RELATED APPLICATION

[0001] The present application claims priority to U.S. Provisional Patent Application No. 62/866,305, entitled“SYSTEM AND METHOD FOR ADMINISTERING NEGATIVE- PRESSURE TREATMENT USING A FLOW ABLE TISSUE DRESSING MATERIAL,” filed June 25, 2019, which is incorporated herein by reference for all purposes.

TECHNICAL FIELD

[0002] The invention set forth in the appended claims relates generally to tissue treatment systems and more particularly, but without limitation, to methods and systems for administering negative-pressure therapy to a tissue site including delivering a flowable tissue dressing material from a delivery device and solidifying the flowable tissue dressing material to form an open cell foam manifold having a plurality of flow channels through which negative-pressure may be applied.

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 a tissue site 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 method for administering negative- pressure therapy to a tissue site is described. More generally, the method includes positioning a cover adjacent to the tissue site and delivering a flowable tissue dressing material from a delivery device to the tissue site. The method further includes solidifying the flowable tissue dressing material to form an open cell foam manifold having a plurality of flow channels in fluid communication with the tissue site, and applying a negative-pressure to the tissue site through the plurality of flow channels via a tissue dressing material delivery tube or a manifold delivery tube. In some embodiments, the method may include positioning a distal end of the tissue dressing material delivery tube beneath the cover and adjacent to the tissue site for delivering the flowable tissue dressing material.

[0008] In some embodiments, a negative-pressure source for applying the negative- pressure can be in fluid communication with the tissue dressing material delivery tube and/or the manifold delivery tube. The delivery device can be physically separate from the negative- pressure source or the delivery device can be in fluid communication with the negative- pressure source.

[0009] In some embodiments, the flowable tissue dressing material can be formed in the delivery device by mixing a first reactant with a second reactant to form the flowable tissue dressing material. The first reactant can be, for example, a polyol, polyaldehyde, or a polyamine. The second reactant can be, for example, a multi-isocyanate, a multi-isocyanate prepolymer, a polycarbamate, a polycarboxylic acid, or an anhydride.

[0010] In some embodiments, prior to mixing, the first reactant can be present in a first zone and the second reactant can be present in a second zone in the device, wherein the first zone is physically separate from the second zone.

[0011] In some embodiments, the first zone may be a first container and the second zone may be a second container. In other embodiments, the first zone and the second zone can be present in a single container having a wall defined therein, which separates the first zone and the second zone. The wall can be at least partially removable to allow for mixing between the first reactant and the second reactant to form the flowable tissue dressing material.

[0012] In some embodiments, the delivery device can further include a third zone for mixing the first reactant with the second reactant to form the flowable tissue dressing material and/or for delivering the flowable tissue dressing material. The third zone can be physically separate from the first zone and the second zone.

[0013] In some alternative embodiments, the delivery device can include the flowable tissue dressing material including a reacted polymer present in a carrier. The reacted polymer may be, for example, a polyurethane, a polyester, a polyamide, an acrylic polymer, an acrylate polymer, a polyvinyl acetate, a polysiloxane, or a combination thereof. The carrier may be, for example, a low boiling point liquid, water, a compressed gas, or a combination thereof.

[0014] Alternatively, other example embodiments may include another method for administering negative-pressure therapy to a tissue site. The method includes positioning a cover adjacent to the tissue site and delivering a flowable hydrophilic tissue dressing material from a delivery device to the tissue site. The method further includes solidifying the flowable hydrophilic tissue dressing material to form an open cell foam manifold having a plurality of flow channels in fluid communication with the tissue site, and applying a negative-pressure to the tissue site through the plurality of flow channels via a tissue dressing material delivery tube or a manifold delivery tube. In some embodiments, the method may include positioning a distal end of the tissue dressing material delivery tube beneath the cover and adjacent to the tissue site for delivering the flowable tissue dressing material.

[0015] In some embodiments, the delivery device includes the flowable hydrophilic tissue dressing material including a reacted polymer, for example, a hydrophilic reacted polymer, present in a carrier. The reacted polymer may be, for example, polyvinylpyrrolidone (PVP), a polyvinyl alcohol, polyethylene oxide (PEO), hydrophilicly- modified polyurethane, or a combination thereof. The carrier may be, for example, a low boiling point liquid, water, a compressed gas, or a combination thereof.

[0016] Alternatively, other example embodiments may include a tissue dressing apparatus. The tissue dressing apparatus can include a delivery device for delivering a flowable tissue dressing material and a cover in fluid communication with the delivery device. The delivery device can include a first zone including a first reactant and a second zone including a second reactant, where the first zone is physically separate from the second zone. The first reactant can be, for example, a polyol, polyaldehyde, or a polyamine. The second reactant can be, for example, a multi-isocyanate, a multi-isocyanate prepolymer, a polycarbamate, a polycarboxylic acid, or an anhydride. Alternatively, the delivery device can include the flowable tissue dressing material including a reacted polymer present in a carrier. The reacted polymer can be, for example, a polyurethane, a polyester, a polyamide, an acrylic polymer, an acrylate polymer, a polyvinyl acetate, a polysiloxane, or a combination thereof. The carrier can be, for example, a low boiling point liquid, water, a compressed gas, or a combination thereof.

[0017] In some embodiments, the first zone may be a first container and the second zone may be a second container. In other embodiments, the first zone and the second zone can be present in a single container having a wall defined therein, which separates the first zone and the second zone. The wall can be at least partially removable to allow for mixing between the first reactant and the second reactant to form the flowable tissue dressing material.

[0018] In some embodiments, the tissue dressing apparatus can further include a negative-pressure source in fluid communication with the tissue dressing apparatus.

[0019] Alternatively, other example embodiments may include another tissue dressing apparatus. The tissue dressing apparatus can include a delivery device for delivering a flowable hydrophilic tissue dressing material and a cover in fluid communication with the delivery device. The delivery device can include the flowable hydrophilic tissue dressing material including a reacted polymer present in a carrier. The reacted polymer can be, for example, polyvinylpyrrolidone (PVP), a polyvinyl alcohol, polyethylene oxide (PEO), hydrophilicly-modified polyurethane, or a combination thereof. The carrier can be, for example, a low boiling point liquid, water, a compressed gas, or a combination thereof.

