Patent Description:
Many different types of wound dressings are known for aiding in the healing process of a human or animal. These different types of wound dressings include many different types of materials and layers, for example, pads such as gauze pads or foam pads. Topical negative pressure ("TNP") therapy, sometimes referred to as vacuum assisted closure, negative pressure wound therapy, or negative pressure wound therapy, is widely recognized as a beneficial mechanism for improving the healing rate of a wound. Such therapy is applicable to a broad range of wounds such as incisional wounds, open wounds and abdominal wounds.

TNP therapy assists in the closure and healing of wounds by reducing tissue edema; encouraging blood flow; stimulating the formation of granulation tissue; removing excess exudates, and may reduce bacterial load and thus reduce the potential for infection of the wound. Furthermore, TNP therapy permits less outside disturbance of the wound and promotes more rapid healing. <CIT> discloses a system including a pump assembly and a wound dressing configured to be positioned over a wound. The pump assembly and the wound dressing can be fluidically connected to facilitate delivery of negative pressure to a wound via a fluid flow path. The system can be configured to efficiently deliver negative pressure and to detect and indicate presence of conditions, such as a blockage in a fluid flow path. Monitoring of the conditions can be performed by detecting a level of activity of a pump of the pump assembly.

Embodiments disclosed herein are directed to a reduced pressure appliance and methods (which are excluded from the scope of the invention) of treatment using a reduced pressure appliance, and may be useful in the treatment of wounds using reduced pressure.

In some embodiments, a negative pressure wound therapy apparatus can include a negative pressure source that can be configured to provide negative pressure via a fluid flow path to a wound covered by a wound dressing. The negative pressure source can be further configured to be periodically activated to reduce pressure under the wound dressing to approximately a negative pressure set point and be periodically deactivated after the pressure under the wound dressing is reduced to the approximately the negative pressure set point. The apparatus can include a controller that can be configured to activate the negative pressure source for a first duration of time to attempt to reduce the pressure to approximately the negative pressure set point. Subsequent, to the expiration of the first duration of time, the controller can deactivate the negative pressure source after the pressure under the wound dressing is reduced to approximately the negative pressure set point. The controller can distinguish between a blockage in the fluid flow path and the presence of a low leak in the fluid flow path. The controller can activate the negative pressure source for a second duration of time in an attempt to reduce pressure in the fluid flow path. The second duration of time can be subsequent to the first duration of time. The controller can deactivate the negative pressure source subsequent to expiration of the second duration of time. The controller can determine a pressure change in the fluid flow path over at least part of the second duration of time, and in response to determining that the pressure change in the fluid flow path over the at least part of the second duration of time indicates reduction in pressure, provide indication of blockage in the fluid flow path.

The apparatus of the preceding paragraph can include one or more of the following features. The low leak can corresponds to a leak rate of gas entering the fluid flow path from external environment at which the apparatus is configured to provide or maintain negative pressure wound therapy. The controller can be further configured to, in response to determining that the pressure change in the fluid flow path over the at least part of the second duration of time does not indicate reduction in pressure, provide indication that the low leak is present in the fluid flow path. The second duration time can be shorter than the first duration of time over which the negative pressure source is activated to attempt to reduce pressure under the wound dressing to approximately the negative pressure set point. The pressure in the fluid flow path can be reduced over the second duration of time when the negative pressure source is active due to evacuation of gas from a portion of the fluid flow path downstream from the blockage. The fluid flow path can include a leak, and the portion of the fluid flow path downstream from the blockage can be depressurized over a duration of time when the negative pressure source is deactivated due to the leak. The apparatus can further include a pressure sensor configured to measure pressure in the fluid flow path. The controller can be further configured to determine the pressure change in the fluid flow path over the at least part of the second duration of time based on a difference between a first pressure measurement made by the pressure sensor approximately at a start of the second duration of time and a second pressure measurement made by the pressure sensor approximately at an end of the second duration of time. The apparatus can further include a canister configured to be fluidically connected to the negative pressure source and to store at least some fluid removed from the wound.

In some implementations, a negative pressure wound therapy apparatus can include a negative pressure source configured to provide negative pressure via a fluid flow path to a wound covered by a wound dressing, the negative pressure source further configured to be periodically activated to reduce pressure under the wound dressing to approximately a negative pressure set point and be periodically deactivated after pressure under the wound dressing is reduced to approximately the negative pressure set point. The apparatus can also include a controller configured to indicate a blockage in the fluid flowpath. The controller can activate the negative pressure source for a first duration of time to attempt to reduce pressure under the wound dressing to approximately the negative pressure set point. Subsequent to expiration of the first duration of time, the controller can deactivate the negative pressure source after pressure under the wound dressing is reduced to approximately the negative pressure set point. The controller can activate the negative pressure source for a second duration of time to attempt to reduce pressure in the fluid flow path, the second duration of time subsequent to the first duration of time. The controller can deactivate the negative pressure source subsequent to expiration of the second duration of time. The controller can determine a pressure change in the fluid flow path over the at least part of the second duration of time. In response to determining that the pressure change in the fluid flow path over the at least part of the second duration of time indicates reduction in pressure, the controller can provide indication of the blockage in the fluid flow path.

The apparatus of any of the preceding paragraphs can include one or more of the following features. The second duration time can be shorter than the first duration of time over which the negative pressure source is activated to attempt to reduce pressure under the wound dressing to approximately the negative pressure set point. The pressure in the fluid flow path can be reduced over the at least part of the duration of time when the negative pressure source is active due to evacuation of gas from a portion of the fluid flow path downstream from the blockage. The fluid flow path can include a leak and the portion of the fluid flow path downstream from the blockage can be depressurized over another duration of time when the negative pressure source is deactivated due to the leak. The apparatus can further include a pressure sensor configured to measure pressure in the fluid flow path. The controller can be further configured to determine the pressure change in the fluid flow path over the at least part of the duration of time based on a difference between a first pressure measurement made by the pressure sensor approximately at a start of the duration of time and a second pressure measurement made by the pressure sensor approximately at an end of the duration of time. The apparatus can further include a canister configured to be fluidically connected to the negative pressure source and to store at least some fluid removed from the wound.

In some implementations, a negative pressure wound therapy apparatus can include a negative pressure source configured to provide negative pressure via a fluid flow path to a wound covered by a wound dressing, the negative pressure source further configured to be periodically activated to reduce pressure under the wound dressing to approximately a negative pressure set point and be periodically deactivated after pressure under the wound dressing is reduced to approximately the negative pressure set point. The apparatus can also include a controller configured to activate the negative pressure source for a duration of time to attempt to reduce pressure in the fluid flow path. The controller can deactivate the negative pressure source subsequent to expiration of the duration of time. The controller can determine a pressure change in the fluid flow path over at least part of the duration of time, and in response to determining that the pressure change in the fluid flow path over the at least part of the duration of time indicates reduction in pressure, provide indication of the blockage in the fluid flow path.

