy system 100. As shown in the embodiment of FIG. 1, dressing 110 can comprise, consist essentially of, or consist of tissue interface 120, cover 125, or both in some embodiments.

[0029] A fluid conduit is another exemplary embodiment of a distribution component. In this context, a "fluid conduit" broadly encompasses tubes, pipes, hoses, ducts, or other structures having one or more lumens or open pathways adapted to convey fluid between two ends. Typically, a tube is an elongated cylindrical structure having some flexibility, although the geometric shape and rigidity can vary. Further, some fluid conduits may be formed into or otherwise integrally combined with other components. The distribution component may also include or be provided with an interface or fluid port to facilitate the connection and disconnection of other components. In some embodiments, for example, a dressing interface may facilitate coupling a fluid conduit to a dressing 110. For example, such a dressing interface can be a SENSAT.R.A.C (trademark) Pad available from Kinetic Concepts, Inc. (San Antonio, Texas).

[0030] The therapy system 100 may also include a regulator or controller, such as controller 130. Further, the therapy system 100 may include sensors for measuring operating parameters and providing a feedback signal indicative of the operating parameters to the controller 130. For example, as shown in FIG. 1, the therapy system 100 may include a first sensor 135 and a second sensor 140 coupled to the controller 130.

[0031] Treatment system 100 may also include a source of infusion solution. For example, solution source 145 may be fluidly coupled to dressing 110 as shown in the exemplary embodiment of FIG. 1. Solution source 145 may be fluidly coupled in some embodiments to a positive pressure source such as positive pressure source 150, a negative pressure source such as negative pressure source 105, or both. A regulator such as drip regulator 155 may also be fluidly coupled to solution source 145 and dressing 110 to ensure an appropriate dosage of infusion solution (e.g., saline) to the tissue site. For example, drip regulator 155 may include a piston that is pneumatically actuated by negative pressure source 105 to aspirate infusion solution from the solution source during the negative pressure interval and inject the solution into the dressing during the ventilation interval. Additionally or alternatively, controller 130 may be coupled to negative pressure source 105, positive pressure source 150, or both to control the dosage of infusion solution to the tissue site. In some embodiments, as shown in the example of FIG. 1, drip regulator 155 may also be fluidly coupled to negative pressure source 105 via dressing 110.

[0032] Some components of treatment system 100 may be housed within or used in conjunction with other components such as sensors, processing units, alarm indicators, memories, databases, software, display devices, or user interfaces that further facilitate treatment. For example, in some embodiments, negative pressure source 105 can be combined with controller 130, solution source 145, and other components to form a treatment unit.

[0033] Generally, the components of the therapy system 100 can be coupled directly or indirectly. For example, the negative pressure source 105 can be directly coupled to the container 115 and can also be indirectly coupled to the dressing 110 via the container 115. The couplings can include fluid couplings, mechanical couplings, thermal couplings, electrical couplings, or chemical couplings (such as chemical bonds), or, depending on the context, some combinations of couplings. For example, the negative pressure source 105 can be electrically coupled to the controller 130 and fluidly coupled to one or more distribution components to provide a fluid path to the tissue site. In some embodiments, the components may also be coupled by physical proximity, integrated into a single structure, or formed from the same piece of material.

[0034] A negative pressure supply, such as the negative pressure source 105, can be a reservoir of negative pressure air or, for example, a manual or electric device such as a vacuum pump, a suction pump, a wall suction port available in many medical facilities, or a micropump. "Negative pressure" generally refers to a pressure that is lower than a local ambient pressure, such as the ambient pressure in the local environment external to the sealed treatment environment. In many cases, the local ambient pressure can also be the atmospheric pressure at which the tissue site is located. Alternatively, this pressure may be lower than the hydrostatic pressure associated with the tissue at the tissue site. Unless otherwise indicated, the pressure values described herein are gauge pressures. References to an increase in negative pressure typically refer to a decrease in absolute pressure, while a decrease in negative pressure typically refers to an increase in absolute pressure. The amount and nature of the negative pressure provided by the negative pressure source 105 can vary depending on the treatment requirements, but the pressure is generally a low vacuum, generally also referred to as a rough vacuum, in the range of -5 mmHg (-667 Pa) to -500 mmHg (-66.7 kPa). A typical treatment range is -50 mmHg (-6.7 kPa) to -300 mmHg (-39.9 kPa).

[0035] Container 115 represents a container, canister, pouch, or other storage component that can be used to manage exudate and other fluids withdrawn from the tissue site. In many environments, a rigid container may be preferred or required for fluid collection, storage, and disposal. In other environments, the fluid can be properly disposed of without storage in a rigid container. Some containers may be reusable, thereby reducing the waste and costs associated with negative pressure therapy.

[0036] A controller, such as controller 130, may be a microprocessor or computer programmed to operate one or more components of the treatment system 100, such as the negative pressure source 105. In some embodiments, for example, controller 130 may be a microcontroller, which generally includes an integrated circuit including a processor core and a memory programmed to directly or indirectly control one or more operating parameters of the treatment system 100. Examples of operating parameters can include, for example, 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. Controller 130 is also preferably configured to receive one or more input signals, such as feedback signals, and is programmed to modify one or more operating parameters based on those input signals.

[0037] Sensors such as the first sensor 135 and the second sensor 140 are generally known in the art as any device operable to detect or measure a physical phenomenon or property, and generally provide a signal indicative of the detected or measured phenomenon or property. For example, the first sensor 135 and the second sensor 140 can be configured to measure one or more operating parameters of the therapy system 100. In some embodiments, the first sensor 135 can be a transducer configured to measure the pressure within the pneumatic pathway and convert the measurement into a signal indicative of the measured pressure. In some embodiments, for example, the first sensor 135 can be a piezoresistive strain gauge. The second sensor 140 can optionally measure, in some embodiments, an operating parameter of the negative pressure source 105, such as a voltage or current. Preferably, the signals from the first sensor 135 and the second sensor 140 are suitable as input signals to the controller 130, although in some embodiments some signal conditioning may be appropriate. For example, the signals may need to be filtered or amplified before being processed by the controller 130. Typically, the signals are electrical signals, although they may be represented in other forms such as optical signals.

[0038] The tissue interface 120 can generally be adapted to contact the tissue site either partially or fully. The tissue interface 120 can take many forms and can have many sizes, shapes, or thicknesses depending on various factors such as the type of treatment being performed or the nature and size of the tissue site. For example, the size and shape of the tissue interface 120 can conform to the contour of a deep and irregularly shaped tissue site. Any or all of the surfaces of the tissue interface 120 can have a rough profile, a bumpy profile, or a jagged profile.

[0039] In some embodiments, the tissue interface 120 can include or consist essentially of a manifold. A manifold in this context can include or consist essentially of means for collecting or distributing fluid across the tissue interface 120 under pressure. For example, the manifold can be adapted to receive a negative pressure from a source and distribute the negative pressure across the tissue interface 120 via a plurality of apertures, which can have the effect of collecting fluid across the tissue site and drawing the fluid toward the source. In some embodiments, the fluid path can be reversed or a secondary fluid path can be provided to facilitate delivery of fluid, such as fluid from a source of drip solution, across the tissue site.

[0040] In some embodiments, the cover 125 can provide a barrier against bacteria and protection from physical trauma. The cover 125 can also be constructed from a material that can reduce evaporative losses and provide a fluid seal between two components or between two environments, such as between a treatment environment and a local external environment. The cover 125 can include or consist of, for example, an elastomeric film or membrane that can provide a suitable seal to maintain negative pressure at the tissue site with respect to a given negative pressure source. The cover 125 can have a high moisture vapor transmission rate (MVTR) in some applications. For example, the MVTR can be at least 250 grams per square meter per 24 hours, measured using the Upright Cup technique of ASTM E96 / E96M at 38 °C and relative humidity (RH) 10% in some embodiments. In some embodiments, an MVTR of up to 5,000 grams per square meter per 24 hours can provide effective breathability and mechanical properties.

[0041] In some exemplary embodiments, the cover 125 can be a drape or film made of a non-porous polymer such as a polyurethane film that allows water vapor to pass through but not liquid. Such a drape typically has a thickness in the range of 25 to 50 microns. For a permeable material, the permeability should generally be low enough to be able to maintain the desired negative pressure. The cover 125 can include, for example, one or more of the following materials: polyurethanes (PU) such as hydrophilic polyurethanes, cellulose derivatives, hydrophilic polyamides, polyvinyl alcohol, polyvinyl pyrrolidone, hydrophilic acrylates, silicones such as hydrophilic silicone elastomers, natural rubber, 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), copolyesters, and polyether block polyimide copolymers. Such materials are commercially available, for example, as Tegaderm® drapes from 3M Company (Minneapolis Minnesota); polyurethane (PU) drapes from Avery Dennison Corporation (Pasadena, California); polyether block polyamide copolymers (PEBAX) such as those made by Arkema S.A. (Colombes, France); and Inspire 2301 and Inspire 2327 polyurethane films from Expopack Advanced Coatings (Wrexham, United Kingdom). In some embodiments, the cover 125 can include Inspire 2301, which has an MVTR (upright cup technique) of 2600 g / m 2 24 hours and a thickness of about 30 microns.

