Patent Description:
Embodiments of the present disclosure relate to methods and apparatuses for dressing and treating a wound with negative or reduced pressure therapy or topical negative pressure (TNP) therapy. In particular, but without limitation, embodiments disclosed herein relate to negative pressure therapy devices, methods for controlling the operation of TNP systems, and methods of using TNP systems. Relevant prior art can be found in <CIT>, <CIT>, <CIT>, <CIT>, and <CIT>.

An apparatus for applying negative pressure to a wound is disclosed. The apparatus includes a negative pressure source configured to provide negative pressure to a wound dressing via a fluid flow path; a switch including an actuator configured to toggle a state of a first pair of electrical contacts and a state of a second pair of electrical contacts in response to a user input; and control circuitry configured to: supply negative pressure with the negative pressure source in response to the first pair of electrical contacts being in an electrically connected state and the second pair of electrical contacts being in the electrically connected state, and disable supply of negative pressure with the negative pressure source in response to the first pair of electrical contacts being in an electrically disconnected state or the second pair of electrical contacts being in the electrically disconnected state. The control circuitry is further configured to disable supply of negative pressure with the negative pressure source in response to the first pair of electrical contacts being in the electrically connected state and the second pair of electrical contacts being in the electrically disconnected state. The switch is further configured to receive the user input as a depression of the switch.

The apparatus of the preceding paragraph can include one or more of the following features: The actuator is configured to simultaneously toggle the state of the first pair of electrical contacts and the state of the second pair of electrical contacts in response to the user input. The control circuitry is configured to supply negative pressure with the negative pressure source in response to no user inputs other than the user input to the switch. When the actuator is broken and no longer able to toggle the state of the first pair of electrical contacts or the state of the second pair of electrical contacts, the control circuitry is further configured to no longer supply negative pressure with the negative pressure source. The control circuitry is further configured to detect a switch fault in response to the state of the first pair of electrical contacts not toggling within a threshold period of time subsequent to toggling of the state of the second pair of electrical contacts. The threshold period of time is <NUM> seconds, <NUM> second, <NUM> seconds, <NUM> second, or <NUM> seconds. The control circuitry is further configured to output a switch fault indication in response to detection of the switch fault. The first pair of electrical contacts includes a plurality of first traces and the second pair of electrical contacts includes a plurality of second traces, and the actuator is configured to short the plurality of first traces to one another and short the plurality of second traces to one another in response to the user input. The negative pressure source is disposed on or within the wound dressing. The control circuitry is configured to disable supply of negative pressure with the negative pressure source by deactivation of operation of the negative pressure source, opening of a vent positioned in the fluid flow path, or closing of a valve positioned in the fluid flow path.

In some embodiments, a method for controlling application of negative pressure to a wound (not claimed) is disclosed. The method includes: using an actuator of a switch, toggling a state of a first pair of contacts and a state of a second pair of contacts in response to receipt of a user input to the switch; supplying negative pressure with a negative pressure source to a wound dressing via a fluid flow path in response to the state of the first pair of contacts being a first state and the state of the second pair of contacts being a second state; and disabling supply of negative pressure with the negative pressure source in response to the state of the first pair of contacts not being the first state or the state of the second pair of contacts not being the second state, wherein the state of the first pair of contacts is the first state and the state of the second pair of contacts is the second state at a first time, and the state of the first pair of contacts is not the first state and the state of the second pair of contacts is not the second state at a second time.

The method of the preceding paragraph can include one or more of the following features: The first and second states correspond to forming an electrical connection. At a third time, the state of the first pair of contacts is the first state and the state of the second pair of contacts is not the second state. The toggling includes simultaneously toggling the state of the first pair of contacts and the state of the second pair of contacts in response to receipt of the user input to the switch. The method further includes detecting a switch fault in response to the state of the first pair of contacts not toggling within a threshold period of time subsequent to toggling of the state of the second pair of contacts. The threshold period of time is between <NUM> seconds and <NUM> seconds. The method further includes outputting a switch fault indication for presentation to a user in response to the detecting. The disabling includes disabling supply of negative pressure with the negative pressure source by deactivation of operation of the negative pressure source, opening of a vent positioned in the fluid flow path, or closing of a valve positioned in the fluid flow path.

