Methods and systems for controlling oxygen delivery in flow therapy devices

Abstract

This application relates to methods and systems for controlling oxygen delivery in a flow therapy device. This disclosure provides a control system for a flow therapy device. The control system can control the delivered oxygen fraction (FdO2) to the patient. The control system can maintain FdO2 at a target level during the treatment period. The control system can automatically control the oxygen inlet valve to control the oxygen flow to the patient.

Description

[0001] This application is a divisional application of invention patent application 202080063505.6, filed on September 10, 2020, entitled "Method and System for Controlling Oxygen Delivery in a Flow Therapy Device". Technical Field

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

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

[0004] According to certain features, aspects, and advantages of the first embodiment disclosed herein, a breathing device for providing a gas flow to a patient is provided, the breathing device comprising: an ambient air inlet; a supplement inlet for receiving supplement gas from a supplement gas source; a valve configured to control the flow rate of supplement gas received through the supplement gas inlet; a flow sensor configured to measure the total flow rate of gas delivered to the patient; and a controller configured to control the delivery of gas to the patient, the controller being configured to: determine a target supplement gas flow rate based at least in part on the total flow rate; and set a valve current based on the target supplement gas flow rate.

[0005] In some configurations of the first embodiment, the supplementary gas includes concentrated oxygen.

[0006] In some configurations of the first embodiment, the controller is configured to determine the target replenishment gas flow rate based at least in part on the target delivered oxygen fraction (FdO2).

[0007] In some configurations of the first embodiment, the controller is configured to determine the target replenishment gas flow rate based at least in part on the oxygen fraction of the ambient air.

[0008] In some configurations of the first embodiment, the controller determines the target supplementary gas flow rate based at least in part on the oxygen fraction of the supplementary gas source.

[0009] In some configurations of the first embodiment, the controller is configured to use a valve model to set the valve current based on the target supplementary gas flow.

[0010] In some configurations of the first embodiment, the valve model is updated over time.

[0011] In some configurations of the first embodiment, the valve model is updated in part based on the measured FdO2.

[0012] In some configurations of the first embodiment, the valve model is updated in part based on the total flow rate.

[0013] In some configurations of the first embodiment, the valve model is updated in part based on the target FdO2.

[0014] In some configurations of the first embodiment, the valve model includes an estimate of the minimum current required to open the valve.

[0015] In some configurations of the first embodiment, the estimate of the minimum current required to open the valve is updated over time.

[0016] In some configurations of the first embodiment, the valve model includes an estimate of the flow rate of the supplemental gas passing through the valve.

[0017] In some configurations of the first embodiment, at least one of a first-order model, the advection diffusion equation, the Navier-Stokes equation, or a machine learning algorithm is used to determine an estimate of the flow rate of the makeup gas passing through the valve.

[0018] According to certain features, aspects, and advantages of the second embodiment disclosed herein, a respiratory device for providing a gas flow to a patient is provided, the respiratory device comprising: an ambient air inlet; a supplement inlet for receiving supplemental gas from a supplemental gas source; a valve configured to control the flow rate of supplemental gas received through the supplemental gas inlet; a gas composition sensor configured to measure the gas composition of a mixture of ambient air and supplemental gas; and a controller configured to control the delivery of gas to the patient, the controller being configured to: regulate valve actuation by controlling valve current; determine a target supplemental gas flow rate; set the valve current based on the target supplemental gas flow rate using a valve model; and update the valve model over time, in part based on measurements received from the gas composition sensor.

[0019] In some configurations of the second embodiment, the supplementary gas includes concentrated oxygen.

[0020] In some configurations of the second embodiment, the valve model is updated over time in part based on predicted changes in the measured gas composition.

[0021] In some configurations of the second embodiment, the predicted changes in the measured gas composition are based at least in part on the current valve position and the current flow rate.

[0022] In some configurations of the second embodiment, the gas composition measurement is the measured delivered oxygen fraction (FdO2).

[0023] In some configurations of the second embodiment, the valve model is updated in part based on the target gas composition over time.

[0024] In some configurations of the second embodiment, the target gas composition is target FdO2.

[0025] In some configurations of the second embodiment, the valve model is updated over time based in part on predicted changes in gas composition.

[0026] In some configurations of the second embodiment, the predicted changes in gas composition are based at least in part on the recent trends in the measured gas composition.

[0027] In some configurations of the second embodiment, the valve model includes an estimate of the minimum current required to open the valve.

[0028] In some configurations of the second embodiment, the estimate of the minimum current required to open the valve is updated over time.

[0029] In some configurations of the second embodiment, the breathing device further includes a flow sensor configured to measure total flow.

[0030] In some configurations of the second embodiment, the controller determines the target replenishment gas flow rate at least in part based on the total flow rate.

[0031] In some configurations of the second embodiment, the controller determines the target replenishment gas flow rate based at least in part on the target FdO2.

[0032] In some configurations of the second embodiment, the controller determines the target replenishment gas flow rate based at least in part on the oxygen fraction of the ambient air.

[0033] In some configurations of the second embodiment, the controller determines the target supplementary gas flow rate based at least in part on the oxygen fraction of the supplementary gas source.

[0034] In some configurations of the second embodiment, the controller updates the valve model at different rates based on the expected breathing rate range.

[0035] In some configurations of the second embodiment, the controller updates the valve model at different rates based on the expected flow oscillation amplitude.

[0036] In some configurations of the second embodiment, the controller updates the valve model at different rates based on the flow rate.

[0037] In some configurations of the second embodiment, the controller uses a feedback loop to update the valve model.

[0038] In some configurations of the second embodiment, the coefficients of the feedback loop are adjusted in part based on the flow rate.

[0039] In some configurations of the second embodiment, the valve model includes an estimate of the flow rate of the supplemental gas passing through the valve.

[0040] In some configurations of the second embodiment, at least one of a first-order model, the advection diffusion equation, the Navier-Stokes equation, or a machine learning algorithm is used to determine an estimate of the flow rate of the supplemental gas passing through the valve.

[0041] 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: an ambient air inlet; a supplement inlet for receiving supplemental gas from a supplemental gas source; a valve, wherein the valve requires a minimum amount of current to open; a gas composition sensor configured to measure the gas composition of a mixture of ambient air and supplemental gas; a main controller configured to control the delivery of gas to the patient, the controller being configured to: adjust the actuation of the valve opening by controlling the valve current; and activate a coarse adjustment controller when a target flow rate of the supplemental gas increases from zero; a coarse adjustment controller configured to: control the actuation of the valve opening by controlling the valve current, wherein the main controller or the coarse adjustment controller is capable of controlling the valve current; iteratively increase the current supplied to the valve; and switch the actuation control of the valve to the main controller after detecting flow through the valve.

[0042] In some configurations of the third embodiment, the controller sets the valve current to an initial value before iteratively increasing the valve current.

[0043] In some configurations of the third embodiment, the initial value corresponds to the minimum possible current required to open the valve opening.

[0044] In some configurations of the third embodiment, the controller performs a step change in the valve current in each iteration of the coarse-tuning controller.

[0045] In some configurations of the third embodiment, the magnitude of the step change increases with each iteration.

[0046] In some configurations of the third embodiment, the magnitude of the step change is at least partially based on the target FdO2.

[0047] In some configurations of the third embodiment, the magnitude of the step change is based at least in part on the total flow.

[0048] In some configurations of the third embodiment, the breathing device includes a gas composition sensor.

[0049] In some configurations of the third embodiment, the gas composition sensor is used to detect the flow rate through the valve.

[0050] In some configurations of the third embodiment, it is determined that flow through the valve is occurring when the concentration of the supplemental gas exceeds the ambient level.

[0051] In some configurations of the third embodiment, flow through the valve is determined to be occurring when the concentration of the supplemental gas exceeds the ambient level by an amount greater than the potential sensor error.

[0052] In some configurations of the third embodiment, the supplementary gas includes concentrated oxygen.

[0053] 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 display; an ambient air inlet; a supplement inlet for receiving supplemental gas from a supplemental gas source; a valve; a gas composition sensor configured to measure the gas composition of a mixture of ambient air and supplemental gas; a controller configured to control the delivery of gas to the patient; receiving an input of a target gas composition; adjusting the actuation of the valve to control the gas composition; displaying the target gas composition in a target mode; displaying the measured gas composition in a measurement mode; monitoring the difference between the target gas composition and the measured gas composition; switching from the target mode to the measurement mode when the difference exceeds a first threshold; and switching from the measurement mode to the target mode when the difference is below a second threshold.

[0054] In some configurations of the fourth embodiment, the supplementary gas includes concentrated oxygen.

[0055] In some configurations of the fourth embodiment, the gas composition measurement is the measured delivered oxygen fraction (FdO2).

[0056] In some configurations of the fourth embodiment, the gas composition sensor includes an acoustic transducer.

[0057] In some configurations of the fourth embodiment, the first threshold is determined in part based on the target gas composition.

[0058] In some configurations of the fourth embodiment, the second threshold is determined in part based on the target gas composition.

[0059] In some configurations of the fourth embodiment, the first threshold is equal to the second threshold.

[0060] In some configurations of the fourth embodiment, the first threshold is higher than the second threshold.

[0061] According to certain features, aspects, and advantages of the fifth embodiment disclosed herein, a breathing device includes: an ambient air inlet for receiving an ambient air flow; a supplementary inlet for receiving supplementary gas from a supplementary gas source; a valve; and a controller configured to control the delivery of gas to a patient, the controller being configured to: adjust the valve position to control the flow rate of supplementary gas added to the ambient air flow; calculate a first level, wherein the first level represents the flow rate of supplementary gas required to achieve a target gas composition for the current total gas flow rate; calculate a second level, wherein the second level represents the flow rate of supplementary gas, the second level being lower than the first level; calculate a third level, wherein the third level represents the flow rate of supplementary gas, the third level being higher than the first level; analyze the patient's respiratory cycle, the respiratory cycle including successive respiratory periods, each respiratory period including an inspiratory period and an expiratory period; control the valve to deliver the first level of supplementary gas during a first portion of each respiratory period in the patient's respiratory period; control the valve to deliver the second level of supplementary gas during a second portion of each respiratory period in the patient's respiratory period; and control the valve to deliver the third level of supplementary gas during a third portion of each respiratory period in the patient's respiratory period.

[0062] In some configurations of the fifth embodiment, the supplementary gas includes oxygen.

[0063] In some configurations of the fifth embodiment, the target gas composition is the target delivered oxygen fraction (FdO2).

[0064] In some configurations of the fifth embodiment, the supplemental gas includes atomized medication.

[0065] In some configurations of the fifth embodiment, the target gas composition is the target atomized drug concentration.

