Patent Description:
One implementation of the present disclosure is a wound therapy system. The wound therapy system includes a dressing an instillation pump fluidly communicable with the dressing and configured to provide instillation fluid to the dressing, a negative pressure pump fluidly communicable with the dressing and configured to remove air from the dressing, and a control circuit communicably coupled to the instillation pump and the negative pressure pump. The control circuit is configured to control the instillation pump to provide an amount of the instillation fluid to the dressing, provide a soak period, and control the negative pressure pump to provide a cyclic variation of negative pressure at the dressing.

In some embodiments, the cyclic variation of negative pressure includes an oscillation of the pressure at the dressing across a pressure differential. In some embodiments, the pressure differential is approximately <NUM> mmHg. In some embodiments, the pressure differential is within a range between approximately <NUM> mmHg and <NUM> mmHg.

In some embodiments, the cyclic variation of negative pressure includes a first cycle and a second cycle. The pressure differential changes between the first cycle and the second cycle. In some embodiments, the pressure differential oscillates over time.

In some embodiments, the pressure differential is user-selectable. In some embodiments, a frequency of the cyclic variation of negative pressure is user-selectable.

In some embodiments, the dressing includes a perforated layer having a plurality of holes extending therethrough. In some embodiments, the dressing is coupleable to a wound bed. The cyclic variation of negative pressure deforms the wound bed at the holes. In some embodiments, the cyclic variation of negative pressure includes a plurality of cycles. Each cycle does an amount of work of within a range between approximately <NUM> mJ and <NUM> mJ for each of the plurality of holes.

In some embodiments, the control circuit is configured to simultaneously control the negative pressure pump to provide a cyclic variation of negative pressure at the dressing and control the instillation pump to provide the instillation fluid to the dressing.

In some embodiments, at least one of the amount of the instillation fluid or the soak period is user-selectable. In some embodiments, the control circuit is further configured to control the negative pressure pump to provide a substantially constant negative pressure at the dressing.

In some embodiments, the control circuit is further configured to repeatedly cycle through sequentially controlling the instillation pump to provide the amount of the instillation fluid to the dressing, providing the soak period, and controlling the negative pressure pump to provide the cyclic variation of negative pressure at the dressing. In some embodiments, the control circuit is further configured to repeatedly cycle through sequentially controlling the instillation pump to provide the amount of the instillation fluid to the dressing, providing the soak period, controlling the negative pressure pump to provide the cyclic variation of negative pressure at the dressing, and controlling the negative pressure pump to provide a substantially constant negative pressure to the wound bed.

Another implementation of the present disclosure is a method of treating a wound. The method includes providing an instillation pump in fluid communication with a dressing, providing a negative pressure pump in fluid communication with the dressing, supplying, by the instillation pump, an amount of instillation fluid to the dressing, waiting for a soak period, and operating the negative pressure pump to create a cyclic variation of negative pressure at the dressing.

In some embodiments, the cyclic variation of negative pressure includes an oscillation of the pressure at the dressing across a pressure differential. In some embodiments, the pressure differential is approximately <NUM> mmHg. In some embodiments, the pressure differential is in a range between approximately <NUM> mmHg and <NUM> mmHg.

In some embodiments, the cyclic variation of negative pressure includes a first cycle and a second cycle. The method includes changing the pressure differential between the first cycle and the second cycle. In some embodiments, the method includes oscillating the pressure differential over time. In some embodiments, the method includes receiving a user selection of the pressure differential. In some embodiments, the method includes receiving a user selection of a frequency of the cyclic variation of negative pressure.

In some embodiments, the method includes deforming, by the cyclic variation of negative pressure, a wound bed coupled to the dressing. In some embodiments, deforming the wound bed includes drawing the wound bed into a plurality of holes that extend through a layer of the dressing. In some embodiments, the method includes doing an amount of work on the wound bed within a range between approximately <NUM> mJ and <NUM> mJ for each of the plurality of holes for each of multiple cycles of the cyclic variation of negative pressure.

In some embodiments, the method includes simultaneously operating the negative pressure pump to create a cyclic variation of negative pressure at the dressing and controlling the instillation pump to provide the instillation fluid to the dressing.

In some embodiments, the method includes receiving a user selection of at least one of the amount of the instillation fluid or the soak period. In some embodiments, the method includes operating the negative pressure pump to create a substantially constant negative pressure at the dressing.

In some embodiments, the method includes repeatedly cycling through sequentially supplying, by the instillation pump, an amount of instillation fluid to the dressing, waiting for a soak period, and operating the negative pressure pump to create a cyclic variation of negative pressure at the dressing.

In some embodiments, the method includes repeatedly cycling through sequentially supplying, by the instillation pump, an amount of instillation fluid to the dressing, waiting for a soak period, operating the negative pressure pump to create a cyclic variation of negative pressure at the dressing, and operating the negative pressure pump to create a substantially constant negative pressure at the dressing.

Another implementation of the present disclosure is a wound therapy system. The wound therapy system includes an instillation pump fluidly communicable with the dressing and configured to provide instillation fluid to the dressing, a negative pressure pump fluidly communicable with the dressing and configured to remove air from the dressing, and a control circuit communicably coupled to the instillation pump and the negative pressure pump. The control circuit is configured to control the instillation pump to provide an amount of the instillation fluid to the dressing, provide a soak period, and control the negative pressure pump to provide a variation of negative pressure at the dressing, the variation characterized by a waveform.

In some embodiments, the waveform includes an amplitude having a maximum at a high pressure value and a minimum at a low pressure value and a frequency. In some embodiments, the amplitude is variable in a repeating pattern. In some embodiments, the frequency is variable in a repeating pattern. In some embodiments, the amplitude is variable in a first repeating pattern and the frequency is variable in a second repeating pattern. In some embodiments, the waveform is user-selectable.

In some embodiments, the control circuit is configured to simultaneously control the negative pressure pump to provide the variation of negative pressure at the dressing and control the instillation pump to provide the instillation fluid to the dressing.

