Patent Description:
<CIT> concerns a sensor enabled wound monitoring and therapy apparatus.

While the clinical benefits of negative-pressure therapy and instillation therapy are widely known, improvements to therapy systems, components, and processes may benefit healthcare providers and patients.

New and useful systems, apparatuses, and methods for applying negative pressure to a tissue site using a dressing are disclosed in the following. Illustrative embodiments are also provided to enable a person skilled in the art to make and use the claimed subject matter. Some embodiments are illustrative of an apparatus or system for delivering negative-pressure and therapeutic solution of fluids to a tissue site, which can be used in conjunction with sensing properties of wound exudates extracted from a tissue site. For example, an apparatus may include a pH sensor, a humidity sensor, a temperature sensor and a pressure sensor embodied on a single pad proximate the tissue site to provide data indicative of acidity, humidity, temperature and pressure. Such apparatus may further comprise a pH sensor having a sensing portion adapted to be positioned between the dressing and the tissue site and coupled to a microprocessor, wherein both are configured to detect a pH level of fluid present at the tissue site and to provide a pH output to the microprocessor based on the pH level detected.

According to the invention as claimed, the dressing comprises a tissue interface having a first layer comprising a foam and a second layer comprising a plurality of apertures, wherein the second layer is adapted to be positioned between the first layer and the tissue site. The dressing further comprises a dressing interface having a housing including a therapy cavity and a component cavity fluidly isolated from the therapy cavity. The therapy cavity has an opening adapted to be in fluid communication with the first layer and a port adapted to be fluidly coupled to a negative-pressure source. The dressing further comprises a control device disposed within the component cavity that includes a microprocessor. The dressing further comprises a first pH sensor having a sensing portion adapted to be positioned between the second layer and the tissue site and electrically coupled to the microprocessor. The first pH sensor is configured to detect a pH level of fluid present at the tissue site and to provide a pH output to the microprocessor based on the pH level detected.

In some embodiments, the dressing interface may further comprise a vent port fluidly coupled to the therapy cavity and adapted to enable airflow into the therapy cavity. The dressing interface may further comprise an instillation port fluidly coupled to the therapy cavity and adapted to fluidly couple an instillation source to the tissue interface. The dressing interface may further comprise a temperature sensor and a humidity sensor, each sensor having a sensing portion disposed within the therapy cavity and electrically coupled to the microprocessor through the body of the housing. The sensing portion of the humidity sensor and the temperature sensor may be disposed proximate the instillation port.

Some embodiments are illustrative of a method (not forming part of the invention as claimed) of applying negative-pressure to a dressing for treating a tissue site. For example, the method may comprise positioning a tissue interface on the tissue site, wherein the tissue interface has a first layer comprising foam and a second layer comprising a plurality of apertures. In some embodiments, the second layer may be adapted to be positioned between the first layer and the tissue site. In some embodiments, the method may further comprise positioning a sensing portion of a pH sensor between the second layer and the tissue site. In some embodiments, the method may further comprise positioning an opening of a dressing interface on the first layer, wherein the dressing interface includes a housing having a therapy cavity including the opening and a component cavity fluidly isolated from the therapy cavity. In some embodiments, the method may further comprise electrically coupling the pH sensor to a microprocessor disposed within the component chamber. In some embodiments, the method may further comprise detecting a pH level of fluid present at the tissue site based on a pH output provided by the first pH sensor to the microprocessor based on the pH level detected.

Some embodiments are illustrative of applying negative-pressure to a tissue interface and sensing properties of fluid at a tissue site. In one example embodiment, the method (not forming part of the invention as claimed) may comprise positioning a dressing interface wherein the dressing interface comprises a housing having a body including a therapy cavity and a component chamber fluidly isolated from the therapy cavity, wherein the therapy cavity has an opening configured to be in fluid communication with the tissue interface. The dressing interface may further comprise a negative-pressure port fluidly coupled to the therapy cavity, an ambient port fluidly coupled to the component chamber, a control device disposed within the component chamber, and at least one sensor having a sensing portion disposed within the therapy cavity and coupled to the control device. The dressing interface may further comprise an ambient input fluidly coupled to the component chamber for providing the sensor access to the ambient environment. The method may further comprise applying negative pressure to the therapy cavity to draw fluids from the tissue interface and into the therapy cavity. The method may further comprise sensing properties of the ambient environment provided by the at least one sensor through the ambient input and the component chamber, and sensing properties of the fluids within the therapy cavity provided by the at least one sensor as compared to the properties of the ambient environment.

Some other embodiments are illustrative of a method (not forming part of the invention as claimed) for applying fluids to a tissue interface and sensing properties of fluids at a tissue site for treating the tissue site. For example, the method may comprise positioning a dressing interface on the tissue site, wherein the dressing interface may have a housing including an outside surface and a therapy cavity having an opening configured to be in fluid communication with the tissue interface. The dressing interface may further comprise a reduced-pressure port fluidly coupled to the therapy cavity and adapted to fluidly couple a reduced-pressure source to the therapy cavity, an instillation port fluidly coupled to the therapy cavity and adapted to fluidly couple an instillation source to the therapy cavity, and a pH sensor and a pressure sensor disposed within the therapy cavity and each electrically coupled to a control device. The method may further comprise applying reduced pressure to the therapy cavity to draw fluids from the tissue interface and into the therapy cavity, and sensing pH and pressure properties of the fluids within the therapy cavity provided from the pressure sensor and the pH sensor. The method may further comprise instilling fluids into the therapy cavity to cleanse the pressure sensor and the pH sensor.

The term "tissue site" in this context broadly refers to a wound, defect, or other treatment target located on or within tissue, including but not limited to, bone tissue, adipose tissue, muscle tissue, neural tissue, dermal tissue, vascular tissue, connective tissue, cartilage, tendons, or ligaments. A wound may include chronic, acute, traumatic, subacute, and dehisced wounds, partial-thickness burns, ulcers (such as diabetic, pressure, or venous insufficiency ulcers), flaps, and grafts, for example. The term "tissue site" may also refer to areas of any tissue that are not necessarily wounded or defective, but are instead areas in which it may be desirable to add or promote the growth of additional tissue. For example, negative pressure may be applied to a tissue site to grow additional tissue that may be harvested and transplanted.

The present technology also provides negative pressure therapy devices and systems, and methods of treatment using such systems with antimicrobial solutions. <FIG> is a simplified functional block diagram of an example embodiment of a therapy system <NUM> that can provide negative-pressure therapy with instillation of treatment solutions in accordance with this specification. The therapy system <NUM> may include a negative-pressure supply, and may include or be configured to be coupled to a distribution component, such as a dressing. In general, a distribution component may refer to any complementary or ancillary component configured to be fluidly coupled to a negative-pressure supply between a negative-pressure supply and a tissue site. A distribution component is preferably detachable, and may be disposable, reusable, or recyclable. For example, a dressing <NUM> is illustrative of a distribution component that may be coupled to a negative-pressure source and other components. The therapy system <NUM> may be packaged as a single, integrated unit such as a therapy system including all of the components shown in <FIG> that are fluidly coupled to the dressing <NUM>. The therapy system may be, for example, a V. Ulta™ System available from Kinetic Concepts, Inc.

The dressing <NUM> may be fluidly coupled to a negative-pressure source <NUM>. A dressing may include a cover, a tissue interface, or both in some embodiments. The dressing <NUM>, for example, may include a cover <NUM>, a dressing interface <NUM>, and a wound dressing or tissue interface <NUM>. A computer or a controller device, such as a controller <NUM>, may also be coupled to the negative-pressure source <NUM>. In some embodiments, the cover <NUM> may be configured to cover the tissue interface <NUM> and the tissue site, and may be adapted to seal the tissue interface and create a therapeutic environment proximate to a tissue site for maintaining a negative pressure at the tissue site. In some embodiments, the dressing interface <NUM> may be configured to fluidly couple the negative-pressure source <NUM> to the therapeutic environment of the dressing. The therapy system <NUM> may optionally include a fluid container, such as a container <NUM>, fluidly coupled to the dressing <NUM> and to the negative-pressure source <NUM>.

The therapy system <NUM> may also include a source of instillation solution, such as a solution source <NUM>. A distribution component may be fluidly coupled to a fluid path between a solution source and a tissue site in some embodiments. For example, an instillation pump <NUM> may be coupled to the solution source <NUM>, as illustrated in the example embodiment of <FIG>. The instillation pump <NUM> may also be fluidly coupled to the negative-pressure source <NUM> such as, for example, by a fluid conductor <NUM>. In some embodiments, the instillation pump <NUM> may be directly coupled to the negative-pressure source <NUM>, as illustrated in <FIG>, but may be indirectly coupled to the negative-pressure source <NUM> through other distribution components in some embodiments. For example, in some embodiments, the instillation pump <NUM> may be fluidly coupled to the negative-pressure source <NUM> through the dressing <NUM>. In some embodiments, the instillation pump <NUM> and the negative-pressure source <NUM> may be fluidly coupled to two different locations on the tissue interface <NUM> by two different dressing interfaces. For example, the negative-pressure source <NUM> may be fluidly coupled to the dressing interface <NUM> while the instillation pump <NUM> may be fluidly to the coupled to dressing interface <NUM> or a second dressing interface <NUM>. In some other embodiments, the instillation pump <NUM> and the negative-pressure source <NUM> may be fluidly coupled to two different tissue interfaces by two different dressing interfaces, one dressing interface for each tissue interface (not shown).

The therapy system <NUM> also may include sensors to measure operating parameters and provide feedback signals to the controller <NUM> indicative of the operating parameters properties of fluids extracted from a tissue site. As illustrated in <FIG>, for example, the therapy system <NUM> may include a pressure sensor <NUM>, an electric sensor <NUM>, or both, coupled to the controller <NUM>. The pressure sensor <NUM> may be fluidly coupled or configured to be fluidly coupled to a distribution component such as, for example, the negative-pressure source <NUM> either directly or indirectly through the container <NUM>. The pressure sensor <NUM> may be configured to measure pressure being generated by the negative-pressure source <NUM>, i.e., the pump pressure (PP). The electric sensor <NUM> also may be coupled to the negative-pressure source <NUM> to measure the pump pressure (PP). In some example embodiments, the electric sensor <NUM> may be fluidly coupled proximate the output of the output of the negative-pressure source <NUM> to directly measure the pump pressure (PP). In other example embodiments, the electric sensor <NUM> may be electrically coupled to the negative-pressure source <NUM> to measure the changes in the current in order to determine the pump pressure (PP).