[0042] The attachment device can be used to attach the cover 125 to an attachment surface such as an intact epidermis, gasket, or another cover. The attachment device can take many forms. For example, the attachment device can be a medically acceptable pressure-sensitive adhesive configured to bond the cover 125 to the epidermis around the tissue site. In some embodiments, for example, part or all of the cover 125 can be coated with an adhesive such as an acrylic adhesive that can have a coating weight of about 25 to 65 grams per square meter (g.s.m.). In some embodiments, a thicker adhesive, or combination of adhesives, can be applied to improve sealing and reduce leakage. Other exemplary embodiments of the attachment device can include double-sided tape, glue, hydrocolloid, hydrogel, silicone gel, or organogel.

[0043] The solution source 145 can also represent a container, canister, pouch, bag, or other storage component that can provide a solution for infusion therapy. The composition of the solution can vary according to a given treatment, but examples of solutions that can be suitable for some formulations can include hypochlorite-based solutions, silver nitrate (0.5%), sulfur-based solutions, biguanides, cationic solutions, and isotonic solutions.

[0044] During operation, the tissue interface 120 can be placed within, on top of, over, or proximal to the tissue site in other ways. For example, if the tissue site is a wound, the tissue interface 120 can partially or completely occlude the wound or can be placed over the wound. The cover 125 can be placed over the tissue interface 120 and sealed to an attachment surface in the vicinity of the tissue site. For example, the cover 125 can be sealed to the intact epidermis surrounding the tissue site. Therefore, the dressing 110 can provide a sealed treatment environment in proximity to the tissue site that is substantially isolated from the external environment, and the negative pressure source 105 can reduce the pressure in the sealed treatment environment.

[0045] The hydrodynamics of using a negative pressure source to reduce pressure at another component or location, such as within a closed therapy environment, can be mathematically complex. However, the basic principles of hydrodynamics applicable to negative pressure therapy and infusion are generally well-known to those skilled in the art, and the process of reducing pressure can be illustratively described herein, for example, as "delivering", "distributing", or "generating" negative pressure.

[0046] Generally, exudate and other types of fluids flow along the fluid path towards the lower pressure. Thus, the term "downstream" typically means within the fluid path that is relatively closer to the negative pressure source or farther away from the positive pressure source. Conversely, the term "upstream" means relatively farther away from the negative pressure source or closer to the positive pressure source. Similarly, it may be convenient to describe certain features from the perspective of the "inlet" or "outlet" of the fluid in such a reference system. This orientation is generally assumed for the purpose of describing the various features and components herein. However, the fluid path can also be reversed in some applications, for example, by replacing the negative pressure source with a positive pressure source, and this descriptive stipulation should not be construed as a limiting stipulation.

[0047] In a sealed treatment environment, the negative pressure applied across the tissue site via the tissue interface 120 can induce macro and micro strains at the tissue site. The negative pressure can also remove exudate and other fluids from the tissue site and collect them within the container 115.

[0048] In some embodiments, the controller 130 can receive and process data from one or more sensors, such as the first sensor 135. The controller 130 can also control the operation of one or more components of the treatment system 100 to manage the pressure delivered to the tissue interface 120. In some embodiments, the controller 130 can include an input for receiving a desired target pressure and can be programmed to process data regarding the setting and input of the target pressure that is to be applied to the tissue interface 120. In some exemplary embodiments, the target pressure can be set by an operator as a desired target negative pressure for treatment at the tissue site and then provided as an input to the controller 130 as a fixed pressure value. The target pressure can vary from tissue site to tissue site based on the type of tissue forming the tissue site, the type of injury or wound (if any), the patient's medical condition, and the preference of the attending physician. After selecting the desired target pressure, the controller 130 can operate the negative pressure source 105 in one or more control modes based on that target pressure and can receive feedback from one or more sensors to maintain the target pressure at the tissue interface 120.

[0049] In some embodiments, the controller 130 can have a continuous pressure mode, in which the negative pressure source 105 is operated to provide a constant target negative pressure during the treatment period or until manually stopped. Additionally or alternatively, the controller can have an intermittent pressure mode. For example, the controller 130 can operate the negative pressure source 105 to cycle between the target pressure and atmospheric pressure. For example, the target pressure can be set to a value of 135 mmHg for a specified period (e.g., 5 minutes), followed by a specified period (e.g., 2 minutes) of inactivity. This cycle can be repeated by operating the negative pressure source 105 to form a rectangular wave pattern between the target pressure and atmospheric pressure.

[0050] In some exemplary 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. The initial rise time may vary depending on the type of dressing and treatment device being used. For example, the initial rise time for a particular treatment system can range from about 20 to 30 mmHg / second, and for another treatment system, it can range from about 5 to 10 mmHg / second. When the treatment system 100 is operating in intermittent mode, the repeated rise time can be a value substantially equal to the initial rise time.

[0051] In some exemplary dynamic pressure control modes, the target pressure can change over time. For example, the target pressure can change in the form of a triangular waveform that varies between a negative pressure of 50 - 135 mmHg with a rise time set at a rate of +25 mmHg / minute and a fall time set at -25 mmHg / minute. In other embodiments of the treatment system 100, the triangular waveform can vary between a negative pressure of 25 - 135 mmHg with a rise time set at a rate of +30 mmHg / minute and a fall time set at -30 mmHg / minute.

[0052] In some embodiments, the controller 130 can control or determine a variable target pressure in the dynamic pressure mode, and this variable target pressure can vary between a maximum pressure value and a minimum pressure value that can be set as an input defined by the operator as a desired range of negative pressure. The variable target pressure can also be processed and controlled by the controller 130, and the controller can change the target pressure according to a predetermined waveform such as a triangular waveform, a sine waveform, or a sawtooth waveform. In some embodiments, the waveform can be set by the operator as a negative pressure that changes with a predetermined negative pressure or time desired for the treatment.

[0053] In some embodiments, the controller 130 can receive and process data such as data related to the infusion solution supplied to the tissue interface 120. Such data can include the type of infusion solution prescribed by a clinician, the volume of fluid or solution to be infused into the tissue site (the "fill volume"), and the time prescribed to leave solution in the tissue site before applying negative pressure to the tissue site (the "dwell time"). The fill volume can be, for example, 10 to 500 mL, and the dwell time can be 1 second to 30 minutes. The controller 130 can also control the operation of one or more components of the treatment system 100 to inject the solution. For example, the controller 130 can manage the fluid dispensed from the solution source 145 to the tissue interface 120. In some embodiments, the fluid can be injected into the tissue site by applying negative pressure from the negative pressure source 105 to reduce the pressure at the tissue site and suction the solution into the tissue interface 120. In some embodiments, the solution can be injected into the tissue site by applying positive pressure from the positive pressure source 150 to move the solution from the solution source 145 to the tissue interface 120. Additionally or alternatively, the solution source 145 can be raised to a height sufficient to allow gravity to move the solution to the tissue interface 120.

[0054] The controller 130 can also control the fluid dynamics of the drip infusion by providing a continuous flow of the solution or an intermittent flow of the solution. A negative pressure can be applied to provide either a continuous flow or an intermittent flow of the solution. The application of the negative pressure may be implemented to provide a continuous pressure operation mode to achieve a continuous flow rate of the drip solution through the tissue interface 120, or to provide a dynamic pressure operation mode to vary the flow rate of the drip solution through the tissue interface 120. Alternatively, the application of the negative pressure may be implemented to provide an intermittent operation mode to allow the drip solution to dwell at the tissue interface 120. In the intermittent mode, for example, a specific fill volume and dwell time can be provided depending on the type of the tissue site being treated and the type of dressing being used. Negative pressure treatment can be performed after or during the infusion of the solution. Before starting another drip infusion cycle, the controller 130 can be utilized to select the operation mode and the duration of the negative pressure treatment.

[0055] Figure 2 is an assembled view of an example of the dressing 110 of FIG. 1 and shows further details that may be relevant to some embodiments in which the tissue interface 120 includes two or more layers. In the example of FIG. 2, the tissue interface 120 includes a first layer 205, a second layer 210, and a third layer 215. In some embodiments, the first layer 205 may be disposed adjacent to the second layer 210, and the third layer 215 may also be disposed adjacent to the second layer 210 on the side opposite the first layer 205. For example, the first layer 205 and the second layer 210 may be overlapped such that the first layer 205 contacts the second layer 210. The first layer 205 may also be joined to the second layer 210 in some embodiments. In some embodiments, the second layer 210 may have the same extent as the surface of the first layer 205. In some embodiments, at least a portion of the third layer 215 may be joined to the second layer 210. The cover 125, the first layer 205, the second layer 210, and the third layer 215 may be substantially transparent or translucent in some examples. For example, a transmittance of at least 80% for white light may be suitable for some embodiments.

