Method and / or device for determining respiratory parameters - Patents.com

Abstract

1. A method for determining respiratory parameters during inhalation of a patient when the patient is receiving respiratory assistance and has his / her mouth closed, the method comprising: providing a system gas flow having a flow rate and a gas fraction to the patient; measuring the gas fraction of a combined gas inlet flow to the patient; determining the flow rate of the combined gas inlet flow using one or more of the gas fraction of the system gas flow, the flow rate of the system gas flow, the gas fraction of the combined gas inlet flow, and an ambient gas fraction; and determining one or more respiratory parameters from the flow rate of the combined gas inlet flow.

Description

[Technical field]

[0001] The present invention relates to a method and / or device for determining a respiratory parameter. [Background technology]

[0002] When providing respiratory support, it is desirable to know various parameters such as patient flow, tidal volume, minute ventilation, apnea, respiratory rate, airway patency, peak flow, etc., which are not always measurable. Summary of the Invention [Problem to be solved by the invention]

[0003] It is an object of the present invention to provide a method and / or device for determining one or more respiratory parameters as described herein. [Means for solving the problem]

[0004] In one aspect, the present invention can be said to include a method of determining respiratory parameters during inhalation of a patient when the patient is receiving respiratory assistance and has his / her mouth closed, the method comprising providing a system gas flow having a flow rate and a gas fraction to the patient, measuring the gas fraction of a combined gas inlet flow to the patient, determining the flow rate of the combined gas inlet flow using one or more of the gas fraction of the system gas flow, the flow rate of the system gas flow, the gas fraction of the combined gas inlet flow, and the ambient gas fraction, and determining one or more respiratory parameters from the flow rate of the combined gas inlet flow.

[0005] Optionally, the respiratory parameters are one or more of tidal volume, minute ventilation, respiratory rate, apnea, airway patency and / or peak flow.

[0006] Optionally, the flow rate of the device gas flow is less than the patient's inhalation demand for at least a portion of the inhalation.

[0007] Optionally, for a portion of the inhalation, the system gas flow is at a first flow rate that is equal to or greater than the inhalation demand; and For a portion of the inhalation, the system gas flow is at a second or subsequent flow rate, each of the second or subsequent flow rates being less than the inhalation demand.

[0008] Optionally, the inhalation demand is the inhalation demand of a patient on whom the method is performed.

[0009] Optionally, the flow rate of the system gas stream varies over time such that for a portion of an inhalation the flow rate is equal to or greater than the inhalation demand, and for a portion of an inhalation the flow rate is less than the inhalation demand.

[0010] Optionally, the time-varying flow rate varies, optionally at a frequency higher than the breathing frequency.

[0011] Optionally, the gas proportion is a gas fraction and / or a gas partial pressure.

[0012] Optionally, the intake demand is a peak intake demand.

[0013] Optionally, the combined gas input stream includes a system gas stream and an ambient (entrained) gas stream.

[0014] Optionally, the gas is one or more of O2, CO2, N2, or a tracer gas.

[0015] Optionally, the gas fraction of the combined gas input stream is measured with a sensor in the nose.

[0016] Optionally, the method includes determining a flow rate of the combined gas inlet stream using all of the gas fraction of the system gas stream, the flow rate of the system gas stream, the gas fraction of the combined gas inlet stream, and the ambient gas fraction.

[0017] Optionally, a flow rate Q of a combined gas inlet flow for the patient. TOT teeth,

number

[0018] Optionally, the tidal volume is selected from the following: V Tidal (t) = ∫Q Tot (t)dt (38) It can be defined as:

[0019] In another aspect, the present invention provides a method for determining respiratory parameters during exhalation of a patient while the patient is receiving respiratory assistance and the patient's mouth is closed, comprising the steps of: providing a system gas flow to a patient having a flow rate and a gas ratio; Measuring a parameter of gas present in the combined gas output stream from the patient; The expiratory gas flow rate is Gas fraction of the system gas stream; Flow rate of the system gas stream; gas parameters of the composite gas outlet stream; Exhalation gas flow parameters determined using measured parameters of gases present in the composite gas output stream and time-varying flow rates or gas fractions. and determining using one or more of determining one or more respiratory parameters from the expiratory gas flow; It can be said that the present invention includes a method including the steps of:

[0020] Optionally, the respiratory parameters are one or more of tidal volume, minute ventilation, respiratory rate, apnea, airway patency and / or peak flow.

[0021] Optionally, the gas proportion is a gas fraction and / or a gas partial pressure.

[0022] Optionally, the combined gas output stream includes a leakage gas stream and an exhalation gas stream.

[0023] Optionally, the composite gas output flow parameter includes a gas fraction measured by a sensor in the nose.

[0024] Optionally, the gas is one or more of O2, CO2, N2, or a tracer gas.

[0025] Optionally, the method includes determining a flow rate of the expiratory gas flow using all of the gas fraction of the system gas flow, the flow rate of the system gas flow, the gas fraction of the combined gas outlet flow, and the expiratory gas flow parameters.

[0026] Optionally, one of the flow rate and the gas proportion varies over time.

[0027] Optionally, the flow rates or gas ratios of the system gas streams are varied.

[0028] Optionally, the flow rate or gas fraction varies at a frequency higher than the breathing frequency.

[0029] Optionally, the expiratory gas flow parameter is a gas fraction of the expiratory gas flow.

[0030] Optionally, a flow rate Q of the patient's exhaled gas flow. E teeth,

number

[0031] Optionally, when variable flow rates are used for system gas flow and expiratory O2 fraction,

number

[0032] Optionally, when variable flow rates are used for system gas flow and exhaled CO2 fraction,

number

[0033] Optionally, when using variable oxygen fraction for system gas flow and expiratory O2 fraction:

number

[0034] Optionally, the tidal volume is: V Tidal (t) = ∫Q E (t)dt (42) It can be defined as:

[0035] In another aspect, the present invention can be said to include a method of determining respiratory parameters of a patient during exhalation when receiving respiratory assistance, the method comprising providing a system gas flow having a flow rate and gas fraction to the patient, measuring parameters of gases present in a combined gas output from the patient, determining a volume fraction of the system gas flow through the mouth and / or nose, determining an expiratory gas flow rate using one or more of the system gas flow gas fraction, the system gas flow rate, gas parameters of the combined gas output, the system gas flow volume fraction, expiratory gas flow parameters, where the expiratory gas flow parameters are determined using the measured parameters of gases present in the combined gas output and the time-varying flow rate or gas fraction of the system gas flow, and determining the one or more respiratory parameters from the expiratory gas flow rate.

[0036] Optionally, the respiratory parameters are one or more of tidal volume, minute ventilation, respiratory rate, apnea, airway patency and / or peak flow.

[0037] Optionally, the gas proportion is a gas fraction and / or a gas partial pressure.

[0038] Optionally, the combined gas output stream includes a leakage gas stream and an exhalation gas stream.

[0039] Optionally, the composite gas output flow parameter is a gas fraction measured with a sensor at the mouth.

[0040] Optionally, the gas is one or more of O2, CO2, N2, or a tracer gas.

[0041] Optionally, the method includes determining a flow rate of the expiratory gas flow using all of the gas fraction of the system gas flow, the flow rate of the system gas flow, the gas fraction of the combined gas outlet flow, and the expiratory gas flow parameters.

[0042] Optionally, one of the flow rate and the gas proportion varies over time.

[0043] Optionally, the flow rates or gas ratios of the system gas streams are varied.

[0044] Optionally, the flow rate varies at a frequency higher than the breathing frequency.

[0045] Optionally, the expiratory gas flow parameter is a gas fraction of the expiratory gas flow.

[0046] Optionally, determining a volumetric percentage of system gas flow through the mouth and / or nose includes determining a volumetric percentage of system gas flow through the mouth.

[0047] Optionally, the volume fraction of system gas flow through the port is a constant k having a value between 0 and 1.

[0048] Optionally, a flow rate Q of the patient's exhaled gas flow. E teeth,

number

[0049] Optionally, when variable flow rates are used for system gas flow and expiratory O2 fraction,

number

[0050] Optionally, when variable flow rates are used for system gas flow and exhaled CO2 fraction,

number

[0051] Optionally, when using variable oxygen fraction for system gas flow and expiratory O2 fraction:

number

[0052] Optionally, the tidal volume is: V Tidal (t) = ∫Q E (t)dt (42) It can be defined as:

[0053] In another aspect, the present invention can be said to include a method of determining respiratory parameters of a patient during exhalation when receiving respiratory assistance, the method comprising providing a system gas flow having a flow rate and gas proportions to the patient, measuring parameters of gases present in a combined gas output stream from the patient, determining an expiratory gas flow rate using one or more of the gas proportions of the system gas flow, the flow rate of the system gas flow, gas parameters of the combined gas output stream, expiratory gas flow parameters, where the expiratory gas flow parameters are determined using the measured parameters of gases present in the combined gas output stream and the time-varying flow rate or gas proportions of the system gas flow, and determining the one or more respiratory parameters from the expiratory gas flow rate.

[0054] Optionally, the method further includes determining a volumetric fraction of system gas flow through the mouth and / or nose, and the expiratory gas flow parameters are determined using the measured parameters of gases present in the combined gas outlet stream, the time-varying flow rates or gas fractions, and the fraction of system gas flow through the mouth and / or nose.

[0055] In another aspect, the invention can be said to include a method of determining respiratory parameters of a patient when receiving respiratory assistance, comprising determining, in any order, whether the patient is inhaling or exhaling and whether the mouth is open or closed, and if the mouth is closed, during inhalation, determining the respiratory parameters in accordance with one or more of the descriptions above, and during exhalation, determining the respiratory parameters in accordance with one or more of the descriptions above, and if the mouth is open, during exhalation, determining the respiratory parameters in accordance with any one of claims 32 to 49, 50 and 51.

[0056] In another aspect, the present invention can be said to comprise a respiratory assistance device for providing respiratory assistance and determining respiratory parameters, the respiratory assistance device comprising a flow generator, one or more sensors or inputs for one or more sensors arranged in the patient's mouth and / or nose, and a controller configured to implement a method according to any of claims 1 to 52.

[0057] Optionally, the apparatus further comprises a humidifier.

[0058] Optionally, the device further comprises or is connected to a non-sealing interface.

[0059] In another aspect, the present invention provides a method for determining respiratory parameters during inhalation of a patient receiving respiratory assistance and with their mouth closed, comprising: providing a non-therapeutic system gas flow to a patient having a flow rate and a gas ratio; Measuring a gas fraction of a combined gas input flow to the patient; The flow rate of the combined gas inlet stream is Gas fraction of the system gas stream; Flow rate of the system gas stream; gas fraction of the combined gas inlet stream; Ambient gas ratio and determining using one or more of determining one or more respiratory parameters from the flow rate of the composite gas input stream; It can be said that the present invention includes a method including the steps of:

[0060] In another aspect, the present invention provides a method for determining respiratory parameters during exhalation of a patient while the patient is receiving respiratory assistance and the patient's mouth is closed, comprising the steps of: presenting to the patient a non-therapeutic system gas flow having a flow rate and a gas rate; Measuring a parameter of gas present in the combined gas output stream from the patient; The flow rate of exhaled gas is gas fraction of the system gas stream; Flow rate of the system gas stream; Composite gas outlet flow parameters, Exhalation gas flow parameters determined using measured parameters of gases present in the composite gas output stream and time-varying flow rates or gas fractions. and determining using one or more of determining one or more respiratory parameters from the flow rate of exhaled gas; It can be said that the present invention includes a method including the steps of:

[0061] In another aspect, the present invention provides a method for determining respiratory parameters of a patient during exhalation while receiving respiratory assistance, the method comprising the steps of: providing a non-therapeutic system gas flow to a patient having a flow rate and a gas ratio; Measuring a parameter of gas present in the combined gas output stream from the patient; determining a proportion of device gas flow through the mouth and / or nose; The expiratory gas flow rate is the oxygen fraction of the system gas stream; Flow rate of the system gas stream; Composite gas outlet flow parameters, volume fraction of gas flow, Exhalation gas flow parameters determined using measured parameters of gases present in the composite gas output stream and time-varying flow rates or gas fractions. and determining using one or more of determining one or more respiratory parameters from the flow rate of exhaled gas; It can be said that the present invention includes a method including the steps of:

[0062] In another aspect, the present invention provides an apparatus for providing respiratory assistance and determining respiratory parameters, comprising: a flow generator for providing a system gas flow to a patient having a flow rate and a gas ratio; one or more sensors or sensor inputs positioned in the patient's mouth and / or nose; a controller, when the patient is inhaling and the mouth is closed, Measuring a gas fraction of a combined gas input flow to the patient; The flow rate of the combined gas inlet stream is Gas fraction of the system gas stream; Flow rate of the system gas stream; gas fraction of the combined gas inlet stream; Ambient gas ratio, and determining using one or more of determining one or more respiratory parameters from the flow rate of the composite gas input stream; A controller configured to It can be said that the present invention includes an apparatus including:

