Wound therapy system with wound volume estimation

Abstract

To provide a wound therapy system configured to estimate a wound volume.SOLUTION: A wound therapy system comprises: a negative pressure circuit configured to apply negative pressure to a wound; a pump fluidly coupled to the negative pressure circuit and operable to control the negative pressure 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 communicably coupled to the pump and the pressure sensor. The controller is configured to: execute a pressure testing procedure comprising applying a pressure stimulus to the negative pressure circuit; observe a dynamic pressure response of the negative pressure circuit to the pressure stimulus using pressure measurements recorded by the pressure sensor; and estimate a wound volume of the wound based on the dynamic pressure response.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims the benefit of priority to U.S. Provisional Patent Application No. 62 / 650,132, filed on Mar. 29, 2018, and U.S. Provisional Patent Application No. 62 / 799,241, filed on Jan. 31, 2019, the entire disclosures of which are hereby incorporated by reference herein in their entirety.

[0002] This disclosure generally relates to wound therapy systems, and more particularly to wound therapy systems configured to estimate the volume of a wound.

Background Art

[0003] Negative pressure wound therapy (NPWT) is a type of wound therapy that involves applying 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 required negative pressure and flow. Recent advances in wound healing with NPWT include applying topical fluid to the wound to act in combination with NPWT. However, it can be difficult to determine the appropriate volume of the dripping fluid to be delivered to the wound. In addition, it can also be difficult to accurately monitor and track the progress of healing over time.

Summary of the Invention

[0004] One embodiment of the present disclosure is a wound therapy system including a negative pressure circuit configured to apply negative pressure to a wound, a pump fluidly coupled to the negative pressure circuit and operable to control the negative pressure 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 control device communicatively coupled to the pump and the pressure sensor. The control device executes a pressure test procedure including applying a pressure stimulus to the negative pressure circuit, observes the dynamic pressure response of the negative pressure circuit to the pressure stimulus using the pressure measurements recorded by the pressure sensor, and is configured to estimate the wound volume of the wound based on the dynamic pressure response.

[0005] In some embodiments, the negative pressure circuit includes a wound dressing sealable to the skin surrounding the wound. In some embodiments, the negative pressure circuit includes at least one of a drip fluid canister for containing drip fluid for delivery to the wound or a removed fluid canister for containing fluid removed from the wound. In some embodiments, the negative pressure circuit includes a tube fluidly connecting the pump to the wound.

[0006] In some embodiments, the negative pressure circuit includes a wound dressing sealable to the skin surrounding the wound, at least one of a drip fluid canister for containing drip fluid for delivery to the wound or a removed fluid canister for containing fluid removed from the wound, and a tube fluidly connecting the drip fluid canister or the removed fluid canister to the wound dressing.

[0007] In some embodiments, the control device is configured to operate the pump to establish a negative pressure within the negative pressure circuit. In some embodiments, the test procedure includes operating the pump to establish a negative pressure within the negative pressure circuit and applying a pressure stimulus after the negative pressure has been established within the negative pressure circuit.

[0008] In some embodiments, the system includes a valve coupled to the negative pressure circuit and operable to controllably vent the negative pressure circuit. In some embodiments, applying the pressure stimulus includes opening the valve to allow an air flow into the negative pressure circuit for a predetermined time and closing the valve after the predetermined time has elapsed. In some embodiments, applying the pressure stimulus further includes waiting for another predetermined time after closing the valve and repeating the opening step, the closing step, and the waiting step until the negative pressure reaches a threshold pressure value. In some embodiments, applying the pressure stimulus further includes operating the pump while the valve is closed to reduce air leakage into the negative pressure circuit.

[0009] In some embodiments, the dynamic pressure response of the negative pressure circuit is characterized by a purge depth parameter defined as the difference between a measured value of the negative pressure before the valve is opened and a measured value of the negative pressure while the valve is open.

[0010] In some embodiments, the dynamic pressure response of the negative pressure circuit is characterized by a rebound parameter defined as the difference between a measured value of the negative pressure after the valve is closed and a measured value of the negative pressure while the valve is open.

[0011] In some embodiments, the dynamic pressure response of the negative pressure circuit is characterized by a delta parameter defined as the difference between a measured value of the negative pressure before the valve is opened and a measured value of the negative pressure after the valve is closed.

[0012] In some embodiments, the dynamic pressure response of the negative pressure circuit is characterized by a leakage rate parameter defined as the rate at which the negative pressure changes while the valve is closed.

[0013] In some embodiments, the wound therapy system includes an orifice located along the negative pressure circuit and configured to allow air to leak out of the negative pressure circuit at a known rate.

[0014] In some embodiments, applying a pressure stimulus includes operating a pump to achieve a predetermined negative pressure within the negative pressure circuit and stopping the pump when the predetermined negative pressure is reached within the negative pressure circuit.

[0015] In some embodiments, estimating a wound volume based on the dynamic pressure response includes determining values for one or more parameters that characterize the dynamic pressure response and applying the values of the one or more parameters as inputs to a model that defines the relationship between the one or more parameters and the wound volume.

[0016] In some embodiments, the model that defines the relationship between one or more parameters and the wound volume is a polynomial approximation model. In some embodiments, the model that defines the relationship between one or more parameters and the wound volume is a neural network.

[0017] In some embodiments, the control device is configured to perform a training procedure that includes applying a pressure stimulus to a training circuit having a known volume, observing the dynamic pressure response of the training circuit to the pressure stimulus using the pressure measurements recorded by a pressure sensor, and associating the known volume with the dynamic pressure response of the training circuit to generate a model that defines the relationship between one or more parameters and the wound volume.

[0018] In some embodiments, generating the model further includes repeating the training procedure for a plurality of known volumes, observing the dynamic pressure response of the training circuit for each of the plurality of known volumes, and generating a correlation between the plurality of known volumes and the dynamic pressure response of the training circuit.

[0019] In some embodiments, the control device is configured to perform a pressure test procedure, observe the dynamic pressure response, and estimate the wound volume a plurality of times during wound treatment. The control device can be configured to determine the progress of healing based on the change in the wound volume during wound treatment.

[0020] In some embodiments, the control device is configured to determine the volume of the dripping fluid to be delivered to the wound based on the estimated wound volume. The control device can be configured to operate a pump to deliver that volume of the dripping fluid to the wound.

[0021] In some embodiments, the control device is configured to determine the volume of the dripping fluid to be delivered to the wound by multiplying the estimated wound volume by a fluid dripping coefficient. In some embodiments, the fluid dripping coefficient is less than 1 such that the wound volume less than the total wound volume is filled with the dripping fluid. In some embodiments, the fluid dripping coefficient is from about 0.2 to about 0.8.

[0022] Another embodiment of the present disclosure is a method for estimating the wound volume of a wound. The method includes applying negative pressure to the wound using a negative pressure circuit, operating a pump fluidly coupled to the negative pressure circuit to control the negative pressure within the negative pressure circuit, measuring the negative pressure within the negative pressure circuit or at the wound, performing a pressure test procedure that includes applying a pressure stimulus to the negative pressure circuit, observing the dynamic pressure response of the negative pressure circuit to the pressure stimulus using the measured value of the negative pressure, and estimating the wound volume based on the dynamic pressure response.

[0023] In some embodiments, the negative pressure circuit includes a wound dressing sealable to the skin surrounding the wound. In some embodiments, the negative pressure circuit includes at least one of a drip fluid canister for containing drip fluid for delivery to the wound or a removed fluid canister for containing fluid removed from the wound. In some embodiments, the negative pressure circuit includes a tube fluidly connecting the pump to the wound.

[0024] In some embodiments, the negative pressure circuit includes a wound dressing sealable to the skin surrounding the wound, at least one of a drip fluid canister for containing drip fluid for delivery to the wound or a removed fluid canister for containing fluid removed from the wound, and a tube fluidly connecting the drip fluid canister or the removed fluid canister to the wound dressing.

[0025] In some embodiments, the method includes operating the pump to establish a negative pressure within the negative pressure circuit. In some embodiments, the test procedure includes operating the pump to establish a negative pressure within the negative pressure circuit and applying a pressure stimulus after the negative pressure has been established within the negative pressure circuit.

[0026] In some embodiments, the method includes operating a valve coupled to the negative pressure circuit to controllably vent the negative pressure circuit. In some embodiments, applying a pressure stimulus includes opening the valve to allow air flow into the negative pressure circuit for a predetermined time and closing the valve after the predetermined time has elapsed.

[0027] In some embodiments, applying a pressure stimulus further includes waiting for another predetermined time after closing the valve and repeating the opening step, the closing step, and the waiting step until the negative pressure reaches a threshold pressure value. In some embodiments, applying a pressure stimulus further includes operating a pump while the valve is closed to reduce air leakage into the negative pressure circuit.

[0028] In some embodiments, the dynamic pressure response of the negative pressure circuit is characterized by a purge depth parameter defined as the difference between a measured value of the negative pressure before the valve is opened and a measured value of the negative pressure while the valve is open.

[0029] In some embodiments, the dynamic pressure response of the negative pressure circuit is characterized by a rebound parameter defined as the difference between a measured value of the negative pressure after the valve is closed and a measured value of the negative pressure while the valve is open.

[0030] In some embodiments, the dynamic pressure response of the negative pressure circuit is characterized by a delta parameter defined as the difference between a measured value of the negative pressure before the valve is opened and a measured value of the negative pressure after the valve is closed.

[0031] In some embodiments, the dynamic pressure response of the negative pressure circuit is characterized by a leakage rate parameter defined as the rate at which the negative pressure changes while the valve is closed.

[0032] In some embodiments, the method includes enabling air to leak at a known rate into the negative pressure circuit through an orifice located along the negative pressure circuit.

[0033] In some embodiments, applying a pressure stimulus includes operating a pump to achieve a predetermined negative pressure within a negative pressure circuit and stopping the operation of the pump when the predetermined negative pressure is reached within the negative pressure circuit.

[0034] In some embodiments, estimating a wound volume based on a dynamic pressure response includes determining values for one or more parameters characterizing the dynamic pressure response and applying the values of the one or more parameters as inputs to a model that defines a relationship between the one or more parameters and the wound volume.

[0035] In some embodiments, the model that defines a relationship between the one or more parameters and the wound volume is a polynomial approximation model. In some embodiments, the model that defines a relationship between the one or more parameters and the wound volume is a neural network.

[0036] In some embodiments, the method includes performing a training procedure that includes applying a pressure stimulus to a training circuit having a known volume, observing the dynamic pressure response of the training circuit to the pressure stimulus using pressure measurements recorded by a pressure sensor, and generating a model that defines a relationship between the one or more parameters and the wound volume by associating the known volume with the dynamic pressure response of the training circuit.

[0037] In some embodiments, generating the model further includes repeating the training procedure for a plurality of known volumes, observing the dynamic pressure response of the training circuit for each of the plurality of known volumes, and generating a correlation between the plurality of known volumes and the dynamic pressure response of the training circuit.

[0038] In some embodiments, the method includes performing a pressure test procedure, observing the dynamic pressure response, and estimating the wound volume multiple times during wound treatment. The method may include determining the progress of healing based on changes in the wound volume during wound treatment.