The apparatus of any of the preceding paragraphs can include one or more of the following features. The pressure in the fluid flow path can be reduced over the at least part of the duration of time when the negative pressure source is active due to evacuation of gas from a portion of the fluid flow path downstream from the blockage. The fluid flow path can include a leak, and a portion of the fluid flow path downstream from the blockage can be depressurized over another duration of time when the negative pressure source is deactivated due to the leak. The apparatus can further include a pressure sensor configured to measure pressure in the fluid flow path. The controller can further be configured to determine the pressure change in the fluid flow path over the at least part of the duration of time based on a difference between a first pressure measurement made by the pressure sensor approximately at a start of the duration of time and a second pressure measurement made by the pressure sensor approximately at an end of the duration of time. The apparatus can further include a canister configured to be fluidically connected to the negative pressure source and to store at least some fluid removed from the wound.

In some implementations, a method of operating a negative pressure wound therapy apparatus including a negative pressure source and a controller can include, by the controller, indicating a blockage in a fluid flowpath that can be fluidically connect a wound covered by a wound dressing to the negative pressure source configured to provide negative pressure to the wound. The method can include activating the negative pressure source for a first duration of time to attempt to reduce pressure under the wound dressing to approximately the negative pressure set point. The method can further include subsequent to expiration of the first duration of time, deactivating the negative pressure source after pressure under the wound dressing is reduced to approximately the negative pressure set point. The method can further include activating the negative pressure source for a second duration of time to attempt to reduce pressure in the fluid flow path, the second duration of time subsequent to the first duration of time. The method can further include deactivating the negative pressure source subsequent to expiration of the second duration of time. The method can further include determining a pressure change in the fluid flow path over at least part of the second duration of time. The method can further include in response to determining that the pressure change in the fluid flow path over at least part of the second duration of time indicates reduction in pressure, provide indication of the blockage in the fluid flow path.

The method of the preceding paragraph can include one or more of the following features. The second duration time can be shorter than the first duration of time over which the negative pressure source is activated to attempt to reduce pressure under the wound dressing to approximately the negative pressure set point. The pressure in the fluid flow path can be reduced over the at least part of the second duration of time when the negative pressure source is active due to evacuation of gas from a portion of the fluid flow path downstream from the blockage. The fluid flow path can include a leak, and the portion of the fluid flow path downstream from the blockage can be depressurized over a duration of time when the negative pressure source is deactivated due to the leak. The method can include measuring pressure in the fluid flow path using a pressure sensor and determining the pressure change in the fluid flow path over at least part of the second duration of time based on a difference between a first pressure measurement made by the pressure sensor approximately at a start of the second duration of time and a second pressure measurement made by the pressure sensor approximately at an end of the second duration of time.

Features and advantages of the present disclosure will be apparent from the following detailed description, taken in conjunction with the accompanying drawings of which:.

The present disclosure relates to methods (which are excluded from the scope of the invention) and apparatuses for dressing and treating a wound with reduced pressure therapy or topical negative pressure (TNP) therapy. In particular, but without limitation, embodiments of this disclosure relate to negative pressure therapy apparatuses, methods (which are excluded from the scope of the invention) for controlling the operation of TNP systems, and methods of using TNP systems. The methods and apparatuses can incorporate or implement any combination of the features described below.

Many different types of wound dressings are known for aiding in the healing process of a human or animal. These different types of wound dressings include many different types of materials and layers, for example, gauze, pads, foam pads or multi-layer wound dressings. TNP therapy, sometimes referred to as vacuum assisted closure, negative pressure wound therapy, or reduced pressure wound therapy, can be a beneficial mechanism for improving the healing rate of a wound. Such therapy is applicable to a broad range of wounds such as incisional wounds, open wounds and abdominal wounds.

TNP therapy can assist in the closure and healing of wounds by reducing tissue edema, encouraging blood flow, stimulating the formation of granulation tissue, removing excess exudates, and reducing bacterial load and thus, infection to the wound. Furthermore, TNP therapy can permit less outside disturbance of the wound and promote more rapid healing.

As is used herein, reduced or negative pressure levels, such as -X mmHg, represent pressure levels that are below atmospheric pressure, which typically corresponds to <NUM> mmHg (or <NUM> atm, <NUM> inHg, <NUM> kPa, <NUM> psi, etc.). Accordingly, a negative pressure value of -X mmHg reflects pressure that is X mmHg below atmospheric pressure, such as a pressure of (<NUM>-X) mmHg. In addition, negative pressure that is "less" or "smaller" than -X mmHg corresponds to pressure that is closer to atmospheric pressure (for example, - <NUM> mmHg is less than -<NUM> mmHg). Negative pressure that is "more" or "greater" than -X mmHg corresponds to pressure that is further from atmospheric pressure (for example, -<NUM> mmHg is more than -<NUM> mmHg).

Embodiments disclosed in this section or elsewhere in this specification relate to apparatuses and methods (which are excluded from the scope of the invention) of treating a wound with reduced pressure, including pump and wound dressing components and apparatuses. The apparatuses and components comprising the wound overlay and packing materials, if any, are sometimes collectively referred to in this section or elsewhere in this specification as dressings.

It will be appreciated that throughout this specification reference is made to a wound. It is to be understood that the term wound encompasses open and closed wounds in which skin is tom, cut or punctured or where trauma causes a contusion, or any other superficial or other conditions or imperfections on the skin of a patient or otherwise that benefit from reduced pressure treatment. A wound is thus broadly defined as any damaged region of tissue where fluid may or may not be produced. Examples of such wounds include abdominal wounds or other large or incisional wounds, either as a result of surgery, trauma, sterniotomies, fasciotomies, or other conditions, dehisced wounds, acute wounds, chronic wounds, subacute and dehisced wounds, traumatic wounds, flaps and skin grafts, lacerations, abrasions, contusions, bums, electrical bums, diabetic ulcers, pressure ulcers, stoma, surgical wounds, trauma and venous ulcers.

Embodiments of the present disclosure are generally applicable to use in topical negative pressure (TNP) or reduced pressure therapy systems. Briefly, negative pressure wound therapy assists in the closure and healing of many forms of "hard to heal" wounds by reducing tissue edema, encouraging blood flow and granular tissue formation, or removing excess exudate and can reduce bacterial load (and thus infection risk). In addition, the therapy allows for less disturbance of a wound leading to more rapid healing. TNP therapy systems can also assist in the healing of surgically closed wounds by removing fluid. TNP therapy can help to stabilize the tissue in the apposed position of closure. A further beneficial use of TNP therapy can be found in grafts and flaps where removal of excess fluid is important and close proximity of the graft to tissue is required in order to ensure tissue viability.

