Respiratory apparatus

Abstract

Respiratory apparatus is provided. The disclosure provides a flow therapy apparatus that can implement one or more closed loop control systems to control the flow of gas of the flow therapy apparatus. The flow therapy apparatus can monitor the blood oxygen saturation (SpO2) of a patient and control the fraction of inspired oxygen (FdO2) delivered to the patient. The flow therapy apparatus can automatically adjust the FdO2 in order to achieve a target SpO2 value of the patient.

Description

[0001] This application is a divisional application of the application filed on October 5, 2018, with application number 201880074904.5 and invention title "Closed-loop Oxygen Control". Technical Field

[0002] This disclosure relates to methods and systems for controlling oxygen delivery in flow therapy devices. background

[0003] Breathing equipment is used in a variety of environments, such as hospitals, medical facilities, home care, or the home, to deliver a flow of gas to a user or patient. Breathing equipment or flow therapy equipment may include an oxygen inlet for allowing the delivery of supplemental oxygen and gas flow, and / or a humidification device for delivering heated and humidified gas. Flow therapy equipment may allow for the adjustment and control of gas flow characteristics, including flow rate, temperature, gas concentration (e.g., oxygen concentration), humidity, pressure, etc. Summary of the Invention

[0004] According to certain features, aspects, and advantages of the first embodiment disclosed herein, a respiratory device for providing a gas flow to a patient is provided, the respiratory device comprising: a controller configured to control the gas delivery to the patient using closed-loop control, wherein the controller is configured to: receive patient parameter data indicating the patient's oxygen saturation (SpO2) from at least one sensor; execute a control phase, wherein operation of the respiratory device during a treatment period is at least partially based on the patient parameter data; and a gas composition sensor configured to determine at least the oxygen content (FdO2) of the gas flow during operation of the respiratory device, wherein the gas composition sensor is an ultrasonic sensor system.

[0005] In some configurations of the first embodiment, the respiratory device includes a patient interface selected from at least one of the following: a face mask, a nasal mask, a nasal pillow mask, a tracheostomy interface, a nasal tube, or an endotracheal tube.

[0006] In some configurations of the first embodiment, the nasal cannula is an unsealed nasal cannula.

[0007] In some configurations of the first embodiment, the breathing device is configured to deliver a high-flow-rate (NHF) gas stream to the patient.

[0008] In some configurations of the first embodiment, the at least one sensor is a pulse oximeter.

[0009] In some configurations of the first embodiment, the controller is configured to receive device parameter data indicating the oxygen concentration of the gas flow.

[0010] In some configurations of the first embodiment, the breathing device includes a supplemental gas inlet valve.

[0011] In some configurations of the first embodiment, the controller is configured to control the operation of the supplementary gas inlet valve.

[0012] In some configurations of the first embodiment, the supplementary gas inlet valve is a proportional valve.

[0013] In some configurations of the first embodiment, the supplementary gas inlet valve is an oxygen inlet valve.

[0014] In some configurations of the first embodiment, the supplemental gas inlet valve includes a rotary connector.

[0015] In some configurations of the first embodiment, the breathing device includes an ambient air inlet.

[0016] In some configurations of the first embodiment, the oxygen inlet valve is in fluid communication with the filter module, and the breathing device is configured to entrain oxygen received from the oxygen inlet valve and ambient air from the ambient air inlet into the filter module.

[0017] In some configurations of the first embodiment, the gas composition sensor is located downstream of the blower module of the breathing device.

[0018] In some configurations of the first embodiment, the filter module is located upstream of the blower module of the breathing device.

[0019] In some configurations of the first embodiment, the blower module mixes ambient air and oxygen.

[0020] In some configurations of the first embodiment, closed-loop control includes using a first closed-loop control model configured to determine a target delivered oxygen fraction (FdO2).

[0021] In some configurations of the first embodiment, the target FdO2 is determined at least in part based on the target SpO2 and the measured SpO2.

[0022] In some configurations of the first embodiment, the target FdO2 is further based at least in part on the measured FdO2.

[0023] In some configurations of the first embodiment, the target FdO2 is further based at least in part on the previous target FdO2.

[0024] In some configurations of the first embodiment, closed-loop control includes using a second closed-loop control model configured to determine the control signal for the oxygen inlet valve based at least in part on the difference between the target FdO2 and the measured FdO2.

[0025] In some configurations of the first embodiment, the control signal for the oxygen valve is determined at least in part based on the target FdO2 and the measured FdO2.

[0026] In some configurations of the first embodiment, the control signal for the oxygen valve is further determined based at least in part on the gas flow rate.

[0027] In some configurations of the first embodiment, the gas flow rate is the total gas flow rate.

[0028] In some configurations of the first embodiment, the controller is configured to switch to manual operation mode when the signal quality of the at least one sensor is below a threshold.

[0029] In some configurations of the first embodiment, the controller is configured to generate a notification to the user indicating that the signal quality of the at least one sensor is below a threshold.

[0030] In some configurations of the first embodiment, the notification request comes from user input indicating whether to switch to manual operation mode.

[0031] In some configurations of the first embodiment, the controller is configured to switch to manual operation mode when the patient's SpO2 is outside a defined limit.

[0032] In some configurations of the first embodiment, the controller is configured to trigger an alarm when the patient's SpO2 is outside a defined limit.

[0033] In some configurations of the first embodiment, control of gas delivery includes control of FdO2 in the gas flow, and the controller is configured to: receive an indication of the signal quality of the at least one sensor; and apply a weighted approach to the control of FdO2 based at least in part on the signal quality.

[0034] In some configurations of the first embodiment, the signal quality indication corresponds to a specific SpO2 reading.

[0035] In some configurations of the first embodiment, the control phase is configured to be performed using a patient-specific model.

[0036] In some configurations of the first embodiment, a patient-specific model is generated during the learning phase of the treatment period.

[0037] In some configurations of the first embodiment, a patient-specific model is generated during the treatment period.

[0038] In some configurations of the first embodiment, the patient-specific model is updated during the treatment period.

[0039] In some configurations of the first embodiment, the control phase is configured to be performed using PID control, at least in part, based on a patient-specific model.

[0040] In some configurations of the first embodiment, the patient-specific model includes the patient's oxygen efficiency.

[0041] In some configurations of the first embodiment, oxygen efficiency is determined at least in part based on measured SpO2 and measured FdO2.

[0042] In some configurations of the first embodiment, oxygen efficiency is determined at least in part based on the measured SpO2 divided by the measured FdO2.

[0043] In some configurations of the first embodiment, oxygen efficiency is determined at least in part based on the nonlinear relationship between the patient's measured SpO2 and measured FdO2.

[0044] In some configurations of the first embodiment, the controller is configured to predict a patient’s SpO2 based at least in part on the measured FdO2.

[0045] In some configurations of the first embodiment, the previous prediction of SpO2 is compared with the measured SpO2 to calculate the model error.

[0046] In some configurations of the first embodiment, the model error is weighted according to the signal quality of the at least one sensor.

[0047] In some configurations of the first embodiment, model error is used to correct the current SpO2 prediction.

[0048] In some configurations of the first embodiment, the predicted SpO2 is based at least in part on the Smith predictor.

[0049] In some configurations of the first embodiment, the controller is configured to receive input that identifies the characteristics of the patient.

[0050] In some configurations of the first embodiment, patient characteristics include at least one of patient type, age, weight, height, or gender.

[0051] In some configurations of the first embodiment, the patient type is one of normal, hypercapnia, or user-defined.

[0052] In some configurations of the first embodiment, the controller is further configured to record data corresponding to the measured FdO2 and the measured SpO2.

[0053] In some configurations of the first embodiment, the breathing device includes a humidifier.

[0054] In some configurations of the first embodiment, the breathing device includes an integrated blower and a humidifier.

[0055] In some configurations of the first embodiment, the breathing device is configured to be portable.

[0056] In some configurations of the first embodiment, the breathing device is configured to have a controlled variable flow rate.

[0057] In some configurations of the first embodiment, the breathing device includes a heated breathing tube.

[0058] In some configurations of the first embodiment, the ultrasonic sensor system includes a first ultrasonic transducer and a second ultrasonic transducer.

[0059] In some configurations of the first embodiment, each of the first and second ultrasonic transducers is a receiver and a transmitter.

[0060] In some configurations of the first embodiment, the first ultrasonic transducer and the second ultrasonic transducer transmit pulses bidirectionally.

[0061] In some configurations of the first embodiment, the first ultrasonic transducer is a transmitter and the second ultrasonic transducer is a receiver.

[0062] In some configurations of the first embodiment, at least one of the first or second ultrasonic transducers transmits pulses along the gas flow.

[0063] In some configurations of the first embodiment, at least one of the first or second ultrasonic transducers transmits pulses across the gas flow.

[0064] In some configurations of the first embodiment, the controller is configured to display a first oxygen efficiency characteristic on the display of the breathing device.

[0065] In some configurations of the first embodiment, the controller is configured to display a second oxygen efficiency characteristic on a display of the respiratory device, and the second indication of oxygen efficiency is based at least in part on the patient's oxygen efficiency and the measured respiratory rate.

[0066] In some configurations of the first embodiment, the second oxygen efficiency characteristic is calculated by dividing the measured SpO2 by the measured FdO2 and then dividing the result by the measured respiration rate.

[0067] In some configurations of the first embodiment, the controller is configured to display a graph or trend line indicating at least one of a first oxygen efficiency characteristic or a second oxygen efficiency characteristic over a defined time period.

[0068] According to certain features, aspects, and advantages of the second embodiment disclosed herein, a breathing device for providing a gas flow to a patient is provided, the breathing device comprising: a controller configured to control the gas delivery to the patient using closed-loop control, the controller being configured to: control the oxygen concentration (FdO2) of the gas flow to the patient; receive data from at least one patient sensor indicating the patient's measured oxygen saturation (SpO2); receive data indicating the measured FdO2 of the gas flow; receive the patient's target SpO2; and perform a step change on the FdO2 of the gas flow, the magnitude of which is at least partially based on the patient's measured SpO2, target SpO2, and oxygen efficiency.

[0069] In some configurations of the second embodiment, oxygen efficiency is determined at least in part based on measured SpO2 and measured FdO2.

[0070] In some configurations of the second embodiment, oxygen efficiency is determined at least in part based on the measured SpO2 divided by the measured FdO2.

[0071] In some configurations of the second embodiment, oxygen efficiency is determined at least in part based on the nonlinear relationship between the patient's measured SpO2 and measured FdO2.

[0072] In some configurations of the second embodiment, the magnitude of the step change is based at least in part on the most recent change in the target FdO2 prior to the step change.

[0073] In some configurations of the second embodiment, the magnitude of the step change is based at least in part on the most recent change in the target FdO2 prior to the step change.

[0074] In some configurations of the second embodiment, the new target FdO2 is calculated at least in part based on the previous target FdO2.

[0075] In some configurations of the second embodiment, the controller is configured to perform a feedforward phase after a step change.

[0076] In some configurations of the second embodiment, the controller is further configured to maintain the target FdO2 for the total duration of the feedforward phase immediately after the step change.

[0077] In some configurations of the second embodiment, the feedforward phase ends if the measured SpO2 meets or exceeds the target SpO2.

[0078] In some configurations of the second embodiment, the feedforward phase ends if the maximum time limit is reached.

[0079] In some configurations of the second embodiment, the respiratory device includes a patient interface selected from at least one of the following: a face mask, a nasal mask, a nasal pillow mask, a tracheostomy interface, a nasal tube, or an endotracheal tube.

[0080] In some configurations of the second embodiment, the nasal cannula is an unsealed nasal cannula.

[0081] In some configurations of the second embodiment, the breathing device is configured to deliver a high-flow-rate (NHF) gas stream to the patient.

[0082] In some configurations of the second embodiment, the at least one patient sensor is a pulse oximeter.

[0083] In some configurations of the second embodiment, the breathing device includes a humidifier.

[0084] In some configurations of the second embodiment, the breathing device includes a gas composition sensor configured to determine measured FdO2 during operation of the breathing device, and the gas composition sensor is an ultrasonic transducer system.

[0085] In some configurations of the second embodiment, the controller is further configured to perform a control phase after the feedforward phase.

[0086] In some configurations of the second embodiment, during the control phase, the controller is further configured to use feedback control to control the FdO2 of the gas flow to achieve the target FdO2.

[0087] In some configurations of the second embodiment, the controller is further configured to: receive an indication of the signal quality of the at least one patient sensor; and to apply a weighted approach to the control of FdO2 based at least in part on the signal quality.

[0088] In some configurations of the second embodiment, the controller is further configured to use the patient's predicted SpO2 to perform the control phase.

[0089] In some configurations of the second embodiment, the breathing device is configured to be portable.

[0090] In some configurations of the second embodiment, the controller is configured to display a first oxygen efficiency characteristic on the display of the breathing device.

[0091] In some configurations of the second embodiment, the controller is configured to display a second oxygen efficiency characteristic on a display of the respiratory device, and the second indication of oxygen efficiency is based at least in part on the patient's oxygen efficiency and the measured respiratory rate.

[0092] In some configurations of the second embodiment, the second oxygen efficiency characteristic is calculated by dividing the measured SpO2 by the measured FdO2 and then dividing the result by the measured respiration rate.

[0093] In some configurations of the second embodiment, the controller is configured to display a graph or trend line indicating at least one of a first oxygen efficiency characteristic or a second oxygen efficiency characteristic over a defined time period.

[0094] According to certain features, aspects, and advantages of the third embodiment disclosed herein, a respiratory device for providing a gas flow to a patient is provided, the respiratory device comprising: a controller configured to control the gas delivery to the patient using closed-loop control, wherein the controller is configured to: receive device parameter data indicating the oxygen concentration (FdO2) of the gas flow; receive patient parameter data from at least one sensor indicating a reading of the patient's oxygen saturation (SpO2), wherein the patient's SpO2 is affected by the FdO2 of the gas flow; receive an indication of the signal quality of the at least one sensor; and apply a weighted approach to the control of FdO2 based at least in part on the signal quality.

[0095] In some configurations of the third embodiment, the signal quality indication corresponds to a specific SpO2 reading.

[0096] In some configurations of the third embodiment, the respiratory device includes a patient interface selected from at least one of the following: a face mask, a nasal mask, a nasal pillow mask, a tracheostomy interface, a nasal tube, or an endotracheal tube.

[0097] In some configurations of the third embodiment, the nasal cannula is an unsealed nasal cannula.

[0098] In some configurations of the third embodiment, the breathing device is configured to deliver a high-flow-rate (NHF) gas stream to the patient.

[0099] In some configurations of the third embodiment, the at least one sensor is a pulse oximeter.

[0100] In some configurations of the third embodiment, the controller is configured to receive input that identifies the characteristics of the patient.

[0101] In some configurations of the third embodiment, the controller is configured to use the patient's predicted SpO2 to control gas delivery.

[0102] In some configurations of the third embodiment, the predicted SpO2 is based at least in part on the Smith predictor.

[0103] In some configurations of the third embodiment, the controller is configured to use a patient-specific model to control gas delivery.

[0104] In some configurations of the third embodiment, the model is a patient-specific model generated during the learning phase of the patient's treatment period.

[0105] In some configurations of the third embodiment, a patient-specific model is generated at least in part based on the default model during the treatment period.

[0106] In some configurations of the third embodiment, the patient-specific model is updated during the treatment period.

[0107] In some configurations of the third embodiment, the model includes a delay time.

[0108] In some configurations of the third embodiment, the model includes exponential decay.

[0109] In some configurations of the third embodiment, the model includes the patient's oxygen efficiency.

[0110] In some configurations of the third embodiment, oxygen efficiency is determined at least in part based on measured SpO2 and measured FdO2.

[0111] In some configurations of the third embodiment, oxygen efficiency is determined at least in part based on the measured SpO2 divided by the measured FdO2.

[0112] In some configurations of the third embodiment, oxygen efficiency is determined at least in part based on the nonlinear relationship between the patient's measured SpO2 and measured FdO2.

[0113] In some configurations of the third embodiment, the breathing device is configured to be portable.

[0114] According to certain features, aspects, and advantages of the fourth embodiment disclosed herein, a respiratory device for providing a gas flow to a patient is provided, the respiratory device comprising: a controller configured to control the gas delivery to the patient using closed-loop control, wherein the controller is configured to: control the oxygen concentration (FdO2) of the gas flow to the patient; receive data from at least one patient sensor indicating a measured oxygen saturation (SpO2) of the patient; receive data indicating the measured FdO2 of the gas flow; receive a target SpO2 of the patient; and execute a waiting phase, wherein during the waiting phase, the controller is configured to determine whether to execute a feedforward phase before transitioning to a control phase, wherein during the waiting phase, the target FdO2 of the gas flow remains constant; and execute a control phase, wherein feedback control is used to control the FdO2 to achieve the target SpO2.

[0115] In some configurations of the fourth embodiment, the controller is further configured to determine whether to perform the feedforward phase based at least in part on the target SpO2 and the measured SpO2.

[0116] In some configurations of the fourth embodiment, the controller is further configured to determine whether to perform a feedforward phase based at least in part on the patient’s oxygen efficiency.

[0117] In some configurations of the fourth embodiment, oxygen efficiency is determined at least in part based on measured SpO2 and measured FdO2.

[0118] In some configurations of the fourth embodiment, oxygen efficiency is determined at least in part based on the measured SpO2 divided by the measured FdO2.

[0119] In some configurations of the fourth embodiment, oxygen efficiency is determined at least in part based on the nonlinear relationship between the patient's measured SpO2 and measured FdO2.

[0120] In some configurations of the fourth embodiment, if the controller determines to execute the feedforward phase, the controller executes the feedforward phase after the waiting phase; and if the controller determines not to execute the feedforward phase, the controller executes the control phase after the waiting phase.

[0121] In some configurations of the fourth embodiment, the controller is further configured to maintain the target FdO2 throughout the total duration of the feedforward phase.

[0122] In some configurations of the fourth embodiment, the feedforward phase ends if the measured SpO2 meets or exceeds the target SpO2.

[0123] In some configurations of the fourth embodiment, the feedforward phase ends if the maximum time limit is reached.

[0124] In some configurations of the fourth embodiment, the controller is further configured to perform a control phase after the feedforward phase.

[0125] In some configurations of the fourth embodiment, the controller is configured to determine whether to perform a step change on the FdO2 of the gas flow before performing the feedforward phase.

[0126] In some configurations of the fourth embodiment, the controller is further configured to determine whether to perform a step change based at least in part on the most recent change in the target FdO2.

[0127] In some configurations of the fourth embodiment, the controller is further configured to determine whether to perform a step change based at least in part on the target SpO2 and the measured SpO2.

[0128] In some configurations of the fourth embodiment, the controller is further configured to determine whether to perform a step change based at least in part on the patient’s oxygen efficiency.

[0129] In some configurations of the fourth embodiment, the magnitude of the step change is based at least in part on the patient’s measured SpO2, target SpO2, and oxygen efficiency.

[0130] In some configurations of the fourth embodiment, the magnitude of the step change is based at least in part on the most recent change in the target FdO2.

[0131] In some configurations of the fourth embodiment, the respiratory device includes a patient interface selected from at least one of the following: a face mask, a nasal mask, a nasal pillow mask, a tracheostomy interface, a nasal tube, or an endotracheal tube.

[0132] In some configurations of the fourth embodiment, the nasal cannula is an unsealed nasal cannula.

[0133] In some configurations of the fourth embodiment, the breathing device is configured to deliver a high-flow-rate (NHF) gas stream to the patient.

[0134] In some configurations of the fourth embodiment, the at least one patient sensor is a pulse oximeter.

[0135] In some configurations of the fourth embodiment, the breathing device includes a humidifier.

[0136] In some configurations of the fourth embodiment, the breathing device includes a gas composition sensor configured to determine measured FdO2 during operation of the breathing device, and the gas composition sensor is an ultrasonic transducer system.

[0137] In some configurations of the fourth embodiment, the controller is further configured to: receive an indication of the signal quality of the at least one patient sensor; and to apply a weighted approach to the control of FdO2 based at least in part on the signal quality.

[0138] In some configurations of the fourth embodiment, the controller is further configured to apply weighting during the control phase.

[0139] In some configurations of the fourth embodiment, the controller is further configured to use the patient's predicted SpO2 to perform the control phase.

[0140] In some configurations of the fourth embodiment, the breathing device is configured to be portable.

[0141] According to certain features, aspects, and advantages of the fifth embodiment disclosed herein, a respiratory device for providing a gas flow to a patient is provided, the respiratory device comprising: a controller configured to control the gas delivery to the patient using closed-loop control, wherein the controller is configured to: deliver a high-flow-rate (NHF) gas flow to the patient; receive data from at least one patient sensor indicating a measured oxygen saturation (SpO2) of the patient; receive data indicating a measured fraction of delivered oxygen (FdO2) of the gas flow; determine the oxygen efficiency of the patient; and generate a patient-specific model based on the measured SpO2 and the measured FdO2, wherein the patient-specific model uses the patient's oxygen efficiency.

[0142] In some configurations of the fifth embodiment, oxygen efficiency is determined at least in part based on measured SpO2 and measured FdO2.

[0143] In some configurations of the fifth embodiment, oxygen efficiency is determined at least in part based on the measured SpO2 divided by the measured FdO2.

[0144] In some configurations of the fifth embodiment, oxygen efficiency is determined at least in part based on the nonlinear relationship between the patient's measured SpO2 and measured FdO2.

[0145] In some configurations of the fifth embodiment, patient-specific models are generated at least in part based on the default model.

[0146] In some configurations of the fifth embodiment, a patient-specific model is generated during the learning phase.

[0147] In some configurations of the fifth embodiment, the patient-specific model is updated during the patient's treatment period.

[0148] In some configurations of the fifth embodiment, the patient-specific model models the magnitude of the change in SpO2 based at least in part on the change in FdO2.

[0149] In some configurations of the fifth embodiment, the patient-specific model uses the flow rate of the gas stream.

[0150] In some configurations of the fifth embodiment, the patient-specific model includes the time delay between changes in the patient's FdO2 and changes in SpO2.

[0151] In some configurations of the fifth embodiment, the delay time is based at least in part on the flow rate of the gas stream.

[0152] In some configurations of the fifth embodiment, the patient-specific model includes exponential decay.

[0153] In some configurations of the fifth embodiment, the at least one patient sensor is a pulse oximeter.

[0154] In some configurations of the fifth embodiment, the breathing device includes a humidifier.

[0155] In some configurations of the fifth embodiment, an ultrasonic transducer system is used to measure FdO2.

[0156] In some configurations of the fifth embodiment, the ultrasonic transducer system includes a first ultrasonic transducer and a second ultrasonic transducer.

[0157] In some configurations of the fifth embodiment, each of the first and second ultrasonic transducers is a receiver and a transmitter.

