WO2021059126A1

WO2021059126A1 - Dressing system for use on deep wounds with reduced in-growth and extended wear time

Info

Publication number: WO2021059126A1
Application number: PCT/IB2020/058839
Authority: WO
Inventors: Christopher Brian Locke; Timothy Mark Robinson
Original assignee: Kci Licensing, Inc.
Priority date: 2019-09-24
Filing date: 2020-09-22
Publication date: 2021-04-01

Abstract

A dressing may include a perforated film, a manifold, and a cover. The perforated film may include a polymer and a plasticizer. The film may be configured to extend over a wound and a periwound of the tissue site, and may be highly flexible and conformable to a deep wound. The film layer may be plastically deformed when pushed into the wound. The film may be breathable and non-adherent to granulation. The manifold may be configured to be adjacent to the film and may backfill the wound. The cover may be disposed over the manifold and coupled to the film around the manifold. In some embodiments, a dressing may include a polymer film layer including a plurality of sacrificial sections configured to break open when the film layer is pushed into the wound. The openings may allow the manifolding of fluid while reducing or inhibiting ingrowth of tissue into the manifold.

Description

DRESSING SYSTEM FOR USE ON DEEP WOUNDS WITH REDUCED IN GROWTH AND

EXTENDED WEAR TIME

CROSS-REFERENCE TO REUATED APPUICATIONS [0001] This application claims the benefit of priority to U.S. Provisional Application No. 62/905,094, filed on September 24, 2019, which is incorporated herein by reference in its entirety.

TECHNICAU FIEUD

[0002] The invention set forth in the appended claims relates generally to tissue treatment systems and more particularly, but without limitation, to dressings for tissue treatment and methods of using the dressings for tissue treatment.

BACKGROUND

[0003] Clinical studies and practice have shown that reducing pressure in proximity to a tissue site can augment and accelerate growth of new tissue at the tissue site. The applications of this phenomenon are numerous, but it has proven particularly advantageous for treating wounds. Regardless of the etiology of a wound, whether trauma, surgery, or another cause, proper care of the wound is important to the outcome. Treatment of wounds or other tissue with reduced pressure may be commonly referred to as "negative-pressure therapy," but is also known by other names, including "negative- pressure wound therapy," "reduced-pressure therapy," "vacuum therapy," "vacuum-assisted closure," and "topical negative-pressure," for example. Negative-pressure therapy may provide a number of benefits, including migration of epithelial and subcutaneous tissues, improved blood flow, and micro deformation of tissue at a wound site. Together, these benefits can increase development of granulation tissue and reduce healing times.

[0004] There is also widespread acceptance that cleansing a tissue site can be highly beneficial for new tissue growth. For example, a wound or a cavity can be washed out with a liquid solution for therapeutic purposes. These practices are commonly referred to as "irrigation" and "lavage" respectively. "Instillation" is another practice that generally refers to a process of slowly introducing fluid to a tissue site and leaving the fluid for a prescribed period of time before removing the fluid. For example, instillation of topical treatment solutions over a wound bed can be combined with negative- pressure therapy to further promote wound healing by loosening soluble contaminants in a wound bed and removing infectious material. As a result, soluble bacterial burden can be decreased, contaminants removed, and the wound cleansed. [0005] While the clinical benefits of negative-pressure therapy and/or instillation therapy are widely known, improvements to therapy systems, components, and processes may benefit healthcare providers and patients.

BRIEF SUMMARY

[0006] New and useful systems, apparatuses, and methods for treating tissue in a negative- pressure therapy environment are set forth in the appended claims. Illustrative embodiments are also provided to enable a person skilled in the art to make and use the claimed subject matter.

[0007] For example, in some embodiments, a dressing for treating tissue may be a composite of dressing layers, including a perforated polymer fdm, a manifold, and an adhesive drape. The polymer fdm may be a composite of a polymer and a plasticizer in some embodiments. In some embodiments, the polymer fdm may be a plastomer. The perforated polymer fdm layer may be highly flexible and conformable to a deep wound. The perforated polymer fdm layer may be plastically deformed when pushed into the wound. The perforated polymer fdm may be breathable and non-adherent to granulation. The dressing may also include an adhesive layer that may aid in coupling the perforated polymer fdm layer to the wound. The manifold may comprise or consist essentially of open-cell foam in some examples.

[0008] Some embodiments of a dressing may include a contact layer, a manifold, and a cover. The contact layer may include a plurality of sacrificial sections. The contact layer may be configured to extend over a wound and a periwound of the tissue site. At least some of the sacrificial sections are configured to open when the contact layer is pushed into the wound. The openings may allow the manifolding of fluid while reducing or inhibiting ingrowth of tissue into the manifold. The manifold may be configured to be adjacent to the contact layer. The cover may be configured to be disposed over the manifold and coupled to the contact layer around the manifold.

[0009] Another example embodiment of a dressing may include a perforated film, a manifold, and a cover. The perforated film may include a polymer and a plasticizer. The perforated film may be configured to extend over a wound and a periwound of the tissue site. The manifold may be configured to be adjacent to the perforated film. The cover may be configured to be disposed over the manifold and coupled to the perforated film around the manifold.

[0010] In more particular examples, the polymer may comprise or consist essentially of polyurethane, elastane, polybutene, polyolefin, or a plastomer. The plasticizer may comprise a low molecular mass oil, benzoic acid, a benzoate derivative, 1,2-cyclohexane dicarboxylic acid diisononyl ester, or an aliphatic ester.

[0011] In more particular examples, the perforated film may comprise a plurality of slots or slits that may be elastic and configured to respond to a pressure gradient across the slots or slits.

[0012] Another example embodiment may include a plastomer film, a manifold, and a cover. The plastomer film may include a plurality of perforations. The plastomer film may be configured to extend over a wound and a periwound of the tissue site. The manifold may be configured to be adjacent to the plastomer film. The cover may be configured to be disposed over the manifold and coupled to the plastomer film around the manifold.

[0013] In more particular examples, the plastomer film may comprise or consist essentially of an ethylene alpha olefin copolymer or octene comonomer and polyethylene.

[0014] A method for applying a dressing to a tissue site is also described herein, wherein some example embodiments include applying a contact layer over the tissue site so that the contact layer extends over a wound and a periwound of the tissue site, filling the wound with a manifold, and applying a cover over the manifold and at least a portion of the contact layer to form a sealed space containing the contact layer and the manifold. The contact layer may include a plurality of sacrificial sections. Applying the contact layer over the tissue site may include pushing the contact layer into the wound and causing one or more of the sacrificial sections to break open.

[0015] Another example method of applying a dressing to a tissue site may include applying a contact layer over the tissue site so that the contact layer extends over a wound and a periwound of the tissue site, filling the wound with a manifold, and applying a cover over the manifold and at least a portion of the contact layer to form a sealed space containing the contact layer and the manifold. The contact layer may comprise a plurality of perforations. Applying the contact layer over the tissue site may include pushing the contact layer into the wound.

[0016] Another example method of applying a dressing to a tissue site may include cutting a manifold to fit a wound of the tissue site, wrapping the manifold with a contact layer comprising a plurality of perforations, filling the wound with the contact layer-wrapped manifold, and applying a cover over the contact layer-wrapped manifold to form a sealed space containing the contact layer- wrapped manifold.

[0017] A kit for forming a seal over a patient’s body is also described herein, wherein some examples of a kit may include a contact layer, a manifold, and a cover. The contact layer may include a plurality of sacrificial sections. The contact layer may be configured to extend over a wound and a periwound of the tissue site. At least some of the sacrificial sections are configured to open when the contact layer is pushed into the wound. The manifold may be configured to be adjacent to the contact layer. The cover may be configured to be disposed over the manifold and coupled to the contact layer around the manifold.

[0018] Another example of a kit for forming a seal over a patient’s body may include a perforated film, a manifold, and a cover. The perforated film may include a polymer and a plasticizer. The perforated film may be configured to extend over a wound and a periwound of the tissue site. The manifold may be configured to be adjacent to the perforated film. The cover may be configured to be disposed over the manifold and coupled to the perforated film around the manifold.

[0019] Another example of a kit for forming a seal over a patient’s body may include a plastomer film, a manifold, and a cover. The plastomer film may include a plurality of perforations. The plastomer film may be configured to extend over a wound and a periwound of the tissue site. The manifold may be configured to be adjacent to the plastomer film. The cover may be configured to be disposed over the manifold and coupled to the plastomer film around the manifold.

[0020] Other objectives, advantages, and a preferred mode of making and using the claimed subject matter may be understood best by reference to the accompanying drawings in conjunction with the following detailed description of illustrative embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a functional block diagram of an example embodiment of a therapy system that can provide negative-pressure treatment and instillation treatment in accordance with this specification;

[0022] Figure 2 is an assembly view of an example of a dressing that can be associated with some embodiments of the therapy system of Figure 1;

[0023] Figure 3 is a schematic view of an example layer that can be associated with some embodiments of the dressing of Figure 2;

[0024] Figure 4 is an assembly view of another example of a dressing that can be associated with some embodiments of the therapy system of Figure 1;

[0025] Figure 5 is a schematic view of an example layer that can be associated with some embodiments of the dressing of Figure 4;

[0026] Figure 6 is a schematic view of the example layer of Figure 5 overlaid on the example layer of Figure 3;

[0027] Figure 7 is a schematic view of another example layer that can be associated with some embodiments of the dressing of Figure 2;

[0028] Figure 8 is a schematic side view of another example of the layer of Figure 7;

[0029] Figure 9 is a schematic side view of another example of the layer of Figure 7;

[0030] Figure 10 is a schematic side view of another example of the layer of Figure 7;

[0031] Figure 11 is a schematic view of another example layer that can be associated with some embodiments of the dressing of Figure 2;

[0032] Figure 12 is a schematic view of another example layer that can be associated with some embodiments of the dressing of Figure 2;

[0033] Figure 13 is a schematic view of an example layer that can be associated with some embodiments of the dressing of Figure 2;

[0034] Figure 14 is a schematic view of an example layer that can be associated with some embodiments of the dressing of Figure 4;

[0035] Figure 15 is a schematic view of the example layer of Figure 14 overlaid on the example layer of Figure 13; [0036] Figure 16 is a schematic side view of another example layer that can be associated with some embodiments of the dressing of Figure 2;

[0037] Figure 17 is a schematic side view of another example layer that can be associated with some embodiments of the dressing of Figure 2;

[0038] Figure 18 is a schematic diagram of an example of the therapy system of Figure 1 having the layer of Figure 2 shown applied to a tissue site;

[0039] Figure 19 is a schematic diagram of another example of the therapy system of Figure 1 having the layer of Figure 7 shown applied to a tissue site; and

[0040] Figure 20 is a schematic diagram of another example of the therapy system of Figure 1 having the layer of Figure 2 shown applied to a tissue site.

DESCRIPTION OF EXAMPLE EMBODIMENTS

[0041] The following description of example embodiments provides information that enables a person skilled in the art to make and use the subject matter set forth in the appended claims, but it may omit certain details already well-known in the art. The following detailed description is, therefore, to be taken as illustrative and not limiting.

[0042] The example embodiments may also be described herein with reference to spatial relationships between various elements or to the spatial orientation of various elements depicted in the attached drawings. In general, such relationships or orientation assume a frame of reference consistent with or relative to a patient in a position to receive treatment. However, as should be recognized by those skilled in the art, this frame of reference is merely a descriptive expedient rather than a strict prescription.

[0043] Figure 1 is a simplified functional block diagram of an example embodiment of a therapy system 100 that can provide negative -pressure therapy with instillation of topical treatment solutions to a tissue site in accordance with this specification.

