Patent Description:
Breathing assistance apparatuses are used in various environments such as hospital, medical facility, residential care, or home environments to deliver a flow of gas to users or patients. A breathing assistance apparatus, or a flow therapy apparatus, may include a humidification apparatus to deliver heated and humidified gases. The apparatus may optionally include a valve used to deliver oxygen with the flow of gas. A flow therapy apparatus may allow adjustment and control over characteristics of the gas flow, including flow rate, temperature, gas concentration, humidity, pressure, etc. Sensors, such as heated temperature sensing elements and/or thermistors, are used to measure these properties of the gases.

<CIT> discloses a breathing apparatus with a user interface comprising a display for displaying at least one menu item, a first button operable to sequentially cycle through and display a plurality of menu items, a second and optionally third button operable to configure a parameter of the selected menu item, and a fourth button operable to confirm the change of a parameter of the selected menu item, wherein the parameter is a respiratory parameter and/or other breathing apparatus parameter.

<CIT> discloses systems and method for conducting respiratory therapy in a respiratory system can adjust a flow of respiratory gases to a patient based upon a detected patient breath cycle. The respiratory system can include a non-sealed patient interface. The respiratory system can be configured to deliver a high flow therapy. A patient breath cycle may be determined using one or more measured parameters, such as a flow rate, a blower motor speed, and/or a system pressure. A flow source may be adjusted to have a phase matching that of the patient's breath cycle, such that flow in increased in response to the patient inhaling, and decreased in response to the patient exhaling.

According to the present invention there is provided a respiratory system according to claim <NUM>.

The flow of respiratory gases in a flow therapy apparatus can be adjusted based upon a detected breath cycle of the patient. The flow of gases can be adjusted such that the flow delivered during expiration is lower than the flow delivered during inspiration. The adjustment may improve patient comfort. The system can synchronize the flow rate with the detected breath cycle of the patient. The amplitude of the flow rate variation can be based partially on a value selected by the user. The flow rate can be adjusted by controlling the motor speed using a positive feedback system. The adjustments to the flow rate can be limited by the controller preventing the flow rate from crossing a minimum and/or maximum threshold, which can be varied. The adjustment can be made to the motor speed, that is, the positive feedback, which can cause the adjustment to the flow rate.

When the patient is exhaling, the threshold(s) or limit(s) can ensure that the apparatus is maintaining at least a minimum flow rate to the patient at all times while also providing expiratory flow relief. Maintaining the threshold can ensure that the flow rate does not fall outside a clinically relevant or effective value and/or a safety limit for a respiratory therapy, particularly for a high flow therapy. A user of the apparatus, such as a clinician and/or the patient, can also adjust the value of variation in the flow rate. The user-adjustment can allow the user to select a value of flow relief that the patient finds most comfortable.

In a configuration, a respiratory system for delivering a respiratory therapy to a patient, the system configured to adjust a flow rate of gases delivered to the patient according to patient inspiration and expiration, can comprise a flow generator configured to generate the flow rate of gases; a controller in electrical communication with one or more sensors and configured to: determine a cycle of the patient inspiration and expiration based on information received from the one or more sensors; and adjust the flow rate of gases based in part on the cycle of the patient inspiration and expiration, wherein the adjusting can be attenuated by a parameter determined based in part on a maximum and/or minimum flow rate measured by the one or more sensors during the cycle of the patient inspiration and expiration.

In a configuration, the flow generator can comprise a motor.

In a configuration, the flow rate can be adjusted by outputting a motor control signal.

In a configuration, the motor can comprise a brushless DC motor.

In a configuration, the cycle of the patient inspiration and expiration can be determined based on a first input and a second inputs received by the controller, the first and second inputs relating to a gases flow characteristic or performance of a component of the system.

In a configuration, the first input can correspond to the flow rate from the one or more sensors.

In a configuration, the second input can correspond to a pressure of a gases flow from the one or more sensors. In a configuration, the second input can correspond to a speed of the motor.

In a configuration, the speed of the motor can be determined based at least in part upon one or more motor parameters.

In a configuration, the maximum and/or minimum flow rate measured by the one or more sensors can be an unbounded response to the patient inspiration and expiration.

In a configuration, the adjusting can be further attenuated by comparing the maximum and/or minimum flow rate measured by the one or more sensors with a maximum and/or minimum threshold.

In a configuration, the maximum and/or minimum flow rate measured by the one or more sensors can be gradually bounded by a negative feedback term.

In a configuration, the parameter can comprise the negative feedback term that can be gradually increased in response to the measured maximum and/or minimum flow rates until the measured maximum and/or minimum flow rate no longer exceeds the maximum and/or minimum threshold.

In a configuration, the maximum and/or minimum threshold can be set by a user.

In a configuration, the system can comprises a user interface configured to receive a user input to adjust the maximum and/or minimum threshold.

In a configuration, the maximum and/or minimum threshold can be a clinically relevant limit of the respiratory therapy.

In a configuration, the minimum threshold can be between <NUM>-<NUM> lpm. In a configuration, the minimum threshold can be between <NUM> lpm. In a configuration, the minimum threshold can be between <NUM>-<NUM> lpm. In a configuration, the minimum threshold can be between <NUM>-<NUM> lpm. In a configuration, the minimum threshold can be between <NUM>-<NUM> lpm. In a configuration, the minimum threshold can be between <NUM>-<NUM> lpm. In a configuration, the minimum threshold can be between <NUM>-<NUM> lpm. In a configuration, the minimum threshold can be between <NUM>-<NUM> lpm. In a configuration, the minimum threshold can be between <NUM>-<NUM> lpm. In a configuration, the minimum threshold can be between <NUM>-<NUM> lpm. In a configuration, the minimum threshold can be between <NUM>-<NUM> lpm. In a configuration, the minimum threshold can be between <NUM>-<NUM> lpm.

In a configuration, the maximum threshold can be between <NUM>-<NUM> lpm. In a configuration, the maximum threshold can be between <NUM>-<NUM> lpm. In a configuration, the maximum threshold can be between <NUM>-<NUM> lpm. In a configuration, the maximum threshold can be between <NUM>-<NUM> lpm. In a configuration, the maximum threshold can be between <NUM>-<NUM> lpm. In a configuration, the maximum threshold can be between <NUM>-<NUM> lpm. In a configuration, the maximum threshold can be between <NUM>-<NUM> lpm. In a configuration, the maximum threshold can be between <NUM>-<NUM> lpm. In a configuration, the maximum threshold can be between <NUM>-<NUM> lpm. In a configuration, the maximum threshold can be between <NUM>-<NUM> lpm. In a configuration, the maximum threshold can be between <NUM>-<NUM> lpm. In a configuration, the maximum threshold can be between <NUM>-<NUM> lpm. In a configuration, the maximum threshold can be between <NUM>-<NUM> lpm. In a configuration, the maximum threshold can be between <NUM>-<NUM> lpm. In a configuration, the maximum threshold can be between <NUM>-<NUM> lpm. In a configuration, the maximum threshold can be between <NUM>-<NUM> lpm.

In a configuration, the maximum and/or minimum threshold can be a safety limit of the respiratory therapy.

In a configuration, the maximum and/or minimum threshold can depend on a selected flow rate.

In a configuration, the maximum and/or minimum threshold can be a predetermined percentage or value above and below the selected flow rate.

In a configuration, the maximum and/or minimum threshold can depend on a selected flow rate and a selected breath synchronization setting.

In a configuration, the system can comprise a user interface configured to receive a user input to adjust the breath synchronization setting.

In a configuration, the breath synchronization setting can comprise a range of numbers. In a configuration, the breath synchronization setting can comprise a plurality of categories including at least low and high settings.

In a configuration, the maximum and/or minimum threshold can be a predetermined percentage or value above and below the selected flow rate, the percentage or value varying based on the selected breath synchronization setting.

In a configuration, the adjusting can be performed iteratively.

In a configuration, the adjusting can comprise an increase in the flow rate when the patient is inspiring.

In a configuration, the adjusting can comprise a decrease in the flow rate when the patient is expiring.

In a configuration, the one or more sensors can comprise an ultrasonic transducer assembly.