[0056] The first layer 205 generally includes, or consists essentially of, a manifold or manifold layer that provides means for collecting or distributing fluid across the tissue interface 120 under pressure. For example, the first layer 205 may be adapted to receive a negative pressure from a source and distribute the negative pressure across the tissue interface 120 by a plurality of paths, thereby having the effect of collecting fluid from the entire tissue site and drawing it toward the source. In some embodiments, the fluid path may be reversed, or a secondary fluid path may be provided to facilitate delivery of fluid across the tissue interface 120 from a source such as a drip solution source.

[0057] In some exemplary embodiments, the paths of the first layer 205 may be interconnected to improve fluid distribution or collection. In some embodiments, the first layer 205 may include, or consist essentially of, a film of a fluid-impermeable material having standoffs 220. Polyurethane is an example of a fluid-impermeable material suitable for some uses of the first layer 205. In some embodiments, the standoffs 220 may include a plurality of raised formations extending above or below the plane of the first layer 205. Each of the standoffs 220 may have an empty cavity therein that may be open to the surrounding environment. For example, portions of the film of the fluid-impermeable material forming the first layer 205 may be shaped or formed into the standoffs 220. In some embodiments, the standoffs 220 may be in the form of vacuum-formed small regions of the film of the first layer 205. In some embodiments, the standoffs 220 may each have a domed or hemispherical profile. Additionally or alternatively, the standoffs 220 may be in the form of raised blisters, bubbles, cells, bosses, or other formations having different shapes such as flat or hemispherical ends, or generally conical, cylindrical, tubular, etc. shapes having geodesic lines. The first layer 205 may further include at least one fluid passage, such as an opening 225, that enables fluid transfer through the first layer 205.

[0058] The thickness of the first layer 205 may also vary depending on the needs of the prescribed therapy. For example, the thickness of the first layer 205 may be decreased to relieve stress on other layers and to reduce tension on surrounding tissues. The thickness of the first layer 205 can also affect the compliance of the first layer 205. In some embodiments, the first layer 205 may include a flexible or elastic film having a thickness in the range of about 20 to 500 microns, and the standoff 220 may have a diameter of 0.5 mm to 2.0 mm.

[0059] The second layer 210 may include or consist essentially of means for controlling or managing fluid flow. In some embodiments, the second layer 210 may be a fluid control layer that includes or consists essentially of a liquid-impermeable elastomeric material. For example, the second layer 210 may include or consist essentially of a flexible or elastic polymeric film such as a polyurethane film. In some embodiments, the second layer 210 may include or consist essentially of the same material as the cover 125.

[0060] In some embodiments, the second layer 210 may also have a smooth or matte surface texture. A finish with a gloss or shine of grade B3 or higher according to the SPI (Society of the Plastics Industry) standard may be particularly advantageous for some applications. In some embodiments, the surface height variations can be limited to an acceptable tolerance. For example, the surface of the second layer 210 may have a substantially flat surface with height variations limited to 0.2 millimeters per centimeter. A thickness of about 50 microns to about 100 microns may be suitable for some examples.

[0061] In some embodiments, the second layer 210 may be embossed, thereby creating a pattern of contact areas having a multi-branching effect. Examples of suitable patterns include tufted, diamond, and woven patterns. Examples of materials suitable for embossing include polyurethane, polyethylene, polypropylene, polyamide, and their copolymers. A thickness of from about 200 microns to about 300 microns may be suitable in some examples.

[0062] In some embodiments, the second layer 210 may be hydrophobic. The hydrophobicity of the second layer 210 can be diverse. In some embodiments, the contact angle with water may be at least 90 degrees. In some embodiments, the second layer 210 may have a contact angle with water of 150 degrees or less. For example, in some embodiments, the contact angle of the second layer 210 may be in the range of at least 90 degrees to about 120 degrees, or at least 120 degrees to 150 degrees. The water contact angle can be measured using any standard device. A manual goniometer can be used to visually approximate the contact angle. In particular, a contact angle measuring device often includes an integrated system that includes a horizontal stage, a liquid dropper such as a syringe, a camera, and software designed to calculate the contact angle more accurately and precisely. Non-limiting examples of such integrated systems include the FTÅ125, FTÅ200, FTÅ2000, and FTÅ4000 systems, all commercially available from First Ten Angstroms, Inc. (Portsmouth, VA), and the DTA25, DTA30, and DTA100 systems, all commercially available from Kruss GmbH (Hamburg, Germany). Unless otherwise specified, the water contact angle herein is measured using deionized distilled water on a horizontal sample surface for a droplet added from a height of 5 cm or less in air at 20 - 25°C and a relative humidity of 20 - 50%. The contact angle herein represents the average of 5 - 9 measurements, excluding both the highest and lowest measured values. The hydrophobicity of the second layer 210 may be further enhanced by a hydrophobic coating of other materials such as silicone or fluorocarbon during coating with either a liquid or plasma.

[0063] The second layer 210 may also be suitable for welding to other layers including the first layer 205. For example, the second layer 210 may be adapted to weld to the polyurethane foam using heat, radio frequency (RF) welding, or other methods of generating heat such as ultrasonic welding. RF welding may be particularly suitable for more polar materials such as polyurethanes, polyamides, polyesters, and acrylates. A sacrificial polar interface can be used to facilitate RF welding of less polar film materials such as polyethylene.

[0064] The areal density of the second layer 210 may vary depending on the therapy or application being prescribed. In some embodiments, an areal density of less than 40 grams per square meter may be suitable, and for some applications, an areal density of about 20 - 30 grams per square meter may be particularly advantageous.

[0065] In some embodiments, for example, the second layer 210 may include or may consist essentially of a hydrophobic polymer such as a polyethylene film. The simple and inert structure of polyethylene can provide a surface that promotes free flow of liquids and low adhesion by providing a surface that interacts little, if at all, with living tissues and fluids, which can be particularly advantageous for many applications. Other suitable polymer films include polyurethane, acrylic, polyolefin (such as cyclic olefin copolymer), polyacetate, polyamide, polyester, copolyester, PEBAX block copolymer, thermoplastic elastomer, thermoplastic vulcanizate, polyether, polyvinyl alcohol, polypropylene, polymethylpentene, polycarbonate, styrenic, silicone, fluoropolymer, and acetate. A thickness of 20 microns to 100 microns may be suitable for many applications. The film can be transparent, colored, or printed. More polar films suitable for laminating to a polyethylene film include polyamide, copolyester, ionomer, and acrylic. A tie layer such as ethylene vinyl acetate or modified polyurethane can be used to assist in bonding the polyethylene to the polar film. Ethyl methyl acrylate (EMA) film may also have suitable hydrophobic and welding properties for some configurations.

[0066] As shown in the example of FIG. 2, the second layer 210 may have one or more fluid restriction portions 230 that may be distributed uniformly or randomly across the second layer 210. The fluid restriction portions 230 may be bidirectional and pressure-responsive. For example, each of the fluid restriction portions 230 may generally include, or consist essentially of, an elastic passageway that is normally not tense and substantially reduces liquid flow, and that may expand or open in response to a pressure gradient. In some embodiments, the fluid restriction portions 230 may include, or consist essentially of, perforations in the second layer 210. The perforations may be formed by removing material from the second layer 210. For example, the perforations may be formed by cutting through the second layer 210, and in some embodiments, the edges of the perforations may be deformed. In the absence of a pressure gradient across the perforations, these passageways may be small enough to form a seal or fluid restriction capable of substantially reducing or preventing liquid flow. Additionally or alternatively, one or more of the fluid restriction portions 230 may be an elastomeric valve that is normally closed when not tense to substantially prevent liquid flow and that may open in response to a pressure gradient. An aperture in the second layer 210 may be a valve suitable for some applications. An aperture is generally a special case of a perforation. An aperture may also be formed by removing material from the second layer 210, although the amount of material removed and the resulting dimensions of the aperture may be on the order of being no larger than a perforation, and the edges may not need to be deformed.

[0067] For example, the perforations may form slots in the second layer 210, and the apertures may form slits, which are generally a special case of slots. In some embodiments, the fluid restriction 230 may include, or consist essentially of, one or more slits, slots, or combinations of slits and slots in the second layer 210. In some examples, the fluid restriction 230 may include, or consist of, linear slots having a length of less than 4 millimeters and a width of less than 1 millimeter. The length may be at least 2 millimeters, and in some embodiments, the width may be at least 0.4 millimeters. A length of about 3 millimeters and a width of about 0.8 millimeters may be particularly suitable for many applications, and a tolerance of about 0.1 millimeter may also be acceptable. Such dimensions and tolerances can be achieved, for example, by a laser cutter. Slots of such a configuration can function as an imperfect valve that substantially reduces liquid flow in a normal closed or stationary state. For example, such slots may form a fluid restriction that is not completely closed or sealed. The slots can expand or open in response to a pressure gradient that increases liquid flow.

