Optimal drip volume determination closed loop system for negative pressure wound therapy drip

Abstract

Systems and methods for treating a tissue site are described. The system includes an instillation source configured to provide an instillation 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 instillation source and the negative pressure source. The controller is configured to actuate the instillation source and the negative pressure source. The system also includes a sensor communicatively coupled to the controller and operatively coupled to the instillation source and the negative pressure source. The sensor is 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.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of priority to U.S. Provisional Application No. 63 / 388,867, filed on July 13, 2022, which is incorporated herein by reference in its entirety. Technical Field

[0003] The present invention as set forth in the appended claims generally relates to system volume determination in a tissue treatment system and more particularly, but not exclusively, to determining instillation volume at a tissue site. Background Art

[0004] Clinical studies and practice have shown that reducing the pressure near a tissue site can increase and accelerate the growth of new tissue at the tissue site. The application of this phenomenon is many, but it has been proven to be particularly beneficial for treating wounds. Regardless of the cause of the wound (whether it is trauma, surgery or other reasons), proper care of the wound is important for the result. Treating wounds or other tissues with reduced pressure is generally referred to as "negative pressure therapy", but is also referred to as other names, including, for example, "negative pressure wound therapy", "reduced pressure therapy", "vacuum therapy", "vacuum assisted closure" and "local negative pressure". Negative pressure therapy can provide many benefits, including migration of epithelial tissue and subcutaneous tissue, improvement of blood flow and micro-deformation of tissue at the wound site. In short, these benefits can increase the development of granulation tissue and reduce healing time.

[0005] It is also generally accepted that cleaning tissue sites can be highly beneficial for new tissue growth. For example, for therapeutic purposes, a wound or cavity can be flushed with a liquid solution. These practices are generally referred to as "flushing" and "irrigation", respectively. "Instillation" is another practice, which generally refers to the process of slowly introducing a fluid into a tissue site and retaining the fluid for a specified period of time before removing the fluid. For example, instillation of a topical treatment solution over a wound bed can be combined with negative pressure therapy to further promote wound healing by loosening soluble contaminants in the wound bed and removing infectious materials. Thus, the soluble bacterial burden can be reduced, contaminants can be removed, and the wound can be cleaned.

[0006] While the clinical benefits of negative pressure therapy and / or infusion therapy are well known, improvements to therapy systems, components, and processes may benefit healthcare providers and patients. Summary of the invention

[0007] New and useful systems, devices and methods for determining optimal instillation volume in a negative pressure environment are set forth in the appended claims. Exemplary embodiments are also provided to enable one skilled in the art to make and use the claimed subject matter.

[0008] For example, in some embodiments, a system for treating a tissue site is described. The system includes a drip source configured to provide an instillation solution to the tissue site, and a negative pressure source configured to aspirate fluid from the tissue site to produce a negative pressure at the tissue site. The system also includes a controller communicatively coupled to the drip source and the negative pressure source. The controller is configured to actuate the drip source and the negative pressure source. The system also includes a sensor communicatively coupled to the controller and operatively coupled to the drip source and the negative pressure source. The sensor is configured to generate a signal indicating the amount of the fluid delivered to the tissue site and the amount of the fluid recovered from the tissue site.

[0009] More generally, a system for treating a tissue site is described. The system may include a controller communicatively coupled to an infusion source and a negative pressure source. The controller may be configured to actuate the infusion source to provide infusion therapy and actuate the negative pressure source to provide negative pressure therapy. The system may include an infusion sensor communicatively coupled to the controller and configured to generate a signal indicating an infusion volume (IV). The system may also include a recovery volume (RV) sensor communicatively coupled to the controller and configured to generate a signal indicating a recovery volume (RV).

[0010] Also described herein is a method for determining the saturation of a tissue site, wherein some example embodiments provide: using a controller to receive a signal indicating an infusion volume (IV); using the controller to receive a signal indicating a recovery volume (RV); using the controller to compare the infusion volume (IV) with the recovery volume (RV); and determining the saturation state of the tissue site in response to comparing the infusion volume (IV) with the recovery volume (RV).

[0011] The objects, advantages and preferred modes of making and using the claimed subject matter may be best understood by referring to the accompanying drawings in conjunction with the following detailed description of illustrative embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a functional block diagram of an example embodiment of a therapy system that can provide negative pressure therapy and infusion therapy according to the present specification;

[0013] Figure 2 is a flow chart illustrating the operational steps of a method for determining an initial system volume to select a dressing for use with a tissue site;

[0014] Figure 3 is exemplified by Figure 1 A flowchart of the operational steps of a method performed by a system for determining an optimal fluid instillation volume for a tissue site;

[0015] Figure 4 It is an example based on Figure 3 A combined bar graph and line graph for determining optimal fluid instillation volumes for the steps of the operation;

[0016] Figure 5 is exemplified by Figure 1 A flowchart of the operational steps of another method performed by a system for determining an optimal fluid instillation volume for a tissue site;

[0017] Figure 6 It is an example based on Figure 5 A combined bar graph and line graph of determining optimal fluid instillation volumes for the steps of the operation;

[0018] Figure 7 is exemplified by Figure 1 A flowchart of the operational steps of another method performed by a system for determining an optimal fluid instillation volume for a tissue site;

[0019] Figure 8 It is an example based on Figure 7 Combined bar and line graph of the procedure steps for determining the optimal fluid instillation volume. DETAILED DESCRIPTION

[0020] The following description of example embodiments provides information enabling those skilled in the art to make and use the subject matter set forth in the appended claims, but may omit certain details already known in the art. Therefore, the following detailed description is to be regarded as illustrative rather than limiting.

[0021] Example embodiments may also be described herein with reference to the spatial relationship between various elements or with reference to the spatial orientation of various elements depicted in the accompanying drawings. Generally speaking, such relationship or orientation assumes a reference frame consistent with or relative to a patient in a position to receive treatment. However, as will be appreciated by those skilled in the art, such a reference frame is merely a descriptive convenience and not a strict requirement.

[0022] In this article, the term "tissue site" refers broadly to a wound, defect or other treatment target located on or in a tissue, including but not limited to surface wounds, bone tissue, adipose tissue, muscle tissue, nerve tissue, skin tissue, vascular tissue, connective tissue, cartilage, tendon or ligament. The term "tissue site" can also refer to an area of ​​any tissue that is not necessarily injured or defective, but rather an area in which it may be desirable to add additional tissue or promote the growth of additional tissue. For example, negative pressure can be applied to the tissue site to allow the additional tissue to grow, and then the additional tissue can be removed and transplanted. As used herein, a surface wound is a wound on the surface of the body exposed to the outer surface of the body, such as damage or damage to the epidermis, dermis and / or subcutaneous layer. A surface wound may include, for example, an ulcer or a closed incision. As used herein, a surface wound does not include a wound in the intra-abdominal cavity. Wounds may include, for example, chronic wounds, acute wounds, traumatic wounds, subacute wounds and dehiscence wounds, partial thickness burns, ulcers (such as diabetic ulcers, pressure sores or venous insufficiency ulcers), flaps and grafts.

[0023] Figure 1 1 is a simplified functional block diagram of an example embodiment of a treatment system 100 that can provide negative pressure therapy and topical treatment solution instillation to a tissue site according to the present specification. For example, the treatment system 100 may include a negative pressure source or negative pressure supply device such as negative pressure source 102, a dressing 104, a fluid container such as tank 106, and a regulator or controller such as controller 108. In addition, the treatment system 100 may include a sensor to measure an operating parameter and provide a feedback signal indicating the operating parameter to the controller 108. For example, Figure 1 As illustrated, the treatment system 100 may include a pressure sensor 110, an electrical sensor 112, or both coupled to the controller 108. Figure 1 As illustrated in the example of , in some embodiments, the dressing 104 can include or consist essentially of a tissue interface 114, a cover 116, or both.

[0024] The treatment system 100 may also include an instillation solution source. For example, the fluid source 118 may be fluidly coupled to the dressing 104, such as Figure 1As illustrated in the example embodiments of . In some embodiments, the fluid source 118 may be fluidly connected to a positive pressure source (such as positive pressure source 120), a negative pressure source (such as negative pressure source 102), or both. A regulator (such as a drip regulator 122) may also be fluidly connected to the fluid source 118 and the dressing 104 to ensure that an appropriate dose of infusion solution (e.g., saline or sterile water) is delivered to the tissue site. For example, the drip regulator 122 may 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 the negative pressure interval and drip the solution into the dressing during the ventilation interval. Additionally or alternatively, the controller 108 may be connected to the negative pressure source 102, the positive pressure source 120, or both to control the dose of the infusion solution to the tissue site. In some embodiments, the drip regulator 122 may also be fluidly connected to the negative pressure source 102 through the dressing 104, such as Figure 1 as shown in the example.

