Patent Description:
Negative pressure wound therapy (NPWT) is a type of wound therapy that involves applying a negative pressure to a wound site to promote wound healing. Some wound treatment systems apply negative pressure to a wound using a pneumatic pump to generate the negative pressure and flow required. Recent advancements in wound healing with NPWT involve applying topical fluids to wounds to work in combination with NPWT. However, it can be difficult to determine the appropriate volume of instillation fluid to deliver to the wound. Additionally, it can be difficult to accurately monitor and track healing progression over time.

<CIT> discloses a negative pressure treatment system with a testing procedure which applies reduced pressure stimulus and monitors dynamic changes.

<CIT> discloses a method for measuring the volume of a wound by measuring a volume of air extracted from the wound.

<CIT> discloses a wound therapy system with a peristaltic pump for instillation therapy.

<CIT> discloses a wound treatment system using dynamic variation of reduced pressure.

The invention is defined by the appended claims in which there is required a wound therapy system comprising: a negative pressure circuit configured to apply negative pressure to a wound; a pump fluidly coupled to the negative pressure circuit and configured to produce a negative pressure at the wound or within the negative pressure circuit; a pressure sensor configured to measure the negative pressure within the negative pressure circuit or at the wound; and a controller configured to: perform a testing procedure comprising a first drawdown period, a leak rate determination period, a vent period, and a second drawdown period; receive one or more pressure measurements of the pressure sensor over the leak rate determination period to determine a leak rate parameter; monitor an amount of elapsed time over the second drawdown period to determine a drawdown parameter; and estimate a volume of the wound based on the leak rate parameter and the drawdown parameter.

A selection of optional features is set out in the dependent claims.

Referring generally to the FIGURES, a wound therapy system with fluid instillation and removal and components thereof are shown, according to various exemplary embodiments. The wound therapy system may include a therapy device and a wound dressing. The therapy device may include an instillation fluid canister, a removed fluid canister, a valve, a pneumatic pump, an instillation pump, and a controller. The wound dressing can be applied to a patient's skin surrounding a wound. The therapy device can be configured to deliver instillation fluid to the wound and provide negative pressure wound therapy (NPWT) by maintaining the wound at negative pressure. Components of the wound therapy device, the wound dressing, and/or the wound form a negative pressure circuit.

The controller can estimate the volume of the wound based on the leakage rate of the wound dressing and an amount of time it takes the pneumatic pump to achieve a predetermined negative pressure. The controller can cause the therapy device to perform a testing procedure (e.g., a pressure testing procedure) to determine the leakage rate of the wound dressing and the amount of time it takes the pneumatic pump to achieve the predetermined negative pressure. The leakage rate of the wound dressing and the amount of time it takes the pneumatic pump to achieve the predetermined negative pressure at the wound are the observed parameters. For example, the controller can apply the observed parameters as inputs to a model that defines a relationship between the observed parameters and the volume of the negative pressure circuit and/or the volume of the wound. The model may include a polynomial approximation model, a neural network model, or any other model that relates the observed parameters to the volume of the negative pressure circuit and/or the volume of the wound. In some embodiments, the model is a pre-existing model stored in the controller by the manufacturer of the therapy device. In other embodiments, the controller can generate the model on-site by performing a training procedure.

The training procedure may be the same as the pressure testing procedure with the exception that the therapy device is connected to a training circuit having a known volume. For example, the wound dressing can be applied to a test device having a known volume rather than to a patient's skin surrounding a wound. The controller can perform the training procedure on various training circuits having various known volumes and may observe the parameters (i.e., the leakage rate and the amount of time to achieve the predetermined negative pressure) of each training circuit. Each of the known volumes may result in different observed parameters. The controller can then associate the known volume of each training circuit with the corresponding parameters. In some embodiments, the controller uses the observed parameters and the known volume of the training circuits to generate the model that defines a relationship between the observed parameters and the volume of the training circuit. The model can then be stored in the therapy device and used to estimate the volume of a wound, as previously described.

In some embodiments, the controller is configured to execute the pressure testing procedure, observe the parameters, and estimate the wound volume at a plurality of times during wound treatment. The controller can then determine healing progression based on changes in the wound volume during wound treatment. In some embodiments, the controller is configured to determine a volume of instillation fluid to deliver to the wound based on the estimated wound volume. The volume of instillation fluid to deliver may be a predetermined percentage of the volume of the wound (e.g., <NUM>%, <NUM>%, <NUM>%, etc.). The controller can then operate the instillation pump to deliver the determined volume of instillation fluid to the wound. These and other features of the wound therapy system are described in detail below.

Referring now to <FIG>, a negative pressure wound therapy (NPWT) system <NUM> is shown, according to an exemplary embodiment. NPWT system <NUM> is shown to include a therapy device <NUM> fluidly connected to a wound dressing <NUM> via tubing <NUM> and <NUM>. Wound dressing <NUM> may be adhered or sealed to a patient's skin <NUM> surrounding a wound <NUM>. Several examples of wound dressings <NUM> which can be used in combination with NPWT system <NUM> are described in detail in <CIT>, <CIT>, and <CIT>.

Therapy device <NUM> can be configured to provide negative pressure wound therapy by reducing the pressure at wound <NUM>. Therapy device <NUM> can draw a vacuum at wound <NUM> (relative to atmospheric pressure) by removing wound exudate, air, and other fluids from wound <NUM>. Wound exudate may include fluid that filters from a patient's circulatory system into lesions or areas of inflammation. For example, wound exudate may include water and dissolved solutes such as blood, plasma proteins, white blood cells, platelets, and red blood cells. Other fluids removed from wound <NUM> may include instillation fluid <NUM> previously delivered to wound <NUM>. Instillation fluid <NUM> can include, for example, a cleansing fluid, a prescribed fluid, a medicated fluid, an antibiotic fluid, or any other type of fluid which can be delivered to wound <NUM> during wound treatment. Instillation fluid <NUM> may be held in an instillation fluid canister <NUM> and controllably dispensed to wound <NUM> via instillation fluid tubing <NUM>. In some embodiments, instillation fluid canister <NUM> is detachable from therapy device <NUM> to allow canister <NUM> to be refilled and replaced as needed.

The fluids <NUM> removed from wound <NUM> pass through removed fluid tubing <NUM> and are collected in removed fluid canister <NUM>. Removed fluid canister <NUM> may be a component of therapy device <NUM> configured to collect wound exudate and other fluids <NUM> removed from wound <NUM>. In some embodiments, removed fluid canister <NUM> is detachable from therapy device <NUM> to allow canister <NUM> to be emptied and replaced as needed. A lower portion of canister <NUM> may be filled with wound exudate and other fluids <NUM> removed from wound <NUM>, whereas an upper portion of canister <NUM> may be filled with air. Therapy device <NUM> can be configured to draw a vacuum within canister <NUM> by pumping air out of canister <NUM>. The reduced pressure within canister <NUM> can be translated to wound dressing <NUM> and wound <NUM> via tubing <NUM> such that wound dressing <NUM> and wound <NUM> are maintained at the same pressure as canister <NUM>.

Referring particularly to <FIG>, block diagrams illustrating therapy device <NUM> in greater detail are shown, according to an exemplary embodiment. Therapy device <NUM> is shown to include a pneumatic pump <NUM>, an instillation pump <NUM>, a valve <NUM>, a filter <NUM>, and a controller <NUM>. Pneumatic pump <NUM> can be fluidly coupled to removed fluid canister <NUM> (e.g., via conduit <NUM>) and can be configured to draw a vacuum within canister <NUM> by pumping air out of canister <NUM>. In some embodiments, pneumatic pump <NUM> is configured to operate in both a forward direction and a reverse direction. For example, pneumatic pump <NUM> can operate in the forward direction to pump air out of canister <NUM> and decrease the pressure within canister <NUM>. Pneumatic pump <NUM> can operate in the reverse direction to pump air into canister <NUM> and increase the pressure within canister <NUM>. Pneumatic pump <NUM> can be controlled by controller <NUM>, described in greater detail below.

Similarly, instillation pump <NUM> can be fluidly coupled to instillation fluid canister <NUM> via tubing <NUM> and fluidly coupled to wound dressing <NUM> via tubing <NUM>. Instillation pump <NUM> can be operated to deliver instillation fluid <NUM> to wound dressing <NUM> and wound <NUM> by pumping instillation fluid <NUM> through tubing <NUM> and tubing <NUM>, as shown in <FIG>. Instillation pump <NUM> can be controlled by controller <NUM>, described in greater detail below.

Filter <NUM> can be positioned between removed fluid canister <NUM> and pneumatic pump <NUM> (e.g., along conduit <NUM>) such that the air pumped out of canister <NUM> passes through filter <NUM>. Filter <NUM> can be configured to prevent liquid or solid particles from entering conduit <NUM> and reaching pneumatic pump <NUM>. Filter <NUM> may include, for example, a bacterial filter that is hydrophobic and/or lipophilic such that aqueous and/or oily liquids will bead on the surface of filter <NUM>. Pneumatic pump <NUM> can be configured to provide sufficient airflow through filter <NUM> that the pressure drop across filter <NUM> is not substantial (e.g., such that the pressure drop will not substantially interfere with the application of negative pressure to wound <NUM> from therapy device <NUM>).

In some embodiments, therapy device <NUM> operates a valve <NUM> to controllably vent the negative pressure circuit, as shown in <FIG>. Valve <NUM> can be fluidly connected with pneumatic pump <NUM> and filter <NUM> via conduit <NUM>. In some embodiments, valve <NUM> is configured to control airflow between conduit <NUM> and the environment around therapy device <NUM>. For example, valve <NUM> can be opened to allow airflow into conduit <NUM> via vent <NUM> and conduit <NUM>, and closed to prevent airflow into conduit <NUM> via vent <NUM> and conduit <NUM>. Valve <NUM> can be opened and closed by controller <NUM>, described in greater detail below. When valve <NUM> is closed, pneumatic pump <NUM> can draw a vacuum within a negative pressure circuit by causing airflow through filter <NUM> in a first direction, as shown in <FIG>. The negative pressure circuit may include any component of system <NUM> that can be maintained at a negative pressure when performing negative pressure wound therapy (e.g., conduit <NUM>, removed fluid canister <NUM>, tubing <NUM>, wound dressing <NUM>, and/or wound <NUM>). For example, the negative pressure circuit may include conduit <NUM>, removed fluid canister <NUM>, tubing <NUM>, wound dressing <NUM>, and/or wound <NUM>. When valve <NUM> is open, airflow from the environment around therapy device <NUM> may enter conduit <NUM> via vent <NUM> and conduit <NUM> and fill the vacuum within the negative pressure circuit. The airflow from conduit <NUM> into canister <NUM> and other volumes within the negative pressure circuit may pass through filter <NUM> in a second direction, opposite the first direction, as shown in <FIG>.