[0039] In some embodiments, the method includes determining the volume of the instillation fluid to be delivered to the wound based on the estimated wound volume and operating a pump to deliver that volume of instillation fluid to the wound.

[0040] In some embodiments, determining the volume of the instillation fluid to be delivered to the wound includes multiplying the estimated wound volume by a fluid instillation coefficient. In some embodiments, the fluid instillation coefficient is less than 1 such that a wound volume less than the total wound volume is filled with the instillation fluid. In some embodiments, the fluid instillation coefficient is from about 0.2 to about 0.8.

[0041] Another embodiment of the present disclosure is a wound therapy system. The wound therapy system includes a negative pressure circuit configured to apply negative pressure to a wound, a canister containing an instillation fluid for delivery to the wound, a pump operable to deliver the instillation fluid to the wound, a pressure sensor configured to measure the negative pressure in the negative pressure circuit or at the wound, and a control device communicatively coupled to the pump and the pressure sensor. The control device is configured to perform a pressure test procedure to estimate the wound volume of the wound, determine the volume of the instillation fluid to be delivered to the wound based on the estimated wound volume, and operate the pump to deliver that volume of instillation fluid to the wound.

[0042] In some embodiments, the control device is configured to determine the volume of the instillation fluid to be delivered to the wound by multiplying the estimated wound volume by a fluid instillation coefficient. In some embodiments, the fluid instillation coefficient is less than 1 such that a wound volume less than the total wound volume is filled with the instillation fluid. In some embodiments, the fluid instillation coefficient is from about 0.2 to about 0.8.

[0043] In some embodiments, the negative pressure circuit includes a wound dressing sealable to the skin surrounding the wound. In some embodiments, the negative pressure circuit includes a tube fluidly connecting the canister to the wound dressing.

[0044] In some embodiments, the control device is configured to operate the pump to establish a negative pressure within the negative pressure circuit. In some embodiments, the pressure test procedure includes operating the pump to establish a negative pressure within the negative pressure circuit and applying a pressure stimulus to the negative pressure circuit after the negative pressure has been established within the negative pressure circuit.

[0045] In some embodiments, the wound therapy system includes an orifice located along the negative pressure circuit and configured to allow air to leak out of the negative pressure circuit at a known rate.

[0046] In some embodiments, the pressure test procedure includes operating the pump to achieve a predetermined negative pressure within the negative pressure circuit and, when the predetermined negative pressure is reached within the negative pressure circuit, stopping the operation of the pump and observing the dynamic pressure response of the negative pressure circuit.

[0047] In some embodiments, the system includes a valve coupled to the negative pressure circuit and operable to controllably vent the negative pressure circuit. In some embodiments, the pressure test procedure includes opening the valve to allow air flow into the negative pressure circuit for a predetermined time and closing the valve after the predetermined time has elapsed.

[0048] In some embodiments, the pressure test procedure includes waiting for another predetermined time after closing the valve and repeating the opening step, closing step, and waiting step until the negative pressure reaches a threshold pressure value.

[0049] In some embodiments, the pressure test procedure includes applying a pressure stimulus to the negative pressure circuit, observing the dynamic pressure response of the negative pressure circuit to the pressure stimulus using pressure measurements recorded by a pressure sensor, and estimating the wound volume of the wound based on the dynamic pressure response. In some embodiments, the pressure test procedure includes operating the pump while the valve is closed to reduce air leakage into the negative pressure circuit.

[0050] In some embodiments, the dynamic pressure response of the negative pressure circuit is characterized by a purge depth parameter defined as the difference between a measured value of the negative pressure before the valve is opened and a measured value of the negative pressure while the valve is open.

[0051] In some embodiments, the dynamic pressure response of the negative pressure circuit is characterized by a rebound parameter defined as the difference between a measured value of the negative pressure after the valve is closed and a measured value of the negative pressure while the valve is open.

[0052] In some embodiments, the dynamic pressure response of the negative pressure circuit is characterized by a delta parameter defined as the difference between a measured value of the negative pressure before the valve is opened and a measured value of the negative pressure after the valve is closed.

[0053] In some embodiments, the dynamic pressure response of the negative pressure circuit is characterized by a leakage rate parameter defined as the rate at which the negative pressure changes while the valve is closed.

[0054] In some embodiments, estimating the wound volume based on the dynamic pressure response includes determining values for one or more parameters that characterize the dynamic pressure response and applying the values of the one or more parameters as inputs to a model that defines the relationship between the one or more parameters and the wound volume.

[0055] In some embodiments, the model that defines the relationship between the one or more parameters and the wound volume is a polynomial approximation model. In some embodiments, the model that defines the relationship between the one or more parameters and the wound volume is a neural network.

[0056] In some embodiments, the control device is configured to perform a training procedure that includes applying a pressure stimulus to a training circuit having a known volume, observing the dynamic pressure response of the training circuit to the pressure stimulus using pressure measurements recorded by a pressure sensor, and generating a model that defines the relationship between one or more parameters and the wound volume by associating the known volume with the dynamic pressure response of the training circuit.

[0057] In some embodiments, generating the model further includes repeating the training procedure for a plurality of known volumes, observing the dynamic pressure response of the training circuit for each of the plurality of known volumes, and generating a correlation between the plurality of known volumes and the dynamic pressure response of the training circuit.

[0058] In some embodiments, the control device is configured to perform a pressure test procedure to estimate the wound volume multiple times during wound treatment and to determine the progress of healing based on changes in the wound volume during wound treatment.

[0059] Those skilled in the art will recognize that the generalities are merely illustrative and are in no way intended to be limiting. Other aspects of the apparatus and / or process described herein, features of the invention, and advantages will become apparent from the detailed description, which is to be construed in conjunction with the accompanying drawings and is defined only by the claims.

Brief Description of the Drawings

[0060]

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[0061] Overview Referring generally to the figures, a wound therapy system and its components involving fluid dripping and removal according to various exemplary embodiments are shown. The wound therapy system can include a therapy device and a wound dressing. The therapy device can include a dripping fluid canister, a removal fluid canister, a valve, a pneumatic pump, a dripping pump, and a control device. The wound dressing can be applied to the patient's skin surrounding the wound. The therapy device can be configured to provide negative pressure wound therapy (NPWT) by delivering the dripping fluid to the wound by maintaining the wound at a negative pressure. The components of the wound therapy device, the wound dressing, and / or the wound form a negative pressure circuit.

[0062] The control device can be configured to operate a pneumatic pump, a drip pump, a valve, and / or other controllable components of the therapy device. In some embodiments, the control device performs a pressure test procedure by applying a pressure stimulus to the negative pressure circuit. For example, the control device may instruct the valve to close and operate the pneumatic pump to establish a negative pressure within the negative pressure circuit. When the negative pressure is established, the control device may deactivate the pneumatic pump. The control device may open the valve for a predetermined time and then close it after the elapse of the predetermined time. In some embodiments, the control device operates the pneumatic pump while the valve is closed to reduce air leakage into the negative pressure circuit. The control device may observe the dynamic pressure response of the negative pressure circuit to the pressure stimulus using the pressure measurements recorded by the pressure sensor. The dynamic pressure response may be characterized by various parameters including, for example, a purge depth parameter, a rebound parameter, a delta parameter, and a leakage rate parameter (described in more detail below).

[0063] The control device can estimate the volume of the wound based on the observed dynamic pressure response. For example, the control device can apply the observed parameters as inputs to a pressure model that defines the relationship between the observed parameters and the volume of the negative pressure circuit and / or the volume of the wound. The model can include a polynomial approximation model, a neural network model, or any other model that associates the observed parameters with the volume of the negative pressure circuit and / or the volume of the wound. In some embodiments, the pressure model is an existing model stored in the control device by the manufacturer of the therapy device. In other embodiments, the control device can generate the pressure model in situ by performing a training procedure.

[0064] The training procedure may be the same as the pressure test procedure, except 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 the patient's skin surrounding the wound. The control device can apply a 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 can result in a different dynamic pressure response to the pressure stimulus. The control device can then associate the known volume of each training circuit with the corresponding dynamic pressure response. In some embodiments, the control device uses the dynamic pressure response of the training circuit to generate a pressure model that defines the relationship between the observed parameters of the dynamic pressure response (e.g., purge depth, rebound, delta, leak rate, etc.) and the volume of the training circuit. The pressure model can then be stored in the therapy device and used to estimate the volume of the wound, as described above.

[0065] In some embodiments, the control device is configured to perform a pressure test procedure, observe the dynamic pressure response, and estimate the wound volume multiple times during wound treatment. The control device can then determine the progress of healing based on the change in the wound volume during wound treatment. In some embodiments, the control device is configured to determine the volume of the dripping fluid to be delivered to the wound based on the estimated wound volume. The volume of the dripping fluid to be delivered may be a predetermined percentage (e.g., 20%, 50%, 80%, etc.) of the volume of the wound. The control device can then operate the drip pump to deliver the determined volume of the dripping fluid to the wound. These and other features of the wound therapy system are described in detail below.

[0066] Wound Therapy System Referring now to FIGS. 1-4, a negative pressure wound therapy (NPWT) system 100 according to an exemplary embodiment is shown. The NPWT system 100 is shown to include a therapy device 102 fluidly connected to a wound dressing 112 via tubes 108 and 110. The wound dressing 112 may be adhered or sealed to the patient's skin 116 surrounding the wound 114. Some examples of wound dressings 112 that can be used in combination with the NPWT system 100 are described in detail in U.S. Patent No. 7,651,484, issued January 26, 2010, U.S. Patent No. 8,394,081, issued March 12, 2013, and U.S. Patent Application No. 14 / 087,418, filed November 22, 2013. The entire disclosure of each of these patents and patent applications is incorporated herein by reference.

[0067] The therapy device 102 can be configured to provide negative pressure wound therapy by reducing the pressure at the wound 114. The therapy device 102 can create a vacuum (relative to atmospheric pressure) at the wound 114 by removing wound exudate, air, and other fluids from the wound 114. Wound exudate can include fluid that seeps from the patient's circulatory system into a lesion or inflammatory site. For example, wound exudate can include water and dissolved solutes such as blood, plasma proteins, white blood cells, platelets, and red blood cells. Other fluids removed from the wound 114 can include instilled fluid 105 that has already been delivered to the wound 114. The instilled fluid 105 can include, for example, a cleansing fluid, a formulation fluid, a drug fluid, an antibiotic fluid, or any other type of fluid that can be delivered to the wound 114 during wound treatment. The instilled fluid 105 can be held within an instilled fluid canister 104 and controllably dispensed to the wound 114 via an instilled fluid tube 108. In some embodiments, the instilled fluid canister 104 is removable from the therapy device 102 to allow the canister 106 to be refilled and replaced as needed.

