Flow path sensing for flow therapy devices

Abstract

This application relates to flow path sensing for flow therapy devices. Systems and methods for respiratory therapy in a respiratory system can adjust the flow of respiratory gases based on a detected patient respiratory cycle. The respiratory system can include a non-sealing patient interface. The respiratory system can be configured to deliver high flow therapy. The patient respiratory cycle can be determined using one or more measured parameters such as flow rate, blower motor speed, and / or system pressure. A flow source can be adjusted to have a phase that matches the phase of the patient respiratory cycle such that the flow increases in response to patient inhalation and decreases in response to patient exhalation.

Description

[0001] This application is a divisional application of the invention patent application 201780039600.0, filed May 17, 2017, entitled "Flow Path Sensing for Flow Therapy Devices." TECHNICAL FIELD

[0002] The present disclosure relates to methods and systems for flow path sensing in flow therapy devices that deliver a flow of gas to a patient. This application claims priority to U.S. Patent Applications 62 / 337,795 and 62 / 507,013, the entire contents of which are incorporated herein by reference. BACKGROUND

[0003] Respiratory assist devices are used to deliver a flow of gas to a user or patient in various environments, such as hospitals, medical facilities, home care, or home environments. Respiratory assist devices or flow therapy devices can include valves for delivering oxygen with the flow of gas, and / or humidification devices for delivering heated and humidified gas. Flow therapy devices can allow for adjustment and control of characteristics of the flow of gas, including flow rate, temperature, gas concentration, humidity, pressure, etc. Sensors such as heated temperature sensing elements and / or thermistors are used to measure these characteristics of the gas. SUMMARY

[0004] The present disclosure describes flow therapy devices that can be used to provide a flow of gas to a patient in a non-occlusive or occlusive system. The flow of breathing gas can be adjusted based on a detected patient respiratory cycle. The patient respiratory cycle can be determined using one or more measured parameters such as flow rate, blower motor speed, and / or system pressure. A periodic waveform that is adjusted to have a phase based on the phase of the patient respiratory cycle can be used to control the flow source such that the flow is adjusted in response to patient inhalation and exhalation.

[0005] Methods for respiratory therapy in a respiratory system are provided. The method can include driving a blower motor configured to produce a flow of air to a patient using a control signal. The method can further include detecting a respiratory cycle of the patient by receiving a first sensor input comprising one or more flow measurements from at least one flow sensor, receiving a second sensor input comprising one or more pressure measurements from at least one pressure sensor or a motor speed measurement associated with the blower motor, and generating a respiratory cycle waveform using at least the received flow measurements, wherein the respiratory cycle waveform can comprise a plurality of alternating inhalation and exhalation periods of the patient. The method can further include synchronizing the control signal with the respiratory cycle by identifying a phase of the respiratory cycle waveform and repeatedly updating a phase of the control signal to achieve a determined phase difference between the control signal and the respiratory cycle waveform such that the control signal can be configured to adjust a speed of the blower motor based on inhalation and exhalation of the patient. The method can further include phase shifting the control signal based on a system delay between the blower motor receiving the control signal and one or more flow measurements. The method can further include phase shifting the control signal such that the control signal can lead the respiratory cycle waveform by an amount of time. The at least one flow sensor can comprise an ultrasonic sensor assembly. The at least one flow sensor can further comprise a heated temperature sensing element. The control signal can be phase locked to the respiratory cycle waveform. An amplitude of the control signal can be determined based at least in part on an amplitude of the respiratory cycle waveform, a positive feedback parameter, and a negative feedback parameter. The second input sensor can be one or more motor speed measurements associated with the blower motor. The respiratory cycle waveform can be generated using the received flow and motor speed measurements. The respiratory cycle waveform can be generated based at least in part on a flow limit calculated using the received flow and motor speed measurements. The respiratory cycle waveform can be generated based at least in part on a calculated patient flow, wherein the patient flow can be based on a system leak calculated using the received flow and motor speed measurements. The motor speed measurements can be determined based at least in part on one or more blower motor parameters. The blower motor can comprise a brushless DC motor. Detecting the respiratory cycle of the patient can comprise receiving a third sensor input comprising one or more pressure measurements from at least one pressure sensor. The second input sensor can be one or more pressure measurements from at least one pressure sensor. The method for respiratory therapy can be performed in a high flow respiratory system. The method for respiratory therapy can be performed in a non-sealed respiratory system. The method for respiratory therapy can be performed in a sealed respiratory system. The method can further comprise adjusting the motor speed to achieve a predetermined pressure of the system based on one or more pressure measurements from at least one pressure sensor.The sealed respiratory system can include a non-invasive ventilation mask. The pressure sensor can be located in the non-invasive ventilation mask, or in a manifold connecting the non-invasive ventilation mask to a patient breathing conduit, or within the patient breathing conduit, or within a housing of the respiratory system. The system can have a memory for storing data. The stored data can include respiratory rate, treatment time, motor speed, flow rate, and / or pressure. The memory can be an EEPROM.

[0006] Respiratory therapy devices are provided. The devices can include a blower for generating a flow of air for a patient, the blower associated with a motor, where the motor can be configured to be driven by a control signal. The devices can further include one or more sensors configured to measure at least flow rate, the one or more sensors further configured to measure motor speed or pressure. The devices can further include a control system configured to detect a breathing cycle of the patient by receiving a first sensor input, the first sensor input including one or more flow measurements from at least one flow sensor; receiving a second sensor input, the second sensor input including one or more pressure measurements from at least one pressure sensor or a motor speed measurement associated with the blower motor; and generating a breathing cycle waveform using at least the received flow measurements, where the breathing cycle waveform can include a plurality of alternating inhalation and exhalation periods of the patient. The control system can be further configured to synchronize the control signal with the breathing cycle by identifying a phase of the breathing cycle waveform; and repeatedly updating a phase of the control signal to achieve a determined phase difference between the control signal and the breathing cycle waveform, such that the control signal can be configured to adjust a speed of the blower motor based on inhalation and exhalation of the patient. The control signal can be further configured to phase shift the control signal based on a system delay between the blower motor receiving the control signal and a sensed resulting air flow. The control signal can be further configured to phase shift the control signal such that the control signal can lead the breathing cycle waveform by a set amount of time. The at least one flow sensor can include an ultrasonic sensor assembly. The at least one flow sensor can further include a heated temperature sensing element. The control signal can be phase locked to the breathing cycle waveform. The breathing cycle waveform can be used to calculate a patient breathing rate. An amplitude of the control signal can be determined based at least in part on an amplitude of the breathing cycle waveform, a positive feedback parameter, and a negative feedback parameter. The second input sensor can be one or more motor speed measurements associated with the blower motor. The breathing cycle waveform can be generated using the received flow and motor speed measurements. The breathing cycle waveform can be generated based at least in part on a calculated patient flow, where the patient flow can be based on a system leak calculated using the received flow and motor speed measurements. The motor speed measurements can be determined based at least in part on one or more blower motor parameters. The blower motor can include a brushless DC motor. The control system can be configured to detect the breathing cycle by receiving a third sensor input, the third sensor input including one or more pressure measurements from at least one pressure sensor. The second input sensor can be one or more pressure measurements from at least one pressure sensor. The respiratory therapy device can be a respiratory high flow therapy device. The respiratory therapy device can be configured for use in a non- sealed respiratory system. The respiratory therapy device can be configured for use in a sealed respiratory system.A respiratory treatment device can be configured to adjust a motor speed to achieve a predetermined pressure of a sealed respiratory system based on one or more pressure measurements from a pressure sensor. The respiratory treatment device can be configured to couple with a non-invasive ventilation mask. The pressure sensor can be located in the non-invasive ventilation mask, or in a manifold connecting the non-invasive ventilation mask to a patient breathing conduit, or within the patient breathing conduit, or within a housing of the respiratory treatment device. The device can have a memory for storing data. The stored data can include respiratory rate, treatment time, motor speed, flow rate, and / or pressure. The memory can be an EEPROM.

[0007] A method for adjusting a flow rate of a respiratory system according to a patient's inhalation and exhalation. The method includes receiving, at a processor, a first input corresponding to a flow rate of an air flow generated by a source based at least in part on a control signal, receiving, at the processor, at least a second input, and determining, by the processor, a predicted respiratory cycle of the patient based at least in part on the first input and the second input. The method can further include adjusting the control signal based at least in part on an amplitude of the predicted respiratory cycle using a positive feedback parameter. The method can further include adjusting the control signal based at least in part on an amplitude of the predicted respiratory cycle using a negative feedback parameter. The method can further include adjusting the control signal of the source, wherein adjusting the control signal includes performing at least one phase-locked loop iteration on the control signal relative to the predicted respiratory cycle such that a phase of the control signal substantially matches a phase of the predicted respiratory cycle by a determined phase difference. The second input can correspond to a speed of a motor associated with the source. The method can further include receiving a third input including a pressure. The second input can correspond to the pressure. Adjusting the control signal can further include phase shifting the control signal relative to the predicted respiratory cycle. Adjusting the control signal can further include phase shifting the control signal relative to the predicted respiratory cycle based at least in part on a system delay. Adjusting the control signal can further include phase shifting the control signal relative to the predicted respiratory cycle by an amount specified by a lead prediction respiratory cycle waveform. The method can be used in a non-sealed or sealed respiratory system. The system can have a memory for storing data. The stored data can include respiratory rate, treatment time, motor speed, flow rate, and / or pressure. The memory can be an EEPROM.

[0008] Systems configured to adjust flow rate based on patient inspiration and expiration are provided. The system can include a source configured to generate a flow of air based at least in part on a control signal. The system can further include a processor configured to receive a first input corresponding to a flow rate of the flow of air, receive at least a second input, and determine a predicted respiratory cycle of the patient based at least in part on the first input and the second input. The processor can be further configured to adjust the control signal based at least in part on an amplitude of the predicted respiratory cycle using a positive feedback parameter. The processor can be further configured to adjust the control signal based at least in part on the amplitude of the predicted respiratory cycle using a negative feedback parameter. The processor can be further configured to adjust the control signal of the source, wherein adjusting the control signal can include performing at least one phase-locked loop iteration on the control signal relative to the predicted respiratory cycle such that a phase of the control signal can substantially match a phase of the predicted respiratory cycle by a determined phase difference. Adjusting the control signal can further include phase shifting the control signal relative to the predicted respiratory cycle. The control signal can be phase shifted relative to the predicted respiratory cycle based at least in part on a system delay. The control signal can be phase shifted relative to the predicted respiratory cycle to preempt a specified amount of the predicted respiratory cycle waveform. The processor can be further configured to calculate a respiratory rate of the patient based at least in part on the predicted respiratory cycle of the patient. The second input can correspond to a speed of a motor associated with the source. The processor can be further configured to receive a third input, the third input including a pressure. The second input sensor can correspond to the pressure. The system can include a high flow system. The system can be a non- sealed respiratory system. The system can be a sealed respiratory system. The respiratory treatment device is configured to adjust a motor speed to achieve a predetermined pressure of the system based on one or more pressure measurements from at least one pressure sensor. The system can include a non-invasive ventilation mask. The pressure sensor can be located in the non-invasive ventilation mask, or in a manifold connecting the non-invasive ventilation mask to a patient breathing conduit, or within the patient breathing conduit, or within a housing of the respiratory system. The system can have a memory for storing data. The stored data can include respiratory rate, treatment time, motor speed, flow rate, and / or pressure. The memory can be an EEPROM.