In a configuration, the one or more sensors can comprise a heated temperature sensing element.

In a configuration, the system can be a high flow respiratory system.

In a configuration, the system can comprise a non-sealed patient interface.

In a configuration, the non-sealed patient interface can comprise a non-sealed nasal cannula.

In a configuration, a respiratory system for delivering a respiratory therapy to a patient, the system configured to adjust a flow rate of gases delivered to the patient according to patient inspiration and expiration, can comprise a flow generator configured to generate the flow rate of gases; and a controller in electrical communication with one or more sensors and configured to: determine a cycle of the patient inspiration and expiration based on information received from the one or more sensors; and adjust the flow rate based in part on the cycle of the patient inspiration and expiration, wherein the adjusting can be attenuated by comparing a maximum and/or minimum flow rate measured by the one or more sensors with a maximum and/or minimum threshold.

In a configuration, the second input can correspond a pressure of a gases flow from the one or more sensors. In a configuration, the second input can correspond to a speed of the motor.

In a configuration, each adjusting can be bound by a parameter determined based in part on a maximum and/or minimum flow rate measured by the one or more sensors.

In a configuration, a method of adjusting a flow rate of gases delivered to a patient according to patient inspiration and expiration using a respiratory system comprising a flow generator configured to generate the flow rate of gases can comprise using a controller of the respiratory system: determining a cycle of inspiration and expiration of the patient based on information received from one or more sensors of the respiratory system; and adjusting the flow rate based in part on the cycle of inspiration and expiration, wherein the adjusting can be attenuated by a parameter determined based in part on a maximum and/or minimum flow rate measured by the one or more sensors during the cycle of inspiration and expiration.

In a configuration, the determining can be based on a first input and a second inputs received by the controller, the first and second inputs relating to a gases flow characteristic or performance of a component of the system.

In a configuration, the method can further comprise determining the speed of the motor based at least in part upon one or more motor parameters.

In a configuration, a method of adjusting a flow rate of gases delivered to a patient according to patient inspiration and expiration using a respiratory system comprising a flow generator configured to generate the flow rate of gases can comprise using a controller of the respiratory system: determining a cycle of the patient inspiration and expiration based on information received from the one or more sensors; and adjusting the flow rate based at least in part on the cycle of the patient inspiration and expiration, wherein the adjusting can be attenuated by comparing a maximum and/or minimum flow rate measured by one or more sensors with a maximum and/or minimum threshold.

In a configuration, a respiratory system for delivering a respiratory therapy to a patient, the system configured to adjust a flow rate of gases delivered to the patient according to patient inspiration and expiration, can comprise a flow generator with a motor for generating a gases flow; and a controller in electrical communication with one or more sensors and configured to: cause to be displayed, on a user interface of the respiratory system, an expiratory relief level setting; receive a first user input to increase and/or decrease an expiratory relief level; cause to be displayed, on the user interface, a maximum and/or minimum flow rate threshold setting; receive a second user input to increase and/or decrease the maximum and/or minimum flow rate threshold; and adjust the flow rate based on the first user input and the second user input, wherein the first user input can be configured to allow adjusting of the flow rate based in part on a cycle of the patient inspiration and expiration and the second user input can be configured to attenuate the adjusting based on the first user input by comparing a maximum and/or minimum flow rate measured by the one or more sensors with the maximum and/or minimum threshold.

In a configuration, the first user input can be configured to allow adjusting of the flow rate based in part on a cycle of the patient inspiration and expiration by turning on and/or off the expiratory relief, and/or adjusting a magnitude of the expiratory relief.

In a configuration, the expiratory relief level setting can comprise a plurality of different expiratory relief levels.

In a configuration, the plurality of different expiratory relief levels can comprise a plurality of categories including at least low and high expiratory relief levels. In a configuration, the plurality of different expiratory relief levels can comprise a range of numbers. In a configuration, the plurality of different expiratory relief levels can comprise a sliding scale.

In a configuration, the first user input can be received via button(s) on the user interface.

In a configuration, the expiratory relief level setting can be accessible by the patient.

In a configuration, the maximum and/or minimum flow rate threshold setting may not be accessible by the patient.

In a configuration, the maximum and/or minimum flow rate threshold setting can be accessible by a clinician or technician.

In a configuration, the expiratory relief levels can affect a negative feedback to adjusting of the flow rate as applied in any of the configurations disclosed herein.

In a configuration, a respiratory system for delivering a respiratory therapy to a patient, the system configured to adjust a flow rate of gases delivered to the patient according to patient inspiration and expiration, can comprise a flow generator with a motor for generating a gases flow; and a controller in electrical communication with one or more sensors and configured to: cause to be displayed, on a user interface of the respiratory system, an expiratory relief level setting, the setting comprising a plurality of different expiratory relief levels; receive a user input via the user interface to increase and/or decrease an expiratory relief level; and adjust the flow rate based on the user input, wherein the user input can be configured to allow adjusting of the flow rate based in part on a cycle of the patient inspiration and expiration.

In a configuration, the user input can be configured to allow adjusting of the flow rate based in part on a cycle of the patient inspiration and expiration by turning on and/or off the expiratory relief, and/or adjusting a magnitude of the expiratory relief.

In a configuration, the controller can be further configured to attenuate the adjusting based on the user input by comparing a maximum and/or minimum flow rate measured by the one or more sensors with a maximum and/or minimum flow rate threshold.

In a configuration, a respiratory system for delivering a respiratory therapy to a patient, the system configured to adjust a flow rate of gases delivered to the patient according to patient inspiration and expiration, can comprise a flow generator with a motor for generating a gases flow; and a controller in electrical communication with one or more sensors and configured to: cause to be displayed, on the user interface, a maximum and/or minimum flow rate threshold setting; receive a user input to increase and/or decrease the maximum and/or minimum flow rate threshold; and adjust the flow rate based on the user input, wherein the user input can be configured to attenuate adjusting of the flow rate based on a cycle of the patient inspiration and expiration by comparing a maximum and/or minimum flow rate measured by the one or more sensors with the maximum and/or minimum threshold.

In a configuration, the user input can be received via button(s) on the user interface.

In a configuration, the maximum and/or minimum flow rate threshold can affect a negative feedback term to adjusting of the flow rate as applied in any of the configurations disclosed herein.

In a configuration, the controller can be configured to adjust the flow rate based on the cycle of the patient inspiration and expiration by receiving an expiratory relief level set by a user.

In a configuration, the controller can be configured to cause to be displayed, on the user interface, a plurality of different expiratory relief levels.

These and other features, aspects, and advantages of the present disclosure are described with reference to the drawings of certain embodiments, which are intended to schematically illustrate certain embodiments and not to limit the disclosure.

Although certain examples are described below, those of skill in the art will appreciate that the disclosure extends beyond the specifically disclosed examples and/or uses and obvious modifications and equivalents thereof. Thus, it is intended that the scope of the disclosure herein disclosed should not be limited by any particular examples described below.

A schematic representation of a high flow respiratory system <NUM> is provided in <FIG>. The respiratory system <NUM> can include a main device housing <NUM>. The main device housing <NUM> can contain a flow generator <NUM> that can be in the form of a motor/impeller arrangement (such as a blower), an optional humidifier or humidification chamber <NUM>, a controller <NUM>, and a user interface <NUM>. The user interface <NUM> can include a display and input device(s) such as button(s), a touch screen, a combination of a touch screen and button(s), or the like. The controller <NUM> can include one or more hardware and/or software processors and can be configured or programmed to control the components of the apparatus, including but not limited to operating the flow generator <NUM> to create a flow of gas for delivery to a patient, operating the humidifier <NUM> (if present) to humidify and/or heat the gas flow, receiving user input from the user interface <NUM> for reconfiguration and/or user-defined operation of the respiratory system <NUM>, and outputting information (for example on the display) to the user. The user can be a patient, healthcare professional, or anyone using the system <NUM>.

With continued reference to <FIG>, a patient breathing conduit <NUM> can be coupled to a gases flow outlet <NUM> in the main device housing <NUM> of the respiratory system <NUM>, and be coupled to a patient interface <NUM>. The patient interface can be a non-sealing interface like a nasal cannula with a manifold <NUM> and nasal prongs <NUM> for providing a high flow therapy. The patient breathing conduit <NUM> can also be coupled to a sealing interface like a face mask, a nasal mask, or a nasal pillow mask. The patient interface can also optionally include an endotracheal tube, a tracheostomy interface, or others.

