Closed-loop system for determining optimal infusion volume for infusion by negative pressure occlusion therapy

Abstract

A system and method for treating a tissue site are described. The system includes an infusion source configured to provide an infusion solution to the tissue site and a negative pressure source configured to draw fluid from the tissue site to generate a negative pressure at the tissue site. The system also includes a controller communicatively coupled to the infusion source and the negative pressure source. The controller is configured to operate the infusion source and to operate the negative pressure source. The system also includes a sensor communicatively coupled to the controller and operably coupled to the infusion source and the negative pressure source. The sensor is configured to generate a signal indicative of the amount of fluid delivered to the tissue site and the amount of fluid recovered from the tissue site.

Description

Technical Field

[0001] (Cross - Reference to Related Applications) This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 388,867, filed on July 13, 2022, which is hereby incorporated by reference in its entirety.

[0002] The invention described in the appended claims generally relates to system volume determination in a tissue treatment system, and more particularly, but not by way of limitation, to determining the infusion volume of a tissue site.

Background Art

[0003] Clinical research and clinical practice have shown that reducing the pressure near a tissue site can enhance and accelerate the growth of new tissue at that tissue site. There are many applications of this phenomenon, but it has proven to be particularly advantageous for treating wounds. Whether it is a trauma, a surgery, or another cause, appropriate care of the wound, regardless of its etiology, is important for the outcome. The treatment of wounds or other tissues using negative pressure may generally be referred to as "negative pressure therapy", but is also known by other names, including, for example, "negative pressure wound therapy", "vacuum - assisted closure", "vacuum therapy", "vacuum - assisted closure", and "local negative pressure". Negative pressure therapy can provide several benefits, including the movement of epithelial and subcutaneous tissues, improved blood flow, and micro - deformation of tissues at the wound site. Overall, these benefits can enhance the development of granulation tissue and shorten the healing time.

[0004] It is also widely accepted that cleaning tissue sites can be very beneficial for the growth of new tissue. For example, a wound or cavity can be flushed with a liquid solution for therapeutic purposes. These clinical procedures are generally referred to as "irrigation" and "lavage," respectively. "Instillation" is another clinical procedure that generally refers to the process of slowly introducing a fluid into a tissue site and leaving the fluid in place for a defined period of time before removing the fluid. For example, to further promote wound healing by releasing soluble contaminants in the wound bed and removing infectious agents, instillation of a topical treatment solution onto the wound bed can be combined with negative pressure therapy. As a result, the soluble bacterial load can be reduced, contaminants can be removed, and the wound can be cleaned.

[0005] The clinical benefits of negative pressure therapy and / or instillation therapy are widely known, but improvements to therapy systems, components, and processes can provide benefits to healthcare providers and patients. SUMMARY OF THE INVENTION

[0006] The appended claims describe novel and useful systems, devices, and methods for determining an optimal instillation volume in a negative pressure environment. Exemplary embodiments are also provided to enable one of ordinary skill in the art to make and use the claimed subject matter.

[0007] For example, in some embodiments, a system for treating a tissue site is described. The system includes an infusion source configured to provide an infusion solution to the tissue site, and a negative pressure source configured to draw fluid from the tissue site to generate a negative pressure at the tissue site. The system also includes a controller communicatively coupled to the infusion source and the negative pressure source. The controller is configured to operate the infusion source and to operate the negative pressure source. The system also includes a sensor communicatively coupled to the controller and operably coupled to the infusion source and the negative pressure source. The sensor is configured to generate a signal indicative of the amount of fluid delivered to the tissue site and the amount of fluid recovered from the tissue site.

[0008] More generally, a system for treating a tissue site is described. The system can include a controller communicatively coupled to an infusion source and a negative pressure source. The controller can be configured to operate the infusion source to provide infusion therapy and to operate the negative pressure source to provide negative pressure therapy. The system can include an infusion sensor communicatively coupled to the controller and configured to generate a signal indicative of an instill volume (IV). The system can also include a recovered volume (RV) sensor communicatively coupled to the controller and configured to generate a signal indicative of a recovered volume (RV).

[0009] A method for determining saturation of a tissue site is also described herein. Some exemplary embodiments provide receiving, using a controller, a signal indicative of an instill volume (IV), receiving, using the controller, a signal indicative of a recovered volume (RV), comparing, using the controller, the instill volume (IV) to the recovered volume (RV), and determining, in response to comparing the instill volume (IV) to the recovered volume (RV), a saturation state of the tissue site.

[0010] The objects, advantages, and preferred embodiments of the claimed subject matter can best be understood by referring to the accompanying drawings in conjunction with the following detailed description of the exemplary embodiments for making and using the invention.

Brief Description of the Drawings

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Modes for Carrying Out the Invention

[0012] The following description of the exemplary embodiments provides information that enables those skilled in the art to make and use the subject matter recited in the appended claims, but certain details that are well known in the art may be omitted. Accordingly, the following detailed description is to be construed as illustrative and not restrictive.

[0013] Exemplary embodiments may also be described herein with reference to spatial relationships between various elements or spatial orientations of various elements shown in the accompanying drawings. Generally, such relationships or orientations assume a reference system that coincides with or is related to a patient in a position for treatment. However, as should be appreciated by those skilled in the art, this reference system is not a strict definition and is merely a means for explanation.

[0014] 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 surface wounds, bone tissue, adipose tissue, muscle tissue, nerve tissue, dermal tissue, vascular tissue, connective tissue, cartilage, tendon, or ligament. The term "tissue site" may also refer to any area of tissue where, although there may not necessarily be a wound or defect, it may be desirable to add or promote the growth of additional tissue instead. For example, negative pressure can be applied to the tissue site to grow additional tissue that can be harvested and transplanted. A surface wound, as used herein, is a wound on the outer surface of the body that is exposed, such as an injury or damage to the epidermis, dermis, and / or subcutaneous layer. A surface wound can include, for example, an ulcer or a closed incision. A surface wound, as used herein, does not include internal wounds within the abdominal cavity. Examples of wounds can include chronic wounds, acute wounds, traumatic wounds, subacute wounds, and laceration wounds, intermediate layer burns, ulcers (such as diabetic ulcers, pressure ulcers, or venous insufficiency ulcers), skin flaps, and grafts.

[0015] FIG. 1 is a simplified functional block diagram of an exemplary embodiment of a therapy system 100 that is capable of providing negative pressure therapy in conjunction with the infusion of a topical treatment solution to a tissue site according to the present specification. The therapy system 100 can include, for example, a negative pressure source or supply such as a negative pressure source 102, a dressing 104, a fluid container such as a canister 106, and an adjuster or controller such as a controller 108. Further, the therapy system 100 can include sensors for measuring operating parameters and providing feedback signals indicative of those operating parameters to the controller 108. As shown in FIG. 1, for example, the therapy system 100 can include a pressure sensor 110, an electrical sensor 112, or both, coupled to the controller 108. As shown in the embodiment of FIG. 1, the dressing 104 can include, or can consist essentially of, a tissue interface 114, a cover 116, or both, in some embodiments.

[0016] The therapy system 100 can also include an infusion solution source. For example, as shown in the exemplary embodiment of FIG. 1, a fluid source 118 can be fluidly coupled to the dressing 104. The fluid source 118 can be fluidly coupled to a positive pressure source such as a positive pressure source 120, a negative pressure source such as a negative pressure source 102, or both, in some embodiments. An adjuster such as an infusion regulator 122 can also be fluidly coupled to the fluid source 118 and the dressing 104 to ensure proper administration of an infusion solution (e.g., saline or sterile water) to the tissue site. For example, the infusion regulator 122 can include a piston that can be pneumatically actuated by the negative pressure source 102 to draw the infusion solution from the fluid source 118 during a negative pressure interval and inject the solution into the dressing during a venting interval. Further, or alternatively, the controller 108 can be coupled to the negative pressure source 102, the positive pressure source 120, or both, to control the administration of the infusion solution to the tissue site. In some embodiments, the infusion regulator 122 can also be fluidly coupled to the negative pressure source 102 via the dressing 104, as shown in the embodiment of FIG. 1.

[0017] Some components of the therapy system 100 can be housed within or used in conjunction with other components, such as sensors, processing units, alarm indicators, memories, databases, software, display devices, or user interfaces, that further facilitate the therapy. For example, in some embodiments, the negative pressure source 102 can be combined into the therapy unit 124 along with the fluid source 118, the controller 108, and other components.

[0018] Generally, the components of the therapy system 100 can be coupled directly or indirectly. For example, the negative pressure source 102 can be directly coupled to the canister 106 and indirectly coupled to the dressing material 104 via the canister 106. Coupling can, in some contexts, include fluid coupling, mechanical coupling, thermal coupling, electrical coupling, or chemical coupling (such as chemical bonding), or some combination of couplings. For example, the negative pressure source 102 can be electrically coupled to the controller 108 and fluidly coupled to one or more distribution components to provide a fluid path to the tissue site. In some embodiments, components can also be coupled by being physically proximate, integrated into a single structure, or formed from the same piece of material. For example, the tissue interface 114 and the cover 116 can be separate layers positioned adjacent to each other and, in some embodiments, can also be joined together.