Distribution components may be fluidly coupled to each other to provide a distribution system for transferring fluids (i.e., liquid and/or gas). For example, a distribution system may include various combinations of fluid conductors and fittings to facilitate fluid coupling. A fluid conductor generally includes any structure with one or more lumina adapted to convey a fluid between two ends, such as a tube, pipe, hose, or conduit. Typically, a fluid conductor is an elongated, cylindrical structure with some flexibility, but the geometry and rigidity may vary. Some fluid conductors may be molded into or otherwise integrally combined with other components. A fitting can be used to mechanically and fluidly couple components to each other. For example, a fitting may comprise a projection and an aperture. The projection may be configured to be inserted into a fluid conductor so that the aperture aligns with a lumen of the fluid conductor. A valve is a type of fitting that can be used to control fluid flow. For example, a check valve can be used to substantially prevent return flow. A port is another example of a fitting. A port may also have a projection, which may be threaded, flared, tapered, barbed, or otherwise configured to provide a fluid seal when coupled to a component.

In some embodiments, distribution 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. Coupling may also include mechanical, thermal, electrical, or chemical coupling (such as a chemical bond) in some contexts. For example, a tube may mechanically and fluidly couple the dressing <NUM> to the container <NUM> in some embodiments. For example, the negative-pressure source <NUM> may be directly coupled to the controller <NUM>, and may be indirectly coupled to the dressing interface <NUM> through the container <NUM> by conduit <NUM> and conduit <NUM>, also referred to herein as negative pressure conduit <NUM> and negative pressure conduit <NUM>. The pressure sensor <NUM> may be fluidly coupled to the dressing <NUM> directly (not shown) or indirectly through the container <NUM> and a filter <NUM> by conduit <NUM> and conduit <NUM>. The filter <NUM> may be any type of filter for preventing the ingress of liquids from the container <NUM>. Additionally, the instillation pump <NUM> may be coupled indirectly to the dressing interface <NUM> through the solution source <NUM> and an instillation regulator <NUM> by fluid conductors <NUM> and <NUM>, also referred to herein as instillation conduit <NUM>. The instillation regulator <NUM> may be electrically coupled to the controller <NUM> (not shown) that may be programmed along with the instillation pump <NUM> to deliver instillation fluid in a controlled fashion. Alternatively, the instillation pump <NUM> may be coupled indirectly to the second dressing interface <NUM> through the solution source <NUM> and the instillation regulator <NUM> by instillation conduits <NUM> and <NUM>.

Some embodiments of the therapy system <NUM> may include a solution source, such as solution source <NUM>, without an instillation pump, such as the instillation pump <NUM>. Instead, the solution source <NUM> may be fluidly coupled directly or indirectly to the dressing interface <NUM> and may further include the instillation regulator <NUM> electrically coupled to the controller <NUM> as described above. In operation, the negative pressure source <NUM> may apply negative pressure to the dressing interface <NUM> through the container <NUM> and the negative pressure conduit <NUM> to create a vacuum within the spaces formed by the dressing interface <NUM> and the tissue interface <NUM>. The vacuum within the spaces would draw instillation fluid into the spaces for cleansing or providing therapy treatment to the tissue site. In some embodiments, the controller <NUM> may be programmed to modulate the instillation regulator <NUM> to control the flow of instillation fluid into the spaces. In another example embodiment, the therapy system <NUM> may include both the instillation pump <NUM> and the negative pressure source <NUM> to alternately deliver instillation fluid to the dressing interface <NUM> by providing a positive pressure to the solution source <NUM> and a negative pressure directly to the dressing interface <NUM>, respectively. Any of the embodiments described above may be utilized to periodically clean, rinse, or hydrate the tissue site using saline along with other pH-modulating instillation fluids such as weak acidic acids.

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

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

"Negative pressure" 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 provided by the dressing <NUM>. 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. Similarly, 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 applied to a tissue site may vary according to therapeutic requirements, the pressure is generally a low vacuum, also commonly referred to as a rough vacuum, between -<NUM> Hg (-<NUM> Pa) and -<NUM> Hg (-<NUM> kPa). Common therapeutic ranges are between -<NUM> Hg (-<NUM> kPa) and -<NUM> Hg (-<NUM> kPa).

A negative-pressure supply, such as the negative-pressure source <NUM>, may be a reservoir of air at a negative pressure, or may be a manual or electrically-powered device that can reduce the pressure in a sealed volume, such as a vacuum pump, a suction pump, a wall suction port available at many healthcare facilities, or a micro-pump, for example. A negative-pressure supply 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 <NUM> may be combined with the controller <NUM> and other components into a therapy unit. A negative-pressure supply may also have one or more supply ports configured to facilitate coupling and de-coupling the negative-pressure supply to one or more distribution components.

The tissue interface <NUM> can be generally adapted to contact a tissue site. The tissue interface <NUM> may be partially or fully in contact with the tissue site. If the tissue site is a wound, for example, the tissue interface <NUM> may partially or completely fill the wound, or may be placed over the wound. The tissue interface <NUM> 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. Moreover, any or all of the surfaces of the tissue interface <NUM> may have projections or an uneven, course, or jagged profile that can induce strains and stresses on a tissue site, which can promote granulation at the tissue site.

In some embodiments, the tissue interface <NUM> may comprise a manifold such as manifold <NUM> shown in <FIG>. A "manifold" in this context may include any substance or structure providing a plurality of pathways adapted to collect or distribute fluid across a tissue site under pressure. For example, a manifold may be adapted to receive negative pressure from a source and distribute negative pressure through multiple apertures across a tissue site, 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 across a tissue site.

In some illustrative embodiments, the pathways of a manifold may be interconnected to improve distribution or collection of fluids across a tissue site. In some illustrative embodiments, a manifold may be a porous foam material having interconnected cells or pores. For example, cellular foam, open-cell foam, reticulated foam, porous tissue collections, and other porous material such as gauze or felted mat generally include pores, edges, and/or walls adapted to form interconnected fluid channels. 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.

The average pore size of a foam manifold may vary according to needs of a prescribed therapy. For example, in some embodiments, the tissue interface <NUM> may be a foam manifold having pore sizes in a range of <NUM>-<NUM> microns. The tensile strength of the tissue interface <NUM> 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. In one non-limiting example, the tissue interface <NUM> may be an open-cell, reticulated polyurethane foam such as GranuFoam° dressing or VeraFlo° foam, both available from Kinetic Concepts, Inc.

The tissue interface <NUM> may be either hydrophobic or hydrophilic. In an example in which the tissue interface <NUM> may be hydrophilic, the tissue interface <NUM> 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 <NUM> may draw fluid away from a tissue site by capillary flow or other wicking mechanisms. An example of a hydrophilic foam is a polyvinyl alcohol, open-cell foam such as V. WhiteFoam® dressing available from Kinetic Concepts, Inc. 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.

The tissue interface <NUM> may further promote granulation at a tissue site when pressure within the sealed therapeutic environment is reduced. For example, any or all of the surfaces of the tissue interface <NUM> may have an uneven, coarse, or jagged profile that can induce microstrains and stresses at a tissue site if negative pressure is applied through the tissue interface <NUM>.

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

In some embodiments, the tissue interface <NUM> may comprise a first layer or upper layer such as the manifold <NUM> and a second layer or lower layer such as a sealing layer <NUM> as shown in <FIG>. In some embodiments, the first layer may be disposed adjacent to the second layer which may have a tissue-facing surface disposed adjacent the tissue site. For example, the first layer and the second layer may be stacked so that the first layer is in contact with the second layer. In some embodiments, the first layer may also be bonded to the second layer, which may be disposed adjacent the tissue site.

In some example embodiments, the sealing layer <NUM> may comprise or consist essentially of a soft, pliable material suitable for providing a fluid seal with a tissue site, and may have a substantially flat surface. For example, the sealing layer <NUM> 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. In some embodiments, the sealing layer <NUM> may have a thickness between about <NUM> microns (µm) and about <NUM> microns (µm). In some embodiments, the sealing layer <NUM> may have a hardness between about <NUM> Shore OO and about <NUM> Shore OO. Further, the sealing layer <NUM> may be comprised of hydrophobic or hydrophilic materials. In some embodiments, the sealing layer <NUM> may be a hydrophobic-coated material. For example, the sealing layer <NUM> may be formed by coating a spaced 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.

Referring to <FIG>, <FIG>, <FIG>, and <FIG>, the sealing layer <NUM> in one embodiment may comprise a peripheral area, such as a periphery <NUM>, surrounding or disposed around a central area, such as an interior portion <NUM>. The sealing layer <NUM> may further comprise apertures <NUM> extending through the periphery <NUM> and the interior portion <NUM>. The interior portion <NUM> may correspond to a surface area of the manifold <NUM> in some examples. The sealing layer <NUM> may also have corners <NUM> and edges <NUM>. The corners <NUM> and the edges <NUM> may be part of the periphery <NUM>. The sealing layer <NUM> may have an interior border <NUM> around the interior portion <NUM>, disposed between the interior portion <NUM> and the periphery <NUM>. In some embodiments, the interior border <NUM> may be substantially free of the apertures <NUM>, such as illustrated in the example of <FIG>, <FIG>, and <FIG>. In some embodiments, the interior portion <NUM> may be symmetrical and centrally disposed in the sealing layer <NUM>.