The flow of gas can be generated by the flow generator <NUM>, and may be humidified, before being delivered to the patient via the patient conduit <NUM> through the patient interface <NUM>. The controller <NUM> can control the flow generator <NUM> to generate a gas flow of a desired flow rate, and/or one or more valves to control mixing of air and oxygen or other breathable gas. The controller <NUM> can control a heating element in the humidification chamber <NUM>, if present, to heat the gases to a desired temperature that achieves a desired level of temperature and/or humidity for delivery to the patient. The patient conduit <NUM> can have a heating element 16a, such as a heater wire, to heat gases flow passing through to the patient. The heating element 16a can also be under the control of the controller <NUM>.

The system <NUM> can use flow rate sensor(s), pressure sensor(s), temperature sensor(s), humidity sensor(s), or other sensors, in communication with the controller <NUM>, to monitor characteristics of the gas flow and/or operate the system <NUM> in a manner that provides suitable therapy. Ultrasonic transducers and heated temperature sensing elements are examples of sensors that can be used to measure flow rate, among other parameters. The gas flow characteristics can include gases concentration, flow rate, pressure, temperature, humidity, or others. The sensors 3a, 3b, 3c, <NUM>, <NUM>, such as pressure, temperature, humidity, and/or flow rate sensors, can be placed in various locations in the main device housing <NUM>, the patient conduit <NUM>, and/or the patient interface <NUM>. The controller <NUM> can receive output from the sensors to assist it in operating the respiratory system <NUM> in a manner that provides suitable therapy, such as to determine a suitable target temperature, flow rate, and/or pressure of the gases flow. Providing suitable therapy can include meeting a patient's inspiratory demand.

The system <NUM> can include a wireless data transmitter and/or receiver, or a transceiver <NUM> to enable the controller <NUM> to receive data signals <NUM> in a wireless manner from the operation sensors and/or to control the various components of the system <NUM>. Additionally, or alternatively, the data transmitter and/or receiver <NUM> can deliver data to a remote server or enable remote control of the system <NUM>. The system <NUM> can also include a wired connection, for example, using cables or wires, to enable the controller <NUM> to receive data signals <NUM> from the operation sensors and/or to control the various components of the system <NUM>.

As used herein, "high flow" therapy refers to administration of gas to the airways of a patient at a relatively high flow rate that generally meets or exceeds the peak inspiratory demand of the patient. The flow rates used to achieve "high flow" may be any of the flow rates listed below. For example, in some configurations, for an adult patient 'high flow therapy' may refer to the delivery of gas(es) to a patient at a flow rate of greater than or equal to about <NUM> litres per minute (<NUM> LPM), such as between about <NUM> LPM and about <NUM> LPM, or between about <NUM> LPM and about <NUM> LPM, or between about <NUM> LPM and about <NUM> LPM, or between about <NUM> LPM and about <NUM> LPM, or between about <NUM> LPM and about <NUM> LPM, or between about <NUM> LPM and about <NUM> LPM, or between about <NUM> LPM and about <NUM> LPM, or between about <NUM> LPM and about <NUM> LPM, or between about <NUM> LPM and about <NUM> LPM. In some configurations, for a neonatal, infant, or child patient 'high flow therapy' may refer to the delivery of gas(es) to a patient at a flow rate of greater than <NUM> LPM, such as between about <NUM> LPM and about <NUM> LPM, or between about <NUM> LPM and about <NUM> LPM, or between about <NUM> LPM and about <NUM> LPM, or between about <NUM> LPM and about <NUM> LPM, or between about <NUM> LPM and about <NUM> LPM, or between about <NUM> LPM and about <NUM> LPM, or between about <NUM> LPM and about <NUM> LPM, or between about <NUM> LPM and <NUM> LPM, or between about <NUM> LPM and <NUM> LPM. A high flow therapy apparatus with an adult patient, a neonatal, infant, or child patient, may deliver gas(es) to the patient at a flow rate of between about <NUM> LPM and about <NUM> LPM, or at a flow rate in any of the sub-ranges outlined above.

<FIG> and <FIG> show an example flow therapy apparatus or respiratory device of the respiratory system <NUM>. The device can include a housing <NUM>, which encloses a flow generator. The flow generator may include a motor/sensor module. The motor/sensor module may be non-removable from the main housing <NUM>. The motor/sensor module can also optionally be removable from the main housing <NUM>. The housing <NUM> can include a humidifier or humidification chamber bay <NUM> for receipt of a removable humidification chamber <NUM>. The removable humidification chamber <NUM> contains a suitable liquid such as water for heating and humidifying gases delivered to a patient. The humidification chamber <NUM> can be fluidly coupled to the device housing <NUM> in a linear slide-on motion into the chamber bay <NUM>. A gas outlet port <NUM> can establish a fluid communication between the motor/sensor module and an inlet <NUM> of the chamber <NUM>.

Heated and humidified gas can exit an outlet <NUM> of the chamber <NUM> into a humidified gas return <NUM>, which can include a removable L-shaped elbow. The removable elbow can further include a patient outlet port <NUM> for coupling to the inspiratory conduit, such as the inspiratory conduit <NUM> of <FIG> to deliver gases to the patient interface <NUM>. The gas outlet port <NUM>, humidified gas return <NUM>, and patient outlet port <NUM> each can have seals such as O-ring seals or T-seals to provide a sealed gases passageway between the device housing <NUM>, the humidification chamber <NUM>, and the inspiratory conduit. A floor portion of the humidification chamber bay <NUM> in the housing <NUM> can include a heater arrangement such as a heater plate or other suitable heating element(s) for heating the water in the humidification chamber <NUM> for use during a humidification process.

As shown in <FIG>, the device can include an arrangement to enable the flow generator to deliver air, oxygen (or alternative auxiliary gas), or a suitable mixture thereof to the humidification chamber <NUM> and thereby to the patient. This arrangement can include an air inlet <NUM>' in a rear wall <NUM> of the housing <NUM>. The device can include a separate oxygen (or other breathable gases) inlet port <NUM>'. In the illustrated configuration, the oxygen inlet port <NUM>' can be positioned adjacent one side of the housing <NUM> at a rear end thereof. The oxygen port <NUM>' can be connected to an oxygen source such as a tank. The oxygen inlet port <NUM>' can be in fluid communication with a valve. The valve can suitably be a solenoid valve that enables the control of the amount of oxygen that is added to the gas flow that is delivered to the humidification chamber <NUM>.

The housing <NUM> can include suitable electronics boards, such as sensing circuit boards. The electronics boards can contain, or can be in electrical communication with, suitable electrical or electronics components, such as but not limited to microprocessors, capacitors, resistors, diodes, operational amplifiers, comparators, and switches. One or more sensors can be used with the electronic boards. Components of the electronics boards (such as but not limited to one or more microprocessors) can act as the controller <NUM> of the apparatus. One or both of the electronics boards can be in electrical communication with the electrical components of the system <NUM>, including but not limited to the display unit and user interface <NUM>, motor, valve, and the heater plate to operate the motor to provide the desired flow rate of gases, humidify and heat the gases flow to an appropriate level, and supply appropriate quantities of oxygen (or quantities of an alternative auxiliary gas) to the gases flow.

As mentioned above, operation sensors, such as flow, temperature, humidity, and/or pressure sensors can be placed in various locations in the respiratory device, the patient conduit <NUM>, and/or cannula <NUM>. The electronics boards can be in electrical communication with those sensors. Output from the sensors can be received by the controller <NUM>, to assist the controller <NUM> to operate the respiratory system <NUM> in a manner that provides optimal therapy, including generally meeting inspiratory demand. One or more sensors (for example, Hall-effect sensors) may be used to measure a motor speed of the motor of the flow generator. The motor may include a brushless DC motor, from which motor speed can be measured without the use of separate sensors. For example, during operation of a brushless DC motor, back-EMF can be measured from the non-energized windings of the motor, from which a motor position can be determined, which can in turn be used to calculate a motor speed. In addition, a motor driver may be used to measure motor current, which can be used with the measured motor speed to calculate a motor torque. The motor may also include a low inertia motor.

