Pressure and oxygen mix control for single limb non-invasive ventilation

Abstract

A method for controlling oxygen mixing for a single-limb non-invasive ventilator, the single-limb non-invasive ventilator comprising: a pressure controller, and both a blower and a pressurized oxygen source downstream of the blower, each of the blower and the pressurized oxygen source comprising a controller and a flow valve controlling flow, the method comprising: (i) generating a flow trajectory; (ii) providing the generated flow trajectory to a complementary flow coupling filter pair comprising a blower flow coupling filter and an oxygen flow coupling filter; (ii) generating an output from each of the filters, the output comprising an input flow trajectory for a blower flow controller and an input flow trajectory for an oxygen flow controller; and (iv) adjusting, by the blower flow controller and / or the oxygen flow controller, a blower speed controller and / or a pressurized oxygen source proportional flow valve based on the input flow trajectory, a target pressure, and oxygen mixing.

Description

[0001] Cross-reference to related applications

[0002] This patent application claims the benefit of priority to U.S. Provisional Application No. 62 / 897,641, filed September 9, 2019, the contents of which are incorporated herein by reference. Technical Field

[0003] The present invention generally relates to a method and system for controlling the pressure and oxygen mixing of a single-limb non-invasive ventilator using a blower as an air source and compressed oxygen flowing downstream of the blower outlet. Background Technology

[0004] Currently, ventilator design engineering practices typically employ compressed gas valves as prime movers; devices that actuate flow. Compressed air and oxygen (typically ranging from 50 to 100 psig) from the hospital piping system are supplied to the valve's gas inlet. The valve regulates the flow into the manifold via electronic feedback control. This mixed gas is delivered to the patient circuit that connects the ventilator to the patient's airway. A simple algebraic proportion of the total flow between the valves achieves the desired mixing while meeting volume or pressure targets with minimal complexity. The oxygen and air valves are identical and therefore statically and dynamically matched. Through matching, the valves do not compete with each other in pushing gas into the manifold, thus achieving the desired mixing, pressure, and volume.

[0005] Newer ventilator designs can use blowers, fans, or reciprocating pistons as prime movers. As long as the inlet gas to these devices is pre-mixed (using, for example, a mechanical mixer or oxygen injected from a compressed gas valve), the tasks of controlling mixing and pressure remain somewhat independent. For example, if oxygen is combined with air upstream (inlet) of the blower, the blower acts as the sole actuator to achieve pressure or volume. In this case, the oxygen source has no effect on establishing pressure in the manifold.

[0006] However, if oxygen is introduced downstream (at the outlet) of the blower, then both the blower and the oxygen valve become a shared prime mover; they both directly affect the pressure in the manifold where the gases are mixed. The problem with this shared action lies in the typical dynamic mismatch between the blower and the compressed gas valve. The blower flow cannot respond almost as quickly as the valve, and the blower source impedance is much higher than that of the valve. This high source impedance means that the blower cannot push gas into the load as easily as the valve can. During transients, the valve can overcome the blower, causing its flow to reverse instantaneously. The mixing and pressure physics transfer functions become entangled, thus interfering with each other. This makes control much more difficult, especially under high mixing settings.

[0007] Therefore, there is a need in the art for a single-limb non-invasive ventilation system that uses a blower as an air source and uses compressed oxygen flowing downstream of the blower outlet, but allows for a rapid, efficient and cost-effective mechanism for controlling pressure and oxygen mixing. Summary of the Invention

[0008] This disclosure relates to inventive methods and systems for controlling the pressure and oxygen mixing of a single-limb non-invasive ventilator using a blower as an air source and compressed oxygen flowing downstream of the blower outlet. Various embodiments and implementations herein relate to a non-invasive ventilator system comprising: a pressure controller, a blower, and a pressurized oxygen source downstream of the blower, wherein each of the blower and the pressurized oxygen source includes a controller and a proportional flow valve for controlling the flow. A total flow trajectory is generated from the output of the blower pressure controller and provided to a complementary flow-coupled filter pair including a blower flow-coupled filter and an oxygen flow-coupled filter. The filters generate an input flow trajectory for the blower flow controller and an input flow trajectory for the pressurized oxygen source flow controller, and the blower flow controller and / or the oxygen flow controller adjust the blower speed and / or the pressurized oxygen source proportional flow valve based on the input flow trajectories and a target pressure and target oxygen mixing.

[0009] In one aspect, a method for controlling oxygen mixing in a single-limb non-invasive ventilator is provided. The single-limb non-invasive ventilator includes both a pressure controller, an air blower, and a pressurized oxygen source, wherein the pressurized oxygen source is downstream of the air blower, each of the air blower and the pressurized oxygen source includes a controller, and the oxygen source includes a proportional flow valve for controlling the flow. The method includes: (i) receiving a target pressure and a target oxygen mixture from a ventilator; (ii) generating a total flow trajectory from the output of a blower pressure controller; (iii) providing the generated total flow trajectory from the blower pressure controller to a complementary flow-coupled filter pair, the complementary flow-coupled filter pair including a blower flow-coupled filter and an oxygen flow-coupled filter; (iv) generating an output from each of the blower flow-coupled filter and the oxygen flow-coupled filter, the output including the input flow trajectory of the blower flow controller and the input flow trajectory of the pressurized oxygen source flow controller, respectively; and (v) adjusting the air blower speed and / or the pressurized oxygen source proportional flow valve by the blower flow controller and / or the oxygen flow controller based on the input flow trajectory and the received target pressure and target oxygen mixture.

[0010] According to an embodiment, the oxygen flow coupling filter includes a low-pass coupling filter. According to an embodiment, the blower flow coupling filter includes a high-pass coupling filter relative to the oxygen flow coupling filter. According to an embodiment, the complementary flow coupling filters are configured to be complementary to divide the actuator effects into different frequency bands, and the different frequency bands are determined according to the mixing objective.

[0011] According to an embodiment, the blower pressure controller includes a multi-stage cascaded feedback structure.

[0012] According to an embodiment, the single-limb noninvasive ventilator also includes a complementary filter that provides feedback to the pressure controller. The complementary filter is configured to receive pressure measurements from a ventilator pressure sensor and proximal pressure measurements from a proximal pressure sensor in the patient circuit. According to an embodiment, the complementary filter is configured to generate a single pressure signal to the pressure controller by blending the pressure measurements received from the ventilator pressure sensor with the proximal pressure measurements received from the proximal pressure sensor. According to an embodiment, the complementary filter is configured to blend the received pressure measurements using complementary frequency bands with a proximal pressure sensor signal at a low frequency and a ventilator pressure sensor signal at a higher frequency.