[0068] The third layer 215 may include, or consist essentially of, a sealing layer or a contact layer formed from a soft, conformable material such as a suitable gel material suitable for providing a fluid seal with the tissue site, and may have a substantially flat surface. For example, the third layer 215 may include, but is not limited to, silicone gel, soft silicone, hydrocolloid, hydrogel, polyurethane gel, polyolefin gel, hydrogenated styrene copolymer gel, foamed gel, soft closed-cell foams such as polyurethane and polyolefin coated with an adhesive, polyurethane, polyolefin, or hydrogenated styrene copolymer. In some embodiments, the third layer 215 may have a thickness of from about 200 microns (μm) to about 1000 microns (μm). In some embodiments, the third layer 215 may have a hardness of from about 5 Shore OO to about 80 Shore OO. Additionally, the third layer 215 can be composed of a hydrophobic or hydrophilic material.

[0069] In some embodiments, the third layer 215 can be made of a hydrophobic-coated material. For example, the third layer 215 can be formed by coating a material having gaps, such as a woven mesh, non-woven mesh, molded mesh, or extruded mesh, with a hydrophobic material. The hydrophobic material for coating can be, for example, soft silicone.

[0070] The third layer 215 may have an outer peripheral portion 235 around or surrounding the treatment opening 240 and an opening 245 of the outer peripheral portion 235 disposed around the treatment opening 240. The treatment opening 240 may, in some examples, be complementary to or correspond to the surface area of the first layer 205. For example, the treatment opening 240 may form a frame, window, or other hole around the surface of the first layer 205. The third layer 215 may also have corners 250 and edges 255. The corners 250 and edges 255 may be part of the outer peripheral portion 235. The third layer 215 may have an inner boundary portion 260 around the treatment opening 240 that does not substantially include the opening 245, as shown in the example of FIG. 2. In some examples, as shown in FIG. 2, the treatment opening 240 is symmetrically and centrally disposed with respect to the third layer 215 and may form an opening central window.

[0071] The opening 245 can be formed, for example, by cutting, perforation, by application of local RF or ultrasonic energy, or by other suitable techniques for forming holes or perforations in the third layer 215. The opening 245 may have a uniform distribution pattern or may be randomly distributed in the third layer 215. The openings 245 in the third layer 215 can have many shapes, such as circular, square, star-shaped, elliptical, polygonal, slit, complex curves, linear shapes, including triangles, or any combination of such shapes.

[0072] The openings 245 may each have uniform or similar geometric characteristics. For example, in some embodiments, the openings 245 may each be circular openings having substantially the same diameter. In some embodiments, the openings 245 may each have a diameter of from about 1 millimeter to about 50 millimeters. In other embodiments, the respective diameter of the openings 245 can be from about 1 millimeter to about 20 millimeters.

[0073] In other embodiments, the geometric characteristics of the openings 245 can be diverse. For example, the diameter of the openings 245 can vary according to the position of the openings 245 in the third layer 215. For example, in some embodiments, the openings 245 disposed at the outer peripheral portion 235 may have a diameter of from about 5 millimeters to about 10 millimeters. A range of from about 7 millimeters to about 9 millimeters may be suitable for some examples. In some embodiments, the openings 245 disposed at the corner portion 250 may have a diameter of from about 7 millimeters to about 8 millimeters.

[0074] At least one of the openings 245 in the outer peripheral portion 235 of the third layer 215 may be disposed at the edge 255 of the outer peripheral portion 235, open or exposed to the edge 255, and may have an inner cut portion that is in lateral fluid communication with the edge 255. The lateral direction may refer to the direction towards the edge 255 in the same plane as the third layer 215. As shown in the example of FIG. 2, the openings 245 in the outer peripheral portion 235 may be disposed adjacent to or at the edge 255 and may be in lateral fluid communication with the edge 255. The openings 245 disposed adjacent to or at the edge 255 may be disposed substantially equidistantly around the outer peripheral portion 235, as shown in the example of FIG. 2. Alternatively, the spacing between the openings 245 adjacent to or at the edge 255 may be irregular.

[0075] As shown in the example of FIG. 2, the dressing 110 may further include attachment means such as an adhesive 265. The adhesive 265 may be, for example, a medically acceptable pressure-sensitive adhesive that extends over the outer periphery, a part, or the entire surface of the cover 125. In some embodiments, for example, the adhesive 265 may be an acrylic adhesive having a coating weight of 25 to 65 grams per square meter (g.s.m.). In some embodiments, a thicker adhesive, or a combination of adhesives, may be applied to improve sealing and reduce leakage. In some embodiments, such a layer of the adhesive 265 may be continuous or discontinuous. The discontinuities of the adhesive 265 may be provided by openings or holes (not shown) in the adhesive 265. The openings or holes in the adhesive 265 may be formed after application of the adhesive 265 or by pattern coating the adhesive 265 onto the surface of a carrier layer, such as the cover 125. The openings or holes in the adhesive 265 may also be dimensioned in some exemplary embodiments to improve the MVTR of the dressing 110.

[0076] As shown in the example of FIG. 2, in some embodiments, the dressing 110 may include a release liner 270 for protecting the adhesive 265 prior to use. The release liner 270 may also provide rigidity, for example, to assist in the deployment of the dressing 110. The release liner 270 may be, for example, a cast paper, film, or polyethylene. Further, in some embodiments, the release liner 270 may be a polyester material such as polyethylene terephthalate (PET) or a similar polar semi-crystalline polymer. The use of a polar semi-crystalline polymer for the release liner 270 can substantially prevent wrinkles or other deformations of the dressing 110. For example, the polar semi-crystalline polymer may be highly oriented and resistant to softening, swelling, or other deformations that may occur when in contact with the components of the dressing 110, or when subjected to changes in temperature or environment, or when sterilized. Further, a release agent may be disposed on the surface of the release liner 270 configured to contact the second layer 210. For example, the release agent may be a silicone coating and may have a release factor suitable for facilitating the manual removal of the release liner 270 without damaging or deforming the dressing 110. In some embodiments, the release agent may be, for example, a fluorocarbon or fluorosilicone. In other embodiments, the release liner 270 may not be coated and may be used without a release agent in other ways.

[0077] The dressing 110 may further include a spacer manifold 275. In some embodiments, the spacer manifold 275 may have a structure similar to that of the first layer 205 having perforations between the standoffs. In other embodiments, the spacer manifold may include or consist essentially of a porous material having interconnected fluid pathways. Examples of suitable porous materials that can include or be adapted to form interconnected fluid pathways (e.g., channels) include cellular foams such as open-cell foams, including reticulated foams; porous tissue aggregates; and other porous materials such as gauze or felt mats that generally include pores, edges, and / or walls. Liquids, gels, and other foams can also include or be cured to include openings and fluid pathways. In some embodiments, the spacer manifold 275 may additionally or alternatively include protrusions that form interconnected fluid pathways. For example, in some instances, the spacer manifold 275 may be shaped to provide surface protrusions that define interconnected fluid pathways or may have standoffs similar or analogous to the standoffs 220.

[0078] In some embodiments, the spacer manifold 275 may comprise or consist essentially of an open-cell foam. For example, an open-cell foam having at least 90% free volume may be suitable for many applications, and a foam having an average pore size in the range of 400 - 600 microns may be particularly suitable for certain therapies. The tensile strength of the spacer manifold 275 may also vary. For example, the tensile strength of the foam may be increased for the dropping of the topical treatment solution. The 25% compression load deflection of the spacer manifold 275 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 spacer manifold 275 may be at least 10 pounds per square inch. The spacer manifold 275 may have a tear strength of at least 2.5 pounds per inch. In some embodiments, the spacer manifold 275 can be a foam composed of a polyol such as polyester or polyether, an isocyanate such as toluene diisocyanate, and a polymerization regulator such as an amine and a tin compound. In some examples, the spacer manifold 275 may be an open-cell polyurethane foam such as that used in GRANUFOAM™ dressing or V.A.C. VERAFLO™ dressing, both available from KCI (San Antonio, Texas).

[0079] Other materials suitable for the spacer manifold 275 may include non-woven fabrics (Libeltex, Freudenberg), three-dimensional (3D) polymer structures (molded polymers, embossed films, and heat-sealed films [Supracore]), and meshes.

