Patent ID: 12233197

DETAILED DESCRIPTION

Overview

Embodiments disclosed herein relate to systems and methods of treating a wound with reduced pressure. As is used herein, reduced or negative pressure levels, such as −X mmHg, represent pressure levels relative to normal ambient atmospheric pressure, which can correspond to 760 mmHg (or 1 atm, 29.93 inHg, 101.325 kPa, 14.696 psi, etc.). Accordingly, a negative pressure value of −X mmHg reflects absolute pressure that is X mmHg below 760 mmHg or, in other words, an absolute pressure of (760−X) mmHg. In addition, negative pressure that is “less” or “smaller” than X mmHg corresponds to pressure that is closer to atmospheric pressure (e.g., −40 mmHg is less than −60 mmHg). Negative pressure that is “more” or “greater” than −X mmHg corresponds to pressure that is further from atmospheric pressure (e.g., −80 mmHg is more than −60 mmHg). In some embodiments, local ambient atmospheric pressure is used as a reference point, and such local atmospheric pressure may not necessarily be, for example, 760 mmHg.

Embodiments of the present invention 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 oedema, encouraging blood flow and granular tissue formation, and/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. In some embodiments, TNP therapy helps 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.

In some embodiments, a negative pressure wound therapy apparatus includes a dressing configured to be placed over a wound and a source of negative pressure configured to be in fluid communication with the dressing. The source of negative pressure is configured to provide negative pressure to the wound. The apparatus can also include a canister configured to collect exudate removed from the wound. The canister can be configured to be in fluid communication with the dressing and the negative pressure source. The apparatus also includes a pressure sensor configured to monitor pressure signals generated by the negative pressure source and a controller. The controller can be configured to determine a level of exudate in the canister (or in the dressing) based at least in part on one or more characteristics of the monitored pressure signals. The one or more characteristics of the pressure signals can change as a level of exudate in the canister increases.

In various embodiments, a method of operating a negative pressure wound therapy apparatus includes monitoring pressure signals generated by a negative pressure source in fluid communication with a dressing and a canister. The method also includes determining a level of exudate in the canister (or in the dressing) based at least in part on one or more characteristics of the monitored pressure signals. The one or more characteristics of the pressure signals can change as a level of exudate in the canister increases.

In some embodiments, systems and methods for determining an amount of flow restriction or reduced volume in front of a negative pressure utilize one or more characteristics of monitored pressure signals. For example, the magnitude of the pressure signals can increase as restriction to flow increase, which effectively reduces the volume in front of a negative pressure source. The volume in front of the negative pressure source may decrease due to filling of a canister or dressing with exudate removed from a wound.

Negative Pressure System

FIG.1illustrates an embodiment of a negative or reduced pressure wound treatment (or TNP) system100comprising a wound filler130placed inside a wound cavity110, the wound cavity sealed by a wound cover120. The wound filler130in combination with the wound cover120can be referred to as wound dressing. A single or multi lumen tube or conduit140is connected the wound cover120with a pump assembly150configured to supply reduced pressure. The wound cover120can be in fluidic communication with the wound cavity110. In any of the system embodiments disclosed herein, as in the embodiment illustrated inFIG.1, the pump assembly can be a canisterless pump assembly (meaning that exudate is collected in the wound dressing is transferred via tube140for collection to another location). However, any of the pump assembly embodiments disclosed herein can be configured to include or support a canister. Additionally, in any of the system embodiments disclosed herein, any of the pump assembly embodiments can be mounted to or supported by the dressing, or adjacent to the dressing. The wound filler130can be any suitable type, such as hydrophilic or hydrophobic foam, gauze, inflatable bag, and so on. The wound filler130can be conformable to the wound cavity110such that it substantially fills the cavity at atmospheric pressure, and also may have a substantially reduced compressed volume when under negative pressure. The wound cover120can provide a substantially fluid impermeable seal over the wound cavity110. In some embodiments, the wound cover120has a top side and a bottom side, and the bottom side adhesively (or in any other suitable manner) seals with wound cavity110. The conduit140or any other conduit disclosed herein can be formed from polyurethane, PVC, nylon, polyethylene, silicone, or any other suitable material.

Some embodiments of the wound cover120can have a port (not shown) configured to receive an end of the conduit140. In some embodiments, the conduit140can otherwise pass through and/or under the wound cover120to supply reduced pressure to the wound cavity110so as to maintain a desired level of reduced pressure in the wound cavity. The conduit140can be any suitable article configured to provide at least a substantially sealed fluid flow pathway between the pump assembly150and the wound cover120, so as to supply the reduced pressure provided by the pump assembly150to wound cavity110.

The wound cover120and the wound filler130can be provided as a single article or an integrated single unit. In some embodiments, no wound filler is provided and the wound cover by itself may be considered the wound dressing. The wound dressing may then be connected, via the conduit140, to a source of negative pressure, such as the pump assembly150. In some embodiments, though not required, the pump assembly150can be miniaturized and portable, although larger conventional pumps such can also be used.

The wound cover120can be located over a wound site to be treated. The wound cover120can form a substantially sealed cavity or enclosure over the wound site. In some embodiments, the wound cover120can be configured to have a film having a high water vapour permeability to enable the evaporation of surplus fluid, and can have a superabsorbing 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, but are not limited to, acute wounds, chronic wounds, surgical incisions and other incisions, subacute and dehisced wounds, traumatic wounds, flaps and skin grafts, lacerations, abrasions, contusions, burns, diabetic ulcers, pressure ulcers, stoma, surgical wounds, trauma and venous ulcers or the like. In some embodiments, the components of the TNP system described herein can be particularly suited for incisional wounds that exude a small amount of wound exudate.

Some embodiments of the system are designed to operate without the use of an exudate canister. Some embodiments can be configured to support an exudate canister. In some embodiments, configuring the pump assembly150and tubing140so that the tubing140can be quickly and easily removed from the pump assembly150can facilitate or improve the process of dressing or pump changes, if necessary. Any of the pump embodiments disclosed herein can be configured to have any suitable connection between the tubing and the pump.

In some embodiments, the pump assembly150can be configured to deliver negative pressure at a desired negative pressure setpoint, which can be selected or programmed to be approximately −80 mmHg, or between about −20 mmHg and −200 mmHg (e.g., as selected by a user). Note that these pressures are relative to normal ambient atmospheric pressure thus, −200 mmHg would be about 560 mmHg in practical terms. In some embodiments, the pressure range can be between about −40 mmHg and −150 mmHg. Alternatively a pressure range of up to −75 mmHg, up to −80 mmHg or over −80 mmHg can be used. Also in other embodiments a pressure range of below −75 mmHg can be used. Alternatively a pressure range of over approximately −100 mmHg, or even 150 mmHg, can be supplied by the pump assembly150.

