Closed Loop Oxygen Control

Abstract

The present disclosure provides a flow therapy device that can implement one or more closed-loop control systems to control the flow of gas through the flow therapy device. The flow therapy device can monitor a patient's blood oxygen saturation (SpO2) and control the percentage of oxygen (FdO2) delivered to the patient. The flow therapy device can automatically adjust FdO2 to achieve a target SpO2 value for the patient.

Description

[Technical Field]

[0001] Field of Disclosure The present disclosure relates to methods and systems for controlling oxygen delivery in a flow therapy device. [Background technology]

[0002] background Ventilators are used to deliver a flow of gas to a user or patient in a variety of settings, such as hospitals, medical facilities, residential care, or home environments. The ventilator or flow therapy device may include an oxygen inlet to allow supplemental oxygen to be delivered along with the gas flow and / or a humidifier to deliver heated and humidified gas. The flow therapy device may allow for adjustment and control of the characteristics of the gas flow, including flow rate, temperature, gas concentration such as oxygen concentration, humidity, pressure, etc. Summary of the Invention [Means for solving the problem]

[0003] overview According to certain features, aspects, and advantages of a first embodiment disclosed herein, there is provided a ventilator for providing a flow of gas to a patient, the ventilator including: a gas composition sensor configured to determine at least an oxygen content (FdO2) of the flow of gas during operation of the ventilator; a controller configured to control the delivery of gas to the patient using closed-loop control, the controller configured to: receive patient parameter data indicative of the patient's oxygen saturation (SpO2) from the at least one sensor; receive data indicative of a measured fraction of delivered oxygen of the flow of gas (FdO2) from the gas composition sensor; receive flow rate data indicative of or corresponding to a flow rate of the flow of gas provided by the ventilator; determine at least one time-related parameter based at least in part on the flow rate data; and generate a patient-specific model based at least in part on the at least one time-related parameter, the patient-specific model being used to predict changes in the patient's oxygen saturation (SpO2) in response to changes in the measured fraction of delivered oxygen of the flow of gas (FdO2).

[0004] In some configurations of the first embodiment, the determination of the at least one time-related parameter is based, at least in part, on whether the flow rate falls below a specified threshold.

[0005] In some configurations of the first embodiment, the at least one time-related parameter is a device-specific delay time associated with the transport delay time of oxygen from the ventilator to the patient.

[0006] In some configurations of the first embodiment, the at least one time-related parameter is a patient-specific delay time associated with the transport delay time of oxygen from the patient's upper airway to the tissue perfusion monitoring site.

[0007] In some configurations of the first embodiment, the at least one time-related parameter is a decay value that is related to the time it takes for the patient's SpO2 level to decay to a range of stable values ​​following a change in FdO2 by the controller.

[0008] In some configurations of the first embodiment, the flow rate data indicates or corresponds to a particular flow rate configured by the user.

[0009] In some configurations of the first embodiment, the flow data indicates or corresponds to the measured flow rate of gas delivered by the ventilator.

[0010] In some configurations of the first embodiment, the flow rate is received from a flow sensor located within the gas flow.

[0011] In some configurations of the first embodiment, the determination of the at least one time-related parameter is based, at least in part, on at least one criterion associated with one or more physical characteristics of the patient.

[0012] In some configurations of the first embodiment, the determination of the at least one time-related parameter is based, at least in part, on at least one criterion related to the size of the patient.

[0013] In some configurations of the first embodiment, at least one criterion related to one or more physical characteristics of the patient is flow rate.

[0014] In some configurations of the first embodiment, at least one criterion associated with one or more physical characteristics of the patient is the type of patient interface detected.

[0015] In some configurations of the first embodiment, at least one criterion associated with one or more physical characteristics of the patient is a type of patient interface configured by the user.

[0016] In some configurations of the first embodiment, at least one criterion associated with one or more physical characteristics of the patient is heart rate.

[0017] In some configurations of the first embodiment, at least one criterion related to one or more physical characteristics of the patient is respiratory rate.

[0018] In some configurations of the first embodiment, the at least one criterion associated with one or more physical characteristics of the patient is an indicator of respiratory strength and / or lung capacity.

[0019] In some configurations of the first embodiment, at least one criterion associated with one or more physical characteristics of the patient is a type or mode of previous therapy.

[0020] In some configurations of the first embodiment, the controller is further configured to select the first algorithm or the second algorithm for determining the at least one time-related parameter based at least in part on whether the flow rate meets a specified threshold.

[0021] In some configurations of the first embodiment, the selection of the first algorithm or the second algorithm for determining the at least one time-related parameter is further based, at least in part, on at least one criterion associated with one or more physical characteristics of the patient.

[0022] In some configurations of the first embodiment, the closed-loop control includes using a first closed-loop control model configured to determine a target fraction of delivered oxygen (FdO2) of the gas flow.

[0023] In some configurations of the first embodiment, the target FdO2 for the gas flow is determined based, at least in part, on the target SpO2 and a patient parameter indicative of the patient's oxygen saturation (SpO2).

[0024] In some configurations of the first embodiment, the target FdO2 for the gas flow is further based, at least in part, on received data indicative of the actual measured fraction of oxygen delivered (FdO2) for the gas flow.

[0025] In some configurations of the first embodiment, the target FdO2 is further based, at least in part, on a previously determined target FdO2.

[0026] In some configurations of the first embodiment, the closed-loop control includes using a second closed-loop control model configured to determine a control signal for the oxygen inlet valve based, at least in part, on a difference between a target FdO2 for the gas flow and received data indicating an actual measured fraction of oxygen delivered (FdO2) for the gas flow.

[0027] In some configurations of the first embodiment, the control signal for the oxygen valve is determined, at least in part, based on received data indicative of the target FdO2 and the actual measured fraction of oxygen (FdO2) delivered in the gas flow.

[0028] In some configurations of the first embodiment, the control signal for the oxygen valve is further determined based, at least in part, on the received flow data.

[0029] In some configurations of the first embodiment, the received flow data corresponds to or is indicative of the total gas flow provided by the ventilator.

[0030] In some configurations of the first embodiment, the patient-specific model is generated during the current treatment session.

[0031] In some configurations of the first embodiment, the patient-specific model is generated during the current treatment session based at least in part on the default model.

[0032] In some configurations of the first embodiment, the patient-specific model is updated during the current treatment session.

[0033] In some configurations of the first embodiment, the patient-specific model includes the patient's oxygen efficiency.

[0034] In some configurations of the first embodiment, the oxygen efficiency is determined based, at least in part, on received data indicative of the patient's oxygen saturation (SpO2) and received data indicative of the measured fraction of oxygen delivered in the gas flow (FdO2).

[0035] In some configurations of the first embodiment, oxygen efficiency is determined at least in part based on received data indicative of oxygen saturation (SpO2) divided by received data indicative of the measured fraction of oxygen delivered (FdO2).

[0036] In some configurations of the first embodiment, oxygen efficiency is determined based, at least in part, on a non-linear relationship between received data indicative of the patient's oxygen saturation (SpO2) and received data indicative of the measured fraction of oxygen delivered (FdO2).

[0037] In some configurations of the first embodiment, the controller is configured to predict the patient's SpO2 based, at least in part, on received data indicative of the measured fraction of oxygen delivered (FdO2).

[0038] In some configurations of the first embodiment, one or more previous predicted values ​​of SpO2 are compared with currently received data indicative of the oxygen saturation SpO2 to calculate a model error.

[0039] In some configurations of the first embodiment, the model error is weighted by the signal quality of at least one sensor.

[0040] In some configurations of the first embodiment, the model error is used to correct the current SpO2 estimate.

[0041] In some configurations of the first embodiment, the predicted SpO2 is based at least in part on a Smith predictor.

[0042] In some configurations of the first embodiment, the ventilator further includes a patient interface selected from at least one of: a face mask, a nasal mask, a nasal pillows mask, a tracheostomy interface, a nasal cannula, or an endotracheal tube.

[0043] In some configurations of the first embodiment, the nasal cannula is a non-sealing nasal cannula.

[0044] In some configurations of the first embodiment, the ventilator is configured to deliver a flow of gas to the patient at a nasal high flow (NHF).

[0045] In some configurations of the first embodiment, the at least one sensor includes a pulse oximeter configured to determine or provide patient parameter data indicative of at least the patient's oxygen saturation (SpO2).

[0046] In some configurations of the first embodiment, the controller is configured to receive instrument parameter data indicative of the oxygen concentration of the gas stream.

[0047] In some configurations of the first embodiment, the respirator further includes a supplemental gas inlet valve.

[0048] In some configurations of the first embodiment, the controller is configured to control operation of the supplemental gas inlet valve.

[0049] In some configurations of the first embodiment, the supplemental gas inlet valve is a proportional valve.

[0050] In some configurations of the first embodiment, the supplemental gas inlet valve is an oxygen inlet valve.

[0051] In some configurations of the first embodiment, the supplemental gas inlet valve includes a swivel connector.

[0052] In some configurations of the first embodiment, the respirator further includes an ambient air inlet.

[0053] In some configurations of the first embodiment, the respirator further includes an oxygen inlet valve in fluid communication with the filter module, and the respirator is configured to inhale oxygen received from the oxygen inlet valve along with ambient air from the ambient air inlet in the filter module.

[0054] In some configurations of the first embodiment, the gas composition sensor is positioned downstream of the ventilator module of the respirator.

[0055] In some configurations of the first embodiment, the ventilator further includes a filter module positioned upstream of the ventilator module.

[0056] In some configurations of the first embodiment, the blower module mixes ambient air with oxygen.

[0057] In some configurations of the first embodiment, the respirator further includes a humidifier.

[0058] In some configurations of the first embodiment, the ventilator further includes an integrated blower and humidifier.

[0059] In some configurations of the first embodiment, the ventilator is configured to be portable.

[0060] In some configurations of the first embodiment, the ventilator is configured to have a controlled variable flow rate.

[0061] In some configurations of the first embodiment, the respirator further includes a heated breathing tube.

[0062] In some configurations of the first embodiment, the ultrasonic sensor system includes a first ultrasonic transducer and a second ultrasonic transducer.

[0063] In some configurations of the first embodiment, the first ultrasonic transducer and the second ultrasonic transducer are a receiver and a transmitter, respectively.

[0064] In some configurations of the first embodiment, the first ultrasonic transducer and the second ultrasonic transducer transmit pulses bidirectionally.

[0065] In some configurations of the first embodiment, the first ultrasonic transducer is a transmitter and the second ultrasonic transducer is a receiver.

[0066] In some configurations of the first embodiment, at least one of the first ultrasonic transducer or the second ultrasonic transducer sends a pulse across the gas flow.

[0067] In some configurations of the first embodiment, the controller is configured to display the first oxygen efficiency characteristic on a display of the ventilator.

[0068] In some configurations of the first embodiment, the controller is configured to display a second oxygen efficiency characteristic on a display of the ventilator, the second displayed value of oxygen efficiency being based at least in part on the patient's oxygen efficiency and the measured respiratory rate.

[0069] In some configurations of the first embodiment, the second oxygen efficiency characteristic is calculated by dividing received patient parameter data indicative of the patient's oxygen saturation (SpO2) by received data indicative of the delivered oxygen fraction (FdO2) of the gas flow, and dividing the resulting value by the measured respiratory rate.

[0070] In some configurations of the first embodiment, the controller is configured to display a graph or trend line illustrating at least one of the first oxygen efficiency characteristic or the second oxygen efficiency characteristic over a defined period of time.

[0071] In some configurations of the first embodiment, the ventilator is operable between a high-flow therapy mode and a bubble CPAP therapy mode.

[0072] In some configurations of the first embodiment, in a high-flow therapy mode, the ventilator is configured to administer high-flow therapy.

[0073] In some configurations of the first embodiment, in a bubble CPAP therapy mode, the ventilator is configured to deliver bubble CPAP therapy.

[0074] In some configurations of the first embodiment, one or more of patient parameter data indicative of oxygen saturation (SpO2) and flow data are received while therapy is being administered to the patient and relate to the current operation of the respiratory therapy device.

[0075] In some configurations of the first embodiment, one or more of the patient parameter data indicative of oxygen saturation (SpO2) and flow data is related to one or more previous operating states or therapy sessions of the respiratory therapy device.

[0076] In a second embodiment, a ventilator for providing a flow of gas to a patient includes: a gas composition sensor configured to determine at least a percentage of delivered oxygen (FdO2) of the flow of gas during operation of the ventilator; a controller configured to control the delivery of the flow of gas to the patient using closed-loop control, the controller being configured to: receive patient parameter data indicative of the patient's oxygen saturation (SpO2) from at least one sensor; receive data indicative of a measured percentage of delivered oxygen (FdO2) of the flow of gas from the gas composition sensor; receive flow rate data corresponding to or indicative of a flow rate of the flow of gas provided by the ventilator; compare the flow rate data to a predetermined flow rate threshold; determine a set of time-related parameters using a first model or a second model based at least in part on a result of the comparison of the flow rate data to the predetermined flow rate threshold; and generate a patient-specific model based at least in part on the set of time-related parameters, the patient-specific model being used to predict changes in the patient's oxygen saturation (SpO2) in response to changes in the measured percentage of delivered oxygen (FdO2) of the flow of gas.

[0077] The respirator of the second embodiment may include any one or more of the features of the respirator of the first embodiment described above.

[0078] In a third embodiment, a respiratory system for providing a flow of gas to a patient includes: a gas composition sensor configured to determine at least a delivered percentage of oxygen (FdO2) of the flow of gas during operation of the respiratory system; a patient sensor configured to determine at least a patient's oxygen saturation (SpO2); a controller configured to control the delivery of the flow of gas to the patient using closed-loop control, the controller configured to: receive patient parameter data indicative of the patient's oxygen saturation (SpO2) from the patient sensor; receive data indicative of a measured delivered percentage of oxygen (FdO2) of the flow of gas from the gas composition sensor; receive flow data corresponding to or indicative of a flow rate of the flow of gas provided by the respiratory system; and generate a patient-specific model based at least in part on the flow data, the patient-specific model being used to predict changes in the patient's oxygen saturation (SpO2) in response to changes in the delivered percentage of oxygen (FdO2) of the flow of gas.

[0079] The breathing system of the third embodiment may include any one or more of the features of the breathing apparatus of the first and / or second embodiments described above.

[0080] In a fourth embodiment, a method for controlling the delivery of a flow of gas to a patient using closed-loop control includes: receiving patient parameter data indicative of the patient's oxygen saturation (SpO2) from at least one sensor; receiving data indicative of the measured percentage of oxygen delivered in the flow of gas (FdO2) from a gas composition sensor; receiving flow rate data corresponding to or indicative of the flow rate of the flow of gas; determining at least one time-related parameter, the or each time-related parameter being based at least in part on the flow rate data; and generating a patient-specific model based at least in part on the at least one time-related parameter; the patient-specific model being used to predict changes in the patient's oxygen saturation (SpO2) in response to changes in the measured percentage of oxygen delivered in the flow of gas (FdO2).

[0081] The method of the fourth embodiment may include any one or more of the respiratory characteristics of the first and / or second embodiments described above, and / or any one or more of the respiratory system characteristics of the third embodiment.

[0082] In a fifth embodiment, there is provided a ventilator for providing a flow of gas to a patient, the ventilator including: a supplemental gas inlet valve configured to accept oxygen from an oxygen source; a flow generator operably connected to the supplemental gas inlet valve and configured to generate a flow of gas; a user interface including a display; and a controller configured to control the delivery of the flow of gas to the patient using closed-loop control, the controller configured to: determine a patient type based on one or more input or estimated or measured parameters of or associated with the patient; determine a patient-specific model based, at least in part, on the determined patient type; and initiate closed-loop control of the oxygen concentration of the flow of gas using the confirmed patient-specific model.

[0083] The respirator of the fifth embodiment may include any one or more of the features of the respirator of the first and / or second embodiments described above, and / or any one or more of the features of the breathing system of the third embodiment.

[0084] In some configurations of the fifth embodiment, the controller is further configured to display, on the display, a request for confirmation of the determined patient-specific model, and to receive user input regarding the request.

[0085] In some configurations of the fifth embodiment, the controller is further configured to initiate closed-loop control of the oxygen concentration of the gas flow using the confirmed patient-specific model based on received user input indicating confirmation of the patient-specific model.

[0086] In some configurations of the fifth embodiment, a patient-specific model is used to predict changes in the patient's oxygen saturation (SpO2) in response to changes in the measured fraction of oxygen delivered in the gas flow (FdO2).

[0087] In some configurations of the fifth embodiment, the ventilator further includes a gas composition sensor configured to determine at least the delivered fraction of oxygen (FdO2) of the gas flow during operation of the ventilator.

[0088] In some configurations of the fifth embodiment, the controller is further configured to receive data from the gas composition sensor indicative of the measured fraction of oxygen delivered (FdO2) of the gas flow.

[0089] In some configurations of the fifth embodiment, the controller is further configured to receive patient parameter data indicative of the patient's oxygen saturation (SpO2) from the at least one sensor.

[0090] In some configurations of the fifth embodiment, closed-loop control of the oxygen concentration of the gas flow using the validated patient-specific model includes adjusting the supplemental gas inlet valve based on received patient parameter data indicative of the patient's oxygen saturation (SpO2) and changes in the patient's oxygen saturation (SpO2) as predicted by the patient-specific model.

[0091] In some configurations of the fifth embodiment, the patient type is determined to be one of: an adult patient, or a pediatric patient.

[0092] In some configurations of the fifth embodiment, the child patient may be further determined to be one of: an infant patient, or a neonatal patient, or a pediatric patient.

[0093] In some configurations of the fifth embodiment, the one or more input or estimated or measured parameters of the patient or associated with the patient include a size of the patient.

[0094] In some configurations of the fifth embodiment, the patient size is the patient's height.

[0095] In some configurations of the fifth embodiment, the ventilator further includes a flow sensor.

[0096] In some configurations of the fifth embodiment, one or more input or estimated or measured parameters of the patient or associated with the patient are estimated by the flow rate setting.

[0097] In some configurations of the fifth embodiment, the one or more input or estimated or measured parameters of the patient or associated with the patient are the patient's measured or estimated heart rate and / or the patient's measured or estimated respiratory rate.

[0098] In a sixth embodiment, a respiratory system for providing a flow of gas to a patient includes: an oxygen source; a supplemental gas inlet valve configured to accept oxygen from the oxygen source; a flow generator operably connected to the supplemental gas inlet valve and configured to generate a flow of gas; a user interface including a display; and a controller configured to control the supply of the flow of gas to the patient using closed-loop control, the controller configured to: determine a patient type based on one or more input or estimated or measured parameters of or associated with the patient; determine a patient-specific model that is based, at least in part, on the determined patient type; and initiate closed-loop control of the oxygen concentration of the flow of gas using the confirmed patient-specific model.

[0099] The breathing system of the sixth embodiment may include any one or more of the characteristics of the breathing apparatus of the first embodiment, and / or the second embodiment, and / or the fifth embodiment described above, and / or any one or more of the characteristics of the breathing system of the third embodiment.

[0100] In some configurations of the sixth embodiment, the system further includes a patient sensor configured to determine at least the patient's oxygen saturation (SpO2).

[0101] In some configurations of the sixth embodiment, the controller is further configured to receive patient parameter data indicative of the patient's oxygen saturation (SpO2) from the patient sensor.

[0102] Features from one or more embodiments or configurations may be combined with features from one or more other embodiments or configurations. Furthermore, two or more embodiments may be used together during the process of assisting a patient's breathing.

[0103] As used herein, the term "comprising" means "consisting at least in part of." When interpreting each sentence in this specification containing the term "comprise," there may be other features present than those preceding the term. Related words such as "comprise" and "comprises" are to be interpreted in the same manner.

[0104] Reference to a range of numerical values ​​disclosed herein (e.g., 1 to 10) also incorporates reference to every rational number within that range (e.g., 1, 1.1, 2, 3, 3.9, 4, 5, 6, 6.5, 7, 8, 9, and 10) and also to any range of rational numbers within that range (e.g., 2 to 8, 1.5 to 5.5, and 3.1 to 4.7), and therefore every subrange of the entire range expressly disclosed herein is intended to be expressly disclosed herein. These are merely examples of what is specifically intended, and all possible combinations of numerical values ​​between the minimum and maximum values ​​recited are likewise considered to be expressly set forth in this application.

[0105] It should be understood that alternative embodiments or configurations may include any or all combinations of two or more of the parts, elements or features shown, described or referenced herein.