Room air can enter the flow generator through the inlet port, such as the air inlet port <NUM>' in <FIG>. The flow generator can operate at a motor speed of greater than <NUM>,<NUM> RPM and less than <NUM>,<NUM> RPM, greater than <NUM>,<NUM> RPM and less than <NUM>,<NUM> RPM, or between any of the foregoing values. Operation of the flow generator can mix the gases entering the flow generator, such as the motor/sensor chamber through the inlet port. Using the flow generator as the mixer can reduce the pressure drop that would otherwise occur in a system with a separate mixer, such as a static mixer comprising baffles, because mixing requires energy.

<FIG> and <FIG> illustrate a block diagram <NUM> of an example control system <NUM> that can detect patient conditions and control operation of the flow therapy apparatus including the gas source. The control system <NUM> can manage a flow rate of the gas flowing through the flow therapy apparatus as it is delivered to a patient. For example, the control system <NUM> can increase or decrease the flow rate by controlling an output of motor speed of the flow generator or blower <NUM> or an output of a valve <NUM> (such as in an auxiliary gas port). The control system <NUM> can automatically determine a set value or a personalized value of the flow rate for a particular patient as discussed below. The flow rate can be optimized by the control system <NUM> to improve patient comfort and therapy.

The control system <NUM> can generate audio and/or display/visual outputs <NUM>, <NUM>. For example, the flow therapy apparatus can include a display and/or a speaker. The display can indicate to the physicians any warnings or alarms generated by the control system <NUM>. The display can also indicate control parameters that can be adjusted by the physicians. For example, the control system <NUM> can automatically recommend a flow rate for a particular patient. The control system <NUM> can also determine a respiratory state of the patient, including but not limited to generating a respiratory rate of the patient, and send it to the display.

The control system <NUM> can change heater control outputs to control one or more of the heating elements (for example, to maintain a temperature set point of the gas delivered to the patient). The control system <NUM> can also change the operation or duty cycle of the heating elements. The heater control outputs can include heater plate control output(s) <NUM> and heated breathing tube control output(s) <NUM>.

The control system <NUM> can determine the outputs <NUM>-<NUM> based on one or more received inputs <NUM>-<NUM>. The inputs <NUM>-<NUM> can correspond to sensor measurements received automatically by the controller (shown in <FIG>, <FIG> and <FIG>). The control system <NUM> can receive sensor inputs including but not limited to temperature sensor(s) inputs <NUM>, flow rate sensor(s) inputs <NUM>, motor speed inputs <NUM>, pressure sensor(s) inputs <NUM>, gas(s) fraction sensor(s) inputs <NUM>, humidity sensor(s) inputs <NUM>, pulse oximeter (for example, SpO<NUM>) sensor(s) inputs <NUM>, stored or user parameter(s) <NUM>, duty cycle or pulse width modulation (PWM) inputs <NUM>, voltage(s) inputs <NUM>, current(s) inputs <NUM>, acoustic sensor(s) inputs <NUM>, power(s) inputs <NUM>, resistance(s) inputs <NUM>, CO<NUM> sensor(s) inputs <NUM>, and/or spirometer inputs <NUM>. The control system <NUM> can receive inputs from the user or stored parameter values in a memory <NUM> (shown in <FIG>). The control system <NUM> can dynamically adjust flow rate for a patient over the time of their therapy. The control system <NUM> can continuously detect system parameters and patient parameters. Any other suitable inputs and/or outputs can be used with the control system <NUM>. For example, with the pulse oximeter sensor(s) input <NUM>, the control system <NUM> can implement one or more closed loop control systems to control the composition of oxygen in the flow of gases, such as described in International application No. <CIT> and published as <CIT>. With the closed loop control system(s), the flow therapy apparatus can monitor blood oxygen saturation (SpO<NUM>) of a patient and control the fraction of oxygen delivered to the patient (FdO<NUM>). The flow therapy apparatus can also automatically adjust the FdO<NUM> in order to achieve a targeted SpO<NUM> value for the patient.

As illustrated in <FIG>, the control system <NUM> can receive inputs from multiple components of the flow therapy apparatus, such as thoraco-abdominal asynchrony (TAA) sensor inputs <NUM>, respiratory sensor inputs <NUM>, work of breathing (WOB) sensor inputs <NUM>, CO2 and/or pressure sensor inputs <NUM>, user inputs and/or stored values <NUM>. Not all of the inputs <NUM>-<NUM> shown in <FIG> may be present. The control system <NUM> in <FIG> can output based on the inputs <NUM>-<NUM> heater control output <NUM>, flow control output(s) <NUM>, and display/audio output(s) <NUM>. The inputs <NUM> to <NUM> and the outputs <NUM> to <NUM> may not all necessarily be present. For example, the control system <NUM> may only receive the WOB sensor (such as EMG) input <NUM> and generate a flow control measurement <NUM>. Depending on the configuration, some of the components corresponding to the inputs may not be included in the flow therapy apparatus. Lack of input itself can be used by the control system <NUM> to determine the input or system conditions.

The control system <NUM> can include programming instructions for detection of input conditions and control of output conditions. <FIG> illustrates a block diagram of an example controller <NUM>. The programming instructions can be stored in a memory <NUM> of the controller <NUM>. The programming instructions can correspond to the methods, processes and functions described herein. The control system <NUM> can be executed by one or more hardware processors <NUM> of the controller <NUM>. The programming instructions can be implemented in C, C++, JAVA, or any other suitable programming languages. The controller can also include circuits <NUM> for receiving sensor signals. Some or all of the portions of the control system <NUM> can be implemented in application specific circuitry <NUM> such as ASICs and FPGAs.

The controller can further include a display <NUM> for transmitting status of the patient and the respiratory assistance system. The display <NUM> can also show warnings. The controller can also receive user inputs via the user interface such as the display <NUM>. The user interface may alternatively or additionally include buttons or a dial.

<FIG> illustrates a block diagram of a motor/sensor module <NUM> which may be used as part of the flow therapy apparatus. The motor/sensor module includes a flow generator <NUM>, which entrains room air to deliver to a patient. The flow generator <NUM> can be a centrifugal blower.

Room air enters a room air inlet <NUM>, which enters the flow generator <NUM> through an inlet port <NUM>. The inlet port <NUM> can include a valve <NUM> through which a pressurized gas may enter the flow generator <NUM>. The valve <NUM> can control a flow of oxygen (or other auxiliary gases) into the blower <NUM>. The valve <NUM> can be any type of valve, including a proportional valve or a binary valve. The inlet port can include no valves.

The flow generator <NUM> can operate at a motor speed of greater than <NUM>,<NUM> RPM and less than <NUM>,<NUM> RPM, greater than <NUM>,<NUM> RPM and less than <NUM>,<NUM> RPM, greater than <NUM>,<NUM> RPM and less than <NUM>,<NUM> RPM, or between any of the foregoing values. Operation of the flow generator <NUM> mixes the gases entering the flow generator <NUM> through the inlet port <NUM>. Using the flow generator <NUM> as the mixer can decrease the pressure drop that would otherwise occur in a system with a separate mixer, such as a static mixer comprising baffles, because mixing requires energy whereas the flow generator imparts energy.

The mixed air exits the flow generator <NUM> through a conduit <NUM> and enters the flow path <NUM> in the sensing chamber <NUM>. A circuit board with sensors <NUM> is positioned in the sensing chamber <NUM> such that the circuit board is immersed in the gas flow. The sensors <NUM> on the circuit board are positioned within the gas flow to measure gas properties within the flow. After passing through the flow path <NUM> in the sensing chamber <NUM>, the gases exit <NUM> to the humidification chamber <NUM>.

