Movable negative pressure wound therapy device

Abstract

The present application generally relates to a mobile negative pressure wound therapy (NPWT) device comprising a negative pressure pump, wherein the NPWT device is adapted to ensure termination of the operation of the negative pressure pump if the NPWT device is operated outside a predetermined operating range. The present application also relates to a corresponding method for operating the NPWT device and a related computer program product.

Description

Technical Field

[0001] This application generally relates to a portable negative pressure wound therapy (NPWT) device including a negative pressure pump, wherein the NPWT device is adapted to ensure termination of operation of the negative pressure pump when the NPWT device is operated outside a predetermined operating range. This application also relates to a corresponding method for operating such an NPWT device and related computer program products. Background Technology

[0002] Negative pressure wound therapy (NPWT) is a technique that uses a negative pressure pump to apply sub-atmospheric pressure to wounds to promote healing, such as surgical wounds, acute wounds, and chronic wounds. NPWT also minimizes external disturbance to the wound and removes excess fluid from the wound site. Traditionally, NPWT has been primarily used by patients in hospital settings. However, recent product developments now allow patients to use this technology at home.

[0003] When using an NPWT device in a home environment, it may not be operated and monitored by a professional user, compared to its use in a hospital environment. Therefore, it is desirable to further simplify the operation and use of the NPWT device to minimize any errors in its use and handling.

[0004] An example of such an NPWT device is disclosed in US9737649, wherein the NPWT device may include one or more controllers responsible for various system functions associated with multiple response levels, such as interacting with a user (e.g., a patient, doctor, nurse, etc.), controlling the negative pressure pump, providing network connectivity, etc. In US9737649, the NPWT device is further configured to determine and monitor fluid flow in the system using one or more pressure sensors or probes that measure pressure in the fluid flow path and provide feedback to one of the controllers. The NPWT device is also configured to provide the user with indications, alarms, etc., reflecting the operating status, including, for example, visual, auditory, tactile, and other types of indications and / or alarms.

[0005] The solution proposed in US9737649 improves the operation of NPWT devices for “unskilled home users” by applying devices to ensure that NPWT devices are easy to operate and to effectively indicate to users whether NPWT devices are faulty.

[0006] While solution US9737649 can reduce operational failures of NPWT devices used in home settings, there is always a desire to further improve the safety of end users (i.e., patients using NPWT devices) and to minimize any risks involved in using NPWT devices.

[0007] In addition, WO2020043567 proposes an apparatus and method for providing negative pressure wound therapy to multiple wounds, particularly for determining whether there is a blockage in one or more fluid flow paths that connect a negative pressure source to one or more dressings.

[0008] In addition, EP2438935 discloses a negative pressure wound therapy device that may include a wound dressing, a fluid collection container, a vacuum pump including a pump motor, and a connecting pipe.

[0009] Additionally, WO2020011690 discloses a negative pressure wound therapy device, which may include a first negative pressure source and a first power source, the first negative pressure source being configured to supply negative pressure to a wound covered by a wound dressing via a fluid flow path, and the first power source being configured to provide power to the first negative pressure source. Summary of the Invention

[0010] In view of the above and other disadvantages of the prior art, the purpose of this application is to provide improvements related to the effective and safe operation of an NPWT device that operates to establish negative pressure within a sealed space formed by the wound covering relative to the wound site.

[0011] According to one aspect of this application, a portable negative pressure wound therapy (NPWT) device is thus provided, comprising: a housing; a negative pressure pump disposed within the housing; a canister coupled to the negative pressure pump and a wound dressing fluid, the wound dressing being configured to create a sealed space partially defined by a wound site; a battery disposed within the housing; and a control unit disposed within the housing, the control unit being electrically connected to the battery and adapted to supply power to the negative pressure pump for operating the negative pressure pump to establish negative pressure within the sealed space, wherein the NPWT device further includes control circuitry disposed externally to the control unit and adapted to terminate operation of the negative pressure pump when the NPWT device is determined to be operating outside a predetermined operating range.