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

The present disclosure relates to methods and apparatuses for dressing and treating a wound with reduced pressure therapy or topical negative pressure (TNP) therapy. In particular, but without limitation, embodiments of this disclosure relate to negative pressure therapy apparatuses, methods for controlling the operation of TNP systems, and methods of using TNP systems. In certain embodiments, the features of this disclosure can advantageously increase the safety of a patient when using a TNP apparatus.

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

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

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

The user interfaces of some TNP apparatuses may have a limited elements through which a user can provide user input. In some instances, particular user interfaces may include just a single element usable by the user to stop and start operation of the TNP apparatus, such as the delivery of negative pressure, and the user may not be able to replace or interchange the functionality of the single element with that of another element. These particular user interfaces can desirably be easier to construct and operate than more complicated user interfaces having numerous elements. However, the particular user interfaces may present a problem if the single element experiences a fault (for example, a failure) and is no longer able to function as expected. The user of the particular user interfaces may, for example, undesirably be unable to pause or stop delivery of negative pressure if negative pressure is being provided by the TNP apparatus.

The situation of a user being unable to stop delivery of negative pressure can additionally introduce risks to the healing of a wound of a patient or to the patient's health. If the patient experiences discomfort from the wound dressing during delivery of negative pressure and the single element fails such that it is no longer able to function to receive user input, the patient may be forced to either continue application of negative pressure therapy despite the dangers or remove the wound dressing, cut or sever one of the tubes or lumens (which may not be possible when a source of negative pressure is integrated in a wound dressing), break the TNP apparatus (for example, by pulling out electronics if possible), remove the power source (if accessible), or the like to terminate delivery of negative pressure. These actions (for example, removal of the wound dressing) can damage the wound of the patient and hinder any healing trajectory that was already progressed, as well as expose the wound to external contaminants due to a loss of protection from the wound dressing.

To help prevent the situation of the user being unable to stop delivery of negative pressure when it is necessary to do so, a TNP apparatus with the single element usable by the user to stop and start delivery of negative pressure can include redundant activation or deactivation controls or mechanisms within the single element. In one example, the single element can be a switch that includes an actuator configured to toggle a state of a first pair of contacts and a state of a second pair of contacts. If the state of either or both of the first or second pair of contacts is toggled during delivery of negative pressure therapy, the TNP apparatus is caused to disable delivery of negative pressure therapy. Accordingly, in the event that the actuator may be broken and only able to toggle the state of one of the first and second pair of contacts, the actuator may nonetheless be usable to stop delivery of negative pressure with the TNP apparatus.

<FIG> illustrates a negative pressure therapy system <NUM> that includes a TNP apparatus <NUM> and a wound <NUM>. The TNP apparatus <NUM> can be used to treat the wound <NUM>. The TNP apparatus <NUM> can include control circuitry 12A, memory 12B, a negative pressure source 12C, a user interface 12D, a power source 12E, a first pressure sensor 12F, a second pressure sensor <NUM> (which may be optional), and a skin detector <NUM> that are configured to electrically communicate with one another. In addition, the TNP apparatus <NUM> can include a wound dressing <NUM>. The power source 12E can provide power to one or more components of the TNP apparatus <NUM>.

One or more of the control circuitry 12A, memory device 12B, negative pressure source 12C, user interface 12D, power source 12E, first pressure sensor 12F, second pressure sensor <NUM>, and skin detector <NUM> can be integral with, incorporated as part of, attached to, or disposed in the wound dressing <NUM>. The TNP apparatus <NUM> can accordingly be considered to have its control electronics and pump on-board the wound dressing <NUM> rather than separate from the wound dressing <NUM>.

