Patient connection detection in a respiratory flow therapy system

Abstract

The system and method can determine whether a patient is connected to a respiratory device (such as via a patient interface) by analyzing the flow parameter signal in the time domain. Furthermore, the process can classify the patient connection status into one of four categories: disconnected, connecting, connected, or disconnecting. The system can include non-sealing patient interfaces, such as nasal cannulas in nasal high-flow therapy, or any other patient interface. Data on the patient's use of the respiratory system can provide treatment compliance and long-term trends of usage information and / or the progress of the patient's respiratory and / or other physiological functions.

Description

[Technical Field]

[0001] The present disclosure relates to methods and systems for providing respiratory flow therapy to a patient. In particular, the present disclosure relates to detecting whether a patient is attached to a respiratory flow system. [Background technology]

[0002] Respiratory assistance apparatus are used in a variety of settings, such as hospitals, medical facilities, home care, or domestic environments, to deliver a flow of gas to a user or patient. Respiratory assistance or respiratory therapy apparatus (collectively, "respiratory apparatus" or "respiratory device") may be used to deliver supplemental oxygen or other gases along with the gas flow, and / or a humidification apparatus may be used to deliver heated and humidified gas. Respiratory apparatus may allow adjustment and control over characteristics of the gas flow, including flow rate, temperature, gas concentration, humidity, pressure, etc. Sensors, such as flow and / or pressure sensors, are used to measure the characteristics of the gas flow.

[0003] Respiratory devices can monitor and determine various parameters related to a patient's use of the device. The parameter data can inform a clinician regarding the progress of the patient's health, the use of the respiratory device, and / or the patient's respiratory function. Such data can also be used to improve the functionality of the respiratory device itself.

[0004] Inhalation and exhalation by a patient using a respiratory device can affect gas flow within the device because when a patient inhales through a patient interface, such as a mask or nasal cannula, resistance to gas flow within the patient interface decreases, and when the patient exhales, resistance to gas flow within the patient interface increases. Several parameters, such as respiratory rate, can be determined by monitoring changes in flow parameter signals due to inhalation and exhalation. Summary of the Invention [Problem to be solved by the invention]

[0005] In a sealed system, this inhalation and exhalation is relatively easy to measure. However, in a non-sealed system, such as a nasal high-flow system, patient inhalation and exhalation are more difficult to determine due to the open nature of the system. Irregularities in the signal, particularly the time-domain signal, can easily be misinterpreted as respiratory trigger events. Parameters determined from such an analysis can be misleading if the respiratory device may detect a breath in the signal when there is no breathing (e.g., because the patient is detached, not breathing through the nose, and / or for other reasons). [Means for solving the problem]

[0006] The present disclosure provides a process for detecting patient connection and disconnection from a respiratory system by performing a time domain analysis of gas flow parameters to determine a correlation value of the flow parameter data and comparing the correlation value to one or more thresholds. Additionally, the process described herein can classify patient connection status into one of four categories: detached, attaching, attached, or detaching.

[0007] The determination of patient connection status can be fed to other control functions of the respiratory device and / or other patient monitoring devices, for example, to synchronize gas delivery when the patient is connected, to suspend oxygen delivery control and / or flow and / or power control to a heating element in the device when the patient removes the patient interface, to improve the accuracy of determination of other parameters such as respiratory rate, and / or to provide treatment compliance and long-term trending of usage information and / or progress of the patient's respiratory function, etc. The processes disclosed herein can be used when the patient interface is a non-sealing device, such as a nasal cannula in nasal high-flow therapy, or any other patient interface, such as a face mask, nasal mask, nasal pillow mask (such as in continuous positive airway pressure (CPAP) therapy and / or bilevel positive airway pressure therapy), endotracheal tube, tracheostomy interface, etc.

[0008] In one configuration, a respiratory system configured to provide respiratory therapy to a patient and to provide information related to the patient's respiration may include a respiratory device having a controller, the controller may be configured to receive data of a first parameter representative of gas flow or performance of a component of the device, the first parameter being indicative of the patient's respiration, determine a correlation value of the data of the first parameter by analyzing trends in the data, and use the correlation value to determine that the patient is connected to a patient interface of the device.

[0009] In one configuration, the controller may be configured to evaluate the correlation value for a subset of the data for the first parameter.

[0010] In one configuration, the size of the subset may be selected such that frequencies within the typical breathing frequency range result in a higher correlation than other frequencies above the typical breathing frequency range.

[0011] In one configuration, the size of the subset may be selected such that the subset includes data from a predetermined time span.

[0012] In one arrangement, the correlation value may be determined by analyzing the correlation between the data of the first parameter and one or more feature vectors.

[0013] In one configuration, the controller may be configured to filter the correlation values ​​over time to provide filtered correlation values.

[0014] In one configuration, the controller can be configured to determine that the patient is connected to the patient interface if the filtered correlation value is above a first threshold.

[0015] In one configuration, the controller can be configured to determine that the patient is connected to the patient interface if the filtered correlation value is above a second threshold for a certain amount of time.

[0016] In one configuration, the first threshold may be greater than the second threshold.

[0017] In one configuration, once a connection is determined, the filtered Correlation value If V is below a third threshold, the patient can be determined to be disconnected.

[0018] In one configuration, once a connection is determined, the filtered Correlation value If V is below a fourth threshold for a certain amount of time, it can be determined that the patient is disconnected.

[0019] In one configuration, the third threshold may be less than the fourth threshold.

[0020] In one configuration, the fourth threshold may be equal to the second threshold. In one configuration, the fourth threshold may be less than the second threshold.

[0021] In one configuration, the controller can be configured to determine that the patient is connected if the patient was not already assumed to be connected and the filtered correlation value is between the first and second threshold values ​​for less than a certain amount of time.

[0022] In one configuration, once determined to be connected, the patient may be determined to be disconnected if the correlation value falls below a second threshold.

[0023] In one configuration, the controller can be configured to determine that the patient is disconnecting if the filtered correlation value is between the third and fourth thresholds for less than a certain amount of time, if the patient was not already assumed to be disconnected.

[0024] In one configuration, once disconnection is determined to be occurring, if the correlation value exceeds a fourth threshold, the patient may be determined to be connected.

[0025] In one configuration, the controller may use the determination of whether or not a patient is connected to determine whether or not to display certain parameters.

[0026] In one configuration, the controller may receive an estimate of the patient's respiratory rate and display the respiratory rate estimate if the controller determines that a patient is connected.

[0027] In one configuration, the device may be configured to synchronize the delivery of gas with the patient's breathing if the patient is determined to be connected.

[0028] In one configuration, the controller may log the time of each patient connection status.

[0029] In one configuration, the device can generate an alarm when the patient is disconnected.

[0030] In one configuration, the device is configured to generate an alert immediately after the patient is disconnected. In one example, the device is configured to generate an alert in real time when the patient is detected as being disconnected.

[0031] In one configuration, the device is configured to generate an alarm following a preset time (ie, a predetermined time) after the patient is disconnected.

[0032] In one configuration, the preset time period can be from about 10 seconds to about 10 minutes. In one example, the device is configured to generate an alarm if the device detects the patient as disconnected for the preset time period. In one example, the preset time period is at least 1 minute.

[0033] In one example, the preset time period may be from about 30 seconds to about 5 minutes.

[0034] In one example, the preset time period may be from about 1 minute to about 2 minutes. 、 Preset Time can be 2 to 3 minutes The device is configured to wait a predetermined time (i.e., a preset time) to allow the patient or medical professional to remedy the removed nasal cannula if the cannula becomes inadvertently dislodged. The device is configured to communicate an alarm if the cannula is detected as being dislodged for the preset time to alert the patient and / or medical professional that the patient is not receiving gas flow. The alarm provides a warning if the patient is not receiving treatment, thereby improving the safety of the system and reducing the likelihood that the patient will not receive treatment due to dislodgment.

[0035] In one configuration, the alarm can be output through a nurse call port.

[0036] In one configuration, the alert can be accompanied by the device providing the user with the option to check whether the patient is still connected. This option can be presented in a graphical user interface. This option can be presented as a button or window that can be selected via the user interface.

[0037] In one configuration, the option to check if the patient is still connected can be used to override the determination that the patient has been disconnected.

[0038] In one configuration, the device may pause recording of certain patient parameters only when the patient is disconnected.

[0039] In one configuration, the patient parameters may include oxygen efficiency.

[0040] In one configuration, oxygen efficiency can be based on SpO2 and FdO2.

[0041] In one configuration, the device can include a make-up gas inlet and a valve, the valve can be adjusted by the controller to regulate the flow rate of make-up gas through the make-up gas inlet. In one example, the make-up gas can be oxygen or nitrogen.

[0042] In one configuration, the controller can close the valve when the patient is disconnected, thereby reducing waste of supplemental gas when the patient is not connected, i.e., the patient is disconnected. The controller can be configured to close the valve and can be configured to reopen the valve when the patient is detected as connected.

[0043] In one configuration, the controller can control the flow generator to achieve the flow rate, and the controller can adjust the flow rate once the patient is disconnected. The flow generator can be a blower.

[0044] In one configuration, adjusting the flow rate may include reducing the flow rate.

[0045] In one configuration, adjusting the flow rate can include increasing the flow rate. For example, if the nasal cannula is partially detached, the controller can be configured to increase the flow rate to overcome the partial detachment. The increased flow rate helps to continue providing respiratory gas to the patient so that the patient can receive respiratory therapy. The respiratory therapy, in one example, can be high-flow therapy. The increased flow rate can deliver an appropriate amount of gas flow to the patient even when the patient interface is detected as partially detached and removed.

[0046] In one configuration, the increased flow rate can continue for an initial period.

[0047] In one configuration, the initial period may be from about 10 seconds to about 10 minutes.

[0048] In one configuration, the initial period may be from about 30 seconds to about 5 minutes.

[0049] In one configuration, the initial period may be from about 1 minute to about 2 minutes.

[0050] In one configuration, the controller can reduce the flow rate when it determines that the patient is still disconnected after the initial period. Reducing the flow rate after the initial period helps protect the flow generator (e.g., blower) from overworking. This can be useful if the respiratory therapy device is operating on a battery. Turning off the blower or reducing the flow rate can help conserve battery power.

[0051] In one configuration, the data for the first parameter may include an absolute value of the first parameter.In one configuration, the data for the first parameter may include a variance of the first parameter.

[0052] In one configuration, the change can be determined by subtracting a target value of the first parameter from a measured value of the first parameter. In one configuration, the change can be determined by subtracting an estimated effect of the second parameter from a measured value of the first parameter.

[0053] In one configuration, the first parameter may be a flow rate.In one configuration, the first parameter may be a pressure.

[0054] In one configuration, the second parameter may be motor speed. In one configuration, the second parameter may be pressure.

[0055] In one configuration, the system may be a non-sealed system.

[0056] In one configuration, the patient interface may include a nasal cannula or tracheostomy interface.

[0057] In one configuration, the system can be configured to provide nasal high flow therapy.

[0058] In one configuration, the system may be a closed system.

[0059] In one configuration, the system may include a patient interface, the patient interface being a face mask, a nasal mask, an endotracheal tube or a tracheostomy interface.

[0060] In one configuration, the system may include a humidifier configured to humidify the gas flow to the patient.

[0061] In one configuration, the controller is configured to reduce power to the humidifier when the patient is disconnected.

[0062] In one configuration, the controller is configured to turn off power to the humidifier when the patient is disconnected. In one configuration, the humidifier includes a heater plate and a humidification chamber. The chamber is positioned on the heater plate when in the active configuration. The controller is configured to turn off power to the heater plate when the patient is detected as disconnected. This conserves battery power when the device is operating on a battery. Turning off the power also reduces the chamber from overheating or being damaged due to prolonged heating. This also helps preserve the state of the heater plate and the chamber. Furthermore, turning off power to the heater plate reduces heating, thereby reducing the chance of increasing the enthalpy of the gas delivered to the patient, thereby reducing the amount of heat in the humidification chamber.

[0063] In one configuration, the system can include a patient breathing conduit having a heating element configured to heat the flow of gas to the patient. The heating element can be a heater wire. The heater wire can be embedded in the wall of the conduit and can be spirally wound. Alternatively, the heater wire can be positioned within the lumen of the conduit.

[0064] In one configuration, the controller is configured to reduce power to the heating element of the patient breathing conduit when the patient is disconnected. This is advantageous because it reduces the likelihood of the breathing conduit overheating or damage to the conduit from heating. Reducing or turning off power to the conduit heating element (e.g., a heater wire within the conduit) can also reduce or prevent excessive enthalpy of the gas.

[0065] In one configuration, the controller is configured to turn off power to the heating element of the patient breathing conduit when the patient is disconnected, which has similar advantages as those described above.

[0066] In one configuration, the system may include a display configured to receive from the one or more processors and display information relating to whether a patient is connected to the system.

[0067] In one configuration, a method for determining whether to disconnect and / or connect a patient to a respiratory system configured to provide respiratory therapy to a patient and also configured to provide information related to the patient's respiration includes receiving, using a controller of a respiratory device, data for a first parameter representative of gas flow or performance of a component of the device, the first parameter being indicative of the patient's respiration; determining a correlation value for the data of the first parameter by analyzing trends in the data; and using the correlation value to determine whether the patient is connected to a patient interface of the system.

[0068] In one configuration, the determining may include evaluating a correlation value for a recent subset of data for the first parameter.

[0069] In one configuration, the method may include selecting the size of the subset such that frequencies within a typical breathing frequency range result in a higher correlation than other frequencies above the typical breathing frequency range.

[0070] In one configuration, the size of the subset may be selected such that the subset includes data from a predetermined time span.

[0071] In one configuration, determining the correlation value may include analyzing the correlation between the data of the first parameter and one or more feature vectors.

[0072] In one configuration, the method may further include filtering the correlation values ​​over time to provide filtered correlation values.

[0073] In one configuration, if the filtered correlation value is above a first threshold, it can be determined that the patient is connected to the patient interface.

[0074] In one configuration, if the filtered correlation value is above a second threshold for a certain amount of time, it can be determined that the patient is connected to the patient interface.

[0075] In one configuration, the first threshold may be greater than the second threshold.

[0076] In one configuration, once a connection is determined, the filtered Correlation value If V is below a third threshold, the patient can be determined to be disconnected.

[0077] In one configuration, once a connection is determined, the filtered Correlation value If V is below a fourth threshold for a certain amount of time, it can be determined that the patient is disconnected.

[0078] In one configuration, the third threshold may be less than the fourth threshold.

[0079] In one configuration, the fourth threshold may be equal to the second threshold. In one configuration, the fourth threshold may be less than the second threshold.

[0080] In one configuration, if the patient was not already assumed to be connected and the filtered correlation value is between the first and second thresholds for less than a certain amount of time, the patient can be determined to be connected.

[0081] In one configuration, once determined to be connected, the patient may be determined to be disconnected if the correlation value falls below a second threshold.

[0082] In one configuration, if the patient was not already assumed to be disconnected and the filtered correlation value is between the third and fourth thresholds for less than a certain amount of time, it can be determined that the patient is disconnecting.

[0083] In one configuration, once disconnection is determined to be occurring, the patient may be determined to be connected if the correlation value exceeds a fourth threshold.

[0084] In one configuration, the method may further include using the determination of whether a patient is connected to determine whether to display certain parameters.

[0085] In one configuration, the method may further include receiving an estimate of the patient's respiratory rate if the patient is determined to be connected and displaying the respiratory rate estimate.