The flow path <NUM> has a curved shape. The gas flow enters at an entrance <NUM>, flows along a curved flow path <NUM>, and exits on the opposite side of the flow path <NUM>. The entrance and exit may be positioned in vertically opposed directions, and the gas flow may enter the path in a vertical upwards direction, then curve around to a horizontal direction, and then curve around to a vertical upwards direction again. The flow path may have no sharp turns. The flow path may have curved ends with a straighter middle section. The flow path can maintain a constant cross-section shape throughout the length of the flow path. The flow path can taper inward slightly from the first end of the flow path, and widens again to the second end of the flow path, which can speed up the flow for better accuracy, stability and reproducibility in measurements. The surface of the flow path can be lined with a surface modifier/lubricant to reduce friction within the flow path. A curved flow path shape can reduce a gas flow's pressure drop without reducing the sensitivity of flow measurements by partially coinciding the measuring region with the flow path. A number of different flow path configurations can be used.

As shown in <FIG>, the mixed air can exit the flow generator and enter a flow path <NUM> in a sensor chamber <NUM>, which can be located in the motor/sensor module. A sensing circuit board <NUM> with sensors, such as ultrasonic transducers <NUM> and/or heated temperature sensing elements, can be positioned in the sensor chamber <NUM> such that the sensing circuit board is at least partially immersed in the gas flow. At least some of the sensors on the sensing circuit board can be positioned within the gas flow to measure gas properties within the flow. After passing through the flow path <NUM> in the sensor chamber <NUM>, the gas can exit to the humidification chamber.

The sensing circuit board <NUM> can include sensors such as acoustic transmitters and/or receivers, humidity sensor, temperature sensor, thermistor, and the like. A gas flow rate may be measured using at least two different types of sensors. The first type of sensor can include a heated temperature sensing element (or a thermistor), which can determine a flow rate by monitoring heat transfer between the gases flow and the heated temperature sensing elements. The heated temperature sensing elements can be run at a constant target temperature within the flow when the gas flows around and past the heated temperature sensing elements. The sensor can measure an amount of power required to maintain the heated temperature sensing elements at the target temperature. The target temperature can be configured to be higher than a temperature of the gas flow, such that more power is required to maintain the heated temperature sensing elements at the target temperature at a higher flow rate.

The second type of sensor can include an acoustic (such as ultrasonic transducer) sensor assembly. Acoustic sensors including acoustic transmitters and/or receivers can be used to measure a time of flight of acoustic signals to determine gas velocity and/or composition, which can be used in flow therapy apparatuses. In one ultrasonic sensing (including ultrasonic transducers, which can act as transmitters and/or receivers) topology, a driver causes a first sensor, such as an ultrasonic transducer, to produce an ultrasonic pulse in a first direction. A second sensor, such as a second ultrasonic transducer, receives this pulse and provides a measurement of the time of flight of the pulse between the first and second ultrasonic transducers. Using this time of flight measurement, the speed of sound of the gas flow between the ultrasonic transducers can be calculated by a processor or controller of the flow therapy apparatus. The second sensor can also transmit and the first sensor can receive a pulse in a second direction opposite the first direction to provide a second measurement of the time of flight, allowing characteristics of the gas flow, such as a flow rate or velocity, to be determined. In another acoustic sensing topology, acoustic pulses transmitted by an acoustic transmitter, such as an ultrasonic transducer, can be received by acoustic receivers, such as microphones.

Readings from both the first and second types of sensors can be combined to determine a more accurate flow measurement. For example, a previously determined flow rate and one or more outputs from one of the types of sensor can be used to determine a predicted current flow rate. The predicted current flow rate can then be updated using one or more outputs from the other one of the first and second types of sensor, in order to calculate a final flow rate.

Some patients may find it more comfortable to adjust the operation of a flow therapy apparatus based upon the patient's breath cycle. For example, as a patient inhales and exhales, a flow rate of air provided by the flow therapy apparatus may be adjusted. The flow rate may be increased during the patient's inspiration, and decreased during the patient's expiration. The flow rate may be adjusted during a patient's inspiration (for example, increased during inspiration), with no adjustment during the patient's expiration, or vice versa. Inspiration and expiration may also be referred to as inhalation and exhalation.

A patient's breathing cycle may be represented as a waveform comprising alternating inhalation and exhalation phases. By determining and monitoring a patient's breath cycle waveform, operations of the flow therapy apparatus can be modified based upon the patient's breath cycle. For example, the flow therapy apparatus may be configured to control a gas flow using a periodic waveform, which may be adjusted based upon the patient's measured breath cycle waveform.

<FIG> illustrates a flowchart of an example process for adjusting the operation of a flow therapy apparatus. At block <NUM>, a control signal is used to drive a motor associated with the flow therapy apparatus (for example, flow generator <NUM> as illustrated in <FIG>). The motor may be used to generate an air flow in order to assist the respiration of a patient. The control signal may include an initial waveform. The initial waveform may include a default waveform, or be based upon one or more measurements associated with the patient.

At block <NUM>, a plurality of measurements are received at the controller that may be used to determine a breathing cycle of the patient. These may include a flow rate 404a, a motor speed 404b, a pressure 404c, and/or the like.

At block <NUM>, the received measurements are used to determine a predicted breath cycle of the patient. The predicted breath cycle of the patient may be determined using one or more different techniques, such as by monitoring flow deviation (for example, from an average or set-point flow rate value), flow restriction (for example, as discussed below), system leak (that is, a portion of the flow of air generated by a blower that did not flow to a patient's lungs), and/or the like.

With continued reference to <FIG>, at block <NUM>, the control signal to the motor is adjusted based upon the predicted breath cycle. For example, the control signal may be adjusted so that the flow rate is increased as the patient inhales, and decreased as the patient exhales.

The process may then return to block <NUM>, where the adjusted control signal is used to drive the blower motor to produce an air flow for the patient.

The process can also be implemented on a respiratory system with a sealed patient interface. The pressure sensor can be placed anywhere in the flow path. A nonlimiting example of a sealed patient interface is an NIV mask. NIV masks can be sealed against the patient's face, resulting in substantially no system leak. This makes it possible to measure the pressure of the gases delivered to the patient near or at the patient end. For example, the pressure sensor can be positioned inside the NIV mask or at a location outside the patient's nares. The pressure sensor can be positioned in a manifold connecting the NIV mask to the patient breathing conduit, such as the patient breathing conduit <NUM> shown in <FIG>.

<FIG> illustrates a block diagram of an example system for adjusting the control signal to the motor at block <NUM> of <FIG>. As illustrated in <FIG>, a patient <NUM> is connected to a flow therapy apparatus <NUM>, such as the flow therapy apparatus <NUM> of <FIG>. The apparatus can include a flow generator with a motor <NUM>, which may be used to provide an air flow to the patient <NUM>.

During operation of the flow therapy apparatus <NUM>, a plurality of measurements may be taken and transmitted to a control signal feedback module <NUM>, in order to adjust a control signal to the motor <NUM> based upon a breath cycle of the patient <NUM>. For example, parameters of the motor <NUM> may be used to measure a motor speed as described above and/or a system pressure. A flow rate of the air flow may be monitored using one or more flow rate sensors <NUM>. The flow rate sensors <NUM> may include two or more different types of sensors, such as a heated temperature sensing element and an ultrasonic transducer assembly. In addition, one or more additional sensors, such as pressure sensors may be used to measure one or more additional measurements (for example, pressure).

The plurality of measurements (for example, motor speed, flow rate, and/or the like) may be used to determine a breath cycle of the patient at a breath cycle detection module <NUM>. The determined breath cycle may be in the form of an alternating waveform (for example, a substantially sinusoidal waveform). The measurements about the motor <NUM> and the measurements by the flow rate sensor <NUM> can both be fed into the breath cycle detection module <NUM>.

Once the breath cycle of the patient has been determined, it may be used to adjust the control signal to the motor <NUM>. For example, the calculated breath cycle waveform from the breath cycle detection module <NUM> may be subject to positive feedback <NUM>.