[0068] The fluid 107 removed from the wound 114 passes through the removal fluid tube 110 and is collected in the removal fluid canister 106. The removal fluid canister 106 may be a component of the therapy device 102 configured to collect wound exudate and other fluid 107 removed from the wound 114. In some embodiments, the removal fluid canister 106 is removable from the therapy device 102 to allow the canister 106 to be emptied and replaced as needed. The lower portion of the canister 106 may be filled with wound exudate and other fluid 107 removed from the wound 114, while the upper portion of the canister 106 may be filled with air. The therapy device 102 can be configured to evacuate the inside of the canister 106 by sucking air out of the canister 106. The reduced pressure within the canister 106 can be transferred to the wound dressing 112 and the wound 114 via the tube 110 such that the wound dressing 112 and the wound 114 are maintained at the same pressure as the canister 106.

[0069] With particular reference to FIGS. 2-4, a block diagram is shown that more particularly illustrates a therapy device 102 according to an exemplary embodiment. The therapy device 102 is shown to include a pneumatic pump 120, a drip pump 122, a valve 132, a filter 128, and a control device 118. The pneumatic pump 120 can be fluidly coupled to the removal fluid canister 106 (e.g., via conduit 136) and can be configured to evacuate the inside of the canister 106 by sucking air out of the canister 106. In some embodiments, the pneumatic pump 120 is configured to operate in both a forward and a reverse direction. For example, the pneumatic pump 120 can operate in the forward direction to suck air out of the canister 106 and reduce the pressure within the canister 106. The pneumatic pump 120 can operate in the reverse direction to pump air into the canister 106 and increase the pressure within the canister 106. The pneumatic pump 120 can be controlled by the control device 118, which is described in more detail below.

[0070] Similarly, the drip pump 122 can be fluidly coupled to the drip fluid canister 104 via the tube 109 and fluidly coupled to the wound dressing 112 via the tube 108. The drip pump 122 can be operated to deliver the drip fluid 105 to the wound dressing 112 and the wound 114 by pumping the drip fluid 105 through the tubes 109 and 108, as shown in FIG. 4. The drip pump 122 can be controlled by a control device 118, which is described in more detail below.

[0071] The filter 128 can be positioned (e.g., along the conduit 136) between the removal fluid canister 106 and the air pressure pump 120 such that air drawn from the canister 106 passes through the filter 128. The filter 128 can be configured to prevent liquid particles or solid particles from entering the conduit 136 and reaching the air pressure pump 120. The filter 128 can include, for example, a hydrophobic and / or lipophilic bacterial filter such that aqueous and / or oily liquids form beads and adhere to the surface of the filter 128. The air pressure pump 120 can be configured to provide sufficient air flow through the filter 128 such that the pressure drop across the filter 128 does not become too large (e.g., such that the pressure drop does not substantially impede the application of negative pressure from the therapy device 102 to the wound 114).

[0072] In some embodiments, the therapy device 102 operates the valve 132 to controllably vent the negative pressure circuit, as shown in FIG. 3A. The valve 132 can be fluidly connected to the pneumatic pump 120 and the filter 128 via the conduit 136. In some embodiments, the valve 132 is configured to control the air flow between the conduit 136 and the environment surrounding the therapy device 102. For example, the valve 132 can be opened to allow air flow into the conduit 136 via the vent hole 134 and the conduit 138, and can be closed to prevent air flow into the conduit 136 via the vent hole 134 and the conduit 138. The valve 132 can be opened and closed by the control device 118, which will be described in more detail below. When the valve 132 is closed, the pneumatic pump 120 can evacuate the negative pressure circuit by creating an air flow through the filter 128 in a first direction, as shown in FIG. 2. The negative pressure circuit can include any component of the system 100 that can be maintained at a negative pressure when performing negative pressure wound therapy (e.g., the conduit 136, the fluid removal canister 106, the tube 110, the wound dressing 112, and / or the wound 114). For example, the negative pressure circuit can include the conduit 136, the fluid removal canister 106, the tube 110, the wound dressing 112, and / or the wound 114. When the valve 132 is open, the air flow from the environment surrounding the therapy device 102 can enter the conduit 136 via the vent hole 134 and the conduit 138 and fill the voids within the negative pressure circuit. The air flow from the conduit 136 into the canister 106 and other volumes within the negative pressure circuit may pass through the filter 128 in a second direction opposite to the first direction, as shown in FIG. 3A.

[0073] In some embodiments, the therapy device 102 vents the negative pressure circuit through the orifice 158 as shown in FIG. 3B. The orifice 158 may be a small opening in the conduit 136 or any other component of the negative pressure circuit (e.g., the fluid removal cannister 106, the tube 110, the tube 111, the wound dressing 112, etc.), and may allow air to leak out of the negative pressure circuit at a known rate. In some embodiments, the therapy device 102 vents the negative pressure circuit through the orifice 158 rather than operating the valve 132. The valve 132 can be excluded from the therapy device 102 in any embodiment that includes the orifice 158. The rate at which air leaks into the negative pressure circuit through the orifice 158 may be substantially constant or may vary as a function of the negative pressure, depending on the shape of the orifice 158. For embodiments in which the leak rate from the orifice 158 is variable, the control device 118 can calculate the leak rate from the orifice 158 based on a measured value of the negative pressure using a stored relationship between the negative pressure and the leak rate. Whether the leak rate from the orifice 158 is substantially constant or variable, the leakage of air into the negative pressure circuit through the orifice 158 can be used to generate the pressure decay curve that is used to estimate the volume of the wound 114, as described with reference to FIGS. 5-9.

[0074] In some embodiments, the therapy device 102 includes various sensors. For example, the therapy device 102 is shown to include a pressure sensor 130 configured to measure the pressure within the canister 106 and / or the pressure at the wound dressing 112 or wound 114. In some embodiments, the therapy device 102 includes a pressure sensor 113 configured to measure the pressure within the tube 111. The tube 111 may be connected to the wound dressing 112 and may be used only to measure the pressure at the wound dressing 112 or wound 114 without a secondary function such as guiding the instilled fluid 105 or wound exudate. In various embodiments, the tubes 108, 110, and 111 may be physically separate tubes or separate lumens within a single tube connecting the therapy device 102 to the wound dressing 112. Thus, the tube 110 may be described as a negative pressure lumen that functions to apply negative pressure to the wound dressing 112 or wound 114, whereas the tube 111 may be described as a sensing lumen configured to sense the pressure at the wound dressing 112 or wound 114. The pressure sensors 130 and 113 can be located within the therapy device 102, positioned at any location along the tubes 108, 110, and 111, or located at the wound dressing 112 in various embodiments. The pressure measurements recorded by the pressure sensors 130 and / or 113 can be passed to the control device 118. The control device 118 uses the pressure measurements as inputs to various pressure test operations and control operations performed by the control device 118 (described in more detail with reference to FIGS. 5-12).

[0075] The control device 118 can be configured to operate the pneumatic pump 120, the drip pump 122, the valve 132, and / or other controllable components of the therapy device 102. In some embodiments, the control device 118 performs a pressure test procedure by applying a pressure stimulus to the negative pressure circuit. For example, the control device 118 may instruct the valve 132 to close and operate the pneumatic pump 120 to establish a negative pressure within the negative pressure circuit. When the negative pressure is established, the control device 118 may deactivate the pneumatic pump 120. The control device 118 may open the valve 132 for a predetermined time and then close it after the elapse of the predetermined time. The control device 118 may observe the dynamic pressure response of the negative pressure circuit to the pressure stimulus using the pressure measurements recorded by the pressure sensors 130 and / or 113. The dynamic pressure response may be characterized by various parameters including, for example, a purge depth parameter, a rebound parameter, a delta parameter, and a leak rate parameter (described in more detail with reference to FIG. 5).

[0076] The control device 118 can estimate the volume of the wound 114 based on the observed dynamic pressure response. For example, the control device 118 can apply the observed parameters as inputs to a pressure model that defines the relationship between the observed parameters and the volume of the negative pressure circuit and / or the volume of the wound 114. The model can include a polynomial approximation model, a neural network model, or any other model that associates the observed parameters with the volume of the negative pressure circuit and / or the volume of the wound 114. In some embodiments, the pressure model is an existing model stored in the control device 118 by the manufacturer of the therapy device 102. In other embodiments, the control device 118 can generate the pressure model in situ by performing a training procedure.

[0077] The training procedure may be the same as the pressure test procedure, except that the therapy device 102 is connected to a training circuit having a known volume. For example, the wound dressing 112 can be applied to a test device having a known volume, rather than to the patient's skin 116 surrounding the wound 114. The control device 118 can apply a 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 can result in a different dynamic pressure response to the pressure stimulus. The control device 118 can then associate the known volume of each training circuit with the corresponding dynamic pressure response. In some embodiments, the control device 118 uses the dynamic pressure response of the training circuit to generate a pressure model that defines the relationship between the observed parameters of the dynamic pressure response (e.g., purge depth, rebound, delta, leak rate, etc.) and the volume of the training circuit. The pressure model can then be stored in the control device 118 and used, as previously described, to estimate the volume of the wound 114.

[0078] In some embodiments, the control device 118 is configured to perform a pressure test procedure, observe the dynamic pressure response, and estimate the wound volume multiple times during wound treatment. The control device 118 can then determine the progress of healing based on the change in the wound volume during wound treatment. In some embodiments, the control device 118 is configured to determine the volume of the drip fluid 105 to be delivered to the wound 114 based on the estimated wound volume. The volume of the drip fluid 105 to be delivered may be a predetermined percentage (e.g., 20%, 50%, 80%, etc.) of the volume of the wound 114. The control device 118 can then operate the drip pump 122 to deliver the determined volume of the drip fluid 105 to the wound 114. These and other features of the control device 118 will be described in more detail with reference to FIGS. 5-12.

[0079] In some embodiments, the therapy device 102 includes a user interface 126. The user interface 126 can include one or more buttons, dials, sliders, keys, or other input devices configured to receive input from the user. The user interface 126 can 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 the user. In some embodiments, the pressure measurements recorded by the pressure sensors 130 and / or 113 are presented to the user via the user interface 126. The user interface 126 can also display warnings generated by the control device 118. For example, the control device 118 can generate a "no cannister" warning if the cannister 106 is not detected.

[0080] In some embodiments, the therapy device 102 includes a data communication interface 124 (e.g., a USB port, a wireless transceiver, etc.) configured to transmit and receive data. The communication interface 124 can include a wired or wireless communication interface (e.g., a jack, an antenna, a transmitter, a receiver, a transceiver, a wire terminal, etc.) for data communication with an external system or device. In various embodiments, the communication can be direct communication (e.g., local wired or wireless communication), or communication via a communication network (e.g., a WAN, the Internet, a cellular network, etc.). For example, the communication interface 124 can include an Ethernet card and port for transmitting and receiving data via a USB port or an Ethernet-based communication link or network. In another example, the communication interface 124 can include a Wi-Fi transceiver for communicating via a wireless communication network or a cellular or mobile phone communication transceiver.

[0081] Control device Referring now to FIG. 5, a block diagram is shown that more particularly illustrates a control device 118 according to an exemplary embodiment. The control device 118 is shown to include a processing circuit 140 that includes a processor 142 and a memory 144. The processor 142 may be a general-purpose or special-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. The processor 142 is configured to execute computer code or instructions stored in the memory 144 or received from other computer-readable media (e.g., CD-ROM, network storage, remote server, etc.).