[0044] The term “tissue site” in this context broadly refers to a wound, defect, or other treatment target located on or within tissue, including but not limited to, a surface wound, bone tissue, adipose tissue, muscle tissue, neural tissue, dermal tissue, vascular tissue, connective tissue, cartilage, tendons, or ligaments. The term “tissue site” may also refer to areas of any tissue that are not necessarily wounded or defective, but are instead areas in which it may be desirable to add or promote the growth of additional tissue. For example, negative pressure may be applied to a tissue site to grow additional tissue that may be harvested and transplanted. A surface wound, as used herein, is a wound on a body that is exposed to the external environment, such as an injury or damage to the epidermis, dermis, and/or subcutaneous layers. Surface wounds may include ulcers or closed incisions, for example. A surface wound, as used herein, does not include wounds within an intra-abdominal cavity. A wound may include chronic, acute, traumatic, subacute, and dehisced wounds, partial-thickness bums, ulcers (such as diabetic, pressure, or venous insufficiency ulcers), flaps, and grafts, for example. [0045] The therapy system 100 may include a source or supply of negative pressure, such as a negative-pressure source 105, and one or more distribution components. A distribution component is preferably detachable and may be disposable, reusable, or recyclable. A dressing, such as a dressing 110, and a fluid container, such as a container 115, are examples of distribution components that may be associated with some examples of the therapy system 100. As illustrated in the example of Figure 1, the dressing 110 may comprise or consist essentially of a tissue interface 120, a cover 125, or both in some embodiments.

[0046] A fluid conductor is another illustrative example of a distribution component. A “fluid conductor,” in this context, broadly includes a tube, pipe, hose, conduit, or other structure with one or more lumina or open pathways adapted to convey a fluid between two ends. Typically, a tube is an elongated, cylindrical structure with some flexibility, but the geometry and rigidity may vary. Moreover, some fluid conductors may be molded into or otherwise integrally combined with other components. Distribution components may also include or comprise interfaces or fluid ports to facilitate coupling and de-coupling other components. In some embodiments, for example, a dressing interface may facilitate coupling a fluid conductor to the dressing 110. For example, such a dressing interface may be a SENSAT.R.A.C.™ Pad available from Kinetic Concepts, Inc. of San Antonio, Texas.

[0047] The therapy system 100 may also include a regulator or controller, such as a controller 130. Additionally, the therapy system 100 may include sensors to measure operating parameters and provide feedback signals to the controller 130 indicative of the operating parameters. As illustrated in Figure 1, for example, the therapy system 100 may include a first sensor 135 and a second sensor 140 coupled to the controller 130.

[0048] The therapy system 100 may also include a source of instillation solution. For example, a solution source 145 may be fluidly coupled to the dressing 110, as illustrated in the example embodiment of Figure 1. The solution source 145 may be fluidly coupled to a positive-pressure source, such as a positive-pressure source 150, a negative-pressure source such as the negative-pressure source 105, or both in some embodiments. A regulator, such as an instillation regulator 155, may also be fluidly coupled to the solution source 145 and the dressing 110 to ensure proper dosage of instillation solution (e.g. saline) to a tissue site. For example, the instillation regulator 155 may comprise a piston that can be pneumatically actuated by the negative-pressure source 105 to draw instillation solution from the solution source during a negative-pressure interval and to instill the solution to a dressing during a venting interval. Additionally or alternatively, the controller 130 may be coupled to the negative-pressure source 105, the positive-pressure source 150, or both, to control dosage of instillation solution to a tissue site. In some embodiments, the instillation regulator 155 may also be fluidly coupled to the negative-pressure source 105 through the dressing 110, as illustrated in the example of Figure 1.

[0049] Some components of the therapy system 100 may be housed within or used in conjunction with other components, such as sensors, processing units, alarm indicators, memory, databases, software, display devices, or user interfaces that further facilitate therapy. For example, in some embodiments, the negative-pressure source 105 may be combined with the controller 130, the solution source 145, and other components into a therapy unit.

[0050] In general, components of the therapy system 100 may be coupled directly or indirectly. For example, the negative-pressure source 105 may be directly coupled to the container 115 and may be indirectly coupled to the dressing 110 through the container 115. Coupling may include fluid, mechanical, thermal, electrical, or chemical coupling (such as a chemical bond), or some combination of coupling in some contexts. For example, the negative-pressure source 105 may be electrically coupled to the controller 130 and may be fluidly coupled to one or more distribution components to provide a fluid path to a tissue site. In some embodiments, components may also be coupled by virtue of physical proximity, being integral to a single structure, or being formed from the same piece of material.

[0051] A negative-pressure supply, such as the negative-pressure source 105, may be a reservoir of air at a negative pressure or may be a manual or electrically-powered device, such as a vacuum pump, a suction pump, a wall suction port available at many healthcare facilities, or a micro pump, for example. “Negative pressure” generally refers to a pressure less than a local ambient pressure, such as the ambient pressure in a local environment external to a sealed therapeutic environment. In many cases, the local ambient pressure may also be the atmospheric pressure at which a tissue site is located. Alternatively, the pressure may be less than a hydrostatic pressure associated with tissue at the tissue site. Unless otherwise indicated, values of pressure stated herein are gauge pressures. References to increases in negative pressure typically refer to a decrease in absolute pressure, while decreases in negative pressure typically refer to an increase in absolute pressure. While the amount and nature of negative pressure provided by the negative-pressure source 105 may vary according to therapeutic requirements, the pressure is generally a low vacuum, also commonly referred to as a rough vacuum, between -5 mm Hg (-667 Pa) and -500 mm Hg (-66.7 kPa). Common therapeutic ranges are between -50 mm Hg (-6.7 kPa) and -300 mm Hg (-39.9 kPa).

[0052] The container 115 is representative of a container, canister, pouch, or other storage component, which can be used to manage exudates and other fluids withdrawn from a tissue site. In many environments, a rigid container may be preferred or required for collecting, storing, and disposing of fluids. In other environments, fluids may be properly disposed of without rigid container storage, and a re-usable container could reduce waste and costs associated with negative-pressure therapy.

[0053] A controller, such as the controller 130, may be a microprocessor or computer programmed to operate one or more components of the therapy system 100, such as the negative- pressure source 105. In some embodiments, for example, the controller 130 may be a microcontroller, which generally comprises an integrated circuit containing a processor core and a memory programmed to directly or indirectly control one or more operating parameters of the therapy system 100. Operating parameters may include the power applied to the negative-pressure source 105, the pressure generated by the negative-pressure source 105, or the pressure distributed to the tissue interface 120, for example. The controller 130 is also preferably configured to receive one or more input signals, such as a feedback signal, and programmed to modify one or more operating parameters based on the input signals.

[0054] Sensors, such as the first sensor 135 and the second sensor 140, are generally known in the art as any apparatus operable to detect or measure a physical phenomenon or property, and generally provide a signal indicative of the phenomenon or property that is detected or measured. For example, the first sensor 135 and the second sensor 140 may be configured to measure one or more operating parameters of the therapy system 100. In some embodiments, the first sensor 135 may be a transducer configured to measure pressure in a pneumatic pathway and convert the measurement to a signal indicative of the pressure measured. In some embodiments, for example, the first sensor 135 may be a piezo-resistive strain gauge. The second sensor 140 may optionally measure operating parameters of the negative-pressure source 105, such as a voltage or current, in some embodiments. Preferably, the signals from the first sensor 135 and the second sensor 140 are suitable as an input signal to the controller 130, but some signal conditioning may be appropriate in some embodiments. For example, the signal may need to be filtered or amplified before it can be processed by the controller 130. Typically, the signal is an electrical signal, but may be represented in other forms, such as an optical signal.

[0055] The tissue interface 120 can be generally adapted to partially or fully contact a tissue site. The tissue interface 120 may take many forms, and may have many sizes, shapes, or thicknesses, depending on a variety of factors, such as the type of treatment being implemented or the nature and size of a tissue site. For example, the size and shape of the tissue interface 120 may be adapted to the contours of deep and irregular shaped tissue sites. Any or all of the surfaces of the tissue interface 120 may have an uneven, coarse, or jagged profile.

[0056] In some embodiments, the tissue interface 120 may comprise or consist essentially of a manifold. A manifold in this context may comprise or consist essentially of a means for collecting or distributing fluid across the tissue interface 120 under pressure. For example, a manifold may be adapted to receive negative pressure from a source and distribute negative pressure through multiple apertures across the tissue interface 120, which may have the effect of collecting fluid from across a tissue site and drawing the fluid toward the source. In some embodiments, the fluid path may be reversed or a secondary fluid path may be provided to facilitate delivering fluid, such as fluid from a source of instillation solution, across a tissue site.

[0057] In some embodiments, the cover 125 may provide a bacterial barrier and protection from physical trauma. The cover 125 may also be constructed from a material that can reduce evaporative losses and provide a fluid seal between two components or two environments, such as between a therapeutic environment and a local external environment. The cover 125 may comprise or consist of, for example, an elastomeric film or membrane that can provide a seal adequate to maintain a negative pressure at a tissue site for a given negative-pressure source. The cover 125 may have a high moisture-vapor transmission rate (MVTR) in some applications. For example, the MVTR may be at least 250 grams per square meter per twenty-four hours in some embodiments, measured using an upright cup technique according to ASTM E96/E96M Upright Cup Method at 38°C and 10% relative humidity (RH). In some embodiments, an MVTR up to 5,000 grams per square meter per twenty-four hours may provide effective breathability and mechanical properties.

[0058] In some example embodiments, the cover 125 may be a polymer drape, such as a polyurethane fdm, that is permeable to water vapor but impermeable to liquid. Such drapes typically have a thickness in the range of 25-50 microns. For permeable materials, the permeability generally should be low enough that a desired negative pressure may be maintained. The cover 125 may comprise, for example, one or more of the following materials: polyurethane (PU), such as hydrophilic polyurethane; cellulosics; hydrophilic polyamides; polyvinyl alcohol; polyvinyl pyrrolidone; hydrophilic acrylics; silicones, such as hydrophilic silicone elastomers; natural rubbers; polyisoprene; styrene butadiene rubber; chloroprene rubber; polybutadiene; nitrile rubber; butyl rubber; ethylene propylene rubber; ethylene propylene diene monomer; chlorosulfonated polyethylene; polysulfide rubber; ethylene vinyl acetate (EVA); co-polyester; and polyether block polyamide copolymers. Such materials are commercially available as, for example, Tegaderm® drape, commercially available from 3M Company, Minneapolis Minnesota; polyurethane (PU) drape; polyether block polyamide copolymer (PEBAX), for example; and INSPIRE 2301 and INSPIRE 2327 polyurethane fdms, commercially available from Expopack Advanced Coatings, Wrexham, United Kingdom. In some embodiments, the cover 125 may comprise INSPIRE 2301 having an MVTR (upright cup technique) of 2600 g/m²/24 hours and a thickness of about 30 microns.

[0059] An attachment device may be used to attach the cover 125 to an attachment surface, such as undamaged epidermis, a gasket, or another cover. The attachment device may take many forms. For example, an attachment device may be a medically-acceptable, pressure -sensitive adhesive configured to bond the cover 125 to epidermis around a tissue site. In some embodiments, for example, some or all of the cover 125 may be coated with an adhesive, such as an acrylic adhesive, which may have a coating weight of about 25-65 grams per square meter (g.s.m.). Thicker adhesives, or combinations of adhesives, may be applied in some embodiments to improve the seal and reduce leaks. Other example embodiments of an attachment device may include a double-sided tape, paste, hydrocolloid, hydrogel, silicone gel, or organogel.

[0060] The solution source 145 may also be representative of a container, canister, pouch, bag, or other storage component, which can provide a solution for instillation therapy. Compositions of solutions may vary according to a prescribed therapy, but examples of solutions that may be suitable for some prescriptions include hypochlorite-based solutions, silver nitrate (0.5%), sulfur-based solutions, biguanides, cationic solutions, and isotonic solutions.