Referring to <FIG> and <FIG>, a negative pressure and instillation wound therapy (NPIWT) system <NUM> is shown, according to exemplary embodiments. <FIG> shows a perspective view of the NPIWT system <NUM>, according to an exemplary embodiment. <FIG> shows a block diagram of the NPIWT system <NUM>, according to an exemplary embodiment. The NPIWT system <NUM> is shown to include a therapy unit <NUM> fluidly coupled to a dressing <NUM> via a vacuum tube <NUM> and an instillation tube <NUM>. The NPIWT system <NUM> is also shown to include an instillation fluid source <NUM> fluidly coupled to the instillation tube <NUM>. The NPIWT system <NUM> is configured to provide negative pressure wound therapy at a wound bed by reducing the pressure at the dressing <NUM> relative to atmospheric pressure. The NPIWT system <NUM> is also configured to provide instillation therapy by providing instillation fluid to the dressing <NUM>. Furthermore, as described in detail herein, the NPIWT system <NUM> is configured to provide debridement of the wound bed and removal of undesirable fluid and debris from the wound bed.

The dressing <NUM> is coupleable to a wound bed, i.e., a location of a wound (e.g., sore, laceration, burn, etc.) on a patient. The dressing <NUM> may be substantially sealed over the wound bed such that a pressure differential may be maintained between the atmosphere and the wound bed (i.e., across the dressing <NUM>). The dressing <NUM> may be coupled to the vacuum tube <NUM> and the instillation tube <NUM>, for example to place the vacuum tube <NUM> and/or the instillation tube <NUM> in fluid communication with the wound bed. An example embodiment of dressing <NUM> is shown in <FIG> and described in detail with reference thereto. In some embodiments, the dressing <NUM> may be a V. VERAFLO™ dressing by Acelity or a V. VERAFLO CLEANSE CHOICE™ dressing by Acelity.

The therapy unit <NUM> includes a negative pressure pump <NUM> (shown in <FIG> and obscured within the therapy unit <NUM> in the perspective view of <FIG>) configured to pump air, wound exudate, and/or other debris (e.g., necrotic tissue) and/or fluids (e.g., instillation fluid) out of the dressing <NUM> via the vacuum tube <NUM>, thereby creating a negative pressure at the dressing <NUM>. The negative pressure pump <NUM> is fluidly communicable with the vacuum tube <NUM> and the dressing <NUM>. Wound exudate and/or other debris and/or fluids removed from the wound bed by the negative pressure pump <NUM> may be collected in a canister <NUM> located on the therapy unit <NUM>.

Operating the negative pressure pump <NUM> may therefore both create a negative pressure at the wound bed and remove undesirable fluid and debris from the wound bed. In some cases, operating the negative pressure pump <NUM> may cause deformation of the wound bed and/or provide other energy to the wound bed to facilitate debridement and healing of the wound bed. As described in detail below, the negative pressure pump <NUM> may be operated in accordance with one or more dynamic pressure control approaches that may facilitate wound healing.

The therapy unit <NUM> also includes an instillation pump <NUM>. The instillation pump <NUM> is configured to selectively provide instillation fluid from the instillation fluid source <NUM> to the dressing <NUM>. The instillation pump <NUM> is operable to control the timing and amount (volume) of instillation fluid provided to the dressing <NUM>. As described in detail below, the instillation pump <NUM> may be controlled in coordination with the negative pressure pump <NUM> to provide one or more wound treatment cycles that may facilitate wound healing.

The therapy unit <NUM> also includes an input/output device <NUM>. The input/output device <NUM> is configured to provide information relating to the operation of the NPIWT system <NUM> to a user and to receive user input from the user. The input/output device <NUM> may allow a user to input various preferences, settings, commands, etc. that may be used in controlling the negative pressure pump <NUM> and the instillation pump <NUM> as described in detail below. The input/output device <NUM> may include a display (e.g., a touchscreen), one or more buttons, one or more speakers, and/or various other devices configured to provide information to a user and/or receive input from a user.

As shown in <FIG>, the therapy unit <NUM> is also shown to include one or more sensors <NUM> and a control circuit <NUM>. The sensor(s) <NUM> may be configured to monitor one or more of various physical parameters relating to the operation of the NPIWT system <NUM>. For example, the sensor(s) <NUM> may measure pressure at the vacuum tube <NUM>, which may be substantially equivalent and/or otherwise indicative of the pressure at the dressing <NUM>. As another example, the sensor(s) <NUM> may measure an amount (e.g., volume) of instillation fluid provided to the dressing <NUM> by the instillation pump <NUM>. The sensor(s) <NUM> may provide such measurements to the control circuit <NUM>.

The control circuit <NUM> is configured to control the operation of the therapy unit <NUM>, including by controlling the negative pressure pump <NUM>, the instillation pump <NUM>, and the input/output device <NUM>. The control circuit <NUM> may receive measurements from the sensor(s) <NUM> and/or user input from the input/output device <NUM> and use the measurements and/or the user input to generate control signals for the instillation pump <NUM> and/or the negative pressure pump <NUM>. As described in detail with reference to <FIG> below, the control circuit <NUM> may control the negative pressure pump <NUM> and the instillation pump <NUM> to provide various combinations of various instillation phases, soak periods, and negative pressure phases to support and encourage wound healing.

Referring now to <FIG>, graphical representations of constant negative pressure therapy and dynamic pressure control therapy are shown, according to exemplary embodiments. A first graph <NUM> illustrates constant negative pressure therapy while a second graph <NUM> illustrates dynamic pressure control therapy. The graphs <NUM>-<NUM> show pressure at the dressing <NUM> on the vertical axis and time on the horizontal axis. The graphs <NUM>-<NUM> both include a pressure line <NUM> that illustrates the pressure at the dressing <NUM> over time. The control circuit <NUM> is configured to control the negative pressure pump <NUM> to achieve the pressure trajectories illustrated by the pressure lines <NUM>.

As illustrated by graph <NUM>, the control circuit <NUM> may control the negative pressure pump <NUM> to remove air, fluid, debris, etc. from the dressing <NUM> to reduce the pressure at the dressing <NUM> from atmospheric pressure to a target negative pressure. The control circuit <NUM> may then control the negative pressure pump <NUM> to maintain the pressure at the dressing <NUM> at approximately the target negative pressure. In some embodiments, the control circuit <NUM> may use pressure measurements from the sensor(s) <NUM> as feedback to facilitate maintenance of the pressure at approximately the target negative pressure. In the embodiment shown, the target negative pressure may be any value from approximately <NUM> mmHg to <NUM> mmHg. For example, in some embodiments, the target negative pressure may be user-selectable via the input/output device <NUM>.

