Patent ID: 12257379

DETAILED DESCRIPTION

The present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which currently preferred embodiments of the present disclosure are shown. The present disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness, and fully convey the scope of the present disclosure to the skilled person. Like reference characters refer to like elements throughout.

Turning now to the drawings and toFIG.1in particular, there is conceptually illustrated a wound treatment system100, comprising a NPWT device102in accordance with the present disclosure. The wound treatment system100further comprises a wound cover104, the wound cover104being adapted to create a sealed space106defined in part by a wound surface108, such as at the skin of a user/person, at or around a wound of the user/person. Additionally, the NPWT device102is fluidly connected to the wound cover104using e.g. a tubing110. The tubing110may be of any suitable flexible tubing fabricated from elastomeric and/or polymeric materials.

The NPWT device102in turn comprises a negative pressure pump112adapted for establishing a negative pressure when the negative pressure pump112is operable, i.e. in an active state. The negative pressure pump112may be any type of pump that is biocompatible and maintains or draws adequate and therapeutic vacuum levels. Preferably, the negative pressure level to be achieved is in a range between about −20 mmHg and about −300 mmHg. In a possible embodiment of the present disclosure, a negative pressure range between about −80 mmHg and about −140 mmHg is used. In a possible embodiment of the present disclosure, the negative pressure pump112is either a diaphragm pump or a peristaltic pump, or the like, in which the moving parts draw the mentioned fluid from the wound cover104.

The negative pressure pump112is fluidly connected to a canister114, the canister114also forming part of the NPWT device102. The canister114may be formed from e.g. molded plastic or the like, and possibly being a detachable component of the NPWT device102. As mentioned above, the canister114is preferably at least partly transparent/translucent to permit viewing into the interior of the canister114to assist the user in determining the remaining capacity of the canister114.

For ease of understanding of the following discussion of the present disclosure, it should be understood that the expressions “negative pressure”, “sub-atmospheric pressure”, “reduced pressure”, as used interchangeably herein, generally refer to a pressure less than a local ambient pressure, such as the ambient pressure in a local environment external to a sealed therapeutic environment provided by a wound cover or dressing. In many cases, the local ambient pressure may also be the atmospheric pressure at which a patient is located. Unless otherwise indicated, values of pressure stated herein are gauge pressures. Similarly, references to increases in negative pressure typically refer to a decrease in absolute pressure, while decreases in negative pressure typically refer to an increase in absolute pressure.

An inlet port116is formed at the canister114, for allowing connection to the tubing110. The inlet port116may also be formed elsewhere at the NPWT device102, however still fluidly connected to the canister114. The connection between the inlet port116and the tubing110is a sealed connection, thus ensuring that no leakage is formed at the inlet port116during normal operation of the NPWT device102. The tubing110is preferably releasably connected to the inlet port116through conventional means including a friction fit, bayonet coupling, snap fit, barbed connector, or the like. The inlet port116may be molded/formed from the same material and/or at the same time as forming the canister114.

The NPWT device102further comprises a battery118for powering the NPWT device102. The battery118may preferably be of the rechargeable type but may alternatively be arranged to be disposable and thus to be changed once discharged. A specifically adapted battery pack may be used in relation to some embodiment of the present disclosure.

The NPWT device102also comprises a control unit120, electrically connected to the battery118and adapted to control an operation of the negative pressure pump112. The control unit120may include a microprocessor, microcontroller, programmable digital signal processor or another programmable device. The control unit120may also, or instead, each include an application specific integrated circuit, a programmable gate array or programmable array logic, a programmable logic device, or a digital signal processor. Where the control unit120includes a programmable device such as the microprocessor, microcontroller or programmable digital signal processor mentioned above, the processor may further include computer executable code that controls operation of the programmable device.

In line with the present disclosure, the NPWT device102further comprises a control circuitry122provided externally from the control unit120and arranged to generally control the operation of the negative pressure pump112, specifically for ensuring that the operation of the negative pressure pump112may be swiftly terminated in case the NPWT device102starts to operate outside of what is considered to be a normal behavior, as has been discussed above. The operation of the control circuitry122is further elaborated below in relation toFIG.3.

In addition, the NPWT device102comprises at least one pressure sensor126arranged in fluid connection with the negative pressure pump112.