[0019] The dispensing component is preferably removable and can be disposable, reusable, or recyclable. The dressing material 104 and the canister 106 are illustrative of the dispensing component. The fluid conductor is another illustrative embodiment of the dispensing component. As used in this context, a "fluid conductor" broadly includes tubes, pipes, hoses, conduits, or other structures having one or more lumens or open paths adapted to convey fluid between two ends. Typically, a tube is an elongated cylindrical structure having some flexibility, but the geometry and rigidity can vary. Additionally, some fluid conductors can be molded within or otherwise integrated and combined with other components. The dispensing component may also include or constitute an interface or fluid port to facilitate connecting and disconnecting other components. In some embodiments, for example, a dressing material interface can facilitate connecting a fluid conductor to the dressing material 104.

[0020] The negative pressure supply unit, such as the negative pressure source 102, can be, for example, a reservoir of negative pressure air, or can be a manual or electric device such as a vacuum pump, a suction pump, a wall suction port available in many healthcare facilities, or a micropump. "Negative pressure" generally refers to a pressure lower than the local ambient pressure, such as the ambient pressure in the local environment outside the sealed treatment environment. In many cases, the local ambient pressure can also be the atmospheric pressure at the tissue site. Alternatively, this pressure can be lower than the hydrostatic pressure associated with the tissue at the tissue site. Unless otherwise indicated, the pressure values described in this specification are gauge pressures. References to an increase in negative pressure typically refer to a decrease in absolute pressure, while a decrease in negative pressure typically refers to an increase in absolute pressure. The amount and nature of the negative pressure applied to the tissue site can vary according to treatment requirements, but the pressure is generally a low vacuum, generally referred to as a rough vacuum, of -5 mmHg (-667 Pa) to -500 mmHg (-66.7 kPa). A typical treatment range is -50 mmHg (-6.7 kPa) to -300 mmHg (-39.9 kPa).

[0021] The canister 106 represents a container, canister, pouch, or other storage component that can be used to manage exudate and other fluids withdrawn from the tissue site. In many environments, a rigid container may be preferred or required to collect, store, and discard the fluid. In other environments, the fluid can be appropriately discarded without storage in a rigid container, and a reusable container can be used to reduce the waste and costs associated with negative pressure therapy.

[0022] A controller, such as controller 108, can be a microprocessor or computer programmed to operate one or more components of the therapy system 100, such as negative pressure source 102. In some embodiments, for example, controller 108 can be a microcontroller, which generally comprises an integrated circuit including a processor core and memory programmed to directly or indirectly control one or more operating parameters of therapy system 100. Examples of operating parameters can include, for example, the power applied to negative pressure source 102, the pressure generated by negative pressure source 102, or the pressure distributed to tissue interface 114. Controller 108 is also preferably configured to receive one or more input signals, such as feedback signals, and is programmed to modify one or more operating parameters based on those input signals.

[0023] Sensors such as pressure sensor 110 or electrical sensor 112 are known in the art as any device operable to detect or measure a physical phenomenon or property and generally provide a signal indicative of the detected or measured phenomenon or property. For example, pressure sensor 110 and electrical sensor 112 can be configured to measure one or more operating parameters of therapy system 100. In some embodiments, pressure sensor 110 can be a transducer configured to measure the pressure within the pneumatic path and convert the measurement into a signal indicative of the measured pressure. In some embodiments, pressure sensor 110 can be a piezoresistive strain gauge. Electrical sensor 112 can optionally measure operating parameters of negative pressure source 102, such as voltage or current, in some embodiments. Preferably, the signals from pressure sensor 110 and electrical sensor 112 are suitable as input signals to controller 108, although some signal conditioning may be appropriate in some cases. For example, the signals may need to be filtered or amplified before being made processable by controller 108. Typically, the signals are electrical signals, although they can also be represented in other forms such as optical signals.

[0024] Tissue interface 114 can generally be adapted to contact the tissue site partially or fully. Tissue interface 114 can take many forms and can have many sizes, shapes, or thicknesses depending on various factors such as the type of treatment being performed or the nature and size of the tissue site. For example, the size and shape of tissue interface 114 can be adapted to the outer profile of a deeply irregularly shaped tissue site.

[0025] In some embodiments, the tissue interface 114 can include or consist essentially of a manifold. A manifold in this context can include or consist essentially of means for collecting or distributing fluid across the tissue interface 114 under pressure. For example, the manifold can be adapted to receive a negative pressure from a source and distribute the negative pressure through a plurality of apertures across the tissue interface 114, which can have the effect of collecting fluid across the tissue site and drawing that fluid toward the source. In some embodiments, the fluid path can be reversed or a secondary fluid path can be provided to facilitate delivery of fluid, such as fluid from an infusion solution source, across the tissue site.

[0026] In some exemplary embodiments, the manifold can comprise a plurality of pathways that can be interconnected to improve fluid distribution or collection. In some exemplary embodiments, the manifold can include or consist essentially of a porous material having interconnected fluid pathways. Examples of suitable porous materials that can be adapted to form interconnected fluid pathways (e.g., channels) include cellular foams, such as open-cell foams including reticulated foams, aggregates of porous tissue, and other porous materials such as gauze or felt-like mats that generally include pores, edges, and / or walls. Liquids, gels, and other foams can also include or be hardened to include openings and fluid pathways. In some embodiments, the manifold can additionally or alternatively comprise protrusions that form interconnected fluid pathways. For example, the manifold can be molded to provide surface protrusions that define interconnected fluid pathways.

[0027] In some embodiments, the tissue interface 114 can include, or can consist essentially of, an open-cell foam having a pore size and porosity that can vary according to the requirements of the prescribed therapy. For example, an open-cell foam having a porosity of at least 90% may be suitable for many therapy applications, and a foam having an average pore size in the range of 400 to 600 microns (40 to 50 pores per inch) may be particularly suitable for some types of therapy. The tensile strength of the tissue interface 114 can also vary according to the requirements of the prescribed therapy. For example, the tensile strength of the foam can be increased for the infusion of topical therapy solutions. The 25% compression load deflection of the tissue interface 114 can be at least 0.35 pounds per square inch, and the 65% compression load deflection can be at least 0.43 pounds per square inch. In some embodiments, the tensile strength of the tissue interface 114 can be at least 10 pounds per square inch. The tissue interface 114 can have a tear strength of at least 2.5 pounds per inch. In some embodiments, the tissue interface can be a foam composed of a polyol such as polyester or polyether, an isocyanate such as toluene diisocyanate, and a polymerization regulator such as an amine and tin compound. In some examples, the tissue interface 114 can be an open-cell polyurethane foam such as that found in both the GRANUFOAM™ dressing or the V.A.C. VERAFLO™ dressing, both available from Kinetic Concepts, Inc (San Antonio, Texas).

[0028] The thickness of the tissue interface 114 can also vary according to the requirements of the prescribed therapy. For example, the thickness of the tissue interface can be decreased to reduce tension on the surrounding tissue. The thickness of the tissue interface 114 can also affect the conformity of the tissue interface 114. In some embodiments, a thickness in the range of about 5 millimeters to 10 millimeters may be suitable.

[0029] The tissue interface 114 can be either hydrophobic or hydrophilic. In one embodiment where the tissue interface 114 can be hydrophilic, the tissue interface 114 can also draw fluid from the tissue site and release it while continuing to distribute negative pressure to the tissue site. The drawing-up characteristics of the tissue interface 114 can draw fluid into it from the tissue site so as to release it by capillary flow or other drawing-up mechanisms. An example of a suitable hydrophilic material is a continuous bubble foam of polyvinyl alcohol such as the V.A.C. WHITEFOAM (trademark) dressing material available from Kinetic Concepts, Inc. (San Antonio, Texas). Other hydrophilic foams can include those made from polyethers. Other foams that can exhibit hydrophilic properties can include hydrophobic foams that are treated or coated to provide hydrophilicity.

[0030] In some embodiments, the tissue interface 114 can be constructed from a bioabsorbable material. Suitable bioabsorbable materials can include, but are not limited to, a polymer blend of polylactic acid (PLA) and polyglycolic acid (PGA). This polymer blend can also include, but is not limited to, polycarbonate, polyfumarate, and caprolactone. The tissue interface 114 can further serve as a scaffold for new cell growth, or cell growth can be promoted by using a scaffold material in combination with the tissue interface 114. A scaffold is generally a substance or structure used to enhance or promote cell growth or tissue formation, such as a three-dimensional porous structure that provides a template for cell growth. Exemplary examples of scaffold materials can include calcium phosphate, collagen, PLA / PGA, coral hydroxyapatite, carbonate, or a processed allograft material.