[0061] In operation, the tissue interface 120 may be placed within, over, on, or otherwise proximate to a tissue site. If the tissue site is a wound, for example, the tissue interface 120 may partially or completely fill the wound, or it may be placed over the wound. The cover 125 may be placed over the tissue interface 120 and sealed to an attachment surface near a tissue site. For example, the cover 125 may be sealed to undamaged epidermis peripheral to a tissue site. Thus, the dressing 110 can provide a sealed therapeutic environment proximate to a tissue site, substantially isolated from the external environment, and the negative-pressure source 105 can reduce pressure in the sealed therapeutic environment.

[0062] The fluid mechanics of using a negative-pressure source to reduce pressure in another component or location, such as within a sealed therapeutic environment, can be mathematically complex. However, the basic principles of fluid mechanics applicable to negative-pressure therapy and instillation are generally well-known to those skilled in the art, and the process of reducing pressure may be described illustratively herein as “delivering,” “distributing,” or “generating” negative pressure, for example.

[0063] In general, exudate and other fluid flow toward lower pressure along a fluid path. Thus, the term “downstream” typically implies something in a fluid path relatively closer to a source of negative pressure or further away from a source of positive pressure. Conversely, the term “upstream” implies something relatively further away from a source of negative pressure or closer to a source of positive pressure. Similarly, it may be convenient to describe certain features in terms of fluid “inlet” or “outlet” in such a frame of reference. This orientation is generally presumed for purposes of describing various features and components herein. However, the fluid path may also be reversed in some applications, such as by substituting a positive-pressure source for a negative-pressure source, and this descriptive convention should not be construed as a limiting convention.

[0064] Negative pressure applied across the tissue site through the tissue interface 120 in the sealed therapeutic environment can induce macro-strain and micro-strain in the tissue site. Negative pressure can also remove exudate and other fluid from a tissue site, which can be collected in container 115.

[0065] In some embodiments, the controller 130 may receive and process data from one or more sensors, such as the first sensor 135. The controller 130 may also control the operation of one or more components of the therapy system 100 to manage the pressure delivered to the tissue interface 120. In some embodiments, controller 130 may include an input for receiving a desired target pressure and may be programmed for processing data relating to the setting and inputting of the target pressure to be applied to the tissue interface 120. In some example embodiments, the target pressure may be a fixed pressure value set by an operator as the target negative pressure desired for therapy at a tissue site and then provided as input to the controller 130. The target pressure may vary from tissue site to tissue site based on the type of tissue forming a tissue site, the type of injury or wound (if any), the medical condition of the patient, and the preference of the attending physician. After selecting a desired target pressure, the controller 130 can operate the negative -pressure source 105 in one or more control modes based on the target pressure and may receive feedback from one or more sensors to maintain the target pressure at the tissue interface 120.

[0066] In some embodiments, the controller 130 may have a continuous pressure mode, in which the negative-pressure source 105 is operated to provide a constant target negative pressure for the duration of treatment or until manually deactivated. Additionally or alternatively, the controller may have an intermittent pressure mode. For example, the controller 130 can operate the negative- pressure source 105 to cycle between a target pressure and atmospheric pressure. For example, the target pressure may be set at a value of 135 mmHg for a specified period of time (e.g., 5 min), followed by a specified period of time (e.g., 2 min) of deactivation. The cycle can be repeated by activating the negative-pressure source 105, which can form a square wave pattern between the target pressure and atmospheric pressure.

[0067] In some example embodiments, the increase in negative-pressure from ambient pressure to the target pressure may not be instantaneous. For example, the negative-pressure source 105 and the dressing 110 may have an initial rise time. The initial rise time may vary depending on the type of dressing and therapy equipment being used. For example, some therapy systems may increase negative pressure at a rate of about 20-30 mmHg/second, and other therapy systems may increase negative pressure at a rate of about 5-10 mmHg/second. If the therapy system 100 is operating in an intermittent mode, the repeating rise time may be a value substantially equal to the initial rise time.

[0068] In some example dynamic pressure control modes, the target pressure can vary with time. For example, the target pressure may vary in the form of a triangular waveform, varying between a negative pressure of 50 and 135 mmHg with a rise rate of negative pressure set at a rate of 25 mmHg/min. and a descent rate set at 25 mmHg/min. In other embodiments of the therapy system 100, the triangular waveform may vary between negative pressure of 25 and 135 mmHg with a rise rate of about 30 mmHg/min and a descent rate set at about 30 mmHg/min.

[0069] In some embodiments, the controller 130 may control or determine a variable target pressure in a dynamic pressure mode, and the variable target pressure may vary between a maximum and minimum pressure value that may be set as an input prescribed by an operator as the range of desired negative pressure. The variable target pressure may also be processed and controlled by the controller 130, which can vary the target pressure according to a predetermined waveform, such as a triangular waveform, a sine waveform, or a saw-tooth waveform. In some embodiments, the waveform may be set by an operator as the predetermined or time-varying negative pressure desired for therapy.

[0070] In some embodiments, the controller 130 may receive and process data, such as data related to instillation solution provided to the tissue interface 120. Such data may include the type of instillation solution prescribed by a clinician, the volume of fluid or solution to be instilled to a tissue site (“fill volume”), and the amount of time prescribed for leaving solution at a tissue site (“dwell time”) before applying a negative pressure to the tissue site. The fill volume may be, for example, between 10 and 500 mL, and the dwell time may be between one second to 30 minutes. The controller 130 may also control the operation of one or more components of the therapy system 100 to instill solution. For example, the controller 130 may manage fluid distributed from the solution source 145 to the tissue interface 120. In some embodiments, fluid may be instilled to a tissue site by applying a negative pressure from the negative-pressure source 105 to reduce the pressure at the tissue site, drawing solution into the tissue interface 120. In some embodiments, solution may be instilled to a tissue site by applying a positive pressure from the positive-pressure source 160 to move solution from the solution source 145 to the tissue interface 120. Additionally or alternatively, the solution source 145 may be elevated to a height sufficient to allow gravity to move solution into the tissue interface 120.

[0071] The controller 130 may also control the fluid dynamics of instillation by providing a continuous flow of solution or an intermittent flow of solution. Negative pressure may be applied to provide either continuous flow or intermittent flow of solution. The application of negative pressure may be implemented to provide a continuous pressure mode of operation to achieve a continuous flow rate of instillation solution through the tissue interface 120, or it may be implemented to provide a dynamic pressure mode of operation to vary the flow rate of instillation solution through the tissue interface 120. Alternatively, the application of negative pressure may be implemented to provide an intermittent mode of operation to allow instillation solution to dwell at the tissue interface 120. In an intermittent mode, a specific fill volume and dwell time may be provided depending, for example, on the type of tissue site being treated and the type of dressing being utilized. After or during instillation of solution, negative-pressure treatment may be applied. The controller 130 may be utilized to select a mode of operation and the duration of the negative pressure treatment before commencing another instillation cycle.

[0072] Figure 2 is an assembly view of an example of the dressing 110 of Figure 1, illustrating additional details that may be associated with some embodiments in which the tissue interface 120 comprises more than one layer. In the example of Figure 2, the tissue interface 120 comprises a first layer 205 and a second layer 210. In some embodiments, the first layer 205 may be disposed adjacent to the second layer 210. For example, the first layer 205 and the second layer 210 may be stacked so that the first layer 205 is in contact with the second layer 210. The first layer 205 may also be heat- bonded or adhered to the second layer 210 in some embodiments. In some embodiments, the first layer 205 optionally includes a low-tack adhesive, which can be configured to hold the tissue interface 120 in place while the cover 125 is applied. The low-tack adhesive may be continuously coated on the first layer 205 or applied in a pattern.

[0073] The first layer 205 may comprise or consist essentially of a contact layer configured to contact a tissue site. In some embodiments, the first layer 205 may comprise or consist essentially of a liquid-impermeable, elastomeric material. For example, the first layer 205 may comprise or consist essentially of a polymer film, such as a polyurethane film. In some embodiments, the first layer 205 may comprise or consist essentially of the same material as the cover 125. The first layer 205 may also have a smooth or matte surface texture in some embodiments. A glossy or shiny finish finer or equal to a grade B3 according to the SPI (Society of the Plastics Industry) standards may be particularly advantageous for some applications. In some embodiments, variations in surface height may be limited to acceptable tolerances. For example, the surface of the first layer 205 may have a substantially flat surface, with height variations limited to 0.2 millimeters over a centimeter.

[0074] In some embodiments, the first layer 205 may be hydrophobic. The hydrophobicity of the first layer 205 may vary, but may have a contact angle with water of at least ninety degrees in some embodiments. In some embodiments the first layer 205 may have a contact angle with water of no more than 150 degrees. For example, in some embodiments, the contact angle of the first layer 205 may be in a range of at least 90 degrees to about 120 degrees, or in a range of at least 120 degrees to 150 degrees. Water contact angles can be measured using any standard apparatus. Although manual goniometers can be used to visually approximate contact angles, contact angle measuring instruments can often include an integrated system involving a level stage, liquid dropper such as a syringe, camera, and software designed to calculate contact angles more accurately and precisely, among other things. Non limiting examples of such integrated systems may include the FTA125, FTA200, FTA2000, and FTA4000 systems, all commercially available from First Ten Angstroms, Inc., of Portsmouth, VA, and the DTA25, DTA30, and DTA100 systems, all commercially available from Kruss GmbH of Hamburg, Germany. Unless otherwise specified, water contact angles herein are measured using deionized and distilled water on a level sample surface for a sessile drop added from a height of no more than 5 cm in air at 20-25°C and 20-50% relative humidity. Contact angles herein represent averages of 5-9 measured values, discarding both the highest and lowest measured values. The hydrophobicity of the first layer 205 may be further enhanced with a hydrophobic coating of other materials, such as silicones and fluorocarbons, either as coated from a liquid, or plasma coated.

[0075] The area density of the first layer 205 may vary according to a prescribed therapy or application. In some embodiments, an area density of less than 40 grams per square meter may be suitable, and an area density of about 20-30 grams per square meter may be particularly advantageous for some applications.

[0076] In some embodiments, for example, the first layer 205 may comprise or consist essentially of a composite of a polymer and a plasticizer. For example, in some embodiments, the polymer may include polyurethane, elastane, polybutylene, polyolefin, or plastomer, and the plasticizer may include a low molecular mass oil, benzoic acid (e.g. VELSIFLEX™ by Velsicol), a benzoate derivative, 1,2-cyclohexane dicarboxylic acid diisononyl ester (e.g., HEXAMOLL™ by BASF), or an aliphatic ester (e.g., HEXAMOLL™ by BASF). In some embodiments, the loading of the plasticizer may be up to 60% w/w. In some embodiments, the first layer 205 may comprise or consist essentially of a plastomer. For example, in some embodiments, the plastomer may include an ethylene alpha olefin copolymer (e.g., EXACT™ by ExxonMobil), or an octane comonomer and polyethylene (e.g., QUEO™ by Borealis). In some embodiments, the first layer 205 may have an elongation at break greater than or equal to about 500%. In some embodiments, the first layer 205 may have a modulus of elasticity of less than or equal to about 60 MPa. In some embodiments, the first layer 205 may have an elasticity of less than or equal to about 50%. The first layer 205 may be a force-deformable film that can extend and not spring back under a stretch force, allowing the film to be deformed to the shape of a tissue site. For example, the first layer 205 may be plastically deformed as it is pushed into a tissue site. The first layer 205 may be applied over a wound and then may be worked into the wound by applying a force and distorting the film. The first layer 205 may be extended by about 2 to about 3 times without breaking by effectively thinning. A thickness between 10 microns and 100 microns may be suitable for many applications. In some embodiments, the first layer 205 may have a thickness of about 30 microns. Films may be clear, colored, or printed.