In some embodiments, therapy device <NUM> vents the negative pressure circuit via an orifice <NUM>, as shown in <FIG>. Orifice <NUM> may be a small opening in conduit <NUM> or any other component of the negative pressure circuit (e.g., removed fluid canister <NUM>, tubing <NUM>, tubing <NUM>, wound dressing <NUM>, etc.) and may allow air to leak into the negative pressure circuit at a known rate. In some embodiments, therapy device <NUM> vents the negative pressure circuit via orifice <NUM> rather than operating valve <NUM>. Valve <NUM> can be omitted from therapy device <NUM> for any embodiment in which orifice <NUM> is included. The rate at which air leaks into the negative pressure circuit via orifice <NUM> may be substantially constant or may vary as a function of the negative pressure, depending on the geometry of orifice <NUM>. For embodiments in which the leak rate via orifice <NUM> is variable, controller <NUM> can use a stored relationship between negative pressure and leak rate to calculate the leak rate via orifice <NUM> based measurements of the negative pressure. Regardless of whether the leak rate via orifice <NUM> is substantially constant or variable, the leakage of air into the negative pressure circuit via orifice <NUM> can be used to generate a pressure decay curve for use in estimating volume <NUM> (see <FIG>) of wound <NUM>.

In some embodiments, therapy device <NUM> includes a variety of sensors. For example, therapy device <NUM> is shown to include a pressure sensor <NUM> configured to measure the pressure within canister <NUM> and/or the pressure at wound dressing <NUM> or wound <NUM>. In some embodiments, therapy device <NUM> includes a pressure sensor <NUM> configured to measure the pressure within tubing <NUM>. Tubing <NUM> may be connected to wound dressing <NUM> and may be dedicated to measuring the pressure at wound dressing <NUM> or wound <NUM> without having a secondary function such as channeling installation fluid <NUM> or wound exudate. In various embodiments, tubing <NUM>, <NUM>, and <NUM> may be physically separate tubes or separate lumens within a single tube that connects therapy device <NUM> to wound dressing <NUM>. Accordingly, tubing <NUM> may be described as a negative pressure lumen that functions apply negative pressure wound dressing <NUM> or wound <NUM>, whereas tubing <NUM> may be described as a sensing lumen configured to sense the pressure at wound dressing <NUM> or wound <NUM>. Pressure sensors <NUM> and <NUM> can be located within therapy device <NUM>, positioned at any location along tubing <NUM>, <NUM>, and <NUM>, or located at wound dressing <NUM> in various embodiments. Pressure measurements recorded by pressure sensors <NUM> and/or <NUM> can be communicated to controller <NUM>. Controller <NUM> use the pressure measurements as inputs to various pressure testing operations and control operations performed by controller <NUM> (described in greater detail with reference to <FIG>).

Controller <NUM> can be configured to operate pneumatic pump <NUM>, instillation pump <NUM>, valve <NUM>, and/or other controllable components of therapy device <NUM>. In some embodiments, controller <NUM> performs a pressure testing procedure by applying a pressure stimulus to the negative pressure circuit. For example, controller <NUM> may instruct valve <NUM> to close and operate pneumatic pump <NUM> to establish negative pressure within the negative pressure circuit. Once the negative pressure has been established, controller <NUM> may deactivate pneumatic pump <NUM>. Controller <NUM> may cause valve <NUM> to open for a predetermined amount of time and then close after the predetermined amount of time has elapsed. Controller <NUM> may observe a dynamic pressure response of the negative pressure circuit to the pressure stimulus using pressure measurements recorded by pressure sensors <NUM> and/or <NUM>. The dynamic pressure response may be characterized by a variety of parameters including, for example, a drawdown time parameter αtime and a leak rate parameter αleak.

Controller <NUM> can estimate volume <NUM> of wound <NUM> based on the observed dynamic pressure response. For example, controller <NUM> can apply the observed parameters as inputs to a model that defines a relationship between the observed parameters and the volume of the negative pressure circuit and/or volume <NUM> of wound <NUM>. The model may include a polynomial approximation model, a neural network model, or any other model that relates the observed parameters to the volume of the negative pressure circuit and/or volume <NUM> of wound <NUM>. In some embodiments, the model is a pre-existing model stored in controller <NUM> by the manufacturer of therapy device <NUM>. In other embodiments, controller <NUM> can generate the model on-site by performing a training procedure.

The training procedure may be the same as the pressure testing procedure with the exception that therapy device <NUM> is connected to a training circuit having a known volume. For example, wound dressing <NUM> can be applied to a test device having a known volume rather than to a patient's skin <NUM> surrounding wound <NUM>. Controller <NUM> can apply the pressure stimulus to various training circuits having various known volumes and may observe the dynamic pressure response of each training circuit. Each of the known volumes may result in a different dynamic pressure response to the pressure stimulus. Controller <NUM> can then associate the known volume of each training circuit with the corresponding dynamic pressure response. In some embodiments, controller <NUM> uses the dynamic pressure responses of the training circuits to generate the model that defines a relationship between the observed parameters of the dynamic pressure response (e.g., depth of purge, rebound, delta, leak rate, etc.) and the volume of the training circuit. The model can then be stored in controller <NUM> and used to estimate the volume of a wound <NUM>, as previously described. In some embodiments, controller <NUM> determines one or more sets of values of the drawdown time parameter αtime and the leak rate parameter αleak, where each set of the drawdown time parameter αtime and the leak rate parameter αtime corresponds to a known volume <NUM>. In some embodiments, controller <NUM> uses the one or more sets of values to generate the model.

In some embodiments, controller <NUM> is configured to execute the pressure testing procedure, observe the dynamic pressure response, and estimate volume <NUM> of wound <NUM> at a plurality of times during wound treatment. Controller <NUM> can then determine healing progression based on changes in volume <NUM> of wound <NUM> during wound treatment. In some embodiments, controller <NUM> is configured to determine a volume of instillation fluid <NUM> to deliver to wound <NUM> based on the estimated value of volume <NUM>. The volume of instillation fluid <NUM> to deliver may be a predetermined percentage of volume <NUM> of wound <NUM> (e.g., <NUM>%, <NUM>%, <NUM>%, etc.). Controller <NUM> can then operate instillation pump <NUM> to deliver the determined volume of instillation fluid <NUM> to wound <NUM>. These and other features of controller <NUM> are described in greater detail with reference to <FIG>.

In some embodiments, therapy device <NUM> includes a user interface <NUM>. User interface <NUM> may include one or more buttons, dials, sliders, keys, or other input devices configured to receive input from a user. User interface <NUM> may also include one or more display devices (e.g., LEDs, LCD displays, etc.), speakers, tactile feedback devices, or other output devices configured to provide information to a user. In some embodiments, the pressure measurements recorded by pressure sensors <NUM> and/or <NUM> are presented to a user via user interface <NUM>. User interface <NUM> can also display alerts generated by controller <NUM>. For example, controller <NUM> can generate a "no canister" alert if canister <NUM> is not detected.

In some embodiments, therapy device <NUM> includes a data communications interface <NUM> (e.g., a USB port, a wireless transceiver, etc.) configured to receive and transmit data. Communications interface <NUM> may include wired or wireless communications interfaces (e.g., jacks, antennas, transmitters, receivers, transceivers, wire terminals, etc.) for conducting data communications external systems or devices. In various embodiments, the communications may be direct (e.g., local wired or wireless communications) or via a communications network (e.g., a WAN, the Internet, a cellular network, etc.). For example, communications interface <NUM> can include a USB port or an Ethernet card and port for sending and receiving data via an Ethernet-based communications link or network. In another example, communications interface <NUM> can include a Wi-Fi transceiver for communicating via a wireless communications network or cellular or mobile phone communications transceivers.

Referring now to <FIG>, wound <NUM> is shown in greater detail, according to some embodiments. In some embodiments, as the pressure within wound <NUM> decreases due to operation of pneumatic pump <NUM>, one or more leaks are formed. For example, air may enter volume <NUM> of wound <NUM> around corners of wound dressing <NUM>. If tubing <NUM>, <NUM>, and <NUM> are fluidly coupled with volume <NUM> via connectors <NUM>, <NUM>, and <NUM>, respectively, a leak can form at connectors <NUM>, <NUM>, and <NUM>. In some embodiments, if the pressure within inner volume <NUM> of wound <NUM> (e.g., p<NUM>) is less than atmospheric pressure patm (i.e., the pressure of air outside of wound dressing <NUM>), a pressure differential Δpdiff = patm - p<NUM> is formed therebetween. In some embodiments, the pressure differential Δpdiff causes air to enter volume <NUM> and travel through tubing <NUM> via any leaks of wound dressing <NUM> and connectors <NUM>-<NUM>. Leaks may form in any other locations between the interface of wound dressing <NUM> and a patient's skin <NUM>. In some embodiments, leakages of air into volume <NUM> of wound <NUM> is correlated to an increased amount of time which is required for pneumatic pump <NUM> to achieve a negative pressure.

Referring now to <FIG>, a block diagram illustrating controller <NUM> in greater detail is shown, according to an exemplary embodiment. Controller <NUM> is shown to include a processing circuit <NUM> including a processor <NUM> and memory <NUM>. Processor <NUM> may be a general purpose or specific purpose processor, an application specific integrated circuit (ASIC), one or more field programmable gate arrays (FPGAs), a group of processing components, or other suitable processing components. Processor <NUM> is configured to execute computer code or instructions stored in memory <NUM> or received from other computer readable media (e.g., CDROM, network storage, a remote server, etc.).