[0063] 1. An apparatus for providing respiratory assistance and determining respiratory parameters, comprising: a flow generator for providing a system gas flow to a patient having a flow rate and a gas ratio; one or more sensors or sensor inputs positioned in the patient's mouth and / or nose; a controller, when the patient is exhaling and the mouth is closed, Measuring a parameter of gas present in the combined gas output stream from the patient; The flow rate of the exhaled gas is gas fraction of the system gas stream; Flow rate of the system gas stream; Combined gas outflow parameters Exhalation gas flow parameters determined using measured parameters of gases present in the composite gas output stream and time-varying flow rates or gas fractions. and determining using one or more of determining one or more respiratory parameters from the flow rate of exhaled gas; A controller configured to The apparatus includes:

[0064] In another aspect, the present invention provides an apparatus for providing respiratory assistance and determining respiratory parameters, comprising: a flow generator for delivering a system gas flow having a flow rate and a gas ratio to the patient; one or more sensors or sensor inputs positioned in the patient's mouth and / or nose; a controller, when the patient is exhaling and the mouth is open, Measuring a parameter of gas present in the combined gas output stream from the patient; determining a proportion of device gas flow through the mouth and / or nose; The flow rate of the exhaled gas is the oxygen fraction of the system gas stream; Flow rate of the system gas stream; Composite gas outlet flow parameters, volume fraction of gas flow, Exhalation gas flow parameters determined using measured parameters of gases present in the composite gas output stream and time-varying flow rates or gas fractions. and determining using one or more of determining one or more respiratory parameters from the flow rate of exhaled gas; A controller configured to It can be said that the present invention includes an apparatus including:

[0065] In another aspect, the present invention provides an apparatus for providing respiratory assistance and determining respiratory parameters, comprising: a flow generator for delivering a system gas flow having a flow rate and a gas ratio to the patient; one or more sensors or sensor inputs positioned in the patient's mouth and / or nose; a controller, when the patient is exhaling, Measuring a parameter of gas present in the combined gas output stream from the patient; The flow rate of the exhaled gas is gas fraction of the system gas stream; Flow rate of the system gas stream; Composite gas outlet flow parameters, Exhalation gas flow parameters determined using measured parameters of gases present in the composite gas output stream and time-varying flow rates or gas fractions. and determining using one or more of determining one or more respiratory parameters from the flow rate of exhaled gas; A controller configured to It can be said that the present invention includes an apparatus including:

[0066] Optionally, the controller is further configured to determine a proportion of system gas flow through the mouth and / or nose, and the expiratory gas flow parameters are determined using the measured parameters of gases present in the combined gas outlet stream, the time-varying flow rates or gas proportions and the proportion of system gas flow through the mouth and / or nose.

[0067] Optionally, the apparatus comprises a humidifier.

[0068] Optionally, the device has or is connected to a non-sealing interface.

[0069] In another aspect, the present invention can be said to include a method of determining respiratory parameters during inhalation of a patient when the patient is receiving respiratory assistance and has his / her mouth closed, comprising providing a system gas flow having a flow rate and gas fraction to the patient, measuring the gas fraction of a combined gas inlet flow to the patient, and determining the flow rate of the combined gas inlet flow using one or more of the system gas flow gas fraction, the system gas flow rate, the combined gas inlet flow gas fraction, and the ambient gas fraction, wherein the system flow rate is a time-varying flow rate that is at least temporarily below the patient inhalation demand flow rate.

[0070] Optionally, when measuring the gas fraction of the combined gas input flow to the patient, the time-varying flow rate is less than the inhalation demand of the patient.

[0071] Optionally, the time-varying flow rate is a fluctuating flow rate.

[0072] Optionally, the flow rate of the combined gas input stream indicates an inhalation demand flow rate.

[0073] In another aspect, the invention may be said to include an apparatus for providing respiratory assistance and determining respiratory parameters, the apparatus including a flow generator, one or more sensors or inputs for one or more sensors positioned in the patient's mouth and / or nose, and a controller configured to implement the method of any of the above paragraphs.

[0074] Optionally, the apparatus further comprises a humidifier.

[0075] Optionally, the device has or is connected to a non-sealing interface.

[0076] In another aspect, the invention can be said to include an apparatus for providing respiratory assistance and determining respiratory parameters, the apparatus including a flow generator, one or more sensors or inputs for the one or more sensors positioned in a patient's mouth and / or nose, a controller configured to control the flow generator to provide a system gas flow to the patient having a time-varying flow rate and gas proportions, receive a target gas input from the target gas sensor, and determine an inhalation demand flow rate based on the target gas input, the time-varying flow rate, and the gas proportions.

[0077] Optionally, the apparatus further comprises a humidifier for humidifying the apparatus gas stream.

[0078] Optionally, the apparatus further includes a non-sealing patient interface.

[0079] Optionally, the target gas input relates to a target gas parameter.

[0080] Optionally, the target gas is oxygen; The target gas parameter is FiO2, and / or The target gas sensor is an O2 fraction sensor.

[0081] Optionally, the system flow rate is a time-varying rate that is at least temporarily below the patient's inhalation demand rate.

[0082] Optionally, the controller receives an input indicative of a patient's breathing phase, indicating an inhalation phase.

[0083] Optionally, the controller calculates the tidal volume based on the inhalation flow rate.

[0084] Reference to a range of numerical values ​​disclosed herein (e.g., 1-10) is intended to incorporate reference to every rational number within that range (e.g., 1, 1.1, 2, 3, 3.9, 4, 5, 6, 6.5, 7, 8, 9, and 10) and also to any rational number range within that range (e.g., 2-8, 1.5-5.5, and 3.1-4.7), and therefore, every subrange of every range explicitly disclosed herein is hereby expressly disclosed. These are merely examples of what is specifically intended, and all possible combinations of numerical values ​​between the lowest and highest values ​​recited are considered to be expressly incorporated in this application as well.

[0085] As used herein, the term "comprising" means "consisting at least in part of." When interpreting each statement containing the term "comprising" herein, other features may be present than those preceded by the term. Related terms such as "comprise" and "comprises" are to be interpreted similarly. Unless the context clearly requires otherwise, throughout this description and claims, the words "comprise", "comprises", and the like are to be interpreted in an inclusive sense, i.e., "including, but not limited to," as opposed to an exclusive or exhaustive sense.

[0086] The phrase "computer-readable medium" should be interpreted to include a single medium or multiple media. Examples of multiple media include centralized or distributed databases and / or associated caches. These multiple media store one or more sets of computer-executable instructions. The phrase "computer-readable medium" should also be interpreted to include any medium capable of storing, encoding or carrying a set of instructions for execution by a processor of a computing device, causing the processor to perform any one or more of the methods described herein. A computer-readable medium may also store, encode or carry data structures used by or associated with those sets of instructions. The phrase "computer-readable medium" includes solid-state memories, optical media, and magnetic media.

[0087] Where references to patents, other external documents or other sources are made herein, this is generally for the purpose of providing a context for discussing features of the present disclosure, and unless specifically noted otherwise, the reference to such external documents is not to be construed as an admission that such documents or such sources are prior art or form part of the general knowledge in the art in any jurisdiction.

[0088] The present invention may also be broadly described as including the parts, elements and features referred to or shown herein, individually or collectively, in any or all combinations of two or more of said parts, elements or features. In the foregoing description, where reference is made to integers or components having known equivalents, those integers are incorporated herein as if set forth individually.

[0089] Those skilled in the art to which the present invention pertains will be able to suggest many modifications in the structure of the present invention as well as widely different embodiments and applications without departing from the scope of the present invention as defined in the appended claims. The disclosures and descriptions herein are purely illustrative and are not intended to be limiting in any sense. Where a specific integer having a known equivalent in the art to which the present invention pertains is described herein, such known equivalent is deemed to be incorporated herein as if individually described. The present invention also contemplates configurations including those described above, of which the following are merely examples.

[0090] definition Patient gas flow: This can be the gas flow entering the patient (during inhalation - patient inhaled gas flow) or the gas flow leaving the patient (during exhalation - patient exhaled gas flow). In the case of inhalation where the inhalation demand is not met, it is the combined gas inflow 17 (also called the patient inhalation gas flow, or the inhalation gas flow, or the total gas inflow; i.e. the gas flow inhaled by the patient) which comprises the system gas flow 11 and the ambient gas flow 16 (entrained air). In some cases, there is no entrainment of ambient air. The combined gas inflow has a gas fraction F m For O2, the gas fraction is FiO2. If the sensor measures O2 fraction during inspiration, the sensor measures the FiO2 / O2 fraction of the combined gas inlet stream (i.e., F m is the FiO2 / O2 fraction). In the case of inhalation where the inhalation demand is met, the ambient gas flow 16 may not be entrained, so it may be the system gas flow 11. In case of suction where the system gas flow 11 exceeds the suction demand, the excess system gas flow (exceeding the suction demand) may escape to the environment, so that it may be part of the system gas flow 11. - Because the system gas flow 11 may vary between meeting, not meeting or exceeding the intake demand at various times, for simplicity, the "combined gas inlet flow" may refer to any of the above situations, but depending on whether the intake demand is met, not met or exceeded, the combined gas flow 17 may include the ambient gas flow 16, may not include the ambient gas flow 16 or may not include all of the system gas flow 11. In the case of exhalation, it is the expiratory gas flow 13 (also called the patient exhaled gas flow; ie the gas flow exhaled by the patient).

[0091] Apparatus gas flow 11: Gas flow from the breathing apparatus.

[0092] Ambient gas flow 16: This is the ambient air entrained in the patient's airways.

[0093] Combined gas inlet flow 17: As mentioned in the definition of patient gas flow, When the intake demand is not met, this is the sum of the system gas flow 11 and the ambient gas flow 16 (entrained air) that is drawn in. When the intake demand is met and there is potentially no entrainment, the combined gas inlet stream 17 is the system gas stream 11 . When the system gas flow exceeds the intake demand, the combined gas input flow 17 is a portion of the system gas flow 11 . The combined gas inlet flow 17 may also be referred to as the "total patient inlet gas flow" or the "total inspired gas flow."

[0094] Exhaled gas flow 13: This is the gas exhaled by the patient, i.e. this is the gas leaving the patient's airways during exhalation.

[0095] Leakage gas flow 12: This includes excess gas flow from the system gas flow 11 that is not inhaled and / or does not enter the patient's lower airways, but escapes to the environment via the mouth and / or nose.

[0096] Combined gas output flow 15 (also called “total gas output flow”): This is the combination of the leakage gas flow 12 and the exhaled gas flow 13 .

[0097] All gas flows may have parameters such as flow rate and / or gas proportions. The proportions may be gas fractions / concentrations and / or gas partial pressures. The parameters may vary over time.

[0098] Reference to an instantaneous parameter, such as an instantaneous flow rate or instantaneous gas fraction, refers to the value of that parameter in the gas flow at a certain instance in time.

[0099] Status parameters: These are parameters that indicate the status of the device, gas flow, patient, etc., such as, but not limited to: a) Mouth state, which can be a binary value of open / closed, or some parameter indicating the ratio (e.g., volume fraction) of gas flow from the system gas flow exiting the mouth relative to the nose. For example, k, b) The flow rate of gas from the breathing apparatus, e.g., Q O , c) The gas fraction (including equivalent gas fraction) of the gas flow from the breathing apparatus, e.g., O2 fraction, but any other gas fraction if appropriate, e.g., N2 or tracer gas F O , but may be any other gas proportion if appropriate, for example N2 or a tracer gas. d) The gas fraction of the gas stream flowing to or from the patient (depending on whether it is measured on inspiration or expiration). For example, the O2 fraction F m , but may be any other gas proportion if appropriate, e.g. CO2, N2 or a tracer gas. e) The gas fraction of the patient's expiratory gas flow. E can be any gas proportion, e.g. O2, CO2, N2 or a tracer gas, where appropriate. f) Gas fraction and flow rate of entrained (ambient) gas. Q ent , F ent (F, used interchangeably herein entrained (Note that it may also be referred to as the gas mixture ratio), but may be any gas ratio, e.g., O2, CO2, N2, or a tracer gas, where appropriate. g) Patient gas flow rate (this can be both a state parameter and a respiratory parameter) that is less than or equal to: a. Flow rate Q of the expiratory gas flow 13 (i.e., the gas flow exhaled by the patient) E and / or b. The flow rate Q of the combined gas inlet flow 17 (i.e., the combined gas flow inhaled by the patient) tot Q TOT Note that also indicates the inhalation flow demand of the patient.

[0100] In the above, the gas fraction may be O2, CO2 or other gas fraction. Gas partial pressure may also be used instead of gas fraction, and will be understood by those skilled in the art to be interchangeable throughout this specification, i.e., references to gas fraction may be references to gas partial pressure.

[0101] Respiratory parameters: These are parameters that indicate the state of respiration, such as but not limited to: - Tidal volume: the volume of air that enters and leaves the lungs with each respiratory cycle, usually measured in ml. - Minute ventilation: the volume of air breathed per minute, usually measured in liters. - Respiratory rate: the pace at which breathing occurs, usually measured in breaths per minute. - Apnea: cessation of breathing that may be temporary. - Airway patency. - Peak flow.

[0102] The state parameters are used to determine the respiratory parameters. There may be crossover between the state parameters and the respiratory parameters.

[0103] As used herein, references to "exhalation" may be used interchangeably with "exhalation."

[0104] As used herein, references to a "proportion" in relation to a gas refer to any relative measure of a constituent gas component in a total gas that includes two or more constituent gas components. For example, the proportion may include: - volume fraction, - fraction, - volume concentration, - concentration, - molar ratio, - Pressure division.