[0158] In some configurations of the fifth embodiment, the first ultrasonic transducer and the second ultrasonic transducer transmit pulses bidirectionally.

[0159] In some configurations of the fifth embodiment, the first ultrasonic transducer is a transmitter and the second ultrasonic transducer is a receiver.

[0160] In some configurations of the fifth embodiment, at least one of the first or second ultrasonic transducers transmits pulses along the gas flow.

[0161] In some configurations of the fifth embodiment, at least one of the first or second ultrasonic transducers transmits pulses across the gas flow.

[0162] In some configurations of the fifth embodiment, the breathing device is configured to be portable.

[0163] According to certain features, aspects, and advantages of the sixth embodiment disclosed herein, a respiratory device for providing a gas flow to a patient is provided, the respiratory device comprising: a controller configured to control the gas delivery to the patient using closed-loop control, wherein the controller is configured to: control the oxygen concentration (FdO2) of the gas flow to the patient; receive data from at least one patient sensor indicating the patient's measured oxygen saturation (SpO2); receive data indicating the measured FdO2 of the gas flow; receive a target SpO2 for the patient; perform a step change on the FdO2 of the gas flow to achieve the target FdO2; perform a feedforward phase; and perform a control phase, wherein feedback control is used to control the FdO2 to achieve the target SpO2.

[0164] In some configurations of the sixth embodiment, the magnitude of the step change is based at least in part on the patient’s measured SpO2, target SpO2, and oxygen efficiency.

[0165] In some configurations of the sixth embodiment, the target FdO2 is based at least in part on the most recent change to the target FdO2 prior to the step change.

[0166] In some configurations of the sixth embodiment, the controller is further configured to maintain the target FdO2 for the total duration of the feedforward phase immediately after the step change.

[0167] In some configurations of the sixth embodiment, the feedforward phase ends if the maximum time limit is reached.

[0168] In some configurations of the sixth embodiment, the feedforward phase ends if the measured SpO2 meets or exceeds the target SpO2.

[0169] In some configurations of the sixth embodiment, the controller is further configured to perform a control phase after the feedforward phase.

[0170] In some configurations of the sixth embodiment, the respiratory device includes a patient interface selected from at least one of the following: a face mask, a nasal mask, a nasal pillow mask, a tracheostomy interface, a nasal tube, or an endotracheal tube.

[0171] In some configurations of the sixth embodiment, the nasal cannula is an unsealed nasal cannula.

[0172] In some configurations of the sixth embodiment, the breathing device is configured to deliver a high-flow-rate (NHF) gas stream to the patient.

[0173] In some configurations of the sixth embodiment, the at least one patient sensor is a pulse oximeter.

[0174] In some configurations of the sixth embodiment, the breathing device includes a humidifier.

[0175] In some configurations of the sixth embodiment, the breathing device includes a gas composition sensor configured to determine measured FdO2 during operation of the breathing device, wherein the gas composition sensor is an ultrasonic transducer system.

[0176] In some configurations of the sixth embodiment, the controller is further configured to: receive an indication of the signal quality of the at least one patient sensor; and to apply a weighted approach to the control of FdO2 based at least in part on the signal quality.

[0177] In some configurations of the sixth embodiment, the controller is further configured to use the patient's predicted SpO2 to perform the control phase.

[0178] In some configurations of the sixth embodiment, the breathing device is configured to be portable.

[0179] According to certain features, aspects, and advantages of the seventh embodiment disclosed herein, a respiratory device for providing a gas flow to a patient is provided, the respiratory device comprising: a controller configured to control the gas delivery to the patient using closed-loop control, wherein the controller is configured to: deliver the gas flow to the patient using nasal high flow (NHF); control the oxygen concentration (FdO2) of the gas flow to the patient; receive data from at least one patient sensor indicating the patient's measured oxygen saturation (SpO2); receive the patient's target SpO2; and perform a step change on the FdO2 of the gas flow, wherein the magnitude of the step change is based at least in part on the patient's measured SpO2 and the target SpO2.

[0180] In some configurations of the seventh embodiment, the step change is further based at least in part on the patient’s oxygen efficiency.

[0181] In some configurations of the seventh embodiment, oxygen efficiency is determined at least in part based on measured SpO2 and measured FdO2.

[0182] In some configurations of the seventh embodiment, oxygen efficiency is determined at least in part based on the measured SpO2 divided by the measured FdO2.

[0183] In some configurations of the seventh embodiment, oxygen efficiency is determined at least in part based on the nonlinear relationship between the patient's measured SpO2 and measured FdO2.

[0184] In some configurations of the seventh embodiment, the magnitude of the step change is based at least in part on the change in the target FdO2 over a defined time period prior to the step change.

[0185] In some configurations of the seventh embodiment, the new target FdO2 is calculated at least in part based on the previous target FdO2.

[0186] In some configurations of the seventh embodiment, the controller is configured to perform a feedforward phase after a step change.

[0187] In some configurations of the seventh embodiment, the controller is further configured to maintain FdO2 at the target FdO2 for the total duration of the feedforward phase.

[0188] In some configurations of the seventh embodiment, the feedforward phase ends if the measured SpO2 meets or exceeds the target SpO2.

[0189] In some configurations of the seventh embodiment, the feedforward phase ends if the maximum time limit is reached.

[0190] In some configurations of the seventh embodiment, the respiratory device includes a patient interface selected from at least one of the following: a face mask, a nasal mask, a nasal pillow mask, a tracheostomy interface, a nasal tube, or an endotracheal tube.

[0191] In some configurations of the seventh embodiment, the nasal cannula is an unsealed nasal cannula.

[0192] In some configurations of the seventh embodiment, the at least one patient sensor is a pulse oximeter.

[0193] In some configurations of the seventh embodiment, the breathing device includes a humidifier.

[0194] In some configurations of the seventh embodiment, the breathing device includes a gas composition sensor configured to determine measured FdO2 during operation of the breathing device, and the gas composition sensor is an ultrasonic transducer system.

[0195] In some configurations of the seventh embodiment, the controller is further configured to perform a control phase after the feedforward phase.

[0196] In some configurations of the seventh embodiment, during the control phase, the controller is further configured to use feedback control to control the FdO2 of the gas flow to achieve the target FdO2.

[0197] In some configurations of the seventh embodiment, the controller is further configured to: receive an indication of the signal quality of the at least one patient sensor; and to apply a weighted approach to the control of FdO2 based at least in part on the signal quality.

[0198] In some configurations of the seventh embodiment, the controller is further configured to use the patient's predicted SpO2 to perform the control phase.

[0199] In some configurations of the seventh embodiment, the breathing device is configured to be portable.

[0200] In some configurations of the seventh embodiment, the controller is configured to display a first oxygen efficiency characteristic on the display of the breathing device.

[0201] In some configurations of the seventh embodiment, the controller is configured to display a second oxygen efficiency characteristic on a display of the respiratory device, and the second indication of oxygen efficiency is based at least in part on the patient's oxygen efficiency and the measured respiratory rate.

[0202] In some configurations of the seventh embodiment, the second oxygen efficiency characteristic is calculated by dividing the measured SpO2 by the measured FdO2 and then dividing the result by the measured respiration rate.

[0203] In some configurations of the seventh embodiment, the controller is configured to display a graph or trend line indicating at least one of a first oxygen efficiency characteristic or a second oxygen efficiency characteristic over a defined time period.

[0204] According to certain features, aspects, and advantages of at least one of the embodiments disclosed herein, a respiratory device for providing a gas flow to a patient is provided, the respiratory device comprising: a controller configured to control the gas delivery to the patient using closed-loop control, wherein the controller is configured to: receive patient parameter data indicating the patient's oxygen saturation (SpO2) from at least one sensor; and execute a control phase wherein, during a treatment period, operation of the respiratory device is based at least in part on the patient parameter data.

[0205] In some configurations, the device includes a patient interface selected from at least one of the following: a face mask, a nasal mask, a nasal pillow mask, a tracheostomy interface, a nasal tube, or an endotracheal tube.

[0206] In some configurations, the breathing device is configured to deliver a high-flow-rate (NHF) gas stream to the patient.

[0207] In some configurations, at least one sensor is a pulse oximeter.

[0208] In some configurations, the device includes a supplemental gas inlet valve.

[0209] In some configurations, the controller is configured to control the operation of the supplemental gas inlet valve.

[0210] In some configurations, the supplemental gas inlet valve is a proportional valve.

[0211] In some configurations, the supplemental gas inlet valve is an oxygen inlet valve.

[0212] In some configurations, the device includes an ambient air inlet.

[0213] In some configurations, the oxygen inlet valve and the filter module are in fluid communication, wherein the breathing apparatus is configured to entrain oxygen received from the oxygen inlet valve and ambient air from the ambient air inlet into the filter module.

[0214] In some configurations, the device includes a gas composition sensor configured to determine at least the oxygen content of the gas stream during operation of the breathing device.

[0215] In some configurations, the gas composition sensor is an ultrasonic transducer system.

[0216] In some configurations, the gas composition sensor is located downstream of the blower module of the breathing device.

[0217] In some configurations, the filter module is located upstream of the blower module of the breathing equipment.

[0218] In some configurations, closed-loop control includes the use of a first closed-loop control model configured to determine the target delivered oxygen fraction (FdO2).

[0219] In some configurations, the target FdO2 is determined at least in part based on the target SpO2 and the patient's SpO2.

[0220] In some configurations, the target FdO2 is further based, at least in part, on the measured FdO2.

[0221] In some configurations, closed-loop control includes the use of a second closed-loop control model configured to determine the control signal for the oxygen inlet valve.

[0222] In some configurations, the control signal for the oxygen valve is determined at least in part based on the target FdO2 and the measured FdO2.

[0223] In some configurations, the control signal for the oxygen valve is further determined based, at least in part, on the gas flow rate.

[0224] In some configurations, the controller is configured to switch to manual operation mode when the signal quality of the at least one sensor is below a threshold.

[0225] In some configurations, the controller is set to switch to manual operation mode when the patient's SpO2 is outside the defined limits.

[0226] In some configurations, the controller is configured to: receive an indication of the quality of the signal; and to apply a weighted approach to the control of FdO2 based at least in part on that signal quality.

[0227] In some configurations, the signal quality indication corresponds to a specific SpO2 reading.

[0228] In some configurations, the controller is configured to perform multiple phases during the treatment period of the respiratory device, wherein the controller is configured to: perform a learning phase, during which the controller is configured to generate a patient-specific model; and perform a control phase based at least in part on the patient-specific model.

[0229] In some configurations, during the learning phase, the controller is configured to: receive device parameter data indicating the oxygen concentration of the gas flow provided to the patient; and receive patient parameter data indicating the patient's oxygen saturation from at least one sensor.

[0230] In some configurations, the controller is configured to generate patient-specific models based at least in part on the relationship between the oxygen concentration of the gas stream and the patient's oxygen saturation.

[0231] In some configurations, the learning phase has a maximum duration.

[0232] In some configurations, the learning phase is executed multiple times during the treatment period.

[0233] In some configurations, the controller is further configured to change the oxygen concentration during the learning phase.

[0234] In some configurations, the controller is further configured to change the oxygen concentration after the controller detects that the measured oxygen saturation of the patient parameter has stabilized.

[0235] In some configurations, the change is made to increase the oxygen concentration.

[0236] In some configurations, the change is made to reduce the oxygen concentration.

[0237] In some configurations, patient-specific models are based, at least in part, on sensor signal quality data recorded during the learning phase.

[0238] In some configurations, a patient-specific model determines a delay time, which is the period between a change in the oxygen concentration of the gas stream and a response to the patient's oxygen saturation.

[0239] In some configurations, patient-specific models calculate exponential decay.

[0240] In some configurations, the parameters of the patient-specific model include at least one of the following: delay time, rate of exponential decay, change in oxygen concentration, and change in blood oxygen saturation.

[0241] In some configurations, the controller is further configured to execute a control phase after the patient-specific model meets the defined characterization criteria.

[0242] In some configurations, the defined characterization criteria define the acceptable range of values ​​for each of one or more parameters of a patient-specific model.

[0243] In some configurations, the control phase is configured to be performed using PID control, at least in part, based on a patient-specific model.

[0244] In some configurations, the controller is configured to receive device parameter data indicating the oxygen concentration of the gas flow.

[0245] In some configurations, the controller is configured to predict a patient’s oxygen saturation based at least in part on the oxygen concentration of the gas stream.

[0246] In some configurations, the prediction is based at least in part on one or more patient parameter readings.

[0247] In some configurations, previous predictions of patient parameters are compared with measured patient parameter readings to calculate model error.

[0248] In some configurations, the model error is weighted according to the signal quality.

[0249] In some configurations, model error is used to correct the current prediction.

[0250] In some configurations, predictions are model-based.

[0251] In some configurations, the model is patient-specific.

[0252] In some configurations, the model is generated during the learning phase of the treatment period.

[0253] In some configurations, the control phase is configured to be performed using a predictive algorithm for predicting a patient's oxygen saturation.

[0254] In some configurations, the prediction algorithm is the Smith predictor.

[0255] In some configurations, the output of the prediction algorithm is based at least in part on a patient-specific model.

[0256] In some configurations, the controller is configured to receive input that identifies the characteristics of the patient.

[0257] In some configurations, patient characteristics include at least one of patient type, age, weight, height, or gender.

[0258] In some configurations, the patient type is one of normal, hypercapnia, or user-defined.

[0259] In some configurations, the controller is configured to perform a learning phase, during which the controller is configured to: receive device parameter data indicating the oxygen concentration of the gas flow provided to the patient; receive patient parameter data indicating the patient's oxygen saturation from at least one sensor; calculate one or more model parameters of a patient-specific model based on the device parameter data and the patient parameter data; determine that at least one of the one or more parameters does not meet the patient characterization criteria used to generate the patient-specific model; and perform a control phase, wherein the operation of the respiratory device during the treatment period is at least partially based on a default patient model.

[0260] In some configurations, the default patient model is selected from multiple default patient models, at least in part, based on one or more of the patient characteristics.

[0261] In some configurations, the default patient model is selected from multiple default patient models, at least in part, based on the patient type.

[0262] In some configurations, the controller is further configured to record data corresponding to the measured oxygen concentration and the measured oxygen saturation.

[0263] In some configurations, the controller is further configured to stop recording data after a defined time period.

[0264] In some configurations, the controller is further configured to stop recording data after the patient-specific model meets the defined characterization criteria.

[0265] In some configurations, the device includes a humidifier.

[0266] In some configurations, the equipment includes an integrated blower and humidifier.

[0267] In some configurations, the breathing equipment is set to be portable.

[0268] In some configurations, the breathing device is configured to have a controlled variable flow rate.

[0269] In some configurations, the target FdO2 is further based, at least in part, on signal quality.

[0270] In some configurations, the breathing equipment is configured to change the flow rate by altering the speed of the blower motor.

[0271] Based on certain features, aspects, and advantages of at least one of the embodiments disclosed herein, a method for providing a gas flow to a patient is provided, the method comprising: receiving patient parameter data indicative of the patient's oxygen saturation from at least one sensor by a controller of a respiratory device; and controlling the operation of the respiratory therapy device using closed-loop control during a control phase of treatment, at least in part based on the patient parameter data.

[0272] In some configurations, the method includes performing a learning phase during the treatment period, which includes: receiving device parameter data and patient parameter data from at least one sensor, the device parameter data indicating the oxygen concentration of the gas stream supplied to the patient and the patient parameter data indicating the patient's oxygen saturation; and generating a patient-specific model based at least in part on the relationship between the oxygen concentration of the gas stream and the patient's oxygen saturation.

[0273] In some configurations, the method includes controlling the operation of the respiratory therapy device during the control phase of the treatment period, at least in part based on a patient-specific model.

[0274] In some configurations, the method includes recording data corresponding to the measured oxygen concentration and the measured oxygen saturation.

[0275] In some configurations, the method includes stopping data recording after a defined time period.

[0276] In some configurations, the method includes generating a patient-specific model based at least in part on signal quality data from the at least one sensor recorded during the learning phase.

[0277] In some configurations, the parameters of the patient-specific model include at least one of the following: delay time, rate of exponential decay, change in oxygen concentration, and change in blood oxygen saturation.

[0278] In some configurations, the method includes performing a control phase after the patient-specific model meets the defined characterization criteria.

[0279] In some configurations, the defined characterization criteria define the acceptable range of values ​​for each of one or more parameters of a patient-specific model.

[0280] In some configurations, the method includes using PID control to perform the control phase, at least in part, based on a patient-specific model.

[0281] In some configurations, the method includes using a predictive algorithm to predict a patient's oxygen saturation to perform a control phase.

[0282] In some configurations, the method includes using predicted oxygen saturation during the control phase.

[0283] In some configurations, the prediction algorithm is the Smith predictor.

[0284] In some configurations, the output of the prediction algorithm is based at least in part on a patient-specific model.

[0285] In some configurations, the method includes receiving input that identifies the characteristics of the patient.

[0286] In some configurations, patient characteristics include at least one of patient type, age, weight, height, or gender.

[0287] In some configurations, the method includes changing the oxygen concentration during the learning phase.

[0288] In some configurations, the method includes changing the oxygen concentration during the learning phase after the measured oxygen saturation of the patient parameters has been detected to be stable.

[0289] In some configurations, the change is made to increase the oxygen concentration.

[0290] In some configurations, the change is made to reduce the oxygen concentration.

[0291] In some configurations, the method includes performing the learning phase multiple times during the treatment period.

[0292] In some configurations, the method includes switching to a manual operation mode when the signal quality of the at least one sensor is below a threshold.

[0293] In some configurations, the method includes switching to manual operation mode when the patient's SpO2 is outside the defined limits.

[0294] In some configurations, the method includes using a first closed control loop to determine the target FdO2.

[0295] In some configurations, the target FdO2 is determined at least in part based on the target SpO2 and the patient's SpO2.

[0296] In some configurations, the target FdO2 is further based, at least in part, on the measured FdO2.

[0297] In some configurations, the method includes using a second closed control loop to determine the control signal for the oxygen inlet valve.

[0298] In some configurations, the control signal is determined at least in part based on the target FdO2 and the measured FdO2.

[0299] In some configurations, the control signal for the oxygen valve is further based, at least in part, on the gas flow rate.

[0300] In some configurations, the method includes adjusting the oxygen inlet valve based on a control signal.

[0301] In some configurations, the method includes entraining oxygen from the oxygen inlet valve and ambient air from the ambient air inlet into the filter module of the breathing apparatus.

[0302] In some configurations, the method includes: indicating the quality of the received signal; and applying weights to the control of FdO2 based at least in part on the signal quality.

[0303] In some configurations, the method includes determining at least the oxygen content of the gas stream during operation of the breathing device.

[0304] In some configurations, the target FdO2 is further based, at least in part, on signal quality.

[0305] According to certain features, aspects, and advantages of at least one of the embodiments disclosed herein, a respiratory device for providing a gas flow to a patient is provided, the respiratory device comprising: a controller configured to control gas delivery to the patient, wherein the controller is configured to: perform a learning phase, wherein during the learning phase, the controller is configured to: receive device parameter data indicating the oxygen concentration of the gas flow provided to the patient; receive patient parameter data indicating the patient's oxygen saturation from at least one sensor; and generate a patient-specific model based at least in part on the relationship between the oxygen concentration of the gas flow and the patient's oxygen saturation; and perform a control phase, wherein the operation of the respiratory device during a treatment period is based at least in part on the patient-specific model.

[0306] In some configurations, the device includes a patient interface selected from at least one of the following: a face mask, a nasal mask, a nasal pillow mask, a tracheostomy interface, a nasal tube, or an endotracheal tube.

[0307] In some configurations, the breathing device is a device that delivers a high-flow-rate (NHF) nasal gas stream.

[0308] In some configurations, the sensor is a pulse oximeter.

[0309] In some configurations, the controller is further configured to record data corresponding to the measured oxygen concentration and the measured oxygen saturation.

[0310] In some configurations, the controller is further configured to stop recording data after a defined time period.

[0311] In some configurations, patient-specific models are based, at least in part, on sensor signal quality data recorded during the learning phase.

[0312] In some configurations, a patient-specific model determines a delay time, which is the period between a change in the oxygen concentration of the gas stream and a response to the patient's oxygen saturation.

[0313] In some configurations, patient-specific models calculate exponential decay.

[0314] In some configurations, the parameters of the patient-specific model include at least one of the following: delay time, rate of exponential decay, change in oxygen concentration, and change in blood oxygen saturation.

[0315] In some configurations, the controller is further configured to execute a control phase after the patient-specific model meets the defined characterization criteria.

[0316] In some configurations, the defined characterization criteria define the acceptable range of values ​​for each of one or more parameters of a patient-specific model.

[0317] In some configurations, the control phase is configured to be executed using closed-loop control.

[0318] In some configurations, the control phase is configured to be performed using PID control, at least in part, based on a patient-specific model.

[0319] In some configurations, the control phase is configured to be performed using a predictive algorithm for predicting a patient's oxygen saturation.

[0320] In some configurations, the controller is further configured to use the predicted oxygen saturation during the control phase.

[0321] In some configurations, the prediction algorithm is the Smith predictor.

[0322] In some configurations, the output of the prediction algorithm is based at least in part on a patient-specific model.

[0323] In some configurations, the controller is configured to receive input that identifies the characteristics of the patient.

[0324] In some configurations, patient characteristics include at least one of patient type, age, weight, height, or gender.

[0325] In some configurations, the controller is further configured to change the oxygen concentration during the learning phase.

[0326] In some configurations, the controller is further configured to change the oxygen concentration after the controller detects that the measured oxygen saturation of the patient parameter has stabilized. In some configurations, the change is to increase the oxygen concentration. In some configurations, the change is to decrease the oxygen concentration.

[0327] In some configurations, the learning phase is executed multiple times during the treatment period.

[0328] Furthermore, in accordance with certain features, aspects, and advantages of at least one of the embodiments disclosed herein, a respiratory device for providing a gas flow to a patient is provided, wherein the respiratory device is configured to deliver a high-flow-rate (NHF) gas flow to the patient, the respiratory device comprising: a controller configured to control the operation of the respiratory device and perform multiple phases during a treatment period of the respiratory device, wherein the controller is configured to: perform a learning phase, wherein during the learning phase the controller is configured to generate a patient-specific model; and perform a control phase, wherein the operation of the respiratory device during the treatment period is at least partially based on the patient-specific model.

[0329] In some configurations, during the learning phase, the controller is further configured to measure the properties of the gas flow supplied to the patient. In some configurations, the property is the oxygen concentration of the gas flow.

[0330] In some configurations, during the learning phase, the controller is further configured to use at least one sensor to measure the patient's physiological parameters. In some configurations, the physiological parameter is the patient's oxygen saturation.