[0066] In some configurations of the fifth embodiment, the breathing device includes a flow generator.

[0067] In some configurations of the fifth embodiment, the flow generator includes a blower.

[0068] In some configurations of the fifth embodiment, the controller is further configured to control the flow generator to deliver the target flow.

[0069] In some configurations of the fifth embodiment, the controller is further configured to control the flow generator to deliver a flow rate that meets or exceeds the patient's inspiratory needs.

[0070] In some configurations of the fifth embodiment, the device provides high-flow nasal treatment.

[0071] In some configurations of the fifth embodiment, the first portion of the respiratory period includes at least a portion of the inspiratory phase of the respiratory period.

[0072] In some configurations of the fifth embodiment, the second portion of the respiratory phase includes at least a portion of the beginning of the expiratory phase of the respiratory phase.

[0073] In some configurations of the fifth embodiment, the third portion of the respiratory phase includes at least a portion of the end of the expiratory phase of the respiratory phase.

[0074] In some configurations of the fifth embodiment, the controller is further configured to take into account the travel time of gas in the breathing circuit between the valve and the patient interface when switching between the first level, the second level, and / or the third level.

[0075] In some configurations of the fifth embodiment, the controller is further configured to estimate the travel time between the valve and the patient interface.

[0076] In some configurations of the fifth embodiment, the controller is further configured to estimate the travel time between the valve and the patient interface based on the current total gas flow rate.

[0077] In some configurations of the fifth embodiment, the second level is a set score of the first level.

[0078] In some configurations of the fifth embodiment, the second level corresponds to no supplemental gas flow being delivered to the ambient air flow.

[0079] In some configurations of the fifth embodiment, the third level is a set multiple of the first level.

[0080] In some configurations of the fifth embodiment, the third level corresponds to the maximum flow rate of the supplemental gas.

[0081] In some configurations of the fifth embodiment, the controller is further configured to calculate a first value and a second value and set a third level to the lower of the first value and the second value, wherein the first value is a limiting multiple of the first level and the second value is the maximum flow rate of the supplementary gas.

[0082] In some configurations of the fifth embodiment, the maximum flow rate of the supplementary gas is determined based on the total flow rate.

[0083] In some configurations of the fifth embodiment, the controller is further configured to calculate the average travel value of the total supplemental gas supplied throughout the breathing period and to generate a savings metric by comparing the average travel value of the total supplemental gas with an estimated amount of supplemental gas that would be used if the valve were controlled to continuously deliver a first level of supplemental gas.

[0084] In some configurations of the fifth embodiment, the breathing device is configured to display the savings metric on the graphical user interface of the breathing device's display.

[0085] In some configurations of the fifth embodiment, the controller is configured to switch to continuous control of the valve to deliver a first level of supplementary gas if the savings metric does not meet the savings threshold.

[0086] In some configurations of the fifth embodiment, the controller is further configured to adjust at least one of the first level, the second level, or the third level to be set for a duration of time.

[0087] In some configurations of the fifth embodiment, the controller is further configured to adjust the duration of the time based at least in part on the flow rate.

[0088] In some configurations of the fifth embodiment, the controller is further configured to adjust the duration of the time at least in part based on the patient’s respiratory rate.

[0089] In some configurations of the fifth embodiment, the controller is further configured to adjust the duration of delivery of supplemental gas to the third level based at least in part on the difference between the first level and the second level.

[0090] According to certain features, aspects, and advantages of the sixth embodiment disclosed herein, a respiratory device includes: an ambient air inlet for receiving an ambient air flow; a supplementary inlet for receiving supplementary gas from a supplementary gas source; a valve; and a controller configured to control the delivery of gas to a patient, the controller being configured to: adjust the valve position to control the flow rate of supplementary gas added to the ambient air flow; calculate a first level, wherein the first level represents the flow rate of supplementary gas required to achieve a target gas composition for the current total gas flow rate; calculate a second level, wherein the second level represents the flow rate of supplementary gas, the second level being lower than the first level; and analyze. The patient's respiratory cycle, which includes successive respiratory periods, each including an inspiratory period and an expiratory period; and determining the suitability of a first operating mode or a second operating mode based on one or more operating parameters and / or patient parameters; and automatically selecting the first operating mode or the second operating mode based on such determination; wherein, in the first operating mode, the valve is continuously controlled to deliver a first level of supplemental gas flow throughout the patient's respiratory period; wherein, in the second operating mode, the valve is controlled to deliver a first level of supplemental gas flow during a first portion of the patient's respiratory period and a second level of supplemental gas flow during a second portion of the patient's respiratory period.

[0091] In some configurations of the sixth embodiment, the controller is further configured to determine the patient's respiratory phase.

[0092] In some configurations of the sixth embodiment, determining the patient's respiratory period includes determining the patient's respiratory rate and respiratory phase.

[0093] In some configurations of the sixth embodiment, the determination of the patient's respiratory phase includes a respiratory confidence metric, wherein the respiratory confidence metric represents confidence that the determination of the patient's respiratory rate and / or respiratory phase is correct.

[0094] In some configurations of the sixth embodiment, the controller is further configured to select the operating mode based at least in part on the respiratory confidence metric.

[0095] In some configurations of the sixth embodiment, the controller is further configured to compare a respiratory confidence metric with a threshold, and to automatically select a first operating mode if the respiratory confidence metric is below the threshold.

[0096] In some configurations of the sixth embodiment, determining the suitability of the first or second operating mode includes comparing the patient’s respiratory rate with a threshold.

[0097] In some configurations of the sixth embodiment, determining the suitability of the first or second operating mode includes comparing the patient's respiratory rate with a threshold, and automatically selecting the first mode if the patient's respiratory rate is higher than the threshold.

[0098] In some configurations of the sixth embodiment, determining the suitability of the first or second operating mode includes comparing the traffic flow with a threshold.

[0099] In some configurations of the sixth embodiment, determining the suitability of the first or second operating mode includes comparing the traffic flow with a threshold, and automatically selecting the first mode if the traffic flow is below the threshold.

[0100] In some configurations of the sixth embodiment, determining the suitability of the first or second operating mode includes calculating the ratio of the patient's respiratory rate to the flow rate and comparing that ratio with a threshold.

[0101] In some configurations of the sixth embodiment, determining the suitability of the first or second operating mode includes calculating the ratio of the patient's respiratory rate to flow rate, comparing the ratio to a threshold, and automatically selecting the first operating mode if the ratio meets the threshold.

[0102] In some configurations of the sixth embodiment, the controller is further configured to estimate the average amount of supplemental gas to be used in the first mode and the second mode, obtain a savings metric by comparing the two values, and select an operating mode based at least in part on the value of the savings metric.

[0103] In some configurations of the sixth embodiment, the first portion of the respiratory period includes at least a portion of the inspiratory phase of the respiratory period.

[0104] In some configurations of the sixth embodiment, the second portion of the respiratory phase includes at least a portion of the beginning of the expiratory phase of the respiratory phase.

[0105] In some configurations of the sixth embodiment, the controller is further configured to calculate a third level, wherein the third level represents the flow rate of the supplemental gas, and the third level is higher than the first level.

[0106] In some configurations of the sixth embodiment, the controller is further configured to control the valve in a second operating mode to deliver a third level of supplemental gas during a third portion of the patient’s respiratory period.

[0107] In some configurations of the sixth embodiment, the third portion of the respiratory phase includes at least a portion of the end of the expiratory phase of the respiratory phase.

[0108] In some configurations of the sixth embodiment, the controller is further configured to take into account the travel time of gas in the breathing circuit between the valve and the patient interface when switching between the first level, the second level, and / or the third level.

[0109] In some configurations of the sixth embodiment, the third level is a set multiple of the first level.

[0110] In some configurations of the sixth embodiment, the third level corresponds to the maximum flow rate of the supplemental gas.

[0111] In some configurations of the sixth embodiment, the controller is further configured to calculate a first value and a second value, and a third level is set to the lower of the first value and the second value, wherein the first value is a limiting multiple of the first level and the second value is the maximum flow rate of the supplementary gas.

[0112] In some configurations of the sixth embodiment, the controller is further configured to adjust at least one of the first level, the second level, or the third level to be set for a duration.

[0113] In some configurations of the sixth embodiment, the controller is further configured to adjust the duration of the time based at least in part on the flow rate.

[0114] In some configurations of the sixth embodiment, the controller is further configured to adjust the duration of the time at least in part based on the patient’s respiratory rate.

[0115] In some configurations of the sixth embodiment, the controller is further configured to adjust the duration of delivery of supplemental gas to the third level based at least in part on the difference between the first and second levels.

[0116] In some configurations of the sixth embodiment, the supplementary gas includes oxygen.

[0117] In some configurations of the sixth embodiment, the target gas composition is the target delivered oxygen fraction (FdO2).

[0118] In some configurations of the sixth embodiment, the controller is further configured to determine the suitability of a first operating mode or a second operating mode at defined time intervals.

[0119] In some configurations of the sixth embodiment, the determined time interval is based on one or more operating parameters and / or patient parameters.

[0120] Features from one or more embodiments or configurations can be combined with features from one or more other embodiments or configurations. Additionally, more than one embodiment can be used together during a patient's respiratory support process.

[0121] The term 'comprising' as used in this specification means 'consisting of at least part of'. In interpreting each expression of the term 'comprising' in this specification, features other than the one or more features following that word may also exist. Related terms such as 'comprise' and 'comprises' will be interpreted in the same manner.

[0122] The intent is that references to the numerical ranges disclosed herein (e.g., 1 to 10) also 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 thus all subranges of all ranges explicitly disclosed herein are explicitly disclosed. These are merely examples of the specific intent, and all possible combinations of numerical values ​​between the enumerated minimum and maximum values ​​should be considered to be explicitly stated in a similar manner in this application.

[0123] 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 shown, described or mentioned in this specification.

[0124] The invention can also be broadly defined as any part, element, or feature individually or collectively mentioned or indicated in the specification of this application, and any or all combinations of any two or more of the said parts, elements, or features.

[0125] Many modifications to the construction of the invention, as well as a variety of widely different embodiments and applications, will become 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 are not intended to be limiting in any sense. When specific integers having known equivalents in the field of this invention are mentioned herein, these known equivalents are considered to be incorporated herein as if set forth separately. Attached Figure Description

[0126] Figure 1A The flow therapy device is illustrated in diagram form.

[0127] Figure 1B A sensing circuit board is shown, which includes a flow sensor that can be used in a flow therapy device.

[0128] Figures 1C to 1D A schematic diagram of various ultrasonic transducer configurations for sensor systems using cross-flow beams is shown.

[0129] Figures 1E to 1F A schematic diagram of various ultrasonic transducer configurations for sensor systems using downstream beams is shown.