[0077] The first layer 205 may have a high moisture-vapor transmission rate (MVTR) in some applications. For example, the MVTR may be at least 250 grams per square meter per twenty-four hours in some embodiments, measured using an upright cup technique according to ASTM E96/E96M Upright Cup Method at 38°C and 10% relative humidity (RH). In some embodiments, an MVTR up to 5,000 grams per square meter per twenty-four hours may provide effective breathability and mechanical properties.

[0078] The first layer 205 may be configured to control fluid movement across or through the first layer 205. For example, the first layer 205 may have one or more passages, which can be distributed uniformly or randomly across the first layer 205. The passages may be bi-directional and pressure- responsive. For example, each of the passages generally may comprise or consist essentially of an elastic passage that is normally unstrained to substantially reduce liquid flow, and can expand or open in response to a pressure gradient. As illustrated in the example of Figure 2, the passages may comprise or consist essentially of perforations 215 in the first layer 205. Perforations 215 may be formed by removing material from the first layer 205. For example, perforations 215 may be formed by cutting through the first layer 205. In the absence of a pressure gradient across the perforations 215, the perforations 215 may be sufficiently small to form a seal or fluid restriction, which can substantially reduce or prevent liquid flow. Additionally, or alternatively, one or more of the passages may be or may function as an elastomeric valve that is normally closed when unstrained to substantially prevent liquid flow, and can open in response to a pressure gradient. In some examples, the passages may comprise or consist essentially of fenestrations in the first layer 205. Generally, fenestrations are a species of perforation, and may also be formed by removing material from the first layer 205. The amount of material removed and the resulting dimensions of the fenestrations may be up to an order of magnitude less than perforations. In some embodiments, the perforations 215 may be arranged to provide equal or substantially equal elasticity in both longitudinal and lateral directions of the first layer 205, in addition to the inherent elasticity of the first layer 205.

[0079] In some embodiments, the perforations 215 may be formed as slots (or fenestrations formed as slits) in the first layer 205. In some examples, the perforations 215 may comprise or consist of linear slots having a length less than 4 millimeters and a width less than 1 millimeter. The length may be at least 2 millimeters, and the width may be at least 0.4 millimeters in some embodiments. 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 may be achieved with a laser cutter, for example. In some embodiments, the perforations 215 may have a length in a range of about 2 millimeters to about 5 millimeters. Slots of such configurations may function as imperfect elastomeric valves that can substantially reduce liquid flow in a normally closed or resting state. For example, such slots may form a flow restriction without being completely closed or sealed. The slots can expand or open wider in response to a pressure gradient to allow increased liquid flow.

[0080] The second layer 210 generally comprises or consists essentially of a manifold, which can provide a means for collecting or distributing fluid across the tissue interface 120 under pressure. For example, the second layer 210 may be adapted to receive negative pressure from a source and distribute negative pressure through multiple apertures across the tissue interface 120, which may have the effect of collecting fluid from across a tissue site and drawing the fluid toward the source. In some embodiments, the fluid path may be reversed or a secondary fluid path may be provided to facilitate delivering fluid, such as from a source of instillation solution, across the tissue interface 120.

[0081] In some illustrative embodiments, the pathways of the second layer 210 may be interconnected to improve distribution or collection of fluids. In some illustrative embodiments, the second layer 210 may comprise or consist essentially of a porous material having interconnected fluid pathways. Examples of suitable porous material that comprise or can be adapted to form interconnected fluid pathways (e.g., channels) may include cellular foam, including open-cell foam such as reticulated foam; porous tissue collections; and other porous material such as gauze or felted mat that generally include pores, edges, and/or walls. Liquids, gels, and other foams may also include or be cured to include apertures and fluid pathways. In some embodiments, the second layer 210 may additionally or alternatively comprise projections that form interconnected fluid pathways. For example, the second layer 210 may be molded to provide surface projections that define interconnected fluid pathways.

[0082] In some embodiments, the second layer 210 may comprise or consist essentially of a reticulated foam having pore sizes and free volume that may vary according to needs of a prescribed therapy. For example, a reticulated foam having a free volume of at least 90% may be suitable for many therapy applications, and a foam having an average pore size in a range of 400-600 microns may be particularly suitable for some types of therapy. The tensile strength of the second layer 210 may also vary according to needs of a prescribed therapy. For example, the tensile strength of a foam may be increased for instillation of topical treatment solutions. The 25% compression load deflection of the second layer 210 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 second layer 210 may be at least 10 pounds per square inch. The second layer 210 may have a tear strength of at least 2.5 pounds per inch. In some embodiments, the second layer 210 may be a foam comprised of polyols such as polyester or polyether, isocyanate such as toluene diisocyanate, and polymerization modifiers such as amines and tin compounds. In some examples, the second layer 210 may be a reticulated polyurethane foam such as used in GRANUFOAM™ dressing or V.A.C. VERAFLO™ dressing, both available from KCI of San Antonio, Texas.

[0083] Other suitable materials for the second layer 210 may include non-woven fabrics; three- dimensional (3D) polymeric structures, such as molded polymers, embossed and formed films, and fusion-bonded films, and mesh, for example.

[0084] In some examples, the second layer 210 may include a 3D textile. A 3D textile of polyester fibers may be particularly advantageous for some embodiments. For example, the second layer 210 may comprise 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 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 for some embodiments. Such a puncture- resistant fabric may have a warp tensile strength of about 330-340 kilograms per centimeter squared (kg/cm²) and a weft tensile strength of about 270-280 kilograms per centimeter squared (kg/cm²) in some embodiments. Another particularly suitable material may be a polyester spacer fabric having a weight of about 470 grams per square meter, which may have a thickness of about 4-5 millimeters in some embodiments. Such a spacer fabric may have a compression strength of about 20-25 kilopascals (at 40% compression). Additionally or alternatively, the second layer 210 may comprise or consist of a material having substantial linear stretch properties, such as a polyester spacer fabric having 2-way stretch and a weight of about 380 grams per square meter. A suitable spacer fabric may have a thickness of about 3-4 millimeters, and may have a warp and weft tensile strength of about 30-40 kilograms in some embodiments. The fabric may have a close-woven layer of polyester on one or more opposing faces in some examples.

[0085] Figure 3 is a schematic view of another example of the first layer 205, illustrating additional details that may be associated with some embodiments. For example, as illustrated in Figure 3, the perforations 215 may comprise a first plurality of perforations 305 and a second plurality of perforations 310. Each of the first plurality of perforations 305 and the second plurality of perforations 310 may be linear or curved perforations, such as slots or slits. In some embodiments where the perforations 215 are linear slots or slits, each of the first plurality of perforations 305 may have a length Li and each of the second plurality of perforations 310 may have a length L2. In some embodiments, where the perforations 215 are curved slots or slits, each of the first plurality of perforations 305 may have a length Li measured from an end of the curved slot or slit to the other end of the curved slot or slit, and each of the second plurality of perforations 310 may have a length L2 measured from an end of the curved slot or slit to the other end of the curved slot or slit. In some embodiments, the length Li may be equal to the length L2. The first plurality of perforations 305 and the second plurality of perforations 310 may be distributed across the first layer 205 in one or more rows in one direction or in different directions.

[0086] In example embodiments, each of the first plurality of perforations 305 may have a first long axis. In some embodiments, the first long axis may be parallel to a first reference line 315 running in a first direction. In illustrative examples, each of the second plurality of perforations 310 may have a second long axis. In example embodiments, the second long axis may be parallel to a second reference line 320 running in a second direction. In some embodiments, one or both of the first reference line 315 and the second reference line 320 may be defined relative to an edge 325 or line of symmetry of the first layer 205. For example, one or both of the first reference line 315 and the second reference line 320 may be parallel or coincident with an edge 325 or line of symmetry of the first layer 205. In some illustrative embodiments, one or both of the first reference line 315 and the second reference line 320 may be rotated an angle relative to an edge 325 of the first layer 205. In example embodiments, an angle a may define the angle between the first reference line 315 and the second reference line 320.

[0087] In some example embodiments, the centroid of each of the first plurality of perforations 305 within a row may intersect a third reference line 330 running in a third direction. In illustrative embodiments, the centroid of each of the second plurality of perforations 310 within a row may intersect a fourth reference line 335 running in a fourth direction. In general, a centroid refers to the center of mass of a geometric object. In the case of a substantially two dimensional object such as a linear slit, the centroid of the linear slit will be the midpoint.

[0088] The pattern of perforations 215 may also be characterized by a pitch, which indicates the spacing between corresponding points on perforations 215 within a pattern. In example embodiments, the pitch may indicate the spacing between the centroids of perforations 215 within the pattern. Some patterns may be characterized by a single pitch value, while others may be characterized by at least two pitch values. For example, if the spacing between centroids of the perforations 215 is the same in all orientations, the pitch may be characterized by a single value indicating the spacing between centroids in adjacent rows. In example embodiments, a pattern comprising a first plurality of perforations 305 and a second plurality of perforations 310 may be characterized by two pitch values, Pi and Pi, where Pi is the spacing between the centroids of each of the first plurality of perforations 305 in adjacent rows, and Pi is the spacing between the centroids of each of the second plurality of perforations 310 in adjacent rows.

[0089] In example embodiments, within each row of the first plurality of perforations 305, each perforation may be separated from an adjacent perforation by a distance /)_/. In some embodiments, within each row of the second plurality of perforations 310, each perforation may be separated from an adjacent perforation by a distance Di. In some patterns, the rows may be staggered. The stagger may be characterized by an orientation of corresponding points in successive rows relative to an edge or other reference line associated with the first layer 205. In some embodiments, the rows of the first plurality of perforations 305 may be staggered. For example, a fifth reference line 340 in a fifth direction runs through the centroids of corresponding perforations 215 of adjacent rows of the first plurality of perforations 305. In some example embodiments, the stagger of the rows of the first plurality of perforations 305 may be characterized by the angle b formed between the first reference line 315 and the fifth reference line 340. In additional illustrative embodiments, the rows of the second plurality of perforations 310 may also be staggered. For example, a sixth reference line 345 in a sixth direction runs through the centroids of corresponding perforations 215 of adjacent rows of the second plurality of perforations 310. In some embodiments, the stagger of the rows of the second plurality of perforations 310 may be characterized by the angle y formed between the first reference line 315 and the sixth reference line 345.

[0090] In the example of Figure 3, each of the first plurality of perforations 305 and the second plurality of perforations 310 may be linear slots or slits. The first reference line 315 may be parallel with an edge 325, and the second reference line 320 may be orthogonal to the edge 325. In example embodiments, the third reference line 330 is orthogonal to the first reference line 315, and the fourth reference line 335 is orthogonal to the second reference line 320. For example, the third reference line 330 may be incident with the centroids of corresponding perforations in alternating rows of the second plurality of perforations 310, and the fourth reference line 335 may intersect the centroids of corresponding perforations in alternating rows of the first plurality of perforations 305. In the example of Figure 3, the perforations 215 are arranged in a cross-pitch pattern in which each of the first plurality of perforations 305 is orthogonal along its first long axis to each of the second plurality of perforations 310 along its second long axis. For example, in Figure 3, Pi is equal to P2 (within acceptable manufacturing tolerances), and the cross-pitch pattern may be characterized by a single pitch value. Additionally, Li and li may be substantially equal, and /⁾ _/ and D2 may be also be substantially equal, all within acceptable manufacturing tolerances. The rows of the first plurality of perforations 305 and the rows of the second plurality of perforations 310 may be characterized as staggered. For example, in some example embodiments of Figure 3, a may be about 90°, b may be about 135°, y may be about 45°, Pi may be about 4 millimeters, P2 may be about 4 millimeters, Li may be about 3 millimeters, li may be about 3 millimeters, /⁾ _/ may be about 5 millimeters, and D2 may be about 5 millimeters.