[0331] In some configurations, the controller is further configured to: receive device parameter data indicating the oxygen concentration of the gas stream supplied to the patient; and receive patient parameter data indicating the patient's oxygen saturation from at least one sensor. In some configurations, during the learning phase, the controller is further configured to generate a patient-specific model based at least in part on the relationship between the oxygen concentration of the gas stream and the patient's oxygen saturation.

[0332] In some configurations, the at least one sensor is a pulse oximeter.

[0333] In some configurations, the controller is further configured to change the oxygen concentration during the learning phase. In some configurations, the controller is further configured to change the oxygen concentration after the controller detects that the measured oxygen saturation of the patient parameter has stabilized. In some configurations, the change is to increase the oxygen concentration. In some configurations, the change is to decrease the oxygen concentration.

[0334] In some configurations, the controller is further configured to record data corresponding to the measured oxygen concentration and the measured oxygen saturation.

[0335] In some configurations, the controller is further configured to stop recording data after a defined time period.

[0336] In some configurations, the controller is further configured to stop recording data after the patient-specific model meets the defined characterization criteria.

[0337] In some configurations, patient-specific models are based, at least in part, on sensor signal quality data recorded during the learning phase.

[0338] In some configurations, the error values ​​of sensor data can be weighted based on the corresponding signal quality data.

[0339] In some configurations, a patient-specific model determines a delay time, which is the period between a change in the oxygen concentration of the gas stream and a response to the patient's oxygen saturation.

[0340] In some configurations, patient-specific models calculate exponential decay.

[0341] In some configurations, the parameters of the patient-specific model include at least: delay time, rate of exponential decay, changes in oxygen concentration, and changes in blood oxygen saturation.

[0342] In some configurations, the control phase is configured to be executed using closed-loop control.

[0343] In some configurations, the control phase is configured to be performed using PID control, at least in part, based on a patient-specific model.

[0344] In some configurations, the control phase is configured to be performed using a prediction algorithm for predicting the patient's physiological parameters.

[0345] In some configurations, the controller is further configured to use the predicted oxygen saturation during the control phase.

[0346] In some configurations, the prediction algorithm is the Smith predictor.

[0347] In some configurations, the output of the prediction algorithm is based at least in part on a patient-specific model.

[0348] In some configurations, the learning phase is executed multiple times during the treatment period.

[0349] In some configurations, the controller is configured to receive input identifying patient characteristics. In some configurations, patient characteristics include at least one of patient type, age, weight, height, or sex. In some configurations, the patient type is one of normal, hypercapnia, or user-defined type.

[0350] Furthermore, in accordance with certain features, aspects, and advantages of at least one of the embodiments disclosed herein, a breathing device for providing a gas flow to a patient is provided, the breathing device comprising: a controller configured to control the gas delivery to the patient, wherein the controller is configured to: receive device parameter data indicating the oxygen concentration of the gas flow; receive patient parameter data indicating a patient's oxygen saturation reading, wherein the patient's oxygen saturation is affected by the oxygen concentration of the gas flow; and predict the patient's oxygen saturation based at least in part on the oxygen concentration of the gas flow.

[0351] In some configurations, the device includes a patient interface selected from at least one of the following: a face mask, a nasal mask, a nasal pillow mask, a tracheostomy interface, a nasal tube, or an endotracheal tube.

[0352] In some configurations, the breathing device is a device that delivers a high-flow-rate (NHF) nasal gas stream.

[0353] In some configurations, the sensor is a pulse oximeter.

[0354] In some configurations, the prediction is based at least in part on one or more patient parameter readings. In some configurations, previous predictions of patient parameters are compared with measured patient parameter readings to calculate model error.

[0355] In some configurations, the model error is weighted according to the signal quality.

[0356] In some configurations, model error is used to correct the current prediction.

[0357] In some configurations, predictions are model-based.

[0358] In some configurations, the model is patient-specific.

[0359] In some configurations, the model is generated during the learning phase of the treatment period.

[0360] In some configurations, a patient-specific model determines a delay time, which is the period between a change in the oxygen concentration of the gas stream and a response to the patient's oxygen saturation.

[0361] In some configurations, patient-specific models include exponential decay.

[0362] In some configurations, the controller is further configured to use the predicted oxygen saturation during the control phase.

[0363] In some configurations, the predictions are based on the Smith predictor.

[0364] In some configurations, the controller is configured to use closed-loop control to perform control of the gas delivery.

[0365] In some configurations, the model is based at least in part on the signal quality data of the sensors recorded during the learning phase.

[0366] Furthermore, in accordance with certain features, aspects, and advantages of at least one of the embodiments disclosed herein, a breathing device for providing a gas flow to a patient is provided, the breathing device comprising: a controller configured to control the gas delivery to the patient using closed-loop control, wherein the controller is configured to: receive device parameter data indicating the oxygen concentration of the gas flow; receive patient parameter data indicating a patient's oxygen saturation reading, wherein the patient's oxygen saturation is affected by the oxygen concentration of the gas flow; receive an indication of signal quality; and apply a weighted approach to the control of the oxygen concentration based at least in part on the signal quality.

[0367] In some configurations, the signal quality indication corresponds to a specific oxygen saturation reading.

[0368] In some configurations, the device includes a patient interface selected from at least one of the following: a face mask, a nasal mask, a nasal pillow mask, a tracheostomy interface, a nasal tube, or an endotracheal tube.

[0369] In some configurations, the sensor is a pulse oximeter.

[0370] In some configurations, the controller is configured to control gas delivery using a predictive algorithm for predicting a patient's oxygen saturation. In some configurations, the output of the predictive algorithm is at least partially based on a model. In some configurations, the model is patient-specific. In some configurations, the model is generated during a learning phase in the treatment period. In some configurations, the model includes a time delay. In some configurations, the model includes exponential decay. In some configurations, the predictive algorithm is a Smith predictor.

[0371] In some configurations, the controller is configured to receive input that identifies the characteristics of the patient.

[0372] Furthermore, according to certain features, aspects, and advantages of at least one of the embodiments disclosed herein, a respiratory device for providing a gas flow to a patient is provided, the respiratory device comprising: a controller configured to control gas delivery to the patient, wherein the controller is configured to: perform a learning phase, wherein during the learning phase, the controller is configured to: receive device parameter data indicating the oxygen concentration of the gas flow provided to the patient; receive patient parameter data indicating the patient's oxygen saturation from at least one sensor; calculate one or more model parameters of a patient-specific model based on the device parameter data and the patient parameter data; determine that at least one of the one or more parameters does not meet the patient characterization criteria used to generate the patient-specific model; and perform a control phase, wherein the operation of the respiratory device during a treatment period is at least partially based on a default patient model.

[0373] In some configurations, the device includes a patient interface selected from at least one of the following: a face mask, a nasal mask, a nasal pillow mask, a tracheostomy interface, a nasal tube, or an endotracheal tube.

[0374] In some configurations, the breathing device is a device that delivers a high-flow-rate (NHF) nasal gas stream.

[0375] In some configurations, the sensor is a pulse oximeter.

[0376] In some configurations, the controller is further configured to record data corresponding to the measured oxygen concentration and the measured oxygen saturation.

[0377] In some configurations, the one or more mode parameters include at least one of the following: delay time, rate of exponential decay, change in oxygen concentration, or change in blood oxygen saturation.

[0378] In some configurations, the default patient model is selected from one of several default patient models.

[0379] In some configurations, the controller is configured to receive input of one or more patient characteristics. In some configurations, patient characteristics include at least one of patient type, age, weight, height, or gender. In some configurations, patient type is one of normal, hypercapnia, or user-defined type. In some configurations, a default patient model is selected from multiple default patient models based at least in part on the one or more patient characteristics. In some configurations, a default patient model is selected from multiple default patient models based at least in part on patient type.

[0380] In some configurations, the control phase is configured to be executed using closed-loop control.

[0381] In some configurations, the control phase is configured to be performed using PID control, at least in part, based on the default patient model.

[0382] In some configurations, the control phase is configured to be performed using a predictive algorithm for predicting a patient's oxygen saturation.

[0383] In some configurations, the controller is further configured to use the predicted oxygen saturation to control the gas delivery to the patient during the control phase.

[0384] In some configurations, the prediction algorithm is the Smith predictor.

[0385] In some configurations, the output of the prediction algorithm is based at least in part on the default patient model.

[0386] Furthermore, based on certain features, aspects, and advantages of at least one of the embodiments disclosed herein, a method for providing a gas flow to a patient is provided, the method comprising: performing a learning phase during a treatment period by a controller of a respiratory therapy device, the learning phase comprising: receiving device parameter data indicating the oxygen concentration of the gas flow provided to the patient; receiving patient parameter data indicating the patient's oxygen saturation from at least one sensor; generating a patient-specific model based at least in part on the relationship between the oxygen concentration of the gas flow and the patient's oxygen saturation; and controlling the operation of the respiratory therapy device during a control phase of the treatment period based at least in part on the patient-specific model.

[0387] This method may include recording data corresponding to the measured oxygen concentration and the measured oxygen saturation.

[0388] This method may include stopping data recording after a specified time period.

[0389] The method may include generating a patient-specific model based at least in part on signal quality data from the at least one sensor recorded during the learning phase.

[0390] The parameters of the patient-specific model include at least one of the following: delay time, rate of exponential decay, change in oxygen concentration, and change in blood oxygen saturation.

[0391] This method may include performing a control phase after the patient-specific model meets defined characterization criteria. The defined characterization criteria may define an acceptable range of values ​​for each of one or more parameters of the patient-specific model.

[0392] This method may include using PID control, at least in part, to perform the control phase based on a patient-specific model.

[0393] This method may include performing a control phase using a prediction algorithm to predict a patient's oxygen saturation. The method may include using the predicted oxygen saturation during the control phase. The prediction algorithm may be a Smith predictor. The output of the prediction algorithm may be at least partially based on a patient-specific model.

[0394] The method may include receiving input that identifies patient characteristics. Patient characteristics may include at least one of patient type, age, weight, height, or gender.

[0395] This method may include changing the oxygen concentration during the learning phase. The method may include changing the oxygen concentration during the learning phase after the measured oxygen saturation of the patient parameter has been detected to have stabilized. The change may increase the oxygen concentration. The change may decrease the oxygen concentration.

[0396] This method may include performing the learning phase multiple times during the treatment period.

[0397] Features from one or more embodiments or configurations may be combined with features from one or more other embodiments or configurations. Furthermore, more than one embodiment may be used together during a patient's respiratory support process.

[0398] As used in this specification, the term "comprising" means "consisting of at least in part with...". When interpreting each statement using the term "comprising" in this specification, features other than the one or more features following the term may also exist. Related terms such as "comprise" and "comprises" will be interpreted in the same manner.

[0399] References to the ranges of numbers disclosed herein (e.g., 1 to 10) are intended to include references to all rational numbers within that range (e.g., 1, 1.1, 2, 3, 3.9, 4, 5, 6, 6.5, 7, 8, 9, and 10), as well as any range of rational numbers within that range (e.g., 2 to 8, 1.5 to 5.5, and 3.1 to 4.7), and therefore, all subranges of the ranges explicitly disclosed herein are hereby explicitly disclosed. These are merely examples of what is specifically intended to be disclosed, and all possible combinations of values ​​between the enumerated minimum and maximum values ​​should be considered as expressly stated in a similar manner in this application.

[0400] It should be understood that alternative embodiments or configurations may include any or all combinations of two or more of the portions, elements or features illustrated, described or mentioned in this specification.

[0401] The invention can also be broadly defined as any part, element, or feature individually or jointly mentioned or indicated in the description of this application, and any or all combinations of any two or more of the said parts, elements, or features.

[0402] Many structural modifications and a wide variety of embodiments and applications of the invention will be apparent to those skilled in the art, without departing from the scope of the invention as defined in the appended claims. The disclosures and descriptions herein are entirely illustrative and not intended to be limiting in any sense. When reference is made herein to a specific entity having a known equivalent in the field of the invention, such known equivalent is considered to be incorporated herein as if described separately. Attached Figure Description

[0403] Figure 1A The flow therapy device is illustrated in diagram form.

[0404] Figure 1B The diagram illustrates a sensing circuit board that includes a flow sensor that can be used in a flow therapy device.

[0405] Figures 1C to 1D The illustration shows schematic diagrams of various ultrasonic transducer configurations for sensor systems using cross-flow beams.

[0406] Figures 1E to 1F The illustration shows schematic diagrams of various ultrasonic transducer configurations for sensor systems using downstream beams.

[0407] Figure 2 The diagrams illustrate the various operational stages of the flow therapy device.

[0408] Figure 3The graphs shown illustrate the fitting trend lines of the patient models.

[0409] Figure 4 The diagram illustrates the iterative trend line of the patient model.

[0410] Figure 5 The graph illustrates the signal hysteresis between the predicted and actual SpO2 values.

[0411] Figure 6 The illustration shows a Smith predictor used in conjunction with a PID controller.

[0412] Figure 7 The figure shows a graph of the predicted SpO2 values ​​with a time delay.

[0413] Figure 8 The diagrams show the outputs of different computational models used for PID controllers.

[0414] Figure 9A The diagram illustrates a flowchart of a method for controlling the operation of a flow therapy device during a flow therapy period.

[0415] Figure 9B The diagram illustrates a flowchart of the sub-processes used in the learning phase of the flow therapy period.

[0416] Figure 9C The diagram illustrates a flowchart of a sub-process used in the control phase of the flow therapy period.

[0417] Figure 10 This is a schematic diagram of a closed-loop control system.

[0418] Figure 11 The diagram illustrates the process used to calculate a patient's oxygen efficiency.

[0419] Figure 12 The diagrams illustrate the various operational stages of the flow therapy device.

[0420] Figure 13A The diagram illustrates a flowchart of a method for controlling the operation of a flow therapy device during a flow therapy period.

[0421] Figure 13B The diagram illustrates a flowchart of the sub-processes used in the setup phase of the flow therapy period.

[0422] Figure 13C The diagram illustrates a flowchart of a sub-process used in the control phase of the flow therapy period.

[0423] Figure 14This is a first bottom perspective view of the main housing of the flow therapy device, showing a recess located inside the housing for a motor and / or sensor module subassembly.

[0424] Figure 15 This is a second bottom perspective view of the main housing of the flow therapy device, showing recesses for the motor and / or sensor module subassemblies.

[0425] Figure 16 It is a perspective view of the motor and / or sensor sub-assemblies of the flow therapy device, the bottom side of the main housing, and the fixed bend.

[0426] Figure 17 This is an exploded perspective view of the components of the motor and / or sensor subassembly, which schematically shows the gas flow path through the subassembly via arrows.

[0427] Figure 18 This is a bottom side view of the cover and sensing PCB of the motor and / or sensor sub-assembly, showing the location of the sensor.

[0428] Figure 19 This is a rear perspective view of a flow therapy device with its rear edge cut off from the adjacent device, showing the arrangement of a portion of the main housing that provides recesses for receiving motor and / or sensor subassemblies.

[0429] Figure 20 This is a left front perspective view of the flow therapy device.

[0430] Figure 21 This is a left front perspective view of the flow therapy device.

[0431] Figure 22 This is a partial cross-sectional view of the valve module and filter module from the left front perspective.

[0432] Figure 23 This is a schematic diagram of the gas flow path for the filter module and valve module, where solid arrows represent oxygen (or another gas) flow and dashed arrows represent ambient air flow.

[0433] Figure 24 This is a cross-sectional view showing the gas flow path through the filter module and valve module.

[0434] Figure 25 This is a rear top perspective view of the valve module in the first configuration.

[0435] Figure 26 It is a rear-view top perspective view showing the gas flow path through the valve module of the first configuration, where solid arrows represent oxygen (or another gas) flow and dashed arrows represent ambient air flow.

[0436] Figure 27This is a cross-sectional view of the valve module in the first configuration.

[0437] Figure 28 It is a cross-sectional view showing the connection of the valve and valve manifold of the valve module in the first configuration, as well as the gas flow path through both. Detailed Implementation

[0438] Patients with a variety of health conditions and diseases can benefit from oxygen therapy. For example, patients with chronic obstructive pulmonary disease (COPD), pneumonia, asthma, bronchopulmonary dysplasia, heart failure, cystic fibrosis, sleep apnea, lung disease, respiratory trauma, or acute respiratory distress receive preoperative and postoperative oxygen delivery, and other conditions or diseases can also benefit from oxygen therapy. A common approach to addressing this is by supplying supplemental oxygen to the patient to prevent their blood oxygen saturation (SpO2) from dropping too low (e.g., below about 90%). However, supplying too much oxygen to a patient can lead to over-oxygenation of their blood and is also considered dangerous. Generally, a patient's SpO2 is maintained within the range of about 80% to about 99%, preferably about 92% to about 96%, although these ranges may vary depending on the patient's condition. Due to various factors such as respiratory rate, tidal volume, heart rate, activity level, height, weight, age, sex, and others, there is no single prescribed level of supplemental oxygen that can consistently achieve a targeted SpO2 response for each patient within a specific range. Individual patients will require regular monitoring and adjustment of their fractional oxygen (FdO2) to ensure they receive the correct amount to achieve their target SpO2. Achieving correct and consistent SpO2 is a critical factor in the treatment of patients with a variety of health conditions or diseases. Furthermore, patients with these health problems can benefit from systems that automatically control oxygen saturation. This disclosure applies to a wide range of patients requiring rapid and accurate oxygen saturation control.

[0439] The fractional oxygen (FdO2) delivered to the patient can be manually controlled. Clinicians can manually adjust the oxygen supply valve to change the flow rate or fractional oxygen delivered to the patient. Clinicians can use patient monitors (such as pulse oximeters) to determine the patient's SpO2 level. Clinicians can continue to manually adjust the amount of oxygen delivered to the patient until the patient's SpO2 level reaches the determined level.

[0440] One problem with the current approach is that when clinicians attempt to achieve a specific SpO2 level, they will need to change the FdO2, wait for the SpO2 reading to stabilize, and then apply further changes to the FdO2 until SpO2 is at the desired level. This repetitive process of changing FdO2 and waiting for SpO2 to stabilize can be very time-consuming, especially when multiple patients require the same treatment.

[0441] Another issue is the accuracy of achievable SpO2. The accuracy of SpO2 control can depend on the fineness of the increments for both the displayed SpO2 and the selectable FdO2. As clinicians may approach the ideal SpO2 and decide not to make further changes to FdO2, the increasing amount of time required to obtain increasingly accurate values ​​can hinder accuracy.

[0442] Another issue is that other factors may cause a patient's SpO2 level to change over time, while FdO2 remains unchanged. This will require regular monitoring and adjustment of the patient's FdO2 to maintain their SpO2 at the correct value. This process can be quite time-consuming for clinicians. Furthermore, if the intervals between adjustments are too long, the patient risks their SpO2 deviating too far from the target level.

[0443] While some systems attempt to perform similar operations, many suffer from further problems stemming from the difficulty in measuring patient oxygen saturation. The signals generated by pulse oximeters and similar devices lag far behind the corresponding changes in the delivered oxygen fraction. Furthermore, oxygen saturation readings can become inaccurate due to various factors.

[0444] This disclosure provides closed-loop control of a flow therapy device that allows patients or clinicians to set a target SpO2 instead of a target FdO2. The flow therapy device can automatically adjust its FdO2 to achieve the target SpO2 based on the values ​​of the target SpO2, the current SpO2, and the current FdO2. Automatic FdO2 control helps to quickly and accurately adjust FdO2 until the target SpO2 is achieved. In some configurations, the system can generate a patient-specific model for each patient at the start of treatment. By adjusting FdO2 as needed to remain within the target SpO2 range rather than requiring constant monitoring by the clinician, the flow therapy device can achieve greater accuracy in reaching the target SpO2.

[0445] This disclosure provides a flow therapy device that can implement one or more closed-loop control systems. The features of the closed-loop control system can be combined with features of one or more configurations disclosed herein.

[0446] The flow therapy device can operate in automatic or manual mode. In automatic mode, the controller can automatically control FdO2 based on a target FdO2 determined according to a target SpO2 and / or the measured SpO2. A valve at the oxygen inlet can be connected to the controller, which can control the oxygen concentration in the gas flow based on the target FdO2. The controller can execute a control algorithm that measures the FdO2 output by the flow therapy device. FdO2 measurements can be performed periodically at a defined frequency (e.g., the maximum sampling rate of the gas concentration sensor or at a lower frequency), or non-periodically. The controller can continue to adjust the valve at the oxygen inlet until the measured FdO2 reaches the target FdO2. The measured FdO2 can be determined by a gas composition sensor.

[0447] In manual mode, the controller can receive target FdO2 from a clinician or patient, for example, via a user interface. The controller can automatically control FdO2 based on the received target FdO2. The controller can control the oxygen concentration in the gas flow by controlling the oxygen inlet valve based on the target FdO2. The controller can execute a control algorithm that uses the measured FdO2 output from a flow therapy device (e.g., a gas composition sensor of the flow therapy device) as input to the controller. FdO2 measurements can be performed periodically at a defined frequency (e.g., the maximum sampling rate of the gas concentration sensor or at a lower frequency) or non-periodically. The controller can continue to adjust the valve at the oxygen inlet to drive the measured FdO2 toward the target FdO2. The measured FdO2 can be determined by the gas composition sensor.

[0448] When a patient's SpO2 is outside the acceptable range, the flow therapy device can be configured to switch from automatic mode to manual mode. In some cases, the flow therapy device reverts to manual mode when the patient's SpO2 is outside the patient limits (above or below the patient limits), or if the patient's SpO2 remains within the limits for a defined period after the start of treatment. The flow therapy device may also revert to manual mode when the patient sensor's signal quality falls below a threshold level for a defined period. In some configurations, the flow therapy device may trigger an alarm when switching from automatic to manual mode. After triggering an alarm, the flow therapy device may continue operating in automatic mode. The flow therapy device provides the user with the option to disable alarms or exit automatic mode via a graphical user interface.

[0449] In automatic mode, the controller can utilize two control loops. The first control loop can determine the target FdO2 based on the target SpO2. The second control loop can use the target FdO2 output from the first control loop and the measured FdO2 to output an oxygen inlet valve control signal. In manual mode, the controller can use only the second control loop, which can receive the target FdO2 from user input or a default value output.

[0450] During high-flow therapy, when the delivered gas flow rate meets or exceeds the patient's peak inspiratory requirement, the oxygen concentration measured in the device (delivered oxygen fraction (FdO2)) can be substantially the same as the oxygen concentration inhaled by the user (inhaled oxygen fraction (FiO2)). This means that the volume of gas delivered to the patient by the device during inspiration meets or exceeds the volume of gas inhaled by the patient during inspiration. High-flow therapy helps prevent entrainment of ambient air during the patient's inhalation and flushing out exhaled air from the patient's airways. As long as the delivered gas flow rate meets or exceeds the patient's peak inspiratory requirement, entrainment of ambient air is prevented, and the FdO2 of the gas delivered by the device is substantially the same as the FiO2 of the gas inhaled by the patient.