[0025] Some components of the treatment system 100 may be housed within or used in conjunction with other components, such as sensors, processing units, alarm indicators, memory, databases, software, display devices, or user interfaces that further facilitate treatment. For example, in some embodiments, the negative pressure source 102 may be combined with the fluid source 118, the controller 108, and other components into a treatment unit 124.

[0026] In general, the components of the treatment system 100 may be directly or indirectly coupled. For example, the negative pressure source 102 may be directly coupled to the tank 106, and may be indirectly coupled to the dressing 104 through the tank 106. The coupling may include a fluid coupling, a mechanical coupling, a thermal coupling, an electrical coupling, or a chemical coupling (such as a chemical bond), or in some cases some combination of couplings. For example, the negative pressure source 102 may be electrically coupled to the controller 108, and may be fluidly coupled to one or more distribution components to provide a fluid path to the tissue site. In some embodiments, the components may also be coupled by means of physical proximity, integration into a single structure, or being formed from the same piece of material. For example, the tissue interface 114 and the cover 116 may be discontinuous layers disposed adjacent to each other, and may be joined together in some embodiments.

[0027] The distribution components are preferably detachable and can be disposable, reusable or recyclable. Dressing 104 and tank 106 are examples of distribution components. Fluid conductor is another illustrative example of distribution components. In this context, "fluid conductor" broadly includes tubes, pipes, hoses, conduits or other structures with one or more lumens or open passages suitable for conveying fluid between two ends. Typically, the tube is an elongated cylindrical structure with a certain flexibility, but the geometry and rigidity can vary. In addition, some fluid conductors can be molded into other components or otherwise combined integrally with other components. The distribution components may also include or include an interface or fluid port to facilitate connecting and separating other components. In some embodiments, for example, a dressing interface may facilitate connecting the fluid conductor to the dressing 104.

[0028] Negative pressure supply device (such as negative pressure source 102) can be a reservoir of air at negative pressure, 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 micro pump. "Negative pressure" generally refers to a pressure less 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 where the tissue site is located. Alternatively, the pressure can be less than the hydrostatic pressure associated with the tissue at the tissue site. Unless otherwise specified, the value of the pressure stated herein is a gauge pressure. Mentioning the increase in negative pressure generally refers to the reduction in absolute pressure, and the reduction in negative pressure generally refers to the increase in absolute pressure. Although the amount and nature of the negative pressure supplied to the tissue site can vary according to treatment requirements, the pressure is generally a low vacuum between -5mmHg (-667Pa) and -500mmHg (-66.7kPa), which is also generally referred to as a rough vacuum. The common treatment range is between -50 mm Hg (-6.7 kPa) and -300 mm Hg (-39.9 kPa).

[0029] Canister 106 represents a container, canister, pouch, or other storage component that can be used to manage exudate and other fluids drawn from a tissue site. In many environments, a rigid container may be preferred or required for collecting, storing, and disposing of fluids. In other environments, fluids may be properly disposed of without rigid container storage, and reusable containers may reduce waste and costs associated with negative pressure therapy.

[0030] A controller, such as controller 108, may be a microprocessor or computer programmed to operate one or more components of the treatment system 100, such as the negative pressure source 102. In some embodiments, for example, the controller 108 may be a microcontroller, which typically includes an integrated circuit including a processor core and a memory programmed to directly or indirectly control one or more operating parameters of the treatment system 100. For example, the operating parameters may include the power applied to the negative pressure source 102, the pressure generated by the negative pressure source 102, or the pressure distributed to the tissue interface 114. The controller 108 is also preferably configured to receive one or more input signals, such as feedback signals, and is programmed to modify the one or more operating parameters based on the input signals.

[0031] Sensors such as pressure sensors 110 or electrical sensors 112 are generally considered in the art to be any device that can operate to detect or measure a physical phenomenon or characteristic, and generally provide a signal indicating the detected or measured phenomenon or characteristic. For example, the pressure sensor 110 and the electrical sensor 112 can be configured to measure one or more operating parameters of the treatment system 100. In some embodiments, the pressure sensor 110 can be a transducer that is configured to measure the pressure in the pneumatic passage and convert the measurement result into a signal indicating the measured pressure. In some embodiments, the pressure sensor 110 can be a piezoresistive strain gauge. In some embodiments, the electrical sensor 112 can optionally measure an operating parameter of the negative pressure source 102, such as voltage or current. Preferably, the signals from the voltage sensor 110 and the current sensor 112 are suitable as input signals to the controller 108, but some signal conditioning may be appropriately performed. For example, before the signal can be processed by the controller 108, it may be necessary to filter or amplify the signal. Typically, the signal is an electrical signal, but can be represented in other forms, such as an optical signal.

[0032] The tissue interface 114 may generally be adapted to partially or completely contact a tissue site. The tissue interface 114 may take a variety of forms and may have a variety of sizes, shapes, or thicknesses, depending on various factors, such as the type of treatment being performed or the nature and size of the tissue site. For example, the size and shape of the tissue interface 114 may be adapted to the contours of a deep and irregularly shaped tissue site.

[0033] In some embodiments, the tissue interface 114 may include or consist essentially of a manifold. The manifold herein may include or consist essentially of a device for collecting or distributing fluids passing through the tissue interface 114 under pressure. For example, the manifold may be adapted to receive negative pressure from a source and distribute the negative pressure across the tissue interface 114 through a plurality of holes, which may have the effect of collecting fluids from the entire tissue site and drawing fluids toward the source. In some embodiments, the fluid path may be reversed or may be provided to facilitate the delivery of a secondary fluid path through the tissue site for fluids, such as fluids from an instillation solution source.

[0034] In some exemplary embodiments, the manifold may include a plurality of passages that may be interconnected to improve the distribution or collection of fluids. In some exemplary embodiments, the manifold may include or be substantially composed of a porous material having interconnected fluid passages. Examples of suitable porous materials that may be suitable for forming interconnected fluid passages (e.g., channels) may include: porous foams, including open-cell foams, such as reticulated foams; porous tissue collections; and other porous materials that typically include pores, edges, and / or walls, such as gauze or felt pads. Liquids, gels, and other foams may also include or be cured to include orifices and fluid passages. In some embodiments, the manifold may additionally or alternatively include projections that form interconnected fluid passages. For example, the manifold may be molded to provide surface projections that define interconnected fluid passages.

[0035] In some embodiments, the tissue interface 114 may include or consist essentially of a reticulated foam having a pore size and free volume that may vary according to the needs of the prescribed treatment. For example, a reticulated foam having at least 90% free volume may be suitable for many therapeutic applications, and a foam having an average pore size in the range of 400 microns to 600 microns (40 to 50 pores / inch) may be particularly suitable for some types of treatment. The tensile strength of the tissue interface 114 may also vary according to the needs of the prescribed treatment. For example, for the instillation of a local therapeutic solution, the tensile strength of the foam may be increased. The 25% compressive load deflection of the tissue interface 114 may be at least 0.35 pounds per square inch, and the 65% compressive load deflection may be at least 0.43 pounds per square inch. In some embodiments, the tensile strength of the tissue interface 114 may be at least 10 pounds per square inch. The tissue interface 114 may 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 a polyester or a polyether), an isocyanate (such as toluene diisocyanate), and a polymerization modifier (such as an amine and a tin compound). In some examples, the tissue interface 114 can be a reticulated polyurethane foam, such as GRANUFOAM®, both available from Kinetic Concepts, Inc. of San Antonio, Texas. TM Dressing or VACVERAFLOTM Present in dressing.

[0036] The thickness of the tissue interface 114 may also vary depending on the needs of the prescribed treatment. For example, the thickness of the tissue interface may be reduced to reduce tension on the surrounding tissue. The thickness of the tissue interface 114 may also affect the conformability of the tissue interface 114. In some embodiments, a thickness in the range of about 5 mm to 10 mm may be suitable.

[0037] The tissue interface 114 can be hydrophobic or hydrophilic. In examples where the tissue interface 114 can be hydrophilic, the tissue interface 114 can also wick fluid away from the tissue site while continuing to distribute negative pressure to the tissue site. The wicking properties of the tissue interface 114 can wick fluid away from the tissue site by capillary flow or other wicking mechanisms. Examples of materials that may be suitable hydrophilic materials are polyvinyl alcohol, open-cell foams such as VACWHITEFOAM available from Kinetic Concepts, Inc. of San Antonio, Texas. TM Dressings. Other hydrophilic foams may include those made from polyethers. Other foams that may exhibit hydrophilic characteristics include hydrophobic foams that have been treated or coated to render them hydrophilic.