[0105] The measured proportion may be a parameter measured by the sensor used, whether it be a concentration, fraction, partial pressure or other. The determined proportion may be a parameter desired by the user and / or a parameter processed by a component of the respiratory system or a parameter related to the respiratory system.

[0106] In this specification, references to "concentration" may also be referred to as "fraction" and may be expressed as a percentage on a volumetric basis of the gas of interest relative to the volume of the constituent gases in the total gas stream of interest, whether the expiratory gas stream, the system stream, or any other stream. However, the parameters may be on other scales and the gases may be other, and these are merely examples.

[0107] The gas associated with the gas parameter to be determined may be, but is not limited to, oxygen (O2), carbon dioxide (CO2), nitrogen (N), helium (He), or sevoflurane. Where a particular gas is referred to herein, it will be understood that this is by way of example only and that the description is applicable to any gas, not just the gas referred to.

[0108] As used herein, "high flow" means a gas flow at a higher than normal / normal rate, such as, but not limited to, higher than the normal inhalation rate of a healthy patient. This may be provided by a non-sealing breathing system, for example, with uncontrolled and often substantial leakage at the entrance to the patient's airway due to a non-sealing patient interface, such as a non-sealing prong. It may also have a humidification function to improve patient comfort, compliance and safety. Alternatively or additionally, it may be higher than other threshold flow rates relevant to the situation - for example, if a gas flow is provided to a patient at a rate that satisfies the inhalation demand (e.g., instantaneous inhalation demand or peak inhalation demand - this may be the inhalation demand of a patient receiving respiratory assistance or a representative inhalation demand, such as representative of a patient based on empirical data), that flow rate may be considered a "high flow" because it is higher than the nominal flow rate that may otherwise be provided. Thus, a "high flow" is context dependent, and what constitutes a "high flow" depends on many factors, such as the health of the patient, the type of treatment / therapy / assistance provided, the nature of the patient (big, small, adult child), etc. One skilled in the art knows what constitutes a "high flow" from the context. It is an order of magnitude of flow rate beyond that which could be provided otherwise.

[0109] However, without being limited thereto, some indicator values ​​of high flow rate may be as follows: - In some configurations, delivery of gas to the patient at a flow rate of about five or about ten liters per minute (5 or 10 LPM or L / min) or greater. - In some configurations, delivery of gas to the patient at a flow rate of about 5 or 10 LPM to about 150 LPM, or about 15 LPM to about 95 LPM, or about 20 LPM to about 90 LPM, or about 25 LPM to about 85 LPM, or about 30 LPM to about 80 LPM, or about 35 LPM to about 75 LPM, or about 40 LPM to about 70 LPM, or about 45 LPM to about 65 LPM, or about 50 LPM to about 60 LPM. For example, according to various embodiments and configurations thereof described herein, the flow rate of gas delivered or provided through the system or from a flow source to an interface can 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 useful ranges can be selected to 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).

[0110] At "high flow", the gas delivered is selected depending on the intended use, e.g., treatment / therapy / assistance. The gas delivered may include a percentage of oxygen. In some configurations, the percentage of oxygen in the gas delivered may be about 15% to about 100%, about 20% to about 100%, or about 21% 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%.

[0111] In some embodiments, the delivered gas may include a percentage of carbon dioxide. In some configurations, the percentage of carbon dioxide in the delivered gas may be greater than 0%, between about 0.3% and about 100%, between about 1% and about 100%, between about 5% and about 100%, between about 10% and about 100%, between about 20% and about 100%, between about 30% and about 100%, between about 40% and about 100%, between about 50% and about 100%, between about 60% and about 100%, between about 70% and about 100%, between about 80% and about 100%, between about 90% and about 100%, or about 100%.

[0112] The "high flow" flow rate for premature babies / infants / children (whose body weight ranges from about 1 to about 30 kg) may vary. Therapeutic flow rates may be set at 0.4 to 0.8 L / min / kg, with a minimum of about 0.5 L / min and a maximum of about 70 L / min. For patients weighing less than 2 kg, the maximum flow is set at 8 L / min.

[0113] The variable flow rate is set at 0.05-2 L / min / kg, with a preferred range being 0.1-1 L / min / kg, and another preferred range being 0.2-0.8 L / min / kg.

[0114] Therapeutic flow may be time-varying (e.g., fluctuating) - that is, the therapeutic flow may have a flow component that varies (e.g., fluctuates) over time. This time-varying flow may be useful for respiratory assistance.

[0115] It should be noted that the embodiments herein also have a signature flow rate that may vary (e.g., fluctuate) over time and be added to the therapeutic flow rate. Thus, when a therapeutic time-varying flow rate is used, the gas flow rate from the device has a therapeutic time-varying gas flow rate component (portion) and a time-varying signature flow rate component (portion). The therapeutic time-varying flow rate has a different purpose than the time-varying signature flow rate and may be of a different frequency and / or amplitude (although they may overlap or be the same). The signature flow rate may be lower, the same or higher than the therapeutic flow rate. The frequency of the signature flow rate may be lower, the same or higher than the frequency of the therapeutic flow rate (if time-varying). In some embodiments, the signature flow rate has a higher frequency than the therapeutic flow rate. The therapeutic (constant or time-varying) flow rate provides respiratory support, airway management, oxygenation, etc., whereas the time-varying signature flow rate aids in the determination of gas parameters. Time-varying signature flow rates are discussed in more detail below. Throughout this specification, unless otherwise noted, the focus will be on time-varying signature flow rates, but this does not exclude the possibility that therapeutic time-varying flow rates may also exist for therapeutic reasons.

[0116] As an example, the signature flow rate may be stepped between a first flow rate and a second flow rate, one or both of which may fall in the range of approximately 0 LPM to 70 LPM. The maximum signature flow rate may be a therapeutic flow rate. The signature flow rate may be combined (e.g., added) with the therapeutic flow rate or may form part or all of the therapeutic flow rate, i.e., the therapeutic flow rate itself may be a signature flow rate. In some embodiments, the signature flow rate may be related to the therapeutic flow rate as a percentage. For example, a time-varying signature flow rate (adult) may be in the following range: - from about 0% to about 200% of therapeutic flow rate; - Approximately 0% to 100% of therapeutic flow rate; - Approximately 100% to 200% of therapeutic flow, or - Approximately 50% to 150% of therapeutic flow rate and / or in the following range: - Approx. 0~140LPM, - Approx. 0~70LPM, - Approx. 70~140LPM, - Approximately 40 to 100 LPM, or - Approx. 20~60LPM is located.

[0117] Note also that these are not limiting flows, and signature flows can be negative, but when combined with therapeutic flows can result in a positive total flow.

[0118] High flow rates have been found to be effective in enhancing oxygenation of a patient and / or reducing the work of breathing by meeting or exceeding the patient's normal parenchymal inhalation flow rate. Additionally, high flow rates may create a flushing effect in the nasopharynx such that the anatomical dead space of the upper airway is washed out by the high inlet gas flow. This creates a reservoir of fresh gas available with each breath while minimizing rebreathing of carbon dioxide, nitrogen, etc.

[0119] Embodiments are described with reference to the following drawings: [Brief description of the drawings]

[0120] [Figure 1A] The system gas flow provision and resulting patient and system gas flows, flows and gas fractions are shown. [Figure 1B] 1 shows a diagram of a general embodiment of a respiratory assistance device. [Diagram 2] 1 shows a flow diagram of an overview of a method for determining respiratory parameters. [Diagram 3] 4A-4D show flow diagrams of different examples of methods for determining respiratory parameters. [Figure 4] 4A-4D show flow diagrams of different examples of methods for determining respiratory parameters. [Diagram 5] 4A-4D show flow diagrams of different examples of methods for determining respiratory parameters. [Figure 6] 1 shows a flow diagram of a composite method for determining respiratory parameters. [Figure 7] 1 shows a flow diagram of a particular example of a composite method for determining respiratory parameters. [Figure 8] 1 illustrates one embodiment of an apparatus for implementing one or more of the methods for providing respiratory assistance and determining respiratory parameters. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0121] 1. Overview The present embodiments relate to methods and / or apparatus for determining one or more respiratory parameters of a patient receiving respiratory assistance, including but not limited to: - Patient gas flow rate - Tidal volume - Minute ventilation - Tidal volume can be determined for each breath within the minute in which minute ventilation is calculated. - Respiratory rate - for example peak-to-peak detection based on calculated tidal volume / flow, e.g. revolutions per minute. Respiratory rate can also be measured by the zero-crossing method (instead of peak). - Apnea - When the patient is not breathing, there may be no change in the measured gas concentration due to contribution or entrainment from the patient. Thus, in the case of apnea, the sensor may always measure only the delivered gas flow. - Airway Patency - Determination of airway patency. One technique is to monitor flow and / or oxygen fluctuations at the mouth from a high flow system. If this can be confirmed, -High flow is in the right position, · Nasal passages are open can be recognized. If the fluctuations do not match those given by the nose (i.e. the fluctuations are modulated), we can conclude that: The patient is breathing, and · The lower airway is open. This can be combined with measurements of FeCO2 to determine: The patient is breathing, and · The lower airway is open. - Peak flow.

[0122] With reference to FIGS. 1A, 1B and 2, in a situation where a patient receives respiratory assistance from a breathing apparatus in the form of a gas flow having a flow rate and an oxygen fraction (one or both of which may be constant (i.e., a set flow rate and / or O2 fraction) or may vary), the method (FIG. 2) and / or the apparatus (FIGS. 1A, 1B) determines one or more of the respiratory parameters using a combination of the following information (state parameters): a) Some parameter indicating the state of the mouth (can be binary open / closed) or the proportion (eg, volume fraction) of gas flow from the system gas flow exiting the mouth relative to the nose, for example k. b) The flow rate of gas from the breathing apparatus, e.g., Q O . c) The gas fraction (including equivalent gas fraction) of the gas flow from the breathing apparatus, for example the O2 fraction, but which may be other gas fractions where appropriate, for example N2 or tracer gas F O , but may be other gas proportions if appropriate, e.g. N2 or a tracer gas. d) The gas fraction of the gas flow entering or leaving the patient (depending on whether it is measured in the inhaled or exhaled breath). For example, the O2 fraction F m , but may be other gas proportions where appropriate, e.g. CO2, N2 or a tracer gas. e) The gas fraction of the patient's expiratory gas flow. E can be any gas proportion where appropriate, e.g. O2, CO2, N2 or a tracer gas. f) Gas fraction and flow rate of entrained (ambient) gas. Q ent , F ent (F, used interchangeably herein entrained (Note that it may also be referred to as the gas mixture ratio), but may be any gas ratio where appropriate, e.g. O2, CO2, N2 or a tracer gas. g) Patient gas flow rate (this can be a respiratory parameter as well as a state parameter): a. Flow rate Q of the expiratory gas flow 13 (i.e., the gas flow exhaled by the patient) E and / or b. The flow rate Q of the combined gas inlet flow 17 (i.e., the combined gas flow inhaled by the patient) tot Q TOT Note that also indicates the inhalation flow demand of the patient.

[0123] In the above, the gas fractions may be O2, CO2, N2 or other gas fractions (or more generally gas proportions, where proportion is understood to be equivalent to fractions). For example, partial pressures may be used instead of gas fractions, and this will be understood by those skilled in the art as being interchangeable throughout this specification.

[0124] The above may be known, measured, calculated from one or more of the other state parameters, or otherwise determined.

[0125] In general terms (see FIG. 2), in one example, state parameter g) (patient gas flow rate - either the flow rate of gas exhaled by the patient or the flow rate of gas inhaled by the patient) is calculated from a combination of one or more state parameters a)-f). The patient gas flow rate (Q TOT Or Q E , or Q) is integrated over one cycle of inspiration or expiration to obtain the tidal volume (respiratory parameter). The flow rate of the patient gas stream can be not only a state parameter but also a result (i.e., respiratory parameter) in itself. In that case, a further respiratory parameter is Q E / Q TOT , but rather they are the required respiratory parameters.

[0126] More generally, the method is shown in Figure 2, in which a gas flow from a respiratory device is provided to a patient at a flow rate and oxygen fraction (or other gas fraction), one or both of which may vary over time (step 21). One or more state parameters are known, measured or calculated or otherwise determined (step 22). The flow rate of the patient gas flow for the patient is determined from the state parameters (step 23) and then one of the respiratory parameters is calculated (step 24).

[0127] An overview of the implementation of the method in a device will now be described with reference to Figures 1A and 1B. By way of example, a high flow breathing device 10 will be described, for example with reference to Figures 1A and 1B. It should be noted that the high flow breathing device is used only as an example and the embodiments herein may function with low flow or any other type of suitable breathing device. References herein to a high flow breathing device and associated parameters are exemplary and should not be considered limiting as to what breathing assistance the embodiments may be used with. In general terms, the device includes a main housing 10 including a flow generator 50, which may be in the form of a motor / impeller arrangement (or alternatively other flow / modulator sources and / or valves), an optional humidifier 52, a controller 19, and a user I / O interface 54 (e.g., including a display and input devices such as buttons, touch screens, etc.). The device may include one or more communication modules 59 that may be either wired, wireless, or a combination thereof, or that allow data communication or connection with one or more external devices or servers via a data or communication link or data network. For example, in one configuration, the device 10 may include a wireless data transmitter and / or receiver or transceiver 59 to enable the controller 19 to wirelessly receive data signals from the operational sensors and / or control various components of the system 10. The controller 19 is configured or programmed to control the components of the device, including operating the flow generator to generate a flow of gas (gas flow) for delivery to the patient, operating a humidifier (if present) to humidify and / or heat the generated gas flow, receiving user input from a user interface for reconfiguration of the device and / or user-defined operation, outputting information to a user (e.g., on a display), and transmitting and / or receiving information to a remote device 69 via the communication module 59. A user may be a patient, a medical professional, or any other person interested in using the device.A patient breathing conduit 58 is coupled to a gas flow output within the housing of the breathing apparatus and is coupled to a (e.g. non-sealed) patient interface 51, such as a (e.g. non-sealed) nasal cannula having a manifold and nasal prongs. The patient breathing conduit may have a heater wire 5 for heating the gas flow passing to the patient.

