Metabolic Monitoring System and Method

Abstract

The present disclosure describes a metabolic monitoring system, including for collecting exhaled gas from a subject's nasal airway; a mixing chamber for receiving at least a portion of the exhaled gas from an interface device; a plurality of sensors for outputting signals related to one or more gas parameters, the one or more gas parameters being related to the inhaled gas and exhaled gas of the subject during one or more breaths; and a processor configured to: determine the gas flow rate in the interface device; determine a pressure change near the subject's mouth to detect mouth breathing of the subject; determine the concentration measurements of O2 and CO2 of the portion of the exhaled gas in the mixing chamber, and discard the concentration measurements corresponding to mouth breathing; determine the oxygen consumption rate VO2 and carbon dioxide production rate VCO2 of the subject based on the determined gas flow rate, the determined CO2 concentration, and the determined O2 concentration.

Description

Technical Field

[0001] The present disclosure relates to metabolic monitoring systems and methods.

[0002] Description of the Related Art

[0003] The present disclosure relates to metabolic monitoring systems and methods. Existing commercial devices cover several applications, including mechanically ventilated critically ill patients, specialized visits (e.g., by dietitians or nutritionists), and spot checks on healthy subjects. There is a need for better metabolism monitoring devices.

[0004] U.S. Patent Application No. US2018 / 125391 discloses a device for modeling, monitoring, and / or managing a subject's metabolism, including measuring a subject's respiratory quotient (RQ) level and / or optimizing and implementing a non-linear feedback model to model the use of energy substances in the subject based on at least one of: the macronutrient composition and calorific value of the food consumed by the subject, the intensity and duration of the subject's activity, the rate and maximum capacity of the subject's glycogen stores, the rate and maximum capacity of the subject's de novo lipogenesis, the quality and duration of the subject's sleep, and / or the subject's RQ level. Summary of the Invention

[0005] Thus, one or more aspects of the present disclosure relate to a metabolic monitoring system, including an interface appliance configured to collect exhaled gas from a subject's nasal airway; a mixing chamber operably connected to the interface appliance, the mixing chamber being configured to receive at least a portion of the exhaled gas from the interface appliance; a plurality of sensors configured to output signals related to one or more gas parameters related to the inhaled and exhaled gases of the subject during one or more breaths; and one or more physical computer processors operably connected to the sensors to receive the output signals, the one or more physical computer processors being configured by computer-readable instructions to: determine the gas flow rate in the interface appliance during one or more breaths based on the output signals from the sensors; determine a pressure change near the subject's mouth during one or more breaths based on the output signals from the sensors to detect the subject's mouth breathing; determine a concentration measurement of a portion of the exhaled gas in the mixing chamber of O 2 and CO 2 and discard the concentration measurements corresponding to mouth breathing; determine the subject's oxygen consumption rate VO 2 and carbon dioxide production rate VCO 2 .

[0006] Another aspect of the present disclosure provides a metabolic monitoring method, including: collecting exhaled gas from a subject's nasal airway through an interface device; receiving at least a portion of the exhaled gas from the interface device in a mixing chamber, the mixing chamber being operably connected to the interface device; receiving output signals related to one or more gas parameters from a plurality of sensors, the one or more gas parameters being related to the inhaled gas and exhaled gas of the subject during one or more breaths; determining, by one or more physical computer processors, the gas flow rate in the interface device during one or more breaths based on the output signals from the sensors; determining, by one or more physical computer processors, the pressure change near the subject's mouth during one or more breaths based on the output signals from the sensors to detect the subject's mouth breathing; determining, by one or more physical computer processors, the concentration measurement of a portion of the exhaled gas in the mixing chamber of O 2 and CO 2 and discarding the concentration measurements corresponding to mouth breathing; and determining, by one or more physical computer processors, the oxygen consumption rate VO 2 and carbon dioxide production rate VCO 2 of the subject based on the determined gas flow rate, the determined carbon dioxide concentration of the exhaled gas in the mixing chamber, and the determined oxygen concentration of the exhaled gas in the mixing chamber.