[0086] In one configuration, the method may further include synchronizing the delivery of gas by the device with the patient's breathing if the patient is determined to be connected.

[0087] In one configuration, the method may further include logging the time of each patient connection status.

[0088] In one configuration, the method may further include generating an alarm when the patient is disconnected.

[0089] In one configuration, the method may further include generating an alarm immediately after the patient is disconnected.

[0090] In one configuration, the method may further include generating an alarm following a preset time after the patient is disconnected.

[0091] In one configuration, the preset time period may be from about 10 seconds to about 10 minutes.

[0092] In one configuration, the preset time period may be from about 30 seconds to about 5 minutes.

[0093] In one example, the preset time period may be from about 1 minute to about 2 minutes.

[0094] In one configuration, the method may further include outputting an alarm through a nurse call port.

[0095] In one configuration, the method may further include the step of accompanying the alert with the device providing the user with the option to check whether the patient is still connected.

[0096] In one configuration, the method may further include overriding the determination that the patient has been disconnected with an option to check whether the patient is still connected.

[0097] In one configuration, the method may further include pausing recording of certain patient parameters only when the patient is disconnected.

[0098] In one configuration, the patient parameters may include oxygen efficiency.

[0099] In one configuration, oxygen efficiency can be based on SpO2 and FdO2.

[0100] In one configuration, the device may include a make-up gas inlet and a valve, and the method may further include the step of the valve being adjusted by the controller to regulate the flow rate of make-up gas through the make-up gas inlet.

[0101] In one configuration, the method may further include the step of the controller closing the valve when the patient is disconnected.

[0102] In one configuration, the method may further include the step of a controller controlling the flow generator to achieve the flow rate, the controller adjusting the flow rate when the patient is disconnected.

[0103] In one configuration, adjusting the flow rate may include reducing the flow rate.

[0104] In one configuration, adjusting the flow rate may include increasing the flow rate.

[0105] In one configuration, the increased flow rate can continue for an initial period.

[0106] In one configuration, the initial period may be from about 10 seconds to about 10 minutes.

[0107] In one configuration, the initial period may be from about 30 seconds to about 5 minutes.

[0108] In one configuration, the initial period may be from about 1 minute to about 2 minutes.

[0109] In one configuration, the method may further include the step of the controller reducing the flow rate when the patient is determined to be still disconnected after the initial period of time.

[0110] In one configuration, the data for the first parameter may include an absolute value of the first parameter.In one configuration, the data for the first parameter may include a variance of the first parameter.

[0111] In one configuration, the method may further include determining the change by subtracting a target value of the first parameter from a measured value of the first parameter.

[0112] In one configuration, the method may further comprise determining the change by subtracting the estimated effect of the second parameter from the measured value of the first parameter.

[0113] In one configuration, the first parameter may be a flow rate.In one configuration, the first parameter may be a pressure.

[0114] In one configuration, the second parameter may be motor speed. In one configuration, the second parameter may be pressure.

[0115] In one configuration, the system may be a non-sealed system.

[0116] In one configuration, the system can be configured to provide nasal high flow therapy.

[0117] In one configuration, the system may include a patient interface, the patient interface being a nasal cannula or a tracheostomy interface.

[0118] In one configuration, the system may be a closed system.

[0119] In one configuration, the system may include a patient interface, the patient interface being a face mask, a nasal mask, an endotracheal tube or a tracheostomy interface.

[0120] In one configuration, the system may include a humidifier configured to humidify the gas flow to the patient.

[0121] In one configuration, the method may further include the step of the controller reducing power to the humidifier when the patient is disconnected.

[0122] In one configuration, the method may further include the step of the controller turning off power to the humidifier when the patient is disconnected.

[0123] In one configuration, the system may include a patient breathing conduit having a heating element configured to heat the flow of gas to the patient.

[0124] In one configuration, the method may further include the step of the controller reducing power to a heating element of the patient breathing conduit when the patient is disconnected.

[0125] In one configuration, the method may further include the step of the controller turning off power to a heating element of the patient breathing conduit when the patient is disconnected.

[0126] In one configuration, the system may include a display configured to receive from the one or more processors and display information relating to whether a patient is connected to the system.

[0127] In one configuration, a respiratory system may be configured to provide respiratory therapy to a patient, the system may also be configured to provide information related to the patient's respiration, the system may include a respiratory device having a controller, the controller may be configured to receive data of a first parameter representative of a flow of gas or of performance of a component of the respiratory device, the first parameter being indicative of the patient's respiration, generate flow parameter change data based on the data of the first parameter, select a portion of the flow parameter change data, and generate a measure of instantaneous patient ventilation based on the portion of the flow parameter change data.

[0128] In one configuration, the controller can be configured to fit or apply one or more functions to selected portions of the flow parameter change data, and generating the measure of instantaneous patient ventilation can include determining an area under a curve generated by the one or more functions. In one configuration, the controller can be configured to apply one or more functions to selected portions of the flow parameter change data, and generating the measure of instantaneous patient ventilation can include determining an area under a curve generated by the one or more functions. The one or more functions can be linear or non-linear or a combination thereof. The curve generated by the one or more functions can be linear, non-linear or a combination thereof. In one configuration, applying one or more functions to the flow parameter change data can output a particular value, such as instantaneous patient ventilation or other similar value.

[0129] In one arrangement, the first parameter may indicate a flow rate, hi one arrangement, the flow rate is a total flow rate.

[0130] In one configuration, the flow parameter change data may be generated by subtracting a target value for the first parameter from a measured value for the first parameter.

[0131] In one configuration, the controller may be further configured to receive data for a second parameter representative of the gas flow or of the performance of a second component of the device, and the flow parameter change data may be generated by subtracting the estimated effect of the second parameter from the measured value of the first parameter.

[0132] In one configuration, the second parameter may be indicative of or is the motor speed.

[0133] In one arrangement, the second parameter may be indicative of or is pressure.

[0134] In one configuration, the flow parameter change data may be generated by subtracting a first average value of the first parameter from a second average value of the first parameter.

[0135] In one configuration, the second average value may be based on a measurement of the first parameter.

[0136] In one configuration, the first average value of the first parameter may be determined by applying an ongoing filter to the first parameter.

[0137] In one configuration, the portion of flow parameter change data includes data relating to time periods within a predefined period of time.

[0138] In one configuration, the portion of the flow parameter change data may represent a length of time.

[0139] In one configuration, the length of time may be such that signal noise is filtered out from the measure of instantaneous patient ventilation.

[0140] In one configuration, the length of time may be such that the predicted breathing frequency will result in an increase in a measure of instantaneous patient ventilation.

[0141] In one configuration, The length of time is 0.5 to 2 seconds can be in the range .

[0142] In one configuration, the controller may be configured to perform a least squares fit to fit one or more functions to selected portions of the flow parameter variation data.

[0143] In one configuration, the curve generated by the one or more functions may be a straight line.

[0144] In one configuration, the curve generated by the one or more functions may be a horizontal line.

[0145] In one configuration, the one or more functions may be algebraic functions.

[0146] In one configuration, one or more of the functions may be transcendental functions.

[0147] In one configuration, one or more functions may generate a best fit line.

[0148] In one configuration, a measure of instantaneous patient ventilation may be generated based on the area under the absolute value of the curve generated by one or more functions.

[0149] In one configuration, the area under the curve can be determined by finding the integral of the absolute value of the line generated by one or more functions.

[0150] In one configuration, a method of generating a measure of instantaneous patient ventilation by a respiratory system that can be configured to provide respiratory therapy to a patient includes receiving, using a controller of the respiratory device, data for a first parameter representative of gas flow or performance of a component of the device, the first parameter being indicative of patient respiration; generating flow parameter change data based on the data for the first parameter; selecting a portion of the flow parameter change data; and generating the measure of instantaneous patient ventilation based on the portion of the flow parameter change data.

[0151] In one configuration, the method may further include applying one or more functions to selected portions of the flow parameter change data, and generating the measure of instantaneous patient ventilation may comprise determining an area under a curve generated by the one or more functions.In one configuration, the method may further include applying one or more functions to selected portions of the flow parameter change data, and generating the measure of instantaneous patient ventilation may comprise determining an area under a curve generated by the one or more functions.

[0152] In one arrangement, the first parameter may be indicative of or is a flow rate. In one arrangement, the flow rate is a total flow rate.

[0153] In one configuration, the method may further include generating flow parameter change data, which may include subtracting a target value for the first parameter from a measured value for the first parameter.

[0154] In one configuration, the method may further include receiving, using a controller of the respiratory device, data for a second parameter representative of the flow of gas or of the performance of a second component of the device, and generating the flow parameter change data may include subtracting an estimated effect of the second parameter from a measurement of the first parameter.

[0155] In one configuration, the second parameter may be indicative of or is the motor speed.

[0156] In one arrangement, the second parameter may be indicative of or is pressure.

[0157] In one configuration, generating the flow parameter variance data may include subtracting a first average value of the first parameter from a second average value of the first parameter.

[0158] In one configuration, the second average value may be based on a measurement of the first parameter.

[0159] In one configuration, the first average value of the first parameter may be determined by applying an ongoing filter to the first parameter.

[0160] In one configuration, the portion of flow parameter change data includes data relating to time periods within a predefined period of time.

[0161] In one configuration, the portion of the flow parameter change data may represent a length of time.

[0162] In one configuration, the length of time may be such that signal noise is filtered out from the measure of instantaneous patient ventilation.

[0163] In one configuration, the length of time may be such that the predicted breathing frequency will result in an increase in a measure of instantaneous patient ventilation.

[0164] In one configuration, the length of time may be between 0.5 and 2 seconds.

[0165] In one configuration, the controller may perform a least squares fit to fit one or more functions to selected portions of the flow parameter variation data.

[0166] In one configuration, the curve generated by the one or more functions may be a straight line.

[0167] In one configuration, the curve generated by the one or more functions may be a horizontal line.

[0168] In one configuration, the one or more functions may be algebraic functions.

[0169] In one configuration, one or more of the functions may be transcendental functions.

[0170] In one configuration, one or more functions may generate a best fit line.

[0171] In one configuration, a measure of instantaneous patient ventilation may be generated based on the area under the absolute value of the curve generated by one or more functions.

[0172] In one configuration, the area under the curve can be determined by finding the integral of the absolute value of the line generated by one or more functions.

[0173] In one configuration, a respiratory system can be configured to provide respiratory therapy to a patient, the system also configured to provide information related to the patient's respiration, the system can include a respiratory device which can include a controller, the controller can be configured to receive data of a first parameter representative of a gas flow or of performance of a component of the device, the first parameter can be indicative of the patient's respiration, generate flow parameter change data based on the data of the first parameter, generate a measure of patient ventilation based on the flow parameter change data, generate a measure of total signal variability based on the flow parameter change data, and determine patient connection based on a comparison of the measure of patient ventilation and the measure of total signal variability.

[0174] In one configuration, the first parameter may be indicative of or is a flow rate.

[0175] In one configuration, the flow parameter change data may be generated by subtracting a target value for the first parameter from a measured value for the first parameter.

[0176] In one configuration, the controller may be further configured to receive data for a second parameter representative of the gas flow or of the performance of a second component of the device, and the flow parameter change data may be generated by subtracting the estimated effect of the second parameter from the measured value of the first parameter.

[0177] In one configuration, the second parameter may be indicative of or is the motor speed.

[0178] In one arrangement, the second parameter may be indicative of or is pressure.

[0179] In one configuration, the flow parameter change data may be generated by subtracting a first average value of the first parameter from a second average value of the first parameter.

[0180] In one configuration, the second average value may be based on a measurement of the first parameter.

[0181] In one configuration, the first average value of the first parameter may be determined by applying an ongoing filter to the first parameter.

[0182] In one configuration, the controller may be further configured to generate a measure of instantaneous patient ventilation from the flow parameter change data, and the measure of patient ventilation may be generated by filtering the measure of instantaneous patient ventilation.

[0183] In one configuration, the controller may be further configured to select a portion of the flow parameter change data.

[0184] In one configuration, the portion of flow parameter change data may represent a period of 0.5 to 2 seconds.

[0185] In one configuration, a measure of instantaneous patient ventilation can be generated by fitting one or more functions to a selected portion of the flow parameter change data and determining the area under the absolute value of the curve generated by the one or more functions. The one or more functions can be linear or non-linear or a combination thereof. The curve generated by the one or more functions can be linear, non-linear or a combination thereof. In one configuration, applying one or more functions to the flow parameter change data can output a particular value, such as instantaneous patient ventilation or other similar value.

[0186] In one configuration, the controller may be configured to perform a least squares fit to fit one or more functions to selected portions of the flow parameter variation data.

[0187] In one configuration, the curve generated by the one or more functions may be a straight line.

[0188] In one configuration, the curve generated by the one or more functions may be a horizontal line.

[0189] In one configuration, determining the area under the modulus of the curve may include finding the integral of the modulus of the curve generated by one or more functions.

[0190] In one configuration, the controller may be further configured to generate a measure of instantaneous total signal variation from the flow parameter change data, and the measure of total signal variation may be generated by filtering the measure of instantaneous total signal variation.

[0191] In one configuration, a measure of the instantaneous total signal variation can be determined by taking the absolute value of the flow parameter change data.

[0192] In one configuration, a measure of the instantaneous total signal variation can be determined by taking the square of the flow parameter change data.

[0193] In one configuration, comparing the measure of patient ventilation to the measure of total signal variability may include taking a ratio of the measure of patient ventilation to the measure of total signal variability.

[0194] In one configuration, once connected, the controller can be configured to determine that the patient is disconnected if the ratio falls below a connection threshold. In one configuration, once connected, the controller is configured to determine that the patient is connected if the ratio does not fall below a connection threshold.

[0195] In one configuration, once determined to be disconnected, the controller may be configured to determine that the patient is connected if the ratio exceeds a connection threshold.

[0196] In one configuration, once disconnection is determined, the controller may be configured to determine that the patient is disconnected if the ratio does not exceed a connection threshold.

[0197] In one configuration, the controller may be configured to determine that the patient is connected if the ratio is above a first threshold.

[0198] In one configuration, the controller can be configured to determine that the patient is connected if the ratio is above a second threshold for a certain amount of time.

[0199] In one configuration, the first threshold may be greater than the second threshold.

[0200] In one configuration, once determined to be connected, the patient may be determined to be disconnected if the ratio falls below a third threshold.

[0201] In one configuration, once determined to be connected, the patient may be determined to be disconnected if the ratio remains below a fourth threshold for a certain amount of time.

[0202] In one configuration, the third threshold may be less than the fourth threshold.

[0203] In one configuration, the fourth threshold may be equal to the second threshold.

[0204] In one configuration, the fourth threshold may be less than the second threshold.

[0205] In one configuration, the controller can be configured to determine that the patient is connected if the ratio is between the first and second thresholds for less than a certain amount of time when the patient was not already assumed to be connected.

[0206] In one configuration, once determined to be connected, the patient may be determined to be disconnected if the ratio falls below a second threshold.

[0207] In one configuration, the controller can be configured to determine that the patient is disconnecting if the ratio is between the third and fourth thresholds for less than a certain amount of time, if the patient was not already assumed to be disconnected.

[0208] In one configuration, once disconnection is determined to be occurring, the patient may be determined to be connected if the ratio exceeds a fourth threshold.