[0020] In some embodiments, the tissue dressing apparatus can further include a negative-pressure source in fluid communication with the tissue dressing apparatus.

[0021] 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

[0022] 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;

[0023] Figure 2 is a graph illustrating additional details of example pressure control modes that may be associated with some embodiments of the therapy system of Figure 1;

[0024] Figure 3 is a graph illustrating additional details that may be associated with another example pressure control mode in some embodiments of the therapy system of Figure l ;

[0025] Figure 4 is a chart illustrating details that may be associated with an example method of operating the therapy system of Figure 1;

[0026] Figure 5A is a front view, illustrating details of a therapy system that can provide negative-pressure treatment in accordance with this specification;

[0027] Figure 5B is a front view, illustrating additional details that may be associated with the therapy system in Figure 5A;

[0028] Figure 6 is a front view, illustrating details that may be associated with some alternative embodiments of a therapy system that can provide negative-pressure treatment in accordance with this specification;

[0029] Figure 7A is a cross-sectional view, illustrating details that may be associated with some embodiments of a delivery device having a first zone and a second zone;

[0030] Figure 7B is a cross-sectional view, illustrating details that may be associated with some alternative embodiments of a delivery device having a first zone, a second zone, and a third zone;

[0031] Figure 7C is a cross-sectional view, illustrating details that may be associated with some alternative embodiments of a delivery device having a first zone, a second zone, and a third zone;

[0032] Figure 7D is a cross-sectional view, illustrating details that may be associated with some alternative embodiments of a delivery device having a first zone, a second zone, and a canister;

[0033] Figure 7E is a cross-sectional view, illustrating details that may be associated with some alternative embodiments of a delivery device having a first zone, a second zone, and a ultraviolet light source;

[0034] Figure 8 is a cross-sectional view, illustrating details that may be associated with some alternative embodiments of a delivery device having a first zone, a second zone, and a third zone; and

[0035] Figure 9 is a cross-sectional view, illustrating details that may be associated with some alternative embodiments of a delivery device having a single container.

DESCRIPTION OF EXAMPLE EMBODIMENTS

[0036] 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.

[0037] 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.

[0038] Figure 1 is a simplified functional block diagram of an example embodiment of a therapy system 10 that can provide negative-pressure therapy, optionally with instillation of topical treatment solutions to a tissue site in accordance with this specification. [0039] The term“tissue site” in this context broadly refers to a wound, defect, or other treatment target located on or within tissue, including, but not limited to, bone tissue, adipose tissue, muscle tissue, neural tissue, dermal tissue, vascular tissue, connective tissue, cartilage, tendons, or ligaments. A wound may include chronic, acute, traumatic, subacute, and dehisced wounds, partial-thickness bums, ulcers (such as diabetic, pressure, or venous insufficiency ulcers), flaps, and grafts, for example. The term“tissue site” may also refer to areas of any tissue that are not necessarily wounded or defective, but are instead areas in which it may be desirable to add or promote the growth of additional tissue. For example, negative pressure may be applied to a tissue site to grow additional tissue that may be harvested and transplanted.

[0040] The therapy system 10 may include a source or supply of negative pressure, such as a negative-pressure source 18, 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 5, and a fluid container, such as a container 11, are examples of distribution components that may be associated with some examples of the therapy system 10. As illustrated in the example of Figure 1, the dressing 5 may comprise or consist essentially of a tissue interface 7, a cover 9, or both in some embodiments.

[0041] 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 5. For example, such a dressing interface may be a SENSAT.R.A.C.™ Pad available from Kinetic Concepts, Inc. of San Antonio, Texas.

[0042] The therapy system 10 may also include a regulator or controller, such as a controller 13. Additionally, the therapy system 10 may include sensors to measure operating parameters and provide feedback signals to the controller 13 indicative of the operating parameters. As illustrated in Figure 1, for example, the therapy system 10 may include a first sensor 12 and a second sensor 14 coupled to the controller 13. [0043] The therapy system 10 may also include a source of instillation solution. For example, a solution source 16 may be fluidly coupled to the dressing 5, as illustrated in the example embodiment of Figure 1. The solution source 16 may be fluidly coupled to a positive-pressure source, such as a positive-pressure source 15, a negative-pressure source such as the negative-pressure source 18, or both in some embodiments. A regulator, such as an instillation regulator 17, may also be fluidly coupled to the solution source 16 and the dressing 5 to ensure proper dosage of instillation solution (e.g. saline) to a tissue site. For example, the instillation regulator 17 may comprise a piston that can be pneumatically actuated by the negative-pressure source 18 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 13 may be coupled to the negative-pressure source 18, the positive-pressure source 15, or both, to control dosage of instillation solution to a tissue site. In some embodiments, the instillation regulator 17 may also be fluidly coupled to the negative-pressure source 18 through the dressing 5, as illustrated in the example of Figure 1.

[0044] Some components of the therapy system 10 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 18 may be combined with the controller 13, the solution source 16, and other components into a therapy unit.

[0045] In general, components of the therapy system 10 may be coupled directly or indirectly. For example, the negative-pressure source 18 may be directly coupled to the container 11 and may be indirectly coupled to the dressing 5 through the container 11. 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 18 may be electrically coupled to the controller 13 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.

[0046] A negative-pressure supply, such as the negative-pressure source 18, 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 18 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).

[0047] The container 11 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.

[0048] A controller, such as the controller 13, may be a microprocessor or computer programmed to operate one or more components of the therapy system 10, such as the negative-pressure source 18. In some embodiments, for example, the controller 13 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 10. Operating parameters may include the power applied to the negative-pressure source 18, the pressure generated by the negative-pressure source 18, or the pressure distributed to the tissue interface 7, for example. The controller 13 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.