Positive feedback <NUM> can function to work with the patient during the patient's breath cycle by reducing the motor speed as the patient exhales, and/or increasing motor speed as the patient inhales. Positive feedback may be implemented during inspiration but not during expiration, or positive feedback may be implemented during expiration but not during inspiration. For example, a patient that attempts to lower his or her work when breathing using "pursed lip breathing" on expiration may benefit from being assisted with positive feedback for increasing flow rate during inspiration, but no positive feedback for decreasing flow rate during expiration. By not implementing positive feedback during expiration, expiration pressure and expiration time may be increased, which may be beneficial for certain patients. One or more scaling parameters may be used to increase or decrease the magnitude of the control signal controlling the speed of motor <NUM>, based upon a determined magnitude of the patient's inhale/exhale. For example, positive feedback for the blower motor control signal may be expressed as: <MAT> where ω corresponds to motor speed, R corresponds to a patient restriction, ω and R correspond to their average or baseline values, and kp corresponds to a positive feedback parameter.

As noted above, flow restriction may also be used to determine a patient's breath cycle. In general, a breathing system as a whole can have some resistance to flow (also referred to as "Restriction" or R), which can be used to indicate a relationship between change in pressure p of the system and the flow of the system. The restriction R may vary as the patient inhales and exhales. Larger values of R represent larger restrictions (for example, when the patient exhales).

With continued reference to <FIG>, the measurements from the flow rate sensor <NUM> can also be fed into a minimum and/or maximum detection module <NUM> for the measured flow rate. The minimum and/or maximum measured flow rate can be used to determine a negative feedback term <NUM>, which can then be combined <NUM> with positive feedback <NUM> to generate a control signal for the motor <NUM>.

Negative feedback may limit the positive feedback applied to the control signal to certain bounds, thereby suppressing the change to the control signal as the patient inhales or exhales. The negative feedback can include a minimum and/or maximum threshold flow rate value. A minimum flow rate value can ensure that the apparatus maintains the flow above a threshold, regardless of how hard the patient is breathing. This can ensure the effectiveness and/or safety of a high flow therapy. The maximum flow rate value can limit the amount of adjustment of the flow rate based on the patient's breath cycle even as the magnitude of the patient's inspiration or expiration increases.

The positive feedback <NUM> can include a breath synchronisation setting on the display of the apparatus adjustable by a user or care provider. The positive feedback breath synchronisation settings can allow the user or care provider to adjust the settings of the machine to further improve comfort and/or effectiveness by manually adjusting an amount of positive feedback. The settings can include, for example, any number of selectable values, such as <NUM>-<NUM>, <NUM>-<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or others. The selectable values can be labelled by being numbered. Alternatively, the selectable values can be labelled as different categories, such as high, medium, and/or low settings. Alternatively, the settings can allow the user to go higher (for example, by pressing a "+" button or the like) or lower (for example, by pressing a "-" button or the like) on the breath synchronization value.

The breath synchronisation can be introduced gradually, for example, by increasing the amplitude of the positive feedback while keeping the average target flow rate the same during the time when the amplitude is increased. The gradual introduction can occur when the breath synchronisation is first turned on, and/or when the user increases an expiratory relief level (that is, increasing the positive feedback level). The gradual introduction can cause the positive feedback to be slowly increased from zero or its previous level up to its new value over a predetermined duration, for example, about <NUM> seconds, about <NUM> minute, about <NUM> minutes, about <NUM> minutes, about <NUM> minutes or about <NUM> minutes. This can result in the motor speed oscillations, and in turn the flow rate oscillations, to slowly increase in amplitude. The gradual introduction can reduce potential patient discomfort during the initial stage of the breath synchronisation, in which the flow rate changes may not be fully synchronised with the patient's breathing. During the gradual introduction, the flow rate may begin to cross the flow rate thresholds. At this point, the negative feedback term can also begin to gradually increase, cancelling or substantially cancelling the further increase in the positive feedback term, in order to maintain the flow rate within the maximum and/or minimum thresholds.

An example of the effect of positive feedback on the motor speed is illustrated in <FIG>. As shown in the top graph of <FIG>, the motor speed <NUM> varies over several breath periods. The motor speed can include a nominal motor speed and positive feedback, with the maximum and minimum values of the motor speed enveloped by the positive feedback term <NUM>. There is a limit on the amount of positive feedback <NUM>, which is initially set high enough so that no limiting occurs. Correspondingly, the initially sensed maximum and minimum flow rates are unbounded responses to the patient's breathing, and are gradually bounded by the negative feedback. The process for determining the flow rate, such as shown in <FIG>, does not know in advance the extent of adjustment of the motor speed so as to stay within the limit or threshold. The negative feedback therefore gradually bounds the positive feedback, for example, the negative feedback can be gradually increased until the measured or sensed maximum and/or minimum flow rates no longer exceeds the limit or threshold.

The minimum and/or maximum threshold flow rate can be fixed values, that is, regardless of the selected flow rate or the selected breath synchronization value. Alternatively or additionally, the minimum and/or maximum threshold flow rate can be set by the user. This can ensure that the device always delivers a minimum flow rate and/or never exceeds a maximum flow rate, regardless of the selected flow rate or the selected breath synchronisation value. Allowing the user to set the threshold(s) can also allow the flow therapy apparatus to deliver gases at a flow rate that is comfortable to the specific patient. The maximum and/or minimum thresholds can be set independent of the breath synchronization setting. For example, a clinician can be allowed to set a maximum and/or minimum threshold to ensure the effectiveness and/or safety of the high flow therapy, while the patient can be allowed to set the breath synchronization value based on what the patient find most comfortable.

Alternatively or additionally, the minimum and/or maximum flow rate can be determined based on a target flow rate set by the user. For example, the maximum and/or minimum flow rate can be a certain percentage above and below the selected flow rate. Alternatively or additionally, the maximum and/or minimum flow rate can be a certain value above and below the selected flow rate.

Alternatively or additionally, the minimum and/or maximum flow rate can be based on both the selected flow rate and the selected breath synchronization value. For example, the maximum and/or minimum flow rate can be a certain percentage above and below the selected flow rate. This percentage value can then vary based on the selected breath synchronization value. Alternatively, the maximum and/or minimum flow rate can be a certain value above and below the selected flow rate. This value can then vary based on the selected breath synchronization value.

The bottom graph of <FIG> shows the flow rate <NUM> sensed by the flow rate sensor(s) of the apparatus and the minimum and maximum flow rates <NUM>, <NUM> that have been set by the user. The flow rate <NUM> results from the motor speed changes according to the top graph of <FIG> and the patient's positive feedback. To keep the flow rate within these limits <NUM>, <NUM>, the controller of the apparatus measures the minimum and maximum flow rate within each breath, and then iteratively adjusts the feedback loop to drive the flow within the bounds such as by following the process shown in <FIG>.

As shown in <FIG>, the user interface <NUM>, which can be the user interface <NUM> of <FIG>, can display a setting that allows a user, such as a patient or a clinician, to adjust an expiratory relief ("ER") level <NUM>. The expiratory relief levels correspond to the positive feedback terms or breath synchronization settings described above. As shown in <FIG>, the user can choose four different levels of expiratory relief, which can include no expiratory relief (that is, no positive feedback) as illustrated by all three ER circles <NUM> being empty in <FIG>, a first or lowest level of expiratory relief, a second level expiratory relief as illustrated by two of the three ER circles <NUM> being solid in <FIG>, and a third or highest level of expiratory relief (that is, a highest or maximum positive feedback term). The user can adjust the expiratory relief level, for example, via buttons <NUM> or other forms of user input for increasing or decreasing the level.

The ER level <NUM> as shown in <FIG> illustrates an example expiratory relief setting. As described above, the user interface can display other forms of expiratory relief setting, such as numerical values, a sliding scale, or otherwise. The expiratory relief setting can include different numbers of levels, which can be discrete levels or on a continuum. As shown in <FIG>, when the expiratory relief setting menu is collapsed, the user interface <NUM> can also display a previously selected expiratory relief level <NUM> on the screen (for example, below a target flow rate value). The previously selected expiratory relief level <NUM> can also optionally be displayed only when the user has set the amount of expiratory relief to a value above <NUM>.

As shown in <FIG>, the user interface <NUM> can also optionally allow adjustments of a set flow rate <NUM>, for example, via buttons <NUM> or other forms of user input for increasing or decreasing the set flow rate <NUM>. The user interface <NUM> can also display a maximum <NUM> and minimum <NUM> flow rate threshold between which the user is allowed to adjust the set flow rate <NUM>. In a configuration, the maximum and minimum flow rate thresholds can be set by a user (such as a clinician) on a separate menu. The separate menu may be designed to be used by the clinician, a technician and/or an engineer. The separate menu may be designed to be inaccessible to a patient or other regular users.