[0209] In one configuration, the controller can be configured to use the determination of whether or not a patient is connected to determine whether or not to display certain parameters.

[0210] In one configuration, the controller may be configured to receive an estimate of the patient's respiratory rate if the controller determines that a patient is connected, and display the respiratory rate estimate.

[0211] In one configuration, the respiratory device may be configured to synchronize the delivery of gas with the patient's breathing if it is determined that a patient is connected.

[0212] In one configuration, the controller can be configured to log the time of each patient connection status.

[0213] In one configuration, the respiratory device may generate an alarm when the patient is disconnected.

[0214] In one configuration, the device can generate an alarm immediately after the patient is disconnected.

[0215] In one configuration, the device may generate an alarm following a preset time after the patient is disconnected.

[0216] In one configuration, the preset time period may be from about 10 seconds to about 10 minutes.

[0217] In one configuration, the preset time period may be from about 30 seconds to about 5 minutes.

[0218] In one configuration, the preset time period may be from about 1 minute to about 2 minutes.

[0219] In one configuration, the alarm can be output through a nurse call port.

[0220] In one configuration, the alert may be accompanied by the device providing the user with the option to check whether the patient is still connected.

[0221] In one configuration, the option to check if the patient is still connected can be used to override the determination that the patient has been disconnected.

[0222] In one configuration, the respiratory device may pause recording of certain patient parameters only when the patient is disconnected.

[0223] In one configuration, the patient parameters may include oxygen efficiency.

[0224] In one configuration, oxygen efficiency can be based on SpO2 and FdO2.

[0225] In one configuration, the device may include a make-up gas inlet and a valve, the valve being adjustable by a controller to regulate the flow rate of make-up gas through the make-up gas inlet.

[0226] In one configuration, the controller can close the valve when the patient is disconnected.

[0227] In one configuration, the controller can control the flow generator to achieve the flow rate, and the controller can adjust the flow rate once the patient is disconnected.

[0228] In one configuration, adjusting the flow rate may include reducing the flow rate.

[0229] In one configuration, adjusting the flow rate may include increasing the flow rate.

[0230] In one configuration, the increased flow rate can continue for an initial period.

[0231] In one configuration, the initial period may be from about 10 seconds to about 10 minutes.

[0232] In one configuration, the initial period may be from about 30 seconds to about 5 minutes.

[0233] In one configuration, the initial period may be from about 1 minute to about 2 minutes.

[0234] In one configuration, the controller may reduce the flow rate when it is determined that the patient is still disconnected after an initial period of time.

[0235] In one configuration, a method for determining patient disconnection and / or connection to a breathing system can be configured to provide respiratory therapy to a patient, the system also configured to provide information related to the patient's respiration, the method including the steps of receiving, using a controller of a breathing device, data for a first parameter representative of a gas flow or of performance of a device component, the first parameter being indicative of the patient's respiration; generating flow parameter change data based on the data for the first parameter; generating a measure of patient ventilation based on the flow parameter change data; generating a measure of total signal variability based on the flow parameter change data; and determining patient connection based on a comparison of the measure of patient ventilation and the measure of total signal variability.

[0236] In one configuration, the first parameter may be indicative of or is a flow rate.

[0237] In one configuration, generating the flow parameter change data may include subtracting a target value of the first parameter from the measured value of the first parameter.

[0238] In one configuration, the method may further include receiving, using a controller of the respiratory device, data for a second parameter representative of the flow of gas or of the performance of a second component of the device, and generating the flow parameter change data may include subtracting an estimated effect of the second parameter from a measurement of the first parameter.

[0239] In one configuration, the second parameter may be indicative of or is the motor speed.

[0240] In one arrangement, the second parameter may be indicative of or is pressure.

[0241] In one configuration, generating the flow parameter variance data may include subtracting a first average value of the first parameter from a second average value of the first parameter.

[0242] In one configuration, the second average value may be based on a measurement of the first parameter.

[0243] In one configuration, the first average value of the first parameter may be determined by applying an ongoing filter to the first parameter.

[0244] In one configuration, the method may further include generating, using a controller of the respiratory device, a measure of instantaneous patient ventilation from the flow parameter change data, and generating the measure of patient ventilation may include filtering the measure of instantaneous patient ventilation.

[0245] In one configuration, the method may further include selecting a portion of the flow parameter change data using a controller of the respiratory device.

[0246] In one configuration, the portion of flow parameter change data may represent a period of 0.5 to 2 seconds.

[0247] In one configuration, generating the measure of instantaneous patient ventilation may include fitting one or more functions to a selected portion of the flow parameter change data and determining the area under the absolute value of the curve generated by the one or more functions.

[0248] In one configuration, determining the area under the absolute value of the curve generated by the one or more functions may include the controller performing a least squares fit to fit the one or more functions to a selected portion of the flow parameter change data.

[0249] In one configuration, the curve generated by the one or more functions may be a straight line.

[0250] In one configuration, the curve generated by the one or more functions may be a horizontal line.

[0251] In one configuration, the area under the modulus of the curve may be determined by finding the integral of the modulus of the curve generated by one or more functions.

[0252] In one configuration, the method may further include generating, using a controller of the respiratory device, a measure of instantaneous total signal variation from the flow parameter change data, wherein generating the measure of total signal variation may include filtering the measure of instantaneous total signal variation.

[0253] In one configuration, generating the measure of instantaneous total signal variation may include taking the absolute value of the flow parameter change data.

[0254] In one configuration, generating a measure of instantaneous total signal variation may include taking the square of the flow parameter change data.

[0255] In one configuration, comparing the measure of patient ventilation to the measure of total signal variability may include taking a ratio of the measure of patient ventilation to the measure of total signal variability.

[0256] In one configuration, once determined to be connected, the patient may be determined to be disconnected if the ratio falls below a connection threshold.

[0257] In one configuration, once connected, if the ratio is not below a connection threshold, the patient may be determined to be connected.

[0258] In one configuration, once determined to be disconnected, the patient may be determined to be connected if the ratio exceeds a connection threshold.

[0259] In one configuration, once determined to be disconnected, if the ratio does not exceed a connection threshold, the patient may be determined to be disconnected.

[0260] In one configuration, if the ratio is above a first threshold, the patient may be determined to be connected.

[0261] In one configuration, if the ratio remains above a second threshold for a certain amount of time, the patient may be determined to be connected.

[0262] In one configuration, the first threshold may be greater than the second threshold.

[0263] In one configuration, once determined to be connected, the patient may be determined to be disconnected if the ratio falls below a third threshold.

[0264] In one configuration, once determined to be connected, the patient may be determined to be disconnected if the ratio remains below a fourth threshold for a certain amount of time.

[0265] In one configuration, the third threshold may be less than the fourth threshold.

[0266] In one configuration, the fourth threshold may be equal to the second threshold.

[0267] In one configuration, the fourth threshold may be less than the second threshold.

[0268] In one configuration, if the patient was not already assumed to be connected and the ratio is between the first and second thresholds for less than a certain amount of time, the patient can be determined to be connected.

[0269] In one configuration, once determined to be connected, the patient may be determined to be disconnected if the ratio falls below a second threshold.

[0270] In one configuration, if the patient was not already assumed to be disconnected and the ratio is between the third and fourth thresholds for less than a certain amount of time, the patient can be determined to be disconnecting.

[0271] In one configuration, once disconnection is determined to be occurring, the patient may be determined to be connected if the ratio exceeds a fourth threshold.

[0272] In one configuration, the method may further include using a controller of the respiratory device to determine whether or not to display certain parameters based on whether or not a patient is connected.

[0273] In one configuration, the method may further include receiving, using a controller of the respiratory device, an estimate of the patient's respiratory rate if it is determined that the patient is connected, and displaying the respiratory rate estimate.

[0274] In one configuration, the method may further include using a controller of the respiratory device to synchronize the delivery of gas with the patient's breathing if it is determined that the patient is connected.

[0275] In one configuration, the method may further include logging the time of each patient connection status using a controller of the respiratory device.

[0276] In one configuration, the method may further include using a controller of the respiratory device to generate an alarm when the patient is disconnected.

[0277] In one configuration, the method may further include generating an alarm immediately after the patient is disconnected.

[0278] In one configuration, the method may further include generating an alarm following a preset time after the patient is disconnected.

[0279] In one configuration, the preset time period may be from about 10 seconds to about 10 minutes.

[0280] In one configuration, the preset time period may be from about 30 seconds to about 5 minutes.

[0281] In one configuration, the preset time period may be from about 1 minute to about 2 minutes.

[0282] In one configuration, the method may further include outputting an alarm through a nurse call port.

[0283] In one configuration, the method may further include accompanying the alert with providing the user with the option to check whether the patient is still connected.

[0284] In one configuration, the option to check if the patient is still connected can be used to override the determination that the patient has been disconnected.

[0285] In one configuration, the method may further include using a controller of the respiratory device to pause recording of certain patient parameters only when the patient is disconnected.

[0286] In one configuration, the patient parameters may include oxygen efficiency.

[0287] In one configuration, oxygen efficiency can be based on SpO2 and FdO2.

[0288] In one configuration, the device may include a make-up gas inlet and a valve, and the method may further include the step of the valve being adjusted by the controller to regulate the flow rate of make-up gas through the make-up gas inlet.

[0289] In one configuration, the method may further include the step of the controller closing the valve when the patient is disconnected.

[0290] In one configuration, the method may further include the step of a controller controlling the flow generator to achieve the flow rate, the controller configured to adjust the flow rate when the patient is disconnected.

[0291] In one configuration, adjusting the flow rate may include reducing the flow rate.

[0292] In one configuration, adjusting the flow rate may include increasing the flow rate.

[0293] In one configuration, the increased flow rate can continue for an initial period.

[0294] In one configuration, the initial period may be from about 10 seconds to about 10 minutes.

[0295] In one configuration, the initial period may be from about 30 seconds to about 5 minutes.

[0296] In one configuration, the initial period may be from about 1 minute to about 2 minutes.

[0297] In one configuration, the method may further include the step of the controller reducing the flow rate when the patient is determined to be still disconnected after the initial period of time.

[0298] In a further configuration, the respiratory device includes a controller configured to determine use of the respiratory device based on the amount of time the patient is detected as connected. The controller is configured to track the amount of time the patient is detected as connected. The controller can further determine and count the number of times the patient is detected as disconnected within a predefined period of time. The predefined period can be, for example, a therapy session. The controller can be configured to transmit the amount of time the patient is detected as connected to a remote computing device, for example, a server. In a further configuration, the server can determine the amount of time the patient has used the respiratory device based on the amount of time or number of times the patient is detected as connected. The controller or server can determine that the patient is compliant with therapy (e.g., high-flow therapy) if the patient is detected as connected for a predetermined period of time. Patient detection methods can be used to determine compliance with therapy, i.e., adherence to therapy. Detecting the patient as connected can be used to determine the patient's use of the respiratory device. This usage or compliance information can be shared or accessed by a medical professional via the respiratory device or via the server.

[0299] These and other features, aspects, and advantages of the present disclosure will be described with reference to drawings of several embodiments, which are intended to schematically illustrate several embodiments and are not intended to limit the disclosure. [Brief explanation of the drawings]

[0300] [Figure 1] 1 illustrates a schematic representation of a respiratory system configured to provide respiratory therapy to a patient. [Figure 2] FIG. 1 is a front view of an example respiratory device with the humidification chamber in place and the handle / lever raised. [Figure 3]FIG. 3 is a top view corresponding to FIG. 2. [Figure 4] FIG. 3 is a right side view corresponding to FIG. 2. [Figure 5] FIG. 3 is a left side view corresponding to FIG. 2. [Figure 6] FIG. 3 is a rear view corresponding to FIG. 2. [Figure 7] FIG. 3 is a front left perspective view corresponding to FIG. 2. [Figure 8] FIG. 3 is a front right perspective view corresponding to FIG. 2. [Figure 9] FIG. 3 is a bottom view corresponding to FIG. 2. [Figure 10] 1 shows an example configuration of the air and oxygen inlet arrangement of the breathing device. [Figure 11] 10 shows another example of an arrangement of air and oxygen inlet ports for a respiratory device. [Figure 12] FIG. 12 is a cross-sectional view showing further details of the air and oxygen inlet arrangement of FIG. 11. [Figure 13] FIG. 12 is another cross-sectional view showing further details of the air and oxygen inlet arrangement of FIG. 11. [Figure 14] FIG. 12 is a longitudinal section showing further details of the air and oxygen inlet arrangement of FIG. 11; [Figure 15] FIG. 12 is an exploded view of the upper and lower chassis components of the main housing of the respiratory device. [Figure 16] FIG. 1 is a front left perspective view of the lower chassis of the main housing showing the housing that receives the monitor / sensor module subassembly. [Figure 17] FIG. 1 is a first bottom perspective view of the main housing of the respiratory device showing the recess inside the housing for the monitor / sensor module subassembly. [Figure 18] FIG. 10 is a second perspective underside view of the main housing of the respiratory device showing the recess for the monitor / sensor module subassembly. [Figure 19A] 1 shows a block diagram of a control system that interacts with and / or provides control and direction to components of the respiratory system. [Figure 19B] 1 shows a block diagram of an example controller. [Figure 20] FIG. 1 shows a block diagram of a motor and sensor module. [Figure 21] 1 illustrates the sensing chamber of an example motor and sensor module. [Figure 22] 1 illustrates an example flowchart for evaluating instantaneous features for patient breath detection. [Figure 23A-C] An example of determining whether flow parameter data is suitable for use in determining patient connection and / or respiration is provided. [Figure 23D] 1 shows an example flow chart for correcting flow data to remove the assumed effect of motor speed. [Figure 24] Shown are examples of instantaneous features when different frequencies are evaluated (no signal noise). [Figure 25A] 10 illustrates an example flowchart for determining filtered features for patient connection determination. [Figure 25B] 10 illustrates an example flowchart for determining patient connectivity status using filtered features. [Figure 26] 1 shows an example flowchart for generating a measure for determining patient connection to a respiratory system. [Figure 27] 10 shows an example flowchart for determining patient connectivity using a patient connectivity measure. [Figure 28] 10 illustrates another example flowchart for determining patient connectivity status using a patient connectivity measure. DETAILED DESCRIPTION OF THE INVENTION

[0301] Although several examples are described below, those skilled in the art will recognize that the present disclosure extends beyond the specifically disclosed examples and / or uses and obvious modifications and equivalents thereof. Accordingly, it is not intended that the scope of the present disclosure disclosed herein should be limited by any specific examples described below.

[0302] Overview of example breathing systems FIG. 1 provides a schematic diagram of a respiratory system 10. The respiratory system 10 may include a main device housing 100. The main device housing 100 may include a flow generator 11, which may be in the form of a motor / impeller arrangement, optionally a humidifier or humidification chamber 12, a controller 13, and a user interface 14. The user interface 14 may include a display and input devices, such as buttons, a touchscreen, or a combination of a touchscreen and buttons. The controller 13 may include one or more hardware and / or software processors and may be configured or programmed to control components of the system, including, but not limited to, operating the flow generator 11 to generate a flow of gas for delivery to a patient, operating the humidifier or humidification chamber 12 (if present) to humidify and / or heat the gas flow, receiving user input from the user interface 14 for reconfiguration and / or user-defined operation of the respiratory system 10, and outputting information to a user (e.g., on a display). The user may be a patient, a medical professional, the system 10, or the like.