[0106] The invention may also be broadly said to consist in the parts, elements and features referred to or shown in the specification of this application, individually or collectively, and in any or all combinations of any two or more of said parts, elements or features.

[0107] Those skilled in the art to which this invention pertains will appreciate that many variations in construction and widely differing embodiments and applications of the invention will occur without departing from the scope of the invention as defined in the appended claims. The disclosures and descriptions herein are purely illustrative and are not intended to be limiting in any way. Where specific entities having known equivalents in the art to which this invention pertains are set forth herein, such known equivalents are deemed to be incorporated herein as if individually set forth. [Brief explanation of the drawings]

[0108] BRIEF DESCRIPTION OF THE DRAWINGS [Figure 1A] 1 shows a schematic configuration of a flow therapy device. [Figure 1B] 1 illustrates a sensing circuit board including a flow sensor that may be used in a flow therapy device. [Figure 1C] 1A-1D show schematic diagrams of various ultrasonic transducer configurations for a sensor system using a cross-flow beam. [Figure 1D] 1A-1D show schematic diagrams of various ultrasonic transducer configurations for a sensor system using a cross-flow beam. [Figure 1E] 1A-1D show schematic diagrams of various ultrasonic transducer configurations for a sensor system using an along-flow beam. [Figure 1F] 1A-1D show schematic diagrams of various ultrasonic transducer configurations for a sensor system using an along-flow beam. [Figure 1G] 1 shows a schematic representation of a ventilator with a flow generator for delivering bubble CPAP. [Figure 2] 1 shows a graph illustrating the operating phases of a flow therapy device. [Figure 3]1 shows a graph illustrating fitted trend lines for a patient model. [Figure 4] 10 shows a graph illustrating replicate trend lines for a patient model. [Figure 5] 10 shows a graph illustrating the signal time difference between predicted and actual SpO2 values. [Figure 6] 1 shows a Smith Predictor being used with a PID controller. [Figure 7] 1 shows a graph of predicted SpO2 values ​​with a delay time. [Figure 8] 1 shows a graph illustrating the output of different computational models for a PID controller. [Figure 9A] 1 illustrates a process flowchart for a method of controlling operation of a flow therapy device during a flow therapy session. [Figure 9B] 1 shows a flowchart of the sub-processes for the learning phase of a flow therapy session. [Figure 9C] 1 shows a flowchart of the sub-processes for the control phase of a flow therapy session. [Figure 10] FIG. 1 is a schematic diagram of a closed loop control system. [Figure 11] 1 illustrates a process for calculating oxygen efficiency for a patient. [Figure 12] 1 shows a graph illustrating the operating phases of a flow therapy device. [Figure 13A] 1 illustrates a process flowchart for a method of controlling operation of a flow therapy device during a flow therapy session. [Figure 13B] 1 shows a flowchart of the sub-processes for the setup phase of a flow therapy session. [Figure 13C] 1 shows a flowchart of the sub-processes for the control phase of a flow therapy session. [Figure 14] FIG. 12 is a perspective view of a first underside of the main housing of the flow therapy device showing a recess in the interior of the housing for the motor and / or sensor module subassembly. [Figure 15]FIG. 10 is a perspective view of a second underside of the main housing of the flow therapy device showing recesses for the motor and / or sensor module subassembly. [Figure 16] FIG. 12 is a perspective view of the motor and / or sensor subassembly on the underside of the main housing and fixed elbow of the flow therapy device. [Figure 17] FIG. 10 is an exploded perspective view of the components of the motor and / or sensor subassembly, shown generally by the arrowed gas flow paths through the subassembly. [Figure 18] FIG. 10 is a view of the underside of the cover and sensing PCB of the motor and / or sensor subassembly, showing the location of the sensors. [Figure 19] A perspective view from the rear of a flow therapy device shown in cross section adjacent the rear edge of the device, illustrating the arrangement of a portion of the main housing that provides a recess for receiving a motor and / or sensor subassembly. [Figure 20] FIG. 1 is a left front perspective view of a flow therapy device. [Figure 21] FIG. 1 is a left front perspective view of a flow therapy device. [Figure 22] FIG. 1 is a partially cutaway front left perspective view showing the valve module and filter module. [Figure 23] 1 is a schematic diagram of the gas flow paths for the filter module and valve module, where solid arrows represent oxygen (or other gas) flow and dashed arrows represent ambient air flow. [Figure 24] FIG. 10 is a cross-sectional view showing the gas flow path through the filter module and the valve module. [Figure 25] FIG. 2 is a rear overhead perspective view of the valve module in a first configuration. [Figure 26] FIG. 1 is a rear overhead perspective view showing the gas flow path through the valve module in a first configuration, with solid arrows representing oxygen (or other gas) flow and dashed arrows representing ambient air flow. [Figure 27] FIG. 2 is a cross-sectional view through a valve module in a first configuration. [Figure 28]1 is a cross-sectional view showing the coupling of valves and valve manifolds of a valve module in a first configuration and the gas flow paths therethrough. FIG. [Figure 29] FIG. 10 is a flow diagram illustrating an exemplary tuning method according to one configuration. DETAILED DESCRIPTION OF THE INVENTION

[0109] Detailed Description Patients suffering from a variety of health conditions and diseases may benefit from oxygen therapy. For example, patients suffering from chronic obstructive pulmonary disease (COPD), pneumonia, asthma, bronchopulmonary dysplasia, heart failure, cystic fibrosis, sleep apnea, lung disease, trauma to the respiratory system, acute respiratory distress, pre- and post-operative oxygen support, and other conditions or diseases may benefit from oxygen therapy. A common method of treating such problems is to provide the patient with supplemental oxygen to prevent the patient's blood oxygen saturation (SpO2) from dropping too low (e.g., below about 90%). However, providing a patient with too much oxygen can over-oxygenate the blood, which is also considered dangerous. Typically, a patient's SpO2 is maintained in the range of about 80% to about 99%, and preferably about 92% to about 96%, although these ranges may vary depending on the patient's condition. Due to a variety of factors, such as respiratory rate, lung tidal volume, heart rate, activity level, height, weight, age, gender, and other factors, there is no single prescribed supplemental oxygen level that will consistently achieve a target range of SpO2 response for each patient. The percentage of oxygen delivered (FdO2) for each patient must be regularly monitored and adjusted to ensure that each patient is receiving the correct FdO2 to achieve the target SpO2. Achieving an accurate and consistent SpO2 is a key element in treating patients with various health conditions or diseases. Furthermore, patients suffering from these health issues may benefit from a system that automatically controls oxygen saturation.

[0110] The percentage of oxygen (FdO2) delivered to the patient can be manually controlled. A clinician can manually adjust an oxygen delivery valve to change the flow rate or percentage of oxygen being delivered to the patient. A clinician can determine the patient's SpO2 level using a patient monitor, such as a pulse oximeter. The clinician can continue to manually adjust the amount of oxygen delivered to the patient until the patient's SpO2 level reaches the determined level.

[0111] One problem with current methods is that when a clinician is trying to achieve a particular SpO2 level, the clinician must change the FdO2, wait for the SpO2 reading to settle, and then make another change to FdO2 until the SpO2 is at the desired level. This repeated process of changing the FdO2 and waiting for the SpO2 to settle can be a significantly time-consuming process, especially when multiple patients require the same treatment.

[0112] Another problem is that some control algorithms may not adequately account for patient size. Control algorithms may not be suitable for neonatal and pediatric patients because their small size causes them to react significantly faster than in patients with larger SpO2 levels. This may be primarily due to the shorter physical distance that oxygenated blood has to travel to the patient's extremities (where pulse oximetry monitoring sites are commonly located).

[0113] Another issue is the accuracy of SpO2 that can be achieved. The accuracy of SpO2 control can depend on how fine the increments are for the displayed SpO2 and the selectable FdO2. Because a clinician may determine that no further changes to FdO2 are necessary once the ideal SpO2 is approached, accuracy can be hindered by the longer time required to obtain increasingly accurate values.

[0114] Another problem is that even if there is no change in FdO2, other factors can change a patient's SpO2 level over time. Patients need to be checked periodically, and their FdO2 adjusted, to maintain the correct SpO2. This process can be quite time-consuming for clinicians. Furthermore, if too much time passes between adjustments, the patient may be at risk of their SpO2 deviating too far from the target level.

[0115] While several systems exist that attempt to do something similar, many of them face additional problems due to the difficulty in measuring a patient's oxygen saturation. Pulse oximeters and similar devices produce signals that correspond with changes in the percentage of oxygen delivered with a significant delay. Furthermore, oxygen saturation readings can be inaccurate due to a variety of factors.

[0116] The present disclosure is applicable to a variety of patients requiring rapid and accurate oxygen saturation control. The present disclosure addresses the issue of patient size by selectively using different functions to determine time-related parameters according to the patient's size, where the output of the time-related parameters results in a controller that can respond quickly to the patient's needs as input to the controller tuning process. The controller can be configured to apply a closed-loop SpO2 control algorithm that can dynamically determine appropriate time-related parameters for determining FdO2 adjustments for larger patients (e.g., adults) and smaller patients (e.g., neonates and pediatrics) based, at least in part, on the operating characteristics of the flow therapy device.

[0117] The present disclosure provides closed-loop control of a flow therapy device that allows the patient or clinician to set a target SpO2 instead of a target FdO2. The flow therapy device can automatically change the FdO2 of the flow therapy device to achieve the target SpO2 based on the target SpO2, current SpO2, and current FdO2 values. Automatically controlling the FdO2 can assist in quickly and accurately adjusting the FdO2 until the target SpO2 is achieved. In some configurations, the system can generate a patient-specific model for each patient that begins a therapy session. The flow therapy device can have greater accuracy in achieving the target SpO2 by adjusting the FdO2 as needed to stay within the target SpO2 range without constant monitoring by the clinician.

[0118] The present disclosure provides flow therapy devices capable of implementing one or more closed-loop control systems, the features of which may be combined with the features of one or more of the configurations disclosed herein.

[0119] The flow therapy device can operate in an automatic mode or a manual mode. In the automatic mode, the controller can automatically control FdO2 based on a target SpO2 and / or a target FdO2 determined based on the measured SpO2. The valve at the oxygen inlet can be connected to a controller that can control the oxygen concentration in the gas flow based on the target FdO2. The controller can execute a control algorithm that can measure the FdO2 output by the flow therapy device. The FdO2 measurements can be taken periodically at a specified frequency, such as the maximum sample rate of the gas concentration sensor, or at a lower frequency, or the measurements can be taken aperiodically. The controller can continue to adjust the valve at the oxygen inlet until the measured FdO2 reaches the target FdO2. The measured FdO2 can be determined by a gas composition sensor.

[0120] In manual mode, the controller may receive a target FdO2 from a clinician or patient, for example, via a user interface. The controller may automatically control FdO2 based on the received target FdO2. The controller may control the oxygen concentration in the gas flow by controlling the oxygen inlet valve based on the target FdO2. The controller may execute a control algorithm that can use the measured FdO2 output by the flow therapy device (e.g., by a gas composition sensor of the flow therapy device) as an input to the controller. The FdO2 measurements may be taken periodically at a specified frequency, such as the maximum sample rate of the gas concentration sensor, or at a lower frequency, or the measurements may be taken aperiodically. The controller may continue to adjust the valve at the oxygen inlet to drive the measured FdO2 toward the target FdO2. The measured FdO2 may be determined by a gas composition sensor.

[0121] The flow therapy device may be configured to change from automatic mode to manual mode when the patient's SpO2 is not within the patient's tolerance range. Optionally, the flow therapy device returns to manual mode when the patient's SpO2 is outside (above or below) the patient's limits or if the patient's SpO2 does not move within the limits within a specified period of time after the start of a therapy session. The flow therapy device may return to manual mode when the patient sensor's signal quality falls below a threshold level for a specified period of time. In some configurations, the flow therapy device may trigger an alarm when switching from automatic mode to manual mode. In some configurations, the flow therapy device may trigger an alarm when the patient sensor's signal quality falls below a threshold level for a specified period of time. After the alarm is triggered, the flow therapy device may continue to function in automatic mode. The flow therapy device may provide the user with the option to disable the alarm or exit automatic mode via a graphical user interface.

[0122] In automatic mode, the controller may utilize two control loops. A first control loop may determine a target FdO2 based on the target SpO2. A second control loop may output an oxygen inlet valve control signal using the target FdO2 output by the first control loop and the measured FdO2. In manual mode, the controller may use only the second control loop, which may receive a target FdO2 or a default value output from a user input.

[0123] During a high-flow therapy session, the oxygen concentration measured by the device, the fraction of delivered oxygen (FdO2), can be substantially the same as the oxygen concentration when the user is breathing, the fraction of inspired oxygen (FiO2), when the flow rate of delivered gas meets or exceeds the patient's peak inspiratory demand. This means that the amount of gas delivered to the patient by the device during inspiration meets or exceeds the amount of gas inhaled by the patient during inspiration. High-flow therapy helps prevent the patient from inhaling ambient air and flushing the patient's airway with exhaled air. As long as the flow rate of delivered gas meets or exceeds the patient's peak inspiratory demand, inhalation of ambient air is prevented, and the gas delivered by the device, FdO2, is substantially the same as the gas the patient inhales, FiO2.

[0124] Flow Therapy Device A flow therapy device 10 is shown in FIG. 1A. The device 10 may include a main housing 100 enclosing a flow generator 11 in the form of a motor / impeller arrangement (e.g., a blower), an optional humidifier 12, a controller 13, and a user interface 14 (e.g., including a display and one or more input devices, such as one or more buttons, a touchscreen, etc.). The controller 13 may be configured or programmed to control the operation of the device. For example, the controller may control device components, including, but not limited to, operating the flow generator 11 to generate a flow of gas (gas flow) for delivery to a patient, operating the humidifier 12 (if present) to humidify and / or heat the generated gas flow, controlling the flow of oxygen to the flow generator blower, receiving user input from the user interface 14 for reconfiguration and / or user-defined operation of the device 10, and outputting information to a user (e.g., on a display). The user may be a patient, a healthcare professional, or any other person interested in using the device. As used herein, "gas flow" may refer to any gas flow that may be used in a respiratory aid or breathing apparatus, such as an ambient air flow, a flow containing substantially 100% oxygen, a gas flow containing some combination of ambient air and oxygen, etc.

[0125] The patient breathing conduit 16 is coupled at one end to a gas outlet 21 of the housing 100 of the flow therapy device 10. The patient breathing conduit 16 is coupled at another end to a patient interface 17, such as a non-sealing nasal cannula comprising a manifold 19 and nasal prongs 18. Additionally or alternatively, the patient breathing conduit 16 may be coupled to a face mask, nasal mask, nasal pillow mask, endotracheal tube, tracheostomy interface, or the like. The gas flow generated by the flow therapy device 10 may be humidified and delivered to the patient via the patient conduit 16 through the cannula 17. The patient conduit 16 may include a heater wire 16a for heating the gas flow passing through the patient. The heater wire 16a may be under the control of the controller 13. The patient conduit 16 and / or the patient interface 17 may be considered part of the flow therapy device 10 or, alternatively, its peripheral devices. The flow therapy device 10, breathing conduit 16, and patient interface 17 together may form a flow therapy system.

[0126] The controller 13 may control the flow generator 11 to generate a gas flow at a desired rate. The controller 13 may also control a supplemental oxygen inlet to allow for the delivery of supplemental oxygen, a humidifier 12 (if present) to humidify and / or heat the gas flow to an appropriate level, etc. The gas flow is directed to the patient through a patient conduit 16 and a cannula 17. The controller 13 may also control a heating element in the humidifier 12 and / or a heating element 16a in the patient conduit 16 to heat the gas to a desired temperature for a desired level of therapy and / or patient comfort. The controller 13 may be programmed with or may determine a suitable target temperature for the gas flow.

[0127] The oxygen inlet port 28 includes a valve through which pressurized gas can enter the flow generator or blower. The valve can control the flow of oxygen into the flow generator blower. The valve can be any type of valve, such as a proportional valve or a binary valve. The oxygen source can be an oxygen tank or a hospital oxygen supply. Medical-grade oxygen is generally 95% to 100% pure. Lower purity oxygen sources can also be used. Examples of valve modules and filters are disclosed in U.S. Provisional Patent Application No. 62 / 409,543, entitled "Valve Modules and Filter," filed October 18, 2016, and U.S. Provisional Patent Application No. 62 / 488,841, entitled "Valve Modules and Filter," filed April 23, 2017, both of which are incorporated herein by reference in their entireties. Valve modules and filters are described in further detail below with reference to Figures 17-25.

[0128] The flow therapy device 10 can measure and control the oxygen content of the gas being delivered to the patient, and therefore the oxygen content of the gas inhaled by the patient. During high-flow therapy, the high flow rate of gas delivered meets or exceeds the patient's peak inspiratory demand. This means that the amount of gas delivered by the device to the patient during inspiration meets or exceeds the amount of gas inhaled by the patient during inspiration. High-flow therapy therefore helps prevent the patient from inhaling ambient air and flushing the patient's airway with exhaled air. As long as the flow rate of delivered gas meets or exceeds the patient's peak inspiratory demand, inhalation of ambient air is prevented, and the gas delivered by the device is substantially the same as the gas inhaled by the patient. As such, the oxygen concentration measured by the device, the fraction of delivered oxygen (FdO2), will be substantially the same as the oxygen concentration the user inhales, the fraction of inspired oxygen (FiO2), and as such, both terms can be considered equivalent.

[0129] Operational sensors 30, 31, 32, such as flow, temperature, humidity, and / or pressure sensors, may be located at various locations within flow therapy device 10. Additional sensors (e.g., sensors 20, 25) may be located at various locations on patient conduit 16 and / or cannula 17 (e.g., there may be a temperature sensor 29 at or near the end of the inspiratory tube). Output from the sensors may be received by controller 13 to assist the controller in operating flow therapy device 10 to provide a suitable therapy. In some configurations, providing a suitable therapy includes determining the patient's peak inspiratory demand. Device 10 may have a transmitter and / or receiver 15 that enables controller 13 to receive signals 8 from the sensors and / or control various components of flow therapy device 10 or accessories or peripherals associated with flow therapy device 10, including, but not limited to, flow generator 11, humidifier 12, and heater wire 16. Additionally or alternatively, the transmitter and / or receiver 15 may provide data to a remote server or allow remote control of the device 10 .

[0130] Oxygen may be measured after mixing of the oxygen with ambient air by placing one or more gas composition sensors (e.g., an ultrasound transducer system, also called an ultrasound sensor system) in the device, in the supply conduit, at the patient interface, or at any other suitable location.

[0131] The oxygen concentration may also be measured by using flow sensors in at least two of the ambient air inlet conduit, the oxygen inlet conduit, and the final supply conduit to determine the flow rates of at least two gases. By determining the flow rates of both inlet gases or the flow rate of one inlet gas and the total flow rate of one inlet gas, in conjunction with the assumed or measured oxygen concentration of the inlet gases (approximately 20.9% for ambient air and approximately 100% for oxygen), the oxygen concentration of the final gas composition may be calculated. Alternatively, flow sensors may be placed in all three of the ambient air inlet conduit, the oxygen inlet conduit, and the final supply conduit, allowing for redundancy and testing that each sensor is operating correctly by checking the consistency of readings. Other methods of measuring the oxygen concentration delivered by the flow therapy device 10 may also be used.

[0132] The flow therapy device 10 may include a patient sensor 26 or patient monitoring system, such as a pulse oximeter, to measure one or more physiological parameters of the patient, such as the patient's blood oxygen saturation (SpO2), heart rate, respiratory rate, perfusion index, and provide an indicator of signal quality. The sensor 26 may communicate with the controller 13 via a wired connection or communication via a wireless transmitter in the sensor 26. The sensor 26 may be a disposable adhesive sensor designed to be connected to the patient's finger. The sensor 26 may also be a non-disposable sensor. Sensors designed for different age groups and available for connection to different locations on the patient may be used with the flow therapy device. The pulse oximeter is attached to the user, typically the user's finger, although other locations, such as the earlobe, are also options. The pulse oximeter is connected to a processor within the device and continuously provides a signal indicative of the patient's blood oxygen saturation. The patient sensor 26 may be a hot-swappable device, allowing it to be attached or replaced while the flow therapy device 10 is in operation. For example, the patient sensor 26 may be connected to the flow therapy device 10 using a USB interface or using a wireless communication protocol (e.g., near field communication, WiFi, or Bluetooth). If the patient sensor 26 is disconnected during operation, the flow therapy device 10 may continue to operate in its previous operating state for a defined period of time. After the defined period of time, the flow therapy device 10 may trigger an alarm, transition from automatic mode to manual mode, and / or exit a control mode (e.g., automatic mode or manual mode) entirely. The patient sensor 26 may be a bedside monitoring system or other patient monitoring system that communicates with the flow therapy device 10 by a physical or wireless interface.