[0038] In some embodiments, the tissue interface 114 may be composed of a bioabsorbable material. Suitable bioabsorbable materials may include, but are not limited to, polymer blends of polylactic acid (PLA) and polyglycolic acid (PGA). Polymer blends may also include, but are not limited to, polycarbonate, polyfumarate, and caprolactone. The tissue interface 114 may also be used as a scaffold for new cell growth, or a scaffold material may be used in conjunction with the tissue interface 114 to promote cell growth. A scaffold is typically a material or structure for enhancing or promoting cell growth or tissue formation, such as a three-dimensional porous structure that provides a template for cell growth. Illustrative examples of scaffold materials include calcium phosphate, collagen, PLA / PGA, coral hydroxyapatite, carbonate, or treated allograft material.

[0039] In some embodiments, the cover 116 can provide a bacterial barrier and prevent physical trauma. The cover 116 can also be made of a material that can reduce evaporative losses and provide a fluid seal between two components or two environments (such as between the treatment environment and the local external environment). The cover 116 can be, for example, an elastomeric film or diaphragm that can provide a seal sufficient to maintain negative pressure at the tissue site for a given negative pressure source. In some applications, the cover 116 can have a high moisture vapor transmission rate (MVTR). For example, in some embodiments, the MVTR can be at least about 300 g / m per twenty-four hours. 2In some example embodiments, the cover 116 may be a polymer drape that is permeable to water vapor but impermeable to liquids, such as a polyurethane film. Such drapes typically have a thickness in the range of about 25 microns to about 50 microns. For permeable materials, the permeability should generally be low enough so that the desired negative pressure can be maintained.

[0040] The cover 116 may include, for example, one or more of the following materials: hydrophilic polyurethane; cellulose; hydrophilic polyamide; polyvinyl alcohol; polyvinyl pyrrolidone; hydrophilic acrylic resin; hydrophilic silicone elastomer; INSPIRE 2301 material, which is from Coveris Advanced Coatings of Wrexham, UK, and has a hardness of, for example, about 14400 g / m 2 / 24-hour MVTR (inverted cup technology) and a thickness of approximately 30 microns; thin, uncoated polymer drapes; natural rubber; polyisoprene; styrene-butadiene rubber; neoprene; polybutadiene; nitrile rubber; butyl rubber; ethylene-propylene rubber; ethylene-propylene-diene monomer; chlorosulfonated polyethylene; polysulfide rubber; polyurethane (PU); EVA film; copolyester; silicone; silicone drapes; 3M Drape; polyurethane (PU) drape, such as PU drape commercially available from Avery Dennison Corporation of Glendale, California; polyether block polyamide copolymer (PEBAX), for example from Arkema of France; INSPIRE 2327; or other suitable material.

[0041] Attachment means can be used to attach cover 116 to an attachment surface, such as an intact epidermis, a gasket or another cover. Attachment means can take many forms. For example, attachment means can be a medically acceptable pressure-sensitive adhesive that is configured to bond cover 116 to the epidermis around the tissue site. In some embodiments, for example, some or all of cover 116 may be coated with an adhesive that may have a coating amount between about 25 grams per square meter (gsm) and about 65g.sm, such as an acrylic adhesive. In some embodiments, a thicker adhesive or a combination of adhesives may be applied to improve sealing and reduce leakage. Other example embodiments of attachment means may include double-sided tape, paste, aqueous colloid, hydrogel, silicone gel or organic gel.

[0042] Fluid source 118 may also be representative of a container, canister, pouch, bag, or other storage component that may provide a solution for infusion therapy. The composition of the solution may vary depending on 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.

[0043] The fluid mechanics of using a negative pressure source to reduce the pressure in another component or location (such as within a sealed treatment environment) can be mathematically complex. However, the basic principles of fluid mechanics that can be applied to negative pressure therapy and instillation are generally well known to those skilled in the art, and the process of reducing pressure can be illustratively described herein as, for example, "delivering," "dispensing," or "generating" negative pressure.

[0044] Typically, exudate and other fluids flow along the fluid path in the direction of lower pressure. Therefore, the term "downstream" generally means a location in the fluid path that is relatively closer to the negative pressure source or farther away from the positive pressure source. On the contrary, the term "upstream" means a location that is relatively farther away from the negative pressure source or closer to the positive pressure source. Similarly, it may be convenient to describe certain features in such a reference frame according to the fluid "inlet" or "outlet". It is generally assumed that this orientation is for describing the various features and components of this article. However, in some applications, the fluid path may also be reversed, such as by replacing the negative pressure source with a positive pressure source, and this descriptive convention should not be understood as a restrictive convention.

[0045] Negative pressure applied across the tissue site through the tissue interface 114 in a sealed treatment environment can induce macro- and micro-strains in the tissue site. Negative pressure can also remove exudate and other fluids from the tissue site that may be collected in the canister 106.

[0046] In some embodiments, the controller 108 can receive and process data from one or more sensors such as a pressure sensor 110 and an electrical sensor 112. The controller 108 can also control the operation of one or more components of the treatment system 100 to manage the pressure delivered to the tissue interface 114. In some embodiments, the controller 108 may include an input for receiving a desired target pressure, and may be programmed to process data related to the setting and input of the target pressure to be applied to the tissue interface 114. In some example embodiments, the target pressure may be a fixed pressure value set by an operator as a target negative pressure desired for treatment at a tissue site and then provided as an input to the controller 108. The target pressure may vary from tissue site to tissue site based on the type of tissue forming the tissue site, the type of injury or wound (if any), the patient's medical condition, and the preferences of the attending physician. After selecting the desired target pressure, the controller 108 may operate the negative pressure source 102 in one or more control modes based on the target pressure, and may receive feedback from one or more sensors to maintain the target pressure at the tissue interface 114.

[0047] In some embodiments, the controller 108 may have a continuous pressure mode, wherein the negative pressure source 102 is operated to provide a constant target negative pressure during the duration of the treatment or until manual deactivation is performed. Additionally or alternatively, the controller may have an intermittent pressure mode. The controller 108 may operate the negative pressure source 102 to cycle between the target pressure and the atmospheric pressure. For example, the target pressure may be set to a value of 135 mmHg for a specified period of time (e.g., 5 minutes), followed by deactivation for a specified period of time (e.g., 2 minutes). The cycle may be repeated by activating the negative pressure source 102, which may form a square wave pattern between the target pressure and the atmospheric pressure.

[0048] In some example 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 used. For example, the initial rise time of one treatment system may be in the range of about 20 mmHg / second-30 mmHg / second, and the initial rise time of another treatment system may be in the range of about 5 mmHg / second-10 mmHg / second. If the treatment system 100 is operated in an intermittent mode, the repetitive rise time may be a value substantially equal to the initial rise time.

[0049] In the dynamic pressure mode, the target pressure may vary over time. For example, the target pressure may vary in the form of a triangular waveform, varying between a negative pressure of 50 mmHg to 135 mmHg, wherein the rise time is set at a rate of +25 mmHg / minute, and the fall time is set at a rate of -25 mmHg / minute. In other embodiments of the treatment system 100, the triangular waveform may vary between a negative pressure of 25 mmHg to 135 mmHg, wherein the rise time is set at a rate of +30 mmHg / minute, and the fall time is set at a rate of -30 mmHg / minute.

[0050] In some embodiments, the controller 108 can control or determine a variable target pressure in a dynamic pressure mode, and the variable target pressure can vary between a maximum pressure value and a minimum pressure value, which can be set as an input specified by the operator as a range of desired negative pressure. The variable target pressure can also be processed and controlled by the controller 108, which can change the target pressure according to a predetermined waveform (such as a triangular waveform, a sine waveform, or a sawtooth waveform). In some embodiments, the waveform can be set by the operator to a predetermined or time-varying negative pressure desired for treatment.

[0051] In some embodiments, the controller 108 may receive and process data, such as data related to the instillation solution provided to the tissue interface 114. Such data may include the type of instillation solution specified by the clinician, the volume of the fluid or solution to be instilled into the tissue site ("fill volume"), and the amount of time specified for leaving the solution at the tissue site before applying negative pressure to the tissue site ("residence time"). The fill volume may be, for example, between 10mL and 500mL, and the residence time may be between one second and 30 minutes. The controller 108 may also control the operation of one or more components of the treatment system 100 to instill the solution. For example, the controller 108 may manage the fluid distributed to the tissue interface 114 from the solution source 118. In some embodiments, the fluid may be instilled into the tissue site by applying negative pressure from the negative pressure source 102 to reduce the pressure at the tissue site, and the solution may be sucked into the tissue interface 114. In some embodiments, the solution may be instilled 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 may be elevated to a height sufficient to allow gravity to move the solution into the tissue interface 114 .