[0009] Methods for adjusting a control waveform of a respiratory assistance device are provided. The method can include detecting a respiratory cycle of a patient, synchronizing a control waveform to the detected respiratory cycle, and phase shifting the control waveform relative to the detected respiratory cycle. The control waveform can be phase shifted to have a determined phase difference relative to the respiratory cycle. Synchronizing the control waveform to the detected respiratory cycle can include using positive feedback to enhance the respiratory cycle. Synchronizing the control waveform to the detected respiratory cycle can include using negative feedback to modulate the respiratory cycle, where the negative feedback can be applied to the respiratory cycle when an amplitude of the respiratory cycle satisfies a threshold amount. The control waveform can be a phase-locked loop relative to the detected respiratory cycle. The phase-locked loop can cause an error between the control waveform and the detected respiratory cycle to gradually decrease each cycle. The control waveform can be phase shifted by an amount to compensate for a system delay associated with the respiratory assistance device. The control waveform can be phase shifted by an amount to anticipate the respiratory cycle. The respiratory assistance device can include at least one flow sensor. The at least one flow sensor can include an ultrasonic sensor assembly. Flow feedback can be received from the at least one flow sensor. The respiratory assistance device can include a blower. The blower can include a motor. Motor speed feedback can be received from the blower motor. The motor can be a brushless DC motor, which can be configured to provide sensorless feedback. The motor can be a low-inertia motor. The method can further include driving the blower motor using the phase-shifted control waveform. The respiratory assistance device can include a blower including a motor and at least one flow sensor, and the method can further include receiving feedback variables from the motor and the at least one flow sensor, where the received motor and flow sensor feedback variables can be calculated in combination to produce a respiratory cycle waveform. Motor speed feedback can be received from the blower motor. The feedback from the motor can include an indication of system pressure. The respiratory system can include a pressure sensor. The received pressure and flow sensor feedback variables can be calculated in combination to produce a respiratory cycle waveform. The received pressure, motor, and flow sensor feedback variables can be calculated in combination to produce a respiratory cycle waveform. The method for performing respiratory therapy can be performed in a high-flow respiratory system. The method for performing respiratory therapy can be performed in a non-sealed respiratory system. The method for performing respiratory therapy can be performed in a sealed respiratory system. The method can further include adjusting the motor speed based on pressure measurements of the pressure sensor to achieve a predetermined pressure of the system. The sealed respiratory system can include a non-invasive ventilation mask. The pressure sensor can be located in the non-invasive ventilation mask, or in a manifold connecting the non-invasive ventilation mask to a patient breathing conduit, or within the patient breathing conduit, or within a housing of the respiratory system. The system can have a memory for storing data. The stored data can include respiratory rate, therapy time, motor speed, flow rate, and / or pressure. The memory can be an EEPROM.

[0010] A respiratory assistance device configured to adjust flow rate according to patient inhalation and exhalation is provided. The device can include a blower including a motor. The device can further include at least one sensor to measure flow rate. The device can further include a processor configured to determine a predicted inhalation and exhalation cycle of the patient based on at least the flow rate and adjust the flow of respiratory gas according to the patient breathing. The at least one sensor can include a first ultrasonic transducer and a second ultrasonic transducer. The at least one sensor can include a heated temperature sensing element. The at least one sensor can include both a first ultrasonic transducer and a second ultrasonic transducer and a heated temperature sensing element. The flow of respiratory gas can be adjusted based at least in part on a bistable system using both positive feedback and negative feedback. The processor can determine the predicted inhalation and exhalation cycle based on the flow rate and a signal indicative of the blower motor speed, the motor configured to provide the signal indicative of the blower motor speed. The respiratory assistance device can further include a pressure sensor to measure pressure. The processor can determine the predicted inhalation and exhalation cycle based on the flow rate and the pressure. The processor can determine the predicted inhalation and exhalation cycle based on the flow rate, the motor speed, and the pressure. The respiratory assistance device can be a high flow respiratory assistance device. The respiratory therapy device can be configured for use in a non-sealed respiratory system. The respiratory therapy device can be configured for use in a sealed respiratory system. The respiratory therapy device can be configured to adjust the motor speed based on the pressure measured by the pressure sensor to achieve a predetermined pressure of the sealed respiratory system. The respiratory therapy device can be configured to couple with a non-invasive ventilation mask. The pressure sensor can be located in the non-invasive ventilation mask, or in a manifold connecting the non-invasive ventilation mask to a patient breathing conduit, or within the patient breathing conduit, or within a housing of the respiratory assistance device. The device can have a memory to store data. The stored data can include respiratory rate, treatment time, motor speed, flow rate, and / or pressure. The memory can be an EEPROM.

[0011] Systems configured to adjust flow rate based on patient inhalation and exhalation are provided. The systems can include a blower and a processor. The processor can be configured to receive a first input corresponding to a flow rate, and a second input. The processor can be further configured to determine a predicted inhalation and exhalation cycle of the patient based on the first input and the second input, and adjust the flow of respiratory gases according to the predicted inhalation and exhalation cycle of the patient. The flow rate can be determined using a first ultrasonic transducer and a second ultrasonic transducer. The flow rate can be determined using a heated temperature sensing element. The flow rate can be determined using a first ultrasonic transducer and a second ultrasonic transducer in combination with a heated temperature sensing element. The flow of respiratory gases can be adjusted based at least in part on a bistable system using both positive feedback and negative feedback. The second input can be a motor speed feedback device configured to provide a signal indicative of the blower motor speed. The processor can be further configured to receive a third input, the third input comprising a pressure. The second input can be a pressure from a pressure sensor. The system can be a high flow system. The respiratory therapy device can be configured for use in a non- sealed respiratory system. The respiratory therapy device can be configured for use in a sealed respiratory system. The respiratory therapy device can be configured to adjust the motor speed based on the pressure from the pressure sensor to achieve a predetermined pressure for a sealed respiratory system. The respiratory therapy device can be configured to couple with a non-invasive ventilation mask. The pressure sensor can be located in the non-invasive ventilation mask, or in a manifold connecting the non-invasive ventilation mask to a patient breathing conduit, or within the patient breathing conduit, or within a housing of the respiratory therapy device. The second input can be a pressure in addition to motor feedback. The system can have a memory for storing data. The stored data can include respiratory rate, treatment time, motor speed, flow rate, and / or pressure. The memory can be an EEPROM.

[0012] A respiratory system configured to determine a respiratory rate of a patient is provided. The system can further include at least one sensor configured to measure a flow rate, a processor configured to be in electrical communication with the at least one sensor to receive flow rate measurements of the patient using the respiratory system, the processor further configured to determine a respiratory rate of the patient by autocorrelating a plot of the flow rate measurements versus time. The processor can be configured to determine a respiratory cycle from one or more peaks or zero crossings of the autocorrelation of the plot of the flow rate measurements versus time. The at least one sensor can include a first ultrasonic transducer and a second ultrasonic transducer. The at least one sensor can include a heated temperature sensing element. The at least one sensor can include both the first ultrasonic transducer and the second ultrasonic transducer and the heated temperature sensing element. The processor can be configured to generate a respiratory cycle waveform based at least in part on the determined respiratory rate, where the respiratory cycle waveform can include a plurality of alternating inhalation and exhalation cycles of the patient. The system can further include a blower for generating a flow of air for the patient, the blower associated with a motor, where the motor can be configured to be driven by a control signal. The blower motor can include a brushless DC motor. The processor can be configured to synchronize the control signal with the respiratory cycle by identifying a phase of the respiratory cycle waveform and repeatedly updating a phase of the control signal to achieve a determined phase difference between the control signal and the respiratory cycle waveform such that the control signal can be configured to adjust a speed of the blower motor based on inhalation and exhalation of the patient. The processor can be further configured to phase shift the control signal based on a system delay between the blower motor receiving the control signal and a sensed flow of air. The processor can be further configured to phase shift the control signal such that the control signal can lead the respiratory cycle waveform by an amount of time. The processor can be configured to generate the respiratory cycle waveform based on flow rate measurements and motor speed measurements associated with the blower motor. The motor speed measurements can be determined based at least in part on one or more blower motor parameters. Generating the respiratory cycle waveform can be based on the flow rate measurements and one or more pressure measurements from a pressure sensor. Generating the respiratory cycle waveform can be based on the flow rate measurements, the motor speed measurements, and one or more pressure measurements from a pressure sensor. The respiratory system can include a respiratory high flow therapy device. The respiratory system can be a non-sealed respiratory system. The respiratory system can be a sealed respiratory system. The processor can be configured to adjust the motor speed based on one or more pressure measurements from a pressure sensor to achieve a predetermined pressure of the system. The respiratory system can include a non-invasive ventilation mask. The pressure sensor can be located in the non-invasive ventilation mask, or in a manifold connecting the non-invasive ventilation mask to a patient breathing conduit, or within the patient breathing conduit, or within a housing of the respiratory system. The system can have a memory for storing data. The stored data can include respiratory rate, treatment time, motor speed, flow rate, and / or pressure.The memory can be an EEPROM.