[0133] The flow therapy device 10 may include a high-flow therapy device. As used herein, "high-flow" therapy refers to the administration of gas to a patient's airways at a relatively high flow rate that meets or exceeds the patient's peak inspiratory demand. The flow rate used to achieve "high flow" may be any of the flow rates listed below. For example, in some configurations, for an adult patient, "high-flow therapy" may refer to the delivery of gas 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 25 LPM to about 75 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 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. For adult, neonatal, infant, or pediatric patients, a high flow therapy device may 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. The flow therapy device 10 may deliver any concentration of oxygen (e.g., FdO2) up to 100% at any flow rate between about 1 LPM and about 100 LPM. In some configurations, any of the flow rates can be combined with oxygen concentrations (FdO2) of about 20%-30%, 21%-30%, 21%-40%, 30%-40%, 40%-50%, 50%-60%, 60%-70%, 70%-80%, 80%-90%, and 90%-100%. In some combinations, the flow rate can be about 25 LPM to 75 LPM combined with oxygen concentrations (FdO2) of about 20%-30%, 21%-30%, 21%-40%, 30%-40%, 40%-50%, 50%-60%, 60%-70%, 70%-80%, 80%-90%, and 90%-100%.In some configurations, the flow therapy device 10, when operating in manual mode, may include a safety threshold that prevents the user from over-oxygenating the patient.

[0134] High-flow therapy may be administered into the user's nares and / or orally or via a tracheostomy interface. High-flow therapy may deliver gas to the user at a flow rate above the intended user's peak inspiratory flow requirements. High-flow therapy may create a flushing effect within the nasopharynx, causing the anatomical dead space of the upper airway to be flushed with a high inflow gas flow. This may create a reservoir of fresh gas available for each breath while minimizing nitrogen and carbon dioxide rebreathing. Meeting inspiratory demand and flushing the airway are even more important when attempting to control a patient's FdO2. High-flow therapy may be delivered by a non-sealing patient interface, such as a nasal cannula. A nasal cannula may be configured to deliver respiratory gas to the user's nares at a flow rate above the intended user's peak inspiratory flow requirements.

[0135] As used herein, the term "non-sealing patient interface" may refer to an interface that provides a pneumatic link between a patient's airway and a gas flow source (e.g., from the flow generator 11) that does not completely occlude the patient's airway. A non-sealing pneumatic link may include less than about 95% occlusion of the patient's airway. A non-sealing pneumatic link may include less than about 90% occlusion of the patient's airway. A non-sealing pneumatic link may include between about 40% and about 80% occlusion of the patient's airway. The airway may include one or more of the patient's nostrils or mouth. In a nasal cannula, the airway is through the nares.

[0136] The flow generator or blower 11 may include an ambient air inlet port 27 that draws ambient room air into the blower. The flow therapy device 10 may also include an oxygen inlet port 28 that leads to a valve through which pressurized gas may enter the flow generator or blower 11. The valve may control the flow of oxygen to the flow generator blower 11. The valve may be any type of valve, including a proportional valve or a binary valve.

[0137] The blower can operate at a motor speed of greater than about 1,000 RPM and less than about 30,000 RPM, greater than about 2,000 RPM and less than about 21,000 RPM, or between any of the aforementioned values. Operation of the blower can mix gas entering the blower through the inlet port. Using the blower as a mixer can reduce the pressure drop that can occur in systems with separate mixers, such as static mixers including baffles, because mixing requires energy.

[0138] 1B, a sensing circuit board 2200 is shown that may be implemented in the flow therapy device 10. The sensing circuit board 2200 may be positioned within the sensor chamber such that the sensing circuit board 2200 is at least partially immersed in the gas flow. The gas flow may flow from the blower 11 through a conduit and into a flow path within the sensor chamber. At least some of the sensors on the sensing circuit board 2200 may be positioned within the gas flow to measure gas properties of the flow. After passing through the flow path within the sensor chamber, the gas may flow to the humidifier 12 described above.

[0139] The sensing circuit board 2200 may be a sensing printed circuit board (PCB). Alternatively, the circuitry on the board 2200 may be assembled with electrical wires connecting electronic components rather than being printed on a circuit board. At least a portion of the sensing circuit board 2200 may be mounted outside the gas flow. The gas flow may be generated by the flow generator 11 described above. The sensing circuit board 2200 may include an ultrasonic transducer 2204. The sensing circuit board 2200 may include one or more thermistors 2205. The thermistor 2205 may be configured to measure the temperature of the gas flow. The sensing circuit board 2200 may include a thermistor flow sensor 2206. The sensing circuit board 2200 may include other types of sensors, such as humidity sensors, including humidity-only sensors and combined humidity and temperature sensors used with a separate temperature sensor, sensors for measuring atmospheric pressure, sensors for measuring differential pressure, and / or sensors for measuring gauge pressure. The thermistor flow sensor 2206 may include a hot wire anemometer, such as a platinum wire, and / or a thermistor, such as a negative temperature coefficient (NTC) or positive temperature coefficient (PTC) thermistor. Other non-limiting examples of heated temperature sensing elements include glass or epoxy encapsulated or unencapsulated thermistors. The thermistor flow sensor 2206 may be configured to measure the flow rate of the gas by being powered with a constant power or to maintain a constant sensor temperature or a constant temperature difference between the sensor and the gas flow.

[0140] The sensing circuit board 2200 can include a first portion 2201 and a second portion 2202. The first portion 2201 can be positioned within the gas flow path, while the second portion 2202 can be positioned outside the gas flow path. The direction of gas flow is indicated by arrow 2203 in FIG. 1B. The direction of gas flow can be straight or curved, as shown in FIG. 1B.

[0141] Positioning one or more of the thermistor 2205 and / or thermistor flow sensor 2206 downstream of a combined blower and mixer may take into account the heat supplied to the gas flow from the blower. Also, immersing a temperature-based flow sensor in the flow path may increase measurement accuracy because a sensor immersed in the flow may be more likely to be exposed to the same conditions, e.g., temperature, as the gas flows through, and therefore may provide a better indication of the gas's properties.

[0142] The sensing circuit board 2200 may include an ultrasonic transducer, transceiver, or sensor for measuring a gas property of a gas stream, such as the gas composition or concentration of one or more gases in the gas stream. Any suitable transducer, transceiver, or sensor may be mounted on the sensing circuit board 2200, as will be appreciated. In this configuration, the sensing circuit board includes an ultrasonic transducer system (also referred to as an ultrasonic sensor system) that utilizes ultrasonic or sound waves to determine gas concentration. Various sensor configurations are described below with reference to FIGS. 1C-1F.

[0143] The ultrasonic transducer system can determine the relative gas concentrations of two or more gases in a gas stream. The ultrasonic transducer system can be configured to measure the oxygen fraction in a bulk gas stream consisting essentially of atmospheric air enriched with supplemental oxygen, a binary gas mixture of nitrogen (N2) and oxygen (O2). It is understood that the ultrasonic transducer system can also be configured to measure the gas concentrations of other enrichment gases blended with atmospheric air in the gas stream, including nitrogen (N2) and carbon dioxide (CO2). The ultrasonic transducer can determine the gas concentrations of gases in the gas stream at relatively high frequencies. For example, the ultrasonic transducer can output measured FdO2 values ​​at frequencies at or below the maximum sample rate of the sensor, such as about 1 Hz to 200 Hz, about 1 Hz to 100 Hz, about 1 Hz to 50 Hz, and about 1 Hz to 25 Hz.

[0144] In some configurations, the sensing circuit board 2200 includes a pair of ultrasonic transducers disposed on opposite sides of the sensing circuit board. Various alternative configurations of ultrasonic transducers can be used to sense properties of the gas stream by transmitting and receiving ultrasonic beams or pulses.

[0145] The distance between the ultrasonic transducers 2204 at either end of the sensing circuit board 2200 can affect measurement resolution. Generally, an actual measured length has a certain amount of error, and because the percentage of error generated during measurement is less for longer lengths than for shorter lengths, increasing the distance between each of the ultrasonic transducers 2204 can reduce the proportional or partial error. Thus, the overall uncertainty of the measurement is reduced. Increasing the distance can also increase measurement resolution and accuracy because the acoustic signal between the ultrasonic transducers 2204 can be of longer duration. However, as the distance increases, the signal may become weaker.

[0146] The ultrasonic transducers 2204 can be positioned so that the spacing between them at least partially coincides with the flow path. In some configurations, the ultrasonic transducers are positioned at opposite ends of the sensing circuit board. Because the entire surface of the flow path is exposed to the acoustic path, sound waves propagate through all of the gas in the flow path. Wave averaging can occur over the entire flow path rather than just one section of the flow path. Averaging over a longer distance reduces error and reduces dependence on air-oxygen mixing. The ultrasonic transducers can be configured to measure gas properties from any angle relative to the flow path.

[0147] Positioning sensors within the flow path or module, instead of outside the flow path or module, allows both transducers 2204 to operate within a smaller temperature range relative to each other or both at substantially one temperature (i.e., the temperature of the gas flow). Because the transducers are temperature sensitive, making them a substantially homogenous temperature increases accuracy. Additionally, positioning sensors along the flow path allows measurements and calculations that account for the effect of gas velocity, so that the effect of gas velocity can be removed from the sensor measurements.

[0148] The ultrasonic transducer system is configured as an ultrasonic binary gas sensing system. Binary gas analysis using ultrasound is based on sensing the velocity of an acoustic pulse through a gas sample, in this case the bulk or primary flow of a gas stream, flowing through a sensing passage in a sensor housing. The speed of sound is a function of the average molecular weight and temperature of the gas. The system can receive a sensor signal indicative of the temperature of the gas flowing through a beam path between the ultrasonic transducers. Knowing the sensed speed of sound and the sensed temperature, the gas composition in the gas stream can be determined or calculated. In particular, a measurement of the speed of sound across the sensing passage can be used to infer the ratio of two known gases by referencing stored data in the form of an empirical relationship, a standard algorithm, or a look-up table, as is known in the field of ultrasonic binary gas analysis. It will be appreciated that an estimate of the temperature of the gas stream within the ultrasonic transducer's beam path can alternatively be used in the binary gas analysis calculations if a temperature sensor is not utilized. In such an alternative embodiment, the temperature of the gas stream can be regulated or controlled within a narrow temperature band, allowing an estimate of the temperature of the gas stream within the beam path to be used.

[0149] In some configurations, the flow therapy device may also include a humidity sensor disposed within the flow path and configured to generate a humidity signal indicative of the humidity of the gas stream flowing through the sensor assembly. In such embodiments, the gas composition may be determined by the sensed speed of sound and the sensed temperature and / or the sensed humidity. The humidity sensor may be a relative humidity sensor or an absolute humidity sensor. In some embodiments, the gas composition may be determined based on the sensed speed of sound and the sensed humidity without the need for a temperature sensor.

[0150] Ultrasonic transducer systems can be used to measure the respective proportions of any two known gases in a gas composition. They can determine the relative gas concentrations in a mixture of air blended with supplemental oxygen, which is substantially equivalent to a nitrogen / oxygen mixture. In such a binary gas mixture, by monitoring the speed of sound and taking temperature into account, the average molecular weight of the gas can be determined, and thus the relative concentrations of the two gases. From this ratio, the oxygen or nitrogen percentage of the gas stream can be derived.

[0151] 1C-1F, various configurations of ultrasonic transducers are described for gas composition sensing systems for sensing the speed of sound through a gas stream by transmitting and receiving ultrasonic beams or pulses, where like reference numerals represent like components.

[0152] 1C , transducer configuration 2300 provides an arrangement in which there is a pair of transducers 2302, 2304 positioned opposite each other and on opposite sides of a sensing passage 2306, the direction of the gas flow path generally indicated at 2308. In this configuration, each of the transducers 2302, 2304 is driven as either a dedicated transmitter or receiver such that ultrasonic pulses 2310 are transmitted unidirectionally across the gas flow path from the transmitter to the receiver transducer. As shown, the transducer pair are aligned with the air flow path direction 2308 (i.e., not displaced upstream or downstream from each other) and are configured to transmit cross-flow pulses that are substantially perpendicular to the gas flow path direction.

[0153] 1D , an alternative transducer configuration 2320 is shown in which a pair of transducers 2322, 2324 are positioned opposite each other on opposite sides of a sensing passage, but each transducer can operate as both a transmitter and a receiver (i.e., the transducers are ultrasonic transmitter-receivers, or transceivers). In this configuration, bidirectional ultrasonic pulses 2326 can be sent between the transducer pair 2322, 2324. For example, the pulses can alternate back and forth between the transducers or be sent in any other sequence or pattern. Again, the transducer pair is aligned with and configured to send cross-flow pulses that are substantially perpendicular to the gas flow direction.

[0154] 1E , an alternative transducer configuration 2360 is shown having a pair of opposing transducers 2362, 2364 at opposite ends of a sensing passage 2306, with a gas flow path direction or axis generally indicated by 2308. In this configuration 2360, each of the transducers 2362, 2364 is driven as either a dedicated transmitter or receiver such that a flow-aligned ultrasonic pulse 2366 is transmitted unidirectionally in a beam path between the transmitter and receiver that is substantially aligned with or parallel to the gas flow path axis 2308 in the sensing passage 2306. In the illustrated embodiment, the transmitter is upstream of the receiver, although it will be understood that the opposite arrangement can also be utilized. In this configuration, a flow sensor is provided in the sensing passage to provide a flow signal indicative of the flow rate of the gas stream in the sensing passage. It is understood that the speed of sound in the sensing passage can be derived or determined in a similar manner as described above, and the flow signal can be used in signal processing to remove or compensate for the gas flow rate in the calculated speed of sound signal.

[0155] Referring to FIG. 1F , an alternative transducer configuration 2370 is shown in which a pair of transducers 2372, 2374 are provided at opposite ends of the sensing passageway as in FIG. 1E , but each transducer can operate as both a transmitter and a receiver, i.e., an ultrasonic transmitter-receiver, or transceiver. In this configuration, along-flow ultrasonic pulses 2376 can be sent bidirectionally between the transducer pair 2372 and 2374. For example, the pulses can alternate back and forth between the transducers or be sent in any other sequence or pattern. Again, the transducer pair is aligned with the gas flow path axis 2308 and configured to transmit the along-flow pulses in one or more beam paths substantially aligned with or parallel to the gas flow path axis 2308 within the sensing passageway 2306. In this configuration, a separate flow sensor is not necessarily required, as the flow component of the sound velocity signal can be derived or determined directly from processing of the transmitted and received acoustic pulses.

[0156] Some examples of flow therapy devices are disclosed in International Application No. PCT / NZ2016 / 050193, filed December 2, 2016, entitled "Flow Path Sensing for Flow Therapy Apparatus," and International Application No. PCT / IB2016 / 053761, filed June 24, 2016, entitled "Breathing Assistance Apparatus," both of which are incorporated herein by reference in their entireties. Aspects of the present disclosure and example configurations of flow therapy devices that may be used are described in further detail below with respect to Figures 11-16.

[0157] Control System 1A, the controller 13 may be programmed or configured to implement a closed-loop control system to control the operation of the flow therapy device. The closed-loop control system may be configured to ensure that the patient's SpO2 reaches and consistently remains at or near a target level.

[0158] The controller 13 may receive one or more inputs from a user, which may be used by the controller 13 to implement a closed-loop control system. The target SpO2 value may be a single value or a range of values. The one or more values ​​may be preset, selected, or determined by a clinician based on the patient type, where the patient type may refer to current pain and / or information about the patient, such as age, weight, height, sex, and other patient characteristics. Similarly, the target SpO2 may be two values, each selected in one of the ways described above. The two values ​​represent a range of acceptable values ​​for the patient's SpO2. The controller may target a value within the range. The target value may be the midpoint of the range or any other value within the range, which may be preset or selected by the user. Alternatively, the range may be automatically set based on the target SpO2 value. The controller may be configured to take one or more preset responses when the patient's SpO2 value moves outside the range. The response may include raising an alarm, changing the FdO2 to manual control, changing the FdO2 to a specific value, and / or other responses. The controller may have one or more ranges, where moving outside each range produces one or more different responses.

[0159] The graphical user interface of the flow therapy device may be configured to prompt the user to input a patient type, and SpO2 limits are determined based on the user selection. Additionally, the user interface may include a custom option that allows the user to define limits.

[0160] Typically, SpO2 is controlled between about 80% and about 100%, or about 80% and about 90%, or about 88% and about 92%, or about 90% and about 99%, or about 92% and about 96%. SpO2 can be controlled between any two suitable values ​​from any two of the above-mentioned ranges. The target SpO2 can be about 80% and about 100%, or about 80% and about 90%, or about 88% and about 92%, or about 90% and about 99%, or about 92% and about 96%, or about 94%, or 94%, or about 90%, or 90%, or about 85%, or 85%. The SpO2 target can be any value between any two suitable values ​​from any two of the above-mentioned ranges. The SpO2 target can correspond to the midpoint of the SpO2 for the defined range.

[0161] FdO2 can be configured to be controlled within a range. As previously mentioned, the oxygen concentration (FdO2) measured within the device is substantially the same as the oxygen concentration (FiO2) breathed by the patient as long as the flow rate meets or exceeds the patient's peak inspiratory demand, and as such, both terms can be considered equivalent. Each of the range limits can be preset, selected by the user, or determined based on the patient type, where patient type may refer to current pain and / or information about the patient, such as age, weight, height, sex, and / or other patient characteristics. Alternatively, a single value for FdO2 can be selected, and the range can be determined at least in part based on this value. For example, the range can be a set amount above and below the selected FdO2. The selected FdO2 can be used as a starting point for the controller. The system can have one or more reactions if the controller attempts to move the FdO2 outside the range. These responses may include sounding an alarm, preventing attempts to move the FdO2 out of range, switching to manual control of the FdO2, and / or switching to a specific FdO2. The device may have one or more ranges, where reaching the limits of each range produces one or more different responses.

[0162] FdO2 can be controlled between about 21% and about 100%, or about 21% and about 90%, or about 21% and about 80%, or about 21% and about 70%, or about 21% and about 60%, or about 21% and about 50%, or about 25% and about 45%. FdO2 can be controlled between any two suitable values ​​from any two ranges described above. The FdO2 target can be between any two suitable values ​​from any two ranges described above. When the range is based on a single value, the upper and lower limits can be determined by adding or subtracting a certain amount from the selected value. The added or subtracted amount can be about 1%, about 5%, about 10%, about 15%, about 20%, about 30%, about 50%, or about 100%. The added or subtracted amount can vary relative to the selected value. For example, the upper limit can be 20% higher than the selected value, so that at a selected value of 50%, FdO2 has an upper limit of 60% for the control range. The percentages used for the ranges can be about 1%, or about 5%, or 10%, or about 15%, or about 20%, or about 30%, or about 50%, or about 100%. The methods for calculating the lower and upper limits do not necessarily have to be the same. When a single value is used, the value can be about 21% to about 100%, or about 25% to about 90%, or about 25% to about 80%, or about 25% to about 70%, or about 25% to about 60%, or about 25% to about 50%, or about 25% to about 45%.

[0163] The graphical user interface (GUI) 14 may be configured to display a range of values ​​within which FdO2 and / or SpO2 are controlled. The range may be displayed by having two limits set apart from one another on the GUI, with an indicator appearing within the range graphically showing the location of the current value relative to the limits of the range.

[0164] The GUI may display graphs of recent FdO2 and / or SpO2 data. The GUI may display the levels of each parameter over a defined period, such as an hour or more, in the same or different graphs. The length of time the data is displayed may be adapted to the length of time for which data is currently available.

[0165] The displayed FdO2 data may be at least one of a target FdO2 or a measured FdO2. The SpO2 data may include a line indicating the target SpO2. Additionally or alternatively, the SpO2 and / or FdO2 data may include one or more lines or shaded portions indicating their respective control limits.

[0166] The graph may be displayed on the default display. Alternatively, the graph may be hidden with only the current data values ​​shown. The graph is made available through interaction with the GUI, such as by selecting to view the graph for a specified parameter.