During use of the NPWT device102, the wound cover104is arranged at a wound site of the user/patient, forming the sealed space106. The tubing110is provided to fluidly connect the wound cover104to the inlet port116of the NPWT device102. The NPWT device102is then activated, e.g. by the user/patient, by pressing the start/pause button208(seeFIG.2A). The negative pressure pump112is thereby activated. When activated, the negative pressure pump112will start to evacuate air through the canister114, the inlet port116, the tubing110and the sealed space106formed by the wound cover104. Accordingly, the negative pressure will be created within the sealed space106. In case a liquid has been formed at the wound site, this liquid from the wound site may at least partly be “drawn” from the wound site, through the tubing110, the inlet port116and into the canister114. The amount of liquid (possibly defined as exudate) that is drawn from the wound and collected in the canister will depend on the type of wound that is being treated as well as the type of wound dressing used. For example, in case an absorbent dressing is used, the liquid may be absorbed and collected both in the canister and the wound dressing, whereas if a dressing with no or little absorption capacity is used most or all of the liquid from the wound site may be collected in the canister. A suitable filter member (not shown inFIG.1) is arranged between the canister114and the negative pressure pump112to ensure that no fluid is allowed to pass to the negative pressure pump112from the canister114.

Turning now toFIGS.2A and2Billustrating different views of a possible implementation of the NPWT device according to the present disclosure, as shown inFIG.1. As presented, a majority of the components comprised with the NPWT device102are arranged within a housing202, where the housing202may be formed at least partly from plastic.

As presented above, the canister114is preferably allowed to be detachably connected to the housing202. By means of such an implementation it may be possible for the user operating the NPWT device102to remove and e.g. discard the canister114in case the canister114is full or otherwise need to be exchanged (e.g. due to a problem with the canister114or the inlet port116, etc.).

As shown inFIG.2A, the housing202is provided with a start/pause button208for initiating/pausing operation of the NPWT device102. The start/pause button208is electrically connected to the control unit120. In addition, the housing202may optionally be provided with one or a plurality of display symbols210,212,214for providing feedback to the user of the NPWT device102. For example, the display symbols210,212,214may provide an indication to the user that there is a possible leakage at e.g. the wound cover104, that there is a need to charge/change the battery118, or that there is a blockage in the tubing110. The display symbols210,212,214may possible be formed by providing e.g. LEDs below an inner surface of the housing202, where suitable symbols may be formed, e.g. printed, at an outer surface of the housing202at suitable corresponding positions. It should be understood that the display symbols210,212,214alternatively may be shown on a display screen integrated with the housing202.

Turning now toFIG.3, presenting an exemplary detailed schematic of the control circuitry122comprised with the NPWT device102. As discussed above, the control circuitry122is provided externally and separately from the control unit120, however arranged in communication with the control unit120. The control circuitry122is further arranged in communication with the pressure sensor126and the negative pressure pump112

The control circuitry122comprises components allowing the operation of the negative pressure pump112to be terminated without any involvement of the control unit120. Thus, even in a situation where the control unit120fails to correctly identify e.g. a problem with sensor values received (such as a “too low” negative pressure), the control circuitry122can act independently of the control unit120and turn off the negative pressure pump112.

In the non-limiting and exemplary illustration as shown inFIG.3, the control circuitry122is shown to comprise a first controllable switch SW1. When the first controllable switch SW1is deactivated the negative pressure pump112will be turned off. The first controllable switch SW1is in turn controlled by each one of a pressure comparator302and a watchdog circuitry304, both comprised with the control circuitry122. Accordingly, the negative pressure pump112will be turned off by means of the first controllable switch SW1if either of the pressure comparator302or the watchdog304provides a control signal indicating that the operation of the negative pressure pump112is to be terminated. InFIG.3the “either functionality” is functionally illustrated by a logic OR circuitry306.

The pressure comparator302is in turn connected to the pressure sensor126, where data from the pressure sensor is compared to a predetermined negative pressure range. The predetermined negative pressure range may in turn be set e.g. a time of manufacturing, allowing the pressure sensor126to be correctly and possibly individually calibrated in a calibration process. It may in some embodiments be suitable to allow the pressure sensor126to be implemented as a differential pressure sensor, in some embodiments allowing for an in comparison higher reliability as compared to non-differential pressure sensor. As is shown inFIG.3, the pressure comparator302is provided with an interface for receiving the predetermined negative pressure range. Such an interface may for example be configured in line with suitable communication protocols, where the so called I2C protocol may be useful.

Accordingly, in case the pressure value as determined by the pressure sensor126fall outside of the predetermined negative pressure range, the pressure comparator302generates a control signal for controlling the first controllable switch SW1, whereby the first controllable switch SW1is turned off and the operation of the negative pressure pump112is terminated. It should be understood that the pressure value as determined by the pressure sensor126is also provided to the control unit120, for use in the general operation of the NPWT device102.