In some embodiments, the pump assembly150is configured to provide continuous or intermittent negative pressure therapy. Continuous therapy can be delivered at above −25 mmHg, −25 mmHg, −40 mmHg, −50 mmHg, −60 mmHg, −70 mmHg, −80 mmHg, −90 mmHg, −100 mmHg, −120 mmHg, −140 mmHg, −160 mmHg, −180 mmHg, −200 mmHg, or below −200 mmHg. Intermittent therapy can be delivered between low and high negative pressure set points. Low set point can be set at above 0 mmHg, 0 mmHg, −25 mmHg, −40 mmHg, −50 mmHg, −60 mmHg, −70 mmHg, −80 mmHg, −90 mmHg, −100 mmHg, −120 mmHg, −140 mmHg, −160 mmHg, −180 mmHg, or below −180 mmHg. High set point can be set at above −25 mmHg, −40 mmHg, −50 mmHg, −60 mmHg, −70 mmHg, −80 mmHg, −90 mmHg, −100 mmHg, −120 mmHg, −140 mmHg, −160 mmHg, −180 mmHg, −200 mmHg, or below −200 mmHg During intermittent therapy, negative pressure at low set point can be delivered for a first time duration, and upon expiration of the first time duration, negative pressure at high set point can be delivered for a second time duration. Upon expiration of the second time duration, negative pressure at low set point can be delivered. The first and second time durations can be same or different values. The first and second durations can be selected from the following range: less than 2 minutes, 2 minutes, 3 minutes, 4 minutes, 6 minutes, 8 minutes, 10 minutes, or greater than 10 minutes. In some embodiments, switching between low and high set points and vice versa can be performed according to a step waveform, square waveform, sinusoidal waveform, and the like.

In operation, the wound filler130is inserted into the wound cavity110and wound cover120is placed so as to seal the wound cavity110. The pump assembly150provides a source of a negative pressure to the wound cover120, which is transmitted to the wound cavity110via the wound filler130. Fluid (e.g., wound exudate) is drawn through the conduit140, and can be stored in a canister. In some embodiments, fluid is absorbed by the wound filler130or one or more absorbent layers (not shown).

Wound dressings that may be utilized with the pump 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 pump assembly and other embodiments of the present application are found in U.S. Patent Publication Nos. 2012/0116334, 2011/0213287, 2011/0282309, 2012/0136325, 2013/0110058, which are incorporated by reference in their entireties. In other embodiments, other suitable wound dressings can be utilized.

Pump Assembly and Canister

FIG.2Aillustrates a front view200A of a pump assembly230and canister220according to some embodiments. As is illustrated, the pump assembly230and the canister are connected, thereby forming a device. The pump assembly230comprises one or more indicators, such as visual indicator202configured to indicate alarms and visual indicator204configured to indicate status of the TNP system. The indicators202and204can be configured to alert a user to a variety of operating and/or failure conditions of the system, including alerting the user to normal or proper operating conditions, pump failure, power supplied to the pump or power failure, detection of a leak within the wound cover or flow pathway, suction blockage, or any other similar or suitable conditions or combinations thereof. In some embodiments, the pump assembly230can comprise additional indicators. In some embodiments, a single indicator is used. In other embodiments, multiple indicators are used. Any suitable indicator can be used such as visual, audio, tactile indicator, and so on. The indicator202can be configured to signal alarm conditions, such as canister full (or dressing full in case of a canisterless system), power low, conduit140disconnected, seal broken in the wound seal120, and so on. The indicator202can be configured to display red flashing light to draw user's attention. The indicator204can be configured to signal status of the TNP system, such as therapy delivery is ok, leak detected, and so on. The indicator204can be configured to display one or more different colors of light, such as green, yellow, etc. For example, green light can be emitted when the TNP system is operating properly and yellow light can be emitted to indicate a warning.

The pump assembly230comprises a display or screen206mounted in a recess208formed in a case of the pump assembly. In some embodiments, the display206can be a touch screen display. In some embodiments, the display206can support playback of audiovisual (AV) content, such as instructional videos. As explained below, the display206can be configured to render a number of screens or graphical user interfaces (GUIs) for configuring, controlling, and monitoring the operation of the TNP system. The pump assembly230comprises a gripping portion210formed in the case of the pump assembly. The gripping portion210can be configured to assist the user to hold the pump assembly230, such as during removal of the canister220. In some embodiments, the canister220can be replaced with another canister, such as when the canister220has been filled with exudate. The canister220can include solidifier material.

The pump assembly230comprises one or more keys or buttons212configured to allow the user to operate and monitor the operation of the TNP system. As is illustrated, in some embodiments, there buttons212a,212b, and212care included. Button212acan be configured as a power button to turn on/off the pump assembly230. Button212bcan be configured as a play/pause button for the delivery of negative pressure therapy. For example, pressing the button212bcan cause therapy to start, and pressing the button212bafterward can cause therapy to pause or end. Button212ccan be configured to lock the display206and/or the buttons212. For instance, button212ecan be pressed so that the user does not unintentionally alter the delivery of the therapy. Button212ccan be depressed to unlock the controls. In other embodiments, additional buttons can be used or one or more of the illustrated buttons212a,212b, or212ccan be omitted. In some embodiments, multiple key presses and/or sequences of key presses can be used to operate the pump assembly230.

The pump assembly230includes one or more latch recesses222formed in the cover. In the illustrated embodiment, two latch recesses222can be formed on the sides of the pump assembly230. The latch recesses222can be configured to allow attachment and detachment of the canister220using one or more canister latches221. The pump assembly230comprises an air outlet224for allowing air removed from the wound cavity110to escape. Air entering the pump assembly can be passed through one or more suitable filters, such as antibacterial filters. This can maintain reusability of the pump assembly. The pump assembly230includes one or more strap mounts226for connecting a carry strap to the pump assembly230or for attaching a cradle. In the illustrated embodiment, two strap mounts226can be formed on the sides of the pump assembly230. In some embodiments, various of these features are omitted and/or various additional features are added to the pump assembly230.