[0167] Bubble CPAP Bubble CPAP therapy is another form of respiratory therapy that can be administered to newborns experiencing respiratory distress. Bubble CPAP therapy can cause fluctuations or oscillations in the pressure of gas delivered to a patient connected to a positive pressure ventilation machine. By submerging one end of the expiratory conduit in a water column, the resulting bubbles cause fluctuations or ripples in the pressure of the gas delivered to the patient. Bubble CPAP systems also provide a method for varying the average pressure of gas delivered to the patient by varying the level to which the end of the expiratory conduit is submerged in the water column. The level to which the end of the expiratory conduit is submerged can be kept constant to maintain the average pressure of gas delivered to the patient.

[0168] FIG. 1G shows a breathing system for administering bubble CPAP therapy that can provide humidified and pressurized gas to a patient 119 through a patient interface, such as a mask 128 of FIG. 1G, connected to an inhalation conduit 121. The inhalation conduit 121 is connected to an outlet 112 of a humidification chamber 110, which contains a volume of water 115. When the volume of water 115 in the humidification chamber 110 is heated by a heating plate 113 located within the device housing 114, water vapor begins to fill the volume of the chamber 110 above the water surface. The water vapor can heat and humidify a flow of gas (e.g., air) brought into the chamber 110 from a blower 118 (see FIG. 1G) through an inlet 116 of the chamber 110. The heated and humidified gas exits the outlet 112 of the humidification chamber 110 and flows into the inhalation conduit 121. The inhalation conduit 121 may include a heater, such as the heater wire 120 of FIG. 1G, which heats the walls of the conduit to promote a substantially constant humidity profile along the inhalation conduit 121, thus reducing condensation of humidified gas within the inhalation conduit 121. The device may provide power to heat the inhalation conduit 121 and heating plate 113, for example, with input from one or more sensors in the system.

[0169] The humidified gas may travel through an inhalation conduit 121 to a patient interface, such as a mask 128 fitted and / or sealed around the mouth, nose, and / or nares of the patient 119. The inhalation conduit 121 provides the patient 119 with a flow of gas, which may be ambient air, oxygen, a mixture of the two, or a mixture of ambient air and one or more other supplemental gases. The gas may include a medication, which may be added by nebulization. The flow of gas through the inhalation conduit 121 may be provided at a substantially constant flow rate in a bubble CPAP system.

[0170] Excess gas may flow through the expiratory conduit 130 to a pressure regulator 134, which may be a bubbler in an illustrative example. In a bubble CPAP system, the expiratory conduit 130 may terminate in an open end 136. This end 136 may be submerged in a volume of water 138 within the bubbler 134.

[0171] The bubbler can regulate pressure by submerging the terminal end 136 of the expiratory conduit 130 to a desired depth below a water level 140 in a volume of water 138. The terminal end 136 can also optionally be located on a short conduit that can be incorporated into the end of the expiratory conduit 130. The bubbler can function as a pressure regulator by releasing gas whenever the pressure exceeds a desired level to maintain the average (mean) pressure at a target level. The bubbler can also include a pressure relief valve 146 for releasing excess gas when the pressure exceeds a desired level. The bubbler can also produce oscillations in pressure, which can be clinically useful. Bubble CPAP therapy can reduce the incidence of acute lung injury and bronchopulmonary dysplasia compared to intubation and / or mechanical ventilation.

[0172] The breathing system of FIG. 1G may include a gas flow provided by a blower 118 integrated into the device housing 114. The system of FIG. 1G may also optionally include a supplemental gas source (e.g., an oxygen tank, an oxygen mixer coupled to a flow meter, etc.) to control the oxygen concentration of the gas flow delivered to the patient 119. The supplemental gas source may be connected to the device housing 114 and / or the blower 118 (e.g., at a supplemental gas inlet). The flow of one or more supplemental gases provided to the device may be electronically controlled by the device at the supplemental gas inlet, for example, as described in accordance with the above disclosure of the flow therapy device. The supplemental gas source may also be configured to provide other types of supplemental gas, such as nitrogen. The supplemental gas source may be connected to an internal mixer that blends the supplemental gas with ambient air to provide the gas flow to the patient. The concentration of the supplemental gas introduced into or present in the gas stream may be controlled. The system may include a temperature sensor 144 in the inhalation conduit 121. The temperature sensor 144 may be coupled to and in electrical communication with a controller located within the instrument housing 114, 117.

[0173] The respiratory device is changeable between a high flow therapy mode and a bubble CPAP therapy mode.

[0174] In the high flow therapy mode, the respiratory device is configured to deliver high flow therapy.

[0175] In the bubble CPAP therapy mode, the respiratory device is configured to deliver bubble CPAP therapy.

[0176] High flow therapy is nasal high flow therapy.

[0177] In the high flow therapy mode, the system includes an unsealed patient interface coupled to the inhalation conduit 121 .

[0178] The unsealed patient interface may be a nasal cannula.

[0179] In use, the nasal cannula is positioned on the user's face to deliver gas to the user's nostrils.

[0180] In the bubble CPAP therapy mode, the system includes a sealed patient interface coupled to an inhalation conduit 121, and an exhalation conduit 130 coupled to the sealed patient interface.

[0181] The expiratory conduit 130 is coupled to a pressure regulator to regulate the pressure within the patient interface and / or the patient's airway.

[0182] As explained in detail above, the pressure regulator includes a chamber with a column of water, and the expiratory conduit 130 is submerged in the column of water. The pressure delivered to the user is defined or set by the depth to which the expiratory conduit 130 is submerged within the column of water.

[0183] The inhalation conduit 121 may be common to both the high flow and bubble CPAP therapy modes.

[0184] The same inhalation conduit can be used for both modes, reducing the number of components that need to be replaced when changing modes.

[0185] Furthermore, this common inhalation conduit allows the same respiratory device, including the blower and humidifier integrated into the housing, to be used for both bubble CPAP mode and high-flow mode. Furthermore, the integrated humidifier-blower in a common housing simplifies the transition between bubble CPAP and high-flow modes, as a single device may be used rather than the unique configuration of several components required in prior art systems.

[0186] The system provides a single breathing apparatus that can be used to deliver both bubble CPAP therapy and high-flow therapy, although only the interface requires modification: no modification to the gas delivery components (i.e., no modification to the gas delivery components) because a common breathing apparatus can be used to deliver humidified gas.

[0187] The controller 13 may include a high flow therapy control program associated with the high flow therapy mode.

[0188] The controller 13 may include a bubble CPAP therapy control program associated with the bubble CPAP therapy mode.

[0189] In some embodiments, the high flow therapy mode may have a high flow therapy controller. Optionally, the high flow therapy controller may be configured to execute a high flow therapy control program.

[0190] In some embodiments, the bubble CPAP therapy mode may have a bubble CPAP therapy controller. Optionally, the bubble CPAP therapy controller may be configured to execute a bubble CPAP therapy control program.

[0191] The controller 13 is configured to select and apply a program corresponding to the selected operating mode.

[0192] Each of the high flow therapy control program and the bubble CPAP therapy control program defines corresponding operating parameters.

[0193] In some configurations, the operating parameters may include one or more motor speed or pressure limits (eg, pressure caps), as described in more detail below.

[0194] Closed-Loop Control Referring to FIG. 10 , a schematic diagram of a closed-loop control system 1000 is shown. The closed-loop control system may utilize two control loops. The first control loop may be implemented by an SpO2 controller. The SpO2 controller may determine a target FdO2 based, in part, on a target SpO2 and / or a measured SpO2. As described above, the target SpO2 value may be a single value or a range of acceptable values. One or more values ​​may be preset or selected by a clinician, or may be automatically determined based on client characteristics. Generally, the target SpO2 value may be received or determined before or at the beginning of a treatment session, although a target SpO2 value may be received at any time during a treatment session. During a treatment session, the SpO2 controller may also receive as inputs one or more measured FdO2 readings from a gas composition sensor, and one or more measured SpO2 readings and one or more signal quality readings from a patient sensor. In some configurations, the SpO2 controller may receive the target FdO2 as an input, in which case the output of the SpO2 controller may be provided directly back as an input to the SpO2 controller. Based at least in part on the input, the SpO2 controller may output the target FdO2 to the second control loop.

[0195] The second control loop may be implemented by an FdO2 controller. The FdO2 controller may receive inputs of measured FdO2 and target FdO2. The FdO2 controller may then output an oxygen inlet valve control signal to control operation of the oxygen valve based on the difference between these measured FdO2 and target FdO2 values. The FdO2 controller may receive the target FdO2 value output from the first control loop when the flow therapy device is operating in automatic mode. The FdO2 controller may also receive additional parameters, such as flow rate values ​​or data, gas properties, and / or measured FdO2. The gas properties may include the temperature of the gas at the O2 inlet and / or the oxygen content of the source. The gas source connected to the oxygen inlet valve may be an oxygen-enriched gas stream, where the oxygen content of the source may be less than pure oxygen (i.e., 100%). For example, the oxygen source may be an oxygen-enriched gas stream having an oxygen content less than 100% and greater than 21%.

[0196] In some examples, the controller receives as input one or more of patient parameter data indicative of the patient's oxygen saturation (SpO2) and gas flow rate data during the administration of therapy to a patient, the input relating to a current operation of the respiratory therapy device. In some other examples, the controller may receive as input one or more of patient parameter data indicative of the patient's oxygen saturation (SpO2) and gas flow rate data, the one or more inputs relating to one or more previous operating states or therapy sessions of the respiratory therapy device.

[0197] From at least some of the inputs, the FdO2 controller can determine the oxygen flow rate required to achieve the target FdO2. The FdO2 controller can use the flow rate input to modify the valve control signal. If the flow rate changes, the FdO2 controller can automatically calculate the new required oxygen flow rate needed to maintain the target FdO2 at the new flow rate without having to wait for feedback from a gas concentration sensor, e.g., a measured FdO2 value. The FdO2 controller can then output a modified valve control signal to control the valve based on the new flow rate. In some configurations, the FdO2 controller's control signal can set the oxygen valve's current to control its operation. Additionally or alternatively, the FdO2 controller can detect changes in the measured FdO2 and modify the valve position accordingly. During manual mode, the second control loop can operate independently without receiving a target FdO2 from the first control loop. Rather, the target FdO2 can be received from user input or a default value.

[0198] During a therapy session, the SpO2 and FdO2 controller may continue to automatically control the operation of the flow therapy device until the therapy session ends or until an event triggers a change from automatic mode to manual mode.

[0199] Closed-loop control using a patient model FIG. 2 provides a graph 200 of SpO2 and FdO2 illustrating multiple phases of operation of a flow therapy device during a treatment session. While FdO2 (the percentage of oxygen delivered) is used in the graph, as previously mentioned, FdO2 is substantially the same as FiO2 as long as the flow rate meets or exceeds the patient's peak inspiratory demand. The operational phases include a learning phase 210 and a control phase 220. During the learning phase, the controller generates a patient-specific model. Due to differences between individual patients, there may be differences in how each patient's SpO2 responds to changes in FdO2. As a result, a patient-specific model may be generated to better control the patient's SpO2. The learning phase 210, also referred to as a model-building phase, may include a waiting stage 212, a feedforward stage 214, and a model generation or patient characterization stage 216. The patient characterization stage occurs simultaneously with at least a portion of the feedforward stage 214. During the patient characterization phase, the patient-specific model may be iteratively developed as data is collected during the feedforward stage 214. The learning phase is complete after the generation of the patient-specific model. After the learning phase, the flow therapy device operates in the control phase until the end of the treatment session. As described below, the flow therapy device may be configured to return to the learning phase during the treatment session. In some configurations, the learning phase is optional, and the patient-specific model may be generated without a defined learning phase. For example, in such configurations, a default model may be used initially. The default model may then be updated to the patient-specific model during the treatment session. The patient-specific model may be updated at defined intervals, defined events, periodically, aperiodically, and / or continuously during the treatment session.

[0200] Learning Phase When the flow therapy device is initially powered on, it may start in manual mode or automatic mode. If the device is in manual mode, it may be switched to automatic mode. When starting in automatic mode or when switched to automatic mode, the flow therapy device may begin a therapy session after the user provides one or more operating settings (e.g., FdO2 limit, SpO2 limit, flow rate, etc.). Once the session begins, the controller may begin a wait stage 212. During the wait stage 212, the position of the oxygen inlet valve is based on the FdO2 setting before the start of the learning phase (e.g., an initial level or default value configured by the clinician), which may result in the valve remaining in the same position or a change in valve position (e.g., open or closed). The patient's SpO2 may change in response to high-flow therapy. The FdO2 is held at a constant level and is not adjusted during the wait stage 212. The controller may measure and record the patient's SpO2. The controller may wait until SpO2 stabilizes and settles to a fairly constant value before proceeding to the feedforward stage 214. The wait stage 212 may last for a defined period of time. The controller may be configured to start the feedforward stage 214 without the wait stage 212.

[0201] During the feedforward stage 214, the controller may change the level of FdO2, for example, increasing or decreasing the level. The new FdO2 value may be preset or determined based on factors such as the patient's current SpO2. The new FdO2 may be selected by a clinician, who selects the FdO2 based on the clinician's own experience and knowledge. The selected FdO2 may bring the patient's SpO2 closer to the target SpO2 level. The FdO2 may be determined automatically by the controller 13.

[0202] During the feedforward stage 214, the controller measures and records the patient's SpO2. The controller can also measure and record FdO2. A graph shows a step change in FdO2 to the target FdO2 value. The actual FdO2 can rise to the target FdO2 over a defined period of time. With respect to SpO2 and FdO2, the actual measured data can be incorporated into the evaluation and generation of a model of the relationship between SpO2 and FdO2. Signal quality indicators from the patient sensor 26 can also be recorded.

[0203] The feedforward stage 214 can last for at least a defined minimum period and can automatically terminate after a defined maximum period. In some configurations, the minimum period can be approximately 30 seconds, approximately 1 minute, approximately 2 minutes, 3 minutes, or another value within the aforementioned values. The maximum period can be approximately 3 minutes, approximately 4 minutes, approximately 5 minutes, approximately 6 minutes, or another value within the aforementioned values. The minimum and maximum values ​​can be a combination of any two suitable values ​​described above. After the minimum period, the controller can determine whether the patient is sufficiently characterized based on an analysis of the defined patient characterization criteria. If the maximum period is reached without the patient being sufficiently characterized, the feedforward stage terminates and the control phase begins using a default patient model. The default model can depend on the patient type (e.g., normocapnic, hypercapnic, user-defined, or other type). The default patient model can be based, at least in part, on one or more received characteristics of the patient. Reasons for failing to characterize a patient are discussed in more detail below. In some configurations, the controller can be configured to bypass the feedforward stage 214 after the wait stage 212. In such cases, the controller may analyze the measured data for SpO2 and FdO2 to characterize the patient during the waiting stage. The controller may initially use a default patient model based on known patient characteristics and may continue to iteratively characterize the patient model based on the measured data for SpO2 and FdO2 during operation, as described further herein, without initiating a prescribed feedforward stage.

[0204] During the feedforward stage 214, the controller may analyze the relationship between FdO2 and SpO2. The controller may be configured to model the relationship using an exponential decay function, where the exponential decay constant is varied to best fit the model to the data. The initial and final FdO2 values ​​used in the exponential decay function may be set by the initial and final target FdO2 values. Fitting the model to the FdO2 data allows for analytical evaluation of the SpO2 model, which may be quicker and less computationally intensive. An example of what both sets of trend fits may look like is shown in FIG. 3. Optionally, the controller may determine the relationship between the measured FdO2 and the amount of time since the change in target FdO2.

[0205] 3, graph 301 shows fitted trends for SpO2 graph 302 and FdO2 graph 305. The graphs also include an indication of the patient monitor's signal quality 304. To fit a trend to the SpO2 data, a model representing the behavior of the SpO2 data may be generated, and at least one constant parameter of the model may be determined. The model may correlate each change in FdO2 with a time-based change in SpO2.

[0206] After a change in FdO2, SpO2 may not show any change due to the change in FdO2 for a period of time, which may be referred to as lag time. Lag time can be attributed to a combination of factors. One possible factor is the time it takes for the device to change FdO2 and become apparently consistent. Another possible factor is the time it takes for gas to travel from the device to the interface, which may depend on the selected flow rate. Another possible factor is the time it takes for gas to travel from the user interface to the patient's lungs. This may depend not only on the selected flow rate, but also on the patient's airway restriction and the length of the path from the interface to the patient's lungs. Another possible factor is the time it takes for oxygenated blood to travel from the patient's lungs to the measurement site (i.e., the patient sensor location). This depends on the blood's movement speed, which varies based on the patient's physiology and heart rate. Furthermore, the length of this time may depend on the distance between the patient's lungs and the type of patient sensor used. The distance may vary depending on the location of the patient sensor. Additionally or alternatively, the distance may vary depending on the patient's size.

[0207] After the delay time, SpO2 may exhibit an exponential decay curve, where SpO2 asymptotically approaches a new value, where the overall change is proportional to the overall change in FdO2. In some embodiments, there are four parameters of the model that can affect its shape (in addition to the effect of changes in FdO2 supply): The first parameter is the delay time between the change in FdO2 and the initial change in SpO2. The second parameter is the initial value of SpO2. The third parameter is the magnitude of the total change in SpO2 relative to the magnitude of the change in FdO2. The fourth parameter is the exponential decay rate, which defines how quickly SpO2 reaches its final value after the delay time.

[0208] Due to FdO2 varying over time instead of representing a single change, the SpO2 model can be evaluated as the integral of the effect of various FdO2 changes over time. A model that can be used is shown below in equation (1):

number

[0209] Equation (1) includes five parameters for the model that can be evaluated and determined when generating the model: FdO20, which is the initial FdO2; SpO20, which is the initial SpO2; the lag time DT, which can be measured as the time in seconds between the change in FdO2 and the effect on the percentage of measured SpO2; τ, which is the exponential decay constant; and

number

[0210] In one embodiment, the fit can be quantified by a method known as least squares fitting. Least squares fitting involves looking at each data point and calculating an error, where the error is based on the difference between that data point and an associated point on the model. The errors for each data point can be added to give an overall error value for the model.

[0211] The model may be determined by selecting the set of parameters that results in a model with the smallest possible total error. Values ​​for the set of parameters may be calculated using a suitable iterative method that seeks to get progressively closer to an ideal set of constant parameters. One algorithm is the Levenberg-Marquardt algorithm. With further reference to FIG. 4, a graph 401 showing the iterations of the trend line before reaching a best fit 405 and a graph 404 of signal quality are shown.

[0212] Furthermore, when calculating the error, the error value for each individual data point may be weighted by the corresponding signal quality for that individual data point. The signal quality of the patient sensor is shown in graph 404. Weighting each data point may give extra weight to more accurate data points when determining constant parameters and fitting trend lines. Without weighting, the error of the data points in the model may be significantly affected by inaccurate data points.

[0213] The results of the learning phase can be used to tune the controller to optimize it for an individual patient. A non-tuned controller that is not specifically modeled for an individual patient can exhibit several drawbacks. In general, a slow / overdamped controller will take longer to reach the target SpO2 and may be slow to respond to any fluctuations. On the other hand, a fast / underdamped controller will try to move too quickly toward the target value and risk overshooting it. This can lead to oscillations of the controller around the target and instability. Preferably, the controller is tightly damped, i.e., the model can reach the target SpO2 value quickly, but not so quickly that it substantially overshoots the target and becomes unstable. Using the model generated by patient characterization, an analytical solution can be found to tightly damp the control algorithm.

[0214] Some of the analyses that can be performed during this learning phase are facilitated by systems that utilize high nasal flow. In other systems, such as ventilation via a mask or tracheostomy interface, the relationship between FdO2 and SpO2 is significantly affected by the patient's respiratory rate. One reason for this is the portion of each breath that is rebreathed exhaled gas. When a patient takes short, fast breaths, a larger portion of the breath is rebreathed gas, and therefore the gas that enters the patient's lungs consists of a smaller amount of therapeutic gas. Similarly, when a patient takes slow, deep breaths, a smaller portion of the breath is rebreathed gas, and therefore the gas that enters the patient's lungs consists of a larger amount of therapeutic gas. This affects the oxygen concentration in the patient's lungs, which in turn affects SpO2.

[0215] As previously mentioned, nasal high flow has the effect of flushing the patient's airways with therapeutic gas, significantly reducing rebreathing. This means that regardless of the patient's respiratory rate, rebreathing is minimal and the gas that enters the patient's lungs is much more similar in composition to the therapeutic gas delivered by the device.