[0303] 1 , a patient breathing conduit 16 may be coupled to a gas outlet 21 in the main device housing 100 of the respiratory system 10, and the patient breathing conduit 16 may be coupled to a patient interface 17, such as a non-sealing interface, such as a nasal cannula with a manifold 19 and nasal prongs 18. The patient breathing conduit 16 may also be coupled to a face mask, a nasal mask or nasal pillow mask, an endotracheal tube, a tracheostomy interface, or the like.

[0304] The gas flow may be generated by a flow generator 11 and may be humidified before delivery to the patient through a patient interface 17 via a patient breathing conduit 16. A controller 13 may control the flow generator 11 to generate a gas flow at a desired rate and / or control one or more valves to control the mixture of air and oxygen or other breathable gas. The controller 13 may control a heating element in the humidification chamber 12, if present, to heat the gas to a desired temperature to achieve a desired level of temperature and / or humidity for delivery to the patient. The patient breathing conduit 16 may have a heating element 16a, such as a heater wire, that heats the gas flow passing through it to the patient. The heating element 16a may also be under the control of the controller 13.

[0305] The system 10 may use ultrasound transducers, flow sensors such as thermistor flow sensors, pressure sensors, temperature sensors, humidity sensors, or other sensors in communication with the controller 13 to monitor characteristics of the gas flow and / or operate the system 10 to provide a suitable therapy. Characteristics of the gas flow may include gas concentration, flow rate, pressure, temperature, humidity, etc. Sensors 3a, 3b, 3c, 20, 25, such as pressure sensors, temperature sensors, humidity sensors, and / or flow sensors, may be located at various locations within the main device housing 100, the patient conduit 16, and / or the patient interface 17. The controller 13 may receive outputs from the sensors that help the controller 13 operate the respiratory system 10 to provide a suitable therapy, such as determining a suitable target temperature, flow rate, and / or pressure for the gas flow. Providing a suitable therapy may include meeting the patient's inspiratory demands.

[0306] System 10 may include a wireless data transmitter and / or receiver, or transceiver 15, that enables controller 13 to wirelessly receive data signals 8 from the motion sensors and / or control various components of system 10. Additionally or alternatively, data transmitter and / or receiver 15 may send data to a remote server or enable remote control of system 10. System 10 may also include wired connections, e.g., using cables or wires, that enable controller 13 to receive data signals 8 from the motion sensors and / or control various components of system 10.

[0307] The respiratory system 10 may include a high-flow therapy device. High-flow therapy, as discussed herein, is intended to be given its typical and ordinary meaning as understood by those skilled in the art, generally referring to a respiratory system that delivers a targeted flow of humidified respiratory gas through an intentionally unsealed patient interface at a flow rate generally intended to meet or exceed the user's inspiratory flow. Exemplary patient interfaces include, but are not limited to, nasal or tracheal patient interfaces. Typical flow rates for adults are often, but are not limited to, in the range of about 15 liters / minute to about 60 liters / minute or more. Typical flow rates for pediatric users (such as neonates, infants, and children) are often, but are not limited to, in the range of about 1 liter / minute per kilogram of user body weight to about 3 liters / minute per kilogram of user body weight or more. High-flow therapy may also include gas mixture compositions, including the administration of supplemental oxygen and / or therapeutic agents. 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. For example, in some configurations, for an adult patient, "high flow therapy" can refer to the delivery of gas to a patient at a flow rate of about 10 liters per minute (10 LPM) or greater, e.g., from about 10 LPM to about 100 LPM, or from about 15 LPM to about 95 LPM, or from about 20 LPM to about 90 LPM, or from about 25 LPM to about 85 LPM, or from about 30 LPM to about 80 LPM, or from about 35 LPM to about 75 LPM, or from about 40 LPM to about 70 LPM, or from about 45 LPM to about 65 LPM, or from about 50 LPM to about 60 LPM.In some configurations, for neonatal, infant, or pediatric patients, "high flow therapy" can refer to the delivery of gas to a patient at a flow rate of greater than 1 LPM, e.g., from about 1 LPM to about 25 LPM, or from about 2 LPM to about 25 LPM, or from about 2 LPM to about 5 LPM, or from about 5 LPM to about 25 LPM, or from about 5 LPM to about 10 LPM, or from about 10 LPM to about 25 LPM, or from about 10 LPM to about 20 LPM, or from about 10 LPM to 15 LPM, or from about 20 LPM to 25 LPM. High flow therapy devices for adult, neonatal, infant, or pediatric patients can deliver gas to a patient at a flow rate of from about 1 LPM to about 100 LPM, or any of the subranges outlined above.

[0308] High-flow therapy can be effective in meeting or exceeding a patient's inspiratory demand, increasing the patient's oxygenation, and / or reducing the work of breathing. Additionally, high-flow therapy can create a flushing effect in the nasopharynx, such that the anatomical dead space in the upper airway is flushed by the incoming high-flow gas stream. The flushing effect can provide a reservoir of fresh gas available with every breath, while minimizing rebreathing of carbon dioxide, nitrogen, etc.

[0309] The patient interface used in high-flow therapy may be a non-sealing interface to prevent barotrauma, which may include tissue damage to the lungs or other organs of the patient's respiratory system due to pressure differences relative to the atmosphere. The patient interface may be a nasal cannula with a manifold and nasal prongs, and / or a face mask, and / or a nasal pillows mask, and / or a nasal mask, and / or a tracheostomy interface, or any other suitable type of patient interface.

[0310] 2-17B illustrate an example respiratory device of the respiratory system 10 having a main housing 100. The main housing 100 has a main housing upper chassis 102 and a main housing lower chassis 202. The main housing upper chassis 102 has a peripheral wall arrangement 106 (see FIG. 15 ). The peripheral wall arrangement defines a humidifier or humidification chamber bay 108 that receives a removable humidification chamber 300. The removable humidification chamber 300 contains a suitable liquid, such as water, that humidifies gases that can be delivered to a patient.

[0311] In the illustrated form, the perimeter wall arrangement 106 of the main housing top chassis 102 may include a substantially vertical left outer wall 110 oriented in the fore-aft direction of the main housing 100, a substantially vertical left inner wall 112 oriented in the fore-aft direction of the main housing 100, and an interconnecting wall 114 extending between and interconnecting upper ends of the left inner wall 110 and the left outer wall 112. The main housing top chassis 102 may further include a substantially vertical right outer wall 116 oriented in the fore-aft direction of the main housing 100, a substantially vertical right inner wall 118 oriented in the fore-aft direction of the main housing 100, and an interconnecting wall 120 extending between and interconnecting upper ends of the right inner wall 116 and the right outer wall 118. The interconnecting walls 114, 120 are angled toward the respective outer edges of the main housing 100, but may alternatively be substantially horizontal or angled inward.

[0312] The main housing upper chassis 102 may further include a substantially vertical rear outer wall 122. The top of the main housing upper chassis 102 may include a forwardly angled surface 124. The surface 124 may have a recess 126 that receives the display and user interface module 14. The display may be configured to display the characteristics of the detected gas in real time. The system may display the patient detection status of the patient interface. If no patient is detected, the controller may not output or may stop outputting the respiratory rate value and / or other parameters for display. The controller may also output to display a message that no patient is detected in block 2708. An example of a message may be a "--" icon. An interconnecting wall 128 may extend between and interconnect the upper end of the rear outer wall 122 and the rear edge of the surface 124.

[0313] A substantially vertical wall portion 130 may extend downwardly from the front end of the surface 124. A substantially horizontal wall portion 132 may extend forwardly from the lower end of the wall portion 130 to form a shelf. A substantially vertical wall portion 134 may extend downwardly from the front end of the wall portion 132 and terminate at a substantially horizontal floor portion 136 of the humidification chamber bay 108. The left interior wall 112, the right interior wall 118, the wall portion 134, and the floor portion 136 may together define the humidification chamber bay 108. The floor portion 136 of the humidification chamber bay 108 may have a recess 138 to receive a heater arrangement, such as a heater plate 140 or other suitable heating element, for heating liquid in the humidification chamber 300 used during the humidification process.

[0314] The main housing lower chassis 202 may be attachable to the upper chassis 102 either by suitable fasteners, such as clips, or by incorporated mounting features. The main housing lower chassis 202 may include a substantially vertical left outer wall 210 oriented in the fore-aft direction of the main housing 100 and adjacent to the left outer wall 110 of the upper chassis 102, and a substantially vertical right outer wall 216 oriented in the fore-aft direction of the main housing 100 and adjacent to the right outer wall 116 of the upper chassis 102. The main housing lower chassis 202 may further include a substantially vertical rear outer wall 222 adjacent to the rear outer wall 122 of the upper chassis 102.

[0315] The lower housing chassis 202 can have a lip 242 that abuts the lip 142 of the upper housing chassis 102 and also forms part of a recess that receives the handle portion 506 of the lever 500. The lower lip 242 can include a forwardly directed protrusion 243 that acts as a retainer for the handle portion 506 of the lever 500. Instead of the lever 500, the system can have a spring-loaded guard that retains the humidification chamber 300 in the humidification chamber bay 108.

[0316] The underside of the lower housing chassis 202 may include a bottom wall 230. Respective interconnecting walls 214, 220, 228 may extend between and interconnect the substantially vertical walls 210, 216, 222 and the bottom wall 230. The bottom wall 230 may include a grill 232 with a plurality of apertures that allow liquid to drain in the event of a leak (e.g., from a spill) from the humidification chamber 300. The bottom wall 230 may further include an elongated, front-to-rear oriented slot 234. The slot 234 may further allow liquid to drain in the event of a leak from the humidification chamber 300 without the liquid entering the electronics housing. In the illustrated configuration, the slot 234 may be wide and elongated relative to the apertures of the grill 232 to maximize liquid drainage.

[0317] As shown in FIGS. 17 and 18 , the lower chassis 202 can have a motor recess 250 that receives a motor and sensor module. The motor and sensor module may be non-removable from the main housing 100. The motor and sensor module may be removable from the main housing 100, as shown in FIGS. 17 and 18 . A recess opening 251 can be provided in the bottom wall 230 adjacent its rear edge to receive the motor / sensor module. A continuous, gas-impermeable, uninterrupted peripheral wall 252 can be formed integrally with the bottom wall 230 of the lower chassis 202 and extend outward from the periphery of the opening 251. A rear portion 254 of the peripheral wall 252 has a first height, and a front portion 256 of the peripheral wall 252 has a second height that is greater than the first height. The rear portion 254 of the peripheral wall 252 terminates in a substantially horizontal step 258 that further terminates in an upper, auxiliary rear portion 260 of the peripheral wall 252. The forward portion 256 and upper auxiliary rear portion 260 of the peripheral wall 252 terminate at a ceiling 262. All of the walls and the ceiling 262 may be continuous, gas-impermeable, and uninterrupted except for the gas flow passages. Thus, the entire motor recess 250 may be gas-impermeable and uninterrupted except for the gas flow passages.

[0318] The motor and sensor module may be insertable into the recess 250 and attachable to the lower chassis 202. When the motor and sensor module is inserted into the lower chassis 202, the gas flow tube 264 may extend through the downward extension tube 133 and be sealed by a soft seal.

[0319] The humidification chamber 300 can be fluidly coupled to the device 10 with a linear sliding motion from a position at the front of the housing 100 toward the rear of the housing 100, rearwardly of the humidification chamber 300 into the chamber bay 108. A gas outlet port 322 can be in fluid communication with the motor.

[0320] 8, the gas inlet port 340 (humidified gas return) may include a removable L-shaped elbow. The removable elbow may further include a patient outlet port 344 that couples to the patient conduit 16, which delivers gas to the patient interface. The gas outlet port 322, the gas inlet port 340, and the patient outlet port 344 may each have a soft seal, such as an O-ring seal or a T-seal, to provide a sealed gas passage between the device 10, the humidification chamber 300, and the patient conduit 16.

[0321] The humidification chamber gas inlet port 306 may be complementary to the gas outlet port 322, and the humidification chamber gas outlet port 308 may be complementary to the gas inlet port 340. The axes of the ports may be parallel to one another, allowing the humidification chamber 300 to be inserted into the chamber bay 108 with a linear motion.

[0322] The respiratory device may have air and oxygen (or alternative supplemental gas) inlets in fluid communication with the motor so that the motor can deliver air, oxygen (or alternative supplemental gas), or a mixture thereof to the humidification chamber 300 and thereby to the patient. As shown in FIG. 10 , the device may have a combined air / oxygen (or alternative supplemental gas) inlet arrangement 350. This arrangement may include a combined air / oxygen port 352 into the housing 100, a filter 354, and a cover 356 with a hinge 358. A gas tube may also extend laterally or in another suitable direction and be in fluid communication with the oxygen (or alternative supplemental gas) source. The port 352 may be fluidly coupled to the motor 402. For example, the port 352 may be coupled to the motor / sensor module 400 via a gas flow path between the port 352 and an inlet aperture or port of the motor and sensor module 400 (which further leads to the motor).

[0323] The device can have the arrangement shown in FIGS. 11-14 that enables the motor to deliver air, oxygen (or alternative auxiliary gas), or a suitable mixture thereof to the humidification chamber 300 and thereby to the patient. This arrangement can include an air inlet 356' in the rear wall 222 of the lower chassis 202 of the housing 100. The air inlet 356' comprises a rigid plate having a suitable grill arrangement of apertures and / or slots. Sound-deadening foam can be provided adjacent to the inner surface of the plate. Positioned within the main housing 100 adjacent to the air inlet 356' is an air filter box 354' that can include an air outlet port 360 that delivers filtered air to the motor via the air inlet port 404 of the motor / sensor module 400. The air filter box 354' can include a filter configured to remove particles (e.g., dust) and / or pathogens (e.g., viruses or bacteria) from the gas flow. A soft seal, such as an O-ring seal, may be provided between the air outlet port 360 and the air inlet port 404 to provide a seal between these components. The device may include a separate oxygen inlet port 358' positioned adjacent one side of the housing 100 at its rear end for receiving oxygen from an oxygen source, such as a tank or source of piped oxygen. The oxygen inlet port 358' is in fluid communication with a valve 362. The valve 362 may preferably be a solenoid valve that allows control of the amount of oxygen added to the gas stream delivered to the humidification chamber 300. The oxygen port 358' and valve 362 may be used with other supplemental gases to control the addition of other supplemental gases to the gas stream. The other supplemental gases may include any one or more of a number of gases useful in gas therapy, including, but not limited to, heliox and nitric oxide.

[0324] As shown in Figures 13-16, the lower housing chassis 202 can include a suitable electronic circuit board, such as a sensing circuit board. The electronic circuit board can be positioned adjacent each outer sidewall 210, 216 of the lower housing chassis 202. The electronic circuit board can include or be in electrical communication with suitable electrical or electronic components, such as, but not limited to, a microprocessor, capacitors, resistors, diodes, operational amplifiers, comparators, and switches. Sensors can be used in conjunction with the electronic circuit board. Components of the electronic circuit board, such as, but not limited to, one or more microprocessors, can act as the controller 13 of the device.

[0325] One or both of the electronic circuit boards can be in electrical communication with the electrical components of the device 10, including the display unit and user interface 14, the motor, the valve 362, and the heater plate 140, to operate the motor to provide the desired flow rate of gas, operate the humidification chamber 300 to humidify and heat the gas stream to an appropriate level, and supply an appropriate amount of oxygen (or an appropriate amount of an alternative auxiliary gas) to the gas stream.