[0451] Flow therapy equipment

[0452] Figure 1A The image shows a flow therapy device 10. Device 10 may include a main housing 100 containing a flow generator 11 (e.g., a blower) arranged in a motor / impeller configuration, an optional humidifier 12, a controller 13, and a user interface 14 (including, for example, a display and input devices such as buttons, a touchscreen, etc.). The controller 13 may be configured or programmed to control the operation of the device. For example, the controller may control components of the device, including but not limited to: operating the flow generator 11 to generate gas flows (flows of individual gases) for delivery to a patient; operating the humidifier 12 (if present) to humidify and / or heat the generated gas flows; controlling the oxygen flow into the flow generator blower; receiving user input from the user interface 14 to reconfigure and / or perform user-defined operations on the device 10; and outputting information to the user (e.g., on the display). The user may be a patient, a healthcare professional, or any other person interested in using the device. As used herein, “gas flow” can refer to any gas flow that can be used in a breathing aid or breathing device, such as an ambient air flow, a flow that includes essentially 100% oxygen, a flow that includes some combination of ambient air and oxygen, and / or the like.

[0453] The patient breathing tube 16 is connected at one end to a gas outlet 21 in the housing 100 of the flow therapy device 10. At the other end, the patient breathing tube 16 is connected to a patient interface 17, such as an unsealed nasal cannula with a manifold 19 and a nasal plug 18. Alternatively, the patient breathing tube 16 may be connected to an interface, nasal mask, nasal pillow mask, endotracheal tube, tracheostomy interface, and / or the like. The gas flow generated by the flow therapy device 10 can be humidified and delivered to the patient via the patient tube 16 and the cannula 17. The patient tube 16 may have a heating wire 16a to heat the gas flow traveling to the patient. The heating wire 16a may be controlled by a controller 13. The patient tube 16 and / or the patient interface 17 may be considered part of the flow therapy device 10, or alternatively, peripheral to it. The flow therapy device 10, the breathing tube 16, and the patient interface 17 together form a flow therapy system.

[0454] Controller 13 can control flow generator 11 to generate a gas flow of desired volume. Controller 13 can also control supplemental oxygen inlet to allow supplemental oxygen delivery, humidifier 12 (if present) to humidify and / or heat the gas flow to an appropriate level, and / or so on. The gas flow is led to the patient via patient catheter 16 and cannula 17. Controller 13 can also control heating elements in humidifier 12 and / or heating elements 16a in patient catheter 16 to heat the gas to a desired temperature to achieve the patient's desired level of treatment and / or comfort. Controller 13 can be programmed with a suitable target temperature for the gas flow or can determine a suitable target temperature for the gas flow.

[0455] Oxygen inlet port 28 may include a valve through which pressurized gas can enter a flow generator or blower. The valve controls the oxygen flow into the flow generator or blower. The valve can be any type of valve, including proportional valves or two-position valves. The oxygen source can be an oxygen cylinder or a hospital oxygen supply system. Medical-grade oxygen typically has a purity between 95% and 100%. Lower purity oxygen sources may also be used. Examples of valve modules and filters are disclosed in U.S. Provisional Application No. 62 / 409,543, filed October 18, 2016, entitled “Valve Modules and Filter,” and U.S. Provisional Application No. 62 / 488,841, filed April 23, 2017, entitled “Valve Modules and Filter,” both of which are incorporated herein by reference in their entirety. The following is about… Figures 17 to 25 Let's discuss the valve module and filter in more detail.

[0456] The flow therapy device 10 can measure and control the oxygen content of the gas delivered to the patient, and therefore measure and control the oxygen content of the gas inhaled by the patient. During high-flow therapy, the high flow rate of the delivered gas meets or exceeds the patient's peak inspiratory demand. This means that the volume of gas delivered to the patient by the device during inspiration meets or exceeds the volume of gas inhaled by the patient during inspiration. Therefore, high-flow therapy helps prevent the entrainment of ambient air during the patient's inhalation and flushes out exhaled air from the patient's airway. As long as the flow rate of the delivered gas meets or exceeds the patient's peak inspiratory demand, the entrainment of ambient air is prevented, and the gas delivered by the device is substantially the same as the gas inhaled by the patient. Therefore, the oxygen concentration measured in the device (delivered oxygen fraction (FdO2)) will be substantially the same as the oxygen concentration inhaled by the user (inhaled oxygen fraction (FiO2)), and thus such terms can be considered equivalent.

[0457] Operating sensors 3a, 3b, 3c (e.g., flow sensors, temperature sensors, humidity sensors, and / or pressure sensors) can be placed in various locations within the flow therapy device 10. Additional sensors (e.g., sensors 20, 25) can be placed in various locations on the patient catheter 16 and / or cannula 17 (e.g., temperature sensor 29 may be present at or near the end of the inspiratory tube). Output from the sensors can be received by the controller 13 to assist the controller in operating the flow therapy device 10 in a manner that provides appropriate therapy. In some configurations, providing appropriate therapy includes meeting the patient's peak inspiratory demand. The device 10 may have a transmitter and / or receiver 15 to enable the controller 13 to receive signals 8 from the sensors and / or control various components of the flow therapy device 10, including but not limited to the flow generator 11, humidifier 12, and heating wire 16a, or accessories or peripheral devices associated with the flow therapy device 10. Additionally or alternatively, the transmitter and / or receiver 15 can transmit data to a remote server or enable remote control of the device 10.

[0458] After oxygen and ambient air have been mixed, oxygen can be measured by placing one or more gas composition sensors (such as an ultrasonic transducer system, also known as an ultrasonic sensor system). This measurement can be performed within the device, delivery tubing, patient interface, or any other suitable location.

[0459] The oxygen concentration can also be measured using flow sensors on at least two of the ambient air inlet conduit, oxygen inlet conduit, and final delivery conduit to determine the flow rates of at least two gases. The oxygen concentration of the final gas composition can be calculated by determining the flow rates of the two inlet gases or one inlet gas, along with a total flow rate and an assumed or measured oxygen concentration (approximately 20.9% for ambient air and approximately 100% for oxygen). Alternatively, flow sensors can be placed at all three inlets—ambient air inlet conduit, oxygen inlet conduit, and final delivery conduit—to allow for redundancy and test the correct operation of each sensor by checking the consistency of the readings. Other methods for measuring the oxygen concentration delivered by the flow therapy device 10 can also be used.

[0460] The flow therapy device 10 may include a patient sensor 26 (e.g., a pulse oximeter or patient monitoring system) to measure one or more physiological parameters of the patient (e.g., the patient's oxygen saturation (SpO2), heart rate, respiratory rate, perfusion index) and provide a measure of signal quality. The sensor 26 may communicate with the controller 13 via a wired connection or via communication through a wireless transmitter on the sensor 26. The sensor 26 may be a disposable adhesive sensor designed to attach to the patient's finger. The sensor 26 may also be a non-disposable sensor. Sensors designed for different age groups and attached to different locations on the patient are available and can be used with the flow therapy device. The pulse oximeter will be attached to the user (typically on their finger), although other locations (e.g., the earlobe) are also an option. The pulse oximeter will be connected to a processor in the device and will continuously provide a signal indicating the patient's oxygen saturation. The patient sensor 26 may be a hot-swappable device that can be attached or interchanged during operation of the flow therapy device 10. For example, patient sensor 26 can connect to flow therapy device 10 via a USB interface or using a wireless communication protocol (such as, for example, near field communication, WiFi, or Bluetooth®). When patient sensor 26 disconnects during operation, flow therapy device 10 can continue operating in its previous operating state for a defined period of time. After the defined period of time, flow therapy device 10 can trigger an alarm, switch from automatic mode to manual mode, and / or completely exit control mode (e.g., automatic or manual mode). Patient sensor 26 can be a bedside monitoring system or other patient monitoring system that communicates with flow therapy device 10 via a physical or wireless interface.

[0461] The flow therapy device 10 may include a high-flow therapy device. As used herein, “high-flow” therapy refers to the application of gas to the patient’s airway at a relatively high flow rate that meets or exceeds the patient’s peak inspiratory requirement. The flow rate used to achieve “high flow” may be any of the flow rates listed below. For example, in some configurations, for adult patients, “high-flow therapy” may refer to delivering gas to the patient at a flow rate greater than or equal to about 10 liters per minute (10 LPM), such as between about 10 LPM and about 100 LPM, or between about 15 LPM and about 95 LPM, or between about 20 LPM and about 90 LPM, or between about 25 LPM and 75 LPM, or between about 25 LPM and about 85 LPM, or between about 30 LPM and about 80 LPM, or between about 35 LPM and about 75 LPM, or between about 40 LPM and about 70 LPM, or between about 45 LPM and about 65 LPM, or between about 50 LPM and about 60 LPM. In some configurations, for newborn, infant, or pediatric patients, "high-flow therapy" may refer to delivering gas to the patient at a flow rate greater than 1 LPM, such as between about 1 LPM and about 25 LPM, or between about 2 LPM and about 25 LPM, or between about 2 LPM and about 5 LPM, or between about 5 LPM and about 25 LPM, or between about 5 LPM and about 10 LPM, or between about 10 LPM and about 25 LPM, or between about 10 LPM and about 20 LPM, or between about 10 LPM and about 15 LPM, or between about 20 LPM and 25 LPM. High-flow therapy devices for adult, newborn, infant, or pediatric patients may deliver gas to the patient at a flow rate between about 1 LPM and about 100 LPM or at any of the subranges outlined above. Flow therapy device 10 may deliver up to 100% of any concentration of oxygen (e.g., FdO2) at any flow rate between about 1 LPM and about 100 LPM. In some configurations, any of these flow rates can be combined with oxygen concentrations (FdO2) of approximately 20%-30%, 21%-30%, 21%-40%, 30%-40%, 40%-50%, 50%-60%, 60%-70%, 70%-80%, 80%-90%, and 90%-100%. In some combinations, the flow rate can be between approximately 25 LPM and 75 LPM and combined with oxygen concentrations (FdO2) of approximately 20%-30%, 21%-30%, 21%-40%, 30%-40%, 40%-50%, 50%-60%, 60%-70%, 70%-80%, 80%-90%, and 90%-100%.In some configurations, the flow therapy device 10 may include safety thresholds when operating in manual mode to prevent the user from delivering too much oxygen to the patient.

[0462] High-flow therapy can be administered through the user's nostrils and / or orally, or via a tracheostomy interface. High-flow therapy delivers gas to the user at a flow rate at or above the user's expected peak inspiratory flow rate requirement. High-flow therapy creates a flushing effect in the nasopharynx, flushing the anatomical dead space of the upper airway with a high gas flow. This generates a reserve of fresh gas for each breath while minimizing rebreathing of nitrogen and carbon dioxide. Furthermore, meeting inspiratory needs and flushing the airway are important when attempting to control a patient's FdO2. High-flow therapy can be delivered using an unsealed patient interface, such as a nasal cannula. A nasal cannula can be configured to deliver breathing gas to the user's nostrils at a flow rate exceeding the user's expected peak inspiratory flow rate requirement.

[0463] As used herein, the term "unsealed patient interface" can refer to an interface that provides a pneumatic link between a patient's airway and a source of gas flow that does not completely obstruct the patient's airway (e.g., from flow generator 11). An unsealed pneumatic link may include an obstruction of less than approximately 95% of the patient's airway. An unsealed pneumatic link may include an obstruction of less than approximately 90% of the patient's airway. An unsealed pneumatic link may include an obstruction between approximately 40% and approximately 80% of the patient's airway. The airway may include one or more of the patient's nostrils or mouth. For nasal intubation, the airway passes through the nostrils.

[0464] The flow generator or blower 11 may include an ambient air inlet port 27 to entrain ambient indoor air into the blower. The flow therapy device 10 may also include an oxygen inlet port 28 leading to a valve through which pressurized gas enters the flow generator or blower 11. This valve controls the oxygen flow into the flow generator or blower 11. The valve can be any type of valve, including proportional valves or two-position valves.

[0465] The blower can operate at motor speeds greater than about 1,000 RPM and less than about 30,000 RPM, greater than about 2,000 RPM and less than about 21,000 RPM, or any of the foregoing values. The operation of the blower can mix the gas entering the blower through the inlet port. Using a blower as a mixer can reduce the pressure drop that would otherwise occur in systems with a separate mixer (e.g., a static mixer including baffles), since mixing requires energy.

[0466] Additional reference Figure 1BThe diagram illustrates a sensing circuit board 2200 that can be implemented in a flow therapy device 10. The sensing circuit board 2200 can be positioned within a sensor chamber such that it is at least partially immersed in the gas flow. The gas flow exits the blower 11 via a duct and enters a flow path within the sensor chamber. At least some of the sensors on the sensing circuit board 2200 can be positioned within the gas flow to measure the properties of the gas within the flow. After passing through the flow path in the sensor chamber, the gas can exit and reach the humidifier 12 described above.

[0467] The sensing circuit board 2200 may be a printed sensing circuit board (PCB). Alternatively, the circuitry on board 2200 may be constructed using wires connecting electronic components, rather than being printed on the circuit board. At least a portion of the sensing circuit board 2200 may be mounted outside the gas flow. The gas flow may be generated by the flow generator 11 described above. The sensing circuit board 2200 may include an ultrasonic transducer 2204. The sensing circuit board 2200 may include one or more thermistors 2205. The thermistors 2205 may be configured to measure the temperature of the gas flow. The sensing circuit board 2200 may include a thermistor flow sensor 2206. The sensing circuit board 2200 may include other types of sensors, such as humidity sensors (including humidity-only sensors to be used with a separate temperature sensor, and combined humidity and temperature sensors), sensors for measuring atmospheric pressure, sensors for measuring differential pressure, and / or sensors for measuring gauge pressure. The thermistor flow sensor 2206 may include a hot-wire flow meter, such as platinum wire, and / or a thermistor (e.g., a negative temperature coefficient (NTC) thermistor or a positive temperature coefficient (PTC) thermistor). Other non-limiting examples of heated temperature sensing elements include glass- or epoxy-encapsulated thermistors, or unencapsulated thermistors. The thermistor flow sensor 2206 may be configured to measure gas flow rate by supplying a constant power supply, maintaining a constant sensor temperature, or maintaining a constant temperature difference between the sensor and the gas flow.

[0468] The sensing circuit board 2200 may include a first portion 2201 and a second portion 2202. The first portion 2201 may be positioned within the gas flow path, while the second portion 2202 may be positioned outside the gas flow path. The direction of gas flow is... Figure 1B The direction of the gas flow can be straight, or as indicated by arrow 2203. Figure 1B The image shown is curved.

[0469] Positioning one or more of the thermistor 2205 and / or thermistor flow sensor 2206 downstream of the combined blower and mixer allows the heat supplied to the gas flow from the blower to be taken into account. Furthermore, immersing the temperature-based flow sensor in the flow path can improve measurement accuracy, as the sensor immersed in the flow is more likely to experience the same conditions (e.g., temperature) as the gas flow, and thus provides a better representation of the gas characteristics.

[0470] Sensing circuit board 2200 may include an ultrasonic transducer, transceiver, or sensor to measure the gas properties of a gas flow, such as a gas composition or concentration of one or more gases within the gas flow. As will be understood, any suitable transducer, transceiver, or sensor may be mounted to sensing circuit board 2200. In this configuration, the sensing circuit board includes an ultrasonic transducer system (also known as an ultrasonic sensor system) that uses ultrasonic waves or sound waves to determine gas concentration. The following section discusses… Figures 1C to 1F To describe the various sensor configurations.

[0471] Ultrasonic transducer systems can determine the relative gas concentrations of two or more gases in a gas stream. An ultrasonic transducer system can be configured to measure the oxygen fraction in a bulk gas stream consisting of atmospheric air enhanced with supplemental oxygen, the atmospheric air being essentially a binary gas mixture of nitrogen (N2) and oxygen (O2). It will also be understood that the ultrasonic transducer system can be configured to measure the gas concentrations of other enhancing gases (including nitrogen (N2) and carbon dioxide (CO2)) already mixed with the atmospheric air in the gas stream. The ultrasonic transducer can determine the gas concentrations in the gas stream at relatively high frequencies. For example, the ultrasonic transducer can output the measured FdO2 value at the sensor's maximum sampling rate or at a frequency lower than the maximum sampling rate, such as between approximately 1 Hz and 200 Hz, between approximately 1 Hz and 100 Hz, between approximately 1 Hz and 50 Hz, and between approximately 1 Hz and 25 Hz.

[0472] In some configurations, the sensing circuit board 2200 includes a pair of ultrasonic transducers provided on opposite sides of the sensing circuit board. Various alternative configurations of the ultrasonic transducers can be used to sense the characteristics of airflow by emitting and receiving ultrasonic beams or pulses.

[0473] The distance between the ultrasonic transducers 2204 at opposite ends of the sensing circuit board 2200 affects the measurement resolution. An increased distance between each of the ultrasonic transducers 2204 can reduce proportional or fractional errors because the overall measured length will have a certain amount of error, and if the length increases, the proportion of error generated during measurement is smaller than the proportion of error for a shorter length. Therefore, the total measurement uncertainty is reduced. Increasing the distance can also improve measurement resolution and accuracy because it allows for a longer time period of acoustic signals between the ultrasonic transducers 2204. However, an increased distance can result in a weaker signal.

[0474] The ultrasonic transducers 2204 can be positioned such that the space between the ultrasonic transducers 2204 at least partially coincides with the flow path. In some configurations, the ultrasonic transducers are positioned at opposite ends of the sensing circuit board. Because the entire surface of the flow path is exposed to the acoustic path, sound waves propagate through all the gas in the flow path. Wave averaging can occur over the entire flow path rather than a segment of it. Averaging over a longer distance reduces errors and decreases dependence on air-oxygen mixing. The ultrasonic transducers can be configured to measure gas properties from any angle relative to the flow path.

[0475] Instead of positioning the sensor outside the flow path or module, positioning it within the flow path or module allows both transducers 2204 to operate within a smaller temperature range relative to each other, or both to operate at essentially the same temperature (i.e., the temperature of the gas flow). Since transducers are temperature-sensitive, placing them at a substantially uniform temperature improves accuracy. Furthermore, positioning the sensor along the flow path allows for measurements and calculations that take into account the effects of gas velocity, making it possible to remove the influence of gas velocity from sensor measurements.

[0476] The ultrasonic transducer system is configured as an ultrasonic binary gas sensing system. Binary gas analysis using ultrasound is based on sensing the velocity of sound pulses passing through a gas sample, in this case, the gas sample being the bulk or primary flow of gas flowing through the sensing channel of the sensor housing. The velocity of sound is a function of the gas's average molecular weight and temperature. The system can receive sensor signals indicating the temperature of the gas flowing between the ultrasonic transducers in the beam path. Knowing the sensed velocity of sound and the sensed temperature, the gas composition in the gas flow can be determined or calculated. Specifically, measurements of the velocity of sound traversing the sensing channel can be used to derive the ratio of two known gases by referencing empirical relationships, standard algorithms, or data stored in lookup tables, as is known in the field of ultrasonic binary gas analysis. It will be understood that, alternatively, if no temperature sensor is used, an estimate of the temperature of the gas flow in the ultrasonic transducer beam path can be used in the calculations of the binary gas analysis. In such alternative embodiments, the temperature of the gas flow can be regulated or controlled to be within a narrow temperature band so that an estimate of the temperature of the gas flow in the beam path can be used.

[0477] In some configurations, the flow therapy device may also include a humidity sensor located in the flow path and configured to generate a humidity signal indicating the humidity of the airflow passing through the sensor assembly. In such embodiments, the gas composition can be determined by sensing the velocity of sound and sensing the temperature and / or sensing the humidity. The humidity sensor may be a relative humidity sensor or an absolute humidity sensor. In some embodiments, the gas composition can be determined based on the sensed velocity of sound and sensed humidity without a temperature sensor.

[0478] Ultrasonic transducer systems can be used to measure the ratio of any two known gases in a gas composition. An ultrasonic transducer system can determine the relative gas concentrations in an air mixture mixed with supplemental oxygen, which is essentially equivalent to a nitrogen / oxygen mixture. In such binary gas mixtures, by monitoring the velocity of sound and taking temperature into account, the average molecular weight of the gases can be determined, and thus the relative concentrations of the two gases can be determined. From this ratio, the oxygen or nitrogen fraction of the gas stream can be deduced.

[0479] refer to Figures 1C to 1F Various configurations of ultrasonic transducers will be described for gas composition sensing systems, which are used to sense the speed of sound through an airflow by emitting and receiving ultrasonic beams or pulses. Similar reference numerals denote similar parts.

[0480] refer to Figure 1CThe transducer configuration 2300 provides an arrangement in which a pair of transducers 2302, 2304 are positioned opposite each other and on opposite sides of the sensing channel 2306, wherein the gas flow path direction is generally indicated by 2308. In this configuration, each of the transducers 2302, 2304 is driven as a dedicated transmitter or receiver, such that an ultrasonic pulse 2310 is unidirectionally transmitted across the gas flow path from the transmitter to the receiver transducer. As shown, the transducer pair is aligned relative to the air flow path direction 2308 (i.e., without shifting upstream or downstream of each other) and is configured to transmit transverse pulses substantially perpendicular to the gas flow path direction.

[0481] refer to Figure 1D The illustration shows an alternative transducer configuration 2320, in which a pair of transducers 2322, 2324 are provided opposite each other on opposite sides of a sensing channel, but each transducer can operate as both a transmitter and a receiver (i.e., the transducer is an ultrasonic transmitter-receiver or transceiver). In this configuration, bidirectional ultrasonic pulses 2326 can be transmitted between the transducer pair 2322, 2324. For example, pulses can be transmitted back and forth between the transducers or in any other sequence or pattern. Again, the transducer pair is aligned relative to the gas flow path direction and is configured to transmit crossflow pulses substantially perpendicular to the gas flow path direction.

[0482] refer to Figure 1E The illustration shows an alternative transducer configuration 2360, in which a pair of transducers 2362, 2364 are located at opposite ends of a sensing channel 2306 and are positioned opposite each other, with the gas flow path direction or axis generally indicated by 2308. In this configuration 2360, each of the transducers 2362, 2364 is driven as a dedicated transmitter or receiver, such that a downstream ultrasonic pulse 2366 is unidirectionally emitted in a beam path between the transmitter and receiver, which is substantially aligned with or parallel to the gas flow path axis 2308 in the sensing channel 2306. In the illustrated embodiment, the transmitter is upstream of the receiver, but it will be understood that the opposite arrangement can be used. With this configuration, a flow sensor is provided in the sensing channel to provide a flow signal indicating the flow rate of the airflow in the sensing channel. It will be understood that the velocity of sound in the sensing channel can be derived or determined in a manner similar to that previously described, and the flow signal is utilized in signal processing to remove or compensate for the gas flow rate in the calculated velocity of the acoustic signal.