[0216] Because the effect of respiratory rate on the FdO2 / SpO2 relationship is reduced, the device can utilize a learning phase at start-up where data analysis allows for optimal tuning of the controller and / or implementation of patient-specific predictive control without the need for computationally demanding constant learning.

[0217] When the characterization criteria are met, the patient is fully characterized. After patient characterization 216, the learning phase 210 ends and the control phase 220 begins. The characterization criteria may define tolerance ranges for at least some of the parameters used in calculating the patient model. For example, the characterization criteria may include a range of acceptable values ​​for a determined delay time between a change in FdO2 and the first change in SpO2, a range of acceptable values ​​for an initial value of SpO2, a range of acceptable values ​​for an exponential decay rate that defines how quickly SpO2 reaches its final value after the delay time, a range of acceptable values ​​for the ratio of changes between SpO2 and FdO2, and / or other parameters associated with generating the model. The characterization criteria may define only minimum or maximum values ​​for the parameters.

[0218] In some cases, patient characterization may fail. In such a situation, the controller may begin the control phase with a default PID controller or may switch back to automatically maintaining FdO2 at a prescribed level. The default PID controller may be designed to be tightly damped or overdamped for most, if not all, patients. In general, an overdamped controller that moves slowly toward the SpO2 target is preferable to an underdamped controller that oscillates and becomes unstable. Each type of patient may have a different default PID controller.

[0219] Reasons for patient characterization failure may include problems with the data set, such as low average signal quality, too small an FdO2 increase, and / or too small an SpO2 increase. Additionally or alternatively, failure may occur for reasons related to data modeling, such as certain parameters falling outside of a specific tolerance range. These parameters may include model fit / error, as a large error between the model and the data reduces the validity of the model. Parameters may include changed parameters of the model mentioned above (initial SpO2, delay time, exponential decay constant, and increase in the ratio of FdO2 to SpO2), as unrealistic values ​​for any of these would indicate an error in the model. Additionally or alternatively, failure may occur during PID tuning if any of the tuned PID values ​​fall outside a specific range.

[0220] The clinician would ideally be alerted by an alarm that this has occurred, and the option to attempt another learning phase would be available. Additionally or alternatively, the device may itself initiate another learning phase in an attempt to characterize the patient. The number of automatic attempts may be limited to a prescribed number. Additionally or alternatively, a patient-specific model may be generated from a default model and then optionally updated during the treatment session.

[0221] The learning phase may be repeated two or more times during a treatment session. Even if the learning phase is successful, circumstances may arise during a treatment session that cause the controller to re-enter the learning phase. The controller may have a maximum time for which the patient model is valid. For example, in a hospital setting, a patient's condition may change over time, affecting the relationship between FdO2 and SpO2. As such, it may be useful to terminate the control phase and / or automatically initiate a new learning phase to re-characterize the patient after a certain period of time, such as one or more days. Additionally or alternatively, the patient-specific model may be updated and re-characterized during a treatment session. For example, the patient-specific model may be updated periodically, aperiodically, and / or continuously at defined intervals, defined events, during a treatment session.

[0222] The controller may test the error between the corresponding predicted and measured SpO2 values. A sufficiently large error, perhaps multiple error values ​​or over a defined period of time, may indicate an incorrect patient model, and the controller may be configured to initiate a new learning phase. Optionally, if the patient's SpO2 falls outside the target range, the controller may terminate the control phase and trigger a new learning phase.

[0223] Predictive control during the control phase FIG. 5 shows a graph 500 of the signal time difference between predicted SpO2 values ​​and SpO2 data. One of the challenges of controlling FdO2 based on an SpO2 signal is the delay time and resulting signal time difference. When FdO2 is changed in the device, gas with the new oxygen concentration must travel through a conduit to a patient interface, down the patient's airway to the patient's lungs, and perform gas exchange in the patient's lungs. Oxygenated blood must then travel through the patient's blood vessels to the pulse oximeter site and be measured by a patient sensor, after which the measurement data is received by the controller. By the time the measurement data is received by the controller, multiple additional cycles have already been processed, potentially resulting in a significant overshoot of the target SpO2, which in turn can cause large oscillations in the patient's SpO2 and unstable control. Another aspect of nasal high flow is the use of a humidifier during a treatment session. Without a humidifier, the patient's airway quickly dries out. The humidification component may require a significant dwell time to function, thereby increasing the delay time. This additional delay makes predictors in understanding delay times quite important.

[0224] Some ways to handle this include overdamping the controller, having low sensitivity, and / or having a delay between each iteration of the control signal to allow previous changes in FdO2 to fully take effect. Such a delay may be based, at least in part, on data measured during the learning phase described above. To properly handle signal delays, such systems may create new problems due to being too slow to react to the patient's condition. For example, when the device is first powered on, it may take significantly longer to reach the target SpO2, or the controller may be too slow to react to sudden changes in the patient's SpO2.

[0225] The controller may be configured to perform predictive control on the PID controller during the control phase. The predictive control may be a Smith predictor. The predictive control may be determined, at least in part, based on one or more parameters analyzed during the learning phase 210. Using the data received during the learning phase 210 to design or modify the predictive controller allows for much more efficient and patient-specific control. The goal of predictive control is to know the signal time difference to predict the SpO2 value and control FdO2 based on the predicted SpO2 value instead of the measured SpO2. This results in a control algorithm that may be quite sensitive and stable.

[0226] The predicted value of SpO2 may represent SpO2 after a delay time has elapsed. The delay time is the period between the time a change to FdO2 is made and the time a response is seen in SpO2, i.e., a corresponding response is detected in the measured SpO2. Because any FdO2 change has no effect on SpO2 until after the delay time has elapsed, by the end of the delay time period, SpO2 may be predicted fairly accurately using currently available SpO2 and FdO2 data. The predictor may produce data substantially identical to the measured SpO2 data with the delay time removed, as shown in FIG. 5. The prediction does not predict the disturbances present in the actual data, but rather the overall shape of the curve is fitted.

[0227] The predictor may receive inputs including one or more measured FdO2 values, one or more target FdO2 values, one or more predicted SpO2 values, one or more measured SpO2 values, and / or one or more target SpO2 values. Each of the inputs may be a current value and / or a previous value at least temporarily stored by the processor. Each of the inputs may be paired with any relevant data associated with the input data point, such as a signal quality measurement and / or a value related to the time at which the measurement is made.

[0228] From here, the PID controller functions substantially the same as described above, except that the PID controller uses an estimated SpO2 instead of the measured SpO2, and as such, the difference between this estimate and the target is calculated instead. This value represents the change in SpO2. Due to the use of a predictor, the change in SpO2 takes into account previous changes in FdO2 that have not yet taken effect. The change in SpO2 is paired with the current FdO2 to determine a new target FdO2.

[0229] 6 shows a schematic diagram 600 of a Smith Predictor utilized with a PID controller. Initially, the PID controller receives an input of the difference between the predicted patient SpO2 and the target SpO2, and outputs a target FdO2 to the FdO2 controller to move the patient's SpO2 toward the target SpO2. The FdO2 controller outputs commands to control the valves of the flow therapy device based on the target FdO2 output by the PID controller.

[0230] This new FdO2 is delivered to the patient and may be combined with other disturbances to produce a patient response. These disturbances may include errors from any sensors or control mechanisms within the machine (such as the oxygen valve), resulting in an altered FdO2. Additional changes in the patient's response may result from the patient's physiological and physical parameters (such as physical activity or changes in respiratory rate) that have an effect on the patient's SpO2. Therefore, SpO2 is measured, and its value is the patient's current SpO2 ± any error from the sensor. The disturbance information is conveyed in a feedback signal, allowing the controller to adjust the FdO2 level to account for any changes in the patient's activity or breathing pattern that require more or less oxygen. A signal quality indication is also output to the PID controller.

[0231] For reference, in a controller without a Smith Predictor, the measured SpO2 value is compared to the target SpO2, and the difference between the two is fed back to the PID. In a Smith Predictor model, the controller first makes a prediction of SpO2. This can be done using the same model generated during the learning phase or a default model (e.g., where the patient cannot or has not been characterized), where SpO2 is estimated by integrating the effects of all changes in FdO2 over time and then adding them to the initial SpO2.

number

[0232] where DT, SpO20, a, τ, and FdO20 are constant parameters of the model that may be generated during the learning phase or may start as default values. The parameters may remain constant throughout the treatment session or may be updated continuously, periodically, or aperiodically. Importantly, DT is the delay time between the change in FdO2 and the onset of the SpO2 response. In the first step, this calculation is performed assuming DT is 0. This results in an estimate of the patient's SpO2 after the delay time has elapsed. This value may be referred to as the predicted SpO2 without the delay time.

[0233] Following this, the same equation is processed again using the estimate for DT from the learning phase. The output of the model when using DT may be referred to as delayed predicted SpO2, which predicts the current reading from the pulse oximeter. Delayed predicted SpO2 may also be calculated by referencing back to a previous estimate of SpO2 without a delay. For example, if the delay was 90 seconds, the delayed SpO2 estimate would be the undelayed SpO2 estimate made 90 seconds ago.

[0234] The difference between the SpO2 without the delay value and the measured SpO2 value is then calculated. If the model is perfect, the difference will be 0. Generally, there will be some difference, which represents both the error of the model and the error of the disturbances in SpO2 mentioned above.

[0235] 7 shows a graph 700 of predicted values ​​with lag time included. This error and disturbance value can then be added to a first predicted value of SpO2 without lag time and used to correct the predicted SpO2 using the measurement error between the actual SpO2 and the predicted SpO2. This final value represents the predicted SpO2 without lag time plus disturbance.

[0236] The delay time plus the difference between the undisturbed predicted SpO2 and the target SpO2 is then calculated and the result is fed back to the PID controller and the process begins again.

[0237] Assumptions can be made to reduce the computational burden of modeling the SpO2 response. First, because FdO2 is changed in step increments with each iteration of the control cycle, the equation can be evaluated using discrete time points. Because of this, the model can be further rearranged into an iterative process, where results from previous iterations of the model can be included in the evaluation of the current iteration of the model.

[0238] In some cases, the Smith predictor allows the PID controller to react to a prediction of the SpO2 reading rather than reacting to it. For example, the Smith predictor may predict SpO2 rising to a target level and settling there. However, when the actual SpO2 measurement comes in, it may indicate that the SpO2 is approaching the target faster than predicted and is now on the verge of overshooting the target based on previous changes in FdO2. As such, the controller may quickly lower FdO2 to minimize or even prevent the overshoot from occurring. Without the Smith predictor, the control system would not respond to the overshoot until it has already occurred.

[0239] FIG. 8 shows different computational models for the PID controller. To demonstrate the differences that the Smith Predictor makes, the computational model was designed to represent a COPD patient. The model included a sudden drop from a healthy SpO2 reading along with the normally occurring irregular fluctuations in SpO2. The goal was to see how quickly the control system could return the patient to a healthy SpO2 reading and settle at this point, as well as how well it could handle the irregular fluctuations. The same model with the same irregular fluctuations was tested with three different PID controllers: one with a Smith Predictor 802, one with a normal PID tuned to a specific patient 804, and one with a default patient 806. The PID controllers can be tuned or untuned. An untuned PID controller is referred to as a default PID or untuned PID. An untuned controller is referred to as a PID controller that is not tuned to a specific patient. However, the non-tuning controller may be tuned for stability or for a general patient type or for a specific patient type (e.g., normocapnic, hypercapnic, etc.) and loaded into the controller prior to operation of the flow therapy device, exemplary methods of which are described. Additionally, the tuning PID controller and the default PID controller may be referred to as PID controllers that do not incorporate a Smith Predictor. A Smith Predictor may be used to vary the tuning PID.

[0240] As noted above, Smith PID 802 returned to a healthy SpO2 reading approximately four times faster and was more accurate at maintaining target SpO2 than Default PID 806. Synchronized PID 804 performed better than Default PID 806, but not as well as Smith PID 802.

[0241] Patient Type-Based Predictive Control The closed-loop control of the system may face difficulties in estimating the response of smaller patients, such as neonates and pediatric patients. Control methods for determining and predicting SpO2 may be modified to account for smaller patients. The controller may be configured to automatically determine the type of patient connected to the device based on one or more operating characteristics, such as the measured flow rate or flow rate setting. This determination may allow the device to be used seamlessly with any patient, improving clinical workflow by eliminating the need to select a separate control mode and potentially manually configure it for patients requiring lower flow rates.

[0242] Lower flow rates are generally associated with smaller patients, e.g., children and neonates, where higher flow rates may not adequately describe the physiology of such patients. Devices used to administer high-flow therapy to neonates and children are generally configured with significantly lower flow rates than those used for larger patients. For example, such patients are generally administered high-flow therapy at rates set at 25 L / min or less. Estimation algorithms used for larger patients may not be appropriate for smaller patients. Smaller patients are generally considered to be more rapidly responsive patients, requiring more aggressive and rapid control of FdO2. Due to their small size, the SpO2 levels of neonates and children respond significantly more quickly than larger patients due to the shorter physical distance that oxygenated blood must travel to reach the patient's extremities (where pulse oximetry monitoring sites are typically located).

[0243] The controller can use different methods to determine timing parameters for estimating SpO2 levels in smaller patients at lower flow rates. Neonates and small children may be prime candidates for faster controllers, and adults may also be intentionally treated at lower flow rates. When adults are provided gas at lower flow rates, it may be appropriate to adjust the control method to provide faster control. When nasal high flow rates are low or lower, the therapeutic gas flow intake versus ambient air may be lower, reducing the effect of FdO2 on FiO2. Because of this reduced effect, the SpO2 controller may need to respond more aggressively. In other words, adult patients, who typically have higher peak inspiratory flows than juvenile patients (e.g., children, neonates, or infants), are provided gas at lower flow rates, and adult patients inhale somewhat more ambient air than at higher flow rates. This higher level of ambient air intake can result in a dilution of the oxygen (FdO2) concentration in the gas mixture inhaled by the patient, and therefore, as a result, the patient's SpO2 may not respond as expected, requiring more aggressive control of FdO2 to ensure that the SpO2 is maintained within or shifted into the target range.

[0244] Delay time The first time-related parameter used by the controller to estimate SpO2 is the delay time (DT). To determine DT, the controller may use a delay time algorithm that is based on the measured or otherwise set or configured gas flow rate for the patient. For example, at lower flow rates, such as flows below 25 L / min, the controller may dynamically determine a value for the delay time constant. In some examples, the controller may evaluate the flow rate value and determine where it falls within a set of flow rate ranges, as described, rather than simply checking whether it falls below a particular value or threshold.

[0245] The controller may be configured to infer or determine whether the patient type is an adult patient or a pediatric patient. In a further example, the controller may be configured to infer or determine whether the patient type is a particular type of pediatric patient. For example, the controller may be configured to determine whether the patient type is one of the following pediatric patient types: a premature neonatal patient, or a neonatal patient, or an infant patient, or a pediatric patient (e.g., 5-12 years old). The controller may be configured to determine the patient type based on at least one or more flow rate values.

[0246] In such examples, the controller may be configured to associate several flow rate ranges with several types of patients, based at least on the gas flow rate. For example, the controller may be configured to associate a flow rate range of 5 to 8 L / min with neonatal and infant patients, and a flow rate range of 10 to 25 L / min with pediatric patients. These ranges are for illustrative purposes only, and it will be understood that different flow rate ranges may be used in other examples. There may be significant overlap between flow rate ranges prescribed for patients of different sizes and weights due to significant variability in these patient characteristics (e.g., very large infants and very small young children may be prescribed similar flow rates). Therefore, in some configurations, it may be useful for the controller to consider additional patient type criteria.

[0247] Furthermore, in some examples, additional inputs or estimated or measured parameters of the patient may also be used to determine the patient type. These additional inputs or estimated or measured parameters of the patient may also be evaluated or associated with ranges to determine the patient type. For example, the patient's heart rate and / or respiratory rate may be further used by the controller in evaluating or determining the patient type.

[0248] Once the patient type is identified or determined by the controller, the controller may select or determine a patient-specific model appropriate for the patient type, for example, if the controller determines that the patient is a neonatal patient, the controller may determine that a model for neonatal patients should be used. Different models may result in, for example, more or less rapid response or aggressiveness of response.

[0249] In some examples, the controller may be configured to display a request for confirmation of the determined patient-specific model on a display and receive user input regarding the confirmation request, e.g., via a user interface. For example, the controller may show the determined patient-specific model on a display simultaneously with a prompt to the user to confirm or deny delivery of the gas flow using closed-loop control using the patient-specific model. Once the user confirms that the controller should proceed with the determined patient-specific model, the controller is configured to initiate closed-loop control of the oxygen concentration of the gas flow using the confirmed patient-specific model.

[0250] The delay time for the patient may include equipment delay time (delay associated with gas moving through the device and / or breathing circuit (breathing tube and / or patient interface)) and patient delay time (delay associated with oxygen transport within the body). The formula used to determine DT may include one or more variables and / or constants, such as flow rate Q, measurement delay t, measure , path volume V path , transportation delay t transport , and the correlation coefficient z may be used. measure t may have the dimension of time, and may have units of seconds, milliseconds, minutes, or any other suitable units. measure may account for delays arising from the instrument, e.g., pulse oximeter algorithms (which may include signal averaging). measure t may also include signal transmission and / or other communication delays. measuremay incorporate various delays into the electronic / algorithmic determination of the patient's current SpO2 value. path Q may have dimensions of volume, and may have units of liters or other suitable units. Q is a flow rate value having dimensions of volume over time, typically expressed in liters / minute. However, if DT is expressed in other units of time (e.g., seconds), V path The values ​​and / or Q values ​​may be appropriately converted to account for this. The flow rate Q may be the flow rate setpoint as specified or configured by the user (e.g., using a user interface), or the flow rate as measured by a device sensor (e.g., one or more flow sensors in the gas flow). If the respiratory therapy device is an NIV device or has an NIV mode, Q may be the average flow rate of the gas flow delivered through the breathing circuit (e.g., breathing tube and / or patient interface), minus any mask leakage flow. The delivery time t transport can have a time dimension. t transport t may represent the delay due to transport of oxygenated gas from the respiratory therapy equipment to the patient's lungs, and therefore the delay due to transport of oxygenated blood to the measurement site (e.g., most commonly a finger or toe). transport may be closely related to the length of the breathing tube (and / or other physical tube characteristics) and the height or length (or mass) of the patient. The correlation coefficient z may represent the correlation between delay time and the square root of flow rate.

[0251] The constants can be determined by empirical testing with adult patients and patient models. The constants can be used to account for various delay time factors, such as pulse oximetry averaging / algorithm delay, estimated transport delay of oxygenated blood to the measurement site, and estimated transport time of oxygenated blood. However, the use of estimates (e.g., transport delay) and flow-dependent terms derived from adult physiological data can make the output inappropriate for smaller patients.

[0252] In one embodiment, the formula for estimating the delay time for larger patients is:

number

[0253] In one embodiment, the formula for dynamically estimating the delay time for larger and smaller patients is as follows:

number

[0254] During the ceremony,

number

number

number

number

number

number

[0255] Determination of the delay term provides the controller to automatically account for devices with flow rate setpoints below a specified threshold. This can provide greater flow rate differentiation for smaller patients who require more rapid changes in FdO2 during therapy. The algorithm can be configured to account for the relationship between body weight and flow rate, and to account for transit time delays due to system flow paths and transport delays associated with the patient's circulatory system. In one example, for patients up to 12 kg, Q=2 L / kg / min.

[0256] Decay Time Constant A second time-related parameter used by the controller that can be automatically modified to account for smaller patients is the decay value (τ), also called the decay time or (exponential) decay time constant. The decay time constant relates to the patient's response to oxygen, describing the time it takes for SpO2 to decay to a stable value or a range of stable values ​​after a delay period following a change in FdO2. Decay time is a highly variable parameter (intra- and inter-patient). Intra-patient variability means that the decay time may be different for the same patient at different times. Intra-patient decay time may fluctuate or change (short-term and / or long-term) based on the patient's condition and other factors. Inter-patient variability means that the decay time may be different for different patients due to various factors, such as differences in physiology, condition, intra-patient variability, and magnitude. Means for estimating the time constant may include varying its value (in PID-Smith predictor controller tuning) until a best-fit model is found.