Memory <NUM> may include one or more devices (e.g., memory units, memory devices, storage devices, etc.) for storing data and/or computer code for completing and/or facilitating the various processes described in the present disclosure. Memory <NUM> may include random access memory (RAM), read-only memory (ROM), hard drive storage, temporary storage, non-volatile memory, flash memory, optical memory, or any other suitable memory for storing software objects and/or computer instructions. Memory <NUM> may include database components, object code components, script components, or any other type of information structure for supporting the various activities and information structures described in the present disclosure. Memory <NUM> may be communicably connected to processor <NUM> via processing circuit <NUM> and may include computer code for executing (e.g., by processor <NUM>) one or more processes described herein. When processor <NUM> executes instructions stored in memory <NUM>, processor <NUM> generally configures controller <NUM> (and more particularly processing circuit <NUM>) to complete such activities.

Controller <NUM> is shown to include a pump controller <NUM> and a valve controller <NUM>. Pump controller <NUM> can be configured to operate pumps <NUM> and <NUM> by generating and providing control signals to pumps <NUM>-<NUM>. The control signals provided to pumps <NUM>-<NUM> can cause pumps <NUM>-<NUM> to activate, deactivate, or achieve a variable capacity or speed (e.g., operate at half speed, operate at full speed, etc.). Similarly, valve controller <NUM> can be configured to operate valve <NUM> by generating and providing control signals to valve <NUM>. The control signals provided to valve <NUM> can cause valve <NUM> to open, close, or achieve a specified intermediate position (e.g., one-third open, half open, etc.). In some embodiments, pump controller <NUM> and valve controller <NUM> are used by other components of controller <NUM> (e.g., testing procedure controller <NUM>, wound volume estimator <NUM>, etc.) to operate pumps <NUM>-<NUM> and valve <NUM> when carrying out the processes described herein.

In some embodiments, pump controller <NUM> uses input from a canister sensor configured to detect whether removed fluid canister <NUM> is present. Pump controller <NUM> can be configured to activate pneumatic pump <NUM> only when removed fluid canister <NUM> is present. For example, pump controller <NUM> can check whether canister <NUM> is present and can activate pneumatic pump <NUM> in response to a determination that canister <NUM> is present. However, if canister <NUM> is not present, pump controller <NUM> may prevent pneumatic pump <NUM> from activating. Similarly, pump controller <NUM> can be configured to activate instillation pump <NUM> only when instillation fluid canister <NUM> is present. For example, pump controller <NUM> can check whether canister <NUM> is present and can activate instillation pump <NUM> in response to a determination that canister <NUM> is present. However, if canister <NUM> is not present, pump controller <NUM> may prevent instillation pump <NUM> from activating.

Controller <NUM> is shown to include a pressure monitor <NUM>. Pressure monitor <NUM> can be configured to monitor the pressure within removed fluid canister <NUM> and/or the pressure within wound dressing <NUM> or wound <NUM> using feedback from pressure sensors <NUM> and/or <NUM>. For example, pressure sensors <NUM> and/or <NUM> may provide pressure measurements to pressure monitor <NUM>. Pressure monitor <NUM> can use the pressure measurements to determine the pressure within canister <NUM> and/or the pressure within wound dressing <NUM> or wound <NUM> in real-time. Pressure monitor <NUM> can provide the pressure value to model generator <NUM>, pump controller <NUM>, testing procedure controller <NUM>, and/or valve controller <NUM> for use as an input to control processes performed by such components.

Referring now to <FIG>, controller <NUM> is shown to include a testing procedure controller <NUM>. Testing procedure controller <NUM> can be configured to execute a pressure testing procedure to invoke and observe a pressure dynamic response or leakage rate. If therapy device <NUM> is connected to a wound dressing <NUM> applied to a patient's skin <NUM> over a wound <NUM>, testing procedure controller <NUM> can observe the dynamic pressure response and leakage rate of a negative pressure circuit that includes conduit <NUM>, removed fluid canister <NUM>, tubing <NUM>, wound dressing <NUM>, and/or wound <NUM> (which may have an unknown volume). If therapy device <NUM> is connected to a wound dressing <NUM> applied to a training device having a known volume, testing procedure controller <NUM> can observe the dynamic pressure response of a training circuit that includes conduit <NUM>, removed fluid canister <NUM>, tubing <NUM>, wound dressing <NUM>, and/or the training device.

Referring particularly to <FIG>, graph <NUM> illustrates a testing procedure that controller <NUM> (e.g., testing procedure controller <NUM>) may be configured to perform, according to some embodiments. In some embodiments, controller <NUM> is configured to perform the testing procedure shown in graph <NUM> to determine the leak rate parameter αleak and the drawdown time parameter αtime.

Graph <NUM> includes series <NUM> which shows the relationship between negative pressure (the Y-axis) and time (the X-axis) over the testing procedure, according to some embodiments. In some embodiments, the testing procedure includes a first drawdown period <NUM>, a leak rate determination period <NUM>, a vent period <NUM>, and a second drawdown period <NUM>. In some embodiments, first drawdown period <NUM> occurs between time t<NUM> and time t<NUM>. In some embodiments, leak rate determination period <NUM> occurs between time t<NUM> and time t<NUM>. In some embodiments, vent period <NUM> occurs between time t<NUM> and time t<NUM>. In some embodiments, second drawdown period <NUM> occurs between time t<NUM> and time t<NUM>.

During first drawdown period <NUM>, controller <NUM> can send a control signal to valve <NUM> to transition valve <NUM> into a closed configuration such that air cannot pass through conduit <NUM> to vent <NUM>. In some embodiments, testing procedure controller <NUM> sends a command to valve controller <NUM> to transition valve <NUM> into a closed configuration for first drawdown period <NUM>. In some embodiments, after valve <NUM> has been transitioned into the closed configuration, testing procedure controller <NUM> sends control signals to pump controller <NUM> to draw down (e.g., create a negative pressure) at wound <NUM>. In some embodiments, testing procedures controller <NUM> sends information to pump controller <NUM> regarding a drawdown rate (i.e., <MAT>). Pump controller <NUM> is configured to send control signals to pneumatic pump <NUM> to draw down pressure (e.g., create negative pressure) at wound <NUM> according to the drawdown rate. In some embodiments, pump controller <NUM> is configured to operate pneumatic pump <NUM> to drawdown according to one or more predetermined drawdown rates. In some embodiments, testing procedure controller <NUM> is configured to send a command to pump controller <NUM> to cause pneumatic pump <NUM> to drawdown at a maximum rate for first drawdown period <NUM>. In some embodiments, testing procedure controller <NUM> sends values of a manipulated variable u to pump controller <NUM> to cause pneumatic pump <NUM> to drawdown according to a predetermined drawdown rate. For example, testing procedure controller <NUM> may send pump controller <NUM> a binary value of manipulated variable u (e.g., u = <NUM> or u = <NUM>). For example, testing procedure controller <NUM> may send pump controller <NUM> a value u<NUM> = <NUM> of the manipulated variable to pump controller <NUM> which indicates that pump controller <NUM> should cause pneumatic pump <NUM> to drawdown at a first predetermined drawdown rate. Likewise, testing procedure controller <NUM> may send pump controller <NUM> a value u<NUM> = <NUM> of the manipulated variable to pump controller <NUM> which indicates that pump controller <NUM> should cause pneumatic pump <NUM> to drawdown at a second predetermined drawdown rate which is greater than the first predetermined drawdown rate. Testing procedure controller <NUM> may send pump controller <NUM> a 1xd vector of values of the manipulated variable u such as: <MAT> where u<NUM> is a binary value of the manipulated variable u indicating whether or not pump controller <NUM> should cause pneumatic pump <NUM> to drawdown at a first drawdown rate, u<NUM> is another binary value of the manipulated variable u indicating whether or not pump controller <NUM> should cause pneumatic pump <NUM> to drawdown at a second drawdown rate, etc., and ud is a dth binary value of the manipulated variable u indicating whether or not pump controller <NUM> should cause pneumatic pump <NUM> to drawdown at a dth drawdown rate. For example, if d = <NUM>, and pump controller <NUM> can cause pneumatic pump <NUM> to drawdown according to four predetermined drawdown rates, vector u may have the form: <MAT> such that u<NUM> = <NUM>, u<NUM> = <NUM>, u<NUM> = <NUM>, and u<NUM> = <NUM> which indicates that pump controller <NUM> should cause pneumatic pump <NUM> to drawdown according to the fourth drawdown rate (i.e., u<NUM> = <NUM>). In some embodiments, the dth drawdown rate (e.g., in this case, the fourth), is the fastest drawdown rate, while the first drawdown rate is the slowest drawdown rate. In some embodiments, testing procedure controller <NUM> sends pump controller <NUM> a command to cause pneumatic pump <NUM> to drawdown at the fastest drawdown rate for first drawdown period <NUM> (e.g., ud = <NUM>). Testing procedure controller <NUM> can also use the variable drawdown rate of pneumatic pump for second drawdown period <NUM>. In some embodiments, the drawdown time parameter αtime is determined across second drawdown period <NUM>. In some embodiments, if the drawdown rate of pneumatic pump <NUM> across second drawdown period <NUM> is fast, the volume estimation of wound <NUM> is less accurate, but is estimated faster. Likewise, if the drawdown rate of pneumatic pump <NUM> across second drawdown period <NUM> is slow, the volume estimation of wound <NUM> is more accurate, but takes a longer time to estimate. In some embodiments, model generator <NUM> is configured to determine a model fwound for various predetermined drawdown rates of second drawdown period <NUM>, as described in greater detail below.

In some embodiments, testing procedure controller <NUM> uses a setpoint value r as a target value of negative pressure for first drawdown period <NUM>. For example, as shown in <FIG>, r = p<NUM> for first drawdown period <NUM>. In some embodiments, p<NUM> is a low pressure (e.g., a high magnitude of negative pressure) value. In some embodiments, p<NUM> = <NUM> mmHg. In some embodiments, p<NUM> is a negative pressure value such that any leaks in wound dressing <NUM> and/or connectors <NUM>-<NUM> can be monitored. In some embodiments, p<NUM> is a target value of negative pressure to be achieved at wound <NUM> at the end of first drawdown period <NUM>. For example, as shown in <FIG>, negative pressure increases throughout first drawdown period <NUM> until time t<NUM> where p = p<NUM>.