The apertures <NUM> 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 <NUM> may have a uniform distribution pattern, or may be randomly distributed on the sealing layer <NUM>. The apertures <NUM> in the sealing layer <NUM> 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. Each of the apertures <NUM> may have uniform or similar geometric properties. For example, in some embodiments, each of the apertures <NUM> may be circular apertures, having substantially the same diameter. In some embodiments, the diameter of the apertures <NUM> may be between about <NUM> millimeter and about <NUM> millimeters. In other embodiments, the diameter of the apertures <NUM> may be between about <NUM> millimeter and about <NUM> millimeters.

In other embodiments, geometric properties of the apertures <NUM> may vary. For example, the diameter of the apertures <NUM> may vary depending on the position of the apertures <NUM> in the sealing layer <NUM>. In some embodiments, the diameter of the apertures <NUM> in the periphery <NUM> of the sealing layer <NUM> may be larger than the diameter of the apertures <NUM> in the interior portion <NUM> of the sealing layer <NUM>. For example, in some embodiments, the apertures <NUM> disposed in the periphery <NUM> may have a diameter between about <NUM> millimeters to about <NUM> millimeters. In some embodiments, the apertures <NUM> disposed in the corners <NUM> may have a diameter between about <NUM> millimeters to about <NUM> millimeters. In some embodiments, the apertures <NUM> disposed in the interior portion <NUM> may have a diameter between about <NUM> millimeters to about <NUM> millimeters.

At least one of the apertures <NUM> in the periphery <NUM> of the sealing layer <NUM> may be positioned at the edges <NUM> of the periphery <NUM>, and may have an interior cut open or exposed at the edges <NUM> that is in fluid communication in a lateral direction with the edges <NUM>. The lateral direction may refer to a direction toward the edges <NUM> and in the same plane as the sealing layer <NUM>. In some embodiments, the apertures <NUM> in the periphery <NUM> may be positioned proximate to or at the edges <NUM> and in fluid communication in a lateral direction with the edges <NUM>. The apertures <NUM> positioned proximate to or at the edges <NUM> may be spaced substantially equidistant around the periphery <NUM>. Alternatively, the spacing of the apertures <NUM> proximate to or at the edges <NUM> may be irregular.

Additionally, in some embodiments, the sealing layer <NUM> may further include one or more registration apertures, such as alignment holes <NUM>, which may be useful for facilitating alignment of the manifold <NUM> and the sealing layer <NUM> during manufacturing and/or assembly of the tissue interface <NUM>. For example, the alignment holes <NUM> may be positioned in corner regions of the interior border <NUM> of the sealing layer <NUM>, such as alignment regions <NUM> that may otherwise be substantially free of apertures or holes. The exact number and positioning of the alignment holes <NUM> may vary; however, in some instances the alignment holes <NUM> may include two holes or apertures in each of the four corner regions of the interior border <NUM>, for a total of eight holes. In some embodiments, the alignment holes <NUM> may be positioned adjacent to a set of three apertures <NUM> of the periphery <NUM>, which may span along the curvatures of the four corners of the interior border <NUM>.

In some embodiments, the cover <NUM> may provide a bacterial barrier and protection from physical trauma. The cover <NUM> 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 <NUM> may be, 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 <NUM> may have a high moisture-vapor transmission rate (MVTR) in some applications. For example, the MVTR may be at least <NUM>/m^<NUM> per twenty-four hours in some embodiments. In some example embodiments, the cover <NUM> 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 <NUM>-<NUM> microns. For permeable materials, the permeability generally should be low enough that a desired negative pressure may be maintained. In some embodiments, the cover may be a drape <NUM> shown in <FIG> having an opening <NUM>.

An attachment device may be used to attach the cover <NUM> 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 that extends about a periphery, a portion, or an entire sealing member. In some embodiments, for example, some or all of the cover <NUM> may be coated with an acrylic adhesive having a coating weight between <NUM>-<NUM> grams per square meter (g. 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 dressing interface <NUM> may facilitate coupling the negative-pressure source <NUM> to the dressing <NUM>. The negative pressure provided by the negative-pressure source <NUM> may be delivered through the conduit <NUM> to a negative-pressure interface, which may include an elbow portion. In one illustrative embodiment, the negative-pressure interface may be a T. ® Pad or Sensa T. ® Pad available from KCI of San Antonio, Texas. The negative-pressure interface enables the negative pressure to be delivered through the cover <NUM> and to the tissue interface <NUM> and the tissue site. In this illustrative, non-limiting embodiment, the elbow portion may extend through the cover <NUM> to the tissue interface <NUM>, but numerous arrangements are possible.

Sensors, such as the pressure sensor <NUM> or the electric sensor <NUM>, 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 pressure sensor <NUM> and the electric sensor <NUM> may be configured to measure one or more operating parameters of the therapy system <NUM>. In some embodiments, the pressure sensor <NUM> 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 pressure sensor <NUM> may be a piezoresistive strain gauge. The electric sensor <NUM> may optionally measure operating parameters of the negative-pressure source <NUM>, such as the voltage or current, in some embodiments. Preferably, the signals from the pressure sensor <NUM> and the electric sensor <NUM> are suitable as an input signal to the controller <NUM>, but some signal conditioning may be appropriate in some embodiments. Typically, the signal is an electrical signal that is transmitted and/or received on by wire or wireless means, but may be represented in other forms, such as an optical signal.

The solution source <NUM> is representative of a container, canister, pouch, bag, or other storage component, which can provide a solution for instillation therapy. Examples of such other therapeutic solutions that may be suitable for some prescriptions include hypochlorite-based solutions, silver nitrate (<NUM>%), sulfur-based solutions, biguanides, cationic solutions, and isotonic solutions. In one illustrative embodiment, the solution source <NUM> may include a storage component for the solution and a separate cassette for holding the storage component and delivering the solution to the tissue site <NUM>, such as a V. VeraLink™ Cassette available from Kinetic Concepts, Inc.

The container <NUM> may also be representative of a container, canister, pouch, or other storage component, which can be used to collect and manage exudates and other fluids withdrawn from a tissue site. In many environments, a rigid container such as, for example, a container <NUM>, may be preferred or required for collecting, storing, and disposing of fluids. In some embodiments, the container <NUM> may comprise a canister having a collection chamber, a first inlet fluidly coupled to the collection chamber and a first outlet fluidly coupled to the collection chamber and adapted to receive negative pressure from a source of negative pressure. In some embodiments, a first fluid conductor may comprise a first member such as, for example, the conduit <NUM> fluidly coupled between the first inlet and the tissue interface <NUM> by the negative-pressure interface described above, and a second member such as, for example, the conduit <NUM> fluidly coupled between the first outlet and a source of negative pressure whereby the first conductor is adapted to provide negative pressure within the collection chamber to the tissue site.

The therapy system <NUM> may also comprise a flow regulator such as, for example, a vent regulator <NUM> fluidly coupled to a source of ambient air to provide a controlled or managed flow of ambient air to the sealed therapeutic environment provided by the dressing <NUM> and ultimately the tissue site. In some embodiments, the vent regulator <NUM> may control the flow of ambient fluid to purge fluids and exudates from the sealed therapeutic environment. In some embodiments, the vent regulator <NUM> may be fluidly coupled by a fluid conductor or vent conduit <NUM> through the dressing interface <NUM> to the tissue interface <NUM>. The vent regulator <NUM> may be configured to fluidly couple the tissue interface <NUM> to a source of ambient air as indicated by a dashed arrow. In some embodiments, the vent regulator <NUM> may be disposed within the therapy system <NUM> rather than being proximate to the dressing <NUM> so that the air flowing through the vent regulator <NUM> is less susceptible to accidental blockage during use. In such embodiments, the vent regulator <NUM> may be positioned proximate the container <NUM> and/or proximate a source of ambient air where the vent regulator <NUM> is less likely to be blocked during usage.

In operation, the tissue interface <NUM> may be placed within, over, on, or otherwise proximate a tissue site, such as tissue site <NUM>. The cover <NUM> may be placed over the tissue interface <NUM> and sealed to an attachment surface near the tissue site <NUM>. Thus, the dressing <NUM> can provide a sealed therapeutic environment proximate to a tissue site, substantially isolated from the external environment, and the negative-pressure source <NUM> can reduce the pressure in the sealed therapeutic environment. Negative pressure applied across the tissue site through the tissue interface <NUM> in the sealed therapeutic environment can induce macrostrain and microstrain in the tissue site, as well as remove exudates and other fluids from the tissue site, which can be collected in container <NUM>.

In one embodiment, the controller <NUM> may receive and process data, such as data related to the pressure distributed to the tissue interface <NUM> from the pressure sensor <NUM>. The controller <NUM> may also control the operation of one or more components of therapy system <NUM> to manage the pressure distributed to the tissue interface <NUM> for application to the wound at the tissue site <NUM>, which may also be referred to as the wound pressure (WP). In one embodiment, controller <NUM> may include an input for receiving a desired target pressure (TP) set by a clinician or other user and may be program for processing data relating to the setting and inputting of the target pressure (TP) to be applied to the tissue site <NUM>. In one example embodiment, the target pressure (TP) may be a fixed pressure value determined by a user/caregiver as the reduced pressure target desired for therapy at the tissue site <NUM> and then provided as input to the controller <NUM>. The user may be a nurse or a doctor or other approved clinician who prescribes the desired negative pressure to which the tissue site <NUM> should be applied. The desired negative pressure may vary from tissue site to tissue site based on the type of tissue forming the tissue site <NUM>, the type of injury or wound (if any), the medical condition of the patient, and the preference of the attending physician. After selecting the desired target pressure (TP), the negative-pressure source <NUM> is controlled to achieve the target pressure (TP) desired for application to the tissue site <NUM>.