[0257] In one embodiment, the formula for estimating the decay time constant is as follows:

number

[0258] The formula is similar to the delay formula above in that it includes a min() function. The min() function serves the same purpose. The correlation coefficient x may represent the correlation between the decay time and the square root of the flow rate. As mentioned above, the measured delay t measure t may have a dimension of time and may account for delays arising from the instrument, e.g., pulse oximetry algorithms (which may include signal averaging). measure t may also include signal transmission and / or other communication delays. measure may incorporate various delays into the electronic / algorithmic determination of the patient's current SpO2 value.

number

[0259] Q max,infant In the example formula, where the specified limit of is 25, the decay constant is t measure +5x. This value can then be adjusted as part of the best fit determination process. If the flow rate was 9 L / min, the decay constant would be t measure +3x (also subject to optimal fit adjustment) and will be shorter than the time for larger patients with higher flow rates.

[0260] In some embodiments, formulas for delay and decay times to account for flow differences may be used only when one or more auxiliary patient type criteria or criteria associated with one or more physical characteristics of the patient are met. In these cases, flow-based timing parameter formulas are used, but only if additional criteria are met. This may help ensure that the appropriate formulas and controller functionality are used for the patient.

[0261] One additional criterion includes identifying a patient type based on the type of patient interface detected. For example, the type of patient interface (e.g., nasal cannula type) may be determined by a flow resistance or conductivity measurement / estimate by the respiratory therapy device (e.g., using a flow sensor internal to the device, or alternatively, a patient proximity sensor). The type of patient interface may be detected or identified as either an adult-sized nasal cannula or a pediatric-sized nasal cannula. Furthermore, the type of patient interface may be detected or distinguished between several sizes of pediatric-sized nasal cannula. In such an example, each different size nasal cannula may have prongs with a narrower or wider inner diameter. Depending on the flow resistance or conductivity estimate, the controller may determine the type of patient interface connected, for example, detect that an adult- or pediatric-sized nasal cannula is connected. Nasal cannulas with narrower inner diameter prongs present a higher resistance to flow than prongs with a wider inner diameter and, as such, may be appropriately identified or detected. For example, this may be done by measuring the resistance to flow and then comparing it to one or more thresholds or ranges to determine the appropriate nasal cannula to connect. Alternatively, the user may manually enter or select the type of patient interface (e.g., type of nasal cannula) to connect using the user interface 14 (e.g., from a displayed list).

[0262] Another supplemental criterion involves identifying the patient type based on the type of tubing detected. For example, tubing for adult, pediatric, infant, and neonatal patients receiving high-flow therapy may all have different internal diameters. The different diameters may be determined or detected using flow / air resistance as seen by the respiratory therapy equipment using flow and / or pressure measurements. As such, the flow and / or pressure measurements may be used by the controller to identify whether adult tubing is connected, or even more specifically, which particular tubing type is connected. Other methods known in the art may also be used (e.g., an identification register). Alternatively, the user may manually enter or select the type of tubing to be connected using the user interface 14 (e.g., from a displayed list).

[0263] Another supplemental criterion involves identifying patient type based on heart rate. Heart rate measured by a connected pulse oximeter (or a separate sensor or device) can be used to determine whether an infant or neonatal patient is using a therapy device. Infants and neonates may generally have a somewhat higher heart rate compared to the resting heart rate of an adult. For example, an infant or neonate may have a resting heart rate of 100-160 bpm (although some infants or neonates may sometimes have a HR slightly lower than 100 bpm or even higher than 160 bpm). This contrasts with the normal resting heart rate of an adult, which is generally 60-100 bpm. As such, the measured resting heart rate can be used as a supplemental criterion to identify patient type. For example, even children up to the age of 5 generally exhibit a higher resting heart rate of 80-140 bpm. Although the difference between children and adults often becomes less pronounced after age 5, children under 12-13 years of age may have resting heart rates above that of a typical adult, e.g., 70-120 bpm. However, some types of patients who do not necessarily require faster reaction times may also exhibit high heart rates (e.g., postoperative cardiac patients).

[0264] Another criterion involves using respiratory rate to distinguish between adult and neonatal patients. Neonates generally exhibit higher respiratory rates, especially when the neonate is experiencing respiratory distress. For example, infants and neonates may generally have a resting respiratory rate of 30-60 bpm (breaths per minute); children up to 5 years of age may have a resting respiratory rate of 20-40 bpm. Meanwhile, a normal resting respiratory rate for adults is 12-20 bpm. The difference gradually decreases for children under 12-13 years of age, who may have a resting respiratory rate in the range of 16-30 bpm. The patient's respiratory rate can be determined by a pulse oximeter and provided to the controller using flow data / measurements, or it can be determined by the controller itself. As such, the observed respiratory rate can be used as a supplemental criterion to distinguish between patient types. While there may be some overlap between the respiratory status of adults and neonates, neonates experiencing respiratory distress may have a respiratory rate well outside the adult range.

[0265] Alternatively, a user may manually enter or select values ​​for the patient's heart rate and / or respiratory rate using user interface 14 .

[0266] The controller may be configured to select the timing parameter formula to use based on the previous therapy type or mode (in the case of a multi-therapy mode device). For example, a respiratory therapy device can deliver bubble CPAP (BCPAP) therapy (with the correct device) as well as nasal high-flow (NHF) therapy. In such an example, when a switch from BCPAP to NHF occurs, the device's controller may select to use the faster controller configuration from the therapy mode. In some examples, the output from the bubbling detection algorithm (as part of a bubble CPAP therapy session) may be stored and later checked during startup of the closed-loop oxygen controller to identify whether the previous therapy session was actually bubble CPAP, which informs the controller that an infant may be connected to the device. In these examples, therefore, an indication of the previous therapy type may be used as a supplemental criterion for determining or identifying the type of patient connected to the device.

[0267] An exemplary bubbling detection algorithm may use measurements of flow and / or pressure in a gas flow path to generate flow and / or pressure waveforms. Based on identifying the presence of oscillations in one or more waveforms, the algorithm can detect whether bubbling is occurring. For example, the algorithm may attempt to identify the peak-to-peak amplitude of one or more waveforms, or the average of said amplitudes over a time window. If the amplitude exceeds a threshold, this may confirm the presence of bubbling. The bubbling detection algorithm may be any suitable bubbling detection algorithm, such as a bubbling detection algorithm of the type described in WO 2022 / 058982 A1, filed September 21, 2021, the contents of which are incorporated herein by reference in their entirety.

[0268] Controller Tuning As described herein, the PID-Smith predictor controller is tuned with relevant parameters including delay time, exponential decay time constant, and patient oxygen efficiency, the former two parameters once determined according to the above equations, being inputs to the PID and Smith predictor tuning process.

[0269] The delay time and exponential decay time constant are included in the learning phase. During the feedforward phase, the controller determines the change / delta in FdO2 to be used (i.e., step FdO2 change) appropriate for the patient.

[0270] An exemplary method 2900 for tuning a controller is shown in FIG. 29. In the exemplary method 2900, the tuning method 2900 first initiates closed-loop / predictive control in step 2902. The tuning method 2900 then proceeds to determine or identify the type of patient connected to the device in step 2904; for example, the tuning method 2900 may determine or identify whether the patient is a pediatric or infant patient. The patient type may be determined using one or more of the supplemental criteria as described above. The tuning method 2900 then proceeds to determine a suitable delay time (DT) in step 2906. The suitable delay time may be determined using the methods described above; for example, the tuning method may use a delay time algorithm based on the flow setpoint for the patient to determine DT. The tuning method 2900 then proceeds to determine or estimate a suitable decay time constant (τ) in step 2908. For example, the controller may estimate the decay time constant using an equation as described above. Once the patient type has been identified, the preferred delay time determined, and the preferred decay time constant determined / estimated, the tuning method proceeds to continue the PID and Smith Predictor tuning process in step 2910. In the PID and Smith Predictor tuning process, the patient type, delay time, and decay time constant are input into the PID and Smith Predictor tuning process as described.

[0271] Signal Weighting Referring to FIGS. 3 and 4, graphs 304 and 404 provide a signal quality indicator of a patient sensor. During use, the quality of the SpO2 signal from a patient sensor can vary. Patient sensors, such as pulse oximeters, can be inaccurate in some situations, such as when the pulse oximeter is being moved, resulting in poor quality data. Some patient sensors, such as pulse oximeters, can provide a signal quality indicator with each SpO2 reading. The signal quality indicator can be defined as an indication of the measurement accuracy of the patient sensor. The value of the signal quality indicator can be calculated on a defined scale, for example, 0 to 1, where 0 represents no signal and 1 represents the strongest signal. Data representing signal quality from a patient sensor can be processed in one or more ways, including fitting from a different scale (e.g., 0 to 5) to a system-defined scale (e.g., 0 to 1).

[0272] When tuning the PID controller (whether default, patient-specific, or predicted), expected periodic perturbations can be analyzed. Periodic perturbations are variations in SpO2 due to factors beyond the controlled variable (FdO2) and can introduce error into the SpO2 measurement. When tuning the PID controller, expected periodic perturbations can be estimated, and then the standard deviation of the SpO2 reading due to signal quality can also be estimated. SpO2 readings have a certain level of error between the measured value and the true value. This error can be represented by a measure of standard deviation. The standard deviation is inversely proportional to the signal quality.

[0273] Changes in signal quality can affect the error of SpO2 measurements, which in turn affects periodic perturbations in the system. This means that a previously tuned PID will go from tightly damped to overdamped (where the controller is unnecessarily slow) or underdamped (where the controller becomes unstable). Signal quality can be accounted for by weighting the control algorithm based on signal quality readings from the patient sensor. The control output can be multiplied by the signal quality to reduce the impact of data points with low signal quality. The goal is to dampen the PID controller when signal quality decreases and effectively retune the PID controller when the expected periodic perturbation changes.

[0274] Weighting can be applied to the change in FdO2 output by the PID control. The change in FdO2 is scaled relative to the most recent signal quality reading. For example, if FdO2 is 30% and the signal from the pulse oximeter indicates that the patient's SpO2 has dropped, the PID may command a 4% increase in FdO2 to bring it to 34%. However, if the signal quality of the measurement is only 0.5 and linear weighting is used, the increase may be damped to 2%, so the new FdO2 would only be 32%. The weighting allows the controller to continue to control the patient's SpO2, but does so slowly so as not to overcompensate for poor quality measurements.

[0275] The relationship between signal quality and control algorithm weighting may be defined by any function designed to represent the increase in noise as signal quality decreases, and is not limited to a linear function as described above. The relationship between signal quality and control weighting may be based on the correlation between signal quality and the standard deviation of the error.

[0276] By weighting the SpO2 measurement based on signal quality, the PID controller may be less affected by disturbances in the SpO2 measurement, such as motion artifacts and inadequate perfusion. Weighting the control algorithm by signal quality may result in a more robust and stable controller that can compensate for noisy data when signal quality deteriorates, while providing fast and accurate control when signal quality is high and the data is reliable.

[0277] Flow Therapy Device Control Process 9A-9C show a flowchart of a method for controlling operation of a flow therapy device during a high-flow therapy session. Process 900 and sub-processes 910 and 930 may be performed by any system capable of controlling operation of a flow therapy device. For example, process 900 may be performed in whole or in part by controller 13. Multiple different controllers may be configured to perform process 900. For example, different aspects of the process may be performed by the controllers. A remotely located system may be configured to perform portions of the process. For example, a remotely located system may be configured to perform system learning phase 910, and control phase 930 may be performed locally by controller 13. While any number of systems may perform process 900 in whole or in part, for simplicity of explanation, process 900 will be described with reference to specific components of controller 13 and flow therapy system 10.

[0278] In process 900, at block 902, a user may initiate a high flow therapy session with the flow therapy device 10. To initiate a therapy session, the flow therapy device may require specific information about the patient. For example, the input may include one or more patient characteristics, such as the patient type (e.g., normocapnic, hypercapnic, or other type), age, weight, height, gender, and / or other patient characteristics. The flow therapy device 10 may also request the user to set a target SpO2 value or range of values ​​for the patient. The flow therapy device may automatically determine the target SpO2 value based, at least in part, on the received patient characteristics. After receiving the information, the therapy session may be initiated by the user, and the process may proceed to block 910.

[0279] In block 910, the controller can execute a learning phase subprocess. The learning phase can generate a patient-specific model for use during the control phase. In some cases, the learning phase can fail to result in a default patient model to be used during the control phase 930. As described herein, the patient-specific model can be generated from a default model and then optionally updated during a treatment session without a defined learning phase.

[0280] 9B, the learning phase is described in further detail. In block 912, the controller executes a wait stage until the patient's SpO2 value stabilizes. During the wait stage 202, the oxygen inlet valve defaults to the previous FdO2 setting, and the valve may open and close as needed. The patient's SpO2 may change in response to high-flow therapy, and as such, the controller may wait until the SpO2 settles to a fairly constant value before proceeding to block 914. Optionally, the wait stage may be bypassed, and the process may proceed directly to block 914 without executing the wait stage in block 912.

[0281] In block 914, the controller may increase the oxygen concentration of the gas flow to a new level based on the target SpO2 level. The new FdO2 value may be preset or determined based on factors such as the patient's current SpO2. The new FdO2 may be selected by a clinician, who selects the FdO2 based on the clinician's own experience and knowledge. The selected FdO2 may bring the patient's SpO2 closer to the target SpO2 level. The FdO2 may be automatically determined by the controller 13.

[0282] In block 916, the controller measures and records patient and device parameters. The patient parameter may be SpO2, and the device parameter may be FdO2. The controller may measure and record FdO2 and SpO2 data. The actual FdO2 may rise to the target FdO2 over a defined period of time. Signal quality indicators from the patient sensors may also be recorded.

[0283] In block 918, the controller may analyze the relationship between the patient and device parameters and model the relationship. For example, the relationship may be between FdO2 and SpO2, and the controller may determine the relationship between the measured FdO2 and the time since the change in target FdO2. The relationship may be modeled using an exponential decay function, where the exponential decay constant is varied to best fit the model to the data. The initial and final FdO2 values ​​used in the exponential decay function may be set by the initial and final target FdO2 values. Modeling the relationship may be performed as further described herein.

[0284] In block 920, the controller can determine whether patient characterization criteria are met. The characterization criteria may specify tolerance ranges for at least some of the parameters used in calculating the patient model. For example, the characterization criteria may include a range of acceptable values ​​for a determined delay time between a change in FdO2 and the initial change in SpO2, a range of acceptable values ​​for the initial value of SpO2, a range of acceptable values ​​for the exponential decay rate that specifies how quickly SpO2 reaches its final value after the delay time, a range of acceptable values ​​for the rate of change between SpO2 and FdO2, and / or other parameters associated with generating the model. The characterization criteria may specify only minimum or maximum values ​​for the parameters. If the criteria are met, in block 922, the controller outputs a patient-specific model for use during the control phase. If the patient characterization criteria are not met, the process proceeds to block 924, where the controller determines whether the maximum time for the learning phase has been exceeded. If the time has not been exceeded, the controller continues to iterate on the model. If the time has expired, the controller uses a default patient model for the patient in block 926. The controller may restart the learning phase subprocess 910 one or more times if the patient characterization criteria are not met.

[0285] After the learning phase is complete, the model is output for use during the control phase in sub-process 930. The control phase sub-process is further described with reference to Figure 9C.

[0286] In block 932, the controller executes a PID controller based on the patient model output during the learning phase. The PID controller may be configured to control FdO2 based on the target SpO2. In block 934, the PID can predict SpO2 using a predictive algorithm, such as a Smith predictor. In block 936, the PID can determine an FdO2 value based on the predicted patient SpO2 value. In block 938, the PID controller can adjust the output of the FdO2 value based on a signal quality indicator associated with the patient sensor. In block 940, the model is adjusted based on the patient's response. The difference between the predicted SpO2 and the target SpO2 is calculated, and the result is fed back to the PID controller. In block 942, the controller determines whether the treatment session is complete. If the treatment session is not complete, the process begins again. If so, the treatment session ends.

[0287] Closed Loop Control Using Oxygen Efficiency In another configuration for implementing a closed-loop control system for flow therapy device 10, shown in Figure 10, flow therapy device 10 determines oxygen efficiency associated with a patient. Flow therapy device 10 may generate a patient model that uses the patient's oxygen efficiency during a therapy session.

[0288] Oxygen efficiency can be calculated where:

number

[0289] The oxygen efficiency of patients requiring supplemental oxygen may be lower than that of healthy individuals. For example, in healthy individuals, a change in FdO2 may cause a change in SpO2 that is twice as large as that of a patient with low oxygen efficiency. Having an indication of a patient's oxygen efficiency allows closed-loop oxygen control systems to run more efficiently.

[0290] As shown in FIG. 11 , the controller 13 can calculate the patient's oxygen efficiency. The controller can receive measured SpO2 and FdO2 values. The measured FdO2 value can be received from a gas composition sensor. Therefore, an instantaneous oxygen efficiency can be calculated based on the measured SpO2 and FdO2 values. The patient's overall oxygen efficiency can then be estimated by applying an on-the-fly filter to the instantaneous oxygen efficiency data. Filtering the instantaneous oxygen efficiency data can reduce variability in the estimate of the patient's overall oxygen efficiency. The controller can also prioritize more recent data. The instantaneous oxygen efficiency data can be weighted by pulse oximeter signal quality, so that instantaneous oxygen efficiency measurements made from data with low signal quality can reduce their impact on the estimate of the patient's overall oxygen efficiency. The instantaneous oxygen efficiency data can also be weighted based on the size of recent changes to FdO2, so that instantaneous oxygen efficiency measurements made from data following a large change in FdO2 can reduce their impact on the estimate of the patient's overall oxygen efficiency. This is because there is a delay between when a change in FdO2 is introduced and when the measured SpO2 changes. The controller may also consider whether the patient is cannulated when estimating the patient's oxygen efficiency. For example, the controller may ignore efficiency data from periods when the patient is not cannulated.

[0291] The device may constantly monitor and update an estimate of the patient's overall oxygen efficiency. The patient's overall oxygen efficiency may be used by multiple parts of the closed-loop control system, such as predictive models, tuning PID coefficients, and / or step changes before the feedforward stage. The patient's overall oxygen efficiency may be constantly updated as the estimate of the patient's instantaneous oxygen efficiency changes. The controller may start with an initial estimate of the patient's oxygen efficiency based on the typical oxygen efficiency of patients requiring supplemental oxygen. The overall oxygen efficiency may then be updated as data is received. A higher estimate of oxygen efficiency may result in a smaller change in FdO2, thereby reducing the risk of the patient receiving too much oxygen. A lower estimate may result in a larger change in FdO2, thereby allowing the controller to achieve the target SpO2 more quickly, but may cause overshoot.

[0292] In some configurations, the flow therapy device 10 may have an initial oxygen efficiency calculation phase to determine the patient's oxygen efficiency. In some configurations, the oxygen efficiency is not updated after the initial oxygen efficiency calculation.

[0293] Initiating a Closed-Loop Control Treatment Session A closed-loop control therapy session may be initiated by a user using interaction with a graphical user interface of the flow therapy device 10 as described herein. Closed-loop control requires that a patient sensor 26, such as a pulse oximeter, be connected to the patient and to the flow therapy device 10, and that the patient sensor signal quality be at an acceptable level. Before closed-loop control begins, the user must set operating parameters for FdO2 and SpO2. Various methods for selecting these operating parameters are described herein.

[0294] FdO2 may have a control range with upper and lower control limits. A user can select the upper and lower limits of the FdO2 control range. The difference between the upper and lower limits may be fixed. The control range may be fixed to a defined difference in oxygen concentration, such as 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, and 50%, and / or any other range of difference between the above values. Thus, a user can select a particular FdO2 range, such as 25%-45%, 52%-72%, 80%-100%, or any other range. A user can change the value of the FdO2 control limit in 1%, 2%, 5%, or other increments.

[0295] The flow therapy device may have a lower limit of 21% and an upper limit of 100% for the FdO2 control range. The FdO2 control range may be truncated by the limit of oxygen concentration that the device can conveniently deliver (e.g., 95%, 90%, or lower). For example, the gas source connected to the oxygen inlet valve may be an oxygen-enriched gas stream, where the oxygen content of the source may be less than pure oxygen (i.e., 100%).

[0296] The flow therapy device may include various configuration options for setting limits for the FdO2 control range. For example, a user can input the oxygen concentration of the oxygen source; the flow therapy device may be pre-programmed with an upper limit during manufacture that cannot be changed; the upper limit may be changed by a technician but not by the average user; the user can input the oxygen source type (e.g., connector, oxygen bottle, etc.) and the flow therapy device can determine the appropriate limit; and / or the flow therapy device can measure the oxygen concentration of the gas coming from the oxygen source.