As illustrated by graph <NUM>, the control circuit <NUM> may control the negative pressure pump <NUM> to provide a cyclic variation of negative pressure at the dressing <NUM>. The control circuit <NUM> may control the negative pressure pump <NUM> to remove air, fluid, debris, etc. from the dressing <NUM> to reduce the pressure at the dressing <NUM> from atmospheric pressure to a target negative pressure (e.g., a high pressure value). The control circuit <NUM> may then control the negative pressure pump <NUM> to facilitate the pressure at the dressing <NUM> in returning to a low pressure value. That is, the negative pressure pump <NUM> may allow the pressure to drift back towards atmospheric pressure, for example by putting the dressing in fluid communication with the atmosphere, allowing air to leak into the dressing <NUM>, and/or the negative pressure pump <NUM> pumping air into the dressing <NUM>. When the pressure at the dressing <NUM> reaches a low pressure value (e.g., as detected by the sensor(s) <NUM>) the control circuit <NUM> may control the negative pressure pump <NUM> to remove air, fluid, debris, etc. from the dressing <NUM> to reduce the pressure at the dressing <NUM> from the low pressure value to the target negative pressure (e.g., the high pressure value).

As illustrated by graph <NUM>, the control circuit <NUM> may cause the cycle between a low pressure value and a high pressure value to be repeated multiple times. The low pressure value and the high pressure value may be user selectable. For example, the low pressure value may be approximately <NUM> mmHg and the high pressure value may be in the range of approximately <NUM> mmHg to approximately <NUM> mmHg. In some embodiments, the low pressure value may be <NUM> mmHg (i.e., atmospheric pressure). In other words, the control circuit <NUM> may control the negative pressure pump <NUM> to oscillate the pressure at the dressing <NUM> across a pressure differential. The pressure differential may be any value within a range between approximately <NUM> mmHg and approximately <NUM> mmHg, for example <NUM> mmHg (i.e., an oscillation between <NUM> mmHg and <NUM> mmHg is an oscillation across a pressure differential of <NUM> mmHg).

Although graphs <NUM> and <NUM> show linear transitions (i.e., constant slopes) between pressure values, it should be understood that various other pressure trajectories (represented by pressure line <NUM>) may be provided by various embodiments. For example, the pressure line <NUM> may take a sinusoidal form in alternative embodiments of graph <NUM>. Furthermore, while the example of graph <NUM> shows substantially equivalent rise times (i.e., the time for pressure to change from the low pressure value to the high pressure value) and fall times (i.e., the time for pressure to change from the high pressure value to the low pressure value), it should be understood that various relative rise times and fall times may be used. For example, a rise time and/or fall time may be selected by a user via the input/output device <NUM>. The control circuit <NUM> may control the negative pressure pump <NUM> to achieve the user-selected rise time and/or fall time. Various additional embodiments of dynamic pressure control are illustrated at <FIG> and described in detail with reference thereto.

Referring now to <FIG>, a flowchart depicting a process <NUM> for treating a wound using the NPIWT system <NUM> of <FIG> is shown, according to an exemplary embodiment. Process <NUM> is shown as a cycle through three phases, namely an instillation phase <NUM>, a soak phase <NUM>, and a dynamic pressure control phase <NUM>. The control circuit <NUM> may be configured to control the instillation pump <NUM> and the negative pressure pump <NUM> to execute process <NUM>. Advantageously, the process <NUM> may provide improved wound healing as indicated by experimental results shown in <FIG> and described with reference thereto below.

At the instillation phase <NUM>, the control circuit <NUM> controls the instillation pump <NUM> to provide instillation fluid from the instillation fluid source <NUM> to the dressing <NUM> via the instillation tube <NUM>. At the instillation phase <NUM>, the control circuit <NUM> may control the instillation pump <NUM> to provide a particular amount (e.g., volume) of instillation fluid and/or to provide instillation fluid for a particular duration of time. Instillation fluid may thereby be placed in contact with the wound bed. The amount of instillation fluid provided at the instillation phase <NUM> and/or the duration of time of the instillation phase <NUM> may be user-selectable (e.g., by a doctor, nurse, caregiver, patient) via the input/output device <NUM> and/or otherwise customizable (e.g., for various wound types, for various types of instillation fluid).

At the soak phase <NUM>, the control circuit <NUM> provides a soak period between the instillation phase <NUM> and the dynamic pressure control phase <NUM>. During the soak phase <NUM>, the control circuit <NUM> controls the instillation pump <NUM> to prevent additional fluid from being added to the dressing <NUM> and prevents the negative pressure pump <NUM> from operating. The soak phase <NUM> thereby provides a soak period during which the instillation fluid added at the instillation phase <NUM> can soak into the wound bed, for example to soften, loosen, dissolve, etc. unwanted scar tissue or wound exudate. The duration of the soak period may be user-selectable via the input/output device <NUM> and/or otherwise customizable (e.g., for various wound types, for various types of instillation fluid). For example, the soak period may have a duration of between thirty seconds and ten minutes.

At the dynamic pressure control phase <NUM>, the control circuit <NUM> controls the negative pressure pump <NUM> to create a cyclic variation of negative pressure at the dressing <NUM>. The negative pressure pump <NUM> may operate to cause the pressure at the dressing <NUM> to oscillate between a low pressure value and a high pressure value, for example as illustrated by pressure line <NUM> on graph <NUM> of <FIG>. The frequency of such oscillations may vary in various embodiments and/or may be user-selectable via the input/output device <NUM>. The low pressure value, high pressure value, and/or pressure differential may also be customizable (e.g., user-selectable via the input/output device <NUM>). In some embodiments, the instillation pump <NUM> is controlled to provide instillation fluid to the dressing <NUM> during the dynamic pressure control phase <NUM>.