[0091] Figure 4 is an assembly view of another example of the dressing 110 of Figure 1, illustrating additional details that may be associated with some embodiments in which the tissue interface 120 may comprise additional layers. In the example of Figure 4, the tissue interface 120 may comprise a third layer 405 and/or a fourth layer 410, in addition to the first layer 205 and the second layer 210. In some embodiments, the third layer 405 may be adjacent to the first layer 205 opposite the second layer 210. The third layer 405 may also be bonded to the first layer 205 in some embodiments. In some embodiments, the fourth layer 410 may be adjacent to the first layer 205 proximate the second layer 210. The fourth layer 410 may also be bonded to the first layer 205 in some embodiments. In some embodiments, the third layer 405 and/or the fourth layer 410 may be coated or printed on the first layer 205. In some embodiments, the tissue interface 120 may include the third layer 405 but not the fourth layer 410. In some embodiments, the tissue interface 120 may include the fourth layer 410 but not the third layer 405.

[0092] The third layer 405 and the fourth layer 410 may comprise or consist essentially of sealing layers formed from a soft, pliable material, such as a tacky gel, suitable for providing a fluid seal with a tissue site, and may have a substantially flat surface. For example, the third layer 405 and/or the fourth layer 410 may comprise, without limitation, a silicone gel, a soft silicone, hydrocolloid, hydrogel, polyurethane gel, polyolefin gel, hydrogenated styrenic copolymer gel, a foamed gel, a soft closed cell foam such as polyurethanes and polyolefins coated with an adhesive, polyurethane, polyolefin, or hydrogenated styrenic copolymers. The third layer 405 and/or the fourth layer 410 may include an adhesive surface on an underside and a patterned coating of acrylic on a top side. The patterned coating of acrylic may be applied about a peripheral area to allow higher bonding in regions that are likely to be in contact with skin rather than the wound area. In other embodiments, the third layer 405 and/or the fourth layer 410 may comprise a low-tack adhesive layer instead of silicone. In some embodiments, the third layer 405 and/or the fourth layer 410 may have a thickness between about 200 microns (pm) and about 1000 microns (pm). In some embodiments, the third layer 405 and/or the fourth layer 410 may have a hardness between about 5 Shore OO and about 80 Shore OO. Further, the third layer 405 and/or the fourth layer 410 may be comprised of hydrophobic or hydrophilic materials. In some embodiments the third layer 405 and/or the fourth layer 410 may have a bond strength on stainless steel of less than 3 newtons per 25 millimeters (3N/25mm). The third layer 405 may aid in placement of the first layer 205 and/or the dressing 110 and may aid in coupling the third layer 405 to the tissue site. The fourth layer 410 may aid in coupling the second layer 210 to the first layer 205. In some embodiments, the fourth layer 410 may also aid in coupling the cover 125 to the first layer 205.

[0093] In some embodiments, the third layer 405 and/or the fourth layer 410 may be a hydrophobic-coated material. For example, the third layer 405 and/or the fourth layer 410 may be formed by coating a porous material, such as, for example, woven, nonwoven, molded, or extruded mesh with a hydrophobic material. The hydrophobic material for the coating may be a soft silicone, for example.

[0094] The third layer 405 and/or the fourth layer 410 may have comers 415 and edges 420. The third layer 405 and/or the fourth layer 410 may include apertures 425. The apertures 425 may be formed by cutting or by application of local RF or ultrasonic energy, for example, or by other suitable techniques for forming an opening. The apertures 425 may have a uniform distribution pattern, or may be randomly distributed on the third layer 405. The apertures 425 in the third layer 405 may have many shapes, including circles, squares, stars, ovals, polygons, slits, complex curves, rectilinear shapes, triangles, for example, or may have some combination of such shapes.

[0095] Each of the apertures 425 may have uniform or similar geometric properties. For example, in some embodiments, each of the apertures 425 may be circular apertures, having substantially the same diameter. In some embodiments, the diameter of each of the apertures 425 may be between about 1 millimeter and about 50 millimeters. In other embodiments, the diameter of each of the apertures 425 may be between about 1 millimeter and about 20 millimeters.

[0096] In other embodiments, geometric properties of the apertures 425 may vary. For example, the diameter of the apertures 425 may vary depending on the position of the apertures 425 in the third layer 405. The apertures 425 may be spaced substantially equidistant over the third layer 405. Alternatively, the spacing of the apertures 425 may be irregular.

[0097] As illustrated in the example of Figure 4, some embodiments of the dressing 110 may include a release liner 430 to protect the third layer 405 prior to use. The release liner 430 may also provide stiffness to facilitate handling and applying the dressing 110. The release liner 430 may be, for example, a casting paper, a fdm, or polyethylene. Further, in some embodiments, the release liner 430 may be a polyester material such as polyethylene terephthalate (PET), or similar polar semi-crystalline polymer. The use of a polar semi-crystalline polymer for the release liner 430 may substantially preclude wrinkling or other deformation of the dressing 110. For example, the polar semi-crystalline polymer may be highly orientated and resistant to softening, swelling, or other deformation that may occur when brought into contact with components of the dressing 110, or when subj ected to temperature or environmental variations, or sterilization. Further, a release agent may be disposed on a side of the release liner 430 that is configured to contact the third layer 405. For example, the release agent may be a silicone coating and may have a release factor suitable to facilitate removal of the release liner 430 by hand and without damaging or deforming the dressing 110. In some embodiments, the release agent may be a fluorocarbon or a fluorosilicone, for example. In other embodiments, the release liner 430 may be uncoated or otherwise used without a release agent. In some embodiments, a release liner (not shown) may be provide to protect the fourth layer 410 prior to use.

[0098] Figure 5 is a schematic view of an example configuration of the apertures 425, illustrating additional details that may be associated with some embodiments of the third layer 405. In some embodiments, the apertures 425 illustrated in Figure 5 may be associated only with an interior portion of the third layer 405. In the example of Figure 5, the apertures 425 are generally circular and have a width Wi, which may be about 2 millimeters in some examples. Figure 5 also illustrates an example of a uniform distribution pattern of the apertures 425. In Figure 5, the apertures 425 are distributed across the third layer 405 in a grid of parallel rows and columns in a straight pattern. Within each row and column, the apertures 425 may be equidistant from each other, as illustrated in the example of Figure 5. In example embodiments, a pattern comprising a plurality of apertures 425 may be characterized by two pitch values, Pi and Pi, where Pi is the spacing between the centroids of adjacent apertures 425 within a column, and Pi is the spacing between the centroids of adjacent apertures 425 within a row. The rows of apertures 425 may be spaced a distance Pi, and the columns of apertures may be spaced a distance Pi. For example, Pi may be about 4 millimeters and P2 may be about 4 millimeters. In some embodiments, for example, the pitch values, Pi and Pi, of the apertures 425 may be equal to the pitch values Pi and Pi, of the perforations 305. The spacing of the apertures 425 may vary in some embodiments to increase the density of the apertures 425 according to therapeutic requirements.

[0099] Figure 6 is a schematic view of the third layer 405 of Figure 5 overlaid on the first layer 205 of Figure 3, illustrating additional details that may be associated with some example embodiments ofthe tissue interface 120. For example, as illustrated in Figure 6, the perforations 215 may be aligned, overlapping, in registration with, or otherwise fluidly coupled to the apertures 425 in some embodiments. The apertures 425 may have the same pattern as the perforations 215. In some embodiments, one or more of the perforations 215 may be registered with the apertures 425 only in an interior portion, or only partially registered with the apertures 425. The perforations 215 in the example of Figure 6 are generally configured so that each of the perforations 215 is registered with only one of the apertures 425. In other examples, one or more of the perforations 215 may be registered with more than one ofthe apertures 425. For example, any one or more ofthe perforations 215 may extend across two or more of the apertures 425. Additionally or alternatively, one or more of the perforations 215 may not be registered with any of the apertures 425.

[00100] As illustrated in the example of Figure 6, the apertures 425 may be sized to expose a portion of the first layer 205, the perforations 215, or both through the third layer 405. In some embodiments, one or more of the apertures 425 may be sized to expose more than one of the perforations 215. For example, some or all of the apertures 425 may be sized to expose two or three of the perforations 215. In some examples, the length of each of the perforations 215 may be substantially equal to the diameter of each of the apertures 425. More generally, the average dimensions of the perforations are substantially similar to the average dimensions of the apertures 425. In some embodiments, the dimensions of the perforations 215 may exceed the dimensions of the apertures 425, and the size of the apertures 425 may limit the effective size of the perforations 215 exposed through the third layer 405.

[00101] Figure 7 is a schematic view of another example of the first layer 205, illustrating additional details that may be associated with some embodiments. As illustrated in the example of Figure 7, in some embodiments, the first layer 205 may include sacrificial sections 700, which can be distributed uniformly or randomly across the first layer 205. The sacrificial sections 700 may include any raised or recessed feature. For example, the sacrificial sections 700 may comprise or consist essentially of embossments, debossments, recesses, projections, ribs, ridges, channels, grooves, blisters, regions of reduced thickness, regions of stress concentrations, and stress raisers. A sacrificial section 700 may include any feature on the first layer 205 that is configured to tear, open, or break upon stretching the first layer 205. The sacrificial sections 700 may be formed, for example, by heat, embossing, micro embossing, debossing, stamping, casting, or by other suitable techniques for forming a sacrificial section. The sacrificial sections 700 may have a uniform distribution pattern, or may be randomly distributed on the first layer 205. The sacrificial sections 700 in the first layer 205 may have many shapes, including circles, squares, stars, ovals, polygons, complex curves, rectilinear shapes, triangles, for example, or may have some combination of such shapes.

[00102] Each of the sacrificial sections 700 may have uniform or similar geometric properties. For example, in some embodiments, each of the sacrificial sections 700 may be circular, having substantially the same diameter. In some embodiments, the diameter of each of the sacrificial sections 700 may be in a range of about 0.5 millimeters to about 5 millimeters. In other embodiments, the diameter of each of the sacrificial sections 700 may be about 0.8 millimeters. In some embodiments, the diameter of the sacrificial sections 700 may be less than 0.8 millimeters. In some embodiments, the sacrificial sections 700 may have an area in a range of about 0.2 mm² to about 20 mm². In some embodiments, the sacrificial sections 700 may have an area of about 0.5 mm². In some embodiments, the sacrificial sections 700 may have an area less than 0.5 mm².

[00103] In other embodiments, geometric properties of the sacrificial sections 700 may vary. For example, the diameter of the sacrificial sections 700 may vary depending on the position of the sacrificial sections 700 in the first layer 205. The sacrificial sections 700 may be spaced substantially equidistant over the first layer 205. Alternatively, the spacing of the sacrificial sections 700 may be irregular.

[00104] In the example of Figure 7, the sacrificial sections 700 are generally circular and have a width W2, which may be about 0.8 millimeters in some examples. Figure 7 also illustrates an example of a uniform distribution pattern of the sacrificial sections 700. In Figure 7, the sacrificial sections 700 are distributed across the first layer 205 in a grid of parallel rows and columns. Within each row and column, the sacrificial sections 700 may be equidistant from each other, as illustrated in the example of Figure 7. The rows may be spaced a distance /T. and the sacrificial sections 700 within each of the rows may be spaced a distance /¾. For example, a distance l) of about 2 millimeters on center and a distance D4 of about 4 millimeters on center may be suitable for some embodiments. The sacrificial sections 700 in adjacent rows may be aligned or offset. For example, adjacent rows may be offset, as illustrated in Figure 7, so that the sacrificial sections 700 are aligned in alternating rows separated by a distance /¾. A distance / A of about 4 millimeters may be suitable for some examples. The spacing of the sacrificial sections 700 may vary in some embodiments to increase the density of the sacrificial sections 700 according to therapeutic requirements.