[0013] Methods for determining a patient's respiratory rate using a respiratory system are provided. The method can include receiving, from at least one sensor, flow rate measurements of a patient obtained using a respiratory system; autocorrelating a plot of the flow rate measurements versus time; and determining a respiratory rate of the patient from the autocorrelation. Determining the respiratory rate of the patient can further include determining a respiratory cycle of the patient from one or more peaks or zero crossings in the autocorrelation. The flow rate measurements can be made by a first ultrasonic transducer and a second ultrasonic transducer. The flow rate measurements can be made by a heated temperature sensing element. The flow rate measurements can be made by both the first and second ultrasonic transducers and the heated temperature sensing element. The method can further include generating a respiratory cycle waveform based at least in part on the determined respiratory rate, where the respiratory cycle waveform can include a plurality of alternating inhalation and exhalation periods of the patient. The respiratory system can include a blower for generating a flow of air to the patient, the blower being associated with a motor, where the motor is configurable to be driven by a control signal. The blower motor includes a brushless DC motor. The method can further include synchronizing the control signal with the respiratory cycle by identifying a phase of the respiratory cycle waveform and iteratively updating a phase of the control signal to achieve a determined phase difference between the control signal and the respiratory cycle waveform, such that the control signal can be configured to adjust a speed of the blower motor based on inhalation and exhalation of the patient. The synchronizing can further include phase shifting the control signal based on a system delay between the blower motor receiving the control signal and the patient sensing the resulting flow of air. The synchronizing can further include phase shifting the control signal such that the control signal can lead the respiratory cycle waveform by an amount of time. The method can further include generating the respiratory cycle waveform based on the determined respiratory rate and a motor speed measurement associated with the blower motor. The method can further include determining the motor speed measurement based on one or more blower motor parameters. Generating the respiratory cycle waveform can be based on the determined respiratory rate and one or more pressure measurements from a pressure sensor. Generating the respiratory cycle waveform can be based on the determined respiratory rate, one or more blower motor parameters, and one or more pressure measurements from a pressure sensor. The respiratory system can include a respiratory high flow therapy device. The respiratory system can be a non-sealed respiratory system. The respiratory system can be a sealed respiratory system. The processor can be configured to adjust the motor speed based on the pressure measurements from the pressure sensor to achieve a predetermined pressure of the system. The respiratory system can include a non-invasive ventilation mask. The pressure sensor can be located in the non-invasive ventilation mask, or in a manifold connecting the non-invasive ventilation mask to a patient breathing conduit, or within the patient breathing conduit, or within a housing of the respiratory system. The system can have a memory for storing data. The stored data can include respiratory rate, treatment time, motor speed, flow rate, and / or pressure. The memory can be an EEPROM.

[0014] A respiratory therapy device is provided. The respiratory therapy device can include: a blower to generate a flow of air for a patient, the blower associated with a motor, wherein the motor is configurable to be driven by a control signal; one or more sensors configurable to measure at least a flow rate; and a control system configurable to: detect a respiratory cycle of the patient by: receiving one or more flow measurements from the one or more sensors; and generating a respiratory cycle waveform using at least the received flow, wherein the respiratory cycle waveform can include a plurality of alternating inhalation and exhalation periods of the patient; and identifying a phase difference between the control signal and the respiratory cycle waveform from a cross-correlation of the control signal and the respiratory cycle waveform. The control system can be configurable to determine / measure the phase difference from one or more peaks or zero-crossings of the cross-correlation of the control signal and the respiratory cycle waveform. The control system can be configurable to synchronize the control signal with the respiratory cycle by: repeatedly updating a phase of the control signal to achieve a determined phase difference between the control signal and the respiratory cycle waveform based on the identified phase difference, such that the control signal can be configurable to adjust a speed of the blower motor based on inhalation and exhalation of the patient. The control signal can be further configurable to phase shift the control signal based on a system delay between the blower motor receiving the control signal and the patient sensing the resulting flow of air. The control system can be further configurable to phase shift the control signal such that the control signal can lead the respiratory cycle waveform by an amount of time. The one or more sensors can include an ultrasonic sensor assembly. The one or more sensors can further include a heated temperature sensing element. The control signal can be phase-locked to the respiratory cycle waveform. The respiratory cycle waveform can be used to calculate a patient respiratory rate. The patient respiratory rate can be calculated from an autocorrelation of the flow rate measurements over time. The patient respiratory cycle can be determined from one or more peaks or zero-crossings in the autocorrelation. An amplitude of the control signal can be determined based at least in part on an amplitude of the respiratory cycle waveform, a positive feedback parameter, and a negative feedback parameter. The respiratory cycle waveform can be generated based on the received flow and a motor speed measurement associated with the blower motor. The respiratory cycle waveform can be generated based at least in part on a calculated patient flow, wherein the patient flow is calculated based on using the received flow and the motor speed measurement associated with the blower motor. The motor speed measurement can be determined based at least in part on one or more blower motor parameters. The blower motor can include a brushless DC motor. The control system can be configurable to generate the respiratory cycle waveform based on the received flow and one or more pressure measurements from a pressure sensor. The control system can be configurable to generate the respiratory cycle waveform based on the received flow, the motor speed measurement associated with the blower motor, and one or more pressure measurements from a pressure sensor. The respiratory therapy device can be a respiratory high flow therapy device. The respiratory therapy device can be configurable for use in a non-sealed respiratory system. The respiratory therapy device can be configurable for use in a sealed respiratory system.The respiratory treatment device can be configured to adjust the motor speed based on pressure measurements from the pressure sensor to achieve a predetermined pressure of the sealed respiratory system. The respiratory treatment device can be configured to couple with a non-invasive ventilation mask. The pressure sensor can be located in the non-invasive ventilation mask, or in a manifold connecting the non-invasive ventilation mask to a patient breathing conduit, or within the patient breathing conduit, or within a housing of the respiratory treatment device. The system can have a memory for storing data. The stored data can include respiratory rate, treatment time, motor speed, flow rate, and / or pressure. The memory can be an EEPROM.

[0015] Methods for performing respiratory therapy in a respiratory system are disclosed. The methods can include driving a blower motor configured to generate a flow of air to a patient using a control signal, detecting a respiratory cycle of the patient by receiving one or more flow measurements from at least one flow sensor, and generating a respiratory cycle waveform using the received flow, where the respiratory cycle waveform can include a plurality of alternating inhalation and exhalation periods of the patient, and identifying a phase difference between the control signal and the respiratory cycle waveform from a cross-correlation of the control signal and the respiratory cycle waveform. The identifying can further include determining the phase difference from one or more peaks or zero-crossings of the cross-correlation of the control signal and the respiratory cycle waveform. The methods can further include synchronizing the control signal to the respiratory cycle by repeatedly updating a phase of the control signal to achieve a determined phase difference between the control signal and the respiratory cycle waveform based on the identified phase difference, such that the control signal can be configured to adjust a speed of the blower motor based on inhalation and exhalation of the patient. The synchronizing can further include phase shifting the control signal based on a system delay between the blower motor receiving the control signal and the patient sensing the resulting flow of air. The synchronizing can further include phase shifting the control signal such that the control signal can lead the respiratory cycle waveform by an amount of time. The at least one flow sensor can include an ultrasonic sensor assembly. The at least one flow sensor can include a heated temperature sensing element. The methods can further include phase locking the control signal to the respiratory cycle waveform. The respiratory cycle waveform can be used to calculate a respiratory rate of the patient. The detecting can further include calculating the respiratory rate of the patient from an autocorrelation of the flow rate measurements over time. The respiratory cycle of the patient can be determined from one or more peaks or zero-crossings in the autocorrelation. An amplitude of the control signal can be determined based at least in part on an amplitude of the respiratory cycle waveform, a positive feedback parameter, and a negative feedback parameter. The respiratory cycle waveform can be generated based on the received one or more flow measurements and a motor speed measurement associated with the blower motor. The respiratory cycle waveform can be generated based at least in part on a flow limitation calculated using the received flow and the motor speed measurement associated with the blower motor. The respiratory cycle waveform can be generated based at least in part on a calculated patient flow, where the patient flow can be based on a system leak calculated using the received flow and the motor speed measurement. The motor speed measurement can be determined based at least in part on one or more blower motor parameters. The blower motor can include a brushless DC motor. The respiratory cycle waveform can be generated based on the received flow and one or more pressure measurements from a pressure sensor. The respiratory cycle waveform can be generated based on the one or more flow measurements, a motor speed measurement associated with the blower motor, and one or more pressure measurements from a pressure sensor. The methods can be performed in a high flow respiratory system. The methods can be performed in a non-sealed respiratory system. The methods for performing respiratory therapy can be performed in a sealed respiratory system.The method can further include adjusting the motor speed to achieve a predetermined pressure of the system based on the pressure measurement from the pressure sensor. The sealed respiratory system can include a non-invasive ventilation mask. The pressure sensor can be located in the non-invasive ventilation mask, or in a manifold connecting the non-invasive ventilation mask to a patient breathing conduit, or within the patient breathing conduit, or within a housing of the respiratory system. The system can have a memory for storing data. The stored data can include respiratory rate, treatment time, motor speed, flow rate, and / or pressure. The memory can be an EEPROM. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 An example respiratory assist device in the form of a flow therapy device is shown in diagrammatic form.

[0017] Figure 2A An example block diagram of a control system that interacts with and / or provides control and guidance to components of a respiratory assist system is shown.

[0018] Figure 2B An example block diagram of a control system that interacts with and / or provides control and guidance to components of a respiratory assist system is shown.

[0019] Figure 2C A block diagram of an example controller is shown.

[0020] Figure 3 A block diagram of an example motor / sensor module is shown.

[0021] Figure 4 A flow diagram of an example process for adjusting operation of a flow therapy device is shown

[0022] Figure 5 A flow diagram of an example process for determining flow rate is shown.

[0023] Figure 6A A block diagram of an example system for performing breath cycle augmentation for a flow therapy device is shown.

[0024] Figure 6B A block diagram of an example system for implementing a phase-locked control loop for a flow therapy device is shown.

[0025] Figure 7 A flow diagram of an example process for assisting a patient's breathing cycle is shown.

[0026] Figure 8 An example chart of a patient's breathing cycle waveform and a control signal waveform is shown.

[0027] Figure 9A flowchart showing an example process for implementing a control signal for a blower motor as a phase-locked loop with a sensed patient respiratory cycle.

[0028] Figure 10 A flowchart showing an example process for phase shifting a control signal to compensate for system delay.

[0029] Figure 11 A chart showing updating a control signal to compensate for system delay.

[0030] Figure 12 A flowchart showing an example process for configuring a phase-shifted control signal to anticipate a patient's respiratory cycle waveform.

[0031] Figure 13 An example chart showing a patient respiratory cycle and a phase-shifted control loop.

[0032] Figure 14A An example chart showing raw flow rate readings of a patient measured by a system.