[0013] According to one aspect, a single-limb non-invasive ventilation system is provided, configured to control oxygen mixing based on a target pressure and a target oxygen mixture. The system includes: (i) a pressure controller configured to generate a total flow trajectory; (ii) an air blower including a blower flow controller; (iii) a pressurized oxygen source downstream of the air blower and including an oxygen controller and a proportional flow valve for controlling oxygen flow; (iv) a complementary flow-coupled filter pair including a blower flow-coupled filter and an oxygen flow-coupled filter; and (v) a controller configured to: provide the generated total flow trajectory from the blower pressure controller to the complementary flow-coupled filter pair; and receive an output from each of the blower flow-coupled filter and the oxygen flow-coupled filter, the output including the input flow trajectory of the blower flow controller and the input flow trajectory of the pressurized oxygen source flow controller, respectively; wherein the blower flow controller and / or the oxygen flow controller adjust the blower speed and / or the pressurized oxygen source proportional flow valve based on the input flow trajectory and the target pressure and target oxygen mixture.

[0014] According to an embodiment, the single-limb noninvasive ventilator further includes a complementary filter that provides feedback to the pressure controller. The complementary filter is configured to receive pressure measurements from a ventilator pressure sensor and proximal pressure measurements from a proximal pressure sensor in the patient circuit. According to an embodiment, the complementary filter is configured to generate a single pressure signal for the pressure controller by fusing the pressure measurements received from the ventilator pressure sensor with the proximal pressure measurements received from the proximal pressure sensor. According to an embodiment, the complementary filter is configured to fuse the received pressure measurements using complementary frequency bands with a proximal pressure sensor signal at a low frequency and a ventilator pressure sensor signal at a higher frequency.

[0015] It should be understood that all combinations of the foregoing concepts and the additional concepts discussed in more detail below (assuming such concepts are not inconsistent with each other) are considered part of the inventive subject matter disclosed herein. Specifically, all combinations of the claimed subject matter appearing at the end of this disclosure are considered part of the inventive subject matter disclosed herein.

[0016] These and other aspects of the invention will be apparent from the embodiments described below and will be set forth with reference to the embodiments described below. Attached Figure Description

[0017] In the accompanying drawings, similar reference numerals generally refer to the same parts in different views. Furthermore, the drawings are not necessarily drawn to scale, but generally focus on illustrating the principles of the invention.

[0018] Figure 1 This is a schematic diagram of a non-invasive ventilation system according to an embodiment;

[0019] Figure 2 This is a flowchart of a method for controlling the pressure and oxygen mixing of a single-limb non-invasive ventilator according to an embodiment;

[0020] Figure 3 This is a schematic representation of a non-invasive ventilation system according to an embodiment;

[0021] Figure 4 This is a graph showing the frequency response of a flow-coupled filter for oxygen and blower (flow) control according to an embodiment;

[0022] Figure 5 This is a graph illustrating a flow-coupled filter with a step response at a mixing ratio of 30%, according to an embodiment.

[0023] Figure 6 This is a graph illustrating a flow-coupled filter with a step response at a mixing concentration of 60.5%, according to an embodiment.

[0024] Figure 7 This is a graph illustrating a flow-coupled filter with a step response at a mixing ratio of 90%, according to an embodiment.

[0025] Figure 8 This is a lung-patient model used in the design of a pressure controller, based on the use of a loop simulation according to the embodiment;

[0026] Figure 9 It is a graph illustrating the frequency response of the lung circuit dynamics with leakage according to an embodiment;

[0027] Figure 10 This is a graph showing the pseudo-derivative feedback compared to proportional-integral-derivative control according to an embodiment;

[0028] Figure 11 This is a block diagram of the complementary filter used in the pressure feedback control according to an embodiment;

[0029] Figure 12 The illustration is a schematic diagram of a piping system according to an embodiment, which completes the diversion of blower pressure to the near-end line when the exhaust valve Rv is opened;

[0030] Figure 13 It is the loop model assumed for the proximal pressure estimator including the patient loop time constant according to the embodiment;

[0031] Figure 14 This is a block diagram of a method for determining a delay in proximal pressure measurement results according to an embodiment;

[0032] Figure 15 This is an example batch pressure sample used to obtain delay parameters according to an embodiment, wherein the actual delay is 7 milliseconds;

[0033] Figure 16 It is a plot of the cost function and delay estimate according to the embodiment, wherein the upper plot shows the cost (integral squared error) and the lower plot shows the delay estimate;

[0034] Figure 17 It is a diagram defining the flow state based on a simplified diagram of the gas path according to an embodiment;

[0035] Figure 18 It is a graph defined more quantitatively based on the flow state of the blower and oxygen flow relative to the relative magnitude and direction, according to an embodiment; and

[0036] Figure 19 This is a schematic representation of an example state machine hybrid estimator showing the input (right) and output (left) according to an embodiment. Detailed Implementation

[0037] This disclosure describes various embodiments of non-invasive ventilator (NIV) systems and methods. More generally, the applicant has recognized and understood that it would be beneficial to provide a non-invasive ventilator system and method for accurately and rapidly controlling the pressure and oxygen mixing of a single-limb non-invasive ventilator using a blower as an air source and compressed oxygen flowing downstream of the blower outlet. For example, such a non-invasive ventilator system includes both a pressure controller, a blower, and a pressurized oxygen source, wherein the pressurized oxygen source is downstream of the blower, and each of the blower and the pressurized oxygen source includes a controller and a proportional flow valve for controlling the flow. A total flow trajectory is generated from the output of the blower pressure controller and provided to a complementary flow-coupled filter pair, which includes a blower flow-coupled filter and an oxygen flow-coupled filter. The filter generates the input flow trajectory for the blower flow controller and the input flow trajectory for the pressurized oxygen source flow controller, and the blower flow controller and / or oxygen flow controller adjust the blower speed and / or pressurized oxygen source proportional flow valve based on the input flow trajectory and the target pressure and target oxygen mixing.

[0038] The non-invasive ventilation systems and methods disclosed or otherwise conceived in this paper offer numerous advantages over existing technologies. Combining a blower and valve flow control significantly increases the complexity of the control algorithm, primarily in terms of the stability, accuracy, and consistency of the control response. Valves can cause the blower to overpower. And while gas flow cannot be reversed by a compressed gas valve, this is possible in the case of a blower. The dynamic response between the blower and valve can be significant, as can the differences in the flow source output impedance (the ability to drive the flow into the load). The level of control complexity depends heavily on the choice of gas passage structure and specifically on the relative positions of the blower and oxygen.

[0039] Any architecture that combines blower and valve flow control presents numerous other technical challenges. For example, blower flow response time is typically much slower than valve response time because blower inertia requires significantly more time to accelerate and establish flow; for valves, all energy is stored in the compression of the gas. The slower response of the blower itself generally affects pressure response time, but the flow dynamics mismatch between the blower and valve makes pressure and mixing control a challenging problem. Additionally, it is often required that the target pressure set by the user be accurate at the patient connection. Although proximal pressure sensing circuitry is typically provided in single-limb non-invasive ventilation (NIV), using that pressure alone as a source for control introduces a significant delay in the pressure feedback loop. To compensate for this delay, the loop gain must be limited. This further slows down the blower response.