[0483] refer to Figure 1F The illustration shows the alternative transducer configuration 2370, in which and Figure 1ESimilar to the previous configuration, a pair of transducers 2372, 2374 are provided at opposite ends of the sensing channel and are positioned opposite each other. However, each transducer can operate as both a transmitter and a receiver (i.e., the transducer is an ultrasonic transmitter-receiver or transceiver). In this configuration, bidirectional downstream ultrasonic pulses 2376 can be transmitted between the transducer pair 2372, 2374. For example, pulses can be transmitted alternately back and forth between the transducers or in any other sequence or pattern. Again, the transducers are aligned with the gas flow path axis 2308 and configured to transmit downstream pulses in one or more beam paths that are substantially aligned with or parallel to the gas flow path axis 2308 in the sensing channel 2306. With this configuration, it is not necessarily necessary to provide a separate flow sensor, because the flow component of the acoustic signal velocity can be directly derived or determined from the processing of the transmitted and received acoustic pulses.

[0484] Examples of flow therapy devices are disclosed in international application PCT / NZ2016 / 050193, filed December 2, 2016, entitled “Flow Path Sensing for Flow Therapy Apparatus,” and international application PCT / IB2016 / 053761, filed June 24, 2016, entitled “Breathing Assistance Apparatus,” which are incorporated herein by reference in their entirety. The following section discusses… Figures 11 to 16 To further discuss in detail examples of configurations of flow therapy devices that can be used with the aspects disclosed herein.

[0485] control system

[0486] Refer again Figure 1A The controller 13 can be programmed or configured to perform a closed-loop control system for controlling the operation of the flow therapy device. The closed-loop control system can be configured to ensure that the patient's SpO2 reaches a target level and is consistently maintained at or near that level.

[0487] The controller 13 can receive input(s) from the user that can be used by the controller 13 to execute a closed-loop control system. The target SpO2 value can be a single value or a range of values. The (multiple) values ​​can be preset, selected by a clinician, or determined based on patient type, where patient type can refer to current ailment and / or information about the patient (e.g., age, weight, height, sex, and other patient characteristics). Similarly, the target SpO2 can be two values, each selected in any of the ways described above. These two values ​​will represent a range of acceptable SpO2 values ​​for the patient. The controller can target one of the values ​​within the range. The target value can be the middle of the range or any other value within the range, which can be preset or selected by the user. Alternatively, the range can be automatically set based on the target value of SpO2. The controller can be configured to have one or more preset responses when the patient's SpO2 value moves out of the range. Responses can include issuing an alarm, switching to manual control of FdO2, changing FdO2 to a specific value, and / or other responses. A controller can have one or more ranges, where one or more different responses occur when the controller moves outside each range.

[0488] The graphical user interface of the flow therapy device can be configured to prompt the user to enter the patient type, and the SpO2 limit will be determined based on the user's selection. Furthermore, the user interface can include customization options where the user can define these limits.

[0489] Overall, SpO2 will be controlled between approximately 80% and approximately 100%, or between approximately 80% and approximately 90%, or between approximately 88% and approximately 92%, or between approximately 90% and approximately 99%, or between approximately 92% and approximately 96%. SpO2 can be controlled between any two suitable values ​​from any two of the above ranges. Target SpO2 can be between approximately 80% and approximately 100%, or between approximately 80% and approximately 90%, or between approximately 88% and approximately 92%, or between approximately 90% and approximately 99%, or between approximately 92% and approximately 96%, or approximately 94%, or 94%, or approximately 90%, or 90%, or approximately 85%, or 85%. The SpO2 target can be any value between any two suitable values ​​from any two of the above ranges. For the defined range, the SpO2 target can correspond to the middle of the SpO2 range.

[0490] FdO2 can be configured to be controlled within a range. As previously discussed, as long as the flow rate meets or exceeds the patient's peak inspiratory demand, the oxygen concentration (FdO2) measured in the device will be substantially the same as the oxygen concentration (FiO2) in the patient's breath, and thus such terms can be considered equivalent. Each of the range limits can be preset, user-selected, or determined based on patient type, where patient type can refer to current ailment and / or information about the patient (e.g., age, weight, height, sex, and / or other patient characteristics). Alternatively, a single value of FdO2 can be selected, and the range can be determined at least in part based on that value. For example, the range can be above and below a selected FdO2 setpoint. The selected FdO2 can serve as the starting point for the controller. If the controller attempts to move FdO2 out of range, the system can have one or more responses. These responses can include issuing an alarm, preventing FdO2 from moving out of range, switching to manual control of FdO2, and / or switching to a specific FdO2. The device may have one or more ranges, wherein one or more different responses occur when the device reaches the boundary of each range.

[0491] FdO2 can be controlled between approximately 21% and approximately 100%, or between approximately 21% and approximately 90%, or between approximately 21% and approximately 80%, or between approximately 21% and approximately 70%, or between approximately 21% and approximately 60%, or between approximately 21% and approximately 50%, or between approximately 25% and approximately 45%. FdO2 can be controlled between any two suitable values ​​from any two described ranges. The FdO2 target can be between any two suitable values ​​from any two described ranges. If the range is based on a single value, the upper and lower limits can be determined by adding / subtracting a fixed amount from the selected value. The amount added or subtracted can be approximately 1%, or approximately 5%, or 10%, or approximately 15%, or approximately 20%, or approximately 30%, or approximately 50%, or approximately 100%. The amount added / subtracted can vary relative to the selected value. For example, the upper limit can be 20% higher than the selected value, so for the range of control, the selected value of 50% FdO2 will have an upper limit of 60%. The percentage used for this range can be about 1%, or about 5%, or 10%, or about 15%, or about 20%, or about 30%, or about 50%, or about 100%. The methods used to calculate the lower and upper limits will not necessarily need to be the same. If a single value is used, that value can be between about 21% and about 100%, or between about 25% and about 90%, or between about 25% and about 80%, or between about 25% and about 70%, or between about 25% and about 60%, or between about 25% and about 50%, or between about 25% and about 45%.

[0492] The graphical user interface 14 (GUI) can be configured to display the range of values ​​controlled for FdO2 and / or SpO2. The range can be displayed by setting two boundaries on the GUI to be separate from each other, with indicators appearing within the range to graphically represent the position of the current value relative to the range boundaries.

[0493] The GUI can display graphs of recent FdO2 and / or SpO2 data. The GUI can display the level of each parameter on the same or different graphs within a defined time period (e.g., one or more hours). The displayed data duration can match the length of time the data has been available.

[0494] The displayed FdO2 data may be at least one of target FdO2 or measured FdO2. SpO2 data may include a line indicating the target SpO2. Additionally or alternatively, SpO2 and / or FdO2 data may include one or more lines or one or more shaded areas indicating their respective control limits.

[0495] The graph can be displayed on the default screen. Alternatively, the graph can be hidden, showing only the current data values. The graph can be made available through interaction with the GUI (e.g., by selecting specific parameters to view the graph).

[0496] Closed-loop control

[0497] refer to Figure 10 The diagram illustrates a schematic of a closed-loop control system 1000. The closed-loop control system can utilize two control loops. The first control loop can be implemented by an SpO2 controller. The SpO2 controller can determine the target FdO2 in part based on the target SpO2 and / or the measured SpO2. As discussed above, the target SpO2 value can be a single value or a range of acceptable values. The target values ​​(multiple) can be preset, selected by the clinician, or automatically determined based on client characteristics. Generally, the target SpO2 value is received or determined before or at the start of the treatment period, although it can be received at any time during the treatment period. During the treatment period, the SpO2 controller can also receive the following as inputs: measured FdO2 readings from the gas composition sensor, and measured SpO2 readings and signal quality readings from the patient sensor. In some configurations, the SpO2 controller can receive the target FdO2 as input; in such cases, the output of the SpO2 controller can be directly provided back to the SpO2 controller as input. Based at least in part on these inputs, the SpO2 controller can output the target FdO2 to the second control loop.

[0498] The second control loop can be implemented by an FdO2 controller. The FdO2 controller can receive inputs of measured FdO2 and target FdO2. The FdO2 controller can then output an oxygen inlet valve control signal to control the operation of the oxygen valve based on the difference between these measured FdO2 and target FdO2 values. When the flow therapy device operates in automatic mode, the FdO2 controller can receive the target FdO2 value output from the first control loop. The FdO2 controller can also receive additional parameters, such as flow rate, gas properties, and / or measured FdO2. Gas properties may include the temperature of the gas at the O2 inlet and / or the oxygen content of the supply source. The gas supply source connected to the oxygen inlet valve can be an oxygen-enriched gas flow, wherein the oxygen content of the supply source may be less than pure oxygen (i.e., 100%). For example, the oxygen supply source can be an oxygen-enriched gas flow with an oxygen content less than 100% and greater than 21%.

[0499] The FdO2 controller can determine the oxygen flow rate required to achieve the target FdO2 from at least some of these inputs. The FdO2 controller can use the flow rate input to modify the valve control signal. If the flow rate changes, the FdO2 controller can automatically calculate the new required oxygen flow rate needed to maintain the target FdO2 at the new flow rate, without waiting for feedback from a gas concentration sensor (e.g., the measured FdO2 value). The FdO2 controller can then output the modified valve control signal to control the valve based on the new flow rate. In some configurations, the FdO2 controller's control signal can set the current to the oxygen valve to control its operation. Alternatively, the FdO2 controller can detect changes in the measured FdO2 and change the valve position accordingly. During manual mode, the second control loop can operate independently without receiving the target FdO2 from the first control loop. Instead, the target FdO2 can be received from user input or default values.

[0500] During the treatment period, the SpO2 controller and FdO2 controller can continue to automatically control the operation of the flow therapy device until the end of the treatment period or an event triggers a change from automatic mode to manual mode.

[0501] Closed-loop control using patient models

[0502] Figure 2Graphs 200 for SpO2 and FdO2 are provided, illustrating the various operational phases of the flow therapy device during the treatment period. Although FdO2 (fraction of delivered oxygen) is used in these graphs, as previously discussed, FdO2 is substantially the same as FiO2 as long as the flow rate meets or exceeds the patient's peak inspiratory demand. The operational phases include a learning phase 210 and a control phase 220. During the learning phase, the controller generates a patient-specific model. Due to individual patient variability, each patient's SpO2 responds differently to changes in FdO2. As a result, a patient-specific model can be generated to provide better control over the patient's SpO2. Learning phase 210 (also known as the model building phase) may include a waiting phase 212, a feedforward phase 214, and a model generation or patient characterization phase 216. The patient characterization phase occurs simultaneously with at least a portion of the feedforward phase 214. During the patient characterization phase, the patient-specific model can be iteratively developed as data is collected during the feedforward phase 214. The learning phase ends after the patient-specific model is generated. Following the learning phase, the flow therapy device operates in the control phase until the end of the treatment period. As described below, the flow therapy device can be configured to transition back to the learning phase during the treatment period. In some configurations, the learning phase is optional, and a patient-specific model can be generated without a defined learning phase. For example, in such a configuration, a default model can be used initially. The default model can then be updated to a patient-specific model during the treatment period. During the treatment period, the patient-specific model can be updated at defined intervals, defined events, periodically, non-periodically, and / or continuously.

[0503] Learning stage

[0504] When the flow therapy device is initially turned on, it can start in either manual or automatic mode. If the device is in manual mode, it can be switched to automatic mode. When starting in automatic mode or when switched to automatic mode, the flow therapy device can begin the treatment period after the user provides one or more operating settings (e.g., FdO2 limit, SpO2 limit, flow rate, etc.). When the treatment period begins, the controller can initiate a waiting phase 212. During the waiting phase 212, the position of the oxygen inlet valve is based on the FdO2 setpoint prior to the start of the learning phase, which may cause the valve to remain in the same position or cause the valve position to change (e.g., open or closed). The patient's SpO2 may change in response to high flow therapy. The controller can wait until SpO2 stabilizes and has stabilized at a reasonable constant value before proceeding to the feedforward phase 214. The waiting phase 212 can last for a defined period of time. The controller can be configured to initiate the feedforward phase 214 without a waiting phase 212.

[0505] During the feedforward phase 214, the controller can modify the FdO2 level, such as increasing or decreasing it. The new FdO2 value can be preset or determined based on factors such as the patient's current SpO2. The new FdO2 can be selected by the clinician based on their own expertise and knowledge. The selected FdO2 can bring the patient's SpO2 closer to the target SpO2 level. The FdO2 can be automatically determined by the controller 13.

[0506] During the feedforward phase 214, the controller measures and records the patient's SpO2. The controller can also measure and record FdO2. The graph illustrates the step change of FdO2 towards the target FdO2 value. The actual FdO2 can rise to the target FdO2 within a defined time period. The measured data of SpO2 and FdO2 can be incorporated to assess the relationship between SpO2 and FdO2 and to generate a model. Signal quality indicators from the patient sensor 26 can also be recorded.

[0507] The feedforward phase 214 can last for at least a defined minimum time period and can automatically terminate after a defined maximum time period. In some configurations, the minimum time period can be approximately 30 seconds, approximately 1 minute, approximately 2 minutes, 3 minutes, or another value within the above range. The maximum time period can be approximately 3 minutes, approximately 4 minutes, approximately 5 minutes, approximately 6 minutes, or another value within the above range. The minimum and maximum values ​​can be any combination of any two suitable values ​​described above. After the minimum time period, the controller can determine whether the patient has been adequately represented based on an analysis of the defined patient representation criteria. If the maximum time period is reached without adequately representing the patient, the feedforward phase will terminate and the control phase will begin using a default patient model. The default model may depend on the patient type (e.g., normal, hypercapnia, user-defined, or other types). The default patient model may be at least partially based on one or more received characteristics of the patient. The reasons for the inability to represent the patient are discussed in further detail below.

[0508] During the feedforward phase 214, the controller analyzes the relationship between FdO2 and SpO2. The controller can be configured to model this relationship using an exponential decay function, where the exponential decay constant is varied to best fit the model to the data. The initial and final FdO2 values ​​used in the exponential decay function can be set by initial and final target FdO2 values. Fitting the model to FdO2 data allows for the analytical evaluation of the SpO2 model, which can be faster and less computationally demanding. Figure 3 The image shows possible examples of two sets of trend fits. Optionally, the controller can determine the relationship between the measured FdO2 and the amount of time since the target FdO2 change.

[0509] Additional reference Figure 3 Plot 301 illustrates the fitting trends of SpO2 plots 302 and FdO2 plots 305. These plots also include a measure of the signal quality 304 of the patient monitor. To fit the trends to the SpO2 data, a model representing the behavior of the SpO2 data can be generated, and at least one constant parameter of the model can be determined. This model can correlate each change in FdO2 with a time-based change in SpO2.

[0510] Following a change in FdO2, SpO2 does not exhibit any change due to the change in FdO2 for a period of time, which can be termed the delay time. The delay time is caused by a combination of various factors. One potential factor is the time it takes for the device to change the FdO2, and this will be fairly consistent. Another potential factor is the time it takes for the gas to travel from the device to the interface, which can depend on the selected flow rate. Another potential factor is the time it takes for the gas to travel from the user interface to the patient's lungs. This can depend on the selected flow rate, but also on the limitations of the patient's airway and the length of the passageway from the interface to their lungs. Another potential factor is the time it takes for oxygenated blood to travel from the patient's lungs to the measurement site (i.e., the location of the patented sensor). This depends on the speed of blood travel, which will vary based on the patient's physiology and heart rate. Furthermore, this time length can depend on the distance between the patient's lungs and the type of patient sensor used. This distance can be changed by the location of the patient sensor. Alternatively, it can be changed by the patient's size.

[0511] After the delay time, SpO2 can exhibit an exponential decay curve, where SpO2 asymptotically approaches its new value, with the total change proportional to the total change in FdO2. In some embodiments, there are four parameters of the model that can influence the shape of the model (in addition to the effect of the change in FdO2 delivery). The first is the delay time between the change in FdO2 and the first change in SpO2. The second is the initial value of SpO2. The third is the magnitude of the total change in SpO2 relative to the magnitude of the change in FdO2. The fourth is the rate of exponential decay, which defines how quickly SpO2 approaches its final value after the delay time.

[0512] Since FdO2 does not exhibit a single change but rather varies over time, the SpO2 model can be evaluated as an integral of the effects of various FdO2 changes over time. The applicable model is shown below in equation (1).

[0513] (1)

[0514] Equation (1) includes five parameters for the model, which can be evaluated and determined when generating the model. FdO20 is the initial FdO2, SpO20 is the initial SpO2, DT is the delay time, τ is the exponential decay constant, and a is the ratio between the change in SpO2 and the change in FdO2. FdO20 can be determined from the initial target FdO2. The remaining four parameters can be varied to find a model that best fits the data.

[0515] The fit can be quantified using a method called least squares. Least squares involves looking at each data point and calculating the error, where the error is based on the difference between that data point and a relevant point on the model. The errors for each data point can be summed to give the total error of the model.

[0516] A model can be determined by selecting the set of parameters that results in the model having the minimum possible total error. The values ​​of the parameter set can be computed using a suitable iterative method aimed at gradually approaching an ideal set of constant parameters. One such algorithm is the Levenberg-Marquardt algorithm. (See additional references.) Figure 4 The following two figures are illustrated: graph 401, which shows the iteration of the trend line before reaching the best fit 405; and graph 404, which shows the signal quality.

[0517] Furthermore, when calculating the error, the error value of each data segment can be weighted according to the corresponding signal quality of that data segment. The signal quality of the patient's sensor is illustrated in graph 404. When constant parameters are determined and a trend line is fitted, weighting the data points can give additional weight to more accurate data points. Without weighting, the error of the model's data points can potentially be greatly influenced by inaccurate data points.

[0518] The results of the learning phase can be used to tune the controller to best suit the individual patient. An untuned controller that is not specifically modeled for the individual patient can exhibit several drawbacks. Generally, a slow / overdamped controller takes longer to reach the target SpO2 and reacts slowly to any fluctuations. On the other hand, a fast / underdamped controller risks attempting to move too quickly toward the target value and overshooting it. This can cause the controller to oscillate around the target and become unstable. Preferably, the controller is critically damped, meaning the model can reach the target SpO2 value quickly, but not so quickly that it essentially overshoots the target and becomes unstable. Analytical solutions for critically damped control algorithms can be found by using a model generated from patient characterization.

[0519] The use of high-flow nasal cannula systems facilitated several analyses that could be performed during this learning phase. In other systems, such as those ventilated via a mask or tracheostomy port, the relationship between FdO2 and SpO2 is heavily influenced by the patient's respiratory rate. One reason for this is that a portion of each breath is re-exhaled air. When a patient takes short, rapid breaths, most of the air inhaled is re-exhaled air, so the air entering the lungs consists of a smaller portion of therapeutic air. Similarly, when a patient takes slow, deep breaths, a smaller portion of the air inhaled is re-exhaled air, so the air entering the lungs consists of a larger portion of therapeutic air. This affects the oxygen concentration in the lungs, which in turn affects SpO2.

[0520] As described earlier, high-flow nasal cannula has the effect of flushing the patient's airway with therapeutic gas to greatly reduce rebreathing. This means that rebreathing will be minimal regardless of the patient's respiratory rate, and the gas entering the patient's lungs will be much more similar in composition to the therapeutic gas delivered by the device.

[0521] Because the effect of respiratory rate on the FdO2 / SpO2 relationship is reduced, the device is able to utilize a learning phase at startup, during which data analysis allows for optimal tuning of the controller and / or the achievement of patient-specific predictive control without the need for computationally required continuous learning.

[0522] When the characterization criteria are met, the patient is considered fully characterized. Following patient characterization 216, the learning phase 210 ends and the control phase 220 begins. Characterization criteria can define acceptable ranges for at least some of the parameters used to compute the patient model. For example, characterization criteria may include: a range of acceptable values ​​for a defined delay time between a change in FdO2 and a first change in SpO2; a range of acceptable values ​​for an initial value of SpO2; a range of acceptable values ​​for the rate of exponential decay, which defines how quickly SpO2 approaches its final value after the delay time; a range of acceptable values ​​for the ratio between a change in SpO2 and a change in FdO2; and / or other parameters associated with model generation. Characterization criteria may define only minimum or maximum values ​​for the parameters.

[0523] In some cases, patient representation may fail. In such cases, the controller can either utilize the default PID controller to initiate the control phase or switch back to automatically maintain FdO2 at the specified level. The default PID controller can be designed in such a way that it is critically damped or overdamped for most (if not all) patients. Generally, an overdamped controller that moves slowly toward the SpO2 target is more desirable than an underdamped controller that oscillates and becomes unstable. Each patient type can have a different default PID controller.

[0524] Failure in patient representation can be caused by problems with the dataset, such as low mean signal quality, insufficient FdO2 increase, and / or insufficient SpO2 increase. Additionally or alternatively, failure can occur due to reasons associated with modeling the data (e.g., certain parameters falling outside a certain acceptable range). These parameters can include model fit / error, as a large error between the model and the data will reduce the model's effectiveness. These parameters can include various parameters of the model discussed earlier (initial SpO2, delay time, exponential decay constant, and the ratio between FdO2 increase and SpO2 increase), as an unrealistic value for any of these parameters will indicate error in the model. Additionally or alternatively, failure can occur during PID tuning if any of the tuned PID values ​​fall outside a certain range.

[0525] Ideally, an alert would alert the clinician that this has occurred and provide an option to attempt another learning phase. Alternatively, the device itself could initiate another learning phase to attempt to characterize the patient. The number of automated attempts could be limited to a predetermined number. Alternatively, a patient-specific model could be generated from a default model and then optionally updated during the treatment period.

[0526] The learning phase can be repeated more than once during the treatment period. Even if the learning phase is successful, situations may arise during the treatment period that cause the controller to re-enter the learning phase. The controller may have a maximum amount of time for which the patient model is effective. For example, in a hospital setting, the patient's condition can change over time in ways that affect the relationship between FdO2 and SpO2. Therefore, it may be beneficial to end the control phase and / or automatically start a new learning phase to re-represent the patient after a certain amount of time (e.g., one day or several days). Alternatively, the patient-specific model can be updated and re-represented during the treatment period. For example, during the treatment period, the patient-specific model can be updated at defined intervals, defined events, periodically, non-periodically, and / or continuously.

[0527] The controller can test the error between the predicted and measured SpO2 values. A sufficiently large error (potentially spanning multiple error values ​​or a defined time period) indicates an incorrect patient model, and the controller can be configured to initiate a new learning phase. In some cases, if the patient's SpO2 falls outside the target range, the controller can terminate the control phase and trigger a new learning phase.