Referring additionally to <FIG>, a system <NUM> is shown that is similar to the system of <FIG>. The system of <FIG> additionally comprises an oxygen inlet port <NUM> for connection to a source of oxygen (such as a hospital oxygen supply or a oxygen canister or the like), in addition to ambient inlet port <NUM>. The system of <FIG> also comprises a temperature sensor <NUM> at or near the end of the inspiratory tube. The system <NUM> of <FIG> is also suitable for implementing control of the flow of breathable gases in accordance with this disclosure.

Operation sensors 3a, 3b, 3c, such as flow, temperature, humidity, and/or pressure sensors can be placed in various locations in the flow therapy system <NUM>. Additional sensors (for example, sensors <NUM>, <NUM>) may be placed in various locations on the patient conduit <NUM> and/or cannula <NUM> (for example, there may be a temperature sensor <NUM> at or near the end of the inspiratory tube). Output from the sensors can be received by the controller <NUM>, to assist the controller in operating the flow therapy system <NUM> in a manner that provides suitable therapy. In some configurations, providing suitable therapy includes meeting a patient's peak inspiratory demand. The system <NUM> may have a transmitter and/or receiver <NUM> to enable the controller <NUM> to receive signals <NUM> from the sensors and/or to control the various components of the flow therapy system <NUM>, including but not limited to the flow generator <NUM>, humidifier <NUM>, and heater wire 16a, or accessories or peripherals associated with the flow therapy system <NUM>. Additionally, or alternatively, the transmitter and/or receiver <NUM> may deliver data to a remote server or enable remote control of the system <NUM>.

Oxygen may be measured by placing one or more gas composition sensors (such as an ultrasonic transducer system, also referred to as an ultrasonic sensor system) after the oxygen and ambient air have finished mixing. The measurement can be taken within the device, the delivery conduit, the patient interface, or at any other suitable location.

Oxygen concentration may also be measured by using flow rate sensors on at least two of the ambient air inlet conduit, the oxygen inlet conduit, and the final delivery conduit to determine the flow rate of at least two gases. By determining the flow rate of both inlet gases or one inlet gas and one total flow rate, along with the assumed or measured oxygen concentrations of the inlet gases (about <NUM>% for ambient air, about <NUM>% for oxygen), the oxygen concentration of the final gas composition can be calculated. Alternatively, flow rate sensors can be placed at all three of the ambient air inlet conduit, the oxygen inlet conduit, and the final delivery conduit to allow for redundancy and testing that each sensor is working correctly by checking for consistency of readings. Other methods of measuring the oxygen concentration delivered by the flow therapy apparatus <NUM> can also be used.

The flow therapy system <NUM> can include a patient sensor <NUM>, such as a pulse oximeter or a patient monitoring system, to measure one or more physiological parameters of the patient, such as a patient's blood oxygen saturation (SpO2), heart rate, respiratory rate, perfusion index, and provide a measure of signal quality. The sensor <NUM> can communicate with the controller <NUM> through a wired connection or by communication through a wireless transmitter on the sensor <NUM>. The sensor <NUM> may be a disposable adhesive sensor designed to be connected to a patient's finger. The sensor <NUM> may be a non-disposable sensor. Sensors are available that are designed for different age groups and to be connected to different locations on the patient, which can be used with the flow therapy system <NUM>. The pulse oximeter would be attached to the user, typically at their finger, although other places such as an earlobe are also an option. The pulse oximeter would be connected to a processor in the device and would constantly provide signals indicative of the patient's blood oxygen saturation. The patient sensor <NUM> can be a hot swappable device, which can be attached or interchanged during operation of the flow therapy system <NUM>. For example, the patient sensor <NUM> may connect to the flow therapy system <NUM> using a USB interface or using wireless communication protocols (such as, for example, near field communication, WiFi or Bluetooth®). When the patient sensor <NUM> is disconnected during operation, the flow therapy system <NUM> may continue to operate in its previous state of operation for a defined time period. After the defined time period, the flow therapy system <NUM> may trigger an alarm, transition from automatic mode to manual mode, and/or exit control mode (e.g., automatic mode or manual mode) entirely. The patient sensor <NUM> may be a bedside monitoring system or other patient monitoring system that communicates with the flow therapy system <NUM> through a physical or wireless interface.

With reference again to <FIG>, the controller <NUM> can be programmed with or configured to execute a closed loop control system for controlling the operation of the flow therapy system <NUM>. The closed loop control system can be configured to ensure the patient's SpO2 reaches a target level and consistently remains at or near this level.

The controller <NUM> can receive input(s) from a user that can be used by the controller <NUM> to execute the closed loop control system. The target SpO2 value can be a single value or a range of values. The value(s) could be pre-set, chosen by a clinician, or determined based on the type of patient, where type of patient could refer to current affliction, and/or information about the patient such as age, weight, height, gender, and other patient characteristics. Similarly, the target SpO2 could be two values, each selected in any way described above. The two values would represent a range of acceptable values for the patient's SpO2. The controller can target a value within said range. The targeted value could be the middle value of the range, or any other value within the range, which could be pre-set or selected by a user. Alternatively, the range could be automatically set based on the targeted value of SpO2. The controller can be configured to have one or more set responses when the patient's SpO2 value moves outside of the range. The responses may include alarming, changing to manual control of FdO2, changing the FdO2 to a specific value, and/or other responses. The controller can have one or more ranges, where one or more different responses occur as it moves outside of each range.

The graphical user interface of the flow therapy system <NUM> may be configured to prompt the user to input a patient type, and the SpO2 limits would be determined based on what the user selects. Additionally, the user interface may include a custom option, where the user can define the limits.

Generally, SpO2 would be controlled between about <NUM>% and about <NUM>%, or about <NUM>% and about <NUM>%, or about <NUM>% and about <NUM>%, or about <NUM>% and about <NUM>%, or about <NUM>% and about <NUM>%. The SpO2 could be controlled between any two suitable values from any two of the aforementioned ranges. The target SpO2 could be between about <NUM>% and about <NUM>%, or between about <NUM>% and about <NUM>%, or between about <NUM>% and about <NUM>%, or between about <NUM>% and about <NUM>%, or between about <NUM>% and about <NUM>%, or about <NUM>%, or <NUM>% or about <NUM>%, or <NUM>%, or about <NUM>%, or <NUM>%. The SpO2 target could be any value between any two suitable values from any two of the aforementioned ranges. The SpO2 target can correspond to the middle of the SpO2 for a defined range.

The FdO2 can be configured to be controlled within a range. As discussed previously, the oxygen concentration measured in the system (FdO2) would be substantially the same as the oxygen concentration the patient is breathing (FiO2) so long as the flow rate meets or exceeds the peak inspiratory demand of the patient, and as such the terms may can be seen as equivalent. Each of the limits of the range could be pre-set, selected by a user, or determined based on the type of patient, where the type of patient could refer to current affliction, and/or information about the patient such as age, weight, height, gender, and/or other patient characteristic. Alternatively, a single value for FdO2 could be selected, and the range could be determined at least partially based on this value. For example, the range could be a set amount above and below the selected FdO2. The selected FdO2 could be used as the starting point for the controller. The system could have one or more responses if the controller tries to move the FdO2 outside of the range. These responses could include alarming, preventing the FdO2 moving outside of the range, switching to manual control of FdO2, and/or switching to a specific FdO2. The device could have one or more ranges where one or more different responses occur as it reaches the limit of each range.