The control circuitry 12A can include one or more controllers, activation circuits, boost converters, current limiters, feedback conditioning circuits, and H-bridge inverters. The one or more controllers can control the operations of one or more other components of the TNP apparatus <NUM> according at least to instructions stored in the memory device 12B. The one or more controllers can, for instance, control operations of the negative pressure source 12C via a signal input (for example, a pulse width modulation of the signal) to the one or more H-bridge inverters, which in turn drive power from the power source 12E to the negative pressure source 12C.

The negative pressure source 12C can include a pump, such as, without limitation, a rotary diaphragm pump or other diaphragm pump, a piezoelectric pump, a peristaltic pump, a piston pump, a rotary vane pump, a liquid ring pump, a scroll pump, a pump operated by a piezoelectric transducer, a voice coil pump, or any other suitable pump or micropump or any combinations of the foregoing.

The user interface 12D can include one or more elements that receive user inputs or provide user outputs to a patient or caregiver. The one or more elements that receive user inputs can include buttons, switches, dials, touch screens, or the like, and the one or more elements that provide user outputs can include activation of a light emitting diode (LED) or one or more pixels of the display or activation of a speaker or the like. In one example, the user interface 12D can include a switch to receive a first user input (for instance, a negative pressure activation or deactivation input) and two LEDs to indicate an operating status (for example, functioning normally, under fault condition, or awaiting user input) of the TNP apparatus <NUM>.

The first pressure sensor 12F can be used to monitor pressure underneath the wound dressing <NUM>, such as pressure in a fluid flow path connecting the negative pressure source 12C and the wound <NUM>, pressure at the wound <NUM>, or pressure in the negative pressure source 12C. The second pressure sensor <NUM> can be used to monitor pressure external to the wound dressing <NUM>. The pressure external to the wound dressing can be atmospheric pressure; however, the atmospheric pressure can vary depending on, for instance, an altitude of use or pressurized environment in which the TNP apparatus <NUM> may be used.

The control circuitry 12A can control the supply of negative pressure by the negative pressure source 12C according at least to a comparison between the pressure monitored by the first pressure sensor 12F and the pressure monitored by the second pressure sensor <NUM>. The control circuitry 12A can include a controller, such as a microcontroller or microprocessor.

The skin detector <NUM> can be used to determine if the wound dressing <NUM> has been placed over the wound <NUM>. The skin detector <NUM> can, for example, detect skin of a patient. The detection by the skin detector <NUM> can confirm whether the wound dressing <NUM> is coupled to skin of the patient next to the wound <NUM>. When skin is detected, this may indicate that activation of the TNP apparatus <NUM> is intentional rather than unintentional and can thus be used to prevent unintentional activation of the TNP apparatus <NUM> or an end-of-life timer of the TNP apparatus <NUM>, such as during transportation or manufacture of the TNP apparatus <NUM>. In one example, if the skin detector <NUM> indicates to the control circuitry 12A that skin is detected, the control circuitry 12A can activate the negative pressure source 12C to supply negative pressure in response to receiving an activation input via the user interface 12D. If the skin detector <NUM>, on the other hand, indicates to the control circuitry 12A that skin is not detected, the control circuitry 12A may not activate the negative pressure source 12C to supply negative pressure in response to receiving an activation input via the user interface 12D. The skin detector <NUM> can include one or more of a capacitive sensor, an impedance sensor, an optical sensor, a piezoresistive sensor, a piezoelectric sensor, an elastoresistive sensor, and an electrochemical sensor.

The wound dressing <NUM> can include a wound contact layer, a spacer layer, and an absorbent layer. The wound contact layer can be in contact with the wound <NUM>. The wound contact layer can include an adhesive on the patient facing side for securing the dressing to the skin surrounding the wound <NUM> or on the top side for securing the wound contact layer to a cover layer or other layer of the wound dressing <NUM>. In operation, the wound contact layer can provide unidirectional flow so as to facilitate removal of exudate from the wound while blocking or substantially preventing exudate from returning to the wound <NUM>. The spacer layer can assist in distributing negative pressure over the wound site and facilitating transport of wound exudate and fluids into the wound dressing <NUM>. Further, the absorbent layer can absorb and retain exudate aspirated from the wound <NUM>.