[0326] The electronic circuit board can be in electrical communication with a connector arrangement 274 protruding from the rear wall 122 of the upper housing chassis 102. The connector arrangement 274 can be coupled to an alarm, a pulse oximetry port, and / or other suitable accessories. The electronic circuit board can also be in electrical communication with an electrical connector 276, which can also be provided on the rear wall 122 of the upper housing chassis 102 for providing AC or battery power to the device components.

[0327] As mentioned above, operational sensors, such as flow, temperature, humidity, and / or pressure sensors, may be located at various locations within the respiratory device, the patient breathing conduit 16, and / or the cannula 17, as shown in Figure 1. The electronic circuit board may be in electrical communication with the sensors. Output from the sensors may be received by the controller 13 to help the controller 13 operate the respiratory system 10 to provide optimal therapy, such as meeting inspiratory demand.

[0328] As outlined above, electronic circuit boards and other electrical and electronic components can be pneumatically isolated from the gas flow path for improved safety. Sealing also prevents water ingress.

[0329] Control System FIG. 19A shows a block diagram 900 of an example control system 920 (which may be controller 13 in FIG. 1 ) that can detect patient conditions and control the operation of the respiratory system, including the gas source. The control system 920 can manage the flow rate of gases flowing through the respiratory system as they are delivered to the patient. For example, the control system 920 can increase or decrease the flow rate by controlling the motor speed output of a blower (also referred to hereinafter as a "blower motor") 930 or the output of a mixer valve 932. The control system 920 can automatically determine a set or personalized flow rate for a particular patient, as discussed below. The flow rate can be optimized by the control system 920 to improve patient comfort and therapy.

[0330] The control system 920 can generate audio 938 and / or display / visual output 939. For example, a flow therapy device can include a display and / or speaker. The display can indicate to the physician any warnings or alerts generated by the control system 920. The display can also indicate control parameters that the physician can adjust. For example, the control system 920 can automatically recommend a flow rate for a particular patient. The control system 920 can also determine the patient's respiratory status, including, but not limited to, generating the patient's respiratory rate, and send that to a display, which will be described in more detail below.

[0331] The control system 920 can vary the heater control outputs to control one or more of the heating elements (e.g., to maintain a temperature setpoint for the gas delivered to the patient). The control system 920 can also vary the operation or duty cycle of the heating elements. The heater control outputs can include a heater plate control output 934 and a heated breathing tube control output 936.

[0332] The control system 920 can determine outputs 930-939 based on one or more received inputs 901-916. The inputs 901-916 can correspond to sensor measurements automatically received by the controller 600 (shown in FIG. 19B ). The control system 920 can receive sensor inputs including, but not limited to, a temperature sensor input 901, a flow sensor input 902, a motor speed input 903, a pressure sensor input 904, a gas fraction sensor input 905, a humidity sensor input 906, a pulse oximeter (e.g., SpO2) sensor input 907, stored or user parameters 908, a duty cycle or pulse width modulation (PWM) input 909, a voltage input 910, a current input 911, an acoustic sensor input 912, a power input 913, a resistance input 914, a CO2 sensor input 915, and / or a spirometer input 916. The control system 920 can receive input from a user or stored parameter values ​​in memory 624 (shown in FIG. 19B). The control system 920 can dynamically adjust the flow rate to the patient over the course of the patient's treatment. The control system 920 can continuously sense system parameters and patient parameters. Those skilled in the art will understand, based on the disclosure herein, that any other suitable inputs and / or outputs can be used with the control system 920.

[0333] controller FIG. 19B shows a block diagram of one embodiment of a controller 600 (which may be controller 13 of FIG. 1). The controller 600 may include programming instructions for detecting input states and controlling output states. The programming instructions may be stored in memory 624 of the controller 600. The programming instructions may correspond to the methods, processes, and functions described herein. The programming instructions may be executed by one or more hardware processors 622 of the controller 600. The programming instructions may be implemented in C, C++, JAVA, or any other suitable programming language. Some or all of the portions of the programming instructions may be implemented in application-specific circuitry 678, such as ASICs and FPGAs.

[0334] The controller 600 may also include circuitry 628 for receiving sensor signals. The controller 600 may further include a display 630 for communicating the status of the patient and the respiratory assistance system. The display 630 may also display warnings and / or other alerts. The display 630 may be configured to display the characteristics of the detected gas in real time or otherwise. The controller 600 may also receive user input via a user interface, such as a display 680. The user interface may include buttons or dials. The user interface may comprise a touch screen.

[0335] Motor / Sensor Module Any of the features of the respiratory system described herein, including but not limited to a humidification chamber, a flow generator, a user interface, a controller, and a patient respiratory conduit configured to couple a gas outlet of the respiratory system to a patient interface, can be combined with any of the sensor modules described herein.

[0336] Figure 20 shows a block diagram of a motor / sensor module 2000 that can be received by the recess 260 in the respiratory device (shown in Figures 17 and 18). The motor and sensor module can include a blower 2001 that draws in room air for delivery to the patient. The blower 2001 can be a centrifugal blower.

[0337] One or more sensors (e.g., Hall effect sensors) can be used to measure the motor speed of the blower motor. The blower motor can include a brushless DC motor from which the motor speed can be measured without using a separate sensor. For example, during operation of the brushless DC motor, back EMF can be measured from a non-powered winding of the motor, from which the motor position can be determined and used to calculate the motor speed. Additionally, a motor driver can be used to measure the motor current, which can be used with the measured motor speed to calculate the motor torque. The blower motor can include a low inertia motor.

[0338] Room air may enter room air inlet 2002 which enters blower 2001 through inlet port 2003. Inlet port 2003 may include valve 2004 through which pressurized gas may enter blower 2001. Valve 2004 may control the flow rate of oxygen (or other auxiliary gas) into blower 2001. Valve 2004 may be any type of valve, including a proportional valve or a binary valve. In some embodiments, the inlet port does not include a valve.

[0339] Blower 2001 can operate at motor speeds greater than 1,000 RPM and less than 30,000 RPM, greater than 2,000 RPM and less than 25,000 RPM, greater than 3,000 RPM and less than 24,000 RPM, or any value between the aforementioned values. The operation of blower 2001 mixes the gases entering blower 2001 through inlet port 2003. Because mixing requires energy, the use of blower 2001 as a mixer can reduce the pressure drop that would otherwise occur in a system with a separate mixer, such as a static mixer with baffles.

[0340] The mixed air can exit the blower 2001 through a conduit 2005 and enter a flow path 2006 in a sensor chamber 2007. Within the sensor chamber 2007, a sensing circuit board with sensors 2008 can be positioned so as to be at least partially immersed in the gas flow. At least some of the sensors 2008 on the sensing circuit board can be positioned within the gas flow to measure gas properties within the gas flow. After passing through the flow path 2006 in the sensor chamber 2007, the gas can exit (2009) to the humidification chamber 210.

[0341] Positioning the sensor 2008 downstream of the combined blower and mixer 2001 can improve the accuracy of measurements, such as measuring gas fraction concentrations, including oxygen concentration, compared to systems in which the sensor is positioned upstream of the blower and / or mixer. Such positioning can provide a repeatable flow profile. Furthermore, positioning the sensor downstream of the combined blower and mixer avoids the pressure drop that can occur if sensing occurs before the blower because a separate mixer, such as a static mixer with a baffle between the inlet and the sensing system, is required. A mixer can create a pressure drop across the mixer. Positioning sensing after the blower allows the blower to be the mixer, and a static mixer reduces pressure, as opposed to a blower increasing pressure. Additionally, immersing at least a portion of the sensing circuit board and sensor 2008 within the flow path can improve the accuracy of the measurement, as immersion of the sensor within the flow means that the sensor is subjected to the same conditions, such as temperature and pressure, as the gas flows, and is therefore more likely to provide a better representation of the characteristics of the gas flow.

[0342] Referring to FIG. 21 , gas exiting the blower can enter a flow path 402 in a sensor chamber 400, which can be positioned within the motor and sensor module and can be sensor chamber 2007 of FIG. 20 . The flow path 402 can have a curved shape. The flow path 402 can be configured to have a curved shape that does not have sharp turns. The flow path 402 can have curved ends and more linear sections between the curved ends. A curved flow path shape can reduce the pressure drop in the gas flow without reducing the sensitivity of the flow measurement by partially coinciding a measurement area with the flow path to form the measurement portion of the flow path, as will be described below with reference to FIGS. 23A and 23B .

[0343] Within the sensor chamber 400, a sensing circuit board 404 with sensors such as acoustic transmitters / receivers, humidity sensors, temperature sensors, thermistors, etc., can be positioned so that it is at least partially immersed within the flow path 402. Immersing the sensing circuit board and sensors at least partially within the flow path can improve the accuracy of measurements because sensors immersed in the flow are more likely to be subjected to the same conditions, such as temperature and pressure, as the gas flows and therefore provide a better representation of the characteristics of the gas flow. After the gas passes through the flow path 402 within the sensor chamber 400, it can exit to a humidification chamber.

[0344] At least two different types of sensors can be used to measure gas flow rates. The first type of sensor can include a thermistor, which can determine flow rate by monitoring heat transfer between the gas flow and the thermistor. A thermistor flow sensor can pass a thermistor at a constant target temperature within the flow as the gas flows around and past the thermistor. The sensor can measure the amount of power required to maintain the thermistor at the target temperature. The target temperature can be configured to be higher than the temperature of the gas flow, such that higher flow rates require more power to maintain the thermistor at the target temperature.

[0345] The thermistor flow sensor can also maintain multiple (e.g., two, three, or more) constant temperatures at the thermistor to avoid too small or too large a difference between the target temperature and the gas flow temperature. Multiple different target temperatures allow the thermistor flow sensor to be accurate over a wide temperature range of the gas. For example, the thermistor circuit can be configured to switch between two different target temperatures so that the temperature of the gas flow is always within a certain range (e.g., not too close or too far) of one of the two target temperatures. The thermistor circuit can be configured to operate at a first target temperature of about 50°C to about 70°C, or about 66°C. The first target temperature can be associated with a desired flow temperature range of about 0°C to about 60°C, or about 0°C to about 40°C. The thermistor circuit can be configured to operate at a second target temperature of about 90°C to about 110°C, or about 100°C. The second target temperature can relate to a desired flow temperature range of about 20°C to about 100°C or about 30°C to about 70°C.

[0346] The controller can be configured to adjust the thermistor circuit to vary between at least a first target temperature mode and a second target temperature mode by connecting or bypassing a resistor in the thermistor circuit. The thermistor circuit can be arranged in a Wheatstone bridge configuration with a first voltage divider arm and a second voltage divider arm. The thermistor can be located in one of the voltage divider arms. More details of the thermistor flow sensor are described in PCT Application No. PCT / NZ2017 / 050119, filed September 3, 2017, which is incorporated herein by reference in its entirety.

[0347] A second type of sensor can include an acoustic sensor assembly. Acoustic sensors, including acoustic transmitters and / or receivers, can be used to measure the time-of-flight of acoustic signals to determine gas velocity and / or composition, which can be used in flow therapy devices. In one ultrasonic sensing topology (including an ultrasonic transmitter and / or receiver), a driver causes a first sensor, such as an ultrasonic transducer, to generate an ultrasonic pulse in a first direction. A second sensor, such as a second ultrasonic transducer, receives the pulse and provides a measurement of the time-of-flight of the pulse between the first and second ultrasonic transducers. This time-of-flight measurement can be used by a processor or controller in the respiratory system to calculate the speed of sound in the gas flow between the ultrasonic transducers. A second sensor transmits a pulse in a second direction opposite the first direction and is received by the first sensor to provide a second measurement of the time-of-flight, allowing a characteristic of the gas flow, such as flow rate or velocity, to be determined. In another acoustic sensing topology, acoustic pulses transmitted by an acoustic transmitter, such as an ultrasonic transducer, can be received by an acoustic receiver, such as a microphone. More details of the acoustic flow sensor are described in PCT Application No. PCT / NZ2016 / 050193, filed December 2, 2016, which is incorporated herein by reference in its entirety.

[0348] Readings from both the first and second type sensors can be combined to determine a more accurate flow measurement. For example, a predetermined flow rate and one or more outputs from one of the types of sensors can be used to determine a predicted current flow rate. The predicted current flow rate can then be updated using one or more outputs from the other of the first and second type of sensors to calculate a final flow rate.

[0349] Patient detection process example As mentioned above, when a patient breathes through their nose into the patient interface of the respiratory system, a respiratory signal is detected in the flow rate or other flow parameter due to flow resistance variations caused by inhalation and exhalation. The patient may be disconnected from the respiratory system so that there is no respiratory signal in the gas flow parameter.

[0350] It may be advantageous for the respiratory system to be able to determine whether a patient is connected or disconnected, such as using the patient connection determination to help the controller determine whether the dominant frequency of a frequency analysis of gas flow parameters is respiratory rate. Patient disconnection detection may have other applications, which are described in more detail below. In addition to determining whether a patient is connected or disconnected from a respiratory system, it may also be useful to know whether the patient was previously connected to a respiratory device and is in the process of disconnecting from the respiratory device, or was previously disconnected from the respiratory device and is in the process of connecting to the respiratory device.

[0351] The process disclosed herein evaluates time domain features of flow parameter data to determine whether the patient is connected or disconnected. Additionally, the process can classify the patient connection status into one of four categories: disconnected, connecting, or connected or disconnected.

[0352] The flow rate or other gas flow parameter signal may be provided through a pre-processing step that allows the controller to determine whether the gas flow parameter is suitable for use in determining patient connection and / or remove certain features from the flow parameter so that the flow parameter signal provided to the patient connection detection process better represents any effect that the patient's breathing is having on the gas flow parameter (flow rate, pressure, etc.). Details of the pre-processing step are described in more detail below with reference to Figures 23A-23D.

[0353] Instantaneous and filtered feature determination As discussed above, when a patient is connected to a respiratory system and breathing through a patient interface, fluctuations in the preprocessed flow rate or other flow parameter data are assumed to consist of random, uncorrelated noise and correlated respiratory signals generated by the patient. As shown in Figure 22, the process may begin in step 2202 with the controller receiving flow parameter data (e.g., raw data). In decision step 2204, the controller may perform a preprocessing step, for example, by determining whether the flow parameter data is suitable or suitable for use. If the data is not suitable for use, the controller may discard the data in step 2206 and return to step 2202.

[0354] 23A-23C illustrate an example process for determining data suitability. The flow parameter may be a flow rate. The flow parameter may also be a pressure or other type of parameter disclosed herein. The flow parameter data may be an absolute value of the gas flow parameter. Alternatively, the flow parameter data may be a change in the gas flow parameter. The change may be determined by subtracting a target value for the gas flow parameter from a measured value of the gas flow parameter. The change may also be determined by subtracting an estimated effect of a second gas flow parameter from a measured value of a first gas flow parameter. The change may be calculated after determining that the flow parameter data is suitable for use. In one configuration, the change may also be calculated before determining that the flow parameter data is suitable for use.