[0012] This application is based on the understanding that further measures are needed to ensure the rapid termination of the operation of the NPWT device if it begins to operate outside of its normal behavior (defined in this application as a predetermined operating range). According to this application, the rapid termination of the NPWT device's operation is achieved by arranging the NPWT device to further include control circuitry located externally to the control unit. According to this application, the external control circuitry is arranged to be independent of the correct operation of the control unit (typically including some form of programmable circuitry), meaning that the external control circuitry (typically including at least one logic gate or controllable switch with a first input control line for controlling the controllable switch) can also terminate the operation of the NPWT device if, for example, the software / firmware running at the control unit fails to operate in a completely normal manner. Therefore, advantages of this application may include, for example, the possibility of providing an additional layer of security for the NPWT device to ensure that the user is not exposed to, for example, undesirable actions of the NPWT device in fault conditions. It should therefore be emphasized that the control circuitry located externally to the control unit is typically not integrated with the control unit, and is therefore a completely independent circuitry relative to the control unit.

[0013] Further advantages of this application include: allowing external control circuitry to directly receive input from, for example, sensors, and allowing sensors to directly influence whether to terminate the operation of the NPWT device, without prior processing by the control unit. Therefore, the setup defined in this application allows for a blend of advanced processing using the control unit and additional safety layers provided by external control circuitry in the event of, for example, a failure of the control unit.

[0014] An example of undesirable operation of an NPWT device is when a pressure threshold is reached and the negative pressure pump fails to stop. In a typical prior art implementation of an NPWT device, a pressure sensor is connected to a control unit and generates data, which the control unit uses to determine the value of the negative pressure generated by the negative pressure pump. The control unit then uses this pressure value to control when and how the negative pressure pump is activated, typically to ensure that the negative pressure is maintained within a predetermined negative pressure range, which forms part of the predetermined operating range of the NPWT device. One problem with this implementation is that if the control unit fails to process the data from the pressure sensor, or if the control unit "malfunctions," the negative pressure pump may remain activated even if the negative pressure exceeds the predetermined negative pressure range. This can potentially cause pain to the patient at the wound site, as the negative pressure at the wound site may be far below the appropriate negative pressure for the wound.

[0015] To eliminate this situation, in one embodiment, it is advantageous to alternatively arrange the pressure sensor directly connected to an external control circuit, and if the pressure sensor provides an indication that the negative pressure is outside a predetermined negative pressure range, adjust the logic of a controllable switch, for example, included in the external control circuit, to turn off the controllable switch.

[0016] To address the differences between different batches of pressure sensors, it is advantageous to include calibration circuitry in the pressure sensors and / or NPWT devices. This implementation allows, for example, the calibration of each individual pressure sensor during the production phase of the NPWT device. In some embodiments, the pressure sensor is a differential pressure sensor, thereby making the measurement data provided by the pressure sensor more reliable.

[0017] In some embodiments of this application, it is advantageous to further equip the NPWT device with a monitoring circuit connected to the control unit and arranged as an external component associated with the control unit. The monitoring circuit is typically configured to allow a means of recovering the control unit in the event of a control unit failure. The monitoring circuit typically includes a timer arranged to reset the control unit once the timer has counted down to zero (from its current value, which defines a preset time). However, as long as the control unit operates normally, it will continuously reset the monitoring circuit's timer (before the current time has elapsed), thus preventing the monitoring circuit from resetting the control unit.

[0018] However, according to this application, the monitoring circuit is not only arranged to be associated with the control unit, but also configured to reset the control unit. Conversely, according to this application, the monitoring circuit is also connected to a first controllable switch, so that the "timeout" of a timer included in the monitoring circuit will also cause the first controllable switch to switch. This implementation will advantageously further enhance the safety of the NPWT device because the preset time of the monitoring circuit can be set short enough (e.g., between 0.5 seconds and 2 seconds) to ensure that the operation of the negative pressure pump is terminated in the event of a possible failure of the control unit.

[0019] Therefore, in addition to waiting for the negative pressure to exceed the predetermined negative pressure range, the switching of the first controllable switch by the monitoring circuit in conjunction with the first controllable switch of the external control circuit will further limit the undesirable operation of the negative pressure pump in the event of NPWT device failure, thereby further reducing the risks involved in using the NPWT device according to this application.

[0020] In one embodiment of this application, the control circuit further includes a second controllable switch connected to the control unit and adapted to supply power to the negative pressure pump when it is to be operated. Therefore, the control unit can effectively control when the negative pressure pump is operated, wherein the second controllable switch of the external control circuit acts as a "buffer" between the control unit and the negative pressure pump, thereby reducing the risk that any interference generated by the negative pressure pump may affect the control unit.