The control circuitry 12A can, in some instances, prevent supply of negative pressure with the negative pressure source 12C. For example, the control circuitry 12A can prevent supply of negative pressure by deactivating operation of the negative pressure source, opening a vent positioned in the fluid flow path, and closing a valve positioned in the fluid flow path.

The supply of negative pressure with the negative pressure source 12C can, in some instances, be disabled. For example, supply of negative pressure can be disabled by deactivating operation of the negative pressure source 12C or the control circuitry 12A, opening a vent positioned in the fluid flow path, and closing a valve positioned in the fluid flow path. In some implementations, deactivating operation of the negative pressure source 12C or the control circuitry 12A can be performed by disconnection of power to the negative pressure source 12C or the control circuitry 12A or withdrawal of an enable signal provided to the negative pressure source 12C or the control circuitry 12A.

The control circuitry 12A can monitor a duty cycle of the negative pressure source 12C. As is used herein, the "duty cycle" can reflect the amount of time the negative pressure source 12C is active or running over a period of time. In other words, the duty cycle can reflect time that the negative pressure source 12C is in an active state as a fraction of total time under consideration. Duty cycle measurements can reflect a level of activity of the negative pressure source 12C. For example, the duty cycle can indicate that the negative pressure source 12C is operating normally, working hard, working extremely hard, etc. Moreover, the duty cycle measurements, such as periodic duty cycle measurements, can reflect various operating conditions, such as presence or severity of leaks, rate of flow of fluid (for instance, air, liquid, or solid exudate, etc.) aspirated from a wound, or the like. Based on the duty cycle measurements, such as by comparing the measured duty cycle with a set of thresholds (for instance, determined in calibration), the controller can execute or be programmed to execute algorithms or logic that control the operation of the system. For example, duty cycle measurements can indicate presence of a high leak, and the control circuitry 12A can be programmed to indicate this condition to a user (for instance, patient, caregiver, or physician) or temporarily suspend or pause operation of the source of negative pressure in order to conserve power.

When the TNP apparatus <NUM> may be used to treat the wound <NUM>, the wound dressing <NUM> can create a substantially sealed or closed space around the wound <NUM> and under the wound dressing <NUM>, and the first pressure sensor 12F can periodically or continuously measure or monitor a level of pressure in this space. The control circuitry 12A can control the level of pressure in the space between a first negative pressure set point limit and at least a second negative pressure set point limit. In some instances, the first set point limit can be approximately -<NUM> mmHg, or from approximately -<NUM> mmHg or less to approximately -<NUM> mmHg or more. In some instances, the second set point limit can be approximately -<NUM> mmHg, or from approximately -<NUM> mmHg or less to approximately -<NUM> mmHg or more.

<FIG> illustrates a side view of a negative pressure therapy system <NUM>, and <FIG> illustrates a top view of the negative pressure therapy system <NUM>. The negative pressure therapy system <NUM> can be an example implementation of the negative pressure therapy system <NUM>.

In the negative pressure therapy system <NUM>, the wound dressing <NUM> of the TNP apparatus <NUM> is shown as attached to the wound <NUM>. Arrows depict the flow of air through the wound dressing <NUM> and wound exudate from the wound <NUM>. The TNP apparatus <NUM> can include an air exhaust <NUM> and a component area <NUM>, such as a components housing or storage area for components of the TNP apparatus <NUM> like one or more of the control circuitry 12A, memory device 12B, negative pressure source 12C, user interface 12D, power source 12E, first pressure sensor 12F, second pressure sensor <NUM>, and skin detector <NUM>.