In some embodiments, testing procedure controller <NUM> receives measured pressure values of the pressure p at wound <NUM> via pressure monitor <NUM> and pressure sensors <NUM>/<NUM>. In some embodiments, testing procedure controller <NUM> receives values of the pressure p at wound <NUM> as values of a performance variable y. In some embodiments, testing procedure controller <NUM> is configured to perform feedback control (e.g., PID control, PI control, etc.) to determine values of the manipulated variable u. In some embodiments, testing procedure controller <NUM> monitors the values of the performance variable y in real time until the value of the performance variable y is substantially equal to the setpoint value r (e.g., p<NUM>). In some embodiments, once the value of the performance variable y is substantially equal to the value of the setpoint r (e.g.. p = p<NUM>), testing procedure controller <NUM> sends a value of the manipulated variable u to pump controller <NUM> to cause pneumatic pump <NUM> to cease the drawdown. For example, testing procedure controller <NUM> may initially send pump controller <NUM> a value of the manipulated variable u such as u = <NUM> until y = r. In some embodiments, once y = r, testing procedure controller <NUM> sends pump controller <NUM> a value of the manipulated variable u such as u = <NUM> so that pump controller <NUM> causes pneumatic pump <NUM> to stop drawing down pressure p. In some embodiments, once y = r (or once y is within an acceptable range r ± rx where rx indicates an allowable deviation of y from r), testing procedure controller <NUM> sends a command to pump controller <NUM> to cease drawing down negative pressure at wound <NUM>.

After first drawdown period has been completed (at t<NUM> as shown in graph <NUM>), leak rate determination period <NUM> begins, according to some embodiments. Leak rate determination period <NUM> is used to determine slope <NUM> which indicates a rate of leakage of the dressing application (e.g., wound dressing <NUM>, connectors <NUM>-<NUM>) of wound <NUM>. In some embodiments, slope <NUM> is the leak rate parameter αleak.

During leak rate determination period <NUM>, testing procedure controller <NUM> causes valve controller <NUM> to maintain valve <NUM> in the closed configuration for a predetermined period of time Δtleαk, according to some embodiments. Testing procedure controller <NUM> monitors pressure changes over leak rate determination period <NUM> to determine the leak rate parameter αleαk for the specific wound application. As shown in graph <NUM>, the negative pressure decreases from p<NUM> to p<NUM> from time t = t<NUM> to time t = t<NUM>. In some embodiments, testing procedure controller <NUM> monitors change in pressure (e.g., a decrease) over leak rate determination period. For example, testing procedure controller <NUM> can determine a drop in pressure, p<NUM> - p<NUM>, over leak rate determination period <NUM> as the leak rate parameter αleak. In some embodiments, leak rate determination period <NUM> has a predetermined time duration, Δtleαk = t<NUM> - t<NUM>. In some embodiments, testing procedure controller <NUM> measures pressure p<NUM> at time t<NUM> and pressure p<NUM> at time t<NUM>. In some embodiments, the leak rate parameter αleak = p<NUM> - p<NUM> over the predetermined time duration Δtleαk of leak rate determination period <NUM>.

Leak rate determination period <NUM> includes testing procedure controller <NUM> receiving and storing values of the performance variable y (e.g., negative pressure) over the predetermined time period Δtleαk, according to some embodiments. In some embodiments, testing procedure controller <NUM> receives values of the performance variable y over the predetermined time period Δtleαk where Δtleαk = t<NUM> - t<NUM>. For example, testing procedure controller <NUM> may receive values of the performance variable y at a sampling rate fsample over Δtleαk. In some embodiments, the sampling rate is the number of samples of the performance variable y received from pressure sensors <NUM>, <NUM> in a second, such as <MAT>. For example, if testing procedure controller <NUM> is configured to monitor and record values of the performance variable y from pressure sensors <NUM>, <NUM> over a ten second interval (i.e., Δtleαk = t<NUM> - t<NUM> = <NUM> seconds), and fsample = <NUM> Hz (i.e., <MAT>), then the number of samples of the performance variable y over leak rate determination period <NUM> is fsample ▪ Δtleak = <NUM> Hz ▪ <NUM> sec = <NUM> samples. In some embodiments, the samples are measured by pressure sensors <NUM>/<NUM>, and testing procedure controller <NUM> records the samples of the performance variable y in a vector, such as: S = [S<NUM> S<NUM>. Sw] where S<NUM> is the first recorded value of the performance variable y during leak rate determination period <NUM>, S<NUM> is the second recorded value of the performance variable y during leak rate determination period <NUM>, etc., Sw is the wth recorded value of the performance variable y during leak rate determination period <NUM>, and w is the number of samples of the performance variable y over leak rate determination period <NUM> (e.g., w = fsample ▪ (t<NUM> - t<NUM>)).

In some embodiments, testing procedure controller <NUM> also stores a vector of time values associated with the vector S. For example, testing procedure controller <NUM> may store a time vector t = [tS<NUM> tS<NUM>. tSw] where tS<NUM> is a time at which S<NUM> is recorded/sampled, tS<NUM> is a time at which S<NUM> is recorded/sampled, etc., and tSw is a time at which S<NUM> is recorded/sampled. In some embodiments, tS<NUM> = <NUM> and tSw = (t<NUM> - t<NUM>). In some embodiments, tS<NUM> = t<NUM> and tSw = t<NUM>. In some embodiments, each of the values of time vector t are spaced apart <MAT>. For example, if [sample = <NUM> Hz, and tS<NUM> is considered to be <NUM>, <MAT>.

In some embodiments, testing procedure controller <NUM> is configured to determine slope <NUM> (i.e., the leak rate parameter αleak) based on the vector S of samples of the negative pressure at wound <NUM>, and the time vector t associated with S. In some embodiments, testing procedures controller <NUM> determines slope <NUM> (i.e., slope m) between consecutive sampling values (e.g., S<NUM> and S<NUM>, S<NUM> and S<NUM>, S<NUM> and S<NUM>, etc.). For example, if testing procedure controller <NUM> records <NUM> sampled values (i.e., w = <NUM>) over leak rate determination period <NUM> such that S = [S<NUM> S<NUM> S<NUM> S<NUM> S<NUM>] and t = [tS<NUM> tS<NUM> tS<NUM> tS<NUM> tS<NUM>], testing procedure controller <NUM> determine w - <NUM> values of slope m. For example, testing procedure controller <NUM> can determine: <MAT>, and <MAT>. In some embodiments, testing procedure controller <NUM> can determine w - <NUM> values of m and store the values in a slope vector such as: <MAT> where each value of m is determined between consecutively occurring values of S and corresponding/associated values of t at which the samples were recorded.

Testing procedure controller <NUM> can determine the leak rate parameter αleαk based on t, S, and m. In some embodiments, testing procedure controller <NUM> determines an average of the values of m as αleak. For example, testing procedure controller <NUM> can determine: <MAT> according to some embodiments. Testing procedure controller <NUM> also determines a standard deviation associated with the leak rate parameter αleak: <MAT> where: <MAT> according to some embodiments.

In some embodiments, testing procedure controller <NUM> selects the maximum or minimum value of m as αleak. For example, testing procedure controller <NUM> may determine αleak as: <MAT> or: <MAT> according to some embodiments.

In some embodiments, testing procedure controller <NUM> uses the initial and final values of t and S to determine an overall slope m over the entirety of leak rate determination period <NUM> as the leak rate parameter αleak. Testing procedure controller <NUM> determines: <MAT> according to some embodiments.

In some embodiments, Δtleαk (e.g., time between t<NUM> and t<NUM>) of leak rate determination period <NUM> is a predetermined time period. For example Δtleαk may be <NUM> seconds, <NUM> seconds, <NUM> minutes, etc., according to some embodiments. If Δtleαk is a predetermined time period, testing procedure controller <NUM> can determine the leak rate parameter αleak as the change in pressure (e.g., p<NUM> - p<NUM>) over the predetermined time period. For example, αleak = p<NUM> - p<NUM> assuming Δtleαk is a predetermined value. Leak rate determination period <NUM> is used to determine αleαk which characterizes a seal quality at wound <NUM> and quantifies a leak rate at wound <NUM>. In some embodiments, αleak characterizes an ability of wound <NUM> to hold a negative pressure. For example, if αleak is very low, this indicates that wound <NUM> is well sealed and can hold a negative pressure well (e.g., without any leaks) since the pressure drop across leak rate determination period is negligible or slope <NUM> is a near-zero value. Similarly, if αleak is very high, this indicates that wound <NUM> is not well sealed and may not hold a negative pressure as well (e.g., identified by a large pressure drop across leak rate determination period <NUM> or a negative slope <NUM> with a large magnitude), according to some embodiments.

In some embodiments, after leak rate determination period <NUM> is completed, testing procedure controller <NUM> stores the values of αleak, m, t, and S collected/determined over leak rate determination period <NUM> and proceeds to vent period <NUM>. During vent period <NUM>, testing procedure controller <NUM> sends a command to valve controller <NUM> to transition valve <NUM> into the open configuration to allow wound <NUM> to return to atmospheric pressure, according to some embodiments. In some embodiments, testing procedure controller <NUM> causes valve controller <NUM> to maintain valve <NUM> in the open configuration for a predetermined amount of time such that the pressure p within wound <NUM> can return to atmospheric pressure (e.g., <NUM> mmHg negative pressure). In some embodiments, testing procedure controller <NUM> monitors the real time value of the performance variable y received from pressure sensors <NUM>/<NUM> via pressure monitor <NUM> and causes valve controller <NUM> to maintain valve <NUM> in the open configuration until the received pressure measurements from pressure sensors <NUM>/<NUM> are substantially equal to atmospheric pressure, as shown at t<NUM>.

After wound <NUM> has returned to atmospheric pressure, testing procedure controller <NUM> proceeds to second drawdown period <NUM>, according to some embodiments. In some embodiments, second drawdown period <NUM> is performed to determine the drawdown time parameter αtime. The drawdown time parameter αtime is an amount of time required to achieve a desired negative pressure value (e.g., p<NUM>). In some embodiments, the drawdown time parameter αtime is time interval <NUM>. Time interval <NUM> as shown in FIG. <NUM> is greater than time interval <NUM> as shown in FIG. <NUM>, according to some embodiments. In some embodiments, the value of time interval <NUM> can increase due to a larger volume of wound <NUM> and/or a higher leak rate (e.g., a higher value of αleak). Slope <NUM> as shown in <FIG> is substantially equal to slope <NUM> as shown in <FIG>, according to some embodiments. This may indicate that the wound application (e.g., dressing <NUM>) of the testing procedure as shown in <FIG> has a substantially equal leak rate compared to the wound application (e.g., dressing <NUM>) of the testing procedure as shown in <FIG>. Therefore, the increased value of time interval <NUM> as shown in <FIG>, compared to the value of time interval <NUM> as shown in <FIG>, may be due to the testing procedure of graph <NUM> being performed on a wound <NUM> with a larger volume than wound <NUM> of the testing procedure of graph <NUM>.