[0033] Figure 14B An example chart showing an autocorrelation of Figure 14A raw flow rate readings. DETAILED DESCRIPTION

[0034] Figure 1 A flow therapy device 10 is shown in FIG. 1. In general, the device 10 can include a main housing 100 containing a flow generator 11 in the form of a motor / impeller arrangement, an optional humidifier 12, a controller 13, and a user interface 14 (e.g., including a display and input devices such as buttons, a touchscreen, etc.). The controller 13 is configured or programmed to control components of the device, including: operating the flow generator 11 to generate a flow of gas for delivery to a patient; operating the humidifier 12 (if present) to humidify and / or heat the generated flow of gas; receiving user inputs from the user interface 14 for reconfiguration and / or user-defined operation of the device 10; and outputting information to the user (e.g., on the display). The user can be the patient, a healthcare professional, or any other person interested in using the device.

[0035] The patient breathing conduit 16 is coupled to the gas flow output 21 in the housing 100 of the flow therapy apparatus 10 and to the patient interface 17, such as a nasal cannula with a manifold 19 and nasal prongs 18. Additionally or alternatively, the patient breathing conduit 16 can be coupled to a face mask. A flow of gas, which can be humidified, is generated by the flow therapy apparatus 10 and delivered to the patient via the patient conduit 16 through the cannula 17. The patient conduit 16 can have a heater wire 16a for heating the flow of gas to the patient. The heater wire 16a is under the control of the controller 13. The patient conduit 16 and / or the patient interface 17 can be considered part of the flow therapy apparatus 10, or alternatively peripheral thereto. The flow therapy apparatus 10, breathing conduit 16, and patient interface 17 together form a flow therapy system.

[0036] The general operation of the flow therapy breathing apparatus 10 will now be described. The controller 13 can control the flow generator 11 to generate a desired flow rate of gas flow, control one or more valves to control the gas mixture (e.g., 02 control), and / or control the humidifier 12 (if present) to humidify and / or heat the gas flow to an appropriate level. The gas flow is directed to the patient through the patient conduit 16 and cannula 17. The controller 13 can also control heating elements in the humidifier 12 and / or heating elements 16a in the patient conduit 16 to heat the gas to a desired temperature to achieve a desired level of therapy and / or patient comfort. The controller 13 can be programmed with or can determine a suitable target temperature for the gas flow.

[0037] Operation sensors 3a, 3b, 3c, such as flow sensors, temperature sensors, humidity sensors, and / or pressure sensors, can be placed at various locations in the flow therapy apparatus 10. Additional sensors (e.g., sensors 20, 25) can be placed at different locations on the patient conduit 16 and / or cannula 17 (e.g., there can be a temperature sensor at or near the end of the inspiratory tube). The output from the sensors can be received by the controller 13 to assist the controller in operating the flow therapy apparatus 10 in a manner that provides suitable therapy. Providing suitable therapy can include meeting the inspiratory needs of the patient. The apparatus 10 can have a transmitter and / or receiver 15 to enable the controller 13 to receive signals 8 from the sensors and / or to control different components of the flow therapy apparatus 10, including but not limited to the flow generator 11, the humidifier 12, and the heater wire 16a, or accessories or peripherals associated with the flow therapy apparatus 10. The apparatus 10 can have a memory for storing data such as respiratory rate, therapy time, motor speed, flow rate, pressure, etc. The memory can be, for example, an EEPROM. Additionally or alternatively, the transmitter and / or receiver 15 can deliver data to a remote server or enable remote control of the apparatus 10.

[0038] The flow therapy apparatus 10 can comprise a high flow therapy apparatus. As used herein, "high flow" therapy can involve the administration of gas to a patient's airway at a relatively high flow rate, e.g., at least 15 L / min, or 20 L / min, or 25 L / min, or 30 L / min, or 40 L / min, or 50 L / min, or up to 150 L / min for an adult. For children and infants, the flow rate can be 1 L / min and up to 25 L / min, or 2 L / min, or 3 L / min, or 5 L / min, or 10 L / min, or 15 L / min, or 20 L / min. High flow therapy can be administered to a user's nares and / or through the mouth, or via a tracheostomy interface. High flow therapy can deliver gas to a user at a flow rate equal to or in excess of the user's peak inspiratory flow requirement. High flow gas to the patient's airway can advantageously flush the patient's airway, which can reduce the volume of the anatomic dead space. High flow therapy is typically delivered through a non-sealing patient interface, such as a nasal cannula. The nasal cannula can be configured to deliver breathing gas to the user's nares at a flow rate in excess of the user's peak inspiratory flow requirement.

[0039] The term "non-sealing patient interface" as used herein can refer to an interface that provides a pneumatic connection between a patient's airway and a source of positive gas flow, such as from the flow generator 11, and does not completely occlude the patient's airway. The non-sealing pneumatic connection can include less than 95% occlusion of the patient's airway. The non-sealing pneumatic connection can include less than 90% occlusion of the patient's airway. The non-sealing pneumatic connection can include between 40% and 80% occlusion of the patient's airway. The airway can be one or more of the patient's nares or mouth.

[0040] The systems described herein can also be used with a sealing patient interface. Non-limiting examples of sealing patient interfaces can include non-invasive ventilation (NIV) full-face and nasal masks. NIV masks can support a patient's breathing without the need for intubation or tracheostomy. NIV masks can have a patient interface that conforms to the patient's face to provide a sealed fit between the mask and the patient's face.

[0041] Additional details of example flow therapy apparatus are disclosed in U.S. Provisional Application Serial No. 62 / 262,325, filed December 2, 2015, entitled "Flow Path Sensing for Flow Therapy Apparatus," which is incorporated herein by reference in its entirety.

[0042] Control system

[0043] Figure 2AA block diagram 200 of an example control system 220 is shown, which can detect patient conditions and control operation of a flow therapy device including a gas source. The control system 220 can manage the flow rate of gas flowing through the flow therapy device as it is delivered to the patient. For example, the control system 220 can increase or decrease the flow rate by controlling the output 230 of a motor speed of a blower (hereinafter also referred to as a “blower motor”) or the output 232 of a valve in a blender. As described below, the control system 220 can automatically determine a set or personalized value of the flow rate for a particular patient. The flow rate can be optimized by the control system 220 to improve patient comfort and therapy.

[0044] The control system 220 can also generate audio and / or display / visual outputs 238, 239. For example, the flow therapy device can include a display 308 and / or a speaker. The display 308 can indicate any warnings or alarms generated by the control system 220 to a physician. The display 308 can also indicate control parameters that can be adjusted by the physician. For example, the control system 220 can automatically recommend a flow rate for a particular patient. The control system 220 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.

[0045] The control system 220 can vary a heater control output to control one or more of the heating elements (e.g., to maintain a temperature set point of the gas delivered to the patient). The control system 220 can also vary the operation or duty cycle of the heating elements. The heater control output can include a heater plate control output 234 and a heated breathing tube control output 236.

[0046] The control system 220 can determine the outputs 230-239 based on one or more received inputs 201-216. The inputs 201-216 can correspond to sensor measurements automatically received by the controller 300 (as shown, for example, in FIG. 3). The control system 220 can receive sensor inputs including, but not limited to, temperature sensor inputs 201, flow rate sensor inputs 202, motor speed inputs 203, sensor inputs 204, gas fraction sensor inputs 205, humidity sensor inputs 206, pulse oximeter (e.g., Sp02) sensor inputs 207, stored or user parameters 208, duty cycle or pulse width modulation (PWM) inputs 209, voltage inputs 210, current inputs 211, acoustic sensor inputs 212, power inputs 213, resistance inputs 214, C02sensor inputs 215, and / or spirometer inputs 216. The control system 220 can receive inputs from user parameter values or stored parameter values in the memory 304 (as shown, for example, in FIG. 3). Figure 2B The control system 220 can determine the outputs 230-239 based on one or more received inputs 201-216. The inputs 201-216 can correspond to sensor measurements automatically received by the controller 300 (as shown, for example, in FIG. 3). The control system 220 can receive sensor inputs including, but not limited to, temperature sensor inputs 201, flow rate sensor inputs 202, motor speed inputs 203, sensor inputs 204, gas fraction sensor inputs 205, humidity sensor inputs 206, pulse oximeter (e.g., Sp02) sensor inputs 207, stored or user parameters 208, duty cycle or pulse width modulation (PWM) inputs 209, voltage inputs 210, current inputs 211, acoustic sensor inputs 212, power inputs 213, resistance inputs 214, C02sensor inputs 215, and / or spirometer inputs 216. The control system 220 can receive inputs from user parameter values or stored parameter values in the memory 304 (as shown, for example, in FIG. 3). Figure 2B(As shown). The control system 220 can dynamically adjust the patient's flow rate during treatment. The control system 220 can continuously monitor system parameters and patient parameters. Based on the disclosure herein, those skilled in the art will understand that any other suitable inputs and / or outputs can be used with the control system 220.

[0047] like Figure 2B As shown, the control system 220 can receive inputs from multiple components of the flow therapy device, such as chest-abdominal dysregulation (TAA) sensor input 202, respiratory sensor input 204, work of breathing (WOB) sensor input 206, CO2 and / or pressure sensor input 208, user input and / or stored values ​​210. Not necessarily. Figure 2A All inputs 202-210 shown may exist. Figure 2B The control system 220 can output heater control output 230, flow control output 232, and display / audio output 234 based on inputs 202-210. Inputs 202-210 and outputs 230-234 may not be necessary. For example, the control system 220 may only receive EMG input 206 and generate flow control measurement value 232. Depending on the configuration, some components corresponding to the inputs may not be included in the flow therapy device. The control system 220 can use the absence of the input itself to determine input conditions or system conditions.

[0048] Controller

[0049] The control system 220 may include programming instructions for detecting input conditions and controlling output conditions. These programming instructions may be stored in the memory 304 of the controller 300, such as... Figure 2B As shown. Programming instructions may correspond to the methods, processes, and functions described herein. Control system 220 may be executed by one or more hardware processors 302 of controller 300. Programming instructions may be implemented in C, C++, JAVA, or any other suitable programming language. Some or all parts of control system 220 may be implemented in dedicated circuitry 306 such as ASICs and FPGAs.

[0050] Figure 2C A block diagram of an example controller 300 is shown. The controller may include a hardware processor 302 capable of executing instructions stored in memory 304. The control system 220 may be stored as programming instructions in memory 304. The controller may also include circuitry 306 for receiving sensor signals. The controller may further include a display 308 for transmitting the status of the patient and the respiratory support system. The display 308 may also display warnings. The controller may also receive user input via a user interface such as the display 308. The user interface may alternatively or additionally include buttons or a dial.