[0355] As shown in FIG. 23A , in step 2322, the controller may receive second flow parameter data, which is a different type than the first flow parameter data, such as the flow parameter data received in step 2202 of FIG. 22 . The second parameter is estimated to have an effect on the first parameter. For example, motor speed, pressure, and / or oxygen flow rate or concentration may have an effect on the gas flow rate that is separate from the effect of the patient's breathing on the gas flow rate. In decision step 2324, the controller may determine whether the estimated effect is valid. For example, the estimated effect may be valid if it is greater than a minimum threshold. If the estimated effect is not valid, such as because it is below a minimum threshold, it may be difficult to accurately predict the effect of the second parameter on the first parameter. Thus, in step 2328, the controller may determine that the first parameter data, which may be the flow parameter data received in step 2202 of FIG. 22 , is not suitable for use and may discard the first parameter data. If the expected effect is valid, such as by being greater than a minimum threshold, then in step 2326 the controller may determine that the first parameter data is suitable for use.

[0356] In the processes of Figures 23B and 23C, the first parameter can include flow data, and the second parameter can include motor speed, oxygen flow rate, and / or oxygen concentration. In some configurations, the processes of Figures 23B and 23C can be implemented together to determine whether the flow parameter data is suitable for use. In step 2340 of Figure 23B, the controller can receive motor speed data. The motor must be running at a sufficient speed to identify patient breaths in the flow data. If the motor speed is too low, the effect of the motor speed on the flow data (e.g., flow rate data) may not be accurately predicted. Therefore, in step 2342, the controller can compare the motor speed to a minimum motor speed threshold. If the motor speed is below the threshold, in step 2344, the controller can deem the flow parameter data inappropriate and can discard some or all of the flow parameter data. If the motor speed is above the threshold, in step 2346, the controller can calculate a recent change in motor speed. Changes in motor speed can result in changes in flow parameters, making it more difficult to identify patient breaths in the flow parameter data. While the effects of motor speed can be removed to some extent from the flow parameter data, larger changes in motor speed can make the data too unreliable for identifying patient breaths. Therefore, in step 2348, the controller can apply a movement filter to the relative change in motor speed to generate a first value representing the recent relative change in motor speed. In decision step 2350, the controller can compare the first value to a first threshold. If the first value is above the first threshold, the controller can consider the flow parameter value to be inadequate and can discard the flow data point in step 2344. If the first value is below the first threshold, the controller can consider the flow parameter value to be suitable in step 2345.

[0357] Flow parameters (e.g., flow rate) can also be affected by the flow rate or concentration of supplemental gas from a supplemental gas source, such as oxygen from a supplemental oxygen source. While FIG. 23C uses oxygen as an example, the steps performed with respect to the flow rate or concentration of oxygen can also be performed for the flow rate or concentration of any other supplemental gas mixed with ambient air. In step 2352, the controller can receive oxygen flow rate data or oxygen concentration data. In step 2354, the controller can calculate a recent change in oxygen flow rate or oxygen concentration. If the oxygen flow rate or concentration changes, the resulting change in total flow can make it more difficult to identify patient breaths in the flow signal or other flow parameter signal. Therefore, in step 2356, the controller can apply a movement filter to the change in oxygen concentration of the gas or oxygen flow rate to generate a second value representing a recent change in oxygen concentration or flow rate. In decision step 2358, the controller can compare the second value to a second threshold. If the second value is greater than the second threshold, the controller can determine that the flow parameter value is inappropriate and perform step 2359. 2360 If the second value is less than the threshold, the flow parameter data point may be discarded in step 2362 At this point, the controller may consider the flow parameter data to be suitable.

[0358] Either oxygen (or other supplemental gas) concentration data or oxygen (or other supplemental gas) flow rate data can be used for the above determination. Oxygen concentration data can be determined using one or more sensors in the breathing device, such as an ultrasonic sensor. The oxygen flow rate from the oxygen source can be determined by an oxygen flow rate sensor located downstream of the oxygen source.

[0359] As mentioned above, if the controller deems the data suitable, it may also modify the flow rate (or any other flow parameter data) to remove the influence of the motor (or other factors, such as oxygen concentration or flow rate). Modifying the gas flow parameters may include removing the assumed influence of other variables (such as motor speed) from the gas flow parameters. This assumed influence is only valid if the gas flow parameter data meets certain criteria. As mentioned above, if these criteria are not met, the data may be discarded.

[0360] 23D shows an example process for correcting flow data to remove the effects of motor speed. The effects of the motor can be estimated using the motor speed and flow conductance. In step 2380, the controller can measure the instantaneous flow conductance. Flow conductance is approximately constant over time and therefore can be estimated using a low-pass filter. The controller measures the instantaneous flow conductance at each iteration using the current motor speed and the measured flow rate. In step 2382, the controller filters the instantaneous flow conductance to obtain a filtered flow conductance.

[0361] At decision step 2384, the controller can compare the instantaneous flow conductance to the filtered flow conductance to determine if the difference is significantly different. If the difference is significant, something may have changed the physical system, such as a cannula being attached or removed. At decision step 2386, the instantaneous flow conductance can be compared to the filtered flow conductance by taking the difference between the two variables and comparing it to a minimum threshold. If the difference exceeds the threshold, the difference is deemed significant, and the controller can reset the filtered flow conductance at step 2388. Resetting allows the device to quickly adjust its estimate of flow conductance when a cannula is attached and removed from a patient.

[0362] In step 2390, the controller may also modify the filter coefficients of the filtered flow conductance calculation based on the difference between the instantaneous flow conductance and the filtered flow conductance, allowing the filtered flow conductance to change more quickly when there is high variability in the flow conductance, such as when the cannula is first installed. The controller may then return to step 2380 to begin a new iteration of the process.

[0363] If the difference does not exceed the threshold, the difference is deemed not significant and the controller may estimate the motor's effect on flow in step 2392. The controller may use the filtered flow conductance and motor speed to output an effect value. That value may be subtracted or otherwise removed from the flow data in step 2394 to arrive at preprocessed flow data. The preprocessed flow data may more accurately represent the patient's respiratory flow (although the preprocessed flow data may still contain signal noise).

[0364] The controller may also track recent changes in flow conductance. The changes may be tracked by adding the difference between at least two instantaneous flow conductance values ​​to a cumulative sum that decays over time. The decaying cumulative sum is filtered to obtain a filtered recent change in flow conductance. The filtered recent change in flow conductance may be used with the preprocessed flow data in a further portion of the frequency analysis algorithm.

[0365] Returning to FIG. 22 , if the flow parameter data is suitable for use, then in step 2208 the controller can evaluate the instantaneous characteristics of the recent data, which can be done by analyzing whether there is a trend in the recent data. The time scale of the recent data can be fixed, for example, at less than the minimum predicted or typical breathing period, preferably between the minimum predicted or typical breathing period and one-quarter of the minimum predicted or typical breathing period, or between half the minimum predicted or typical breathing period and one-quarter of the minimum predicted or typical breathing period, or preferably less than half the minimum predicted or typical breathing period, or more preferably less than one-quarter of the minimum predicted or typical breathing period. The evaluation can be done using two vectors, and the instantaneous characteristics are a measure of how well the recent data points correlate to one of the two vectors or a combination thereof. The evaluation can also be done using a single vector or three or more vectors.

[0366] When the patient is not breathing through the patient interface, random fluctuations in the preprocessed flow data may be less correlated with one or both of the two vectors than when the patient is breathing through the patient interface. Furthermore, higher frequency data may be less correlated than lower frequency data because the period of data being evaluated has multiple oscillations of the higher frequency. Signals that may result in higher correlations (and therefore more instantaneous features) are low frequency signals, such as the patient's breathing signal.

[0367] FIG. 24 shows an example of the instantaneous feature when various frequencies of data (which may include a sine wave) are evaluated (without signal noise). The shaded area 2402 represents the possible values ​​of the instantaneous feature (due to different phases of the sine wave). The solid line 2404 shows the average of the instantaneous feature for that frequency. Continuing with FIG. 22, at decision step 2210, the controller determines whether the instantaneous feature exceeds a certain instantaneous feature threshold. In the configuration shown in FIG. 24, the threshold is shown as dotted line 2406.

[0368] In one configuration, 60 min -1 Sine waves with frequencies less than 1 may have instantaneous features close to 1. This frequency may be largely correlated to the typical respiratory frequency of a patient, such as an adult patient. Respiratory signals can be decomposed into a fundamental (respiratory) frequency and harmonics. The harmonics typically decrease in magnitude with harmonic order (e.g., the first harmonic has a smaller frequency amplitude than the fundamental frequency, the second harmonic has a smaller frequency amplitude than the first harmonic). All of these harmonics contribute to the instantaneous feature with the highest amplitude, i.e., the fundamental frequency amplitude that exerts the most influence. In some configurations, the threshold may be lower than 1 (such as about 0.4 in FIG. 24), thereby providing a 60-120 min -1may also exceed that threshold. These frequencies may still be caused by the patient's breathing, especially in the case of an infant. The relatively high frequencies mentioned above typically do not produce instantaneous features that exceed the threshold.

[0369] 22, if the instantaneous feature exceeds the threshold, the controller can output that a breath is detected or that the patient is connected in step 2212. If the instantaneous feature does not exceed the threshold, the controller can output that a breath is not detected or that the patient is disconnected in step 2214.

[0370] An instantaneous feature exceeding an instantaneous feature threshold may indicate that a breathing patient is connected to a patient interface (such as by being connected to a cannula). Additionally, to reduce signal noise that causes fluctuations in the instantaneous features, the instantaneous features may be filtered before using them to determine the patient connection status of the respiratory system.

[0371] As shown in Figure 25A, two filters can be applied to the instantaneous features in the process of obtaining the filtered features. The process can begin in step 2502 with the controller receiving flow parameter data (e.g., raw data). In decision step 2504, the controller can perform pre-processing steps, such as by determining whether the flow parameter data is suitable or suitable for use. If the data is not suitable for use, the controller can discard the data in step 2506 and return to step 2502. If the data is suitable for use, in step 2508, the controller can evaluate the instantaneous features of the data.

[0372] In step 2510, the controller may apply two different filters to the instantaneous feature to generate a main filtered feature and a short filtered feature, respectively. In step 2512, the controller may use the short filtered feature to determine filter coefficients for the main filtered feature. In step 2514, the filtered feature may be used to determine patient connection status, as shown in FIG. 25B. The application of two filters allows the main filtered feature to change more quickly as the instantaneous feature approaches 1, thereby allowing a faster patient connection decision when there is a strong respiratory signal. Furthermore, when the patient is not breathing through the patient interface (e.g., cannula), the instantaneous feature drops toward 0, thereby increasing the filter coefficient for the main filtered feature and causing the main filtered feature to change more slowly, thereby slowing down the patient connection decision. The controller may take a relatively long time to determine that the patient is disconnected (than when the patient is connected and breathing through the patient interface), but may take a relatively short time to determine that the patient is connected.

[0373] It is preferable to erroneously determine that a patient is connected to a breathing system when the patient is not, rather than erroneously determine that a patient is disconnected when the patient is still connected to the system. This is because, in part, several algorithms that control the flow rate and / or motor speed of a breathing device depend on a connected patient to function. Erroneously determining that a patient is disconnected can prevent these algorithms from functioning when necessary. This can prevent the device from synchronizing the patient's breathing with the delivery of gas and / or reduce the effectiveness of respiratory therapy. Furthermore, erroneously determining that a patient is disconnected can cause discomfort to a patient who is still connected to the patient interface due to an incorrect flow rate and / or motor speed.

[0374] As shown in FIG. 26 , the flow parameter data can be subjected to a process that derives a measure of patient ventilation and a measure of total signal variability. Similar to other processes described herein, this process can begin with the controller receiving flow parameter data (which can include raw data for the first or second parameter) in step 2602. The flow parameter can be a flow rate or a parameter indicative of a flow rate. In one configuration, flow rate can refer to total flow rate, including respiratory flow rate, supplemental gas flow rate, etc. In one configuration, the flow parameter can be a direct measure of gas flow. The flow parameter can be a pressure, motor speed, or other type of parameter disclosed herein. The flow parameter can be a parameter that is a measure of or indicative of pressure, motor speed, or other type of parameter disclosed herein. The flow parameter can represent the performance of a device component. In decision step 2604, the controller can perform a preprocessing step, such as by determining whether the flow parameter data is suitable or suitable for use. If the data is not suitable for use, the controller can discard the data in step 2606 and return to step 2602.

[0375] If the data is suitable for use, in step 2608, the controller may generate flow parameter change data. The flow parameter change data may be determined by subtracting a target value of the flow parameter data from the measured value of the flow parameter data. The flow parameter change data may be determined by subtracting an estimated effect of a second parameter from the measured value of the first parameter. In one configuration, the first flow parameter or first parameter is a gas flow rate or a parameter indicative of gas flow rate. In one configuration, the second flow parameter or second parameter is a pressure, motor speed, or another flow measure or parameter indicative thereof. The estimated effect of the second parameter on the first parameter may be a change in flow rate that can be predicted based on a current value of the second parameter, such as the current motor speed. This estimated effect may assume no noise or patient interaction. The estimated effect may be calculated using a moving average of the relationship between motor speed and flow rate along with the current value of the second parameter, such as the current motor speed, which may be used to characterize the relationship between the first and second flow parameters. In one configuration, the flow parameter change data can be determined by subtracting a first average value of the flow parameter data from a second average value of the flow parameter data. The first average value can be later in time than the second average value. The first average value can also be based on a window of data that is longer than the second average value. In one configuration, the second average value can be based on a window of data that is longer than the first average value. The windows of data can be mutually exclusive in time or overlapping in time. The windows of data can relate to the same or different lengths of time. The first average value of the flow parameter data can be determined by applying a filter or an ongoing filter to the flow parameter data. The first average value of the flow parameter data can be constantly or continuously updated. The second average value can be based on measurements. The flow parameter change data can be calculated after determining that the flow parameter data is suitable for use. In one configuration, the flow parameter change data can be calculated before determining that the flow parameter data is suitable for use.

[0376] In step 2610, the controller selects a portion of the flow parameter change data for analysis. The portion of the flow parameter change data selected may be the most recently measured flow parameter change data or flow parameter change data measured simultaneously or closely in time for analysis. The portion of the flow parameter change data may relate to a period within a predefined time period. The portion may be selected to obtain a data set representing or relating to a predetermined length of time. Selecting a portion of the processed flow parameter data relating to a longer period ensures that more noise is filtered out of the processed flow parameter data compared to selecting a portion of the processed flow parameter data relating to a shorter period of time. However, selecting a portion of the processed flow parameter data relating to a longer period of time may result in filtering out relatively high frequency respiratory signals compared to selecting a portion of the processed flow parameter data relating to a shorter period of time. Thus, when selecting a portion of the processed flow parameter data representing a length of time, there may be a trade-off between filtering out noise and detecting or capturing momentary changes. In one configuration, it may be advantageous to select a portion of the processed flow parameter data representing a length of time shorter than a respiratory period. In one configuration, selecting a portion of the processed flow parameter data representing a range of 0.5 to 2 seconds can provide reliability in detecting patient interaction or connection (along with talking, coughing, etc.) for most expected breathing frequencies while being long enough to reduce the likelihood of an erroneous determination of patient connection or interaction due to random noise. In one configuration, the selected portion of the processed flow parameter data can be less than 0.5 seconds, 0.5 to 1, 1 to 1.5, 1.5 to 2, 2 to 2.5, 2.5 to 3, 3 to 3.5, 3.5 to 4, 4 to 4.5, 4.5 to 5, 5 to 5.5, 5.5 to 6 seconds, or greater than 6 seconds.