[0052] The controller 108 can also control the fluid dynamics of the instillation by providing a continuous flow of solution or an intermittent flow of solution. Negative pressure can be applied to provide a continuous flow of solution or an intermittent flow. The application of negative pressure can be implemented to provide a continuous pressure operating mode to achieve a continuous flow rate of the instillation solution through the tissue interface 114, or the application of negative pressure can be implemented to provide a dynamic pressure operating mode to change the flow rate of the instillation solution through the tissue interface 114. Alternatively, the application of negative pressure can be implemented to provide an intermittent operating mode to allow the instillation solution to stay at the tissue interface 114. In the intermittent mode, a specific fill volume and residence time can be provided, which depends on, for example, the type of tissue site being treated and the type of dressing being utilized. After or during the instillation of the solution, negative pressure therapy can be applied. The controller 108 can be used to select the operating mode and the duration of the negative pressure therapy before starting another instillation cycle by instilling more solution.

[0053] Some treatment systems that provide negative pressure therapy and instillation therapy may have difficulty determining a clinically appropriate instillation volume. Some clinicians may not be familiar with the technical aspects of negative pressure wound therapy instillation and may not be able to determine the instillation volume appropriate for an individual tissue site. Other clinicians may be obscured from their view of the tissue site by an opaque dressing or wound filler. Still other clinicians may face other obstacles to the correct administration of negative pressure wound therapy instillation. Failure to determine the appropriate instillation volume for a tissue site may result in overfilling of the tissue site. Overfilling of a tissue site or dressing may point to a tissue site instilling a volume of fluid that is larger than the volume of the tissue site itself. Overfilling may increase the pressure at the tissue site and cause the dressing to fail, allowing fluid to leak from the dressing. Since the dressing covering the tissue site may no longer remain sealed during the negative pressure therapy interval, fluid leakage caused by overfilling may also lead to failure of negative pressure therapy.

[0054] Failure to provide an appropriate volume of instillation solution may also result in insufficient filling of a tissue site. Insufficient filling may refer to a volume of fluid that is insufficient to properly saturate the tissue site with an instillation of the tissue site. Insufficient filling of the instillation solution may reduce the effectiveness of the instillation therapy, thereby reducing the benefits that the patient may receive from the instillation therapy. Preventing overfilling and underfilling relies on proper estimation of the volume of the tissue site. Proper estimation of the size and volume of the tissue site may sometimes be a time-consuming process. Unfortunately, the time demands of a clinician for patient care may exceed the number of hours in a day. Therefore, excessive time demands may result in a reduction in the adoption of negative pressure wound therapy instillations because clinicians may avoid adopting or using negative pressure wound therapy instillations. Avoiding the adoption of negative pressure wound therapy instillations may prevent a wider population from receiving the benefits of instillation therapy and negative pressure wound therapy.

[0055] These limitations and others can be addressed by the treatment system 100, which can provide systems and methods for determining optimal instillation volumes for individual tissue sites. Determining the optimal instillation volume for an individual tissue site allows the treatment system 100 to optimize the delivery of the instillation solution, thereby reducing the risk of overfilling or underfilling the tissue site. Determining the optimal instillation volume by using the system 100 can also reduce the time demands of the clinician and improve the ease of use of the system providing instillation and negative pressure wound therapy, thereby leading to improved patient outcomes and wider adoption of beneficial treatments.

[0056] For example, the treatment system 100 can provide intervals for dripping, solution retention, and controlled negative pressure. In some embodiments, the controller 108 of the treatment system 100 can be equipped with a drip volume determination and control logic component and a method for determining the drip volume. The treatment system 100 also includes an apparatus for dripping variable volume solutions, 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 a tissue site. In some embodiments, the system 100 determines the optimal drip volume. The optimal drip volume can be a volume that achieves saturation of the dressing 104. Saturation occurs when the drip cycle and the negative pressure cycle reach a balance, that is, the negative pressure cycle removes the same volume of liquid as dripped by the drip cycle. The balance can also be expressed as a point where the drip volume retained by the dressing is maximized.

[0057] In some embodiments, the controller 108 can be communicatively coupled to the tank 106. The tank 106 can include a sensor 126 or other device configured to determine the volume of the fluid received from the tissue site. For example, the controller 108 and the sensor 126 can determine the volume of the fluid received from the dressing 104 by tachometry, weight change or other suitable methods. In some embodiments, the sensor 126 can be a strain gauge. When the fluid enters the tank 106, the weight of the fluid added to the tank 106 can increase the force on the sensor 126. The signal generated by the sensor 126 in response to the 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 an intermediate value of the fluid weight to determine the additional amount of fluid added to the tank 106 in a subsequent negative pressure therapy cycle.

[0058] In other embodiments, the sensor 126 may be a tachometer such as a Hall effect sensor. For example, the sensor 126 may be disposed at the fluid inlet of the tank 106. The fluid flowing through the sensor 126 during the negative pressure therapy cycle may cause the sensor 126 to generate a signal representing the rotational speed. The signal may be received by the controller 108 and interpreted as a corresponding volume. In other embodiments, the sensor 126 may be a glass level gauge or a float. The sensor 126 may be a type of hydrostatic device such as a displacer, a bubbler, or a differential pressure transmitter. The sensor 126 may be a load cell, a magnetic level gauge, or a capacitive transmitter. In other embodiments, the sensor 126 may be a magnetostrictive level transmitter, an ultrasonic level transmitter, a laser level transmitter, or even a radar level transmitter. The sensor 126 may also be other types of level sensors, such as a resistor chain, a gamma ray, or a microwave sensor. In an exemplary embodiment, the sensor 126 may be an optical level sensor such as produced by Strain Measurement Devices or a fiber optic water sensor such as the 44.1WS-B / K1 or 44.2WS-G produced by Wolf GmbH. Other suitable sensors may be produced by SEMRAD Process Control and Monitoring, such as those produced for level transmitters and indicators, and sensors produced for wastewater level monitoring, such as the dBi HART ultrasonic smart transducers produced by Pulsar Measurement, which may represent suitable types of sensors.

[0059] Preferably, the sensor 126 is communicatively coupled to the controller 108, thereby allowing the controller 108 to distinguish the volume of fluid received for each negative pressure therapy cycle from the volume of fluid previously contained in the canister 106. In some embodiments, the sensor 126 can be a separate flow meter that is fluidly coupled between the canister 106 and the dressing 104 and communicatively coupled to the controller 108 to determine the volume of fluid that enters the canister 106 during each negative pressure therapy cycle. In some embodiments, the controller 108 can be configured to adjust the negative pressure therapy in response to the signal received from the sensor 126.

[0060] In some embodiments, the controller 108 is communicatively coupled to the fluid source 118 and / or the regulator 122. The fluid source 118 and / or the regulator 122 may include a sensor 128 or other device configured to determine the volume of fluid delivered to the dressing 104. For example, the controller 108 and the sensor 128 may determine the amount of fluid delivered to the dressing 104 by flow rate measurement, weight change, or other suitable methods. In some embodiments, the sensor 128 may be a strain gauge. When the fluid leaves the fluid source 118, the weight of the fluid may reduce the force on the sensor 128. The signal generated by the sensor 128 in response to the force may be received by the controller 108 and interpreted as the weight of the fluid and the corresponding delivery volume. In some embodiments, the controller 108 may store intermediate values ​​of the fluid weight to determine the additional amount of fluid removed from the fluid source 118 in a subsequent drip therapy cycle.

[0061] In other embodiments, the sensor 128 can be a tachometer such as a Hall effect sensor. For example, the sensor 128 can be disposed at the fluid outlet of the regulator 122. The fluid flowing through the sensor 128 during the infusion therapy cycle can cause the sensor 128 to generate a signal representing the rotational speed. The signal can be received by the controller 108 and interpreted as a corresponding volume.

[0062] Preferably, the sensor 128 is communicatively coupled to the controller 108, thereby allowing the controller 108 to distinguish the volume of fluid delivered by each drip therapy cycle from the volume of fluid previously delivered by the regulator 122. In some embodiments, the sensor 128 can be a separate flow meter that is fluidly coupled between the regulator 122 and the dressing 104 and communicatively coupled to the controller 108 to determine the volume of fluid that enters the dressing 104 in each drip therapy cycle. In some embodiments, the controller 108 can be configured to adjust the drip therapy in response to the signal received from the sensor 128.

[0063] Figure 21 is a flow chart illustrating the operational steps of a method 200 for determining an initial tissue site volume to select a dressing for use with a tissue site. In some embodiments, a clinician may perform steps associated with the method 200. In other embodiments, a controller 108 of the system 100 may perform steps associated with the method 200. The method begins at frame 202, where the size of the tissue site is estimated. In some embodiments, a clinician may visually estimate the size of the tissue site. For example, a clinician may visually observe the tissue site and make an initial estimate of the size of the tissue site. In some embodiments, a clinician may visually estimate the tissue site as small, medium, large, or extra large. In some embodiments, a clinician may be assisted by the presence of a similarly named prepackaged dressing. A clinician may visually compare a prepackaged dressing with a tissue site to determine whether the prepackaged dressing is the appropriate size.