[0051] Motor / sensor module

[0052] Figure 3 A block diagram of a motor / sensor module 2000 that can be used as part of a flow therapy device is shown. The motor / sensor module includes a blower 2001 that entrains room air for delivery to a patient. The blower 2001 can be a centrifugal blower.

[0053] Room air enters a room air inlet 2002 that enters the blower 2001 through an inlet port 2003. The inlet port 2003 can include a valve 2004 through which pressurized gas can enter the blower 2001. The valve 2004 can control the flow of oxygen into the blower 2001. The valve 2004 can be any type of valve, including a proportional valve or a binary valve. The inlet port can not include a valve.

[0054] The blower 2001 can operate at a motor speed greater than 1,000 RPM and less than 30,000 RPM, greater than 2,000 RPM and less than 25,000 RPM, greater than 20,000 RPM and less than 24,000 RPM, or between any of the foregoing values. Operation of the blower 2001 mixes the gas entering the blower 2001 through the inlet port 2003. Using the blower 2001 as a mixer can reduce the pressure drop that would otherwise occur in a system with a separate mixer, such as a static mixer including baffles, because mixing requires energy and the blower imparts energy.

[0055] The mixed air exits the blower 2001 through a conduit 2005 and enters a flow path 2006 in a measurement chamber 2007. A circuit board with sensors 2008 is positioned in the measurement chamber 2007 such that the circuit board is immersed in the gas flow. The sensors 2008 on the circuit board are positioned within the gas flow to measure gas properties within the flow. After passing through the flow path 2006 in the measurement chamber 2007, the gas exits 2009 into a liquid chamber 300.

[0056] Positioning sensor 2008 downstream of the combined blower and mixer 2001 improves the accuracy of measurements (such as measurements of gas fractional concentration, including oxygen concentration) compared to systems that position the sensor upstream of the blower and / or mixer. Such positioning provides repeatable flow profiles. Furthermore, positioning the sensor downstream of the combined blower and mixer avoids pressure drops that would otherwise occur, as a separate mixer, such as a static mixer with baffles, is required between the inlet and the sensing system in cases where sensing occurs before the blower. The mixer introduces a pressure drop. Positioning the sensor after the blower allows the blower to act as the mixer, whereas a static mixer would reduce pressure, whereas the blower would increase pressure. Additionally, immersing the circuit board and sensor 2008 in the flow path improves measurement accuracy, as the sensors being submerged in the flow means they are more likely to be at the same temperature as the gas flow and therefore better represent the gas characteristics.

[0057] Measurement chamber

[0058] like Figure 3 As shown, the measuring chamber 2007 can be positioned downstream of the blower 2001 within the motor / sensor module 2000. The measuring chamber 2007 includes a flow path 2006 and is designed to hold a circuit board and one or more sensors 2008.

[0059] Gas flow may experience pressure drops during its passage through a flow therapy device, which consumes energy and can consequently affect the system's ability to achieve a specific flow rate. Pressure losses may be due to friction in the straight sections of the flow path or due to deviations from the straight path (such as bends, valves, contractions, or expansions in the path).

[0060] Flow path 2006 has a curved shape. The gas flow enters at inlet 2103, flows along the curved flow path 2104, and exits on the opposite side of flow path 2105. The inlet and outlet can be positioned in vertically opposite directions, and the gas flow can enter the path vertically upwards, then curve horizontally, and then curve vertically upwards again. The flow path may not have sharp turns. The flow path can have curved ends and a relatively straight middle section. The flow path can maintain a constant cross-sectional shape throughout its entire length. The flow path can taper slightly inwards from a first end and widen again to a second end, which can accelerate 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. The curved flow path shape can reduce the pressure drop of the gas flow without reducing the sensitivity of the flow measurement by aligning the measurement area with a portion of the flow path. Many different flow path configurations can be used. Other examples of possible flow path configurations are disclosed in U.S. Provisional Application Serial No. 62 / 262,325 cited in this article.

[0061] Adjusting flow based on respiratory cycle

[0062] To better assist a patient's breathing, it may be beneficial to be able to adjust the operation of the flow therapy device based on the patient's respiratory cycle. For example, the flow rate of air supplied by the flow therapy device can be adjusted with the patient's inhalation and exhalation. The flow rate can be adjusted based on the patient's inhalation or exhalation. For example, the flow rate can be increased during the patient's inhalation and decreased during the patient's exhalation. The flow rate can be adjusted during the patient's inhalation (e.g., increased during inhalation) and not adjusted during the patient's exhalation, and vice versa. Inhalation and exhalation can also be referred to as inhalation and exhalation.

[0063] A patient's respiratory cycle can be represented as a waveform comprising alternating expiratory and inspiratory phases. By identifying and monitoring the patient's respiratory cycle waveform, the operation of a flow therapy device can be modified based on the patient's respiratory cycle. For example, the flow therapy device can be configured to use a periodic waveform to control gas flow, which can be adjusted based on the patient's measured respiratory cycle waveform.

[0064] Figure 4 A flowchart illustrating an example process for adjusting the operation of a flow therapy device is provided. At box 402, a control signal is used to drive the blower motor associated with the flow therapy device (e.g., as shown in the diagram). Figure 1 The flow generator 11 shown or Figure 3The blower 2001) is shown. A blower motor can be used to generate a flow of air to assist with the patient's breathing. The control signal can include an initial waveform. The initial waveform can include a default waveform, or can be based on one or more measurements associated with the patient.

[0065] At block 404, a plurality of measurements that can be used to determine a respiratory cycle of the patient are received. These measurements can include a flow rate 404a, a motor speed 404b, a pressure 404c, and the like. Each of these types of measurements will be described in more detail below.

[0066] At block 406, the received measurements are used to determine a predicted respiratory cycle of the patient. The predicted respiratory cycle of the patient can be determined using one or more different techniques, such as a flow deviation 406a, a flow limitation 406b, a system leak 406c, and the like. Each of these different techniques will be described in more detail below.

[0067] At block 408, the control signal to the blower motor is adjusted based on the predicted respiratory cycle. For example, the control signal can be adjusted so that the flow rate is increased when the patient is inhaling, and decreased when the patient is exhaling. The control signal can be configured to have a phase-locked loop with the predicted respiratory cycle. Each of these implementations will be described in more detail below.

[0068] The process can then return to block 402, where the adjusted control signal is used to drive the blower motor to generate a flow of air for the patient.

[0069] Measuring system parameters

[0070] As discussed, the respiratory cycle of the patient can be determined based at least in part on a plurality of different measurements, such as a measured flow, a measured motor speed, a measured pressure, or a combination thereof.

[0071] a) Flow

[0072] Flow refers to the flow of gas through the system (e.g., from the blower motor or other flow generator to the patient). A flow rate can be measured using one or more flow sensors. For example, a flow rate can be measured using a heated temperature sensing element. The heated temperature sensing element can include a heated temperature sensing element, a hot wire anemometer, such as a platinum wire or a heated thermistor, and / or a negative temperature coefficient (NTC) thermistor. Other non-limiting examples of heated temperature sensing elements include glass or epoxy encapsulated or unencapsulated thermistors. The heated temperature sensing element is configured to measure a flow rate of a gas.

[0073] Flow rate can be measured using fast-response-time flow sensors, such as ultrasonic sensor assemblies comprising a first ultrasonic transducer and a second ultrasonic transducer. One or more sensors can be located along the flow path (such as...). Figure 3 The flow path shown is located near the flow path. U.S. Provisional Application Serial No. 62 / 262,325, cited herein, discloses an example of using an ultrasonic transducer to measure flow rate along a portion of a flow path. Specifically, a first ultrasonic transducer may be located downstream of the flow path in the aforementioned measurement chamber, and a second ultrasonic transducer may be located upstream of the flow path in the aforementioned measurement chamber. The first and second ultrasonic transducers may each emit and receive ultrasonic signals from each other. A controller of the breathing device may determine one or more characteristics of the gas flow, including but not limited to flow rate, based on time-of-flight measurements between the first and second ultrasonic transducers. Flow rate may also be measured using one or more ultrasonic transmitters and one or more ultrasonic receivers (such as microphones). One or more ultrasonic transmitters may emit ultrasonic signals along an acoustic path. One or more ultrasonic receivers may be located and receive ultrasonic signals along an acoustic path. A controller of the breathing device may determine one or more characteristics of the gas flow, including but not limited to flow rate, based on time-of-flight measurements between one or more ultrasonic transmitters and ultrasonic receivers.

[0074] Because the system's flow rate can fluctuate with a patient's inspiration and expiration, it is important to be able to measure the flow rate quickly and accurately. A combination of two or more different sensors can be used to measure the flow rate. For example, a first-type sensor may be able to measure the flow rate with better short-term or local accuracy (e.g., detecting rapid respiratory changes in flow rate) but may have poorer long-term accuracy (e.g., due to the accumulation of small errors), while a second-type sensor may be able to measure the flow rate with poorer local accuracy (e.g., due to local noise) but better average accuracy. The output readings from both the first-type and second-type sensors can be combined to determine a more accurate flow measurement. For example, a previously determined flow rate and one or more outputs from the second-type 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 first-type sensor to calculate the final flow rate. The first-type sensor may include an ultrasonic sensor assembly, while the second-type sensor may include a heated temperature sensing element.

[0075] Figure 5A flowchart illustrating an example process for determining flow rate is shown. At block 502, a first flow rate measurement is received from a first flow sensor, such as a heated temperature sensing element sensor. At block 504, a second flow rate measurement is received from an ultrasonic sensor assembly, as described above.

[0076] At block 506, a current flow prediction is determined based on the second flow rate measurement and previous flow rate measurements. At block 508, the flow rate is determined using the current flow prediction and the first flow rate measurement. By utilizing both a heated temperature sensing element sensor and an ultrasonic transducer, the disadvantages of both types of sensors can be mitigated, allowing for fast and accurate measurement of flow rate.

[0077] Measurements from different types of sensors can be combined in different ways. For example, measurements from one or more ultrasonic transducers can be read directly, while heated temperature sensing element measurements are filtered to provide a basis correction to ultrasonic flow calculations (e.g., by using a heated temperature sensing element, which has better long-term accuracy, to correct measurements of an ultrasonic transducer, which exhibits faster response times).