<FIG> illustrates a negative or reduced pressure wound treatment system <NUM> comprising a wound filler <NUM> placed inside a wound cavity <NUM>, the wound cavity sealed by a wound cover <NUM>. The wound filler <NUM> in combination with the wound cover <NUM> can be referred to as wound dressing. A single or multi lumen tube or conduit <NUM> is connected the wound cover <NUM> with a reduced pressure wound therapy assembly <NUM> configured to supply reduced pressure. The wound cover <NUM> can be in fluidic communication with the wound cavity <NUM>. The assembly <NUM> can be a canisterless assembly (meaning that exudate is collected in the wound dressing or is transferred via tube <NUM> for collection to another location). However, any of the assemblies disclosed herein can be configured to include or support a canister. Additionally, in any of the systems disclosed herein, any of the assemblies can be mounted to or supported by the dressing, or adjacent to the dressing.

The wound filler <NUM> can be any suitable type, such as hydrophilic or hydrophobic foam, gauze, inflatable bag, and so on. The wound filler <NUM> can be conformable to the wound cavity <NUM> such that it substantially fills the cavity. The wound cover <NUM> can provide a substantially fluid impermeable seal over the wound cavity <NUM>. The wound cover <NUM> can have a top side and a bottom side, and the bottom side adhesively (or in any other suitable manner) seals with wound cavity <NUM>. The conduit <NUM> or lumen or any other conduit or lumen disclosed herein can be formed from polyurethane, PVC, nylon, polyethylene, silicone, or any other suitable material.

The wound cover <NUM> can have a port (not shown) configured to receive an end of the conduit <NUM>. The port can be Renays Soft Port available from Smith & Nephew. The conduit <NUM> can otherwise pass through or under the wound cover <NUM> to supply reduced pressure to the wound cavity <NUM> so as to maintain a desired level of reduced pressure in the wound cavity. The conduit <NUM> can be any suitable article configured to provide at least a substantially sealed fluid flow pathway between the assembly <NUM> and the wound cover <NUM>, so as to supply the reduced pressure provided by the assembly <NUM> to wound cavity <NUM>.

The wound cover <NUM> and the wound filler <NUM> can be provided as a single article or an integrated single unit. No wound filler can also be possible and the wound cover by itself can be considered the wound dressing. The wound dressing can then be connected, via the conduit <NUM>, to a source of negative pressure, such as the assembly <NUM>. The assembly <NUM> can be miniaturized and portable, although larger conventional negative pressure sources can also be used.

The wound cover <NUM> can be located over a wound site to be treated. The wound cover <NUM> can form a substantially sealed cavity or enclosure over the wound site. The wound cover <NUM> can be configured to have a film having a high water vapor permeability to enable the evaporation of surplus fluid, and can have a super absorbing material contained therein to safely absorb wound exudate. It will be appreciated that throughout this specification reference is made to a wound. In this sense it is to be understood that the term wound is to be broadly construed and encompasses open and closed wounds in which skin is torn, cut or punctured or where trauma causes a contusion, or any other surficial or other conditions or imperfections on the skin of a patient or otherwise that benefit from reduced pressure treatment. A wound is thus broadly defined as any damaged region of tissue where fluid may or may not be produced. Examples of such wounds include acute wounds, chronic wounds, surgical incisions and other incisions, subacute and dehisced wounds, traumatic wounds, flaps and skin grafts, lacerations, abrasions, contusions, bums, diabetic ulcers, pressure ulcers, stoma, surgical wounds, trauma and venous ulcers. The components of the TNP system described herein can be particularly suited for incisional wounds that exude a small amount of wound exudate.

The system can be designed to operate without the use of an exudate canister. The system can be configured to support an exudate canister. Configuring the assembly <NUM> and tubing <NUM> can be done so that the tubing <NUM> can be quickly and easily removed from the assembly <NUM> can facilitate or improve the process of dressing or assembly changes, if necessary. The system can be configured to have any suitable connection between the tubing and the assembly <NUM>.

The assembly <NUM> can be configured to deliver negative pressure of approximately -<NUM> mmHg, or between about -<NUM> mmHg and <NUM> mmHg. The pressure range can be between about -<NUM> mmHg and -<NUM> mmHg. Alternatively, a pressure range of up to -<NUM> mmHg, up to - <NUM> mmHg or over -<NUM> mmHg can be used. Also a pressure range of below - <NUM> mmHg can be used. Alternatively, a pressure range of over approximately -<NUM> mmHg, or even <NUM> mmHg, can be supplied by the assembly <NUM>.

In operation, the wound filler <NUM> is inserted into the wound cavity <NUM> and wound cover <NUM> is placed so as to seal the wound cavity <NUM><NUM>. The assembly <NUM> provides a source of a negative pressure to the wound cover <NUM>, which is transmitted to the wound cavity <NUM> via the wound filler <NUM>. Fluid (e.g., wound exudate) is drawn through the conduit <NUM>, and can be stored in a canister. Fluid can be absorbed by the wound filler <NUM> or one or more absorbent layers (not shown).

Wound dressings that may be utilized with the assembly and other embodiments of the present application include Renasys-F, Renasys-G, Renasys AB, and Pico Dressings available from Smith & Nephew. Further description of such wound dressings and other components of a negative pressure wound therapy system that may be used with the assembly and other embodiments of the present application are found in <CIT>, <CIT>, <CIT>, <CIT>, and <CIT>. Other suitable wound dressings can be utilized.

<FIG> illustrate that the reduced pressure wound therapy system can be configured to operate with and without a canister (for example, in canister and canisterless modes) according to some embodiments. <FIG> shows a TNP system 200A that has a wound dressing connected directly to the pump assembly <NUM> (for example, canisterless mode). <FIG> shows a TNP system 200B that has a canister <NUM> interposed between the wound dressing and the pump assembly <NUM> (for example, canister mode). At the beginning of the application of negative pressure wound therapy to a wound when the wound is in the early stages of the healing process and exudes a significant volume of exudate, the reduced pressure wound therapy system can operate with a canister. In this mode of operation, the negative pressure wound therapy system can operate with a foam or gauze RENASYS™ dressing sold by Smith & Nephew or any other suitable dressing. Operation of the reduced pressure wound therapy system with a canister can sometimes be referred to herein as "RENASYS", "RENASYS-mode", or derivatives thereof. As the wound is progressing through the healing process and is starting to exude a smaller volume of exudate, the canister can be removed and the negative pressure wound therapy system may operate with an absorbent dressing, such as the PICO™ dressing sold by Smith & Nephew or any other suitable dressing that retains the wound exudate within the dressing. Operation of the reduced pressure wound therapy system without a canister may sometimes be referred to herein as "PICO", "PICO-mode", or derivatives thereof.