Referring more specifically to <FIG>, a graph illustrating an illustrative embodiment of pressure control modes <NUM> that may be used for the negative-pressure and instillation therapy system of <FIG> is shown wherein the x-axis represents time in minutes (min) and/or seconds (sec) and the y-axis represents pressure generated by a pump in Torr (mmHg) that varies with time in a continuous pressure mode and an intermittent pressure mode that may be used for applying negative pressure in the therapy system. The target pressure (TP) may be set by the user in a continuous pressure mode as indicated by solid line <NUM> and dotted line <NUM> wherein the wound pressure (WP) is applied to the tissue site <NUM> until the user deactivates the negative-pressure source <NUM>. The target pressure (TP) may also be set by the user in an intermittent pressure mode as indicated by solid lines <NUM>, <NUM> and <NUM> wherein the wound pressure (WP) is cycled between the target pressure (TP) and atmospheric pressure. For example, the target pressure (TP) may be set by the user at a value of <NUM> mmHg for a specified period of time (e.g., <NUM>) followed by the therapy being turned off for a specified period of time (e.g., <NUM>) as indicated by the gap between the solid lines <NUM> and <NUM> by venting the tissue site <NUM> to the atmosphere, and then repeating the cycle by turning the therapy back on as indicated by solid line <NUM> which consequently forms a square wave pattern between the target pressure (TP) level and atmospheric pressure. In some embodiments, the ratio of the "on-time" to the "off-time" or the total "cycle time" may be referred to as a pump duty cycle (PD).

In some example embodiments, the decrease in the wound pressure (WP) at the tissue site <NUM> from ambient pressure to the target pressure (TP) is not instantaneous, but rather gradual depending on the type of therapy equipment and dressing being used for the particular therapy treatment. For example, the negative-pressure source <NUM> and the dressing <NUM> may have an initial rise time as indicated by the dashed line <NUM> that 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 the range between about <NUM>-<NUM> mmHg/second or, more specifically, equal to about <NUM> mmHg/second, and in the range between about <NUM>-<NUM> mmHg/second for another therapy system. When the therapy system <NUM> is operating in the intermittent mode, the repeating rise time as indicated by the solid line <NUM> may be a value substantially equal to the initial rise time as indicated by the dashed line <NUM>.

The target pressure may also be a variable target pressure (VTP) controlled or determined by controller <NUM> that varies in a dynamic pressure mode. For example, the variable target pressure (VTP) may vary between a maximum and minimum pressure value that may be set as an input determined by a user as the range of negative pressures desired for therapy at the tissue site <NUM>. The variable target pressure (VTP) may also be processed and controlled by controller <NUM> that varies the target pressure (TP) according to a predetermined waveform such as, for example, a sine waveform or a saw-tooth waveform or a triangular waveform, that may be set as an input by a user as the predetermined or time-varying reduced pressures desired for therapy at the tissue site <NUM>.

Referring more specifically to <FIG>, a graph illustrating an illustrative embodiment of another pressure control mode for the negative-pressure and instillation therapy system of <FIG> is shown wherein the x-axis represents time in minutes (min) and/or seconds (sec) and the y-axis represents pressure generated by a pump in Torr (mmHg) that varies with time in a dynamic pressure mode that may be used for applying negative pressure in the therapy system. For example, the variable target pressure (VTP) may be a reduced pressure that provides an effective treatment by applying reduced pressure to tissue site <NUM> in the form of a triangular waveform varying between a minimum and maximum pressure of <NUM>-<NUM> mmHg with a rise time <NUM> set at a rate of +<NUM> mmHg/min. and a descent time <NUM> set at -<NUM> mmHg/min, respectively. In another embodiment of the therapy system <NUM>, the variable target pressure (VTP) may be a reduced pressure that applies reduced pressure to tissue site <NUM> in the form of a triangular waveform varying between <NUM>-<NUM> mmHg with a rise time <NUM> set at a rate of +<NUM> mmHg/min and a descent time <NUM> set at -<NUM> mmHg/min. Again, the type of system and tissue site determines the type of reduced pressure therapy to be used.

<FIG> is a flow chart illustrating an illustrative embodiment of a therapy method <NUM> that may be used for providing negative-pressure and instillation therapy for delivering an antimicrobial solution or other treatment solution to a dressing at a tissue site. In one embodiment, the controller <NUM> receives and processes data, such as data related to fluids provided to the tissue interface <NUM>. Such data may include the type of instillation solution prescribed by a clinician, the volume of fluid or solution to be instilled to the tissue site ("fill volume"), and the amount of time needed to soak the tissue interface ("soak time") before applying a negative pressure to the tissue site. The fill volume may be, for example, between <NUM> and <NUM>, and the soak time may be between one second to <NUM> minutes. The controller <NUM> may also control the operation of one or more components of the therapy system <NUM> to manage the instillation fluids delivered from the solution source <NUM> to the tissue site <NUM> for cleaning and/or providing therapy treatment to the wound along with the negative pressure therapy as described above. In one embodiment, fluid may be instilled to the tissue site <NUM> by applying a negative pressure from the negative-pressure source <NUM> to reduce the pressure at the tissue site <NUM> and draw the instillation fluid into the dressing <NUM> as indicated at <NUM> and described above in more detail. In another embodiment, fluid may be instilled to the tissue site <NUM> by applying a positive pressure from the negative-pressure source <NUM> (not shown) or the instillation pump <NUM> to force the instillation fluid from the solution source <NUM> to the tissue interface <NUM> as indicated at <NUM>. In yet another embodiment, fluid may be instilled to the tissue site <NUM> by elevating the solution source <NUM> to height sufficient to force the instillation fluid into the tissue interface <NUM> by the force of gravity as indicated at <NUM>. Thus, the therapy method <NUM> includes instilling fluid into the tissue interface <NUM> by either drawing or forcing the fluid into the tissue interface <NUM> as indicated at <NUM>.

The therapy method <NUM> may control the fluid dynamics of applying the fluid solution to the tissue interface <NUM> at <NUM> by providing a continuous flow of fluid at <NUM> or an intermittent flow of fluid for soaking the tissue interface <NUM> at <NUM>. The therapy method <NUM> may include the application of negative pressure to the tissue interface <NUM> to provide either the continuous flow or intermittent soaking flow of fluid at <NUM>. The application of negative pressure may be implemented to provide a continuous pressure mode of operation at <NUM> as described above to achieve a continuous flow rate of instillation fluid through the tissue interface <NUM> or a dynamic pressure mode of operation at <NUM> as described above to vary the flow rate of instillation fluid through the tissue interface <NUM>. Alternatively, the application of negative pressure may be implemented to provide an intermittent mode of operation at <NUM> as described above to allow instillation fluid to soak into the tissue interface <NUM> as described above. In the intermittent mode, a specific fill volume and the soak time may be provided depending, for example, on the type of wound being treated and the type of dressing <NUM> being utilized to treat the wound. After or during instillation of fluid into the tissue interface <NUM> has been completed, the therapy method <NUM> may begin may be utilized using any one of the three modes of operation at <NUM> as described above. The controller <NUM> may be utilized to select any one of these three modes of operation and the duration of the negative pressure therapy as described above before commencing another instillation cycle at <NUM> by instilling more fluid at <NUM>.

As discussed above, the tissue site <NUM> may include, without limitation, any irregularity with a tissue, such as an open wound, surgical incision, or diseased tissue. The therapy system <NUM> is presented in the context of a tissue site that includes a wound that may extend through the epidermis and the dermis, and may reach into the hypodermis or subcutaneous tissue. The therapy system <NUM> may be used to treat a wound of any depth, as well as many different types of wounds including open wounds, incisions, or other tissue sites. The tissue site <NUM> may be the bodily tissue of any human, animal, or other organism, including bone tissue, adipose tissue, muscle tissue, dermal tissue, vascular tissue, connective tissue, cartilage, tendons, ligaments, or any other tissue. Treatment of the tissue site <NUM> may include removal of fluids originating from the tissue site <NUM>, such as exudates or ascites, or fluids instilled into the dressing to cleanse or treat the tissue site <NUM>, such as antimicrobial solutions.

As indicated above, the therapy system <NUM> may be packaged as a single, integrated unit such as a therapy system including all of the components shown in <FIG> that are fluidly coupled to the dressing <NUM>. In some embodiments, an integrated therapy unit may include the negative-pressure source <NUM>, the controller <NUM>, the pressure sensor <NUM>, and the container <NUM> which may be fluidly coupled to the dressing interface <NUM>. In this therapy unit, the negative-pressure source <NUM> is indirectly coupled to the dressing interface <NUM> through the container <NUM> by conduit <NUM> and conduit <NUM>, and the pressure sensor <NUM> is indirectly coupled to the dressing interface <NUM> by conduit <NUM> and conduit <NUM> as described above. In some embodiments, the negative pressure conduit <NUM> and the pressure sensing conduit <NUM> may be combined in a single fluid conductor that can be, for example, a multi-lumen tubing comprising a central primary lumen that functions as the negative pressure conduit <NUM> for delivering negative pressure to the dressing interface <NUM> and several peripheral auxiliary lumens that function as the pressure sensing conduit <NUM> for sensing the pressure that the dressing interface <NUM> delivers to the tissue interface <NUM>. In this type of therapy unit wherein the pressure sensor <NUM> is removed from and indirectly coupled to the dressing interface <NUM>, the negative pressure measured by the pressure sensor <NUM> may be different from the wound pressure (WP) actually being applied to the tissue site <NUM>. Such pressure differences must be approximated in order to adjust the negative-pressure source <NUM> to deliver the pump pressure (PP) necessary to provide the desired or target pressure (TP) to the tissue interface <NUM>. Moreover, such pressure differences and predictability may be exacerbated by viscous fluids such as exudates being produced by the tissue site or utilizing a single therapy device including a pressure sensor to deliver negative pressure to multiple tissue sites on a single patient.

What is needed is a pressure sensor that is integrated within the dressing interface <NUM> so that the pressure sensor is proximate the tissue interface <NUM> when disposed on the tissue site in order to provide a more accurate reading of the wound pressure (WP) being provided within the therapy environment of the dressing <NUM>. The integrated pressure sensor may be used with or without the remote pressure sensor <NUM> that is indirectly coupled to the dressing interface <NUM>. In some example embodiments, the dressing interface <NUM> may comprise a housing having a therapy cavity that opens to the tissue site when positioned thereon. The integrated pressure sensor may have a sensing portion disposed within the therapy cavity along with other sensors including, for example, a temperature sensor, a humidity sensor, and a pH sensor. The sensors may be electrically coupled to the controller <NUM> outside the therapy cavity to provide data indicative of the pressure, temperature, humidity, and acidity properties within the therapeutic space of the therapy cavity. The sensors may be electrically coupled to the controller <NUM>, for example, by wireless means. Systems, apparatuses, and methods described herein provide the advantage of more accurate measurements of these properties, as well as other significant advantages described below in more detail.