[0078] b) Motor speed

[0079] One or more sensors, such as a Hall effect sensor, can be used to measure a motor speed of a blower motor. The blower motor can include a brushless DC motor from which motor speed can be measured without the use of a separate sensor. For example, during operation of the brushless DC motor, a back electromotive force can be measured from a non-energized winding of the motor, from which motor position can be determined, which in turn can be used to calculate motor speed. Additionally, motor current can be measured using a motor driver, which can be used along with the measured motor speed to calculate motor torque. The blower motor can include a low-inertia motor.

[0080] c) Pressure

[0081] One or more pressure sensors can be used to determine system pressure. The one or more pressure sensors can be one or more gauge pressure sensors or one or more absolute pressure sensors. The one or more pressure sensors can be at any location in the system, but at least one pressure sensor can be positioned in a flow path within a main housing of the breathing apparatus. One or more motor parameters can be used to determine system pressure without the need for a separate pressure sensor. The pressure sensor can be used to confirm system pressure determined by the motor parameters.

[0082] Using motor parameters to calculate system pressure can have good short-term accuracy, but can have poor long-term average accuracy compared to using a separate pressure sensor. As such, the output from the pressure sensor and the motor parameters can be used together to determine an accurate system pressure measurement (e.g., using one or more of the techniques described above with respect to flow rate measurement).

[0083] Determining respiratory cycle

[0084] a) Flow deviation

[0085] The patient's respiratory cycle can be determined by observing the deviation of the system's flow rate Q from an average or setpoint flow rate value For example, the flow rate can tend to increase in response to the patient's inhalation, and decrease in response to the patient's exhalation. However, since the motor's speed can also vary, it can be difficult to determine which portion of the deviation is due to changes in the motor speed, and which portion is due to the patient's respiratory cycle.

[0086] b) Limit

[0087] Flow rate limitations can be used to determine the patient's respiratory cycle. Generally, a respiratory system will have some flow resistance (also referred to as a "limitation" or R) overall, which can be used to indicate a relationship between changes in the system's pressure p and the square of the system's flow rate Q 2 ) as shown by the following equation.

[0088] p = RQ 2

[0089] Thus, the limitation R can be approximated as:

[0090]

[0091] The limitation R can vary with the patient's inhalation and exhalation. The smaller the R value, the greater the limitation (e.g., when the patient is exhaling).

[0092] Further, the pressure p can also be approximated as a function of the motor speed as shown by the following equation:

[0093] p = k m ω 2

[0094] where ω corresponds to the motor speed, and k m corresponds to a constant. Thus, the limitation R can be approximated as:

[0095]

[0096] Thus, when using a varying R value as an indicator of a patient's respiratory cycle, the patient's respiratory cycle can be determined based on the measured flow rate Q and the measured motor speed ω. The constant k can be calculated using one or more pressure measurements. m The value of k, or we can assume k m The value of .

[0097] The pressure drop caused by the patient's respiratory and circulatory processes (inspiration / expiration) and the pressure drop caused by other factors (also known as systemic pressure drop) can be added together, as shown in the following equation:

[0098] k m ω 2 =k c Q 2 +RQ 2

[0099]

[0100] Where k c This corresponds to a constant associated with the system pressure drop. The detection of the patient's respiratory cycle is based on the deviation of the detected R (e.g., compared to the mean). The deviation (not the magnitude of R). Therefore, the constant k c It can be ignored. It can be... The value is tracked as a moving average to compensate for deviations in the limiting mechanism (e.g., due to irregular breathing, cannula movement, etc.) and to provide a smoother waveform.

[0101] c) System leak

[0102] The airflow generated by the blower can consist of a first portion flowing to the patient's lungs and a second portion leaking from the system (referred to as the "leak flow"). This can be expressed by the following equation:

[0103] Q = Q p +Q l

[0104] Q p Corresponding to the patient flow, and Q l This corresponds to leakage flow.

[0105] Additionally, the pressure at the casing can be referred to as the "leakage pressure drop". The total blower pressure of the system can be approximated as the sum of the system pressure drop and the leakage pressure drop, which can be expressed as:

[0106]

[0107] Where k l Corresponding to the leakage constant. In a closed or sealed system, k lwill be constant. In a non-sealed system, k l may vary over time, but can be considered substantially constant over a particular breath cycle. k l characterizes the "system leak."

[0108] Thus, the leak flow can be approximated as:

[0109]

[0110] The pressure at the cannula can be approximated as (the leak pressure only) and the patient's lung flow can be approximated as Q p = Q + Q l . As the patient's lung flow changes, the patient's breath cycle can be determined.

[0111] As described above, the variables Q, Q p , Q l , k m , and k c may be measured, calculated, or estimated. Additionally, k l may be estimated by knowing the average flow into the patient's lungs will be approximately zero for the purposes of providing respiratory assistance. In other words, the following assumptions can be made: and The difference in the amount of gas inhaled and exhaled by the patient due to gas exchange (also referred to as "drift") can be calculated, allowing for drift correction of the average flow. If the period T of the patient's breath is known, the average leak of the system can be approximated as:

[0112]

[0113] Then, k l may be calculated using the above equation. If the period T is not known, a time-weighted average can be used over a period of time where a certain number of breaths are known to be close to the period T.

[0114] Once the patient's breath cycle is determined (e.g., using any of the techniques disclosed above), the control signal can be adjusted based on the patient's breath cycle. Additionally, the breath cycle can be used to calculate the patient's respiratory rate (e.g., breaths per minute). The calculated respiratory rate can be displayed, stored, or transmitted (e.g., at the display 308).

[0115] Pressure control in a sealed system

[0116] Pressure sensor readings can be obtained at the patient end or along a portion of the patient breathing tubing in a respiratory system having a sealed patient interface as described above. Pressure sensor readings can also be obtained within a flow therapy device. The pressure sensor can be placed anywhere in the flow path. A non-limiting example of a sealed patient interface is a NIV mask. The NIV mask can seal against the patient's face, resulting in virtually no system leakage. This allows for the measurement of the pressure of the gas delivered to the patient near or at the patient end. The pressure sensor can be positioned inside the NIV mask. The pressure sensor can be positioned outside the patient's nostrils. The pressure sensor can be positioned where the NIV mask is connected to the patient breathing tubing (such as...). Figure 1 The patient's breathing tube 16 is shown in the manifold.

[0117] Measurements from pressure sensors located near or at the patient end (such as those inside the NIV mask or along a portion of the patient's breathing tube) allow for the use of some of the equations described above to control the pressure delivered to the patient. Specifically, equation k m ω 2 =k c Q 2 +RQ 2 The pressure term RQ in 2 The pressure sensor reading P can be used instead to obtain the following equation.

[0118]

[0119] For this equation, we can assume that Q / ω is approximately constant because the system's operation does not change rapidly. This can be achieved by multiplying both sides of the equation by the term (Q / ω). 2 The equation can be further rearranged to obtain an expression that more clearly shows how the pressure sensor reading P and / or the system flow rate Q can affect the motor speed ω.

[0120]

[0121] Based on this equation, the desired system pressure can be achieved by controlling the motor speed. If the desired or predetermined system pressure is known, the required motor speed to achieve it can be calculated. The controller can then adjust the motor speed within the sealed breathing system to control the system pressure.

[0122] Respiratory cycle enhancement

[0123] Once the patient's respiratory cycle has been determined, the control signal to the blower motor can be adjusted based on the determined respiratory cycle in order to better assist the patient's breathing. For example, the flow therapy device can assist the patient's respiratory cycle by increasing air flow when the patient is inhaling, while decreasing flow when the patient is exhaling.

[0124] Figure 6A A block diagram of an example system for performing respiratory cycle augmentation for a flow therapy device is shown. As shown, a patient 602 is connected to a flow therapy device 604. The respiratory system device 604 includes a blower motor 606 or other type of flow generator that can be used to provide air flow to the patient 602. Figure 6A

[0125] During operation of the flow therapy device 604, a number of measurements can be obtained and transmitted to a control signal feedback module 610 in order to adjust the control signal to the blower motor 406 based on the patient's 602 respiratory cycle. For example, motor speed and / or system pressure can be measured using parameters of the blower motor 406. The flow rate of the air flow can be monitored using one or more flow sensors 608. The flow sensors 408 can include two or more different types of sensors, such as a heated temperature sensing element and an ultrasonic sensor assembly. Additionally, one or more additional sensors such as pressure sensors (not shown) can be used to measure one or more additional measurements (e.g., pressure).

[0126] The number of measurements (e.g., motor speed, flow rate, etc.) can be used to determine the patient's respiratory cycle at a respiratory cycle detection module 612. The determined respiratory cycle can be in the form of an alternating waveform (e.g., a substantially sinusoidal waveform).

[0127] Once the patient's respiratory cycle has been determined, it can be used to adjust the control signal to the blower motor 606. For example, the calculated respiratory cycle waveform from the respiratory cycle detection module 612 can be subjected to positive feedback 614 and / or negative feedback 616. Both the positive feedback 614 and the negative feedback 616 can be performed based on the calculated respiratory cycle and combined at 618 to generate a control signal for the blower motor 602.

[0128] The positive feedback 614 can be used to act with the patient during the patient's respiratory cycle by decreasing the motor speed as the patient exhales, and / or increasing the motor speed as the patient inhales. Based on the determined amplitude of the patient's inhalation / exhalation, one or more scaling parameters can be used to increase / decrease the amplitude of the control signal that controls the speed of the blower motor 406. For example, the positive feedback of the blower motor control signal can be represented as:

[0129] ​

[0130] where ω corresponds to motor speed, R corresponds to patient restriction, and correspond to their average or baseline values, and k p corresponds to a positive feedback parameter.

[0131] On the other hand, by dampening the control signal as the patient inhales or exhales, negative feedback 616 can be used to limit the positive feedback provided to the patient's breathing cycle. For example, as the patient inhales, the motor speed of the blower motor can only increase to a certain limit, even as the magnitude of the patient's inhalation increases. The negative feedback 616 can optionally be used only when the magnitude of the patient's inhalation or exhalation exceeds a threshold level. The negative feedback can be provided during inhalation but not exhalation, or vice versa.

[0132] The negative feedback can include limiting the positive feedback applied to the control signal to a certain bound. The negative feedback can include an explicit term, such as:

[0133]

[0134] where the negative feedback parameter k n and N are set such that when the limit bias is low (e.g., close to zero), the negative feedback is negligible, but as the bias increases, the positive feedback begins to dominate. The amount of positive or negative feedback (e.g., the values of the positive feedback parameter k p and the negative feedback parameter k n ) can be adjusted based on the patient's breathing cycle (e.g., whether the patient is inhaling or exhaling).