The pump assembly <NUM> can include one or more switches or buttons <NUM>, one or more indicators <NUM>, and a control board <NUM>, which can include one or more controllers, one or more memories. The one or more buttons <NUM> and the one or more indicators <NUM> (which collectively make up a user interface) can be in electrical communication with the control board <NUM>, which can include one or more controllers and memory. The one or more buttons <NUM> can be used for any suitable purpose for controlling an operation of the pump assembly <NUM>. For example, the one or more buttons <NUM> can be used to activate the pump system <NUM>, pause the pump assembly <NUM>, and clear system indicators such as one or more of the one or more indications <NUM>. The one or more buttons <NUM> can by any type of switch or button, such as a touchpad, touch screen, keyboard, and so on. One or more buttons <NUM> can be a press button. One or more buttons <NUM> can be included on a touchscreen interface.

The pump assembly <NUM> can include a connector port <NUM> adapted to receive a connector <NUM>. The connector <NUM> can be a part of the canister or the wound dressing that is attached to the pump assembly <NUM>, as described herein. The connector <NUM> can be removably attached to the connector port <NUM>. In some arrangements, a first connector <NUM> can be removed from the pump assembly <NUM> and replaced with a second connector <NUM> that is then attached to the pump assembly <NUM>. For example, a first connector <NUM> that is connected to a RENASYS™ dressing can be removed from the connector port <NUM> and replaced with a second connector <NUM> that connected to a PICO™ dressing, thereby allowing the pump assembly <NUM> to be switched from canister to a canisterless mode of operation. As described in more detail below, the connector <NUM> and/or pump assembly <NUM> can be adapted to allow the pump assembly <NUM> to detect whether a canister or canisterless connector <NUM> is attached to the connector port <NUM>. In some arrangements, the operation of the pump assembly <NUM> can be adjusted according to whether the pump assembly <NUM> detects a canister or a canisterless connector <NUM> is connected to the connector port <NUM>.

The connector port <NUM> can include one or more connector switches in electrical communication with the control board <NUM>, which can include one or more controllers. The one or more connector switches can be configured to engage one or more connectors of the canister or the dressing. One or more connector switches can advantageously permit the pump assembly <NUM> (e.g., the control board <NUM>) to differentiate between a canister connection and a dressing connection. One or more of the connectors <NUM> can include one or more connector switches in addition to or in lieu of the one or more connector switches of the connector port <NUM>. The connector switches contemplated herein can be mechanical, electrical, optical, and/or magnetic, or any other suitable switch, and can include sensors. The connector switches can be configured to close or open an electrical circuit, thereby permitting the control board <NUM> to detect whether the connector switch is engaged or disengaged. For example, as described in more detail below, the connector port <NUM> can include a connector switch that is actuated by a portion of a connector <NUM> that couples a canister to the connector port <NUM>. The connector switch can be further configured so that the switch is not actuated by a connector <NUM> that couples a dressing to the connector port <NUM>, thereby allowing the control board <NUM> to detect whether a canister or a dressing is attached to the connector port <NUM>. In some arrangements, the pump assembly <NUM> can be configured so that the connector switch is activated by a connector <NUM> that couples a dressing to the connector port <NUM> and is not activated by a connector <NUM> that couples a canister to the connector port <NUM>.

With continued reference to <FIG>, the one or more indicators <NUM> can indicate one or more operating or failure conditions of the pump assembly <NUM>. Each of the one or more indicators <NUM> can provide an indication regarding a different operating or failure condition. An active (such as, lit) visual indicator (such as, LED) of the one or more indicators <NUM> can represent a certain operation condition for the pump assembly <NUM>. For example, a dressing indicator of the one or more indicators <NUM> can provide an indication as to presence of leakages or leaks in the TNP system <NUM>, and an active dressing indicator can represent a leak. As another example, a dressing capacity indicator of the one or more indicators <NUM> can provide an indication as to the remaining fluid capacity of the wound dressing or canister, and an active dressing capacity indicator can represent that the wound dressing or canister is at or nearing capacity. As yet another example, a power source indicator of the one or more indicators <NUM> can provide an indication as to remaining capacity or life of the power source <NUM>, such as one or more batteries, and an active power source indicator can represent a low capacity. One or more indicators <NUM> can represent a combination of one or more of the above operating or failure conditions of the pump assembly <NUM> or other operating or failure conditions for the pump assembly <NUM>.

The one or more indicators <NUM> can be icons. For example, the one or more indicators <NUM> can be activated (e.g., lit) via an illumination source such as LEDs (not shown) of pump assembly <NUM>. The one or more indicators <NUM> can, for instance, be of a different color, two different colors (e.g., two indicators can share the same color), or same color. The pump assembly <NUM> can include visual, audible, tactile, haptic, or other types of indicators or alarms configured to signal to the user various operating conditions. Such conditions include system on/off, standby, pause, normal operation, dressing problem, leak and error. The indicators can include speakers, displays, light sources, etc., or combinations thereof. One or more buttons indicators <NUM> can be included on a touchscreen interface.

The pump assembly <NUM> can be powered by a power source <NUM> such as a one or more battery cells or any other suitable power source. Battery cells can include any combination of one or more of lithium-ion, lithium-polymer, lithium iron phosphate, lead acid, nickel based, alkaline. The pump assembly <NUM> can also include a source of negative pressure <NUM>, which can include a pump <NUM> powered by an actuator <NUM>, such as an electric motor. The actuator <NUM> can be integrated into the pump <NUM>. The negative pressure source <NUM> can be a rotary diaphragm pump or other diaphragm pump, a piezoelectric pump, a peristaltic pump, a piston pump, a rotary vane pump, a liquid ring pump, a scroll pump, a diaphragm pump operated by a piezoelectric transducer, a pump operated by a voice coil actuator, or any other suitable pump or micropump or any combinations of the foregoing. The pump assembly <NUM> can also include one or more pressure sensors <NUM> that measure pressure in the fluid flow path. The power source <NUM> can supply power to electro-mechanical components of the pump assembly <NUM>, including one or more of the negative pressure source <NUM>, pressure sensor <NUM>, control board <NUM>, buttons <NUM>, and indicators <NUM>.

The pump assembly <NUM> can further include an inlet <NUM> to connect the pump assembly <NUM> to the wound dressing. For example, the inlet <NUM> can be connected to the connector port <NUM> and the connector <NUM> that is in fluid communication with the wound dressing via a fluid flow path.

The pump assembly <NUM> can also include an outlet <NUM>. The outlet <NUM> can vent or exhaust gas to the atmosphere. A filter (not shown) can be interposed between the outlet <NUM> and the atmosphere. The filter can provide filtration of the gas prior to venting the gas to the atmosphere. The filter can be a bacterial filter, odor filter, or any combination thereof. A dampening component (not shown), such as a noise dampening component, can be interposed between the outlet <NUM> and the atmosphere. The dampening component can reduce the noise generated by the pump assembly <NUM> during operation. The pump assembly <NUM> can communicate information, such as information related to provision of negative pressure therapy, to one or more remote devices. Such communication can be performed using a wired or wireless interface.