[0080] In some examples, the spacer manifold 275 may include a three-dimensional fabric such as various fabrics commercially available from Baltex, Muller, and Heathcoates. A three-dimensional fabric of polyester fibers may be particularly advantageous in some embodiments. For example, the spacer manifold 275 may include or consist essentially of a three-dimensional weave of polyester fibers. In some embodiments, the fibers may be elastic in at least two dimensions. A puncture-resistant fabric made of polyester and cotton fibers having a weight of about 650 grams per square meter and a thickness of about 1-2 millimeters may be particularly advantageous in some embodiments. Such a puncture-resistant fabric may have a longitudinal tensile strength of about 330-340 kilograms and a transverse tensile strength of about 270-280 kilograms in some embodiments. Another particularly suitable material may be a polyester spacer fabric having a weight of about 470 grams per square meter and a thickness of about 4-5 millimeters in some embodiments. Such a spacer fabric may have a compression strength of about 20-25 kilopascals (when compressed by 40%).

[0081] FIG. 2 also shows an example of a fluid conduit 280 and a dressing interface 285. As shown in the example of FIG. 2, the fluid conduit 280 can be a flexible tube that can be fluidly coupled to the dressing interface 285 at one end. The dressing interface 285 can be an elbow connector that can provide a fluid path between the fluid conduit 280 and the tissue interface 120 by being disposed over the opening 290 of the cover 125 as shown in the example of FIG. 2. The dressing interface 285 may be larger than the opening 290 and may have the same spread as the spacer manifold 275 in some embodiments.

[0082] As shown in the example of FIG. 2, the opening 225, the spacer manifold 275, and the opening 290 may be aligned axially in some embodiments, and the spacer manifold 275 may be disposed between the opening 225 and the opening 290. The opening 225, the spacer manifold 275, and the opening 290 may have similar shapes in some embodiments. In other embodiments, the spacer manifold 275 may have a shape similar to that of the second layer 210. The spacer manifold 275 is preferably larger than the opening 225 and the opening 290. In some embodiments, the spacer manifold 275 may have a thickness in the range of about 0.5 millimeter to about 10 millimeters.

[0083] One or more of the components of the dressing 110 may be further treated with an antibacterial agent in some embodiments. For example, some embodiments of the first layer 205, the second layer 210, or both may be polymers coated with or mixed with an antibacterial agent. In other examples, the fluid conduit 280 may be treated with one or more antibacterial agents additionally or alternatively. Suitable antibacterial agents can include, for example, metallic silver, PHMB, iodine, or complexes thereof, and mixtures such as povidone iodine, copper metal compounds, chlorhexidine, or some combinations of these materials.

[0084] Additionally or alternatively, one or more of the components may be coated with a mixture that can reduce biofilms and infections and that may include citric acid and collagen. For example, the first layer 205 may be coated with such a mixture.

[0085] In some embodiments, the first layer 205 may be made of or coated with a material that can prevent the growth of bacteria and can bind to and hold bacteria.

[0086] Figure 3 is a top view of the assembled dressing 110 in the example of FIG. 2, showing further details that may be relevant to some embodiments. As shown in the example of FIG. 3, the cover 125 and the third layer 215 may have substantially the same outer peripheral shape and dimensions such that in some examples the cover 125 and the third layer 215 have the same extent. The first layer 205 may be centrally disposed on the third layer 215, such as above the treatment opening 240. The cover 125 may be disposed on the first layer 205 and the spacer manifold 275 with the opening 290 aligned over the spacer manifold 275.

[0087] The cover 125 may be substantially transparent and, in some embodiments, enables at least a portion of the opening 245 and the fluid restriction 230 to be visible. As shown in the example of FIG. 3, at least a portion of the fluid restriction 230 may be offset from the standoff 220. For example, the fluid restriction 230 may be aligned with the standoff 220 such that most of the fluid restriction 230 is not aligned with the standoff 220. In some embodiments, the standoff 220 may not be aligned with any of the fluid restrictions 230.

[0088] Figure 4 is a bottom view of the dressing 110 of FIG. 3, showing further details that may be relevant to some embodiments. The release liner 270 is removed in the example of FIG. 4. As shown in the example of FIG. 4, most of the fluid restriction 230 may be aligned with the treatment opening 240 or otherwise exposed through the treatment opening, and at least a portion of the first layer 205 may be disposed adjacent to the fluid restriction 230 on the side opposite the treatment opening 240. In some embodiments, the first layer 205 and the second layer 210 may be substantially aligned with the treatment opening 240 or may extend across the treatment opening 240.

[0089] Additionally, the first layer 205 may have a first edge 405, and the second layer 210 may have a second edge 410. In some examples, the first edge 405 and the second edge 410 may have substantially the same shape such that the adjacent faces of the first layer 205 and the second layer 210 are geometrically similar. The first edge 405 and the second edge 410 may also be congruent in some examples, and thus, the adjacent faces of the first layer 205 and the second layer 210 have substantially the same extent and substantially the same surface area. In the example of FIG. 4, the first edge 405 defines a larger face of the first layer 205 than the face of the second layer 210 defined by the second edge 410, and the larger face of the first layer 205 extends beyond the smaller face of the second edge 410.

[0090] The faces defined by the first edge 405, the second edge 410, or both may also be geometrically similar to the treatment aperture 240 and larger than the treatment aperture 240 in some embodiments, as shown in the example of FIG. 4. The third layer 215 may have a coating margin 415 around the treatment aperture 240 where additional adhesive may be disposed. As shown in the example of FIG. 4, the treatment aperture 240 may be elliptical or stadium-shaped in some embodiments. The treatment aperture 240 may have an area equal to about 20% to about 80% of the area of the region of the third layer 215 in some examples. The treatment aperture 240 may also have an area equal to about 20% to about 80% of the area of the face defined by the first edge 405 of the first layer 205. A width of about 90 millimeters to about 110 millimeters and a length of about 150 millimeters to about 160 millimeters may be suitable for some embodiments of the treatment aperture 240. For example, the width of the treatment aperture 240 may be about 100 millimeters and the length may be about 155 millimeters. In some embodiments, a suitable width of the coating margin 415 may be about 2 millimeters to about 3 millimeters. For example, the coating margin 415 may have the same extent as the region defined between the treatment aperture 240 and the first edge 405, and the adhesive may secure the first layer 205, the second layer 210, or both to the third layer 215.

[0091] FIG. 5 is a cross-sectional view of the dressing 110 of FIG. 3 along line 5-5, showing additional details that may be relevant to some embodiments. As shown in FIG. 5, the cover 125, the first layer 205, the second layer 210, the third layer 215, and the spacer manifold 275 may be assembled in an overlapping relationship. The cover 125 may be coupled to the third layer 215 around the first layer 205 and the second layer 210 such that the cover 125 and the third layer 215 substantially surround the first layer 205, the second layer 210, and the spacer manifold 275. The second layer 210 may be exposed through the treatment opening 240, and at least a portion of the adhesive 265 may be exposed through the opening 245.

[0092] The first layer 205 may be oriented such that the standoffs 220 are adjacent to the second layer 210, thereby creating a plurality of spaces 505 between the first layer 205 and the second layer 210. In some examples, the spaces 505 may form fluid pathways interconnected between the fluid restriction 230 and the opening 225. In the example of FIG. 5, the spacer manifold 275 is also disposed between the first layer 205 and the cover 125. As shown, the spacer manifold 275 may be disposed over the opening 225, thereby separating the cover 125 from the second layer 210 and providing additional fluid pathways.

[0093] As shown in the example of FIG. 5, some embodiments of the first layer 205 may be formed of a single sheet or film of a fluid-impermeable material on which the standoffs 220 may be formed. For example, the standoffs 220 may be formed in the first layer 205 by applying a vacuum to the film of the fluid-impermeable material of the first layer 205. The standoffs may have dimensions that depend on the particular use of the dressing 110. For example, the first layer 205 may include a film having a thickness of about 500 microns, and the standoffs may each have a height of about 1 millimeter to 4 millimeters. A width of about 1 millimeter to 4 millimeters may also be suitable in some embodiments. In some embodiments, the standoffs 220 may have dimensions of a height of about 3 millimeters and a diameter of about 3 millimeters. Additionally, the standoffs 220 may be distributed across the first layer 205 in a uniform grid or array having a pitch of about 3.5 millimeters to about 4 millimeters. A pitch of about 3.75 millimeters may be particularly suitable in some examples. The spacing may be varied, for example, to modify flow characteristics and permeability.

[0094] FIG. 6 is an assembly view of another example of the dressing 110 of FIG. 1 and shows further details that may be relevant to some embodiments. As shown in FIG. 6, some examples of the third layer 215 may not have the treatment aperture 240, and the apertures 245 may be distributed in a uniform pattern across the third layer 215.