The canister220is configured to hold fluid (e.g., exudate) removed from the wound cavity110. The canister220includes one or more latches221for attaching the canister to the pump assembly230. In the illustrated embodiment, the canister220comprises two latches221on the sides of the canister. The exterior of the canister220can formed from frosted plastic so that the canister is substantially opaque and the contents of the canister and substantially hidden from plain view. The canister220comprises a gripping portion214formed in a case of the canister. The gripping portion214can be configured to allow the user to hold the pump assembly220, such as during removal of the canister from the apparatus230. The canister220includes a substantially transparent window216, which can also include graduations of volume. For example, the illustrated 300 mL canister220includes graduations of 50 mL, 100 mL, 150 mL, 200 mL, 250 mL, and 300 mL. Other embodiments of the canister can hold different volume of fluid and can include different graduation scale. The canister220comprises a tubing channel218for connecting to the conduit140. In some embodiments, various of these features, such as the gripping portion214, are omitted and/or various additional features are added to the canister220.

FIG.2Billustrates a rear view200B of the pump assembly230and canister220according to some embodiments. The pump assembly230comprises a speaker port232for producing and/or radiating sound. The pump assembly230includes a filter access door234for accessing and replacing one or more filters, such as odor filter, antibacterial filters, etc. In one embodiment, the access door234can be used to access a chamber (such as a plenum chamber) in which noise suppressing or sound absorbing material is placed. The chamber and sound absorbing material can be part of a silencing system that is used to suppress or absorb noise generated by the source of negative pressure. Sound absorbing material can serve to break up sound waves as travel (or reverberate) through the chamber. Sound absorbing material can further function as an odor suppressant. In one embodiment, for example, sound absorbing material can be impregnated with activated charcoal for odor suppression. The access door234can further include a seal (such as a sealing gasket) for tight closure of the chamber. Additional details of the silencing system are described in U.S. Patent Publication No. 2010/0185165, which is incorporated by reference in its entirety.

The pump assembly230comprises a gripping portion236formed in the case of the pump assembly. As is illustrated, the gripping portion236is a recess formed in the outer casing of the pump assembly230. In some embodiments, the gripping portion236may include rubber, silicone, etc. coating. The gripping portion236can be configured (e.g., positioned and dimensioned) to allow the user to firmly hold the pump assembly230, such as during removal of the canister220. The pump assembly230includes one or more covers238configured as screw covers and/or feet or protectors for placing the pump assembly230on a surface. The covers230can be formed out of rubber, silicone, or any other suitable material. The pump assembly230comprises a power jack239for charging and recharging an internal battery of the pump assembly. In some embodiments, the power jack239is a direct current (DC) jack. In some embodiments, the pump assembly can comprise a disposable power source, such as batteries, so that no power jack is needed.

The canister220includes one or more feet244for placing the canister on a surface. The feet244can be formed out of rubber, silicone, or any other suitable material and can be angled at a suitable angle so that the canister220remains stable when placed on the surface. The canister220comprises a tube mount relief246configured to allow one or more tubes to exit to the front of the device. The canister220includes a stand or kickstand248for supporting the canister when it is placed on a surface. As explained below, the kickstand248can pivot between an opened and closed position. In closed position, the kickstand248can be latched to the canister220. In some embodiments, the kickstand248can be made out of opaque material, such as plastic. In other embodiments, the kickstand248can be made out of transparent material. The kickstand248includes a gripping portion242formed in the kickstand. The gripping portion242can be configured to allow the user to place the kickstand248in the closed position. The kickstand248comprises a hole249to allow the user to place the kickstand in the open position. The hole249can be sized to allow the user to extend the kickstand using a finger.

FIG.2Cillustrates a view200C of the pump assembly230separated from the canister220according to some embodiments. The pump assembly230includes a vacuum attachment or connector252through which a vacuum pump communicates negative pressure to the canister220. The connector252can correspond to the inlet of the pump assembly. The pump assembly230comprises a USB access door256configured to allow access to one or more USB ports. In some embodiments, the USB access door is omitted and USB ports are accessed through the door234. The pump assembly230can include additional access doors configured to allow access to additional serial, parallel, and/or hybrid data transfer interfaces, such as SD, Compact Disc (CD), DVD, FireWire, Thunderbolt, PCI Express, and the like. In other embodiments, one or more of these additional ports are accessed through the door234.

FIG.2Dillustrates a view200D of the interior components of the pump assembly230according to some embodiments. The pump assembly230can include various components, such as a canister connector252which includes a sealing ring253, control printed circuit board (PCB)260, peripherals PCB262(e.g., for USB connectivity), power supply PCB264, vacuum pump266, power supply268(e.g., rechargeable battery), speaker270, and light guide or pipe272(e.g., for status indication using guided light emitted by one or more LEDs). Further details of status indication are provided in U.S. Pat. No. 8,294,586, which is incorporated by reference in its entirety. Other components can be included, such as electrical cables, connectors, tubing, valves, filters, fasteners, screws, holders, and so on. In some embodiments, the pump assembly230can comprise alternative or additional components.

FIG.2Eillustrates another view200E of the interior components of the pump assembly230according to some embodiments. As is explained below, the pump assembly230includes an antenna276. The connector252between the vacuum pump266and the canister220includes a flow restrictor278. As is explained below, the flow restrictor278can be a calibrated flow restrictor used for measuring flow in the fluid flow path and for determining various operating conditions, such as leaks, blockages, high pressure (over-vacuum), and the like. In some embodiments, flow across the restrictor278can be determined by measuring a pressure differential (or pressure drop) across the flow restrictor. In various embodiments, flow across the restrictor278can be characterized as high flow (e.g., due to a leak), low flow (e.g., due to a blockage or canister being full), normal flow, etc. As is illustrated, pressure sensor284measures pressure upstream (or on the canister side) of the flow restrictor278. Pressure sensor284can be an electronic pressure sensor mounted on the control PCB264. Conduit or lumen286can connect the upstream side of the flow restrictor278with the pressure sensor284. Pressure sensors280and282measure pressure downstream (or on the vacuum pump side) of the flow restrictor278. Pressure sensors280and282can be electronic pressure sensors mounted on the control PCB264. Conduit or lumen288can connect the downstream side of the flow restrictor278with the pressure sensors280and284via a Y-connector289.