FdO2 can be controlled between about <NUM>% and about <NUM>%, or about <NUM>% and about <NUM>%, or about <NUM>% and about <NUM>%, or about <NUM>% and about <NUM>%, or about <NUM>% and about <NUM>%, or about <NUM>% and about <NUM>%, or about <NUM>% and about <NUM>%. The FdO2 could be controlled between any two suitable values from any two ranges described. The FdO2 target could be between any two suitable values from any two ranges described. If the range is based on the single value, the upper and lower limits could be decided by adding/subtracting a fixed amount from the selected value. The amount added or subtracted could be about <NUM>%, or about <NUM>%, or <NUM> %, or about <NUM>%, or about <NUM>%, or about <NUM>%, or about <NUM>%, or about <NUM>%. The amount added/subtracted could change relative to the selected value. For example, the upper limit could be <NUM>% higher than the selected value, so a selected value of <NUM>% FdO2 would have an upper limit of <NUM>% for the range of control. The percentage used for the range could be about <NUM>%, or about <NUM>%, or <NUM> %, or about <NUM>%, or about <NUM>%, or about <NUM>%, or about <NUM>%, or about <NUM>%. The method for calculating the lower limit and the upper would not necessarily need to be the same. If a single value is used, the value could be between about <NUM>% and about <NUM>%, or about <NUM>% and about <NUM>%, or about <NUM>% and about <NUM>%, or about <NUM>% and about <NUM>%, or about <NUM>% and about <NUM>%, or about <NUM>% and about <NUM>%, or about <NUM>% and about <NUM>%.

With reference to <FIG> a schematic diagram of the closed loop control system <NUM> is illustrated. The closed loop control system may utilize two control loops. The first control loop may be implemented by the SpO2 controller. The SpO2 controller can determine a target FdO2 based in part on the target SpO2 and/or the measured SpO2. As discussed above, the target SpO2 value can be a single value or a range of acceptable values. The value(s) could be pre-set, chosen by a clinician, or determined automatically based on client characteristics. Generally, target SpO2 values are received or determined before or at the beginning of a therapy session, though target SpO2 values may be received at any time during the therapy session. During a therapy session, the SpO2 controller can also receive as inputs: measured FdO2 reading(s) from a gases composition sensor, and measured SpO2 reading(s) and a signal quality reading(s) from the patient sensor. In some configurations, the SpO2 controller can receive target FdO2 as an input, in such a case, the output of the SpO2 controller may be provided directly back to the SpO2 controller as the input. Based at least in part on the inputs, the SpO2 controller can output a target FdO2 to the second control loop.

The second control loop may be implemented by the FdO2 controller. The FdO2 controller can receive inputs of measured FdO2 and target FdO2. The FdO2 controller can then output an oxygen inlet valve control signal to control the operation of the oxygen valve based on a difference between these measured FdO2 and target FdO2 values. The FdO2 controller may receive the target FdO2 value that is output from the first control loop when the flow therapy system <NUM> is operating in automatic mode. The FdO2 controller may also receive additional parameters such as flow rate values, gas properties, and/or measured FdO2. The gas properties may include the temperature of the gas at the O2 inlet and/or the oxygen content of the supply source. The gases supply source connected to the oxygen inlet valve may be an enriched oxygen gasflow where the oxygen content of the supply source may be less than pure oxygen (i.e., <NUM>%). For example, the oxygen supply source may be an oxygen enriched gas flow having an oxygen content of less than <NUM>% and greater than <NUM>%.

From at least some of the inputs, the FdO2 controller can determine an oxygen flow rate that would be required to achieve the target FdO2. The FdO2 controller can use the flow rate input in order to alter the valve control signal. If the flow rate changes, the FdO2 controller can automatically calculate a new required oxygen flow rate required to maintain the target FdO2 at the new flow rate without having to wait for feedback from the gas concentration sensor, such as the measured FdO2 value. The FdO2 controller can then output the altered valve control signal to control the valve based on the new flow rate. In some configurations, the control signal of the FdO2 controller may set the current of the oxygen valve in order to control operation of the oxygen valve. Additionally, or alternatively, the FdO2 controller could detect changes to the measured FdO2 and alter the position of the valve accordingly. During manual mode, the second control loop can operate independently without receiving the target FdO2 from the first control loop. Rather, the target FdO2 can be received from user input or a default value.

During the therapy session, the SpO2 and FdO2 controllers can continue to automatically control the operation of the flow therapy system until the therapy session ends or an event triggers a change from the automatic mode to manual mode.

Although this disclosure has been described in the context of certain embodiments and examples, it will be understood by those skilled in the art that the disclosure extends beyond the specifically disclosed embodiments to other alternative embodiments and/or uses and obvious modifications and equivalents thereof. In addition, while several variations of the embodiments of the disclosure have been shown and described in detail, other modifications, which are within the scope of this disclosure, will be readily apparent to those of skill in the art. It is also contemplated that various combinations or subcombinations of the specific features and aspects of the embodiments may be made and still fall within the scope of the disclosure. For example, features described above in connection with one embodiment can be used with a different embodiment described herein and the combination still fall within the scope of the disclosure. It should be understood that various features and aspects of the disclosed embodiments can be combined with, or substituted for, one another in order to form varying modes of the embodiments of the disclosure. Thus, it is intended that the scope of the disclosure herein should not be limited by the particular embodiments described above.

Features, materials, characteristics, or groups described in conjunction with a particular aspect, embodiment, or example are to be understood to be applicable to any other aspect, embodiment or example described in this section or elsewhere in this specification unless incompatible therewith.

Furthermore, certain features that are described in this disclosure in the context of separate implementations can also be implemented in combination in a single implementation. Moreover, although features may be described above as acting in certain combinations, one or more features from a claimed combination can, in some cases, be excised from the combination, and the combination may be claimed as a subcombination or variation of a subcombination.

Conditional language used herein, such as, among others, "can," "could," "might," "may," "e.g.," and the like, unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements and/or steps. Thus, such conditional language is not generally intended to imply that features, elements and/or steps are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without other input or prompting, whether these features, elements and/or steps are included or are to be performed in any particular embodiment.

As another example, in certain embodiments, the terms "generally parallel" and "substantially parallel" refer to a value, amount, or characteristic that departs from exactly parallel by less than or equal to <NUM> degrees, <NUM> degrees, <NUM> degrees, <NUM> degrees, <NUM> degree, <NUM> degree, or otherwise.

Any methods disclosed herein need not be performed in the order recited. The methods disclosed herein include certain actions taken by a practitioner; however, they can also include any third-party instruction of those actions, either expressly or by implication. For example, actions such as "controlling a motor speed" include "instructing controlling of a motor speed.

All of the methods and tasks described herein may be performed and fully automated by a computer system. The computer system may, in some cases, include multiple distinct computers or computing devices (e.g., physical servers, workstations, storage arrays, cloud computing resources, etc.) that communicate and interoperate over a network to perform the described functions. Each such computing device typically includes a processor (or multiple processors) that executes program instructions or modules stored in a memory or other non-transitory computer-readable storage medium or device (e.g., solid state storage devices, disk drives, etc.). The various functions disclosed herein may be embodied in such program instructions, and/or may be implemented in application-specific circuitry (e.g., ASICs or FPGAs) of the computer system. Where the computer system includes multiple computing devices, these devices may, but need not, be co-located. The results of the disclosed methods and tasks may be persistently stored by transforming physical storage devices, such as solid state memory chips and/or magnetic disks, into a different state. In some embodiments, the computer system may be a cloud-based computing system whose processing resources are shared by multiple distinct business entities or other users.

Claim 1:
A respiratory system (<NUM>) for delivering a respiratory therapy to a patient, the system (<NUM>) configured to adjust a flow rate of gases delivered to the patient according to patient inspiration and expiration, the system (<NUM>) comprising:
a flow generator (<NUM>) with a motor for generating a gases flow; and
a controller (<NUM>) in electrical communication with one or more sensors (3a, 3b, 3c, <NUM>, <NUM>) and configured to:
cause to be displayed, on a user interface (<NUM>) of the respiratory system (<NUM>), an expiratory relief level setting, the setting comprising a plurality of different expiratory relief levels (<NUM>);
receive a user input via the user interface (<NUM>) to increase and/or decrease an expiratory relief level (<NUM>);
determine a cycle of the patient inspiration and expiration based on information received from the one or more sensors (3a, 3b, 3c, <NUM>, <NUM>); and
adjust the flow rate based in part on the cycle of the patient inspiration and expiration, wherein the adjusting is attenuated by a parameter determined based in part on a maximum and/or minimum flow rate measured by the one or more sensors (3a, 3b, 3c, <NUM>, <NUM>) during the cycle of the patient inspiration and expiration.