[0528] Predictive control during the control phase

[0529] Figure 5 The figure 500 illustrates the signal hysteresis curve between the predicted SpO2 value and the actual SpO2 data. One of the difficulties in controlling FdO2 based on the SpO2 signal is the delay time and signal hysteresis. When FdO2 is changed at the device, gas with the new oxygen concentration needs to travel through a catheter to the patient interface, down the patient's airway into their lungs, and perform gas exchange in the lungs. The oxygenated blood then must travel through their blood vessels to the pulse oximeter site, be measured by the patient's sensor, and then the measurement data is received by the controller. By the time the controller receives the measurement data, several additional cycles may have been processed, resulting in a substantial overshoot of the target SpO2, which in turn causes large oscillations in the patient's SpO2 and leads to control instability. Furthermore, another aspect of high-flow nasal cannula is the use of a humidifier during treatment. Without a humidifier, the patient's airway will dry out rapidly. The humidifier component requires sufficient residence time to function, thus increasing the delay time. This additional delay makes it increasingly important for the predictor to account for the delay time.

[0530] Some approaches to addressing this problem include overdamping the controller, having low sensitivity, and / or allowing previous changes in FdO2 to take full effect by incorporating a delay between each iteration of the control signal. Such delays can be based at least in part on data measured during the learning phase discussed earlier. While such a system can adequately handle signal delays, it can present new problems due to its slowness and lack of responsiveness to the patient's condition. For example, it may significantly increase the time taken to reach the target SpO2 when the device is first turned on, or the controller may be too slow to react to sudden changes in the patient's SpO2.

[0531] The controller can be configured to implement predictive control during the control phase, becoming a PID controller. The predictive control can be a Smith predictor. Predictive control can be determined at least in part based on one or more parameters analyzed during the learning phase 210. Using data received during the learning phase 210 to design or modify the predictive controller allows for much more effective patient-specific control. The goal of predictive control is to predict the SpO2 value, taking into account signal hysteresis, and to control FdO2 based on the predicted SpO2 value rather than the measured SpO2. This results in a control algorithm that can be highly sensitive and stable.

[0532] The predicted value of SpO2 can represent SpO2 after a delay time has elapsed. The delay time is the time between when a change is made to FdO2 and when a response is seen in SpO2 (i.e., when a corresponding response is detected in the measured SpO2). Because any change in FdO2 will not have any effect on SpO2 until after the delay time has elapsed, the currently available data for SpO2 and FdO2 can be used to predict SpO2 fairly accurately until the end of the delay period. The predictor can generate data that is essentially the same as the measured SpO2 data, where the delay time is removed, such as... Figure 5 As illustrated in the figure. Although the prediction did not predict the disturbances shown in the actual data, the overall shape of the curve matches.

[0533] The predictor can receive inputs including one or more measured FdO2 values, one or more target FdO2 values, one or more predicted SpO2 values, one or more measured SpO2 values, and / or one or more target SpO2 values. Each of these inputs can be a recent value and / or a previous value, at least temporarily stored by the processor. Each of these inputs can be paired with any relevant data associated with the input data point, such as signal quality measurements and / or values ​​relating to the time when the measurement occurred.

[0534] Here, the PID controller will function essentially the same as described earlier; however, the PID controller uses an estimated SpO2 instead of the measured SpO2, and thus will instead calculate the difference between this estimate and the target. This value will represent the change in SpO2. Because a predictor is used, the change in SpO2 will take into account previous changes in FdO2 that have not yet taken effect. The change in SpO2 will be paired with the current FdO2 to determine the new target FdO2.

[0535] Figure 6The diagram 600 illustrates a Smith predictor used in conjunction with a PID controller. Initially, the PID controller receives input of the predicted difference between the patient's SpO2 and the target SpO2, and outputs the target FdO2 to the FdO2 controller to bring the patient's SpO2 closer to the target SpO2. The FdO2 controller then outputs commands based on the target FdO2 output by the PID controller to control the valves of the flow therapy device.

[0536] The new FdO2 is delivered to the patient and combined with other disturbances to induce a patient response. These disturbances can include errors from any sensors or control mechanisms within the machine (e.g., oxygen valves) that cause changes in FdO2. Additional variations in the patient response can be caused by the patient's physiological and physical parameters (vigorous physical activity, changes in respiratory rate, etc.) that affect the patient's SpO2. SpO2 is then measured, and this value will be the patient's current SpO2 plus or minus any errors from the sensors. A signal quality indication is also output to a PID controller.

[0537] For reference, in controllers without a Smith predictor, the measured SpO2 value is then compared to the target SpO2, and the difference is fed back into the PID controller. Using the Smith predictor model, the controller first makes a prediction of SpO2. This can be done using the same model generated during the learning phase or a default model (e.g., when the patient cannot be or is not represented), where SpO2 is estimated by integrating the effects of all past FdO2 changes over time and then adding them to the initial SpO2:

[0538]

[0539] in These are the constant parameters of the model, which can be generated during the learning phase or started as default values. These parameters can remain unchanged throughout the treatment period or can be updated continuously, periodically, or non-periodically. Importantly, DT is the delay time between the change in FdO2 and the onset of the SpO2 response. In the first step, this calculation is run, where DT is assumed to be 0. This results in an estimate of the patient's SpO2 after the delay time has elapsed. This value can be referred to as the predicted SpO2 without the delay time.

[0540] Subsequently, the same equation is processed again using the estimates from the DT (Digital Transformation Tool) from the learning phase. When using DT, the model's output can be called the predicted SpO2 with a time delay, which predicts the current reading from the pulse oximeter. The predicted SpO2 with a time delay can also be calculated by referencing a previous estimate of SpO2 without a time delay. For example, if the time delay is 90 seconds, the estimate of SpO2 with a time delay is the estimate of SpO2 without a time delay obtained 90 seconds ago.

[0541] Then, the difference between the SpO2 value without delay and the measured SpO2 value is calculated. If the model is perfect, the difference will be 0. Typically, there will be some difference, which represents both errors in the model and the interference in SpO2 mentioned earlier.

[0542] Figure 7 The diagram 700 illustrates the prediction with the included delay time. This error and interference value is then added to the first prediction of SpO2 without the delay time, and can be used to correct the predicted SpO2 using the measurement error between the actual and predicted SpO2. This final value represents the predicted SpO2 without the added delay time interference.

[0543] Then, the difference between the predicted SpO2 and the target SpO2 without delay time or external interference is calculated, and the result is fed back to the PID controller, and the process starts again.

[0544] Assumptions can be made to reduce the computational burden of modeling the SpO2 response. First, since FdO2 changes in step increments with each iteration of the control loop, the equations can be evaluated using discrete time points. Therefore, the model can be further rearranged into an iterative process, where results from previous iterations of the model can be included in the current iteration evaluating the model.

[0545] In some cases, a Smith predictor can allow a PID controller to react to an anticipated SpO2 reading without actually reacting to it. For example, a Smith predictor might predict that SpO2 will rise to the target level and stabilize there. However, when the actual SpO2 measurement comes into play, it may indicate that SpO2 is approaching the target faster than predicted and is now heading towards overshooting the target value based on previous changes in FdO2. Therefore, the controller can quickly reduce FdO2 to minimize or even prevent overshoot. Without a Smith predictor, the control system would not respond to overshoot until it has already occurred.

[0546] Figure 8Different computational models for PID controllers are illustrated. To demonstrate the differences caused by the Smith predictor, a computational model was set up to represent a COPD patient. This model involves a sudden drop from a healthy SpO2 reading along with random fluctuations in SpO2 that would normally occur. The aim was to understand how quickly the control system could restore the patient to a healthy SpO2 reading and stabilize at that point, and how well it handled random fluctuations. The same model with the same random fluctuations was tested on three different PID controllers: one with a Smith predictor 802, one a normal PID tuned for a specific patient 804, and one a PID controller tuned for a default patient 806. PID controllers can be tuned or untuned. An untuned PID controller can be referred to as the default PID or an untuned PID. An untuned controller refers to a PID controller that is not tuned for a specific patient. However, an untuned controller can be tuned for stability or for a general patient type or a specific patient type (e.g., normal, hypercapnia, etc.) and is loaded onto the controller before operating the flow therapy device. Furthermore, "tuned PID controller" and "default PID controller" can refer to PID controllers not integrated with the Smith predictor. The Smith predictor can be used to modify the tuned PID.

[0547] As described above, the Smith PID 802 recovers to a healthy SpO2 reading approximately four times faster than the default PID 806 and is more accurate in maintaining the target SpO2. The tuned PID 804 is worse than the default PID 806, but not as good as the Smith PID 802.

[0548] Signal weighting

[0549] refer to Figure 3 and Figure 4 Graphs 304 and 404 provide a signal quality indicator for the patient sensor. The quality of the SpO2 signal from the patient sensor can change during use. Patient sensors (e.g., pulse oximeters) can be inaccurate in a few cases, such as when the pulse oximeter is moved around, resulting in poor-quality data. Some patient sensors (e.g., pulse oximeters) can provide a signal quality indicator with each SpO2 reading. The signal quality indicator can be defined as a measure of the measurement accuracy of the patient sensor. The value of the signal quality indicator can be calculated on a defined scale, such as 0 to 1, where 0 represents no signal and 1 represents the strongest signal. Data representing the signal quality from the patient sensor can be processed in one or more ways, including fitting from different scales (e.g., 0 to 5) to a defined scale of the system (e.g., 0 to 1).

[0550] When tuning a PID controller (whether it is default, patient-specific, or predictive), anticipated periodic disturbances can be analyzed. Periodic disturbances are fluctuations in SpO2 caused by factors other than the control variable (FdO2) and include errors in SpO2 measurement. By tuning the PID controller, anticipated periodic disturbances can be estimated, and consequently, the standard deviation of the SpO2 reading due to signal quality can also be estimated. The SpO2 reading will have a certain level of error between the measured and true values. This error can be represented by a measure of the standard deviation. The standard deviation will be inversely proportional to the signal quality.

[0551] Variations in signal quality can affect the error in SpO2 measurements, thus influencing the system's periodic disturbances. This means that a previously tuned PID controller can go from critically damped to overdamped (the controller becomes unnecessarily slow) or over-damped (the controller becomes unstable). Signal quality can be addressed by weighting the control algorithm based on signal quality readings from patient sensors. The control output can be multiplied by the signal quality to reduce the impact of data points with low signal quality. The goal is to attenuate the PID controller when signal quality deteriorates, thereby effectively retuning the PID controller as expected changes in periodic disturbances occur.

[0552] Weights can be applied to changes in FdO2 output via PID control. The change in FdO2 will be scaled relative to the latest signal quality reading. For example, if FdO2 is at 30% and the signal from the pulse oximeter indicates that the patient's SpO2 has decreased, the PID might instruct FdO2 to increase by 4% to reach 34%. However, if the signal quality for the measurement is only 0.5 and linear weighting is being used, this increase might be attenuated to 2%, resulting in a new FdO2 of only 32%. Weighting allows the controller to continue controlling the patient's SpO2, but so slowly that it does not overcompensate for poor-quality measurements.

[0553] The relationship between signal quality and control algorithm weights can be defined by any function designed to represent the increase in noise as signal quality decreases, and is not limited to the linear function described above. The relationship between signal quality and control weights can also be based on the correlation between signal quality and the standard deviation of the error.

[0554] By weighting SpO2 measurements based on signal quality, PID controllers can be less affected by disturbances in SpO2 measurements (such as motion artifacts and poor perfusion). Weighting the control algorithm based on signal quality results in a more robust and stable controller that can compensate for noisy data when signal quality deteriorates, while providing fast and accurate control when signal quality is high and data is reliable.

[0555] Processes used to control flow therapy equipment

[0556] Figures 9A to 9C A flowchart illustrating a method for controlling the operation of a flow therapy device during a high-flow treatment phase is shown. Process 900, as well as subprocesses 910 and 930, can be implemented by any system capable of controlling the operation of the flow therapy device. For example, process 900 can be implemented wholly or partially by controller 13. Multiple different controllers can be configured to implement process 900. For example, different aspects of the process can be implemented by controllers. A remotely located system can be configured to be part of the implementation of the process. For example, a remotely located system can be configured to perform the learning phase 910 of the system, and the control phase 930 can be performed locally by controller 13. Although any number of systems can implement process 900 wholly or partially, for the sake of simplicity, process 900 will be described in terms of specific components of controller 13 and flow therapy system 10.

[0557] In process 900, at box 902, the user can initiate a high-flow treatment period on the flow therapy device 10. To initiate the treatment period, the flow therapy device may require a defined set of information about the patient. For example, input may include one or more patient characteristics, such as patient type (e.g., normal, hypercapnia, or other), age, weight, height, sex, and / or other patient characteristics. The flow therapy device 10 may also require the user to set a target SpO2 value or range for the patient. The flow therapy device may automatically determine the target SpO2 value, at least in part, based on the received patient characteristics. After receiving the information, the user can initiate the treatment period, and the process can proceed to box 910.

[0558] At box 910, the controller can execute a learning phase subprocess. The learning phase can generate a patient-specific model for use during the control phase. In some cases, the learning phase may fail, resulting in the use of a default patient model during control phase 930. As discussed herein, a patient-specific model can be generated from the default model and then optionally updated during the treatment phase without a defined learning phase.

[0559] Additional reference Figure 9BThe learning phase is described in further detail. At box 912, the controller performs a waiting phase until the patient's SpO2 value stabilizes. During the waiting phase 202, the oxygen inlet valve defaults to the previous FdO2 setpoint, and this valve can be opened or closed as needed. The patient's SpO2 may change in response to high-flow-rate treatment, and therefore the controller can wait until the SpO2 has stabilized at a reasonably constant value before proceeding to box 914. Optionally, the waiting phase can be bypassed, and the process can proceed directly to box 914 without performing a waiting phase at box 912.

[0560] At box 914, the controller can increase the oxygen concentration of the gas stream to a new level based on the target SpO2 level. The new FdO2 value can be preset or determined based on factors such as the patient's current SpO2. The new FdO2 can be selected by the clinician based on their own expertise and knowledge. The selected FdO2 can bring the patient's SpO2 closer to the target SpO2 level. The FdO2 can be determined automatically by controller 13.

[0561] At box 916, the controller measures and records patient and device parameters. The patient parameter can be SpO2, and the device parameter can be FdO2. The controller can measure and record FdO2 and SpO2 data. The actual FdO2 can gradually increase to the target FdO2 within a defined time period. Signal quality indicators from the patient sensor can also be recorded.

[0562] At box 918, the controller can analyze and model the relationship between the patient and device parameters. For example, this relationship could be between FdO2 and SpO2, and the controller can determine the relationship between the measured FdO2 and the amount of time since the target FdO2 change. An exponential decay function can be used to model this relationship, where the exponential decay constant is varied to best fit the model to the data. The initial and final FdO2 values ​​used in the exponential decay function can be set by the initial and final target FdO2 values. Modeling of this relationship can be performed as further described herein.

[0563] At box 920, the controller can determine whether patient representation criteria are met. Representation criteria can define acceptable ranges for at least some of the parameters used to compute the patient model. For example, representation criteria may include: a range of acceptable values ​​for a defined delay time between a change in FdO2 and a first change in SpO2; a range of acceptable values ​​for an initial value of SpO2; a range of acceptable values ​​for the rate of exponential decay, which defines how quickly SpO2 approaches its final value after the delay time; a range of acceptable values ​​for the ratio between a change in SpO2 and a change in FdO2; and / or other parameters associated with model generation. Representation criteria may define only minimum or maximum values ​​for the parameters. If the criteria are met, at box 922, the controller outputs a patient-specific model for use during the control phase. If the patient representation criteria are not met, the process proceeds to box 924, where the controller determines whether the maximum time for the learning phase has been exceeded. If the maximum time has not been exceeded, the controller continues iterating on the model. If the maximum time has been exceeded, at box 926, the controller uses a default patient model for the patient. If the patient characterization criteria are not met, the controller can restart the learning phase subprocess 910 once or multiple times.

[0564] After the learning phase is complete, at subprocess 930, the model is output for use during the control phase. About Figure 9C This will be further described in the sub-process of the control phase.

[0565] At box 932, the controller executes the PID controller based on the patient model output during the learning phase. The PID controller can be configured to control FdO2 based on the target SpO2. At box 934, the PID can use a predictive algorithm (e.g., a Smith predictor) to predict SpO2. At box 936, the PID can determine the FdO2 value based on the predicted patient SpO2 value. At box 938, the PID controller can adjust the output of the FdO2 value based on a signal quality indicator associated with the patient sensor. At box 940, the model is adjusted based on the patient response. The difference between the predicted SpO2 and the target SpO2 is calculated, and the result is fed back to the PID controller. At box 942, the controller determines whether the treatment period is complete. If the treatment period is not complete, the process restarts. If it is complete, the treatment period ends.

[0566] Closed-loop control using oxygen efficiency

[0567] In use to implement Figure 10 In another configuration of the closed-loop control system of the flow therapy device 10 illustrated, the flow therapy device 10 determines the oxygen efficiency associated with the patient. The flow therapy device 10 can generate a patient model of the oxygen efficiency used by the patient during the treatment period.

[0568] The system can calculate the patient's oxygen efficiency (ξ). O2 Along with other parameters, oxygen efficiency can generally be calculated based on the patient's measured SpO2 and measured FdO2. In one configuration, oxygen efficiency is determined by dividing the patient's measured SpO2 by the measured FdO2. In another configuration, oxygen efficiency is determined based on the non-linear relationship between the patient's measured SpO2 and measured FdO2.

[0569] Patients requiring supplemental oxygen may have lower oxygen efficiency than healthy individuals. For example, in a healthy individual, a change in FdO2 can cause a doubling of the change in SpO2, which would be similar to the SpO2 of a patient with low oxygen efficiency. Measuring a patient's oxygen efficiency allows for more efficient implementation of closed-loop oxygen control systems.

[0570] like Figure 11 As illustrated, controller 13 can calculate a patient's oxygen efficiency. The controller can receive measured SpO2 and FdO2 values. The measured FdO2 value can be received from a gas composition sensor. Instantaneous oxygen efficiency can then be calculated based on the measured SpO2 and FdO2 values. The patient's total oxygen efficiency can then be estimated by applying an applied filter to the instantaneous oxygen efficiency data. Filtering the instantaneous oxygen efficiency data reduces fluctuations when estimating the patient's total oxygen efficiency. The controller can also prioritize the most recent data. Instantaneous oxygen efficiency data can be weighted according to the signal quality of the pulse oximeter, so that measurements of instantaneous oxygen efficiency based on data with low signal quality have a reduced impact on the estimation of the patient's total oxygen efficiency. Instantaneous oxygen efficiency data can also be weighted according to the magnitude of the most recent change in FdO2, so that measurements of instantaneous oxygen efficiency based on data after a large change in FdO2 have a reduced impact on the estimation of the patient's total oxygen efficiency. This is due to the time lag between when a change is made in FdO2 and when a change is observed in the measured SpO2. When estimating a patient's oxygen efficiency, the controller can also take into account whether the patient is intubated. For example, the controller can disregard efficiency data from periods when the patient is not intubated.

[0571] The device can continuously monitor and update the estimate of the patient's total oxygen efficiency. The patient's total oxygen efficiency can be used by multiple parts of the closed-loop control system, such as in the predictive model, tuning of the PID coefficients, and / or step changes before the feedforward phase. The patient's total oxygen efficiency can be continuously updated as the estimate of the instantaneous oxygen efficiency changes. The controller can start with an initial estimate of the patient's oxygen efficiency based on the typical oxygen efficiency for patients requiring supplemental oxygen. The total oxygen efficiency can then be updated as data is received. A higher estimate of oxygen efficiency results in smaller changes in FdO2, which reduces the risk of the patient receiving too much oxygen. A lower estimate results in larger changes in FdO2, which allows the controller to achieve the target SpO2 more quickly but may cause overshoot.

[0572] In some configurations, the flow therapy device 10 may have an initial oxygen efficiency calculation phase to determine the patient's oxygen efficiency. In other configurations, the oxygen efficiency is not updated after the initial oxygen efficiency calculation.

[0573] The start of closed-loop control treatment period

[0574] As described herein, a user can initiate a closed-loop control treatment period by interacting with the graphical user interface of the flow therapy device 10. Closed-loop control may require a patient sensor 26 (e.g., a pulse oximeter) to be connected to both the patient and the flow therapy device 10, and the signal quality of the patient sensor must be at an acceptable level. Before starting closed-loop control, the user must set operating parameters for FdO2 and SpO2. Various methods for selecting these operating parameters are described herein.

[0575] The control range for FdO2 can have upper and lower control values. Users can select the upper and lower limits for the FdO2 control range. The difference between the upper and lower limits can be fixed. The control range can be fixed to a defined difference in oxygen concentration, such as 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, and 50% and / or any other range between these values. Users can then select specific FdO2 ranges, such as 25%-45%, 52%-72%, 80%-100%, or any other range. Users can change the values ​​of the FdO2 control limits in increments of 1%, 2%, 5%, or other increments.

[0576] The flow therapy device may have a lower limit of 21% and an upper limit of 100% for FdO2 control. The FdO2 control range may be cut off by limits (e.g., 95%, 90%, or lower) of the oxygen concentration that the device can practicably deliver. For example, the gas supply source connected to the oxygen inlet valve may be an oxygen-enriched gas flow, wherein the oxygen content of the supply source may be less than pure oxygen (i.e., 100%).

[0577] Flow therapy devices may include various configuration options for setting limits on the FdO2 control range. For example, a user may input the oxygen concentration of the oxygen source; the flow therapy device may be pre-programmed during manufacturing with an unchangeable upper limit; the upper limit may be changed by a technician but not by a regular user; a user may input the type of oxygen source (e.g., concentrator, oxygen cylinder, etc.), and the flow therapy device may determine appropriate limits; and / or the flow therapy device may measure the oxygen concentration of the gas from the oxygen source.

[0578] Furthermore, the flow therapy device can issue an alarm if the target oxygen concentration cannot be achieved. The alarm can serve as a fail-safe measure for situations where a control range higher than the oxygen source concentration has been selected. For example, if the control range is 80%-100% when connected to a 90% source, the flow therapy device will not exceed 90% and will trigger an alarm.

[0579] If a user attempts to reduce the control range of FdO2 above or below the upper or lower limit, the control range can be truncated. For example, if a user attempts to reduce the control limit by 21%–41%, the upper limit can continue to decrease, but the lower limit will remain at 21%. This will result in a control range less than 20% (e.g., 21%–35%). The control range can also have a lower limit on its size (e.g., 5%, 10%, 15%, etc.). The lower limit can be based on the size of the control range. For example, the lower limit could be half the size of the control range. Specifically, when one of the limits of the control range is at its physical limit (i.e., 21% or 100%), the other limit must be at least 10% above or below that limit. In such a configuration, the lowest and highest possible control ranges are 21%–31% and 90%–100%, respectively. The controller can change the FdO2 between the upper and lower limits of the control range to maintain SpO2 within the patient's target range.