[0049] Sensors, such as the first sensor 12 and the second sensor 14, 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 12 and the second sensor 14 may be configured to measure one or more operating parameters of the therapy system 10. In some embodiments, the first sensor 12 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 12 may be a piezo-resistive strain gauge. The second sensor 14 may optionally measure operating parameters of the negative-pressure source 18, such as a voltage or current, in some embodiments. Preferably, the signals from the first sensor 12 and the second sensor 14 are suitable as an input signal to the controller 13, 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 13. Typically, the signal is an electrical signal, but may be represented in other forms, such as an optical signal.

[0050] The tissue interface 7 can be generally adapted to partially or fully contact a tissue site. The tissue interface 7 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 7 may be adapted to the contours of deep and irregular shaped tissue sites. Any or all of the surfaces of the tissue interface 7 may have an uneven, coarse, or jagged profile.

[0051] In some embodiments, the tissue interface 7 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 7 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 7, 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.

[0052] In some illustrative embodiments, a manifold may comprise a plurality of pathways, which can be interconnected to improve distribution or collection of fluids. In some illustrative embodiments, a manifold may comprise or consist essentially of a porous material having interconnected fluid pathways. Examples of suitable porous material that can be adapted to form interconnected fluid pathways (e.g., channels) may include cellular foam, including open-cell foam such as reticulated foam; porous tissue collections; and other porous material such as gauze or felted mat that generally include pores, edges, and/or walls. Liquids, gels, and other foams may also include or be cured to include apertures and fluid pathways. In some embodiments, a manifold may additionally or alternatively comprise projections that form interconnected fluid pathways. For example, a manifold may be molded to provide surface projections that define interconnected fluid pathways.

[0053] In some embodiments, the tissue interface 7 may comprise or consist essentially of reticulated foam having pore sizes and free volume that may vary according to needs of a prescribed therapy. For example, reticulated foam having a free volume of at least 90% may be suitable for many therapy applications, and foam having an average pore size in a range of 400-600 microns (40-50 pores per inch) may be particularly suitable for some types of therapy. The tensile strength of the tissue interface 7 may also vary according to needs of a prescribed therapy. For example, the tensile strength of foam may be increased for instillation of topical treatment solutions. The 25% compression load deflection of the tissue interface 7 may be at least 0.35 pounds per square inch, and the 65% compression load deflection may be at least 0.43 pounds per square inch. In some embodiments, the tensile strength of the tissue interface 120 may be at least 10 pounds per square inch. The tissue interface 7 may have a tear strength of at least 2.5 pounds per inch. In some embodiments, the tissue interface may be foam comprised of polyols such as polyester or polyether, isocyanate such as toluene diisocyanate, and polymerization modifiers such as amines and tin compounds. In some examples, the tissue interface 7 may be reticulated polyurethane foam such as found in GRANUFOAM™ dressing or V.A.C. VERAFLO™ dressing, both available from Kinetic Concepts, Inc. of San Antonio, Texas.

[0054] The thickness of the tissue interface 7 may also vary according to needs of a prescribed therapy. For example, the thickness of the tissue interface may be decreased to reduce tension on peripheral tissue. The thickness of the tissue interface 7 can also affect the conformability of the tissue interface 7. In some embodiments, a thickness in a range of about 5 millimeters to 10 millimeters may be suitable.

[0055] The tissue interface 7 may be either hydrophobic or hydrophilic. In an example in which the tissue interface 7 may be hydrophilic, the tissue interface 7 may also wick fluid away from a tissue site, while continuing to distribute negative pressure to the tissue site. The wicking properties of the tissue interface 7 may draw fluid away from a tissue site by capillary flow or other wicking mechanisms. An example of a hydrophilic material that may be suitable is a polyvinyl alcohol, open-cell foam such as V.A.C. WHITEFOAM™ dressing available from Kinetic Concepts, Inc. of San Antonio, Texas. Other hydrophilic foams may include those made from polyether. Other foams that may exhibit hydrophilic characteristics include hydrophobic foams that have been treated or coated to provide hydrophilicity.

[0056] In some embodiments, the tissue interface 7 may be constructed from bioresorbable materials. Suitable bioresorbable materials may include, without limitation, a polymeric blend of polylactic acid (PLA) and poly glycolic acid (PGA). The polymeric blend may also include, without limitation, polycarbonates, polyfumarates, and capralactones. The tissue interface 7 may further serve as a scaffold for new cell-growth, or a scaffold material may be used in conjunction with the tissue interface 7 to promote cell-growth. A scaffold is generally a substance or structure used to enhance or promote the growth of cells or formation of tissue, such as a three-dimensional porous structure that provides a template for cell growth. Illustrative examples of scaffold materials include calcium phosphate, collagen, PLA/PGA, coral hydroxy apatites, carbonates, or processed allograft materials.

[0057] In some embodiments, the cover 9 may provide a bacterial barrier and protection from physical trauma. The cover 9 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 9 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 9 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 9 may be a polymer drape, such as a polyurethane film, that is permeable to water vapor but impermeable to liquid. Such drapes typically have a thickness in the range of 25-50 microns. For permeable materials, the permeability generally should be low enough that a desired negative pressure may be maintained. The cover 9 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, commercially available from Avery Dennison Corporation, Pasadena, California; polyether block polyamide copolymer (PEBAX), for example, from Arkema S.A., Colombes, France; and Inspire 2301 and Inpsire 2327 polyurethane films, commercially available from Expopack Advanced Coatings, Wrexham, United Kingdom. In some embodiments, the cover 9 may comprise INSPIRE 2301 having an MVTR (upright cup technique) of 2600 g/m ² /24 hours and a thickness of about 30 microns.

[0059] An attachment device may be used to attach the cover 9 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, pres sure- sensitive adhesive configured to bond the cover 9 to epidermis around a tissue site. In some embodiments, for example, some or all of the cover 9 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. In some embodiments, the cover 9 may not include an adhesive and the flowable tissue dressing material (further described below) may provide a seal or adhesion to a tissue site.

[0060] The solution source 16 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 7 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 7 may partially or completely fill the wound, or it may be placed over the wound. The cover 9 may be placed over the tissue interface 7 and sealed to an attachment surface near a tissue site. For example, the cover 9 may be sealed to undamaged epidermis peripheral to a tissue site. Thus, the dressing 5 can provide a sealed therapeutic environment proximate to a tissue site, substantially isolated from the external environment, and the negative- pressure source 18 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 7 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 11.