[0021] Advantageously, the control unit is also adapted to use pulse width modulation (PWM) to control a second controllable switch, thereby seamlessly controlling the speed of the negative pressure pump according to the desired behavior / scheme.

[0022] In some embodiments of this application, the control unit is adapted to continuously measure the intermediate voltage level of the battery and select a PWM scheme based on the most recently measured battery voltage level. Typically, the battery voltage level will gradually decrease during operation of the NPWT device, and simply turning the second controllable switch on / off using a constant PWM switching scheme will cause the speed of the negative pressure pump to decrease as the voltage level decreases. Therefore, in order to maintain the operating speed of the negative pressure pump within a predetermined speed range (e.g., + / - 10% of the speed value), it is desirable to select the PWM scheme based on the most recently measured battery voltage level. This measure allows the speed of the negative pressure pump to remain substantially constant (e.g., within the exemplary + / - 10% mentioned above). Maintaining the speed of the negative pressure pump substantially constant will also result in a substantially constant sound level of the negative pressure pump, thereby reducing interference to patients using the NPWT device. In some embodiments, the “base speed” of the negative pressure pump is selected during manufacturing or by the patient, wherein the base speed is set to a level that minimizes the amount of interference experienced (or expected to be experienced) by the patient. In some embodiments, the selection of the base speed can be achieved through input provided by the patient using a user interface included in the NPWT device.

[0023] Furthermore, it is generally preferred that the can be detachably connected to the housing, which includes the negative pressure pump, so that, for example, a full can can be removed and replaced with an empty (new) can. In such embodiments, it may be desirable to provide, for example, some form of engagement device for the can and the housing to secure the can to the housing so that the can is not accidentally removed from the housing. In one embodiment, the engagement device may include a pair of flexible protrusions extending from the can and adapted to engage, for example, a corresponding locking groove provided on the housing.

[0024] In embodiments of this application, the NPWT device is suitable for home care. Therefore, given that the NPWT device is portable, it is suitable for user carrying, for example, via a pocket, belt, strap, or similar object. Furthermore, to simplify operation by the (end)user, the NPWT device may additionally include an indicator device for displaying indicators providing information about the device's operating status. In one embodiment, instead of a display element, the NPWT device includes a dedicated light source disposed on its front operating surface to provide the user with the aforementioned operating status information.

[0025] Advantageously, the NPWT device is a component of a wound treatment system, further comprising a wound covering. This will be further elaborated in the detailed description of this application below.

[0026] According to another aspect of this application, a method for operating a portable negative pressure wound therapy (NPWT) device is also provided, the NPWT device comprising: a housing; a negative pressure pump disposed within the housing; a canister coupled to the negative pressure pump and a wound dressing fluid configured to create a sealed space partially defined by a wound site; a battery disposed within the housing; and a control unit disposed within the housing, the control unit being electrically connected to the battery, wherein the method includes the steps of: operating the negative pressure pump by supplying power from the battery to the negative pressure pump to establish negative pressure within the sealed space; generating a first control signal if it is determined that the NPWT device is operating outside a predetermined operating range; and terminating the operation of the negative pressure pump using a control circuit also included in the NPWT device and disposed outside the control unit. This aspect of the application provides similar advantages to those discussed above with respect to the foregoing aspects of this application.

[0027] According to another aspect of this application, a computer program product comprising a non-transitory computer-readable medium storing a computer program method for operating a portable negative pressure wound therapy (NPWT) device, the NPWT device comprising: a housing; a negative pressure pump disposed within the housing; a canister coupled to the negative pressure pump and a wound dressing fluid configured to create a sealed space partially defined by a wound site; a battery disposed within the housing; and a control unit disposed within the housing, the control unit being electrically connected to the battery, wherein the computer program product includes: code for operating the negative pressure pump to establish negative pressure within the sealed space by supplying power from the battery to the negative pressure pump; code for generating a first control signal upon determining that the NPWT device is operating outside a predetermined operating range; and code for terminating operation of the negative pressure pump using control circuitry also included in the NPWT device and disposed externally to the control unit. Furthermore, this aspect of the application provides similar advantages to those discussed above with respect to the foregoing aspects of this application.