[0082] The memory 144 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. The memory 144 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. The memory 144 may include database components, object code components, script components, or any other type of information structure for supporting the various activities and the information structures described in the present disclosure. The memory 144 may be communicatively connected to the processor 142 via the processing circuit 140 and may include computer code for performing one or more processes described herein (e.g., by the processor 142). When the processor 142 executes instructions stored in the memory 144, the processor 142 generally configures the control device 118 (more particularly, the processing circuit 140) to complete such activities.

[0083] The control device 118 is shown to include a pump control device 146 and a valve control device 150. The pump control device 146 can be configured to operate the pumps 120 - 122 by generating a control signal and providing it to the pumps 120 - 122. The control signal provided to the pumps 120 - 122 can cause the pumps 120 - 122 to operate, stop operating, or achieve a variable capacity or variable speed (e.g., operate at half speed, operate at maximum speed, etc.) of the pumps 120 - 122. Similarly, the valve control device 150 can be configured to operate the valve 132 by generating a control signal and providing it to the valve 132. The control signal provided to the valve 132 can cause the valve 132 to open, close, or achieve a specified intermediate position (e.g., 1 / 3 open, 1 / 2 open, etc.) of the valve 132. In some embodiments, the pump control device 146 and the valve control device 150 are used by other components of the control device 118 (e.g., the test procedure control device 148, the wound volume estimator 156, etc.) to operate the pumps 120 - 122 and the valve 132 when executing the processes described herein.

[0084] In some embodiments, the pump control device 146 uses an input from a canister sensor configured to detect whether the removal fluid canister 106 is present. The pump control device 146 can be configured to operate the active pneumatic pump 120 only when the removal fluid canister 106 is present. For example, the pump control device 146 can confirm whether the canister 106 is present and can operate the pneumatic pump 120 in response to a determination that the canister 106 is present. However, if the canister 106 is not present, the pump control device 146 may prevent the pneumatic pump 120 from operating. Similarly, the pump control device 146 can be configured to operate the active drip pump 122 only when the drip fluid canister 104 is present. For example, the pump control device 146 can confirm whether the canister 104 is present and can operate the active drip pump 122 in response to a determination that the canister 104 is present. However, if the canister 104 is not present, the pump control device 146 may prevent the drip pump 122 from operating.

[0085] The control device 118 is shown to include a pressure monitor 152. The pressure monitor 152 can be configured to monitor the pressure within the removal fluid canister 106 and / or the pressure within the wound dressing 112 or the wound 114 using feedback from the pressure sensors 130 and / or 113. For example, the pressure sensors 130 and / or 113 may provide pressure measurements to the pressure monitor 152. The pressure monitor 152 can use the pressure measurements to determine in real time the pressure within the canister 106 and / or the pressure within the wound dressing 112 or the wound 114. The pressure monitor 152 can provide the pressure value to the model generation device 154, the pump control device 146, the test procedure control device 148, and / or the valve control device 150 for use as an input to control the processes implemented by such components.

[0086] Referring now to FIGS. 5 and 6A - 6C, the control device 118 is shown to include a test procedure control device 148. The test procedure control device 148 can be configured to execute a pressure test procedure to cause and observe a dynamic pressure response. When the therapy device 102 is connected to a wound dressing 112 applied to the patient's skin 116 covering the wound 114, the test procedure control device 148 can observe the dynamic pressure response of a negative pressure circuit (which may have an unknown volume) including the conduit 136, the fluid removal canister 106, the tube 110, the wound dressing 112, and / or the wound 114. When the therapy device 102 is connected to a wound dressing 112 applied to a training device having a known volume, the test procedure control device 148 can observe the dynamic pressure response of a training circuit including the conduit 136, the fluid removal canister 106, the tube 110, the wound dressing 112, and / or the training device.

[0087] Referring particularly to FIG. 6A, a graph 200 is shown illustrating a passive pressure test procedure performed by the test procedure control device 148, according to an exemplary embodiment. The test procedure control device 148 can be configured to operate the pneumatic pump 120 to establish a negative pressure within the negative pressure circuit and / or the training circuit. The negative pressure may be defined as the difference between the atmospheric pressure surrounding the therapy device 102 and the pressure within the negative pressure circuit and / or the training circuit (i.e., the amount by which the atmospheric pressure exceeds the pressure within the negative pressure circuit and / or the training circuit). For example, at time t0, the negative pressure is shown to have a value of P0 (e.g., 0 mmHg), which represents that the pressure within the negative pressure circuit and / or the training circuit is equal to the atmospheric pressure surrounding the therapy device 102.

[0088] At time t0, the test procedure control device 148 starts the operation of the pneumatic pump 120 to reduce the negative pressure in the negative pressure circuit and / or the training circuit. The negative pressure continues to decrease until it reaches a negative pressure value of P8 mmHg (for example, 125 mmHg) lower than the atmospheric pressure at time t1. Between time t1 and time t2, the test procedure control device 148 maintains the negative pressure at the value of P8 by operating the pneumatic pump 120 as needed to remove air from the negative pressure circuit and / or the training circuit. Then, after the negative pressure is established in the negative pressure circuit and / or the training circuit, the test procedure control device 148 may apply a pressure stimulus to the negative pressure circuit and / or the training circuit.

[0089] At time t2, the test procedure control device 148 stops the operation of the pneumatic pump 120. The magnitude of the negative pressure in the negative pressure circuit and / or the training circuit may decrease starting from time t2 due to air leakage into the negative pressure circuit and / or the training circuit while the valve 132 is closed. The rate at which the negative pressure decreases while the valve 132 is closed is determined by the slope of line 202 between time t2 and time t3. The test procedure control device 148 may determine the slope of line 202 between time t2 and time t3 and store this slope as the value of the leakage rate parameter. The leakage rate parameter may be one of the parameters characterizing the dynamic pressure response of the negative pressure circuit and / or the training circuit.

[0090] At time t3, the test procedure control device 148 applies a pressure stimulus to the negative pressure circuit and / or the training circuit. Applying the pressure stimulus may include operating the valve 132 to controllably ventilate the negative pressure circuit and / or the training circuit. For example, the test procedure control device 148 may open the valve 132 at time t3 to allow air flow into the negative pressure circuit and / or the training circuit. The test procedure control device 148 may keep the valve 132 open for a predetermined time (i.e., from time t3 to time t4) and close the valve 132 after the elapse of the predetermined time (i.e., at time t4).

[0091] At time t4, the test procedure control device 148 may observe the dynamic pressure response of the negative pressure circuit and / or the training circuit to the pressure stimulus. The dynamic pressure response may be characterized by several additional parameters including a purge depth parameter, a rebound parameter, and a delta parameter. The purge depth parameter may be defined as the difference between the measured value of the negative pressure P7 before the valve 132 is opened and the measured value of the negative pressure P3 while the valve 132 is open (i.e., purge depth = P7 - P3). The rebound parameter may be defined as the difference between the measured value of the negative pressure P6 after the valve 132 is closed and the measured value of the negative pressure P3 while the valve 132 is open (i.e., rebound = P6 - P3). The delta parameter may be defined as the difference between the measured value of the negative pressure P7 before the valve 132 is opened and the measured value of the negative pressure P6 after the valve 132 is closed (i.e., delta = P7 - P6).

[0092] In some embodiments, the test procedure control device 148 further applies the pressure stimulus one or more times until the negative pressure reaches the threshold value P1 when the valve 132 is closed. During each application of the pressure stimulus, the test procedure control device 148 may wait for another predetermined time (i.e., from time t4 to time t5 and from time t6 to time t7). For example, the test procedure control device 148 may wait for a predetermined time from time t4 to time t5 and apply the pressure stimulus again at time t5. The test procedure control device 148 may open the valve 132 at time t5 to allow air flow into the negative pressure circuit and / or the training circuit. The test procedure control device 148 may keep the valve 132 open for a predetermined time (i.e., from time t5 to time t6) and close the valve 132 after the predetermined time has elapsed (i.e., at time t6). At time t6, the test procedure control device 148 may store the values of the purge depth parameter (i.e., purge depth = P5 - P1), the rebound parameter (i.e., rebound = P4 - P1), and the delta parameter (i.e., delta = P5 - P4) in response to the second application of the pressure stimulus. This process can be repeated until the value of the negative pressure in the negative pressure circuit and / or the training circuit reaches the threshold pressure value P1 at time t9.

[0093] Referring particularly to FIG. 6B, a graph 210 is shown that illustrates an active test procedure performed by a test procedure control device 148, according to an exemplary embodiment. The test procedure control device 148 can be configured to operate the pneumatic pump 120 to establish a negative pressure within the negative pressure circuit and / or the training circuit. The negative pressure may be defined as the difference between the atmospheric pressure surrounding the therapy device 102 and the pressure within the negative pressure circuit and / or the training circuit (i.e., the amount by which the atmospheric pressure exceeds the pressure within the negative pressure circuit and / or the training circuit). For example, at time t0, the negative pressure is shown to have a value of P0 (e.g., 0 mmHg), which represents that the pressure within the negative pressure circuit and / or the training circuit is equal to the atmospheric pressure surrounding the therapy device 102.

[0094] The active test procedure illustrated in FIG. 6B may be substantially similar to the passive test procedure illustrated in FIG. 6A. However, in the active test procedure, the control device 148 can be configured to operate the pneumatic pump 120 by short periods of controlled operation of the pneumatic pump 120 while the valve 132 is closed (e.g., between times t4 and t5, between times t6 and t7, and between times t8 and t9) to compensate for a high air leakage rate into the negative pressure circuit and / or the training circuit. In graph 210, line 212 represents the pressure within the negative pressure circuit and / or the training circuit as a function of time. The actual air leakage rate into the negative pressure circuit and / or the training circuit while the valve 132 is closed is represented by the slope of line segment 216, whereas the slope of line 214 represents the average or assisted leakage rate between times t4 and t5. The average or assisted leakage rate is So as to be equal to TIFF2025102822000002.tif17170, during the time period from t4 to t5, a part of the air is removed from the negative pressure circuit and / or the training circuit (raising the negative pressure by each controlled operation) by the short-time controlled operation of the pneumatic pump 120. Similar negative pressure adjustments can be made during the time period from t6 to t7 and during the time period from t8 to t9. In this way, in order to compensate for the actual high leakage rate while the valve 132 is closed, the inflow of air into the negative pressure circuit and / or the training circuit can be alleviated.

[0095] Referring particularly to FIGS. 6C - 6D, graphs 220 and 230 are shown which illustrate uncontrolled test procedures implemented by the test procedure control device 148 according to an exemplary embodiment. Different from the passive and active test procedures described with reference to FIGS. 6A and 6B, the uncontrolled test procedure does not utilize the valve 132 and can be implemented for embodiments in which the therapy device 102 includes the orifice 158 instead of the valve 132. Graph 220 illustrates an uncontrolled test procedure when the orifice 158 leaks air into the negative pressure circuit and / or the training circuit at a variable leakage rate, whereas graph 220 illustrates an uncontrolled test procedure when the orifice 158 leaks air into the negative pressure circuit and / or the training circuit at a substantially constant leakage rate.