<FIG> illustrates the pump assembly <NUM> of <FIG> with a canister <NUM> additionally positioned in a fluid flow path between the inlet <NUM> and the wound dressing. The connector <NUM> can fluidically connect the canister <NUM> to the connector port <NUM>. As discussed further below, the connector <NUM> can be configured to signal to the pump assembly <NUM> whether the connector port <NUM> is connected to a wound dressing directly or whether a canister <NUM> is disposed between the connector <NUM> and the wound dressing.

The control board <NUM> (for example, a controller) adjusts one or more operational parameters of negative pressure wound therapy depending on whether the pump assembly is connected to the canister or the dressing. For example, in canisterless mode, the level of negative pressure provided to the wound can be reduced compared to canister mode because the wound is exuding a smaller amount of fluid. As another example, detection of one or more operating conditions can be enabled, disabled, or adjusted. For instance, in canisterless mode, canister full detection (or blockage detection) and alarming can be disabled and, instead, dressing full detection and alarming can be enabled.

The pump assembly <NUM> includes a user interface, such as one or more displays, indicators, lights, buttons, switches, speakers, vibrating elements, etc. The user interface can be adjusted based on detection of a canister. For example, in canister mode, the user interface can include an indicator alerting a user when canister becomes full. In canisterless mode, this indicator can be replaced with an indicator alerting the user when the dressing become full. The indicators can be icons.

<FIG> depicts a perspective view <NUM> of a dual mode TNP system in a canister mode according to some embodiments. In the illustrated system, a canister <NUM> is attached to a pump assembly <NUM> (which can be similar as the pump assembly <NUM> described herein). The pump assembly <NUM> can be adapted to be slidably coupled to the canister <NUM>. The canister <NUM> can have an inlet <NUM> through which wound exudate can enter the canister <NUM>. The pump assembly <NUM> can slide back to disengage the pump assembly <NUM> from the canister <NUM>, as illustrated with respect to <FIG>.

<FIG> depicts a perspective view <NUM> of the TNP system of <FIG> with the canister <NUM> disengaged from the pump assembly <NUM>. In some cases, the pump assembly <NUM> can operate in a canisterless mode. As described above, the pump assembly <NUM> can have a connector port <NUM> that is adapted to connect to a connector <NUM> (shown schematically in <FIG>). The connector <NUM> can be a canister connector or a canisterless connector as discussed herein. The connector port <NUM> can be fluidically connected to a negative pressure source (such as, vacuum pump) housed within the pump assembly <NUM>. The connector port <NUM> can establish a flow path between the negative pressure source of the pump assembly <NUM> and the connector <NUM> that is connected to the connector port <NUM>. The pump assembly <NUM> can provide negative pressure to a canister connector <NUM> or a canisterless connector that is attached to the connector port <NUM>. The canister <NUM> can have the canister connector <NUM> that fluidically connects to the connector port <NUM> when the pump assembly <NUM> is slidably mounted onto the canister <NUM>. Mounting (such as slidingly mounting) the canister <NUM> can activate a switch configured to indicate that the canister has been connected, as described herein. Conversely, dismounting of the canister <NUM> can deactivate the switch. The canister <NUM> can have an inlet <NUM> through which wound exudate enters the canister <NUM> when negative pressure is applied to the canister <NUM> through the canister connector <NUM>.

With continued reference to <FIG>, the pump assembly <NUM> can include a dial <NUM> (also illustrated in <FIG>) that allows pressure selection on the pump assembly <NUM>. The magnitude of the negative pressure supplied by the pump assembly <NUM> can be adjusted by turning the dial <NUM>. The dial <NUM> can be adapted to turn to two or more discreet settings. For example, the dial <NUM> can have three discreet settings that allow the negative pressure provided by the pump assembly <NUM> to be set to one of three settings (e.g., -<NUM> mmHg, -<NUM> mmHg, and -<NUM> mmHg). The pump assembly <NUM> can include a bar <NUM> that can be used as an anchoring site for a strap or clasp, thereby allowing the pump assembly <NUM> to be suspended from a strap that is attached to the bar <NUM>. When the canister <NUM> and the pump assembly <NUM> are connected together, a ramped portion of the top surface of the canister <NUM> can form an overhang that is supported on an inclined portion of the bottom surface of the pump assembly <NUM>, thereby enhancing retention of the canister <NUM> on the pump assembly <NUM> when the pump assembly <NUM> is suspended from the bar <NUM>. The pump assembly <NUM> can include one or more icons on the housing <NUM> of the pump assembly <NUM>. The icons can be backlit by a light source that is disposed within the housing <NUM> of the pump assembly <NUM>.

<FIG> illustrate various visual indicators on a housing of any of the pump assemblies described herein, such as the pump assembly <NUM>, including <NUM> (battery level), <NUM> (blockage in fluid flow path), <NUM> (leak in fluid flow path), and <NUM> (provision of therapy) in canisterless (<FIG>) and canister (<FIG>) modes of operation. <FIG> also illustrates the pump assembly <NUM> connected to a canister <NUM>. The illustrated indicators can be configured to provide various indications as described herein. For example, certain indications can include non-critical alarms that do not result in pausing therapy, while certain indications are critical alarms that result in pausing therapy. For instance, as described herein, detection of a minor or sustainable air leak does not result in pausing therapy, whereas detection of a major or unsustainable air leak results in pausing therapy.

<FIG> illustrates a negative pressure wound therapy system <NUM> according to some embodiments. Any of the embodiments of the negative pressure wound therapy system <NUM> disclosed herein can have any one or more of the same components, features, materials, sizes, configurations, and other details of any other system embodiments disclosed, including the embodiments of the pump assembly <NUM> in <FIG> and the embodiments of the pump assembly <NUM> in <FIG> and <FIG>. The negative pressure wound therapy system <NUM> can be miniaturized and portable, although larger conventional portable or non-portable (e.g., wall suction) pumps can also be used. The negative pressure wound therapy system <NUM> can include a switch or a button <NUM>, illustrated as a play/pause button located on the exterior of the housing of the system. The button <NUM> can be configured to stop, pause, and/or restart negative pressure wound therapy. Although illustrated as a press button <NUM>, other types of switches or buttons can be included, such as a touchpad, touch screen, keyboard, and so on. The negative pressure wound therapy system <NUM> can have one or more indicators, such as the three indicators <NUM>, <NUM>, <NUM>, for providing various indications as described herein. The one or more indicators can be visual indicators, such as one or more LEDs, audible, haptic, tactile, or any combination of such indicators. The negative pressure wound therapy system <NUM> can have one indicator, two indicators, or four or more indicators. The negative pressure wound therapy system <NUM> can have a connector port or inlet <NUM>. The negative pressure wound therapy system <NUM> can operate without a canister as described herein. In some cases, the illustrated negative pressure wound therapy system <NUM> can be a PICOTM system sold by Smith & Nephew. Additional details regarding the negative pressure wound therapy system <NUM> are described in <CIT>,<CIT>; and <CIT>.