[0580] As described herein, users can manually set the target range for SpO2. In some configurations, instead of manually selecting the target range for SpO2, the user can select a patient type, and the controller then selects a predetermined SpO2 control limit based on the patient type. Examples of patient types may include: "Normal," which has a defined SpO2 control range, such as 90%-98%, 92%-98%, 92%-96%, or another defined range; or "Hypercapnia," which has a defined control range, such as 88%-92%, 86%-90%, 88%-90%, or another defined range.

[0581] To maintain a patient's SpO2 within the target range, the controller can use the center of the target range as the target. Furthermore, the boundaries of the target range can serve as alarm limits. For example, for a "normal" patient with a target SpO2 range of 92%-96%, the device will target 94% of the SpO2 value. If the patient's SpO2 value falls outside the 92%-96% range, the device will then issue an alarm. Flow therapy devices can have additional alarms set at defined boundaries, independent of the selected SpO2 control range. For example, a flow therapy device can issue alarms at 50%, 60%, 70%, 75%, and / or 80% to indicate a decrease in the patient's saturation.

[0582] The flow therapy device 10 may include a configuration menu in which some or all of these values ​​can be changed. The configuration menu may be protected by a PIN or similar password function, preventing certain users from accessing these settings. For example, the configuration menu may be designed to be inaccessible to ordinary users (e.g., patients or nurses) but rather to be accessible to anyone configuring the device (e.g., technicians or manufacturers).

[0583] In the configuration menu, the limits that can be selected for the FdO2 control range can be modified. For example, the device can be configured such that the upper limit of the FdO2 control range cannot exceed 90%. Setting the limits of the control range can serve as a safety feature by preventing the device from delivering excessively high and / or low oxygen concentrations. Furthermore, the limits can be set based on the substances the device may deliver. For example, if the device is connected to an oxygen-enriched source containing a gas with an oxygen concentration of 90%, it will be impossible for the device to achieve 100% FdO2. In this case, the upper limit of the selectable FdO2 control range would need to be set to 90% or less.

[0584] In higher-level menus, it is also possible to change the size of the FdO2 control range. For example, the control range can be set to 10%, 15%, 20%, 27%, 30%, 36%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, or any other control range. When approaching one of the above limits, the control range can be reduced, for example, by half. For example, if the range is set to 40% and the lower limit of FdO2 is 21%, the lowest selectable range will be 21%-41%.

[0585] The SpO2 target range can be manually set by the user. The SpO2 target range for each patient type can also be changed in the configuration menu. Furthermore, the device can have additional patient types that can be selected via the configuration menu. For example, additional patient types can be labeled "Other" and can include customizable SpO2 target ranges. The upper and lower limits of the SpO2 target range for each patient type can be changed between 80% and 100% in 1% increments.

[0586] During the treatment period, the SpO2 controller and FdO2 controller can automatically control the operation of the flow therapy device until the end of the treatment period or an event triggers a change from automatic mode to manual mode.

[0587] During treatment, the graphical user interface (GUI) can display a graphical indicator of oxygen efficiency. The oxygen efficiency characteristic displayed on the GUI can be based on output values ​​of SpO2 and FdO2. Another oxygen efficiency characteristic can be a function of the determined oxygen efficiency and the patient's respiratory rate. When the oxygen efficiency characteristic is a function of the determined oxygen efficiency and the patient's respiratory rate, it can be calculated by dividing SpO2 by FdO2 and then dividing that value by the respiratory rate. Oxygen efficiency characteristic values ​​can be recorded and displayed in graph or trendline format to show how these values ​​change over time. The GUI can be configured to display each of the oxygen efficiency characteristics and the respiratory rate oxygen efficiency characteristic individually or together. For example, values ​​associated with each characteristic can be displayed together on the same screen or on separate screens (e.g., the user can switch to different screens within the interface to view different characteristics). Graphs or trendlines can be configured to display each characteristic individually or together on the same screen.

[0588] Figure 12 Graphs 1200 for SpO2 and FdO2 are provided, illustrating the various operational phases of the flow therapy device during the treatment period. Although FdO2 (delivered oxygen fraction) is used in these graphs, as previously discussed, FdO2 is essentially the same as FiO2 as long as the flow rate meets or exceeds the patient's peak inspiratory demand.

[0589] The operational phases include a waiting phase 1212, a step change phase 1214, a feedforward phase 1216, and a control phase 1220. Once control limits have been set, the flow therapy device 10 can enter the waiting phase 1212. The waiting phase 1212 allows the SpO2 sensor to stabilize and allows for an initial data set, such as SpO2, FdO2, signal quality, and other parameters. In particular, an initial estimate of the patient's oxygen efficiency can be determined. If the patient is already using the device in manual oxygen control mode with the SpO2 sensor attached, the device may already have an estimate of the patient's oxygen efficiency. In this case, the collected data can be used to continuously update this estimate.

[0590] In this configuration, the waiting phase 1212 can be extended for a fixed predetermined amount of time. This amount of time can be between 1 second and 60 seconds, or between 2 seconds and 30 seconds, or between 3 seconds and 15 seconds, or between 4 seconds and 10 seconds, 5 seconds, or any other time period within the above range.

[0591] During the waiting phase 1212, the device can also evaluate data to determine what action to take during the subsequent feedforward phase 1216. Prior to feedforward phase 1216, the controller can perform a step change 1214 in FdO2. The flow therapy device can make a step change in FdO2 to attempt to bring the actual SpO2 within or near the target range. After making the step change in FdO2, FdO2 can be maintained at a constant duration during feedforward phase 1216 to allow the patient's SpO2 to stabilize.

[0592] At the end of the waiting phase 1212, data from several parameters can be evaluated to determine the magnitude of the step change 1214 and whether the feedforward phase 1216 should be executed. First, the patient's SpO2 can be compared to a target SpO2 range. If the patient's SpO2 is within or above the target range, the step change 1214 and feedforward phase 1216 can be bypassed, and the controller will transition directly from the waiting phase 1212 to the control phase 1220. If the patient's SpO2 is below the target range, the controller can determine whether the step change 1214 is needed. For example, a large recent change in FdO2 might mean that a step change 1214 in FdO2 is not needed. If a step change 1214 is needed, the device will proceed to the step change 1214 after the waiting phase 1212 ends.

[0593] For step change 1214, the controller determines the change in FdO2 to be achieved. The magnitude of the step change is based at least in part on the current SpO2, the target SpO2, and the oxygen efficiency.

[0594] Because of the lag between changing FdO2 and observing a change in SpO2, there may be changes in FdO2 that have not yet taken effect when calculating oxygen efficiency. The flow therapy device 10 can take into account any recent changes in FdO2 when determining the predicted SpO2, oxygen efficiency, and the magnitude of step changes.

[0595] During the feedforward phase 1216, the controller maintains FdO2 at the determined FdO2. In the absence of a step change 1214, FdO2 can be maintained at the current FdO2 value. In the presence of a step change 1214, the determined FdO2 is the sum of the previously measured FdO2 and the magnitude of the step change. The feedforward phase 1216 may continue until a defined maximum time for the feedforward phase is reached (e.g., 60 seconds, 120 seconds, or another defined maximum duration), or until the measured SpO2 is at and / or within the target SpO2 value. After the feedforward phase 1216 ends, the control phase 1220 begins.

[0596] Predictive control during the control phase

[0597] During control phase 1220, the controller modulates FdO2 within the control range to achieve the target SpO2. The formula for determining the target FdO2 during the control phase is shown below in velocity form.

[0598]

[0599] Where E SpO2 It is the error function, and K P K I and K D These are the PID coefficients. The error function represents the distance between the patient's SpO2 and the target SpO2, and it is calculated differently depending on whether a Smith predictor is used. In some configurations, a first-order low-pass Butterworth filter can also be used to filter the error function to remove random measurement errors.

[0600] As described in this article, the PID coefficients can be tuned to better achieve the patient's target SpO2. Furthermore, the PID coefficients can be weighted according to the reciprocal of the patient's oxygen efficiency, allowing the controller to make larger changes to FdO2 for patients with low oxygen efficiency, thus achieving a consistent SpO2 variation.

[0601] When using the default PID or a tuned PID, the error function is as follows.

[0602]

[0603] As discussed herein, the PID coefficients can be tuned based on patient characteristics. Furthermore, the Smith predictor can be used to remove the pure time delay between when a change is made in FdO2 and when a corresponding change is detected in SpO2. The delay time can be estimated based on the flow rate of the flow therapy device 10.

[0604] The Smith predictor can use a model of a patient's SpO2 response based on changes in FdO2. Using this model, the Smith predictor can predict how SpO2 will behave after a delay.

[0605] An error term, representing the error between the modeled SpO2 and the measured SpO2, is used to continuously correct the predicted value. Once an initial SpO2 prediction is made, it is then adjusted by incorporating the error term. Combining these parameters yields the error-adjusted predicted SpO2 value. This value is then used to calculate the error function. When the model and the estimated delay time are sufficiently accurate, the Smith predictor PID can function similarly to a default or tuned PID with no delay time used in patients.

[0606] As described in this paper, in some configurations, the Smith predictor model can be evaluated using the cumulative change in FdO2 multiplied by a coefficient representing the relationship between changes in FdO2 and changes in SpO2. This coefficient is patient-specific and generated using initial estimates. It is then continuously updated based on real-time data received from the patient, such as SpO2 and FdO2. This coefficient can be updated during all phases of the closed-loop control mode and is not limited to a specific learning phase.

[0607] The coefficients used in the Smith predictor model can be the patient's oxygen efficiency. The patient's oxygen efficiency can be continuously evaluated and updated within the model's algorithm. As described in this paper, the oxygen efficiency estimate is updated throughout the waiting phase, feedforward phase, and control phase, as well as during manual mode (if a pulse oximeter is being used).

[0608] PID controller weighted

[0609] As described herein, the control signal can be weighted based on the signal quality from the patient sensor 26. Additionally, the weighting can depend on whether the measured SpO2 is above or below a target value. When the measured SpO2 is below the target, the weight can be equal to or greater than one, between 1 and 2, between 1.1 and 1.75, between 1.2 and 1.5, 1.25, or any value or range within the aforementioned ranges. When the measured SpO2 is above the target, the weight can be less than or equal to one, between 0.25 and 1, between 0.5 and 0.9, between 0.75 and 0.85, 0.8, or any value or range within the aforementioned ranges. This allows the controller to increase the oxygen concentration more quickly when SpO2 is too low, while also reducing the chance of overshooting the SpO2 target and causing a decrease in oxygen concentration when SpO2 is too high. This weighting process can help reduce the amount of time a patient receives lower concentrations of oxygen.

[0610] Processes used to control flow therapy equipment

[0611] Figures 13A to 13C A flowchart illustrating a method for controlling the operation of a flow therapy device during a high-flow treatment period is shown. Process 1300, as well as subprocesses 1310 and 1330, can be implemented by any system capable of controlling the operation of the flow therapy device. For example, process 1300 can be implemented wholly or partially by controller 13. Multiple different controllers can be configured to implement process 1300. For example, different aspects of the process can be implemented by controllers. A remotely located system can be configured to be part of the implementation of the process. For example, a remotely located system can be configured to perform the system setup phase 1310, and the control phase 1330 can be performed locally by controller 13. Although any number of systems can implement process 1300 wholly or partially, for the sake of simplicity, process 1300 will be described with respect to specific components of controller 13 and flow therapy system 10.

[0612] In process 1300, at box 1302, the user can initiate a high-flow treatment period on the flow therapy device 10. To initiate the treatment period, the flow therapy device may require a defined set of information about the patient. For example, input may include one or more patient characteristics, such as patient type (e.g., normal, hypercapnia, or other), age, weight, height, sex, and / or other patient characteristics. The flow therapy device 10 may also require the user to set a target SpO2 value or range for the patient. The flow therapy device may automatically determine the target SpO2 value or range for the patient, at least in part, based on the received patient characteristics. After receiving the information (if necessary), the user can initiate the treatment period, and the process can proceed to box 1310.

[0613] At box 1310, the controller can perform the setup phase. (See attached reference.) Figure 13B Let's describe the setup phase sub-process 1310. At box 1312, the controller waits for a defined time period before proceeding. This waiting time allows the patient's SpO2 value to stabilize. During the waiting phase 1312, the oxygen inlet valve can default to the previous FdO2 setting, and the valve can be opened or closed as needed.

[0614] At box 1314, during the waiting phase, the controller measures and records patient parameters and device parameters. The patient parameter can be SpO2, and the device parameter can be FdO2. The controller can measure and record FdO2 and SpO2 data. The controller can determine oxygen efficiency based on SpO2 and FdO2.

[0615] At box 1316, the controller can determine whether the patient's SpO2 is within or above the target SpO2 range. If the target SpO2 is already within or above the target range, the process bypasses the step change and feedforward phases and proceeds directly to the control phase at box 1322. If the patient's SpO2 value is not within the target range, the process proceeds to box 1317.

[0616] At block 1317, the controller can determine whether FdO2 is at an acceptable level. If FdO2 is already at an acceptable level due to a recent change in FdO2, no further adjustment of FdO2 is required before the feedforward phase, and the process bypasses the step change and proceeds directly to block 1320. If FdO2 is not at an acceptable level, the process proceeds to block 1318.

[0617] At box 1318, the controller can perform a step change in oxygen concentration. The controller can perform this step change to increase the oxygen concentration of the gas stream to a new level based on the target SpO2 level, FdO2, and oxygen efficiency. The new FdO2 value can be determined based on factors such as the patient's current SpO2. The new FdO2 can be selected by the clinician based on their own expertise and knowledge. The selected FdO2 can bring the patient's SpO2 closer to the target SpO2 level. The FdO2 can be determined automatically by controller 13.

[0618] At block 1320, the controller may execute a feedforward phase. During feedforward phase 1216, the controller maintains FdO2 at a defined value for a defined amount of time. The controller may perform the feedforward phase without changing FdO2 when bypassing a step change. Feedforward phase 1216 may continue until a defined maximum time for the feedforward phase is reached (e.g., 120 seconds), or until the measured SpO2 is at and / or within the target SpO2 value. After the feedforward phase is complete, the process proceeds to block 1322 and begins control phase subprocess 1330. (Regarding...) Figure 13C Let's further describe the control phase subprocess 1330.

[0619] At box 1332, the controller performs a control phase that uses a PID controller to control the execution of the flow therapy device 10. The PID controller can be configured to control FdO2 based on a target SpO2 and the measured SpO2. At box 1334, the controller can use a predictive algorithm (e.g., a Smith predictor) to predict SpO2. At box 1336, the controller can determine a target FdO2 value based on the predicted patient SpO2 value. At box 1338, the controller can determine oxygen efficiency based on the measured SpO2 value and the measured FdO2. At box 1340, the controller can adjust the output of the FdO2 value based on a signal quality indicator associated with the patient sensor. At box 1342, the controller control signal to the oxygen valve is adjusted. The difference between the predicted SpO2 and the target SpO2 is calculated, and the result is fed back to the PID controller to control the oxygen valve. At box 1344, the controller determines whether the treatment period is complete. If the treatment period is not complete, the process continues until the end of the treatment period.

[0620] Motor and / or sensor module configuration

[0621] Figures 14 to 16 The diagram illustrates the configuration of the flow therapy device 10. The flow therapy device includes a main housing 100. The main housing 100 has an upper main housing chassis 102 and a lower main housing chassis 202.

[0622] like Figure 14 and Figure 15 As shown, the lower chassis 202 has a motor recess 250 for receiving a removable or non-removable motor and / or sensor module 400, the motor recess being in Figures 14 to 15 As shown in the diagram and described in further detail below, a recessed opening 251 is provided in the bottom wall 230 near its rear edge for receiving a removable or non-removable motor / sensor module 400. Figure 14 and Figure 15 As shown in the figure and described in further detail below.

[0623] Figures 16 to 19 The motor and / or sensor module or sub-assembly 400 is shown in more detail. As discussed above, the lower chassis 202 includes a recess 250 for receiving the motor and / or sensor module 400.

[0624] exist Figures 16 to 19 In the form shown, the motor and / or sensor module 400 includes a stacked arrangement of three main components: a base 403 of the sub-assembly 400 (on which the motor 402 is positioned), an outlet gas flow path and sensing layer 420 positioned above the base 403, and a cover layer 440. The base 403, sensing layer 420, and cover layer 440 are assembled together to form a sub-assembly housing having a shape complementary to the shape of the recess 250, such that the sub-assembly 400 can be received in the recess 250. The base 403 is configured to close the recess opening 251 when the sub-assembly 400 is positioned in the recess 250. The sub-assembly 400 can be held in place in the recess in any suitable manner (e.g., using fasteners, clips, or quick-release arrangements) or can be secured in a non-removable manner.

[0625] The sensing layer includes a gas flow path with one or more sensors, which is arranged to deliver gas to the outlet port of the housing.

[0626] Motor 402 has a body 408 that defines an impeller chamber for housing an impeller. Motor 402 can be any suitable gas blower motor, and can be, for example, a motor and impeller assembly of the type described in the publicly available PCT specification WO2013 / 009193. The contents of that specification are incorporated herein by reference in their entirety.

[0627] Gas outlet 406 is in fluid communication with the outlet gas flow path and the gas inlet of sensing layer 420, which are stacked on top of the motor. Layer 420 includes a body 422 comprising a plurality of mounting legs 425 that can be inserted into a plurality of mounting slots (not shown) of base 403 to secure body 422 to base 403. In one configuration, body 422 defines a gas flow path connecting gas outlet 406 to the gas flow path and the gas inlet of sensing layer 420.

[0628] Body 422 defines the lower portion 426 of the sensing and gas flow path. Cover layer 440 has body 442 that defines the upper portion 446 of the sensing and gas flow path, wherein the shapes of the upper portion 426 and the lower portion 446 substantially correspond to each other.

[0629] like Figure 17 and Figure 18As shown, the gas flow path includes elongated straight gas flow portions 428 and 448. An inlet is in fluid communication with a tangential inlet portion 430 and 450 of the gas flow path, located at or near the inlet end of the elongated straight portion 428 and 448. Recesses 433, 453 and 434, 454 may be provided at opposite ends of the elongated straight portion of the gas flow path.

[0630] The gas outlet port 452 extends vertically through the body 442 of the cover 440 and is located at or near the opposite outlet ends of the elongated straight portions 428, 448 of the gas flow path. The gas outlet port 452 is in fluid communication with the upper portion of the motor recess 250, which in turn is in fluid communication with the gas flow channel. Similarly, due to the configuration of the walls 252 and top plate 262 of the recess 250, if gas leaks from the motor / sensor module 400, the gas will be vented to the atmosphere rather than entering the portion of the main housing 100 that houses a large number of electronic components and control devices. The recess 250 may include spacers (e.g., ... Figure 15 The lugs shown protruding downwards from the top plate 262 are designed to maintain an appropriate spacing for the gas flow from the gas outlet port 452 and the top plate recess 262.

[0631] from Figure 17 It can be seen that at least a portion of the gas flow path passing through and exiting the motor and / or sensing module 400 has a tortuous or meandering configuration. For example, the direction of the gas flow traveling through the elongated portions 428, 448 is generally opposite to the direction of the gas flow traveling from the gas outlet port 452 to the inlet of the gas flow channel passing through the bend 324.

[0632] like Figure 18 and Figure 19 As shown, the overlay 440 includes a sensing printed circuit board (PCB) 456. The overlay 440 may also include one or more temperature sensors, such as thermistors located in elongated portions 428, 448 of the gas flow path. One sensor will measure the gas temperature, and another sensor can be used as a redundant temperature sensor. Alternatively, one of the thermistors can be used as a reference flow sensor (e.g., via a thermostatic thermistor), and the measured temperature can be used to determine the gas flow rate through portions 428, 448 of the gas flow path. One or more temperature sensors may be located on a portion of the sensing PCB 456 facing the gas flow. Furthermore, the sensing PCB 456 may include other sensors, including but not limited to pressure sensors, humidity sensors, and dew point sensors.

[0633] One or both of the electronic circuit boards 272 will be electrically connected or coupled to the sensor to process the information received from the sensor and operate the device 10 based on the information received from the sensor.

[0634] In an alternative configuration, the motor / impeller unit can be positioned remotely from device 10. In this configuration, the module received in recess 250 may consist only of a gas flow path and various sensors to deliver gas to the fixed bend 324 and thereby to the liquid chamber 300. In another alternative configuration, the module received in recess 250 may consist only of a motor and a gas flow path, but without sensors.

[0635] In another alternative configuration, the motor and / or sensor module 400 may not be removable from the recess 250, but may be permanently mounted therein. In this configuration, the benefit of gas isolation from electrical / electronic components will still be provided.

[0636] The flow path is compact and has fewer turns / sharp bends, which reduces flow separation and lowers flow resistance.

[0637] The arrangement of the motor and flow path provides another layer of isolation due to the wall arrangement.

[0638] The modular motor and / or sensor modules allow for the disassembly of the modules when cleaning and / or maintenance are required.

[0639] Advantageously, there are no leakage paths in the motor and / or sensor modules. While the motor and / or sensor modules may be potential leak points, a leak in this area would result in oxygen being released into the atmosphere or into the liquid chamber.

[0640] Valve module

[0641] Figures 20 to 28 A first configuration of valve module 4001 is shown. Valve module 4001 controls the flow of oxygen and / or other gases into the gas flow path of device 10, and enables device 10 to adjust the proportion of oxygen entrained in the airflow. The valve module is formed as a modular unit to facilitate manufacture, assembly, repair, or replacement, for example, in the event of failure, routine maintenance, or future upgrades / improvements.

[0642] Valve module 4001 is vertically inserted upwards into valve module housing 306 in the lower chassis 202 of the main housing. In alternative configurations, the valve module can be inserted into the housing in different directions, such as forward, downward, rearward, or lateral. Valve module 4001 can be removably engaged with the main housing of the equipment, such that valve module 4001 is substantially received within the housing and accessible from the outside of the housing. In some configurations, valve module 4001 can be fixed within the main housing and is not removable. A portion of valve module 4001 is arranged to be substantially flush with the outer wall of the housing when the valve module is removably engaged with the housing.

[0643] Because the valve module is modular and accessible from the outside of the housing, it can be replaced without significant disassembly of device 10 and without damaging the seals of the device housing. Since the valve module 4001 is essentially received within the housing, it becomes integrated with the housing when engaged, without increasing the size or volume of the housing. Furthermore, the components of the valve module (e.g., valve 4003 and valve manifold 4011 described below) are protected during use because they are positioned within the valve support 4051 and the main housing of the device. This configuration significantly reduces the likelihood of damage to the valve module and its components should device 10 be accidentally bumped or dropped.