[0297] Additionally, the flow therapy device may issue an alarm if it is unable to achieve the target oxygen concentration. The alarm may serve as a fail-safe in situations where a control range is selected that exceeds the concentration of the oxygen source. For example, if the control range is 80%-100% when connected to a 90% oxygen source, the flow therapy device will not be able to go above 90% and will trigger an alarm.

[0298] If a user attempts to lower the FdO2 control range above the upper or lower limit, respectively, the control range may be truncated. For example, if a user attempts to lower the control limit from 21% to 41%, the upper limit may continue to be lowered, but the lower limit remains at 21%. This results in a control range narrower than 20% (e.g., 21% to 35%). The control range may also have a lower limit relative to its size (e.g., 5%, 10%, 15%, etc.). The lower limit may be based on the size of the control range. For example, the lower limit may be half the size of the control range. Specifically, when one limit of the control range is at its physical limit (i.e., 21% or 100%), the other limit may be at least 10% above or below the other limit. In such a configuration, the lowest and highest possible control ranges are 21% to 31% and 90% to 100%, respectively. The controller can vary FdO2 between the upper and lower limits of the control range to maintain SpO2 within the patient's target range.

[0299] As described herein, a user can manually set a target SpO2 range. In some configurations, instead of manually selecting a target SpO2 range, a user may select a patient type, and the controller then selects predetermined SpO2 control limits based on the patient type. Examples of patient types may include "normal," such as a defined SpO2 control range of 90%-98%, 92%-98%, 92%-96%, or within another defined range, or "hypercapnic," such as a defined control range of 88%-92%, 86%-90%, 88%-90%, or another defined control range.

[0300] To maintain a patient's SpO2 within a target range, the controller may target the center of the patient's target range. The limits of the target range may further serve as alarm limits. For example, for a "normal" patient with an SpO2 target range of 92% to 96%, the device may target an SpO2 value of 94%. Thus, the device will sound an alarm if the patient's SpO2 value falls outside the 92% to 96% range. The flow therapy device may have additional alarms set at defined limits that are independent of the selected SpO2 control range. For example, the flow therapy device may sound an alarm at 50%, 60%, 70%, 75%, and / or 80% to indicate a patient's oxygen desaturation.

[0301] The flow therapy device 10 may include a configuration menu that may allow some or all of these values ​​to be changed. The configuration menu may be protected by a PIN or similar password feature to prevent certain users from accessing these settings. For example, the configuration menu may be intended to be inaccessible to general users (such as patients or nurses), but may instead be designed to be accessible to anyone who configures the device (such as a technician or manufacturer).

[0302] In the configuration menu, the limits that can be selected for the FdO2 control range can be modified. For example, the device can be configured so that the upper limit of the FdO2 control range cannot exceed 90%. The set limits of the control range can serve as a safety feature by preventing the device from delivering excessively high and / or low oxygen concentrations. Furthermore, the limits can be set based on what the device is capable of delivering. For example, if the device is connected to an oxygen-enriched source containing gas with a 90% oxygen concentration, the device will not be able to achieve 100% FdO2. In this situation, the upper limit of the selectable FdO2 control range should be set to 90% or less.

[0303] The size of the FdO2 control range may also be changed in a higher level menu. For example, the size of the control range may be set to 10%, 15%, 20%, 27%, 30%, 36%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, or any other control range. The control range may be reduced, for example, by half, when one of the above limits is reached. For example, if the FdO2 lower limit is 21% and the range is set to 40%, the lowest selectable range is 21% to 41%.

[0304] The SpO2 target range can be manually set by the user. The SpO2 target range for each patient type can potentially be changed in the configuration menu. Additionally, the device can have additional patient types that can be made selectable through the configuration menu. For example, an additional patient type can be labeled "Other" and include a customizable SpO2 target range. The upper and lower limits of the SpO2 target range for each patient type can be varied from 80% to 100% in 1% increments.

[0305] During a therapy session, the SpO2 controller and FdO2 controller can automatically control the operation of the flow therapy device until the therapy session ends or an event causes a change from automatic mode to manual mode.

[0306] During a therapy session, the graphical user interface may display a graphical indicator of oxygen efficiency. The oxygen efficiency characteristic displayed in the graphical user interface may be an output value based on SpO2 and FdO2. Another oxygen efficiency characteristic may be a function of the determined oxygen efficiency and the patient's respiratory rate. If the oxygen efficiency characteristic is a function of the determined oxygen efficiency and the patient's respiratory rate, it may be calculated by dividing SpO2 by FdO2 and then dividing this value by the respiratory rate. The oxygen efficiency characteristic value may be recorded and displayed in graph or trend line format to show how the value changes over time. The graphical user interface may be configured to display each of the oxygen efficiency characteristic and the respiratory rate oxygen efficiency characteristic individually or together. For example, values ​​associated with each characteristic may be displayed together on the same screen or on separate screens (e.g., a user may navigate to a different screen within the interface to view different characteristics). Graphs or trend lines may be configured to display each characteristic individually or together on the same screen.

[0307] 12 shows a graph 1200 of SpO2 and FdO2 illustrating the phases of operation of a flow therapy device during a treatment session. FdO2 (fraction of oxygen delivered) is used in the graph, but as noted above, FdO2 is substantially the same as FiO2, as long as the flow rate meets or exceeds the patient's peak inspiratory demand.

[0308] The operational phases may include a wait stage 1212, a step change 1214, a feedforward stage 1216, and a control phase 1220. Once the control limits are set, the flow therapy device 10 may enter a wait stage 1212. The wait stage 1212 allows the SpO2 sensor to settle and allows for the collection of some initial data, such as SpO2, FdO2, signal quality, and other parameters. In particular, an initial estimate of the patient's oxygen efficiency may be determined. If the patient is already using the device in manual oxygen control mode with an SpO2 sensor attached, the device may already have an estimate of the patient's oxygen efficiency. In that case, collected data may be used to continue updating this estimate.

[0309] In this configuration, the wait stage 1212 may be extended for a predetermined period of time, which may be between 1 second and 60 seconds, or between 2 seconds and 30 seconds, or between 3 seconds and 15 seconds, or between 4 seconds and 10 seconds, 5 seconds, or any other period within the ranges mentioned above.

[0310] During the wait stage 1212, the device may also evaluate the data to determine what action to take during the subsequent feedforward stage 1216. Prior to the feedforward stage 1216, the controller may perform a step change 1214 in FdO2. The flow therapy device may make a step change in FdO2 in an attempt to bring the actual SpO2 into or close to a target range. After making the step change in FdO2, FdO2 may be held constant for a defined duration during the feedforward stage 1216 to allow the patient's SpO2 to settle.

[0311] Near the end of the wait stage 1212, data regarding several parameters may be evaluated to determine the magnitude of the step change 1214 and whether the feedforward stage 1216 should be executed. First, the patient's SpO2 may be compared to a target SpO2 range. When the patient's SpO2 is within or above the target range, the step change 1214 and the feedforward stage 1216 may be bypassed, and the controller transitions directly from the wait stage 1212 to the control phase 1220. If the patient's SpO2 is below the target range, the controller can determine whether a step change 1214 is required. For example, a recent large change in FdO2 may mean that a step change 1214 in FdO2 is not required. If a step change 1214 is required, the device proceeds with the step change 1214 following the end of the wait stage 1212.

[0312] In step change 1214, the controller decides to implement a change in FdO2, the magnitude of the step change being based at least in part on the current SpO2, the target SpO2, and oxygen efficiency.

[0313] Due to the delay between a change in FdO2 and when the change in SpO2 appears, there may be changes in FdO2 that do not yet have an effect when calculating oxygen efficiency. The flow therapy device 10 may take into account any recent changes in FdO2 when determining the predicted SpO2, oxygen efficiency, and step change magnitude.

[0314] During the feedforward stage 1216, the controller may maintain FdO2 at the determined FdO2. If no step change 1214 occurs, FdO2 may be maintained at the current FdO2 value. If there is a step change 1214, the determined FdO2 is the previous measured FdO2 plus the magnitude of the step change. The feedforward stage 1216 may continue until a maximum time specified for the feedforward stage (e.g., 60 seconds, 120 seconds, or another specified maximum duration) is reached, or until the measured SpO2 is at the target SpO2 value and / or within the target SpO2 range. After the feedforward stage 1216 ends, the control phase 1220 begins.

[0315] Predictive control during the control phase During the control phase 1220, the controller varies FdO2 within the control range to achieve the target SpO2. In rate form, the equation for determining the target FdO2 during the control phase is:

number

[0316] In the formula, E SpO2 is the error function, and K P , K. I and K. D are the PID coefficients. The error function represents how far the patient's SpO2 is from the target SpO2 and is calculated differently depending on whether a Smith Predictor is used. In some configurations, the error function may also be filtered with a first-order low-pass Butterworth filter to remove random measurement errors.

[0317] As described herein, the PID coefficients can be tuned to better achieve a patient's target SpO2. Additionally, the PID coefficients can also be weighted by the inverse of the patient's oxygen efficiency, causing the controller to provide greater changes in the patient's FdO2 at lower oxygen efficiencies to achieve consistent changes in SpO2.

[0318] If the default PID or a tuned PID is used, the error function is: E SpO2 (t)=SpO2 Measured (t)-SpO2 Target

[0319] As described herein, the PID coefficients may be tuned based on patient characteristics. Additionally, a Smith predictor may be used to eliminate the pure time delay between when a change in FdO2 is introduced and when a corresponding change in SpO2 is detected. The delay time may be estimated based on the flow rate of the flow therapy device 10.

[0320] The Smith Predictor can use a model of the patient's SpO2 response based on changes in FdO2. Using the model, the Smith Predictor can make a prediction of what the SpO2 will be after a delay time.

[0321] The predicted value is continually corrected using a disturbance term that represents the error between the modeled and measured SpO2. Once an initial SpO2 prediction is made, the predicted value is adjusted by incorporating the disturbance term. Combining these parameters gives a disturbance-adjusted predicted SpO2 value. This value is then used to calculate the error function. If the model and estimated delay time are sufficiently accurate, the Smith Predictor PID will perform similarly to the default or tuned PID used in patients without a delay time.

[0322] As described herein, in some configurations, the Smith Predictor model may be evaluated with respect to SpO2 using an accumulation of changes in FdO2 multiplied by a coefficient that represents the relationship between changes in FdO2 and changes in SpO2. The coefficient is patient-specific and is generated using an initial estimate. As such, the coefficient is continually updated based on live data (e.g., SpO2 and FdO2) received from the patient. The coefficient may be updated during all phases of the closed-loop control mode and is not limited to a specific learning phase.

[0323] A coefficient used in the Smith Predictor model may be the patient's oxygen efficiency, which is constantly evaluated and updated in the model's algorithm. As described herein, the oxygen efficiency estimate is updated throughout the wait stage, feedforward stage, and control phase, and during manual mode if a pulse oximeter is used.

[0324] PID Controller Weighting As described herein, the control signal may be weighted depending on the signal quality from the patient sensor 26. In addition, the control signal may also be weighted depending on whether the measured SpO2 is above or below the target value. When the measured SpO2 is below the target, the weighting may be 1 or greater, 1-2, 1.1-1.75, 1.2-1.5, 1.25, or any value or range within the aforementioned ranges. When the measured SpO2 is above the target, the weighting may be 1 or less, 0.25 and 1, 0.5-0.9, 0.75-0.85, 0.8, or any value or range within the aforementioned ranges. This not only allows the controller to more quickly increase the oxygen concentration when the SpO2 is too low, but also reduces the chance of overshooting the SpO2 target when the SpO2 is too high and oxygen concentration is decreasing. This weighting process may help reduce the time the patient receives a lower concentration of oxygen.

[0325] Flow Therapy Device Control Process 13A-13C show a flowchart of a method for controlling operation of a flow therapy device during a high-flow therapy session. Process 1300 and sub-processes 1310 and 1330 may be performed by any system capable of controlling operation of a flow therapy device. For example, process 1300 may be performed in whole or in part by controller 13. Multiple different controllers may be configured to perform process 1300. For example, different aspects of the process may be performed by the controllers. A remotely located system may be configured to perform portions of the process. For example, a remotely located system may be configured to perform system setup phase 1310, and control phase 1330 may be performed locally by controller 13. While any number of systems may perform process 1300 in whole or in part, for simplicity of explanation, process 1300 will be described with reference to specific components of controller 13 and flow therapy system 10.

[0326] In process 1300, at block 1302, a user may initiate a high flow therapy session with the flow therapy device 10. To initiate a therapy session, the flow therapy device may require specific information about the patient. For example, the input may include one or more patient characteristics, such as the patient's type (e.g., normocapnic, hypercapnic, or other type), age, weight, height, sex, and / or other patient characteristics. The flow therapy device 10 may also prompt the user to set a target SpO2 value or range of values ​​for the patient. The flow therapy device may automatically determine the patient's target SpO2 value or range of values ​​based, at least in part, on the received patient characteristics. After receiving any required information, the therapy session may be initiated by the user, and the process may proceed to block 1310.

[0327] At block 1310, the controller may execute a setup phase. The setup phase subprocess 1310 is described with further reference to FIG. 13B. At block 1312, the controller waits a defined period of time before proceeding. The wait time may provide a period for the patient's SpO2 value to settle. During the wait stage 1212, the oxygen inlet valve may default to the previous FdO2 setting, and the valve may open or close as needed.

[0328] In block 1314, during the waiting stage, the controller measures and records patient parameters and device parameters. The patient parameter may be SpO2, and the device parameter may be FdO2. The controller can measure and record FdO2 and SpO2 data. The controller can determine oxygen efficiency based on SpO2 and FdO2.

[0329] In block 1316, the controller can determine whether the patient's SpO2 is within or above the target SpO2 range. If the target is already within or above the target SpO2 range, the process bypasses the step change and feedforward stages and proceeds directly to the control phase in block 1322. If the patient's SpO2 value is not within the target range, the process proceeds to block 1317.

[0330] In block 1317, the controller can determine whether FdO2 is at an acceptable level. If FdO2 is already at an acceptable level due to a recent change in FdO2, no further adjustment to FdO2 is needed before the feedforward stage, and the process bypasses the step change and proceeds directly to block 1320. If FdO2 is not at an acceptable level, the process proceeds to block 1318.

[0331] In block 1318, the controller can implement a step change in oxygen concentration. The controller can implement a step change to increase the oxygen concentration of the gas flow to a new level based on the target SpO2 level, FdO2, and oxygen efficiency. The new FdO2 value can be determined based on factors such as the patient's current SpO2. The new FdO2 can be selected by a clinician, who selects the FdO2 based on the clinician's own experience and knowledge. The selected FdO2 can bring the patient's SpO2 closer to the target SpO2 level. The FdO2 can be automatically determined by the controller 13.

[0332] In block 1320, the controller may execute a feedforward stage. During the feedforward stage 1216, the controller maintains FdO2 at a determined value for a determined time. When the controller bypasses a step change, the controller may proceed with the feedforward stage without changing FdO2. The feedforward stage 1216 may continue until a maximum time specified for the feedforward stage is reached (e.g., 120 seconds) or until the measured SpO2 is at the target SpO2 value and / or within the target SpO2 range. After completion of the feedforward stage, the process proceeds to block 1322 to begin the control phase subprocess 1330. The control phase subprocess 1330 is further described with reference to FIG. 13C.

[0333] In block 1332, the controller executes a control phase using a PID controller to control the performance of the flow therapy device 10. The PID controller may be configured to control FdO2 based on the target SpO2 and the measured SpO2. In block 1334, the controller can predict SpO2 using a predictive algorithm, such as a Smith predictor. In block 1336, the controller can determine a target FdO2 value based on the predicted patient SpO2 value. In block 1338, the controller can determine oxygen efficiency based on the measured SpO2 value and the measured FdO2. In block 1340, the controller can adjust the output of the FdO2 value based on a signal quality indicator associated with the patient sensor. In block 1342, the controller control signal to the oxygen valve is adjusted. The difference between the predicted SpO2 and the target SpO2 is calculated, and the result is fed back to the PID controller to control the oxygen valve. In block 1344, the controller determines whether the therapy session is complete. If the treatment session is not complete, the process continues until the treatment session is finished.

[0334] Motor and / or sensor module configuration The configuration of flow therapy device 10 is shown in Figures 14-16. The flow therapy device includes a main housing 100. Main housing 100 has an upper main housing casing 102 and a lower main housing casing 202.

[0335] 14 and 15, the lower housing 202 has a motor recess 250 for receiving a removable or non-removable motor and / or sensor module 400, as shown in FIGS. 13-15 and described in further detail below. A recess opening 251 is provided in the bottom wall 230 adjacent its rear edge for receiving a removable or non-removable motor / sensor module 400, as shown in FIGS. 13 and 15 and described in further detail below.

[0336] 16-19 show in more detail the motor and / or sensor module or subassembly 400. As mentioned above, the lower housing 202 includes a recess 250 for receiving the motor and / or sensor module 400.

[0337] 16-19, motor and / or sensor module 400 includes three main components: a base 403 of subassembly 400 (on which motor 402 is positioned), an outlet gas flow path and sensing layer 420 positioned above base 403, and a stacked arrangement of cover layer 440. Base 403, sensing layer 420, and cover layer 440 are assembled to form a subassembly housing having a shape complementary to that of recess 250 so that subassembly 400 can be received in recess 250. Base 403 is configured to close recess opening 251 when subassembly 400 is positioned within recess 250. Subassembly 400 can be maintained in place within the recess in any suitable manner, such as with fasteners, clips, or quick release arrangements, or can be permanently secured.

[0338] The sensing layer includes a gas flow path with one or more sensors, the gas flow path being arranged to supply gas to an outlet port of the housing.

[0339] Motor 402 has a body 408 that defines an impeller chamber that houses an impeller. Motor 402 may be any suitable gas blower motor, and may be, for example, a motor and impeller assembly of the type described in WO 2013 / 009193, the entire contents of which are incorporated herein by reference.

[0340] The gas outlet 406 is in fluid communication with an outlet gas flow path and a gas inlet of a sensing layer 420 stacked on top of the motor. This layer 420 includes a body 422 including a plurality of mounting legs 425 that can be inserted into a plurality of mounting slots (not shown) in the base 403 to secure the body 422 to the base 403. In one configuration, the body 422 defines a gas flow path that couples the gas outlet 406 to the gas flow path and the gas inlet of the sensing layer 420.

[0341] The body 422 defines a lower portion 426 of the sensing and gas flow passages. The cover layer 440 has a body 442 that defines an upper portion 446 of the sensing and gas flow passages, the shapes of the upper and lower portions 426, 446 substantially corresponding to one another.

[0342] 17 and 18, the gas flow path includes a linear, elongated gas flow section 428, 448. The inlet is in fluid communication with a tangential gas flow path inlet section 430, 450 located at or adjacent the inlet end of the linear, elongated gas flow path section 428, 448. Recesses 433, 453 and 434, 454 may be provided at opposite ends of the linear, elongated gas flow path section.

[0343] Gas outlet ports 452 extend vertically through the body 442 of the cover layer 440 and are positioned at or adjacent opposite outlet ends of the linear elongated portions 428, 448 of the gas flow path. The gas outlet ports 452 are in fluid communication with the upper portion of the motor recess 250, which is in turn in fluid communication with the gas flow path. Again, due to the configuration of the walls 252 and ceiling 262 of the recess 250, if there is a gas leak from the motor / sensor module 400, the gas will be vented to the atmosphere rather than entering the portion of the main housing 100 containing most of the electronics and controls. The recess 250 may include one or more spacers, such as lugs projecting downwardly from the ceiling 262, as shown in FIG. 15 , to maintain suitable spacing for gas flow from the gas outlet ports 452 and the recess ceiling 262.

[0344] 17, it can be seen that at least a portion of the gas flow path through and exiting the motor and / or sensing module 400 has a serpentine or undulating configuration. For example, the direction of gas flow traveling through the elongated portions 428, 448 is generally opposite the direction of gas flow traveling from the gas outlet port 452 to the inlet of the gas flow path through the elbow 324.

[0345] 18 and 19, the cover layer 440 includes a sensing printed circuit board (PCB) 456. The cover layer 440 may also include one or more temperature sensors, such as thermistors, mounted on the elongated portions 428, 448 of the gas flow path. One sensor may measure the temperature of the gas, and the other sensor may act as a redundant temperature sensor. Alternatively, one of the thermistors may be used as a reference flow sensor (e.g., by using it as a constant temperature thermistor), and the measured temperature may be used to determine the gas flow rate through the portions 428, 448 of the gas flow path. One or more temperature sensors may be located on a portion of the sensing PCB 456 that faces the gas flow. The sensing PCB 456 may further include other sensors, including, but not limited to, pressure sensors, humidity sensors, and dew point sensors.