As indicated above, the dressing <NUM> may include the cover <NUM>, the dressing interface <NUM>, and the tissue interface <NUM>. Referring now to <FIG>, <FIG>, <FIG>, <FIG>, and <FIG>, a first dressing is shown comprising a dressing interface <NUM>, the drape <NUM>, and a tissue interface fluidly coupled to the dressing interface <NUM> through the opening <NUM> of the drape <NUM>. The tissue interface may include the manifold <NUM> and the sealing layer <NUM> disposed adjacent a tissue site <NUM>, all of which may be functionally similar in part to the dressing interface <NUM>, the cover <NUM>, and the tissue interface <NUM>, respectively, as described above. In one example embodiment, the dressing interface <NUM> may comprise a housing <NUM> and a wall <NUM> disposed within the housing <NUM> wherein the wall <NUM> forms a recessed space or a therapy cavity <NUM> that opens to the manifold <NUM> when disposed at the tissue site <NUM> and a component cavity <NUM> opening away from the tissue site <NUM> of the upper portion of the dressing interface <NUM>. In some embodiments, sensing portions of various sensors may be disposed within the therapy cavity <NUM>, and electrical devices associated with the sensors may be disposed within the component cavity <NUM> and electrically coupled to the sensing portions through the wall <NUM>. Electrical devices disposed within the component cavity <NUM> may include components associated with some example embodiments of the therapy system of <FIG>. Although the dressing interface <NUM> and the therapy cavity <NUM> are functionally similar to the dressing interface <NUM> as described above, the dressing interface <NUM> further comprises the wall <NUM>, the sensors, and the associated electrical devices described below in more detail. In some embodiments, the housing <NUM> may further comprise a neck portion or neck <NUM> fluidly coupled to a conduit <NUM>. In some embodiments, the housing <NUM> may further comprise a flange portion or flange <NUM> having flow channels (see <FIG>) configured to be fluidly coupled to the therapy cavity <NUM> when disposed on the manifold <NUM>.

In some example embodiments, the neck <NUM> of the housing <NUM> may include portions of both the therapy cavity <NUM> and the component cavity <NUM>. That portion of the neck <NUM> extending into the therapy cavity <NUM> is fluidly coupled to the conduit <NUM>, while the portion extending into the component cavity <NUM> may contain some of the electrical devices. In some example embodiments, the conduit <NUM> may comprise a primary lumen or a negative pressure lumen <NUM> and separate auxiliary lumens such as, for example, an instillation lumen <NUM> and a venting lumen <NUM> fluidly coupled by the neck <NUM> of the housing <NUM> to the therapy cavity <NUM>. The negative pressure lumen <NUM> is similar to the negative pressure conduit <NUM> that may be coupled indirectly to the negative-pressure source <NUM>. The venting lumen <NUM> is similar to the vent conduit <NUM> that may be fluidly coupled to the vent regulator <NUM> for purging fluids from the therapy cavity <NUM>. The instillation lumen <NUM> is similar to the instillation conduit <NUM> that may be fluidly coupled directly or indirectly to the solution source <NUM> for flushing fluids from the therapy cavity <NUM> for removal by the application of negative pressure through the negative pressure lumen <NUM>.

In some embodiments, the component cavity <NUM> containing the electrical devices may be open to the ambient environment such that the electrical devices are exposed to the ambient environment. In other example embodiments, the component cavity <NUM> may be closed by a cover such as, for example, a cap <NUM> to protect the electrical devices. In still other embodiments, the component cavity <NUM> covered by the cap <NUM> may still be vented to the ambient environment to provide cooling to the electrical devices and a source of ambient pressure for a pressure sensor disposed in the therapy cavity <NUM> as described in more detail below. The first dressing interface <NUM> may further comprise a drape ring <NUM> covering the circumference of the flange <NUM> and the adjacent portion of the drape <NUM> to seal the therapy cavity <NUM> of the housing <NUM> over the manifold <NUM> and the tissue site <NUM>. In some embodiments, the drape ring <NUM> may comprise a polyurethane film including and an attachment device such as, for example, an acrylic, polyurethane gel, silicone, or hybrid combination of the foregoing adhesives (not shown) to attach the drape ring <NUM> to the flange <NUM> and the drape <NUM>. The attachment device of drape ring <NUM> may be a single element of silicon or hydrocolloid with the adhesive on each side that functions as a gasket between the drape <NUM> and the flange <NUM>. In some embodiments, the drape ring <NUM> may be similar to the cover <NUM> and/or the attachment device described above in more detail.

In some embodiments, a pressure sensor <NUM>, humidity sensor <NUM>, and a temperature that may be a component of the humidity sensor <NUM> (collectively referred to below as "the sensors") may be disposed in the housing <NUM> with each one having a sensing portion extending into the therapy cavity <NUM> of the housing <NUM> and associated electronics disposed within the component cavity <NUM>. The housing <NUM> may include other types of sensors, or combinations of the foregoing sensors, such as, for example, oxygen sensors. In some example embodiments, the sensors may be coupled to or mounted on the wall <NUM> and electrically coupled to electrical components and circuits disposed within the component cavity <NUM> by electrical conductors extending through the wall <NUM>. In some preferred embodiments, the electrical conductors extend through pathways in the wall <NUM> while keeping the therapy cavity <NUM> electrically and pneumatically isolated from the component cavity <NUM>. For example, the wall <NUM> may comprise a circuit board <NUM> on which the electrical circuits and/or components may be printed or mounted. In some other examples, the circuit board <NUM> may be the wall <NUM> that covers an opening between the therapy cavity <NUM> and the component cavity <NUM>, and pneumatically seals the therapy cavity <NUM> from the component cavity <NUM> when seated over the opening.

In some embodiments, the electrical circuits and/or components associated with the sensors that are mounted on the circuit board <NUM> within the component cavity <NUM> may be electrically coupled to the controller <NUM> to interface with the rest of the therapy system <NUM> as described above. In some embodiments, for example, the electrical circuits and/or components may be electrically coupled to the controller <NUM> by a conductor that may be a component of the conduit <NUM>. In some other preferred embodiments, a communications module <NUM> may be disposed in the component cavity <NUM> of the housing <NUM> and mounted on the circuit board <NUM> within the component cavity <NUM>. Using a wireless communications module <NUM> has the advantage of eliminating an electrical conductor between the dressing interface <NUM> and the integrated portion of the therapy system <NUM> that may become entangled with the conduit <NUM> when in use during therapy treatments. For example, the electrical circuits and/or components associated with the sensors along with the terminal portion of the sensors may be electrically coupled to the controller <NUM> by wireless means such as an integrated device implementing Bluetooth® Low Energy wireless technology. More specifically, the communications module <NUM> may be a Bluetooth® Low Energy system-on-chip that includes a microprocessor (an example of the microprocessors referred to hereinafter) such as the nRF51822 chip available from Nordic Semiconductor. The wireless communications module <NUM> may be implemented with other wireless technologies suitable for use in the medical environment.

In some embodiments, a voltage regulator <NUM> for signal conditioning and a power source <NUM> may be disposed within the component cavity <NUM> of the housing <NUM>, and mounted on the circuit board <NUM>. The power source <NUM> may be secured to the circuit board <NUM> by a bracket <NUM>. The power source <NUM> may be, for example, a battery that may be a coin battery having a low-profile that provides a <NUM>-volt source for the communications module <NUM> and the other electronic components within the component cavity <NUM> associated with the sensors. In some example embodiments, the sensors, the electrical circuits and/or components associated with the sensors, the wall <NUM> and/or the circuit board <NUM>, the communications module <NUM>, and the power source <NUM> may be integrated into a single package and referred to hereinafter as a sensor assembly <NUM> as shown in <FIG>. In some preferred embodiments, the wall <NUM> of the sensor assembly <NUM> may be the circuit board <NUM> itself as described above that provides a seal between tissue site <NUM> and the atmosphere when positioned over the opening between the therapy cavity <NUM> and the component cavity <NUM> of the housing <NUM> and functions as the wall <NUM> within the housing <NUM> that forms the therapy cavity <NUM>.

Referring now to <FIG>, a perspective view and a bottom view, respectively, of a bottom surface of the flange <NUM> facing the manifold <NUM> is shown. In some embodiments, the bottom surface may comprise features or channels to direct the flow of liquids and/or exudates away from the sensors out of the therapy cavity <NUM> into the negative pressure lumen <NUM> when negative pressure is being applied to the therapy cavity <NUM>. In some embodiments, these channels may be molded into the bottom surface of the flange <NUM> to form a plurality of serrated guide channels <NUM>, perimeter collection channels <NUM>, and intermediate collection channels <NUM>. The serrated guide channels <NUM> may be positioned and oriented in groups on bottom surface to directly capture and channel at least half of the liquids being drawn into the therapy cavity <NUM> with the groups of serrated guide channels <NUM>, and indirectly channel a major portion of the balance of the liquids being drawn into the therapy cavity <NUM> between the groups of serrated guide channels <NUM>. In addition, perimeter collection channels <NUM> and intermediate collection channels <NUM> redirect the flow of liquids that are being drawn in between the groups of radially-oriented serrated guide channels <NUM> into the guide channels <NUM>. An example of this redirected flow is illustrated by bolded flow arrows <NUM>. In some example embodiments, a portion of the housing <NUM> within the therapy cavity <NUM> may comprise a second set of serrated guide channels <NUM> spaced apart and radially-oriented to funnel liquids being drawn into the therapy cavity <NUM> from the flange <NUM> into the negative pressure lumen <NUM>. In other example embodiments of the bottom surface of the flange <NUM> and that portion of the housing <NUM> within the therapy cavity <NUM>, the channels may be arranged in different patterns.