[0065] In some embodiments, the controller 13 may receive and process data from one or more sensors, such as the first sensor 12. The controller 13 may also control the operation of one or more components of the therapy system 10 to manage the pressure delivered to the tissue interface 7. In some embodiments, controller 13 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 7. 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 13. 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 13 can operate the negative-pressure source 18 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 7.

[0066] Figure 2 is a graph illustrating additional details of an example control mode that may be associated with some embodiments of the controller 13. In some embodiments, the controller 13 may have a continuous pressure mode, in which the negative-pressure source 18 is operated to provide a constant target negative pressure, as indicated by line 205 and line 208, for the duration of treatment or until manually deactivated. Additionally or alternatively, the controller may have an intermittent pressure mode, as illustrated in the example of Figure 2. In Figure 2, the x-axis represents time and the y-axis represents negative pressure generated by the negative-pressure source 18 over time. In the example of Figure 2, the controller 13 can operate the negative-pressure source 18 to cycle between a target pressure and atmospheric pressure. For example, the target pressure may be set at a value of 135 mmHg, as indicated by line 205, for a specified period of time (e.g., 5 min), followed by a specified period of time (e.g., 2 min) of deactivation, as indicated by the gap between the solid lines 215 and 218. The cycle can be repeated by activating the negative- pressure source 18, as indicated by line 218, 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 18 and the dressing 5 may have an initial rise time, as indicated by the dashed line 225. The initial rise time may vary depending on the type of dressing and therapy equipment being used. For example, the initial rise time for one therapy system may be in a range of about 20-30 mmHg/second and in a range of about 5-10 mmHg/second for another therapy system. If the therapy system 10 is operating in an intermittent mode, the repeating rise time, as indicated by the solid line 218, may be a value substantially equal to the initial rise time as indicated by the dashed line 225.

[0068] Figure 3 is a graph illustrating additional details that may be associated with another example pressure control mode in some embodiments of the therapy system 10. In Figure 3, the x-axis represents time and the y-axis represents negative pressure generated by the negative-pressure source 18. The target pressure in the example of Figure 3 can vary with time in a dynamic pressure mode. For example, the target pressure may vary in the form of a triangular waveform, varying between a negative pressure of 50 and 135 mmHg with a rise time 308 set at a rate of +25 mmHg/min. and a descent time 310 set at -25 mmHg/min. In other embodiments of the therapy system 10, the triangular waveform may vary between negative pressure of 25 and 135 mmHg with a rise time 308 set at a rate of +30 mmHg/min and a descent time 310 set at -30 mmHg/min.

[0069] In some embodiments, the controller 13 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 13, 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] Figure 4 is a chart illustrating details that may be associated with an example method 400 of operating the therapy system 10 to provide negative-pressure treatment and instillation treatment to the tissue interface 7. In some embodiments, the controller 13 may receive and process data, such as data related to instillation solution provided to the tissue interface 7. 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 13 may also control the operation of one or more components of the therapy system 10 to instill solution, as indicated at 405. For example, the controller 13 may manage fluid distributed from the solution source 16 to the tissue interface 7. In some embodiments, fluid may be instilled to a tissue site by applying a negative pressure from the negative-pressure source 18 to reduce the pressure at the tissue site, drawing solution into the tissue interface 7, as indicated at 410. In some embodiments, solution may be instilled to a tissue site by applying a positive pressure from the positive-pressure source 15 to move solution from the solution source 16 to the tissue interface 7, as indicated at 415. Additionally or alternatively, the solution source 16 may be elevated to a height sufficient to allow gravity to move solution into the tissue interface 7, as indicated at 420. [0071] The controller 13 may also control the fluid dynamics of instillation at 425 by providing a continuous flow of solution at 430 or an intermittent flow of solution at 435. Negative pressure may be applied to provide either continuous flow or intermittent flow of solution at 440. The application of negative pressure may be implemented to provide a continuous pressure mode of operation at 445 to achieve a continuous flow rate of instillation solution through the tissue interface 7, or it may be implemented to provide a dynamic pressure mode of operation at 450 to vary the flow rate of instillation solution through the tissue interface 7. Alternatively, the application of negative pressure may be implemented to provide an intermittent mode of operation at 455 to allow instillation solution to dwell at the tissue interface 7. 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 at 460. The controller 13 may be utilized to select a mode of operation and the duration of the negative pressure treatment before commencing another instillation cycle at 465 by instilling more solution at 405.

[0072] Methods and apparatuses for administering negative-pressure therapy to a tissue site, for example, via the therapy system 10 are also provided herein. For example, a tissue dressing apparatus is described herein, which can include a delivery device as described herein, which can deliver a flowable tissue dressing material, which can readily conform to the size and shape of the tissue site to form the tissue interface 7. As used herein, the term“flowable” refers to an ability of a substance to be transported by gravity or under pressure from a storage vessel to a tissue site. Examples of a“flowable” substance include, but are not limited to a liquid, a gel, a slurry, a suspension, an aerosol, and any combination thereof. As used herein, the term“flowable tissue dressing material,” can refer to a flowable hydrophilic tissue dressing material, a flowable hydrophobic tissue dressing material, or both. Thus, the methods, apparatuses, and devices described herein can form tissue dressings in various configurations.

[0073] As illustrated in Figure 5A, a tissue dressing apparatus may include a cover 9 and the method may include positioning a cover 9 adjacent to a tissue site 50. A distal end 55 of a tissue dressing material delivery tube 60 can be positioned beneath the cover 9, for example, under the cover 9 or through a delivery port (not shown), optionally present in the cover 9, and adjacent to the tissue site 50. A flowable tissue dressing material from a delivery device 100 can be delivered, for example, through the tissue dressing material delivery tube 60 to the tissue site 50, for example, into a void space 65, such as a wound space. The tissue dressing material delivery tube 60 can in fluid communication with the delivery device 100, for example via a delivery port (not shown). In any embodiment, the flowable tissue dressing material may be poured, injected, or sprayed onto or into a tissue site, for example, with or without use of the tissue dressing material delivery tube 60. It is contemplated herein that a flowable tissue dressing material may be delivered through the tissue dressing material delivery tube 60 to the tissue site 50 and then a cover 9 may be positioned over the flowable tissue dressing material and tissue site 50. In some embodiments, the tissue site 50 can include an internal site ( e.g ., void space 65) and the flowable tissue dressing material may be delivered percutaneously.