[0040] Additionally, using blower speed control can improve the response, but the tachometer signal tends to drop out at low speeds. Using current and voltage observers can address the dropout, but at higher speeds exceeding the sampling rate, torque commutation ripple frequencies can alias back into the control band, causing instability.

[0041] As with any control system, the effects of disturbances must be considered as part of the design to ensure that the control follows the desired target pressure despite disturbances and that the control attenuates rather than amplifies the disturbances. For NIV, sources of disturbance include (a) flow disturbances (demand) from the patient, (b) disturbances (leakage and partial blockage) in the patient connection, and (c) torque disturbances from the blower motor bearings and pneumatic pressure loads.

[0042] Additionally, patient exhaled gases that can be returned to the environment via the blower can be "preloaded" with oxygen-rich gas into the blower pathway. Subsequent rebreathing introduces additional oxygen at the desired set point, further complicating mixture control.

[0043] Ventilator control typically employs proportional-integral-derivative (PID) compensators to stabilize and shape the transient response. With fixed-gain control, changes in patient pressure hemodynamics can lead to significant discrepancies in transient response and end-inspiratory pressure accuracy due to overshoot. The PID architecture itself can be a cause of overshoot because it employs two real numbers, or a pair of complex "zeros," in its design, which continuously operate within the closed loop.

[0044] Several versions or alternative custom controller architectures are often required in ventilators to operate for specific areas of ventilation. For example, previous ventilator designs have used separate controllers to serve respiratory delivery, system services or diagnostics, standby mode, and in some cases, different controllers for neonatal, pediatric, and adult patients. While this can be an effective approach, it doubles the complexity, making it three or four times more difficult to manage in terms of design, testing, and software changes.

[0045] The methods and systems described herein, or otherwise conceived, address and resolve these problems. While some ventilators use individual gain or configurations depending on patient size, circuit size, type, specific ventilator settings, etc., the invention described herein claims protection for effective control utilizing a single configuration. This also extends to auxiliary functions such as controllers used in calibration, system services, and standby states.

[0046] refer to Figure 1In one embodiment, this is an example of a non-invasive ventilation system 100. The system includes a gas source, which can be any gas, including but not limited to air and oxygen from the atmosphere. According to an embodiment, the non-invasive ventilation system 100 includes a blower as an air source and compressed oxygen flowing downstream of the blower outlet. The system also includes a controller 120, which is a conventional microprocessor, an application-specific integrated circuit (ASIC), a system-on-a-chip (SOC), and / or a field-programmable gate array (FPGA), and other types of controllers. The controller can be implemented with or without a processor and can also be implemented as a combination of dedicated hardware performing some functions and a processor (e.g., one or more programmable microprocessors and associated circuitry) performing other functions.

[0047] Controller 120 may be coupled to or otherwise communicate with any necessary memory, power supply, I / O devices, control circuitry, sensors, valves, blowers, and / or other devices necessary for the operation of the ventilator according to embodiments described herein or otherwise contemplated. For example, in various implementations, the processor or controller may be associated with one or more storage media. In some implementations, the storage media may be encoded with one or more programs that, when run on one or more processors and / or controllers, perform at least some of the functions discussed herein. Various storage media may be embedded within the processor or controller or may be portable, such that one or more programs stored thereon may be loaded into the processor or controller to implement the various aspects of the invention discussed herein. The terms “program” or “computer program” are used herein in a general sense to refer to any type of computer code (e.g., software or microcode) that may be employed to program one or more processors or controllers.

[0048] According to one embodiment, controller 120 is configured or programmed to function as a blower controller for coordinating and controlling the blower function of a non-invasive ventilator. For example, the blower controller can control the rate and intensity of the system's (multiple) blowers, thereby controlling or directing flow through the loop. According to another embodiment, the blower controller is a separate component, preferably in communication with controller 120, although the multiple functions of the system can be coordinated in other ways. While this embodiment uses a blower flow controller to activate the loop, any type of flow source, including, for example, a proportionally controlled compressed gas valve, can be utilized, where the source provides the actual flow and pressure measurement.

[0049] The non-invasive ventilator includes a tubing or patient circuit 130 that delivers gas from a remote ventilator component 140 to a patient interface 150. The patient interface 150 may be, for example, a mask covering all or part of the patient's mouth and / or nose. A variety of different mask sizes may be available to accommodate patients or individuals of different sizes, and / or the mask may be adjustable. Alternatively, the patient interface 150 may be adapted to be inserted into, on, or otherwise interact with a tracheostomy tube. Therefore, the patient interface 150 may be of various sizes to accommodate tracheostomies of different shapes and sizes. The patient interface is configured to fit at least a portion of the patient's airway and includes an exhalation port 180. The single-limb non-invasive ventilation system includes a distal gas flow sensor 160 at the end of the tubing near the remote ventilator component 140, a proximal pressure sensor 170 at the end of the tubing near the patient interface 150, and a distal (machine) sensor 190 near the distal gas flow sensor 160. Either the distal gas flow sensor 160 or the proximal pressure sensor 170 may include, for example, two or more sensors. For example, the distal gas flow sensor 160 may include a blower flow sensor and an O2 valve sensor. Additionally, any sensor may be external to or internal to the ventilator. The controller 120 is configured to receive sensor data from the distal gas flow sensor 160, the distal (machine) sensor 190, and the proximal pressure sensor 170 via wired or wireless communication. According to embodiments, the proximal pressure sensor may be physically attached to the patient connection and electrically communicate back to the processor, or it may be located within the ventilator, with a small-diameter tube connecting the sensor back to the patient connection. Embodiments described herein, for example, address delays introduced by the tube.

[0050] refer to Figure 2 In one embodiment, this is a flowchart of a method 200 for controlling the pressure and oxygen mixing of a single-limb non-invasive ventilator. At step 210, a non-invasive ventilator system 100 is provided. The non-invasive ventilator system can be any embodiment described herein or otherwise contemplated.

[0051] At step 220, the system receives the target pressure and target oxygen mix. The target pressure and target oxygen mix can be any desired pressure and mix and will depend on the needs of the patient and healthcare professionals. The target pressure and target oxygen mix can be received using any input method, including via a user interface or any other method.

[0052] At step 230 of the method, the system generates a total flow trajectory from the output of the system's blower pressure controller. The total flow trajectory can be calculated using any of the methods disclosed herein or otherwise contemplated.