[0135] Figure 7 A flowchart illustrating an example process for assisting a patient's breathing cycle is shown. At block 702, a control signal is used to drive a blower motor associated with a flow therapy device.

[0136] At block 704, a patient breathing cycle is detected. Detecting a patient breathing cycle can include receiving a plurality of measurements from one or more sensors, such as flow rate measurements, motor speed measurements, pressure measurements, etc. The received measurements can be used to determine the patient's breathing cycle, e.g., using any of the techniques described above.

[0137] At block 706, it is determined whether the patient is currently inhaling or exhaling. If the patient is inhaling, then at block 708, the control signal to the motor can be modified to increase the air flow to the patient, which can reduce the respiratory effort the patient needs to make during inhalation. Due to the increase in air flow, respiratory effort can be reduced. On the other hand, if the patient is exhaling, then at block 710, the control signal to the motor can be modified to decrease the air flow to the patient. This can be beneficial to the patient because during exhalation, respiratory effort is reduced due to the patient not having to inhale the air flow. Additionally, noise caused by the collision between the patient's exhalation gas and the incoming gas from the cannula can be reduced. Being able to adjust the air flow based on the patient's inhalation / exhalation can enhance the effectiveness of high flow respiratory therapy. For example, because the patient does not have to inhale the air flow during exhalation, a fairly high flow rate (e.g., during inhalation) can be delivered to provide greater dead space flushing and / or CO2 washout.

[0138] The amount of increase or decrease in air flow can be based on the amplitude of the patient's inhalation / exhalation. A combination of positive feedback and negative feedback can be used to adjust the control signal. For example, positive feedback can be used to assist the patient's breathing by increasing the motor speed when the patient is inhaling and decreasing the motor speed when the patient is exhaling based on the amplitude of the patient's inhalation / exhalation, while negative feedback can be used to limit or dampen the positive feedback applied to the motor control signal. The process can then return to block 702, where the motor is driven using the updated control signal, and the patient's breathing cycle continues to be monitored.

[0139] While Figure 7 While it is shown that feedback is implemented during both the inhalation phase and the exhalation phase of the patient's breathing cycle, as described above, the positive feedback parameter or the negative feedback parameter can be adjusted based at least in part on the patient's position in the breathing cycle (e.g., whether the patient is inhaling or exhaling). For example, positive feedback can be implemented during inhalation but not during exhalation. For example, a patient who attempts to exhale using "pursed-lip breathing" to lower their work of breathing can benefit from being assisted by increasing the flow rate during inhalation with positive feedback and decreasing the flow rate during exhalation without positive feedback. By not implementing positive feedback during exhalation, exhalation pressure and exhalation time can be increased, which can be beneficial for some patients.

[0140] Control loop with phase shift

[0141] To assist the patient's breathing, the control signal used to drive the blower motor can be configured to have a phase-locked loop to the sensed patient breathing cycle, thereby synchronizing the control signal with the patient's breathing cycle.

[0142] Figure 6B A block diagram of a system for implementing a phase-locked control loop for a flow therapy device is shown. As Figure 6BAs shown, the patient 602 is connected to the flow therapy device 404, with Figure 6A The blower motor 606 is configured to supply a flow of air to the patient 602 according to the received control signal. The control signal that controls the blower motor 606 can include an initial periodic waveform (e.g., a default waveform, or a waveform based on one or more patient measurements).

[0143] The blower motor 606 and flow sensor 608 can be configured to measure motor speed and flow rate, respectively (which can be received by the control signal feedback module 610), where the patient's respiratory cycle can be determined at the respiratory cycle detection module 612. The respiratory cycle can include a waveform.

[0144] Using the determined respiratory cycle, the phase 620 of the patient's respiratory cycle waveform is determined and compared to the phase 626 of the applied control signal waveform 624 to enter a phase-locked control loop 622 that updates the phase of the applied control signal waveform 624. In this way, the error between the phase of the applied control signal waveform 624 and the respiratory cycle waveform can be iteratively reduced so that the applied control signal waveform 624 substantially matches the patient's respiratory cycle. For example, Figure 8 An example graph of a patient's respiratory cycle waveform 802 and a control signal waveform 804 is shown. The phase of the control signal 804 is compared to the phase of the respiratory cycle 802 to determine a phase mismatch 806. The phase of the control signal 804 can be iteratively updated so that the phases of the control signal and respiratory cycle will substantially synchronize (e.g., reduce the phase mismatch 806). The phase of the control signal can be iteratively updated until the phase mismatch is within a threshold amount (e.g., a set time, a percentage of phase, etc.).

[0145] Additionally, the control signal is phase shifted to produce a phase-shifted applied waveform 628. The control signal waveform is phase shifted so as to compensate for the delay between the signal to the blower motor and the resulting flow received by the patient. The waveform can be phase shifted so as to anticipate the patient's respiratory cycle. For example, the control signal can be configured to slightly increase the speed of the blower motor before the patient begins to inhale, and to slightly decrease the speed of the blower motor before the patient begins to exhale. This provides a predictive system, rather than a strictly reactive system, so that more comfortable breathing transitions are allowed as the patient inhales and exhales.

[0146] Figure 9 A flowchart of an example process for implementing a control signal for a blower motor as a phase-locked loop with a sensed patient respiratory cycle is shown. At block 902, a control signal is used to drive a blower motor associated with a flow therapy device.

[0147] At block 904, a patient respiratory cycle is detected. Detecting a patient respiratory cycle can include receiving a plurality of measurements from one or more sensors, such as flow rate measurements, motor speed measurements, pressure measurements, etc. The received measurements can be used to determine a patient’s respiratory cycle, e.g., using any of the techniques described above. Additionally, a respiratory rate or frequency can be calculated based on the determined respiratory cycle.

[0148] The controller can estimate the respiratory rate in a variety of ways. The controller can estimate the respiratory rate when the controller is initially started and / or while the controller is running. The respiratory rate can be estimated by counting zero crossings of any type of respiratory signal described herein. The respiratory rate can be estimated by taking a fast Fourier transform (FFT) of the respiratory signal and finding the dominant frequency. The respiratory rate can be estimated by finding the zero crossings or peaks of the autocorrelation of the respiratory signal.

[0149] The autocorrelation can be a comparison of a signal to a delayed copy of itself as a function of the delay. The autocorrelation can reveal repeating patterns hidden in the original waveform of the signal, e.g., by noise. In particular, a plot of the patient’s original flow rate readings measured by the system versus time, such as Figure 14A shown in FIG. 4A, can be autocorrelated, as shown in FIG. 4B. Peaks of the autocorrelation can be identified. The peaks can be the estimated respiratory cycles, which can be used to estimate the patient’s respiratory rate, also referred to as the respiratory rate. The respiratory cycles can also be determined by identifying the zero crossings of the autocorrelation. The autocorrelation, especially the first few cycles, can provide a more noise-robust estimate of the respiratory cycles than when acting directly on the original respiratory signal waveform. This is because edge detection can be unstable on the original waveform due to noise. Figure 14B

[0150] In addition to helping determine the respiratory rate or frequency to implement the control signal for the blower motor as a phase-locked loop, the respiratory rate information extracted from the autocorrelation can also be used to provide consistency information. For example, the extracted respiratory rate information can indicate whether the patient is using the system correctly. The extracted respiratory rate information can indicate the work of breathing.

[0151] At block 906, it is determined whether the phase of the control signal matches the phase of the sensed patient respiratory cycle. The determination can be satisfied if the phase of the control signal is within a threshold amount or percentage of the phase of the sensed patient respiratory cycle. The phase difference between the control signal and the sensed patient waveform can be determined in a similar manner as described above for estimating the respiratory rate. For example, the controller can perform a cross-correlation between the control signal and the sensed patient waveform and find a peak in the cross-correlation. The peak can occur at or substantially at a time delay between the two waveforms.

[0152] ​If it is determined that the control signal phase does not match the phase of the sensed patient respiratory cycle, then at block 908, the phase of the control signal is repeatedly adjusted to match the phase of the sensed patient respiratory cycle. The phase of the control signal can be adjusted by a predetermined amount, a predetermined percentage, a percentage or amount based on the difference between the phase of the control signal and the phase of the sensed patient respiratory cycle, etc. The process can then return to block 902, where the motor can continue to be driven by the control signal, and the patient's respiratory cycle can continue to be monitored.

[0153] The amplitude of the control signal can be based on one or more positive feedback or negative feedback parameters. For example, the amplitude of the patient's inhalation or exhalation can be measured and can be used to determine the amplitude of the control signal waveform using the positive feedback parameters and the negative feedback parameters.

[0154] By implementing a phase-locked loop, synchronization between the control signal and the patient respiratory cycle can be achieved to allow for more comfortable respiratory transitions as the patient inhales and exhales. Positive feedback can be reduced or eliminated when asynchrony is suspected. In such cases, the control signal can be configured to reduce the peak of the flow, or to make the flow substantially constant, where the constant flow rate is lower than the flow rate when positive feedback is implemented. Reducing or eliminating positive feedback can reduce or eliminate potential discomfort to the patient due to the positive feedback of the control signal. Once synchronization between the control signal and the patient respiratory cycle is reestablished, positive feedback can be restarted or increased.

[0155] With synchronization achieved, the control signal waveform can be gradually introduced. For example, the amplitude of the control signal waveform can start from a lower value, such that the control signal waveform that is slightly out of phase with the patient's respiratory cycle does not cause too much discomfort to the patient. The amplitude of the control signal waveform can increase as synchronization is achieved.

[0156] The control signal waveform can be configured to achieve a target phase difference with respect to the patient's respiratory cycle. For example, the control signal waveform can be phase shifted by a target amount with respect to the respiratory cycle in order to compensate for system delays, or to preempt the patient's respiratory cycle. These implementations are discussed in more detail below.

[0157] A delay can be sensed between the time a control signal is delivered to a blower motor and the time a resulting air flow is generated by the blower motor (due to, for example, motor acceleration or deceleration, delays due to inertia, sensed delays, etc.), which is referred to hereinafter as a system delay. The control signal can be phase shifted in order to compensate for the system delay. Figure 10 A flowchart illustrating an example process for phase shifting a control signal to compensate for a system delay is shown. At block 1002, a control signal is used to drive a blower motor associated with a flow therapy device.