[00105] In some embodiments of the first layer 205 having sacrificial sections 700, the first layer 205 may comprise or consist essentially of a polymer film, such as a polyurethane film. In some embodiments, the first layer 205 may comprise or consist essentially of the same material as the cover 125. In some embodiments, for example, the first layer 205 may comprise or consist essentially of a hydrophobic polymer, such as a polyethylene film. Other suitable polymeric films include polyurethanes, acrylics, polyolefin (such as cyclic olefin copolymers), polyacetates, polyamides, polyesters, copolyesters, PEBAX block copolymers, thermoplastic elastomers, thermoplastic vulcanizates, polyethers, polyvinyl alcohols, polypropylene, polymethylpentene, polycarbonate, styreneics, silicones, fluoropolymers, and acetates.

[00106] Figure 8, Figure 9, and Figure 10 are schematic side views other examples of the first layer 205, illustrating additional details that may be associated with some embodiments. As illustrated in the example of Figure 8, the sacrificial sections 700 may be hemispherical projections extending from a base portion 800 of the first layer 205. The base portion 800 is the portion of the first layer 205 that does not have a sacrificial section 700. As illustrated in the example of Figure 9, the sacrificial sections 700 may be projections having a flat top. As illustrated in the example of Figure 10, the sacrificial sections 700 may be recesses. In each of Figure 8, Figure 9, and Figure 10, the base portion 800 of the first layer 205 may have a first thickness T1 and the sacrificial sections 700 may have a second thickness T2. In some embodiments, the second thickness T2 may be about 50% of the first thickness Tl. In some embodiments, the second thickness T2 may range from about 10% to about 70% of the first thickness Tl. In some embodiments, the sacrificial sections 700 may all extend the same direction. In other embodiments, some of the sacrificial sections 700 may extend in first direction and some of the sacrificial sections 700 may extend in a second direction opposite the first direction.

[00107] Figure 11 is a schematic view of another example of the first layer 205, illustrating additional details that may be associated with some embodiments. As illustrated in the example of Figure 11, in some embodiments, the first layer 205 may include sacrificial sections 700 and perforations 215. The sacrificial sections 700 may be located in a first region 1100 of the first layer 205 and the perforations 215 may be located in a second region 1105. In some embodiments, the first region 1100 may be centrally located in the first layer 205 and the second region 1105 may surround the first region 1100. In some embodiments, the first region 1100 may be configured to be located proximate a wound and the second region 1105 may be configured to be located proximate a periwound.

[00108] Figure 12 is a schematic view of another example of the first layer 205, illustrating additional details that may be associated with some embodiments. In some embodiments, the first layer 205 may include sacrificial sections 700 and perforations 215 distributed across the first layer 205. In some embodiments, the sacrificial sections 700 and the perforations 215 may be uniformly distributed across the first layer 205. As illustrated in the example of Figure 12, the first layer 205 may include alternating rows of sacrificial sections 700 and perforations 215. In some embodiments, the first layer 205 may include alternating columns of sacrificial sections 700 and perforations 215. In some embodiments, the first layer 205 may include rows comprising alternating sacrificial sections 700 and perforations 215. In some embodiments, the first layer 205 may include columns comprising alternating sacrificial sections 700 and perforations 215.

[00109] Figure 13 is a schematic view of another example of the first layer 205, illustrating additional details that may be associated with some embodiments. As illustrated in the example of Figure 13, the perforations 215 may each consist essentially of one or more linear slots having a length Li. A length Ls of about 3 millimeters may be suitable for some examples. Figure 13 additionally illustrates an example of a uniform distribution pattern of the perforations 215. In Figure 13, the perforations 215 are substantially coextensive with the first layer 205, and are distributed across the first layer 205 in a grid of parallel rows and columns, in which the slots are also mutually parallel to each other. The rows may be spaced a distance Dg. and the perforations 215 within each of the rows may be spaced a distance D7. For example, a distance Dr, of about 3 millimeters on center and a distance D₇ of about 3 millimeters on center may be suitable for some embodiments. The perforations 215 in adjacent rows may be aligned or offset. For example, adjacent rows may be offset, as illustrated in Figure 13, so that the perforations 215 are aligned in alternating rows separated by a distance Z¾. A distance Z¾ of about 6 millimeters may be suitable for some examples. The spacing of the perforations 215 may vary in some embodiments to increase the density of the perforations 215 according to therapeutic requirements.

[00110] Figure 14 is a schematic view of an example configuration of the apertures 425, illustrating additional details that may be associated with some embodiments of the third layer 405. In some embodiments, the apertures 425 illustrated in Figure 14 may be associated only with an interior portion of the third layer 405. In the example of Figure 14, the apertures 425 are generally circular and have a width W₃, which may be about 2 millimeters in some examples. Figure 14 also illustrates an example of a uniform distribution pattern of the apertures 425. In Figure 14, the apertures 425 are distributed across the third layer 405 in a grid of parallel rows and columns. Within each row and column, the apertures 425 may be equidistant from each other, as illustrated in the example of Figure 14. The rows may be spaced a distance Dg, and the apertures 425 within each of the rows may be spaced a distance Dio. For example, a distance Dg of about 3 millimeters on center and a distance Dw of about 6 millimeters on center may be suitable for some embodiments. The apertures 425 in adjacent rows may be aligned or offset. For example, adjacent rows may be offset, as illustrated in Figure 14, so that the apertures 425 are aligned in alternating rows separated by a distance Du. A distance Du of about 6 millimeters may be suitable for some examples. The spacing of the apertures 425 may vary in some embodiments to increase the density of the apertures 425 according to therapeutic requirements.

[00111] Figure 15 is a schematic view of the third layer 405 of Figure 14 overlaid on the first layer 205 of Figure 13, illustrating additional details that may be associated with some example embodiments of the tissue interface 120. For example, as illustrated in Figure 15, the perforations 215 may be aligned, overlapping, in registration with, or otherwise fluidly coupled to the apertures 425 in some embodiments.

[00112] Figure 16 and Figure 17 are schematic side views other examples of the first layer 205, illustrating additional details that may be associated with some embodiments. In some embodiments, the first layer 205 may include one or more features configured to aid in coupling the second layer 210 to the first layer. For example, as shown in Figure 16, the first layer 205 may have a first side 1600 and a second side 1605. The first side 1600 may be configured to face the tissue site and the second side 1605 may be configured to face the second layer 210. In some embodiments, the first layer 205 may include one or more micro-hooks 1610 on the second side 1605. The micro-hooks 1610 may be configured to mechanically interlock with the second layer 210. As shown in Figure 17, in some embodiments, the second side 1605 of the first layer 205 may be flocked with one or more fibers 1700.

[00113] In some embodiments, one or more of the components of the dressing 110 may additionally be treated with an antimicrobial agent. For example, the second layer 210 may be a foam, mesh, or non-woven coated with an antimicrobial agent. In some embodiments, the second layer 210 may comprise antimicrobial elements, such as fibers coated with an antimicrobial agent. Additionally or alternatively, some embodiments of the first layer 205 may be a polymer coated or mixed with an antimicrobial agent. In other examples, the fluid conductor 230 may additionally or alternatively be treated with one or more antimicrobial agents. Suitable antimicrobial agents may include, for example, metallic silver, PHMB, iodine or its complexes and mixes such as povidone iodine, copper metal compounds, chlorhexidine, or some combination of these materials.

[00114] Additionally or alternatively, one or more of the components may be coated with a mixture that may include citric acid and collagen, which can reduce bio-films and infections. For example, the second layer 210 may be foam coated with such a mixture.

[00115] The cover 125, the first layer 205, the second layer 210, the third layer 405, and/or the fourth layer 410, or various combinations may be assembled before application or in situ. In some embodiments, the first layer 205 may be dispensed as a single sheet. In other embodiments, the first layer 205 may be supplied on a roll. Rolls of multiple widths may be provided. The first layer 205 may be cut from the roll and sized and/or shaped as desired.

[00116] Figure 18 is a schematic diagram of an example of the therapy system 100 applied to a tissue site. In the example of Figure 18, the tissue site comprises or consists essentially of a wound 1800, which may extend through or otherwise involve an epidermis 1805, a dermis 1810, and a subcutaneous tissue 1815. In some embodiments, the wound 1800 may extend below the surface of the epidermis 1805. A portion of the epidermis 1805 surrounding the wound 1800 may be considered the periwound 1820. The wound 1800 may also include an edge 1825 between the wound 1800 and the periwound 1820. The geometry and dimensions of the tissue interface 120, the cover 125, or both may vary to suit a particular application or anatomy. For example, the first layer 205 may be sized and/or shaped to cover the wound 1800 and at least a part of the epidermis 1805. Additionally, the second layer 210 may be sized and/or shaped to extend into and fill the wound 1800.

[00117] The tissue interface 120 can be placed within, over, on, or otherwise proximate to the tissue site. In use, a release liner (if included) may be removed to expose the third layer 405 (not shown) and the first layer 205. Additionally, another release liner (if included) may be removed to expose the fourth layer 410 (if included) and the first layer 205. In the example of Figure 18, the first layer 205 can be placed over the tissue site, including the wound 1800, the edge 1825, and the periwound 1820. The first layer 205 may be pushed into the wound 1800. The first layer 205 may be worked into the wound 1800, including any deep recesses in the wound 1800, by applying a force and distorting the fdm of the first layer 205. The material properties of the first layer 205 allow the first layer 205 to be deformed into the wound 1800, without significantly distorting the perforations 215 or springing back out of the wound 1800. The first layer 205 may be plastically deformed to the wound 1800. The first layer 205 may be readily deformed into the wound 1800 but may remain flat over the periwound 1820. The third layer 405 (not shown) may aid in coupling the first layer 205 to the wound 1800 and the periwound 1820. As shown in the example of Figure 18, the first layer 205 maybe coupled flush against the wound 1800 and the periwound 1820. The perforations 215 in the first layer 205 located in the wound 1800 may be more open than the perforations 215 located over the periwound. The more open perforations 215 proximate the wound 1800 allow for manifolding of fluid through the first layer 205, whereas the more closed perforations 215 proximate the periwound 1820 may reduce or prevent the manifolding of fluid through the first layer 205 to the periwound 1820.

[00118] Following the application of the first layer 205, the second layer 210 may be placed into the wound 1800 above the first layer 205. The second layer 210 may be sized and/or shaped to fit the size and shape of the wound 1800 so that the second layer 210 can fill the wound 1800. In some embodiments, based on the size and shape of the wound 1800, filling the wound 1800 may be accomplished with more than one second layer 210. If included, the fourth layer 410 may aid in coupling the second layer 210 to the first layer 205. The first layer 205 may be interposed between the second layer 210 and the tissue site, which can prevent direct contact between the second layer 210 and the periwound 1820, providing a barrier between the periwound 1820 and the second layer 210. In some embodiments, the micro-hooks 1310 may aid in coupling the second layer 210 to the first layer 205. In other embodiments, the flocked fibers 1400 may aid in coupling the second layer 210 to the first layer 205.

[00119] Following the insertion of the second layer 210 into the wound behind the first layer 205, the cover 125 may be placed over the second layer 210 and the first layer 205. As shown in the example of Figure 15, in some embodiments, the edge of the cover 125 may not extend to the edge of the first layer 205. In some embodiments, the cover 125 and the first layer 205 may be coextensive. For example, the cover may be cut flush with the edge of the first layer 205. In other embodiments, the cover 125 may overlap the edge of the first layer 205. If included, the fourth layer 410 may aid in coupling the cover 125 to the first layer 205.

[00120] Figure 18 also illustrates one example of a fluid conductor 1830 and a dressing interface 1835. As shown in the example of Figure 18, the fluid conductor 1830 may be a flexible tube, which can be fluidly coupled on one end to the dressing interface 1835. The dressing interface 935 may be an elbow connector, as shown in the example of Figure 18. In some examples, the tissue interface 120 can be applied to the tissue site 905 before the cover 125 is applied over the tissue interface 120. The cover 125 may include an aperture 1840, or the aperture 1840 may be cut into the cover 125 before or after positioning the cover 125 over the tissue interface 120. The aperture 1840 of Figure 18 is centrally disposed. In other examples, the position of the aperture 1840 may be off-center or adjacent to an end or edge of the cover 125. The dressing interface 935 can be placed over the aperture 1840 to provide a fluid path between the fluid conductor 1830 and the tissue interface 120. In other examples, the fluid conductor 1830 may be inserted directly through the cover 125 into the tissue interface 120.