[0346] One or both of the electronic boards 272 are in electrical communication with or coupled to the sensors to process information received from the sensors and operate the device 10 based on the information received from the sensors.

[0347] In an alternative configuration, the motor / impeller unit may be provided at a location remote from the device 10. In that configuration, the module received in the recess 250 may include only the gas flow path and various sensors to supply gas to the fixed elbow 324 and thereby to the liquid chamber 300. In an alternative configuration, the module received in the recess 250 may include only the motor and gas flow path, but not the sensors.

[0348] In another alternative configuration, the motor and / or sensor module 400 may not be removable from the recess 250, but rather may be permanently attached thereto, while still providing the benefits of isolating the gas from the electrical / electronic components.

[0349] The flow path is compact and has fewer curves / sharp turns, thereby reducing flow separation and lowering resistance to flow.

[0350] The motor and flow path arrangement provides another layer of insulation for the wall arrangement.

[0351] By having a modular motor and / or sensor module, the various parts of the module can be disassembled if cleaning and / or repair is required.

[0352] Advantageously, there are no leak paths in the motor and / or sensor module, which may have potential leak points, and a leak in that area would allow oxygen to be released into the atmosphere or liquid chamber.

[0353] Valve Module 20-28 show a first configuration of valve module 4001. Valve module 4001 controls the flow of oxygen and / or other gases into the gas flow path of device 10 and allows device 10 to regulate the proportion of oxygen drawn into the air flow. The valve module is formed as a modular unit for ease of manufacture, assembly, repair or replacement, for example, in the event of malfunction, routine maintenance or future upgrades / modifications.

[0354] The valve module 4001 is inserted vertically upward into the valve module receptacle 306 in the lower casing 202 of the main housing. In alternative configurations, the valve module may be insertable into the housing in different orientations, such as forward, downward, rearward, or sideways. The valve module 4001 is removably engageable with the main housing of the device such that the valve module 4001 is substantially received in the housing and accessible from the exterior of the housing. In some configurations, the valve module 4001 can be fixed within the main housing and not removable. When the valve module is removably engaged with the housing, a portion of the valve module 4001 is positioned substantially flush with the exterior wall of the housing.

[0355] Because the valve module is modular and accessible from the exterior of the housing, the valve module can be replaced without significant disassembly of the device 10 and without compromising the device's housing seal. Because the valve module 4001 is substantially received within the housing, when the valve module is engaged with the housing, it becomes integral with the housing and does not increase the size or bulk of the housing. Furthermore, the components of the valve module, such as the valve 4003 and valve manifold 4011 described below, are protected during use because they are positioned within the valve support 4051 and the device's main housing. This configuration significantly reduces the likelihood of damage to the valve module and its components if the device 10 is inadvertently knocked or dropped.

[0356] The valve module includes a flow control valve 4003 arranged to control the flow of gas through the valve manifold 4011. The valve is arranged to control the flow of gas to a portion of the apparatus. For example, the valve may be arranged to control the flow of gas to the filter module 1001. Alternatively, the valve 4003 may be arranged to control the flow of gas to another portion of the apparatus. The valve module 4001 and the filter module 1001 are positioned upstream of the blower 402 and the motor and / or sensor module 400. In some embodiments, the valve module 4001 and the filter module 1001 are positioned downstream of the blower 402.

[0357] Valve 4003 includes a cylindrical body 4005 and a valve member within the body.

[0358] The flow control valve may be, for example, a solenoid valve, motor driven, or piezo operated.

[0359] In a solenoid valve, a valve member is actuated between an open position and a closed position. A solenoid valve may be a proportional valve: the amount of gas flow through the valve (i.e., due to the valve opening size) is a function of the current supplied to the valve.

[0360] Alternatively, the solenoid valve may be controlled by a modulated input signal so that the valve is modulated between open and closed positions.

[0361] The valve 4003 can be a needle valve, plunger valve, gate valve, ball valve, butterfly valve, globe valve, etc. The valve can be of the pressure compensated type.

[0362] In some configurations, the valve is a normally closed valve, i.e., the valve is closed when power is off, thereby preventing the connected gas supply line from continuously venting oxygen or other gases when the device is powered off. In some alternative configurations, the valve is a normally open valve.

[0363] In some configurations, the valve 4003 is an electrically actuated proportional solenoid valve. For example, the valve may be a μProp valve available from Staiger GmbH & Co. KG (Erligheim, Germany) or an Asco 202 series Preciflow valve available from Emerson / Asco Valves (New Jersey), or any other suitable type of valve.

[0364] The valve may have a coaxial inlet-outlet configuration.

[0365] The valve module 4001 includes a valve manifold 4011 having a body 4013 that defines a gas flow path 4015 between a valve manifold gas inlet 4017 and one or more valve manifold gas outlets 4019. The valve manifold gas inlet 4017 is axially disposed at or toward the end of the valve manifold. In some configurations, the valve manifold 4011 has a single gas outlet 4019 that is radially disposed about the valve manifold. In some configurations, the valve manifold 4011 includes multiple valve manifold gas outlets 4019 that are radially disposed about the valve manifold. The valve manifold outlets 4019 are positioned to deliver gas from the valve manifold gas inlet 4017 to the gas inlet of the filter module 1001. The radial placement of the outlet(s) 4019 helps direct oxygen (or other gases) toward the filter module, minimizing oxygen loss and increasing draw efficiency. Valve 4003 is positioned to control the flow of gas from a valve manifold gas inlet 4017 to one or more valve manifold gas outlets 4019. When the valve is "closed," gas flow is prevented from the gas inlet 4017 to one or more gas outlets 4019. When the valve is "open," gas flow is allowed from the gas inlet 4017 to one or more gas outlets 4019.

[0366] An end 4018 of the valve manifold 4011 opposite the gas inlet receives and sealingly engages the valve 4003, placing the valve and the valve manifold in fluid communication. The end 4018 includes a flange 4023 for attachment to the valve. The flange 4023 has apertures that receive fasteners 4024, 4025 for fastening the manifold to the valve 4003. One or more O-rings are provided around the periphery of the interface between the valve 4003 and the valve manifold 4011 to sealingly engage the valve with the valve manifold.

[0367] The valve manifold 4011 directs / disperses the oxygen from the valves through radially arranged gas outlets 4019. In some embodiments, a single gas outlet 4019 is provided in the valve manifold. As the oxygen passes through one or more outlets, noise is generated. Because ventilators may be used in close proximity to patients in medical and / or home environments, it is desirable to minimize the noise generated.

[0368] Additionally or alternatively, to reduce noise, a hood, duct, or channel may be formed around, near, or in fluid communication with one or more valve manifold outlets 4019. Additionally and / or alternatively, foam or the like may be placed around the valve manifold and near the valve manifold outlets to reduce noise.

[0369] A small filter is provided within the inlet of the valve manifold gas inlet 4017 to prevent dust or particulates from being introduced into the valve.

[0370] The end of the valve manifold corresponding to the gas inlet 4015 is arranged to receive and connect to a connector 4031. In the form shown, the connector 4031 is a swivel connector. Alternatively, the connector 4031 can be arranged so that the gas inlet 4033 of the connector can move in different ways, for example, translationally or pivotally.

[0371] Valve module 4001 is located at the beginning of the device's flow path. If valve 4003 becomes blocked (i.e., by dust, particulates, etc.), excess pressurized oxygen or other gas is "bumped out" through one or more ambient air inlet openings in valve support 4051 so that it remains open (e.g., in FIG. 26, the openings are shown just below the swivel connector). This prevents any excess pressure from reaching the patient. As such, the system can be considered inherently pressure limited without the use of a pressure relief valve.

[0372] One or more openings 4052 are provided in the valve support 4051 to draw ambient air into the gas flow path of the device. The ambient air flow path passes near or adjacent to the valve. In the illustrated embodiment, the openings 4052 are located around the gas inlet of the swivel connector. Additionally or alternatively, openings may be located elsewhere in the valve support. When the blower motor 402 of the device is operated, suction is created through the filter module and valve module, drawing ambient air into the device. The ambient air flow path passes through the valve module and allows ambient air to be drawn in along with the gas flow from the flow control valve. The ambient air flow path has a gas outlet adapted to supply ambient air so that the ambient air flows past one or more temperature sensors of the device to supply the gas flow.

[0373] The device may simultaneously draw gas and ambient air from a gas inlet of the valve manifold, or may pressurize gas from the gas inlet to force the gas through a filter. Gas flows out of the valve module and into the gas inlet in the filter. The device may be configured such that gas and ambient air from the gas inlet are dynamically drawn into / mixed within the device before being delivered to a gas outlet of the device.

[0374] The valve module may be configured to have one or more of: large openings 4052 for ambient air located around the swivel connector and / or elsewhere; rounded / rounded / beveled edges in the flow path (i.e., for example, in the valve manifold) to minimize pressure drop across the valve module, minimizing turbulence and smoothing the flow.

[0375] The valve module 4001 described herein is positioned to mate directly with the filter 1001 to provide a gas flow path from the valve module to the filter. No hose connections are required between the valve module and the filter module. This minimizes component size and simplifies connection and disconnection of the modular valve module from the filter module.

[0376] The filter and valve modules described herein may provide various gas flow paths to the device. For example, a valve module may control the flow of oxygen through the valve and filter modules and into the gas flow paths of the device. Alternatively, the valve module may be bypassed by connecting an alternative oxygen source directly to the filter module via a first subcompartment gas inlet (e.g., inlet 1011 in FIG. 24). This may be practical in situations where a user wants to manually adjust the oxygen source (i.e., via a wall-supplied rotameter, etc.).

[0377] It is understood that the filter modules and valve modules described herein may be used separately in an apparatus for providing a flow of gas, or alternatively, the filter and valve modules may be used together as a filter and valve assembly for enhanced functionality.

[0378] In the illustrated configuration, the device 10 receives oxygen by at least one of the following: via a valve module (automatic oxygen regulation by the device) or via an alternative gas inlet provided on top of the filter (allowing for attachment of a manually adjustable oxygen source - i.e., by a wall-fed rotameter, etc.).

[0379] The various configurations described are merely example configurations: any one or more features from any of the configurations may be used in combination with any one or more features from any of the other configurations.

[0380] For example, swivel connectors used in valve modules may have additional functionality. In some configurations, the swivel connector may be arranged to swivel about two or more axes, and may have two adjacent swivel connection portions with, for example, axes of rotation perpendicular to one another, so that the gas inlet of the swivel connector can rotate about two axes. In some configurations, the swivel connector may include a ball-and-socket arrangement or the like, allowing the gas inlet of the swivel connector to rotate in substantially any direction. In some configurations, the swivel connector may be arranged to provide both swivel and translational motion, such that the swivel connector gas inlet can swivel about, for example, about one or more axes and also move linearly. This may be useful, for example, for translating the gas inlet from one portion of a device to another, such as from one side of the device to the other side of the device. In some configurations, the gas inlet may be arranged to translate instead of rotate.

[0381] As another example, the motor and / or sensor subassembly recesses are described as being on the underside of the main housing, but could instead be on the rear, side, front, or top of the housing. In such variations, the air and / or oxygen inlets could also be positioned differently as needed.

[0382] As another example, rather than being configured so that the liquid chamber is inserted into and removed from the chamber space from the front of the housing, the configuration may be such that the liquid chamber is inserted into and removed from the chamber space from the side, rear or top of the housing.

[0383] As another example, although the filter module is described as being inserted into the housing from above and the valve module is described as being inserted into the housing from below, either or both of those components may be inserted into any suitable part of the housing, top, bottom, side, front or rear.

[0384] The filter module and valve module are described with reference to a flow therapy device capable of delivering heated and humidified gas to a patient or user. The device may be suitable for treating chronic obstructive pulmonary disease (COPD). The device may be configured to deliver gas to a patient interface at high flow rates (high flow therapy), particularly nasal high flow therapy.

[0385] Alternatively, the filter module and / or valve module may be used in a device for different purposes. The device may be a high-flow therapy device or a low-flow therapy device. Features may also be provided in devices for providing continuous positive airway pressure (CPAP) that may deliver gas (humidified or otherwise) at positive pressure.

[0386] Alternatively, the filter module and / or valve module may be used with devices that do not require a humidifier, and therefore do not require the features of the liquid chamber 300 or chamber space 108. For example, it will be understood that the configuration for isolating the motor and gas flow path from the electrical and electronic components has broad application in other types of gas delivery devices.

[0387] The term "flow therapy device" is intended to encompass all such variations.

[0388] The reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that the prior art forms part of the general knowledge in the field of endeavor in any country worldwide.

[0389] When reference is made herein to directional terms such as "upper," "lower," "forward," "rearward," "horizontal," "vertical," etc., these terms refer to the device when in a typical in-use position and are used to indicate and / or describe relative directions or orientations.

[0390] Unless the context clearly dictates otherwise, throughout the description and claims, the words "comprise," "including," and the like are to be construed in an inclusive sense, i.e., "including but not limited to," as opposed to exclusive or exhaustive.

[0391] As used herein, the terms "approximately," "about," and "substantially" refer to an amount close to the stated amount that still performs the desired function or achieves the desired result. For example, in some embodiments, where the context allows, the terms "approximately," "about," and "substantially" can refer to an amount that is within 10% or less, within 5% or less, and within 1% or less of the stated amount.

[0392] The reference herein to any prior art is not, and should not be taken as, an acknowledgment or any form of suggestion that the prior art forms part of the general knowledge in the field of endeavor in any country throughout the world.

[0393] The disclosed devices and systems may also be broadly described as consisting individually or collectively of the parts, elements and features referred to or shown in the specification of this application, and in any or all combinations of two or more of said parts, elements and / or features.

[0394] Where the above description refers to components having wholes or their known equivalents, those wholes are incorporated herein as if individually set forth.

[0395] Depending on the embodiment, some acts, events, or functions of any algorithm, method, or process described herein may be performed in a different sequence, added, merged, or omitted entirely (e.g., not all acts or events described are necessary to implement an algorithm). Furthermore, in some embodiments, acts or events may be performed not sequentially, but simultaneously, for example, by multithreading, interrupt processing, or multiple processors or processor cores, or on other parallel architectures.

[0396] It should be noted that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the disclosed apparatus and system and without diminishing its attendant advantages. For example, various components can be rearranged as needed. Accordingly, such changes and modifications are intended to be included within the scope of the disclosed apparatus and system. Moreover, not all features, aspects, and advantages are necessarily required to implement the disclosed apparatus and system. Accordingly, the scope of the disclosed apparatus and system is intended to be defined solely by the scope of the following claims.

Claims

1. A respiratory device that provides gas flow to the patient, During the operation of the respiratory device, a gas composition sensor configured to determine at least the oxygen content (FdO2) of the gas flow is provided; A controller configured to control the supply of the gas flow to the patient using closed-loop control, comprising: receiving patient parameter data from at least one sensor indicating the patient's oxygen saturation (SpO2); receiving data from a gas composition sensor indicating the measured percentage of oxygen supplied to the gas flow (FdO2); receiving flow rate data corresponding to or indicating the flow rate of the gas flow provided by the ventilator; determining at least one time-related parameter, wherein each of the time-related parameters is at least partly based on the flow rate data; and generating a patient-specific model that is at least partly based on the at least one time-related parameter; The patient-specific model is used to predict the change in the patient's oxygen saturation (SpO2) in response to the change in the measured proportion (FdO2) of oxygen supplied to the gas flow, in a respiratory system.

2. The determination of the at least one time-related parameter is at least in part based on whether the flow rate falls below a specified threshold, and / or The at least one time-related parameter includes an instrument-specific delay time associated with the delay time of oxygen transport from the ventilator to the patient, and / or The at least one time-related parameter is a patient-specific delay time associated with the delay time of oxygen transport from the patient's upper airway to the tissue perfusion monitoring site, and / or The respiratory device according to claim 1, wherein the at least one time-related parameter is a decay value associated with the time it takes for the patient's SpO2 level to decay to a stable value within a range following a change in FdO2 by the controller.

3. The flow rate data indicates or corresponds to a specific flow rate configured by the user, or the flow rate data indicates or corresponds to the measured flow rate of the gas delivered by the respirator. The respiratory apparatus according to claim 1, wherein the flow rate is received from a flow sensor provided in the gas flow.

4. The determination of the at least one time-related parameter is at least in part based on at least one criterion associated with one or more physical characteristics of the patient, and / or the patient's size, and / or the flow rate, and / or the type of patient interface detected, and / or the type of patient interface configured by the user. The respiratory apparatus according to claim 1, wherein the controller is further configured to select a first algorithm or a second algorithm to determine the at least one time-related parameter based on whether the flow rate meets a predetermined threshold, at least in part.

5. The closed-loop control includes using a first closed-loop control model configured to determine a target percentage (FdO2) of oxygen supplied for the gas flow, The aforementioned target percentage is, At least in part, it is determined based on the target SpO2 and the patient parameter indicating the patient's oxygen saturation (SpO2), and / or At least in part, it is based on the received data showing the measured proportion (FdO2) of oxygen supplied to the gas flow, and / or The respiratory apparatus according to claim 1, which is at least in part based on a previously determined target FdO2.

6. The closed-loop control includes, at least in part, using a second closed-loop control model configured to determine a control signal for an oxygen inlet valve based on the difference between a target FdO2 for the gas flow and the received data indicating the measured proportion (FdO2) of supplied oxygen in the gas flow. The respiratory apparatus according to claim 1, wherein the control signal for the oxygen valve is determined, at least in part, based on the received data indicating the target FdO2 and the measured ratio (FdO2) of oxygen supplied to the gas flow.

7. The patient-specific model is generated during the current treatment session, according to claim 1.

8. The patient-specific model includes the patient's oxygen efficiency, The respiratory apparatus according to claim 1, wherein the oxygen efficiency is determined at least in part based on the received data indicating the patient's oxygen saturation (SpO2), the received data indicating the measured proportion (FdO2) of supplied oxygen in the gas flow, and / or the received data indicating the oxygen saturation (SpO2) divided by the received data indicating the measured proportion (FdO2) of supplied oxygen.

9. Furthermore, it includes a patient interface selected from at least one of the following: face mask, nasal mask, nasal pillow mask, tracheostomy interface, nasal cannula, unsealed nasal cannula, or endotracheal tube. The respiratory device is configured to supply a gas flow to the patient in nasal high-flow (NHF) and / or The respiratory apparatus according to claim 1, wherein the at least one sensor includes a pulse oximeter configured to determine or provide patient parameter data indicating at least the patient's oxygen saturation (SpO2).

10. Further including a supplementary gas inlet valve, The controller is configured to control the operation of the supplemental gas inlet valve. The respiratory apparatus according to claim 1, wherein the supplemental gas inlet valve is a proportional valve and / or an oxygen inlet valve.

11. The respiratory device is Construed to be portable, and / or, It is configured to have a controlled variable flow rate, and / or The respiratory apparatus according to claim 1, further comprising a heated breathing tube.

12. The ultrasonic sensor system includes a first ultrasonic transducer and a second ultrasonic transducer. The respiratory apparatus according to claim 1, wherein the first ultrasonic transducer and the second ultrasonic transducer are a receiver and a transmitter configured to send pulses bidirectionally across the gas flow.

13. The controller is configured to display a second oxygen efficiency characteristic on the ventilator's display, and the second display frequency of oxygen efficiency is at least in part based on the patient's oxygen efficiency and measured respiratory rate. The second oxygen efficiency characteristic is calculated by dividing the received patient parameter data indicating the patient's oxygen saturation (SpO2) by the received data indicating the percentage of oxygen supplied in the gas flow (FdO2), and then dividing the resulting value by the measured respiratory rate, and / or The respiratory apparatus according to claim 1, wherein the controller is configured to display a graph or trend line showing at least one of the first oxygen efficiency characteristics or the second oxygen efficiency characteristics over a specified period of time.

14. The respiratory device according to claim 1, wherein the respiratory device is capable of switching between a high-flow therapy mode and a bubble CPAP therapy mode.

15. One or more of the patient parameter data indicating oxygen saturation (SpO2) and the flow rate data are received while the patient is receiving treatment and are related to the current operation of the respiratory therapy device, or The respiratory device according to any one of claims 1 to 14, wherein one or more of the patient parameter data indicating oxygen saturation (SpO2) and the flow rate data are related to one or more previous operating states or treatment sessions of the respiratory therapy device.

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