[0064] The method continues at frame 204, where the method 200 determines whether the tissue site is a small tissue site. For example, the clinician can compare a small pre-packaged dressing with the tissue site to determine whether the small pre-packaged dressing can fill the tissue site. If the tissue site is a small tissue site, the method continues to frame 206 on the "yes" path, where the method 200 applies the small dressing to the tissue site. For example, the clinician can place a dressing 104 with a small volume at the tissue site. The method 200 continues to frame 218, where an optimization routine is started. For example, the clinician can provide information that a small dressing is positioned at the tissue site to the controller 108 by using a user interface, and the controller 108 starts the optimization routine.

[0065] At frame 204, if the tissue site is not a small tissue site, the method continues on a "no" path to frame 208, where the method 200 determines whether the tissue site is a medium tissue site. For example, the clinician can compare a medium pre-packaged dressing with the tissue site to determine whether the medium pre-packaged dressing can fill the tissue site. If the tissue site is a medium tissue site, the method continues on a "yes" path to frame 210, where the method 200 uses a medium dressing for the tissue site. For example, the clinician can place a dressing 104 with a medium volume at the tissue site. The method 200 continues to frame 218, where an optimization routine is started. For example, the clinician can provide information that a medium dressing is positioned at the tissue site to the controller 108 by using a user interface, and the controller 108 starts an optimization routine.

[0066] At frame 208, if the tissue site is not a medium tissue site, the method continues on a "no" path to frame 212, where the method 200 determines whether the tissue site is a large tissue site. For example, the clinician can compare a large pre-packaged dressing to the tissue site to determine whether the large pre-packaged dressing can fill the tissue site. If the tissue site is a large tissue site, the method continues on a "yes" path to frame 214, where the method 200 uses a large dressing for the tissue site. For example, the clinician can place a dressing 104 with a large volume at the tissue site. The method 200 continues to frame 218, where an optimization routine is started. For example, the clinician can provide information that a large dressing is positioned at the tissue site to the controller 108 by using a user interface, and the controller 108 starts the optimization routine. At frame 212, if the tissue site is not a large tissue site, the method continues on a "no" path to frame 216, where the method 200 uses an extra-large dressing for the tissue site. For example, the clinician can place a dressing 104 with an extra-large volume at the tissue site. The method 200 continues to block 218 where an optimization routine is initiated. For example, the clinician may provide information to the controller 108 that an oversized dressing is positioned at the tissue site by using a user interface, and the controller 108 begins the optimization routine.

[0067] Figure 3 is exemplified by Figure 1 Flowchart of the operational steps of an optimization routine or method 300 performed by the system 100 for determining an optimal fluid instillation volume for a tissue site. In some embodiments, the method 300 may use a uniform process, a uniform instillation distribution, or a uniform optimization routine. A uniform instillation distribution may refer to cyclically delivering the same volume of fluid in each instillation cycle. The method 300 begins at block 302, where the system 100 receives an instillation volume (IV). In some embodiments, the controller 108 may receive an instillation volume (IV) from Figure 2 The method 200 of receives input to set an initial instillation volume based on a visual estimate of the size of the tissue site. For example, the clinician may input that a small pre-packaged dressing is used, and the controller 108 may set the instillation volume (IV) to the expected volume associated with the use of a small dressing. Similarly, if a medium, large, or extra-large pre-packaged dressing is used, the controller 108 may set the instillation volume (IV) to the expected volume associated with the use of a medium, large, or extra-large pre-packaged dressing.

[0068] The method continues at frame 304, where the instillation volume (IV) is instilled into the tissue site. For example, the controller 108 can actuate the positive pressure source 120 and the regulator 122 to instill the instillation volume (IV) into the tissue site. In some embodiments, a stay operation can be performed after the instillation volume (IV) is instilled into the tissue site. The stay operation can be an operation that allows the instillation volume to remain in the dressing for a predetermined time period. In other embodiments, the stay operation is not performed. The method continues at frame 306, where a value associated with the instillation volume (IV) is stored. For example, a sensor 128 associated with the regulator 122 and / or the fluid source 118 can provide a signal to the controller 108, which indicates a value associated with the volume of the fluid instilled into the tissue site, i.e., the instillation volume (IV). The controller 108 can store a value associated with the volume of the fluid instilled into the tissue site or the instillation volume (IV).

[0069] Method 300 continues at frame 308, wherein fluid is aspirated from tissue site and a certain volume of fluid is recovered in a negative pressure therapy cycle. For example, controller 108 can operate negative pressure source 102 to aspirate fluid from tissue site through dressing 104 and into tank 106. In some embodiments, the operation of negative pressure source 102 can be used for a cycle of negative pressure therapy. The method continues at frame 310, wherein method 300 measures and stores the volume of fluid associated with the volume of recovered fluid, i.e., recovery volume (RV). For example, sensor 126 can generate a signal indicating the value of the volume (recovery volume (RV)) of fluid recovered from tissue site. Controller 108 can receive and store a value associated with the signal generated by sensor 126, i.e., recovery volume (RV).

[0070] The method continues at box 312, where the method 300 compares the instillation volume (IV) with the recovery volume (RV). For example, the controller 108 can compare the value associated with the instillation volume (IV) with the value associated with the recovery volume (RV). At box 314, the method 300 determines whether the recovery volume (RV) is greater than the instillation volume (IV). For example, the controller 108 compares the value associated with the recovery volume (RV) with the value associated with the instillation volume (IV). If the recovery volume (RV) is greater than the instillation volume (IV), the method continues on the "yes" path to box 316, where the method 300 reports an error and the method 300 ends. For example, the controller 108 can send an alarm signal, such as an audible alarm, a tactile alarm, or a visual alarm.

[0071] At box 314, if the recovery volume (RV) is not greater than the instillation volume (IV), the method 300 continues to decision box 318, where the method 300 determines whether the recovery volume (RV) is less than the instillation volume (IV). If the recovery volume (RV) is less than the instillation volume (IV), the method 300 continues along the "yes" path to box 304, where the method 300 repeats. If the recovery volume (RV) is not less than the instillation volume (IV), the method 300 continues on the "no" path to box 320, where the method 300 reports optimization and continues to box 322. At box 322, the method 300 starts negative pressure wound therapy instillation. For example, the controller 108 reports that the dressing 104 is at the optimal instillation volume, such as with an audible indicator, a tactile indicator, or a visual indicator, and the controller 108 starts negative pressure wound therapy instillation. In some embodiments, the controller 108 can track the number and volume of instillations during the method 300. Once the controller 108 determines that saturation has been reached, the controller 108 can provide an optimized instillation volume for the instillation with negative pressure therapy. The optimized instillation volume can be based in part on the number and size of instillations during the method 300 and the estimated instillation fluid remaining in the tissue site after each volume of fluid is instilled during the method 300. In addition to the size of the tissue site, the optimized instillation volume can also vary with the negative pressure setting and the negative pressure duration.

[0072] Figure 4 It is an example based on Figure 3 Combined bar and line graph of fluid volume for each step of the procedure. Figure 4 , the y-axis represents the volume of fluid, and the x-axis represents time. In each cycle through method 300, the instillation volume (IV) is the same, that is, the volume of fluid delivered to the dressing 104 is the same. For example, in each instillation cycle occurring at box 304 of method 300, the system 100 delivers the same volume of fluid. As illustrated by bars 402, 406, 410, 414, and 418, the same volume of fluid is delivered through each iteration of method 300, that is, the instillation volume (IV) is the same. Similarly, each negative pressure therapy cycle occurring at box 308 of method 300 will have approximately the same length. For example, in each negative pressure therapy cycle of method 300, the system 100 will operate the negative pressure source 102 for approximately the same length of time. As illustrated by bars 404, 408, 412, 416, and 420, the negative pressure therapy cycle has approximately the same length. In each negative pressure therapy cycle, the system will recycle different amounts of fluid. When fluid is instilled 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 will be the amount of fluid delivered minus the amount of fluid absorbed by the tissue interface 114.