[00121] If not already configured, the dressing interface 1835 may be disposed over the aperture 1840 and attached to the cover 125. The fluid conductor 1830 may be fluidly coupled to the dressing interface 1835 and to the negative-pressure source 105.

[00122] Negative pressure from the negative-pressure source 105 can be distributed through the fluid conductor 1830 and the dressing interface 1835 to the tissue interface 120. Negative pressure applied through the tissue interface 120 can also create a negative pressure differential across the perforations 215 in the first layer 205, which can open or expand the perforations 215. For example, in some embodiments in which the perforations 215 may comprise substantially closed fenestrations through the first layer 205, a pressure gradient across the fenestrations can strain the adjacent material of the first layer 205 and increase the dimensions of the fenestrations to allow liquid movement through them, similar to the operation of a duckbill valve. Opening the perforations 215 can allow exudate and other liquid movement through the perforations 215 into the second layer 210. The second layer 210 can provide passage of negative pressure and exudate, which can be collected in the container 115. The perforations 215 located over the periwound 1820 may remain substantially closed, which can reduce or eliminate manifolding of fluid to the periwound 1820. The reduced or eliminated manifolding of fluid to the periwound 1820 may reduce or eliminate maceration of the periwound 1820.

[00123] Changes in pressure can also cause the second layer 210 to expand and contract. The first layer 205 can protect the epidermis 1805 from irritation that could be caused by expansion, contraction, or other movement of the second layer 210. The first layer 205 can also substantially reduce or prevent exposure of the wound 1800 to the second layer 210, which can inhibit growth of tissue into the second layer 210.

[00124] If the negative-pressure source 105 is removed or turned off, the pressure differential across the perforations 215 can dissipate, allowing the perforations 215 to close and prevent exudate or other liquid from returning to the wound 1800 through the first layer 205.

[00125] Additionally, or alternatively, instillation solution or other fluid may be distributed to the dressing 110, which can increase the pressure in the tissue interface 120. The increased pressure in the tissue interface 120 can create a positive pressure differential across the perforations 215 in the first layer 205, which can open the perforations 215 to allow the instillation solution or other fluid to be distributed to the wound 1800.

[00126] Figure 19 is a schematic diagram of another example of the therapy system 100 applied to the wound 1800 using the first layer 205 of Figure 7. In the example of Figure 19, the first layer 205 having sacrificial sections 700 is pushed into the wound 1800. The force of pushing the first layer 205 into the wound 1800 causes the sacrificial sections 700 to break, forming openings 1900. The breaking of the sacrificial sections 700 may allow the first layer 205 to conform to the shape of the wound 1800 and may reduce spring back of the first layer 205 away from the wound 1800. The openings 1900 formed by breaking the sacrificial sections 700 may function similar to the perforations 215. For example, negative pressure applied through the tissue interface 120 can also create a negative pressure differential across the openings 1900 in the first layer 205, which can further open or expand the openings 1900. A pressure gradient across the openings 1900 can strain the adjacent material of the first layer 205 and increase the dimensions of the openings 1900 to allow liquid movement through them, similar to the operation of a duckbill valve. Opening the openings 1900 can allow exudate and other liquid movement through the openings 1900 into the second layer 210. The second layer 210 can provide passage of negative pressure and exudate, which can be collected in the container 115. The openings 1900 may also allow instillation solution or other fluid to be distributed to the wound 1800. The openings 1900 may be sufficiently small to substantially reduce or prevent exposure of the wound 1800 to the second layer 210, which can inhibit growth of tissue into the second layer 210. The sacrificial sections 700 located over the periwound 1820 remain closed, which may prevent manifolding of fluid to the periwound 1820. The reduced or eliminated manifolding of fluid to the periwound 1820 may reduce or eliminate maceration of the periwound 1820.

[00127] Figure 20 is a schematic diagram of another example of the therapy system 100 applied to the tissue site. In the example of Figure 20, the second layer 210 may be sized and/or shaped to the size and shape of the wound 1800 and the first layer 205 may be may be wrapped around the second layer 210. If included, the third layer 405 or the fourth layer 410 may be disposed toward to the second layer 210 to couple the first layer 205 to the second layer 210. The third layer 405 or the fourth layer 410 may also adhere to itself. The second layer 210 enclosed by the first layer 205 may then be inserted into the wound 1800. The first layer 205 may not need to overlap the periwound 1820 as the first layer 205 encloses the second layer 210.

[00128] In some examples, the dressing 110 may include one or more attachment devices (not shown). In some embodiments, one or more of the attachment devices may comprise or consist essentially of an adhesive 2000. In some examples the adhesive 2000 may be, for example, a medically- acceptable, pressure -sensitive adhesive that extends about a periphery, a portion, or an entire surface of the cover 125. In some embodiments, for example, the adhesive 2000 may be an acrylic adhesive having a coating weight between 25-65 grams per square meter (g.s.m.). Thicker adhesives, or combinations of adhesives, may be applied in some embodiments to improve the seal and reduce leaks. In some embodiments, such a layer of the adhesive 2000 may be continuous or discontinuous. Discontinuities in the adhesive 2000 may be provided by apertures or holes (not shown) in the adhesive 2000. The apertures or holes in the adhesive 2000 may be formed after application of the adhesive 2000 or by coating the adhesive 2000 in patterns on a carrier layer, such as, for example, the cover 125. Apertures or holes in the adhesive 2000 may also be sized to enhance the MVTR of the attachment devices in some example embodiments. In some embodiments, one or more of the attachment devices may comprise or consist essentially of a composite strip of a perforated gel, substantially similar to the third layer 405, and a backing with an adhesive.

[00129] The adhesive 2000 can be disposed around edges of the cover 125, and may be pressed onto the cover 125 and the epidermis 1805 (or other attachment surface) to fix the dressing 110 in position and to seal the second layer 210.

[00130] The systems, apparatuses, and methods described herein may provide significant advantages. For example, the dressing 110 provides a highly flexible tissue interface layer that is non adherent to granulation, yet promotes granulation formation through its ability to manifold. Additionally, the dressing 110 can be simple to apply, reducing the time to apply and remove. For example, in some embodiments of the dressing 110, the first layer 205 may be used to overlap a periwound and may provide a barrier between the periwound and the second layer 210, which can significantly reduce or eliminate the need to size the second layer 210 for a wound. Additionally, the ability of the first layer 205 to be deformed to the contours of, and remain in contact with, a deep wound may ensure good contact between the first layer 205 and the wound bed throughout the course of negative-pressure therapy. The first layer 205 may be selectively deformed to allow full customization of the first layer 205 to a tissue site . Further, the third layer 405 and/or the fourth layer 410 coupled to the first layer 205 may allow the first layer 205 to be coupled to a patient and/or may allow the first layer 205 to be wrapped around the second layer 210 before the second layer 210 is used to fill a wound.

[00131] The benefits provided by the dressing 110 may include good manifolding, beneficial granulation, protection of the peripheral tissue from maceration, protection of the tissue site from shedding materials, and a low-trauma and high-seal bond. These characteristics may be particularly advantageous for surface wounds having moderate or high depth and medium -to-high levels of exudate. Some embodiments of the dressing 110 may remain on the tissue site for at least 5 days, and some embodiments may remain for at least 7 to 14 days. Antimicrobial agents in the dressing 110 may extend the usable life of the dressing 110 by reducing or eliminating infection risks that may be associated with extended use, particularly use with infected or highly exuding wounds.

[00132] Components of the dressing 110 may also be provided as one or more kits. In one embodiment, for example, a kit for forming a seal over a patient’s body may include a contact layer, a manifold, and a cover. The contact layer may include a plurality of sacrificial sections. The contact layer may be configured to extend over a wound and a periwound of the tissue site. At least some of the sacrificial sections are configured to open when the contact layer is pushed into the wound. The manifold may be configured to be adjacent to the contact layer. The cover may be configured to be disposed over the manifold and coupled to the contact layer around the manifold. In another embodiment, a kit for forming a seal over a patient’s body may include a perforated film, a manifold, and a cover. The perforated film may include a polymer and a plasticizer. The perforated film may be configured to extend over a wound and a periwound of the tissue site. The manifold may be configured to be adjacent to the perforated film. The cover may be configured to be disposed over the manifold and coupled to the perforated fdm around the manifold. In some embodiments, a kit for forming a seal over a patient’s body may include a plastomer fdm, a manifold, and a cover. The plastomer fdm may include a plurality of perforations. The plastomer fdm may be configured to extend over a wound and a periwound of the tissue site. The manifold may be configured to be adjacent to the plastomer fdm. The cover may be configured to be disposed over the manifold and coupled to the plastomer fdm around the manifold.

[00133] While shown in a few illustrative embodiments, a person having ordinary skill in the art will recognize that the systems, apparatuses, and methods described herein are susceptible to various changes and modifications that fall within the scope of the appended claims. Moreover, descriptions of various alternatives using terms such as “or” do not require mutual exclusivity unless clearly required by the context, and the indefinite articles “a” or “an” do not limit the subject to a single instance unless clearly required by the context. Components may be also be combined or eliminated in various configurations for purposes of sale, manufacture, assembly, or use. For example, in some configurations the dressing 110, the container 115, or both may be separated from other components for manufacture or sale. In other example configurations, the controller 130 may also be manufactured, configured, assembled, or sold independently of other components.

[00134] The appended claims set forth novel and inventive aspects of the subject matter described above, but the claims may also encompass additional subject matter not specifically recited in detail. For example, certain features, elements, or aspects may be omitted from the claims if not necessary to distinguish the novel and inventive features from what is already known to a person having ordinary skill in the art. Features, elements, and aspects described in the context of some embodiments may also be omitted, combined, or replaced by alternative features serving the same, equivalent, or similar purpose without departing from the scope of the invention defined by the appended claims.

Claims

CLAIMS What is claimed is:

1. A dressing for treating a tissue site with negative pressure, the dressing comprising: a contact layer including a plurality of sacrificial sections, the contact layer configured to extend over a wound and a periwound of the tissue site, and wherein at least some of the sacrificial sections are configured to open when the contact layer is pushed into the wound; a manifold configured to be adjacent to the contact layer; and a cover configured to be disposed over the manifold and coupled to the contact layer around the manifold.

2. The dressing of claim 1, wherein the contact layer comprises a film.

3. The dressing of any of claims 1-2, wherein the contact layer comprises polyurethane.

4. The dressing of any of claims 1-2, wherein the contact layer has a first thickness and the sacrificial sections have a second thickness, wherein the second thickness is in a range of about 10% to about 70% of the first thickness.

5. The dressing of any of claims 1-2, wherein the contact layer has a first thickness and the sacrificial sections have a second thickness, wherein the second thickness is about 50% of the first thickness.

6. The dressing of any of claims 1-5, wherein the sacrificial sections are distributed across the contact layer.

7. The dressing of any of claims 1-6, wherein the sacrificial sections are circular.

8. The dressing of claim 7, wherein the sacrificial sections have a diameter in a range of about 0.5 millimeters to about 5 millimeters.

9. The dressing of claim 7, wherein the sacrificial sections have a diameter of about 0.8 millimeters.

10. The dressing of any of claims 1-9, wherein the contact layer further comprises a plurality of perforations.

11. The dressing of claim 10, wherein the perforations comprise slits in the contact layer.

12. The dressing of claim 11, wherein the slits each have a length in a range of about 2 millimeters to about 5 millimeters.