[0377] In one configuration, the controller selects a portion of the processed flow parameter data before generating the flow parameter change data in step 2608. In one configuration, the controller selects a portion (or window) of the processed flow parameter data that corresponds to a predetermined length of time such that signal noise is filtered out from the measure of instantaneous patient ventilation described below. In one configuration, the controller selects a portion of the processed flow parameter data that corresponds to a predetermined length of time such that predicted breathing frequencies, which may include all predicted breathing frequencies, will result in an increase in the measure of instantaneous patient ventilation.

[0378] In step 2612, the controller fits one or more functions to the selected portion of the flow parameter change data. The one or more functions may be algebraic functions, such as polynomials (e.g., constant, linear, nonlinear, quadratic, cubic, etc.), rational, square root, etc. The one or more functions may be transcendental functions, such as exponential, hyperbolic, logarithmic, power, periodic (e.g., trigonometric, etc.). The controller may implement various line and / or curve fitting techniques to fit one or more functions to the selected portion of the flow parameter change data, which may include, but are not limited to, regression analysis, interpolation, extrapolation, linear least squares, nonlinear least squares, total least squares, linear simple linear regression analysis, robust linear simple linear regression analysis, polynomial regression, orthogonal regression, Deming regression, linear segmented regression, and regression dilution. The one or more functions, including at least those listed above, may generate a curve. The curve may be a line. Lines or curves described herein may include multiple curvatures, vertices, and / or other features. Lines described herein may be straight, angled, and / or horizontal. Lines described herein may be best fit lines.

[0379] In one configuration, the controller may perform a least squares fit of a line, which may include fitting a linear function, such as a straight line, to a selected portion of the flow parameter change data. For example, the line may be

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[0380] In step 2614, the controller generates a measure of patient ventilation. The measure of patient ventilation may be primarily related to patient ventilation, but may include some noise. The controller may generate a measure of instantaneous patient ventilation, also referred to as a flow volume parameter or volume measurement, in step 2612 by determining the area under a function fit to a selected portion of the flow parameter change data. In one configuration, the controller may generate a measure of instantaneous patient ventilation in step 2612 by determining the area under a curve generated by a function fit to the flow parameter change data. In one configuration, the controller may generate a measure of instantaneous patient ventilation in step 2612 by determining the area under one or more functions or the absolute value of the curve generated by the one or more functions. This may be determined in step 2612 by taking the integral of the one or more functions or the absolute value of the curve generated by the one or more functions. In one non-limiting example, this is represented by the equation shown below:

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[0381] A measure of instantaneous patient ventilation (V) is used to represent patient minute ventilation. O ) can be multiplied by 1 minute. The measure of instantaneous patient ventilation can be filtered over time to generate a measure of patient ventilation that can be used to determine patient connection. The measure of patient ventilation can be a measure of volume. The measure of patient ventilation can be

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[0382] In step 2616, the controller generates a measure of total signal variability. The measure of total signal variability may include noise contributed by respiratory system electronics, signal noise, environment, patient respiration, patient ventilation, patient movement, and / or other noise that may or may not originate from the patient. The controller may generate a measure of instantaneous total signal variability from the flow parameter change data generated in step 2608. The controller may generate a measure of instantaneous total signal variability, which may also be described as variability or average variability, by taking the absolute value of the flow parameter change data. In one non-limiting example, this is expressed in the following equation:

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[0383] In one configuration, instead, each data point relative to the offset can be made positive by taking the square of the flow parameter change data. However, taking the square of the flow parameter change data can result in incorrect patient connection decisions due to random outliers in the flow parameter change data. Utilizing absolute values ​​can be more tolerant to outliers in the flow parameter change data, which can result from coughing, yawning, etc. A measure of the instantaneous total signal fluctuation (V short ) to V O The instantaneous total signal variation measure can be viewed as representing the total variation in the flow parameter variation data resulting from both the patient signal and random noise.

[0384] V O Similarly, a measure of the total instantaneous signal fluctuation (V short ) can be filtered over time to generate a measure of total signal variability to facilitate determination of patient connectivity. The measure of total signal variability is

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[0385] Determining Connection Status As shown in FIG. 25B, the controller can use the filtered features described above to determine four categories of patient connectivity status: whether the patient is disconnected from the breathing system, connecting to the breathing system, connected, or disconnecting from the breathing system. This assessment can be made by comparing the primary filtered features to one or more feature thresholds (such as thresholds close to or slightly less than 1, as described above). To reach a determination that the patient is connected or disconnected, the primary filtered features must be above or below the threshold. The threshold can be determined by further analyzing recent changes in the primary filtered features, sums calculated prior to recent changes in flow conductance, and / or the value of the features when the signal contains pure noise, i.e., the known value of the feature when the patient is not connected.

[0386] At decision step 2530, the controller may determine whether the patient was previously connected to or is in the process of being disconnected (i.e., still connected) to the respiratory system. If the patient was not previously connected or disconnecting, i.e., the patient is disconnected or connected, then at step 2542, the controller may determine whether the predominant filtered feature is greater than a first threshold or the patient has been connected for a predetermined amount of time. If the predominant filtered feature is greater than the first threshold or the patient has been connected to the respiratory system for at least a predetermined amount of time, then at step 2550, the controller may determine that the patient is connected to the respiratory system.

[0387] If the primary filtered feature is less than or equal to the first threshold and / or the patient has not been connected to the respiratory device for at least a predetermined amount of time, the controller may determine whether the primary filtered feature is greater than a second threshold that is lower than the first threshold in step 2544. If the primary filtered feature is less than the second threshold, the controller may determine that the patient is disconnected in step 2546. If the primary filtered feature is greater than the second threshold but less than or equal to the first threshold (i.e., between the first and second thresholds), the controller may determine that the patient is connected to the respiratory system in step 2548.

[0388] If the patient was previously connected or is disconnecting, the controller may determine whether the predominant filtered feature is below a third threshold or the patient has been in the process of disconnecting for a predetermined amount of time in step 2532. If the predominant filtered feature is below the third threshold or the patient has been disconnecting for a predetermined amount of time, the controller may determine that the patient is disconnected in step 2543.

[0389] If the primary filtered feature is greater than or equal to the third threshold and / or the patient has not been disconnected for a predetermined amount of time, the controller may determine whether the primary filtered feature is less than a fourth threshold that is greater than the third threshold in step 2536. If the primary filtered feature is less than the fourth threshold but greater than or equal to the third threshold (i.e., between the third and fourth thresholds), the controller may determine in step 2538 that the patient is disconnecting from the respiratory system. If the primary filtered feature is greater than or equal to (or higher than) the fourth threshold, the controller may determine in step 2540 that the patient is connected.

[0390] The first threshold and the fourth threshold may be the same or different (e.g., the fourth threshold may be lower than the first threshold). The second threshold and the fourth threshold may be the same or different (e.g., the fourth threshold may be lower than the second threshold). The absolute values ​​of the difference between the first threshold and the second threshold and the difference between the third threshold and the fourth threshold may be the same or different.

[0391] The process shown in Figure 25B ensures that the controller does not determine that a patient is connected or disconnected based on the primary filtered feature temporarily exceeding the threshold by a small amount, for example, by determining that the patient is still in the process of connecting to or disconnecting from the respiratory system. If the primary filtered feature exceeds the threshold, but not by a significant amount, the patient is determined to be connected or disconnected. Furthermore, if the patient is determined to be connected or disconnected for a certain amount of time, the determination can switch to a determination that the primary filtered feature is connected or disconnected without the primary filtered feature having to be significantly above or below the feature threshold.

[0392] As shown in FIG. 27, the controller may use the measure of patient ventilation generated above with reference to FIG. 26.

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[0393] In one configuration, a measure of instantaneous patient ventilation (V O ) and a measure of total signal variability (Vshort ) are similar, the controller can determine that the majority of the signal change is caused by the patient and therefore the patient is connected or coupled. In one configuration, a measure of instantaneous patient ventilation (V O ) and a measure of total signal variability (V short ) are significantly different (for example, V short >>V O , the controller can determine that the majority of the signal variations are caused by random noise and therefore the patient is not connected or coupled.

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[0394] The patient coupling measure (σ) can be determined, in part, through the use of correction factors. Correction factors are used to account for two or more measures of instantaneous patient ventilation (V), each calculated in a different way. O ) can be determined by comparing the correction factors. Correction factors can be used to compare two or more measures of patient ventilation, each calculated differently.

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[0395] When the signal-to-noise ratio (SNR) is zero, the patient connectivity measure (σ) may be zero. As the signal-to-noise ratio (SNR) approaches zero, the patient connectivity measure (σ) may approach zero. When the signal-to-noise ratio (SNR) is infinite, the patient connectivity measure (σ) may be one. As the signal-to-noise ratio (SNR) approaches infinity, the patient connectivity measure (σ) may approach one. The patient connectivity measure (σ) may be used to determine patient connectivity by comparing the patient connectivity measure (σ) to one or more thresholds. Alternatively, the controller may determine whether the patient is connected to the breathing system by comparing the patient connectivity measure, the correction factor, any measure of patient minute ventilation, or any combination thereof, to a predetermined threshold. This combination may be based on an average value or any weighted average value. The correction factor and / or the measure of minute ventilation tend to be zero when the patient is disconnected and should therefore exceed a certain threshold if the patient is connected to the breathing system.

[0396] 27, the controller may determine whether the patient was previously connected to or disconnected from the respiratory system at decision step 2702. If the patient was previously disconnected, at step 2704 the controller may determine whether the patient was previously connected to or disconnected from the respiratory system, for example, a measure of patient ventilation.

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[0397] In one configuration, the connection threshold may be set to a value corresponding to a signal-to-noise ratio of 33%. In one configuration, the connection threshold may be set to a value corresponding to a signal-to-noise ratio below or above 33%. In one configuration, in step 2704, the controller may determine whether the patient connection measure (σ) continuously exceeds the connection threshold or another threshold for a set period of time. This period may be such that a short period of data, such as a few seconds, will decay, such as by about 80% by the end of the period. This may advantageously prevent a few seconds of erroneous data from resulting in an erroneous determination of patient connection.

[0398] If the patient was previously connected, then in step 2710, the controller may determine whether the patient connectivity measure (σ) is below a disconnection threshold. If the patient connectivity measure (σ) is below the disconnection threshold, then the controller determines that the patient is disconnected in step 2714. If the patient connectivity measure (σ) is not below the disconnection threshold, then the controller determines that the patient is connected in step 2712. The disconnection threshold is below the connection threshold. The disconnection threshold may be set to a value that can reliably assume that changes are caused solely by random noise. In one configuration, in step 2710, the controller may determine whether the patient connectivity measure (σ) is below the disconnection threshold continuously for a set period of time. This period may be such that a short period of data, such as a few seconds, will decay by the end of the period. This may advantageously prevent a few seconds of erroneous data from resulting in an erroneous determination of patient connectivity.

[0399] As shown in Figure 28, the controller can use the patient connectivity measure (σ) described above to determine four categories of patient connectivity status: whether the patient is disconnected from the respiratory system, connecting to the respiratory system, connected, or disconnecting from the respiratory system. This evaluation can be made by comparing the patient connectivity measure (σ), also referred to as a ratio, to one or more thresholds. To reach a determination that the patient is connected or disconnected, the patient connectivity measure (σ) must be above or below the threshold.

[0400] In decision step 2830, the controller may determine whether the patient was previously connected to the respiratory system or is in the process of being disconnected (i.e., still connected). If the patient was not previously connected or disconnecting, i.e., the patient is disconnected or connected, then in step 2842, the controller may determine whether the patient connectivity measure (σ) is greater than a first threshold or the patient has been connected for a predetermined amount of time. If the patient connectivity measure (σ) is greater than the first threshold or the patient has been connected to the respiratory system for at least a predetermined amount of time, then in step 2850, the controller may determine that the patient is connected to the respiratory system.

[0401] If the patient connectivity measure (σ) is less than or equal to the first threshold and / or if the patient has not been connected to the breathing system for at least a predetermined amount of time, then in step 2844 the controller may determine whether the patient connectivity measure (σ) is greater than a second threshold that is lower than the first threshold. Patient connectivity scale (σ) If σ is less than the second threshold, the controller may determine that the patient is disconnected in step 2846. If the patient connectivity measure (σ) is greater than the second threshold but less than or equal to the first threshold (i.e., between the first and second thresholds), the controller may determine that the patient is connected to the respiratory system in step 2848.

[0402] If the patient was previously connected or is disconnecting, the controller may determine whether the patient connectivity measure (σ) is below a third threshold or the patient has been in the process of disconnecting for a predetermined amount of time in step 2832. If the patient connectivity measure (σ) is below the third threshold or the patient has been disconnecting for a predetermined amount of time, the controller may determine that the patient is disconnected in step 2834.

[0403] If the patient coupling measure (σ) is greater than or equal to the third threshold and / or the patient has not been disconnected for a predetermined amount of time, then in step 2836 the controller may determine whether the patient coupling measure (σ) is less than a fourth threshold that is greater than the third threshold. If the patient coupling measure (σ) is less than the fourth threshold but greater than or equal to the third threshold (i.e., between the third and fourth thresholds), then in step 2838 the controller may determine that the patient is disconnecting from the respiratory system. If the patient coupling measure (σ) is greater than or equal to (or higher than) the fourth threshold, then in step 2840 the controller may determine that the patient is connected.

[0404] The first threshold and the fourth threshold may be the same or different (e.g., the fourth threshold may be lower than the first threshold). The second threshold and the fourth threshold may be the same or different (e.g., the fourth threshold may be lower than the second threshold). The absolute values ​​of the difference between the first threshold and the second threshold and the difference between the third threshold and the fourth threshold may be the same or different.

[0405] 28 ensures that the controller does not determine that a patient is connected or disconnected based on the patient connectivity measure (σ) temporarily exceeding a threshold by a small amount, for example, by determining that the patient is still in the process of connecting to or disconnecting from the respiratory system. If the patient connectivity measure (σ) exceeds the threshold, but not by a significant amount, the patient is determined to be connected or disconnected. Furthermore, if the patient is determined to be connected or disconnected for a certain amount of time, the determination can switch to a determination of connected or disconnected without the patient connectivity measure (σ) having to be significantly above or below the characteristic threshold.

[0406] The systems and methods described with reference to Figures 27 and 28 may be more reliable for determining patient connection than the systems and methods described with reference to Figures 25A and 25B.

[0407] Generating a proxy measure of patient ventilation The controller measures the patient ventilation.

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[0408] The function used can be generated through machine learning by utilizing the measures detailed herein together with actual measures of patient ventilation.

[0409] The surrogate measure of patient ventilation (V) can be related to the actual patient minute ventilation as well as other factors, such as the flow path and / or flow limitation profile in the breathing system, such as between the cannula and the patient's nose. In one configuration, the actual patient minute ventilation cannot be calculated from the surrogate measure of patient ventilation (V) alone and requires measures of factors. In one configuration, the surrogate measure of patient ventilation (V) can be converted to or approximated to the actual patient minute ventilation along with other factors, such as the flow path, flow limitation profile, and / or other factors in the breathing system. Changes in the surrogate measure of patient ventilation (V) can be correlated to actual changes in actual patient minute ventilation for the same patient using the same nasal cannula. Thus, trends in the surrogate measure of patient ventilation (V) can be used to indicate similar trends in the patient's actual minute ventilation. Furthermore, the determination of patient connection can be incorporated by analyzing trends in minute ventilation, whereby trends in minute ventilation are assessed using only the surrogate measure of patient ventilation (V) corresponding to the period during which the patient was determined to be connected. A surrogate measure of patient ventilation (V) can have additional applications that aid in the efficient use of the respiratory system.