[0053] At step 240 of the method, the total flow trajectory generated from the blower pressure controller of the system is provided to a complementary flow-coupled filter pair, which includes a blower flow-coupled filter and an oxygen flow-coupled filter. The oxygen flow-coupled filter may include a low-pass coupling filter, and the blower flow-coupled filter may include a high-pass coupling filter relative to the oxygen flow-coupled filter. The complementary flow-coupled filter pair is configured to be complementary to divide the actuator effects into different frequency bands.

[0054] At step 250 of the method, each of the blower flow coupling filter and the oxygen flow coupling filter generates an output, which includes the input flow trajectory of the blower flow controller and the input flow trajectory of the pressurized oxygen source controller, respectively. These inputs are provided to the blower flow controller and the pressurized oxygen source controller.

[0055] At step 260 of the method, based on the received target pressure and target oxygen mixture and also based on the corresponding received input flow trajectory, the blower flow controller adjusts the speed of the air blower and / or the oxygen flow controller adjusts the pressurized oxygen source proportional flow valve.

[0056] According to an embodiment, the single-limb noninvasive ventilator may further include a complementary filter that provides feedback to the pressure controller. This complementary filter is configured to receive pressure measurements from a ventilator pressure sensor and proximal pressure measurements from a proximal pressure sensor in the patient circuit. The complementary filter may be configured to generate a single pressure signal to the pressure controller by fusing the pressure measurements received from the ventilator pressure sensor with the proximal pressure measurements received from the proximal pressure sensor. The complementary filter may also be configured to fuse the received pressure measurements using complementary frequency bands with a proximal pressure sensor signal at a low frequency and a ventilator pressure sensor signal at a higher frequency.

[0057] refer to Figure 3 , Figure 3 This is an embodiment of a single-limb non-invasive ventilation system 300 configured to control oxygen mixing based on target pressure and target oxygen mixing. The non-invasive ventilation system can be any embodiment described herein or otherwise conceived. Component reference for the non-invasive ventilation system. Figure 3 The description is provided below, and further details are provided in more detail.

[0058] According to an embodiment, the system may include a single pressure controller 310 configured to generate a total flow trajectory and / or generate an output for (such as by the system's controller 120) generating the total flow trajectory.

[0059] The system also includes a blower 330, which includes a blower flow controller 332 for controlling the blower flow and an air blower speed controller 336. Therefore, the blower flow controller and the blower speed controller can control the flow input into the system. The blower and blower components can be any components suitable for appropriate control of the system.

[0060] The system also includes a pressurized oxygen source 340 downstream of the blower, and includes an oxygen controller 342 and a proportional flow valve for controlling the oxygen flow. Therefore, the oxygen controller and oxygen flow valve can control the oxygen flowing into the system and the oxygen mixing process. The pressurized oxygen source can be any oxygen source.

[0061] The system also includes a complementary flow-coupled filter pair, comprising a blower flow-coupled filter 334 and an oxygen flow-coupled filter 344. These filters may include any filter suitable for performing the functions described herein or otherwise contemplated. For example, the oxygen flow-coupled filter may be a low-pass coupling filter, and the blower flow-coupled filter may be a high-pass coupling filter relative to the oxygen flow-coupled filter. The complementary flow-coupled filter pair is configured to be complementary to divide the actuator effects across different frequency bands.

[0062] The controller 120 of the system is configured to perform one or more functions of the system. Many or all of the control functions can be performed by the controller 120. For example, the controller can be configured to: (i) provide the generated total flow trajectory from the blower pressure controller to the complementary flow-coupled filter pair; and (ii) receive outputs from each of the blower flow-coupled filter and the oxygen flow-coupled filter, the outputs comprising the input flow trajectory of the blower flow controller and the input flow trajectory of the pressurized oxygen source flow controller, respectively.

[0063] Therefore, the blower flow controller and / or oxygen flow controller can adjust the blower speed or the flow controller and / or pressurized oxygen source proportional flow valve based on the input flow trajectory and target pressure and target oxygen mixing.

[0064] According to an embodiment, the system also includes a complementary filter 350 that provides feedback to the pressure controller. This complementary filter can be configured to receive pressure measurements from the ventilator pressure sensor 352 and proximal pressure measurements from the proximal pressure sensor of the patient circuit 354. The complementary filter can be configured to generate a single pressure signal to the pressure controller by fusing the pressure measurements received from the ventilator pressure sensor with the proximal pressure measurements received from the proximal pressure sensor. Additionally, the complementary filter can be configured to fuse the received pressure measurements using complementary frequency bands with the proximal pressure sensor signal at a low frequency and the ventilator pressure sensor signal at a higher frequency.

[0065] According to an embodiment, the system includes a dynamic ratio measurement method with hybrid control consisting of oxygen flow coupled filters:

[0066] (Formula 1)

[0067] It also includes a blower flow coupling filter:

[0068] (Formula 2)

[0069] For formulas 1 and 2, the flow-coupled filters for oxygen and blowers span the full range of mixing from 21% to 100%. Figure 4 The example frequency response of the flow-coupled filter is shown. The filter's variable cutoff frequency depends on the mixing target. Steady-state mixing ratios were achieved in all cases at extreme settings of 21% and 100%; all kinetics disappeared. Figures 5-7 The example step response of the filter alone is shown in the figure. Figures 5-7 The diagram illustrates symmetry (complementary action); leading action on the blower side and lag on the oxygen side. It also shows the variable rise time depending on the mixing target. Figure 5 A flow-coupled filter is shown, which has a step response at a mixing ratio of 30%. Figure 6 An example of a flow-coupled filter is shown, which has a step response at a mixing ratio of 60%. Figure 7 An example of a flow-coupled filter is shown, which has a step response at a mixing ratio of 60%.

[0070] Control structure; Blower cascade structure

[0071] The coupled filter derived above receives the same input: the output of the pressure controller—the total flow trajectory. The coupled filter output provides the corresponding input flow trajectory for the blower (air) and oxygen valve flow control loops based on the set mixing. The coupled filter naturally includes an algebraic scaling factor to achieve proper mixing at steady state; however, equally important are the frequency response characteristics of the blower and oxygen valve, which respond with invariant, stable control from the lowest to the highest mixing settings. Figure 3 This is a schematic representation of a cascaded controller, and it illustrates how a coupling filter can be used to connect the pressure controller to two flow control loops for the blower and oxygen valve.

[0072] therefore, Figure 3A multi-stage cascaded feedback architecture as a blower pressure controller is also illustrated. This architecture maximizes the stiffness of the internal loops and manages disturbance suppression at each sub-stage, enabling high-performance pressure control at the highest level. Starting with the innermost part of the cascade, these stages include (a) a current feedback loop that minimizes the effects of back-EMF and overcomes the inherent electrical time constant of the engine (not shown in the figure); (b) a blower speed feedback loop that linearizes speed control, suppresses motor load disturbances, and hard limits the maximum speed constraint with high accuracy; (c) a flow feedback loop that helps suppress pressure disturbances caused by patient flow demand, coughing, and partial loop blockage; and at the highest level, (d) a pressure feedback loop that accurately tracks the applied pressure trajectory.