[0130] Figure 2 This is a schematic diagram of a closed-loop control system.

[0131] Figure 3 This is a first bottom perspective view of the main housing of the flow therapy device, showing the recesses within the housing for the motor and / or sensor module subassemblies.

[0132] Figure 4 This is a second bottom perspective view of the main housing of the flow therapy device, showing recesses for motor and / or sensor module subassemblies.

[0133] Figure 5 It is a perspective view of the motor and / or sensor subassemblies on the bottom side of the main housing of the flow therapy device, as well as the fixed bend.

[0134] Figure 6 This is an exploded perspective view of the components of the motor and / or sensor subassembly, with arrows schematically showing the gas flow path through the subassembly.

[0135] Figure 7 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.

[0136] Figure 8This is a rear perspective view of the flow therapy device, cut open near the rear edge of the device, showing the arrangement of this portion of the main housing that provides recesses for receiving motor and / or sensor subassemblies.

[0137] Figure 9 This is a frontal 3D view of the flow therapy device.

[0138] Figure 10 This is a frontal 3D view of the flow therapy device.

[0139] Figure 11 This is a partial sectional perspective view of the valve module and filter module from the left front.

[0140] Figure 12 This is a schematic diagram of gas flow paths used in filter modules and valve modules, where solid arrows represent the flow of oxygen (or another gas), and dashed arrows represent the flow of ambient air.

[0141] Figure 13 This is a cross-sectional view showing the gas flow path through the filter module and valve module.

[0142] Figure 14 This is a top-down perspective view of the rear of the first configuration valve module.

[0143] Figure 15 It is a rear-view perspective view showing the gas flow path through the first configuration valve module, where solid arrows indicate the flow of oxygen (or another gas) and dashed arrows indicate the flow of ambient air.

[0144] Figure 16 This is a cross-sectional view through the first configuration valve module.

[0145] Figure 17 It is a cross-sectional view showing the connection of the valve and valve manifold of the first configuration valve module, and the gas flow path through the valve and valve manifold.

[0146] Figure 18 This is an example of a graph illustrating the relationship between valve parameters.

[0147] Figure 19 An example flowchart illustrating the valve regulation process is provided.

[0148] Figure 20 An example flowchart illustrating the process of updating the valve model is provided.

[0149] Figure 21 An example graph showing the measured flow rate during respiration.

[0150] Figure 22 An example chart is shown, which illustrates sample results of oxygen content analysis in the breathing circuit.

[0151] Figure 23 An example of a control scheme for oxygen-saving mode is shown.

[0152] Figure 24 An example flowchart is shown for implementing an oxygen-saving mode during treatment.

[0153] Figure 25 An example flowchart is shown for the process of determining whether to use oxygen-saving mode during treatment. Detailed Implementation

[0154] Patients with a variety of health conditions and illnesses 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 illnesses can also benefit from oxygen therapy. A common approach to addressing these issues is to supply 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 range of SpO2 responses for each patient. 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 accurate and consistent SpO2 is a critical factor in the treatment of patients experiencing 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.

[0155] 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 fraction of 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.

[0156] One problem with the current method is the difficulty in manually maintaining the target FdO2. Additionally, clinicians cannot constantly adjust the valve to cope with fluctuations in flow rate, such as during a patient's breathing.

[0157] This disclosure provides an FdO2 control system that allows for automatic valve control, ensuring a consistent target FdO2 even when the total flow rate fluctuates (e.g., during a single breath). The system also allows users to more easily set the target FdO2 and maintain it despite flow rate variations without requiring further user input. This FdO2 control system can also be used to more effectively execute closed-loop SpO2 control algorithms.

[0158] This disclosure provides a control system for a flow therapy device. The control system can be configured to ensure that instantaneous FdO2 is maintained at a target level at substantially all points during the treatment period. The open-loop control system uses the measured total flow rate and certain gas properties to determine the target flow rate through a supplemental gas inlet valve (e.g., an oxygen control valve). The target valve flow rate is based on the flow rate required to achieve the target FdO2 for the patient. The flow therapy device can use the target valve flow rate and certain assumed valve characteristics to set a valve current. The valve current can control the actuation of the valve, thereby controlling the gas flow rate through the auxiliary valve. The flow therapy device can adjust the assumed valve characteristics using estimates of the target valve flow rate and the actual valve flow rate.

[0159] In some configurations, flow therapy devices can use multiple controllers. A coarse-tuning controller can be used to quickly find the minimum current required to open the oxygen control valve, and then once the required minimum current is determined, control of the valve can be transferred to the main controller. The main controller can determine a measure of effective FdO2 based on the average FdO2 during a single breath.

[0160] The controller continuously determines the measurement of effective FdO2. The flow therapy device can then alternate between displaying target FdO2 and effective FdO2 based on the difference between these two values. The controller can determine whether the effective FdO2 is sufficiently close to the target FdO2. When the device is displaying effective FdO2, if the difference drops below a first threshold, the device will switch to displaying target FdO2. When the device is displaying target FdO2, if the difference exceeds a second threshold, the device will switch to displaying effective FdO2.

[0161] Flow therapy equipment

[0162] Figure 1AThe image shows a flow therapy device 10. Device 10 may include a main housing 100 containing a flow generator 11 (e.g., a blower) in the form of a motor / impeller arrangement, 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 in this article, “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 containing essentially 100% oxygen, a flow containing some combination of ambient air and oxygen, and so on.

[0163] The patient breathing tube 16 is connected at one end to the airflow 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 nose fork 18. Alternatively, the patient breathing tube 16 can be connected to a face mask, nasal mask, nasal pillow mask, endotracheal tube, tracheostomy interface, etc. 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 can 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.

[0164] Controller 13 can control flow generator 11 to generate a gas flow with a desired flow rate. Controller 13 can also control supplemental oxygen inlet to allow delivery of supplemental oxygen, humidifier 12 (if present) to humidify and / or heat the gas flow to an appropriate level, etc. The gas flow is led out 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 a desired level of treatment and / or comfort for the patient. 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. In some embodiments, administration of a gas mixture composition including supplemental oxygen and / or a therapeutic drug can be provided through the supplemental oxygen inlet. The gas mixture composition may comprise oxygen, a helium-oxygen mixture, nitrogen, nitric oxide, carbon dioxide, argon, helium, methane, sulfur hexafluoride, and combinations thereof, and / or the supplemental gas may comprise a nebulized drug.

[0165] 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 source. 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,” which are incorporated herein by reference in their entirety. The following section discusses… Figures 17 to 25 Let's discuss the valve module and filter in more detail.

[0166] 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 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, 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 breathed by the user (inhaled oxygen fraction (FiO2)), and thus such terms can be considered equivalent.

[0167] 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). Outputs 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 may transmit data to a remote server or enable remote control of the device 10.

[0168] After oxygen and ambient air have been mixed, oxygen levels 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.

[0169] 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, the patient sensor 26 can use a USB interface or a wireless communication protocol (e.g., near-field communication, WiFi, or...). The patient sensor 26 is connected to the flow therapy device 10. When the patient sensor 26 disconnects during operation, the flow therapy device 10 can continue operating in its previous operating state for a defined time period. After the defined time period, the 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). The patient sensor 26 can be a bedside monitoring system or other patient monitoring systems that communicate with the flow therapy device 10 via a physical or wireless interface.

[0170] Flow therapy device 10 may include a high-flow therapy device. High-flow therapy discussed herein is intended to be given its typical, general meaning as understood by those skilled in the art, and generally refers to a respiratory support system that delivers a target flow rate of humidified respiratory gas via an intentionally unsealed patient interface at a flow rate generally designed to meet or exceed the patient's inspiratory flow rate. Typical patient interfaces include, but are not limited to, nasal or tracheal patient interfaces. Typical flow rates for adults typically range from, but are not limited to, about fifteen liters per minute (LPM) to about seventy liters per minute or greater. Typical flow rates for pediatric patients (such as newborns, infants, and children) typically range from, but are not limited to, about one liter per minute per kilogram of patient weight to about three liters per minute per kilogram of patient weight or greater. High-flow therapy may also optionally include a gas mixture composition containing supplemental oxygen and / or the administration of therapeutic drugs. High-flow therapy is often referred to as nasal high-flow (NHF), humidified high-flow nasal cannula (HHFNC), high-flow nasal oxygen (HFNO), high-flow therapy (HFT), or tracheal high-flow (THF), among other common names. The flow rate used to achieve "high flow" can be any of the flow rates listed below. For example, in some configurations, for adult patients, "high flow therapy" can 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 about 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 neonatal, 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, neonatal, 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 sub-ranges listed 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% to 30%, 21% to 30%, 21% to 40%, 30% to 40%, 40% to 50%, 50% to 60%, 60% to 70%, 70% to 80%, 80% to 90%, and 90% to 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% to 30%, 21% to 30%, 21% to 40%, 30% to 40%, 40% to 50%, 50% to 60%, 60% to 70%, 70% to 80%, 80% to 90%, and 90% to 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.

[0171] High-flow therapy can be administered through the user's nostrils and / or mouth, or via a tracheostomy port. High-flow therapy delivers gas to the user at a flow rate equal to or exceeding 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 flow rate of gas. This creates a reserve of fresh gas available for each breath while minimizing rebreathing of nitrogen and carbon dioxide. Additionally, meeting inspiratory needs and flushing the airway are important when attempting to control a patient's FdO2. High-flow therapy can be delivered using unsealed patient interfaces, such as nasal cannulas. Nasal cannulas 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.

[0172] 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 flow source (such as from flow generator 11) that does not completely obstruct the patient's airway. An unsealed pneumatic link may obstruct the patient's airway by less than about 95%. An unsealed pneumatic link may obstruct the patient's airway by less than about 90%. An unsealed pneumatic link may obstruct the patient's airway by between about 40% and about 80%. The airway may include one or more of the patient's nostrils or mouth. For nasal intubation, the airway passes through the nostrils.

[0173] 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 can enter the flow generator or blower 11. The valve controls the oxygen flow into the flow generator or blower 11. This valve can be of any type, including proportional valves or two-position valves.

[0174] 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, greater than about 4,000 RPM and less than about 19,000 RPM, or any of the above values. Operating the blower mixes the gas entering the blower through these inlet ports. Using a blower as a mixer reduces the pressure drop that occurs in systems with separate mixers (such as static mixers including baffles), since mixing requires energy. Having a static mixer also increases the volume of the gas flow path between the valve and the gas composition sensor, which can further increase the time delay between a change in valve current and the measurement of the corresponding change in oxygen concentration.