As indicated above, the sensor assembly <NUM> may comprise a pressure sensor <NUM>, a humidity sensor <NUM>, and a temperature sensor as a component of either the pressure sensor <NUM> or the humidity sensor <NUM>. Each of the sensors may comprise a sensing portion extending into the therapy cavity <NUM> of the housing <NUM> and a terminal portion electrically coupled to the electrical circuits and/or components within the component cavity <NUM>. Referring more specifically to <FIG>, <FIG>, <FIG>, and <FIG>, the housing <NUM> may comprise a sensor bracket <NUM> that may be a molded portion of the housing <NUM> within the therapy cavity <NUM> in some embodiments. The sensor bracket <NUM> may be structured to house and secure the pressure sensor <NUM> on the circuit board <NUM> within the therapy cavity <NUM> of the sensor assembly <NUM> that provides a seal between tissue site <NUM> and the atmosphere as described above. In some embodiments, the pressure sensor <NUM> may be a differential gauge comprising a sensing portion <NUM> and a terminal portion or vent <NUM>. The vent <NUM> of the pressure sensor <NUM> may be fluidly coupled through the circuit board <NUM> to the component cavity <NUM> and the atmosphere by a vent hole <NUM> extending through the circuit board <NUM>. Because the component cavity <NUM> is vented to the ambient environment, the vent <NUM> of the pressure sensor <NUM> is able to measure the wound pressure (WP) with reference to the ambient pressure. The sensing portion <NUM> of the pressure sensor <NUM> may be positioned in close proximity to the manifold <NUM> to optimize fluid coupling and accurately measure the wound pressure (WP) at the tissue site <NUM>. In some embodiments, the pressure sensor <NUM> may be a piezo-resistive pressure sensor having a pressure sensing element covered by a dielectric gel such as, for example, a Model TE <NUM> pressure sensor available from TE Connectivity. The dielectric gel provides electrical and fluid isolation from the blood and wound exudates in order to protect the sensing element from corrosion or other degradation. This allows the pressure sensor <NUM> to measure the wound pressure (WP) directly within the therapy cavity <NUM> of the housing <NUM> proximate to the manifold <NUM> as opposed to measuring the wound pressure (WP) from a remote location. In some embodiments, the pressure sensor <NUM> may be a gauge that measures the absolute pressure that does not need to be vented.

In some embodiments, the pressure sensor <NUM> also may comprise a temperature sensor for measuring the temperature at the tissue site <NUM>. In other embodiments, the humidity sensor <NUM> may comprise a temperature sensor for measuring the temperature at the tissue site <NUM>. The sensor bracket <NUM> also may be structured to support the humidity sensor <NUM> on the circuit board <NUM> of the sensor assembly <NUM>. In some embodiments, the humidity sensor <NUM> may comprise a sensing portion that is electrically coupled through the circuit board <NUM> to a microprocessor mounted on the other side of the circuit board <NUM> within the component cavity <NUM>. The sensing portion of the humidity sensor <NUM> may be fluidly coupled to the space within the therapy cavity <NUM> that includes a fluid pathway <NUM> extending from the therapy cavity <NUM> into the negative pressure lumen <NUM> of the conduit <NUM> as indicated by the bold arrow to sense both the humidity and the temperature. The sensing portion of the humidity sensor <NUM> may be positioned within the fluid pathway <NUM> to limit direct contact with bodily fluids being drawn into the negative pressure lumen <NUM> from the tissue site <NUM>. In some embodiments, the space within the therapy cavity <NUM> adjacent the sensing portion of the humidity sensor <NUM> may be purged by venting the space through the venting lumen <NUM> as described in more detail below. The space may also be flushed by instilling fluids into the space through the instillation lumen <NUM>. As indicated above, the humidity sensor <NUM> may further comprise a temperature sensor (not shown) as the location within the fluid pathway <NUM> is well-suited to achieve accurate readings of the temperature of the fluids. In some embodiments, the humidity sensor <NUM> that comprises a temperature sensor may be a single integrated device such as, for example, Model TE HTU21D(F) humidity sensor also available from TE Connectivity.

In some example embodiments, the dressing <NUM> may further comprise a pH sensor or pH sensors having a sensing portion adapted to be positioned between the sealing layer <NUM> and the tissue site <NUM> and configured to detect a pH level of fluid present at the tissue site for providing a pH output based on the pH level detected. Referring again to <FIG>, <FIG>, and <FIG>, for example, the dressing <NUM> may include an interior pH sensor <NUM> having a head or a sensing portion <NUM> positioned adjacent the interior portion <NUM> of the sealing layer <NUM> and a peripheral pH sensor <NUM> having a head or a sensing portion <NUM> positioned adjacent the periphery <NUM> of the sealing layer <NUM>. In other embodiments, the dressing <NUM> may comprise multiple peripheral pH sensors at different locations around the periphery <NUM> of the sealing layer <NUM>. For example, the peripheral pH sensor <NUM> may be positioned on a portion of the epidermis immediately adjacent the tissue site <NUM>, such as at a periwound region, while a second peripheral pH sensor may be positioned on the epidermis at a greater distance away from the tissue site <NUM>. Thus, by configuring the dressing <NUM> to include one or more pH sensors for detecting or measuring the pH at different locations within or outside of the tissue site <NUM>, the controller <NUM> in conjunction with the other components of the therapy system <NUM> may be able to determine whether a particular pH parameter is localized to a specific portion of the tissue site <NUM> or the surrounding tissue. The controller <NUM> may also be able to compare pH measurements obtained from different locations throughout the tissue site <NUM> or the surrounding tissue.

Some embodiments of the pH sensors comprising a sensing portion as described above may be electrically coupled through the circuit board <NUM> to a front-end amplifier <NUM> mounted on the other side of the circuit board <NUM> within the component cavity <NUM>. For example, the sensing portion <NUM> of the interior pH sensor <NUM> may have a terminal portion <NUM> directly coupled to the front-end amplifier <NUM> or indirectly by a conductor <NUM>. The sensing portion <NUM> of the peripheral pH sensor <NUM> also may have a terminal portion <NUM> directly coupled to the front-end amplifier <NUM> or indirectly by a conductor <NUM>. In some embodiments, the terminal portion of the pH sensors or the conductors <NUM> and <NUM> may extend through the sealing layer <NUM>, and may be combined as a single conduit <NUM> that may be electrically coupled to the front-end amplifier <NUM>. In some embodiments, the conductors <NUM> and <NUM> may be manufactured as a component of the sealing layer <NUM> or threaded through additional apertures extending through the sealing layer <NUM> when the dressing <NUM> is being applied to the tissue site <NUM> as described below.

The front-end amplifier <NUM> comprises analog signal conditioning circuitry that includes sensitive analog amplifiers such as, for example, operational amplifiers, filters, and application-specific integrated circuits. The front-end amplifier <NUM> measures minute voltage potential changes provided by the sensing portions to provide an output signal indicative of the pH of the fluids within or surrounding the tissue site <NUM>. The front-end amplifier <NUM> may be, for example, an extremely accurate voltmeter that measures the voltage potential between the working electrode <NUM> and the reference electrode <NUM>. The front-end amplifier <NUM> may be for example a high impedance analog front-end (AFE) device such as the LMP7721 and LMP91200 chips that are available from manufacturers such as Texas Instruments or the AD7793 and AD8603 chips that are available from manufacturers such as Analog Devices.

Measuring the pH level of the fluids within or surrounding the tissue site <NUM> is an important indicator of wound health. For example, a slightly acidic pH level between about <NUM> and about <NUM>, may be considered as being optimal for wound healing in some embodiments, while a pH level outside this range, and particularly an alkaline pH level, may indicate that the wound has stalled. Separate equipment or instruments used to measure the pH level externally that are not integrated into the dressing have been used to measure the pH level of the wound during dressing changes that may occur, for example, every three days which provides infrequent data that is insufficient to form detailed trend information at one location in the wound or information at multiple locations in and around the wound, especially over large wound areas. By placing the pH sensors within the dressing itself between the sealing layer <NUM> and the tissue site <NUM> underneath the tissue interface <NUM> for measuring the pH level during the application of negative pressure therapy rather than during dressing changes, the pH level can be measured more frequently such as, for example every five minutes. As a result, valuable information regarding the healing process may be obtained that is sufficient to define trends at a single location and/or identify variations between different locations at the tissue site <NUM>. Positioning the pH sensors in direct contact with the tissue site underneath such tissue interfaces described above may provide a more accurate measurement of the pH level.

Additionally, the therapy system <NUM> and/or the microprocessor of the communications module <NUM> may be programmed to detect the time rate of change of the pH to provide additional information regarding the healing process. In one example embodiment, the dressing interface <NUM> may further comprise an indicator <NUM> electrically coupled to the microprocessor of the communication module <NUM> to provide a visual indication indicating that there may be an unfavorable change of the pH and/or temperature of the wound or the skin that may indicate the presence of an infection. For example, the system <NUM> may be programmed to provide a warning from the indicator <NUM> when the time rate of change from the acidic pH is more than about <NUM>% over a <NUM> hour period. The indicator <NUM> may provide a visual, audible, or any other indication to warn the user or the caregiver.