Testing procedure controller <NUM> can determine the drawdown time parameter αtime by sending a command (e.g., a value of the manipulated variable u) to pump controller <NUM> to cause pneumatic pump <NUM> to drawdown at a rate of <MAT>. Testing procedure controller <NUM> can receive the pressure measurements from pressure monitor <NUM> and/or pressure sensors <NUM>/<NUM> and determine an amount of time that pneumatic pump <NUM> operates to achieve a desired pressure (e.g., p<NUM>) as αtime. In some embodiments, testing procedure controller <NUM> can send a command to pump controller <NUM> to cause pneumatic pump <NUM> to drawdown according to various drawdown rates <MAT>. In some embodiments, faster drawdown rates allow αtime to be determined quicker but the model determined using αtime (described in greater detail below with reference to model generator <NUM>) is less accurate. In some embodiments, slower drawdown rates allow αtime to be used to generate a more accurate model, but require longer drawdown time (e.g., time interval <NUM>) to determine αtime.

In some embodiments, testing procedure controller <NUM> is configured to send a command to valve controller <NUM> to transition valve <NUM> into the closed configuration to initiate second drawdown period <NUM>. In some embodiments, after valve <NUM> has been transitioned into the closed configuration, testing procedure controller <NUM> sends a command to pump controller <NUM> to initiate a second drawdown. In some embodiments, testing procedure controller <NUM> sends a value of the manipulated variable u to pump controller <NUM> to cause pneumatic pump <NUM> to drawdown the negative pressure at wound <NUM>. In some embodiments, testing procedure controller <NUM> sends a command (e.g., a value of the manipulated variable u) to pump controller <NUM> to cause pneumatic pump <NUM> to drawdown according to a predetermined drawdown operation. In some embodiments, the predetermined drawdown operation includes increasing the voltage supplied to pneumatic pump <NUM> if pneumatic pump <NUM> cannot achieve the desired negative pressure (e.g., p<NUM>) given the current voltage. In some embodiments, the voltage increases of pneumatic pump <NUM> are performed at predetermined/known time intervals.

Similar to first drawdown period <NUM>, testing procedure controller <NUM> can send values of the manipulated variable u to pump controller <NUM> to cause pneumatic pump <NUM> to drawdown at a variety of drawdown rates for second drawdown period <NUM>. In some embodiments, faster drawdown rates result in a less accurate estimation of the drawdown time parameter αtime but can advantageously be used to estimate the drawdown time parameter αtime faster. Likewise, slower drawdown rates advantageously result in a more accurate estimation of the drawdown time parameter αtime but require a longer amount of time to estimate the drawdown time parameter αtime, according to some embodiments.

During second drawdown period <NUM>, testing procedure controller <NUM> monitors the value of the performance variable y received from pressure sensors <NUM>, <NUM> via pressure monitor <NUM> and compares the value of the performance variable y to the desired/setpoint value r. In some embodiments, the desired/setpoint value r is a negative pressure value at wound <NUM> that pneumatic pump <NUM> is trying to achieve (e.g., a target pressure value). For example, the setpoint value r may be p<NUM>. In some embodiments, the setpoint value r is greater than or less than p<NUM>. In this way, the target pressure value of second drawdown period <NUM> may be the same, or greater than, or less than the target pressure value of first drawdown period <NUM>.

Testing procedure controller <NUM> continues monitoring the value of the performance variable y and monitoring an amount of elapsed time since the beginning (e.g., t<NUM>) of second drawdown period <NUM>, according to some embodiments. In some embodiments, testing procedure controller <NUM> includes a timer configured to reset at the beginning of second drawdown period <NUM> (e.g., at t<NUM>) or to store a time at which second drawdown period <NUM> begins (e.g., store the value of t<NUM>). In some embodiments, the timer resets or records the time value immediately after valve <NUM> has transitioned into the closed configuration and once pneumatic pump <NUM> has begun drawing down pressure at wound <NUM>.

In some embodiments, once the value of the performance variable y is substantially equal to the setpoint r (e.g., equal to, within a negligible amount, etc.), the timer of testing procedure controller <NUM> records time t<NUM>. In some embodiments, testing procedure controller <NUM> monitors the amount of time (i.e., t<NUM> - t<NUM>) required to achieve the desired negative pressure value (e.g., r, p<NUM>). In some embodiments, testing procedure controller <NUM> monitors the elapsed time to drawdown to p<NUM> or r. In some embodiments, the amount of elapsed time Δtdrawdown = t<NUM> - t<NUM>. In some embodiments, the amount of elapsed time Δtdrawdown is the drawdown time parameter αtime.

Testing procedure controller <NUM> can perform the testing procedure as described in greater detail above to determine values of the leak rate parameter αleak and the drawdown time parameter αtime for a known volume of wound <NUM> and/or a known training circuit volume. For example, testing procedure controller <NUM> can perform the testing procedure multiple times for a variety of several training circuits having known volumes (e.g., <NUM> cc, <NUM> cc, <NUM> cc, <NUM> cc, etc.). In some embodiments, testing procedure controller <NUM> is configured to perform the testing procedure several times for each of the training circuits having known volumes. In some embodiments, the resulting values of the leak rate parameter αleαk and the drawdown time parameter αtime are averaged for each of the training circuits to mitigate an amount of random error. For example, the testing procedure may be performed <NUM> times for a training circuit having the known volume of <NUM> cc and the leak rate parameter αleak and the drawdown time parameter αtime can be averaged to reduce random error. In some embodiments, the testing procedure is performed for various NPWT systems having different pneumatic pumps <NUM>, therapy pressures, training circuit volumes, etc. In some embodiments, model generator <NUM> is configured to generate a model for each of multiple training circuits using any of the methods and techniques described in greater detail below.

In some embodiments, the training circuit volume includes known volume values of the various pipes, canisters, tubes, etc., which pneumatic pump <NUM> is configured to draw down. In some embodiments, the training circuit volume includes a known volume of wound <NUM>, Vwound. In some embodiments, the training circuit volume is: <MAT> where Vsystem is the known volume of various tubes, pipes, canisters, etc., which pneumatic pump <NUM> is configured to produce a negative pressure within (e.g., conduit <NUM>, removed fluid canister <NUM>, tubing <NUM>, wound dressing <NUM>, and/or wound <NUM>), and Vwound is a known volume of wound <NUM>.

In some embodiments, the testing procedure can be performed multiple times for a variety of values of Vwound. For example, the testing procedure can be performed by controller <NUM> for a value of Vwound = 50cc, Vwound = <NUM> cc, Vwound = <NUM> cc, etc. In some embodiments, the testing procedure is performed multiple times for each value of Vwound to determine average parameter values associated with the particular value of Vwound. In some embodiments, Vsystem is held constant while the testing procedure is repeated for various values of Vwound. In this way, changes in the overall volume of the training circuit, Vtraining are due to changes in Vwound. The testing procedure can also be performed multiple times for each value of Vwound having multiple leak rates. In some embodiments, testing procedure controller <NUM> is configured to provide model generator <NUM> with the leak rate parameter αleak and the drawdown time parameter αtime for each combination of leak rate and Vwound resulting from performing the testing procedure.

In some embodiments, controller <NUM> performs the testing procedure for various systems having different values of Vsystem. In some embodiments, controller <NUM> performs the testing procedure multiple times for various values of Vwound for each of the various systems. In some embodiments, model generator <NUM> is configured to generate a model for each of the various systems using any of the methods and techniques described in greater detail below. For example, model generator <NUM> can generate a model for various training circuits which may be used during NPWT.

In some embodiments, model generator <NUM> is configured to determine a model to relate the recorded/determined parameters (i.e., αleak and αtime) to Vwound for the known values of Vwound. This model can then be used during NPWT to determine the volume of an unknown wound <NUM>. Model generator <NUM> can be configured to perform a multi-variable regression (e.g., perform a multi-variable polynomial curve fit, perform a multi-variable linear regression), use a neural network, or create a matrix/table to create a model that relates the parameters to known values of Vwound. In some embodiments, model generator <NUM> creates a model for a variety of values of Vsystem. For example, model generator <NUM> can create a table for each of a variety of typical values of Vsystem which correspond to various NPWT circuits that may be used during NPWT.

Referring again to <FIG>, controller <NUM> is shown to include a model generator <NUM>, according to some embodiments. Model generator <NUM> can be configured to generate a model that defines a relationship between the parameters of the dynamic pressure response and the volume of wound <NUM>. To generate the model, model generator <NUM> can cause testing procedure controller <NUM> to run the pressure testing procedure outlined above for several different training circuits having several different known volumes (e.g., <NUM> cc, <NUM> cc, <NUM> cc, <NUM> cc, etc.). When the pressure testing procedure is performed on a training circuit having a known volume, the pressure testing procedure may be referred to as a training procedure. Each performance of the training procedure may include applying the pressure stimulus to a training circuit having a known volume, observing the dynamic pressure response of the training circuit to the pressure stimulus (e.g., determining/measuring αleak and αtime), and associating the known volume with the dynamic pressure response of the training circuit.

In some embodiments, model generator <NUM> records the values of the parameters of the dynamic pressure response (i.e., the leak rate parameter αleαk and the drawdown time parameter αtime) for each known volume and associates those values with the known volume. The values of the parameters and the known volume form a set of training data which can be used to construct the model. The values of the parameters form a set of model input training data, whereas the known volumes form a set of model output training data. Model generator <NUM> can use any of a variety of model generation techniques to construct a model (i.e., a mathematical model) that relates the values of the parameters to the corresponding volume in the set of training data.

In some embodiments, model generator <NUM> creates a n by m matrix A (i.e., a model) for each typical value of Vsystem (i.e., typical negative pressure wound therapy systems). In some embodiments, the matrix A relates the leak rate parameter values αleak and the drawdown time parameter values αdrawdown to the known wound volume values Vwound associated with the parameters. In some embodiments, the matrix A has the form: <MAT> where each column represents volumes of wound <NUM> corresponding to a different value of the drawdown time parameter αtime, each row represents different volumes of wound <NUM> corresponding to a different leak rate parameter αleαk, and each element of the matrix represents a volume of Vwound which corresponds to the particular combination of αtime and αleak. In some embodiments, model generator <NUM> is configured to receive various data sets where each data set includes a value of Vwound for which the particular test was performed, and the values of αtime and αleak that resulted from the test. In some embodiments, model generator <NUM> is configured to receive data sets from each iteration of the test and create matrix A based on the data sets. In some embodiments, matrix A is created (e.g., sorted, arranged, generated, constructed, etc.) such that the values of αtime (e.g., associated with the columns of matrix A) increase from left to right, and such that the values of αleak (e.g., associated with the rows of matrix A) increase from top to bottom of matrix A.