In some embodiments, one of pressure sensors280and282can be designated as a primary pressure sensor and the other as a backup pressure sensor in case the primary pressure sensor becomes defective or inoperative. For example, pressure sensor280can be the primary pressure sensor and pressure sensor282can be the backup pressure sensor. Pressure drop across the flow restrictor278can be determined by subtracting pressure measured by sensor280and sensor284. If pressure sensor280fails, pressure drop across the flow restrictor can be determined by subtracting pressure measured by sensor282and sensor284. In certain embodiments, the backup pressure sensor can be used for monitoring and indicating high pressure conditions, that is when the pressure in the flow path exceeds a maximum pressure threshold. In some embodiments, one or more differential pressure sensors can be used. For example, a differential pressure sensor connected to the upstream and downstream sides of the flow restrictor278can measure the pressure drop across the flow restrictor. In some embodiments, one or more of these components, such as the flow restrictor278, are omitted and/or additional components, such as one or more flow meters, are used.

Flow Rate Monitoring

FIG.3illustrates a fluid flow path300A according to some embodiments. The flow path300A includes a wound cavity310, canister320, pressure sensor330, and source of negative pressure340. The flow of fluid is from left to right (e.g., from the wound310to the negative pressure source340).FIG.3illustrates a fluid flow path300B according to some embodiments. The flow path300B includes the wound310cavity, pressure sensor330, canister320, and source of negative pressure340. The flow of fluid is from left to right (e.g., from the wound cavity310to the negative pressure source340). As is illustrated, the difference between flow paths300A and300B is the positioning of the pressure sensor330. In fluid flow path300A the pressure sensor330is located downstream of the canister320(e.g., at the inlet of the negative pressure source340), while in the fluid flow path300B the pressure sensor330is located upstream of the canister320.

Some embodiments of the system monitor and/or determine a rate of flow of fluid in the system. In certain embodiments, flow rate monitoring can be performed by a controller or processor. Monitoring the flow rate can be used, among other things, to ensure that therapy is properly delivered to the wound, to detect blockages, canister full (or dressing full in case of a canisterless system) conditions, and/or leaks in the fluid flow path, high pressure, ensure that the flow rate is not unsafe (e.g., dangerously high), etc.

In some embodiments, the system performs flow rate monitoring indirectly by measuring and/or monitoring activity of the negative pressure source. For example, speed of vacuum pump motor can be measured, such as, by using a tachometer. A pump control processor can continuously monitor the pump speed using the tachometer feedback from the pump. If pump speed falls below a threshold value over a particular period of time, such as 2 minutes, it can be determined that a blockage is present in the flow path, particularly in systems in which an minimum pump speed is expected (e.g., due to a presence of a controlled leak). The blockage can be due to a blockage in a tube or lumen, canister (or dressing) being full, etc. An alarm can be triggered and the system can wait for the user to take one or more actions to resolve the blockage. In some embodiments, activity of the negative pressure source can be measured by one or more other suitable techniques, such as by using a pump speed sensor (e.g., Hall sensor), measuring back EMF generated by the pump motor, and the like. A pump control processor can continuously monitor voltage and/or current at which the pump is being driven, and determine the activity of the negative pressure source based on the monitored voltage and/or current and load on the pump. In some embodiments, pulse frequency (e.g., pressure signal frequency) can be monitored (e.g., using one or more pressure sensors) to determine the activity of the negative pressure source. For example, a count of pressure pulses can be used as an indicator of the activity of the negative pressure source.

In various embodiments, tachometer can be read periodically, such as every 100 msec, and periodic readings made over a time duration, such as 2.5 seconds, 32 second, or any other suitable duration can be combined (e.g., averaged). Combined tachometer readings can be used for leak detection, blockage detection, limiting the maximum flow rate, etc. Combined tachometer readings (e.g., in counts) can be converted to a flow rate (e.g., in mL/min) using one or more conversion equations and/or tables so that a current flow rate is determined. In some embodiments, the flow rate is determined according to the following equation:
FR=C1*F*P+C2where FR is the flow rate, F is the frequency of the pump tachometer signal, P is pressure produced by the pump (or pressure setpoint), and C1and C2are suitable constants. The determined flow rate can be compared to various flow rate thresholds, such as blockage threshold, leakage threshold, and maximum flow rate threshold, to determine a presence of a particular condition, such as a blockage, leakage, and over-vacuum.

Other suitable ways for determining flow rate can be used. For example, the flow rate can be periodically computed, such as every 250 milliseconds or any other suitable time value, according to the following formula:
FR=Slope*Tachometer+Interceptwhere Tachometer is an average of tachometer readings (e.g., in Hz), such as over last 2.5 second or any other suitable period of time, and Slope and Intercept are constants that are based on the pressure setpoint. The values for Slope and Intercept can be determined for possible pressure setpoints (e.g., −25 mmHg, −40 mmHg, −50 mmHg, 60 mmHg, −70 mmHg, −80 mmHg, −90 mmHg, −100 mmHg, −120 mmHg, −140 mmHg, 160 mmHg, −180 mmHg, −200 mmHg) for a given vacuum pump type. The flow as a function of the pump speed may not be a best fit as a single line because the vacuum pump can be designed to be more efficient at lower flow rates. Because of this, slope and intercept values can be pre-computed for various setpoints and various pumps. Flow rate can be measured in standard liters per minute (SLPM) or any other suitable measurement unit.

In some embodiments, a blockage condition is detected when the determined flow rate falls below a blockage threshold. A blockage alarm can be enabled if the blockage condition is present over a period of time, such as 30 seconds. The blockage alarm can be disabled when the determined flow rate exceeds the blockage threshold. In some embodiments, the system can differentiate between a blockage in a tube or lumen and canister (or dressing) full conditions. In some embodiments, a leakage condition is detected when the determined flow rate exceeds a leakage threshold. A leakage alarm can be enabled if the leakage condition is present over a period of time, such as 30 seconds. The leakage alarm can be disabled when the detected flow rate falls below the leakage threshold. In some embodiments, in order to prevent an over-vacuum condition, a maximum flow rate is imposed, such as 1.6 liters/min. Pump drive signal, such as voltage or current signal, can be limited not exceed the flow rate threshold.

In certain embodiments, one or more pressure sensors can be placed in suitable locations in the fluid flow path. Pressure measured by the one or more sensors is provided to the system (e.g., pump control processor) so that it can determine and adjust the pump drive signal to achieve a desired negative pressure level. The pump drive signal can be generated using PWM. Additional details of flow rate detection and pump control are provided in U.S. Patent Application No. 2013/0150813, which is incorporated by reference in its entirety.