Referring to <FIG>, the interior pH sensor <NUM> and/or the peripheral pH sensor <NUM> may be, for example, pH sensor <NUM> comprising a pair of printed medical electrodes including a working electrode <NUM> and a reference electrode <NUM>. In some embodiments, the working electrode <NUM> may have a node being substantially circular in shape at one end and having a terminal portion at the other end. The reference electrode <NUM> may have a node substantially semicircular in shape and disposed around the node of the working electrode <NUM>, and also may have a terminal portion at the other end. In some example embodiments, the working electrode <NUM> may comprise a material selected from a group including graphene oxide ink, conductive carbon, carbon nanotube inks, silver, nano-silver, silver chloride ink, gold, nano-gold, gold-based ink, metal oxides, conductive polymers, or a combination thereof. This working electrode <NUM> further comprise a coating or film applied over the material wherein such coating or film may be selected from a group including metal oxides such as, for example, tungsten, platinum, iridium, ruthenium, and antimony oxides, or a group of conductive polymers such as polyaniline and others so that the conductivity of the working electrode <NUM> changes based on changes in hydrogen ion concentration of the fluids being measured or sampled. In some example embodiments, the reference electrode <NUM> may comprise a material selected from a group including silver, nano-silver, silver chloride ink, or a combination thereof. The pH sensor <NUM> may further comprise a coating <NUM> covering the electrodes that insulates and isolates the working electrode <NUM> from the reference electrode <NUM> and the wound fluid, except for an electrically conductive space <NUM> between the nodes of the working electrode <NUM> and the reference electrode <NUM>. In some embodiments, the coating <NUM> does not completely cover the terminal portions of the working electrode <NUM> and the reference electrode <NUM> to form terminals <NUM> and <NUM>, respectively. The terminals <NUM> and <NUM> may be electrically coupled to the front-end amplifier <NUM>. In some embodiments, the terminals <NUM> and <NUM> may be electrically coupled to the front-end amplifier <NUM> by the conductors <NUM> and <NUM>.

In some other embodiments, the interior pH sensor <NUM> and/or the peripheral pH sensor <NUM> may include a third electrode such as, for example, pH sensor <NUM> shown in <FIG> that comprises a third electrode or a counter electrode <NUM> in addition to the working electrode <NUM> and the reference electrode <NUM> of the pH sensor <NUM>. The counter electrode <NUM> also comprises a node partially surrounding the node of the working electrode <NUM> and a terminal <NUM> adapted to be electrically coupled to the front-end amplifier <NUM>. Otherwise, the pH sensor <NUM> is substantially similar to the pH sensor <NUM> described above as indicated by the reference numerals. The counter electrode <NUM> is also separated from the working electrode <NUM> and is also insulated from the wound fluid and the other electrodes by the coating <NUM> except in the electrical conductive space <NUM>. The counter electrode <NUM> may be used in connection with the working electrode <NUM> and the reference electrode <NUM> for the purpose of error correction of the voltages being measured. For example, the counter electrode <NUM> may possess the same voltage potential as the potential of the working electrode <NUM> except with an opposite sign so that any electrochemical process affecting the working electrode <NUM> will be accompanied by an opposite electrochemical process on the counter electrode <NUM>. Although voltage measurements are still being taken between the working electrode <NUM> and the reference electrode <NUM> by the analog front end device of the pH sensor <NUM>, the counter electrode <NUM> may be used for such error correction and may also be used for current readings associated with the voltage measurements. Custom printed electrodes assembled in conjunction with a front-end amplifier may be used to partially comprise pH sensors such as the pH sensor <NUM> and the pH sensor <NUM> may be available from several companies such as, for example, GSI Technologies, Inc. and Dropsens.

In some embodiments, the tissue interfaces described above may comprise a film underside such as, for example, the sealing layer <NUM>. In some embodiments, the pH sensors may be printed directly on the sealing layer <NUM> to form a thin and flexible sensor or a separate film layer having a smooth surface (not shown). The separate layer may be, for example, another polyurethane film which is then bonded to the sealing layer <NUM>. In some embodiments, the pH sensors may be screen-printed onto a separate mylar (PET) substrate or directly onto the polyurethane sealing layer utilizing silver chloride, graphene, or other conductive inks, for example. Additional perforations or apertures may be formed in the sealing layer <NUM> to ensure adequate fluid flow around the pH sensor. However, some preferable embodiments do not include any perforations or apertures in the region of the head or sensing portions <NUM>, <NUM> of the pH sensors <NUM>, <NUM> to avoid impacting the conduction of the electrically conductive space <NUM> between the nodes of the working electrode <NUM> and the reference electrode <NUM>. In some preferred embodiments, the tail or terminal portion of the pH sensors such as, for example, terminal portions <NUM>, <NUM>, may have a thickness when printed in the range of about <NUM> to about <NUM>. In such embodiments, the terminal portions <NUM>, <NUM> may be electrically insulated, but sufficiently far away from the sensing portions <NUM>, <NUM> to avoid impacting the conductivity of the sensing portions <NUM>, <NUM> as described above. In some embodiments, the terminal portions <NUM>, <NUM> may be coated with Teflon.

In some embodiments after printing, the pH sensors <NUM>, <NUM> may be functionalized by electrodepositing the working electrode <NUM> with iridium oxide so that the conductivity of the working electrode <NUM> is variable and dependent on the local hydrogen concentration or pH as described above. Thus, the measured potential or voltage between the working electrode <NUM> and the reference electrode <NUM> is also sensitive to local changes in hydrogen concentration or the pH at the tissue site.

In some other example embodiments, the tissue interface may comprise a smooth surface integrated with the tissue-facing side of a manifold such as, for example, the manifold <NUM> that may include a smooth surface underneath (not shown). In such embodiments, the pH sensors may be printed directly on the smooth surface of the manifold to form a tissue interface integrated with the pH sensors. In some embodiments, the pH sensors <NUM>, <NUM> may be screen-printed onto directly onto the smooth surface of the manifold <NUM> utilizing silver chloride, graphene, or other conductive inks, for example, as described above.

The pH sensors may be positioned at various pH sites within the central portion <NUM> and around the periphery <NUM> of the sealing layer <NUM>, as well as in the periwound region. In some embodiments, each of these pH sensors may be printed as an array of individual pH sensors positioned at the pH sites and/or as an array of individual pH sensors at each of the pH sites. In such embodiments, each of the individual pH sensors may be electrically coupled to front-end amplifier <NUM> as described above.

The systems, apparatuses, and methods described herein may provide other significant advantages. For example, some therapy systems are a closed system wherein the pneumatic pathway is not vented to ambient air, but rather controlled by varying the supply pressure (SP) to achieve the desired target pressure (TP) in a continuous pressure mode, an intermittent pressure mode, or a variable target pressure mode as described above in more detail with reference to <FIG>. In some embodiments of the closed system, the wound pressure (WP) being measured in the dressing interface <NUM> may not drop in response to a decrease in the supply pressure (SP) as a result of a blockage within the dressing interface <NUM> or other portions of the pneumatic pathway. In some embodiments of the closed system, the supply pressure (SP) may not provide airflow to the tissue interface <NUM> frequently enough that may result in the creation of a significant head pressure or blockages within the dressing interface <NUM> that also would interfere with sensor measurements being taken by the dressing interface <NUM> as described above. The head pressure in some embodiments may be defined as a difference in pressure (DP) between a negative pressure set by a user or caregiver for treatment, i.e., the target pressure (TP), and the negative pressure provided by a negative pressure source that is necessary to offset the pressure drop inherent in the fluid conductors, i.e., the supply pressure (SP), in order to achieve or reach the target pressure (TP). For example, the head pressure that a negative pressure source needs to overcome may be as much as <NUM> mmHg. Problems may occur in such closed systems when a blockage occurs in the pneumatic pathway of the fluid conductors that causes the negative pressure source to increase to a value above the normal supply pressure (SP) as a result of the blockage. For example, if the blockage suddenly clears, the instantaneous change in the pressure being supplied may cause harm to the tissue site.

Some therapy systems have attempted to compensate for head pressure by introducing a supply of ambient air flow into the therapeutic environment, e.g., the therapy cavity <NUM>, by providing a vent with a filter on the housing <NUM> of the dressing interface <NUM> to provide ambient air flow into the therapeutic environment as a controlled leak. However, in some embodiments, the filter may be blocked when the interface dressing is applied to the tissue site or when asked at least blocked during use. Locating the filter in such a location may also be problematic because it is more likely to be contaminated or compromised by other chemicals and agents associated with treatment utilizing instillation fluids that could adversely affect the performance of the filter and the vent itself.

The embodiments of the therapy systems described herein overcome the problems associated with having a large head pressure in a closed pneumatic environment, and the problems associated with using a vent disposed on or adjacent the dressing interface. More specifically, the embodiments of the therapy systems described above comprise a pressure sensor, such as the pressure sensor <NUM>, disposed within the pneumatic environment, i.e., in situ, that independently measures the wound pressure (WP) within the therapy cavity <NUM> of the housing <NUM> as described above rather than doing so remotely. Consequently, the pressure sensor <NUM> is able to instantaneously identify dangerously high head pressures and/or blockages within the therapy cavity <NUM> adjacent the manifold <NUM>. Because the auxiliary lumens are not being used for pressure sensing, the venting lumen <NUM> may be fluidly coupled to a fluid regulator such as, for example, the vent regulator <NUM> in <FIG>, that may remotely vent the therapeutic environment within the therapy cavity <NUM> to the ambient environment or fluidly couple the therapeutic environment to a source of positive pressure. The vent regulator <NUM> may then be used to provide ambient air or positive pressure to the therapeutic environment in a controlled fashion to "purge" the therapeutic environment within both the therapy cavity <NUM> to resolve the problems identified above regarding head pressures and blockages.

Using a regulator to purge the therapeutic environment is especially important in therapy systems such as those disclosed in <FIG> and <FIG> that provide both negative pressure therapy and instillation therapy for delivering therapeutic fluids to a tissue site. For example, in one embodiment, therapeutic fluid may be instilled to the tissue site <NUM> by applying a negative pressure from the negative-pressure source <NUM> to reduce the pressure at the tissue site <NUM> to draw the therapeutic fluid into the dressing <NUM> as indicated at <NUM>. In another embodiment, therapeutic fluid may be instilled to the tissue site <NUM> by applying a positive pressure from the negative-pressure source <NUM> (not shown) or the instillation pump <NUM> to force the therapeutic fluid from the solution source <NUM> to the tissue interface <NUM> as indicated at <NUM>. Such embodiments may not be sufficient to remove all the therapeutic fluid from the therapeutic environment, or may not be sufficient to remove the therapeutic fluid quickly enough from the therapeutic environment to facilitate the continuation of accurate temperature, humidity, and pH measurements. Thus, the venting lumen <NUM> may be used to provide ambient air or positive pressure to the therapeutic environment to more completely or quickly purge the therapeutic environment to obtain the desired measurements as described above.