[0028] Further features and advantages of this application will become more apparent when examined in light of the appended claims and the description below. Those skilled in the art will recognize that different features of this application can be combined to create embodiments other than those described below, without departing from the scope of this application. Attached Figure Description

[0029] Various aspects of this application, including its specific features and advantages, will be readily understood from the detailed description and accompanying drawings below, wherein:

[0030] Figure 1 A wound treatment system including the NPWT device according to this application is conceptually illustrated;

[0031] Figure 2A and Figure 2B It shows Figure 1 Different views of possible implementations of the NPWT device are shown;

[0032] Figure 3 Detailed exemplary embodiments of the control circuitry included in the NPWT device according to this application are shown, and

[0033] Figure 4 This is a flowchart illustrating the steps of a method for operating this NPWT device and performing a method according to the present preferred embodiment of this application. Detailed Implementation

[0034] The present application will now be described more fully with reference to the accompanying drawings, which illustrate presently preferred embodiments of the application. However, the present application can be embodied in many different forms and should not be construed as limited to the embodiments described herein; rather, these embodiments are provided for clarity and completeness and to fully convey the scope of the application to those skilled in the art. The same reference numerals throughout refer to the same elements.

[0035] Now turn to the accompanying drawings, especially referring to... Figure 1 A wound treatment system 100 is conceptually illustrated, comprising an NPWT device 102 according to this application. The wound treatment system 100 also includes a wound cover 104 adapted to create a sealed space 106 partially defined by a wound surface 108 at or around, for example, the user's skin, a wound, or surrounding the user's skin. Additionally, the NPWT device 102 is fluidly connected to the wound cover 104 using, for example, a nozzle 110. The nozzle 110 can be any suitable flexible nozzle made of an elastomeric and / or polymeric material.

[0036] The NPWT device 102 further includes a negative pressure pump 112 adapted to establish negative pressure when the pump 112 is operational (i.e., in an activated state). The negative pressure pump 112 can be any type of biocompatible pump that maintains or aspirates a sufficient and therapeutic level of vacuum. Preferably, the negative pressure level to be achieved is in the range of about -20 mmHg to about -300 mmHg. In possible embodiments of this application, a negative pressure range of about -80 mmHg to about -140 mmHg is used. In possible embodiments of this application, the negative pressure pump 112 is a diaphragm pump or a peristaltic pump, etc., wherein a moving part aspirates the fluid from the wound dressing 104.

[0037] The negative pressure pump 112 is fluidly connected to the tank 114, which also forms part of the NPWT device 102. The tank 114 may be formed of, for example, molded plastic and may be a removable part of the NPWT device 102. As described above, preferably, the tank 114 is at least partially transparent / semi-transparent to allow observation of the interior of the tank 114, thereby helping the user determine the remaining capacity of the tank 114.

[0038] To facilitate understanding of the discussion herein, it should be understood that the interchangeable terms “negative pressure,” “subatmospheric pressure,” and “reduced pressure” generally refer to pressures less than the local ambient pressure, such as the ambient pressure in the external local environment provided by a sealed treatment environment created by a wound covering or dressing. In many cases, the local ambient pressure may also be the atmospheric pressure in which the patient is located. Unless otherwise stated, the pressure values ​​mentioned herein are gauge pressures. Similarly, an increase in negative pressure generally refers to a decrease in absolute pressure, while a decrease in negative pressure generally refers to an increase in absolute pressure.

[0039] An inlet port 116 is formed at the tank 114 to allow connection to the nozzle 110. The inlet port 116 may also be formed elsewhere on the NPWT device 102, but still fluidly connected to the tank 114. The connection between the inlet port 116 and the nozzle 110 is a sealed connection, thereby ensuring that no leakage occurs at the inlet port 116 during normal operation of the NPWT device 102. Preferably, the nozzle 110 is releasably connected to the inlet port 116 by conventional means including friction fit, bayonet connection, snap-fit, barbed connector, etc. The inlet port 116 may be molded / formed from the same material as the material forming the tank 114, and / or the inlet port may be molded / formed concurrently with the formation of the tank.

[0040] The NPWT device 102 also includes a battery 118 for supplying power to the NPWT device 102. Preferably, the battery 118 may be of a rechargeable type, but alternatively, it may be arranged as disposable so that it can be replaced once discharged. Particularly suitable battery packs may be used in conjunction with some embodiments of this application.