[0073] Line 422 illustrates the total aggregate volume of fluid retained by a tissue site (e.g., tissue interface 114) after each negative pressure therapy cycle. The aggregate 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 a negative pressure therapy cycle recovers a volume equal to the volume of fluid instilled. In the illustrated embodiment, after the negative pressure therapy cycle illustrated by bar 404, a first fluid volume 426 is recovered. The first fluid volume 426 is less than the volume of fluid instilled during the instillation cycle of bar 402. The remainder of the total volume of fluid instilled during the instillation cycle 402 is retained at the tissue site by the tissue interface 114, as illustrated by the first retained fluid volume 427. After the negative pressure therapy cycle illustrated by bar 408, a second fluid volume 428 is recovered. The second fluid volume 428 is greater than the first fluid volume 426 and less than the volume of fluid instilled during the instillation cycle of bar 406. 426. The remainder of the fluid volume instilled during instillation cycle 406 is retained at the tissue site by tissue interface 114, as illustrated by second retention volume 429. Second retained fluid volume 429 is less than first retained fluid volume 427. After the negative pressure therapy cycle illustrated by bar 412, a third fluid volume 430 is recovered. Third fluid volume 430 is greater than first fluid volume 426 and second fluid volume 428, and is less than the volume of fluid instilled during instillation cycle 410. The remainder of the fluid volume instilled during instillation cycle 410 is retained at the tissue site by tissue interface 114, as illustrated by third retention volume 431. Third retained fluid volume 431 is less than first retained fluid volume 427 and second retained fluid volume 431. After the negative pressure therapy cycle illustrated by bar 416, a fourth fluid volume 432 is recovered. The fourth fluid volume 430 is greater than the first fluid volume 426, the second fluid volume 428, and the third fluid volume 430, and is equal to the volume of fluid instilled during the instillation cycle of the bar 414. The fourth fluid volume 432, which is equal to the amount of fluid instilled at the bar 414, indicates that the dressing 104 and the tissue site have reached saturation and the instillation volume is optimized. In each subsequent cycle, the volume of fluid recovered (e.g., the fifth fluid volume 434 recovered during the negative pressure cycle 420) is substantially equal to the volume of fluid instilled before the negative pressure cycle (e.g., the volume of fluid instilled at the bar 418).

[0074] Figure 5 is exemplified by Figure 1Flowchart of another optimization routine or operational steps of method 500 performed by system 100 for determining an optimal fluid instillation volume for a tissue site. In some embodiments, method 500 may use a bolus-lead reduction process or a bolus-lead reduction instillation profile. Method 500 begins at block 502, where system 100 receives an initial instillation volume (IIV). In some embodiments, method 500 is responsive to method 200 receiving the initial instillation volume (IIV). For example, controller 108 may receive an initial instillation volume (IIV) from Figure 2 The method 200 receives input to set an initial instillation volume (IIV) based on a visual estimate of the size of the tissue site. In some embodiments, the clinician can input that a small pre-packaged dressing is used, and the controller 108 can set the initial instillation volume (IIV) to the expected volume associated with the use of the small dressing. Similarly, if a medium, large, or extra-large pre-packaged dressing is used, the controller 108 can set the initial instillation volume (IIV) to the expected volume associated with the use of the medium, large, or extra-large pre-packaged dressing. The method 500 continues at box 504, where the initial instillation volume (IIV) is stored. For example, the controller 108 can store a value associated with the initial instillation volume (IIV).

[0075] At frame 506, the initial instillation volume (IIV) is instilled into the tissue site. For example, the controller 108 can actuate the positive pressure source 120 and the regulator 122 to instill the initial instillation volume (IIV) into the dressing 104. In some embodiments, a dwell operation can be performed after the initial instillation volume (IIV) is instilled into the tissue site. In other embodiments, the dwell operation is not performed. The method 500 continues at frame 508, where a value associated with the volume of the fluid instilled into the tissue site is stored. For example, the sensor 128 can provide a signal to the controller 108, which indicates a value associated with the volume of the fluid instilled into the tissue site, i.e., the instillation volume (IV). The controller 108 can store a value associated with the volume of the fluid instilled into the tissue site, i.e., the instillation volume (IV).

[0076] The method 500 continues at frame 510, where fluid is aspirated from the tissue site in a negative pressure therapy cycle and a volume of fluid, i.e., a recovery volume (RV), is recovered. For example, the controller 108 can operate the negative pressure source 102 to aspirate fluid from the tissue site through the dressing 104 and into the tank 106. The method 500 continues at frame 512, where the method 500 measures and stores a volume of fluid associated with the recovery volume (RV). For example, the sensor 126 can generate a signal indicating a value of the volume of fluid recovered from the tissue site (the recovery volume (RV)). The controller 108 can receive and store a value associated with the signal generated by the sensor 126.

[0077] The method continues at box 514, where the method 500 compares the instillation volume (IV) with the recovery volume (RV). For example, the controller 108 can compare the value associated with the instillation volume (IV) with the value associated with the recovery volume (RV). At box 516, the method 500 determines whether the recovery volume (RV) is greater than the instillation volume (IV). For example, the controller 108 compares the value associated with the recovery volume (RV) with the value associated with the instillation volume (IV). If the recovery volume (RV) is greater than the instillation volume (IV), the method continues on the "yes" path to box 518, where the method 500 reports an error and the method 500 ends. For example, the controller 108 can send an alarm signal, such as an audible alarm, a tactile alarm, or a visual alarm.

[0078] At box 516, if the recovery volume (RV) is not greater than the instillation volume (IV), the method proceeds to decision box 520 along the "no" path, wherein the method 500 determines whether the recovery volume (RV) is less than the instillation volume (IV). If the recovery volume (RV) is less than the instillation volume (IV), the method 500 continues along the "yes" path to box 522, wherein the method 500 iterates the volume of fluid to be instilled by setting the initial instillation volume (IIV) to a predetermined amount less than the instillation volume (IV). For example, the controller 108 can reduce the initial instillation volume (IIV) to a predetermined amount less than the instillation volume (IV). In some embodiments, iteration can be selected in response to the relationship between the volume of the fluid instilled and the volume of the recovered fluid. For example, if the volume of the recovered fluid is higher than a threshold percentage of the volume of the fluid instilled, the system can determine that a push of fluid is recovered. In response, the system can increase the reduction of the subsequent instillation volume. The method continues to box 506, wherein the method 500 repeats.

[0079] At block 520, if the recovery volume (RV) is not less than the instillation volume (IV), the method 500 continues on a "NO" path to block 524, where the method 500 reports optimization and continues to block 526, where the method 500 begins negative pressure wound therapy instillation. For example, the controller 108 reports that the dressing 104 is at the optimal instillation volume, such as with an audible indicator, a tactile indicator, or a visual indicator, and the controller 108 begins negative pressure wound therapy instillation.

[0080] Figure 6 It is an example based on Figure 5 Combined bar and line graph of optimal fluid instillation volumes for each procedure step. Figure 6, the y-axis represents the volume of fluid, and the x-axis represents time. In each cycle through method 500, a reduced volume is instilled into the tissue site. For example, in each subsequent instillation cycle of method 500, system 100 delivers a smaller volume of fluid. As illustrated by bars 602, 606, 610, 614 and 616, a smaller volume of fluid is delivered through each iteration of method 500, i.e., the instillation volume (IV) is reduced. Each negative pressure therapy cycle will have approximately the same length. For example, in each negative pressure therapy cycle of method 500, system 100 will operate negative pressure source 102 for approximately the same length of time. As illustrated by bars 604, 608, 612, 616 and 620, the negative pressure therapy cycle has approximately the same length. In each negative pressure therapy cycle, system 100 will recycle different amounts of fluid. When the fluid is instilled into the tissue site, the tissue interface 114 can absorb a certain amount of fluid. Thus, the amount of fluid recovered during a negative pressure therapy cycle will be the amount of fluid delivered minus the amount of fluid absorbed by the tissue interface 114.

[0081] Line 622 illustrates the aggregate volume of fluid retained by a tissue site (e.g., tissue interface 114) after each negative pressure therapy cycle. The aggregate 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 instilled. In the illustrated embodiment, after the negative pressure therapy cycle illustrated by bar 604, a first fluid volume 626 is recovered. The first fluid volume 626 is less than the volume of fluid instilled during the instillation cycle of bar 602. The remainder of the total volume of fluid instilled during the instillation cycle 602 is retained at the tissue site by the tissue interface 114, as illustrated by the first retained fluid volume 627. As illustrated by Figure 6 As illustrated, the first fluid volume 626 can be considered large. In response, the subsequent drip volume can be reduced. For example, the fluid volume dripped during the drip cycle of bar 606 is less than the fluid volume dripped during the drip cycle 602. Line 622 indicates at point 640 that the aggregate volume of the retained fluid is substantially equal to the first retained fluid volume 627.

[0082] After the negative pressure therapy cycle illustrated by bar 608, a second fluid volume 628 is recovered. The second fluid volume 628 is again less than the volume of fluid instilled during the instillation cycle 606; however, the second fluid volume 628 may represent a greater proportion of the volume of fluid instilled during the instillation cycle 606. The remainder of the total volume of fluid instilled during the instillation cycle 606 is retained at the tissue site by the tissue interface 114, as illustrated by the second retained fluid volume 629. Line 622 indicates at point 642 that the aggregate volume of fluid retained is substantially equal to the first retained fluid volume 627 and the second retained fluid volume 629.