During the dynamic pressure control phase <NUM>, the negative pressure pump <NUM> is controlled to remove air, fluid, and/or debris from the wound bed and the dressing <NUM>. In some cases, the negative pressure pump <NUM> may remove the instillation fluid added at the instillation phase <NUM>. The negative pressure pump <NUM> may also remove tissue softened, dissolved, etc. by the instillation fluid during the soak phase <NUM>. Under dynamic pressure control (e.g., as shown on graph <NUM> of <FIG>), the cyclic variation of negative pressure may provide additional energy to the wound bed to facilitate debridement and encourage wound healing. The instillation phase <NUM>, the soak phase <NUM>, and the dynamic pressure control phase <NUM> thereby work together to provide improved wound therapy.

As illustrated by <FIG>, the control circuit <NUM> may control the NPIWT system <NUM> to repeatedly cycle through the sequence of the instillation phase <NUM>, the soak phase <NUM>, and the dynamic pressure control phase <NUM>. Various parameters (e.g., amount of instillation fluid provide, the length of the soak phase, the low pressure value, the high pressure value, the oscillation frequency) of the phases <NUM> may remain constant between cycles, may vary between cycles, or some combination thereof. Accordingly, the process <NUM> is highly configurable for various wound types, wound sizes, patients, instillation fluids, dressings <NUM>, etc..

Referring now to <FIG>, experimental results showing improved wound healing using process <NUM> and the NPIWT system <NUM> are shown, according to an exemplary embodiment. An animal study was conducted in which the NPIWT system <NUM> was used to treat wounds under various control approaches, described below. After a period of time, the thickness of granulation tissue on the wound was then measured, which indicates an amount of wound healing (i.e., thicker granulation tissue corresponds to more healing).

<FIG> shows a graph <NUM> and table <NUM> that indicate that process <NUM> may provide higher rates of wound healing than alternative wound therapy approaches. The table <NUM> displays the data represented in the graph <NUM>. The graph <NUM> includes a first bar <NUM> that shows the mean granulation tissue thickness in the experiment for a wound treated by the NPIWT system <NUM> using constant negative pressure (e.g., <NUM> mmHg), for example as illustrated by graph <NUM> of <FIG>. The graph <NUM> also includes a second bar <NUM> that shows the mean granulation tissue thickness in the experiment for a wound treated by the NPIWT system <NUM> using intermittent constant negative pressure, in which constant negative pressure (e.g., <NUM> mmHg) is applied for intermittent time periods separated by periods where the negative pressure pump <NUM> is turned off. The graph <NUM> includes a third bar <NUM> that shows the mean granulation tissue thickness in the experiment for a wound treated by the NPIWT system <NUM> using dynamic pressure control, for example as illustrated by graph <NUM> of <FIG> (e.g., with a low pressure value of <NUM> mmHg and a high pressure value of <NUM> mmHg). Bars <NUM>-<NUM> correspond to negative pressure wound therapy without instillation therapy.

The graph <NUM> also includes a fourth bar <NUM> that shows the mean granulation tissue thickness in the experiment for a wound treated by the NPIWT system <NUM> using a combination of instillation therapy and constant negative pressure. The graph <NUM> also includes a fifth bar <NUM> that shows the mean granulation tissue thickness for a wound treated by the NPIWT system <NUM> executing process <NUM>. Accordingly, the fourth bar <NUM> and the fifth bar <NUM> correspond to negative pressure wound therapy with instillation therapy.

As shown in the graph <NUM> of <FIG>, the fifth bar <NUM> is the largest, indicating that process <NUM> facilitates greater wound healing relative to the wound therapy approaches corresponding to the first bar <NUM>, second bar <NUM>, third bar <NUM>, and fourth bar <NUM>.

Referring now to <FIG>, detailed views of an embodiment of the dressing <NUM> are shown, according to an exemplary embodiment. <FIG> shows a cross-sectional side view of the dressing <NUM> while <FIG> shows a bottom view of the dressing <NUM> (i.e., a view of the wound-facing surface of the dressing <NUM> when applied to a patient). The dressing <NUM> of <FIG> may facilitate debridement and cleansing of a wound bed when used in conjunction with process <NUM> and/or various other wound therapy approaches described herein. The dressing <NUM> of <FIG> may substantially similar to the dressing(s) shown and described in detail in "WOUND DRESSING WITH SEMI-RIGID SUPPORT TO INCREASE DISRUPTION USING PERFORATED DRESSING AND NEGATIVE PRESSURE WOUND THERAPY, Applicant Docket Number VAC. 1615PRO, <CIT>, incorporated by reference herein in its entirety.

As shown in <FIG>, the dressing <NUM> includes a drape <NUM> coupled to a connection pad <NUM>, an intermediate layer <NUM> coupled to the drape <NUM>, a perforated layer <NUM> coupled to the intermediate layer <NUM>, and a wound contact layer <NUM> coupled to the perforated layer <NUM>. The drape <NUM> is sealable over a wound bed to couple the dressing <NUM> to the wound bed in a substantially airtight manner to allow a pressure differential to be maintained across the drape <NUM>. The connection pad <NUM> is coupled to the drape <NUM>, the vacuum tube <NUM> and the instillation tube <NUM>. The connection pad <NUM> is positioned at a passage <NUM> through the drape <NUM>. The connection pad <NUM> allows for removal of air, fluid, wound exudate, etc. from the dressing <NUM> via the vacuum tube <NUM> and allows for addition of instillation fluid to the dressing <NUM> via the instillation tube <NUM>.

The drape <NUM> is positioned along the intermediate layer <NUM>. The intermediate layer <NUM> may be a support layer and/or a manifolding layer. The intermediate layer <NUM> allows air, fluid, debris, etc. to flow therethrough, i.e., to flow between the connection pad <NUM> and the perforated layer <NUM>. The perforated layer <NUM> is positioned along the intermediate layer <NUM> and configured to allow a negative pressure to be distributed across the wound bed and to allow fluid, debris, etc. to be pass therethrough. A wound contact layer <NUM> may be coupled to the perforated layer <NUM> and may be configured to minimize adherence of the dressing <NUM> to the wound bed.