[0041] The NPWT device 102 also includes a control unit 120 electrically connected to the battery 118 and adapted to control the operation of the negative pressure pump 112. The control unit 120 may include a microprocessor, microcontroller, programmable digital signal processor, or other programmable device. The control unit 120 may also (or alternatively) 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 unit 120 includes a programmable device such as a microprocessor, microcontroller, or programmable digital signal processor as described above, the processor may also include computer-executable code for controlling the operation of the programmable device.

[0042] According to this application, the NPWT device 102 also includes a control circuit 122 disposed outside the control unit 120 and arranged to generally control the operation of the negative pressure pump 112, particularly to ensure that the operation of the negative pressure pump 112 can be quickly terminated when the NPWT device 102 begins to operate outside of what is considered normal behavior, as discussed above. The following is in conjunction with... Figure 3 The operation of control circuit 122 will be further explained.

[0043] In addition, the NPWT device 102 includes at least one pressure sensor 126 arranged in fluid connection with the negative pressure pump 112.

[0044] During use of the NPWT device 102, a wound dressing 104 is placed over the user's / patient's wound site, thereby forming a sealed space 106. A connecting pipe 110 is configured to fluidly connect the wound dressing 104 to the inlet port 116 of the NPWT device 102. The NPWT device 102 is then activated, for example, by the user / patient by pressing the start / pause button 208 (see reference). Figure 2A Therefore, the negative pressure pump 112 is activated. Upon activation, the negative pressure pump 112 begins to vent air through the tank 114, inlet port 116, connecting pipe 110, and the sealed space 106 formed by the wound dressing 104. Thus, negative pressure is generated within the sealed space 106. If fluid has formed at the wound site, this fluid from the wound can be at least partially "drawn" from the wound site, through the connecting pipe 110, inlet port 116, and into the tank 114. The amount of fluid (potentially defined as exudate) drawn from the wound and collected in the tank will depend on the type of wound being treated and the type of wound dressing used. For example, when using an absorbent dressing, the fluid can be absorbed and collected in both the tank and the wound dressing, while if a dressing with no or very low absorbency is used, most or all of the fluid from the wound site can be collected in the tank. A suitable filter element ( Figure 1 (Not shown) is positioned between tank 114 and negative pressure pump 112 to ensure that liquid cannot flow from tank 114 to negative pressure pump 112.

[0045] Now go to Figure 2A and Figure 2B This shows, as Figure 1 Different views of possible embodiments of the NPWT device according to this application are shown. As shown, most of the components included in the NPWT device 102 are arranged within a housing 202, wherein the housing 202 may be at least partially formed of plastic.

[0046] As described above, preferably, the can 114 is detachably connected to the housing 202. With this implementation, the user operating the NPWT device 102 can remove and, for example, discard the can 114 if it is full or if it needs to be replaced for other reasons (e.g., due to a problem with the can 114 or the inlet port 116).

[0047] like Figure 2AAs shown, housing 202 is provided with a start / pause button 208 for starting / pausing the operation of NPWT device 102. Start / pause button 208 is electrically connected to control unit 120. Additionally, housing 202 may optionally be provided with one or more display indicators 210, 212, 214 for providing feedback to the user of NPWT device 102. For example, display indicators 210, 212, 214 may indicate to the user: a possible leak at, for example, wound covering 104; the need to charge / replace battery 118; or a blockage in connector 110. Display indicators 210, 212, 214 may be formed by providing, for example, LEDs below the inner surface of housing 202, wherein suitable indicators may be formed (e.g., printed) at appropriate corresponding positions on the outer surface of housing 202. It should be understood that, alternatively, display indicators 210, 212, 214 may be displayed on a display screen integrated into housing 202.

[0048] Now refer to Figure 3 This diagram illustrates an exemplary detailed schematic of the control circuitry 122, including the NPWT device 102. As described above, the control circuitry 122 is external and independent of the control unit 120, but is arranged to communicate with the control unit 120. The control circuitry 122 is also arranged to communicate with the pressure sensor 126 and the negative pressure pump 112.

[0049] The control circuit 122 includes components capable of terminating the operation of the negative pressure pump 112 without the intervention of the control unit 120. Therefore, even if the control unit 120 fails to correctly identify a problem, such as a problem with the received sensor value (e.g., "too low" negative pressure), the control circuit 122 can operate independently of the control unit 120 and shut down the negative pressure pump 112.