[0410] Application example of breath detection process Determining whether a patient is connected to a patient interface can inform the accuracy of respiratory rate determination and / or for other purposes, one of which is for the process of adherence tracking. Adherence tracking is an important element for measuring patient compliance, particularly for insurance claims purposes. Adherence tracking is part of compliance measurement that informs users, clinicians, insurance companies, etc., whether a patient is connected or not, and whether the patient is using the prescribed therapy as intended. Because there is a risk of erring on the side of patient compliance, i.e., it is preferable to overestimate rather than underestimate patient compliance, any time a patient is detected as connected to a patient interface can be logged in the electronic memory of the respiratory device as a moment when therapy was adhered to.

[0411] The respiratory device may maintain a log of the total amount of time the patient was connected to the device and / or how long the device was on, with adherence being the percentage of duration the device was on. The device may log the duration of each patient connection status category. Data related to adherence may be accessible through a higher level settings menu. The menu may be password encrypted and / or otherwise protected from patient access. Compliance data may be logged for transmission to a server and / or available for download by connecting the respiratory device to a second device (such as a computer or USB).

[0412] The respiratory device can generate an alert when a patient is disconnected. The alert can be generated immediately or after a preset time after the determination that the patient has disconnected. The preset time can be from about 10 seconds to about 10 minutes, or from about 30 seconds to about 5 minutes, or from about 1 minute to about 2 minutes. The alert can also be output to a nurse call port. After the alert is generated, the device can provide the user with an option to confirm whether the patient has disconnected from the device, for example, via a user interface on the respiratory device. If the patient is still connected to the device, the user can use the option to manually override the controller's determination that the patient has disconnected. The override option can reduce false positive detections, for example, when the patient is connected to the device but may be breathing shallowly. The device's controller can use the patient connection determination to determine whether to display certain parameters. For example, the controller can receive an estimate of the patient's respiratory rate and display the respiratory rate estimate if it is determined that the patient is connected. The controller can also cause a determination of whether the patient is connected or not to be displayed. For example, the device may display a respiratory rate estimate if a patient is determined to be connected, and may display a symbol and / or notification that patient connection cannot be confirmed if a patient is not determined to be connected, thereby improving the reliability of the displayed respiratory rate estimate.

[0413] The device may also attempt to synchronize gas delivery with the patient's breathing if it determines that a patient is connected. Respiratory gating may include adjusting a flow source (such as a flow generator) to have a phase that matches the phase of the patient's respiratory cycle, such as by increasing flow rate when the patient is inhaling and / or decreasing flow rate when the patient is exhaling. One or more measured parameters, such as flow rate, blower motor speed, and / or system pressure, may be used to determine the patient's respiratory cycle. Further details of respiratory gating may be found in International Publication No. WO 2017 / 200394, filed May 17, 2017, which is incorporated herein by reference in its entirety.

[0414] The device can be configured to pause recording of certain patient parameters only when the patient is disconnected. Such patient parameters can include oxygen efficiency, which can be calculated based on the patient's measured blood oxygen saturation (SpO2) and the measured fraction of oxygen (FdO2) delivered to the patient. Alternatively, oxygen efficiency can be determined based on the patient's measured SpO2 divided by the measured FdO2. Oxygen efficiency can be determined based on a nonlinear relationship between the patient's measured SpO2 and the measured FdO2. The device can implement one or more closed-loop control systems that use oxygen efficiency to control the flow rate of gas. Patient disconnection detection can also be fed into oxygen delivery control, such as closed-loop control. If the patient temporarily disconnects from the patient interface, the patient's oxygen saturation may decrease, and the respiratory device controller can begin increasing the oxygen concentration in the gas mixture to be delivered to the patient. The device can automatically adjust FdO2 to achieve a target SpO2 value for the patient. When the patient interface is reattached to the patient, the oxygen concentration in the gas stream may be high, causing the patient's oxygen saturation to rise sharply, which may be harmful to the patient. Patient disconnection detection may factor into the device's oxygen delivery control, whereby the controller does not initiate an increase in oxygen delivery when it is determined that the patient has disconnected from the device, or the controller switches to a predetermined value. The device may also be configured to close a valve to stop the delivery of oxygen or other breathable gas mixed with air when it is determined that the patient has disconnected. Closing the valve to the oxygen or other breathable gas inlet may reduce the cost of providing therapy and / or improve user safety.

[0415] Additionally or alternatively, the device may be configured to reduce the flow rate, reduce or turn off power to the heating element of the humidification chamber, and / or reduce or turn off power to the heating element of the patient breathing conduit once it is determined that the patient has been disconnected. Reducing the flow rate may reduce noise. Reducing the flow rate and / or reducing or turning off power to the heating element of the humidification chamber and / or the patient breathing conduit may reduce the power consumption of the device, thereby extending battery life and / or the life of another power source for the device. Additionally or alternatively, the device may be configured to increase the flow rate for an initial period once it is determined that the patient has been disconnected. The increased flow rate may improve the reliability of the patient detection process. The initial period of increased flow rate may be used to confirm that the patient has actually been disconnected from the device, i.e., to reduce false detections. If the controller determines that the patient is disconnected at a relatively high flow rate, the device may take other actions as described above (e.g., stop some control algorithms, output an alarm, reduce the flow rate, reduce or turn off power to the humidification chamber and / or heating element of the patient breathing conduit, etc.). The initial period may be, for example, from about 10 seconds to about 10 minutes, or from about 30 seconds to 5 minutes, or from about 1 minute to 2 minutes. The device may resume normal operation, e.g., increasing the flow rate and / or turning on power to the humidification chamber and / or heating element of the patient breathing conduit, etc., once it is determined that the patient has reconnected to the device.

[0416] term Unless the context clearly requires otherwise, throughout the specification and claims, the words "comprises," "includes," "comprising," "including," and the like are to be construed in their inclusive sense, i.e., "including but not limited to," as opposed to their exclusive or exhaustive sense.

[0417] While the present disclosure has been described with reference to several embodiments and examples, those skilled in the art will recognize that the disclosure extends beyond the specifically disclosed embodiments to other alternative embodiments and / or uses, as well as obvious modifications and equivalents thereof. Moreover, while several variations of the embodiments of the present disclosure have been shown and described in detail, other embodiments within the scope of the present disclosure will be readily apparent to those skilled in the art. It is also contemplated that various combinations or subcombinations of certain features and aspects of the embodiments may be made and still fall within the scope of the present disclosure. For example, features described above in connection with one embodiment may be used in different embodiments described herein, with the combination still falling within the scope of the present disclosure. It should be understood that various features and aspects of the disclosed embodiments can be combined with or substituted for one another to form various modes of embodiments of the present disclosure. Therefore, it is not intended that the scope of the disclosure herein be limited by the specific embodiments described above. Thus, unless otherwise specified or clearly contradicted, each embodiment of the present invention may include, in addition to its essential features described herein, one or more features described herein from each of the other embodiments of the present invention described herein.

[0418] It should be understood that any feature, material, characteristic, or group described in connection with a particular aspect, embodiment, or example is also applicable to any other aspect, embodiment, or example described in this section or elsewhere in this specification, to the extent not inconsistent. All features disclosed herein (including any accompanying claims, abstract, and drawings), and / or all steps of any method or process so disclosed, may be combined in any combination, except combinations in which at least some of such features and / or steps are mutually exclusive. Protection is not limited to the details of any of the above-described embodiments. Protection extends to any novel or any novel combination of features disclosed herein (including any accompanying claims, abstract, and drawings), or any novel or any novel combination of steps of any method or process so disclosed.

[0419] Furthermore, certain features described in this disclosure in the context of separate implementations may also be implemented in combination in a single implementation. Conversely, various features described in the context of a single implementation may also be implemented in multiple implementations separately or in any suitable subcombination. Furthermore, although features may be described above as functioning in certain combinations, one or more features from a claimed combination may, in some cases, be deleted from the combination, and the combination may be claimed as a subcombination or a variation of the subcombination.

[0420] Furthermore, while operations may be shown in the figures or described in the specification in a particular order, it is not necessary that such operations be performed in the particular order shown, or in any sequential order, or that all operations be performed, to achieve desirable results. Other operations not shown or described may be incorporated into the example methods and processes. For example, one or more additional operations may be performed before, after, simultaneously with, or between any of the described operations. Furthermore, operations may be rearranged or reordered in other embodiments. Those skilled in the art will appreciate that in some embodiments, the actual steps performed in the illustrated and / or disclosed processes may differ from those shown in the figures. Depending on the embodiment, some of the steps described above may be removed and others may be added. Furthermore, features and attributes of the specific embodiments disclosed above may be combined in different ways to form additional embodiments, all of which are within the scope of the present disclosure. Also, the separation of various system components in the above-described embodiments should not be understood as requiring such separation in all embodiments, and it should be understood that the described components and systems may generally be incorporated together in a single product or packaged into multiple products.

[0421] For purposes of this disclosure, certain aspects, advantages, and novel features have been described herein. Not all such advantages may be achieved in accordance with any particular embodiment. Thus, for example, it will be understood by those skilled in the art that the present disclosure can be embodied or practiced in a way that achieves one advantage or advantages taught herein without necessarily achieving other advantages that may be taught or suggested herein.

[0422] Conditional language such as "may," "might," "might," and the like, unless specifically stated otherwise or understood otherwise by the context in which it is used, is generally intended to mean that some embodiments include certain features, elements, and / or steps, but other embodiments do not. Thus, such conditional language is generally not intended to imply that features, elements, and / or steps are in any way essential to one or more embodiments, or that one or more embodiments necessarily include logic that determines whether or not those features, elements, and / or steps are included or performed in any particular embodiment, with or without user input or direction.

[0423] As used herein, language of degree, such as the terms "approximately," "about," "generally," and "substantially," refers to a value, amount, or characteristic that is close to the stated value, amount, or characteristic, yet still performs a desired function or achieves a desired result. For example, the terms "approximately," "about," "generally," and "substantially" can refer to an amount that is within 10% of the stated amount, within 5%, within 1%, within 0.1%, or within 0.01%.

[0424] The scope of the present disclosure is not intended to be limited by the specific disclosure of embodiments in this section or elsewhere herein, but rather may be defined by the claims, whether presented in this section or elsewhere herein, or hereafter presented. Claim language is to be construed broadly based on the language employed therein and is not to be limited to the examples described herein or during the prosecution of this application, which examples are to be construed as non-exclusive.

Claims

1. 1. A respiratory system configured to provide respiratory therapy to a patient, comprising: The respiratory system comprises:

1. A respiratory device comprising: a flow generator configured to generate a flow of gas for delivery to the patient; and a controller, the controller comprising: receiving data of a first parameter of the gas flow indicative of respiration of the patient; generating flow parameter variation data based on the data for the first parameter; generating a measure of patient ventilation based on the flow parameter change data; generating a measure of total signal variability based on the flow parameter variation data; determining patient connection to the respiratory device based on a comparison of the measure of patient ventilation and the measure of total signal variability; a respiratory device configured to: A system comprising:

2. The system of claim 1 , wherein the first parameter is indicative of or is a flow rate.

3. 3. The system of claim 1 or 2, wherein the flow parameter change data is generated by subtracting a target value of the first parameter from a measured value of the first parameter.

4. 3. The system of claim 1, wherein the controller is further configured to receive data of a second parameter representative of the performance of a component of the respiratory device, the flow parameter change data being generated by subtracting an estimated effect of the second parameter from a measurement of the first parameter, the component of the respiratory device being a blower of the flow generator, the blower comprising a motor.

5. The system described in claim 4, wherein the second parameter indicates or is the motor speed of the blower motor.

6. 3. The system of claim 1, wherein the flow parameter change data is generated by subtracting a first average value of the first parameter from a second average value of the first parameter, the first average value and the second average value being determined based on different windows of data for each of the first parameters.

7. The system of claim 6 , wherein the second average value of the first parameter is determined based on a window of data that includes measurements of the first parameter.

8. 8. The system of claim 6 or 7, wherein the first average value of the first parameter is determined by applying an ongoing filter to the data for the first parameter.

9. 9. The system of claim 1, wherein the controller is further configured to generate data representing a plurality of measures of instantaneous patient ventilation from the flow parameter change data, the measures of patient ventilation being generated by filtering the data representing the plurality of measures of instantaneous patient ventilation.

10. 10. The system of claim 9, wherein the controller is further configured to select a portion of the flow parameter change data to generate respective measures of instantaneous patient ventilation.

11. 11. The system of claim 10, wherein the selected portion of the flow parameter change data represents a length of time in the range of 0.5 to 2 seconds.

12. 12. The system of claim 10 or 11, wherein each measure of instantaneous patient ventilation is generated by fitting one or more functions to the selected portion of the flow parameter change data, generating a curve based on the one or more fitting functions, and finding the integral of the absolute value of the curve generated by the one or more fitting functions.

13. The system of claim 12 , wherein the controller is configured to perform a least squares fit to fit the one or more functions to the selected portion of the flow parameter variation data.

14. 14. The system of claim 12 or 13, wherein the curve generated by the one or more functions is a straight line.

15. 14. The system of claim 12 or 13, wherein the curve generated by the one or more functions is a horizontal line.

16. 16. The system of any one of claims 1 to 15, wherein the controller is further configured to generate data representing a plurality of measures of instantaneous total signal variation from the flow parameter change data, the data representing the plurality of measures of total signal variation being generated by filtering the measures of instantaneous total signal variation.

17. 17. The system of claim 16, wherein each measure of instantaneous total signal variation is determined by taking the absolute value of the flow parameter change data.

18. 18. The system of any one of claims 1 to 17, wherein comparing the measure of patient ventilation with the measure of total signal variability comprises taking a ratio of the measure of patient ventilation to the measure of total signal variability.

19. 20. The system of claim 18, wherein the controller is configured to determine that the patient is connected if the ratio is above a first threshold.

20. the controller is configured to determine that the patient is connected if the ratio exceeds a second threshold for a certain amount of time; The system of claim 19 , wherein the first threshold is greater than the second threshold.

21. the controller is configured to use the determination of whether a patient is connected to determine whether to display a plurality of parameters, the plurality of parameters including the patient's respiratory rate; 21. The system of any one of claims 1 to 20, wherein the controller is configured to receive an estimate of the patient's respiratory rate when the patient is determined to be connected, and to display the respiratory rate estimate.

22. The system of any one of claims 1 to 21, wherein the system is a non-sealing system and the system is configured to provide nasal high flow therapy.

23. A system according to any preceding claim, wherein the system comprises a humidifier configured to humidify the flow of gas to the patient.

24. The system of claim 1 , wherein the respiratory device further comprises a flow sensor that determines the flow rate of the flow of gas.

25. 25. The system of claim 24, wherein the flow sensor is positioned between a flow generator of the respiratory device and an outlet of the respiratory device.

26. 26. The system of claim 24 or 25, wherein the flow sensor is an ultrasonic type sensor system, the flow sensor comprising a first ultrasonic transducer that transmits an acoustic pulse through the gas flow and a second ultrasonic transducer that receives the acoustic pulse, and determines the flow rate of the gas flow based on the speed of sound between the transducers.

27. A system according to any one of claims 24 to 26, wherein the first parameter of the gas flow is indicative of or is a flow rate, the flow rate being determined by the flow sensor.

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