[0073] The system includes a speed controller that bridges the current and flow controllers and suppresses viscous friction and torque-related disturbances. The speed controller relies on a model-based motor speed observer that supplements the tachometer readings at low speeds, thus providing the ability to control the blower speed at very low rates. This significantly improves the ability to control pressure transients during blower exhalation.

[0074] The system includes cascaded inter-compensator communication that provides feedforward speed advantage and improved anti-saturation capability. A feedforward connection exists between pressure error and blower current command, and an anti-saturation feedback connection operates from the blower speed limit back to the pressure loop integrator.

[0075] The system includes an integrated, application-compatible architecture. In addition to being suitable for respiratory delivery purposes, the cascaded controller architecture can serve other applications, including system services, standby, and flow therapy modes.

[0076] Adaptive pressure control using lung resistance estimation

[0077] Pressure control overshoot is associated with specific load dynamics (lung and loop time constants), however, it depends on the controller architecture and associated gain. The lung and loop can be determined based on, for example... Figure 8 The linear loop model shown is used for modeling (system simulation). Therefore, Figure 8 A lung patient model is shown using circuitry simulated for a pressure controller design.

[0078] Ventilator net flow is Qv, lumped patient tubing compliance is CT, lumped loop leakage resistance is RL, and net loop leakage flow is QL. Pp is proximal pressure, QL is pulmonary flow, RL is pulmonary resistance, PL is pulmonary pressure, and CL is pulmonary compliance.

[0079] Given the system and the linear parameter assumptions, the second-order real pole transfer function from the ventilator net flow to the near-end pressure can be written as follows:

[0080] (Formula 3)

[0081] The amplitude-frequency response curve of the transfer function is plotted on Figure 9 The graph (i.e., a plot showing the frequency response "scene" of the lung circuit dynamics with leakage) is shown in the middle. Typically, the frequency response function is plotted by a thick black line, where the low-frequency (steady-state) gain equals the circuit leakage resistance. As the leakage resistance becomes very high, the zeroth-order term in Equation 26 disappears, resulting in the RCC model already described in an earlier paper to represent invasive systems (where leakage is negligible):

[0082] (Formula 4)

[0083] However, frequency response formula 4 can also be defined in terms of another parameter; lung resistance. The extreme limits. For The transfer function is reduced to a first-order response, which has a cutoff based on the time constant associated with the loop leakage resistance and the combined compliance of the loop and the lung:

[0084] (Formula 5a)

[0085] for In the blocked state, the transfer function is again reduced to a first-order response, however, this first-order response has a cutoff based on the time constant associated with the loop leakage resistance and the compliance of the patient-only loop.

[0086] (Formula 5b)

[0087] In either of these extreme cases (Equation 5a) or (Equation 5b), the zeros of the transfer function disappear. However, for the general case, the zeros, determined by the lung time constant, relate the cutoff frequencies that exist between the two poles, and these are defined by the extreme cases described above. In this general case, at least for any practical purpose, these two frequencies are hopelessly entangled in terms of analytically reducing their values.

[0088] These terms provide a framework for the direct synthesis of pressure control solutions; in which the open-loop system is forced to behave as a simple integrator. It is only necessary to determine the loop-forming filter that effectively “cancels” the system’s dynamics but ensures the residual existence of the integrator. The loop-forming filter can be simply defined as having the inverse of (3) of the integrator:

[0089] (Formula 6)

[0090] And the value of K is set to achieve the desired closed-loop cutoff frequency. Of course, anti-saturation measures must be appropriately included to manage saturation in the event of flow control saturation. However, the linear compensator (Equation 6) is readily identified as a PID (Proportional-Integral-Derivative) filter cascaded with a hysteresis filter. Loop gain is absorbed. K The PID gain becomes:

[0091] (Formula 7)

[0092] (Formula 8)

[0093] (Formula 9)

[0094] In theory; more precisely, in the theory of linear systems, this will all work. The problem is that all these parameters can vary depending on many factors.

[0095] Pipeline compliance It can be calibrated before patient attachment, and although condensation in the circuit can cause a slight increase in compliance, a circuit operating at a higher temperature than it was calibrated for will have a greater effect. An increase in the operating (absolute) temperature of the gas causes a proportional increase in compliance with a fixed compliance boundary (rigid boundary). This can be corrected for if the assumed operating temperature or gas temperature measurements are provided. If the boundary is flexible, then pipe compliance can also differ at different operating pressures because the increased pressure leads to an increase in geometry.

[0096] Lung compliance The greatest variation / variation in lung compliance is patient-specific, although patient-specific lung compliance can change with disease progression or improvement, or with changes in bed position (supine, lateral, etc.). Even greater effects can be attributed to strong active breathing, which tends to manifest as “increased compliance.” According to linear models, lung compliance cannot be easily distinguished from patient effort. Even if clinicians can measure compliance before or during administered ventilation, these measurements should not be assumed to be constant. Some devices for online, real-time estimation of lung compliance should be arranged to ensure robust control. Unlike tubing compliance, lung compliance will not be affected by temperature, as the vast surface area of ​​the airways and lungs regulates temperature to around 37 degrees Celsius.

[0097] Lung airway resistance Similar to lung compliance, this problem should be estimated online, but the main issue lies in flow resistance; at least in the upper airway or ETT, it doesn't always fit a linear model well. The flow-pressure relationship is better approximated as quadratic; as a 2-parameter model. Resistance is given as a function of flow. Therefore, for lung resistance:

[0098] (Formula 10)

[0099] Therefore, the resistance changes continuously with the flow.

[0100] Leakage resistance They still follow the same model, but with different coefficients:

[0101] (Formula 11)

[0102] Although fixed (known) leakage resistance can be calibrated before patient attachment or determined a priori from factory measurements (especially mask leakage or exhalation port leakage), preparations for estimating unknown leakage should be included, as leakage can increase (or decrease) during respiratory delivery.

[0103] Options for pressure control considerations include:

[0104] 1. Fix all parameters to some nominal values ​​to compromise between overshoot at low airway resistance and oscillation at high resistance. This is known to be less effective when patient load approaches extreme dynamics (slow and fast lung time constants).

[0105] 2. Construct an estimator to continuously update the parameters and thus update the PID gain in real time. This is an improvement on (1.), but it assumes a “frozen parameter” assumption for a system with linearly varying parameters; the system is stable not only in a specific (frozen) operating state, but also between states as the system transitions between them. This assumption is not always true, there is no easy way to ensure it, and therefore there is considerable risk in choosing continuous updates, in addition to the complexity of designing the estimator.

[0106] 3. Use gain allocation methods to focus on smaller sets of parameters or individual parameters; those that have a more significant impact on stability and response. Update the appropriate gain based on the breathing principle.