[0095] FIG. 7 is a schematic diagram of an example of the second layer 210, showing further details that may be relevant to some embodiments. As shown in the example of FIG. 7, each of the fluid restriction portions 230 may consist essentially of one or more slits having a length L. A length of about 3 millimeters may be particularly suitable for some embodiments. FIG. 7 further shows an example of a uniform distribution pattern of the fluid restriction portions 230. In FIG. 7, the fluid restriction portions 230 have substantially the same spread as the second layer 210 and are distributed across the second layer 210 in a grid of parallel rows and columns, and the slits are also parallel to each other. In some embodiments, the rows may be spaced apart by a distance D1. A distance of about 3 millimeters at the center may be suitable for some embodiments. In some examples, the fluid restriction portions 230 within each column may be spaced apart by a distance D2, which may be about 3 millimeters at the center. In some embodiments, the fluid restriction portions 230 of adjacent columns may be aligned or offset. For example, adjacent columns may be offset as shown in FIG. 7, so that the fluid restriction portions 230 are aligned in alternating columns and are separated by a distance D3, which may be about 6 millimeters in some embodiments. The spacing of the fluid restriction portions 230 may vary in some embodiments so as to increase the density of the fluid restriction portions 230 according to the requirements of the therapy.

[0096] FIG. 8 is a schematic diagram of an exemplary configuration of the opening 245, showing further details that may be relevant to some embodiments of the third layer 215. In the example of FIG. 8, the opening 245 is generally circular and has a diameter D4 that may be about 6 millimeters to about 8 millimeters in some embodiments. A diameter D4 of about 7 millimeters may be particularly suitable for some embodiments. FIG. 8 also shows an example of a uniform distribution pattern of the openings 245. In FIG. 8, the openings 245 are distributed in a grid of parallel rows and columns. In each row and each column, the openings 245 may be equidistant from each other as shown in the example of FIG. 8. FIG. 8 shows one exemplary configuration that may be particularly suitable for many applications, where the openings 245 are spaced apart by a distance D5 along each row and each column having an offset D6. In some examples, the distance D5 may be about 9 millimeters to about 10 millimeters, and the offset D6 may be about 8 millimeters to about 9 millimeters.

[0097] FIG. 9 is a schematic diagram of an opening 245 configured in the example of FIG. 8 and overlaid on the second layer 210 of FIG. 7, showing further details that may be related to an exemplary embodiment of a portion of the tissue interface 120. For example, as shown in FIG. 9, two or more of the fluid restriction portions 230 may be aligned, overlaid, positioned, and fluidly coupled in other ways with the opening 245 in some embodiments. In some embodiments, one or more of the fluid restriction portions 230 may be only partially aligned with the opening 245. The opening 245 in the example of FIG. 9 is generally sized and configured such that at least four of the fluid restriction portions 230 are aligned with each one of the openings 245. In other examples, one or more of the fluid restriction portions 230 may be aligned with two or more of the openings 245. For example, any one or more of the fluid restriction portions 230 may be a perforation or an opening window extending across two or more of the openings 245. Additionally or alternatively, one or more of the fluid restriction portions 230 may not be aligned with any of the openings 245.

[0098] As shown in the example of FIG. 9, the opening 245 may be sized to expose a portion of the second layer 210, the fluid restriction portion 230, or both through the third layer 215. The opening 245 in the example of FIG. 9 is generally sized to expose two or more of the fluid restriction portions 230. A part or all of the opening 245 may be sized to expose two or three of the fluid restriction portions 230. In some examples, the respective length L of the fluid restriction portion 230 may be substantially smaller than the respective width W of the opening 245. More generally, the average dimension of the fluid restriction portion 230 is substantially smaller than the average dimension of the opening 245. In some examples, the opening 245 may be elliptical, and the respective length of the fluid restriction portion 230 may be substantially smaller than the major axis or the minor axis. However, in some embodiments, the dimension of the fluid restriction portion 230 may exceed the dimension of the opening 245, and the size of the opening 245 may limit the effective size of the fluid restriction portion 230 exposed on the lower surface of the dressing 110.

[0099] Figure 10 is an assembly diagram of another example of the dressing 110 of FIG. 1, showing further details that may be relevant to some embodiments. As shown in FIG. 10, some examples of the dressing 110 may not have a third layer 215. FIG. 10 also shows another example of the opening 225. In the example of FIG. 10, the opening 225 includes a main opening 1005 and one or more auxiliary openings 1010 around the main opening 1005. The main opening 1005 may be larger than the auxiliary openings 1010 in some embodiments. For example, the main opening 1005 of FIG. 10 may have a width of about 10 millimeters, and each of the auxiliary openings 1010 may have a width of about 3 millimeters.

[0100] Figure 11 is an assembly diagram of another example of the dressing 110 of FIG. 1, showing further details that may be relevant to some embodiments. In some embodiments, the first layer 205 includes a plurality of fluid passages in addition to or instead of the opening 225. As shown in FIG. 11, the fluid passages may include an opening 1105 adjacent to the standoff 220. In some examples, the opening 1105 may be formed in a portion between the standoffs 220 of the first layer 205 and may penetrate the first layer 205. The number of openings 1105 may vary depending on the type of application. The opening 1105 may have different shapes, such as circular, elliptical, rectangular, or other irregular shapes. The opening 1105 may have a width, diameter, major axis, or length of about 0.5 mm to 1.5 mm. A diameter of about 1 millimeter may be suitable for some embodiments. In some exemplary embodiments, the opening 1105 may be formed by cutting or thermal perforation of the first layer 205.

[0101] Additionally or alternatively, some embodiments of the dressing 110 may include a visual screen 1110 that can cover the tissue site from the patient's view and can be removed for diagnosis without disturbing the dressing 110. For example, a suitable screen may be opaque or may include or consist essentially of a highly breathable polymer film that is at least partially light-blocking. A visually occlusive polyurethane film may be suitable in some examples. In some embodiments, the visual screen is assembled to the cover 125 and may be coated with a resealable adhesive such as a patterned coating of silicone or polyurethane gel.

[0102] The individual components of the dressing 110 may be adhered to each other, for example, with a solvent or non-solvent adhesive, or by heat bonding, or fixed to each other in other ways, without adversely affecting fluid management. Further, the second layer 210 or the first layer 205 may be coupled to the inner boundary 260 or the coating margin 415 of the third layer 215 by any suitable method such as welding or an adhesive.

[0103] The cover 125, the first layer 205, the second layer 210, the third layer 215, the spacer manifold 275, or various combinations thereof may be assembled before application or in situ. For example, in some embodiments, the second layer 210 may be laminated to the first layer 205. The cover 125 may, in some embodiments, be disposed over the first layer 205 and coupled to the third layer 215 around the first layer 205. In some embodiments, one or more layers of the tissue interface 120 may be coextensive. For example, the second layer 210 may be cut flush with the edge of the first layer 205. In some embodiments, the dressing 110 may be provided as a composite dressing. For example, the third layer 215 may be coupled to the cover 125 so as to surround the first layer 205 and the second layer 210, and the third layer 215 may be configured to face the tissue site. In other examples, the first layer 205, the second layer 210, and the third layer 215 may have the same extent, and the respective edges may be exposed at the outer periphery of the tissue interface 120 to facilitate customization.

[0104] In use, the release liner 270 (if included) may be removed to expose the lower surface of the tissue interface 120. For example, in some embodiments, removing the release liner 270 may expose the third layer 215. In some embodiments, the tissue interface 120 may be cut or excised as appropriate. The tissue interface 120 can be placed within, on top of, at, or otherwise adjacent to the tissue site, particularly in the tissue site such as the surface tissue site and the adjacent epidermis. In some applications, the treatment aperture 240 of the third layer 215 may be placed adjacent to, proximate to, or covering the tissue site. In some applications, at least a portion of the second layer 210, the fluid restriction portion 230, or both may be exposed to the tissue site through the treatment aperture 240, the aperture 245, or both. The outer peripheral portion 235 of the third layer 215 may be placed adjacent to or proximate to the tissue around or surrounding the tissue site. The third layer 215 can be sufficiently adhesive to hold the dressing 110 in place, but at the same time can also allow the dressing 110 to be removed or repositioned without damaging the tissue site.

[0105] Removing the release liner 270 can also expose the adhesive 265, and the cover 125 can be attached to an attachment surface such as the outer peripheral portion 235 or other areas around the treatment aperture 240 and the first layer 205. The adhesive 265 may also be attached to the epidermis surrounding the tissue site around the first layer 205 and the second layer 210. For example, the adhesive 265 may be in fluid communication with the attachment surface through the aperture 245 at least at the outer peripheral portion 235 of the third layer 215. The adhesive 265 may also be in fluid communication with the edge 255 through the aperture 245 exposed at the edge 255.

[0106] Once the dressing 110 is in the desired position, the dressing 110 can be secured to the tissue site. In some embodiments, particularly when the tissue interface 120 is cut to a custom size or shape, a cover may be joined to the attachment surface around the edge of the tissue interface 120 to seal any exposed edges. Additionally or alternatively, in some embodiments, an adhesive 265 may be pressed through the aperture 245 to join the dressing 110 to the attachment surface. The aperture 245 in the edge 255 may enable the adhesive 265 to flow around the edge 255 to enhance the adhesion of the edge 255 to the attachment surface.