In some embodiments, flow rate monitoring is performed by measuring flow through a flow restrictor placed in a portion of the fluid flow path. In certain embodiments, flow restrictor278illustrated inFIG.2Ecan be used. The flow restrictor can be calibrated such that it can be used to reliably monitor flow rate for different types of wounds, dressings, and operating conditions. For example, a high precision silicon flow restrictor can be used. As another example, the flow restrictor can be built using other suitable materials. The flow restrictor can be located at any suitable location in the flow path, such as between the source of the negative pressure and the canister, such as upstream of the source of the negative pressure and downstream of the canister. A differential pressure sensor or two pressure sensors can be used to measure a pressure drop across the flow restrictor. For example, as explained above in connection withFIG.2E, the pressure drop across the flow restrictor278can be measured using sensors282and284. In certain embodiments, if the pressure drop falls below a pressure differential threshold, which indicates low flow, the measured flow rate is compared to a flow rate threshold. If the measured flow rate falls below the flow rate threshold, blockage condition is detected. Additional details of blockage detection are provided in U.S. Patent Publication No. 2011/0071483, which is incorporated by reference in its entirety. In some embodiments, the measured flow rate is compared to a leakage threshold. If the measured flow rate exceeds the leakage threshold, a leak is detected. Additional details of leakage detection are provided in U.S. Pat. No. 8,308,714, which is incorporated by reference in its entirety.

Blockage Detection

In some embodiments, blockages and presence of exudate in one or more tubes or lumens are detected by processing data from one or more pressure sensors, such as sensors280,282, and284. This detection can be enhanced by changing one or more settings of the vacuum pump, such as increasing vacuum level delivered by the pump, decreasing the vacuum level, stopping the pump, changing the pump speed, changing a cadence of the pump, and the like. In some embodiments, as the pump operates, it generates pressure pulses or signals that are propagated through the fluid flow path. The pressure signals are illustrated in the pressure curve402ofFIG.4according to some embodiments. As is illustrated in region404, pressure in the fluid flow path varies or oscillates around a particular pressure setting or set point408(e.g., as selected by the user) during normal operation of the system. Region406illustrates pressure pulses in the flow path when there is a blockage distal to the negative pressure source, such as the canister (or dressing) becomes full and/or a canister filter is occluded or blocked. As is illustrated, a distal blockage causes a reduced volume to be seen upstream of the canister (or dressing), and the amplitude of the pressure pulses increases. The frequency of a pressure signal is slowed or decreased in some embodiments. In certain embodiments, this change or “bounce” in the magnitude (or frequency) of the pressure pulse signal can be magnified or enhanced by varying the pump speed, varying the cadence of the pump, such as by adjusting PWM parameters, and the like. Such adjustments of pump operation are not required but can be performed over short time duration and the changes can be small such that the operation of the system remains relatively unaffected. In some embodiments, the canister filter can be hydrophobic so that the flow of liquid is substantially blocked while the flow of air is allowed. Additional details of flow rate detection are described in U.S. Patent Publication No. 2012/0078539, which is incorporated by reference in its entirety.

In some embodiments, canisterless systems use absorbent dressing for exudate removed from the wound. Such dressing may include absorbing or superabsorbing material to collect and/or retain exudate so that it is not aspirated into the negative pressure source. Similar to a canister filter, a dressing filter (which may be hydrophobic) may be used to prevent the exudate from reaching the negative pressure source. In such systems, detection of a dressing full condition or dressing filter (which may be) occluded condition can be an equivalent to detection of a canister full condition.

In some embodiments, changes in characteristics of pressure signals can be used to determine distal blockages, level of exudate in the canister (or dressing), canister (or dressing) full conditions, and the like. The characteristics can include signal magnitude, frequency, shape (e.g., envelope), etc. In some embodiments, the system can detect canister (or dressing) pre-full condition or the level of exudate in the canister (or dressing) reaching a certain threshold, which may be less than being approximately 100% full. For example, the system can detect the canister (or dressing) being 75% full, 80% full, 95%, and so on. Advantageously, such detection mechanisms can provide earlier indication of the need to change the canister (or dressing) and avoid prolonged interruption of the delivery of therapy. Sensitivity of alarms can be increased. In various embodiments, the level of a leak in present in the fluid flow path does not affect accurate determination of the level of exudate in the canister and/or detection of the canister (or dressing) pre-full or full conditions.

FIGS.5A-5Dillustrates graphs of pressure signals according to some embodiments. The illustrated graphs can correspond to a particular pressure setting, such as 40 mmHg. The illustrated graphs can also correspond to various leak levels of leak rates in the system. For example,FIG.5Amay correspond to 60 mL/min leak (e.g., low leak),FIG.5Bmay correspond to a 150 mL/min leak,FIG.5Cmay correspond to a 450 mL/min leak, andFIG.5Dmay correspond to a 1000 mL/min leak (e.g., very high leak).FIG.5Aillustrates a magnitude curve502A of the pressure signal in the flow path as sensed by one or more pressure sensors over a period of time. Curve502A can correspond to a signal observed when the canister is relatively empty. For example, the canister may be configured to hold up to 750 mL fluid volume, and curve502A can correspond to the empty volume of 515 mL. As is illustrated, the bounce in the pressure signal magnitude curve502A is relatively small as the curve is substantially flat. The bounce of the pressure signal can be measured using a variety of techniques, such as by measuring peak-to-trough change and selecting the largest such change as being indicative of the largest bounce. Curve502A can correspond to the voltage reading, current reading, etc. Curve504A corresponds to a pump speed signal (e.g., as measured by a tachometer, PWM signal, etc.).

FIG.5Billustrates a magnitude curve502B of the pressure signal in the flow path as sensed by one or more pressure sensors over a period of time. Curve502B can correspond to a signal observed when the canister is relatively full. For example, the canister may be configured to hold up to 750 mL volume, and curve502B can correspond to the empty volume of 60 mL. As is illustrated, the bounce in the pressure signal magnitude curve502B is larger than that in curve502A. Curve504B corresponds to the pump speed signal.FIG.5Cillustrates a magnitude curve502C of the pressure signal in the flow path as sensed by one or more pressure sensors over a period of time. Curve502C can correspond to a signal observed when the canister is almost full. For example, the canister may be configured to hold up to 750 mL volume, and curve502C can correspond to the empty volume of 30 mL. As is illustrated, the bounce in the pressure signal magnitude curve502B is larger than that in curves502A and502B. Curve504C corresponds to the pump speed signal.