[0128] High flow rates can be used as a means of enhancing 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 airways. High flow rates can be particularly useful before, during, or after a medical procedure.

[0129] Further benefits of high gas flows may include that high gas flows increase pressure within the patient's airways, thereby providing pressure support that opens the airways, trachea, lungs / alveoli, and bronchi. The opening of these structures promotes oxygenation and aids to some extent in the removal of CO2.

[0130] The increased pressure may also prevent structures such as the larynx from obscuring the view of the vocal cords during intubation. When humidified, high gas flow may also prevent drying of the airway, mitigate damage to the mucosa, and reduce the risk of laryngospasm and the risks associated with a dry airway, such as nosebleeds, aspiration (as a result of nosebleeds), airway obstruction, swelling, and bleeding. Another advantage of high gas flow is the removal of smoke generated in the airway during surgery. For example, smoke may be generated by lasers and / or cauterizing devices.

[0131] 1A, the present embodiment can be used in any suitable situation in which a patient is provided with a gas flow (such as, but not limited to, a high gas flow for high flow therapy) from a respiratory device 10 to provide therapy (respiratory assistance). The device 10 provides a device gas flow 11. The device gas flow 11 has a flow rate Q O This flow rate can be a constant flow rate (does not change over time) or can vary over time depending on the needs of the treatment. The system gas flow has an O2 fraction F O(As an example, fractions are used here for illustrative purposes, although it could be other gas fractions, or more generally gas ratios). The O2 fraction can be constant (does not change over time) or time-varying, as desired. In such a situation, the patient breathes at least a portion of the system gas flow 11 during inhalation. The patient may entrain air as an entrained gas flow 16. The entrained gas flow is determined by the flow rate and the O2 fraction (Q ent , F ent ). The total patient gas inflow (also called the "combined gas inflow" or "total inhalation gas flow") 17 is a combination of the entrained gas flow and the system gas flow 11 (when the inhalation demand is not being met, but as explained above, when the inhalation demand is being met, it may be only the system gas flow 11, or when it exceeds the inhalation demand, it may even be a small portion of the system gas flow 11; from this point on, the distinction will be understood by those skilled in the art even if it is not explicitly stated). When there is no entrainment, the combined gas inflow 17 is the system gas flow 11. The total flow is Q TOT =Q O +Q ent which also indicates the patient's inhalation demand. The combined O2 fraction F m (also called inhaled FiO2).

[0132] The patient is E and O2 fraction F E The exhaled gas stream 13 is exhaled from the exhaled airway 12. This may come from the mouth and / or nose. The exhaled gas stream 13 has constituent gas components such as CO2, O2, nitrogen, helium, etc. The exhaled gas stream 13 may also contain an anesthetic agent such as sevoflurane.

[0133] There is also a "leakage gas flow" 12, which comprises excess gas flow from the system gas flow 11 that is not inhaled and / or does not enter the patient's lower airways, but escapes to the environment via the mouth and / or nose.

[0134] The “combined gas output flow” (also called the “total gas output flow”) 15 is the combination of the leakage gas flow 12 and the exhaled gas flow 13 .

[0135] The exhaled gas flow 13, the leaking gas flow 12 and the resulting combined gas flow 15 can exit through the mouth, the nose or the mouth and the nose. There are several scenarios: 1) the patient's mouth is open and the exhaled gas flow, the leaking gas flow and the resulting combined gas flow exit primarily (a term that may include / inclusive of entirely) through the patient's mouth; 2) the patient's mouth is open and the exhaled gas flow, the leaking gas flow and the resulting combined gas flow exit both through the patient's mouth and nose; 3) the patient's mouth is closed and the exhaled gas flow, the leaking gas flow and the resulting combined gas flow exit through the patient's nose.

[0136] If the combined gas output flow 15 is measured, this can be done with a suitable sensor. The sensor can be located anywhere suitable, but its sensing portion (sensor input) can be positioned to measure either the flow from the mouth, the flow from the nose, or the flow from the nose and the mouth. Various implementations of the sensor are possible, and the sensor can be located anywhere suitable, but when referring to a location relative to the mouth and / or nose, it is an indication of where the sensing portion (sensing input) is positioned. For example, in a sensor with a sampling conduit, the sampling conduit (sensing portion) is near the mouth and / or nose, even if the sensor or part of the sensor is located elsewhere. Other implementations of the sensor will be known to those skilled in the art. If the sensor is measuring exclusively the flow from the mouth or nose, the sensor may not be measuring the entire combined gas output flow, because part can also exit from other orifices (e.g. the other of the nose or mouth depending on which one the sensor is not measuring). In this case, the sensor measurement still obtains a measurement of the combined gas output flow that is suitable and / or sufficient to determine the gas parameters of the exhaled gas flow.

[0137] The present embodiments utilize the methods and / or apparatus of PCT / IB2021 / 052062, U.S. Patent Application No. 62 / 989081 (from which PCT / IB2021 / 052062 claims priority), PCT / IB2021 / 051587, and U.S. Patent Application No. 62 / 982298 (from which PCT / IB2021 / 051587 claims priority), all of which are incorporated by reference in their entireties herein.

[0138] Three exemplary, but non-limiting, embodiments of the method will now be described in more detail with reference to Figures 3 to 6. Such embodiments can be implemented, for example, in the apparatus of Figures 1B or 8.

[0139] 3, in one example, tidal volume and / or other respiratory parameters may be determined from a closed-mouth patient during the inspiratory portion of the patient's gas flow, as seen in steps 300-305. m is measured / determined, Q O , F O is known, and Q TOT may be calculated, from which the tidal volume and / or any respiratory values ​​may be calculated or otherwise determined.

[0140] 4, in one example, tidal volume and / or other respiratory parameters may be determined from a closed-mouth patient during the expiratory portion of the patient's gas flow, as seen in steps 400-406. E , F m is measured / determined, Q O , F O is known, and Q E may be calculated, from which the tidal volume and / or any respiratory values ​​may be calculated or otherwise determined.

[0141] 5, in one example, tidal volume and / or other respiratory parameters may be determined from an open-mouthed patient during the expiratory portion of the patient's gas flow, as seen in steps 400-406, 500. E , Fm is measured / determined, Q O , F O is known, and Q E may be calculated, from which the tidal volume and / or any respiratory values ​​may be calculated or otherwise determined.

[0142] In any of the above, the patient inhalation gas flow rate (Q TOT ) or patient expiratory gas flow rate (Q E ) may itself be the respiratory parameter output and no further calculations may be made regarding tidal volume or other respiratory parameters, i.e. steps 305, 405, 505 may be omitted.

[0143] FIG. 6 illustrates how the three embodiments can be used together in a system. In each case, the method uses some combination of state parameters according to FIGS. 3-5 and the more detailed description above and below to estimate the patient inhalation gas flow rate (Q TOT ) or patient exhaled gas flow rate (Q E ) and may further include using the patient inhalation gas flow rate or the patient exhalation gas flow rate to determine one or more additional respiratory parameters. Figure 7 shows an example of a combined method, which is an example of the more general method of Figure 6 (other examples are possible).

[0144] The embodiment will now be described in more detail with reference to Figures 3-7.

[0145] 2. Determination of the combined gas inflow flow rate and / or other respiratory parameters during the inhalation cycle when the patient's mouth is closed. 3, in one embodiment, a patient's inhalation gas flow rate is determined from a combination of state parameters, and optionally one or more of the respiratory parameters are derived therefrom. The method of this embodiment is performed when the patient's mouth is closed while the patient is inhaling. Whether the patient's mouth is closed can be determined in any suitable manner by a person and / or a device. For example, a person may look at the patient and see that the mouth is closed, and input the mouth closed state into the device.

[0146] A closed mouth is a special case of the constant k=0. k is a value between 0 and 1 and is the rate at which the delivered gas (the device gas flow 11) passes through the mouth (e.g., in one example, when k=0, the device gas flow 11 does not exit the mouth). When the mouth is closed, as in this case, the device gas flow 11 does not pass through the mouth, so k=0. In this case, the mouth is always closed, so k is a constant. In the more general case, k can change over time because the "openness" of the mouth changes over time. In this case, the later embodiment regarding the mouth and nose being open is relevant, and k can be dependent on t, i.e., k(t). In this case, k is a time-varying constant, mathematically a constant, but not a constant value because it changes over time. Note that even in the situation where the mouth is open, k may not be time-dependent, so both time-dependent and time-independent k are possible. When the mouth is closed (k=0), the formula is F measured through the nose-sensing sensor 14. m Based on.

[0147] The constant k is further described in relation to the unclosed embodiment.

[0148] The method may be carried out in an apparatus such as that described below. A detailed derivation of the equations used in the method is provided in the Derivation section below.

[0149] In summary, the flow rate Q of the patient's combined gas inlet flow (patient inhalation) 17 TOT teeth,

number

[0150] It should be noted that references herein to O2 when referring to the above parameters may alternatively be replaced with CO2, N2 or other tracer gases. More generally, any gas ratio may be used.

[0151] Q TOT Once calculated, Q TOT can be used to determine tidal volume (a respiratory parameter) by integrating over the inhalation cycle. Tidal volume is given by: V Tidal (t) = ∫Q Tot (t)dt (38) It can be defined as:

[0152] Further respiratory parameters can be determined as follows. - Minute ventilation - Breathing rate - Apnea - Airway patency - Peak flow

[0153] The method is described in further detail with reference to the flow chart of FIG.

[0154] Q O , F Oare known operating parameters of the device / device gas stream 11 (step 304). entrained is the gas fraction of oxygen in the ambient air, which is known - about 21%. That is, from Eq. 37, Q TOT To determine this, the FiO2 must be determined.

[0155] A system gas flow 11 is generated and delivered by the respiratory apparatus 10 to the patient via the patient interface 51 (step 300). During the patient's inhalation cycle (step 301), F m (in this case the FiO2 present during inhalation) is measured (step 302) by a suitable sensor 14, for example an oxygen fraction sensor 14. The sensor 14 may be located adjacent to and / or within the patient's nose. When the mouth is open an oral sensor is used, whereas when the mouth is closed (in this example) a nasal sensor is used, as will be further described below in relation to embodiments. For example, the oxygen fraction sensor 14 may be provided in a cannula 51 providing the system gas flow 11. The oxygen sensor measures the oxygen fraction F of the patient gas flow 17 entering the patient's airway (inhaled). m The measurements can be taken at time intervals (e.g., continuously or at least periodically / discretely) over time during the inhalation cycle. For example, the measurements can be m (t), F m (t+△t), etc. (i.e., at time t and any time thereafter). This allows the known (step 304) Q O , F O , F entrained , and a number of measurements are provided (step 302) with corresponding Q TOT (t), Q TOT (t+△t) etc. can be obtained (step 303). TOT A time-dependent series of (t) is obtained, which can be integrated to obtain the tidal volume using Equation 38 (step 305). The respiratory rate is also Q TOT(t), and the minute volume can be determined from knowledge of the respiratory rate and tidal volume.

[0156] Using Equation 37, Q TOT In order to obtain (step 303), entrainment of air gas flow by the patient is required when FiO2 is determined, and therefore, when FiO2 is measured, the flow rate of the device gas flow 11 may preferably be less than the inhalation demand of the patient (in this specification, inhalation demand may refer to instantaneous inhalation demand and / or peak inhalation demand, unless otherwise specified). This means that the device gas flow 11 is at least temporarily less than the inhalation demand of the patient (e.g., instantaneous inhalation demand or peak inhalation demand). For example, for at least a part of the inhalation, the flow rate is less than the inhalation demand. For example, for a part of the inhalation, the device flow 11 is a first flow rate that is equal to or greater than the inhalation demand, and for a part of the inhalation, the device gas flow 11 is a second or subsequent flow rate that is less than the inhalation demand, respectively. There may also be cases where the device flow 11 is permanently less than the inhalation demand (flow rate) of the patient, which would be undesirable because the device gas flow 11 is not therapeutic / does not provide the desired respiratory support. Thus, in one option, the flow rate of the system gas flow 11 is temporarily reduced below the inhalation demand when the FiO2 measurement is taken. In one option, the flow rate of the system gas flow can be varied in any suitable manner in step 300. For example, it can be varied to be periodically below the inhalation demand when the measurement is taken. Preferably, the time during which the system gas flow is below the inhalation demand is kept as short as possible to minimize interruption of respiratory support. The time-varying flow rate / gas fraction can be at a frequency higher than the patient's breathing frequency. The time-varying flow rate / gas fraction can be at a frequency lower than the patient's breathing frequency. Q TOT indicates the required intake flow rate, so Q TOT The inhalation demand can be determined by determining, which assists in delivering a system gas flow rate less than the inhalation demand, if necessary. That is, the inhalation demand flow rate can be determined based on the target gas input, the time-varying flow rate, and the gas ratio.

[0157] Other respiratory parameters may alternatively or additionally be determined as described above.

[0158] 3. Determination of expiratory gas flow and / or respiratory parameters during the exhalation cycle when the patient's mouth is closed With reference to FIG. 4, in one embodiment, the patient's exhalation flow rate is determined from a combination of state parameters, and optionally one or more of the respiratory parameters are derived therefrom. The method of this embodiment is performed when the patient's mouth is closed during exhalation. Whether the patient's mouth is closed can be determined in any suitable manner. For example, a person may look at the patient and see that the mouth is closed, and input the mouth closed state into the device. Other options are possible. A closed mouth is a special case of the constant k=0, as described above. In this case, k is constant, since the mouth is always closed. In a more general case, k may change over time, since the "openness" of the mouth changes over time. In this case, the later embodiment regarding mouth and nose opening is relevant, and k may depend on t, i.e., k(t). In this case, k is a time-varying constant, mathematically constant, but not a constant value, since it changes over time. Note that even in the mouth open situation, k may not be time dependent, so both time-dependent and time-independent k are possible. The constant k is further described in relation to the unclosed embodiment.

[0159] The method may be carried out in an apparatus such as that described below. A detailed derivation of the equations used in the method is provided in the Derivation section below.

[0160] This embodiment utilizes a system gas stream 11 having a time-varying flow rate or a time-varying oxygen fraction. More generally, another gas (e.g., CO2, N2, etc.) could provide a time-varying gas fraction marker in system gas stream 11, but O2 is used here as an exemplary option. The gas fraction could more generally be any gas ratio. Options for time-varying flow rates and time-varying oxygen fractions are described below.

[0161] 3.1 Determination of respiratory parameters using time-varying flow rate or O2 fraction of system gas stream In summary, the flow rate Q of the patient's expiratory gas flow (patient exhalation) 13 E teeth,

number

[0162] Q E Once calculated, Q E can be used to determine tidal volume (a respiratory parameter) by integrating over the exhalation cycle. Tidal volume is given by: V Tidal (t) = ∫Q E(t)dt (42) It can be defined as:

[0163] Further respiratory parameters can be determined as follows. - Minute ventilation - Breathing rate - Apnea - Airway patency

[0164] The method is described in further detail with reference to the flow chart of FIG.

[0165] Q O , F O Q is a known operating parameter of the device / device gas flow 11 (step 404). That is, Q E To determine F m and F E It is necessary to determine this. This will be explained.

[0166] 3.1.1 F m Decision A system gas flow 11 is generated and provided by the respiratory apparatus 10 to the patient via a patient interface (step 400).

[0167] During the patient's exhalation cycle (step 401), m is measured (step 402) by a suitable sensor 14, for example an oxygen or CO2 fraction sensor. The sensor may be positioned to sense near and / or within the patient's nose. For example, the oxygen fraction sensor 14 may be provided in the cannula 51 that provides the system gas flow 11. The oxygen sensor 14 measures the oxygen fraction of the combined gas flow 17 exiting (exhaled) from the patient. Measurements may be taken at time intervals over time (e.g., continuously or at least periodically / discretely) during the exhalation cycle. For example, measurements may be taken of F m (t), F m (t+△t), etc. This allows the known (step 404) Q O , F OA number of measurements are provided (step 402) along with the result (F E are also required, see below), and the corresponding Q E The values ​​of (t), (t+Δt), etc. are obtained (step 405).

[0168] 3.1.2 F E Decision During the patient's exhalation cycle (step 401), E is also determined (step 403) as follows. A detailed explanation and derivation are given in the Derivation section. F E The decisions are described in PCT / IB2021 / 052062 and U.S. Patent Application No. 62 / 989081, from which PCT / IB2021 / 052062 claims priority, both of which are incorporated herein in their entireties. E is the CO2 fraction (F ECO2 ) or O2 fraction (F EO2 ), both of which are included herein and described in the incorporated applications.

[0169] The present embodiment relates to a non-sealed breathing apparatus 10 that provides a system gas flow 11 to a patient. A non-sealed apparatus means that a portion of the system gas flow 11 does not enter the lower airways of the patient, but rather "leaks" to the environment (leakage gas flow 12). This results in a "combined gas output flow" (also called "total gas output flow") that is the combination of the leakage gas flow 12 and the exhaled gas flow 13. That is, F m When measuring the gas fraction F (i.e., the fraction of oxygen or CO2 or other gas from the patient), it is the gas fraction of the combined gas stream 15 that is measured, not the gas fraction F of the expiratory gas stream 13. E The gas fraction of the expiratory gas flow F ENo. 62 / 989081 may also be used to determine the desired gas component parameter F in the actual exhaled gas flow 13 from the patient, by measuring the gas component parameter in the combined gas outlet flow 15 at or near the patient ("proximal"), accounting for the effect of the leakage gas flow 12 on the measured parameter, and adjusting the measured value accordingly (or using the measured value and other information) to determine the desired gas component parameter F in the actual exhaled gas flow 13 from the patient. E The present invention provides an apparatus and method for determining the amount of CO2, O2, and / or O2 present in the system. The apparatus gas stream can be altered using the signature to aid in determining the parameter. Note: The composite gas output stream 15 may also contain other gases (in addition to CO2 and O2), such as gases present in ambient air. The described embodiment will function in the presence of such additional gases.

[0170] Next, F E Determining the gas parameters of the actual exhaled gas flow 13 will be described. The respiratory device 10 may include a flow source capable of providing a system gas flow to the patient. The device is further described below with reference to FIG. 8. The device 10 provides a time-varying system gas flow such that a time-varying parameter of the system gas flow varies over time. This provides a signature that can be used to determine the gas parameters of the actual exhaled gas flow 13. As possible examples, the time-varying parameter of the system gas flow may be a flow rate or a gas ratio, such as a gas fraction (e.g., O2 fraction) and / or a gas partial pressure (e.g., O2 partial pressure). The time-varying flow rate / gas ratio may be at a higher frequency than the patient's breathing frequency. The time-varying flow rate / gas ratio may be at a lower frequency than the patient's breathing frequency. In this embodiment, CO2 sensing of the patient is used, but O2, N2 tracer, anaesthetic or other gas sensing may be used instead.

[0171] 3.1.2.1 Using time-varying flow rate F E Ask for In one embodiment, the system gas stream flow rate is varied over time in a suitable manner, as described elsewhere herein.

[0172] Next, F E can be determined using one of the following equations, the derivation of which is described below.

[0173] (General case) Exhaled gas fraction F E The decision includes the following:

number

[0174] Exhaled CO2 fraction F E The determination of the above is based on the following:

number

[0175] F E If it is CO2 that is to be determined, F ECO2 can be called again.

[0176] 3.1.2.2 Using time-varying O2 fraction to determine F E Ask for In one embodiment, the gas fraction (such as the O2 fraction) of the system gas stream is varied over time in a suitable manner, as described elsewhere herein.

[0177] Next, the expiratory O2 fraction F E To determine the following:

number

[0178] F E If it is O2 that is determined, F EO2 can be called again.

[0179] 3.1.3 QE , tidal volume and other respiratory parameters As mentioned above, F m and F E Once Q is determined (measured value and Eq. 16 (for time-varying flow rate) or Eq. 17 (for time-varying oxygen fraction), respectively), Q can be calculated from Eq. 41. E can be obtained (step 405).

[0180] Next, Q E Once calculated, Q is calculated using Equation 42. E can be used to determine tidal volume (a respiratory parameter) by integrating over the inhalation cycle (step 406).

[0181] Other respiratory parameters may alternatively or additionally be determined as described above.

[0182] 4. Determination of the expulsion flow rate and / or state parameters during the expulsion cycle when the patient's mouth is open. Referring to FIG. 5, in one embodiment, the patient's exhaled flow is determined from a combination of state parameters, from which, optionally, one or more of the respiratory parameters are then derived.

[0183] The method of this embodiment is performed while the patient is exhaling and the patient's mouth is somewhat open.

[0184] The method is carried out using an apparatus such as that described below. A detailed derivation of the equations used in the method is provided in the Derivation section below.

[0185] This embodiment utilizes a system gas stream with variable flow rate or variable oxygen fraction. Each option is described separately. Further embodiments are possible in which both flow rate and oxygen fraction are varied. More generally, another gas could provide a time-varying gas fraction marker in system gas stream 11, but O2 is used here as an exemplary option. The gas fraction could more generally be any gas ratio. Options for time-varying flow rate and time-varying oxygen fraction are described separately.

[0186] In summary, the flow rate Q of the patient's expiratory gas flow (patient exhalation) 13 E teeth,

number

[0187] In this case, k is constant. In the more general case, k may change over time as the "openness" of the mouth changes over time. In that case, k is a time-varying constant, mathematically constant, but not a constant value over time since it may change. Note that even in situations where the mouth is open, k may not be time dependent, so there can be both time-dependent and time-independent k. It will be understood that references to k may be k(t) and vice versa, unless the context dictates otherwise.

[0188] When using variable flow rates for the system gas flow (expiratory O2 fraction),

number

[0189] When using variable flow rates for the system gas flow (expiratory CO2 fraction),

number

number

[0190] Equation 30 is similar to Equation 41, except that Equation 30 has a k(t) term, whereas Equation 41 has a (1-k(t)) term. This is because in Equation 41, the mouth is closed, so sensor 14 senses at the nose. In Equation 30, the mouth is open, so sensor 14 senses at the mouth.

[0191] Q E Once calculated, Q E can be used to determine tidal volume (a respiratory parameter) by integrating over the inhalation cycle. Tidal volume is given by: V Tidal (t) = ∫Q E (t)dt (42) It can be defined as:

[0192] Further respiratory parameters can be determined as follows. - Minute ventilation - Breathing rate - Apnea - Airway patency

[0193] The method is described in further detail with reference to the flow chart of FIG.

[0194] Q O , F O Q is a known operating parameter of the device / device gas flow 11 (step 404). That is, Q E To determine F m , F E and k must be determined. A system gas flow 11 is generated and provided by the respiratory apparatus 10 to the patient via the patient interface 51 (step 400). During the exhalation cycle (step 401), F m and F E can be obtained according to the previous embodiment (steps 402, 403). E (step 405) and tidal volume (or other respiratory parameter) (step 406) can be determined in the same manner as in the previous embodiment (closed mouth, during the exhalation cycle), except now k is also used. The determination of K (step 500) will now be described.

[0195] 4.1 Determination of k or k(t) This involves determining the fraction k, or more generally k(t), of the system gas flow 11 exiting the port.

[0196] This is a value between 0 and 1 and is the percentage of delivered gas (system gas flow 11) that passes through the mouth. When the mouth is closed, k=0, and when the mouth is open, a percentage k(t) of the system gas flow passes through the mouth and a percentage (1-k(t)) passes through the nose. As noted above, k may or may not change over time, and any reference to k may be k(t) and vice versa.

[0197] When the mouth is closed (k=0), the formula is F measured through the nose-sensing sensor 14. m When the mouth is open (k is between 0 and 1), the formula is F measured at the mouth. m In this context, "at" means near, at, in close proximity to, in the vicinity of, or any other term indicating that the sensing portion / input portion of the sensor is located in a location that allows for suitable measurement of the associated gas flow.

[0198] Although k has been defined relative to the fraction of device gas flow exiting the mouth, it will be understood that a mathematically and / or physically similar constant may be defined relative to the fraction exiting the nose, for example. Such variations will be understood as equivalents by those skilled in the art. Thus, the fraction k may be thought of more generally as the fraction (e.g., volume fraction) of gas flow passing through the mouth and / or nose.

[0199] Determining the fraction k at a particular sensor location can be done in a variety of ways, including: 1. Supply flow through one nostril of the sealed interface and measure the flow (Qm) out the other nostril (this can be done using a flow meter or a pressure sensor upstream of a known pressure plate that creates a known resistance to the surroundings). For example, k=(Qo-Qm) / Qo. 2. Deliver flow through a nasal interface sealed at the nostrils, ensuring that all delivered flow exits the oral cavity. 3. For the special case of k=0 (mouth closed), observe the oxygen trace throughout the entire respiratory cycle. If there is a clear gradient of inhalation and exhalation during high flow, then the mouth is closed (k=0).

[0200] 4.2 Q E , tidal volume and other respiratory parameters F m , F EOnce (measurement and equation 16 or 17, respectively - steps 402, 403) and k (from one of the methods above) (step 500) have been determined as above, Q E can be obtained from Equation 30 (step 405).

[0201] Next, Q E Once calculated, Equation 42 can be used to calculate Q over the delivery cycle. E By integrating, it can be used to determine the tidal volume (a respiratory parameter) (step 406).

[0202] Other respiratory parameters may alternatively or additionally be determined as described above.

[0203] 5. Combined Method In another embodiment, several embodiments may be available depending on the condition of the patient's mouth and / or the need to perform the method during inhalation or exhalation.

[0204] In one embodiment, all the methods described above can be used / implemented with the device 10 described herein, and the method used depends on the state of the patient's mouth and / or the part of the breathing cycle. Figure 6 shows how the methods are combined. In such an embodiment, the method used to determine the breathing parameters is based on whether the patient's mouth is open or closed (step 61) and whether the patient is inhaling or exhaling (breathing phase) (step 60). These states (including breathing phase) can be determined using any suitable method. For example, a CO2 trace, an ECG or a breathing band can be used, these are just a few non-limiting examples. If the mouth is closed (step 62) and the patient is inhaling (step 64), the method of Figure 3 is used (step 67). If the mouth is closed (step 62) and the patient is exhaling (step 64), the method of Figure 4 is used (step 66). If the mouth is open (step 62) and the patient is exhaling (step 63), the method of Figure 5 is used (step 65). Otherwise, if the mouth is open, breathing is monitored until exhalation is detected.Depending on the patient's condition, any one or combination of methods can be used as desired.

[0205] 7 shows a non-limiting example of one possible implementation of the combined method. The device gas flow 11 at the sensor location (whether mouth or nose) is determined, resulting in k (step 70). From this, it can be determined whether the mouth is open or closed.

[0206] If the mouth is closed and k=0, it is determined whether the patient is exhaling or inhaling. If the patient is inhaling and the mouth is closed, path 71 is taken. The gas fraction is measured at the nasal patient sensor 14 (step 71A), in this case the system gas flow Q O 1 is used to measure the FiO2 measured at time t (step 71B). The following FiO2 is calculated using the system gas flow Q O 2 at time (t+Δt) (Step 71C).TOT is determined based on the FiO2 measurements (step 71D), which can be integrated between time points to determine the tidal flow rate. This process can be repeated for subsequent time points (step 75).

[0207] When the patient is exhaling, path 73 or 74 is taken regardless of whether the mouth is open or closed. If the mouth is open, however, k is determined in step 70. Next, the gas fraction is measured (step 72) and the flow or O2 fraction is varied (path 73 or path 74). If oxygen is varied (step 74A), the gas fraction at the nasal and / or oral patient sensors 14 is measured (step 74B), in which case F m CO2 / F m O2 is the device O2 fraction F O2_1 is measured at time t using F m CO2 / F m O2 is the O2 fraction F O2_2 is measured at time (t+Δt) using (step 74C). E is determined based on the determination of FeCO2 / FeO2 (step 74D). This can be integrated between time points to determine the tidal flow rate. This process can be repeated for subsequent time points (step 75).

[0208] When the flow rate is varied (step 73A), the gas fraction at the nasal and / or oral patient sensors 14 is measured (step 73B), in which case FmCO2 / FmO2 is proportional to the flow Q O1 is measured at time t using FmCO2 / FmO2 as a function of flow Q O2 is measured at time (t+Δt) using (Step 73C). E is determined based on the determination of FeCO2 / FeO2 (step 73D). This can be integrated between time points to determine the tidal flow rate. This process can be repeated for subsequent time points (step 75).

[0209] 6. Devices for providing gas flow and determining respiratory parameters An apparatus and method for determining such respiratory parameters will now be described with reference to the apparatus of Figure 8 and with reference to the methods described with reference to Figures 3-7 above. This apparatus may also be used in other embodiments described herein. The apparatus of Figure 8 is a more detailed description of the apparatus of Figure 1B.

[0210] A respiratory device 10 can provide the device gas flow 11 used in the methods described herein. It can also have a sensor 14 for performing various measurements for the methods. Various implementations of the sensor are possible and the sensor can be located anywhere suitable, but when referring to a location relative to the mouth and / or nose, it is an indication of where the sensing portion is positioned. For example, in a sensor with a sampling conduit, the sampling conduit (sensing portion) is near the mouth and / or nose, even if the sensor or part of the sensor is located elsewhere. Other implementations of the sensor will be known to those skilled in the art. A controller of the device can perform one or more parts or all of the methods. Optionally, other external devices can be used instead of or in addition to the respiratory device to perform one or more parts or all of the methods.

[0211] FIG. 8 shows a respiratory device 10 for providing flow therapy or other therapy (respiratory support) to a patient. The device is configured to deliver a time-varying device gas flow 11 and to perform processing to determine desired respiratory parameters (e.g., tidal volume, minute ventilation, respiratory rate, apnea, airway patency, etc.). The device 10 may be an integrated or separate component-based arrangement, as generally shown in the dotted box in FIG. 8. In some configurations, the device may be a modular arrangement of components. Thus, the device may be referred to as a "system", although this term may be used interchangeably and without limitation. In the following, it will be referred to as a device, although this should not be considered limiting. The device may be used for any suitable purpose, including pre-oxygenation during anesthesia procedures, high-flow therapy, ventilation during anesthesia procedures, while treating patients with respiratory distress, treating patients with obstructive sleep apnea, or any other treatment where monitoring of the patient's respiratory behavior is required.

[0212] The apparatus includes a flow source 50 for providing a high flow rate gas 31, such as oxygen or a mixture of oxygen and one or more other gases. Alternatively, the apparatus may also have a connection for coupling to a flow source. Thus, the flow source may be considered to form part of the apparatus or to be separate from the apparatus, depending on the circumstances, or part of the flow source forms part of the apparatus and part of the flow source is located outside the apparatus.

[0213] The flow source may be an in-wall oxygenator, a high-flow breathing device with an oxygen tank 50A, a tank of other gas and / or a blower / flow generator 50B. FIG. 8 shows a flow source 50 with a flow generator 50B with an optional air inlet 50C and an optional connection to an O2 source (such as a tank or O2 generator) 50A via a shutoff valve and / or regulator and / or other gas flow control 50D, but this is only one option. The description from here on can refer to either embodiment. The flow source may be one or a combination of a flow generator, an O2 source, an air source, as described. Although the flow source 50 is shown as part of the device 10, in the case of an external oxygen tank or an in-wall source, it can be considered a separate component, in which case the device has a connection port for connecting to such a flow source. The flow source provides a (preferably high) flow rate of gas that can be delivered to the patient via a delivery conduit and a patient interface 51. Depending on the end use, the patient interface 51 may be an unsealed (also called "non-sealed") interface, such as a nasal interface (cannula) (e.g., when used in high-flow therapy) or a sealed interface, such as a nasal mask, full-face mask, nasal pillows, etc. (e.g., when used in CPAP).

[0214] The time-varying flow rate embodiment can be used with a non-sealing patient interface. The time-varying flow rate gas stream is not channeled or passed to an external cavity of the patient, so it is preferably passed through, for example, a non-sealing nasal cannula. The external cavity may introduce a low pass filter, which may attenuate the signature of the time-varying flow rate. The time-varying fraction embodiment can be used with a sealing or non-sealing patient interface. The patient interface 51 is preferably a non-sealing patient interface, which may help prevent, for example, barotrauma (e.g., tissue damage in the lungs or other organs due to pressure differences relative to the atmosphere). The patient interface may be a nasal interface (cannula) with a manifold and nasal prongs, and / or a face mask, and / or a nasal pillows mask, and / or a nasal mask, and / or a tracheotomy interface, or any other suitable type of patient interface. The flow source may provide, for example, a therapeutic gas flow rate ranging from about 0.5 liters / minute to about 375 liters / minute, or any range therein, or higher or lower limits.

[0215] The time-varying system gas flow may have a time-varying (e.g., fluctuating) flow rate for therapy, and the controller controls the gas flow modulator to provide a time-varying system gas flow for therapy at a fluctuating flow rate of about 375 L / min to about 0 L / min, or preferably about 240 L / min to about 7.5 L / min, or more preferably about 120 L / min to about 15 L / min, and / or the fluctuating flow rate has one or more frequencies of about 0.1 Hz to about 200 Hz, preferably about 0.1 Hz to about 6 Hz, more preferably about 0.5 Hz to about 4 Hz, and even more preferably 0.6 Hz to about 3 Hz. The gas flow modulator may be a flow source (where it may be a flow generator, an O2 source, ambient air, etc., as discussed above) and / or a valve or other device for modulating or otherwise varying a parameter (e.g., flow rate, gas ratio) of the gas flow.

[0216] The variable flow rate can include a therapeutic flow rate component, the therapeutic flow rate being from about 375 liters / minute to about 0 liters / minute, or from about 150 liters / minute to about 0 liters / minute, or preferably from about 120 liters / minute to about 15 liters / minute, or more preferably from about 90 liters / minute to about 30 liters / minute.

[0217] The variable flow rate can include a therapeutic gas flow component, and a constant (eg, bias / base) flow rate component of the therapeutic gas flow is between about 0.5 liters / minute and about 25 liters / minute.

[0218] The variable flow rate can include a therapeutic flow rate component, the therapeutic flow rate being from about 0.2 liters / minute per kilogram of patient to about 2.5 liters / minute per kilogram of patient, preferably from about 0.25 liters / minute per kilogram of patient to about 1.75 liters / minute per kilogram of patient, more preferably from about 0.3 liters / minute per kilogram of patient to about 1.25 liters / minute per kilogram of patient or about 1.5 liters / minute per kilogram of patient, and even more preferably from about 0.4 liters / minute per kilogram of patient to about 0.8 liters / minute per kilogram of patient.

[0219] The time-varying (eg, fluctuating) component or components of the gas flow may have one or more frequencies between about 0.3 Hz and about 4 Hz.

[0220] The variable flow rates may include at least one time-varying flow component, each variable flow rate ranging from about 0.05 liters / minute per kilogram of patient to about 2 liters / minute per kilogram of patient, preferably from about 0.05 liters / minute per kilogram of patient to about 0.5 liters / minute per kilogram of patient, preferably from about 0.12 liters / minute per kilogram of patient to about 0.4 liters / minute per kilogram of patient, more preferably from about 0.12 liters / minute per kilogram of patient to about 0.35 liters / minute per kilogram of patient. Alternatively, the variable flow rates may include at least one time-varying flow component, each variable flow rate ranging from 0.05 liters / minute per kilogram of patient to about 2 liters / minute per kilogram of patient, preferably from 0.1 liters / minute per kilogram of patient to 1 liter / minute per kilogram of patient, more preferably from 0.2 liters / minute per kilogram of patient to 0.8 liters / minute per kilogram of patient.

[0221] The above are examples of therapeutic flow rates that vary over time. A signature flow rate may also be provided and may be lower, the same, or higher than the therapeutic flow rate. The frequency of the signature flow rate (if time-varying) may be lower, the same, or higher than the frequency of the therapeutic flow rate. In some embodiments, the signature flow rate has a higher frequency than the therapeutic flow rate.

[0222] As an example, the signature flow rate may be stepped between a first flow rate and a second flow rate, one or both of which may fall in the range of approximately 0 LPM to 70 LPM. The maximum signature flow rate may be the therapeutic flow rate. The signature flow rate may be combined (e.g., added) with the therapeutic flow rate or may form part or all of the therapeutic flow rate, i.e., the therapeutic flow rate itself may be the signature flow rate. In some embodiments, the signature flow rate may be related to the therapeutic flow rate as a percentage. For example, a time-varying signature flow rate (adult) may be in the following range: - from about 0% to about 200% of therapeutic flow rate; - Approximately 0% to 100% of therapeutic flow rate; - Approximately 100% to 200% of therapeutic flow, or - Approximately 50% to 150% of therapeutic flow rate and / or in the following range: - Approx. 0~140LPM, - Approx. 0~70LPM, - Approx. 70~140LPM, - Approximately 40 to 100 LPM, or - Approx. 20~60LPM is located.

[0223] Note also that these are not limiting flows, and signature flows can be negative, but when combined with therapeutic flows can result in a positive total flow.

[0224] In some embodiments, the therapeutic flows also function as signature flows, i.e., they serve a dual purpose.

[0225] The above are merely examples and other types of time-varying flow rates can be provided, with the controller controlling the gas flow modulator to provide a time-varying system gas flow at a time-varying flow rate. The system may have knowledge of the time-varying flow rate and / or may measure the time-varying flow rate provided, for example by flow sensors such as 53A, 53B, 53C, 53D.

[0226] A humidifier 52 may be optionally provided between the flow source 50 and the patient to provide humidification of the delivered gas. It may be a humidifier integrated with the flow source 50 to form an integrated device (see dotted line) or a humidifier separate from the flow source 50 but attachable to the flow source 50. Alternatively, the humidifier 52 may be a stand-alone humidifier having a chamber and a base, in which case the humidifier is coupled to the flow source 50 via a conduit or other suitable means. One or more sensors 53A, 53B, 53C, 53D, such as flow rate, oxygen fraction CO2 or other gas fraction, total or partial pressure, humidity, temperature or other sensors, may be located on or near the entire device and / or the patient 14. Alternatively or additionally, sensors capable of deriving such parameters may also be used. Additionally or alternatively, the sensors 53A-53D may be one or more physiological sensors for sensing a patient physiological parameter such as heart rate, oxygen saturation (e.g., pulse oximeter sensor 54E), partial pressure of oxygen in the blood, respiration rate, partial pressure of O2 and / or CO2 in the blood. Alternatively or additionally, sensors capable of deriving such parameters may be used. Other patient sensors may include EEG sensors, torso bands for detecting respiration, and other suitable sensors that may sense, among other things, whether the patient is exhaling or inhaling (respiratory phase / state). In some configurations, a humidifier may be optional, although a humidifier may be preferred due to the benefit that humidified gas helps maintain airway condition. Humidification is preferably used with high flow gas flows to increase patient comfort, compliance, support and / or safety. One or more of the sensors may form part of the device or may be external to the device, with inputs for external sensors.

[0227] Sensors 14 are provided for measuring gas parameters (of the target gas) of the patient combined gas inflow and outflow flows 15. The sensors may sense at the mouth and / or nose. The sensors may be located at any suitable location that may be at the mouth and / or nose, or may be extracted therefrom with sensing portions at the mouth and / or nose. That is, depending on the target gas, e.g., oxygen, carbon dioxide, nitrogen, helium and / or anaesthetic agent such as sevoflurane, a sensor is selected that senses that gas in the combined gas outflow. The sensor may be, for example, a mainstream sensor or a sidestream sensor, and may be located in close proximity (in, on, near) to the nose and / or mouth. Other locations are possible. Time-varying flow rate embodiments may function with one gas parameter sensor - for example, when one gas parameter (e.g., fractional CO2 or fractional O2) is measured. In time-varying flow rate embodiments, it is not necessary to measure multiple gas parameters to obtain a target parameter (e.g., it is not necessary to measure fractional CO2 and fractional O2 to practice the embodiments herein).

[0228] Output from the sensor is sent to the controller to aid in controlling the device, such as varying the gas flow or, in the case of sensor 14, determining and displaying a respiratory parameter. Alternatively or additionally, input from a user is also possible. The controller is coupled to the flow source, the humidifier, and the sensor. The controller controls these and other aspects of the device, as described below. The controller can operate the flow source to provide a delivered gas flow. It can also operate the gas flow modulator (including the flow source) to control the flow, pressure, volume, and / or other parameters of the gas provided by the flow source based on feedback from the sensor or optionally without feedback (e.g., using default settings or user input). The controller can also control any other suitable parameters of the flow source to meet oxygenation requirements and / or CO2 removal. The controller 19 can also control the humidifier 52 based on feedback from the sensors 53A-53D, 14. Using inputs from the sensors, the controller can determine oxygenation requirements and provide information to a medical professional (who may control components of the respiratory apparatus to provide the desired therapy, e.g., flow rate, O2 fraction, humidity, etc.) and / or control parameters of the flow source, gas flow modulator and / or humidifier as needed. Alternatively, this embodiment can be provided as a stand-alone monitoring device independent of the respiratory apparatus that provides information to a medical professional and / or communicates with and / or controls components of the respiratory apparatus to provide the desired therapy or respiratory assistance. Thus, the medical professional can control the respiratory apparatus to provide the desired therapy. Thus, the controller does not always determine the oxygenation requirements and / or the control parameters of the apparatus.

[0229] The controller 19 is also configured to operate the device such that the device gas flow has a time-varying flow rate that provides therapy and a signature flow rate as described. This can be done by any suitable means, such as controlling the flow generator 50B or other suitable gas modulator. The gas modulators can be used to modulate (i.e., change, modify, adjust or otherwise control parameters of the gas flow). Each gas flow modulator can be provided in the flow source (the flow source itself can be a gas flow modulator), after the flow source and before the humidifier, after the humidifier and / or in any other suitable location in the device to modulate the gas flow path. The gas flow modulator (including the flow source) can also be operated to control the flow, pressure, volume and / or other parameters of the gas provided by the flow source based on feedback from sensors or optionally without feedback (e.g., using default settings or based on user input). The controller can also control any other suitable parameters of the flow source to meet oxygenation requirements. The gas modulator may be, for example, any of those described in International Publication No. WO 2017 / 187390 or U.S. Patent Publication No. 20210052844, which are incorporated by reference in their entireties.

[0230] The controller can then measure the composite gas output flow and determine gas and / or respiratory parameters using any of the techniques described throughout.

[0231] For other embodiments below related to varying gas fractions, the controller 19 is additionally or alternatively configured to operate the device such that the system gas flow has a time-varying gas fraction (such as O2 fraction or other gas fraction and / or O2 partial pressure or other gas partial pressure) that provides therapy / respiratory support and has a signature gas fraction (such as gas fraction and / or gas partial pressure) as described. The controller can do this by any suitable means such as controlling a proportional valve coupled to the O2 source 50A or any other means previously described in other patents. The controller can then measure the combined gas output flow and / or determine (e.g., obtain an estimate of) the gas and / or respiratory parameters using any of the techniques described throughout. In one embodiment, there are two proportional valves that operate 180 degrees out of phase. When one opens, the other closes. One controls the O2 fraction in the system gas flow and the other controls the air fraction in the system gas flow, but together keep the total gas flow rate of the system gas flow constant. In another alternative, a single proportional valve is used with the impeller / flow generator, where the proportional valve controls the O2 fraction and the impeller controls the flow rate. In some embodiments, a single proportional valve can be used before or after the impeller. If a single proportional valve is used before the impeller, the proportional valve controls the O2 fraction to the inlet of the impeller along with the ambient air. In some embodiments, more than one proportional valve can be used with the impeller and can be positioned anywhere in the system relative to the impeller. The controller 19 can control the proportional valves to operate as needed to achieve the time-varying gas proportions as described herein.

[0232] An input / output interface 54 (such as a display and / or input devices) is provided for receiving information from a user (e.g., a clinician or patient) that can be used to determine, for example, oxygenation requirements, anesthetic gas agent, detection, flow rates, gas fractions, partial pressures, and / or any other parameters that may be controlled by the device.

[0233] The device also includes a display, which may be part of the I / O, for displaying measurements of gas parameters of the expiratory gas flow as a graph, digital display, or any other suitable means. It may also display status and / or respiratory parameters such as tidal volume (instantaneous or cycle number average) and / or patient gas flow. It may display values ​​or average values ​​or traces.

[0234] The device may include one or more communication modules 59 to enable data communication or connection with one or more external devices or servers, either wired, wireless, or a combination thereof, or via a data or communication link or data network. For example, in one configuration, the device may include a wireless data transmitter and / or receiver or transceiver 59 to enable the controller 19 to wirelessly receive data signals from the motion sensors and / or control various components of the system. The transceiver 59 or data transmitter and / or receiver module may have an antenna. In one example, the transceiver may include a Wi-Fi modem. Additionally or alternatively, the data transmitter and / or receiver 59 may deliver data to a remote patient management system (i.e., a remote server) 69 or enable remote control of the system. The system may include a wired connection, e.g., using a cable or wire, to enable the controller 19 to receive data signals from the motion sensors and / or control various components of the device 10. The device 10 may include one or more wireless communication modules. For example, the device may include a cellular communication module, such as, for example, a 3G, 4G or 5G module. Module 59 may be or may include a modem that allows the device to communicate with a remote patient management system (not shown) using a suitable communication network. The remote management system may include a single server or multiple servers or multiple computing devices implemented in a cloud computing network. The communication may be two-way communication between the device and the patient management system (such as a server) or other remote systems. The device 10 may also include other wireless communication modules, such as, for example, a Bluetooth module and / or a Wi-Fi module. The Bluetooth module and / or the WiFi module allow the device to transmit information wirelessly to other devices, such as, for example, a smartphone or tablet, or to operate over a LAN (Local Area Network) or a wireless LAN (WLAN).The device may additionally or alternatively include a Near Field Communication (NFC) module to enable data transfer and / or data communication.

[0235] For example, the measured patient respiratory parameter data (e.g., inhale, exhale, and / or total breath time ratio) may be communicated to a remote patient management system (i.e., remote server). The remote patient management system may be a single server, or a network of servers, or a cloud computing system, or other suitable architecture for operating a remote patient management system. The remote patient management system (i.e., remote server) may further include a memory for storing received data and various software applications or services executed to perform a number of functions. Thus, for example, the remote patient management system (i.e., remote server) may communicate information or instructions to the system 10 depending at least in part on the data received. For example, depending on the nature of the received data, the remote server (or software application executed on the remote server) may be triggered to communicate an alert, alarm, or notification to the system 10. The remote patient management system may further store the received data for access by an authorized party, such as a clinician, a patient, or other authorized party. The remote patient management system may be further configured to generate a report in response to a request from an authorized party, and the respiratory parameter data, e.g., inhale, exhale, and / or total breath time ratio, may be included in the generated report. The report may further include other patient respiratory parameters, such as respiration rate or SpO2, and / or device parameters, such as flow rate, humidity level.

[0236] As mentioned above, the controller 19 implements one or more of the methods described herein. Depending on the embodiment of the method used, one or more of the following state parameters are obtained using the device or other means as indicated: a) Mouth state, which can be a binary open / closed or some parameter indicating the ratio (e.g., volume fraction) of gas flow from the system gas flow exiting the mouth relative to the nose. For example, k, b) The flow rate of gas from the breathing apparatus, e.g., Q O , c) The gas fraction of the gas flow from the breathing apparatus (including any equivalent gas fraction), e.g., the O fraction, but if appropriate any other gas fraction, e.g., N or tracer gas F O , but may be any other gas proportion if appropriate, for example N2 or a tracer gas. d) The gas fraction of the gas flow entering or leaving the patient (depending on whether it is measured on inspiration or expiration). For example, the O2 fraction F m , but may be any other gas proportion if appropriate, e.g. CO2, N2 or a tracer gas. e) The gas fraction of the patient's expiratory gas flow. E can be any gas proportion, e.g. O2, CO2, N2 or a tracer gas, where appropriate. f) Gas fraction and flow rate of entrained (ambient) gas. Q ent , F ent (F entrained (Note that it may also be referred to as the gas mixture ratio), but may be any gas ratio, e.g., O2, CO2, N2, or a tracer gas, where appropriate. g) Patient gas flow rate (this can be both a state parameter and a respiratory parameter) that is less than or equal to: a. Flow rate Q of the expiratory gas flow 13 (i.e., the gas flow exhaled by the patient) E and / or b. The flow rate Q of the combined gas inlet flow 17 (i.e., the combined gas flow inhaled by the patient) tot Q TOT Note that also indicates the inhalation flow demand of the patient.

[0237] In the above, the gas fraction may be O2, CO2 or other gas fractions. Instead of gas fractions, partial pressures may also be used, which will be understood by those skilled in the art as being interchangeable throughout this specification.

[0238] The controller uses one or more of the state parameters according to one or more of the methods described herein to determine Q E Or Qtot is determined, followed by determining tidal volume and / or one or more of the other respiratory parameters described herein.

[0239] It will be appreciated that the above embodiments are specific examples of using one or more state parameters to determine one or more respiratory parameters. In each case, gases such as trace gases such as O2, CO2, N2, or anesthetic agents may be used as markers to make the determination. Any references to specific gases above are exemplary only and should not be so limiting as alternative gases may readily be used.

[0240] 7. Derivation The derivation of the various equations used is given in this section.

[0241] The formulas refer to a constant k, which is a value between 0 and 1 and is the rate at which the delivered gas (the device gas flow rate 11) passes through the mouth. When the mouth is closed, k=0. When the mouth is open, a certain percentage k of the device gas flow passes through the mouth and a certain percentage (1-k) passes through the nose (e.g., arriving / leaving the nose). K can be a time constant. In the more general case, k can also change over time because the "openness" of the mouth changes over time. In this case, k can be dependent on t, i.e., k(t). In this case, k is a time-varying constant, mathematically a constant, but not a constant value over time because it can change. Note that even in the situation where the mouth is open, k may not be time-dependent, so both time-dependent and time-independent k are possible. References to k or k(t) should not be considered limiting herein, and either can be used as long as the context allows.

[0242] When the mouth is closed (k=0), the formula is F measured through the sensor 14 at the nose. m When the mouth is open (k=0~1), the formula is based on F measured at the mouth. m Based on.

[0243] 7.1 Determination of combined gas inlet flow rates and / or respiratory parameters during the inhalation cycle when the patient's mouth is closed. In this embodiment, Q TOT To obtain the (total inspired) patient gas inflow (combined gas inflow) 17 (system gas flow 11 and entrained air gas flow 16) flow rate to the patient, use the following equation 37:

number

[0244] k is a value between 0 and 1 and is the rate at which delivered gas (system gas stream 11) exits through the port. If the port is closed, then k = 0. In this case, since the port is closed, k = 0, and the term (1-k(t)) becomes 1 and k vanishes.

[0245] It should be noted that references to O2 herein with respect to the above parameters may be interchangeable with N2 or other tracer gases instead.

[0246] QTOT Once calculated, Q TOT can be used to determine tidal volume (a respiratory parameter) by integrating over the inhalation cycle. Tidal volume is given by: V Tidal (t) = ∫Q Tot (t)dt (38) It can be defined as:

[0247] When the port is closed, the rate of system gas flow out / into the port is equal to zero.

[0248] Thus, if the sensor 14 (e.g., a sampling line) is placed in the patient's nose next to the patient interface, F m (In this case the oxygen fraction (FiO2)) can be measured and from this it is possible to determine a sensed parameter (eg O2 fraction) of the (instantaneous) flow entering the patient.

number

[0249] When rearranged,

number

[0250] The total flow is given by: Q Tot (t)=Q entrained (t)+Q o (t) (35)

[0251] Substituting (34) into (35), we get the following.

number

[0252] Therefore, the tidal volume during inhalation is V Tidal (t) = ∫Q Tot (t)dt (38)

number

[0253] As mentioned above, to measure inhalation flow, delivery of less than the instantaneous demand is necessary. However, doing this throughout the entire inhalation cycle is not necessarily desirable as it reduces respiratory support (e.g., FiO2) to the patient. Thus, the flow rate of the device can be varied over time (e.g., oscillating or varying between two values), measurements taken while flow rate is low, and interpolation or similar techniques can be used to derive continuous measurements of flow, which can then be integrated to determine tidal volume. The frequency of oscillation is optionally higher than the respiratory frequency.

[0254] Additionally, the time of low flow can be shortened relative to the time of high flow to increase the average FiO2 delivered to the patient. Note that the low flow must be greater than zero to allow for differentiation from high flow systems and entrained air.

[0255] Optionally, varying the flow rate includes steps between a high flow rate, preferably higher than the patient's inhalation demand, and a low flow rate, optionally a non-zero flow rate, lower than the patient's inhalation demand.

[0256] 7.2 Determination of expiratory gas flow and / or state parameters during the exhalation cycle when the patient's mouth is closed In this embodiment, Q E - To obtain the expiratory flow rate (i.e. the flow rate of the expiratory gas flow 13), the following equation 41 is used:

number

[0257] Q E Once calculated, Q E can be used to determine tidal volume (a respiratory parameter) by integrating over the exhalation cycle. Tidal volume is given by: V Tidal (t) = ∫Q E (t)dt (42) It can be defined as:

[0258] An alternative approach to solving the problem of needing to keep the system gas flow less than the instantaneous inhalation flow during inhalation so that oxygen concentration can be measured by the sensor described herein.

[0259] Generally, assuming that the inhalation and exhalation volumes are the same, it is possible to measure only the exhalation flow.

[0260] When flow occurs from the nose to the surrounding environment, the measured fraction at the nose can be expressed as:

number

[0261] Q E If we rearrange it,

number

[0262] F E Although (t) cannot be measured directly, by varying the oxygen flow, F can be calculated using equation (17). E (t) can be found.

number

[0263] Varying the oxygen during expiration has the advantage that it does not affect the patient's FiO2.

[0264] F from measured / known parameters EIn addition to calculating (t), we measure FiO2 during inspiration and assume a difference between the inspired and expired oxygen fractions (e.g., the expired O2 fraction is 5% lower than the inspired O2 fraction), so F E (t) can also be inferred. Furthermore, it can have an assumed value.

[0265] To calculate Equation 41, F E However, it may be difficult to determine a parameter of the gas composition of the expired gas flow 13 (whether O2 fraction, CO2 fraction or other gas parameter) when the system gas flow 11 is provided to the patient because leakage ("leakage gas flow") 12 from the system gas flow 11 from the respiratory apparatus 10 is added to the expired gas flow 13 to produce a total gas output flow ("combined gas output flow") 15 from the patient as measured, for example, by a sensor 14.

[0266] Thus, the expiratory gas flow 13 is not actually measured by the sensor 14, but rather a combined gas output flow 15, which combines the leak gas flow 12 and the patient's expiratory gas flow. The leak gas flow 12 may dilute (e.g., when measuring CO2 fraction) or increase (e.g., when measuring O2 fraction) or more generally "change" the gas components of the expiratory gas flow 13 measured by the sensor 14, giving misleading information about the parameters of the resulting gas components. This problem is exacerbated at high flows, e.g., when providing high-flow therapy. Thus, instead of measuring the expiratory gas flow 13, the sensor is actually measuring the gas components of the combined gas output flow 15, which includes the expiratory gas flow 13 and possibly at least a portion of the device gas flow 11 (i.e., the leak gas flow 12). Because the expiratory gas flow 13 is not actually measured, but rather a combined gas output flow is measured, the apparent reading of the expiratory gas flow is not accurate. It should be noted that the composite gas output stream 15 may also include other gases, such as gases present in the ambient air.

[0267] This situation is described in detail in PCT / IB2021 / 052062, U.S. Patent Application No. 62 / 989081 (from which PCT / IB2021 / 052062 claims priority), which are incorporated herein by reference in their entirety.

[0268] The following derivation is performed by measuring the parameters of the gas components in the combined gas outlet flow 15 at or near the patient ("nearby"), taking into account the effect of the leakage gas flow 12 on the measured parameters, adjusting the measurements accordingly (or otherwise using the measurements and other information), and determining the parameters of the desired gas components in the actual expiratory gas flow 13 from the patient, F. E The present invention can be used to provide an apparatus and method for determining the signature of a gas that is present in the ambient air. The apparatus gas stream can be altered with a signature to aid in the determination of the parameter. The composite gas output stream 15 can also include other gases (in addition to CO2 and O2) such as gases present in ambient air. The described embodiment also functions in the presence of such additional gases.

[0269] The respiratory device may include a flow source capable of providing a system gas flow to a patient. The device provides a time-varying system gas flow such that a time-varying parameter of the system gas flow varies over time. This provides a signature that can be used to assist in determining a gas parameter of the actual exhaled gas flow 13. As possible examples, the time-varying parameter of the system gas flow may be a flow rate or a gas fraction, such as a gas fraction (e.g., O2 fraction) and / or a gas partial pressure (e.g., O2 partial pressure).

[0270] F E is derived in one of two ways, depending on whether the time-varying flow rate or the time-varying O2 fraction of the system gas stream 11 is used:

[0271] Note that for measurements at the nose, in the derivations below (sections 7.2.1 and 7.2.2), the constant k must be replaced by (1-k). When the mouth is closed and measurements are taken at the nose, k=0, and (1-k)=1.

[0272] NOTE: Changes in oxygen fraction or flow may occur only during exhalation to reduce interruptions to patient respiratory support.

[0273] 7.2.1 Determination of respiratory parameters using time-varying system gas flows F E can be determined as follows when using a system gas stream 13 with a time-varying flow rate (an alternative equation can be used for CO2 breath fraction - O2 breath fraction, described below):

number

[0274] It is derived as follows: Assuming that all or most of the gas exhaled by the patient exits through the mouth, the volume fraction of gas measured at the mouth of a patient providing high flow to the nose (F m ) as a function of time,

number

[0275] Equation (1) is based on the unknown quantities k and Q E can be rearranged to find the ratio of

number

[0276] During the patient's exhalation phase, the fraction of the (exhaled) gas component (volume fraction of the gas component F measured in the patient's combined gas outlet flow 15') m ), the patient's expiratory gas flow rate (Q E ) and the rate of system gas flow out the port (k) can be approximated for two samples taken at times t and t+Δt, where Δt, the time between samples, is short enough that it can be assumed that the rate of system gas flow out the port (k) is approximately constant.

number

[0277] Next, from (3),

number

[0278] F E Solve.

number

[0279] This formula can be used to determine parameters of the expiratory gas flow 13, such as the expiratory fraction of oxygen, carbon dioxide, nitrogen, helium and / or anaesthetic agents such as sevoflurane.

[0280] In some configurations, the parameters of the gas flow components in the expiratory gas flow 13′ (FE A correction or compensation can be applied to equation (4) to obtain a better estimate of . For example, a correction or compensation can be applied to equation (4) to account for the fact that the assumption that the ratio of the combined gas outlet flow and the system gas flow out of the port is approximately constant is incorrect. Such a correction or compensation can take into account the ratio of the port flow to the patient interface flow as a function of the patient interface flow, for example, as described in applicant's publications WO 2017187391 or U.S. Patent Application Publication No. 2019 / 0150831, which are incorporated herein by reference in their entireties.

[0281] In the measurement of CO2, F O (t)=F O Since (t+Δt)~0, equation (4) becomes:

number

[0282] The above is a known / measured quantity, F m (t), Q O (t), F m (t+Δt), Q O This is the equation for oxygen and carbon dioxide for (t+Δt). The calculated F E CO2 can restore the carbon dioxide waveform.

[0283] 7.2.2 Determination of respiratory parameters using time-varying gas fractions of system gas flows When using a system gas stream 11 with a time-varying gas fraction, the following can be determined:

number

[0284] If the oxygen fraction of the system gas stream 11 changes over time but the flow rate of the system gas stream 11 is constant, Q o (t+Δt)=Q o(t) and equation (4) is

number

[0285] Simplifying the top and bottom rows, we get:

number

[0286] 7.3 Determination of the delivery flow rate and / or state parameters during the delivery cycle when the patient's mouth is open In this embodiment, the following formula 30:

number

[0287] Equation 30 is similar to Equation 41, except that Equation 30 has a k(t) term, whereas Equation 41 has a (1-k(t)) term. This is because in Equation 41, the mouth is closed so sensor 14 senses at the nose. In Equation 30, the mouth is open so sensor 14 senses at the mouth.

[0288] This k(t) can be calculated as follows: For example, a sealed interface can be used at one nostril and the flow Q from the other nostril can be measured. m Measure. Q m =(1-k)Q o (28)

[0289] This gives the following formula:

number

[0290] Once the amount of high flow present at the mouth is determined, the tidal volume can be determined.

[0291] Consider equation (14).

number

[0292] Next, the discharge flow is

number

[0293] Using the previously derived equations 16 and 17, the volume fraction of the exhaled gas F can be calculated by changing the oxygen fraction or flow rate of the system gas flow. E can be determined.

Claims

1. 1. An apparatus for providing respiratory assistance and determining respiratory parameters of a patient while receiving respiratory assistance, comprising: a flow generator for providing a system gas flow to the patient having a system gas flow rate and a system gas flow gas fraction; one or more sensors or inputs for one or more sensors positioned in the patient's mouth and / or nose for measuring gas parameters of a combined gas outflow from the patient; a controller, determining a proportion of the device gas flow through the mouth and / or nose of the patient; The expiratory gas flow rate is the gas fraction of the system gas stream; the flow rate of the system gas stream; gas parameters of the combined gas effluent stream; the proportion of the device gas flow through the mouth and / or nose of the patient; an expiratory gas flow parameter determined using gas parameters of the combined gas output stream and a time-varying flow rate or time-varying gas fraction of the system gas stream; configured to determine using one or more of: determining one or more respiratory parameters from the expiratory gas flow; A controller; An apparatus comprising:

2. The one or more respiratory parameters are: tidal volume, minute ventilation, breathing rate, Apnea, Airway patency, and / or Peak flow rate 10. The apparatus of claim 1, comprising one or more of:

3. 10. The apparatus of claim 1, wherein the gas parameters of the combined gas output stream are gas proportions measured by one or more sensors positioned at the mouth of the patient.

4. 10. The apparatus of claim 1, wherein the apparatus gas stream comprises one or more of O2, CO2, N2, or a tracer gas.

5. 10. The device of claim 1, wherein the flow rate of the device gas flow varies at a frequency higher than the breathing frequency.

6. The device of claim 1 , wherein the expiratory gas flow parameter is a gas fraction of the expiratory gas flow.

7. 2. The device of claim 1, wherein the controller is configured to determine the percentage of the device gas flow through the patient's mouth and / or nose by determining the percentage of the device gas flow through the patient's mouth based on input from the one or more sensors.

8. The controller controls the expiratory gas flow rate (Q E )of, [Equation 1] and configured to determine based on the formula: Q E is the expiratory gas flow rate, Q O is the flow rate of the system gas stream; k is the rate of device gas flow through the patient's mouth, with k=0 indicating the patient's mouth is closed; F O is the gas fraction of the system gas stream; F m is a gas parameter of the composite gas outlet stream; F E 10. The apparatus of claim 1, wherein: is the expiratory gas flow parameter.

9. The controller is configured to determine the expiratory gas flow parameter using a time-varying flow rate of the device gas flow, and to determine a gas parameter (F m ) is the volume fraction of O2, and the controller controls the expiratory gas flow parameter (F E )of, [Equation 2] The apparatus of claim 8 , wherein the determination is based on:

10. The controller is configured to determine an expiratory gas flow parameter using the time-varying flow rate of the device gas flow, and to determine a gas parameter (F m ) is the volume fraction of CO2, and the controller controls the expiratory gas flow parameter (F E )of, [Equation 3] The apparatus of claim 8 , wherein the determination is based on:

11. The controller is configured to determine an expiratory gas flow parameter using the time-varying oxygen fraction of the device gas flow, and to determine a gas parameter (F m ) is the volume fraction of O2, and the controller controls the expiratory gas flow parameter (F E )of, [Equation 4] The apparatus of claim 8 , wherein the determination is based on:

12. The one or more respiratory parameters may include tidal volume (V Tidal ), wherein the controller determines a tidal volume, [Equation 5] The apparatus of claim 8 , configured to determine based on:

13. 2. The device of claim 1, wherein the controller is configured to determine the expiratory gas flow parameter using gas parameters of the combined gas outlet flow, a time-varying flow rate or time-varying gas fraction of the system gas flow, and a fraction of the system gas flow through the mouth and / or nose of the patient.

14. The device of claim 1 further comprising a humidifier.

15. 2. The device of claim 1, wherein the controller is configured to determine the expiratory gas flow rate using all of the gas fraction of the device gas flow, the flow rate of the device gas flow, gas parameters of the combined gas outlet flow, and expiratory gas flow parameters.

16. 10. The apparatus of claim 1, wherein one of the flow rate of the system gas stream and the gas fraction of the system gas stream varies over time.

17. 17. The device of any one of claims 1 to 16, wherein the device has or connects to a non-sealing interface.

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