The user interface 12D of the negative pressure therapy system <NUM> can include a switch <NUM>, a first indicator <NUM> (such as a first LED), and a second indicator <NUM> (such as a second LED). The switch <NUM> is configured to receive a negative pressure activation or deactivation user input in response to depression of the switch <NUM>. The first indicator <NUM> and the second indicator <NUM> can indicate an operating status like functioning normally, under fault condition, or awaiting user input. In some implementations, the switch <NUM> can couple to a power supply connection of the negative pressure source 12C or the control circuitry 12A (such as a controller of the control circuitry 12A) or an enable signal of the negative pressure source 12C or the control circuitry 12A to activate or deactivate supply of negative pressure or disable supply of negative pressure. Moreover, the control circuitry 12A can monitor the user interface 12D, such as the switch <NUM>, the first indicator <NUM>, or the second indicator <NUM>, to detect issues like a fault and, responsive to the fault detection, output a fault indication via the user interface 12D or activate or deactivate supply of negative pressure or disable supply of negative pressure. In certain embodiments, the control circuitry 12A may supply negative pressure with the negative pressure source 12C in response to no user inputs other a user input to the switch <NUM>.

Component parts of the wound dressing <NUM> of the negative pressure therapy system <NUM> are illustrated to include an airlock layer <NUM>, an absorbing layer <NUM>, and a contact layer <NUM>. The airlock layer <NUM> can enable air flow. The absorbing layer <NUM> can absorb wound exudate. The contact layer <NUM> can be soft and include silicon and be used to couple the TNP apparatus <NUM> to the patient.

<FIG> illustrates a circuit schematic <NUM> for a switch like the switch <NUM>, according to some embodiments. The switch can be a double pole, single throw switch and include an actuator that toggles states of multiple sets of contacts (for example, two, three, four, or more sets of contacts) in response to a user input as a depression of the switch. The actuator can simultaneously or in a staggered manner toggle the states of the multiple sets of contacts. As illustrated in <FIG>, the multiple sets of contacts include a first pair of contacts including contacts <NUM> and <NUM> (collectively with a first contact pad forming a first switch, which can be referred to as SW1) and a second pair of contacts including contacts <NUM> and <NUM> (collectively with a first contact pad forming a second switch, which can be referred to as SW2). SW1 and SW2 can act as redundant switches. Although the schematic <NUM> illustrates two pairs of contacts, any of the switches described herein can include more than two pairs of contacts.

The contacts <NUM> and <NUM> are shown as open, and the contacts <NUM> and <NUM> are shown as open. The contacts <NUM> and <NUM> may be open because a contact pad of SW1 is not electrically connecting or shorting the contacts <NUM> and <NUM> together. When the contacts <NUM> and <NUM> are open, SW1 may also be considered to be open. Similarly, the contacts <NUM> and <NUM> may be open because a contact pad of SW2 is not electrically connecting or shorting the contacts <NUM> and <NUM> together. When the contacts <NUM> and <NUM> are open, SW2 may also be considered to be open.

The contacts <NUM> and <NUM> may be closed when the contact pad of SW1 electrically connects or shorts the contacts <NUM> and <NUM> together. When the contacts <NUM> and <NUM> are closed, SW1 may also be considered to be closed. The contacts <NUM> and <NUM> may be closed when the contact pad of SW2 electrically connects or shorts the contacts <NUM> and <NUM> together. When the contacts <NUM> and <NUM> are closed, SW2 may also be considered to be closed.

The switch can further include an input A and an output B. For example, the input A can be electrically coupled to either power (for example, the power source 12E) or ground of the TNP apparatus <NUM>, and the output B can be electrically coupled to control operations of the TNP apparatus (or vice versa). When the switch is closed, an electrical connection to power or ground is formed thereby enabling the TNP apparatus <NUM> to operate or function to provide therapy. For instance, when the switch is closed, a signal may be provided or generated to the control circuitry 12A to activate the negative pressure source 12C or enable supply of power by the power source 12E to other components of the TNP apparatus <NUM>.

In some implementations, when the switch is functioning properly, the states of the multiple sets of contacts may toggle only in response to the user input to switch. If switch is broken, however, and the actuator is no longer able to toggle one or more of the multiple sets of contacts, the switch may no longer toggle states of all of the multiple sets of contacts in response to the user input. Accordingly, if the actuator is no longer able to toggle one or more of the multiple sets of contacts, the control circuitry 12A may no longer be configured to supply negative pressure with the negative pressure source 12C.