FIG.5Dillustrates a magnitude curve502D of the pressure signal in the flow path as sensed by one or more pressure sensors over a period of time. Curve502D can correspond to a signal observed when the canister is nearly full. For example, the canister may be configured to hold up to 750 mL volume, and curve502D can correspond to the empty volume of 15 mL. As is illustrated, the bounce in the pressure signal magnitude curve502D is larger than that in curves502A,502B, and502C. Curve504D corresponds to the pump speed signal.

Table 1 illustrates the largest magnitude bounces or peak-to-trough changes (e.g., in voltage as indicated by Vp-p) measured for the curves502A,502B,502C, and502D according to some embodiments. With reference to the first row (row 1), column A corresponds to curve502A and indicates the largest change of 0.010 V, column B corresponds to curve502D and indicates the largest change of 0.078 V, column C corresponds to curve502C and indicates the largest change of 0.122 V, and column D corresponds to curve502D and indicates the largest change of 0.170 V. These increasing bounce values confirm that the bounce in the pressure signal magnitude increases as the canister fills up. Level of exudate in the canister (or the dressing) can be detected by comparing the determined pressure magnitude bounce to one or more magnitude thresholds, which can be determined experimentally for canisters (or dressing) of various sizes. For example, canister (or dressing) pre-full condition may be set to the canister having 30 mL or less empty volume. Using Table 1, a pre-full threshold can be set to approximately 0.12 V peak-to-trough bounce. In some embodiments, measures other than or in addition to peak-to-trough can be used, such as average bounce, etc.

TABLE 1Pressure Magnitude Bounce at 40 mmHgDCBAPressure Magnitude15 mL30 mL60 mL515 mL(Vp−p) at 40 mmHgvolumevolumevolumevolume160 mL/min0.1700.1220.0780.0102150 mL/min0.1740.1200.0740.0123450 mL/min0.1780.1180.0680.00841000 mL/min0.1240.0820.0500.012

In some embodiments, signal processing techniques can be utilized on the detected pressure signal. For example, sensed pressure values can be processed, such as low-pass filtered (e.g., via averaging), to remove noise. As another example, detected pressure signal can be converted into frequency domain, for example by using the Fast Fourier Transform (FFT). The signal can be processed and analyzed in frequency domain.

FIGS.6A-6Dillustrates graphs of pressure signals according to some embodiments. Similar toFIGS.5A-5D, these graphs illustrate pressure magnitude curves and pump speed curves at 150 mL/min leak for unfilled canister volumes of 515 mL, 60 mL, 30 mL, and 15 mL. As is illustrated inFIGS.6A-6Dand confirmed by the values in the second row (row 2) of Table 1, the bounce in the pressure signal increases as the canister fills up.FIGS.7A-7Dillustrates graphs of pressure signals according to some embodiments. Similar toFIGS.5A-5D, these graphs illustrate pressure magnitude curves and pump speed curves at 450 mL/min leak for unfilled canister volumes of 515 mL, 60 mL, 30 mL, and 15 mL. As is illustrated inFIGS.7A-7Dand confirmed by the values in the third row (row 3) of Table 1, the bounce in the pressure signal increases as the canister fills up.FIGS.8A-8Dillustrates graphs of pressure signals according to some embodiments. Similar toFIGS.5A-5D, these graphs illustrate pressure magnitude curves and pump speed curves at 1000 mL/min leak (which is a very high leak) for unfilled canister volumes of 515 mL, 60 mL, 30 mL, and 15 mL. As is illustrated inFIGS.8A-8Dand confirmed by the values in the fourth row (row 4) of Table 1, the bounce in the pressure signal increases as the canister fills up. From the illustrations inFIGS.5-8and the values in Table 1, it can be seen that detection of the level of exudate in the canister (or in the dressing) and/or canister (or dressing) pre-full condition can be performed irrespective of the leak rate in the fluid flow path.

As is illustrated inFIGS.5-8and Table 1, the bounce or ripple in the observed pressure magnitude increases as the canister fills up and the volume “seen” by the pump decreases.FIG.9illustrates sensed pressure magnitude ripple according to some embodiments. The y-axis represents largest peak-to-trough voltage changes. The x-axis corresponds to canister unfilled volumes (e.g., volume ahead or upstream of the pump). A 750 mL, canister is used according to some embodiments. There are four curves illustrated corresponding to target pressure settings of 40 mmHg, 80 mmHg, 120 mmHg, and 200 mmHg. Vertical bars on the curves represent variation resulting from the changes to the leak rate. Table 2 illustrates the plotted values according to some embodiments. As is illustrated inFIG.9and Table 2, magnitude of the pressure bounce increases as the canister becomes full irrespective of the leak rate for various pressure settings.

TABLE 215 mL30 mL60 mL515 mLVp−p*volumevolumevolumevolume40 mmHg0.174 ± 0.0080.120 ± 0.0040.073 ± 0.0100.010 ± 0.00480 mmHg0.119 ± 0.0150.081 ± 0.0060.049 ± 0.0020.008 ± 0.000120 mmHg0.095 ± 0.0050.061 ± 0.0050.037 ± 0.0020.006 ± 0.000200 mmHg0.056 ± 0.0000.037 ± 0.0090.027 ± 0.0090.008 ± 0.000(* 1000 mL/min data was excluded)

In some embodiments, thresholds for determining the level of exudate in the canister (or the dressing) and/or canister (or dressing) pre-full condition can be determined for various pressure settings and various canister volumes. For example, Table 3 illustrates the largest magnitude bounces or peak-to-trough changes for 80 mmHg pressure setting according to some embodiments. Similar tables can be constructed for other possible pressure settings. Level of exudate in the canister/dressing (and, accordingly, a measure of how empty the canister/dressing is), canister/dressing pre-full condition, and/or canister/dressing full condition can be determined at run time by loading a table corresponding to a particular selected pressure setting and comparing the monitored pressure signal magnitude bounce to one or more thresholds. Other suitable data structures can be used in place of a table, such as array, list, index, graph, etc.