[0644] The valve module includes a flow control valve 4003 arranged to control the flow of gas through the valve manifold 4011. This valve is arranged to control the flow of gas entering a portion of the equipment. For example, the valve may be arranged to control the flow of gas to the filter module 1001. Alternatively, valve 4003 may be arranged to control the flow of gas to another portion of the equipment. Valve module 4001 and filter module 1001 are located upstream of blower 402 and motor and / or sensor module 400. In some embodiments, valve module 4001 and filter module 1001 are located downstream of blower 402.

[0645] Valve 4003 includes a cylindrical body 4005 and a valve component within the body.

[0646] For example, a flow control valve can be a solenoid valve, a motor-driven valve, or a piezoelectric valve.

[0647] In a solenoid valve, the valve component is actuated between an open position and a closed position. A solenoid valve can be a proportional valve. The range of gas flow through the valve (i.e., due to the valve opening degree) is relative to the current supplied to the valve.

[0648] Alternatively, a modulated input signal can be used to control the solenoid valve, thereby modulating the valve between the open and closed positions.

[0649] Valve 4003 can be a needle valve, piston valve, gate valve, ball valve, butterfly valve, globe valve, etc. The valve can be pressure-compensated.

[0650] In some configurations, the valve is a normally closed valve; that is, the valve is closed when power is off. This prevents the connected gas supply line from continuously releasing oxygen or other gases when the equipment is powered off. In some alternative configurations, the valve is a normally open valve.

[0651] In some configurations, valve 4003 is an electrically actuated proportional solenoid valve. For example, the valve may be an µProp valve available from Steger GmbH & Co. KG in Erligheim, Germany, an Asco 202 series Preciflow valve available from Emerson / Asco Valves in New Jersey, or any other suitable type of valve.

[0652] The valve can have a coaxial inlet-outlet configuration.

[0653] Valve module 4001 includes a valve manifold 4011 having a body 4013 that defines a gas flow path 4015 between a valve manifold gas inlet 4017 and one or more valve manifold gas outlets 4019. The gas inlet 4017 of the valve manifold is axially positioned at or toward an end of the valve manifold. In some configurations, valve manifold 4011 has a single gas outlet 4019 radially positioned on the valve manifold. In some configurations, valve manifold 4011 includes a plurality of valve manifold gas outlets 4019 radially positioned around the valve manifold. The valve manifold outlets 4019 are arranged to deliver gas from the valve manifold gas inlet 4017 to the gas inlet of filter module 1001. The radial arrangement of the outlets(s) 4019 helps direct oxygen (or other gases) toward the filter module, thereby minimizing oxygen loss and improving entrainment efficiency. Valve 4003 is arranged to control the gas flow from valve manifold gas inlet 4017 to valve manifold gas outlet 4019. When the valve is "closed", it blocks the gas flow from gas inlet 4017 to gas outlet 4019. When the valve is "open", it allows the gas flow from gas inlet 4017 to gas outlet 4019.

[0654] The end 4018 of the valve manifold 4011 opposite the gas inlet receives and seals with the valve 4003, such that the valve and the valve manifold are in fluid communication. End 4018 includes a flange 4023 to be mounted to the valve. The flange 4023 has an orifice 4023A for receiving a fastener 4023F to secure the manifold to the valve 4003. Multiple O-rings may be provided around the periphery of the interface between the valve 4003 and the valve manifold 4011 to seal the valve to the valve manifold.

[0655] Valve manifold 4011 directs / disperses oxygen from the valve via radially positioned gas outlet 4019. In some embodiments, a single gas outlet 4019 is provided in the valve manifold. Noise is generated as oxygen passes through the outlet(s). Because the device may be used in a medical and / or home environment adjacent to a patient, it is desirable to minimize the generated noise.

[0656] Alternatively or additionally, a cover, pipe, or channel may be formed around, near, or in fluid communication with the valve manifold outlets 4019 to reduce noise. Additionally and / or alternatively, foam, etc., may be placed around the valve manifold, near the valve manifold outlets, to reduce noise.

[0657] A small filter can be installed inside the inlet of the valve manifold gas inlet 4017 to prevent dust or particles from being introduced into the valve.

[0658] The end of the valve manifold corresponding to the gas inlet 4015 is arranged to receive and connect to connector 4031. In the form shown, connector 4031 is a rotary connector. Alternatively, connector 4031 may be arranged such that the gas inlet 4033 of the connector can move in different ways, such as translational or pivotal movement.

[0659] Valve module 4001 is located at the beginning of the flow path of the equipment. If valve 4003 is blocked (i.e., blocked by dust, particles, etc.) and thus remains open, excess pressurized oxygen or other gas will open from the multiple ambient air inlets in valve support 4051 (e.g., Figure 26 The pressure is "poured" out through the opening (shown as being below the rotary connector). This prevents any excessive pressure from reaching the patient. Therefore, the system can inherently be considered pressure-limiting without the need for a pressure relief valve.

[0660] Multiple openings 4051O are provided in the valve support 4051 to allow ambient air to be drawn into the gas flow path of the device. The ambient air flow path passes near or adjacent to the valve. In the form shown, the openings 4051O are located around the gas inlet of the rotary connector. Alternatively, the openings may be located elsewhere in the valve support. When the blower motor 402 of the device operates, it creates a suction through the filter module and valve module to draw ambient air into the device. The ambient air flow path passes through the valve module and allows ambient air to be entrained by the gas flow from the flow control valve. The ambient air flow path has a gas outlet adapted to deliver ambient air such that it flows through one or more temperature sensors of the device used to deliver the gas flow.

[0661] The device can simultaneously draw in gas from the gas inlet of the valve manifold and ambient air, or pressurize the gas from the gas inlet to force it through a filter. The gas will exit the valve module and enter the gas inlet in the filter. The device can be configured such that the gas from the gas inlet and ambient air are dynamically entrained / mixed within the device before being delivered to the gas outlet.

[0662] The valve module can be configured to minimize the pressure drop across the valve module by one or more of the following: placing a large opening 4051O for ambient air around the rotary connector and / or elsewhere; having a radius / circular / sloping edge in the flow path (i.e., for example, inside the valve manifold) to minimize turbulence and smooth the flow.

[0663] The valve module 4001 described herein is arranged to connect directly to the filter 1001 to provide a gas flow path from the valve module to the filter. No hose connection is required between the valve module and the filter module. This minimizes the size of the components and facilitates easy connection and disconnection of the modular valve and filter modules.

[0664] The filter module and valve module described herein can provide a varied gas flow path for the device. For example, the valve module can control the oxygen flow into the device via the valve module and filter module. Alternatively, by means of a gas inlet through the first sub-compartment (e.g., Figure 24 The inlet (1011) connects the alternative oxygen source directly to the filter module, bypassing the valve module. This is useful in situations where the user may want to manually adjust the oxygen supply (i.e., via a wall-mounted supply rotor flow meter).

[0665] It will be understood that the filter modules and valve modules described herein can be used individually in devices used to deliver gas streams. Alternatively, the filter and valve modules can be used together as a filter and valve assembly to improve functionality.

[0666] In the configuration shown, device 10 receives oxygen by at least one of the following methods: via a valve module (for automatic oxygen regulation of the device); or via an alternative gas inlet located on top of the filter (allowing attachment of a manually adjustable oxygen supply - i.e., such as via a wall-mounted supply rotor flow meter).

[0667] The various configurations described are merely exemplary. Any one or more features from any of these configurations may be used in combination with any one or more features from any of the other configurations.

[0668] For example, the rotary connector used in a valve module may have additional functionality. In some configurations, the rotary connector may be arranged to rotate about more than one axis; and may, for example, have two adjacent rotary connection portions with axes of rotation transverse to each other, such that the gas inlet of the rotary connector can rotate about two axes. In some configurations, the rotary connector may include a ball-and-socket arrangement or similar arrangement, such that the gas inlet of the rotary connector can rotate in substantially any direction. In some configurations, the rotary connector may be arranged to provide both rotational and translational movement; such that the gas inlet of the rotary connector can rotate about one or more axes and, for example, travel in a straight line. This may be useful for translating a gas inlet from one part of the equipment to another, such as, for example, from one side of the equipment to the other. In some configurations, the gas inlet may be arranged for translation rather than rotation.

[0669] As another example, while the motor and / or sensor subassembly recess is described as being located in the bottom side of the main housing, it may alternatively be located in the rear, side, front, or top of the housing. In such variations, the air and / or oxygen inlet may also be located differently depending on requirements.

[0670] As another example, instead of a liquid chamber and a compartment, the liquid chamber is configured such that the liquid chamber is inserted into and removed from the compartment from the front of the housing, and the liquid chamber is configured such that the liquid chamber is inserted into and removed from the compartment from the side, rear, or top of the housing.

[0671] As another example, although the filter module is described as being inserted into the housing from above and the valve module from below, any one or both of these components can be inserted into any suitable part of the housing, such as the upper part, lower part, side part, front part, or rear part.

[0672] The filter module and valve module are described with reference to a flow therapy device capable of delivering heated and humidified gas to a patient or user. This device is suitable for treating chronic obstructive pulmonary disease (COPD). The device can be configured to deliver gas at a high flow rate to the patient interface (high-flow therapy), particularly nasal high-flow therapy.

[0673] Alternatively, filter modules and / or valve modules may be used in devices for different purposes. The device may be a high-flow-rate treatment device or a low-flow-rate treatment device. Features may also be included in devices for providing continuous positive airway pressure (CPAP), which deliver gas (humidified or otherwise) under positive pressure.

[0674] Alternatively, the filter module and / or valve module can be used with devices that do not require a humidifier and therefore do not require the liquid chamber 300 or compartment 108 features. For example, it will be understood that configurations that isolate the motor and gas flow path from electrical and electronic components are widely used in other types of gas delivery equipment.

[0675] The term “flow therapy device” is intended to encompass all such variations.

[0676] Any reference to prior art in this specification is not and should not be construed as an admission or in any way implying that the prior art constitutes part of common general knowledge in the relevant field in any country of the world.

[0677] In this document, references to directional terms such as “up,” “down,” “forward,” “backward,” “horizontal,” and “vertical” are used to indicate the situation when the device is in a typical position of use and to show and / or describe relative direction or orientation.

[0678] Unless the context clearly requires otherwise, throughout the specification and claims, the words “comprising,” “including,” etc., shall be interpreted in a inclusive sense, not in an exclusive or exhaustive sense, that is, in the sense of “including but not limited to.”

[0679] As used herein, the terms “approximately,” “about,” and “substantially” mean an amount that is close to the stated amount and still performs the desired function or achieves the desired result. For example, in some embodiments, as the context permits, the terms “approximately,” “about,” and “substantially” may refer to an amount that is less than or equal to 10%, less than or equal to 5%, and less than or equal to 1% of the stated amount.

[0680] Any reference to prior art in this specification is not and should not be construed as an admission or in any way implying that such prior art is part of common general knowledge in the relevant field in any country of the world.

[0681] The disclosed devices and systems can also be broadly referred to as the parts, elements and features that are individually or jointly mentioned or indicated in the specification of the application, and any or all combinations of two or more of said parts, elements or features.

[0682] In the above description, references have been made to components in whole or in part having known equivalents thereof, which are incorporated herein as if stated separately.

[0683] Depending on the implementation, certain actions, events, or functions of any algorithm, method, or process described herein may be performed in a different sequence, and may be added, combined, or omitted entirely (e.g., not all described actions or events are necessary for the practice of the algorithm). Furthermore, in some embodiments, actions or events may be performed simultaneously rather than sequentially, for example, through multithreading, interrupt handling, or on multiple processors or processor cores or other parallel architectures.

[0684] It should be noted that various variations and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the disclosed apparatus and system, and without diminishing its accompanying advantages. For example, various components may be repositioned as needed. Therefore, such changes and modifications are contemplated to be included within the scope of the disclosed apparatus and system. Furthermore, not all of these features, aspects, and advantages are necessary for practicing the disclosed apparatus and system. Therefore, the scope of the disclosed apparatus and system is intended to be defined solely by the appended claims.

Claims

1. A breathing device for providing a gas flow to a patient, the breathing device comprising: The controller is configured as follows: Receive an indication of the oxygen concentration, i.e., FdO2, of the gas stream supplied to the patient; Receive the patient's oxygen saturation, i.e., SpO2; Receive target SpO2; During the control phase, feedback control is used to control the FdO2 to achieve the target SpO2; During the waiting phase prior to the control phase, a determination is made regarding whether to enter the feedforward phase before transitioning to the control phase, wherein the FdO2 remains constant during the waiting phase. as well as After the waiting phase and before transitioning to the control phase, the feedforward phase is entered based on a determination related to whether to enter the feedforward phase, and feedforward control is used to control the FdO2 so that the patient's SpO2 approaches the target SpO2.

2. The breathing device according to claim 1, wherein, The determination of whether to enter the feedforward phase is based at least in part on the target SpO2 and the received SpO2.

3. The breathing device according to claim 1 or 2, wherein, This determination is further based, at least in part, on the patient's oxygen efficiency.

4. The breathing device according to any one of claims 1 to 2, wherein, Oxygen efficiency is determined at least in part based on the received SpO2 and the received FdO2.

5. The breathing device according to any one of claims 1 to 2, wherein, If the controller determines that a feedforward phase is not needed, the controller directly enters the control phase.

6. The breathing device according to any one of claims 1 to 2, wherein, If the controller determines that a feedforward phase is needed, then the controller enters that feedforward phase.

7. The breathing device according to any one of claims 1 to 2, wherein, Before entering this feedforward phase, the controller determines whether a step change in FdO2 is needed.

8. The breathing device according to claim 7, wherein, The determination relating to whether or not to perform this step change of FdO2 is based at least in part on the target SpO2 and the received SpO2.

9. The breathing device according to claim 7, wherein, The determination of whether or not this step change in FdO2 is performed is further based, at least in part, on the patient’s oxygen efficiency.

10. The breathing device according to claim 7, wherein, The determination of whether or not to perform this step change in FdO2 is further based, at least in part, on the most recent changes in FdO2.

11. The breathing device according to claim 7, wherein, If the controller determines that the step change is needed, then the controller performs the step change of FdO2.

12. The breathing device according to claim 7, wherein, The magnitude of this step change in FdO2 is at least partially based on the target SpO2 and the received SpO2.

13. The breathing device according to claim 12, wherein, The magnitude of this step change in FdO2 is further based, at least in part, on the patient's oxygen efficiency.

14. The breathing device according to claim 13, wherein, The magnitude of this step change in FdO2 is further based, at least in part, on recent changes in FdO2.

15. The breathing device according to claim 7, wherein, Following an optional step change, the controller maintains a constant FdO2 level for the duration of the feedforward phase.

16. The breathing device according to any one of claims 1 to 2 and 8 to 15, wherein, Once the feedforward phase ends, the controller enters the control phase.

17. The breathing device according to any one of claims 1 to 2 and 8 to 15, wherein, If the duration of the feedforward phase exceeds the time limit, the feedforward phase ends.

18. The breathing device according to any one of claims 1 to 2 and 8 to 15, wherein, If the received SpO2 exceeds the target SpO2, the feedforward phase ends.

19. The breathing device according to any one of claims 1 to 2 and 8 to 15, wherein, The breathing device has a lower limit of not less than 21% or an upper limit of not more than 100% for FdO2 control.

20. The breathing device according to any one of claims 1 to 2 and 8 to 15, wherein, The breathing device is configured to deliver a high-flow-rate nasal gas stream, or NHF gas stream, to the patient.

21. The breathing device according to any one of claims 1 to 2 and 8 to 15, further comprising a humidifier.

22. The breathing device according to any one of claims 1 to 2 and 8 to 15, further comprising a gas composition sensor configured to determine received FdO2 during operation of the breathing device, wherein, The gas composition sensor is an ultrasonic transducer system.

23. The breathing device according to any one of claims 1 to 2 and 8 to 15, wherein, The controller is configured to receive an indication of the patient's oxygen saturation, i.e., SpO2, from a pulse oximeter.

24. The breathing device according to any one of claims 1 to 2 and 8 to 15, wherein, In this control phase, the controller is further configured to determine the patient's predicted SpO2 based at least in part on data indicating the received FdO2 of the gas flow, and to control the FdO2 of the gas flow to the patient based at least in part on the patient's predicted SpO2.

25. The breathing device according to claim 23, wherein, The controller is further configured to receive an indication of the signal quality of the pulse oximeter and to apply a weighted approach to the control of the FdO2 based at least in part on the signal quality.

26. The breathing device according to claim 19, wherein, The controller is further configured to cut off or narrow the FdO2 control range if the FdO2 control range is to be adjusted to be above the upper limit or below the lower limit.

27. The breathing device according to claim 26, wherein, The controller is further configured to reduce the upper limit only if the lower limit is 21% and the FdO2 control range is to be adjusted below the lower limit.

28. The breathing device according to any one of claims 26 to 27, wherein, The controller is further configured to increase the upper limit while keeping the lower limit fixed if the upper limit of the FdO2 control range is to be increased and is less than 100%.

29. The breathing device according to claim 28, wherein, The controller is further configured to increase the lower limit of the FdO2 control range if the FdO2 control range exceeds a specified range.

30. The breathing device according to any one of claims 26 to 27 and 29, wherein, The controller is further configured to increase only the lower limit of the FdO2 control range if the upper limit is 100% and the FdO2 control range is to be adjusted to exceed the upper limit.

31. The breathing device according to any one of claims 26 to 27 and 29, wherein, The size of this control range shall be no less than 5% and no more than 30%.

32. A controller for controlling a breathing apparatus for providing a gas flow to a patient, the controller being included in the breathing apparatus and configured to: Receive an indication of the oxygen concentration, i.e., FdO2, of the gas stream supplied to the patient; Receive the patient's oxygen saturation, i.e., SpO2; Receive target SpO2; During the control phase, feedback control is used to control the FdO2 to achieve the target SpO2; During the waiting phase preceding the control phase, determinations are made regarding whether to enter the feedforward phase before transitioning to the control phase. During this waiting period, the FdO2 remains constant; as well as After the waiting phase and before transitioning to the control phase, the feedforward phase is entered based on a determination related to whether to enter the feedforward phase, and feedforward control is used to control the FdO2 so that the patient's SpO2 approaches the target SpO2.

33. The controller according to claim 32, wherein, The determination of whether to enter the feedforward phase is based at least in part on the target SpO2 and the received SpO2.

34. The controller according to claim 32 or 33, wherein, This determination is further based, at least in part, on the patient's oxygen efficiency.

35. The controller according to any one of claims 32 to 33, wherein, Oxygen efficiency is determined at least in part based on the received SpO2 and the received FdO2.

36. The controller according to any one of claims 32 to 33, wherein, If the controller determines that a feedforward phase is not needed, the controller directly enters the control phase.

37. The controller according to any one of claims 32 to 33, wherein, If the controller determines that a feedforward phase is needed, then the controller enters that feedforward phase.

38. The controller according to any one of claims 32 to 33, wherein, Before entering this feedforward phase, the controller determines whether a step change in FdO2 is needed.

39. The controller according to claim 38, wherein, The determination relating to whether or not to perform this step change of FdO2 is based at least in part on the target SpO2 and the received SpO2.

40. The controller according to claim 38, wherein, The determination of whether or not this step change in FdO2 is performed is further based, at least in part, on the patient’s oxygen efficiency.

41. The controller according to claim 38, wherein, The determination of whether or not to perform this step change in FdO2 is further based, at least in part, on the most recent changes in FdO2.

42. The controller according to claim 38, wherein, If the controller determines that the step change is needed, then the controller performs the step change of FdO2.

43. The controller according to claim 38, wherein, The magnitude of this step change in FdO2 is at least partially based on the target SpO2 and the received SpO2.

44. The controller according to claim 43, wherein, The magnitude of this step change in FdO2 is further based, at least in part, on the patient's oxygen efficiency.

45. The controller according to claim 42, wherein, The magnitude of this step change in FdO2 is further based, at least in part, on recent changes in FdO2.

46. ​​The controller according to claim 38, wherein, Following an optional step change, the controller maintains a constant FdO2 level for the duration of the feedforward phase.

47. The controller according to any one of claims 32 to 33 and 39 to 46, wherein, Once the feedforward phase ends, the controller enters the control phase.

48. The controller according to any one of claims 32 to 33 and 39 to 46, wherein, If the duration of the feedforward phase exceeds the time limit, the feedforward phase ends.

49. The controller according to any one of claims 32 to 33 and 39 to 46, wherein, If the received SpO2 exceeds the target SpO2, the feedforward phase ends.

50. The controller according to any one of claims 32 to 33 and 39 to 46, wherein, The breathing device has a lower limit of not less than 21% or an upper limit of not more than 100% for FdO2 control.

51. The controller according to any one of claims 32 to 33 and 39 to 46, wherein, The breathing device is configured to deliver a high-flow-rate nasal gas stream, or NHF gas stream, to the patient.

52. The controller according to any one of claims 32 to 33 and 39 to 46, wherein the breathing device further comprises a humidifier.

53. The controller according to any one of claims 32 to 33 and 39 to 46, wherein the breathing device further comprises a gas composition sensor configured to determine received FdO2 during operation of the breathing device, wherein, The gas composition sensor is an ultrasonic transducer system.

54. The controller according to any one of claims 32 to 33 and 39 to 46, wherein, The controller is configured to receive an indication of the patient's oxygen saturation, i.e., SpO2, from a pulse oximeter.

55. The controller according to any one of claims 32 to 33 and 39 to 46, wherein, In this control phase, the controller is further configured to determine the patient's predicted SpO2 based at least in part on data indicating the received FdO2 of the gas flow, and to control the FdO2 of the gas flow to the patient based at least in part on the patient's predicted SpO2.

56. The controller according to claim 54, wherein, The controller is further configured to receive an indication of the signal quality of the pulse oximeter and to apply a weighted approach to the control of the FdO2 based at least in part on the signal quality.

57. The controller according to claim 50, wherein, The controller is further configured to cut off or narrow the FdO2 control range if the FdO2 control range is to be adjusted to be above the upper limit or below the lower limit.

58. The controller according to claim 57, wherein, The controller is further configured to reduce the upper limit only if the lower limit is 21% and the FdO2 control range is to be adjusted below the lower limit.

59. The controller according to any one of claims 57 to 58, wherein, The controller is further configured to increase the upper limit while keeping the lower limit fixed if the upper limit of the FdO2 control range is to be increased and is less than 100%.

60. The controller according to claim 59, wherein, The controller is further configured to increase the lower limit of the FdO2 control range if the FdO2 control range exceeds a specified range.

61. The controller according to any one of claims 57 to 58 and 60, wherein, The controller is further configured to increase only the lower limit of the FdO2 control range if the upper limit is 100% and the FdO2 control range is to be adjusted to exceed the upper limit.

62. The controller according to any one of claims 57 to 58 and 60, wherein, The size of this control range shall be no less than 5% and no more than 30%.

63. A respiratory system, comprising: Breathing circuit; Patient interface; as well as The breathing device according to any one of claims 1 to 31.

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