[0107] In some embodiments, the aperture 245 may be sized to control the amount of adhesive 265 that is exposed through the aperture 245. For a given geometry of the corner 250, the relative size of the aperture 245 may be configured to maximize the exposed surface area of the adhesive 265 that is in fluid communication through the aperture 245 at the corner 250. For example, the edges 255 may intersect at substantially right angles or at about 90 degrees to define the corner 250. In some embodiments, the corner 250 may have a radius of about 10 millimeters. Further, in some embodiments, three of the apertures 245 may be arranged in a triangular configuration at the corner 250 to maximize the exposed surface area of the adhesive 265. In other embodiments, the size and number of the apertures 245 at the corner 250 may be adjusted as needed according to the selected geometry of the corner 250 to maximize the exposed surface area of the adhesive 265. Further, the apertures 245 at the corner 250 may be completely contained within the third layer 215 to substantially eliminate lateral fluid communication outside of the corner 250. By completely containing the apertures 245 at the corner 250 within the third layer 215, fluid communication of the adhesive 265 outside of the corner 250 is substantially eliminated, and the handling of the dressing 110 during deployment at the tissue site can be improved. Further, by substantially excluding the adhesive 265 from the outside of the corner 250, the flexibility of the corner 250 can be improved to enhance comfort.

[0108] In some embodiments, the adhesive strength of the adhesive 265 may vary based on the composition of the third layer 215. For example, the adhesive strength may vary based on the size of the aperture 245. In some examples, the adhesive strength may be inversely proportional to the size of the aperture 245. Additionally or alternatively, the adhesive strength may vary by location, for example, when the size of the aperture 245 changes. For example, a small adhesive strength combined with a large aperture 245 may result in a bond comparable to a large adhesive strength at a location with a small aperture 245.

[0109] The geometric shape and dimensions of the tissue interface 120, the cover 125, or both may vary to conform to a particular application or anatomical structure. For example, the geometric shape or dimensions of the tissue interface 120 and the cover 125 can be adapted to provide an effective and secure seal against difficult anatomical surfaces such as elbows or heels at and around the tissue site. Additionally or alternatively, the dimensions can be modified to increase the surface area of the third layer 215, enhance the movement and proliferation of epithelial cells at the tissue site, and reduce the potential for granulation tissue ingrowth.

[0110] Accordingly, the dressing 110 can provide a sealed treatment environment proximate to the tissue site that is substantially isolated from the external environment, and the negative pressure source 105 can reduce the pressure within the sealed treatment environment. The treatment aperture 240 can provide an open area for the delivery of negative pressure and the passage of exudate through the second layer 210 and the first layer 205. Further, the dressing 110 can allow for reattachment or repositioning, for example, to eliminate air leakage caused by wrinkles and other discontinuities in the dressing 110. The possibility of fixing leaks can, in some embodiments, increase the effectiveness of the therapy and reduce power consumption.

[0111] If not already configured, the dressing interface 285 may be placed over the aperture 290 and attached to the cover 125. The fluid conduit 280 may be fluidly coupled to the dressing interface 285 and the negative pressure source 105.

[0112] Negative pressure can be applied to the tissue interface 120 through the aperture 290. In some embodiments, the spacer manifold 275 can prevent the first layer 205 from being drawn into or pushed into the aperture 290 and can prevent the tissue interface from being blocked by the negative pressure source 105. The standoff 220 preferably resists collapse under therapeutic-level negative pressure. In some examples, the cover 125 in combination with the standoff 220 can effectively form independent air bubbles that can enhance resistance to collapse.

[0113] The negative pressure applied through the tissue interface 120 can also create a negative pressure differential across the fluid restriction 230 of the second layer 210 that can open or expand the fluid restriction 230. For example, in some embodiments where the fluid restriction 230 may include a substantially closed aperture through the second layer 210, similar to the operation of a duckbill valve, the pressure gradient across the aperture can tension the adjacent material of the second layer 210 and can increase the size of the aperture to allow movement of liquid therethrough. By opening the fluid restriction 230, movement of exudate and other liquids to the first layer 205 through the fluid restriction 230 can be enabled. The first layer 205 can allow for the passage of negative pressure and exudate that can be collected in the container 115.

[0114] The change in pressure can also cause the first layer 205 to expand and contract. The second layer 210, the third layer 215, or both can protect the epidermis from irritation that may be caused by the expansion, contraction, or other movement of the first layer 205. For example, in some embodiments, the covering margin 415 may be disposed between the first layer 205 and the epidermis around the tissue site. The second layer 210 and the third layer 215 can also substantially reduce or prevent exposure of the tissue site to the first layer 205, thereby inhibiting tissue growth into the first layer 205. For example, the second layer 210 can cover the treatment aperture 240 to prevent direct contact between the first layer 205 and the tissue site.

[0115] When the negative pressure source 105 is removed or turned off, the pressure difference across the fluid restriction 230 is eliminated, the fluid restriction 230 closes, and exudate or other liquid can be prevented from returning to the tissue site through the second layer 210.

[0116] In some applications, a filler may also be disposed between the tissue site and the third layer 215. For example, if the tissue site is a surface wound, a wound filler may be applied from within the wound to around the wound, and the third layer 215 may be disposed around the wound and over the wound filler. In some embodiments, the filler may be a manifold such as an open-cell foam. The filler may, in some embodiments, include or consist essentially of the same material as the first layer 205 or the spacer manifold 275.

[0117] Additionally or alternatively, an infusion solution or other fluid that can increase the pressure within the tissue interface 120 may be dispensed into the dressing 110. An increase in the pressure within the tissue interface 120 can create a positive pressure differential across the fluid restriction 230 of the second layer 210 that can open the fluid restriction 230 and dispense the infusion solution or other fluid to the tissue site.

[0118] The systems, devices, and methods described herein can provide significant advantages. For example, in some dressings for negative pressure therapy, it may be necessary to size and apply them appropriately to achieve a good fit and seal, which can require time and skill. In contrast, some embodiments of dressing 110 provide a negative pressure dressing that is easily applied and reduces the time for application and removal. In some embodiments, for example, dressing 110 provides or enhances many of the benefits of other negative pressure therapy dressings that require sizing, while being a fully integrated negative pressure therapy dressing that can be applied to a tissue site (including around the wound) in one step without being cut for sizing. Such benefits can include good multi-branching, beneficial granulation, minimal ingrowth into the tissue interface, protection of surrounding tissue from maceration, protection of the tissue site from shed material, and low trauma and high seal bonding. These characteristics can be particularly advantageous for surface wounds with moderate depth and medium to high levels of exudate. Some embodiments of dressing 110 may be maintained on the tissue site for at least 5 days, and some embodiments may be maintained for at least 7 days. The antimicrobial agent in dressing 110 can extend the usable time of dressing 110 by reducing or eliminating the risk of infection, which can be associated with long-term use, particularly in infected or highly exuding wounds.

[0119] Some embodiments of dressing 110 may also provide means for inducing micro-strain on the tissue site and both primary and secondary multi-branching of fluids. For example, some embodiments of the second layer 210 may be embossed to provide a secondary multi-branching that can multi-branch a small amount of fluid at low pressure, and the first layer 205 can provide a primary multi-branching that moves a large amount of fluid at high pressure. Additionally or alternatively, some embodiments of dressing 110 can provide a substantially transparent structure, thereby enabling observation or visualization of the tissue site without compromising the integrity of dressing 110 or the treatment.

[0120] Although shown in several exemplary embodiments, those skilled in the art will recognize that various changes and modifications to the systems, apparatuses, and methods described herein are readily possible within the scope of the appended claims. Further, descriptions of various alternative forms using terms such as "or" are not required to be mutually exclusive 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 can also be combined or removed in various configurations for purposes of sale, manufacture, assembly, or use. For example, in some configurations, for purposes of manufacture or sale, the dressing 110, the container 115, or both can be removed or separated from other components. In other exemplary configurations, one or more of the first layer 205, the second layer 210, or the third layer 215 can also be manufactured, configured, assembled, or sold independently of other components.

[0121] The appended claims recite novel and inventive aspects of the above-described subject matter, but the claims can also include additional subject matter that is not specifically recited in detail. For example, specific features, elements, or aspects can be omitted from the claims if not necessary to distinguish novel and inventive features from those known to those skilled in the art. Features, elements, and aspects described in the context of some embodiments can also be omitted, combined, or replaced by alternative features that serve the same, equivalent, or similar purpose without departing from the scope of the invention as defined by the appended claims.