TABLE 3Pressure Magnitude Bounce at 80 mmHgDCBAPressure Magnitude15 mL30 mL60 mL515 mL(Vp−p) at 80 mmHgvolumevolumevolumevolume160 mL/min0.1140.0780.0480.0082150 mL/min0.1160.0840.0500.0083450 mL/min0.1280.0800.0500.00841000 mL/min0.0920.0580.0340.010

In some embodiments, frequency of the detected pressure signal can be used in addition to or instead of changes in amplitude for detection of canister (or dressing) pre-full conditions and/or for determining the level of exudate in the canister (or dressing). For example, Table 4 illustrates pressure signal frequencies at 40 mmHg pressure setting for various unfilled canister volumes at various leak rates according to some embodiments. As is shown in Table 4, the frequency of the detected pressure signal decreases or drops as the canister becomes full (e.g., compare column A corresponding to 515 mL unfilled canister volume to column D corresponding to 15 mL unfilled canister volume). This change in the frequency is observed irrespective of the leak rate. The frequency of the detected pressure signal can be compared to one or more frequency thresholds, which may be determined experimentally, to detect canister (or dressing) pre-full condition and/or detect the level of exudate in the canister (or dressing).

TABLE 4Pressure Signal Frequency at 40 mmHgDCBAPressure Frequency15 mL30 mL60 mL515 mLat 40 mmHg (Hz)volumevolumevolumevolume160 mL/min2.592.672.672.622150 mL/min3.513.763.753.533450 mL/min6.626.946.996.9441000 mL/min13.1612.9912.6613.89

In some embodiments, similar tables can be constructed for other possible pressure settings. For example, Table 5 illustrates pressure signal frequencies at 80 mmHg pressure setting for various unfilled canister volumes at various leak rates according to some embodiments. Level of exudate in the canister (or dressing), canister (or dressing) pre-full condition, and/or canister (or dressing) full condition can be determined at run time by loading a table (or another suitable data structure) corresponding to a particular selected pressure setting and comparing the monitored pressure signal frequency to one or more thresholds. The thresholds can be determined experimentally for various canister (or dressing) volumes.

TABLE 5Pressure Signal Frequency at 80 mmHgDCBAPressure Frequency15 mL30 mL60 mL515 mLat 80 mmHg (Hz)volumevolumevolumevolume160 mL/min3.763.833.823.822150 mL/min4.984.674.814.883450 mL/min8.268.478.268.2041000 mL/min15.3815.6315.1515.87

In some embodiments, additional attributes can be used for canister (or dressing) pre-full detection and/or determination of the level of exudate in the canister (or dressing). For example, flow rate through the flow path can be used in addition to analyzing the pressure magnitude. In some embodiments, flow rate can be measured indirectly by measuring and analyzing the pump speed as is disclosed in U.S. Patent Publication No. 2012/0001762, which is incorporated by reference in its entirety. In some embodiments, flow rate can be measured directly by using a flow meter. In some embodiments, increase in the pressure magnitude bounce and decrease in the flow rate (e.g., pump speed, such as reflected by a slowing tachometer) indicates a canister (or dressing) full condition. Decrease in the pump speed alone may not be a reliable indicator of the canister full condition as such decrease can be caused by an improved seal and resulting lowering of the leak rate. In addition, presence of a small leak in the flow path may cause the pump to continue working even though the canister may be nearly full or frill, which can cause inaccurate detection of the canister full condition.

In some embodiments, detection of canister (or dressing) pre-full and/or full conditions using the characteristics of the pressure signals can allow the system to differentiate between blockage conditions in the fluid flow path and blockages in the canister (or in the dressing). In some embodiments, alarm sensitivity is improved. For example, canister full detection mechanisms in systems that do not use characteristics of the pressure signal may rely solely on the flow rate measurements (e.g., as indicated by pump speed measurements) for determining whether the canister is full. Using characteristics of the pressure signal as disclosed herein can trigger the canister frill alarm much earlier, such as for example 20 or more minutes earlier. Advantageously, improving alarm sensitivity can result in increasing safety and patient comfort as the canister can be changed timely before it becomes full and therapy is interrupted.

FIG.10illustrates a process1000of detecting proximal blockages according to some embodiments. The process1000can be implemented by a controller of processor. The process1000measures one or more pressure signal characteristics in block1002. For example, pressure signal magnitude, frequency, etc. can be measured. In block1004, the process1000removes noise from the one or more measured pressure signal characteristics. For example, the pressure signal can be low pass filtered. In block1006, the process1000compares the one or more pressure signal characteristics to one or more thresholds. If in block1008the process1000determines that the one or more thresholds have been satisfied (e.g., exceeded), the process transitions to block1012where it determines that there is a proximal blockage (e.g., due to the canister being full). The process1000can activate one or more alarms or indicators. If in block1008the process1000determines that the one or more thresholds have not been satisfied (e.g., not exceeded), the process transitions to block1010where it determines that there is no proximal blockage. In some embodiments, the process1000can use hysteresis in block1008. For example, the process1000can transition to block1012provided that a threshold has been met (e.g., exceeded) for a duration or period of time. In some embodiments, the one or more thresholds utilized by the process1000can be selected to determine canister (or dressing) pre-full condition and/or a particular level of exudate in the canister (or dressing). Process1000can be implemented by systems with canisters or by canisterless systems.

In some embodiments, canister (or dressing) full condition can be detected as follows. A plurality of pressure sensor readings, each performed over a time duration (e.g., 2 seconds or any other suitable duration which may be vary between sample periods), are collected. A number of readings of the plurality of readings, such as 25 sample periods out of 30 or any other suitable number, are checked to determine if each indicates that the canister is full. This can performed by determining maximum and minimum pressure values captured over the time duration of a particular sample period. The values can be voltage values, current values, or any other suitable values that correspond to pressure. A difference between maximum and minimum values for a particular sample period corresponds to peak-to-through pressure (which is indicative of change in pressure pulse amplitude). If it is determined that the peak-to-through pressure for a particular sample period exceeds a threshold pressure value, then the particular sample period indicates that the canister is full.

The threshold value can be any suitable pressure threshold, such as a value selected or determined based on the negative pressure setpoint and the current level of activity of the pump, which as explained above can be determined using a tachometer average (such as averaged tachometer readings or any other suitable measure of the flow rate). For example, threshold values listed in Table 1 can be used for comparing to peak-to-through pressure. These values correspond to a particular pump motor and particular pressure sensor.