[0175] Based on user input and the treatment provided by the specific device, the controller can determine the target output parameters of the blower. The controller can receive the measured values ​​of the target output parameters, and based on the difference between the determined flow rate and the measured flow rate, the controller can adjust the speed of the blower.

[0176] The target output parameter can be flow rate. The target flow rate can be a constant value (e.g., nasal flow rate). The target flow rate can also be a fluctuating value. In some configurations, the controller can control the blower motor speed based on the target flow rate and additionally increase or decrease the motor speed based on the patient's respiratory cycle. The target flow rate does not necessarily change, but the controller causes the motor speed to fluctuate to add oscillations to the instantaneous flow rate, thus synchronizing the flow rate with the patient's breathing. Such a system is described in International Application No. PCT / NZ2017 / 050063, filed May 17, 2017, entitled "Flow Path Sensing for Flow Therapy Apparatus".

[0177] The target output parameter can alternatively be pressure. The target pressure can be a constant value (e.g., CPAP). Alternatively, the target flow rate can be a value that potentially fluctuates with respiration (e.g., bilevel NIV). In both cases, the total flow rate cannot be constant.

[0178] Additional References Figure 1B The 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 in a sensor chamber such that it is at least partially immersed in the gas flow. The gas flow can exit the blower 11 through a duct and enter 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 gas properties within the flow. After passing through the flow path in the sensor chamber, the gas can exit and reach the humidifier 12 described above.

[0179] 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 a 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 the gas flow rate by being supplied with a constant power, or by being maintained at a constant sensor temperature, or by maintaining a constant temperature difference between the sensor and the gas flow.

[0180] 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.

[0181] Positioning one or more of the thermistors 2205 and / or the thermistor flow sensor 2206 downstream of the combined blower and mixer allows the heat supplied from the blower to the gas flow to be taken into account. Furthermore, immersing a temperature-based flow sensor in the flow path can improve measurement accuracy because a 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.

[0182] Sensing circuit board 2200 may include an ultrasonic transducer, transceiver, or sensor to measure the gas properties of a gas flow, such as the 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 referred to 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.

[0183] 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 large gas stream composed of atmospheric air supplemented 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 reinforcing gases (including nitrogen (N2) and carbon dioxide (CO2)) already mixed with 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.

[0184] 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.

[0185] The distance between the ultrasonic transducers 2204 on opposite ends of the sensing circuit board 2200 affects the measurement resolution. Increasing the distance between the individual 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 that with a shorter length. Therefore, the overall uncertainty of the measurement result 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, increasing the distance results in a weaker signal.

[0186] 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 over 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.

[0187] Positioning the sensor within the flow path or module, rather than outside of it, 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 measurements and calculations to account for the effect of gas velocity, making it possible to remove the influence of gas velocity from the sensor measurements.

[0188] 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, a large 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, the ratio of two known gases can be derived using measurements of the velocity of sound across the sensing channel, by referencing empirical relationships, standard algorithms, or data stored in lookup tables, as is known in the field of binary gas analysis using ultrasound. 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 within a narrow temperature band to allow the use of the estimated temperature of the gas flow in the beam path.

[0189] 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 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.

[0190] 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.

[0191] 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 passing through an airflow by emitting and receiving ultrasonic beams or pulses. Similar reference numerals denote similar parts.

[0192] refer to Figure 1C The 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, with the gas flow path direction 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 emitted from the transmitter to the receiver transducer across the gas flow path. 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 emit transverse pulses substantially perpendicular to the gas flow path direction.

[0193] refer to Figure 1DAn alternative transducer configuration 2320 is shown, in which a pair of transducers 2322, 2324 are provided opposite each other on opposite sides of the sensing channel, but in which 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.

[0194] refer to Figure 1E An alternative transducer configuration 2360 is shown, in which a pair of transducers 2362, 2364 are located at opposite ends of 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, the beam path being substantially aligned with or parallel to the gas flow path axis 2308 in 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. For 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.

[0195] refer to Figure 1F This demonstrates an 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 opposite to 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 obtained or determined by processing the transmitted and received acoustic pulses.

[0196] In some configurations, such as those described in International Application No. PCT / NZ2017 / 050119, filed September 13, 2017, entitled "Thermistor Flow Sensor Having Multiple Temperature Points," flow therapy devices can use flow beads to measure the total flow rate of a gas. Flow beads can offer the advantage of providing more accurate flow measurements, but they are slower to respond to sudden changes in flow (such as high-frequency oscillations). Ultrasonic transducers can measure sudden changes in flow, but the overall measurement may be less accurate. In some configurations, the controller can combine inputs from the flow bead and the ultrasonic transducer to produce a final measurement of the total flow rate, allowing for both accurate flow measurement and detection of sudden changes in flow.

[0197] Some 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. Examples of configurations of flow therapy devices that can be used with various aspects of this disclosure are discussed in further detail below.

[0198] Closed-loop control

[0199] 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. This 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.

[0200] The controller 13 may receive multiple inputs from a user, which 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. These 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 an acceptable range of 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 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.

[0201] 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 SpO2 median.

[0202] 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) breathed by the patient, and thus such terms can be considered equivalent. Each range limit 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 certain set amount of the selected FdO2. The selected FdO2 can be used 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 limit of each range.

[0203] refer to Figure 2 A schematic diagram of a closed-loop control system 1000 is shown. 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 an acceptable range. This value(s) 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.

[0204] 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.

[0205] FdO2 control system

[0206] Refer again Figure 1A The controller 13 can be programmed or configured to perform an FdO2 control system for controlling the operation of the flow therapy device.

[0207] An FdO2 control system can be configured to ensure that instantaneous FdO2 remains at the target level at all points during the treatment period. The controller can measure FdO2, compare it to the target FdO2, and then adjust the oxygen inlet valve accordingly. However, when the FdO2 sensor is located at a non-negligible distance from the valve, there is a time delay between the time the valve is adjusted and the time the corresponding change in FdO2 is measured. The controller can adjust the valve after this time delay. However, if the flow rate fluctuates, the controller may be able to achieve the target FdO2 on an average basis, but not on a continuous and substantially instantaneous basis. To maintain FdO2 at the target level on a continuous and substantially instantaneous basis without moving the FdO2 sensor closer to the valve, the FdO2 controller can incorporate the measurement of the total flow rate into the valve control.

[0208] The process of regulating valve flow

[0209] For further reference Figure 18 and Figure 19 This demonstrates the process of adjusting the flow rate of the oxygen inlet valve. The main controller can first determine the valve flow rate required to achieve the target FdO2. This can be based on the target oxygen concentration, the oxygen concentration of the oxygen source, the oxygen concentration of the ambient air, and the current flow rate.

[0210] Target oxygen concentration (F 目标 The oxygen concentration in ambient air (F) can be set by the user or through the closed-loop SpO2 control algorithm described herein. 空气 The oxygen concentration (F) of the oxygen source can be assumed to be constant. Typically, the oxygen concentration of the oxygen source (F...) 源 The oxygen concentration (Q) is a constant parameter. In some cases, the oxygen concentration may be adjustable by the user. The current flow rate (Q) can be measured by one or more flow sensors.

[0211]

[0212] In one configuration, as the target FdO2 and flow rate change, the above-mentioned flow rate for the target valve ( The equation can be continuously updated.

[0213] Once the target valve flow rate is determined, the controller can determine the valve current required to actuate the valve to achieve the target valve flow rate, which can be determined by the valve model.

[0214] A valve model can use two or more parameters to determine the valve current. The first parameter can be the valve gain (I0).增益 The valve gain defines the linear component of the relationship between current change and flow rate change. In some configurations, the valve gain value can be a preset constant. Alternatively, the valve gain can be determined based on the pressure of the oxygen source. The oxygen source pressure can refer to the pressure upstream of the flow control valve, which may be set by a pressure regulator on the oxygen supply source. The oxygen source pressure can be measured by a pressure sensor upstream of the oxygen valve.

[0215] The second parameter can be the deviation of the current required to open the valve (I). 偏离 If the current deviates below this value, no flow will pass through the valve. The current deviation can be at a minimum value (I...). 偏离最小 ) and maximum value (I 偏离最大 The current deviation varies within a certain range. The current deviation can be initially estimated by a coarse-tuning controller and then adjusted over time using a main controller. In some embodiments, a single controller can estimate and adjust this value.

[0216]

[0217] The controller can then control the valve current (I) 阀 The target valve flow rate is set to a defined value. The process of determining the target valve flow rate and then updating the valve current can run continuously. For example, the process can run at a rate of 20 Hz.

[0218] coarse adjustment controller

[0219] When the valve is first activated (e.g., the target FdO2 increases from 21%), the coarse-tuning controller can initially determine the current deviation required to open the valve. As previously described, due to the distance between the valve and the gas composition sensor, there is a time delay between the time it takes to adjust the valve position and the time it takes to measure the corresponding change in FdO2. Therefore, there is a risk that increasing the current too quickly when the current deviation is determined may cause the controller to exceed the target FdO2. On the other hand, increasing the current too slowly may result in a further delay before the device can begin supplying the patient with the target FdO2 level.

[0220] Initially, the estimated current deviation can be set to the minimum expected value ( (For example, see) Figure 18 The valve current can then be set using a valve model based on the target valve flow rate. The main controller can continuously update the estimate of the current deviation. However, as described above, when the valve is closed, the main controller may detect the current deviation too slowly, resulting in a prolonged period without supplemental oxygen being supplied.

[0221] The coarse-tuning controller iteratively increases the estimated current deviation until airflow through the valve is detected. The increment at each iteration can be calculated in at least two ways. In some configurations, the larger of the two calculated increments can then be applied.

[0222] This can be achieved by increasing the current deviation by an exponentially increasing amount (ΔI) at each time step. 指数 This can be used to adjust the current deviation. Alternatively, the current deviation can be adjusted by increasing it by a minimum amount (ΔI) at each time step. 最小 This is used to adjust the current deviation. The minimum amount can be proportional to a defined target valve flow rate. A higher target valve flow rate may mean that a larger change can be made to the current deviation estimate without the risk of exceeding the target FdO2.

[0223] In each iteration of the coarse-tuning controller, the controller can increase the current deviation from the estimated value by the larger of the two values ​​mentioned above. In some configurations, the controller can increase the valve by ΔI. 最小 And begin, and then once ΔI 指数 >ΔI 最小 Switch to using ΔI 指数 .

[0224]

[0225] Where Δt is the time step of the controller, and ΔI 增加 It is ΔI 指数 The score increases.

[0226] When the target FdO2 changes for the first time, or when the target FdO2 changes from an environmental value to an increasing value (e.g., FiO2), 目标 =21% → FiO2 目标 The coarse adjustment controller can be activated at any time (>21%). It can also be activated when the user enters closed-loop SpO2 control. The current deviation (I) determined during the treatment period... 偏离 The estimated value of ) can be stored by the coarse-tuning controller so that the current deviation is not reset to the minimum current deviation after each activation.