<FIG> illustrates a process <NUM> for operating a negative pressure wound therapy system according to some embodiments. The process <NUM>, which can also be referred to as a state machine, can be executed by one or more controllers of any of the systems, assemblies, or pumps disclosed herein, such as the system <NUM>. The process <NUM> includes Power Off State <NUM>, Power On States <NUM>, and Power Off State <NUM>. Power On States <NUM> can include Therapy Active States <NUM>, and Therapy Stop State <NUM>. The Therapy Active States <NUM> can further include Therapy Initialization State <NUM>, Pump Down State <NUM>, Maintain Pressure State <NUM>, Turn Pump Off and On and Measure Pressure Decay State <NUM>, Blockage State <NUM>, and Low Leak State <NUM>.

Operation of the TNP system can start in the Power Off State <NUM>, and the process <NUM> can transition to the Power On States <NUM>. This transition can be made automatically or in response to a user action, such as in response to a press of an "On" button (for example, one of the buttons <NUM>). The process <NUM> can transition to the Power On States <NUM> from Power Off State <NUM> upon a system reset, which can be performed by the user through one or more of the buttons <NUM>. Such system reset can involve a reset of the one or more controllers.

The process <NUM> can transition to the Power On States <NUM> in response to waking up from the Power Off State <NUM>. In the Power Off State <NUM>, the process <NUM> can be operating in low power mode, such as by causing the one or more processors to sleep or otherwise consume little power. This transition can be performed automatically, such as after passage of a duration of time. Alternatively or additionally, this transition can be performed in response to a user action as described herein. When the process <NUM> is in the Power Off State <NUM>, the TNP system may be off and not provide negative pressure.

Upon transition to the Power On States <NUM>, the process <NUM> can monitor or continue monitoring power source capacity, such as battery voltage or current. If the power source capacity falls below a certain threshold associated with proper operation of the TNP system, the process can transition to the Power Off State <NUM>. The process <NUM> can transition from the Power On States <NUM> to the Power Off State <NUM> in response to a user action, such as in response to a press of an "Off" button (for example, one of the buttons <NUM>). In some cases, a single button is configured to function as "On" and "Off" button.

Following a reset, timeout, or user action (such as, a button press), the process <NUM> can transition to the Therapy Active State <NUM>. In some cases, Therapy Active States <NUM> are entered via the Therapy Initialization State <NUM>. Upon transitioning to the Therapy Active States <NUM>, the process <NUM> can determine that the TNP system is operating in canister or canisterless mode. For example, as described herein, the process can determine that the switch indicating attachment of a canister has been activated in order to determine that the TNP system is operating in the canister mode.

The process <NUM> can determine target pressure setpoint depending on the mode of operation. In some cases, in canisterless mode, the target pressure setpoint is preset. For example, the target pressure setpoint in canisterless mode can be -<NUM> mmHg. In some cases, in canisterless mode, the target pressure setpoint can be selected. For example, the target pressure setpoint can be selected using the dial <NUM> as described herein. For instance, in canister mode, the target pressure setpoint can be selected as -<NUM> mmHg, -<NUM> mmHg, or -<NUM> mmHg. In some cases, the target pressure setpoint can be set once by the process <NUM> before negative pressure therapy is applied and can remain set until the TNP system has been powered-off and on again.

The process <NUM> can transition to the Pump Down State <NUM> in which provision of negative pressure wound therapy is commenced. The process <NUM> can activate or start the negative pressure source to attempt to reduce pressure at the wound to the target pressure setpoint. The process <NUM> can monitor pressure at the wound with one or more pressure sensors positioned in a fluid flow path connecting the negative pressure source to the dressing. When the pressure has been successfully reduced to the target set point, the process <NUM> can transition to the Maintain Pressure State <NUM>. In some cases, the process <NUM> can stop or deactivate the source of negative pressure when the target set point has been reached or attained. In some cases, the process <NUM> can slow down the source of negative pressure when the target set point has been reached or attained.

In the Maintain Pressure State <NUM>, the target pressure can be maintained, for example, by activating the negative pressure source pump when pressure at the wound has decreased above the target pressure setpoint and deactivating the negative pressure source when the target pressure has been restored. Pressure at the wound can decrease above the setpoint (or become more positive) due to one or more leaks in the fluid flow path.

In both Pump Down State <NUM> and Maintain Pressure State <NUM>, various system parameters, such as pressure at the wound or level of activity of the negative pressure source can be monitored to determine whether negative pressure wound therapy should be stopped or additional or alternative indication should be provided. Such additional or alternative indication can include the process <NUM> providing one or more of visual (such as, using one or more indicators <NUM> as shown in <FIG> and <FIG>), audible, haptic or tactile indications. Such determination can be based on finding of one or more blockages or leaks in the fluid flow path. In some cases, level of activity of the negative pressure source can be monitored via determining duty cycle of the negative pressure source, which can reflect proportion of time the negative pressure source is active over a time duration. In some cases, the level of activity of the negative pressure source can be monitored by one or more of power drawn (which can be determined by monitoring current or voltage), motor rotation, valve opening and closing. A timeout mechanism (such as, monitoring the blockage or the leak duration) or determination scheme using a hysteresis can be used to reduce a likelihood of false positives in the blockage or the leak detection.

In some cases, detection of a leak or blockage can cause the process <NUM> to transition into the Therapy Stop State <NUM> from one or more of Pump Down <NUM> or Blockage <NUM> States. In this state, negative pressure source can be stopped to pause provision of therapy. The process <NUM> can transition to the Therapy Stop State <NUM> in response to detecting: (<NUM>) pump down time indicative of a leak in canister or canisterless mode, (<NUM>) timeout indicative of blockage while maintaining pressure in the canister mode, (<NUM>) pressure decay due to a blockage, (<NUM>) timeout indicative of a leak while maintaining pressure in canister or canisterless mode.

The process <NUM> can distinguish between sustainable and unsustainable leaks or blockages as described herein. For example, a sustainable leak or blockage can be associated with less intense condition(s) that do not necessitate pausing or stopping therapy. Rather, the process <NUM> can indicate presence of the sustainable leak or blockage as described herein to permit the user to remedy the leak or blockage without the necessity to interrupt therapy. As another example, an unsustainable leak or blockage can be associated with more intense condition(s) that necessitate pausing or stopping therapy. Such unsustainable conditions can be so severe that continuing operation of the negative pressure source to provide therapy can drain the capacity of the power source.

When the target pressure setpoint cannot be reached in the Pump Down State <NUM> over a duration of time, the process <NUM> can determine presence of a leak. The process <NUM> can determine that such leak that prevents reaching the setpoint is unsustainable and indicate its presence by deactivating or stopping the negative pressure source. Additionally, the process <NUM> can indicate presence of the unsustainable leak visually, audibly, haptically or tactilely. Unsustainable leaks can be due to, for example, disconnecting the dressing from the negative pressure source when operating in the canisterless mode or disconnecting the canister when operating in the canister mode.