The perforated layer <NUM> includes multiple holes <NUM> extending therethrough. In various embodiments, various numbers of the holes <NUM> are arranged in various positions on the perforated layer <NUM>. As described in detail below, when negative pressure is established at the dressing <NUM>, the wound bed may be caused to deform into the holes <NUM> by the negative pressure. Deformation of the wound bed into the multiple holes <NUM> may contribute to the breakdown of scar tissue or other unwanted tissue or debris at the wound bed. The perforated layer <NUM> may thereby facilitate debridement and/or cleansing of the wound bed to promote wound healing.

Referring now to <FIG>, a visualization of wound bed deformation into the multiple holes <NUM> of the perforated layer <NUM> of the dressing <NUM> of <FIG> under dynamic pressure control is shown, according to an exemplary embodiment. <FIG> shows a schematic diagram <NUM> illustrating that wound bed deformation may be quantified by a measurement of a deformation height from a base <NUM> of the wound bed to a deformation peak <NUM> of the wound bed. The deformation height may correspond to a vertical displacement between a point on the wound bed aligned with one of the multiple holes <NUM> and a point on the wound bed not aligned with one of the multiple holes <NUM>, such that the deformation height measures how far the wound bed extends into the hole <NUM>.

<FIG> also includes a graph <NUM> that illustrates deformation height over time under dynamic pressure control. In the example shown, the control circuit <NUM> controls the negative pressure pump <NUM> to provide a cyclic variation of negative pressure at the dressing <NUM> that acts on the wound bed. In this example, the cyclic variation of negative pressure follows the waveform shown in graph <NUM> of <FIG> and oscillates between a low pressure value of <NUM> mmHg and a high pressure value of <NUM> mmHg. Furthermore, in the example shown, the graph <NUM> is based upon experimental results using a simulated wound material known as Dermasol.

The graph <NUM> includes a deformation height line <NUM> that shows that the deformation height approximately tracks the waveform of graph <NUM>. The deformation height increases as negative pressure increases and decreases as negative pressure decrease. In the example shown by the graph <NUM>, the deformation height line <NUM> reaches maximums at approximately <NUM> millimeters and minimums at approximately <NUM> millimeters. In other words, in the example shown, the wound bed deforms by approximately <NUM> millimeters into the holes <NUM> under high negative pressure and by approximately <NUM> millimeter under low negative pressure. <FIG> also includes a first depiction <NUM> of the wound bed while at a maximum deformation and a second depiction <NUM> of the wound bed while at a minimum deformation.

The deformation of the wound bed may be characterized in terms of the work provided to the wound bed and the elastic energy stored in the deformed tissue. The following paragraphs describe the Applicant's present understanding of the relationship between applied negative pressure, wound bed deformation, work, and elastic energy.

During negative pressure wound therapy, the tissue in the wound bed is displaced by applied pressure. The work W performed by the applied pressure is related to a change in the elastic energy ΔU stored in the deformation tissue as: <MAT>.

This relationship can be employed to predict tissue deformations from a given applied pressure. To illustrate this, a simple calculation may be performed using experimentally determined values for a model wound material Dermasol. Given a constant value of the applied pressure P, a model wound bed of initial height L and made of Dermasol with Young's modulus E, a fractional change of length ΔL/L of a region with cross-sectional area A will occur. The Applicant believes that the work performed by the applied pressure and associated change in tissue elastic energy is given by: <MAT>.

This relationship is validated with the experimentally determined values reported in the following table:.

While the work performed by the applied pressure and the elastic energy in the deformed tissue are of the same magnitude, there is an approximately <NUM>% discrepancy. The resolution of this discrepancy will require the following improvements: First, more accurate measurement of the elastic properties of the Dermosol may be required. The Young's modulus and Poisson's ration, the latter having been neglected above in the analysis above for the sake of simplicity, can be accurately determined using an oscillatory rheometer. Second, inclusion of the deformation of the dressing may also be required.

Knowing the elastic properties of Dermosol, the geometry of the wound model, and the applied pressure, the displacement of the wound is calculable. This face is reflected in the relationships by Equations (<NUM>), i.e., <MAT>.

Here the displacement ΔL is a function of the initial geometry L, the applied pressure P, and the elastic property E. Using more detailed information from the rheometry measurements suggested above and the computational method Finite Element Analysis, the deformation field of the wound model may be calculated. This technique may be a useful tool for optimizing negative pressure wound therapy products, for example the NPIWT system <NUM> and components thereof.

The total amount of work done on a wound bed may also be calculated using this approach. For example, at <NUM> mJ per perforation (i.e., as calculated at Equations (<NUM>)) and a dressing <NUM> with twenty-three holes <NUM>, the negative pressure pump <NUM> does approximately <NUM> mJ of work on the wound bed per cycle of the cyclic variation of negative pressure (i.e., for each period of the waveform shown on graph <NUM>). If five cycles are provided in a phase (e.g., during the dynamic pressure control phase <NUM>) the work increases to approximately <NUM> * <NUM> mJ = <NUM> mJ for the phase. The negative pressure pump <NUM> may therefore do substantially more work on the wound bed under dynamic pressure control than under a constant negative pressure approach.

Referring now to <FIG>, a process <NUM> for providing wound therapy with the NPIWT system <NUM> is shown, according to an exemplary embodiment. The control circuit <NUM> may be configured to control the instillation pump <NUM> and the negative pressure pump <NUM> to execute process <NUM>. In some embodiments, the process <NUM> is carried out with a dressing <NUM> that includes the perforated layer <NUM> with holes <NUM> as in <FIG>. As described in detail below, provides <NUM> provides wound therapy having a scrub cycle and an instillation cycle.

At step <NUM>, wound therapy is initiated. The dressing <NUM> is sealed over a wound bed and coupled to the therapy unit <NUM> by the vacuum tube <NUM> and the instillation tube <NUM>. To cause wound therapy to be initiated, a user may input a command via the input/output device <NUM> to initiate therapy (e.g., to turn on). In response, the control circuit <NUM> may be activated and may proceed to control the instillation pump <NUM> and the negative pressure pump <NUM> as described in the following paragraphs.

At step <NUM>, the control circuit <NUM> determines whether to initiate a scrub cycle. The scrub cycle includes steps <NUM>-<NUM> of process <NUM>, described in detail below. The scrub cycle provides enhanced scrubbing, debridement, cleansing, etc. of the wound bed. Accordingly, the control circuit <NUM> may determine to initiate the scrub cycle based on an indication that the wound bed requires scrubbing, debridement, cleansing, etc., for example based on information about the type of wound being treated. In some embodiments, the control circuit <NUM> causes the input/output device <NUM> to prompt a user to select whether to initiate the scrub cycle.