[0083] After the negative pressure therapy cycle illustrated by bar 612, a third fluid volume 630 is recovered. The third fluid volume 630 is again less than the volume of fluid instilled during the instillation cycle 610; however, the third fluid volume 630 may represent a greater proportion of the volume of fluid instilled during the instillation cycle 610. The remainder of the total volume of fluid instilled during the instillation cycle 610 is retained at the tissue site by the tissue interface 114, as illustrated by the third retained fluid volume 631. Line 622 indicates at point 644 that the aggregate volume of retained fluid is substantially equal to the first retained fluid volume 627, the second retained fluid volume 629, and the third retained fluid volume 631. Line 622 is equal to the amount of fluid instilled at bar 602 as represented at point 644, indicating that saturation has been achieved with the dressing 104 and the tissue site and the instillation volume is optimized. Subsequent drip cycles 614 and 618 and corresponding negative pressure cycles 616 and 620 recover a volume of fluid 632 and 634 that is substantially equal to the volume of fluid dripped in the previous drip cycle. In response, line 622 remains substantially horizontal, further indicating that saturation of the tissue site and dressing 104 is achieved.

[0084] Figure 7 is exemplified by Figure 1 Flowchart of the operational steps of an optimization routine or method 700 performed by the system 100 for determining an optimal fluid instillation volume for a tissue site. In some embodiments, the method 700 may use a step-wise increase process or a step-wise increase instillation profile. The method 700 begins at block 702, where the system 100 receives an initial instillation volume (IIV) in response to the method 200. For example, the controller 108 may receive an initial instillation volume (IIV) from Figure 2 The method 200 receives input to set an initial instillation volume (IIV) based on a visual estimate of the size of the tissue site. In some embodiments, the clinician can input that a small pre-packaged dressing is used, and the controller 108 can set the initial instillation 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 is used, the controller 108 can set the initial instillation volume (IIV) to the expected volume associated with the use of a medium, large, or extra-large pre-packaged dressing. The method 700 continues at box 704, where the initial instillation volume (IIV) is stored. For example, the controller 108 can store a value associated with the initial instillation volume (IIV).

[0085] At frame 706, the initial instillation volume (IIV) is instilled into the tissue site. For example, the controller 108 can actuate the positive pressure source 120 and the regulator 122 to instill the initial instillation volume (IIV) into the dressing 104. In some embodiments, a dwell operation can be performed after the instillation volume is instilled into the tissue site. In other embodiments, the dwell operation is not performed. The method 700 continues at frame 708, wherein a value associated with the volume of the fluid instilled, i.e., the instillation volume (IV), is stored. For example, the regulator 122 or the fluid source 118 can provide a signal to the controller 108, which indicates a value associated with the volume of the fluid instilled into the tissue site, i.e., the instillation volume (IV). The controller 108 can store a value associated with the volume of the fluid instilled into the tissue site, i.e., the instillation volume (IV).

[0086] The method 700 continues at frame 710, where fluid is aspirated 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 aspirate fluid from the tissue site through the dressing 104 and into the tank 106. The method 700 continues at frame 712, where the method 700 measures and stores the volume of fluid associated with the volume of recovered fluid, i.e., the recovery volume (RV). For example, the tank 106 can generate a signal indicating the value of the volume of fluid recovered from the tissue site (recovery volume (RV)). The controller 108 can receive and store a value associated with the signal generated by the tank 106.

[0087] The method continues at box 714, where the method 700 compares the instillation volume (IV) with the recovery volume (RV). For example, the controller 108 can compare the value associated with the instillation volume (IV) with the value associated with the recovery volume (RV). At box 716, the method 700 determines whether the recovery volume (RV) is greater than the instillation volume (IV). For example, the controller 108 compares the value associated with the recovery volume (RV) with the value associated with the instillation volume (IV). If the recovery volume (RV) is greater than the instillation volume (IV), the method continues on the "yes" path to box 718, where the method 700 reports an error and the method 700 ends. For example, the controller 108 can send an alarm signal, such as an audible alarm, a tactile alarm, or a visual alarm.

[0088] At box 716, if the recovery volume (RV) is not greater than the instillation volume (IV), the method continues to decision box 720, wherein the method 700 determines whether the recovery volume (RV) is less than the instillation volume (IV). If the recovery volume (RV) is less than the instillation volume (IV), the method 700 continues to box 722 along the "yes" path, wherein the method 700 iterates the volume of fluid to be instilled by setting the initial instillation volume (IIV) to a predetermined amount greater than the instillation volume (IV). For example, the controller 108 can increase the initial instillation volume (IIV) by a predetermined amount. In some embodiments, iteration can be selected in response to the relationship between the volume of the fluid instilled and the volume of the recovered fluid. For example, if the volume of the recovered fluid is higher than the threshold percentage of the volume of the instilled fluid, the system can determine that the fluid of a push is recovered. In response, the system can increase the reduction of the subsequent instillation volume. In another example, if the volume of the recovered fluid is lower than the threshold percentage of the volume of the instilled fluid, the system can determine that the fluid instilled is insufficient. In response, the system may increase subsequent infusion volumes.The method continues to block 706 where the method 700 repeats.

[0089] At block 720, if the recovery volume (RV) is not less than the instillation volume (IV), the method 700 continues on a "NO" path to block 720, where the method 700 reports optimization and continues to block 722, where the method 700 starts negative pressure wound therapy instillation. For example, the controller 108 reports that the dressing 104 is at the optimal instillation volume, such as with an audible indicator, a tactile indicator, or a visual indicator, and the controller 108 starts negative pressure wound therapy instillation.

[0090] Figure 8 It is an example based on Figure 7 Combined bar and line graph of optimal fluid instillation volumes for each procedure step. Figure 8 , the y-axis represents the volume of fluid, and the x-axis represents time. In each cycle through method 700, the detection volume is instilled into the tissue site. For example, in each subsequent instillation cycle of method 700, the system 100 delivers different volumes of fluid until the tissue site and the dressing 104 are saturated. Each negative pressure therapy cycle will have approximately the same length. For example, in each negative pressure therapy cycle of method 700, the system 100 will operate the negative pressure source 102 for approximately the same length of time. As illustrated by bars 804, 808, 812, 816 and 820, the negative pressure therapy cycles have approximately the same length. In each negative pressure therapy cycle, the system 100 will recycle different amounts of fluid. When the fluid is instilled 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 will be the amount of fluid delivered minus the amount of fluid absorbed by the tissue interface 114.

[0091] Line 822 illustrates the aggregate volume of fluid retained by a tissue site (e.g., tissue interface 114) after each negative pressure therapy cycle. The aggregate 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 instilled. In the illustrated embodiment, after the negative pressure therapy cycle illustrated by bar 804, a first fluid volume 824 is recovered. The first fluid volume 824 is less than the volume of fluid instilled during the instillation cycle of bar 802. The remainder of the total volume of fluid instilled during the instillation cycle 802 is retained at the tissue site by the tissue interface 114, as illustrated by the first retained fluid volume 825. As illustrated by Figure 8 As illustrated, the first fluid volume 824 can be considered to be smaller relative to the volume of the fluid being dripped; in response, the subsequent drip volumes can be increased. For example, the volume of fluid dripped during the drip cycle of bar 806 is greater than the volume of fluid dripped during the drip cycle 802. Line 822 indicates at point 834 that the aggregate volume of the retained fluid is substantially equal to the first retained fluid volume 825.

[0092] After the negative pressure therapy cycle illustrated by bar 808, a second fluid volume 826 is recovered. The second fluid volume 826 is again less than the volume of fluid instilled during the instillation cycle 806; however, the second fluid volume 826 may represent a greater proportion of the volume of fluid instilled during the instillation cycle 806. The remainder of the total volume of fluid instilled during the instillation cycle 806 is retained at the tissue site by the tissue interface 114, as illustrated by the second retained fluid volume 827. Line 822 indicates at point 836 that the aggregate volume of retained fluid is substantially equal to the first retained fluid volume 827 and the second retained fluid volume 829. As shown in FIG. Figure 8 As illustrated, second fluid volume 826 can be considered to be larger relative to the volume of the fluid being dripped; in response, the subsequent drip volume can be reduced. For example, the volume of fluid dripped during the drip cycle of strip 810 is less than the volume of fluid dripped during drip cycle 806.