[0227] Once gas flow from the valve is detected, the flow therapy device can switch from using a coarse-tuning controller to using a main controller. The gas flow from the valve can be determined by measuring FdO2 using a gas composition sensor. Once the measured FdO2 exceeds a certain threshold amount at the ambient level, it can be determined that the valve is open. This threshold amount can be based on sensor error (e.g., for a gas composition sensor with up to 3% error in the measured FdO2 value, the valve is determined to be open when FdO2 exceeds 24%).

[0228] Update valve model

[0229] In order to maintain FdO2 at the target level, regarding Figure 19 The described process depends on the accuracy of the valve model. To improve this accuracy, the main controller can continuously evaluate the model's accuracy and then adjust the current deviation (I) accordingly. 偏离 ).about Figure 20 The process for updating the valve model is described. This process can be performed at a rate higher than the set valve current (I0). 阀 The process is performed at a slower rate. For example, in some configurations, the current deviation can be adjusted at a rate of 3 Hz. The valve model can be updated at different rates depending on various settings or parameters (e.g., the expected range of respiratory rates, the expected amplitude of flow oscillations, and / or other settings or parameters).

[0230] Exponential filtering

[0231] To adjust for current deviation, the controller can compare the average target valve flow rate with an estimate of the average actual valve flow rate (the average of these two values ​​is the average within one breath). To obtain these averages, a time constant (τ) can be used. 过滤 The exponential filter filters several parameters over time. τ can be chosen. 过滤 This filters out fluctuations in the measured flow rate during a single breath of the patient. In each iteration of the main controller, the filtered values ​​of the following parameters can be updated:

[0232]

[0233] This instruction manual uses long notes throughout to indicate parameters that represent the average value of a patient's breath.

[0234] Average target valve flow

[0235] After updating the above filtered values, the main controller can calculate the estimated values ​​of the average target valve flow and the average actual valve flow.

[0236]

[0237] The equation used to determine the average target valve flow rate is similar to the equation used to determine the instantaneous valve flow rate, the only difference being that some values ​​are replaced by a filtered form with the same parameters.

[0238] Average valve flow

[0239] The average valve flow rate can be estimated using a model. An average flow rate model estimates the flow rate through the valve. This model can account for the amount of time it takes for oxygen to mix with the surrounding air and reach the sensor. In some configurations, this model can be a physically derived differential equation, such as a first-order model, the advection-diffusion equation, or the Navier-Stokes equations. This model can be obtained numerically using machine learning algorithms such as neural networks. In one configuration, the average valve flow rate ( It can be calculated using the following equation.

[0240]

[0241] Where F 测得 The oxygen fraction, F, is measured by a gas composition sensor. 控制 It is the oxygen fraction that the measured oxygen fraction tends to and will be affected by the current valve position and current flow rate, and V is the effective volume between the valve outlet and the gas composition sensor. Using F... 控制 Replace F in the first equation 测得 Because the time for adjusting the valve position coincides with the time the gas composition sensor detects F 测得 There is a time delay between the corresponding changes. When estimating the valve flow rate (Q) 阀 When ), F can be used. 控制 Replace F 测得 In order to take into account the changes in valve current and F 测得 The delay between corresponding changes. This can be calculated using the derivative term in the second equation. Therefore, F 控制 It can be used to predict F 测得 How will it function? As can be seen from the second equation, if the gas composition sensor is very close to the valve outlet, V will approach zero, and F... 控制 Will be basically with F 测得 same.

[0242] and The difference between them can then be input into the controller, which can then output a response to I. 偏离 The change in the estimated value. If and If they are very similar, it means that I 偏离 The estimate is close to correct, so only small changes are made. Conversely, if and Significantly different indicates that I 偏离 They are further from the correct value, and therefore make greater changes.

[0243] The coefficients used by the controller can be inversely proportional to the time constant used by the exponential filter.

[0244] Consider different treatments

[0245] The FdO2 controller can modify the control of the flow therapy device based on the therapy delivered by the specific device. In one configuration, the time constant can be set based on the therapy and for exponential filtering, which in turn sets the coefficients of the controller described herein.

[0246] The time constant used for each treatment can be set based on the typical fluctuations in the flow rate used for that treatment. Treatments with more consistent flow rates can have smaller time constants, allowing older data to decay more quickly. This, in turn, can result in larger controller coefficients, making I... 偏离 The value is adjusted in larger increments. When the total flow is more consistent, current deviations can be adjusted more quickly.

[0247] Conversely, treatments with less consistent flow rates can have smaller time constants, causing older data to decay more slowly. This, in turn, can lead to smaller coefficients in the PI controller, resulting in I... 偏离 The value is adjusted in smaller increments. When the total flow is not quite consistent, the current deviation can be adjusted more slowly.

[0248] Furthermore, the filter time constant (and thus these coefficients) can be adjusted based on the set flow rate for a specific treatment. Generally, a larger flow rate will result in a smaller filter time constant because the resulting flow rate will be more consistent, and the time delay between the valve and the gas composition sensor will be smaller.

[0249] Target oxygen alarm

[0250] In addition to controlling the valves to achieve the target FdO2, the main controller can continuously evaluate whether the target FdO2 can be achieved. The main controller can set an accuracy threshold for the FdO2 algorithm. This accuracy threshold can increase with the target FdO2 value.

[0251] An alarm can be generated if oxygen levels are determined to be too high. In some configurations, an alarm is generated if two of the following criteria are met consecutively for at least a defined time period (e.g., 8 seconds or longer): (i) the measured FdO2 exceeds the target FdO2 by a greater amount than an accuracy threshold; and (ii) the estimated current deviates from its minimum expected value. This time period can be any defined time period.

[0252] If the measured FdO2 then drops below the threshold within a defined time period (e.g., more than two seconds), the determination of excessive oxygen and the corresponding alarm are cleared.

[0253] If the following two indicators are met consecutively over a defined time period (e.g., 5 seconds or longer), oxygen is determined to be too low and an alarm is generated: (i) the measured FdO2 is less than the target FdO2 by an amount greater than the accuracy threshold; and (ii) the estimated current deviates from its maximum expected value.

[0254] If the measured FdO2 then exceeds a threshold for a defined time period (e.g., more than two seconds), the low oxygen level determination and corresponding alarm are cleared. The time period for each threshold that will turn the corresponding alarm on or off can be any defined time period and can be different from or the same as the other thresholds.

[0255] Used to display oxygen filter

[0256] The controller can continuously determine the effective FdO2 measurement. Effective FdO2 can be calculated by filtering the measurement of the total amount of oxygen delivered to the patient and then dividing that value by the filtered measurement of the total gas delivered to the patient.

[0257]

[0258] The controller can then alternate between displaying the target FdO2 and the effective FdO2. If the effective FdO2 is sufficiently close to the target FdO2, it is preferable to simply display the target FdO2, as this target value is satisfied within a defined threshold. Alternatively, if the effective FdO2 is significantly different from the target FdO2, the effective FdO2 is displayed instead. In this case, the target FdO2 is not within the defined threshold and may not be considered an accurate representation of the FdO2 delivered to the patient.

[0259] If the device operates in low-pressure mode (e.g., the device is configured to be supplied with oxygen via a low-pressure port), the target FdO2 can be considered to be 21%.

[0260] The controller determines whether the effective FdO2 is sufficiently close to the target FdO2 by taking the difference between these two values ​​and comparing it to a threshold. When the device is displaying effective FdO2, if the difference drops below a first threshold, the device switches to displaying the target FdO2. When the device is displaying the target FdO2, if the difference exceeds a second threshold, the device switches to displaying effective FdO2. The second threshold can be greater than the first threshold. For example, the first threshold can be 0.5%, and the second threshold can be 2.5%. The first threshold can also be the same as the second threshold. For example, both the first and second thresholds can be 2.5%.

[0261] Alternatively or concurrently, the first and / or second thresholds may be determined at least in part based on the accuracy thresholds used for high / low oxygen alarms. Using accuracy thresholds can help ensure that the flow therapy device does not generate high / low oxygen alarms while also displaying the target FdO2.

[0262] Oxygen saving process

[0263] Refer again Figure 1A The controller 13 can be programmed or configured to perform an oxygen-saving process for controlling the operation of the flow therapy device 10. The oxygen-saving process can operate in conjunction with the closed-loop and open-loop control systems disclosed herein. The oxygen-saving process can be configured to conserve oxygen while ensuring that the patient's SpO2 reaches and is consistently maintained at or near that level.

[0264] The oxygen-saving process described in this article reduces the total amount of oxygen used without reducing the effective FdO2 received by the patient during inspiration. The oxygen-saving process adjusts the oxygen flow control valve so that FdO2 is below the target FdO2 for at least a portion of the expiratory phase.

[0265] The oxygen-saving process can adjust the oxygen flow control valve to deliver an increased amount of oxygen-enriched gas above the FdO2 target at the end of expiration and / or the beginning of inspiration, so that the FdO2 delivered to the patient quickly returns to the target FdO2 level used during the inspiratory phase. The oxygen-saving process can also adjust the oxygen flow control valve downwards to allow FdO2 to fall back to the target FdO2 level.

[0266] The advantage of oxygen-saving processes is that they reduce the amount of supplemental gas (e.g., oxygen) used in flow therapy devices without significantly affecting the treatment delivered to the patient. Oxygen-saving processes can be beneficial because they allow for oxygen conservation during the expiratory phase while still providing the desired therapeutic effect during the inspiratory phase by achieving the target FdO2. This is also beneficial because it reduces the amount of oxygen diffused into the ambient environment, and the reduced amount of oxygen used lowers costs for the user. It can also reduce the frequency with which the user needs to refill or replace the oxygen source (e.g., oxygen cylinder).

[0267] Determination of respiratory time

[0268] As used in this article, "respiratory phase" can refer to a patient's complete respiratory cycle, which consists of an inspiratory phase and an expiratory phase. The inspiratory phase covers the complete inspiratory cycle, and the expiratory phase covers the complete expiratory cycle.

[0269] As used in this article, "breathing phase" can refer to the discrete time position of the inspiratory or expiratory phase.

[0270] To conserve oxygen without compromising therapeutic efficacy, an oxygen-saving process reduces the amount of oxygen delivered during exhalation while simultaneously returning the FdO2 at the patient interface to the target FdO2 level before the start of each inspiratory phase. For this purpose, controller 13 can generate a model of the patient's respiratory cycle. Controller 13 can control and / or receive signals from components of the flow therapy device 10. Controller 13 can be configured to analyze the patient's respiratory cycle and determine the patient's respiratory model. For example, the controller can generate waveforms representing the patient's respiratory phases. Controller 13 can also estimate the instantaneous oxygen fraction of the gas leaving the patient interface.