In some cases, the process <NUM> may not be able to restore the target pressure at the wound in the Maintain Pressure State <NUM> due to presence of a leak or blockage in the fluid flow path. The process <NUM> can distinguish between leak or blockage by comparing the level of activity of the negative pressure source, such as the duty cycle, to a leak threshold or blockage threshold as described herein. When blockage is present, fluid flow path volume through which the negative pressure source moves fluid is reduced. As a result, the level of activity of the negative pressure source decreases. When leak is present, fluid flow path volume through which the negative pressure source moves fluid is increased. As a result, the level of activity of the negative pressure source increases. By using different leak and blockage thresholds, the process <NUM> can distinguish between leak and blockage conditions. Leak and blockage thresholds can be selected or adjusted to account for canister or canisterless modes of operation. This can be advantageous because of different fluid flow path volumes when operating in both modes. For example, the fluid flow path volumes when operating in canister mode includes additional volume of the canister, which is not present in the canisterless mode.

The process <NUM> can monitor lifetime or usage time of the TNP system. For example, the process <NUM> can only update the lifetime in the Therapy Active States <NUM>. Lifetime can be measured as total amount of time the negative pressure source has been active since initial activation of the TNP system. The process <NUM> can start measuring or monitoring lifetime only after a therapy has been successfully provided for a threshold period of time, such as <NUM> minute, <NUM> minutes, <NUM> minutes, <NUM> minutes or <NUM> minutes. Successfully provision of therapy can correspond to being able to attain and maintain target pressure.

The process <NUM> can monitor the lifetime to determine when it the TNP system reaches end of life, such as <NUM> days of operation, <NUM> days of operation, <NUM> days of operation, or like. The process <NUM> can determine when the TNP system has reached or exceeded its expected therapy operation life or EOL. When the process <NUM> detects that EOL has been reached, ability of provide negative pressure wound therapy can be disabled. One or more of visual, audible, haptic or tactile indications can be provided as described herein.

Alternatively or additionally, the process <NUM> can determine or indicate presence of a blockage in the fluid flow path based on monitoring a pressure change in the fluid flow path. The negative pressure wound therapy system implementing the process <NUM> can be configured to provide negative pressure wound therapy even in a presence of a low leak, which can correspond to a low leak rate for gas entering the fluid flow path from the external environment (such as, the atmosphere). Such low leak condition can be due to presence of good seal(s) between the dressing and the wound as well as in other portion(s) of the fluid flow path. For example, the system <NUM> illustrated in <FIG> can be configured to provide or maintain negative pressure wound therapy with a leak rate of less than approximately <NUM> mE/min at a target pressure setpoint of approximately -<NUM> mmHg. As another example, the system <NUM> illustrated in <FIG> can be configured to provide or maintain negative pressure wound therapy in canisterless mode with a leak rate of less than approximately <NUM>/min at a target pressure setpoint of approximately -<NUM> mmHg. As yet another example, the system <NUM> can be configured to provide or maintain negative pressure wound therapy in canister mode with a leak rate of less than approximately <NUM> scc/min (or standard cubic centimeters per minute) at a target pressure setpoint of approximately -<NUM> mmHg. The preceding leak rates are provided for illustration and suitable smaller or larger leak rate values can be used depending on the embodiment.

Provision of negative pressure wound therapy in presence of a low leak in the fluid flow path or a blockage in the fluid flow path can be associated with a decreased level of activity of the negative pressure source. In case of a blockage, this decreased level of activity can be due to the reduction of the fluid flow path volume through which the negative pressure source moves fluid, which causes a slow flow through the fluid flow path. In case of the low leak, this decreased level of activity can be due to rather small amount of gas entering the fluid flow path, which likewise causes a slower flow of fluid that the negative pressure source moves through the fluid flow path.

To distinguish between these two operating conditions, the process <NUM> can monitor the pressure change in the fluid flow path. For example, the process <NUM> can activate or turn on the negative pressure source to aspirate fluid from the fluid flow path. If a blockage is present in the fluid flow path, the negative pressure source may be able to reduce pressure in the fluid flow path due to the evacuation of fluid (such as, gas) from the reduced volume in the fluid flow path downstream from the blockage. This reduced volume can include at least a portion of the conduit <NUM> that is downstream from the blockage. Such volume can be on the order of a few milliliters in some cases. The process <NUM> can monitor reduction in the pressure in the fluid flow path and determine or indicate presence of a blockage when the reduced pressure satisfies a value (such as, reaches a blockage threshold). If a blockage is not present in the fluid flow path, but, instead, the system is operating in the presence of a low leak in the fluid flow path, activation of the negative pressure source may not result in a discernable pressure reduction in the fluid flow path because the fluid flow path volume from which the negative pressure source evacuates fluid has not been reduced. This can be particularly so when a canister with a significant volume for storing removed fluids is present in the fluid flow path, such as during operation in canister mode as described herein.

Fluid flow path may not be perfectly sealed, and one or more small leaks can be present in the fluid flow path. For instance, one or more leaks can be present at or near location where a conduit connects to the pump assembly, such as at or near the connector <NUM> or the connector port <NUM>. When a blockage is present, the reduced volume in the fluid flow path downstream from the blockage can depressurize when the negative pressure source is deactivated. For example, due to the one or more leaks, the reduced volume in the fluid flow path downstream from the blockage can attain atmospheric pressure when the negative pressure source is not active. Because of the reduced volume in the fluid flow path downstream from the blockage, such depressurization can occur rapidly. For example, if a canister filter is blocked (such as, due to the canister being full), volume of the fluid flow path downstream from the blockage can be very small because it may only include the conduit connecting the pump assembly to the canister. As another example, when the blockage is upstream from the canister (such as, in a conduit connecting the canister to the wound), volume of the fluid flow path downstream from the blockage can be slightly larger than in the previous example, but still be rather small. Depressurization when the negative pressure source is not active or negative pressure increase when the negative pressure source is activated can occur quite rapidly when one or more blockages are present in the fluid flow path.

For blockage detection, the process <NUM> can activate the negative pressure source for a short duration of time. For example, the process <NUM> can activate the negative pressure source for a period of time that is long enough to permit pressure in the fluid flow path to be reduced in case of a blockage, but short enough to not drain the capacity of the power source. For instance, the process <NUM> can activate the negative pressure source for <NUM> msec, less than <NUM> msec, or more than <NUM> msec. After the duration of time expires, the process <NUM> can deactivate or turn off the negative pressure source.