[0074] In various aspects, the method includes solidifying the flowable tissue dressing material to form a foam, for example, an open cell foam or a closed cell foam adjacent to the tissue site 50. In any embodiment, an open cell foam manifold can be formed having a plurality of flow channels in fluid communication with the tissue site 50. Thus, in any embodiment, the tissue dressing apparatus may further include an open cell foam manifold as described herein formed by solidifying the flowable tissue dressing material. Solidifying the flowable tissue dressing material can be achieved by any known means in the art, for example, via cooling, reacting, heating, curing, cross-linking, exposure to ultraviolet light, and combinations thereof. In any embodiment, the foam may have a higher molecular weight (M _n ), for example, greater than or equal to about 100,000, greater than or equal to about 500,000 or about 1,000,000; or from about 100,000 to about 1,000,000, about 250,000 to about 1,000,000 or about 500,000 to about 1,000,000. Additionally or alternatively, the foam may have a moisture vapor transmission rate (MVRT) of about 250 g/m ² /24 hours to about 1500 g/m ² /24 hours, or about 500 g/m ² /24 hours to about 1500 g/m ² /24 hours, or about 1000 g/m ² /24 hours to about 1500 g/m ² /24 hours. In some embodiments, the foam may be radio-opaque so that is capable of detection by X-ray.

[0075] In some embodiments, the flowable tissue dressing material is allowed to react completely, e.g., foaming has stopped and the majority of heat is released, before applying the flowable tissue dressing material to a tissue site. In other embodiments, the flowable tissue dressing material is applied to a tissue site while still reacting, e.g., foaming. In such instances, a cooler temperature of the tissue site can slow and/or stop the foaming.

[0076] As further illustrated in Figure 5B, the tissue dressing apparatus may further include a negative-pressure source 18 in fluid communication with the tissue dressing apparatus, and the method may include applying a negative-pressure to the tissue site through the plurality of flow channels (not shown) of the open cell foam 85. For example, negative- pressure may be delivered via a manifold delivery tube 70 or the tissue dressing material delivery tube 60 (not shown in Figure 5B). In some embodiments, the manifold delivery tube 70 may be integral with a connector pad 75. In some embodiments, the connector pad 75 may include a pressure valve ( e.g ., positive pressure valve) (not shown) for releasing gas formed during solidification of the flowable tissue dressing material. The negative-pressure source 18 for applying the negative-pressure can be in fluid communication with the tissue dressing material delivery tube 60, the manifold delivery tube 70, the connector pad 75, the cover 9, or a combination thereof, for example via fluid conductor 80 for applying the negative-pressure. In some embodiments, the connector pad 75 may include a water soluble component, such as a baffle, which can degrade or break down after the foam has been formed. For example, instillation fluid can cause at least a portion of the connector pad 75 to degrade or breakdown in order to prevent form from entering fluid conductor 80. Examples of suitable material for the water soluble component of the connector pad 75 include, but are not limited to a sugar, polyvinylpyrrolidone (PVP), a polyvinyl alcohol, polyethylene oxide (PEO), and cellulose.

[0077] In some embodiments, the foam formed may be self-skinning when in contact with the cover 9, and the user may have to cut a hole into the skin before application of a connector pad 75 to deliver negative-pressure. Optionally, a foam filling pad may also be included, which may be bonded to the cover 9. The foam filling pad may be left in place after delivery of the flowable tissue dressing material or may be removed. If left in place, a user would need to cut a hole in the foam filling pad before application of a connector pad 75 to deliver negative-pressure.

[0078] As illustrated in Figure 5B, the delivery device 100 is not in fluid communication with the negative-pressure source 18, i.e., the delivery device 100 is physically separate from the negative-pressure source 18. Alternatively, as illustrated in Figure 6, the delivery device 100 can be in fluid communication with the negative-pressure source 18, for example, via a flowable material fluid conductor 90 and flowable material fluid conductor 95. It is contemplated herein, that the flowable tissue dressing material may be delivered to tissue site 50 via flowable material fluid conductor 90 and flowable material fluid conductor 95, for example, the delivery device 100 is in fluid communication with the therapy system 10 and delivery of the flowable tissue dressing material may be automatic. For example, the therapy system may further comprise a delivery actuator or a pump ( e.g ., peristaltic pump) in fluid communication with the negative-pressure source 18 and the tissue dressing apparatus for delivering the flowable tissue dressing material. The delivery actuator or pump can actuate a pressurized container to deliver the flowable tissue dressing material to the tissue site 50, for example, via flowable material conductor 90. The therapy system may measure the pressure at the tissue site while the flowable tissue dressing material is being delivered, for example, via a controller 13, in order to calculate when the wound is full. For example, as the air in a wound is displaced it can enter the fluid conductor 80, in effect pressuring the container 11, and this wound fill pressure can be logged in the system. Once this wound fill pressure has reached a plateau, the wound can be deemed to be full and delivery of the flowable tissue dressing material can be ceased. The rate of change of wound fill pressure can be relatively constant while filling the wound but can sharply increase once the wound is full. In addition to controlling the delivery of the flowable tissue dressing material, the controller 13 may also control the means (e.g., the transmission of UV light) for solidifying the flowable tissue dressing material. The flowable material fluid conductor 90 may be sealed once the flowable tissue dressing material solidifies to form a foam as described herein, but the fluid conductor 80 may remain substantially open to the flow of fluids. Any foam that may entered the fluid conductor 80 will be porous so that fluids may flow through the fluid conductor 80.