If the control circuit <NUM> determines that the scrub cycle will be initiated, at step <NUM> the control circuit <NUM> controls the instillation pump <NUM> to provide an instillation phase. During step <NUM> (i.e., during the instillation phase), instillation fluid is added to the dressing <NUM>. The control circuit <NUM> may control the instillation pump <NUM> to provide a particular amount of the instillation fluid to the dressing <NUM> and/or provide instillation fluid to the dressing <NUM> for a particular amount of time. The amount of fluid added and/or the duration of the instillation phase may be user-selectable via the input/output device <NUM> and/or otherwise customizable (e.g., for various wound types, for various types of instillation fluid).

At step <NUM>, the instillation fluid added at step <NUM> is allowed to soak into the wound bed in a soak phase. During the soak phase (i.e., at step <NUM>), the control circuit <NUM> may control the instillation pump <NUM> to prevent instillation fluid from being added to the dressing <NUM> and may prevent operation of the negative pressure pump <NUM>. The control circuit <NUM> thereby provides a soak period during which the instillation fluid added at step <NUM> can soak into the wound bed, for example to soften, loosen, dissolve, etc. unwanted scar tissue or wound exudate. The duration of the soak period may be user-selectable via the input/output device <NUM> and/or otherwise customizable (e.g., for various wound types, for various types of instillation fluid). For example, the soak period may have a duration of between thirty seconds and ten minutes.

At step <NUM>, the control circuit <NUM> controls the negative pressure pump <NUM> to provide a cyclic variation of negative pressure at the dressing <NUM> and the wound bed in a dynamic pressure control phase. In embodiments where the dressing <NUM> includes holes <NUM> as in <FIG>, the wound bed may be deformed into the holes <NUM> during step <NUM>. For example, the wound deformation height may increase as the negative pressure at the dressing <NUM> increases and may decrease as the negative pressure at the dressing <NUM> decreases. In some embodiments, as described above with reference to <FIG>, the negative pressure may do work on the wound bed in a range of approximately <NUM> mJ to <NUM> mJ per hole <NUM> for each cycle of the cyclic variation of negative pressure (e.g., for each period of the waveform shown on graph <NUM> of <FIG>). In various embodiments, the negative pressure may do work on the wound bed in a range of approximately <NUM> mJ and <NUM> mJ per hole <NUM> for each cycle. As another example, with a diameter of the holes <NUM> of approximately <NUM> and a negative pressure of <NUM> mmHg, work in a range of approximately <NUM> mJ to <NUM> mJ can be achieved. Higher amounts of work may be provided by increasing the size of the holes <NUM> and by increasing the pressure (in absolute value). The combination of dynamic pressure control and the perforated layer <NUM> of the dressing <NUM> provides increased scrubbing and debridement of the wound bed at step <NUM>. Accordingly, step <NUM> may cause the separation of a substantial amount of debris, scar tissue, etc. from the wound bed.

In some embodiments, the dynamic pressure control phase of step <NUM> includes controlling the negative pressure pump <NUM> to provide a waveform having hold periods at high pressure values and/or low pressure values, for example as shown in <FIG> and described with reference thereto. In some embodiments, the dynamic pressure control phase of step <NUM> includes controlling the negative pressure pump <NUM> to provide an aggressive cleanse waveform, for example as shown in <FIG> and described with reference thereto. In some embodiments, the dynamic pressure control phase of step <NUM> includes varying a high pressure value and/or pressure differential of the cyclic variation of negative pressure over time, for example as shown in <FIG> and described in detail with reference thereto. The duration of step <NUM> may be user-selectable and/or otherwise customizable. In various embodiments, the dynamic pressure control phase may have a duration between one minute and three hours, for example three minutes. In some embodiments, the dynamic pressure control phase of step <NUM> includes controlling the instillation pump <NUM> to provide instillation fluid to the dressing <NUM> during step <NUM>.

At step <NUM>, the control circuit <NUM> determines whether to continue the scrub cycle. In some embodiments, the control circuit <NUM> may determine whether to continue the scrub cycle based on a preset number of desired scrub cycles. For example, the control circuit <NUM> may count the number of times that steps <NUM>-<NUM> are completed and continue the scrub cycle until that number reaches a preset threshold (e.g., a threshold number input by a user). In other embodiments, at step <NUM> the control circuit <NUM> may cause the input/output device <NUM> to prompt a user for input indicating whether to continue the scrub cycle and determine whether to content the scrub cycle based on the user input.

If the control circuit <NUM> makes a determine a determination to continue the scrub cycle, at step <NUM> the control circuit <NUM> controls the negative pressure pump <NUM> to provide a fluid removal phase. During the fluid removal phase, the negative pressure pump <NUM> is controlled to remove fluid, debris, etc. from the dressing <NUM>. The fluid, debris, etc. removed from the dressing <NUM> by the negative pressure pump <NUM> at step <NUM> may include the instillation fluid added at step <NUM> and debris, scar tissue, etc. separated from the wound bed at step <NUM>. Step <NUM> thereby provides a fluid removal phase in which undesirable fluid and debris is removed from the dressing <NUM> and prepares NPIWT system <NUM> to repeat the scrub cycle.

Following the fluid removal phase of step <NUM>, the process <NUM> returns to cycle through step <NUM>, step <NUM>, and step <NUM>. The scrub cycle (i.e., steps <NUM>-<NUM>) may be repeated any number of times until, at an instance of step <NUM>, the control circuit <NUM> determines that the scrub cycle will no longer be continued.

If the control circuit <NUM> determines that the scrub cycle will not be continued at step <NUM>, process <NUM> proceeds to step <NUM> where a constant negative pressure phase is provided to initiate an instillation cycle (steps <NUM>-<NUM>). At step <NUM>, the control circuit <NUM> controls the negative pressure pump <NUM> to provide an approximately constant negative pressure (e.g., <NUM> mmHg, <NUM> mmHg, etc.), for example as shown in graph <NUM> of <FIG>. The control circuit <NUM> may receive pressure measurements from the sensor(s) <NUM> for use as feedback in a control loop for the negative pressure pump <NUM>. The negative pressure pump <NUM> may remove fluid, debris, etc. provided to the dressing <NUM> and/or separated or exuded from the wound bed. The duration of the constant negative pressure phase may be user-selectable via input/output device <NUM> and/or otherwise customizable.