In some embodiments, model generator <NUM> also generates vectors which correspond to the rows and columns of matrix A. In some embodiments, the vectors are row and column vectors of the drawdown time parameters αtime and the leak rate parameters αleak which were determined through testing for the associated volume values. For example, the vector of the drawdown time parameters αtime may be referred to as vector C and have the form: <MAT> according to some embodiments. Likewise, the vectors of the leak rate parameters αleαk may be referred to as vector B and have the form: <MAT> according to some embodiments.

In some embodiments, model generator <NUM> creates a table <NUM> as shown in <FIG> based on the datasets received from testing procedure controller <NUM>. Table <NUM> includes a horizontal/top header <NUM> and a vertical/side header <NUM>, according to some embodiments. In some embodiments, top header <NUM> represents various values of αtime, and columns corresponding to various values of Vwound. Side header <NUM> represents various values of αleak and rows correspond to various values of Vwound. In some embodiments, top header <NUM> and the corresponding columns of Vwound values are sorted in an ascending order of αtime, with lower values of αtime farther left and higher values of αtime farther right. Likewise, side header <NUM> is sorted in ascending order of αleak with lower values of αleak at the top of side header <NUM> and higher values of αleak at the bottom of side header <NUM>, according to some embodiments.

In some embodiments, model generator <NUM> performs a multi-variable regression based on the values of Vwound and the corresponding αtime and αleak parameters. In some embodiments, model generator <NUM> performs a multi-variable linear regression to determine the equation: <MAT> where C<NUM>, C<NUM>, and C<NUM> are constants determined by model generator <NUM> by performing the multi-variable linear regression.

In some embodiments, model generator <NUM> performs a multi-variable non-linear regression to determine the equation: <MAT> where f<NUM> is a non-linear function of αtime determined by performing the non-linear multi variable regression, and f<NUM> is a non-linear function of αleak determined by performing the non-linear multi variable regression. In some embodiments, any of the above equations have the general form: <MAT> where fwound is a function (e.g., linear, non-linear, etc.) relating αleak and αtime to Vwound. In some embodiments, fwound is determined by performing a multi-variable regression on the various values of Vwound and the associated values of αtime and αleak corresponding to each of the Vwound values.

In some embodiments, model generator <NUM> creates fwound using a polynomial approximation model to relate the values of the parameters to the corresponding volume. To generate a polynomial approximation model, model generator <NUM> can perform a curve fitting process such as polynomial regression using any of a variety of regression techniques. Examples of regression techniques which can be used by model generator <NUM> include least squares, ordinary least squares, linear least squares, partial least squares, total least squares, generalized least squares, weighted least squares non-linear least squares, non-negative least squares, iteratively reweighted least squares, ridge regression, least absolute deviations, Bayesian linear regression, Bayesian multivariate linear regression, etc..

In some embodiments, fwound is generated by model generator <NUM> using a neural network. To generate a neural network model, model generator <NUM> can perform a machine learning process. Examples of machine learning techniques which can be used by model generator <NUM> include decision tree learning, association rule learning, artificial neural networks, deep learning, inductive logic programming, support vector machines, clustering, Bayesian networks, reinforcement learning, representation learning, similarity and metric learning, sparse dictionary learning, genetic algorithms, rule-based machine learning, etc..

Referring still to <FIG>, controller <NUM> is shown to include wound volume estimator <NUM>, according to some embodiments. In some embodiments, wound volume estimator <NUM> is provided with any of matrix A and the associated vectors B and C, table <NUM>, and/or the mathematical model determined by model generator <NUM> (e.g., fwound). In some embodiments, wound volume estimator <NUM> is configured to cause testing procedure controller <NUM> to perform the testing procedure as described in greater detail above with reference to <FIG> for an unknown wound volume. In some embodiments, wound volume estimator <NUM> is configured to perform the testing procedure. For example, wound volume estimator <NUM> may be configured to perform any of the functionality of testing procedure controller <NUM> (e.g., to perform first drawdown period <NUM>, operate valve <NUM>, control pneumatic pump <NUM>, etc.). In some embodiments, wound volume estimator <NUM> determines the values of αtime and αleαk or receives the determined values of αtime and αleak from testing procedure controller <NUM>. In some embodiments, wound volume estimator <NUM> uses any of the mathematical models (e.g., fwound), matrix A, table <NUM>, etc., generated and received from model generator <NUM> to determine an estimated value of the unknown value of Vwound. In some embodiments, if wound volume estimator <NUM> uses table <NUM> and/or matrix A, and one or both of the values of αtime and αleak do not correspond to the values of αtime and αleak as stored in vectors B and C or in table <NUM>, wound volume estimator <NUM> is configured to perform an interpolation to determine Vwound.

In some embodiments, wound volume estimator <NUM> uses table <NUM> to determine the unknown value Vwound based on the determined parameters αtime and αleak resulting from performing the testing procedure on wound <NUM> with an unknown volume. In some embodiments, wound volume estimator <NUM> first checks through the values of side header <NUM> to determine if any of the values of αleak in side header <NUM> are substantially equal to the value of αleak determined from performing the testing procedure on wound <NUM> with the unknown value of Vwound. For example, if wound volume estimator <NUM> determines that αleak is substantially equal to αleak,<NUM> of side header <NUM>, wound volume estimator <NUM> determines that the value of Vwound is one of the values of V in the row corresponding to αleak,<NUM>. Next, wound volume estimator <NUM> can compare the various values of αtime in the top header <NUM> to the value of αtime determined from performing the testing procedure on wound <NUM>. For example, if wound volume estimator <NUM> determines that αtime is substantially equal to αtime,<NUM>, and αleak is substantially equal to αleak,<NUM>, wound volume estimator <NUM> can determine that the volume of wound <NUM> is substantially equal to V<NUM>,<NUM>.

In some embodiments, if wound volume estimator <NUM> determines that αleak and/or αtime do not correspond to values of side header <NUM> and top header <NUM>, respectively, wound volume estimator <NUM> can perform an interpolation or an extrapolation to determine the volume of wound <NUM>. In some embodiments, wound volume estimator <NUM> uses any of the values of table <NUM> in a multi-variable linear interpolation (or extrapolation) to determine the volume of wound <NUM>. In some embodiments, wound volume estimator <NUM> performs a non-linear interpolation to determine the volume of wound <NUM>.

Wound volume estimator <NUM> can be similarly configured to determine the volume of wound <NUM> using matrix A and vectors B and C. For example, wound volume estimator <NUM> can compare the value of αtime to values of the elements of vector C to determine a column value of matrix A, and compare the value of αleak to values of the elements of vector B to determine a row value of matrix A. For example, if αtime is equal to the fifth element of vector C and αleak is equal to the tenth element of vector C, wound volume estimator <NUM> can select A(<NUM>,<NUM>) or V<NUM>,<NUM> as Vwound for wound <NUM>. Likewise, wound volume estimator <NUM> can be configured to interpolate or extrapolate values of matrix A to determine values of Vwound that are associated with a value of αtime and/or αleak not included in vector B and vector C. In some embodiments, wound volume estimator <NUM> is configured to use a linear multi-variable interpolation technique or a non-linear interpolation technique.

In some embodiments, wound volume estimator <NUM> is configured to use any of the linear regression equations (e.g., Vwound = C<NUM>αtime + C<NUM>αleak + C<NUM>), the non-linear regression equation (e.g., Vwound = f<NUM>(αtime) + f<NUM>(αleak)), or any of the mathematical models (e.g., generally referred to as Vwound = fwound (αtime, αleak)) determined using any of the methods described in greater detail above (e.g., generated using a machine learning algorithm, using a polynomial curve-fit, using a linear regression, etc.) using the data received from testing procedure controller <NUM> for the known volumes. For example, wound volume estimator <NUM> can input the determined values of αleak and αtime (e.g., the parameters resulting from performing the testing procedure on a wound <NUM> with an unknown volume) into fwound to determine the volume Vwound of wound <NUM>. In some embodiments, wound volume estimator <NUM> is configured to select an appropriate model (e.g., an appropriate table <NUM>, an appropriate matrix A, an appropriate fwound) based on a volume (e.g., Vsystem) of circuit which pneumatic pump <NUM> is configured to drawdown. For example, wound volume estimator <NUM> can select an appropriate fwound model generated from a testing procedure for a system having a similar volume from a database of various fwound models.

Advantageously, using both αtime and αleak to determine Vwound reduces inaccuracies or deviations in αtime due to air leaking into inner volume <NUM> of wound <NUM>, according to some embodiments. For example, a wound application for a wound having volume Vwound with a high leak rate (e.g., a high value of αleak) may have a higher value of αtime when compared to a wound with the same volume Vwound but a lower leak rate (e.g., a lower value of αleak). By taking both αtime and αleak into account, model generator <NUM> and wound volume estimator <NUM> can account for the degree of leakage for the particular wound and accurately determine Vwound, regardless of high or low leakage rates (e.g., high or low values of αleak).

Referring now to <FIG>, a graph <NUM> and process <NUM> illustrating an application of the wound volume estimates are shown, according to an exemplary embodiment. Controller <NUM> can use the estimated wound volume to calculate a volume of instillation fluid <NUM> to deliver to wound <NUM> (step <NUM>). In some embodiments, controller <NUM> calculates the volume of instillation fluid <NUM> to deliver to wound <NUM> by multiplying the estimated wound volume by a fluid instillation factor. The fluid instillation factor may be less than one (i.e., between zero and one) such that the calculated volume of instillation fluid <NUM> is less than the volume of wound <NUM>. In some embodiments, the fluid instillation factor is between approximately <NUM> and approximately <NUM>. However, it is contemplated that the fluid instillation factor can have any value in various alternative embodiments.