<FIG> is a logical truth table <NUM> for the circuit schematic <NUM>. As can be understood from the logical truth table <NUM>, the electrical path from the input A to the output B can be considered to be formed or "on" if both SW1 and SW2 are closed, and the electrical path from the input A to the output B can be considered to be not formed or "off" if at least one of SW1 or SW2 is open.

In other implementations, a switch can be designed differently from the circuit schematic <NUM> and be made to function according to an alternative logical truth table different from the logical truth table <NUM>. The alternative logical truth table can include multiple possible configurations and each configuration cause the electrical path from the input A to the output B to be either on or off. One or more of the multiple possible configurations of the alternative logical truth table can cause the electrical path from the input A to the output B to be on, and the one or more other of the multiple configurations of the alternative logical truth table can cause the electrical path from the input A to the output B being off. In certain embodiments, a total number of the multiple configurations which cause the electrical path from the input A to the output B to be on can be less than a total number of the multiple configurations which cause the electrical path from the input A to the output B to be off. This may advantageously result in a bias toward causing the electrical path from the input A to the output B to be off unless the switch is properly functioning. As a result, the switch may intelligently cause the negative pressure source 12C to operate when the switch is properly functioning but not when the switch is not properly functioning.

<FIG> illustrate an implementation of the circuit schematic <NUM>, according to some embodiments. Contacts <NUM>, <NUM>, <NUM>, <NUM> can respectively be implementations of the contacts <NUM>, <NUM>, <NUM>, <NUM>. The SW1 contact pad <NUM> can be an implementation of the contact pad of SW1 of <FIG>, and the SW2 contact pad <NUM> can be an implementation of the contact pad of SW2 of <FIG>.

As illustrated, at least some of the contacts <NUM>, <NUM>, <NUM>, <NUM> can each include a primary trace and multiple secondary traces extending from the primary trace. The multiple secondary traces can each extend perpendicular to the primary trace from which it extends. The primary traces can be curved as shown with respect to the contacts <NUM> and <NUM> or straight as shown with respect to the contacts <NUM> and <NUM>. The primary and secondary traces of the contacts <NUM>, <NUM>, <NUM>, <NUM> can be printed, for example, on a circuit board.

In <FIG>, the contacts <NUM> and <NUM> are shown as open, and the contacts <NUM> and <NUM> are shown as open. In <FIG>, the contacts <NUM> and <NUM> are shown as closed due to contact of the SW1 contact pad <NUM> with the contacts <NUM> and <NUM>, and the contacts <NUM> and <NUM> are shown as closed due to contact of the SW2 contact pad <NUM> with the contacts <NUM> and <NUM>. An electrical path is formed from the input A to the output B, for example, through the contact <NUM>, contact pad <NUM>, contact <NUM>, contact <NUM>, contact pad <NUM>, and contact <NUM>. The SW1 contact pad <NUM> and the SW2 contact pad <NUM> can be conductive plates. Contact pads <NUM> and <NUM> may be brought into contact with the contacts <NUM>, <NUM>, <NUM>, <NUM> by an actuator (or actuators), which can be mechanically, pneumatically, electrically, or the like actuated by a user input as a depression of the switch.

<FIG> illustrate another implementation of the circuit schematic <NUM>, according to some embodiments. Contacts <NUM>, <NUM>, <NUM>, <NUM> can respectively be implementations of the contacts <NUM>, <NUM>, <NUM>, <NUM>. The SW1 contact pad <NUM> can be an implementation of the contact pad of SW1 of <FIG>, and the SW2 contact pad <NUM> can be an implementation of the contact pad of SW2 of <FIG>.

As illustrated, at least some of the contacts <NUM>, <NUM>, <NUM>, <NUM> can each include a primary trace and multiple secondary traces extending from the primary trace. The multiple secondary traces can each extend perpendicular to the primary trace from which it extends. The primary traces can be straight as shown. The primary and secondary traces of the contacts <NUM>, <NUM>, <NUM>, <NUM> can be printed, for example, on a circuit board.