13. The dressing of claim 11, wherein the slits each have a length of about 3 millimeters.

14. The dressing of any of claims 10-13, wherein the plurality of sacrificial sections and the plurality of perforations are uniformly distributed across the contact layer.

15. The dressing of any of claims 10-14, wherein the contact layer comprises a first region and a second region, the plurality of sacrificial sections located in the first region and the perforations located in the second region.

16. The dressing of claim 15, wherein the second region surrounds the first region.

17. The dressing of claim 15, wherein the first region is centrally located on the contact layer and the second region surrounds the first region.

18. The dressing of claim 15, wherein the first region is configured to be located proximate the wound and the second region is configured to be located proximate the periwound.

19. The dressing of any of claims 1-18, wherein the contact layer comprises a first side configured to face the tissue site and second side configured to face the manifold.

20. The dressing of claim 19, wherein the contact layer comprises an adhesive on the first side.

21. The dressing of any of claims 19-20, wherein the contact layer comprises an adhesive on the second side.

22. The dressing of any of claims 19-21, wherein the contact layer comprises one or more micro hooks on the second side.

23. The dressing of any of claims 19-21, wherein the second side of the contact layer is flocked.

24. The dressing of any of claims 1-23, wherein the contact layer is deformable to the shape of the wound.

25. The dressing of any of claims 1-24, wherein the contact layer comprises a film comprising a polymer and a plasticizer.

26. The dressing of claim 25, wherein the polymer comprises polyurethane.

27. The dressing of claim 25, wherein the polymer comprises elastane.

28. The dressing of claim 25, wherein the polymer comprises polybutene.

29. The dressing of claim 25, wherein the polymer comprises polyolefin.

30. The dressing of claim 25, wherein the polymer comprises a plastomer.

31. The dressing of claim 30, wherein the plastomer comprises an ethylene alpha olefin copolymer.

32. The dressing of claim 30, wherein the plastomer comprises octene comonomer and polyethylene.

33. The dressing of any of claims 25-32, wherein the plasticizer comprises a low molecular mass oil.

34. The dressing of any of claims 25-32, wherein the plasticizer comprises benzoic acid.

35. The dressing of any of claims 25-32, wherein the plasticizer comprises 1,2-cyclohexane dicarboxylic acid diisononyl ester.

36. The dressing of any of claims 25-32, wherein the plasticizer comprises an aliphatic ester.

37. The dressing of any of claims 25-36, wherein loading of the plasticizer is up to 60% w/w.

38. The dressing of any of claims 1-24, wherein the contact layer comprises a plastomer film.

39. The dressing of claim 38, wherein the plastomer film comprises an ethylene alpha olefin copolymer.

40. The dressing of claim 38, wherein the plastomer film comprises octene comonomer and polyethylene.

41. A dressing for treating a tissue site with negative pressure, the dressing comprising: a perforated film comprising a polymer and a plasticizer, the perforated film configured to extend over a wound and a periwound of the tissue site; a manifold configured to be adjacent to the perforated film; and a cover configured to be disposed over the manifold and coupled to the perforated film around the manifold.

42. The dressing of claim 41, wherein the polymer comprises polyurethane.

43. The dressing of claim 41, wherein the polymer comprises elastane.

44. The dressing of claim 41, wherein the polymer comprises polybutene.

45. The dressing of claim 41, wherein the polymer comprises polyolefin.

46. The dressing of claim 41, wherein the polymer comprises a plastomer.

47. The dressing of claim 46, wherein the plastomer comprises an ethylene alpha olefin copolymer.

48. The dressing of claim 46, wherein the plastomer comprises octene comonomer and polyethylene.

49. The dressing of any of claims 41-48, wherein the plasticizer comprises a low molecular mass oil.

50. The dressing of any of claims 41-48, wherein the plasticizer comprises benzoic acid.

51. The dressing of any of claims 41-48, wherein the plasticizer comprises 1,2-cyclohexane dicarboxylic acid diisononyl ester.

52. The dressing of any of claims 41-48, wherein the plasticizer comprises an aliphatic ester.

53. The dressing of any of claims 41-52, wherein loading of the plasticizer is up to 60% w/w.

54. The dressing of any of claims 41-53, wherein the perforated film has a thickness in a range of about 10 microns to about 100 microns.

55. The dressing of any of claims 41-53, wherein the perforated film has a thickness of about 30 microns.

56. The dressing of any of claims 41-55, wherein the perforated film has a moisture vapor transmission rate of at least 250 g/m²/24 hrs.

57. The dressing of any of claims 41-56, wherein the perforated film comprises a first side configured to face the tissue site and second side configured to face the manifold.

58. The dressing of claim 57, wherein the perforated film comprises an adhesive on the first side.

59. The dressing of any of claims 57-58, wherein the perforated film comprises an adhesive on the second side.

60. The dressing of any of claims 41-59, wherein the perforated film includes a plurality of sacrificial sections, wherein at least some of the sacrificial sections are configured to open when the contact layer is pushed into the wound

61. The dressing of any of claims 60, wherein the perforated film has a first thickness and the sacrificial sections have a second thickness, wherein the second thickness is in a range of about 10% to about 70% of the first thickness.

62. The dressing of any of claims 60, wherein the perforated film has a first thickness and the sacrificial sections have a second thickness, wherein the second thickness is about 50% of the first thickness.

63. The dressing of any of claims 60-62, wherein the sacrificial sections are distributed across the perforated film.

64. The dressing of any of claims 60-63, wherein the sacrificial sections are circular.

65. The dressing of claim 64, wherein the sacrificial sections have a diameter in a range of about 0.5 millimeters to about 5 millimeters.

66. The dressing of claim 64, wherein the sacrificial sections have a diameter of about 0.8 millimeters.

67. A dressing for treating a tissue site with negative pressure, the dressing comprising: a plastomer film comprising a plurality of perforations, the plastomer film configured to extend over a wound and a periwound of the tissue site; a manifold configured to be adjacent to the plastomer film; and a cover configured to be disposed over the manifold and coupled to the plastomer film around the manifold.

68. The dressing of claim 67, wherein the plastomer film comprises an ethylene alpha olefin copolymer.

69. The dressing of claim 67, wherein the plastomer film comprises octene comonomer and polyethylene.

70. The dressing of any of claims 67-69, wherein the plastomer film includes a plurality of sacrificial sections, wherein at least some of the sacrificial sections are configured to open when the contact layer is pushed into the wound

71. The dressing of any of claims 70, wherein the plastomer film has a first thickness and the sacrificial sections have a second thickness, wherein the second thickness is in a range of about 10% to about 70% of the first thickness.

72. The dressing of any of claims 70, wherein the plastomer film has a first thickness and the sacrificial sections have a second thickness, wherein the second thickness is about 50% of the first thickness.

73. The dressing of any of claims 70-72, wherein the sacrificial sections are distributed across the plastomer film.

74. The dressing of any of claims 70-72, wherein the sacrificial sections are circular.

75. The dressing of claim 74, wherein the sacrificial sections have a diameter in a range of about 0.5 millimeters to about 5 millimeters.

76. The dressing of claim 74, wherein the sacrificial sections have a diameter of about 0.8 millimeters.

77. A method of applying a dressing to a tissue site, the method comprising: applying a contact layer over the tissue site so that the contact layer extends over a wound and a periwound of the tissue site, the contact layer including a plurality of sacrificial sections, wherein applying the contact layer over the tissue site includes pushing the contact layer into the wound and causing one or more of the sacrificial sections to break open; filling the wound with a manifold; and applying a cover over the manifold and at least a portion of the contact layer to form a sealed space containing the contact layer and the manifold.

78. A method of applying a dressing to a tissue site, the method comprising: applying a contact layer over the tissue site so that the contact layer extends over a wound and a periwound of the tissue site, the contact layer comprising a plurality of perforations, wherein applying the contact layer over the tissue site includes pushing the contact layer into the wound; filling the wound with a manifold; and applying a cover over the manifold and at least a portion of the contact layer to form a sealed space containing the contact layer and the manifold, the cover comprising a film.

79. The method of claim 78, wherein the perforations are configured to expand in response to a pressure gradient across the contact layer.

80. The method of any of claims 78-79, wherein the perforations comprise slits in the contact layer.

81. The method of any of claims 78-80, wherein the contact layer comprises a film comprising a polymer and a plasticizer.

82. The method of claim 81, wherein the polymer comprises polyurethane.

83. The method of claim 81, wherein the polymer comprises elastane.

84. The method of claim 81, wherein the polymer comprises polybutene.

85. The method of claim 81, wherein the polymer comprises polyolefin.

86. The method of claim 81, wherein the polymer comprises a plastomer.

87. The method of claim 86, wherein the plastomer comprises an ethylene alpha olefin copolymer.

88. The method of claim 86, wherein the plastomer comprises octene comonomer and polyethylene.

89. The method of any of claims 81-88, wherein the plasticizer comprises a low molecular mass oil.

90. The method of any of claims 81-88, wherein the plasticizer comprises benzoic acid.

91. The method of any of claims 81-88, wherein the plasticizer comprises 1,2-cyclohexane dicarboxylic acid diisononyl ester.

92. The method of any of claims 81-88, wherein the plasticizer comprises an aliphatic ester.

93. The method of any of claims 81-92, wherein loading of the plasticizer is up to 60% w/w.

94. The method of any of claims 78-80, wherein the contact layer comprises a film comprising a plastomer.

95. The method of claim 94, wherein the plastomer comprises an ethylene alpha olefin copolymer.

96. The method of claim 94, wherein the plastomer comprises octene comonomer and polyethylene.

97. The method of any of claims 78-96, wherein the contact layer comprises a plurality of sacrificial sections.

98. The method of claim 97, wherein the sacrificial sections are configured to open when deformed.

99. The method of any of claims 78-98, wherein the contact layer comprises a first side configured to face the tissue site and second side configured to face the manifold.

100. The method of claim 99, wherein the first side of the contact layer is coated with an adhesive.

101. The method of any of claims 99-100, wherein the second side of the contact layer is coated with an adhesive.

102. The method of any of claims 99-101, wherein the second side of the contact layer comprises hooks configured to engage with the manifold.

103. The method of any of claims 99-102, wherein the second side of the contact layer is flocked.

104. The method of any of claims 78-103, wherein the contact layer is deformable to the shape of the wound.

105. The method of any of claims 78-104, wherein the contact layer has a moisture vapor transmission rate of at least 250 g/m²/24 hrs.

106. A method of applying a dressing to a tissue site, the method comprising: cutting a manifold to fit a wound of the tissue site; wrapping the manifold with a contact layer comprising a plurality of perforations; filling the wound with the contact layer-wrapped manifold; and applying a cover over the contact layer-wrapped manifold to form a sealed space containing the contact layer-wrapped manifold, the cover comprising a film.

107. A kit for forming a seal over a portion of a patient’s body, the kit comprising: a contact layer including a plurality of sacrificial sections, the contact layer configured to extend over a wound and a periwound of a tissue site, and wherein at least some of the sacrificial sections are configured to open when the contact layer is pushed into the wound; a manifold configured to be adjacent to the contact layer; and a cover configured to be disposed over the manifold and coupled to the contact layer around the manifold.

108. A kit for forming a seal over a portion of a patient’s body, the kit comprising: a perforated film comprising a polymer and a plasticizer, the perforated film configured to extend over a wound and a periwound of a tissue site; a manifold configured to be adjacent to the perforated film; and a cover configured to be disposed over the manifold and coupled to the perforated film around the manifold.

109. A kit for forming a seal over a portion of a patient’s body, the kit comprising: a plastomer film comprising a plurality of perforations, the plastomer film configured to extend over a wound and a periwound of a tissue site; a manifold configured to be adjacent to the plastomer film; and a cover configured to be disposed over the manifold and coupled to the plastomer film around the manifold.

110. The systems, apparatuses, and methods substantially as described herein.