In graph <NUM>, line <NUM> represents the estimated volume of wound <NUM> as a function of time, whereas line <NUM> represents the calculated volume of instillation fluid <NUM> to deliver to wound <NUM> over time. At time t<NUM>, the estimated volume of wound <NUM> is V<NUM>. The estimated wound volume V<NUM> at time t<NUM> can be multiplied by the fluid instillation factor F (e.g., F = <NUM>) to calculate the volume of instillation fluid <NUM> V<NUM> to deliver to wound <NUM> at time t<NUM> (i.e., V<NUM> * F = V<NUM>). As wound <NUM> heals, the estimated volume of wound <NUM> decreases and reaches a value of V<NUM> at time t<NUM>. The estimated wound volume V<NUM> at time t<NUM> can be multiplied by the fluid instillation factor F to calculate the volume of instillation fluid <NUM> V<NUM> to deliver to wound <NUM> at time t<NUM> (i.e., V<NUM> * F = V<NUM>).

Controller <NUM> can then operate a pump to deliver the calculated volume of instillation fluid <NUM> to wound <NUM> (step <NUM>). Step <NUM> can include operating instillation pump <NUM> to draw instillation fluid <NUM> from instillation fluid canister <NUM> and deliver instillation fluid <NUM> to wound <NUM> via tubing <NUM> and <NUM>. In some embodiments, the calculated volume of instillation fluid <NUM> is also used to control the operation of pneumatic pump <NUM>. For example, controller <NUM> can operate pneumatic pump <NUM> to remove the volume of instillation fluid <NUM> from wound <NUM> via tubing <NUM>. The amount of time that pneumatic pump <NUM> operates may be a function of the volume of instillation fluid <NUM> that was delivered to wound <NUM>.

Referring now to <FIG>, a process <NUM> for generating a model (e.g., fwound) to relate one or more parameters (e.g., αleak and αtime) to a wound volume (e.g., Vwound) is shown, according to some embodiments. In some embodiments, controller <NUM> is configured to perform process <NUM>. In some embodiments, process <NUM> is performed by controller <NUM> and/or the various components of NPWT system <NUM>. In some embodiments, process <NUM> illustrates various steps that controller <NUM> can perform to determine fwound. In some embodiments, process <NUM> is the testing procedure described in greater detail above with reference to <FIG>. Process <NUM> includes steps <NUM>-<NUM>, according to some embodiments.

Process <NUM> includes providing a negative pressure circuit (NPC) with a known volume Vsystem for a known wound volume Vwound (step <NUM>), according to some embodiments. In some embodiments, providing the NPC circuit for the known wound includes setting up a NPC circuit by providing wound dressing <NUM> to patient's skin <NUM> over wound <NUM>. In some embodiments, Vwound is a known volume of wound <NUM>. For example, step <NUM> may include configuring NPWT system <NUM> (e.g., having a known Vsystem) to perform NPWT for a test wound (e.g., wound <NUM> with a known volume Vwound). In some embodiments, step <NUM> includes setting up NPWT system <NUM> and starting therapy device <NUM>.

Process <NUM> includes operating a pump to draw down negative pressure at wound <NUM> to achieve p<NUM> at the known wound volume Vwound (step <NUM>), according to some embodiments, in some embodiments, step <NUM> is first drawdown period <NUM>. In some embodiments, the pump is pneumatic pump <NUM>. In some embodiments, step <NUM> includes any of the functionality, techniques, steps, etc., of first drawdown period <NUM>. In some embodiments, step <NUM> is performed by testing procedure controller <NUM>. In some embodiments, p<NUM> is <NUM> mmHg. In some embodiments, step <NUM> is performed by testing procedure controller <NUM> and pump controller <NUM>. Pneumatic pump <NUM> is configured to produce a negative pressure at wound <NUM>, according to some embodiments. In some embodiments, step <NUM> includes testing procedure controller <NUM> monitoring pressure measurements at wound <NUM> via pressure sensors <NUM>, <NUM>, and continuing to cause pneumatic pump <NUM> to drawdown the negative pressure until the measured/monitored pressure is substantially equal to p<NUM>. In some embodiments, step <NUM> is also performed by valve controller. In some embodiments, step <NUM> includes valve controller <NUM> sending a control signal to valve <NUM> to transition valve <NUM> into a closed configuration such pneumatic pump <NUM> can drawdown a negative pressure at wound <NUM>.

Process <NUM> includes recording pressure values of the known volume Vwound for a predetermined time period Δtleαk (step <NUM>), according to some embodiments. In some embodiments, step <NUM> is leak rate determination period <NUM>. In some embodiments, controller <NUM> is configured to perform step <NUM>. In some embodiments, step <NUM> is performed by testing procedure controller <NUM>. For example, testing procedure controller <NUM> can be configured to receive pressure measurements from pressure sensors <NUM>/<NUM> over time period Δtleαk (e.g., t<NUM> - t<NUM> as shown in <FIG>) to perform step <NUM>. In some embodiments, step <NUM> includes recording multiple pressure values of the negative pressure (e.g., vacuum pressures) of wound <NUM>. In some embodiments, step <NUM> includes recording an initial pressure value (e.g., p<NUM>) of wound <NUM> at a beginning of time period Δtleαk, and a final pressure value (e.g., p<NUM>) at an end of time period Δtleαk. In some embodiments, step <NUM> is performed by testing procedure controller <NUM> and pressure monitor <NUM>.

Process <NUM> includes venting wound <NUM> to atmospheric pressure (step <NUM>), according to some embodiments. In some embodiments, step <NUM> is performed after step <NUM>. In some embodiments, step <NUM> and step <NUM> are performed simultaneously. In some embodiments, step <NUM> is performed by testing procedure controller <NUM> and valve controller <NUM>. For example, step <NUM> may include testing procedure controller <NUM> sending a command to valve controller <NUM> to transition valve <NUM> into the open configuration such that wound <NUM> can return to atmospheric pressure. In some embodiments, step <NUM> is performed by testing procedure controller, valve controller <NUM>, and valve <NUM>. In some embodiments, step <NUM> is vent period <NUM>.

Process <NUM> includes determining the leak rate parameter αleak for Vwound based on the pressure values of wound <NUM> recorded during step <NUM> (step <NUM>), according to some embodiments. In some embodiments, step <NUM> is performed by testing procedure controller <NUM>. In some embodiments, αleak is a difference between an initial pressure value and a final pressure value of time interval Δtleαk. In some embodiments, αleak is slope <NUM>. In some embodiments, <MAT>.

Process <NUM> includes repeating steps <NUM>-<NUM> (step <NUM>), according to some embodiments. In some embodiments, controller <NUM> and/or NPWT system <NUM> repeat steps <NUM>-<NUM> X number of times to determine an average value of αleak to minimize random error. In some embodiments, step <NUM> is optional.

Process <NUM> includes operating the pump (e.g., pneumatic pump <NUM>) to draw down negative pressure at wound <NUM> to achieve p<NUM> (step <NUM>), according to some embodiments. In some embodiments, step <NUM> is second drawdown period <NUM>. In some embodiments, step <NUM> is performed by testing procedure controller <NUM>, pump controller <NUM>, and pneumatic pump <NUM>. In some embodiments, the pressure is drawn down to pressure p<NUM>. In some embodiments, the pressure is drawn down to a pressure greater than or less than pressure p<NUM>.

Process <NUM> includes recording a time duration Δtdrawdown to achieve p<NUM> for wound <NUM> as αtime (step <NUM>), according to some embodiments. In some embodiments, time duration Δtdrawdown is time interval <NUM>. In some embodiments, αtime is the amount of time that pneumatic pump <NUM> must operate to achieve pressure p<NUM>. In some embodiments, step <NUM> is performed by testing procedure controller <NUM>.

Process <NUM> includes repeating steps <NUM>-<NUM> Y number of times to determine an average value of αtime (step <NUM>), according to some embodiments. In some embodiments, steps <NUM>-<NUM> are repeated in order to reduce an amount of random error in αtime. In some embodiments, step <NUM> is optional.

Process <NUM> includes recording the leak rate parameter αleak and the drawdown time parameter αtime associated with the value of Vwound in a dataset (step <NUM>), according to some embodiments. In some embodiments, step <NUM> is performed by testing procedure controller <NUM>. In some embodiments, step <NUM> includes generating a matrix N = [αtime αleak Vwound] and providing matrix N to model generator <NUM>. In some embodiments, the matrix N is stored, and additional performances of steps <NUM>-<NUM> define additional rows for the matrix N.

Process <NUM> includes repeating steps <NUM>-<NUM> for various values of Vwound, αleak, and αtime (step <NUM>), according to some embodiments. In some embodiments, each additional iteration of steps <NUM>-<NUM> results in an additional row of the matrix N. In some embodiments, steps <NUM>-<NUM> are performed until a sufficient amount of test data is recorded in matrix N. In some embodiments, steps <NUM>-<NUM> are performed for various values of Vwound which are typical, and for various leakages αleαk that may be encountered during implementation of NPWT.

Process <NUM> includes generating a model (e.g., fwound) relating Vwound to αleak and αtime for a current value of Vsystem (step <NUM>) based on the recorded datasets (e.g., matrix N), according to some embodiments. In some embodiments, step <NUM> is performed by model generator <NUM>. In some embodiments, step <NUM> includes providing the recorded datasets (e.g., matrix N) to model generator <NUM>. In some embodiments, the generated model is matrix A, table <NUM>, fwound, etc. In some embodiments, step <NUM> includes performing any of a regression, a curve fitting technique, a machine learning algorithm, etc., to determine fwound. In some embodiments, step <NUM> includes arranging, sorting, etc., matrix N to generate matrix A or table <NUM>. In some embodiments, a model is generated for each of multiple values of Vsystem. In some embodiments, step <NUM> includes providing the generated model to wound volume estimator <NUM>.

Process <NUM> includes repeating steps <NUM>-<NUM> for various values of Vsystem (step <NUM>) to determine models that relate αleak and αtime to Vwound for each of the various values of Vsystem, according to some embodiments. In some embodiments, step <NUM> includes performing steps <NUM>-<NUM> for various NPWT systems. In some embodiments, step <NUM> is performed by controller <NUM> and a test technician (e.g., step <NUM> may include replacing a current NPWT system with a different system having a different Vsystem).