As illustrated, at least some of the contacts <NUM>, <NUM>, <NUM>, <NUM> can each include a perimeter trace that extends around a conductive area. The perimeter trace and the contact area of the contacts <NUM>, <NUM>, <NUM>, <NUM> can be printed, for example, on a circuit board.

<FIG> illustrates a therapy control process <NUM> usable to control delivery of negative pressure therapy by an apparatus, such as the TNP apparatus <NUM>. For convenience, the therapy control process <NUM> is described in the context of the TNP apparatus <NUM>, but may instead be implemented in other systems described herein or by other systems not shown. The therapy control process <NUM> can be performed, in some instances, by the control circuitry 12A alone or in combination with the user interface 12D of the TNP apparatus <NUM>.

At block <NUM>, the therapy control process <NUM> can receive a user input. The user input as a depression of the switch <NUM> can be received, for instance, via the user interface 12D.

At block <NUM>, the therapy control process <NUM> can attempt to toggle states of multiple sets of contacts (for example, close the contacts) in response to the user input. The switch <NUM> can, for example, include an actuator (or actuators) that can attempt to toggle the states of multiple pairs of contacts like the contacts <NUM> and <NUM> and the contacts <NUM> and <NUM>. If the switch <NUM> is functioning properly, the switch <NUM> can toggle the states of the multiple pairs of contacts. For example, the state of the multiple pairs of contacts can each be toggled simultaneously (or substantially so) or one after another so that each of the multiple pairs of contacts is closed. If the switch <NUM> is not functioning properly, the switch <NUM> may not toggle the state of one or more of the multiple pairs of contacts.

At block <NUM>, if the states of the multiple sets of contacts were not toggled, the therapy control process <NUM> can end. On the other hand, if the states of the multiple sets of contacts were toggled, the therapy control process <NUM> can move to block <NUM> to supply negative pressure. The supply of negative pressure can be initiated by the control circuitry 12A and performed by the negative pressure source 12C, and the negative pressure can be supplied to the wound dressing <NUM> via the fluid flow path.

At block <NUM>, if the states of the multiple sets of contacts remain unchanged, the therapy control process <NUM> can move again to block <NUM> and the supply of negative pressure can continue. On the other hand, at block <NUM>, if the state of at least one of the multiple sets of contacts is changed (for example, opened), the therapy control process <NUM> can move to block <NUM>. For example, a user input as a depression of the switch <NUM> can be received via the user interface 12D, and may cause the state of one or more of the multiple pairs of contacts to toggle. If the switch <NUM> is functioning properly, the switch <NUM> can toggle the states of the multiple pairs of contacts. For example, the state of the multiple pairs of contacts can each be toggled simultaneously (or substantially so) or one after another so that each of the multiple pairs of contacts is opened. If the switch <NUM> is not functioning properly, the switch <NUM> may not toggle the state of one or more of the multiple pairs of contacts.

At block <NUM>, the therapy control process <NUM> can disable supply of negative pressure. The supply of negative pressure can, for instance, be disabled by deactivation of operation of the negative pressure source 12C or the control circuitry 12A, opening of a vent positioned in the fluid flow path, and closing of a valve positioned in the fluid flow path. Because the toggling of fewer than all of the multiple sets of contacts at block <NUM> (for example, opening) may result in the therapy control process <NUM> moving from block <NUM> to block <NUM>, the therapy control process <NUM> can advantageously, in certain embodiments, favor disabling or be biased to disable the supply of negative pressure in response to some indication to disable supply of negative pressure despite not receiving an expected indication to disable supply of negative pressure that may involve toggling of all of the multiple sets of contacts. After block <NUM>, the therapy control process <NUM> can end. In some embodiments, block <NUM> can be performed periodically or in response to a change in the state of one or more contacts (such as, as a result of an interrupt being generated when the state of one or more contacts is toggled). In certain implementations, block <NUM> can be performed while negative pressure is being supplied.