[0050] In such Figure 3 In the non-limiting and exemplary illustrations shown, the control circuit 122 includes a first controllable switch SW1. When the first controllable switch SW1 is turned off, the negative pressure pump 112 will be shut down. The first controllable switch SW1 is then controlled by each of the pressure comparator 302 and the watchdog circuitry 304, both of which are included in the control circuit 122. Thus, if either the pressure comparator 302 or the watchdog circuitry 304 provides a control signal indicating that the operation of the negative pressure pump 112 will be terminated, the negative pressure pump 112 will be shut down by means of the first controllable switch SW1. Figure 3 In this context, the "OR function" is functionally implemented by the "Logic OR" circuit 306.

[0051] Pressure comparator 302 is then connected to pressure sensor 126, where data from the pressure sensor is compared to a predetermined negative pressure range. The predetermined negative pressure range may then be set, for example, during manufacturing, thereby allowing pressure sensor 126 to be properly calibrated during calibration (and possibly, individually). In some embodiments, implementing pressure sensor 126 as a differential pressure sensor may be suitable, resulting in higher comparison reliability in some embodiments compared to non-differential pressure sensors. Figure 3 As shown, the pressure comparator 302 is provided with an interface for receiving a predetermined negative pressure range. Such an interface can be configured, for example, according to a suitable communication protocol, in which the commonly known I2C protocol may be useful.

[0052] Therefore, when the pressure value determined by pressure sensor 126 falls outside the predetermined negative pressure range, pressure comparator 302 generates a control signal to control the first controllable switch SW1, thereby turning off the first controllable switch SW1 and terminating the operation of the negative pressure pump 112. It should be understood that the pressure value determined by pressure sensor 126 is also provided to control unit 120 for use in the normal operation of the NPWT device 102.

[0053] The monitoring circuit 304 is arranged to communicate with the control unit 120 and is typically included in the NPWT device 102 to enable the recovery of the control unit 120 in the event of a failure. However, according to this application, the monitoring circuit 304 also serves as a means for directly terminating the operation of the negative pressure pump 112. This is achieved by allowing a "reset signal" (in the event of no response from the control unit 120) to be transferred and provided to the first controllable switch SW1 (i.e., not just provided to the control unit 120 to reset it). Therefore, if the monitoring circuit 304 enters a reset state, the reset signal will reset the control unit 120 and simultaneously provide a control signal for operating the first controllable switch SW1.

[0054] Compared to the situation where the termination of the negative pressure pump 112 depends solely on the operation of the control unit 120, the application of the monitoring circuit 304 associated with the first controllable switch SW1 allows for a significant reduction in response time. In other words, the monitoring circuit 304 will directly provide a control signal to the first controllable switch SW1 to terminate the operation of the negative pressure pump 112, instead of having to wait for the control unit 120 to "restart".

[0055] In addition, the control circuit 122 includes a second controllable switch SW2. The second controllable switch SW2 is arranged to communicate with the control unit 120 and, in some embodiments, can be considered as a driver for the negative pressure pump 112. In some embodiments of this application, the control unit operates the negative pressure pump 112 based on pulse width modulation (PWM), meaning that the control unit 112 uses the second controllable switch SW2 to turn the negative pressure pump 112 on and off. The switching frequency is selected to be high enough to ensure that the rotational inertia of the motor (not shown) included in the negative pressure pump 112 continues to operate the negative pressure pump 112. However, by controlling the ratio of the on and off times of the second controllable switch SW2, the total suction force provided via the negative pressure pump 112 can be controlled.

[0056] In some embodiments, it may be desirable to select a PWM switching scheme that keeps the frequency completely constant over time. Therefore, in such embodiments, it is desirable to maintain a completely constant frequency while simultaneously adjusting the on / off ratio (compared to adjusting both the frequency and the on / off ratio). This implementation has proven desirable to the end user because it eliminates any noise generated by the operation of the negative pressure pump 112.

[0057] To achieve this functionality, in some embodiments it may be desirable to monitor the voltage level of battery 118 and select a PWM switching scheme based on the most recently measured voltage level. With this implementation, the speed of negative pressure pump 112 can be maintained even if the voltage level of battery 118 gradually decreases over time.

[0058] During the operation of NPWT device 102, further reference Figure 4 The control unit will select a suitable PWM scheme, for example, based on the recently measured voltage level of battery 118, and then generate a control signal that controls the second controllable switch SW2, thereby operating the negative pressure pump 112 (S1).