[0096] In both uncontrolled test procedures, at time t0, the test procedure control device 148 starts the operation of the pneumatic pump 120 to reduce the pressure in the negative pressure circuit and / or the training circuit. The negative pressure continues to decrease until it reaches a negative pressure value of P2 mmHg (e.g., 125 mmHg) lower than the atmospheric pressure at time t1.

[0097] At time t1, the test procedure control device 148 deactivates the pneumatic pump 120. The magnitude of the negative pressure in the negative pressure circuit and / or the training circuit may start at time t1 and decrease due to air leakage into the negative pressure circuit and / or the training circuit through the orifice 158. The rate at which the negative pressure decreases is determined by the slope of line 222 between time t1 and time t2. In graph 220, as time elapses between t1 and t2, as indicated by the slope of line 222 approaching zero, air leakage into the negative pressure circuit and / or the training circuit through the orifice 158 occurs more rapidly near time t1 and more slowly near time t2. In graph 230, air leakage into the negative pressure circuit and / or the training circuit through the orifice 158 occurs at a substantially constant rate, as indicated by the substantially straight line 232. In either scenario, the test procedure control device 148 may determine the slope of line 222 between time t1 and time t2 one or more times and store this slope as the value of the leakage rate parameter. Alternatively, the leakage rate parameter can be defined as the time required for the negative pressure to drop from P2 to P1 and can be calculated by subtracting t1 from t2 (i.e., t2 - t1). The leakage rate parameter may be one of the parameters characterizing the dynamic pressure response of the negative pressure circuit and / or the training circuit.

[0098] In various embodiments, the test procedure control device 148 can be configured to perform passive test procedures, active test procedures, and / or uncontrolled test procedures. Passive test procedures may be suitable under most conditions and may be the main test procedure or the default test procedure used by the test procedure control device 148. However, active test procedures may be suitable when the leakage rate is high and may be used by the test procedure control device 148 in response to a determination that the actual leakage rate exceeds a predetermined leakage rate threshold. Uncontrolled test procedures may be suitable for embodiments in which the valve 132 is replaced by the orifice 158.

[0099] The leakage rate can be determined in various ways. In some embodiments, the leakage rate is determined by operating the pneumatic pump 120 to achieve a predetermined negative pressure within the negative pressure circuit and measuring the pressure decay over time. In some embodiments, the leakage rate is determined based on the efficiency of the pneumatic pump 120 or the power consumed by the pneumatic pump 120. For example, the pump control device 146 can be configured to perform short-term controlled operation of the pneumatic pump 120 to maintain the negative pressure at a set value or to prevent the negative pressure from decreasing at a rate exceeding a predetermined leakage rate threshold, as described above. The number or frequency of these short-term controlled operations of the pneumatic pump 120 depends on the leakage rate and can be used to determine the leakage rate. Similarly, the power consumed by the pneumatic pump 120 to perform these short-term controlled operations depends on the leakage rate and can be used to determine the leakage rate. For example, the control device 118 can be configured to record the number of short-term controlled operations of the pneumatic pump 120 within a given period, measure the frequency or interval of the short-term controlled operations, measure the duty cycle of the pneumatic pump 120 (e.g., the percentage of time the pneumatic pump 120 is operating), or measure the amount of power consumed by the pneumatic pump 120 to perform the short-term controlled operations. Any of these measurement criteria may characterize the pump efficiency and can be stored as a pump efficiency parameter. The control device 118 can calculate the leakage rate as a function of the pump efficiency using a stored formula or a predetermined relationship.

[0100] Referring again to FIG. 5, the control device 118 is shown to include a model generation device 154. The model generation device 154 can be configured to generate a model that defines the relationship between the parameters of the dynamic pressure response and the volume of the wound 114. To generate the model, the model generation device 154 can cause the test procedure controller 148 to perform the pressure test procedure outlined above for several different training circuits having several different known volumes (e.g., 50 cc, 100 cc, 200 cc, 300 cc, etc.). When the pressure test procedure is performed on a training circuit having a known volume, the pressure test procedure may be referred to as a training procedure. Each execution of the training procedure may include applying a pressure stimulus to a training circuit having a known volume, observing the dynamic pressure response of the training circuit to the pressure stimulus, and associating the known volume with the dynamic pressure response of the training circuit.

[0101] In some embodiments, the model generation device 154 records the values of the parameters of the dynamic pressure response (i.e., leak rate, purge depth, rebound, delta, etc.) for each known volume and associates those values with the known volume. The values of the parameters and the known volumes form a set of training data that can be used to build the model. The values of the parameters form a set of model input training data, and in contrast, the known volumes form a set of model output training data. The model generation device 154 can use any of a variety of model generation techniques to build a model (i.e., a mathematical model) that associates the values of the parameters with the corresponding volumes as a set of training data.

[0102] In some embodiments, the model generation device 154 creates a polynomial approximation model to associate the values of the parameters with the corresponding volumes. To generate the polynomial approximation model, the model generation device 154 can perform a curve fitting process such as polynomial regression using any of various regression techniques. Examples of regression techniques that can be used by the model generation device 154 include the least squares method, ordinary least squares method, linear least squares method, partial least squares method, total least squares method, generalized least squares method, weighted least squares method, non-linear least squares method, non-negative least squares method, iteratively reweighted least squares method, ridge regression, least absolute deviation, Bayesian linear regression, Bayesian multivariate linear regression, and the like.

[0103] In other embodiments, the model generation device 154 creates a neural network model to associate the values of the parameters with the corresponding volumes. To generate the neural network model, the model generation device 154 can perform a machine learning process. Examples of machine learning techniques that can be used by the model generation device 154 include decision tree learning, correlation 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, and the like.

[0104] Referring now to FIG. 7A, there is shown a graph 250 illustrating several pressure decay curves 252, 254, 256, and 258 according to an exemplary embodiment. Each of the pressure decay curves 252 - 258 corresponds to a known volume and represents the pressure in the negative pressure circuit and / or training circuit as a function of time for the corresponding volume. For example, pressure decay curve 252 corresponds to a volume of 300 cc, pressure decay curve 254 corresponds to a volume of 200 cc, pressure decay curve 256 corresponds to a volume of 100 cc, and pressure decay curve 258 corresponds to a volume of 50 cc. Each of the pressure decay curves 252 - 258 may be created by the model generation device 154 using any of the modeling techniques described above. For example, the pressure decay curves 252 - 258 can be created by performing a pressure test procedure for each known volume and plotting the pressure decay over time for each known volume.

[0105] In some embodiments, the control device 118 uses the pressure decay curves 252 - 258 to convert the measured pressure value to the corresponding volume when estimating the volume of the wound 114. For example, the control device 118 can measure the pressure in the negative pressure circuit and identify the time at which the pressure was measured. The control device 118 can interpolate between the pressure decay curves 252 - 258 to determine an interpolated pressure value corresponding to the pair of measured pressure and time. For example, at time t1, the control device 118 may observe a pressure value of P1. The combination of time t1 and pressure P1 defines a point 260 within the graph 250. Point 260 is approximately midway between pressure decay curve 252 and pressure decay curve 254. The control device 118 can interpolate between pressure decay curves 252 and 254 and estimate that the volume of the negative pressure circuit is approximately midway between the known volume corresponding to pressure decay curve 252 and the known volume corresponding to pressure decay curve 254 (about 250 cc). In other embodiments, the control device 118 estimates the volume of the wound 114 by applying the observed parameters of the dynamic pressure response as inputs to the pressure model.

[0106] Referring now to FIG. 7B, there is shown a graph 260 illustrating a pressure decay curve 264 without assistance and a pressure decay curve 262 with assistance, according to an exemplary embodiment. In graph 260, both the pressure decay curve 264 without assistance and the pressure decay curve 262 with assistance correspond to the same volume of the negative pressure circuit and / or the training circuit. The pressure decay curve 264 without assistance illustrates the pressure decay during the passive test procedure shown in FIG. 6A (i.e., when the pneumatic pump 120 is not operated to compensate for the high leakage rate). Conversely, the pressure decay curve 262 with assistance illustrates the pressure decay during the active test procedure (i.e., when the pneumatic pump 120 is operated to compensate for the high leakage rate). As described with reference to FIG. 6B, the pressure decay is reduced by operating the pneumatic pump 120 during the active test procedure, and thus, a more gradual pressure decay curve 262 with assistance is obtained as compared to the pressure decay curve 264 without assistance.

[0107] Referring again to FIG. 5, the control device 118 is shown to include a wound volume estimator 156. The wound volume estimator 156 can be configured to estimate the volume of the wound 114 based on pressure measurements collected by the pressure sensors 130 and / or 113. In some embodiments, the wound volume estimator 156 estimates the volume of the wound 114 by performing a pressure test procedure. The pressure test procedure can include applying a pressure stimulus to the negative pressure circuit and observing the dynamic pressure response of the negative pressure circuit to the pressure stimulus. As described above, the negative pressure circuit can include any component of the system 100 that can be maintained at a negative pressure when performing negative pressure wound therapy (e.g., the conduit 136, the fluid removal canister 106, the tube 110, the wound dressing 112, and / or the wound 114).

[0108] To perform the pressure test procedure, the wound volume estimator 156 may instruct the valve 132 to close and operate the pneumatic pump 120 to establish a negative pressure within the negative pressure circuit. When the negative pressure is established, the wound volume estimator 156 may deactivate the pneumatic pump 120. The wound volume estimator 156 may open the valve 132 for a predetermined time and then close it after the lapse of the predetermined time. The wound volume estimator 156 may observe the dynamic pressure response of the negative pressure circuit to the pressure stimulus using the pressure measurements recorded by the pressure sensors 130 and / or 113. The dynamic pressure response may be characterized by various parameters including, for example, a purge depth parameter, a rebound parameter, a delta parameter, and a leak rate parameter, as previously explained.

[0109] The wound volume estimator 156 can estimate the volume of the wound 114 based on the observed dynamic pressure response. For example, the wound volume estimator 156 can apply the observed parameters as inputs to a pressure model that defines the relationship between the observed parameters and the volume of the negative pressure circuit and / or the volume of the wound 114. In some embodiments, the pressure model is a model created by the model generation device 154 (e.g., by performing a training procedure based on training data collected using a training circuit). The model can include a polynomial approximation model, a neural network model, or any other model that associates the observed parameters with the volume of the negative pressure circuit and / or the volume of the wound 114. In other embodiments, the pressure model is an existing model stored in the memory 144 by the manufacturer of the therapy device 102.

[0110] In some embodiments, the wound volume estimator 156 is configured to perform a pressure test procedure, observe a dynamic pressure response, and estimate the wound volume multiple times during wound treatment. The wound volume estimator 156 can then determine the progress of healing based on changes in the wound volume during wound treatment. In some embodiments, the wound volume estimator 156 is configured to determine the volume of the instillation fluid 105 to be delivered to the wound 114 based on the estimated wound volume. The volume of the instillation fluid 105 to be delivered may be a predetermined percentage (e.g., 20%, 50%, 80%, etc.) of the volume of the wound 114. The wound volume estimator 156 can then operate the instillation pump 122 to deliver the determined volume of the instillation fluid 105 to the wound 114.

[0111] Flow chart Referring now to FIG. 8, a flowchart of a process 300 for generating a pressure model according to an exemplary embodiment is shown. The process 300 can be performed by one or more components of the therapy device 102 to create a model that characterizes the dynamic pressure response of the training circuit and / or the negative pressure circuit. For example, the process 300 can be performed by the control device 118, the pneumatic pump 120, the valve 132, and / or the pressure sensors 130 and / or 113. In some embodiments, the process 300 is executed by the test procedure control device 148 and the model generation device 154.

[0112] Process 300 is shown to include applying a pressure stimulus to a training circuit having a known volume (step 302). The training circuit can include one or more components of therapy device 102 (e.g., conduit 136, removal fluid canister 106, etc.) and / or other components of system 100 (e.g., tube 110, wound dressing 112). Under wound treatment conditions, wound dressing 112 is typically applied to patient's skin 116 surrounding wound 114. However, the training circuit may replace wound 114 with a training device having a known volume. Step 302 can include instructing valve 132 to close and operating pneumatic pump 120 to establish a negative pressure within the training circuit. When the negative pressure is established, pneumatic pump 120 may be deactivated. Step 302 can include opening valve 132 for a predetermined time and then closing valve 132 after the elapse of the predetermined time.

[0113] Process 300 is shown to include observing the dynamic pressure response of the training circuit to the pressure stimulus (step 304) and associating the known volume of the training circuit with the dynamic pressure response (step 306). Step 304 can include monitoring the pressure of the training circuit over time using pressure measurements recorded by pressure sensors 130 and / or 113. The dynamic pressure response may be characterized by various parameters including, for example, purge depth parameter, rebound parameter, delta parameter, and leak rate parameter, as previously explained. Step 306 can include storing the values of the parameters of the dynamic pressure response as input training data and storing the known volume of the training circuit as output training data corresponding to the input training data.

[0114] Process 300 is shown to include determining whether all volumes have been tested (step 308). If not all volumes have been tested (i.e., the result of step 308 is "no"), the training device to which therapy device 102 is connected can be replaced with a different training device having a different known volume. Then, steps 302 - 306 can be repeated by applying a pressure stimulus to observe the dynamic pressure response of the training circuit for each known volume. Each set of dynamic pressure response parameters can be stored as input training data, and each set and the corresponding known volume can be stored as output training data.

[0115] When all volumes have been tested (i.e., the result of step 308 is "yes"), process 300 can proceed to generating a pressure model (step 310). Step 310 can include constructing a model (i.e., a mathematical model) that associates the values of the dynamic pressure response parameters with a set of training data for the corresponding volume using any of various model generation techniques.

[0116] In some embodiments, the model generated in step 310 is a polynomial approximation model. Step 310 can include performing a curve fitting process such as polynomial regression using any of various regression techniques. Examples of regression techniques that can be used in step 310 include least squares method, ordinary least squares method, linear least squares method, partial least squares method, total least squares method, generalized least squares method, weighted least squares method, non - linear least squares method, non - negative least squares method, iteratively re - weighted least squares method, ridge regression, least absolute deviation, Bayesian linear regression, Bayesian multivariate linear regression, and the like.

[0117] In some embodiments, the model generated in step 310 is a neural network model. Step 310 may include using any of a variety of machine learning techniques to generate a neural network model that associates values of the dynamic pressure response parameters with a corresponding volume as a set of training data. Examples of machine learning techniques that can be used in step 310 include decision tree learning, correlation 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, and the like. The pressure model can then be stored for use in estimating the volume of the wound 114.

[0118] Referring now to FIG. 9, a flowchart of a process 400 for estimating the volume of a wound according to an exemplary embodiment is shown. Process 400 can be performed by one or more components of the therapy device 102 to estimate the volume of the wound 114. For example, process 400 can be performed by the control device 118, the pneumatic pump 120, the valve 132, and / or the pressure sensor 130 and / or 113. In some embodiments, process 400 is executed by the test procedure control device 148 and the wound volume estimator 156.

[0119] Process 400 is shown to include applying a pressure stimulus to a negative pressure circuit having an unknown volume (step 402). The negative pressure circuit can include one or more components of therapy device 102 (e.g., conduit 136, waste fluid canister 106, etc.) and / or other components of system 100 (e.g., tube 110, wound dressing 112, wound 114). Under wound treatment conditions, wound dressing 112 may be applied to patient skin 116 surrounding wound 114. Thus, the volume of wound 114 forms part of the negative pressure circuit. Step 402 can include instructing valve 132 to close and operating pneumatic pump 120 to establish a negative pressure within the negative pressure circuit. When the negative pressure is established, pneumatic pump 120 may be deactivated. Step 402 can include opening valve 132 for a predetermined time and then closing valve 132 after the elapse of the predetermined time. In some embodiments, step 402 includes performing a passive test procedure and / or an active test procedure as described with reference to FIGS. 6A-6B.

[0120] Process 400 is shown to include observing the dynamic pressure response of the negative pressure circuit to the pressure stimulus (step 404) and determining values for parameters that characterize the dynamic pressure response (step 406). Step 404 can include monitoring the pressure of the negative pressure circuit over time using pressure measurements recorded by pressure sensors 130 and / or 113. The dynamic pressure response may be characterized by various parameters including, for example, a purge depth parameter, a rebound parameter, a delta parameter, and a leak rate parameter, as previously described. Step 406 can include storing the values of the parameters of the dynamic pressure response.

[0121] Process 400 is shown to include applying the value of the parameter as an input to a pressure response model that defines the wound volume as a function of the parameter (step 408). In some embodiments, the pressure response model is a model created by implementing process 300 (e.g., by implementing a regression process or a machine learning process using training data collected using a training circuit). The model can include a polynomial approximation model, a neural network model, or any other model that associates the observed parameter with the volume of the negative pressure circuit and / or the volume of the wound 114.

[0122] Process 400 is shown to include estimating the volume of the wound based on the output of the model (step 410). In some embodiments, the output of the pressure response model is the estimated volume of the wound 114. Thus, the output of the pressure response model can be used as the estimated wound volume. In other embodiments, the output of the pressure response model is the estimated volume of the negative pressure circuit. If the output of the pressure response model is the estimated volume of the negative pressure circuit, step 410 can include subtracting the known volume of other components of the negative pressure circuit to identify the estimated volume of the wound 114. For example, step 410 can include subtracting the known volume of the conduit 136, the fluid removal canister 106, the tube 110, and / or the wound dressing 112 such that the only remaining volume is the volume of the wound 114.

[0123] In some embodiments, the volume of the waste fluid canister 106 that forms part of the negative pressure circuit is limited to the volume of air within the canister 106. The volume of air within the canister 106 can vary based on the level of the waste fluid 107 within the canister 106. In some embodiments, the waste fluid canister 106 includes a sensor (e.g., a level sensor, a weight sensor, etc.) that operates to record the level of the waste fluid 107 within the canister 106. The observed level of the waste fluid 107 can then be used to estimate the volume of air within the canister 106. In other embodiments, the volume of air within the canister 106 can be estimated by performing a dead space detection process. An example of a dead space detection process that can be used to estimate the volume of air within the canister 106 is described in detail in U.S. Provisional Patent Application No. 62 / 577,579, filed Oct. 26, 2017, the entire disclosure of which is incorporated herein by reference.

[0124] Referring now to FIG. 10, a flowchart of a process 500 for monitoring the progress of healing over time according to an exemplary embodiment is shown. Process 500 can be implemented by one or more components of the therapy device 102 to evaluate the progress of healing based on the volume of the wound 114. For example, process 500 can be implemented by the control device 118, the pneumatic pump 120, the valve 132, and / or the pressure sensors 130 and / or 113.

[0125] Process 500 is shown to include performing a pressure test procedure (step 502) to estimate the wound volume multiple times during wound treatment. Step 502 may include performing process 400 multiple times (e.g., once a day) during wound treatment. Each time process 400 is performed, the volume of wound 114 may be estimated. Each estimated value of the wound volume can be stored along with the time at which the estimated value was obtained. The pair of time and estimated wound volume can be stored as a data point in the memory of therapy device 102 and / or presented to the user as an output of therapy device 102 (e.g., via communication interface 124 or user interface 126). In some embodiments, the estimated wound volume can be plotted as a function of time, as shown in FIG. 11.

[0126] Process 500 is shown to include determining the progress of healing based on the change in wound volume during wound treatment (step 504). Step 504 may include comparing the current estimated value of the wound volume with one or more previous estimated values of the wound volume to identify the change in the wound volume. In some embodiments, step 504 includes determining the rate at which wound 114 is healing based on the change in wound volume over time. In some embodiments, step 504 includes extrapolating or predicting the time at which wound 114 will be completely healed based on a series of wound volume estimates. For example, step 504 may include predicting the time at which the estimated wound volume reaches zero (or another threshold) based on the series of wound volume estimates obtained in step 502.

[0127] Referring now to FIGS. 11-12, graphs 600 and flowcharts 700 are shown illustrating the application of the estimated wound volume according to an exemplary embodiment. The control device 118 can calculate the volume of the dripping fluid 105 to be delivered to the wound 114 using the estimated wound volume (step 702). In some embodiments, the control device 118 calculates the volume of the dripping fluid 105 to be delivered to the wound 114 by multiplying the estimated wound volume by a fluid dripping coefficient. The fluid dripping coefficient may be less than 1 (i.e., between 0 and 1) such that the calculated volume of the dripping fluid 105 is less than the volume of the wound 114. In some embodiments, the fluid dripping coefficient is from about 0.2 to about 0.8. However, it is contemplated that the fluid dripping coefficient can have any value in various alternative embodiments.

[0128] In graph 600, line 602 represents the estimated volume of wound 114 as a function of time, while line 604 represents the calculated volume of the dripping fluid 105 to be delivered to wound 114 over time. At time t1, the estimated volume of wound 114 is V4. By multiplying the estimated wound volume V4 at time t1 by the fluid dripping coefficient F (e.g., F = 0.8), the volume of the dripping fluid 105 V3 to be delivered to wound 114 at time t1 can be calculated (i.e., V4*F = V3). As wound 114 heals, the estimated volume of wound 114 decreases and reaches a value of V2 at time t2. By multiplying the estimated wound volume V2 at time t2 by the fluid dripping coefficient F, the volume of the dripping fluid 105 V1 to be delivered to wound 114 at time t2 can be calculated (i.e., V2*F = V1).

[0129] Next, the control device 118 can operate the pump to deliver the calculated volume of the dripping fluid 105 to the wound 114 (step 704). Step 704 can include operating the dripping pump 122 to draw out the dripping fluid 105 from the dripping fluid canister 104 and deliver the dripping fluid 105 to the wound 114 via the tubes 109 and 108. In some embodiments, the calculated volume of the dripping fluid 105 is also used to control the operation of the pneumatic pump 120. For example, the control device 118 can operate the pneumatic pump 120 to remove that volume of the dripping fluid 105 from the wound 114 via the tube 110. The amount of time the pneumatic pump 120 operates can be a function of the volume of the dripping fluid 105 delivered to the wound 114.