In embodiments of therapy systems that include an air flow regulator comprising a valve such as the solenoid valve described above, the valve provides controlled airflow venting or positive pressure to the therapy cavity <NUM> as opposed to a constant airflow provided by a closed system or an open system including a filter in response to the wound pressure (WP) being sensed by the pressure sensor <NUM>. The controller <NUM> may be programmed to periodically open the solenoid valve as described above allowing ambient air to flow into the therapy cavity <NUM>, or applying a positive pressure into the therapy cavity <NUM>, at a predetermined flow rate and/or for a predetermined duration of time to purge the pneumatic system including the therapy cavity <NUM> and the negative pressure lumen <NUM> of bodily liquids and exudates so that the humidity sensor <NUM> and the pH sensors <NUM>,<NUM> provide more accurate readings and in a timely fashion. This feature allows the controller to activate the solenoid valve in a predetermined fashion to purge blockages and excess liquids that may develop in the fluid pathways or the therapy cavity <NUM> during operation. In some embodiments, the controller may be programmed to open the solenoid valve for a fixed period of time at predetermined intervals such as, for example, for five seconds every four minutes to mitigate the formation of any blockages.

In some other embodiments, the controller may be programmed to open the solenoid valve in response to a stimulus within the pneumatic system rather than, or additionally, being programmed to function on a predetermined therapy schedule. For example, if the pressure sensor is not detecting pressure decay in the canister, this may be indicative of a column of fluid forming in the fluid pathway or the presence of a blockage in the fluid pathway. Likewise, the controller may be programmed to recognize that an expected drop in canister pressure as a result of the valve opening may be an indication that the fluid pathway is open. The controller may be programmed to conduct such tests automatically and routinely during therapy so that the patient or caregiver can be forewarned of an impending blockage. The controller may also be programmed to detect a relation between the extent of the deviation in canister pressure resulting from the opening of the valve and the volume of fluid with in the fluid pathway. For example, if the pressure change within the canister is significant when measured, this could be an indication that there is a significant volume of fluid within the fluid pathway. However, if the pressure change within the canister is not significant, this could be an indication that the plenum volume was larger.

The systems, apparatuses, and methods described herein may provide additional advantages related to the instillation of cleansing and/or therapeutic solutions to the therapy cavity <NUM>. Using a source of fluids such as, for example, solution source <NUM> to flush the therapeutic environment is especially important in therapy systems such as those disclosed in <FIG> and <FIG> that provide both negative pressure therapy and instillation therapy for delivering therapeutic fluids to a tissue site. For example, the sensors are disposed within the therapy cavity <NUM> and consequently exposed and in direct conflict with wound fluids and exudates that have the potential for fouling the sensors so that they do not provide reliable data over a period of time during which therapy is being provided. Moreover, fouling the sensors may also disable the sensors and/or degrade the calibration of the sensors such that they no longer accurately analyze the wound fluid to provide data indicating the current state of the wound. Additionally, some of the sensors such as, for example, the pH sensors <NUM>,<NUM> comprising screen-printed electrodes as described above require soaking or hydration to ensure stable measurement of the potential difference between the electrodes, i.e., the voltage between the working and the reference electrodes. Manual cleaning or hydration (lavage) of the sensors would not work because the therapeutic cavity would not be conveniently accessible as it would require the removal of the dressing to provide sufficient access to the tissue interface <NUM>. Thus, the ability to provide cleansing and/or therapeutic solutions directly to the therapy cavity <NUM> for cleansing or hydration as described above along with the ability to deliver negative pressure and other pH-modulating controlled instillates such as phosphate buffered saline or weak acidic acids is a distinct advantage to enhance operation of the systems and methods described herein.

As described above in more detail, some embodiments of the therapy system <NUM> may include a solution source, such as solution source <NUM>, without an instillation pump, such as the instillation pump <NUM>. Instead, the solution source <NUM> may be fluidly coupled directly or indirectly to the dressing interface <NUM>, and may further include the instillation regulator <NUM> electrically coupled to the controller <NUM> as described above. In operation, the negative pressure source <NUM> may apply negative pressure to the therapy cavity <NUM> through the container <NUM> and the negative pressure lumen <NUM> to create a vacuum within the space formed by the therapy cavity <NUM> and the tissue interface <NUM>. The vacuum within the space would draw cleansing and/or hydration fluid from the solution source <NUM> and through the instillation lumen <NUM> into the space for cleansing or wetting the sensors and/or the tissue interface <NUM>. In some embodiments, the controller <NUM> may be programmed to modulate the instillation regulator <NUM> to control the flow of such fluids into the space. Any of the embodiments described above may be utilized to periodically clean, rinse, or hydrate the sensors, the tissue interface, and the tissue site using saline along with other pH-modulating instillation fluids such as weak acidic acids.

In operation, the tissue interface <NUM> may be placed within, over, on, or otherwise proximate a tissue site, such as tissue site <NUM>. The cover <NUM> may be placed over the tissue interface <NUM> and sealed to an attachment surface near the tissue site <NUM>. Thus, the dressing <NUM> can provide a sealed therapeutic environment proximate to a tissue site, substantially isolated from the external environment, and the negative-pressure source <NUM> can reduce the pressure in the sealed therapeutic environment.

Some embodiments of therapy systems including, for example, the therapy system <NUM> including the dressing <NUM>, are illustrative of a method for providing reduced-pressure to a tissue interface and sensing properties of fluids extracted from a tissue site for treating the tissue. In one example embodiment, the method may comprise positioning a tissue interface on the tissue site, wherein the tissue interface has a first layer comprising foam and a second layer comprising a plurality of apertures. In some embodiments, the second layer may be adapted to be positioned between the first layer and the tissue site. In some embodiments, the method may further comprise positioning a sensing portion of a pH sensor between the second layer and the tissue site. In some embodiments, the method may further comprise positioning an opening of a dressing interface on the first layer, wherein the dressing interface includes a housing having a therapy cavity including the opening and a component cavity fluidly isolated from the therapy cavity. In some embodiments, the method may further comprise electrically coupling the pH sensor to a microprocessor disposed within the component chamber. In some embodiments, the method may further comprise detecting a pH level of fluid present at the tissue site based on a pH output provided by the first pH sensor to the microprocessor based on the pH level detected.

The dressing interface may further comprise a temperature sensor, a humidity sensor, and a pressure sensor, each having a sensing portion disposed within the therapy cavity and each electrically coupled to the microprocessor. The method may further comprise applying reduced pressure to the therapy cavity to draw fluids from the tissue interface into the therapy cavity and out of a reduced-pressure port. The method may further comprise sensing the pH, temperature, humidity, and pressure properties of the fluids flowing through therapy cavity utilizing the sensing portion of the sensors and outputting signals from the sensors to the microprocessor. The method may further comprise providing fluid data from the microprocessor indicative of such properties, and inputting the fluid data from the control device to the therapy system for processing the fluid data and treating the tissue site in response to the fluid data.

The systems, apparatuses, and methods described herein may provide other significant advantages over dressing interfaces currently available. For example, a patient may require two dressings for two tissue sites, but wish to use only a single therapy device to provide negative pressure to and collect fluids from the multiple dressings to minimize the cost of therapy. In some therapy systems currently available, two dressing interfaces may be fluidly coupled to the single therapy device by a Y-connector. The problem with this arrangement is that the Y-connector embodiment would not permit the pressure sensor in the therapy device to measure the wound pressure in both dressings independently from one another. A significant advantage of using a dressing interface including in situ sensors, e.g., the dressing interface <NUM> including the sensor assembly <NUM> and the pressure sensor <NUM>, is that multiple dressings may be fluidly coupled to the therapy unit of a therapy system and independently provide pressure data to the therapy unit regarding the associated dressing interface. Each dressing interface <NUM> that is fluidly coupled to the therapy unit for providing negative pressure to the tissue interface <NUM> and collecting fluids from the tissue interface <NUM> has the additional advantage of being able to collect and monitor other information at the tissue site, as well as the humidity data, temperature data, and the pH data being provided by the in situ sensors the sensor assembly <NUM>. For example, the sensor assembly <NUM> may include accelerometers to determine the patient's compliance with specific therapy treatments including various exercise routines and/or various immobilization requirements.

Another advantage of using the dressing interface <NUM> that includes a pressure sensor in situ such as, for example, the pressure sensor <NUM>, is that the pressure sensor <NUM> can more accurately monitor the wound pressure (WP) at the tissue site and identify blockages and fluid leaks that may occur within the therapeutic space as described in more detail above. Another advantage of using a dressing interface including in situ sensors, e.g., the dressing interface <NUM>, is that the sensor assembly <NUM> provides additional data including pressure, temperature, humidity, and pH of the fluids being drawn from the tissue site that facilitates improved control algorithms and wound profiling to further assist the caregiver with additional information provided by the therapy unit of the therapy system to optimize the wound therapy being provided and the overall healing progression of the tissue site when combined with appropriate control logic.

Claim 1:
A dressing (<NUM>) for treating a tissue site (<NUM>), comprising:
a tissue interface (<NUM>) having a first layer comprising a foam and a second layer comprising a plurality of apertures (<NUM>), the second layer adapted to be positioned between the first layer and the tissue site (<NUM>);
a dressing interface (<NUM>) having a housing (<NUM>) including a therapy cavity (<NUM>) and a component cavity (<NUM>) fluidly isolated from the therapy cavity (<NUM>), the therapy cavity (<NUM>) having an opening adapted to be in fluid communication with the first layer and a port adapted to be fluidly coupled to a negative-pressure source (<NUM>);
a control device (<NUM>) disposed within the component cavity (<NUM>) and including a microprocessor; and
a first pH sensor (<NUM>, <NUM>) having a sensing portion (<NUM>, <NUM>) adapted to be positioned between the second layer and the tissue site (<NUM>) and electrically coupled to the microprocessor, the first pH sensor (<NUM>, <NUM>) configured to detect a pH level of fluid present at the tissue site (<NUM>) and to provide a pH output to the microprocessor based on the pH level detected.