[0059] The control unit 120 continuously receives indications from the pressure sensor 126 related to the negative pressure generated by the negative pressure pump 112, and controls when and for how long the negative pressure pump 112 operates. However, according to this application, it is desirable to ensure the operation of the negative pressure pump 112 in the event of any possible problems with the NPWT device 102.

[0060] Therefore, according to this application, if it is determined that the NPWT device 102 is operating outside a first predetermined operating range, a control signal (S2) is generated. Operation outside the first predetermined operating range includes, for example, a situation where the negative pressure generated by the negative pressure pump 112 exceeds a predetermined negative pressure range. However, other situations include, for example, a situation where the control unit 120 of the NPWT device 102 is determined to have failed, for example, by a reset signal generated by the monitoring circuit 304 included in the control circuit 122. In this case as well, the control signal is generated.

[0061] The control signal is also used to terminate (S3) the operation of the negative pressure pump 112 using the control circuit 122, wherein the control circuit 122 is located outside the control unit 120.

[0062] The control functions of this application can be implemented using existing computer processors, or by a dedicated computer processor for a suitable system (for this or other purposes), or by a hardwired system. Embodiments within the scope of this application include a program product comprising a machine-readable medium for carrying or having machine-executable instructions or data structures stored thereon. This machine-readable medium can be any available medium accessible to a general-purpose or special-purpose computer or other machine with a processor. For example, the machine-readable medium may include RAM, ROM, EPROM, EEPROM, CD-ROM or other optical disc storage, disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of machine-executable instructions or data structures and is accessible to a general-purpose or special-purpose computer or other machine with a processor.

[0063] Although the accompanying drawings may show a sequence, the order of the steps may differ from what is depicted. Furthermore, two or more steps may be performed simultaneously or partially simultaneously. This variation will depend on the chosen software and hardware system and the designer's choices. All these variations are within the scope of this application. Similarly, software implementation can be accomplished using standard programming techniques with rule-based logic and other logic to perform various connection steps, processing steps, comparison steps, and determination steps. Moreover, although this application has been described with reference to specific exemplary embodiments, many different changes, modifications, etc., will become apparent to those skilled in the art.

[0064] Furthermore, through a study of the accompanying drawings, this application, and the appended claims, those skilled in the art can understand and implement variations of the disclosed embodiments when practicing this application. Additionally, in the claims, the word "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude a plural.

Claims

1. A portable negative pressure wound therapy device, comprising: case, A negative pressure pump is arranged inside the housing. A tank connected to the negative pressure pump and the wound covering fluid, the wound covering being used to create a sealed space partially defined by the wound site. The battery arranged inside the casing, A control unit disposed within the housing, electrically connected to the battery, and adapted to supply power to the negative pressure pump for operating the negative pressure pump to establish negative pressure within the sealed space, A pressure sensor, adapted to provide an indication of the negative pressure generated by the negative pressure pump. in, The negative pressure wound therapy device also includes a control circuit, which is located outside the control unit. The pressure sensor is connected to the control unit and the control circuit, and The control circuit includes a first controllable switch, which is arranged to cut off the power supply to the negative pressure pump in the event that the operation of the negative pressure pump is to be terminated because the negative pressure wound therapy device is determined to be operating outside a predetermined operating range.

2. The negative pressure wound therapy device according to claim 1, wherein, The first controllable switch includes a first input control line for controlling the controllable switch.

3. The negative pressure wound therapy device according to claim 2 further includes a monitoring circuit, the monitoring circuit being connected to the control unit and the first input control line of the first controllable switch, wherein, The monitoring timeout causes the controllable switch to switch.

4. The negative pressure wound therapy device according to claim 1, wherein, The control circuit includes a second controllable switch connected to the control unit and adapted to supply power to the negative pressure pump when the negative pressure pump is to be operated.

5. The negative pressure wound therapy device according to claim 4, wherein, The control unit is also adapted to use pulse width modulation to control the second controllable switch.

6. The negative pressure wound therapy device according to claim 5, wherein, The control unit is also adapted to select a pulse width modulation scheme based on the most recently measured voltage level of the battery.

7. The negative pressure wound therapy device according to claim 6, wherein, The pulse width modulation scheme is also selected to keep the operating speed of the negative pressure pump within a predetermined speed range.

8. A wound treatment system, comprising: The negative pressure wound therapy device according to any one of claims 1 to 7, and Wound covering.

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