[0031] In some embodiments, the cover 116 can provide protection from bacterial barriers and physical trauma. The cover 116 can also be constructed from materials that can reduce evaporative loss and provide a fluid seal between two components or between two environments such as between the treatment environment and the local external environment. The cover 116 can be, for example, an elastic film or membrane that can provide a sufficient seal to maintain negative pressure at the tissue site against a given negative pressure source. The cover 116 can have a high moisture-vapor transmission rate (MVTR) in some applications. For example, the MVTR can be at least about 300 g / m per 24 hours in some embodiments. 2 In some exemplary embodiments, the cover 116 can be a polymeric drape such as a polyurethane film that is permeable to water vapor but impermeable to liquids. Such drapes typically have a thickness in the range of about 25 microns to about 50 microns. With respect to the permeable material, the permeability should generally be low enough to be able to maintain the desired negative pressure.

[0032] The cover 116 can be, for example, hydrophilic polyurethane; a cellulose-based material; hydrophilic polyamide; polyvinyl alcohol; polyvinyl pyrrolidone; hydrophilic acrylic; hydrophilic silicone elastomer; for example, about 14400 g / m 2 / The INSPIRE 2301 material manufactured by Coveris Advanced Coatings (Wrexham, United Kingdom) with a MVTR (inverted cup technology) of 24 hours and a thickness of approximately 30 microns; an uncoated thin polymer drape; natural rubber; polyisoprene; styrene-butadiene rubber; chloroprene rubber; polybutadiene; nitrile rubber; butyl rubber; ethylene-propylene rubber; ethylene-propylene-diene monomer; chlorosulfonated polyethylene; polysulfide rubber; polyurethane (PU); EVA film; copolyester; silicone; silicone drape; 3M Tegaderm® drape; polyurethane (PU) drape such as those available from Avery Dennison Corporation (Glendale, California); polyether block polyamide copolymer (PEBAX) such as those manufactured by Arkema (France); INSPIRE 2327; or one or more of other suitable materials may be included.

[0033] An attachment device can be used to attach the cover 116 to an attachment surface such as an intact epidermis, gasket, or another cover. The attachment device can take many forms. For example, the attachment device can be a medically acceptable pressure-sensitive adhesive configured to bond the cover 116 to the epidermis around the tissue site. In some embodiments, for example, part or all of the cover 116 can be coated with an adhesive such as an acrylic adhesive that can have a coating weight of about 25 grams per square meter (g.s.m.) to about 65 g.s.m. In some embodiments, a thicker adhesive, or a combination of adhesives, can be applied to improve the seal and reduce leakage. Other exemplary embodiments of the attachment device can include double-sided tape, paste, hydrocolloid, hydrogel, silicone gel, or organogel.

[0034] The fluid source 118 may also represent a container, canister, pouch, bag, or other storage component capable of providing a solution for infusion therapy. The composition of the solution can vary according to the prescribed therapy, but examples of solutions that may be suitable for some prescriptions include hypochlorite-based solutions, silver nitrate (0.5%), sulfur-based solutions, biguanides, cationic solutions, and isotonic solutions.

[0035] Hydrodynamics that use a negative pressure source to reduce pressure in another component or location, such as within a sealed treatment environment, can be mathematically complex. However, the basic principles of hydrodynamics applicable to negative pressure therapy and infusion are generally well known to those skilled in the art, and the process of reducing pressure can be illustratively described herein, for example, as "delivering," "distributing," or "generating" negative pressure.

[0036] Generally, exudate and other fluids flow along a fluid path towards a lower pressure. Therefore, the term "downstream" typically refers to a position within the fluid path that is relatively closer to the negative pressure source or farther away from the positive pressure source. Conversely, the term "upstream" refers to a position that is relatively farther away from the negative pressure source or closer to the positive pressure source. Similarly, in such a reference system, it may be convenient to describe certain features from the perspective of the "inlet" or "outlet" of the fluid. This orientation is generally assumed for the purpose of describing the various features and components herein. However, the fluid path can also be reversed in some applications (such as by replacing the negative pressure source with a positive pressure source), and this descriptive convention should not be construed as a limiting convention.

[0037] In a sealed treatment environment, the negative pressure applied across the tissue site via the tissue interface 114 can induce macro and micro strains at that tissue site. The negative pressure can also remove exudate and other fluids from the tissue site, and these exudate and other fluids can be collected within the canister 106.

[0038] In some embodiments, the controller 108 can receive and process data from one or more sensors, such as the pressure sensor 110 and the electrical sensor 112. The controller 108 can also control the operation of one or more components of the therapy system 100 to manage the pressure delivered to the tissue interface 114. In some embodiments, the controller 108 can include an input for receiving a desired target pressure and can be programmed to process data related to the setting and input of that target pressure that is to be applied to the tissue interface 114. In some exemplary embodiments, the target pressure can be a fixed pressure value that is set by an operator as the desired target negative pressure for therapy at the tissue site and provided as an input to the controller 108. The target pressure can vary depending on the type of tissue forming the tissue site, the type of injury or wound (if any), the patient's medical condition, and the preference of the attending physician. After selecting the desired target pressure, the controller 108 can operate the negative pressure source 102 in one or more control modes based on that target pressure and can receive feedback from one or more sensors to maintain the target pressure at the tissue interface 114.

[0039] In some embodiments, the controller 108 can have a continuous pressure mode in which the negative pressure source 102 is operated to provide a constant target negative pressure over the duration of the treatment or until manually deactivated. Further or alternatively, the controller can have an intermittent pressure mode. The controller 108 can operate the negative pressure source 102 to cycle between the target pressure and atmospheric pressure. For example, the target pressure can be set to a value of 135 mmHg for a specified period (e.g., 5 minutes) and then deactivated for a specified period (e.g., 2 minutes). By operating the negative pressure source 102, this cycle can be repeated, thereby forming a square wave pattern between the target pressure and atmospheric pressure.

[0040] In some exemplary embodiments, the increase in negative pressure from ambient pressure to target pressure may not be instantaneous. For example, the negative pressure source 102 and the dressing 104 may have an initial rise time. The initial rise time may vary depending on the type of dressing and treatment device being used. For example, the initial rise time for one therapy system can range from about 20 to 30 mmHg / second, and for another therapy system, it can range from about 5 to 10 mmHg / second. When the therapy system 100 is operating in intermittent mode, the repeated rise time can be a value substantially equal to the initial rise time.

[0041] The target pressure can vary over time in dynamic pressure mode. For example, the target pressure can vary in the form of a triangular wave that varies between a negative pressure of 50 - 135 mmHg, having a rise time set at a rate of +25 mmHg / minute and a fall time set at a rate of -25 mmHg / minute. In other embodiments of the therapy system 100, the triangular wave can vary between a negative pressure of 25 - 135 mmHg, having a rise time set at a rate of +30 mmHg / minute and a fall time set at -30 mmHg / minute.

[0042] In some embodiments, the controller 108 can control or determine a variable target pressure in dynamic pressure mode, and the variable target pressure can vary between a maximum pressure value and a minimum pressure value that can be set as an input defined by the operator as a desired range of negative pressure. The variable target pressure can also be processed and controlled by the controller 108, and the controller 108 can vary the target pressure according to a predetermined waveform such as a triangular wave, sine wave, or sawtooth wave. In some embodiments, the waveform can be set by the operator as a predetermined negative pressure or time-varying negative pressure desired for the treatment.

[0043] In some embodiments, the controller 108 can receive and process data, such as data related to the infusion solution provided to the tissue interface 114. Such data can include the type of infusion solution prescribed by a clinician, the volume of fluid or solution to be infused into the tissue site (the "fill volume"), and the amount of time (the "dwell time") defined to leave the solution at the tissue site before applying negative pressure to the tissue site. The fill volume can be, for example, 10 to 500 mL, and the dwell time can be 1 second to 30 minutes. The controller 108 can also control the operation of one or more components of the therapy system 100 for injecting the solution. For example, the controller 108 can manage the fluid dispensed from the solution source 118 to the tissue interface 114. In some embodiments, fluid can be injected into the tissue site by applying negative pressure from the negative pressure source 102 to reduce the pressure at the tissue site and draw the solution into the tissue interface 114. In some embodiments, solution can be injected into the tissue site by applying positive pressure from the positive pressure source 120 to move the solution from the solution source 118 to the tissue interface 114. Additionally or alternatively, the solution source 118 can be raised to a sufficient height to enable the solution to be moved into the tissue interface 114 by gravity.

[0044] The controller 108 can also control the fluid dynamics of the infusion by providing a continuous flow or an intermittent flow of the solution. A negative pressure can be applied to provide either a continuous flow or an intermittent flow of the solution. The application of the negative pressure can be implemented to provide a continuous pressure operation mode for achieving a continuous flow rate of the infusion solution through the tissue interface 114, or can be implemented to provide a dynamic pressure operation mode for varying the flow rate of the infusion solution through the tissue interface 114. Alternatively, the application of the negative pressure can be implemented to provide an intermittent operation mode that allows the infusion solution to dwell at the tissue interface 114. In the intermittent mode, for example, a specific fill volume and dwell time can be provided depending on the type of tissue site being treated and the type of dressing material being utilized. A negative pressure treatment can be applied after or during the infusion of the solution. The controller 108 can be utilized to select the operation mode and duration of the negative pressure treatment before initiating another infusion cycle by injecting more solution.

[0045] Some therapy systems that provide negative pressure therapy and infusion therapy may encounter difficulties in determining a clinically appropriate infusion volume. Some clinicians may not be familiar with the technical aspects of infusion by negative pressure closure therapy and may be unable to determine an appropriate infusion volume for an individual tissue site. Other clinicians may have their view of the tissue site blocked by an opaque dressing material or wound filler. Still other clinicians may face other obstacles to the proper administration of infusion by negative pressure closure therapy. The inability to determine an appropriate infusion volume for a tissue site can lead to overfilling of the tissue site. Overfilling of a tissue site or dressing material may refer to the infusion of a volume of fluid into the tissue site that is greater than the volume of the tissue site itself. Overfilling may allow fluid to leak from the dressing material by increasing the pressure at the tissue site and damaging the dressing material. Fluid leakage caused by overfilling may also cause failure of the negative pressure therapy because the dressing material covering the tissue site can no longer maintain a seal during the negative pressure therapy interval.

[0046] The inability to provide an appropriate volume of infusion solution can also lead to underfilling of the tissue site. Underfilling may refer to the infusion of an insufficient volume of fluid into the tissue site to adequately saturate the tissue site. Underfilling of the infusion solution may reduce the benefits that a patient can enjoy from the infusion therapy by reducing the effectiveness of the infusion therapy. Preventing overfilling and underfilling depends on an appropriate estimation of the volume of the tissue site. Appropriate estimation of the size and volume of a tissue site can, in some cases, be a time-consuming process. Unfortunately, the time demands placed on clinicians with respect to patient care may exceed the number of hours in a day. As a result, excessive time demands may lead to a decrease in the adoption of infusion by negative pressure closure therapy because clinicians may avoid the adoption or use of infusion by negative pressure closure therapy. Avoiding the adoption of infusion by negative pressure closure therapy may prevent more people from enjoying the benefits of infusion therapy by negative pressure closure therapy.

[0047] These limitations and others can be addressed by therapy system 100, which can provide a system and process for determining the optimal infusion volume for an individual tissue site. Determining the optimal infusion volume for an individual tissue site reduces the risk of overfilling or underfilling the tissue site by enabling the therapy system 100 to optimize the delivery of the infusion solution. Determining the optimal infusion volume via the use of system 100 can also reduce the clinician's time requirements and improve the ease of use of systems that provide infusion and negative pressure wound therapy, leading to improved patient outcomes and broader adoption of beneficial therapies.

[0048] For example, therapy system 100 can provide intervals of infusion, solution dwell, and controlled negative pressure. In some embodiments, the controller 108 of therapy system 100 can be equipped with infusion volume determination and control logic, as well as a method for determining the volume infused. Therapy system 100 further includes an apparatus for infusing a variable volume of solution, a negative pressure delivery system, and a negative pressure collection system. In some embodiments, the negative pressure collection system can be equipped with a method for determining the volume of fluid collected from the tissue site. In some embodiments, system 100 determines the optimal infusion volume. The optimal infusion volume can be the volume that achieves saturation of the dressing 104. Saturation occurs when the infusion cycle and the negative pressure cycle are in equilibrium, with the negative pressure cycle removing the same volume of liquid that the infusion cycle has infused. Equilibrium can also be represented as the point in time when the dressing's retained infusion volume is maximized.

[0049] In some embodiments, the controller 108 can be communicatively coupled to the canister 106. The canister 106 can include a sensor 126 or other device configured to determine the volume of fluid received from the tissue site. For example, the controller 108 and the sensor 126 can determine the volume of fluid received from the dressing 104 via rotational speed measurement, change in weight, or other suitable methods. In some embodiments, the sensor 126 can be a strain gauge. When fluid enters the canister 106, the weight of the fluid added to the canister 106 can increase the force on the sensor 126. The signal generated by the sensor 126 in response to that force can be received by the controller 108 and interpreted as the weight of the fluid and the corresponding volume. In some embodiments, the controller 108 can store a median value of the fluid weight to determine an additional amount of fluid to be added to the canister 106 in subsequent negative pressure therapy cycles.

[0050] In other embodiments, sensor 126 can be a tachometer such as a Hall effect sensor. For example, sensor 126 can be disposed at the fluid inlet of canister 106. A signal representing the rotational speed can be generated in sensor 126 by the fluid flowing past sensor 126 during a negative pressure therapy cycle. The signal can be received by controller 108 and interpreted as a corresponding volume. In still other embodiments, sensor 126 can be a glass level gauge or a float. Sensor 126 can also be one type of hydrostatic device such as a displacer, a bubbler, or a differential pressure transmitter. Sensor 126 can also be a load cell, a magnetic level gauge, or a capacitance transmitter. In still other embodiments, sensor 126 can be a magnetostrictive level transmitter, an ultrasonic level transmitter, a laser level transmitter, or even a radar level transmitter. Sensor 126 can also be other types of level sensors such as a resistance chain, a gamma ray, or a microwave sensor. In an exemplary embodiment, sensor 126 can be an optical liquid level sensor such as one manufactured by Strain Measurement Devices, or an optical fiber water sensor such as the 44.1WS-B / K1 or 44.2WS-G manufactured by Wolf GmbH. Other suitable sensors can be those manufactured by SEMRAD Process Control and Monitoring such as those manufactured for liquid level transmitters and indicators, and sensors manufactured for wastewater level monitoring such as the dBi HART ultrasonic intelligent transducer manufactured by Pulsar Measurement can represent suitable types of sensors.

[0051] Preferably, by communicably coupling sensor 126 to controller 108, controller 108 may be able to distinguish the volume of fluid received in each cycle of negative pressure therapy from the volume of fluid previously contained within canister 106. In some embodiments, sensor 126 may be a separate flow meter fluidly coupled between canister 106 and dressing 104 and communicably coupled to controller 108 to determine the volume of fluid flowing into canister 106 in each negative pressure therapy cycle. In some embodiments, controller 108 may be configured to adjust the negative pressure therapy in response to a signal received from sensor 126.

[0052] In some embodiments, controller 108 may be communicably coupled to fluid source 118 and / or regulator 122. Fluid source 118 and / or regulator 122 may include a sensor 128 or other device configured to determine the volume of fluid delivered to dressing 104. For example, controller 108 and sensor 128 may be able to determine the volume of fluid delivered to dressing 104 via rotational speed measurement, change in weight, or other suitable method. In some embodiments, sensor 128 may be a strain gauge. As the fluid exits fluid source 118, the weight of the fluid can reduce the force on sensor 128. A signal generated by sensor 128 in response to the force can be received by controller 108 and interpreted as the weight of the fluid and the corresponding delivered volume. In some embodiments, controller 108 may be able to store an intermediate value of the weight of the fluid to determine an additional amount of fluid removed from fluid source 118 in subsequent infusion cycles.

[0053] In other embodiments, sensor 128 can be a tachometer such as a Hall effect sensor. For example, sensor 128 can be disposed at the fluid outlet of regulator 122. A signal representing the rotational speed can be generated in sensor 128 by the fluid flowing past sensor 128 during an infusion therapy cycle. That signal can be received by controller 108 and interpreted as a corresponding volume.

[0054] Preferably, by communicably coupling sensor 128 to controller 108, controller 108 may be able to distinguish the volume of fluid delivered in each cycle of the infusion therapy from the volume of fluid previously delivered via regulator 122. In some embodiments, sensor 128 can also be a separate flow meter that is fluid-coupled between regulator 122 and dressing 104 and communicably coupled to controller 108 to determine the volume of fluid flowing into dressing 104 in each infusion therapy cycle. In some embodiments, controller 108 can be configured to adjust the infusion therapy in response to the signal received from sensor 128.

[0055] Figure 2 is a flowchart showing the operational steps of process 200 for determining an initial tissue site volume for the selection of a dressing material for use with a tissue site. In some embodiments, a clinician can perform the steps associated with process 200. In other embodiments, controller 108 of system 100 can perform the steps associated with process 200. This process begins at block 202 where the size of the tissue site is estimated. In some embodiments, a clinician can visually estimate the size of the tissue site. For example, the clinician can visually observe the tissue site to make an initial estimate of its size. In some embodiments, the clinician can visually estimate the tissue site as small, medium, large, or extra-large. In some embodiments, the presence of similarly named pre-packaged dressing materials can assist the clinician. The clinician can determine whether the pre-packaged dressing material is of an appropriate size by visually comparing the pre-packaged dressing material to the tissue site.

[0056] The process continues to block 204 where process 200 determines whether the tissue site is a small tissue site. For example, the clinician can determine whether a small pre-packaged dressing material can fill the tissue site by comparing the small pre-packaged dressing material to the tissue site. If the tissue site is a small tissue site, the process proceeds along the "yes" path to block 206 where process 200 applies a small dressing material to the tissue site. For example, the clinician can place dressing material 104 having a small volume on the tissue site. Process 200 continues to block 218 where an optimization routine is initiated. For example, the clinician can provide information that the small dressing material is positioned on the tissue site to controller 108 via use of the user interface, and controller 108 can initiate the optimization routine.

[0057] In block 204, if the tissue site is not a small tissue site, the process proceeds along the "no" path to block 208 where process 200 determines whether the tissue site is a medium-sized tissue site. For example, a clinician can determine whether a medium-sized pre-packaged dressing can fill the tissue site by comparing the medium-sized pre-packaged dressing to the tissue site. If the tissue site is a medium-sized tissue site, the process proceeds along the "yes" path to block 210 where process 200 uses a medium-sized dressing with the tissue site. For example, a clinician can place a dressing 104 having a medium volume at the tissue site. Process 200 continues to block 218 where an optimization routine is initiated. For example, a clinician can provide information that the medium-sized dressing is positioned at the tissue site to controller 108 via use of the user interface, and controller 108 initiates the optimization routine.

[0058] In block 208, if the tissue site is not a medium tissue site, the process proceeds along the "no" path to block 212 where process 200 determines whether the tissue site is a large tissue site. For example, a clinician can determine whether a large pre-packaged dressing can fill the tissue site by comparing the large pre-packaged dressing to the tissue site. If the tissue site is a large tissue site, the process proceeds along the "yes" path to block 214 where process 200 uses a large dressing with the tissue site. For example, a clinician can place a dressing 104 with a large volume at the tissue site. Process 200 continues to block 218 where an optimization routine is initiated. For example, a clinician can provide information that a large dressing is positioned at the tissue site to controller 108 via use of a user interface, and controller 108 initiates the optimization routine. In block 212, if the tissue site is not a large tissue site, the process proceeds along the "no" path to block 216 where process 200 uses an extra-large dressing with the tissue site. For example, a clinician can place a dressing 104 with an extra-large volume at the tissue site. Process 200 continues to block 218 where an optimization routine is initiated. For example, a clinician can provide information that an extra-large dressing is positioned at the tissue site to controller 108 via use of a user interface, and controller 108 initiates the optimization routine.

[0059] FIG. 3 is a flowchart showing the operational steps of an optimization routine or process 300 for determining an optimal fluid infusion volume for a tissue site, which is executed by the system 100 of FIG. 1. In some embodiments, process 300 can use a uniform process, a uniform infusion profile, or a uniform optimization routine. A uniform infusion profile may refer to the delivery of a periodic fluid of the same volume in each infusion cycle. Process 300 begins at block 302 where the system 100 receives an infusion volume (IV). In some embodiments, the controller 108 can receive an input from the process 200 of FIG. 2 for setting an initial infusion volume based on a visual estimate of the tissue site size. For example, a clinician can input that a small pre-packaged dressing material was used, and the controller 108 can set the infusion volume (IV) to the expected volume associated with the use of the small dressing material. Similarly, if a medium, large, or extra-large pre-packaged dressing material was used, the controller 108 can set the infusion volume (IV) to the expected volume associated with the use of the medium, large, or extra-large pre-packaged dressing material.

[0060] This process continues to block 304 where an infusion volume (IV) is infused into the tissue site. For example, the controller 108 can operate the positive pressure source 120 and the regulator 122 to infuse the infusion volume (IV) into the tissue site. In some embodiments, a dwell operation can be performed after the drip infusion of the infusion volume (IV) into the tissue site. The dwell operation can be an operation that allows the infused volume to remain within the dressing material for a predetermined period. In other embodiments, the dwell operation is not performed. This process continues to block 306 where a value associated with the infusion volume (IV) is stored. For example, the sensor 128 associated with the regulator 122 and / or the fluid source 118 can provide a signal indicating a value associated with the infusion volume (IV), which is the volume of fluid infused into the tissue site, to the controller 108. The controller 108 can store the volume of fluid infused into the tissue site, i.e., the value associated with the infusion volume (IV).

[0061] Process 300 continues to block 308 where fluid is drawn from the tissue site and a volume of fluid is recovered in a negative pressure therapy cycle. For example, the controller 108 can operate the negative pressure source 102 to draw fluid from the tissue site into the canister 106 through the dressing material 104. In some embodiments, the operation of this negative pressure source 102 can relate to one cycle of negative pressure therapy. This process continues to block 310 where the process 300 measures and stores the volume of fluid associated with the recovered volume (RV), which is the volume of the recovered fluid. For example, the sensor 126 can generate a signal indicating the value of the recovered volume (RV), which is the volume of fluid recovered from the tissue site. The controller 108 can receive and store the recovered volume (RV), which is the value associated with the signal generated by the sensor 126.

[0062] This process follows block 312 where process 300 compares the injection volume (IV) to the recovery volume (RV). For example, the controller 108 can compare the value associated with the injection volume (IV) to the value associated with the recovery volume (RV). In block 314, process 300 determines whether the recovery volume (RV) is greater than the injection volume (IV). For example, the controller 108 compares the value associated with the recovery volume (RV) to the value associated with the injection volume (IV). If the recovery volume (RV) is greater than the injection volume (IV), the process proceeds along the "yes" path to block 316 where process 300 reports an error and process 300 ends. For example, the controller 108 can signal an alarm such as an auditory alarm, a tactile alarm, or a visual alarm.

[0063] In block 314, if the recovered volume (RV) is not greater than the infused volume (IV), process 300 proceeds to decision block 318 where process 300 determines whether the recovered volume (RV) is less than the infused volume (IV). If the recovered volume (RV) is less than the infused volume (IV), process 300 proceeds along the "yes" path to block 304 where process 300 is repeated. If the recovered volume (RV) is not less than the infused volume (IV), process 300 proceeds along the "no" path to block 320 where process 300 reports optimization, followed by block 322. In block 322, process 300 initiates drip infusion by negative pressure closure therapy. For example, controller 108 reports that dressing 104 is at an optimal drip infusion volume using an auditory indicator, a tactile indicator, a visual indicator, etc., and controller 108 initiates drip infusion by negative pressure closure therapy. In some embodiments, controller 108 can track the number and volume of drip infusions during process 300. When controller 108 determines that saturation has been achieved, controller 108 can provide an optimized drip infusion volume for drip infusion by negative pressure therapy. The optimized drip infusion volume can be based in part on the number and size of drip infusions during process 300, and on the estimation of the drip infusion fluid left at the tissue site after each volume of fluid has been infused during process 300. The optimized drip infusion volume can further vary depending on the size of the tissue site, as well as the negative pressure setting and the duration of negative pressure.

[0064] Figure 4 is a combination of a bar graph and a line graph showing the fluid volume according to the operation steps of FIG. 3. In FIG. 4, the y-axis represents the volume of the fluid and the x-axis represents time. In each cycle through process 300, the injection volume (IV) is the same, that is, the volume of fluid delivered to the dressing material 104 is the same. For example, in each injection cycle implemented in block 304 of process 300, system 100 delivers the same volume of fluid. As shown by bar lines 402, 406, 410, 414, and 418, each iteration through process 300 delivers the same volume of fluid, that is, the injection volume (IV) is the same. Similarly, each negative pressure therapy cycle implemented in block 308 of process 300 will have approximately the same length. For example, in each negative pressure therapy cycle of process 300, system 100 will operate the negative pressure source 102 for a period of time of approximately the same length. As shown by bar lines 404, 408, 412, 416, and 420, the negative pressure therapy cycles are of approximately the same length. In each negative pressure therapy cycle, the system will recover different amounts of fluid. When fluid is injected into the tissue site, the tissue interface 114 can absorb a certain amount of fluid. Therefore, the amount of fluid recovered during the negative pressure therapy cycle is the amount of fluid delivered minus the amount of fluid absorbed by the tissue interface 114.

[0065] Line 422 indicates the total volume of fluid retained by the tissue site, such as tissue interface 114, after each negative pressure therapy cycle. The total volume of fluid recovered after each negative pressure therapy cycle will increase until the tissue interface 114 and the tissue site are saturated. Saturation occurs when the negative pressure therapy cycle recovers a volume equal to the volume of fluid injected. In the illustrated embodiment, after the negative pressure therapy cycle indicated by dash line 404, a first volume of fluid 426 is recovered. The first volume of fluid 426 is less than the volume of fluid injected during the injection cycle of dash line 402. The remainder of the total volume of fluid injected during injection cycle 402 is retained in the tissue site by tissue interface 114, as indicated by a first volume of retained fluid 427. After the negative pressure therapy cycle indicated by dash line 408, a second volume of fluid 428 is recovered. The second volume of fluid 428 is more than the first volume of fluid 426 and less than the volume of fluid injected during the injection cycle of dash line 406. The remainder of the volume of fluid injected during injection cycle 406 is retained in the tissue site by tissue interface 114, as indicated by a second volume of retention 429. The second volume of retained fluid 429 is less than the first volume of retained fluid 427. After the negative pressure therapy cycle indicated by dash line 412, a third volume of fluid 430 is recovered. The third volume of fluid 430 is more than the first volume of fluid 426 and the second volume of fluid 428 and less than the volume of fluid injected during injection cycle 410. The remainder of the volume of fluid injected during injection cycle 410 is retained in the tissue site by tissue interface 114, as indicated by a third volume of retention 431. The third volume of retained fluid 431 is less than the first volume of retained fluid 427 and the second volume of retained fluid 431. After the negative pressure therapy cycle indicated by dash line 416, a fourth volume of fluid 432 is recovered. The fourth volume of fluid 430 is more than the first volume of fluid 426, the second volume of fluid 428, and the third volume of fluid 430 and equal to the volume of fluid injected during the injection cycle of dash line 414.The fact that the fluid 432 of the fourth volume is equal to the amount of fluid injected at the stem line 414 indicates that the dressing material 104 and the tissue site have reached saturation and the infusion volume has been optimized. In each subsequent cycle, the volume of fluid recovered, e.g., the fifth volume of fluid 434 recovered during the negative pressure cycle 420, is substantially equal to the volume of fluid injected prior to that negative pressure cycle, e.g., the volume of fluid injected at the stem line 418.