[0107] For the purposes of this disclosure, the last option was chosen to avoid the complexity of a more extensive multi-state estimator; however, the use of method (2.) is not technically prohibited. Experiments have determined that the Ki and Kd gains can be fixed and can be adjusted based on a hypothesized single-parameter quadratic model. The single system parameter estimate is used to simply adjust Kp. In Equation 33, it is assumed that K1 < <K2, Equals K2:

[0108] (Formula 12)

[0109] in It is calculated as cm H2O / (lps) 2 Estimated airway resistance in units of 1.

[0110] To further avoid pressure overshoot, a PDF (pseudo-derivative feedback) version of the control is used. This method feeds back the non-integral component of the compensator after, but not before, the integrator. In other words, proportional and derivative feedback is used to measure the result P instead of the measurement error e. The PDF structure is similar to... Figure 10 Compared to the PID structure in [the text]. Therefore, Figure 10 The pseudo-derivative feedback (PDF) is shown in comparison with PID control; the PDF retains the same characteristic function as PID control, but removes the zeros introduced by the PID compensator.

[0111] Complementary filters for pressure control

[0112] For the pressure controller, another complementary filter is used for pressure feedback. This filter combination fuses the machine and proximal pressure signals into a single signal for pressure feedback control. Fusion occurs across complementary frequency bands: the proximal sensor at a lower frequency and the machine sensor at a higher frequency. The machine signal, with less delay, provides a stable but faster blower response, while the proximal signal provides accurate proximal pressure at steady state. A block diagram of the complementary filter used in pressure feedback control is illustrated in [illustration missing]. Figure 11 In the new method, the crossover frequency between the low-pass filter and the band-pass filter is increased, giving greater weight to the proximal pressure than in the previous design.

[0113] Proximal pressure estimation during purging

[0114] High-performance pressure control is possible as long as the integrity of the feedback measurement is maintained. However, for pneumatic designs that require periodic purging of the proximal sensing circuitry (to prevent the intrusion of water and slime), the pressure is temporarily absent. This “opens” the closed loop, and this can introduce instability. For high-performance control, the final good measurement cannot be simply “locked in” or paused during the duration of the purging. This still constitutes a sensor-down—open-loop situation. The best way to maintain stable operation during this interval, which lasts only a few hundred milliseconds, is to estimate the proximal pressure using other available pressure and flow sensors. This estimate needs to be as close as possible to the normal measurement in terms of amplitude, phase, and delay to serve as a proxy. Feedback control and stability are sensitive to all of these factors. Therefore, the delay (propagation delay) must also be part of the estimation.

[0115] According to an embodiment, the pressure from the blower manifold pressure sensor (blower pressure sensor) is diverted to the proximal pressure sensor connection to drain any condensate that may have accumulated or migrated to the end of the proximal pressure sensing line. Figure 12 The diagram schematically illustrates how the purge flow is diverted from the blower pressure through the purge valve Rv, represented by resistance. Therefore, Figure 12 This is a schematic representation of a piping system that completes the shunting of blower pressure to the proximal line when the purge valve Rv is opened. Therefore, the integrity of Pm is maintained during purge. For single-limb NIV, this can be accomplished every minute from the start of respiration. And during this interval, the proximal sensor will sense a superimposed pressure value existing somewhere between the actual blower and proximal pressures, primarily determined by the pressure drop from the sensor filter and the purge value limits. These parameters are difficult to estimate and are likely to differ in each system.

[0116] According to the embodiments, the methods and systems described herein or otherwise conceived may utilize a residual pressure during purging, machine pressure Pm, and flow sensor measurements from the ventilator, QO2 and Qb. This requires prior parameters of circuit compliance CT and circuit propagation delay, which can be determined as part of the patient circuit calibration.

[0117] refer to Figure 13 This is a loop model based on the proximal pressure estimator assumptions that include the patient loop time constant. The location of the lumped loop compliance relative to pipe resistance retains machine pressure and ventilator flow as inputs. Therefore, Figure 13 The diagram illustrates the hypothetical loop model and the generalized patient load impedance. It does not need to be known, but rather is used to explain the occurrence of non-zero proximal pressure. . It is pipeline resistance. It is the net flow (QO2 plus Qb) from the ventilator. It is patient catheter compliance, and It is the machine pressure measured at the inlet of the tubing leading to the patient.

[0118] Unlike the prior model used to estimate loop parameters, the (lumped) pipe compliance is chosen to exist on the upstream (left) side of the (lumped) pipe resistance. This key choice ensures that compliance, the fundamental dynamic parameters, are preserved in the model formulation. The loop simulation, written as a linear model, is extended to a nonlinear model by allowing the pipe resistance to be a function of the flow through it:

[0119] (Formula 13)

[0120] Machine pressure arises from the net flow in the pipeline compliance:

[0121] (Formula 14)

[0122] And the pressure drop from the machine to the near end is:

[0123] (Formula 15)

[0124] Finally, the nonlinear resistance of the pipe is replaced by solving for the proximal pressure as an estimate, but this estimate is further delayed by a delay of D to simulate the same delay as if a sensing circuit were present.

[0125] (Formula 16)

[0126] This formula provides a very close estimate of proximal pressure, good enough to be used as a feedback signal in pressure control during purge intervals. Tests have shown no perceptible difference in pressure control for purge / normal breathing.

[0127] The delay parameter D was obtained by running a single-limb circuit compliance calibration. All patient tubing compliance and resistance parameters were determined; however, additionally, machine pressure, actual proximal pressure, and net ventilator flow signal measurements were saved to further determine the patient circuit delay. After calibration to determine the parameters, the undelayed model proximal pressure output was compared with the (delayed) measured pressure. A continuous estimate for D was then derived and applied to the undelayed estimate to minimize grouped sample differences. The value of D was rounded to the most recent step size ΔT used in the control.

[0128] To illustrate one embodiment of the method, an N-tap delay circuit is used in a batch closed-loop process. Stepwise, samples of the measured results and the estimated delay are distinguished, and the squared error is integrated over the batch. The result is then fed into an optimization routine (e.g., Powell's gradient search), which yields a delay exponent quantized according to the sampling interval of the system timing. For various embodiments, this is 0.001 seconds, but other values ​​are possible. The delay exponent selects the number of delay taps to apply to the estimated proximal pressure samples for the next iteration. The process stops with the estimated delay when the error reaches a threshold set by the optimizer. Reference Figure 14 In one embodiment, this is a block diagram of a method for determining a delay in proximal pressure measurement results.

[0129] The closed-loop iteration of the vector leads to the convergence of the actual delay of the loop, as shown by... Figure 15 The graph of proximal pressure is shown below. The proximal pressure is from an example batch of pressure samples to obtain the latency parameter, where the actual latency is 7 milliseconds. (Reference) Figure 16The figure shows the cost function and the delay estimate, with the upper plot showing the cost (integral squared error) and the lower plot showing the delay estimate that converges to the actual value (7 milliseconds) in less than 14 iterations.