At step <NUM>, the control circuit <NUM> provides an instillation phase by controlling the instillation pump <NUM> to provide instillation fluid to the dressing <NUM>. In some embodiments, the control circuit <NUM> behaves substantially the same at step <NUM> is as at step <NUM>. The instillation pump <NUM> may be controlled to provide a particular amount of the instillation fluid to the dressing <NUM> and/or provide instillation fluid to the dressing <NUM> for a particular amount of time. The amount of fluid added and/or the duration of the instillation phase may be user-selectable via the input/output device <NUM> and/or otherwise customizable (e.g., for various wound types, for various types of instillation fluid).

At step <NUM>, the control circuit <NUM> provides a soak phase by controlling the instillation pump <NUM> to prevent the addition of instillation fluid to the dressing <NUM> for a soak period and to prevent operation of the negative pressure pump <NUM> for the soak period. In some embodiments, the control circuit <NUM> behaves substantially the same at step <NUM> as at step <NUM>. The control circuit <NUM> provides a soak period during which the instillation fluid added at step <NUM> can soak into the wound bed, for example to soften, loosen, dissolve, etc. unwanted scar tissue or wound exudate or to provide other therapy to the wound bed. The duration of the soak period may be user-selectable via the input/output device <NUM> and/or otherwise customizable (e.g., for various wound types, for various types of instillation fluid). For example, the soak period may have a duration of between thirty seconds and ten minutes.

At step <NUM>, the control circuit <NUM> determines whether to return to the scrub cycle or to repeat the instillation cycle (i.e., steps <NUM>-<NUM>). For example, the control circuit <NUM> may repeat the instillation cycle for a preset or user-selected number of times before repeating the instillation cycle. In some embodiments, at step <NUM> the control circuit <NUM> causes the input/output device <NUM> to prompt a user to input an indication of whether to return to the scrub cycle or to repeat the instillation cycle. If the control circuit <NUM> makes a determination to not return to the scrub cycle, process <NUM> returns to step <NUM> to restart the instillation cycle. If the control circuit <NUM> makes a determination to return to the scrub cycle, the process <NUM> returns to step <NUM> to reenter the scrub cycle.

The control circuit <NUM> may thereby control the instillation pump <NUM> and the negative pressure pump <NUM> to provide various numbers of scrub cycles and instillation cycles in various orders. Furthermore, it should be understood that the duration of each phase (i.e., steps <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>) is highly variable. For example, the duration of one or more phases may change between sequential cycles. Various other parameters (e.g., low pressure values, high pressure values, frequency, waveform, amount of instillation fluid, etc.) may also vary between cycles. Accordingly, process <NUM> is highly configurable and customizable to provide negative pressure and instillation wound therapy well suited to a variety of wound types, patients, stages of healing, etc..

Referring now to <FIG> an alternative embodiment of a dynamic pressure control waveform is shown, according to an exemplary embodiment. <FIG> shows a graph <NUM> that includes a pressure line <NUM> that charts negative pressure over time. In the embodiment of <FIG>, the pressure line <NUM> increases from atmospheric pressure to a high pressure value (e.g., <NUM> mmHg of negative pressure) and remains at the high pressure value for a first hold period <NUM> before decreasing to a low pressure value (e.g., <NUM> mmHg). The pressure line <NUM> then remains at the low pressure value for a second hold period <NUM> before returning to the high pressure value. This cycle may be repeated any number of times. The graph <NUM> also includes a deformation height line <NUM> that charts the deformation height of the wound bed over time in response to the changes in negative pressure.

The control circuit <NUM> may control the negative pressure pump <NUM> to provide negative pressure that substantially tracks the pressure line <NUM> of <FIG>. In such a case, the first hold period <NUM> may allow time for the wound bed to reach a maximum deformation height (e.g., shown as <NUM>) before the negative pressure is reduced. The second hold period <NUM> may allow the wound bed to reach a minimum deformation height (e.g., shown as <NUM>) before the negative pressure is increased. The dynamic pressure control waveform of <FIG> thereby accounts for a lag time between a change in pressure and a change in tissue deformation, which may help to maximize the amount of work done on the wound bed. In various embodiments, the first hold period <NUM> and the second hold period <NUM> may have the same duration or different durations. In various embodiments, the maximum deformation height and the minimum deformation height have various values. A dynamic pressure control approach having hold periods <NUM>, <NUM> may be applied in process <NUM> (at dynamic pressure control phase <NUM>) and/or process <NUM> (at dynamic pressure control phase <NUM>), and may be used with the perforated layer <NUM> of the dressing <NUM>.

Referring now to <FIG>, a graphical representation of aggressive cleanse pressure control is shown, according to an exemplary embodiment. <FIG> includes a graph <NUM> that charts negative pressure over time. Graph <NUM> includes a dynamic pressure control line <NUM> and an aggressive cleanse pressure control line <NUM>. The dynamic pressure control line <NUM> corresponds to the pressure line <NUM> on graph <NUM> of <FIG> and is included in graph <NUM> for the sake of comparison to the aggressive cleanse pressure control line <NUM>. The dynamic pressure control line <NUM> shows that, under dynamic pressure control, the control circuit <NUM> may control the negative pressure pump <NUM> to draw a negative pressure at the dressing <NUM> from atmospheric pressure to a high pressure value, allow the negative pressure to return to a low pressure value, draw the negative pressure back to the high pressure value, and so on. In other words, the dynamic pressure control line <NUM> illustrates a waveform having a frequency and an amplitude (i.e., a pressure differential). The amplitude of the dynamic pressure control line <NUM> ranges from a minimum at the low pressure value to a maximum at the high pressure value.