The watchdog circuitry304is arranged in communication with the control unit120and is generally comprised with the NPWT device102for allowing path of recovery of the control unit120in case of a malfunction of the control unit120. However, in line with the present disclosure the watchdog circuitry304will also function as a means for direct terminating the operation of the negative pressure pump112. This is achieved by allowing a “reset signal” (in case of a non-responsive control unit120) to be siphoned off and provided to the first controllable switch SW1, i.e. not just for provided to the control unit120for resetting the control unit120. Accordingly, if the watchdog circuitry304enters into a reset state, the reset signal will reset the control unit120and at the same time provide a control signal for operating the first controllable switch SW1.

The implementation of the watchdog circuitry304in relation to the first controllable switch SW1allows for a greatly reduced reaction time as compared to a situation where the termination of the negative pressure pump112is only dependent on the operation of the control unit120. That is, rather than having to wait for the control unit120to “reboot”, the watchdog circuitry304will directly provide its control signal to the first controllable switch SW1to terminate the operation of the negative pressure pump112.

In addition to the above, the control circuitry122further comprises a second controllable switch SW2. The second controllable switch SW2is arranged in communication with the control unit120and may in some embodiments be seen as functioning as driver for the negative pressure pump112. In some implementations of the present disclosure, the control unit operates the negative pressure pump112based on pulse width modulation (PWM), meaning that the control unit112switches the negative pressure pump112on and off, using the second controllable switch SW2. The frequency of the switching is selected to be high enough to ensure that the moment of inertia of an electrical motor (not shown) comprised with the negative pressure pump112continues to operate the negative pressure pump112. However, by controlling the ratio between the time the second controllable switch SW2on and off, the overall suction provided by means of the negative pressure pump112may be controlled.

In some embodiments it may be desirable to select a PWM switching scheme that keeps the frequency fairly constant over time. In such an embodiment it is thus desirable to keep the frequency fairly constant while at the same time adjusting the on/off ratio (as compared to adjust both of the switching frequency and the on/off ratio). Such an implementation has shown desirable for the end user, since this keeps any sound stemming from the operation of the negative pressure pump112.

To achieve such a functionality, it may in some embodiments be desirable to monitor a voltage level of the battery118and select the PWM switching scheme according to a recently measured voltage level. By means of such an implementation, it may be possible to keep the speed of the negative pressure pump112even though the voltage level of the battery118will gradually decline over time.

During operation of the NPWT device102, with further reference toFIG.4, the control unit will select a suitable PWM scheme, for example based on recently measured voltage level of the battery118, and subsequently generate a control signal that in turn controls the second controllable switch SW2, thereby operating, S1, the negative pressure pump112.

The control unit120will continuously receive an indication from the pressure sensor126relating to the negative pressure formed by the negative pressure pump112, and control when and for how long time the negative pressure pump112is to operate. However, in line with the present disclosure it is desirable to ensure that the operation of the negative pressure pump112in case of any possible problem with the NPWT device102.

Accordingly, in line with the present disclosure a control signal is formed, S2, if the NPWT device102is determined to operate outside a first predefined operational range. Operation outside of first predefined operational range for example includes a situation where the negative pressure formed by the negative pressure pump112comes outside a predetermined negative pressure range. However, other situations include for example where the control unit120of the NPWT device102is determined to fail, such as by a reset signal generated by the watchdog circuitry304comprised with the control circuitry122. Also in this situation such a control signal is formed.

The control signal is in turned used for terminating, S3, the operation of the negative pressure pump112using the control circuitry122, where the control circuitry122is provided externally from the control unit120.

The control functionality of the present disclosure may be implemented using existing computer processors, or by a special purpose computer processor for an appropriate system, incorporated for this or another purpose, or by a hardwire system. Embodiments within the scope of the present disclosure include program products comprising machine-readable medium for carrying or having machine-executable instructions or data structures stored thereon. Such machine-readable media can be any available media that can be accessed by a general purpose or special purpose computer or other machine with a processor. By way of example, such machine-readable media can comprise RAM, ROM, EPROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code in the form of machine-executable instructions or data structures and which can be accessed by a general purpose or special purpose computer or other machine with a processor.

Although the figures may show a sequence, the order of the steps may differ from what is depicted. Also, two or more steps may be performed concurrently or with partial concurrence. Such variation will depend on the software and hardware systems chosen and on designer choice. All such variations are within the scope of the disclosure. Likewise, software implementations could be accomplished with standard programming techniques with rule-based logic and other logic to accomplish the various connection steps, processing steps, comparison steps and decision steps. Additionally, even though the present disclosure has been described with reference to specific exemplifying embodiments thereof, many different alterations, modifications and the like will become apparent for those skilled in the art.

In addition, variations to the disclosed embodiments can be understood and effected by the skilled addressee in practicing the present disclosure, from a study of the drawings, the disclosure, and the appended claims. Furthermore, in the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality.