Respiratory systems and methods

Abstract

The present disclosure relates to a system and method for providing a flow of respiratory gas to a patient, the system including a controller, a flow regulator, and one or more sensors, the controller configured to control the flow regulator to regulate the flow of respiratory gas in response to a determined pressure in the system that exceeds or does not exceed a pressure threshold.

Description

Technical Field

[0001] The present disclosure relates to systems and methods for controlling a respiratory gas flow to a patient.

[0002] Specifically, but not limited thereto, the systems and methods control the respiratory gas flow to the patient in response to a change in system pressure downstream of a flow regulator that provides the respiratory gas flow.

Background Art

[0003] A patient may lose respiratory function during anesthesia or sedation, or more generally during certain medical procedures. Prior to a medical procedure, a patient may be pre-oxygenated by a medical professional to provide a reservoir of oxygen saturation, which is generally performed with bag ventilation and a face mask. Once under general anesthesia, the patient must be intubated to administer oxygen to the patient. In some cases, intubation is completed in 30 - 60 seconds, but in some cases, especially when it is difficult to advance through the patient's airway (e.g., due to cancer, severe injury, obesity or neck muscle spasms), intubation takes a very long time. While pre-oxygenation provides a buffer against a decrease in oxygen saturation, for a long intubation procedure, it is necessary to interrupt the intubation process and reapply the face mask to increase the patient's oxygen saturation to a sufficient level. Interruptions in the intubation process may occur several times for a difficult intubation process, which is time-consuming and exposes the patient to serious health risks. After attempting intubation about three times, the medical procedure is abandoned.

[0004] In procedures where multiple respiratory support systems are required, there is a concern that the combination of support systems may cause overpressure delivery (e.g., when a cannula is placed over the patient and the anesthesiologist desires delivery of respiratory support through a mask attached over the top of the cannula).

[0005] Furthermore, switching between different support systems can be time-consuming or difficult. Therefore, it may be desirable to have a configuration that allows for easy exchange between respiratory support systems, such as support via high-flow gas flow, and respiratory support via a face mask and bag or an anesthesia machine. It may also be desirable to be able to quickly and easily stop or reduce the gas flow.

[0006] No reference herein to any patent document or any other matter identified as prior art shall be construed as permission for such document or other matter to have been publicly known or for the information contained herein to have been part of the common general knowledge at the priority date of any claim. [Overview of the project] [Means for solving the problem]

[0007] In one aspect of the present disclosure, a respiratory system is provided for providing a respiratory gas flow to a patient, the system including a flow regulator and a controller configured to receive inputs of flow rate and pressure of a respiratory gas flow in the system, to control the flow regulator to provide the respiratory gas flow to the patient at a target flow rate, and to control the flow regulator to adjust the respiratory gas flow to a target pressure when the pressure of the respiratory gas flow in the system meets or exceeds a pressure threshold corresponding to the target flow rate.

[0008] In some embodiments, the target pressure includes a pressure threshold corresponding to a target flow rate or a pressure threshold corresponding to a flow rate less than the target flow rate.

[0009] In some embodiments, the controller is configured to control a flow regulator to adjust the breathing gas flow to a target pressure when the breathing gas flow rate is less than the target flow rate.

[0010] In some embodiments, the controller is configured to control a flow regulator to adjust the breathing gas flow to a target flow rate when the breathing gas flow rate exceeds a target flow rate.

[0011] In some embodiments, the controller is configured to control the flow regulator to a target pressure when the pressure of the breathing gas flow exceeds a pressure threshold corresponding to a target flow rate, or a pressure threshold corresponding to a flow rate less than the target flow rate.

[0012] In some embodiments, when the system starts operating from an "off" or dormant state, the controller is configured to monitor the flow rate of the breathing gas flow within the system and to control the flow regulator to adjust the breathing gas flow to a target flow rate. In some embodiments, the target flow rate changes over time to increase from a current value to a flow rate setpoint.

[0013] In some embodiments, the target flow rate is the flow rate setpoint. The flow rate setpoint may be determined by the user of the respiratory system. In some embodiments, the flow rate setpoint may be set by the user providing input to the controller.

[0014] In some embodiments, the controller includes a flow controller that provides a flow control output and a pressure controller that provides a pressure control output, and the control input to the flow regulator is the minimum value of the flow control output and the pressure control output.

[0015] In some embodiments, the flow regulator includes a blower, and the flow control output and pressure control output include the angular velocity of the blower.

[0016] In some embodiments, the flow regulator includes a proportional valve, and the flow control output and pressure control output include limiting the flow path to a fixed size through the proportional valve.

[0017] In some embodiments, the controller is configured to receive a flow rate value indicating the flow rate of the respiratory gas supplied to the patient.

[0018] In some embodiments, the controller may be able to operate in a first control mode when the flow rate exceeds a target flow rate in order to control the flow rate to a target flow rate, and the controller may be able to operate in a second control mode when the pressure of the breathing gas flow exceeds a pressure threshold corresponding to the target flow rate, or exceeds a certain pressure threshold corresponding to a flow rate less than the target flow rate, in order to control the pressure to a target pressure.

[0019] In some embodiments, the respiratory system includes one or more flow sensors configured to allow the patient to sense the flow rate of respiratory gas within the system.

[0020] In some embodiments, the respiratory system includes one or more pressure sensors configured to allow the patient to sense the pressure of the respiratory gas flow within the system.

[0021] In some embodiments, the controller is further configured to receive inputs from one or more flow sensors indicating the flow rate of the breathing gas flow in the system, and inputs from one or more pressure sensors indicating the pressure of the breathing gas flow in the system.

[0022] In some embodiments, the breathing system includes a delivery conduit for providing a gas flow from a flow regulator to a patient interface, and the patient interface is configured to deliver the breathing gas flow to the patient.

[0023] In some embodiments, the patient interface includes a nasal cannula, optionally an unsealed nasal cannula.

[0024] In some embodiments, the patient interface includes a gas delivery side arm that is in fluid communication with a delivery conduit, a manifold provided at the end of the gas delivery side arm, and one or more nasal elements extending from the manifold, configured to provide a respiratory gas flow to one or more nostrils of the patient, wherein the gas delivery side member includes a foldable portion.

[0025] The foldable part may be operable in a first configuration where the foldable part is substantially in an open state and a second configuration where the foldable part is substantially in a closed state.

[0026] In some embodiments, when the controller controls the flow regulator to a target pressure, the flow to the patient is reduced to a reduced flow rate of about 15 L / min or less, or about 10 L / min or less, or about 10 L / min, or about 5 L / min to about 10 L / min, or less than about 5 L / min, or 0 L / min.

[0027] In some embodiments, the controller is configured to control the flow regulator to increase the respiratory gas flow toward the target flow rate.

[0028] In some embodiments, the delivery conduit further includes a patient breathing circuit arranged between the delivery circuit and the patient interface, and the patient breathing circuit is connected to the delivery circuit by an outlet connector.

[0029] In some embodiments, the flow regulator includes one or more of a flow generator configured to be controlled by a controller to regulate the respiratory gas flow to the patient and a proportional valve configured to be controlled by a controller to regulate the respiratory gas flow.

[0030] In some embodiments, the flow generator includes a blower configured to be controlled by a controller to generate a respiratory gas flow.

[0031] In some embodiments, the respiratory system includes an O2 pressure sensor configured to sense the pressure within the oxygen (O2) delivery circuit of the respiratory system.

[0032] In some embodiments, the respiratory system includes an O2 flow sensor configured to sense the flow rate of the O2 flow within the oxygen (O2) delivery circuit of the respiratory system. In some embodiments, the proportional valve may be arranged between the O2 pressure sensor and the O2 flow sensor within the O2 delivery circuit.

[0033] In some embodiments, there is a patient breathing circuit, which may be connected to an O2 delivery circuit and an air delivery circuit, and the patient breathing circuit and / or patient interface may further include a patient pressure sensor and a patient flow sensor. In some embodiments, the flow regulator includes a blower, which may be arranged in the patient breathing circuit before the patient pressure sensor and the patient flow sensor.

[0034] In some embodiments, the controller is operably in communication with, or includes, a memory component that stores one or more functions, curves, lookup tables, or algorithms that provide a relationship between a pressure threshold and a corresponding flow rate.

[0035] In some embodiments, the controller is configured to control the flow regulator to reduce the breathing gas flow by a variable reduction rate.

[0036] In some embodiments, the relationship between the pressure threshold and the corresponding flow rate may be represented by a pressure limit curve or function that defines a curve having a sigmoid shape.

[0037] In some embodiments, the relationship between a pressure threshold and a corresponding flow rate includes a first pressure region, a second pressure region, and a transition region arranged between the first and second pressure regions.

[0038] In some embodiments, the first pressure region may correspond when the foldable portion is substantially in a first configuration, and the second region may correspond when the foldable portion is substantially in a second configuration.

[0039] In some embodiments, the first pressure region includes a pressure threshold offset by a first pressure margin from a reference pressure value, and the second pressure region includes a pressure threshold offset by a second pressure margin from a reference pressure value, thereby making the first pressure margin greater than the second pressure margin.

[0040] In some embodiments, the first and second margins provide an offset of the pressure threshold limit value in the first pressure region that is substantially parallel to the offset of the pressure threshold in the second pressure region of the pressure limit curve, and the first and second pressure regions correspond to the minimum rate of change of the breathing gas flow.

[0041] In some embodiments, the gradient of the transition region of the pressure limit curve corresponds to the maximum rate of change of the breathing gas flow.

[0042] In some embodiments, the transition region of the pressure limit curve may be centered on the transition flow rate. In some embodiments, the controller is configured to control the flow regulator so that the breathing gas flow reaches its maximum rate of change when the pressure and the corresponding flow rate are within the transition region of the pressure limit curve.

[0043] In some embodiments, the first and second pressure margins provide a margin for temporarily reducing the system pressure of the breathing gas flow from below a pressure threshold without the controller controlling the flow regulator to increase the breathing gas flow.

[0044] Viewed from another perspective, the present invention provides a respiratory system for providing a respiratory gas flow to a patient, the system comprising a controller and a flow regulator configured to be controlled by the controller to provide a respiratory gas flow to a patient, the controller being configured to control the flow regulator to a pressure setpoint that determines the flow rate, and the controller being configured to control the flow regulator to limit the flow rate of the respiratory gas flow to below the flow rate setpoint.

[0045] In some embodiments, the flow rate setpoint is set by the user of the respiratory system. In some embodiments, the flow rate setpoint may be set by the user providing input to the controller.

[0046] In some embodiments, the system includes several setpoints that determine the flow rates, and the controller is configured to control the flow regulator to those setpoints.

[0047] In some embodiments, the setpoint for determining the flow rate is based on the flow rate of the breathing gas stream.

[0048] In some embodiments, the setpoint for determining the flow rate is predetermined.

[0049] In some embodiments, the pressure setpoint used to determine the flow rate when the breathing gas flow rate is at or near the flow rate setpoint is separated from the normal system pressure value by a first margin, and the pressure setpoint used to determine the flow rate when the breathing gas flow rate is at or near 0 L / min is separated from the normal system pressure value by a second margin, with the first margin being greater than the second margin.

[0050] In some embodiments, when the respiratory gas flow rate is 0 L / min or close to it, the pressure setpoint used to determine the flow rate is 0 cmH2O.

[0051] In some embodiments, the flow regulator includes a blower and / or a proportional valve.

[0052] In some embodiments, the breathing system further includes one or more of a flow sensor, a pressure sensor, and a user interface.

[0053] In some embodiments, the respiratory system further includes an unsealed nasal interface that communicates with a flow regulator and fluid, and is configured to deliver a respiratory gas flow to the patient.

[0054] In some embodiments, the unsealed nasal interface includes a gas delivery side arm, a manifold provided at the end of the gas delivery side arm, and one or more nasal elements extending from the manifold, configured to deliver a respiratory gas flow to one or more nostrils of a patient, wherein the gas delivery side member includes a foldable portion.

[0055] In some embodiments, the foldable portion is operable in a first configuration in which it is substantially open, and in a second configuration in which it is substantially closed.

[0056] In some embodiments, the flow rate setting points are greater than 0 L / min, arbitrarily greater than 0 L / min to approximately 120 L / min, arbitrarily approximately 20 L / min to approximately 90 L / min, and arbitrarily approximately 40 L / min to approximately 70 L / min.

[0057] In another aspect of the present disclosure, a respiratory system is provided for providing a respiratory gas flow to a patient, the system comprising a controller and a flow regulator configured to be controlled by the controller for providing a respiratory gas flow to a patient, the controller being configured to receive inputs relating to a flow setpoint, one or more pressure inputs indicating a system pressure corresponding to a respiratory gas flow downstream of the flow regulator, one or more flow inputs indicating a respiratory gas flow downstream of the flow regulator, and to compare the received pressure and / or flow inputs with a predetermined pressure threshold and flow setpoint corresponding to the flow, and to control the flow regulator between two control modes, the first control mode comprising controlling the flow regulator to provide a respiratory gas flow to a flow setpoint when the system pressure is below a predetermined pressure threshold for the corresponding flow, and the second control mode comprising controlling the flow regulator to adjust the respiratory gas flow to a target pressure when the flow rate of the respiratory gas flow is below a flow setpoint.

[0058] In another aspect of the present disclosure, a respiratory system is provided for providing a respiratory gas flow to a patient, the system comprising a controller and a flow regulator configured to be controlled by the controller for providing a respiratory gas flow to a patient, the controller being configured to receive an input indicating system pressure, compare the system pressure to one or more pressure thresholds for a corresponding flow rate, control the flow regulator to reduce the system pressure in response to a system pressure that satisfies or exceeds one or more pressure thresholds for a corresponding flow rate, and control the flow regulator to reach a target flow rate in response to a system pressure that does not meet or exceed a pressure threshold for a corresponding flow rate.

[0059] In another aspect of the present disclosure, a respiratory system is provided for providing a respiratory gas flow to a patient, the system comprising a controller and a flow regulator configured to be controlled by the controller for providing a respiratory gas flow to a patient, the controller being configured to control the flow regulator to a flow rate setpoint, and the controller being configured to control the flow regulator to limit the pressure of the respiratory gas flow to below a pressure limit that determines the flow rate.

[0060] In another aspect of the present disclosure, a respiratory system is provided for providing a respiratory gas flow to a patient, the system comprising a controller, a flow regulator configured to be controlled by the controller for providing a respiratory gas flow to the patient, and one or more sensors configured to determine the pressure of the respiratory gas flow in the respiratory system to the patient, the controller being configured to receive inputs from one or more sensors indicating the pressure of the respiratory gas flow in the respiratory system, compare the pressure to a pressure threshold for a corresponding flow rate, and in response to a pressure exceeding the pressure threshold for a corresponding flow rate, control the flow regulator to reduce the respiratory gas flow, and in response to a pressure not exceeding the pressure threshold for a corresponding flow rate, control the flow regulator to regulate the respiratory gas flow.

[0061] The respiratory system controller may include a microcontroller, a PID (proportional-integral-derivative) controller, or a variation of a PID controller (such as a P, PI, or I controller) in which the proportional, derivative, and integral elements of the controller can be turned on or off as needed, or any other architecture configured to operate by algorithms stored in memory communicating with the controller to direct the operation of the controllable components of the respiratory system. Thus, the controller allows the respiratory system to control one or more components of the respiratory system in response to changes in pressure and / or flow within the system. The controller may also control a flow regulator in response to changes in pressure within the system. The pressure within the system may be the pressure downstream of the flow regulator. This is in contrast to a pressure relief valve, which relieves pressure within the system by typically venting gas to the atmosphere when the system pressure exceeds a pressure threshold. This venting of the delivery gas may be considered a waste source.

[0062] The respiratory system controller receives pressure input within the system and determines whether the pressure value within the system meets or exceeds a pressure threshold for the corresponding flow rate, which indicates occlusion (some flow may still be present across it) or blockage (no flow across it). In response, the controller controls components of the respiratory system, which may regulate the flow. After removing the occlusion or blockage, the controller also restores the desired flow to the respiratory system. A controller that controls the respiratory gas flow to the patient thus reduces the waste of gases such as oxygen. It may also reduce undesirable effects on the respiratory gas flow delivered to the patient via another respiratory support system; for example, the controller controls the respiratory gas flow via an anesthesia system used in conjunction with the system of this disclosure to minimize dilution of the anesthetic delivered to the patient. In situations where a mask may be used over a cannula, such as those described below, this can be advantageous by providing better control over the pressure acting on the closed / blocked (i.e., folded) portion, so that the user does not need to apply excessive force to the mask over the cannula and does not need to control any residual flow across the foldable portion associated with the cannula.

[0063] In some embodiments, the flow regulator includes a flow generator, such as a blower, configured to be controlled by a controller to generate a respiratory gas flow for the patient.

[0064] In some embodiments, the flow regulator includes a proportional valve configured to be controlled by a controller to regulate the breathing gas flow.

[0065] In some embodiments, the flow regulator further includes a proportional valve and a flow generator.

[0066] The algorithm implemented by the controller controls flow regulators, such as blowers and / or proportional valves, to provide pressure / flow control to the respiratory system supplying gas to the patient during respiratory support delivery. Examples of respiratory support are described above and include nasal high-flow, continuous positive airway pressure, and mechanical ventilation. The respiratory system may include two or more blowers and / or two or more proportional valves.

[0067] In some embodiments, the controller is further configured to determine the flow rate of the breathing gas flow from an input indicating the pressure of the breathing gas flow.

[0068] In another embodiment, the sensor includes one or more flow sensors configured to sense the flow rate of respiratory gas flow in a delivery conduit to a patient. The controller is further configured to receive inputs from these one or more flow sensors indicating the flow rate of respiratory gas flow in the delivery conduit. Preferably, the flow rate input is flow rate data.

[0069] In some embodiments, the pressure of the respiratory gas flow within the respiratory system is determined from data indicating the flow rate of the respiratory gas flow within the respiratory system.

[0070] In some embodiments, one or more sensors are configured to sense the pressure of the breathing gas flow in the breathing system downstream of the flow regulator. Preferably, one or more sensors are located downstream of the flow regulator.

[0071] In some embodiments, the sensors include one or more pressure sensors configured to sense the pressure of the respiratory gas flow in the system to the patient.

[0072] In some embodiments, one or more sensors include one or more pressure sensors and one or more flow sensors.

[0073] In some embodiments, the pressure of the breathing gas flow within the breathing system is the pressure of the breathing gas flow downstream of the flow regulator.

[0074] In some embodiments, the input indicating the pressure of the respiratory gas flow within the respiratory system includes data.

[0075] In some embodiments, the respiratory system further includes a delivery conduit and a patient interface at one end of the delivery conduit, the patient interface being configured to deliver a respiratory gas stream to the patient.

[0076] In some embodiments, the pressure of the breathing gas flow is the pressure of the breathing gas flow upstream of the foldable section or within the foldable section.

[0077] In one example, the patient interface is in fluid communication with the gas supply unit, and the gas flow is controlled by a flow regulator in the breathing system. Examples of the gas supply unit include a pressurizing source (such as a gas tank or a hospital wall supply unit), a blower, a mixer, or a combination thereof. The breathing system may also include a humidifier to humidify the gas before it is delivered to the patient.

[0078] In some embodiments, the patient interface includes an outlet received by the patient's nostril or mouth, and a gas delivery side member extending from the side of the outlet, the gas delivery side member including a lumen for gas flow from the inlet to the outlet of the patient interface, and a foldable portion. For example, the patient interface is a nasal cannula and optionally an unsealed nasal cannula.

[0079] In some embodiments, the foldable section is configured as in the first configuration and is foldable from the first configuration into the second configuration. In the second configuration, the breathing gas flow through the foldable section is a reduced flow rate compared to when the foldable section is in the first configuration. For example, the reduced flow rate is approximately 15 L / min or less, or approximately 10 L / min or less, or approximately 10 L / min, or approximately 5 L / min to approximately 10 L / min, or less than approximately 5 L / min, or 0 L / min.

[0080] In some embodiments, the controller is further configured to control the flow regulator to reduce the breathing gas flow to a reduced flow rate in response to a pressure exceeding a pressure threshold for a corresponding flow rate. For example, the breathing gas flow is gradually reduced to a reduced flow rate. In some embodiments, the controller is configured to control the flow regulator to reduce the pressure in the system, and then reduce the breathing gas flow (as determined by the pressure change and the resistance to the flow in the system). For example, the pressure in the system may be reduced, for example, by gradually decreasing the operation of the flow regulator.

[0081] In some embodiments, the controller is further configured to control the flow regulator to continuously reduce the breathing gas flow toward a reduced flow rate. Alternatively / additionally, the controller may be configured to control the flow regulator, for example, by reducing its operation, to continuously reduce the pressure in the system toward a pressure target.

[0082] In some embodiments, the controller is further configured to control a flow regulator to adjust the breathing gas flow to a target flow rate in response to a pressure that does not exceed a pressure threshold for the corresponding flow rate. For example, the target flow rate may be 40 to 70 L / min.

[0083] In some embodiments, the controller is further configured to control a flow regulator in order to continuously adjust the breathing gas flow toward a target flow rate.

[0084] In some embodiments, the controller is further configured to control a flow regulator to increase the breathing gas flow toward a target flow rate.

[0085] In one example, the breathing gas flow is gradually increased to a target flow rate. Alternatively, the controller is configured to control the flow regulator to continuously increase the breathing gas flow toward a target flow rate.

[0086] In some embodiments, the delivery conduit further includes a delivery circuit and a patient breathing circuit arranged between the delivery circuit and the patient interface, the patient breathing circuit being connected to the delivery circuit by an outlet connector.

[0087] In some embodiments, the delivery conduit further includes a delivery circuit and a patient breathing circuit arranged between the delivery circuit and the patient interface, the patient breathing circuit being connected to the delivery circuit by an outlet connector.

[0088] In some embodiments, the controller, flow regulator, one or more sensors, and delivery circuit are housed within a housing, and the outlet connector is mounted on the housing. For example, the housing is a box.

[0089] In some embodiments, one or more sensors include an O2 pressure sensor configured to sense the pressure of the O2 flow from the O2 supply unit to the patient in the oxygen (O2) delivery circuit of the respiratory system.

[0090] In some embodiments, one or more sensors include an O2 flow sensor configured to sense the flow rate of O2 from an oxygen (O2) supply unit to the patient.

[0091] In some embodiments, a proportional valve is arranged between an O2 pressure sensor and an O2 flow sensor within the O2 delivery circuit.

[0092] In some embodiments, one or more sensors include an air pressure sensor configured to sense the pressure of the airflow from ambient air to the patient within the air delivery circuit of the respiratory system.

[0093] In some embodiments, the blower is arranged after the air pressure sensor in the air delivery circuit.

[0094] In some embodiments, the patient breathing circuit is connected to an O2 delivery circuit and an air delivery circuit, and the patient breathing circuit and / or patient interface further includes a patient pressure sensor and a patient flow sensor.

[0095] In some embodiments, the patient breathing circuit is connected to an O2 delivery circuit and an air delivery circuit, and the patient breathing circuit and / or patient interface further includes a patient pressure sensor and a patient flow sensor.

[0096] In some embodiments, the blower is positioned within the patient breathing circuit before the patient pressure sensor and the patient flow sensor.

[0097] In some embodiments, the pressure threshold for the corresponding flow rate forms a pressure limit curve.

[0098] In some embodiments, the pressure threshold for the corresponding flow rate forms a pressure limit curve. In those embodiments, the controller is further configured to compare the pressure and flow rate with the pressure limit curve.

[0099] In some embodiments, the pressure limit curve relates to the restriction of flow within the respiratory system and / or delivery conduit.

[0100] In some embodiments, the flow regulator is configured to reduce the breathing gas flow by a rate of reduction corresponding to a pressure limit curve.

[0101] In some embodiments, the pressure limit curve is sigmoid-shaped.

[0102] In some embodiments, the sigmoid-shaped pressure limit curve includes a first pressure region, a second pressure region, and a transition region arranged between the first and second pressure regions.

[0103] In some embodiments, the first pressure region corresponds to the first configuration, and the second pressure region corresponds to the second configuration.

[0104] In some embodiments, in a first configuration, the normal operating pressure of the breathing gas flow in the delivery conduit is lower than the pressure limit curve by a first pressure margin, and in a second configuration, the normal operating pressure of the breathing gas flow is lower than the pressure limit curve by a second pressure margin, thereby the first pressure margin being substantially larger than the second pressure margin. The first and second pressure margins can provide margins to temporarily increase the pressure of the breathing gas flow from the normal pressure so as not to reduce the breathing gas flow.

[0105] In another embodiment, the first and second pressure margins provide a margin to temporarily reduce the pressure of the breathing gas flow from the normal pressure so as not to increase the breathing gas flow.

[0106] In some embodiments, the first pressure region is substantially parallel to the second pressure region of the pressure limit curve, and the first and second pressure regions correspond to the minimum reduction rate of the breathing gas flow.

[0107] In some embodiments, the transition region of the pressure limit curve corresponds to the maximum reduction rate of the breathing gas flow.

[0108] In some embodiments, the transition region of the pressure limit curve is centered on the transition flow rate.

[0109] In some embodiments, the flow regulator is configured to reduce the breathing gas flow by the maximum reduction rate when the pressure and corresponding flow rate are in the transition region of the pressure limit curve.

[0110] In another aspect of the present disclosure, a respiratory system is provided for providing a respiratory gas flow to a patient, the system comprising a controller, a flow regulator configured to be controlled by the controller for providing a respiratory gas flow to the patient, one or more sensors configured to determine the pressure of the respiratory gas flow in the respiratory system to the patient, and a patient interface configured to fluidly communicate with the flow regulator and deliver the respiratory gas flow to the patient, the patient interface comprising an inlet for receiving the respiratory gas flow from the flow regulator, an outlet for delivering the respiratory gas flow to the patient's airway, and a switch between a first configuration and a second configuration. The breathing system includes a gas conduit with a foldable section configured to allow the breathing gas flow to be adjusted, wherein the pressure of the breathing gas flow in the breathing system when the foldable section is in a second configuration is greater than the pressure of the breathing gas flow in the breathing system when the foldable section is in a first configuration, and the controller is configured to receive inputs from one or more sensors indicating the pressure of the breathing gas flow in the breathing system, compare the pressure to a pressure threshold, and in response to a pressure that meets or exceeds the pressure threshold, control a flow regulator to provide a first adjustment of the breathing gas flow, and in response to a pressure that does not meet or exceed the pressure threshold, control a flow regulator to provide a second adjustment of the breathing gas flow.

[0111] In some embodiments, the second adjustment differs from the first adjustment.

[0112] In some embodiments, the first adjustment includes reducing or maintaining the breathing gas flow.

[0113] In some embodiments, the first adjustment includes reducing the breathing gas flow in response to a pressure exceeding a pressure threshold.

[0114] In some embodiments, the first adjustment includes reducing or maintaining the breathing gas flow in response to a pressure that satisfies a pressure threshold.

[0115] In some embodiments, the second adjustment includes increasing the breathing gas flow.

[0116] In some embodiments, the second adjustment includes adjusting the breathing gas flow to a target flow rate.

[0117] In some embodiments, one or more sensors are placed downstream of the flow regulator.

[0118] In some embodiments, the respiratory system further includes a delivery conduit configured to deliver a respiratory gas flow from a flow regulator to a patient interface.

[0119] In some embodiments, the delivery conduit further includes a delivery circuit and a patient breathing circuit arranged between the delivery circuit and the patient interface, the patient breathing circuit being connected to the delivery circuit by an outlet connector.

[0120] In some embodiments, the controller, flow regulator, one or more sensors, and delivery circuit are housed within a housing, and the outlet connector is mounted on the housing.

[0121] In some embodiments, the flow regulator includes a flow generator configured to be controlled by a controller to generate a respiratory gas flow to the patient.

[0122] In some embodiments, the flow regulator includes a proportional valve configured to be controlled by a controller to regulate the breathing gas flow.

[0123] In some embodiments, the flow regulator further includes a proportional valve and a flow generator.

[0124] In some embodiments, the flow generator includes a blower configured to be controlled by a controller to generate a breathing gas flow.

[0125] In some embodiments, one or more sensors include an O2 pressure sensor configured to sense the pressure of the O2 flow from the O2 supply unit to the patient in the oxygen (O2) delivery circuit of the respiratory system.

[0126] In some embodiments, one or more sensors include an O2 flow sensor configured to sense the flow rate of O2 from an oxygen (O2) supply unit to the patient.

[0127] In some embodiments, a proportional valve is positioned between an O2 pressure sensor and an O2 flow sensor in an O2 delivery circuit.

[0128] In some embodiments, one or more sensors include an air pressure sensor configured to sense the pressure of the airflow from ambient air to the patient within the air delivery circuit of the respiratory system.

[0129] In some embodiments, the blower is positioned after the air pressure sensor in the air delivery circuit.

[0130] In some embodiments, the patient breathing circuit is connected to an O2 delivery circuit and an air delivery circuit, and the patient breathing circuit and / or patient interface further includes a patient pressure sensor and a patient flow sensor.

[0131] In some embodiments, the blower is positioned within the patient breathing circuit before the patient pressure sensor and the patient flow sensor.

[0132] In some embodiments, one or more sensors include one or more pressure sensors configured to sense the pressure of the respiratory gas flow in the system to the patient. One or more pressure sensors are configured to sense the pressure of the respiratory gas flow in the respiratory system downstream of the flow regulator.

[0133] In some embodiments, the input indicating the pressure of the respiratory gas flow within the respiratory system includes data.

[0134] In some embodiments, the pressure of the breathing gas flow within the breathing system is the pressure of the breathing gas flow downstream of the flow regulator.

[0135] In some embodiments, the pressure of the breathing gas flow is the pressure of the breathing gas flow upstream of the foldable section or within the foldable section.

[0136] Another aspect of the present disclosure provides a method for operating a respiratory system to provide a respiratory gas flow to a patient, the method comprising: providing a respiratory gas flow to a patient in the respiratory system; determining the pressure of the respiratory gas flow to the patient in the respiratory system using one or more sensors configured to determine the pressure of the respiratory gas flow in the respiratory system; receiving inputs from one or more sensors indicating the pressure of the respiratory gas flow in the system; comparing the pressure to a pressure threshold for a corresponding flow rate; controlling a flow regulator to reduce the respiratory gas flow in response to a pressure exceeding the pressure threshold for a corresponding flow rate; and controlling a flow regulator to adjust the respiratory gas flow in response to a pressure not exceeding the pressure threshold for a corresponding flow rate.

[0137] Another aspect of the present disclosure provides a method for operating a respiratory system as described above, the method comprising: providing a respiratory gas flow to a patient in the respiratory system; determining the pressure of the respiratory gas flow to the patient in the respiratory system using one or more sensors configured to determine the pressure of the respiratory gas flow in the respiratory system; receiving inputs from one or more sensors indicating the pressure of the respiratory gas flow in the system; comparing the pressure to a pressure threshold for a corresponding flow rate; controlling a flow regulator to reduce the respiratory gas flow in response to a pressure exceeding the pressure threshold for a corresponding flow rate; and controlling a flow regulator to adjust the respiratory gas flow in response to a pressure not exceeding the pressure threshold for a corresponding flow rate.

[0138] Next, embodiments of this disclosure will be described in more detail with reference to the following figures. [Brief explanation of the drawing]

[0139] [Figure 1] This is a schematic diagram of an example of a respiratory system for providing respiratory gas to a patient. [Figure 2a] An embodiment of the present disclosure shows a patient wearing a first patient interface for use with a respiratory system for providing respiratory gas to the patient. [Figure 2b] An embodiment of the present disclosure shows a patient wearing a first patient interface with a second patient interface for use in conjunction with a respiratory system for providing respiratory gas to the patient. [Figure 3a] A schematic diagram of the first configuration of the foldable part of the patient interface is provided. [Figure 3b] A schematic diagram of the second configuration of the foldable part of the patient interface is provided. [Figure 4] This is a schematic diagram of a respiratory system for providing respiratory gas to a patient according to an embodiment of the present disclosure. [Figure 5] This is a schematic diagram of a respiratory system for providing respiratory gas to a patient according to an embodiment of the present disclosure. [Figure 6] This is a schematic diagram of a respiratory system for providing respiratory gas to a patient according to an embodiment of the present disclosure. [Figure 7] This is a schematic diagram of a respiratory system for providing respiratory gas to a patient according to an embodiment of the present disclosure. [Figure 8] This is a schematic diagram of a respiratory system for providing respiratory gas to a patient according to an embodiment of the present disclosure. [Figure 9] This is a graph showing a curve representing the relationship between flow and pressure, used when controlling the breathing gas flow according to embodiments of the present disclosure. [Figure 10] This is a graph showing a curve representing the relationship between flow and pressure, used when controlling the breathing gas flow according to embodiments of the present disclosure. [Figure 11] This is a graph showing another curve representing the relationship between flow and pressure, used when controlling the breathing gas flow according to embodiments of the present disclosure. [Figure 12] The zero-flow pressure curve is a graph that shows that a nominal pressure limit (curve R) or a zero pressure limit (curve S) can exist. [Figure 13] This is a graph showing a curve representing the relationship between flow and pressure offset, used when controlling the breathing gas flow according to embodiments of the present disclosure. [Figure 14]This graph shows the relationship between pressure and flow rate as the resistance to the flow experienced by the system increases. [Figure 15] This is a state diagram showing the operating state of a respiratory system according to an embodiment of the present disclosure. [Figure 16] This is a flowchart illustrating the operation of a respiratory system according to an embodiment of the present disclosure. [Figure 17] This is a flowchart illustrating a method for operating a respiratory system according to embodiments of the present disclosure. [Modes for carrying out the invention]

[0140] Throughout the figures and specifications, similar reference numbers may be used to indicate the same or similar components, and redundant descriptions of them may be omitted.

[0141] As mentioned, the respiratory system provides gas for delivery to the patient. The respiratory system may take many forms, such as continuous positive airway pressure (CPAP) systems and high-flow breathing gas systems (e.g., for high-flow therapy and anesthetic procedures).

[0142] In this specification, “high flow” means any gas flow that is higher than normal / normal, such as higher than the normal inspiratory flow rate of a healthy patient. Alternatively or additionally, “high flow” may be higher than some other threshold flow rate in relation to the situation, for example, if a gas flow is provided to a patient at a flow rate that meets inspiratory demand, that flow rate may be considered “high flow” because it is higher than the nominal flow rate that might otherwise have been supplied. “High flow” is therefore situational, and what constitutes “high flow” depends on many factors, such as the patient’s health condition, the type of procedure / treatment / support provided, the patient’s characteristics (large, small, adult, child) and similar. A person skilled in the art should recognize what constitutes “high flow” from the situation. “High flow” is the magnitude of a flow rate that exceeds the flow rate that might otherwise have been supplied.

[0143] However, without limitations, some of the values ​​indicating high flow can be as follows:

[0144] In some configurations, gas is delivered to the patient at a flow rate of approximately 5 or 10 liters per minute (5 or 10 LPM or L / min) or more.

[0145] In some configurations, gas is delivered to the patient at flow rates of approximately 5 or 10 LPM to approximately 150 LPM, or approximately 15 LPM to approximately 95 LPM, or approximately 20 LPM to approximately 90 LPM, or approximately 25 LPM to approximately 85 LPM, or approximately 30 LPM to approximately 80 LPM, or approximately 35 LPM to approximately 75 LPM, or approximately 40 LPM to approximately 70 LPM, or approximately 45 LPM to approximately 65 LPM, or approximately 50 LPM to approximately 60 LPM. For example, according to various embodiments and configurations described herein, the flow rate of the gas supplied to the interface via the system or from a flow source or flow regulator may include, but is not limited to, flows of at least about 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150 LPM or more, and a beneficial range may be selected to include any of these values ​​(e.g., about 20 LPM to about 90 LPM, about 40 LPM to about 70 LPM, about 40 LPM to about 80 LPM, about 50 LPM to about 80 LPM, about 60 LPM to about 80 LPM, about 70 LPM to about 100 LPM, about 70 LPM to about 80 LPM).

[0146] In "high-flow" systems, the delivered gas is selected depending on the intended use, for example, in a therapeutic context. The delivered gas may contain a certain percentage of oxygen. In some configurations, the percentage of oxygen in the delivered gas may be approximately 15% to 100%, 20% to 100%, 30% to 100%, 40% to 100%, 50% to 100%, 60% to 100%, 70% to 100%, 80% to 100%, 90% to 100%, 100%, or 100%.

[0147] In some embodiments, the delivered gas may contain a certain percentage of carbon dioxide. In some configurations, the percentage of carbon dioxide in the delivered gas may be greater than 0%, about 0.3% to about 100%, about 1% to about 100%, about 5% to about 100%, about 10% to about 100%, about 20% to about 100%, or about 30% to about 100%, or about 40% to about 100%, or about 50% to about 100%, or about 60% to about 100%, or about 70% to about 100%, or about 80% to about 100%, or about 90% to about 100%, or about 100%, or 100%.

[0148] The flow rate for "high flow" for premature infants / babies / children (weighing approximately 1 to 30 kg) may vary. The flow rate can be set from 0.4 to 8 L / min / kg, with a minimum of approximately 0.5 L / min and a maximum of approximately 70 L / min. For patients weighing less than 2 kg, the maximum flow rate may be set to 8 L / min.

[0149] Effective high-flow treatments have been found that meet or exceed the patient's normal inspiratory flow in order to increase the patient's oxygen supply and / or reduce the work of breathing. Additionally, high-flow treatment can produce a flushing effect in the nasopharynx, so that the anatomical dead space of the upper airway is flushed out by the high inhaled gas flow. This minimizes rebreathing of carbon dioxide, nitrogen, and other gases while generating a store of fresh gas available with each breath.

[0150] As an example, the high-flow breathing system 10 is described with reference to Figure 1. High flow may be used as a means to improve gas exchange and / or respiratory support through the delivery of oxygen and / or other gases, and through the removal of CO2 from the patient's airway. High flow may be particularly effective before, during, or after medical and / or anesthetic procedures.

[0151] When used before a medical procedure, a high gas flow can pre-load the patient with oxygen to provide an oxygen buffer during apnea phases in the medical procedure, resulting in higher blood oxygen saturation and oxygen volume in the lungs.

[0152] Continuous oxygen supply is crucial for maintaining healthy respiratory function during medical procedures (such as anesthesia) where respiratory function may be impaired (e.g., weakened or stopped). If this supply is disrupted, hypoxia, hypoxemia, and / or hypercapnia may occur. During medical procedures such as anesthesia and / or sedation, when the patient is unconscious or may become unconscious, the patient is monitored to detect when this occurs. If oxygen supply and / or CO2 removal is impaired, the clinician should stop the medical procedure and facilitate oxygen supply and / or CO2 removal. This can be achieved, for example, by manually ventilating the patient, such as by bag-mask ventilation, or by using a high-flow ventilation system to deliver a high flow of gas to the patient's airways. Furthermore, it should be recognized that masks used for sedation / ventilation (not necessarily limited to bag-masks) may also be used for pre-oxygenation and to monitor patient parameters such as end-respiratory carbon dioxide, etc.

[0153] Further advantages of high gas flow include the fact that high gas flow increases pressure within the patient's airways, thereby providing a pressure supply that opens the airways, trachea, lungs / alveoli, and bronchioles. Opening these structures enhances oxygen delivery and, to some extent, assists in CO2 removal.

[0154] When humidified, high gas flow can prevent airway dryness, mitigate mucociliary damage, and reduce the risk of laryngospasm, as well as risks associated with airway dryness such as nosebleeds, aspiration (as a result of nosebleeds), and airway obstruction, swelling, and bleeding. Another advantage of high gas flow is that the flow can clear smoke generated in the airway during surgery. Smoke, for example, can be generated by lasers and / or cauterization devices.

[0155] Referring to Figure 1, System 10 may include an arrangement based on integrated or separate components, generally shown in Figure 1 within the dotted box 11. In some configurations, System 10 may include a modular arrangement of components. System 10 may include a flow source 12, such as a wall-mounted oxygen source, oxygen tank, blower, flow therapy device, or any other source of oxygen or other gas, or a combination thereof. In some embodiments, the flow source 12 includes a flow regulator, and in some embodiments, the flow regulator includes a flow generator, such as a blower, bellows, and / or piston. In some embodiments, the flow regulator includes a flow generator and a proportional valve, the proportional valve may function to control the oxygen concentration in a mixed gas flow, such as air (preferably filtered air) and oxygen delivered to the patient. In some embodiments, the flow regulator includes a proportional valve, and in such embodiments, the flow regulator may not include a flow generator. Examples of systems including a flow generator and a proportional valve in this context are described in relation to Figures 7 and 8. In other embodiments, the flow source 12 does not need to include a flow generator, and in such embodiments, the flow source 12 may include a wall-mounted gas source and / or a mixed gas or other gas supply unit. In some embodiments, the flow source 12 may include a compressed gas source (e.g., a wall-mounted gas source, an oxygen tank supply unit, etc.) and a blower.

[0156] In some embodiments, the flow source 12 includes or is part of an anesthesia machine. The system 10 may also include an additive gas source 12A containing one or more other gases that can be combined with the gas from the flow source 12. The flow source 12 can provide a gas flow 13 that can be delivered to the patient 16 via a delivery conduit 14 and a patient interface 15 (such as a nasal cannula). The gas flow 13 may deliver a high flow to the patient in the context described above. The controller 19 controls the flow source 12 and the additive gas source 12A through valves or similar devices to control the flow and other characteristics, such as the flow rate, pressure, composition, concentration, volume, etc., of the gas flow 13. A humidifier 17 is also optionally provided, which can humidify the gas and / or control the temperature of the gas, for example, under the control of the controller 19. One or more of the sensors 18a, 18b, 18c, and 18d, such as flow, oxygen, pressure, humidity, temperature, or other sensors, may be placed through the system and / or on, on, or near the patient 16. The sensors may include a pulse oximeter 18d on the patient to determine the oxygen concentration in the blood.

[0157] The controller 19 may be operably connected to one or more components of the system 10 by various means, including wired or wireless connections. For example, the controller 19 may be operably connected to one or more of the flow source 12, the additive gas source 12A, the humidifier 17 and sensors 18a-18d, and the input / output (I / O) interface 20. For example, the controller 19 may be provided on or in a high-flow device or a separate component, and / or may be incorporated into or used with another device such as an anesthesia machine or a ventilator, or may be part of the system 10 and communicate with one or more separate controllers that control the operation of a separate component used with the system 10 to provide respiratory support to a patient. The controller may include a microcontroller, a PID (proportional-integral-derivative) controller, or a variation of a PID controller (such as a P, PI, or I controller) in which the proportional, derivative, and integral elements of the controller can be turned on or off as needed, or any other architecture configured to operate by an algorithm stored in memory that communicates with the controller to instruct the operation of controllable components of the respiratory system. Thus, the controller 19 may control the flow source 12 and other components of the system 10, or other components used with the system 10, to provide the patient with a delivered gas flow having specific characteristics such as desired flow rate, pressure, components (if more than two gases are provided), volume, and / or other parameters based on feedback from one or more sensors 18a-18d. The controller 19 may also control any other appropriate parameters of the flow source to meet oxygen administration, airway pressure, and / or patient flow requirements, and / or system pressure and / or system flow requirements (e.g., predetermined or set by the user through interface 20). The controller 19 can also control the humidifier 17, and this control may be based on feedback from one or more sensors 18a to 18d.Using the input from the sensor, the controller may determine any operational changes necessary to meet the oxygen delivery requirements and, if necessary, modify the control parameters of the flow source 12 and / or the humidifier 17 and / or other additive gas sources 12A and / or other components of the system.

[0158] An input / output (I / O) interface 20 (such as a display and / or input device) may be provided. The interface 20 can receive information and inputs (such as required patient respiratory support parameters) from a user (e.g., a clinician or patient) which can be used to determine oxygen administration, pressure, flow requirements and / or other system settings, used to control one or more of the flow source 12, the supplement gas source 12A and other components of the system 10, in order to achieve a gas flow 13 with the necessary features to provide the required respiratory support. In some embodiments, the system may not have a controller and / or I / O interface. A healthcare professional, such as a nurse or technician, may provide the necessary control functions.

[0159] As described above, the high gas flow (optionally humidified) may be delivered to the patient 16 via the delivery conduit 14 and patient interface 15 or an “interface” such as a cannula, mask, nasal interface, oral device, or a combination thereof. In some embodiments, the high gas flow (optionally humidified) may be delivered to the patient 16 for surgical use, for example, surgical inhalation. In these embodiments, the “interface” can be a surgical cannula, trocar, or other suitable interface. The patient interface may seal, substantially seal, partially seal, not seal, substantially not seal, or not seal in the patient’s airway. As used herein, a nasal interface is a device such as a cannula, nasal mask, nasal pillow, or other type of nasal device, or a combination thereof configured to direct the gas flow to one or both of the patient’s nostrils.

[0160] The nasal interface can also be used in combination with a face mask 300 or oral device (such as a tube inserted into the mouth) as shown in Figure 2b, and / or a mask or oral device (such as a tube inserted into the mouth) that can be detached from and / or attached to the nasal interface.

[0161] A nasal cannula is a nasal interface that may include one or more prongs and is configured to be inserted into a patient's nasal cavity. A mask refers to an interface that covers a patient's nasal cavity and / or mouth, and may also include a device in which the portion of the mask that covers the patient's mouth can be removed. A mask also refers to a nasal interface that includes a nasal pillow that creates a substantial seal at the patient's nostrils.

[0162] Figures 2a and 2b show an example of a patient 16 wearing a patient interface 200 with a foldable breathing conduit section, such as the nasal cannula 15 of the breathing system 10 in Figure 1. The patient depicted is an adult; however, the patient may be an infant, child, or adolescent.

[0163] The patient interface 200 includes a first gas (delivery) conduit 202. The first gas conduit 202 is adapted to receive gas from the respiratory system 10 in Figure 1 (for example, via the conduit 14 shown in Figure 1) and direct the gas to the patient 16. The first gas conduit 202 may include reinforcing elements 203 adapted to reinforce and / or add rigidity to the first gas conduit in order to prevent deformation or folding of the first gas conduit 202 resulting from the application of force to the first gas conduit 202. The reinforcing elements 203 may include, but are not limited to, a number of structures including plastic or metal that reinforce beads within or above the wall of the lumen 202 of the first conduit.

[0164] The patient interface 200 may include a gas delivery side arm that is in fluid communication with a first gas conduit 202. The first gas conduit 202 is in pneumatic communication with a flow manifold 206 provided at the end of the gas delivery side arm. The flow manifold 206 receives gas from the first gas conduit 202 and passes it through one or more nasal delivery elements 208 (e.g., nasal prongs) extending from the manifold. One or more nasal delivery elements 208 extend outward from the flow manifold 206. One or more nasal delivery elements 208 are adapted to be positioned without sealing within one or more nostrils of patient 16. The first patient interface 200 is therefore an unsealed patient interface. As shown, the patient interface 200 includes two nasal prongs 208 adapted to be positioned one at a time in each of the patient's nostrils. Each nasal prong 208 may be shaped or angled so that it extends inward toward the patient's nasal septum. Alternatively, the first patient interface 200 may be a sealed nasal interface.

[0165] In the embodiments shown in Figures 2a and 2b, the flow manifold 206 receives the flow from one side of the flow manifold 206 (for example, with respect to a virtual vertical plane bisecting the patient P's face) and provides a passage for the flow through the manifold to each of the nasal prongs 208. In some embodiments, the conduit may extend from a single side of the manifold, for example from the left or right side of the manifold. In some situations, providing the conduit on the left side of the patient interface may be preferable for the clinician to access, for example, for intubation. Alternatively, a conduit extending from the right side may be preferable in procedures such as endoscopy, for example, when the patient is typically lying on their left side. In other configurations, the patient interface 200 may include more (e.g., three or four) or fewer (e.g., one) nasal delivery elements 208. In other configurations, each of the nasal delivery elements 208 may have different characteristics. For example, one of a pair of nasal delivery elements 208 may be relatively long, and the other nasal delivery element 208 may be relatively short.

[0166] In some configurations, the flow manifold 206 may be configured to receive flow from two sides of the flow manifold 206 (for example, from the “left” and “right” sides of the flow manifold 206, instead of just the patient’s right side of the flow manifold 206, as seen in Figures 2a and 2b). In some such configurations, multiple gas conduits may be used to provide pneumatic communication between the flow manifold 206 and the respiratory system 10. For example, the patient interface may include a double conduit, where a first gas conduit 202 extends from a first side of the interface (the patient’s right side in the shown example), and a second gas conduit (not shown) extends from a second opposite side of the interface. In some configurations, the flow manifold 206 may be configured to receive flow from a non-side of the flow manifold 206 (for example, from the “bottom” or “top” of the flow manifold 206, or both), or from the front of the flow manifold 206 on the patient’s side 16.

[0167] The patient interface 200 may further include attachment and / or support parts, such as cheek support parts 210, for attaching and / or supporting the gas conduit 202 or a plurality of conduits over the patient's face. Alternatively or additionally, the patient interface 200 may be held in place via one or more head straps or headgear (not shown).

[0168] The first gas conduit 202 of the patient interface 200 includes a first portion 204 configured to transition from a first configuration in which a first level of gas can pass through the first portion 204 to a second configuration in which a second level of gas can pass through the first portion 204.

[0169] Figure 2b shows patient 16 wearing a patient interface 200, which includes two nasal prongs 208 simultaneously beneath the face mask assembly 300 (second patient interface). In this configuration, the face mask assembly 300 is placed on top of the patient interface 200 worn by patient 16. Figure 2b schematically shows the face mask assembly 300 as a transparent structure to show the patient interface 200 beneath the face mask assembly 300. The first patient interface 200 may be used with a first respiratory support system 10, and the face mask assembly (second patient interface) 300 may be used with a second respiratory support system (not shown). In some configurations, the first and second respiratory support systems are the same system and / or the first and second respiratory support systems include a common flow source, although the modes of respiratory support provided by the first and second respiratory support systems are different. In other configurations, the first and second respiratory support systems are separate systems.

[0170] The configuration shown in Figure 2b may be advantageous when providing a patient with the selective delivery of different modes of treatment or support using different patient interfaces, and / or when stopping or pausing the delivery of treatment from the interface, and / or when it is possible to withdraw the gas provided by the interface. For example, the configuration may find specific applications in emergency resuscitation, around intubation of patients receiving high-flow treatment, ENT surgery, assisting in the adjustment of patients' preoperative conditions before anesthetic administration, and during post-extubation and recovery.

[0171] The face mask assembly 300 may be used as a second respiratory support system or in conjunction with a second respiratory support system, and / or to deliver one or more substances other than those delivered by the cannula 200. For example, to deliver an anesthetic and / or oxygen to the patient, or to deliver the same substance as the first patient interface 200, but at a different flow and / or pressure level. Alternatively, the face mask assembly 300 may be used to reduce or stop the delivery of treatment from the first respiratory support system through the first patient interface 200. In some embodiments, the face mask assembly 300 may be adapted to measure respiratory gases, such as carbon dioxide exhaled by the patient, the measurement of which may be affected by the flow from the patient interface 200 of the first respiratory support system.

[0172] The configuration shown in Figure 2b allows for the exchange of two different respiratory support systems. Additionally, this configuration may allow the first patient interface 200 to remain on the patient throughout the medical procedure and / or during the recovery process (regardless of whether the patient continues to receive treatment through the patient interface 200 throughout the procedure) without interfering with other clinical care.

[0173] In the shown embodiment, the face mask assembly 300 includes a full-face mask 302 configured to cover both the patient's nose and mouth. In other configurations, the face mask assembly 300 may include a nose mask placed on the patient interface 200 to cover only the patient's nasal area.

[0174] As shown, the face mask 302 includes a sealing area 304 adapted to seal against the patient's face. The face mask assembly 300 is connected, for example, via a filter element 350, to a second gas source that supplies one or more other gases to the patient through the face mask. In some configurations, the second gas source is different from the source supplying gas to the patient interface 200 (e.g., an auxiliary gas source or flow generator). In some configurations, the second gas source is the same as the source supplying gas to the patient interface 200.

[0175] In some embodiments, the face mask assembly 300 is connected to a second flow source, which is a separate gas source or separate respiratory support system configured to provide a respiratory supply unit isolated from all flow sources, or a respiratory support system that delivers a gas stream to the first patient interface 200, or which includes a separate gas source or separate respiratory support system. For example, the separate respiratory support system may be a ventilator or CPAP or high-flow therapy device or a manual resuscitation device (e.g., a portable face mask with a bag). Alternatively or additionally, the face mask assembly 300 may be connected to a device for measuring the characteristics of the respiratory gas.

[0176] Alternatively, a separate respiratory support system may be an anesthetic device, or may include an anesthetic device, and / or a second gas source may include an anesthetic gas, or air, or oxygen, or a combination of gases, for delivery via the face mask 302.

[0177] The configuration shown in Figure 2b allows for gas delivery from multiple sources via at least two different respiratory support modes, and furthermore, allows a physician, clinician, or medical professional to quickly and easily change the type of respiratory support mode.

[0178] In one specific application, a patient undergoing anesthesia may undergo pre-oxygenation by delivering a high flow of oxygen or humidified gas, or a mixture of both, for example, via a nasal cannula, while the patient is still breathing spontaneously and before the administration of the anesthetic. Pre-oxygenation increases the patient's oxygen stores before the anesthetic procedure. The term “anesthetic procedure” may refer, without limitation, to general anesthesia, procedural sedation, and regional / local anesthesia. In some situations, the anesthesiologist managing the patient’s anesthetic procedure may want to switch between delivery of a gas flow from one patient interface (e.g., nasal cannula 200) and delivery of a gas flow from another patient interface, such as via a face mask 300.

[0179] Anesthesiologists also use bag-equipped masks to administer oxygen to patients, and in some cases, it may be more beneficial to use a bag-mask when the patient's vital signs begin to decline, for example, to deliver more pressure to support the patient's airway, or to have greater manual control over fluctuations in the delivered pressure. In some situations, medical professionals may want to switch between different respiratory systems or support modes. In a first mode, respiratory support may be provided by a first respiratory support system (e.g., via the patient interface 200), and in a second mode, respiratory support may be provided by a second respiratory support system (e.g., via the face mask assembly 300), with reduced or stopped support from the first system. For example, a high flow from interface 200 may modify the expected behavior of the anesthetic circuit provided by the face mask 300 (the face mask 300 is typically a sealed circuit) and may dilute the anesthetic delivered by the face mask assembly 300, so it may be desirable to stop the high flow from the first patient interface 200 when delivering the anesthetic through the face mask assembly 300. Thus, it may be advantageous to stop or substantially reduce the additional flow from the first respiratory system.

[0180] In some configurations, switching between two respiratory support modes or subsystems may be facilitated by the structure of the first gas conduit 202, which has a first section 204 configured to transition between a first configuration in which a first level of gas can pass through the first section 204 and a second configuration in which a second level of gas can pass through the first section 204.

[0181] In some configurations, the first section 204 is configured to be more foldable than other sections of the conduit 202 to alter the gas flow through the first section 204 (reducing the gas flow through the conduit to the patient), or to be better adapted by other means, and / or to allow the mask seal to seal the top of the conduit. In other configurations, the entire conduit 202 may be configured to be foldable, or to be better adapted by other means to alter the gas flow through the conduit 202. In some configurations, the exhaust port may be provided upstream of the foldable section to exhaust gas from the conduit upstream of the foldable section into the atmosphere.

[0182] In some embodiments, the first configuration is completely or substantially open, and the second configuration is completely or substantially closed. That is, the conduit 202 is configured to be more foldable and deformable than other parts of the conduit 202 when in the second configuration, or otherwise adapted to completely or substantially close the flow in the first part 204. There may be one or more intermediate states between the first and second configurations, in which case it will be understood that one or more of these intermediate states may have fewer openings (or more closures) than the completely or substantially open state (first configuration), but more openings (or less closures) than the completely or substantially closed condition (second configuration).

[0183] Figures 3a and 3b provide schematic diagrams of the first and second configurations, with Figure 3a showing the first configuration (substantially open) and Figure 3b showing the first portion 204 in the second configuration (substantially closed) by adding the sealing 304 of the face mask 302 over the first portion 204. In some embodiments, the first portion 204 of the first gas conduit 202 (i.e., more foldable or deformable portions) should be longer than the width of the portion of the sealing 304 of the face mask 302 that covers the first portion 204 of the first gas conduit 202. This ensures that the sealing of the face mask 302 does not cover the non-foldable portion of the first gas conduit 202. For example, the first portion 204 may extend from a distance of 35 mm or less from the center of the user's nose to at least 50 mm from the center of the user's nose. The first portion 204 may have a length of at least about 5 mm, a length of about 1 mm to about 30 mm, a length of about 5 mm to about 15 mm, or a length of about 10 mm. In some embodiments, the length of the first portion may be at least 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 20 mm, 25 mm, 30 mm, 35 mm, 40 mm, 45 mm, 50 mm or more.

[0184] The first portion 204 may advance between a first configuration and a second configuration based on the relative level of force applied to the wall of the first portion 204. For example, as shown in Figures 2 and 3, the force may be applied by the sealing 304 of the face mask 302. In this example, the first portion 204 is configured to be positioned below the sealing 304 of the face mask 302.

[0185] Alternatively, force may be applied to the first part 204 by other means, such as a clamp (not shown), or alternatively, a medical professional may compress the conduit by pressing the conduit wall with their thumb or other fingers.

[0186] In some embodiments, the sealing of the face mask acting on the first portion 204 of the gas conduit 202 causes the first portion 204 to form a seal or at least a partial seal between the nasal outlet of the first patient interface 200 and the flow source 12. Additionally, the sealing of the face mask forms a seal or at least a partial seal on the first portion 204 of the gas conduit 202.

[0187] Switching between respiratory support therapies can therefore be easily achieved by fitting the mask to the patient's face such that the mask seal folds (partially or completely) the first portion 204 of the gas conduit 202 supplying the first interface 200, in order to reduce or stop the therapy supplied by the first interface 200. This also provides a seal between the face mask 300 and the outer surface of the first portion 204 of the conduit 202, so that respiratory support or therapy can be provided by the face mask 300 when the respiratory support or therapy provided by the first patient interface 200 can be reduced or stopped. With the patient interface 200 equipped with a foldable conduit portion 204, a user, such as an anesthesiologist or nurse or clinician, can use the face mask assembly 300 on the patient interface 200 to select and control the delivery of gas from multiple respiratory support systems to provide different therapy or support modes. The first patient interface 200 may be constructed to function in a manner that prevents the delivery of high flow and other respiratory therapies or anesthetics through the patient interface 200 when the first portion 204 is in a second configuration. In some embodiments, the first part 204 can be returned to its first configuration by removing the face mask assembly 300 from the patient's face, so that the respiratory support or treatment supplied by the first patient interface 200 can be resumed or returned to the state it was in before the configuration change.

[0188] Embodiments of this disclosure improve the control of respiratory gas flow provided to a patient. In some embodiments, the respiratory support system includes a pressure relief valve or device. System 10 may include such a pressure relief or regulating device, or a pressure limiting device 100 (e.g., a pressure relief valve i.e., a PRV). This pressure limiting device 100 may be a valve having the features described in International Publication No. 2018 / 033863, which is incorporated herein by reference in its entirety. In some embodiments, the respiratory system does not include or excludes a pressure relief valve or device. In some embodiments, the respiratory system does not include or excludes a flow-compensated pressure relief valve or device, such as a flow-compensated pressure relief valve having the features described in International Publication No. 2018 / 033863.

[0189] Pressure relief and pressure control may specifically occur downstream from the flow source 12 and are then preferably used in respiratory support systems such as a high-flow system 10, including an unsealed patient interface (such as a nasal cannula in a first patient interface 200), to provide an upper limit on pressures that could impact patient airway pressure (also called patient pressure). Importantly, the pressure upper limit may be configured to provide a safety threshold, ensure patient pressure safety, and / or prevent damage to tubes, fluid connections, or other components in the system 10 due to overpressure. Similarly, pressure relief or limiting devices 100 may be used in sealed systems such as CPAP (continuous positive airway pressure), BiPAP (bilevel positive airway pressure), and / or bubble CPAP systems to regulate the pressure delivered to the patient.

[0190] A respiratory system 22 for providing a respiratory gas flow to the patient is shown in Figures 4–8 in different embodiments of this disclosure.

[0191] Figure 4 shows a respiratory system 22 including a controller 24 and a flow source 12 which may include a flow regulator configured to be controlled by the controller 24 to regulate the respiratory gas flow to the patient 16. The controller is configured to receive flow inputs and pressures of the respiratory gas flow within the system, and to provide the respiratory gas flow to the patient at a target flow rate. It may also be configured to control the flow regulator to regulate the respiratory gas flow to a target pressure when the pressure of the respiratory gas flow within the system meets or exceeds a pressure threshold corresponding to the target flow rate. In some embodiments, the target pressure includes a pressure threshold corresponding to a target flow rate, or a pressure threshold corresponding to a flow rate less than the target flow rate. The pressure threshold corresponding to the target flow rate may be determined by the controller using a function stored in a memory component of the controller, or in a memory component operably coupled to the controller, as described, for example, in any of the foregoing. The target pressure or pressure threshold may be defined as an absolute pressure value or a gauge pressure value.

[0192] As stated above, the flow source 12 may include a flow generator, such as a blower, configured to be controlled by the controller 24, in order to generate a breathing gas flow. Alternatively or additionally, the flow source 12 may include a proportional valve configured to be controlled by the controller 24, in order to regulate the breathing gas flow from the gas source, or the flow source 12 may include a combination of a flow generator and a proportional valve.

[0193] Typically, system 22 further includes one or more sensors 28 configured to determine the characteristics of the respiratory system, such as the characteristics of the respiratory gas flow within the respiratory system and / or provided to the patient. System 10 can operate system 22 in a manner that monitors the characteristics of the system and / or provides appropriate respiratory assistance using ultrasonic transducers, flow sensors such as thermistor flow sensors, pressure sensors, temperature sensors, humidity sensors, or other sensors communicating with controller 24. Such characteristics may include gas concentration, flow rate, pressure, temperature, humidity, or other characteristics. Sensors 28, such as pressure, temperature, humidity, and / or flow sensors, can be placed in various locations within system 22, such as in the main housing containing components of system 22, patient conduit 12, and / or patient interface 200. Controller 24 can receive signals from sensors 28 that provide controller inputs used to determine the control of one or more components of the respiratory assistance system 22 in a manner that provides appropriate respiratory assistance. For example, the controller 24 may use signals from one or more sensors 28 to determine an appropriate target temperature, humidity, flow rate, and / or oxygen concentration of the gas flow, or an appropriate pressure that may be generated downstream from the flow source 12 in the system. Providing appropriate respiratory support may include meeting the patient's inspiratory receptacle. Appropriate respiratory support flow rates, such as high flow rates and / or flow rates that meet or exceed the patient's inspiratory receptacle, are described elsewhere in this specification.

[0194] In some embodiments, the sensor includes a flow sensor (e.g., ultrasonic, temperature-based, or other suitable flow sensor) configured to sense the flow rate of the gas flow supplied to the patient 16, and the sensed flow rate is used by the controller 24 to determine a safe upper pressure limit for the operation of the system 22 at the sensed flow rate. The controller 24 can then control the operation of one or more components of the system 22 (e.g., actuators), such as the flow source 12, to achieve a target flow rate stored in memory operably communicating with the controller or any other component of the system, for example, by modifying the blower speed. The target flow rate may be a flow rate setpoint entered by the user of the system through the I / O interface 20, or the target flow rate may be determined or pre-programmed in the controller or associated memory / component. By modifying the flow rate, the blower speed may be increased or decreased (and / or the size of the hole in the proportional valve may be increased or decreased) to achieve the respective increases or decreases in flow rate.

[0195] In some embodiments, when the system starts operating from an "off" or dormant state, the controller is configured to monitor the flow rate of the breathing gas flow within the system and to control the flow regulator to adjust the breathing gas flow to achieve a target flow rate. Ideally, the target flow rate changes over time to increase from the current value to a flow rate setpoint. The controller may also be configured to monitor the flow rate of the breathing gas flow to a new target flow rate in other environments, such as when the user changes the flow rate setpoint in which the system operates.

[0196] The controller 24 may receive input from one or more pressure sensors. The controller can measure or estimate the pressure delivered to the patient from the pressure sensor input. The pressure sensors are placed downstream of the flow source 12. For example, the pressure sensors may be placed at or near the patient interface 200. The pressure sensors may also be placed immediately behind the flow source. The pressure delivered to the patient's airway (patient pressure) can be determined by the controller, which calculates the difference between the ambient pressure and the absolute pressure downstream of the flow source. Patient pressure can be estimated by measuring the pressure in the main device housing downstream of the flow generator and calculating the pressure drop along the delivery conduit 202. The pressure sensors may also be placed elsewhere in the pneumatic circuit downstream of the gas flow of the flow source 12. The pressure sensors may include one or more gauge pressure sensors, or alternatively, one or more absolute pressure sensors. Gauge pressure sensors can directly measure the difference between the absolute pressure downstream of the flow generator and the ambient pressure. In a system with two absolute pressure sensors, one sensor can be placed downstream of the flow source to measure the absolute pressure downstream of the flow source, and the other sensor can be placed in a different location to measure the ambient pressure. The controller can determine the pressure delivered to the patient by determining the difference between the pressure measurements taken by the two absolute pressure sensors.

[0197] In various embodiments, the controller 24 is configured to receive one or more signals directly from one or more pressure sensors or through manual inputs provided to a user interface operably communicating with the controller, or to receive an output value indicating the system pressure in the pneumatic circuit downstream of the flow source 12 through which the respiratory gas flow in the respiratory system 22 is delivered to the patient 16. The controller 24 may convert the received signals into pressure values, and the controller may compare these values ​​to pressure thresholds for corresponding flow rates, such as those stored in the controller or a memory device or module operably communicating with the controller. Since the controller needs to know the flow rate of the gas in the pneumatic circuit in order to determine whether the system pressure meets or exceeds the pressure threshold for corresponding flow rates, the controller may also receive one or more signals directly from one or more flow sensors, or the controller may obtain flow rate values ​​through manual inputs provided to a user interface operably communicating with the controller, or the controller may derive flow rate values ​​by, for example, knowing the resistance to flow in the pneumatic components of the system 22 and by, for example, calculating the flow from the blower speed in the flow source 12.

[0198] The controller 24 may determine the system pressure continuously or intermittently, and there may be related benefits to both. For example, continuous determination of the system pressure provides the best response in terms of how quickly the controller can detect changes in the system pressure that meet or exceed (or fall below) a pressure threshold for a corresponding flow rate, and how quickly the controller can respond by controlling the flow source 12 to reduce the blower speed (and possibly reduce the breathing gas flow) in response to a pressure that meets or exceeds the pressure threshold for a corresponding flow rate, and to control the flow source 12 to adjust the breathing gas flow in response to a pressure that does not meet or exceed the pressure threshold for a corresponding flow rate. Alternatively, the controller 24 may intermittently sense or receive a pressure input that provides more economical operation, but the system may change slightly before the controller receives the pressure input, so the system may experience a response delay, and thus the adjustment and / or control of the flow source 12 may become unresponsive.

[0199] The pressure threshold corresponding to the flow rate may be stored in a memory component of the controller 24, or in a memory device or component outside the controller 24 that is operably in communication with the controller 24. The relationship between the pressure threshold and the corresponding flow rate may be stored as one or more functions, curves, lookup tables, mathematical models, or algorithms used by the controller to determine a specific pressure threshold for the corresponding flow rate. In some embodiments, the relationship between the pressure threshold and the corresponding flow rate, as used by the controller 24, can be represented graphically, examples of which are shown in Figures 9-14.

[0200] Figure 5 shows another embodiment of the respiratory system 22, which includes a controller 24 and a flow source 12 configured to be controlled by the controller 24 to regulate the respiratory gas flow to the patient 16 via a patient interface 200 configured to fluidly communicate with the flow source 12 and deliver the respiratory gas flow to the patient 16. The respiratory system 22 also includes one or more sensors 28 configured to determine the system pressure downstream of the flow source 12 and / or the flow rate of the respiratory gas flow in the respiratory support system that provides gas to the patient.

[0201] The patient interface 200 receives the respiratory gas flow from the flow source 12 via the conduit 202. The conduit 202 includes a first portion 204 configured to operate in at least a first configuration and a second configuration.

[0202] In the embodiment shown in Figure 5, the controller 24 may be configured to receive input from the sensor 28 indicating the pressure and / or flow rate of the breathing gas flow in the breathing support system 22, compare the sensed pressure with a pressure threshold, and in response to a pressure that meets or exceeds the pressure threshold, control the flow source 12 to provide a first adjustment of the breathing gas flow, and in response to a pressure that does not meet or exceed the pressure threshold, control the flow regulator 26 to provide a second adjustment of the breathing gas flow.

[0203] As described above, in some embodiments, the second adjustment differs from the first adjustment, which includes maintaining the system pressure downstream of the flow source at a target pressure, for example, a pressure threshold, and / or reducing the system pressure downstream of the flow source to a target pressure lower than the pressure threshold. The second adjustment may also include increasing or decreasing the breathing gas flow rate to a target flow rate in response to a system pressure downstream of the flow source that does not meet or exceed the pressure threshold.

[0204] The corresponding flow rate may be the flow rate of the respiratory gas flow provided by the flow source in or along part of the pneumatic circuit of the respiratory system 22 that provides gas flow to the patient interface 200 and / or in the patient's airway. As previously described, the corresponding flow rate may be the flow rate obtained by one or more flow sensors that directly provide input to the controller 24, the corresponding flow rate may be entered by a user operating a user interface that operably communicates with the controller, or, if the resistance of the pneumatic components of the system 22 is known, the corresponding flow rate may be inferred from other factors, such as the blower speed of the flow source.

[0205] Figure 6 shows a breathing system 22 according to another embodiment of the present disclosure. In this embodiment, the system 22 includes a controller 24 and a flow source in the form of a flow regulator or blower 27, configured to be controlled by the controller 24 to generate a breathing gas flow to the patient 16 via a delivery conduit 202. Typically, the controller 24 and blower 27 are contained within a common housing 33, although the controller may be located away from or within a separate housing from the blower 27 and other components of the respiratory support system. In some embodiments, the housing 33 also includes a humidifier (shown in the embodiment of Figure 1) which includes a humidification chamber through which the gas flow from the blower passes in order to humidify the gas delivered to the patient by increasing its moisture content and, optionally, its temperature. The humidified gas is then delivered to the patient interface 200 by a delivery conduit 202 (the delivery conduit 202 may include the humidifier and a portion of the delivery circuit 38 downstream of the patient breathing circuit 40). The respiratory support system 22 further includes a patient interface 200 configured to receive a gas flow through a delivery conduit 202 for delivery to a patient 16. The patient interface 200 may include one or more nasal elements, or a face mask assembly configured to deliver gas to each or both of the patient's nostrils and / or mouth. The patient interface 200 receives the respiratory gas flow from the blower 27 via the conduit 202. The conduit 202 includes a foldable first portion 204 configured to operate in at least a first configuration and a second configuration as described in any of the foregoing.

[0206] The foldable section 204 is configured to operate in a first configuration (e.g., unfolded or fully or substantially open) and to be foldable from the first configuration to a second configuration (e.g., folded or fully or substantially closed). There may be one or more intermediate states between the first and second configurations, in which case one or more intermediate states may be less open (or more closed) than the fully or substantially open state (first configuration), but more open (or less closed) than the fully or substantially closed state (second configuration). As stated, the controller 24 modifies the operation of the flow source when the foldable section 204 is in the second configuration compared to when the foldable section 204 is in the first configuration. In some embodiments, this is achieved by adjusting (e.g., reducing) the speed of the blower 27, which then adjusts (e.g., reduces) the breathing gas flow to a reduced flow rate in the system in response to a sensed system pressure that meets or exceeds a pressure threshold for the corresponding flow rate of the breathing gas flow supplied to the patient. In some embodiments, the controller 24 changes the state (e.g., degree of opening) of one or more proportional valves, which then adjusts (e.g., reduces) the breathing gas flow to a reduced flow rate in the system in response to a sensed system pressure that meets or exceeds a pressure threshold for the corresponding flow rate of the breathing gas flow supplied to the patient. In some embodiments, the controller 24 changes the operation and / or state of both the blower and the proportional valves.

[0207] The breathing system 22 shown in Figure 6 includes two types of sensors: a flow sensor 32 configured to sense the flow rate of the breathing gas flow within the breathing system 22, and a pressure sensor 29 configured to sense the pressure within the breathing system 22 downstream of the blower 27, including downstream of the outlet of the housing 33.

[0208] The flow sensor 32 and pressure sensor 29 are located downstream of the flow regulator, i.e., the blower 27. The flow sensor 32 and pressure sensor 29 are configured to sense the flow rate and pressure, respectively, downstream of the flow regulator and within the delivery conduit 202. In this embodiment, the controller 24 receives data from the pressure sensor 29 and flow sensor 32 indicating the pressure and flow rate of the breathing gas flow within the delivery conduit 202, and is configured to compare the sensed pressure with a pressure threshold for the corresponding flow rate, as stored by the controller 24 and a memory component operably connected to the controller.

[0209] In some embodiments, one or more pressure sensors may be placed downstream of the blower 27 near the system outlet to which the delivery conduit 202 is connected, in order to determine the system outlet pressure. The outlet pressure can be used to estimate patient pressure, as discussed below. In some embodiments, a second pressure sensor 29 may be provided to offer redundancy in order to provide a backup pressure input in case the primary pressure sensor fails. In some embodiments, the controller 24 may receive input from an absolute (ambient) pressure sensor 29a to detect the operating pressure, which may change due to, for example, altitude, and may affect the performance of its components such as the flow source and blower. However, gauge sensors may have a superior solution and can be preferred pressure sensors for many applications.

[0210] In some embodiments, in addition to a pressure sensor 29 configured to sense the pressure inside the delivery conduit, there is a pressure sensor configured to sense the pressure delivered to the patient. The controller 24 can then determine the flow rate of the gas to the patient from the pressure difference sensed between these two sensors.

[0211] The patient interface 200 has the features described above. Thus, in some embodiments, the patient interface 200 is a nasal cannula, such as an unsealed nasal cannula, that receives the respiratory gas flow from a conduit 202 having a foldable portion 204 that can transition between a first configuration and a second configuration (Figure 3b).

[0212] The patient interface 200 is hereafter referred to as the nasal cannula 200 to provide a more specific description of the components involved in the delivery of respiratory gases according to embodiments of the present disclosure. In some embodiments, the foldable portion 204 folds into a second configuration when the face mask assembly 300 is attached to the patient 16 over the nasal cannula 200. The face mask assembly 300 may be abbreviated as the mask 300. The delivery conduit 202 is configured to deliver a respiratory gas stream to the patient 16 through the foldable portion 204 when it is in the second configuration at a reduced flow rate compared to when the foldable portion 204 is in the first configuration. For example, the reduced flow rate may be less than about 15 L / min, about 0 to 15 L / min, or about 5 to 15 L / min, or 0 L / min. The flow rate when the foldable portion 204 is in the first configuration is a high flow rate, which may be greater than about 20 L / min, about 20 to 90 L / min, or about 40 to 70 L / min.

[0213] The delivery conduit 202 may be considered to provide a delivery circuit 38 and a patient breathing circuit 40 arranged between the delivery circuit 38 and the patient interface 200. The patient breathing circuit 40 is connected to the delivery circuit 38 via an outlet connector 34. In the embodiment of Figure 6, the controller 24, blower 27, pressure sensor 29, flow sensor 32, and delivery circuit 38 are housed within a housing 33. The outlet connector 34 may be mounted on or pass through the housing 33 to provide a physical connection between the delivery circuit 38 inside the housing and the patient breathing circuit 40 outside the housing. It will be recognized that the patient interface 200 may be connected to the patient breathing circuit 40 via a connector not shown in this figure. It will also be recognized that the system 22 may further include one or more proportional valves of the above types, which may also be housed within the housing 33. As recognized, restrictions are introduced in the flow within the breathing system by intentionally folding a portion of the patient interface 200, or from there a foldable portion 204 from which the patient interface receives the gas flow. When this occurs, in the example of the breathing system 22 in use, the controller 24 may detect the flow restriction by determining that there is an increase in the system pressure and may control the flow regulator 26 to adjust the system pressure (for example, by changing the speed of the blower 27 and / or the size of the flow path through the proportional valve 25, see Figure 7). When the foldable section 204 returns to the first configuration, the controller 24 may detect the change by determining that there is a decrease in the system pressure and may control the blower 27 and / or the proportional valve 25 to increase the breathing gas flow, which may then increase the system pressure, while the pressure threshold corresponding to the flow rate of gas remains low.

[0214] The respiratory support system may be susceptible to accidental limitations on flow, such as those caused by a tear, bend, or collapse of the delivery conduit 202. Another way in which flow may be limited in such a system is when the anatomical and / or airway features of a particular patient have higher resistance. These limitations may generate substantial back pressure in the flow path upstream of the limitation. In some embodiments of the respiratory system 22, when these limitations occur, the respiratory system may, by action of the controller 24, determine that the pressure in the delivery conduit 202 exceeds a pressure threshold for the corresponding flow rate, and the controller 24 may control the blower 27 to reduce the respiratory gas flow, thereby reducing the pressure in the system 22. Once the accidental limitation is removed, the controller 24 may further control the blower 27 to increase the respiratory gas flow, thereby increasing the pressure in the system 22. Alternatively or additionally, the controller 24 may control the proportional valve 25 to open further, thereby increasing the respiratory gas flow and increasing the pressure in the system 22.

[0215] Figures 7 and 8 are schematic diagrams of components of a respiratory system 22 that provides a respiratory gas flow to a patient according to embodiments of the present disclosure. More specifically, Figures 7 and 8 show components of the respiratory system 22 that deliver respiratory gas from an oxygen (O2) source 42 (e.g., a wall source or O2 tank) and an ambient air source 44 to a nasal cannula 200 and to the patient.

[0216] The breathing system 22 shown in Figures 7 and 8 includes a pressure sensor 46 (e.g., an O2 pressure sensor) configured to sense the pressure in the O2 delivery circuit 47 of the breathing system 22. The pressure sensor may be used to determine that the O2 delivery circuit 47 is connected to an O2 source 42. Control of the O2 flow may be provided by a proportional valve 25 controllable by a controller 24 (not shown). The O2 delivery circuit 47 further includes a flow sensor 48 (e.g., an O2 flow sensor) configured to sense the flow rate of the O2 flow from the O2 supply after the O2 flow has been regulated by the proportional valve 25.

[0217] The breathing system 22 shown in Figures 7 and 8 further includes a flow sensor 50 (e.g., an airflow sensor) configured to sense the airflow rate from an ambient air source 44 within the air delivery circuit 49 of the breathing system 22. In some embodiments, a patient breathing circuit 40 is connected to an O2 delivery circuit 47 and an air delivery circuit 49, and the patient breathing circuit and / or patient interface further includes a patient pressure sensor and a patient flow sensor. Airflow control is provided by a blower 27 of the above type, controllable by a controller 24. In Figure 7, the blower 27 is provided within the air delivery circuit 49, whereas in Figure 8, the blower 27 is provided within the patient breathing circuit 40. In both embodiments, the respiratory system 22 provides closed-loop control of pressure and / or flow by a controller 24 that controls the operation of the blower 27 to limit or alter the amount of O2 entering the patient breathing circuit 40, for example by changing the angular velocity / motor speed of the blower 27 and / or the current or voltage supplied to the blower 27, and / or by controlling the opening degree of the proportional valve 25, for example by changing the current supplied to the valve.

[0218] In some embodiments, a blower 27 regulates the breathing gas flow, and a proportional valve 25 controls the oxygen concentration in the breathing gas. Both are controlled by a controller 24. Thus, when the user operates the I / O interface 20 to increase the flow from a given flow rate setpoint, the control to the blower 27 may increase its speed, potentially diluting the O2 concentration. The controller 24 compensates for this by operating the proportional valve 25 to open further (for example, by increasing the current to the proportional valve) so that more O2 can flow to the patient to meet the O2 concentration setpoint required by the user. If the user changes the O2 concentration setpoint to a higher concentration, the controller 24 controls the proportional valve 25 so that more oxygen can flow into the breathing gas delivered to the patient.

[0219] In the embodiments shown in Figures 7 and 8, the patient breathing circuit 40 is in fluid communication with the O2 delivery circuit 47 and the air delivery circuit 49. As stated, in Figure 8, the patient breathing circuit 40 includes a blower 27 controlled by a controller 24 to deliver a gas flow, typically containing air and O2, to the nasal cannula 200. In both embodiments, the patient delivery circuit 40 may also include a patient pressure sensor 54 and / or a patient flow sensor 52 configured to monitor the pressure and / or flow rate of the combination of O2 and air breathing gases delivered to the patient via the nasal cannula 200.

[0220] In relation to this, in the embodiments of Figures 7 and 8, there may be an open passage within the air delivery circuit 49 (for example, between the inlet of the blower 27 receiving ambient air from the source 44 in Figure 7 and a location in the passage downstream of the blower 27), thereby enabling bidirectional flow. The open passage includes a passage without a one-way valve or any component that allows only unidirectional flow of gas. This may be beneficial in scenarios where there is a blockage at the outlet of the system connected to a patient breathing circuit 40, for example, to avoid high system pressures that could allow excess gas accumulated in the system to safely "leak" out of the air delivery circuit 49 through the blower 27 and damage certain components. Many prior art respiratory support systems rely on one-way valves to deliver flow to the patient, which can prevent backflow in the described environment and cause component damage and / or system failure.

[0221] In the embodiment shown in Figure 7, O2 is mixed with ambient air downstream of the blower 27. This may be beneficial for embodiments that humidify the gas provided to a patient, as the gas mixed downstream of the blower 27 may be colder than the gas mixed upstream of the blower (as in Figure 8), and the operation of the blower should heat the gas passing through it. This may improve the accuracy of humidification when the humidifier control is based on the temperature of the gas entering the humidification chamber. In some embodiments, one or more pressure sensors may monitor ambient air pressure to accommodate different operating conditions, such as changes in altitude.

[0222] Figures 9–14 are graphs showing curves representing the relationship between flow and pressure, which are used in embodiments of this disclosure in controlling components of a respiratory system to deliver a respiratory gas flow to a patient. As stated, the controller 24 is configured to control the flow regulator 26 to increase, maintain, or decrease the respiratory gas flow. For example, the controller 24 is configured to control the blower 27 to increase, maintain, or decrease the angular velocity (i.e., speed) of the blower 27 by providing an electrical control signal or by directly controlling the voltage or current supply to the blower, thereby increasing, maintaining, or decreasing the respiratory gas flow. The controller 24 determines appropriate control to the flow regulator 26 in response to pressures that, at a corresponding flow rate, do not meet or exceed, or meet or exceed, one or more pressure thresholds, such as the flow rates shown in the curves of Figures 9–14 (which may be referred to hereafter as pressure limit curves C). In some embodiments, the controller 24 determines appropriate control to the flow regulator 26 in response to system pressures that, at a corresponding flow rate, are below, meet, or exceed pressure thresholds. One or more pressure thresholds may be predetermined pressure thresholds. As stated above, the pressure thresholds and corresponding flow rates may be stored in a memory component of the controller 24 or a memory component operably connected to the controller 24.

[0223] In some embodiments, the controller 24 is configured to control the flow regulator to adjust the respiratory gas flow to a target pressure when the respiratory gas flow rate is less than the target flow rate. This avoids a situation where the controller attempts to increase the flow to approach the target flow rate, where the pressure threshold may exceed the current flow rate due to the system pressure. Alternatively / additionally, the controller may be configured to control the flow regulator to adjust the respiratory gas flow to a target flow rate when the respiratory gas flow rate exceeds the target flow rate, i.e., to reduce the flow to a target flow rate when the respiratory gas flow rate is exceeded, thereby avoiding the risk of harm to the patient. In some embodiments, the controller is configured to control the flow regulator to a target pressure when the respiratory gas flow pressure exceeds a pressure threshold corresponding to the target flow rate or a pressure threshold corresponding to a flow rate less than the target flow rate.

[0224] The pressure limit curve C has been determined by considering the known resistance of the system components to flow and the known flow rate range delivered to the patient. The pressure limit curve C may be stored in memory accessible to the controller 24, as previously discussed, which may include a computer-readable medium (e.g., a disk, hard drive, USB, optical drive, or other data storage device) containing program instructions for the controller 24 to perform the necessary control, as described herein.

[0225] In some embodiments, the pressure limit curve C provides a safety threshold corresponding to a safe patient pressure for the corresponding flow rate of gas to the patient when the flow to the nasal cannula 200 is restricted, such as when the foldable section 204 is in a folded configuration and a mask is attached. This pressure threshold is applied to reduce the risk of overpressure to the patient, which could cause baroscopic obstruction of the patient's airway. Thus, in some embodiments, the controller 24 automatically reduces the flow delivered to the patient through the nasal cannula 200 when there is an obstruction in the delivery conduit 202, such as an accidental blockage, or when the mask 300 is used to ventilate the patient and is pressed over the nasal cannula, for example, in a second configuration, to fully fold the foldable section 204. When this occurs, the controller 24 may implement pressure control of the system 22 by controlling the operation of other components, such as the blower 27 and / or proportional valve 25, to reach the target pressure induced by the pressure limit curve C. Furthermore, the controller 24 may automatically increase the respiratory gas flow when the mask is removed, and the foldable section 204 can be returned to the first configuration.

[0226] In some embodiments, the controller 24 may control only the blower 27 (e.g., angular velocity), the blower 27 and one or more proportional valves 25, or one or more proportional valves 25 only, to control the flow rate and / or pressure of the breathing gas flow. In embodiments where the proportional valves and blower are in parallel flow paths (e.g., Figure 7), check valves (not shown) may be provided in the air delivery circuit 49 before and after the blower to prevent backflow of the flow exiting the air delivery circuit 49 via the ambient air source 44, so that the flow and / or pressure of the breathing gas flow is controlled by the proportional valves. In some embodiments, pressure relief valves (not shown) may be provided in a system where pressure relief valves (e.g., valves that vent to the atmosphere) are operable by the controller 24 to control the flow and / or pressure of the breathing gas flow.

[0227] In some embodiments, the controller 24 may be programmed to apply an additional safety threshold, which is a pressure limit, to induce the controller 24 to substantially reduce or stop the operation of the flow regulator 26 when an arbitrary flow rate is reached, for example by turning off the blower 27 and / or stopping the proportional valve 25. This safety threshold may be a value greater than about 20 cmH2O, for example, about 30 cmH2O, about 40 cmH2O, about 50 cmH2O, or about 60 cmH2O, or about 70 cmH2O. In some embodiments, a safety threshold of about 60 cmH2O may be preferred, or a safety threshold calculated as a safety margin exceeding a predetermined pressure threshold for a corresponding flow rate may be used or calculated as a safety margin exceeding the normal expected range or system pressure range.

[0228] The resistance of system components to flow may be measured, calculated, and / or estimated, and may include the resistance of all components of the respiratory support system 22, optionally all components downstream of the outlet of the flow regulator 26. This necessitates that the consumables of the system 22 be carefully designed to have tight tolerances for resistance to flow, or conservative assumptions be used considering that manufacturing tolerances are not very tight. Knowing the resistance of the system 22 allows for the estimation of the pressure difference across the respiratory support system 22, thereby enabling the estimation of patient pressure from the system pressure. The respiratory system 22 can also determine the resistance characteristics in the delivery conduit 30 in real time from the pressure sensor 29 and the flow sensor 32, and compare this to known resistance to reduce the expected fluctuations in patient pressure. Knowing the current patient pressure ensures that the pressure can be controlled according to the pressure limit curve C, and as a result, the respiratory system 22 can better control the pressure / flow to the nasal cannula 31. In fact, the controller 24 operates the blower 27 and other components of the system 22 to avoid or minimize the operation of the system in the “overpressure” region corresponding to region 64, as will be discussed below.

[0229] During operation of the respiratory support system 22, the “normal” operating pressure values ​​for the corresponding flow rates are shown to be below the pressure limit curve C. More specifically, Figures 9 and 10 show the region 58 corresponding to the normal operating system pressure at the corresponding flow rates. Conveniently, the normal operating band provides a range of safe system pressure for the corresponding flow rates, and thus a “safe” band that provides a range for clinicians to safely operate components of the system, such as the delivery conduit 202, the foldable section 204, the manifold 206, the cannula 200, and other components necessary to deliver gas to the patient, without risking the delivery of overpressure to the patient’s airway and the risk of barotrauma or other injury.

[0230] Figure 10 shows a limiting operating region 60, where a pressure limit curve C may be defined for use in controlling the operation of the system for delivering breathing gas to a patient. In some embodiments, the controller calculates the shape of curve C using a function stored in the controller's memory component or a memory component operably coupled to the controller. Thus, upon receiving a “setpoint flow rate” entered by the user into the I / O interface 20, the controller uses the function to fit the curve within the limiting operating region 60 by defining the required upper flow rate of curve C and knowing the lower pressure limit (which may be defined by the manufacturer or user as the operating limit of the system). If the controller 24 determines that the system pressure is within the limiting operating region 60 and below curve C, the controller 24 may allow the flow to continue being delivered with the current control rather than immediately changing the control of the system components to reduce the flow. The limiting operating region 60 may occur when a temporary or instantaneous blockage or restriction of flow is present in the conduit, which may occur unintentionally or when a clinician interacts with the patient and / or places various components of the respiratory support system, including the patient interface, over the patient, and it may be desirable to prevent the controller 24 from immediately reducing the flow rate each time a bend is present in the conduit. This region is not present in the embodiments shown in Figures 9 and 11, as the pressure limit curve C is defined immediately next to the normal operating region and provides a pressure threshold that the controller may use. The control parameters conveyed by the embodiments in Figures 9 and 11 may be used in scenarios where it may be desirable to limit the degree of unintentional (or intentional) temporary blockage in the delivery conduit 202 before the flow rate is reduced.

[0231] The region below the pressure limit curve C and below the normal operating region is the mismatch region 62. Operation in this region may occur if a delivery conduit leaks or is disconnected from the system's flow-generating components, for example, if a delivery conduit is disconnected from the housing 33. Flow rates and pressures within this mismatch region 62 may also occur if mismatched or unintended system components are used. This region may also include pressures for corresponding flow rates that may be undesirable, and such pressures may not achieve sufficient or intended respiratory assistance. In some embodiments, if the controller 24 detects pressure within the mismatch / disconnection band 62, the controller 24 may sound a visible and / or audible alarm or warning to communicate to the system user that the system has detected a mismatch condition, for example, a condition that may mean a leak or disconnection within the system 22.

[0232] The region above the pressure limit curve C and above the limit operating region 60 shown in Figure 10 is called the overpressure region 64. In embodiments where a safety threshold (Figure 11) is applied, this limit may be placed within the overpressure region 64. When the controller 24 determines that the system pressure exceeds the threshold defined by the pressure limit curve C, the controller 24 may change the control of the blower 27 to reduce the blower speed in order to lower the system pressure to a target pressure, for example, a pressure value defined by the curve C at the corresponding flow rate. Alternatively / additionally, the controller 24 may control the operation of a valve, such as a proportional valve 25, to reduce the pressure in the system. In some embodiments, the controller 24 may be configured to track the time spent in the limit operating region 60 and / or above the pressure limit curve C, and if the pressure in the breathing system 22 remains in this region after a certain period, the controller 24 may trigger an audible and / or visual alarm to warn the user of the possibility of a blockage in the gas delivery conduit or other components of the system.

[0233] Figure 10 also shows that the pressure can be temporarily increased by the sigmoid pressure limit curve C, and that this increase does not cause the controller to reduce the pressure and / or flow. That is, in the first configuration of the foldable section 204 when in use, the nominal (reference) system pressure in the normal operating pressure region 58 is lower than the pressure limit curve C by at least the first pressure margin M1. In the second configuration of the foldable section 204, the nominal (reference) system pressure in the normal operating pressure region 58 is lower than the pressure limit curve C by at least the second pressure margin M2. The nominal (reference) system pressure may also be the upper limit pressure of the normal operating pressure region 58. Figure 10 shows that the first pressure margin M1 is greater than the second pressure margin M2. That is, system 22 provides an acceptable variation in pressure changes within system 22. When system 22 is in the normal operating region 58, there is a larger margin of acceptable variation from the normal system pressure at higher flows than at lower flows. The tight pressure margin at low flows, which may correspond to the folded state, and the larger margin at high flows, which may correspond to the unfolded state, mean that, in the absence of significant pressure and / or flow rate changes, the control of system 22 will remain in the “folded” or “unfolded” state, respectively, in those regions. Accordingly, the controller 24 ensures that the control will not be changed until the pressure in the system needs to change significantly (e.g., from pressure control to flow control, or vice versa), as this is necessary when the foldable section 204 transitions from a second (folded) configuration to a first (unfolded) configuration, or vice versa, and until the shutoff is substantially released (inducing a transition to flow control) or until the shutoff becomes more than transient (inducing a transition to pressure control).

[0234] Referring to the graph in Figure 11, during operation of the respiratory support system 22 within the normal operating pressure range 58, the controller 24 is configured to control the flow regulator 26 to provide the respiratory gas flow at a target flow rate, for example, at a setpoint flow rate prescribed by the user, such as a clinician, using the I / O interface 20. As long as the system pressure remains below the pressure value defined by the pressure limit curve C at its target flow rate within the normal operating range 58, the controller 24 controls the flow regulator to provide the gas flow at its target flow rate. In this situation, the controller may be considered to be in a first control mode, which is a flow control mode. According to the control shown in Figure 11, when the controller 24 determines that the system pressure is meeting or exceeding the pressure value defined by the pressure limit curve C at its target flow rate (for example, when obstruction begins), the controller 24 is configured to control the flow regulator 26 to adjust the respiratory gas flow to a target pressure that is below the pressure value defined by the pressure limit curve C. In this situation, the controller may be considered to be in a second control mode, which is a pressure control mode. In the embodiment shown in Figure 11, the target pressure includes a pressure value along the pressure limit curve C. As the obstruction increases (for example, as the foldable section 204 is folded more), the flow rate of the breathing gas flow in the system decreases, and the target pressure corresponding to the reduced flow rate also decreases. Accordingly, the controller 24 controls the flow regulator 26 to adjust the breathing gas flow downward along the pressure limit curve C as the amount of obstruction increases.

[0235] The controller 24 may be configured to identify the system pressure when the sensed pressure input value is equal to the value of the curve for the corresponding flow rate, thus "satisfying" the pressure limit curve C. However, it should be understood that the controller may also be programmed to trigger a change in control when the sensed system pressure "approximates" or is very close to the value of the pressure limit curve C, for example, within about 10% of the curve value, or within about 5% of the curve value, or within about 3% of the curve value, or within about 2% of the curve value, or within about 1% of the curve value. In some embodiments, the flow rate of the breathing gas stream may be gradually reduced, and it may be possible to reach a very low flow rate that eventually approaches (or possibly reaches) 0 L / min. This reduces the pressure in the breathing system 22, which may prevent the pressure in the system 22 from satisfying or exceeding the pressure limit curve C.

[0236] In some embodiments, the controller 24 controls the flow regulator 26 to control the breathing gas flow in order to maintain the system pressure at or along the pressure limit curve C. If the system pressure falls below the pressure limit along the pressure limit curve C at the corresponding flow rate, the controller 24 may control the flow regulator 26 to increase the breathing gas flow to achieve a target pressure. This target pressure may be a pressure value along the pressure limit curve C. This target pressure may be a higher target pressure along the pressure limit curve C. In other words, as the blockage decreases or as the blower speed increases relative to a given system pressure, the breathing gas flow rate increases and the corresponding target pressure along the pressure limit curve C increases. Therefore, as the blockage decreases, the controller controls the flow regulator 26 to adjust the breathing gas flow rate upward along the pressure limit curve C toward the flow rate setpoint. The control toward the target pressure may optionally be switched to flow control when the target flow rate is met and the system pressure is below the pressure value at that target flow rate along the pressure limit curve C. The increase and / or decrease in respiratory gas flow may be continuous or stepwise.

[0237] The pressure limit curve C is designed to instruct the controller 24 to avoid or reduce the likelihood of limiting flow within the system 22 that could result in an overpressure event or condition that delivers unsafe patient or system pressures that could damage system components. As stated, the limiting may be intentionally brought about by folding the foldable portion 204 that supplies or forms part of the nasal cannula 200 with the mask 300 attached, or the limiting may be brought about accidentally, for example, by a portion of the delivery conduit tearing, twisting, or bending. The shape of the pressure limit curve C in Figures 10 and 13 is sigmoid or "S" shaped. In embodiments utilizing a sigmoid pressure limit curve, the controller 24 may actuate the flow regulator 26 to adjust the gas flow rate by a variable increase or variable decrease rate. The sigmoid pressure limit curve C allows the controller 24 to control the flow regulator to provide or maintain a low system pressure with a low flow. This can be beneficial in that the foldable portion 204 can be kept folded, while also minimizing the opportunity for a pressure difference or significant pressure difference to cross the foldable portion when in the second configuration, which could otherwise make it difficult for residual flow to be delivered to the patient through the foldable portion 204 or for the mask to be placed over the cannula for the delivery of necessary respiratory support. In some embodiments, the pressure threshold curve C may be defined so that a known amount or range of amounts of residual flow crossing the foldable portion 204 in the second configuration is achieved, for example, by applying a specific amount of pressure difference across the foldable portion 204 in the second configuration to reach a specific amount of residual flow. The smoothness of the pressure threshold curve C provides the user with smooth tactile feedback that can be felt through the foldable portion 204 and the mask 300, and through the mask 300 if a force is present due to system pressure.

[0238] However, it should be understood that the pressure threshold curve C may have various shapes in all situations, and is shaped to directly control gas delivery below the pressure limit for the corresponding flow rate, and is ideally relatively smooth to achieve smooth control (although stepped control resulting from stepped curve C may also be fitted in some embodiments, these may cause control instability between steps). The normal operating region 58 below curve C may be determined by the resistance of the components in the system 22 to flow, and different manufacturing tolerances are possible as discussed above. The parameters of curve C may vary depending on the preference for operation. In some embodiments, a higher pressure limit (y-intercept) at zero flow may result in a larger residual flow across the foldable section 204 when in the second configuration. In other embodiments, the target pressure at zero flow may be close to 0 cmH2O or 0 cmH2O. Alternatively / additionally, a higher pressure limit at high flow rates (i.e., a larger difference between the pressure limit curve C and the normal operating pressure in region 58) may accommodate more deformation in system conditions (e.g., cannula folding or blockage) before the controller 24 adjusts the flow regulator control to reduce the pressure. This increases the allowable range over which the system pressure rises before the pressure limit value of the pressure limit curve C at the target flow rate is met or exceeded. In some embodiments, the curve C may be linear or include a linear section between the control endpoints defined by the minimum and maximum operating pressures. However, controlling the linear curve C may result in an undesirable amount of residual flow crossing the foldable section 204 when in the second configuration at low flow rates. Alternatively / additionally, the curve C may be quadratic or include a quadratic section, which may, in some cases, be more prone to accidental induction of pressure threshold detection in the event of inadvertent or transient bends or twists or other conditions that cause high system pressures. Thus, it has been determined that, in some embodiments, it is preferable for a sigmoid or other S-shaped curve, in conjunction with the "restriction" operating region 60, to guide control.

[0239] Figure 12 is a graph showing that the pressure curve can have a nominal pressure limit (curve R) or a zero pressure limit (curve S) at zero flow. The zero pressure limit at zero flow theoretically provides zero residual flow when there is a blocked or folded state in the system. The higher the nominal zero flow pressure limit (curve R), the more residual flow may be generated when folded. In some embodiments, it may be desirable to operate the system 22 at a low or zero flow with a small amount of residual pressure (for example, when the foldable section 204 is in a second state). In such embodiments, the controller 24 controls and maintains the operation of the flow regulator 26 so that a small amount of system pressure is maintained at zero (or low) flow, for example, so that the blower 27 is maintained at a very low angular velocity. This has the advantage of helping to restore flow in the system and to the patient when the foldable section 204 changes toward a first configuration. Specifically, when the foldable section 204 changes from the second configuration to the first configuration (i.e., the obstruction is reduced), the breathing gas flow rate increases and the system pressure decreases. The controller 24 controls the flow regulator 26 to adjust the breathing gas flow to a new target pressure in response to the given increased flow rate. In order to reach that new target pressure, the breathing gas flow rate increases again to provide the new target pressure.

[0240] Accordingly, the controller 24 controls the flow regulator 26 to adjust the breathing gas flow to the target pressure along the pressure limit curve C until the flow rate setpoint is met, at which point the controller 24 switches to flow control mode. However, small amounts of system pressure at zero (or low flow) can create a pressure difference across the foldable section 204, which can result in residual flow. In some applications, residual flow is desirable. In other applications, residual flow is undesirable, and such residual flow may be stopped or substantially reduced by configuring the pressure limit curve so that the y-axis of the pressure-flow graph intersects the origin (0,0), which should correspond to the complete stop of the flow regulator 26. In such embodiments, the absence of any flow in the system may make it impossible for the controller 24 to determine whether there has been a change in pressure and / or flow in the system in order for the controller 24 to operate adequately in pressure control (pressure-induced control) and / or flow control (flow-induced control) modes. Accordingly, the controller 24 may be configured to control the flow regulator 26 to deliver a short burst or pulse of flow corresponding to a “test pulse” to determine whether there has been a change in system pressure indicating that the blockage or interruption (for example, caused by the foldable section 204 being in the second configuration) has been removed. If the test pulse results only in an increase in system pressure (with only a slight increase in flow rate), the controller determines that the blockage or interruption remains and that pressure-inducible control (or deactivation of the flow regulator except for the test pulse) should continue. Recognizing that more regular (or longer) pulses may increase residual flow when the interruption has not been removed, the duration between test pulses may be pre-programmed and / or modified on request. Conversely, if the duration between pulses is long, residual flow may be significantly reduced, but the controller may not respond adequately because it cannot detect the reduction in system pressure until the test pulse occurs. If the controller detects an increase in flow in response to a test pulse, it may decide to remove the blockage and adjust the flow regulator control to increase the velocity, thereby increasing the flow and / or pressure in the system.

[0241] In one example, the controller 24 continuously or periodically receives sample data indicating the pressure and / or flow rate of the respiratory gas flow in the system 22 and compares the received data with values ​​obtained from the pressure limit curve C. Ideally, the controller 24 seeks to achieve a target flow rate corresponding to a flow rate setpoint, provided that the pressure in the system does not exceed the target pressure corresponding to the value along the curve C. The controller 24 may control the flow regulator 26 in response to the received pressure value. For example, if the received pressure value indicates that the system pressure satisfies or exceeds the value of the curve C for the corresponding flow rate, the controller 24 controls the system to achieve a system pressure that is less than or equal to the value of the curve C for the corresponding flow rate (i.e., pressure-induced control). Alternatively, if the received pressure value indicates that the system pressure does not satisfy or exceed the value of the curve C, the controller controls the system to achieve the target flow rate (i.e., flow-induced control). As an example, the controller 24 may adjust the operation of the system 22 to reduce the respiratory gas flow in response to a received pressure exceeding the value of the pressure limit curve C for the corresponding flow rate by controlling the flow regulator 26 to reduce or stop the respiratory gas flow supplied to the patient. Alternatively or additionally, the controller may actuate the proportional valve 25 to reduce the system pressure. Conversely, the controller may adjust the operation of the system 22 to increase the breathing gas flow in response to a received pressure that does not exceed the value of the pressure limit curve C for the corresponding flow rate, by controlling the flow regulator 26 (and optionally the proportional valve 25) to increase the breathing gas flow in response to a pressure that does not exceed the value of the pressure limit curve C for the corresponding flow rate.

[0242] If the controller 24 determines that the received pressure does not exceed the pressure limit curve C, and determines the difference between the target flow rate and the measured flow rate, the controller 24 can then output commands via the digital communication interface or by adjusting the supply voltage or current to increase or decrease the motor speed of the blower 27 and / or open or close the proportional valve 25. The control can be modified based on the difference by controlling, for example, the supply voltage or current to the blower and / or proportional valve binaryly (e.g., switching the blower on / off) or continuously, for example. If the sensed pressure value satisfies or exceeds the pressure limit curve C, the controller 24 may reduce the supply voltage or current to the blower by using a set reduction amount, a set speed, a variable reduction speed, or pressure-based PID control or the above. The angular velocity of the blower may be reduced with each iteration of the feedback control until the sensed pressure value is less than or equal to the pressure limit curve C or until the flow threshold is reached. This may indicate a shut-off state. The angular velocity of the blower may be reduced to a constant speed or a variable speed.

[0243] Figure 13 shows an example of a sigmoid pressure limit curve C in the characterization of offset pressure for clarity. Figure 13 shows how the normalized system pressure and the pressure threshold for low flow (e.g., 1 cmH2O) differ from the pressure threshold for high flow (e.g., 20 cmH2O). The sigmoid-shaped pressure limit curve C has a first pressure region 66 corresponding to a normal nasal cannula 31, a second pressure region 68 corresponding to a folded nasal cannula 31, or some other limit on the flow of the system 22 or delivery conduit 30. The sigmoid-shaped pressure limit curve C has a transition region indicated by a dashed line 69, aligned between the first pressure region 66 and the second pressure region 68. The first pressure region 66 is substantially parallel to the second pressure region 68 of the pressure limit curve C. The first pressure region 66 and the second pressure region 68 correspond to pressure thresholds for the corresponding flow rates within their respective regions. The transition region may be determined according to the required operating parameters, typically by a trade-off between preferring the benefits of a lower pressure threshold over a wider range of low flow or the benefits of a higher pressure threshold over a wider range of high flow. Connecting by a smooth "S"-shaped transition provides smoother control and avoids the vibrations and / or instability that may occur in the system if the pressure transition were an instantaneous step. While two pressure regions are described in relation to the pressure limit curve C, it should be understood that additional pressure regions may be provided.

[0244] The transition region 69 of the pressure limit curve represents the maximum increase / decrease rate of respiratory gas flow control, centered around a transition flow rate lower than the flow setpoint (i.e., target flow rate) during normal operation. That is, the controller 24 is configured to control the flow regulator 26 to reduce the respiratory gas flow at the maximum reduction rate when the sensed pressure and flow rate are within the transition region 69 of the pressure limit curve, and the sensed pressure exceeds the pressure limit curve C for the corresponding flow rate. In one example, the system 22 prevents the patient airway pressure from exceeding the safety limit when in this transition region 69, and reduces the flow (ideally to near zero) when, for example, the nasal cannula 200 is folded for bag-mask ventilation.

[0245] As stated, the difference between the flow rate in the transition region and the target flow rate allows for a temporary increase in system pressure, and in case the cause of the pressure increase is a temporary limitation and the temporary pressure increase is immediately removed, the controller 24 can reduce the breathing gas flow at an initial minimum reduction rate until it approaches the transition flow rate.

[0246] Figure 14 is a graph provided to show the changing relationship between pressure and flow rate as resistance to flow experienced in the system increases, for example, as the pressure applied by the clinician to the mask placed over the cannula increases (or when there is an increase in another type of blockage in the system). When the clinician pushes down the mask, the cannula begins to fold, and the resistance to flow in the system increases, which is detected as an increase in system pressure. The increase in resistance to flow is represented in Figure 14 as a dashed line with increasing slopes R1 to R4, where R1 represents the lowest resistance on the graph and R4 represents the highest resistance. These demonstrate that, for a given flow rate, the system pressure increases as resistance to flow increases by folding the cannula, and when the resistance to flow is sufficiently high (e.g., the cannula is fully folded), the system pressure intersects the pressure limit curve C. Higher resistances cross the curve further below the pressure limit curve C, as indicated by intersections P1, P2, and P3. P3 corresponds to a fully or nearly fully folded cannula (or another type of full or nearly full blockage) that has high resistance to flows (R4 curve) that easily cross the pressure limit curve C at low pressure and flow.

[0247] In some embodiments, when the controller 24 determines that the system 22 has encountered an obstruction or that the foldable section is in a second state, the folded state 68 (Figure 13), the controller 24 controls the flow regulator 26 to reduce the flow. The controller 24 may further be configured to provide an output, such as a visual or audible alarm, via an I / O device 20 or any other system component, to indicate that the foldable section is in the folded state and / or that delivery of the anesthetic may begin. In some embodiments, this output may include a control signal provided to the anesthesia machine. This can be advantageous when the anesthetic is delivered via inhalation through a mask 300 over a nasal cannula 200, because if the flow delivered to the patient is not substantially reduced, these flows can dilute the anesthetic.

[0248] As mentioned, Figure 10 shows a limiting region 60 where a sigmoid pressure limit curve C may be defined, and where a temporary increase in pressure may occur before the controller 24 changes the control of the flow regulator 26. This temporary increase in pressure may occur, for example, due to an unintentional bending of the tubing of the breathing system 22. In some embodiments, the pressure limit curve C may be set as close as possible to the expected normal pressure in order to minimize the flow at lower pressures and move the mask 300 over the nasal cannula 200 without rapidly increasing the flow to the flow rate setpoint.

[0249] It will be recognized that the pressure limit curve C is not limited to a sigmoid shape. However, a sigmoid shape allows for a rapid transition of pressure between two pressure regions without an instantaneous jump between them. An instantaneous jump can be undesirable because this gap may introduce instability into the control of the breathing system 22. For example, the output from the controller 24 (e.g., the blower speed control parameter) should change significantly in response to the instantaneous rate of change in pressure and flow within the transition region, and this instantaneous rate of change in the controller output introduces instability.

[0250] Referring again to Figure 13, while the respiratory system 22 can operate within the normal operating region 66, when operating closer to the transition region 69 of the sigmoid pressure limit curve C, the respiratory system 22 may transition more rapidly between pressure states (i.e., lower pressure offsets relative to the normal operating pressure and higher pressure offsets). As mentioned earlier, rapid pressure transitions are still possible, and different overall curve shapes, such as a "Z"-shaped curve, can be imagined. A "Z"-shaped curve allows the pressure limit curve to be "flat" (stable at the pressure limit) in both its unfolded and folded states.

[0251] Figure 15 is a state diagram of the operating state of the breathing system 22, referring to the pressure limit curves in Figures 9-14. From the normal operating state of the breathing system 22, the normal state may transition to a mismatch / disconnection state. In the mismatch / disconnection state, the controller may increase the breathing gas flow to approach the target flow rate / setpoint, but the sensed pressure will not meet the expected value, so the controller 24 may trigger an alarm to the user of the breathing system 22, and / or the controller may activate the flow regulator 26 or proportional valve 25 to reduce or stop the flow.

[0252] The normal state may also transition to a limited state where the system pressure satisfies (but does not exceed) a pressure limit curve C for a given flow rate, for example. That is, in some embodiments, when the sensed pressure is at pressure limit curve C for a given flow rate, the controller initiates pressure induction control to keep the pressure at or below the pressure limit. In other embodiments, the controller may reduce the blower speed or decrease the opening of the flow regulator's proportional valve when the sensed pressure satisfies or exceeds pressure limit curve C. Alternatively, the controller 24 may remain in pressure induction control but change the target flow rate to a lower setpoint. For example, when the pressure satisfies or exceeds the pressure limit curve, the controller may set a new target flow rate at a lower setpoint, for example, 20 L / min, rather than a target flow rate of, for example, 70 L / min set by the operator. When the controller 24 determines that the system pressure has dropped below the pressure limit, the controller may then switch to flow induction control and increase the blower speed or increase the opening of the flow regulator's proportional valve to (gradually) meet the flow rate setpoint. The controller 24 periodically or continuously checks the system pressure and, if the system pressure has not been reduced below the pressure limit, may maintain or further reduce the flow regulator parameters discussed above. The reduced blower speed may be achieved, for example, by reducing the control signal or supply current (or voltage) to the flow regulator to reduce the blower angular velocity. Alternatively / additionally, the controller may control the operation of the proportional valve to reduce the flow. In other embodiments, the controller 24 may be configured to determine the current system pressure only once it has been established that the system is operating at a lower flow setpoint, rather than periodically or continuously determining the system pressure, based on the flow input.

[0253] Under normal conditions, the controller may control the flow regulator 26 to deliver a target flow rate (also called a setpoint flow rate) to the patient through the nasal cannula 200. The controller 24 may control the respiratory system 22 to enable operation in a restricted state without switching between flow-guided and pressure-guided control, in order to minimize events that restrict flow in response to accidental or unnecessary pressure and / or instantaneous or transient changes in system pressure. This allows the user of the respiratory system 22 to perform normal tasks with the respiratory system 22 more freely without transitioning to any of the overpressure conditions described above, such as moving / bending the circuit, checking whether the patient is breathing, moving the head, waking the patient as much as possible, inserting a nasal fiber optic tube, etc. The pressure limit curve C is set to be as high as possible while ensuring patient safety in some embodiments.

[0254] As the sensed pressure increases its crossing of the pressure limit curve C at the corresponding flow rate, the limiting state transitions to an overpressure state. In the overpressure state, the controller 24 is configured to control the flow regulator 26 or proportional valve 25 to reduce or stop the respiratory gas flow as described above, and / or to trigger an audible and / or visual alarm if this state persists for an extended period. Ideally, the transition to the overpressure state causes the controller to transition to pressure-induced control, and in some embodiments, the controller may be configured to sound an alarm while the controller is in pressure-induced control mode, or if the pressure-induced control lasts longer than a pre-programmed duration or a pre-programmed percentage of the period during which respiratory support is provided to the patient. One or more warnings or alarms may also be triggered during the overpressure state for other parameters, such as whether there is flow delivered to the patient and / or what percentage (e.g., 90%) of the target flow rate is achieved.

[0255] In some embodiments, the controller is configured to provide an alarm system that communicates priority information or warnings to the user. For example, a first visible and / or audible warning may be a red, higher volume, and / or continuous tone indicating highest priority; a second visible and / or audible warning may be an orange, lower volume, and / or pulsed tone indicating second priority; a third visible and / or audible warning may be green (or yellow, white, etc.) and / or pulsed tone with a lower pulse frequency indicating third priority, and so on. Visible warnings may be provided by the I / O interface 20, or by LEDs, or similarly on the housing 33 or on components that may be located away from the housing, such as an IV pole, bed rail, or mountable to the user for the user's convenience. Various priorities may correspond to various system states having different priorities for warnings (based on patient care requirements). Warnings may be generated by controller 24 or by any combination of system controllers / microcontrollers, such as a safety microcontroller, which may be configured to provide or enable LEDs with multiple levels of brightness (e.g., dim and brightest) to ensure that there is always at least one LED lit when the device receives power. This ensures that any system failure (e.g., a crash of the microcontroller driving the LEDs) does not falsely indicate that the entire system is off. In this configuration, the warning LEDs are only completely extinguished when power to the device is completely cut off.

[0256] In further embodiments, the controller may be configured to provide different warnings depending on where the system is operating on the pressure limit curve C. For example, the controller 24 may be configured to emit a first audible warning from the I / O interface 20 consisting of, for example, 5 beeps per second when shutoff is guided to the system, causing the system pressure to meet or exceed the pressure limit curve at or near the target flow rate, triggering the controller 24 to switch to pressure induction control (see X in Figure 9). Alternatively / additionally, the controller 24 may be configured to emit a second audible warning from the I / O interface 20 consisting of, for example, 3 beeps per second when the system pressure is progressing along the pressure limit curve C (towards and through Y in Figure 9), and a third audible warning consisting of, for example, 1 beep per second may be emitted when the system pressure and / or flow is further reduced (see Z in Figure 9). The beep rates provided in this example are suggested solely to demonstrate the effectiveness of different warning sounds (or visual cues) representing different operating states of the system, providing useful feedback to clinicians, such as whether the foldable section 204 is fully folded. It should be understood that these and other warnings may be provided audibly or visually by the controller, activating the I / O interface 20 and / or other components that may be located away from the system housing 33 as described above.

[0257] Further states of the breathing system 22 may be interrupted, transitioning from a normal or restricted state. An interrupted state is transitioned from a restricted or normal state when the sensed flow rate reaches a threshold, for example, 2 L / min, or 0 L / min, and when the system pressure is greater than or equal to the pressure limit curve C for the corresponding flow rate. In some embodiments, when an interrupted state is present, the controller 24 controls the flow regulator 26 to adjust the breathing gas flow (which may be 0 L / min) to a target pressure above 0 cmH2O (where the pressure limit curve C intersects the y-intercept). Therefore, in such embodiments, the system pressure is zero or substantially low. Once the blockage or interruption in the system is removed, the system pressure decreases and the breathing gas flow rate increases. The controller 24 controls the flow regulator 26 to adjust the breathing gas flow to a new higher target pressure corresponding to the higher flow rate. As the flow regulator 26 increases the pressure of the breathing gas flow, the flow rate increases accordingly, resulting in a new higher flow rate that establishes a new target pressure corresponding to the new higher flow rate. Accordingly, the flow regulator 26 is configured to regulate the breathing gas flow to a target pressure until the flow rate setpoint is met, after which the controller 24 switches to flow induction control. In addition or by other means, the controller 24 determines whether the sensed pressure and flow rate correspond to a pressure waveform that coincides with the time when the nasal cannula 31 is folded and bag-mask ventilation has occurred. If this cannot be determined, the controller 24 may continue to increase the flow and return to the first configuration.

[0258] Figure 16 is a high-level schematic diagram of the operational control of the breathing system 22 according to an example of the present disclosure. In the example shown, the controller 24 may be considered to provide a flow controller that provides a flow control output, and a pressure controller that provides a pressure control output, operating as a separate module of the controller 24. The flow controller uses a flow setpoint (which may be a target flow rate) and a sensed flow rate (a measured flow value) as inputs, and the pressure controller uses a pressure setpoint and a sensed pressure (a measured pressure value) calculated from a pressure limit curve C for the corresponding measured flow rate as inputs. The controller 24, which simultaneously implements these pressure and flow controllers, can thus provide the breathing system 22 with pressure-inductive control and flow-inductive control. A change in control in either the pressure-inductive or flow-inductive control mode may be achieved, for example, by changing the control of the flow regulator to achieve a change in the angular velocity of the blower, and / or by changing the supply current or voltage to achieve the required increase or decrease in flow rate, by changing the control of the proportional valve. As described above, the predetermined pressure threshold and the corresponding flow rate represented by curve C are stored in a memory component of the controller 24 or a memory component operably connected to the controller 24, and can be represented in any suitable form, such as a function, curve, lookup table or algorithm or similar. To implement control, the controller 24 selects a minimum control value determined by the flow control system and the pressure control system to control the flow regulator / blower or proportional valve.

[0259] Referring next to Figure 17, schematic steps in a method 70 of operating a respiratory support system 22 according to an embodiment of the present disclosure to provide a respiratory gas flow to a patient. In step 71, a respiratory gas flow is provided to the patient by the respiratory support system 22, which may be a target flow rate. This typically involves adding a patient interface to the patient, who receives the respiratory gas flow from the flow source of the respiratory support system under the control of the respiratory support system controller. In step 72, the controller determines the system pressure corresponding to the gas pressure downstream of the flow regulator. The system pressure is typically determined using one or more sensors, such as one or more pressure sensors configured to determine the pressure of the respiratory gas flow in the respiratory system, but in other embodiments, the system pressure may be measured and provided to the controller by manual means, such as an operator inputting a value using an input / output interface that operably communicates with the controller. In step 73, the controller receives an input indicating the flow rate of the respiratory gas flow in the system. Typically, the flow rate is measured by one or more sensors, such as one or more flow sensors. In step 74, the controller compares the system pressure determined in step 72 with a predetermined pressure threshold for the corresponding flow rate at which the respiratory support system may be activated. Specifically, the controller compares the system pressure determined in step 72 with a pressure threshold for the corresponding target flow rate. The pressure threshold is stored in a memory component of the controller or a memory component operably connected to the controller and may be represented in any suitable form, such as a function, curve, lookup table or algorithm or similar. In some embodiments, the memory component may include a computer-readable medium (e.g., a disk, hard drive, USB, optical drive, or other data storage device) containing program instructions for causing the controller to perform the necessary controls as described herein.In step 75, the controller controls components of the respiratory support system, such as a flow regulator, to maintain, increase, or decrease the breathing gas flow in response to the system pressure, which meets or exceeds the pressure threshold at the target flow rate, or does not meet or exceed it, as determined by the controller in step 74. In embodiments where the comparison in step 74 determines that the pressure threshold meets or exceeds the target flow rate, the controller may switch to a pressure-induced control mode (Figure 15), in which the controller controls the operation of the system components to reduce the system flow and / or pressure. Alternatively, the controller may remain in flow-induced control mode but change the target flow rate to a lower setpoint. In embodiments where the comparison in step 74 determines that the pressure is below the pressure threshold and the target flow rate has been achieved, the controller switches to flow-induced control mode (Figure 15). In embodiments where the comparison in step 74 determines that the pressure is below the pressure threshold but the target flow rate has not been achieved, the controller may remain in pressure-induced mode, in which the controller controls the flow regulator to the target pressure.

[0260] It should be understood that various modifications, additions, and / or substitutions may be made to the parts described herein without departing from the scope of the invention, as defined in the claims attached herein.

[0261] The present invention may be said to be broadly comprised, individually or collectively, of the parts, elements, and features referred to or shown in the details of this application in any or all of the aforementioned parts, elements, or features. Where, in the foregoing description, integers or components having known equivalents thereof are referred to, those integers are incorporated herein as if they were individually described.

[0262] When any or all of the terms “comprise” (including), “comprises” (including), “comprised” (including), or “comprising” (including) are used herein (including in the claims), those terms shall be construed as specifying the existence of any particular feature, integer, step, or component, but shall not exclude the existence of any other feature, integer, step, or component, or any group thereof.

[0263] It should be understood that the following claims are provided for illustrative purposes only and are not intended to limit the scope of any claims that may be asserted in the future. Features may be added to or omitted from the claims at a later date to further define or redefine one or more of the inventions.

Claims

1. A respiratory system for providing a respiratory gas flow to a patient, Flow regulator and The system is configured to receive inputs of the flow rate and pressure of the breathing gas flow within the system, The flow regulator is controlled to provide the patient with the respiratory gas flow at a target flow rate. A controller configured to control the flow regulator to adjust the breathing gas flow to a target pressure when the pressure of the breathing gas flow in the system meets or exceeds a pressure threshold corresponding to the target flow rate. Includes, The target pressure includes the pressure threshold corresponding to the target flow rate, or the pressure threshold corresponding to a flow rate less than the target flow rate. The controller is further configured to receive a flow rate value indicating the flow rate of the respiratory gas supplied to the patient. The aforementioned controller, When the flow rate exceeds the target flow rate, the system is capable of operating in a first control mode to control the flow rate to the target flow rate. When the pressure of the breathing gas flow exceeds the pressure threshold corresponding to the target flow rate, or when it exceeds the pressure threshold corresponding to a flow rate less than the target flow rate, the system can be operated in a second control mode to control the pressure to the target pressure. Respiratory system.

2. The controller is configured to control the flow regulator to adjust the breathing gas flow to the target pressure when the flow rate of the breathing gas flow is less than the target flow rate, and / or The controller is configured to control the flow regulator to adjust the breathing gas flow to the target flow rate when the flow rate of the breathing gas flow exceeds the target flow rate, and / or The breathing system according to claim 1, wherein the controller is configured to control the flow regulator to the target pressure when the pressure of the breathing gas flow exceeds the pressure threshold corresponding to the target flow rate, or the pressure threshold corresponding to a flow rate less than the target flow rate.

3. The breathing system according to claim 1 or 2, wherein when the system starts operating from an "off" or dormant state, the controller is configured to monitor the flow rate of the breathing gas flow within the system and to control the flow regulator to adjust the breathing gas flow to the target flow rate.

4. The aforementioned target flow rate is the flow rate setting point, and / or The flow rate setting point is determined by the user of the breathing system, and / or The target flow rate changes over time in order to increase it from the current value to the set flow rate point. The respiratory system according to any one of claims 1 to 3.

5. The breathing system according to any one of claims 1 to 4, wherein the controller includes a flow controller that provides a flow control output and a pressure controller that provides a pressure control output, and the control input to the flow regulator is the minimum value of the flow control output and the pressure control output.

6. The flow regulator includes a blower, and the flow rate control output and the pressure control output include the angular velocity of the blower, and / or The flow regulator includes a proportional valve, and the flow rate control output and the pressure control output include limiting the flow path to a certain size through the proportional valve, and / or The flow regulator includes a flow generator configured to be controlled by the controller to adjust the respiratory gas flow to the patient, and / or The flow regulator includes a proportional valve configured to be controlled by the controller to regulate the breathing gas flow, The respiratory system according to claim 5.

7. The breathing system according to claim 6, wherein the flow generator includes a blower configured to be controlled by the controller to generate the breathing gas flow.

8. The respiratory system includes one or more flow sensors configured to sense the flow rate of the respiratory gas flow to the patient within the system, and / or The respiratory system includes one or more pressure sensors configured to sense the pressure of the respiratory gas flow to the patient within the system, and / or The controller is further configured to receive inputs from one or more flow sensors indicating the flow rate of the breathing gas flow in the system, and inputs from one or more pressure sensors indicating the pressure of the breathing gas flow in the system. The respiratory system according to any one of claims 1 to 7.

9. The respiratory system according to any one of claims 1 to 8, further comprising a delivery conduit for providing a gas flow from the flow regulator to a patient interface, wherein the patient interface is configured to deliver the respiratory gas flow to the patient.

10. The respiratory system according to claim 9, wherein the patient interface comprises a gas delivery side arm having fluid communication with the delivery conduit, a manifold provided at the end of the gas delivery side arm, and one or more nasal elements extending from the manifold, configured to provide the respiratory gas flow to one or more nostrils of the patient, the gas delivery side arm comprising a foldable portion configured to control the flow rate of the respiratory gas flow through the foldable portion.

11. The foldable portion is operable in a first configuration in which the foldable portion is substantially open, and in a second configuration in which the foldable portion is substantially closed. When pressure is applied to the foldable portion, the foldable portion folds into the second configuration. When the pressure is removed from the foldable portion, the foldable portion returns to the first configuration. The respiratory system according to claim 10.

12. The delivery conduit further includes a delivery circuit and a patient breathing circuit arranged between the delivery circuit and the patient interface, the patient breathing circuit being connected to the delivery circuit by an outlet connector. The respiratory system according to claim 10 or 11.

13. The respiratory system according to any one of claims 9 to 12, wherein the patient interface includes a nasal cannula.

14. The respiratory system according to claim 13, wherein the nasal cannula includes an unsealed nasal cannula.

15. When the controller controls the flow regulator to the target pressure, the flow to the patient is reduced to a reduced flow rate of approximately 15 L / min or less, or approximately 10 L / min or less, or approximately 10 L / min, or approximately 5 L / min to approximately 10 L / min, or less than approximately 5 L / min, or 0 L / min, and / or The breathing system according to any one of claims 1 to 14, wherein the controller is configured to control the flow regulator to increase the breathing gas flow toward the target flow rate.

16. The respiratory system uses oxygen (O) from the respiratory system. 2 ) O configured to sense pressure within the delivery circuit 2 Including a pressure sensor and / or, The respiratory system uses oxygen (O) from the respiratory system. 2 ) O in the delivery circuit 2 O configured to sense the flow rate 2 Including a flow sensor, or The respiratory system senses the pressure within the oxygen (O 2 ) delivery circuit of the respiratory system and is configured with an O 2 pressure sensor, and senses the flow rate of the O 2 flow within the oxygen (O 2 ) delivery circuit of the respiratory system and is configured with an O 2 flow rate sensor, and includes The respiratory system according to any one of claims 1 to 15.

17. The breathing system according to claim 16, as dependent on claim 6, wherein the proportional valve is arranged between the O2 pressure sensor and the O2 flow sensor in the O2 delivery circuit.

18. The patient breathing circuit is the O 2 Connected to a delivery circuit and an air delivery circuit, the patient breathing circuit and / or the patient interface further include a patient pressure sensor and a patient flow sensor. The respiratory system according to claim 16 or 17, as dependent on claim 10 or 11.

19. The breathing system according to claim 18, wherein the flow regulator includes a blower, and the blower is arranged in the patient breathing circuit before the patient pressure sensor and the patient flow sensor.

20. The breathing system according to any one of claims 1 to 19, wherein the controller is operably in communication with, or includes, a memory component that stores one or more functions, curves, lookup tables, or algorithms that provide a relationship between the pressure threshold and the corresponding flow rate.

21. The controller is configured to control the flow regulator so as to reduce the breathing gas flow by a variable reduction rate, and / or The relationship between the pressure threshold and the corresponding flow rate can be represented by a pressure limit curve or function that defines a curve having a sigmoid shape, and / or The breathing system according to claim 20, wherein the relationship between the pressure threshold and the corresponding flow rate includes a first pressure region corresponding to a first end of the curve, a second pressure region corresponding to a second end of the curve, and a transition region corresponding to the portion of the curve between the first pressure region and the second pressure region.

22. The breathing system according to claim 21, as dependent on claim 10 or 11, wherein the first pressure region corresponds to when the foldable portion is substantially in the first configuration, and the second region corresponds to when the foldable portion is substantially in the second configuration.

23. The breathing system according to claim 22, wherein the first pressure region includes a pressure threshold offset by a first pressure margin from a reference pressure value, and the second pressure region includes a pressure threshold offset by a second pressure margin from a reference pressure value, so that the first pressure margin is greater than the second pressure margin.

24. The breathing system according to claim 23, wherein the first and second margins provide an offset of the pressure threshold in the first pressure region that is substantially parallel to the offset of the pressure threshold in the second pressure region of the pressure limit curve, and the first and second pressure regions correspond to the minimum rate of change of the breathing gas flow.

25. The slope of the transition region of the pressure limit curve corresponds to the maximum rate of change of the breathing gas flow, and / or The transition region of the pressure limit curve is centered on the transition flow rate. The respiratory system according to any one of claims 22 to 24.

26. The breathing system according to claim 25, wherein the controller is configured to control the flow regulator so that the breathing gas flow reaches the maximum rate of change when the pressure and the corresponding flow rate are within the transition region of the pressure limit curve.

27. The breathing system according to any one of claims 21 to 26, wherein the first and second pressure margins provide a margin for temporarily reducing the system pressure of the breathing gas flow from below the pressure threshold without the controller controlling the flow regulator to increase the breathing gas flow.

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