The aggressive cleanse pressure control line <NUM> illustrates an alternative pressure control approach which may do an increased amount of work on the wound bed and provide for increased debridement of the wound bed. The aggressive cleanse pressure control line <NUM> illustrates that the control circuit <NUM> may control the negative pressure pump <NUM> to draw a negative pressure at the dressing <NUM> from atmospheric pressure to a high pressure value, allow the dressing <NUM> to return to atmospheric pressure, draw negative pressure at the dressing <NUM> from atmospheric pressure to a high pressure value, allow the dressing <NUM> to return to atmospheric pressure, and so on. The control circuit <NUM> thereby controls the negative pressure pump <NUM> to provide a cyclic variation of negative pressure that oscillates between a high pressure value and atmospheric pressure.

Accordingly, the aggressive cleanse pressure control line <NUM> depicts a waveform with a greater amplitude (i.e., greater pressure differential) as compared to the waveform of the dynamic pressure control line <NUM>. Furthermore, the aggressive cleanse pressure control line <NUM> depicts a waveform with a greater frequency (shorter period) as compared to the waveform of the dynamic pressure control line <NUM>. Because of the greater amplitude and frequency, aggressive cleanse pressure control may provide more energy to the wound bed and cause increased scrubbing and debridement of the wound bed. In some embodiments, aggressive cleanse pressure control may be used in process <NUM> (at dynamic pressure control phase <NUM>) and/or process <NUM> (at dynamic pressure control phase <NUM>). In some embodiments, aggressive cleanse pressure control is used with the perforated layer <NUM> of the dressing <NUM>.

Referring now to <FIG>, a graphical representation of dynamic pressure control with a variable high pressure value is shown, according to an exemplary embodiment. As illustrated by pressure line <NUM> on graph <NUM> of <FIG>, dynamic pressure control may provide a cyclic variation of negative pressure that includes multiple cycles between a low pressure value and a high pressure value. In the example of <FIG>, the high pressure value changes between a first cycle and a second cycle of the multiple cycles. In various embodiments, the pressure differential may change between the first and second cycles in a variety of ways. In the example of <FIG>, the high pressure value oscillates over time between a minimum high pressure value (e.g., <NUM> mmHg) and a maximum high pressure value (e.g., <NUM> mmHg). The control circuit <NUM> may be configured to control the negative pressure pump <NUM> to provide the negative pressure depicted by the pressure line <NUM> of <FIG>. Changing the high pressure value over time as in <FIG> may facilitate wound healing by preventing the wound bed from adapting to a particular high pressure value. Dynamic pressure control with a variable high pressure value as illustrated by pressure line <NUM> may be used in process <NUM> (at dynamic pressure control phase <NUM>) and/or process <NUM> (at dynamic pressure control phase <NUM>). In some embodiments, dynamic pressure control with a variable high pressure value is used with the perforated layer <NUM> of the dressing <NUM>.

<FIG> and <FIG> show various dynamic pressure control waveforms according to various embodiments. The control circuit <NUM> may be configured to control the negative pressure pump <NUM> to provide negative pressure at the dressing <NUM> that substantially tracks one or more of these waveforms and/or combinations thereof. For example, the hold periods of the pressure line <NUM> <FIG> may be combined with the variable high pressure value of the pressure line <NUM> of <FIG> to provide hold periods at varying high pressure values. Many such combinations and adaptations are possible.

Although the figures show a specific order of method steps, the order of the steps may differ from what is depicted. Also two or more steps can be performed concurrently or with partial concurrence. Such variation will depend on the software and hardware systems chosen and on designer choice. All such variations are within the scope of the disclosure. Likewise, software implementations could be accomplished with standard programming techniques with rule based logic and other logic to accomplish the various connection steps, calculation steps, processing steps, comparison steps, and decision steps.

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

As utilized herein, the terms "approximately," "about," "substantially", and similar terms are intended to have a broad meaning in harmony with the common and accepted usage by those of ordinary skill in the art to which the subject matter of this disclosure pertains. It should be understood by those of skill in the art who review this disclosure that these terms are intended to allow a description of certain features described and claimed without restricting the scope of these features to the precise numerical ranges provided. Accordingly, these terms should be interpreted as indicating that insubstantial or inconsequential modifications or alterations of the subject matter described and claimed are considered to be within the scope of the invention as recited in the appended claims.

As used herein, the term "circuit" may include hardware structured to execute the functions described herein. In some embodiments, each respective "circuit" may include machine-readable media for configuring the hardware to execute the functions described herein. The circuit may be embodied as one or more circuitry components including, but not limited to, processing circuitry, network interfaces, peripheral devices, input devices, output devices, sensors, etc. In some embodiments, a circuit may take the form of one or more analog circuits, electronic circuits (e.g., integrated circuits (IC), discrete circuits, system on a chip (SOCs) circuits, etc.), telecommunication circuits, hybrid circuits, and any other type of "circuit. " In this regard, the "circuit" may include any type of component for accomplishing or facilitating achievement of the operations described herein. For example, a circuit as described herein may include one or more transistors, logic gates (e.g., NAND, AND, NOR, OR, XOR, NOT, XNOR, etc.), resistors, multiplexers, registers, capacitors, inductors, diodes, wiring, and so on).

Claim 1:
A wound therapy system, comprising:
a dressing (<NUM>);
an instillation pump (<NUM>) fluidly communicable with the dressing (<NUM>) and configured to provide instillation fluid to the dressing (<NUM>);
a negative pressure pump (<NUM>) fluidly communicable with the dressing (<NUM> and configured to remove air from the dressing (<NUM>); and
a control circuit (<NUM>) communicably coupled to the instillation pump (<NUM>) and the negative pressure pump (<NUM>) and configured to:
control the instillation pump (<NUM>) to provide an amount of the instillation fluid to the dressing;
provide a soak period; and
control the negative pressure pump (<NUM>) to provide a cyclic variation of negative pressure at the dressing (<NUM>); characterized by
the dressing (<NUM>) comprising a perforated layer (<NUM>) comprising a plurality of holes (<NUM>) extending therethrough;
wherein the dressing (<NUM>) is coupleable to a wound bed; and wherein the cyclic variation of negative pressure deforms the wound bed at the holes (<NUM>);
wherein the cyclic variation of negative pressure comprises a plurality of cycles; and wherein each cycle does an amount of work of within a range between <NUM> mJ and <NUM> mJ for each of the plurality of holes (<NUM>).