[0066] FIG. 5 is a flowchart showing the operational steps of another optimization routine or process 500 for determining an optimal fluid infusion volume for a tissue site, performed by the system 100 of FIG. 1. In some embodiments, the process 500 can use a bolus-lead reduction process or a bolus-lead reduction infusion profile. The process 500 begins at block 502 where the system 100 receives an initial infusion volume (IIV). In some embodiments, the process 500 receives the initial infusion volume (IIV) in response to the process 200. For example, the controller 108 can receive an input from the process 200 of FIG. 2 for setting the initial infusion volume (IIV) based on a visual estimate of the tissue site size. In some embodiments, a clinician can input that a small pre-packaged dressing material was used, and the controller 108 can set the initial infusion volume (IIV) to the expected volume associated with the use of the small dressing material. Similarly, if a medium, large, or extra-large pre-packaged dressing material was used, the controller 108 can set the initial infusion volume (IIV) to the expected volume associated with the use of the medium, large, or extra-large pre-packaged dressing material. The process 500 is followed by block 504 where the initial infusion volume (IIV) is stored. For example, the controller 108 can store a value associated with the initial infusion volume (IIV).

[0067] In block 506, an initial infusion volume (IIV) is infused into the tissue site. For example, the controller 108 can operate the positive pressure source 120 and the regulator 122 to infuse the initial infusion volume (IIV) into the dressing 104. In some embodiments, a dwell operation can be performed after the infusion of the initial infusion volume (IIV) into the tissue site. In other embodiments, the dwell operation is not performed. The process 500 continues to block 508 where a value associated with the volume of fluid infused into the tissue site is stored. For example, the sensor 128 can provide a signal to the controller 108 indicating a value associated with the infusion volume (IV), which is the volume of fluid infused into the tissue site. The controller 108 can store a value associated with the infusion volume (IV), which is the volume of fluid infused into the tissue site.

[0068] The process 500 continues to block 510 where fluid is drawn from the tissue site in a negative pressure therapy cycle and a volume of fluid (recovery volume (RV)) is recovered. For example, the controller 108 can operate the negative pressure source 102 to draw fluid from the tissue site through the dressing 104 into the canister 106. The process 500 continues to block 512 where the process 500 measures and stores the volume of fluid associated with the recovery volume (RV). For example, the sensor 126 can generate a signal indicating a value of the recovery volume (RV), which is the volume of fluid recovered from the tissue site. The controller 108 can receive and store the value associated with the signal generated by the sensor 126.

[0069] This process continues to block 514 where process 500 compares the injection volume (IV) with the recovery volume (RV). For example, the controller 108 can compare the value associated with the injection volume (IV) with the value associated with the recovery volume (RV). In block 516, process 500 determines whether the recovery volume (RV) is greater than the injection volume (IV). For example, the controller 108 compares the value associated with the recovery volume (RV) with the value associated with the injection volume (IV). If the recovery volume (RV) is greater than the injection volume (IV), the process proceeds along the "yes" path to block 518 where process 500 reports an error and process 500 ends. For example, the controller 108 can signal an alarm such as an audible alarm, a tactile alarm, or a visual alarm.

[0070] In block 516, if the recovery volume (RV) is not greater than the injection volume (IV), the process proceeds along the "no" path to decision block 520 where process 500 determines whether the recovery volume (RV) is less than the injection volume (IV). If the recovery volume (RV) is less than the injection volume (IV), process 500 proceeds along the "yes" path to block 522 where process 500 repeats injecting a volume of fluid by setting the initial injection volume (IIV) to be less than the injection volume (IV) by a predetermined amount. For example, the controller 108 can reduce the initial injection volume (IIV) to be less than the injection volume (IV) by a predetermined amount. In some embodiments, this repetition can be selected in response to the relationship between the volume of fluid injected and the volume of fluid recovered. For example, if the volume of fluid recovered exceeds a threshold percentage of the volume of fluid injected, the system can determine that a fluid bolus has been recovered. In response, the system can increase the reduction amount of subsequent drip infusion volumes. This process continues to block 506 where process 500 is repeated.

[0071] In block 520, if the recovered volume (RV) is not less than the infused volume (IV), the process 500 proceeds along the "no" path to block 524 where the process 500 reports optimization, followed by block 526 where the process 500 initiates drip infusion by negative pressure closure therapy. For example, the controller 108 reports that the dressing material 104 is at the optimal drip infusion volume using an auditory indicator, a tactile indicator, a visual indicator, etc., and the controller 108 initiates drip infusion by negative pressure closure therapy.

[0072] Figure 6 is a combination of a bar graph and a line graph showing the determination of the optimal fluid drip infusion volume according to the operation steps of Figure 5. In Figure 6, the y-axis represents the volume of the fluid, and the x-axis represents time. In each cycle through process 500, a gradually decreasing volume is infused into the tissue site. For example, in each subsequent infusion cycle of process 500, the system 100 delivers a smaller volume of fluid. As shown by bar lines 602, 606, 610, 614, and 616, each iteration through process 500 delivers a smaller volume of fluid, that is, the infused volume (IV) decreases. Each negative pressure therapy cycle will have approximately the same length. For example, in each negative pressure therapy cycle of process 500, the system 100 will operate the negative pressure source 102 for approximately the same length of time. As shown by bar lines 604, 608, 612, 616, and 620, the negative pressure therapy cycles are approximately the same length. In each negative pressure therapy cycle, the system 100 will recover different amounts of fluid. When the fluid is infused into the tissue site, the tissue interface 114 can absorb a certain amount of fluid. Therefore, the amount of fluid recovered during the negative pressure therapy cycle is the amount of fluid delivered minus the amount of fluid absorbed by the tissue interface 114.

[0073] Line 622 indicates the total volume of fluid retained by a tissue site, e.g., tissue interface 114, after each negative pressure therapy cycle. The total volume of fluid retained after each negative pressure therapy cycle will increase until the tissue interface 114 and the tissue site are saturated. Saturation occurs when the negative pressure therapy cycle recovers a volume equal to the volume of fluid injected. In the illustrated embodiment, after the negative pressure therapy cycle indicated by dash line 604, a first volume of fluid 626 is recovered. The first volume of fluid 626 is less than the volume of fluid injected during the injection cycle of dash line 602. The remainder of the total volume of fluid injected during injection cycle 602 is retained in the tissue site by tissue interface 114, as indicated by a first volume of retained fluid 627. As shown in FIG. 6, the first volume of fluid 626 can be considered large, and in response, subsequent injection volumes can be reduced. For example, the volume of fluid injected during the injection cycle of dash line 606 is less than the volume of fluid injected during injection cycle 602. Line 622 indicates that at time point 640, the total volume of fluid retained is substantially equal to the first volume of retained fluid 627.

[0074] After the negative pressure therapy cycle indicated by dash line 608, a second volume of fluid 628 is recovered. The second volume of fluid 628 is also less than the volume of fluid injected during injection cycle 606, however, the second volume of fluid 628 can represent a larger proportion of the volume of fluid injected during injection cycle 606. The remainder of the total volume of fluid injected during injection cycle 606 is retained in the tissue site by tissue interface 114, as indicated by a second volume of retained fluid 629. Line 622 indicates that at time point 642, the total volume of fluid retained is substantially equal to the first volume of retained fluid 627 and the second volume of retained fluid 629.

[0075] After the negative pressure therapy cycle indicated by the rod line 612, a third volume of fluid 630 has been recovered. The third volume of fluid 630 is also, in this case, less than the volume of fluid injected during the infusion cycle 610; however, the third volume of fluid 630 can represent a greater proportion of the volume of fluid injected during the infusion cycle 610. The remainder of the total volume of fluid injected during the infusion cycle 610 is retained at the tissue site by the tissue interface 114, as indicated by the third volume of retained fluid 631. Line 622 indicates that, at time point 644, the total volume of fluid retained is substantially equal to the first volume of retained fluid 627, the second volume of retained fluid 629, and the third volume of retained fluid 631. As represented at time point 644, the fact that line 622 is equal to the amount of fluid injected at rod line 602 indicates that the dressing 104 and the tissue site have reached saturation and that the infusion volume has been optimized. Subsequent infusion cycles 614 and 618, and corresponding negative pressure cycles 616 and 620, are recovering volumes of fluid 632 and fluid 634 that are substantially equal to the volume of fluid injected in the preceding infusion cycle. In response, line 622 remains substantially horizontal, further indicating that the tissue site and the dressing 104 have reached saturation.