[0271] Figure 21 The waveform 2100 shows the flow rate measured during respiration in a high-flow system. In a high-flow system, the gas flow rate can be maintained at a relatively constant level. However, due to the speed of the control algorithm for the blower, slight fluctuations in flow rate (specifically, the flow rate that increases during inspiration and decreases during expiration) still occur.

[0272] Controller 13 can determine respiratory periods and / or phases by analyzing fluctuations in flow rate. Combinations of measurements can be used to determine respiratory periods and / or phases. For example, by analyzing a combination of flow rate and motor speed, an estimate of the resistance in the loop can be calculated. The resistance will fluctuate periodically with the patient's breathing. Exemplary embodiments of systems and methods for analyzing and determining a patient's respiratory rate are further described by reference in PCT / IB2018 / 059195 and PCT / NZ2017 / 050063, which are incorporated herein by reference in their entirety.

[0273] The patient's respiratory phase can be determined through frequency analysis (such as FFT) or time-domain analysis (such as zero crossing). Control of FdO2 can be accomplished based on a triggering system, wherein the controller 13 can identify one or more indicators of the transition between inspiration and expiration (and vice versa) and use these indicators to trigger regulation of FdO2.

[0274] In some embodiments, the controller 13 may wait until it is determined that the patient's respiratory cycle is consistent before starting to execute an oxygen-saving mode based on a control cycle corresponding to the patient's respiratory phase. If the patient's respiratory phase changes, the controller may adjust or interrupt the control cycle.

[0275] The controller can be configured to execute an oxygen-saving operating mode when the representation of the patient's respiratory cycle meets a certain confidence threshold, since oxygen saving depends on the accuracy of the representation of the patient's respiratory cycle. The confidence threshold is more likely to be met when the patient breathes consistently with a sufficiently high tidal volume. In cases where the patient's respiratory cycle cannot be reliably represented, the controller 13 can execute a default treatment mode instead of an oxygen-saving mode, wherein the controller is configured to meet the target FdO2 at substantially all points in the patient's respiratory cycle, as further described herein.

[0276] Advection-Diffusion Calculation

[0277] When an oxygen-saving process delivers a gas flow with relatively consistent FdO2 over time, it can be assumed that the FdO2 is consistent throughout the entire length of the breathing circuit. However, if the FdO2 fluctuates over time, the FdO2 at a particular moment may differ at different locations within the breathing circuit. In particular, the FdO2 measurements taken by the gas composition sensors in the device may not match the FdO2 at the patient interface. To ensure that the patient is being supplied with the correct FdO2, an estimate of the FdO2 at the patient interface can be calculated based on the FdO2 measured at the device over time.

[0278] Two main factors contribute to the difference between the FdO2 measured at the device and the FdO2 at the patient interface. The first factor is the time delay caused by the gas traveling between these two locations, resulting in peaks and troughs in the FdO2 value at the patient interface, which may be offset in the time domain by corresponding peaks and troughs in the FdO2 measurement at the device. The second factor is the amount of mixing that occurs as the gas travels through the circuit, resulting in a reduction in the amplitude of the oxygen concentration waveform further downstream in the breathing circuit.

[0279] Both of these factors can be considered using the advection-diffusion equation. The advection-diffusion equation includes an advection term that considers the aforementioned time delay and a diffusion term that considers the aforementioned mixing. Equation (1) is an example embodiment of the advection-diffusion equation:

[0280]

[0281] The advection-diffusion equations can be solved numerically, for example, using an upwind finite-difference scheme with Crank-Nicholson time steps. Alternatively, the advection-diffusion equations can be solved using a lower-accuracy numerical scheme of the advection equations, where the diffusion term is ignored and instead obtained from the “numerical-diffusion” produced by that scheme. This second approach may be less accurate but saves computational resources.

[0282] Figure 22Example chart 2210 is shown, illustrating example results from analysis using the methods described above for determining oxygen content in the breathing circuit. Airvo 2212 provides the oxygen percentage measured at the gas composition sensor in the breathing circuit. The end of hose 2214 provides the oxygen percentage measured at the patient interface. Advance-diffusion 2216 and Cheap-diffusion 2218 provide calculated estimates of the oxygen percentage at the patient interface. Chart 2220 shows the flow rate measured over the same time period.

[0283] Valve control

[0284] The controller 13 can use a valve control algorithm to estimate the start of the expiratory and inspiratory phases of the patient's respiratory cycle and adjust the valve before the start of these phases to deliver the desired FdO2 during each phase. Specifically, the controller 13 can estimate the transition from the inspiratory phase to the expiratory phase and adjust the valve so that the FdO2 at the patient interface begins to decrease once inspiration ends. Similarly, the controller 13 can estimate the transition from the expiratory phase to the inspiratory phase and adjust the valve so that the FdO2 at the patient interface returns to the target level before inspiration begins.

[0285] The primary task is to deliver the target FdO2 to the patient, followed by conserving as much oxygen as possible. This allows for a gradual increase and decrease in FdO2 during the expiratory phase, with the FdO2 at the patient interface at the target level at the start of the inspiratory phase and only beginning to decrease at the end of the inspiratory phase.

[0286] There is a delay between adjusting the valve and measuring the change in FdO2 at the device, and a further delay before the change occurs at the patient interface. The controller can compensate for this delay by predicting the onset of expiration and adjusting the valve accordingly. In one embodiment, the onset of expiration is estimated by observing the beginning of an expiratory phase, and the onset of the next expiratory phase is then predicted by using an estimate of the patient's respiratory rate.

[0287] Based on the current flow rate, the controller can calculate the travel time of the gas between the valve and the patient interface. The controller can use this travel time to determine when to reduce FdO2 after a respiratory cycle has elapsed. For example, in one instance, if the patient's respiratory rate is 20 breaths per minute, then a respiratory cycle would be 3 seconds. If the travel time is 0.5 seconds, the controller could close the valve 2.5 seconds after the start of the expiratory phase to begin reducing FdO2 at the end of the upcoming inspiratory phase.

[0288] Increasing FdO2 presents a slightly more complex challenge because the controller must ensure that the FdO2 at the patient interface is at or near the target level at the start of the inspiratory phase. To do this, the controller determines a cutoff time for the FdO2 at the patient interface to return to the target level after the start of expiration. This cutoff time can be set to 1 to 1.5 respiratory cycles after the start of expiration minus the travel time. Setting the cutoff time closer to 1.5 respiratory cycles minus the travel time increases the amount of oxygen saved, but also increases the chance that the FdO2 at the patient interface may not be at the target level in time for the start of inspiration. If the controller determines that the target FdO2 is being delivered to the patient interface before the start of inspiration, the cutoff time can initially be set to a more economical value (e.g., closer to 1 respiratory cycle minus the travel time) and then moved closer to its upper limit. In practice, the cutoff time can be approximately 1.4 respiratory cycles minus the travel time.

[0289] To ensure the target FdO2 threshold is met, the controller can adjust the valve to deliver the target FdO2 to the patient interface before a cutoff time. Due to oxygen diffusion within the system, even with a step change in the valve control signal, FdO2 will gradually increase over a period of time. Thus, the controller can compensate for diffusion by adjusting the valve at a predetermined time, based on the calculated time required for FdO2 at the patient interface to gradually increase to the target FdO2 threshold. This period before the cutoff time can be referred to as the boost period.

[0290] If the FdO2 ramp rises more rapidly, the amount of oxygen saved can be greater because this allows oxygen to be reduced over a longer portion of each exhalation period. By setting a higher target oxygen flow rate for the valve during the ramp-up phase, FdO2 can ramp up more quickly. This increased target oxygen flow rate may exceed the oxygen flow rate used to achieve the target FdO2 at the target total flow rate.

[0291] refer to Figure 23 An example of a control scheme for an oxygen-saving mode is shown. In the illustrated embodiment, the controller can calculate three target levels for operation during oxygen-saving mode. The first level 2330 is a target FdO2 for the patient. The target FdO2 for the patient can be determined for the patient using the procedures described herein (e.g., open-loop and / or closed-loop control), or by the user. The second level 2340 is lower than the first level. The second level 2340 may be referred to as a low level or low period. Preferably, the valve is fully closed to conserve oxygen. The third level 2350 is higher than the first level. The third level may be referred to as an increased level or increased period.

[0292] The boost level can be an increase in the target oxygen flow rate, which is a multiple of the target FdO2 level of 2330. The target oxygen flow rate can be the oxygen flow rate used to achieve the target FdO2 level when the oxygen-saving mode is not running. In the example shown, the target oxygen flow rate is doubled during the boost period. For example, if the target FdO2 level 2330 is 40%, then the FdO2 at boost level 2350 will be 59%. The increase in the target oxygen flow rate can be any value up to the system's maximum oxygen flow rate, because increasing the oxygen flow rate beyond this value will not increase FdO2. For example, if the target FdO2 level 2330 is 80%, then the FdO2 at boost level 2350 can be 100% (or lower if the O2 concentration of the O2 source is less than 100%).

[0293] Using a multiplier during boost periods to increase oxygen levels instead of always supplying maximum oxygen can help reduce the risk of exceeding the target and allows for additional flow rate adjustments if inhalation begins earlier than expected.

[0294] The boost period 2350 can be extended until the deadline, after which FdO2 can return to the target level 2330. The start of the boost period 2350 can be determined based on the calculated length of the boost period. The calculated length of the boost period can depend on a number of factors. In some embodiments, the length of the period is proportional to:

[0295] Oxygen shut-off duration (low period 2340);

[0296] The difference between the oxygen flow rate of 2330 at the first level and the oxygen flow rate of 2340 at the second level; and

[0297] The volume of the breathing circuit between the inlet and the patient interface.

[0298] The length of the boost period 2350 can be inversely proportional to the following: the difference between the oxygen flow rate at the first level 2330 and the oxygen flow rate at the third level 2350, and the target total flow rate.

[0299] Based on the potential for further estimated diffusion, the duration of the boost period 2350 can be slightly adjusted. This estimate can be based on the total flow.

[0300] exist Figure 23In Figure 2320 shown, the controller target is the FdO2 target set by the control algorithm, where the oxygen valve is completely closed during the low period 2340, and the FdO2 in the boost period 2350 is twice the FdO2 of the first level 2330. AirvoRawMeasured is the signal from the gas composition sensor, and EndOfTube is the estimated FdO2 calculated using the advection-diffusion equation. Respiratory FiO2 is the effective FdO2, calculated by taking the total amount of oxygen delivered during the inspiratory period and dividing it by the total amount of gas delivered during the same period. Figure 2310 shows the flow rates measured for the same time period.