[0130] Hybrid Controller

[0131] The mixing control is primarily facilitated by flow-coupled filters—filters that couple the total flow output trajectory to the blower and oxygen flow controller. Each coupled filter receives a calibrated mixing target—adjusted by the mixing controller at each respiratory cycle based on the difference (if any) between the set mixing target and the mixing estimate described further below. The mixing controller is sample-based, meaning that mixing convergence is not uniform over time, but rather uniform with the number of breaths; the information provided at the end of each breath constitutes the sample used by the controller. This further improves mixing accuracy beyond what a single flow-coupled filter could achieve.

[0132] Hybrid estimator

[0133] Rebreathing, a term more often used to describe the subsequent inhalation of gas exhaled from a previous breath, is more generally used in ventilation control designs involving gas in any compartment of the gas path that may subsequently be returned to its origin. Therefore, rebreathing can exist, for example in a blower-based design, when the manifold pressure exceeds the pressure generated by the blower and the unexhaled gas being inhaled by the patient. Although the blower can rotate rapidly in the direction that would normally produce a forward flow, pressure applied from the downstream potential can cause the flow through the blower to reverse. If such a space exists, this can cause downstream gas to re-enter the blower and the blower inlet chamber.

[0134] The blower passage allows for the rebreathing of gases from two sources: the patient and the oxygen flowstream. In the patient's case, the gas returning to the blower compartment will be a mixture from subsequent breaths. Depending on other conditions, it is possible that oxygen can be directly forced into the blower compartment from the oxygen valve using the reverse blower flow. In this case, the volume of introduced gas is at 100% O2 enrichment during the rebreathing interval. In either case, the presence of rebreathing and the estimation of gas volume and mixture can be tracked using blower and oxygen flow sensors and then used to correct for subsequent mixing. Therefore, the oxygen concentration of the gas in the blower passage is not always 21% oxygen, but can instead be assigned an "enrichment factor" to account for the rebreathed gas until the blower flow is reversed and the compartment is cleared, where the enrichment factor returns to 0.21.

[0135] To track rebreathing and changes in enrichment factors, the flow state is defined based on the flow direction measured in the oxygen and blower flow sensors. The flow state serves as a trigger condition for transition logic in a state machine that calculates and maintains the oxygen mixing in the patient and blower compartment.

[0136] It is naturally expected that the mixture spreads across the gas path channels as the flow advances, but this is not easy to model quantitatively for real-time applications and therefore the mixture estimates are based on the assumption of piston flow, as if obvious boundaries exist between clumps of different gas mixtures.

[0137] refer to Figure 17 and Figure 18 In one embodiment, the definition of the flow state is derived from a conceptual diagram of the flow connection between the blower and the oxygen valve. Figure 17 It is a diagram defining the flow state based on a simplified diagram of the gas pathway of the system. Figure 18 This is a more quantitative definition of the flow state based on the relative magnitude and direction of the blower and oxygen flow. Further details of the flow state are described below.

[0138] Flow state 1: Blower with O2 from O2 valve

[0139] The flow proceeds to state 1, where oxygen and air from the blower and O2 valve are directed toward the patient. The blower pathway may contain nitrogen >0.21 because the rebreathing window at the oxygen valve inlet is active.

[0140] Flow state 1: Clean the blower

[0141] The flow proceeds to state 1, where both oxygen and air from the blower and O2 valve are directed towards the patient. The blower passage should be cleared of >0.21% nitride, as no rebreathing window is active.

[0142] Flow state 1: Blower with patient return gas

[0143] The flow proceeds to state 1, where oxygen and air from the blower and O2 valve are directed toward the patient. The blower pathway may contain >0.21% nitride because the flow exhaled by the patient at the rebreathing window is active.

[0144] Flow state 2

[0145] In this flow state, the O2 flow suppresses the blower flow, so O2 flows into the blower passage and toward the patient.

[0146] Flow state 3

[0147] The flow proceeds to state 3, where oxygen is set to zero and patient gas is returned from the loop to the ventilator. Only the blower flow is integrated into enriched gas from the patient.

[0148] In the state diagram, as respiration progresses, the process transitions between states. Two estimates are maintained: an estimate of the blower enrichment factor and an estimate of the gas delivered from the patient port. (Reference) Figure 19 In one embodiment, an example state machine hybrid estimator is shown, illustrating the input (right) and output (left).

[0149] Flow state 3 essentially defines patient exhalation, where the exhaled gas flow from the lungs exceeds the leakage rate present in the patient circuit at some point. Since there is no sensor for estimating the gas enrichment (from the patient), it can be assumed that the returned gas is emitted from the instantaneous time interval of the guided exhalation. Previous inventions simply assumed an average mixing enrichment factor for the returned gas, but this invention takes into account the possibility of significant gradients existing through the patient circuit. Therefore, a last-in-first-out (LIFO) approach is used. This invention reverts to the same mixing estimation profile emitted during inhalation, however, instead of based on time, based on volume. This is accomplished through buffer volume and mixing estimation data that begin immediately after flow state 3. Thus, the (unknown) occurrence of the initiation of flow state 3 can begin at any point in the respiration.

[0150] Although the above analysis is for examination of certain embodiments, these are provided merely as examples. Many other embodiments have been described above, and variations thereof are contemplated with respect to single-limb noninvasive ventilation systems and methods.

[0151] All definitions used herein should be understood to be governed by the dictionary definition, the definition in the document incorporated by reference, and / or the general meaning of the defined terms. Unless clearly indicated to the contrary, the indefinite articles “a” and “an” as used herein in the specification and claims should be understood to mean “at least one”.

[0152] The phrase “and / or” as used herein in the specification and claims should be understood to mean “any one or both” of the elements so combined (i.e., elements that are combined in some cases and separate in others). Multiple elements listed with “and / or” should be understood in the same way as “one or more” of the elements so combined. Elements other than those specifically identified by the “and / or” clause may optionally be present, whether related to or unrelated to those specifically identified elements.

[0153] As used herein in the specification and claims, “or” should be understood to have the same meaning as “and / or” as defined above. For example, when separating items in a list, “or” or “and / or” should be interpreted as inclusive, i.e., including at least one of a plurality of elements or a list of elements, and including more than one, and optionally including additional unlisted items. Terms that clearly indicate the opposite, such as “only one of” or “exact one of” or, when used in the claims, “consisting of”, will refer to including a plurality of elements or an exact one of a list of elements. In general, the term “or” as used herein should be interpreted only as indicating an exclusive substitution (i.e., “one or the other but not both”) when preceded by an exclusive term (such as “any one,” “one of,” “only one of,” or “exact one of”).