[0130] Wound Therapy Graph Referring now to FIG. 13, a graph 800 is shown illustrating some stages of a wound therapy process according to an exemplary embodiment. The wound therapy process illustrated in FIG. 13 can be implemented by one or more components of the therapy device 102, as described above. Line 802 represents the negative pressure in the negative pressure circuit at each stage of the wound therapy process.

[0131] At time t0, the therapy device 102 begins operating the pneumatic pump 120 to decrease the negative pressure in the negative pressure circuit during an initial draw-down stage 804 that occurs between times t0 and t1. At time t1, the negative pressure in the negative pressure circuit reaches approximately 125 mmHg, which is lower than atmospheric pressure, and the pneumatic pump 120 is deactivated.

[0132] Between times t1 and t2, the negative pressure in the negative pressure circuit is monitored using measurements from the pressure sensors 130 and / or 113 during a seal verification stage 806. A substantial pressure change between times t1 and t2 can indicate that the seal between the wound dressing 112 and the patient's skin is not airtight, whereas a substantially constant pressure between times t1 and t2 can indicate that the wound dressing 112 is properly sealed to the patient's skin.

[0133] At time t2, the pneumatic pump 120 is operated until the negative pressure in the negative pressure circuit drops to approximately 200 mmHg, which is lower than the atmospheric pressure. When the negative pressure reaches 200 mmHg, the pneumatic pump 120 stops operating and the wound volume determination stage 808 starts. The pneumatic pump 120 may be intermittently operated during stage 808 to maintain the negative pressure at approximately 200 mmHg and compensate for air leakage into the negative pressure circuit.

[0134] At time t3, the pneumatic pump 120 stops operating and the leakage determination stage 810 starts. Between time t3 and t4, the negative pressure in the negative pressure circuit is monitored to determine the rate at which air leaks into the negative pressure circuit. At time t4, the pneumatic pump 120 is operated again to lower the negative pressure so as to return to approximately 200 mmHg. The pneumatic pump 120 may be intermittently operated between time t4 and t5 to maintain the negative pressure at approximately 200 mmHg and compensate for air leakage into the negative pressure circuit.

[0135] At time t5, the pneumatic pump 120 stops operating and the wound volume determination stage 812 starts. During the wound volume determination stage 812, the therapy device 102 may perform one or more of the pressure test procedures described with reference to FIGS. 6A - 6D. The time ranges shown in graphs 200, 210, 220, and 230 may occur entirely between time t5 and t6 in graph 800.

[0136] At time t6, the pneumatic pump 120 is operated and the negative pressure drops to approximately 125 mmHg, which is lower than the atmospheric pressure, during the lowering for the dripping stage 814. When the negative pressure reaches approximately 125 mmHg at time t7, the pneumatic pump 120 stops operating. The pneumatic pump 120 may be intermittently operated between time t7 and t8 to maintain the negative pressure at approximately 125 mmHg and compensate for air leakage into the negative pressure circuit. Between time t7 and t8, the dripping fluid 105 may be delivered to the wound 114.

[0137] Configuration of the Exemplary Embodiment The construction and arrangement of systems and methods as shown in various exemplary embodiments are merely exemplary. Although only a few embodiments are detailed in this disclosure, many modifications (e.g., changes in the size, dimensions, structure, shape, and ratio of various elements, parameter values, mounting arrangements, amounts of materials used, colors, orientations, etc.) are possible. For example, the positions of elements can be reversed or otherwise changed, and the nature or number of discrete elements can be modified or altered. Thus, all such modifications are intended to be included within the scope of this disclosure. The order or sequence of any process or method steps can be changed or reordered 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 invention.

[0138] This disclosure contemplates methods, systems, and program products on any machine-readable medium for performing various operations. Embodiments of the present disclosure can be implemented using an existing computer processor, by a dedicated computer processor for a suitable system incorporated for this or another purpose, or by a wired system. Embodiments within the scope of the present disclosure include program products that include a machine-readable medium for carrying or storing machine-executable instructions or data structures. 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 include RAM, ROM, EPROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of machine-executable instructions or data structures and that 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 for causing a general-purpose computer, special-purpose computer, or special-purpose processor to perform a certain function or group of functions.

[0139] The figure shows a specific order of method steps, but the order of the steps may be different from the order in which they are depicted. Also, two or more steps can be performed simultaneously or partially simultaneously. Such changes depend on the selected software system and hardware system as well as the designer's choices. All such changes are within the scope of this disclosure. Similarly, software embodiments can be implemented using standard programming techniques with rule-based logic and other logic to implement various connection steps, processing steps, comparison steps, and decision steps.

Claims

1. In a wound therapy system, a negative pressure circuit configured to apply a negative pressure to a wound; a pump fluidly coupled to the negative pressure circuit, the pump operable to control the negative pressure within the negative pressure circuit; a pressure sensor configured to measure the negative pressure within the negative pressure circuit or at the wound; a control device communicatively coupled to the pump and the pressure sensor, executing a pressure test procedure including applying a pressure stimulus to the negative pressure circuit, observing a dynamic pressure response of the negative pressure circuit to the pressure stimulus using pressure measurements recorded by the pressure sensor, and estimating a wound volume of the wound based on the dynamic pressure response the control device configured as such; A wound therapy system, characterized by comprising the above.

2. The wound therapy system according to claim 1, wherein the negative pressure circuit comprises a wound dressing sealable to the skin surrounding the wound.

3. The wound therapy system according to claim 1, wherein the negative pressure circuit comprises at least one of a drip fluid canister containing drip fluid for delivery to the wound or a removed fluid canister containing fluid removed from the wound.

4. The wound therapy system according to claim 1, wherein the negative pressure circuit comprises a tube fluidly connecting the pump to the wound.

5. The wound therapy system according to claim 1, wherein the negative pressure circuit comprises a wound dressing sealable to the skin surrounding the wound, at least one of a drip fluid canister containing drip fluid for delivery to the wound or a removed fluid canister containing fluid removed from the wound, and a tube fluidly connecting the drip fluid canister or the removed fluid canister to the wound dressing. A wound therapy system, characterized by comprising the above.

6. The wound therapy system according to claim 1, wherein the control device is configured to operate the pump to establish the negative pressure within the negative pressure circuit.

7. In the wound therapy system according to claim 1, the test procedure comprises operating the pump to establish the negative pressure within the negative pressure circuit, and applying the pressure stimulus after the negative pressure is established in the negative pressure circuit A wound treatment system, characterized by comprising the above. **Claim 8** The wound treatment system according to claim 1, further comprising a valve coupled to the negative pressure circuit and operable to controllably vent the negative pressure circuit. **Claim 9** In the wound treatment system according to claim 8, applying the pressure stimulus includes: opening the valve to allow an air flow into the negative pressure circuit for a predetermined time; closing the valve after the elapse of the predetermined time. A wound treatment system, characterized by comprising the above. **Claim 10** In the wound treatment system according to claim 9, applying the pressure stimulus includes: waiting for another predetermined time after closing the valve; repeating the opening step, the closing step, and the waiting step until the negative pressure reaches a threshold pressure value. A wound treatment system, further characterized by comprising the above. **Claim 11** In the wound treatment system according to claim 9, applying the pressure stimulus further includes operating the pump while the valve is closed to reduce air leakage into the negative pressure circuit. **Claim 12** In the wound treatment system according to claim 9, the dynamic pressure response of the negative pressure circuit is characterized by a purge depth parameter defined as the difference between a measured value of the negative pressure before the valve is opened and a measured value of the negative pressure while the valve is open. **Claim 13** In the wound treatment system according to claim 9, the dynamic pressure response of the negative pressure circuit is characterized by a rebound parameter defined as the difference between a measured value of the negative pressure after the valve is closed and a measured value of the negative pressure while the valve is open. **Claim 14** In the wound treatment system according to claim 9, the dynamic pressure response of the negative pressure circuit is characterized by a delta parameter defined as the difference between a measured value of the negative pressure before the valve is opened and a measured value of the negative pressure after the valve is closed. **Claim 15** In the wound therapy system according to claim 9, the dynamic pressure response of the negative pressure circuit is characterized by a leakage rate parameter defined as the rate at which the negative pressure changes while the valve is closed. A wound therapy system characterized by this.

16. In the wound therapy system according to claim 1, the wound therapy system further comprises an orifice located along the negative pressure circuit, the orifice being configured to allow air to leak out of the negative pressure circuit at a known rate.

17. In the wound therapy system according to claim 16, applying the pressure stimulus operating the pump to achieve a predetermined negative pressure in the negative pressure circuit, and stopping the operation of the pump when the predetermined negative pressure is reached in the negative pressure circuit A wound therapy system characterized by including.

18. In the wound therapy system according to claim 1, estimating the wound volume based on the dynamic pressure response determining values for one or more parameters characterizing the dynamic pressure response, and applying the values of the one or more parameters as inputs to a model defining the relationship between the one or more parameters and the wound volume A wound therapy system characterized by including.

19. In the wound therapy system according to claim 18, the model defining the relationship between the one or more parameters and the wound volume is a polynomial approximation model. A wound therapy system characterized by this.

20. In the wound therapy system according to claim 18, the model defining the relationship between the one or more parameters and the wound volume is a neural network. A wound therapy system characterized by this.

21. In the wound therapy system according to claim 18, the control device performs a training procedure including 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 using the pressure measurements recorded by the pressure sensor, and associating the known volume with the dynamic pressure response of the training circuit to generate the model defining the relationship between the one or more parameters and the wound volume. A wound therapy system characterized by this.

22. In the wound therapy system according to claim 21, generating the model comprises repeating the training procedure for a plurality of known volumes, observing the dynamic pressure response of the training circuit for each of the plurality of known volumes, generating a correlation between the plurality of known volumes and the dynamic pressure response of the training circuit and further comprising a wound therapy system characterized by this.

23. In the wound therapy system according to claim 1, the control device executes the pressure test procedure, observes the dynamic pressure response, and estimates the wound volume a plurality of times during wound treatment, and determines the progress of healing based on changes in the wound volume during wound treatment A wound therapy system characterized by being configured as follows.

24. In the wound therapy system according to claim 1, the control device determines the volume of the dripping fluid to be delivered to the wound based on the estimated wound volume, and operates the pump so as to deliver the volume of the dripping fluid to the wound A wound therapy system characterized by being configured as follows.

25. In the wound therapy system according to claim 24, the control device is configured to determine the volume of the dripping fluid to be delivered to the wound by multiplying the estimated wound volume by a fluid dripping coefficient, characterized by this.

26. In the wound therapy system according to claim 25, the fluid dripping coefficient is less than 1 such that a wound volume less than the total wound volume is filled with the dripping fluid, characterized by this.

27. In the wound therapy system according to claim 25, the fluid dripping coefficient is about 0.2 to about 0.8, characterized by this.