[0076] FIG. 7 is a flowchart showing the operational steps of an optimization routine or process 700 for determining the optimal fluid drip infusion volume of a tissue site, executed by the system 100 of FIG. 1. In some embodiments, process 700 can use a step - up process or a step - up drip infusion profile. Process 700 begins at block 702 where, in response to process 200, the system 100 receives an initial infusion volume (IIV). For example, the controller 108 can receive an input from process 200 of FIG. 2 for setting an initial infusion volume (IIV) based on a visual estimate of the tissue site size. In some embodiments, a clinician can input that a small pre - packaged dressing was used, and the controller 108 can set the initial infusion volume (IIV) to the expected volume associated with the use of a small dressing. Similarly, if a medium, large, or extra - large pre - packaged dressing was used, the controller 108 can set the initial infusion volume (IIV) to the expected volume associated with the use of a medium, large, or extra - large pre - packaged dressing. Process 700 continues to block 704 where the initial drip infusion volume (IIV) is stored. For example, the controller 108 can store the value associated with the initial drip infusion volume (IIV).

[0077] At block 706, an initial infusion volume (IIV) is infused into the tissue site. For example, the controller 108 can operate the positive pressure source 120 and the regulator 122 to infuse an initial drip infusion volume (IIV) into the dressing 104. In some embodiments, a dwell operation can be performed after the drip infusion of the infusion volume into the tissue site. In other embodiments, the dwell operation is not performed. The process 700 continues to block 708 where a value associated with the infusion volume (IV), which is the volume of the infused fluid, is stored. For example, the regulator 122 or the fluid source 118 can provide a signal indicating a value associated with the infusion volume (IV), which is the volume of the fluid infused into the tissue site, to the controller 108. The controller 108 can store a value associated with the infusion volume (IV), which is the volume of the fluid infused into the tissue site.

[0078] The process 700 continues to block 710 where fluid is drawn from the tissue site in a negative pressure therapy cycle and a volume of fluid is recovered. For example, the controller 108 can operate the negative pressure source 102 to draw fluid from the tissue site through the dressing 104 into the canister 106. The process 700 continues to block 712 where the process 700 measures and stores a volume of fluid associated with the recovered volume (RV), which is the volume of the recovered fluid. For example, the canister 106 can generate a signal indicating a value of the recovered volume (RV), which is the volume of the fluid recovered from the tissue site. The controller 108 can receive and store a value associated with the signal generated by the canister 106.

[0079] This process follows block 714 where process 700 compares the injection volume (IV) to the recovery volume (RV). For example, controller 108 can compare the value associated with the injection volume (IV) to the value associated with the recovery volume (RV). In block 716, process 700 determines whether the recovery volume (RV) is greater than the injection volume (IV). For example, controller 108 compares the value associated with the recovery volume (RV) to the value associated with the injection volume (IV). If the recovery volume (RV) is greater than the injection volume (IV), the process proceeds along the "yes" path to block 718 where process 700 reports an error and process 700 ends. For example, controller 108 can signal an alarm such as an audible alarm, a tactile alarm, or a visual alarm.

[0080] In block 716, if the recovered volume (RV) is not greater than the infused volume (IV), the process proceeds to decision block 720 where process 700 determines whether the recovered volume (RV) is less than the infused volume (IV). If the recovered volume (RV) is less than the infused volume (IV), process 700 proceeds along the "yes" path to block 722 where process 700 repeats injecting a volume of fluid by setting the initial infusion volume (IIV) to be a predetermined amount more than the infused volume (IV). For example, controller 108 can increase the initial infusion volume (IIV) by a predetermined amount. In some embodiments, this repetition can be selected in response to the relationship between the volume of fluid infused and the volume of fluid recovered. For example, if the volume of fluid recovered exceeds a threshold percentage of the volume of fluid infused, the system can determine that a bolus of fluid is being recovered. In response, the system can increase the reduction amount of subsequent drip infusion volume. In another example, if the volume of fluid recovered is below a threshold percentage of the volume of fluid infused, the system can determine that the infused fluid is insufficient. In response, the system can increase the subsequent drip infusion volume. The process continues to block 706 where process 700 is repeated.

[0081] In block 720, if the recovered volume (RV) is not less than the infused volume (IV), process 700 proceeds along the "no" path to block 720 where process 700 reports optimization and then continues to block 722 where process 700 starts drip infusion by negative pressure closed therapy. For example, controller 108 reports that dressing 104 is at an optimal drip infusion volume using an auditory indicator, a tactile indicator, a visual indicator, etc., and controller 108 starts drip infusion by negative pressure closed therapy.

[0082] FIG. 8 is a combination of a bar graph and a line graph showing the determination of an optimal fluid instillation volume according to the operational steps of FIG. 7. In FIG. 8, the y-axis represents the volume of fluid, and the x-axis represents time. In each cycle through process 700, an exploratory volume of fluid is instilled into the tissue site. For example, in each subsequent instillation cycle of process 700, system 100 delivers different volumes of fluid until the tissue site and dressing 104 are saturated. Each negative pressure therapy cycle will have approximately the same length. For example, in each negative pressure therapy cycle of process 700, system 100 will operate the negative pressure source 102 for a period of time of approximately the same length. As shown by bar lines 804, 808, 812, 816, and 820, the negative pressure therapy cycles are of approximately the same length. In each negative pressure therapy cycle, system 100 will recover different amounts of fluid. When fluid is instilled into the tissue site, tissue interface 114 may absorb a certain amount of fluid. Therefore, the amount of fluid recovered during a negative pressure therapy cycle is the amount of fluid delivered minus the amount of fluid absorbed by tissue interface 114.

[0083] Line 822 indicates the total volume of fluid retained by the tissue site, such as tissue interface 114, after each negative pressure therapy cycle. The total volume of fluid retained after each negative pressure therapy cycle will increase until the tissue interface 114 and the tissue site are saturated. Saturation occurs when the negative pressure therapy cycle retrieves a volume equal to the volume of the injected fluid. In the illustrated embodiment, after the negative pressure therapy cycle indicated by dash line 804, a first volume of fluid 824 has been retrieved. The first volume of fluid 824 is less than the volume of fluid injected during the injection cycle of dash line 802. The remainder of the total volume of fluid injected during injection cycle 802 is retained in the tissue site by tissue interface 114, as indicated by the first volume of retained fluid 825. As shown in FIG. 8, the first volume of fluid 824 can be considered small relative to the volume of fluid injected, and in response, subsequent injection volumes can be increased. For example, the volume of fluid injected during the injection cycle of dash line 806 is greater than the volume of fluid injected during the injection cycle of dash line 802. Line 822 indicates that at time point 834, the total volume of fluid retained is substantially equal to the first volume of retained fluid 825.

[0084] After the negative pressure therapy cycle indicated by the stem line 808, a second volume of fluid 826 has been recovered. The second volume of fluid 826 is also, in this case, less than the volume of fluid injected during the injection cycle 806; however, the second volume of fluid 826 can represent a larger proportion of the volume of fluid injected during the injection cycle 806. The remainder of the total volume of fluid injected during the injection cycle 806 is retained at the tissue site by the tissue interface 114, as indicated by the second volume of retained fluid 827. Line 822 indicates that at time point 836, the total volume of fluid retained is substantially equal to the first volume of retained fluid 827 and the second volume of retained fluid 829. As shown in FIG. 8, the second volume of fluid 826 can be considered large relative to the volume of fluid injected, and in response, subsequent injection volumes can be decreased. For example, the volume of fluid injected during the injection cycle of the stem line 810 is less than the volume of fluid injected during the injection cycle 806.

[0085] After the negative pressure therapy cycle indicated by the bar line 812, a third volume of fluid 828 has been recovered. The third volume of fluid 828 is also, in this case, less than the volume of fluid injected during the infusion cycle 810; however, the third volume of fluid 828 may represent a larger proportion of the volume of fluid injected during the infusion cycle 810. The remainder of the total volume of fluid injected during the infusion cycle 810 is retained at the tissue site by the tissue interface 114, as indicated by the third volume of retained fluid 829. The line 822 indicates that, at time point 838, the total volume of fluid retained is substantially equal to the first volume of retained fluid 825, the second volume of retained fluid 827, and the third volume of retained fluid 829. As represented at time point 838, the fact that the line 822 is equal to the amount of fluid injected at the bar line 802 indicates that the dressing 104 and the tissue site have reached saturation and that the infusion volume has been optimized. The subsequent infusion cycles 814 and 818, and the corresponding negative pressure cycles 816 and 820, are recovering volumes of fluid 830 and 832 that are substantially equal to the volume of fluid injected in the preceding infusion cycle. In response, the line 822 remains substantially horizontal, which further indicates that the tissue site and the dressing 104 have reached saturation.

[0086] The systems, devices, and methods described herein may provide numerous advantages. For example, the therapy system 100 provides a process for determining the equilibrium state of a tissue site. By determining the equilibrium state of the tissue site, the therapy system 100 can optimize the delivery of the infusion solution and reduce the risk of overfilling or underfilling the tissue site. Optimization can also reduce the clinician's time requirements and improve the ease of use of systems that provide infusion and negative pressure wound therapy, leading to improved patient outcomes and broader adoption of beneficial therapies.