<FIG> illustrates a switch fault detection process <NUM> usable to detect a switch fault in an apparatus configured to delivery negative pressure wound therapy, such as the TNP apparatus <NUM>. For convenience, the switch fault detection process <NUM> is described in the context of the TNP apparatus <NUM>, but may instead be implemented in other systems described herein or by other systems not shown. The switch fault detection process <NUM> can be performed, for example, by the control circuitry 12A alone or in combination with the user interface 12D. The process <NUM> can be used to detect a fault in the user interface 12D. The switch fault detection process <NUM> may begin, in some instances, with the negative pressure source 12C turned off and not providing negative pressure.

At block <NUM>, the switch fault detection process <NUM> can detect a toggle in a state of one of a set of contacts. For example, the control circuitry 12A can detect a toggle in the state of one of the pair of contacts of the switch <NUM>, such as the contacts <NUM> and <NUM> shown in <FIG>. The toggle can be detected, for instance, from a change in an electrical characteristic (such as voltage or current), mechanical characteristic, pressure characteristic, or thermal characteristic of the one of the pair of contacts of the switch <NUM> and may be detected using a sensor.

At block <NUM>, the switch fault detection process <NUM> can determine whether a state of another set of contacts is toggled. For example, the control circuitry 12A can detect, in response to a user input to the switch <NUM>, a toggle in the state of another of the pair of contacts of the switch <NUM>, such as the contacts <NUM> and <NUM> shown in <FIG>. The toggle can be detected, for instance, from a change in an electrical characteristic (such as voltage or current), mechanical characteristic, pressure characteristic, or thermal characteristic of the other of the pair of contacts of the switch <NUM> and may be detected using a sensor.

If the state of the another set of contacts is toggled, the switch fault detection process <NUM> can move to block <NUM> and supply negative pressure. The supply of negative pressure can be initiated by the control circuitry 12A and performed by the negative pressure source 12C, and the negative pressure can be supplied to the wound dressing <NUM> via the fluid flow path.

If the state of the another set of contacts is not toggled, the switch fault detection process <NUM> can move to block <NUM> and output a switch fault indication. The failure of the another set of contacts to toggle can be indicative of the another set of contacts failing to toggle as would be expected from a user input. For example, the control circuitry 12A detect a switch fault from the another set of contacts not toggling and thus output the switch fault indication, such as for presentation on the user interface 12D. The switch fault detection process <NUM> at block <NUM> may moreover monitor for the toggle of the another set of contacts for a time period, such as <NUM> seconds, <NUM> second, <NUM> seconds, <NUM> second, <NUM> seconds, or longer, before moving to block <NUM> and outputting the switch fault indication.

Although the processes in <FIG> and <FIG> describe toggling one or more contacts to enable or disable supply of negative pressure, toggling one or more contacts can be used for controlling other functions of the TNP apparatus <NUM>, such as for example initial activation of the TNP apparatus <NUM>.

Although one of more examples in this disclosure describe that a negative pressure source, control circuitry, or other components can be part of an integrated unit, such as on-board a wound dressing, the one or more examples do not limit the scope of the disclosure to such an integrated unit. The features related to redundant activation or deactivation control can, for instance, be included as part of a TNP apparatus that is not integral or separate from a wound dressing or with any medical or electronic device.

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

User interface screens illustrated and described herein can include additional 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 or alternative information. Components can be arranged, grouped, displayed in any suitable order.

Claim 1:
An apparatus for applying negative pressure to a wound, the apparatus comprising:
a negative pressure source configured to provide negative pressure to a wound dressing via a fluid flow path;
a switch comprising an actuator configured to toggle a state of a first pair of electrical contacts and a state of a second pair of electrical contacts in response to a user input, the switch being configured to receive the user input as a depression of the switch; and
control circuitry configured to:
supply negative pressure with the negative pressure source in response to the first pair of electrical contacts being in an electrically connected state and the second pair of electrical contacts being in the electrically connected state,
disable supply of negative pressure with the negative pressure source in response to the first pair of electrical contacts being in an electrically disconnected state or the second pair of electrical contacts being in the electrically disconnected state, and
wherein the control circuitry is configured to disable supply of negative pressure with the negative pressure source in response to the first pair of electrical contacts being in the electrically connected state and the second pair of electrical contacts being in the electrically disconnected state.