[0158] At block 1004, one or more sensors can be used to sense the resulting flow from the blower motor. The one or more sensors can include a heated temperature sensing element, an ultrasonic sensor, etc. Based on the measured flow, a system delay is determined between the time the control signal is received by the blower motor and the time the resulting flow is sensed.

[0159] At block 1006, the control signal is adjusted based on the determined system delay. For example, Figure 11 A graph is shown demonstrating updating the control signal to compensate for the system delay. The system delay 1106 is measured between the time the motor receives the control signal 1102 and the time the patient receives the resulting flow 1104. The control signal can then be phase shifted to form a phase shifted control signal 1108 in order to compensate for the delay 1106.

[0160] The control waveform can be further shifted so that it anticipates the sensed respiratory cycle waveform of the patient. Figure 12 A flowchart is shown demonstrating an example process for configuring a phase shifted control signal to anticipate the respiratory cycle waveform of a patient. At block 1202, a control signal is used to drive a blower motor associated with a flow therapy device.

[0161] At block 1204, a patient respiratory cycle is detected. Detecting the patient respiratory cycle can include receiving a plurality of measurements from one or more sensors, such as flow rate measurements, motor speed measurements, pressure measurements, etc. The received measurements can be used to determine the respiratory cycle of the patient, for example, using any of the techniques described above.

[0162] At block 1206, the phase of the control signal can be matched to the phase of the respiratory cycle. This can include an iterative process, such as the iterative process described above with reference to Figure 8 and / or Figure 9 the iterative process described above.

[0163] At block 1208, the patient respiratory cycle is analyzed to identify when the patient is inhaling or exhaling. For example, Figure 13 An example graph is shown demonstrating a patient respiratory cycle 1302 and a phase shifted control signal 1304. As Figure 13 shown, it can be inferred that the patient begins to exhale near the peak of the respiratory cycle waveform of the patient (e.g., shortly after the peak) at 1306 and begins to inhale near the trough of the respiratory cycle waveform (e.g., shortly after the trough) at 1308.

[0164] Returning to Figure 12 , at block 1210, the control signal is phase shifted based on the patient respiratory cycle. For example, the control signal can be phase shifted so that the control signal leads the phase of the respiratory cycle by a set amount of phase or time. For example, as Figure 13As shown, the control waveform can be shifted so that the motor starts decreasing speed before the patient begins to exhale and starts increasing speed before the patient begins to inhale.

[0165] The control waveform can be selected from a series of predetermined shapes, and can be modified based on one or more respiratory parameters (e.g., the amplitude of the respiratory cycle waveform). The control waveform can be dynamically created based on a sensed respiratory waveform.

[0166] Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise", "comprising", and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense, that is to say, in the sense of "including, but not limited to".

[0167] The term "about" is used herein to mean within standard measurement precision.

[0168] Any reference to prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that this prior art forms part of the common general knowledge in the field of endeavour in any country.

[0169] The disclosed devices and systems can also be said broadly to consist of the components, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more of the disclosed components, elements or features.

[0170] Where in the foregoing description reference has been made to integers or components having known equivalents thereof, those integers have been presented as if such equivalents are fully known then to exist.

[0171] Certain actions, events, or functions of any of the algorithms, methods, or processes described herein can be performed in a different order, can be added, merged or entirely omitted (e.g., not all described actions or events are necessary to practice the algorithms). Moreover, actions or events can be performed concurrently, for example, through multi-threaded processing, interrupt processing, or multiple processors or processor cores or on other parallel architectures, rather than sequentially.

[0172] It is noted that various changes and modifications to the disclosed devices and systems can be made which will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the disclosed devices and systems and without diminishing its attendant advantages. For example, various components can be repositioned as desired. Accordingly, it is intended that all such changes and modifications be included within the scope of the disclosed devices and systems. Further, not all of the features, aspects and advantages of the disclosed devices and systems can be needed to practice the disclosed devices and systems. Accordingly, the scope of the disclosed devices and systems is intended to be governed only by the following claims and not the description.

Claims

1. A respiratory system configured to determine a patient's respiratory rate, the respiratory system comprising: At least one sensor configured to measure flow rate; The processor is configured to be electrically connected to the at least one sensor to receive flow rate measurements of a patient using a respiratory system, and the processor is further configured to determine the patient's respiratory rate by autocorrelation of a graph of the flow rate measurements versus time.

2. The respiratory system as claimed in claim 1, wherein, The processor is also configured to determine respiratory cycles from one or more peaks or zero crossings of the autocorrelation of a graph of flow rate measurements versus time.

3. The respiratory system as described in claim 1 or 2, wherein, The at least one sensor includes a first ultrasonic transducer and a second ultrasonic transducer and / or a heated temperature sensing element.

4. The respiratory system as described in claim 1 or 2, wherein, The processor is also configured to generate a respiratory cycle waveform based at least in part on the determined respiratory rate, the respiratory cycle waveform comprising multiple alternating inspiratory and expiratory cycles of the patient.

5. The respiratory system as claimed in claim 4, wherein, The respiratory system also includes a blower for generating airflow for the patient, the blower being associated with a motor that can be configured to be driven by a control signal.

6. The respiratory system as claimed in claim 5, wherein, Motors include brushless DC motors.

7. The respiratory system as claimed in claim 5, wherein, The processor is also configured to synchronize the control signal with the respiratory cycle by: identifying the phase of the respiratory cycle waveform; and repeatedly updating the phase of the control signal to achieve a defined phase difference between the control signal and the respiratory cycle waveform, such that the control signal is configured to adjust the speed of the motor based on the patient's inhalation and exhalation.

8. The respiratory system as claimed in claim 5, wherein, The processor is also configured to phase-shift the control signal based on the system delay between the control signal received by the blower motor and the sensed airflow.

9. The respiratory system as claimed in claim 5, wherein, The processor is also configured to phase-shift the control signal so that the control signal preempts the breathing cycle waveform by a set amount of time.

10. The respiratory system of claim 5, wherein, The processor is also configured to generate respiratory cycle waveforms based on flow rate measurements and motor speed measurements associated with the motor.

11. The respiratory system of claim 10, wherein, The motor speed measurement is determined at least in part based on one or more motor parameters.

12. The respiratory system of claim 5, wherein, The processor is also configured to generate respiratory cycle waveforms based on flow rate measurements and one or more pressure measurements from a pressure sensor.

13. The respiratory system of claim 12, wherein, The processor is also configured to generate respiratory cycle waveforms based on flow rate measurements, motor speed measurements, and one or more pressure measurements from a pressure sensor.

14. The respiratory system as claimed in claim 1 or 2, wherein, The respiratory system also includes high-flow-rate respiratory therapy equipment.

15. The respiratory system as claimed in claim 1 or 2, wherein, The respiratory system is a non-sealed respiratory system.

16. The respiratory system as claimed in claim 1 or 2, wherein, The respiratory system is a sealed respiratory system.

17. The respiratory system of claim 12, wherein, The processor is also configured to adjust the motor speed based on one or more pressure measurements from a pressure sensor to achieve a predetermined pressure for the respiratory system.

18. The respiratory system as claimed in claim 1 or 2, wherein, The respiratory system includes a non-invasive ventilation mask.

19. The respiratory system of claim 12, wherein, The respiratory system includes a non-invasive ventilation mask, with a pressure sensor located in the non-invasive ventilation mask, or in a manifold that connects the non-invasive ventilation mask to the patient's breathing tube, or inside the patient's breathing tube, or inside the housing of the respiratory system.

20. A method for determining a patient's respiratory rate using a respiratory system, the method comprising: Receive flow rate measurements from at least one sensor from patients using a respiratory system; Autocorrelation of the flow rate measurement versus time; as well as The patient's respiratory rate was determined from autocorrelation.

21. The method of claim 20, wherein, Determining a patient's respiratory rate also involves determining the patient's respiratory cycle from one or more peaks or zero crossings in the autocorrelation.

22. The method of claim 20 or 21, wherein, Flow rate is measured using a first ultrasonic transducer, a second ultrasonic transducer, and / or a heated temperature sensing element.

23. The method of claim 20 or 21, wherein, The method also includes generating a respiratory cycle waveform based at least in part on the determined respiratory rate, the respiratory cycle waveform comprising multiple alternating inspiratory and expiratory cycles of the patient.

24. The method of claim 23, wherein, The respiratory system includes a blower for generating airflow for the patient, the blower being associated with a motor configured to be driven by a control signal; The method further includes synchronizing the control signal with the respiratory cycle by identifying the phase of the respiratory cycle waveform and repeatedly updating the phase of the control signal to achieve a defined phase difference between the control signal and the respiratory cycle waveform, such that the control signal is configured to adjust the speed of the motor based on the patient's inhalation and exhalation.

25. The method of claim 24, wherein, Motors include brushless DC motors.

26. The method of claim 24, wherein, Synchronizing the control signal with the respiratory cycle also includes phase shifting the control signal based on the system delay between the control signal received by the motor and the airflow sensed by the patient.

27. The method of claim 24, wherein, Synchronizing the control signal with the respiratory cycle also includes phase shifting the control signal so that the control signal precedes the respiratory cycle waveform by a set time amount.

28. The method of claim 24, wherein, The method also includes generating a respiratory cycle waveform based on a determined breathing rate and a motor speed measurement associated with the blower motor.

29. The method of claim 28, wherein, The method also includes determining a motor speed measurement based on the one or more motor parameters.

30. The method of claim 24, wherein, The respiratory cycle waveform is generated based on a determined respiratory rate and one or more pressure measurements from a pressure sensor.

31. The method of claim 30, wherein, The respiratory cycle waveform is generated based on a determined respiratory rate, the one or more motor parameters, and the one or more pressure measurements from a pressure sensor.

32. The method of claim 20 or 21, wherein, This method is performed in a high-flow-rate respiratory therapy system.

33. The method of claim 23 or 24, wherein, This method is performed in an open-system breathing apparatus.

34. The method of claim 23 or 24, wherein, This method is performed in a sealed breathing system.

35. The method of claim 30, wherein, The method also includes adjusting the motor speed based on pressure measurements from a pressure sensor to achieve a predetermined pressure for the respiratory system.

36. The method of claim 34, wherein, Sealed breathing systems include non-invasive ventilation masks.

37. The method of claim 30, wherein, A sealed respiratory system includes a non-invasive ventilation mask, with a pressure sensor located in the non-invasive ventilation mask, or in a manifold that connects the non-invasive ventilation mask to the patient's breathing tube, or inside the patient's breathing tube, or inside the housing of the respiratory system.

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