[0301] Figure 23 The example in the text refers to a patient with a respiratory rate of 20 BPM and a target flow rate of 40 LPM. The effective FdO2 is roughly at the target level, and the oxygen used has been reduced by about 15%.

[0302] In an alternative embodiment, the target oxygen flow rate for the boost phase can be set to the same value as the target total flow rate, thereby achieving maximum FdO2 during the boost phase. This allows for the most abrupt possible change in FdO2 at the patient interface, but also increases the risk of exceeding the target FdO2.

[0303] Determine the applicability of oxygen conservation

[0304] Controller 13 can determine whether conditions are suitable for implementing an oxygen-saving operating mode. The controller can determine whether to implement the oxygen-saving mode based on one or more factors. Furthermore, the controller can continuously monitor each of these factors during operation to determine whether to enter or exit the oxygen-saving mode.

[0305] One factor is the accuracy of the patient's respiratory cycle modeling. This is because oxygen-saving modes rely on accurate analysis of the patient's respiratory cycle. The controller can execute oxygen-saving mode only if the analysis results meet the defined confidence thresholds used for modeling the patient's respiratory cycle. The controller can calculate a confidence metric associated with the model of the patient's respiratory cycle and compare the calculated confidence metric with the confidence thresholds.

[0306] Another factor is the amount of oxygen saved. While the oxygen-saving mode conserves oxygen during the low-period period, it also uses an increased amount of oxygen during the high-period period. The controller can compare these two values ​​and can execute the oxygen-saving mode only if the predicted oxygen savings during the low-period period are greater than the increase in oxygen usage during the high-period period. Alternatively, the controller can execute the oxygen-saving mode only if the total reduction in oxygen used meets a defined threshold.

[0307] Another factor can be based on the analysis of the target flow rate and respiratory rate. From the advection term of the advection-diffusion equation, it can be seen that the travel time between the device and the patient interface increases when using a lower flow rate. Therefore, controlling FdO2 becomes easier at higher flow rates. Additionally, as the patient's respiratory rate increases, the length of each respiratory cycle becomes shorter, and consequently, the controller must switch between control periods more frequently, and the prediction of inspiratory and expiratory transitions must be more accurate.

[0308] Oxygen conservation becomes increasingly difficult for two main reasons, especially when low flow rates are combined with high respiratory rates. First, the travel time becomes considerably longer relative to the length of the respiratory cycle, necessitating further valve changes before the transition between inspiration and expiration, thus introducing a greater likelihood of error. Second, while frequent FdO2 transitions can be achieved through valves, the low gas flow rate allows for increased mixing before reaching the patient interface, resulting in smaller FdO2 oscillations. If the controller aims to maintain the target FdO2 during the inspiratory phase, the amount of oxygen that can be conserved becomes considerably smaller.

[0309] The controller can additionally determine whether to implement an oxygen-saving mode based on the relationship between the target flow rate and the patient's respiratory rate. For example, the implementation of an oxygen-saving mode may depend on the ratio between flow rate and respiratory rate exceeding a threshold.

[0310] Implementation of oxygen-saving mode

[0311] Figure 24 An embodiment of a flowchart illustrating the execution of an oxygen-saving mode during treatment is shown. Process 2400 can be implemented by a controller or control system configured to control the operation of the flow therapy device. For example, process 2400 can be implemented wholly or partially by the controller 13 of the flow therapy device 10.

[0312] At box 2410, the controller can analyze the patient's respiratory cycle. Controller 13 can be configured to determine the patient's respiratory model based on this analysis. For example, the controller can generate waveforms representing the patient's respiratory periods. The respiratory period and / or phase can be determined using combinations of measurements. The patient's respiratory cycle can be determined through frequency analysis (such as FFT) or time-domain analysis (such as zero-crossing).

[0313] At box 2420, the controller determines the target FdO2 level for the treatment period. This may be referred to as the first level. The target FdO2 level for the patient can be determined for the patient using various procedures described herein (such as open-loop and / or closed-loop control), or by the user. The target FdO2 level may represent the flow rate of the supplementary gas (e.g., oxygen) required to achieve the target gas composition based on the total gas flow rate.

[0314] At box 2430, the controller determines a low FdO2 level. The low FdO2 level is a secondary level and is below the target FdO2 level. The low FdO2 level can be the ambient oxygen level. A low FdO2 level can be achieved by completely cutting off the flow of the makeup gas (e.g., oxygen). For example, controller 13 can be configured to completely close the valve.

[0315] At box 2440, the controller determines to increase the FdO2 level. The increased FdO2 level is the third level and is above the target FdO2 level. The increase level can be an increase in the target oxygen flow rate, a multiple of the target FdO2. For example, the increase level could be twice the target FdO2 level. The increase in the target oxygen flow rate can be any value up to the system's maximum oxygen flow rate. Using a multiplication factor to increase oxygen during the increase period, rather than always supplying maximum oxygen, can help reduce the risk of exceeding the target and allows for additional flow rate adjustments if inhalation begins earlier than expected.

[0316] At box 2450, the controller determines the timing of each level during a respiratory phase. The controller can determine the duration and timing of the target FdO2 phase, the low FdO2 phase, and the FdO2-boosting phase. Each phase can extend a portion of the respiratory phase.

[0317] At box 2460, the controller controls valve operation based on the determined level and timing characteristics of the patient's respiratory cycle, and characteristics determined for each level. The controller 13 can adjust the valve during operation based on determined time periods, such that the desired FdO2 is delivered during each time period. Specifically, the controller 13 can estimate the transition from the inspiratory phase to the expiratory phase and adjust the valve such that FdO2 decreases from the target FdO2 level to a low FdO2 level once inspiration ends. The controller 13 can determine the transition from a low FdO2 level to an increased FdO2 level and can adjust the valve such that FdO2 moves from a low FdO2 level to an increased FdO2 level. The controller 13 can estimate the transition from the expiratory phase to the inspiratory phase and can adjust the valve such that FdO2 returns from the increased FdO2 level to the target FdO2 level before inspiration begins.

[0318] In addition, the controller can continuously monitor and adjust various levels and timing characteristics based on ongoing analysis of the patient's respiratory cycle. The controller can determine whether conditions are suitable for continuing oxygen-saving mode. Regarding... Figure 25 The process described herein is used to further describe embodiments of the factors used to determine whether to switch between operating modes.

[0319] The process of selecting an oxygen-saving mode

[0320] Figure 25 An embodiment of a flowchart illustrating the process for determining whether to use an oxygen-saving mode during treatment is shown. Process 2500 can be implemented by a controller or control system configured to control the operation of the respiratory equipment. For example, process 2500 can be implemented wholly or partially by the controller 13 of the respiratory equipment 10.

[0321] At box 2510, the controller can analyze the patient's respiratory cycle. An oxygen-saving process can be configured to execute when the representation of the patient's respiratory cycle meets a certain confidence threshold. The oxygen-saving mode depends on the accurate analysis of the patient's respiratory cycle. The controller can execute the oxygen-saving mode only if the analysis results meet the defined confidence threshold used for modeling the patient's respiratory cycle. The controller can calculate a confidence metric associated with the model of the patient's respiratory cycle.

[0322] At box 2520, the controller can determine whether a confidence threshold for implementing the oxygen-saving mode has been met by comparing a confidence metric with a confidence threshold. If the patient's respiratory cycle cannot be confidently characterized and the confidence threshold is not met, the oxygen-saving process can operate in standard treatment mode, and this process can proceed to box 2550. If the threshold has been met, the process proceeds to box 2530.

[0323] At box 2530, the controller can determine the operational characteristics of operating in oxygen-saving mode. These operational characteristics may include oxygen-saving characteristics. Oxygen-saving characteristics can be used to determine how much oxygen will be saved when operating in oxygen-saving mode. Oxygen-saving mode saves oxygen during low-flow periods and also uses an increased amount of oxygen during high-flow periods. The system can determine and compare these two values ​​to assess the predicted oxygen savings. Operational characteristics may include target flow rate and patient respiratory rate. Oxygen saving can become increasingly difficult, especially when low flow rate is combined with a high respiratory rate. The controller can determine the ratio between flow rate and respiratory rate.

[0324] At box 2540, the controller can determine whether the operating thresholds for implementing the oxygen-saving mode have been met. The controller can compare the oxygen-saving characteristic with the oxygen-saving threshold to determine whether the total reduction in oxygen meets the oxygen-saving threshold. Alternatively, the ratio of flow rate to breathing rate can be compared with a separate threshold. If none of these defined thresholds are met, the process proceeds to box 2550. If the thresholds are met, the process proceeds to box 2560.

[0325] At box 2550, the controller operates the system in standard mode (as described in more detail herein), where the controller is configured to meet the target FdO2 at substantially all points in the patient's respiratory cycle. At box 2510, the controller can further analyze the characteristics of the patient's respiratory cycle to determine whether to continue operating in standard mode or switch to oxygen-saving mode.

[0326] At box 2560, the controller operates in oxygen-saving mode, where the controller uses three different levels to operate the valve, such as... Figure 24 As described in more detail below. The controller can continue to analyze the characteristics of the patient's respiratory cycle at box 2510 to determine whether the controller should continue operating in oxygen-saving mode or switch to standard mode.

[0327] The analysis to determine whether to continue using or switch to oxygen-saving mode can be performed at defined intervals. For example, defined intervals can be performed at each respiratory interval, every other respiratory interval, or after a predetermined number of respiratory intervals. This analysis can be performed based on any suitable time increment (e.g., every second, every five seconds, or any defined time increment). The defined intervals can be based on the operational characteristics of the current mode and / or patient characteristics.

[0328] Motor and / or sensor module configuration

[0329] Figures 3 to 5 The configuration of the flow therapy device 10 is shown in the image. The flow therapy device includes a main housing 100. The main housing 100 has an upper main housing housing 102 and a lower main housing housing 202.

[0330] like Figure 3 and Figure 4 As shown, the lower housing 202 has a motor recess 250 for receiving a removable or non-removable motor and / or sensor module 400, which in... Figures 3 to 5 As shown and will be described in further detail below, a recess 251 is provided in the bottom wall 230 near its rear edge for receiving a removable or non-removable motor / sensor module 400. Figure 3 and Figure 5 It is shown in the figure and will be described in further detail below.

[0331] Figures 5 to 8 The motor and / or sensor module or sub-assembly 400 is shown in more detail. As discussed above, the lower housing 202 includes a recess 250 for receiving the motor and / or sensor module 400.

[0332] exist Figures 5 to 8In 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 secured in a non-removable manner.

[0333] 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.