[0093] After the negative pressure therapy cycle illustrated by bar 812, a third fluid volume 828 is recovered. The third fluid volume 828 is again less than the volume of fluid instilled during the instillation cycle 810; however, the third fluid volume 828 may represent a greater proportion of the volume of fluid instilled during the instillation cycle 810. The remainder of the total volume of fluid instilled during the instillation cycle 810 is retained at the tissue site by the tissue interface 114, as illustrated by the third retained fluid volume 829. Line 822 indicates at point 838 that the aggregate volume of fluid retained is substantially equal to the first retained fluid volume 825, the second retained fluid volume 827, and the third retained fluid volume 829. Line 822 is equal to the amount of fluid instilled at bar 802 as represented at point 838, indicating that saturation has been achieved with the dressing 104 and the tissue site and the instillation volume is optimized. Subsequent drip cycles 814 and 818 and corresponding negative pressure cycles 816 and 820 recover a volume of fluid 830 and 832 that is substantially equal to the volume of fluid dripped in the previous drip cycle. In response, line 822 remains substantially horizontal, further indicating that saturation of the tissue site and dressing 104 is achieved.

[0094] The systems, devices, and methods described herein may provide significant advantages. For example, a treatment system 100 that provides a method for determining a state of equilibrium at a tissue site. By determining the state of equilibrium at a tissue site, the treatment system 100 may optimize the delivery of an instillation solution, thereby reducing the risk of overfilling or underfilling a tissue site. The optimization may also reduce the time demands of a clinician and improve the ease of use of a system that provides instillation and negative pressure wound therapy, thereby leading to improved patient outcomes and wider adoption of beneficial treatments.

[0095] Although shown in several exemplary embodiments, it will be appreciated by those skilled in the art that the systems, apparatuses, and methods described herein are susceptible to various changes and modifications, and that these changes and modifications fall within the scope of the appended claims. In addition, unless the context clearly requires otherwise, descriptions of various alternatives using terms such as "or" do not need to be mutually exclusive, and unless the context clearly requires otherwise, the indefinite article "one" or "an" does not limit the subject matter to a single instance. For the purpose of sale, manufacture, assembly, or use, components may also be combined or removed in various configurations. For example, in some configurations, the dressing 104, the container 115, or both may be removed or separated from other components for manufacture or sale. In other example configurations, the controller 108 may also be manufactured, configured, assembled, or sold independently of the other components.

[0096] The appended claims set forth novel and inventive aspects of the subject matter described above, but the claims may also include additional subject matter not specifically described in detail. For example, certain features, elements, or aspects may be omitted from the claims if it is not necessary to distinguish novel and inventive features from features known to those of ordinary skill in the art. Features, elements, and aspects described in the context of some embodiments may also be omitted, combined, or replaced by alternative features that serve the same, equivalent, or similar purposes without departing from the scope of the invention as defined by the appended claims.

Claims

1. A system for treating a tissue site, the system comprising: an instillation source configured to provide an instillation solution to the tissue site; a negative pressure source configured to draw fluid from the tissue site to generate negative pressure at the tissue site; a controller communicatively coupled to the instillation source and the negative pressure source, the controller being configured to: actuating the infusion source; as well as actuating the negative pressure source; as well as A sensor is communicatively coupled to the controller and operatively coupled to the instillation source and the negative pressure source, the sensor being configured to generate a signal indicative of an amount of fluid delivered to and an amount of fluid recovered from the tissue site. 2 . The system of claim 1 , wherein the controller is configured to actuate the instillation source to saturate the tissue site.

3. The system of claim 2, wherein saturating comprises withdrawing the same volume of fluid from the tissue site as that delivered by the instillation source. The system of claim 1 , wherein the controller is configured to determine a saturation level of the tissue site.

5. The system of claim 4, wherein the controller actuates a uniform drip distribution.

6. The system of claim 5, wherein the uniform drip distribution comprises: 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 instillation volume (IV), the controller determines that saturation is achieved and actuates the instillation source and the negative pressure source to provide instillation therapy and negative pressure therapy; as well as If the recovery volume (RV) is less than about the infusion volume (IV), the controller determines that saturation has not been achieved and the controller operates the infusion source to provide the infusion volume (IV).

7. The system of claim 4, wherein the controller operates the drip source using a step-up drip profile.

8. The system of claim 7, wherein the step-wise increasing infusion profile comprises: 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 instillation volume (IV), the controller determines that saturation is achieved and actuates the instillation source and the negative pressure source to provide instillation therapy and negative pressure therapy; as well as If the recovery volume (RV) is less than about the instillation volume (IV), the controller determines that saturation has not been achieved and increases the instillation volume (IV).

9. The system of claim 4, wherein the controller operates the infusion source using a bolus-guided infusion profile.

10. The system of claim 9, wherein the bolus-guided drip profile comprises: 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 instillation volume (IV), the controller determines that saturation is achieved and actuates the instillation source and the negative pressure source to provide instillation therapy and negative pressure therapy; as well as If the recovery volume (RV) is less than about the instillation volume (IV), the controller determines that saturation has not been achieved and decreases the instillation volume (IV).

11. The system of claim 1, wherein the sensor comprises a plurality of sensors configured to determine the volume of fluid instilled and the volume of fluid recovered.

12. The system of claim 11, wherein the plurality of sensors include strain gauges and the controller determines the weight of the volume of fluid instilled and the weight of the volume of fluid recovered.

13. The system of claim 11, wherein the plurality of sensors include Hall effect sensors and the controller determines the height of the volume of fluid instilled and the height of the volume of fluid recovered.

14. The system of claim 11, wherein the plurality of sensors comprises optical sensors.

15. A method for determining saturation of a tissue site, the method comprising: receiving, with a controller, a signal indicative of an infusion volume (IV); receiving, with the controller, a signal indicative of a recovery volume (RV); comparing, using the controller, the infusion volume (IV) to the recovery volume (RV); as well as In response to comparing the instillation volume (IV) to the recovery volume (RV), a saturation state of the tissue site is determined.

16. The method of claim 15, wherein determining the saturation state of the tissue region comprises: If the recovery volume (RV) is greater than the infusion volume (IV), the controller generates an alarm signal; The controller determines that saturation is achieved if the recovery volume (RV) is approximately equal to the instillation volume (IV); and If the recovery volume (RV) is less than about the instillation volume (IV), the controller determines that saturation has not been achieved.

17. The method of claim 15, wherein determining a saturation state of the tissue site comprises: If the recovery volume (RV) is greater than the infusion volume (IV), the controller generates an alarm signal; The controller determines that saturation is achieved if the recovery volume (RV) is approximately equal to the instillation volume (IV); and If the recovery volume (RV) is less than about the instillation volume (IV), the controller determines that saturation has not been achieved and increases the instillation volume (IV).

18. The method of claim 15, wherein determining a saturation state of the tissue site comprises: If the recovery volume (RV) is greater than the infusion volume (IV), the controller generates an alarm signal; The controller determines that saturation is achieved if the recovery volume (RV) is approximately equal to the instillation volume (IV); and If the recovery volume (RV) is less than about the instillation volume (IV), the controller determines that saturation has not been achieved and decreases the instillation volume (IV).

19. A system for treating a tissue site, the system comprising: a controller communicatively coupled to the infusion source and the negative pressure source, the controller being configured to: actuating the infusion source to provide infusion therapy; as well as actuating the negative pressure source to provide negative pressure therapy; an instillation sensor communicatively coupled to the controller and configured to generate a signal indicative of an instillation volume (IV); as well as A recovery volume (RV) sensor is communicatively coupled to the controller and configured to generate a signal indicative of a recovery volume (RV).

20. The system of claim 19, wherein the controller actuates a uniform drip distribution.

21. The system of claim 20, wherein the uniform drip distribution comprises: the controller operating the infusion source to provide the infusion volume (IV); The controller operates the negative pressure source to recover the 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 instillation volume (IV), the controller determines that saturation is achieved and actuates the instillation source and the negative pressure source to provide instillation therapy and negative pressure therapy; as well as If the recovery volume (RV) is less than about the infusion volume (IV), the controller determines that saturation has not been achieved and the controller operates the infusion source to provide the infusion volume (IV).

22. The system of claim 19, wherein the controller actuates a step-wise increasing drip profile.

23. The system of claim 22, wherein the step-wise increasing infusion profile comprises: the controller operating the infusion source to provide the infusion volume (IV); The controller operates the negative pressure source to recover the 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 instillation volume (IV), the controller determines that saturation is achieved and actuates the instillation source and the negative pressure source to provide instillation therapy and negative pressure therapy; as well as If the recovery volume (RV) is less than about the instillation volume (IV), the controller determines that saturation has not been achieved and increases the instillation volume (IV).

24. The system of claim 19, wherein the controller actuates a bolus-directed drip profile.

25. The system of claim 24, wherein the bolus-guided drip profile comprises: the controller operating the infusion source to provide the infusion volume (IV); The controller operates the negative pressure source to recover the 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 instillation volume (IV), the controller determines that saturation is achieved and actuates the instillation source and the negative pressure source to provide instillation therapy and negative pressure therapy; as well as If the recovery volume (RV) is less than about the instillation volume (IV), the controller determines that saturation has not been achieved and decreases the instillation volume (IV).

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

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