[0079] In any embodiment, the flowable tissue dressing material can be formed in the delivery device 100 by mixing a first reactant with a second reactant to form the flowable tissue dressing material. A device for delivering a flowable tissue dressing material may include a first zone comprising a first reactant and a second zone comprising a second reactant. The first zone may be physically separate from the second zone. Figure 7A illustrates further details that may be associated with some embodiments of a delivery device 100. In some embodiments, the delivery device 100 may be a single container 105 including a first zone 110 and a second zone 120 therein. The delivery device 100 can further include a wall 150 defined therein, which separates the first zone 110 and the second zone 120. The wall 150 can be at least partially removable to allow for mixing between the first reactant and the second reactant to form a flowable tissue dressing material upon removal of at least a portion of the wall 150. For example, the wall 150 may be formed of a material, which can be pierced, punctured or removed by a user. Exemplary materials that wall 150 may be formed of include, but are not limited to, a metal (e.g., aluminum, steel, and stainless steel), optionally coated with a polymeric coating (e.g., polyurethanes, epoxies, thermosets, such as phenol formaldehyde, urea formaldehyde, melamine formaldehyde, or polyolefins, blends and copolymers thereof), and a polymeric material (e.g., polyamides, acetals, polyesters, and other engineering polymers, such as aramids and aromatic polyesters). Mixing can be achieved by a user, for example, by partially removing a wall as described herein, e.g., wall 150, to allow the first reactant and the second reactant to mix with one another, and or by agitating the device. Additionally or alternatively, an optional mixer 190 for mixing the first reactant with the second reactant may be included in the device, for example, as illustrated in Figure 7A in device 100. Examples of a suitable mixer 190 include but are not limited to a ball (e.g., metal, glass, or plastic ball), a mechanical reciprocating plunger, a magnetically coupled impeller or beads, for example, where an external magnetic source rotates the impellor or agitates the beads. Although not shown, it is contemplated herein that the mixer 190 can be present in any of the delivery device embodiments described herein.

[0080] The first reactant and the second reactant may be any suitable multipart polymer reaction system, which, when mixed together and/or reacted, form a flowable tissue dressing material, such as a polymer foam, for example, a polyurethane foam. Examples of a suitable first reactant include, but are not limited to a polyol, a polyaldehyde, a polyamine, and combinations thereof. Examples of a suitable second reactant include, but are not limited to a multi-isocyanate (e.g., diisocyanate, triisocyanate), a multi-isocyanate prepolymer, a polycarbamate, a polycarboxylic acid, an anhydride, and combinations thereof. As used herein, the term“multi-isocyanate prepolymer” refers to a multi-isocyanate, such as a diisocyanate, having at least a portion of the active isocyanate groups already reacted leaving fewer isocyanate groups to react with a polyol. For example, the first reactant may be a polyol and the second reactant may be a multi-isocyanate (e.g., diisocyanate). Once the polyol and the multi-isocyanate are mixed together in the presence of water, for example, either present in the device and/or present as ambient water, they can react to form a polyurethane foam, which can be delivered to a tissue site as a flowable tissue dressing material. Similarly, a polyaldehyde (i.e., first reactant) and a polycarbamate (i.e., second reactant) when mixed together can react to form a polyurethane foam.

[0081] Optionally, in some embodiments, as illustrated in Figure 7B, a third zone 130 may be included in a delivery device 101 for mixing the first reactant from the first zone 110 with the second reactant from the second zone 120 to form a flowable tissue dressing material and/or for delivering the flowable tissue dressing material. In the example in Figure 7B, partially removable walls 150 may be defined therein, which physically separate the first zone 110 and the second zone 120 from the third zone 130. Upon removal of at least a portion of the walls 150, the first reactant and the second reactant may enter the third zone 130 and be admixed to form a flowable tissue dressing material. Figure 7C illustrates another example configuration of a delivery device 102 having a first zone 110, a second zone 120, a third zone 130 and a wall 150 defined therein, which is at least partially removable. Delivery device 102 further includes an irremovable wall 155 defined therein, which physically separates the first zone 110 and the second zone 120.

[0082] Optionally, as illustrated in Figure 7D, a canister 160 may be in fluid communication with a single container 105 of a delivery device 103. The canister 160 can contain a propellant, as further described below, for further enabling delivery of a flowable tissue dressing material from the delivery device 103. For example, the propellant may expand to force the flowable tissue dressing material out of the device 103, for example, through holes in a spray nozzle as an aerosol. Although not shown, it is contemplated herein that canister 160 can be present in any of the delivery device embodiments described herein. Additionally, the canister 160 may be removable or irremovable. Optionally, as illustrated in Figure 7E, an ultraviolet (UV) light source 165 may be included with the delivery device 104, for example, for further solidifying a flowable tissue dressing material at a tissue site. While Figure 7E illustrates a UV light source 165 as integral to the single container 105, it is contemplated herein that the UV light source 165 may be removable from the single container 105 and/or may be separate from the single container 105. Although not shown, it is contemplated herein that UV light source 165 can be present in any of the device embodiments described herein.

[0083] In another example embodiment as illustrated in Figure 8, a delivery device 200 may include a first zone 110 comprising a first reactant in a first container 210 and a second zone 120 comprising a second reactant in a second container 220. The delivery device 200 may further include a third zone 130 in a third container 230 for combining and/or mixing the first reactant with the second reactant to form a flowable tissue dressing material. For example, the first container 210, the second container 220, and the third container 230 may each include a removable cap 180, so that the first reactant and the second reactant can be removed from the first container 210 and the second container 220 and added to the third container 230. The first reactant and the second reactant may be mixed in any of the first container 210, the second container 220, and the third container 230. It is contemplated herein, if the first reactant and the second reactant are mixed in the first container 210 or the second container 220, the third container 230 may be absent.

[0084] In another example, a delivery device for delivering a flowable dressing material may include the flowable dressing material comprising a reacted polymer present in a carrier. Referring more specifically to Figure 9, a device 300 contains the flowable dressing material in a single container 305. Examples of a suitable reacted polymer include, but are not limited to a polyurethane, a polyester, a polyamide, an acrylic polymer, an acrylate polymer, a polyvinyl acetate, a polysiloxane, and combinations and copolymers thereof.