[0087] Although shown in several exemplary embodiments, those skilled in the art will recognize that the systems, devices, and methods described herein are amenable to various changes and modifications that fall within the scope of the appended claims. Further, the description of various alternative examples using terms such as "or" is not required to be mutually exclusive unless clearly required by the context, and the indefinite articles "a" or "an" do not limit the object to a single instance unless clearly required by the context. Components can also be combined or removed in various configurations for purposes of sale, manufacture, assembly, or use. For example, in some configurations, the dressing material 104, the container 115, or both can be excluded or separated from other components for purposes of manufacture or sale. In other exemplary configurations, the controller 108 can also be manufactured, configured, assembled, or sold independently of other components.

[0088] The appended claims set forth novel and inventive aspects of the above-described subject matter, but the claims may also encompass additional subject matter that is not particularly recited in detail. For example, a particular feature, element, or aspect can be omitted from the claims if it is not necessary to distinguish novel and inventive features from those known to those skilled in the art. Features, elements, and aspects described in the context of some embodiments can also be omitted, combined, or replaced with alternative features that serve the same purpose, equivalent purpose, or similar purpose without departing from the scope of the invention as defined by the appended claims.

Claims

1. A system for treating a tissue site, comprising: An infusion source configured to provide an infusion solution to the tissue site; A negative pressure source configured to draw fluid from the tissue site to generate a negative pressure at the tissue site; A controller communicatively coupled to the infusion source and the negative pressure source, the controller being configured to: Operate the infusion source; Operate the negative pressure source; and A sensor communicatively coupled to the controller and operatively coupled to the infusion source and the negative pressure source, the sensor being configured to generate a signal indicative of an amount of fluid delivered to the tissue site and an amount of fluid recovered from the tissue site.

2. The system of claim 1, wherein the controller is configured to operate the infusion source to saturate the tissue site.

3. The system of claim 2, wherein saturation includes drawing a volume of fluid from the tissue site that is the same volume as the volume delivered by the infusion source.

4. The system of claim 1, wherein the controller is configured to determine saturation of the tissue site.

5. The system of claim 4, wherein the controller operates a uniform infusion profile.

6. The uniform infusion profile includes: The controller operating the infusion source to provide an infusion volume (IV); The controller operating the negative pressure source to recover a recovery volume (RV); When the recovery volume (RV) is greater than the infusion volume (IV), the controller generating an alarm signal; When the recovery volume (RV) is approximately equal to the infusion volume (IV), the controller determining that saturation has been achieved and operating the infusion source and the negative pressure source to provide infusion therapy and negative pressure therapy; and When the recovery volume (RV) is less than the infusion volume (IV), the controller determining that saturation has not been achieved and operating the infusion source to provide the infusion volume (IV).

7. The system according to claim 4, wherein the controller operates the infusion source using a step - up infusion profile.

8. The step - up infusion profile is such that the controller operates the infusion source to provide an infusion volume (IV); the controller operates the negative pressure source to recover a recovery volume (RV); if the recovery volume (RV) is greater than the infusion volume (IV), the controller generates an alarm signal; if the recovery volume (RV) is approximately equal to the infusion volume (IV), the controller determines that saturation has been achieved and operates the infusion source and the negative pressure source to provide infusion therapy and negative pressure therapy; if the recovery volume (RV) is less than the infusion volume (IV) by about the infusion volume (IV), the controller determines that saturation has not been achieved and increases the infusion volume (IV), the system according to claim 7.

9. The system according to claim 4, wherein the controller operates the infusion source using a bolus - first infusion profile.

10. The bolus - first infusion profile is such that the controller operates the infusion source to provide an infusion volume (IV); the controller operates the negative pressure source to recover a recovery volume (RV); if the recovery volume (RV) is greater than the infusion volume (IV), the controller generates an alarm signal; if the recovery volume (RV) is approximately equal to the infusion volume (IV), the controller determines that saturation has been achieved and operates the infusion source and the negative pressure source to provide infusion therapy and negative pressure therapy; if the recovery volume (RV) is less than the infusion volume (IV) by about the infusion volume (IV), the controller determines that saturation has not been achieved and decreases the infusion volume (IV), the system according to claim 9.

11. The system according to claim 1, comprising a plurality of sensors, wherein the sensors are configured to determine the volume of fluid infused and the volume of fluid recovered.

12. The system of claim 11, wherein the plurality of sensors includes strain gauges, and the controller determines the weight of the volume of the injected fluid and the weight of the volume of the recovered fluid. **Claim 13** The system of claim 11, wherein the plurality of sensors includes Hall effect sensors, and the controller determines the height of the volume of the injected fluid and the height of the volume of the recovered fluid. **Claim 14** The system of claim 11, wherein the plurality of sensors includes optical sensors. **Claim 15** A method for determining saturation of a tissue site, comprising: receiving, using a controller, a signal indicative of an injected volume (IV); receiving, using the controller, a signal indicative of a recovered volume (RV); comparing, using the controller, the injected volume (IV) with the recovered volume (RV); determining a saturation state of the tissue site in response to comparing the injected volume (IV) with the recovered volume (RV). **Claim 16** Determining the saturation state of the tissue site includes: when the recovered volume (RV) is greater than the injected volume (IV), the controller generates an alarm signal; when the recovered volume (RV) is approximately equal to the injected volume (IV), the controller determines that saturation has been achieved; when the recovered volume (RV) is less than the injected volume (IV), the controller determines that saturation has not been achieved. The method of claim 15. **Claim 17** Determining the saturation state of the tissue site includes: when the recovered volume (RV) is greater than the injected volume (IV), the controller generates an alarm signal; when the recovered volume (RV) is approximately equal to the injected volume (IV), the controller determines that saturation has been achieved; when the recovered volume (RV) is less than the injected volume (IV), the controller determines that saturation has not been achieved and increases the injected volume (IV). The method of claim 15. **Claim 18** Determining the saturation state of the tissue site includes: when the recovered volume (RV) is greater than the injected volume (IV), the controller generates an alarm signal; When the recovery volume (RV) is approximately equal to the infusion volume (IV), the controller determines that saturation has been achieved, and When the recovery volume (RV) is less than approximately the infusion volume (IV), the controller determines that saturation has not been achieved and decreases the infusion volume (IV). The method according to claim 15, comprising: **Claim 19** A system for treating a tissue site, comprising: A controller communicatively coupled to an infusion source and a negative pressure source, Configured to operate the infusion source to provide an infusion therapy, A controller configured to operate the negative pressure source to provide a negative pressure therapy; and An infusion sensor communicatively coupled to the controller and configured to generate a signal indicative of an infusion volume (IV); and A recovery volume (RV) sensor communicatively coupled to the controller and configured to generate a signal indicative of a recovery volume (RV). **Claim 20** The system according to claim 19, wherein the controller operates a uniform infusion profile. **Claim 21** The uniform infusion profile comprises: The controller operates the infusion source to provide the infusion volume (IV); The controller operates the negative pressure source to recover the recovery volume (RV); When the recovery volume (RV) is greater than the infusion volume (IV), the controller generates an alarm signal; When the recovery volume (RV) is approximately equal to the infusion volume (IV), the controller determines that saturation has been achieved and operates the infusion source and the negative pressure source to provide an infusion therapy and a negative pressure therapy; and When the recovery volume (RV) is less than approximately the infusion volume (IV), the controller determines that saturation has not been achieved and operates the infusion source to provide the infusion volume (IV). The system according to claim 20, comprising: **Claim 22** The system according to claim 19, wherein the controller operates a stepwise increasing infusion profile. **Claim 23** The stepwise increasing infusion profile comprises: The controller operates the infusion source to provide the infusion volume (IV); The controller operating the negative pressure source to recover the recovery volume (RV); When the recovery volume (RV) is greater than the infusion volume (IV), the controller generating an alarm signal; When the recovery volume (RV) is approximately equal to the infusion volume (IV), the controller determining that saturation has been achieved and operating the infusion source and the negative pressure source to provide infusion therapy and negative pressure therapy; When the recovery volume (RV) is less than the infusion volume (IV) by about the infusion volume (IV), the controller determining that saturation has not been achieved and increasing the infusion volume (IV), the system according to claim 22.

24. The system according to claim 19, wherein the controller operates a bolus-first infusion profile.

25. The bolus-first infusion profile is such that The controller operates the infusion source to provide the infusion volume (IV); The controller operates the negative pressure source to recover the recovery volume (RV); When the recovery volume (RV) is greater than the infusion volume (IV), the controller generating an alarm signal; When the recovery volume (RV) is approximately equal to the infusion volume (IV), the controller determining that saturation has been achieved and operating the infusion source and the negative pressure source to provide infusion therapy and negative pressure therapy; When the recovery volume (RV) is less than the infusion volume (IV) by about the infusion volume (IV), the controller determining that saturation has not been achieved and decreasing the infusion volume (IV), the system according to claim 24.

26. Systems, methods, and apparatuses as described and illustrated herein.

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