[0154] As used herein in the specification and claims, the phrase "at least one" when referring to a list of one or more elements should be understood to mean at least one element selected from any one or more elements in the list of elements, but does not necessarily include at least one of every element specifically listed in the list of elements, and does not exclude any combination of elements in the list of elements. This definition also allows for the optional presence of elements other than those specifically identified in the list of elements referred to by the phrase "at least one," whether related to or not related to those specifically identified elements.

[0155] It should also be understood that, unless clearly indicated to the contrary, in any method claimed herein that includes more than one step or action, the order of the steps or actions of the method is not necessarily limited to the order in which the steps or actions of the method are described.

[0156] In the claims and in the foregoing description, all transitional words such as “comprising,” “including,” “carrying,” “having,” “containing,” “involving,” “holding,” and “composed of” should be understood as open-ended, meaning including but not limited to. Only the transitional words “composed of” and “substantially composed of” should be closed or semi-closed transitional phrases, as set forth in Section 2111.03 of the U.S. Patent Examination Procedure Manual.

[0157] Although several inventive embodiments have been described and illustrated herein, those skilled in the art will readily conceive of various other means and / or structures for performing the functions described herein and / or obtaining one or more of the results and / or advantages described herein, and each of such variations and / or modifications is considered to be within the scope of the inventive embodiments described herein. More generally, those skilled in the art will readily recognize that all parameters, dimensions, materials, and configurations described herein are intended to be exemplary and that actual parameters, dimensions, materials, and / or configurations will depend on the specific application or application to which the teachings of the invention are applied. Those skilled in the art will realize or be able to determine many equivalents of the particular inventive embodiments described herein using only conventional experimentation. Therefore, it should be understood that the foregoing embodiments are presented by way of example only and, within the scope of the appended claims and their equivalents, the inventive embodiments can be practiced in ways other than those specifically described and claimed. The inventive embodiments of this disclosure relate to each individual feature, system, article of manufacture, material, kit, and / or method described herein. In addition, any combination of two or more such features, systems, articles of manufacture, materials, kits, and / or methods (if such features, systems, articles of manufacture, materials, kits, and / or methods are not inconsistent with each other) is included within the scope of the invention disclosed herein.

Claims

1. A storage medium encoded with one or more programs, said one or more programs, when executed on one or more processors and / or controllers, performing operations for controlling oxygen mixing of a single-limb non-invasive ventilator, said single-limb non-invasive ventilator including a pressure controller, and further including both an air blower and a pressurized oxygen source, wherein said pressurized oxygen source is downstream of said air blower, each of said air blower and said pressurized oxygen source including a controller, and said pressurized oxygen source including a proportional flow valve for controlling flow, said operations including: The target pressure and target oxygen are received and mixed by the ventilator; The total flow trajectory is generated from the output of the pressure controller; The generated total flow trajectory is provided from the pressure controller to a pair of complementary flow-coupled filters, which includes a blower flow-coupled filter and an oxygen flow-coupled filter. An output is generated from each of the blower flow coupling filter and the oxygen flow coupling filter, the outputs respectively including the input flow trajectory of the blower flow controller and the input flow trajectory of the oxygen flow controller; as well as The blower speed or the proportional flow valve of the pressurized oxygen source is adjusted by the blower flow controller and / or the oxygen flow controller based on the input flow trajectory and the received target pressure and target oxygen mixture.

2. The storage medium according to claim 1, wherein the oxygen flow coupling filter comprises a low-pass coupling filter.

3. The storage medium of claim 2, wherein the blower flow coupling filter comprises a high-pass coupling filter relative to the oxygen flow coupling filter.

4. The storage medium of claim 1, wherein the complementary current-coupled filter pair is configured to be complementary to divide the actuator effects across different frequency bands.

5. The storage medium according to claim 1, wherein the pressure controller comprises a multi-stage cascaded feedback architecture.

6. The storage medium of claim 1, wherein the single-limb noninvasive ventilator further comprises a complementary filter that feeds back to the pressure controller, the complementary filter being configured to receive pressure measurements from a ventilator pressure sensor and from a proximal pressure sensor in the patient circuit.

7. The storage medium of claim 6, wherein the complementary filter is configured to generate a single pressure signal to the pressure controller by fusing pressure measurements received from the ventilator pressure sensor with proximal pressure measurements received from the proximal pressure sensor.

8. The storage medium of claim 7, wherein the complementary filter is configured to fuse the received pressure measurement results using complementary frequency bands with the proximal pressure sensor signal at a low frequency and the ventilator pressure sensor signal at a higher frequency.

9. A single-limb non-invasive ventilation system configured to control oxygen mixing based on a target pressure and a target oxygen mixture, comprising: The pressure controller is configured to generate the total flow trajectory; An air blower, including a blower flow controller and a speed controller for controlling the blower flow; A pressurized oxygen source, downstream of the blower, includes an oxygen flow controller and a proportional flow valve for controlling the oxygen flow. A complementary flow-coupled filter pair, the complementary flow-coupled filter pair comprising a blower flow-coupled filter and an oxygen flow-coupled filter; as well as The controller is configured to: (i) provide the generated total flow trajectory from the pressure controller to the complementary flow-coupled filter pair; (ii) receiving an output from each of the blower flow coupling filter and the oxygen flow coupling filter, the output comprising the input flow trajectory of the blower flow controller and the input flow trajectory of the oxygen flow controller, wherein the blower flow controller and / or the oxygen flow controller adjusts the air blower speed or the proportional flow valve of the flow controller and / or the pressurized oxygen source based on the input flow trajectory and the target pressure and target oxygen mixing.

10. The single-limb non-invasive ventilation system according to claim 9, wherein the oxygen flow coupling filter includes a low-pass coupling filter.

11. The single-limb non-invasive ventilation system of claim 10, wherein the blower flow coupling filter comprises a high-pass coupling filter relative to the oxygen flow coupling filter.

12. The single-limb non-invasive ventilation system of claim 9, wherein the complementary flow-coupled filter pair is configured to be complementary to divide the actuator effects into different frequency bands.

13. The single-limb non-invasive ventilation system of claim 9, wherein the single-limb non-invasive ventilation system further comprises a complementary filter that feeds back to the pressure controller, the complementary filter being configured to receive pressure measurements from the ventilator pressure sensor and from a proximal pressure sensor in the patient circuit.

14. The single-limb non-invasive ventilation system of claim 13, wherein the complementary filter is configured to generate a single pressure signal to the pressure controller by fusing pressure measurements received from the ventilator pressure sensor with proximal pressure measurements received from the proximal pressure sensor.

15. The single-limb non-invasive ventilation system of claim 14, wherein the complementary filter is configured to fuse the received pressure measurement results using complementary frequency bands with the proximal pressure sensor signal at a low frequency and the ventilator pressure sensor signal at a higher frequency.

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