TABLE 6Threshold values for detecting canister full conditionTachometerPeak-to-ThroughSetpointFrequency (in Hz)Pressure (in mV)(in mmHg)LowMedHighLowMedHigh251725<2550110215402335<3575135220503050<5090175225603055<5580185225704060<60115185235804060<60100165235904565<651101702351004565<651051652351204575<751051752351405085<851101902351606090<9011016522018075100<10013016522020075100<100125155210

Canister full determination can be performed on a sliding window basis. For example, a sliding window of 25 out of 30 sample periods can be analyzed and if 25 sample periods are determined to indicate that the canister is full, the pump concludes that the canister (or dressing) is full. Assuming that the sample period is 2 seconds, using a sliding window of 25 out of 30 sample periods effectively results in determining whether change in pressure pulse amplitude exceeds the threshold for 60 seconds. If the tachometer average becomes greater than a leak threshold (e.g., flow rate associated with presence of a leak in the flow path) or canister pressure (as measured by a pressure sensor) becomes less than a low vacuum pressure threshold (e.g., flow rate associated with a low vacuum condition in the flow path), canister full detection can be suspended or terminated. For example, if a sliding window of 25 out of 30 sample periods with each sample period having duration of 2 seconds in used, 60 second timer for canister full detection can be reset when it has been determined that the tachometer average becomes greater than the leak threshold or canister pressure becomes less than the low vacuum pressure threshold. This can prevent generation of unnecessary and undesirable alarms.

Alternatively or additionally, canister full condition can be detected if a single sample period indicates that the canister is full. However, performing canister full detection using a plurality of sample periods can mitigate the effects of one or more transient conditions in the fluid flow path or one or more errant pressure readings. Alternatively or additionally, canister full detection can be performed by measuring the frequency of detected pressure signal and comparing the measured frequency to one or more suitable thresholds.

In some embodiments, additional or alternative mechanisms can be used for detecting proximal blockages. One or more additional pressure sensors can be used to measure differential pressure across the canister (e.g., at the canister inlet and outlet). One or more additional conduits (e.g., dual lumens) can be used to inject a signal through one lumen for detection by another lumen. Flow rate can be measured directly or indirectly and used for canister blockage detection. A bias leak can be introduced into the flow path and maintained such that flow rate dropping below the bias leak rate indicates a presence of a blockage in the flow path. Optical sensors, ultrasonic sensors, and/or weight sensors can be used to determine the level of exudate in the canister (or dressing). Lasers can also be used. One or more sensors that are not related to measuring pressure and/or flow, such as a capacitive sensor or a strain gauge, can be used.

In some embodiments, temporary blockages caused by slugs or boluses of fluid in tubes and/or lumens are detected by turning off the pump and monitoring the pressure change in the fluid flow path. The pump can be turned off for a short duration of time as to not affect the operation of the system. Presence of temporary blockages in the system due to boluses of fluid can cause a detectable difference in pressure decay in the device including a discontinuous “stair and risers” pattern in a system with a distal leak. Such discontinuous decaying pattern may be due to boluses of fluid moving through the fluid flow path and arriving at the canister inlet, which can suddenly change the volume seen by the pressure sensor (and the canister or the dressing). When boluses of fluid are not present, a more continuous decaying pattern may be is observed. In certain embodiments, when the discontinuous “stairs and risers” pattern is detected, the system can increase the level of vacuum produced by the pump to clear the boluses. An alarm can be asserted if the tubes and/or lumens cannot be cleared.

In some embodiments, one or more flow sensors and/or flow meters can be used to directly measure the fluid flow. In some embodiments, the system can utilize one or more of the foregoing flow rate monitoring techniques. The system can be configured to suitably arbitrate between flow rates determined using multiple flow rate monitoring techniques if one or more such techniques are executed in parallel. In certain embodiments, the system execute one of the techniques, such as the flow rate determination based on the pump speed, and utilize one or more other techniques as needed. In various embodiments, the system can utilize one or more other techniques in cases the determined flow rate or flow path condition is perceived to be inaccurate or unreliable. In some embodiments, the system can utilize one or more of the techniques to detect a sudden change in a flow rate suggesting change to the dressing leak characteristics (e.g., a greater flow indicates the development of a leak and a lesser flow indicating a sudden restriction or blockage).

OTHER VARIATIONS

Any value of a magnitude, frequency, threshold, limit, duration, etc. provided herein and/or illustrated in the figures is not intended to be absolute and, thereby, can be approximate. In addition, any magnitude, frequency, threshold, limit, duration, etc. provided herein and/or illustrated in the figures can be fixed or varied either automatically or by a user. Moreover, any value of a magnitude, frequency, threshold, limit, duration, etc. provided herein and/or illustrated in the figures is illustrative and can change depending on an embodiment. For example, the values provided in the tables (Tables 1-5) can vary depending on canister (or dressing) volume, sensor range, etc. Furthermore, as is used herein relative terminology such as exceeds, greater than, less than, etc. in relation to a reference value is intended to also encompass being equal to the reference value. For example, exceeding a reference value that is positive can encompass being equal to or greater than the reference value. In addition, as is used herein relative terminology such as exceeds, greater than, less than, etc. in relation to a reference value is intended to also encompass an inverse of the disclosed relationship, such as below, less than, greater than, etc. in relations to the reference value.

Features, materials, characteristics, or groups described in conjunction with a particular aspect, embodiment, or example are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed (such as the process illustrated inFIG.10), may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The protection is not restricted to the details of any foregoing embodiments. The protection extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of protection. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms. Furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made. Those skilled in the art will appreciate that in some embodiments, the actual steps taken in the processes illustrated and/or disclosed may differ from those shown in the figures. Depending on the embodiment, certain of the steps described above may be removed, others may be added. For example, the actual steps and/or order of steps taken in the disclosed processes may differ from those shown in the figure. Depending on the embodiment, certain of the steps described above may be removed, others may be added. For instance, the various components illustrated in the figures may be implemented as software and/or firmware on a processor, controller, ASIC, FPGA, and/or dedicated hardware. Furthermore, the features and attributes of the specific embodiments disclosed above may be combined in different ways to form additional embodiments, all of which fall within the scope of the present disclosure.

User interface screens illustrated and described herein can include additional and/or alternative components. These components can include menus, lists, buttons, text boxes, labels, radio buttons, scroll bars, sliders, checkboxes, combo boxes, status bars, dialog boxes, windows, and the like. User interface screens can include additional and/or alternative information. Components can be arranged, grouped, displayed in any suitable order.

Although the present disclosure includes certain embodiments, examples and applications, it will be understood by those skilled in the art that the present disclosure extends beyond the specifically disclosed embodiments to other alternative embodiments and/or uses and obvious modifications and equivalents thereof, including embodiments which do not provide all of the features and advantages set forth herein. Accordingly, the scope of the present disclosure is not intended to be limited by the specific disclosures of preferred embodiments herein, and may be defined by claims as presented herein or as presented in the future.