[0085] Alternatively, the flowable dressing material present in single container 305 may be a flowable hydrophilic tissue dressing material including a reacted polymer ( i.e ., a hydrophilic reacted polymer) present in a carrier. Examples of a suitable hydrophilic reacted polymer include, but are not limited to polyvinylpyrrolidone (PVP), a polyvinyl alcohol, polyethylene oxide (PEO), hydrophilicly-modified polyurethane, and combinations and copolymers thereof. The hydrophilicly-modified polyurethane can include any suitable hydrophilic moieties, such as, but not limited to a hydroxyl moiety, a carboxyl moiety, an ester moiety, a quaternary ammonium ion moiety, a metal ion moiety ( e.g ., sodium ion, potassium ion, sodium salt, potassium salt), a nitrogen-containing moiety (e.g., an amine, an amide, an imine) and combination thereof. In some embodiments, peroxide and/or hydrogen peroxide may be included with the reacted polymer in the carrier. Additionally or alternatively, the hydrophilic reacted polymer may include polymer segments with a low glass transition temperature, for example, less than or equal to about 25°C.

[0086] In any embodiment, the reacted polymer (including the hydrophilic reacted polymer) may be dissolved or dispersed in a suitable carrier, such as, but not limited to a low boiling point liquid, water, a compressed gas, and combinations thereof. The reacted polymer (including the hydrophilic reacted polymer) and carrier may be in the form of a dispersion, solution or emulsion. Examples of a low boiling point liquid include, but are not limited to a fluorocarbon, a chlorofluorocarbon, a hydrofluorocarbon (e.g., tetrafluoropropene, Solkane®) a hydrochlorofluorocarbon, and combinations thereof. Examples of a compressed gas include but are not limited to compressed carbon dioxide, compressed nitrogen, a compressed alkane (e.g., methane, ethane, propane, and the like), and combinations thereof. [0087] As illustrated in Figures 7A-7D and 9 a delivery tube 170 optionally may be present for delivering a flowable tissue dressing material from the delivery devices 100, 101, 102, 103, 300. Although not shown in Figure 8, a delivery tube 170 may be present in one or more of a first container 210, a second container 220, and a third container 230. A delivery means 185 may be in fluid communication with the delivery tube 170 for delivering the flowable dressing material to a tissue site. Examples of suitable delivery means 185 include, but are not limited to a nozzle, such as a spray nozzle, or a manifold delivery tube. In some embodiments, the flowable dressing material may be transferred and/or mixed in a separate vessel ( e.g ., measuring cup) from which it can be poured onto a tissue site. It is also contemplated herein that a delivery tube 170 may be absent and any of the devices described herein may include a removable cap, so that a flowable tissue dressing material can be poured from the devices onto a tissue site.

[0088] In any embodiment, the delivery devices described herein may be made of any suitable material, such as, but not limited to metal, plastic, or a combination thereof. Suitable metals include, but are not limited to aluminum and coated steels. Suitable plastics include, but are not limited to polycarbonates, polyesters, and polyolefins. In any embodiment, an interior of the devices described herein is sterile and the contents of the device may be sterile. Sterilization can be achieved by any known methods in the art, for example, via gamma sterilization or electron beam (e-beam) sterilization. In the case of e-beam sterilization, the delivery devices described herein may include a window, for example, a plastic window, to permit transmission of the e-beam.

[0089] The delivery devices described herein can include one or more additional agents for incorporation into a flowable tissue dressing material and/or for use in the formation of a flowable tissue dressing material. Each additional agent may be present in the first zone 110, the second zone 120, the third zone 130, or a combination thereof. In any embodiment, a cell opener can be included in the devices described herein to promote opening or rupturing of cell walls and to enhance an open cell structure as the polymer foam is produced. Examples of a suitable cell opener include, but are not limited to a silicone, a polyether siloxane, a mineral (e.g., clays, silicas, calcium carbonate and the like), and combinations thereof.

[0090] Additionally or alternatively, the delivery devices described herein can further include a foaming agent, a propellant, or a combination thereof to assist with foam formation and delivery. As used herein, a foaming agent includes any suitable surfactants and blowing agents as known in the art for producing a flowable tissue dressing material, e.g., a polymer foam. Examples of suitable foaming agents include, but are not limited to a low boiling point liquid, water, a compressed gas, hydrocarbons (e.g. pentane, isopentane, cyclopentane), liquid carbon dioxide, and combinations thereof. Examples of a low boiling point liquid include, but are not limited to a fluorocarbon, a chlorofluorocarbon, a hydrofluorocarbon (e.g., tetrafluoropropene, Solkane®) a hydrochlorofluorocarbon, and combinations thereof. Examples of a compressed gas include but are not limited to compressed carbon dioxide, compressed nitrogen, a compressed alkane (e.g., methane, ethane, propane, and the like), and combinations thereof. Examples of a suitable propellant include, but are not limited to low boiling point liquids as described herein. The propellant may be present within the delivery devices described herein, for example, in the first zone 110, in the second zone 120, in the third zone 130, or a combination thereof, or in the single container 305. Alternatively, with reference to Figure 7D, the propellant may be present in a separate canister 160 in fluid communication with the devices described herein. In addition to aiding in delivery of a flowable tissue dressing material, the propellant may also aid in mixing of the first reactant with the second reactant or mixing the reacted polymer.

[0091] Additionally or alternatively, the delivery devices described herein can further include a catalyst, for example, when the first reactant and the second reactant are present, to assist in formation of a flowable tissue dressing material, e.g., a polymer foam. Any suitable catalysts known in the art for producing polymer foams can be used. For example, suitable gelling catalysts and/or blowing catalysts may be used for forming a polyurethane foam. Examples of catalysts include, but are not limited to, tertiary amine catalysts (e.g., 1,4- diazabicyclo[2.2.2]octane), metal complex catalysts, such as metal carboxylates (e.g., tin carboxylates, bismuth carboxylates, zinc carboxylates, zirconium carboxylates, nickel carboxylates), dibutyltin dilaurate, bismuth octanoate, and platinum catalysts.