[0334] 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.

[0335] Gas outlet 406 is in fluid communication with the outlet gas flow path and the gas inlet of sensing layer 420, which is stacked on top of the motor. This layer 420 includes a body 422 with a plurality of mounting legs 425 that can be inserted into a plurality of mounting slots (not shown) of base 403 to secure the 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.

[0336] Body 422 defines a lower portion 426 of the sensing and gas flow path. Cover layer 440 has body 442 that defines an 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.

[0337] like Figure 6 and Figure 7As shown, the gas flow path includes elongated straight gas flow portions 428 and 448. Inlets are in fluid communication with tangential inlet portions 430 and 450 of the gas flow path, located at or near the inlet ends of the elongated straight gas flow portions 428 and 448. Recesses 433, 453 and 434, 454 may be provided at opposite ends of the elongated straight gas flow portions.

[0338] The gas outlet port 452 extends vertically through the body 442 of the cover layer 440 and is located at or near the opposite outlet end of the straight elongated 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 the 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 equipment. The recess 250 may include spacers, such as lugs projecting downwards from the top plate 262, etc. Figure 4 As shown, an appropriate spacing is maintained for the airflow from the top plate of the gas outlet port 452 and the recess 262.

[0339] from Figure 6 As can be seen, at least a portion of the gas flow path through and out of the motor and / or sensing module 400 has a tortuous or meandering configuration. For example, the gas flow direction through the elongated portions 428, 448 is generally opposite to the gas flow direction from the gas outlet port 452 to the inlet of the gas flow channel through the bend 324.

[0340] like Figure 7 and Figure 8 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., by functioning as 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.

[0341] One or both of the electronic circuit boards 272 will be electrically connected or coupled to these sensors to process information received from the sensors and operate the device 10 based on the information received from the sensors.

[0342] 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 an alternative configuration, the module received in recess 250 may consist only of a motor and a gas flow path, but without sensors.

[0343] 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 isolating gas from electrical / electronic components will still be provided.

[0344] The flow path is compact and has fewer turns / sharp bends, which reduces flow separation and lowers flow resistance.

[0345] The arrangement of the motor and flow path provides another layer of isolation due to the wall arrangement.

[0346] The modular motor and / or sensor modules allow for the disassembly of the modules when cleaning and / or maintenance are required.

[0347] 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.

[0348] Valve module

[0349] Figures 9 to 17 A first configuration of valve module 4001 is shown. Valve module 4001 controls the flow rate of oxygen and / or other gases entering the gas flow path of device 10 and enables device 10 to regulate 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.

[0350] Valve module 4001 is vertically inserted upwards into valve module housing 306 within the lower housing 202 of the main housing. In alternative configurations, the valve module can be inserted into the housing in various 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.

[0351] 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 housing. Since the valve module 4001 is essentially housed 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.

[0352] 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.

[0353] Valve 4003 includes a cylindrical body 4005 and a valve component within the body.

[0354] For example, a flow control valve can be a solenoid valve, a motor-driven valve, or a piezoelectric valve.

[0355] 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.

[0356] Alternatively, a modulated input signal can be used to control the solenoid valve, thereby modulating the valve between the open and closed positions.

[0357] Valve 4003 can be a needle valve, piston valve, gate valve, ball valve, butterfly valve, globe valve, etc. The valve can be pressure-compensated.

[0358] 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.

[0359] In some configurations, valve 4003 is an electrically actuated proportional solenoid valve. For example, the valve may be a 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.

[0360] The valve can have a coaxial inlet-outlet configuration.

[0361] 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 (multiple) valve manifold gas outlets 4019. When the valve is "closed," it blocks the gas flow from gas inlet 4017 to (multiple) gas outlets 4019. When the valve is "open," it allows the gas flow from gas inlet 4017 to (multiple) gas outlets 4019.

[0362] The end 4018 of the valve manifold 4011 opposite to 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 orifices 4023A for receiving fasteners 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.

[0363] Valve manifold 4011 directs / disperses oxygen from the valve via a 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 close to a patient in a medical and / or home environment, it is desirable to minimize the generated noise.

[0364] Additionally or alternatively, shrouds, pipes, or channels 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.

[0365] 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.

[0366] The end of the valve manifold corresponding to 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 gas inlet 4033 of the connector can move in different ways, such as translational or pivotal movement.

[0367] 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 remains open, excess pressurized oxygen or other gas will open from the multiple ambient air inlets in valve support 4051 (e.g., Figure 15 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-limited without the need for a pressure relief valve.

[0368] 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 close 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, a suction is generated 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 the 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 past one or more temperature sensors of the device used to deliver the gas flow.

[0369] 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 device's gas outlet.

[0370] 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.

[0371] 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.

[0372] The filter module and valve module described herein can provide a variable 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, the gas can be supplied through the first sub-compartment gas inlet (e.g., Figure 13 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 wish to manually adjust the oxygen supply (i.e., via a wall-mounted supply rotor flow meter, for example).

[0373] It will be understood that the filter modules and valve modules described herein can be used separately in devices used to deliver gas streams. Alternatively, the filter and valve modules can be used together as a filter and valve assembly for improved functionality.

[0374] 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 source, i.e., such as via a wall-mounted supply rotor flow meter).

[0375] The various configurations described are merely exemplary. Any one or more features from any configuration can be used in combination with any one or more features from any other configuration.

[0376] For example, rotary connectors used in valve modules can have additional functions. In some configurations, the rotary connector can be arranged to rotate about more than one axis; and can, for example, have two adjacent rotary connection portions with rotation axes transverse to each other, such that the gas inlet of the rotary connector can rotate about these two axes. In some configurations, the rotary connector may include a ball-and-socket arrangement or similar arrangement, so that the gas inlet of the rotary connector can rotate in substantially any direction. In some configurations, the rotary connector can be arranged to provide both rotational and translational movements; such that the gas inlet of the rotary connector can rotate about one or more axes, for example, and also travel in a straight line. This may be practical for translating a gas inlet from one part of the equipment to another, such as from one side of the equipment to the other. In some configurations, the gas inlet can be arranged to perform translation rather than rotation.

[0377] 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 can alternatively be located in the rear, side, front, or top of the housing. For such variations, the air and / or oxygen inlet can also be positioned differently depending on requirements.

[0378] As another example, instead of configuring the liquid chamber and recess such that the liquid chamber is inserted into and removed from the recess from the front of the housing, it can be configured such that the liquid chamber is inserted into and removed from the recess from the side, rear, or top of the housing.

[0379] 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.

[0380] 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 can be 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.

[0381] Alternatively, filter modules and / or valve modules can be used in devices intended for different purposes. The device can be a high-flow-rate treatment device or a low-flow-rate treatment device. These features can also be incorporated into devices for providing continuous positive airway pressure (CPAP), which can deliver gas (humidified or otherwise) under positive pressure.

[0382] 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 the cavity 108 feature. 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.

[0383] The term "flow therapy device" is intended to cover all such variations.

[0384] Any prior art mentioned in this specification is not and should not be construed as an admission or in any way implying that such prior art forms part of the common knowledge in the field in any country in the world.

[0385] When directional terms such as “up,” “down,” “forward,” “backward,” “horizontal,” and “vertical” are used in this document, these terms refer to the situation when the device is in a typical position of use and are used to indicate and / or describe relative direction or orientation.

[0386] 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 a non-exclusive or exhaustive sense, that is, in the sense of “including but not limited to.”

[0387] 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.

[0388] Any prior art mentioned in this specification is not and should not be construed as an admission or in any way implying that such prior art forms part of the common knowledge in the field in any country in the world.

[0389] The disclosed devices and systems may also be broadly referred to as the parts, elements and features individually or jointly mentioned or indicated in the description of this application, in any or all combinations of two or more of the parts, elements or features.

[0390] Where the whole or its components having known equivalents have been mentioned in the foregoing description, such wholes are incorporated herein as if described separately.

[0391] 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.

[0392] It should be noted that various changes and modifications to the currently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the disclosed apparatus and system, and without diminishing its accompanying advantages. For example, 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: Ambient air inlet; The replenishment inlet is used to receive replenishment gas from the replenishment gas source. A valve, in which a minimum amount of current is required to open; A gas composition sensor, configured to measure the gas composition of a mixture of ambient air and supplementary gas; The main controller is configured to control the delivery of gas to the patient. The main controller is configured as follows: The actuation of the valve opening is adjusted by controlling the valve current; and When the target flow rate of the supplemental gas increases from zero, the coarse adjustment controller is activated; The coarse adjustment controller is configured as follows: The valve opening is actuated by controlling the valve current; Iteratively increase the current supplied to the valve; and After detecting the flow through the valve, the actuation control of the valve is switched to the main controller.

2. The breathing device as described in claim 1, wherein, The controller sets the valve current to an initial value before iteratively increasing it.

3. The breathing device as described in claim 2, wherein, The initial value corresponds to the minimum possible current required to open the valve opening.

4. The breathing device according to any one of claims 1 to 3, wherein, In each iteration of the coarse-tuning controller, the coarse-tuning controller performs a step change in the valve current.

5. The breathing device as described in claim 4, wherein, The magnitude of the step change increases with each iteration.

6. The breathing device as described in claim 4, wherein, The magnitude of the step change is at least partially based on the target FdO2.

7. The breathing device as claimed in claim 4, wherein, The magnitude of a step change is at least partially based on the total flow.

8. The breathing device according to any one of claims 1 to 3, wherein, A gas composition sensor is used to detect the flow rate through the valve.

9. The breathing device according to any one of claims 1 to 3, wherein, When the concentration of the supplemental gas exceeds the ambient level, it is determined that flow is occurring through the valve.

10. The breathing device according to any one of claims 1 to 3, wherein, When the concentration of the supplemental gas exceeds the ambient level by a amount greater than the potential sensor error, it is determined that flow is occurring through the valve.

11. The breathing device according to any one of claims 1 to 3, wherein, The supplementary gas includes concentrated oxygen.

12. The breathing device as claimed in claim 5, wherein, The magnitude of the step change is at least partially based on the target FdO2.

13. The breathing device as described in claim 5, 6, or 12, wherein, The magnitude of a step change is at least partially based on the total flow.

14. The breathing device as claimed in claim 8, wherein, When the concentration of the supplemental gas exceeds the ambient level, it is determined that flow is occurring through the valve.

15. The breathing device as claimed in claim 8, wherein, When the concentration of the supplemental gas exceeds the ambient level by a amount greater than the potential sensor error, it is determined that flow is occurring through the valve.

16. The breathing device as claimed in claim 9, wherein, When the concentration of the supplemental gas exceeds the ambient level by a amount greater than the potential sensor error, it is determined that flow is occurring through the valve.

Images