The process <NUM> can activate the negative pressure source for the duration of time suitable for detecting a blockage in the Turn Pump Off and On and Measure Pressure Decay State <NUM>. The process <NUM> can transition to this state <NUM> from the Maintain Pressure State <NUM>. For example, the process <NUM> can transition to the Turn Pump Off and On and Measure Pressure Decay State <NUM> after establishing (or reestablishing) the target pressure at the wound in the Maintain Pressure State <NUM>. The process <NUM> can periodically transition to the Turn Pump Off and On and Measure Pressure Decay State <NUM>. The duration of time during which the negative pressure source is active in the Turn Pump Off and On and Measure Pressure Decay State <NUM> can be shorter than a duration of time during which the negative pressure source is active in the Maintain Pressure State <NUM>.

In the Turn Pump Off and On and Measure Pressure Decay State <NUM>, the process <NUM> can activate the negative pressure source to determine a pressure change in the fluid flow path. The process <NUM> can determine a first pressure in the fluid flow path before the negative pressure source is activated in the Turn Pump Off and On and Measure Pressure Decay State <NUM>. The process <NUM> can utilize a pressure sensor, as described herein. Prior to, at the time of, or after deactivating the negative pressure source in the Turn Pump Off and On and Measure Pressure Decay State <NUM>, the process <NUM> can determine a second pressure in the fluid flow path. The process <NUM> can determine the pressure change or difference between the first and second pressures. The process <NUM> can compare the pressure difference to a value, such as a blockage threshold, to determine if a blockage is present in the fluid flow path. If the process <NUM> determines that the pressure difference satisfies the value (for instance, reaches or falls below the blockage threshold), the process <NUM> can transition to the Blockage State <NUM>. In that state, the process <NUM> can indicate presence of blockage using any one or more indications described herein. The process <NUM> can additionally or alternatively deactivate the negative pressure source in the Blockage State <NUM>. Provision of negative pressure can be restarted (for example, in the Pump Down State <NUM>) following deactivation of the negative pressure source upon a timeout or user action (such as, a button press).

If the process <NUM> determines that the pressure difference does not satisfy the value (for instance, does not reach the blockage threshold), the process <NUM> can transition to the Low Leak State <NUM>. In that state, the process <NUM> can indicate normal operation in presence of a low leak in the fluid flow path using any one or more indications described herein. The process <NUM> can remain in the Therapy Active <NUM> states. For example, the process <NUM> can transition to the Maintain Pressure State <NUM> from the Low Leak State <NUM>.

The process <NUM> can execute the Turn Pump Off and On and Measure Pressure Decay State <NUM> a number of times prior to indicating presence of a blockage. Such detection can involve consecutive or non-consecutive executions of the State <NUM>. The process <NUM> can transition to the Turn Pump Off and On and Measure Pressure Decay State <NUM> from any state other than the Maintain Pressure State <NUM> or any one or more states.

The process <NUM> can measure pressure change due to activation of the negative pressure source in the Maintain Pressure State <NUM> instead of doing so in the Turn Pump Off and On and Measure Pressure Decay State <NUM>. In the Maintain Pressure State <NUM>, the process <NUM> can determine the pressure change in the fluid flow path as a result of activation of the negative pressure source to restore the target pressure setpoint. As described herein, pressure change can be measured over the entire duration of activation of the negative pressure source or a portion such duration. The process can compare the determined pressure change to a value to indicate presence of a blockage as described herein.

The process <NUM> can measure pressure change due to activation of the negative pressure source in the Pump Down State <NUM> instead of doing so in the Turn Pump Off and On and Measure Pressure Decay State <NUM>. The process <NUM> can indicate presence of a blockage as described herein.

Blockage detection based on monitoring pressure in the fluid flow path as described herein can quickly provide indication of any blockages present in the fluid flow path and allow the user to resolve such blockage quicker such that provision of therapy is not interrupted or interrupted for only a short duration of time.

Additional details regarding operating the negative pressure wound therapy system are described in <CIT>, and titled "SYSTEMS AND METHODS FOR CONTROLLING DUAL MODE NEGATIVE PRESSURE WOUND THERAPY APPARATUS".

Although some of the disclosed embodiments relate to a dual mode negative pressure wound therapy system, the approaches disclosed herein, including blockage detection, can be used in any negative pressure wound therapy system, such as a canister or canisterless system.

Many other variations than those described herein will be apparent from this disclosure. For example, depending on the embodiment, certain acts, events, or functions of any of the steps described herein can be performed in a different sequence, can be added, merged, or left out altogether (e.g., not all described acts or events are necessary for the practice of the processes). Moreover, in certain embodiments, acts or events can be performed concurrently. In addition, different tasks or processes can be performed by different machines and/or computing systems that can function together.

Those skilled in the art will appreciate that in some embodiments, the actual steps taken in the processes illustrated or disclosed may differ from those shown in the figures. For example, the actual steps or order of steps taken in the disclosed processes may differ from those shown in the figure. For instance, the various components illustrated in the figures may be implemented as software or firmware on a processor, controller, ASIC, FPGA, or dedicated hardware. Hardware components, such as processors, ASICs and FPGAs can include logic circuitry.

Conditional language used herein, such as, among others, "can," "might," "may," and "e.g.,", unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements and/or states. Thus, such conditional language is not generally intended to imply that features, elements and/or states are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without author input or prompting, whether these features, elements and/or states are included or are to be performed in any particular embodiment. The terms "comprising," "including," and "having," are synonymous and are used inclusively, in an open-ended fashion, and do not exclude additional elements, features, acts and operations. Additionally, the words "herein," "above," "below," and words of similar import, when used in this application, refer to this application as a whole and not to any particular portions of this application.

Conjunctive language such as the phrase "at least one of X, Y and Z," unless specifically stated otherwise, is to be understood with the context as used in general to convey that an item or term may be either X, Y, or Z, or a combination thereof. Thus, such conjunctive language is not generally intended to imply that certain embodiments require at least one of X, at least one of Y and at least one of Z to each be present.

Unless otherwise explicitly stated, articles such as "a" or "an" should generally be interpreted to include one or more described items. Accordingly, phrases such as "a device configured to" are intended to include one or more recited devices. Such one or more recited devices can also be collectively configured to carry out the stated recitations.

Claim 1:
A negative pressure wound therapy apparatus comprising:
a negative pressure source configured to provide negative pressure via a fluid flow path to a wound covered by a wound dressing, the negative pressure source further configured to be periodically activated to reduce pressure under the wound dressing to approximately a negative pressure set point and be periodically deactivated after pressure under the wound dressing is reduced to approximately the negative pressure set point; and
a controller,
characterised in that the controller is configured to indicate a blockage in the fluid flow path by being further configured to:
activate the negative pressure source for a duration of time to attempt to reduce pressure in the fluid flow path,
deactivate the negative pressure source subsequent to expiration of the duration of time,
determine a pressure change in the fluid flow path over at least part of the duration of time, and
in response to determining that the pressure change in the fluid flow path over the at least part of the duration of time indicates reduction in pressure, provide indication of the blockage in the fluid flow path.