28. In a method for estimating the wound volume of a wound, applying negative pressure to the wound using a negative pressure circuit, operating a pump fluidly coupled to the negative pressure circuit so as to control the negative pressure in the negative pressure circuit, measuring the negative pressure in the negative pressure circuit or at the wound, performing a pressure test procedure including applying a pressure stimulus to the negative pressure circuit, observing the dynamic pressure response of the negative pressure circuit to the pressure stimulus using the measured value of the negative pressure, estimating the wound volume based on the dynamic pressure response A method characterized by including this.

29. The method according to claim 28, wherein the negative pressure circuit comprises a wound dressing sealable to the skin surrounding the wound.

30. The method according to claim 28, wherein the negative pressure circuit comprises at least one of a drip fluid canister for containing drip fluid for delivery to the wound or a removed fluid canister for containing fluid removed from the wound.

31. The method according to claim 28, wherein the negative pressure circuit comprises a tube fluidly connecting the pump to the wound.

32. The method according to claim 28, wherein the negative pressure circuit comprises a wound dressing sealable to the skin surrounding the wound, at least one of a drip fluid canister for containing drip fluid for delivery to the wound or a removed fluid canister for containing fluid removed from the wound, and a tube fluidly connecting the drip fluid canister or the removed fluid canister to the wound dressing.

33. The method according to claim 28, further comprising operating the pump to establish the negative pressure within the negative pressure circuit.

34. The method according to claim 28, wherein the test procedure comprises operating the pump to establish the negative pressure within the negative pressure circuit, and applying the pressure stimulus after the negative pressure has been established within the negative pressure circuit.

35. The method according to claim 28, further comprising operating a valve coupled to the negative pressure circuit to controllably vent the negative pressure circuit.

36. In the method according to claim 35, applying the pressure stimulus comprises opening the valve to allow an air flow into the negative pressure circuit for a predetermined time, and closing the valve after the elapse of the predetermined time.

37. In the method according to claim 36, applying the pressure stimulus comprises waiting for another predetermined time after closing the valve, and repeating the opening step, the closing step, and the waiting step until the negative pressure reaches a threshold pressure value.

38. The method according to claim 36, wherein applying the pressure stimulus further comprises operating the pump while the valve is closed to reduce air leakage into the negative pressure circuit.

39. The method according to claim 36, wherein the dynamic pressure response of the negative pressure circuit is characterized by a purge depth parameter defined as the difference between a measured value of the negative pressure before the valve is opened and a measured value of the negative pressure while the valve is open.

40. The method according to claim 36, wherein the dynamic pressure response of the negative pressure circuit is characterized by a rebound parameter defined as the difference between a measured value of the negative pressure after the valve is closed and a measured value of the negative pressure while the valve is open.

41. The method according to claim 36, wherein the dynamic pressure response of the negative pressure circuit is characterized by a delta parameter defined as the difference between a measured value of the negative pressure before the valve is opened and a measured value of the negative pressure after the valve is closed.

42. The method according to claim 36, wherein the dynamic pressure response of the negative pressure circuit is characterized by a leakage rate parameter defined as the rate at which the negative pressure changes while the valve is closed.

43. The method according to claim 28, further comprising enabling air to leak into the negative pressure circuit at a known rate through an orifice located along the negative pressure circuit.

44. The method according to claim 43, wherein applying the pressure stimulus comprises operating the pump to achieve a predetermined negative pressure within the negative pressure circuit, and stopping the operation of the pump when the predetermined negative pressure is reached within the negative pressure circuit and characterized by including the above.

45. The method according to claim 28, wherein estimating the wound volume based on the dynamic pressure response comprises determining values for one or more parameters characterizing the dynamic pressure response, and applying the values of the one or more parameters as inputs to a model defining the relationship between the one or more parameters and the wound volume and characterized by including the above.

46. The method according to claim 45, wherein the model defining the relationship between the one or more parameters and the wound volume is a polynomial approximation model.

47. The method according to claim 45, wherein the model defining the relationship between the one or more parameters and the wound volume is a neural network.

48. In the method according to claim 45, performing a training procedure including applying the pressure stimulus to a training circuit having a known volume, observing a dynamic pressure response of the training circuit to the pressure stimulus using pressure measurements recorded by a pressure sensor, and associating the known volume with the dynamic pressure response of the training circuit to further generate the model defining the relationship between the one or more parameters and the wound volume.

49. In the method according to claim 48, generating the model comprises repeating the training procedure for a plurality of known volumes, observing the dynamic pressure response of the training circuit for each of the plurality of known volumes, and generating a correlation between the plurality of known volumes and the dynamic pressure response of the training circuit .

50. In the method according to claim 28, performing the pressure test procedure, observing the dynamic pressure response, and estimating the wound volume a plurality of times during wound treatment, and determining the progress of healing based on changes in the wound volume during wound treatment .

51. In the method according to claim 28, determining a volume of a dripping fluid to be delivered to the wound based on the estimated wound volume, and operating the pump to deliver the volume of the dripping fluid to the wound .

52. The method according to claim 51, wherein determining the volume of the dripping fluid to be delivered to the wound comprises multiplying the estimated wound volume by a fluid dripping coefficient.

53. The method according to claim 52, wherein the fluid dripping coefficient is less than 1 such that a wound volume less than the total wound volume is filled with the dripping fluid.

54. The method according to claim 52, wherein the fluid dripping coefficient is from about 0.2 to about 0.

8.

55. In a wound therapy system, a negative pressure circuit configured to apply a negative pressure to a wound; a cannister for containing a dripping fluid for delivery to the wound; a pump operable to deliver the dripping fluid to the wound; a pressure sensor configured to measure the negative pressure in the negative pressure circuit or at the wound; a control device communicatively coupled to the pump and the pressure sensor, executing a pressure test procedure to estimate a wound volume of the wound, determining a volume of the dripping fluid to be delivered to the wound based on the estimated wound volume, and operating the pump to deliver the volume of the dripping fluid to the wound the control device thus configured A wound therapy system, characterized by comprising.

56. The wound therapy system according to claim 55, wherein the control device is configured to determine the volume of the dripping fluid to be delivered to the wound by multiplying the estimated wound volume by a fluid dripping coefficient. A wound therapy system, characterized by that.

57. The wound therapy system according to claim 56, wherein the fluid dripping coefficient is less than 1 such that a wound volume less than the total wound volume is filled with the dripping fluid. A wound therapy system, characterized by that.

58. The wound therapy system according to claim 56, wherein the fluid dripping coefficient is from about 0.2 to about 0.

8. A wound therapy system, characterized by that.

59. The wound therapy system according to claim 55, wherein the negative pressure circuit comprises a wound dressing sealable to the skin surrounding the wound. A wound therapy system, characterized by that.

60. The wound therapy system according to claim 59, wherein the negative pressure circuit comprises a tube fluidly connecting the cannister to the wound dressing. A wound therapy system, characterized by that.

61. The wound therapy system according to claim 55, wherein the control device is configured to operate the pump to establish the negative pressure in the negative pressure circuit. A wound therapy system, characterized by that.

62. The wound therapy system according to claim 55, wherein the pressure test procedure operating the pump to establish the negative pressure in the negative pressure circuit; applying a pressure stimulus to the negative pressure circuit after the negative pressure is established in the negative pressure circuit A wound therapy system, characterized by including.

63. In the wound therapy system according to claim 55, further comprising an orifice located along the negative pressure circuit, the orifice being configured to allow air to leak out of the negative pressure circuit at a known rate. A wound therapy system characterized by that.

64. In the wound therapy system according to claim 63, the pressure test procedure operating the pump to achieve a predetermined negative pressure in the negative pressure circuit; when the predetermined negative pressure is reached in the negative pressure circuit, stopping the operation of the pump and observing the dynamic pressure response of the negative pressure circuit A wound therapy system characterized by including.

65. In the wound therapy system according to claim 55, further comprising a valve coupled to the negative pressure circuit, the valve being operable to controllably vent the negative pressure circuit. A wound therapy system characterized by that.

66. In the wound therapy system according to claim 65, the pressure test procedure opening the valve to allow air flow into the negative pressure circuit for a predetermined time; closing the valve after the elapse of the predetermined time A wound therapy system characterized by including.

67. In the wound therapy system according to claim 66, the pressure test procedure waiting for another predetermined time after closing the valve; repeating the opening step, the closing step, and the waiting step until the negative pressure reaches a threshold pressure value A wound therapy system characterized by including.

68. In the wound therapy system according to claim 66, the pressure test procedure includes operating the pump while the valve is closed to reduce air leakage into the negative pressure circuit. A wound therapy system characterized by that.

69. In the wound therapy system according to claim 66, the pressure test procedure applying a pressure stimulus to the negative pressure circuit; observing the dynamic pressure response of the negative pressure circuit to the pressure stimulus using the pressure measurement value recorded by the pressure sensor; estimating the wound volume of the wound based on the dynamic pressure response A wound therapy system characterized by including.

70. In the wound therapy system according to claim 69, the dynamic pressure response of the negative pressure circuit is characterized by a purge depth parameter defined as the difference between the measured value of the negative pressure before the valve is opened and the measured value of the negative pressure while the valve is open. A wound therapy system characterized by that.

71. In the wound therapy system according to claim 69, the dynamic pressure response of the negative pressure circuit is characterized by a rebound parameter defined as the difference between the measured value of the negative pressure after the valve is closed and the measured value of the negative pressure while the valve is open. A wound therapy system characterized by that.

72. In the wound therapy system according to claim 69, the dynamic pressure response of the negative pressure circuit is characterized by a delta parameter defined as the difference between the measured value of the negative pressure before the valve is opened and the measured value of the negative pressure after the valve is closed. A wound therapy system characterized by that.

73. In the wound therapy system according to claim 69, the dynamic pressure response of the negative pressure circuit is characterized by a leakage rate parameter defined as the rate at which the negative pressure changes while the valve is closed. A wound therapy system characterized by that.

74. In the wound therapy system according to claim 69, estimating the wound volume based on the dynamic pressure response includes determining values for one or more parameters characterizing the dynamic pressure response, and applying the values of the one or more parameters as inputs to a model that defines the relationship between the one or more parameters and the wound volume A wound therapy system characterized by including.

75. In the wound therapy system according to claim 74, the model that defines the relationship between the one or more parameters and the wound volume is a polynomial approximation model. A wound therapy system characterized by that.

76. In the wound therapy system according to claim 74, the model that defines the relationship between the one or more parameters and the wound volume is a neural network. A wound therapy system characterized by that.

77. In the wound therapy system according to claim 74, the control device performs a training procedure including 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 using the pressure measurement values recorded by the pressure sensor, and associating the known volume with the dynamic pressure response of the training circuit to generate the model that defines the relationship between the one or more parameters and the wound volume. A wound therapy system characterized by the above.

78. In the wound therapy system according to claim 77, generating the model includes repeating the training procedure for a plurality of known volumes, observing the dynamic pressure response of the training circuit for each of the plurality of known volumes, and generating a correlation between the plurality of known volumes and the dynamic pressure response of the training circuit. A wound therapy system further characterized by including the above.

79. In the wound therapy system according to claim 55, the control device performs the pressure test procedure to estimate the wound volume multiple times during wound treatment, and determines the progress of healing based on changes in the wound volume during wound treatment. A wound therapy system characterized by being configured as above.

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