Referring now to <FIG>, a process <NUM> for determining the volume Vwound of wound <NUM> (i.e., if the volume of wound <NUM> is unknown) is shown, according to some embodiments. Process <NUM> may rely on the model(s) generated in process <NUM> by model generator <NUM>. In some embodiments, process <NUM> can be performed intermittently throughout NPWT to determine the volume of wound <NUM>. Process <NUM> can be performed by controller <NUM>. Process <NUM> includes steps <NUM>-<NUM>, according to some embodiments.

Process <NUM> includes performing steps <NUM>-<NUM> of process <NUM> to determine the leak rate parameter αleαk for an unknown value of Vwound (step <NUM>), according to some embodiments. In some embodiments, step <NUM> is performed by controller <NUM>.

Process <NUM> includes performing steps <NUM>-<NUM> to determine the drawdown time parameter αtime (step <NUM>) for the unknown value of Vwound (step <NUM>), according to some embodiments. In some embodiments, step <NUM> is performed by controller <NUM>.

Process <NUM> includes inputting αleak and αtime to the model generated by model generator <NUM> in process <NUM> (step <NUM>), according to some embodiments. In some embodiments, step <NUM> includes inputting αleak and αtime into fwound for a present NPWT system having Vsystem to determine Vwound. In some embodiments, step <NUM> is performed by wound volume estimator <NUM>. In some embodiments, step <NUM> includes looking up a value of Vwound in table <NUM> and/or matrix A based on αleak and αtime. In some embodiments, step <NUM> includes interpolating or extrapolating to determine the value of Vwound if αleak does not match any of the values of side header <NUM> and/or vector B, or if αtime does not match any of the values of top header <NUM> and/or vector C.

Process <NUM> includes determining an instillation fluid volume based on the determine Vwound of step <NUM> (step <NUM>), according to some embodiments. In some embodiments, step <NUM> is performed by controller <NUM>. In some embodiments, step <NUM> is step <NUM> of process <NUM>.

Referring now to <FIG>, process <NUM> for operating therapy device <NUM> is shown, according to some embodiments. Process <NUM> can be performed by controller <NUM>, communications interface <NUM>, and user interface <NUM>. In some embodiments, process <NUM> is a process for determining a volume of a wound (e.g., wound <NUM>).

Process <NUM> initiates with startup of therapy device <NUM> (step <NUM>), according to some embodiments. In some embodiments, after therapy device <NUM> has started, process <NUM> proceeds to step <NUM>. At step <NUM>, controller <NUM> can receive a command from a user to transition therapy device <NUM> into fill assist mode, manual volume move, or automatic volume determination mode. In some embodiments, the command is received via user interface <NUM>. If the user sends a command to transition therapy device <NUM> into the fill assist mode, therapy device <NUM> transitions into the fill assist mode, and process <NUM> proceeds to step <NUM>, according to some embodiments. If the user sends a command to transition therapy device <NUM> into the manual volume entry mode, process <NUM> proceeds to step <NUM>, according to some embodiments. If the user sends a command to transition therapy device <NUM> into an automatic volume detection mode, process <NUM> proceeds to step <NUM>, according to some embodiments.

Process <NUM> includes performing the testing procedure to determine the leak rate parameter αleαk and the drawdown time parameter αtime (step <NUM>), according to some embodiments. In some embodiments, the testing procedure is the testing procedure described in greater detail above with reference to <FIG>. In some embodiments, the testing procedure is process <NUM>. In some embodiments, step <NUM> is performed by controller <NUM> and/or testing procedure controller <NUM>.

Process <NUM> includes estimating Vwound based on the leak rate parameter αleak and the drawdown time parameter αtime (step <NUM>), according to some embodiments. In some embodiments, step <NUM> is performed by wound volume estimator <NUM> using the model generated by model generator <NUM>. In some embodiments, the model fwound, or table <NUM>, or matrix A (and vectors B and C) are preloaded into memory <NUM> of controller <NUM> for a variety of values of Vsystem. In some embodiments, step <NUM> is step <NUM> of process <NUM>. In some embodiments, step <NUM> includes inputting the leak rate parameter αleak and the drawdown time parameter αtime into the model (as generated by model generator <NUM>, described in greater detail above) to determine Vwound.

Process <NUM> includes displaying the value of Vwound determined in step <NUM> via user interface <NUM> (step <NUM>), according to some embodiments. In some embodiments, the value of Vwound is displayed via user interface <NUM> in response to completing step <NUM>. In some embodiments, the value of Vwound is displayed via user interface <NUM> in addition to a confirmation from the user to accept or reject the value of Vwound.

Process <NUM> includes determining (e.g., receiving an input) whether the user has accepted the value of Vwound as determined in step <NUM> (step <NUM>), according to some embodiments. In some embodiments, a request is displayed via user interface <NUM> requesting confirmation of the value of Vwound. In some embodiments, controller <NUM> receives a command from a user (e.g., a yes or a no command) indicating whether the user has accepted the value of Vwound. If controller <NUM> receives a command from the user indicating that the user has accepted the value of Vwound (YES), process <NUM> proceeds to step <NUM>, according to some embodiments. If controller <NUM> receives a command from the user indicating that the user has rejected the value of Vwound (NO), process <NUM> proceeds to step <NUM>.

Process <NUM> includes setting the value of Vwound equal to the instillation volume (step <NUM>), according to some embodiments. In some embodiments, step <NUM> is performed by controller <NUM>. In some embodiments, step <NUM> includes determining the instillation volume (e.g., a volume of instillation fluid <NUM> to be provided to wound <NUM>) based on the value of Vwound. In some embodiments, step <NUM> includes performing process <NUM>. In some embodiments, process <NUM> ends (step <NUM>) in response to completing step <NUM>.

If controller <NUM> receives a command via user interface <NUM> that the user has rejected the value of Vwound (NO, step <NUM>), process <NUM> proceeds to step <NUM>, according to some embodiments. In some embodiments, step <NUM> includes requesting an input from the user via user interface <NUM> whether the automatic volume estimation (i.e., steps <NUM>-<NUM>) should be performed again. In some embodiments, if controller <NUM> receives a command from the user via user interface <NUM> to re-perform the automatic volume estimation, process <NUM> returns to step <NUM>. If controller <NUM> receives a command from the user via user interface <NUM> that indicates the automatic volume estimation should not be performed again, process <NUM> proceeds to step <NUM>, according to some embodiments.

Process <NUM> includes requesting an input from a user whether or not to transition into the fill assist mode (step <NUM>), according to some embodiments. In some embodiments, step <NUM> includes providing a request to the user via user interface <NUM>. In some embodiments, if controller <NUM> receives a command from the user via user interface <NUM> to perform the fill assist (YES, step <NUM>), process <NUM> proceeds to step <NUM>. In some embodiments, if controller <NUM> receives a command from the user via user interface <NUM> that a fill assist operation should not be performed (NO, step <NUM>), process <NUM> proceeds to step <NUM>.

Process <NUM> includes performing a fill assist operation (step <NUM>), according to some embodiments. In some embodiments, the fill assist operation is performed by controller <NUM> and instillation pump <NUM>. In some embodiments, the fill assist operation includes allowing a user to manually indicate an amount of instillation fluid <NUM> that should be provided to wound <NUM> by manually operating instillation pump <NUM>. Controller <NUM> can be configured to measure a quantity of instillation fluid <NUM> added to wound <NUM> by instillation pump <NUM> during the fill assist operation (as controlled by the user), and can determine Vwound based on the quantity of instillation fluid added to wound <NUM> during the fill assist operation (step <NUM>). In some embodiments, in response to completing the fill assist operation, process <NUM> proceeds to step <NUM>.

If controller <NUM> receives a command via user interface <NUM> that the fill assist operation should not be performed (step <NUM>, NO), process <NUM> proceeds to step <NUM>, according to some embodiments. At step <NUM>, controller <NUM> receives a manual volume entry via user interface <NUM>, according to some embodiments. In some embodiments, in response to receiving the manual volume entry via user interface <NUM>, process <NUM> proceeds to step <NUM>. At step <NUM>, controller <NUM> sets the manually entered volume (e.g., manually entered Vwound) as the instillation fluid volume. In some embodiments, after the manually entered volume has been set as the instillation fluid volume, process <NUM> proceeds to step <NUM>.

The construction and arrangement of the systems and methods as shown in the various exemplary embodiments are illustrative only. Although only a few embodiments have been described in detail in this disclosure, many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.). For example, the position of elements can be reversed or otherwise varied and the nature or number of discrete elements or positions can be altered or varied. Accordingly, all such modifications are intended to be included within the scope of the present disclosure. The order or sequence of any process or method steps can be varied or re-sequenced according to alternative embodiments. Other substitutions, modifications, changes, and omissions can be made in the design, operating conditions and arrangement of the exemplary embodiments without departing from the scope of the present disclosure.

The present disclosure contemplates methods, systems and program products on any machine-readable media for accomplishing various operations. The embodiments of the present disclosure can be implemented using existing computer processors, or by a special purpose computer processor for an appropriate system, incorporated for this or another purpose, or by a hardwired system. Embodiments within the scope of the present disclosure include program products comprising machine-readable media for carrying or having machine-executable instructions or data structures stored thereon. Such machine-readable media can be any available media that can be accessed by a general purpose or special purpose computer or other machine with a processor. By way of example, such machine-readable media can comprise RAM, ROM, EPROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code in the form of machine-executable instructions or data structures and which can be accessed by a general purpose or special purpose computer or other machine with a processor. Combinations of the above are also included within the scope of machine-readable media. Machine-executable instructions include, for example, instructions and data which cause a general purpose computer, special purpose computer, or special purpose processing machines to perform a certain function or group of functions.

Claim 1:
A wound therapy system comprising:
a negative pressure circuit configured to apply negative pressure to a wound;
a pump (<NUM>) fluidly coupled to the negative pressure circuit and configured to produce a negative pressure at the wound (<NUM>) or within the negative pressure circuit;
a pressure sensor (<NUM>, <NUM>) configured to measure the negative pressure within the negative pressure circuit or at the wound (<NUM>); and characterized by
a controller (<NUM>) configured to:
perform a testing procedure comprising a first drawdown period (<NUM>), a leak rate determination period (<NUM>), a vent period (<NUM>), and a second drawdown period (<NUM>);
receive one or more pressure measurements of the pressure sensor (<NUM>, <NUM>) over the leak rate determination period to determine a leak rate parameter;
monitor an amount of elapsed time over the second drawdown period to determine a drawdown parameter; and
estimate a volume of the wound (<NUM>) based on the leak rate parameter and the drawdown parameter.