[0092] Additionally or alternatively, the delivery devices described herein and/or the flowable tissue dressing material can further include a softener, such as water soluble particles, to encourage a certain degree of porosity at the tissue site interface, which upon contact with water present in the wound can soften and/or dissolve to leave pores or fissures in foam. Examples of suitable water soluble particles include, but are not limited to a salt, a water soluble polymer, and combinations thereof. Examples of a salt include, but are not limited to sodium chloride, magnesium chloride, calcium chloride, sodium carbonate, potassium carbonate, and combinations thereof. Examples of water soluble polymers include, but are not limited to polyvinylpyrrolidone (PVP), a polyvinyl alcohol, polyethylene oxide (PEO), carboxy modified polyurethane, hydroxy modified polyurethane, and combinations thereof.

[0093] Additionally or alternatively, the delivery devices described herein and/or the flowable tissue dressing material can further include an antimicrobial agent. Examples of suitable antimicrobial agents include, but are not limited to organic acids such as carboxylic acids, silver, gold, zinc, copper, polyhexamethylene biguanide (PHMB), iodine and combinations thereof. Exemplary carboxylic acids include, but are not limited to ascorbic acid (e.g., (R)-3,4-dihydroxy-5-((S)- l,2-dihydroxyethyl)furan-2(5H)-one or Vitamin C), formic acid, gluconic acid, lactic acid, oxalic acid, tartaric acid, peroxy-pyruvic acid, and combinations thereof. Examples of carboxylic acids include, but are not limited to citric acid and acetic acid (i.e., ethanoic acid). The metal (e.g., silver) may be present in metallic form, in ionic form (e.g., a silver salt), or both.

[0094] Additionally or alternatively, the delivery devices described herein and/or the flowable tissue dressing material can further include a polysaccharide, such as chitosan and/or an anionic polysaccharide. The anionic polysaccharide may be substantially insoluble in water at pH 7. Additionally or alternatively, the anionic polysaccharide may have a molecular weight greater than about 20,000, more preferably greater than about 50,000. The anionic polysaccharide may be in the form of a film, or fibers having a length greater than 1 mm. Suitable anionic polysaccharides include, but are not limited to, polycarboxylates, alginates, hyaluronates, pectins, carrageenans, xanthan gums, sulfated dextrans, cellulose derivatives, such as carboxymethyl celluloses, and oxidized celluloses. The term“oxidized cellulose” refers to any material produced by the oxidation of cellulose, for example with dinitrogen tetroxide. Such oxidation converts primary alcohol groups on the saccharide residues to carboxylic acid groups, forming uronic acid residues within the cellulose chain. The oxidation generally does not proceed with complete selectivity, and as a result, hydroxyl groups on carbons 2 and 3 are occasionally converted to the keto form. These keto units introduce an alkali-labile link, which at pH 7 or higher initiates the decomposition of the polymer via formation of a lactone and sugar ring cleavage. In some embodiments, oxidized cellulose may be oxidized regenerated cellulose (ORC), which may be prepared by oxidation of a regenerated cellulose, such as rayon. It has been known that ORC has haemostatic properties. ORC has been available as a haemostatic fabric called SURGICEL ^® (Johnson & Johnson Medical, Inc.) since 1950. This product may be produced by the oxidation of a knitted rayon material.

[0095] Additionally or alternatively, the delivery devices described herein and/or the flowable tissue dressing material can further include one or more super absorbent polymers, for example in particle form. Examples of suitable super absorbent polymers include, but are not limited to polyacrylic acid, a salt of polyacrylic acid (e.g^ sodium polyacrylate (Luquasorb® 1160, Luquasorb® 1161; BASF)), polyacrylamide, cellulosic polymer, 2- acrylamido-2-methylpropanesulfonic acid (AMPS), polyethylene oxide (PEO), and a combination thereof.

[0096] Additionally or alternatively, the delivery devices described herein and/or the flowable tissue dressing material can further include an alcohol, a colorant ( e.g ., a pigment, a dye), a release agent (e.g., wax, fluorocarbon), and a combination thereof. For example, an alcohol can be included as a further solvent and/or suspending agent along with the reacted polymer. Examples of a suitable alcohol include, but are not limited to ethanol, isopropyl alcohol, and a combination thereof.

[0097] Additionally or alternatively, the delivery devices described herein and/or the flowable tissue dressing material can further include a photoinitiator that is capable of undergoing photopolymerization or radiation curing, i.e., producing a free radical when exposed to radiation, e.g., UV light, which can react, for example, with the first reactant and/or the second reactant, to initiate polymer chain growth. Examples of a suitable photoinitiator include, but are not limited to, 2,2-dimethoxy-l,2,-diphenylethan-l-one, 1- hydroxy-cyclohexyl-phenyl-ketone (IRGACURE® 184); l-[4-(2-hydroxyethoxy)-phenyl]-2- hydroxy-2-methyl- 1 -propane- 1 -one (IRGACURE® 2959); and 2-benzyl-2-(dimethylamino)- l-[4- (4-morpholinyl) phenyl] -1-butanone (IRGACURE® 369).

[0098] The systems, delivery devices, and methods described herein may provide significant advantages. For example, the delivery devices described herein can provide a tissue dressing material that can be readily applied to wounds of varying sizes without needing timely customization. Advantageously, when delivering flowable hydrophilic tissue dressing material, the hydrophilic nature of the tissue dressing material can allow for enhanced breathability, absorbency and/or wicking of the tissue dressing material applied to the tissue site. The nature of the flowable tissue dressing material can also allow for better adhesion between the tissue dressing material and skin of a tissue site. Additionally, the devices for delivery of a flowable tissue dressing material can eliminate the need for additional traditional dressing material components, such as support and release layers. Furthermore, the delivery devices are portable and can be used in many environments and settings to produce tissue dressings in various configurations.

[0099] 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 5, the container 11, or both may be eliminated or separated from other components for manufacture or sale. In other example configurations, the controller 13 may also be manufactured, configured, assembled, or sold independently of other components.

[00100] 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.