Claims

1. 1. A dressing for treating a tissue site using negative pressure, the dressing comprising: a first polymer film having a plurality of fluid restriction portions; a second polymer film including a plurality of standoffs disposed adjacent to the first polymer film; A dressing comprising:

2. The dressing of claim 1 , wherein said first polymeric film and said second polymeric film are substantially transparent.

3. 10. The dressing of claim 1, wherein said first polymeric film and said second polymeric film are translucent.

4. The dressing of claim 1 , wherein the first polymeric film and the second polymeric film allow visualization of the tissue site.

5. The dressing of claim 1 , wherein the plurality of standoffs form a plurality of spaces between the first polymer film and the second polymer film.

6. A dressing according to any preceding claim, wherein at least a portion of the standoff is offset from the fluid restriction portion.

7. A dressing according to any preceding claim, wherein substantially all of the standoffs are offset from the fluid restriction portion.

8. A dressing according to any preceding claim, wherein the second polymeric film further comprises a fluid passage adjacent the standoff.

9. A dressing according to any preceding claim, wherein the second polymeric film further comprises an opening adjacent the standoff.

10. A dressing according to any preceding claim, wherein the second polymeric film further comprises openings formed in portions of the second polymeric film between the standoffs.

11. A dressing according to any preceding claim, wherein the second polymeric film further comprises fluid passages configured to transport a fluid through the second polymeric film.

12. A dressing according to any preceding claim, wherein the second polymeric film further comprises an opening adjacent the standoff, the opening having a width in the range of 0.5 millimeters to 1.5 millimeters.

13. A dressing according to any preceding claim, wherein the first polymeric film is bonded to the second polymeric film.

14. A dressing according to any preceding claim, wherein the first polymeric film is bonded to the second polymeric film.

15. A dressing according to any preceding claim, wherein the first polymeric film is adhered to the second polymeric film.

16. A dressing according to any preceding claim, wherein the first polymeric film is mechanically bonded to the second polymeric film.

17. A dressing according to any preceding claim, wherein the first polymeric film is a polyurethane film.

18. A dressing according to any preceding claim, wherein the first polymeric film has a thickness in the range of from about 50 microns to about 100 microns.

19. A dressing according to any preceding claim, wherein the fluid restriction portion is a fenestration in the first polymeric film.

20. 20. The dressing of claim 19, wherein each of the fenestrations has a length in the range of about 2 millimeters to about 5 millimeters.

21. 20. The dressing of claim 19, wherein each of the fenestrations has a length of about 3 millimeters.

22. A dressing according to any preceding claim, wherein the first polymeric film has a thickness in the range from about 200 microns to about 300 microns.

23. A dressing according to any preceding claim, wherein the first polymeric film is flexible.

24. A dressing according to any preceding claim, wherein the first polymeric film is elastic.

25. A dressing according to any preceding claim, wherein the first polymeric film is embossed.

26. A dressing according to any preceding claim, wherein the first polymeric film comprises a boss pattern.

27. 27. The dressing of claim 26, wherein the pattern is a taffeta pattern.

28. 27. The dressing of claim 26, wherein the pattern is a diamond pattern.

29. 27. The dressing of claim 26, wherein the pattern is a woven pattern.

30. A dressing according to any preceding claim, wherein the second polymeric film is a polyurethane film.

31. A dressing according to any preceding claim, wherein the second polymeric film has a thickness of about 500 microns.

32. A dressing according to any preceding claim, wherein the second polymeric film is flexible.

33. A dressing according to any preceding claim, wherein the second polymeric film is elastic.

34. A dressing according to any preceding claim, wherein the standoffs form an array.

35. 35. The dressing of claim 34, wherein each of the standoffs has a height in the range of about 1 millimeter to about 4 millimeters.

36. 35. The dressing of claim 34, wherein each of the standoffs has a width in the range of about 1 millimeter to about 4 millimeters.

37. 35. The dressing of claim 34, wherein the standoffs have a pitch of about 3.5 millimeters to about 4 millimeters.

38. A dressing according to any preceding claim, further comprising a cover disposed over the second polymeric film.

39. A dressing according to any preceding claim, wherein the second polymeric film further comprises at least one fluid passageway.

40. A dressing according to any preceding claim, further comprising a removable screen positioned over the second polymeric film.

41. 41. A dressing according to claim 40, wherein the removable screen comprises a light occlusive film.

42. 41. A dressing according to claim 40, wherein the removable screen comprises an opaque film.

43. 41. A dressing according to claim 40, wherein the removable screen comprises a light occlusive polymeric film.

44. 41. A dressing according to claim 40, wherein the removable screen comprises a light occlusive polyurethane film.

45. at least one fluid passageway through the second polymeric film; a cover disposed over the second polymer film; a spacer disposed between the fluid passage and the cover; 45. A dressing according to any preceding claim further comprising:

46. 46. ​​The dressing of claim 45, wherein the spacer comprises a manifold.

47. 46. ​​The dressing of claim 45, wherein the spacer comprises reticulated foam.

48. 46. ​​The dressing of claim 45, further comprising a dressing interface fluidly coupled to the fluid passageway through the cover and the spacer.

49. 49. The dressing of claim 48, wherein the spacer is coextensive with the dressing interface.

50. 46. ​​The dressing of claim 45, wherein the fluid passageway includes a main opening and one or more secondary openings about the main opening.

51. 46. ​​A dressing according to claim 45, further comprising a screen which is removably attached to the cover and which is light occlusive.

52. 52. The dressing of claim 51, wherein the screen comprises a polyurethane film.

53. 53. A dressing according to any one of claims 1 to 52, further comprising a layer of silicone gel positioned adjacent to the first polymeric film opposite the second polymeric film, the layer of silicone gel having perforations fluidly coupled to at least a portion of the fluid restricting portion.

54. 54. The dressing of claim 53, wherein at least a portion of the perforations are aligned with at least a portion of the fluid restriction portion.

55. A dressing according to any preceding claim, wherein the standoffs comprise blisters, bubbles, cells, bosses, or combinations thereof.

56. 1. A dressing for treating a tissue site using negative pressure, the dressing comprising: A cover having an opening; a first layer including a plurality of standoffs and at least one fluid passage; a second layer including a plurality of fluidic elastomeric valves; a third layer including a treatment opening; a treatment opening in the cover, the first layer, the second layer, and the third layer, assembled in an overlapping relationship with the first layer and the second layer disposed between the cover and the third layer, at least a portion of the elastomeric valve exposed through the treatment opening, the opening in the cover fluidly coupled to at least one fluid passage in the first layer, and the standoff disposed adjacent to the second layer.

57. 57. The dressing of claim 56, wherein the standoffs form a plurality of spaces between the first layer and the second layer.

58. 57. The dressing of claim 56, wherein the treatment aperture forms a frame around at least a portion of the elastomeric valve.

59. 57. The dressing of claim 56, wherein at least a portion of the standoff is offset from the elastomeric valve.

60. 57. The dressing of claim 56, wherein the first layer includes a plurality of fluid passages adjacent the standoffs.

61. 57. The dressing of claim 56, wherein the cover, the first layer, the second layer, and the third layer are substantially transparent.

62. 57. The dressing of claim 56, further comprising a spacer disposed between the opening in the cover and the first layer.

63. 57. The dressing of claim 56, further comprising a screen removably positioned over said cover, said screen being visually occlusive.

64. 57. The dressing of claim 56, wherein the first layer and the second layer each have an exposed periphery.

65. 57. The dressing of claim 56, wherein the cover and the third layer surround the first layer and the second layer.

66. 1. A dressing for treating a tissue site using negative pressure, the dressing comprising: A cover having an opening; a first layer including a plurality of standoffs and at least one fluid passage; a second layer including a plurality of slots; a third layer including a plurality of openings; a dressing, wherein the cover, the first layer, the second layer, and the third layer are assembled in an overlapping relationship with the first layer and the second layer disposed between the cover and the third layer, at least a portion of the slot is exposed through the plurality of openings in the third layer, the openings in the cover are fluidly coupled to at least one fluid passage in the first layer, and the standoff is disposed adjacent to the second layer.

67. 1. An apparatus for treating a tissue site using negative pressure, the apparatus comprising: A dressing according to any one of claims 1 to 66; and a negative pressure source fluidly coupled to the dressing.

68. 67. Use of a dressing according to any preceding claim for treating a tissue site using negative pressure.

69. 1. A method of treating a tissue site using negative pressure, the method comprising: applying a dressing according to any one of claims 1 to 66 to the tissue site; applying negative pressure to the tissue site through the dressing; and viewing the tissue site through the dressing.

70. 1. A method of treating a tissue site using negative pressure, the method comprising: applying to the tissue site a dressing of any one of claims 1-66 comprising a screen configured to obscure the tissue site; applying negative pressure to the tissue site through the dressing; removing the screen; viewing the tissue site through the dressing; and repositioning the screen to obscure the tissue site.

71. 23. A system, apparatus, and method substantially as described herein.

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