[0007] These and other objects, features, and characteristics of the present disclosure, as well as the operating methods and functions of the related elements of the structure, and the combination and economy of manufacture of the components, will become more apparent by considering the following description and the appended claims in conjunction with the accompanying drawings, all of which form a part of this specification, wherein like reference numerals designate corresponding parts in the various drawings. However, it should be clearly understood that the drawings are for illustrative and descriptive purposes only and are not intended as a definition of the limits of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 Illustrates a nocturnal metabolic monitoring system according to one or more embodiments;

[0009] Figure 2A Illustrates an example of an interface device according to one or more embodiments;

[0010] Figures 2B to 2C Illustrates an example of a subject interface according to one or more embodiments;

[0011] Figure 3 Illustrates an example of a nocturnal metabolic monitoring system according to one or more embodiments;

[0012] Figure 4Illustrates an example of a nocturnal metabolic monitoring system according to one or more embodiments; and

[0013] Figure 5 Illustrates a nocturnal metabolic monitoring method according to one or more embodiments. Detailed Description

[0014] As used herein, unless the context clearly dictates otherwise, the singular forms "a," "an," and "the" include plural references. As used herein, the phrase two or more parts or components "coupled" shall mean that the parts are joined or operate together either directly or indirectly (i.e., through one or more intermediate parts or components) as long as a link occurs. As used herein, "directly coupled" means that two elements are in direct contact with each other. As used herein, "fixedly coupled" or "fixed" means that two components are coupled so as to move as one piece while maintaining a constant orientation relative to each other.

[0015] As used herein, the word "integral" means that a component is produced as a single piece or unit. That is, a component that includes segments produced separately and then coupled together as a unit is not an "integral" component or body. As used herein, the phrase two or more parts or components "engaged" with each other shall mean that the parts exert a force on each other either directly or through one or more intermediate parts or components. As used herein, the term "number" shall mean one or an integer greater than one (i.e., a plurality).

[0016] Unless explicitly stated otherwise therein, directional phrases used herein (such as but not limited to top, bottom, left, right, up, down, front, back, and derivatives thereof) refer to the orientation of elements shown in the drawings and do not limit the claims.

[0017] Figure 1 Illustrates an example of a metabolic monitoring system 100 according to one or more embodiments of the present invention. In some embodiments, system 100 is configured to perform metabolic monitoring while a subject is inactive (e.g., sleeping). In some embodiments, system 100 is configured for nocturnal metabolic monitoring. System 100 can allow for monitoring of a subject's metabolism at home (at night and without the need for a professional) without the use of an expensive and sporadic measurement using a metabolism chamber or other equipment that is only available in specialized facilities. Continuous monitoring of metabolism and its changes can provide insights into basal energy expenditure as well as available glycogen reserves and can be used to customize diet and physical activity in order to optimize weight and energy management.

[0018] In some embodiments, based on oxygen consumption (VO 2 ) measurement and carbon dioxide production (VCO 2) By measuring and its overnight changes, system 100 can provide information about the metabolic state of a subject. In some embodiments, system 100 includes a mixing chamber for gas analysis (e.g., CO 2 concentration measurement and O 2 concentration measurement). The mixing chamber can be made smaller and relatively portable. No subject cooperation is required other than the wearing interface. VO 2 measurement and VCO 2 measurement can be used to estimate the energy expenditure (EE) and respiratory quotient (RQ) of a subject. The energy expenditure (EE) can be used to evaluate the caloric needs of an individual, while the respiratory quotient (RQ) can provide information about the macronutrients (e.g., carbohydrates, fats, proteins, etc.) primarily used to generate energy.

[0019] In some embodiments, system 100 includes a subject interface 90 that is designed to collect all exhaled gas at the subject's nose (e.g., continuously, with each breath) during one or more breaths for further analysis. In some embodiments, system 100 is configured to detect mouth breathing (e.g., using pressure sensor 44) in order to discard invalid measurements (including measurements of mouth breathing). This provides a more accurate determination of VO 2 、VCO 2 、EE and / or RQ. System 100 also provides a better depiction of the subject's nocturnal metabolic state.

[0020] In some embodiments, system 100 includes a subject interface 90, one or more sensors 40, a mixing chamber 30, one or more physical computer processors 60, a user interface 120, an electronic storage 130, a network 150, and / or other components.

[0021] In some embodiments, the subject interface 90 is configured to convey a flow of breathable gas (e.g., ambient air) to the airway of the subject 70. The subject interface 90 is configured to deliver breathable ambient air to the nostrils of the subject and also collect exhaled gas from the subject's nostrils (e.g., using the interface appliance 80). In some embodiments, the subject interface 90 includes a conduit 50, an interface appliance 80, one or more valves 85, and / or other components. In some embodiments, the interface appliance 80 is configured to removably engage one or more external orifices (e.g., nostrils) of the airway of the subject 70 to convey gas between the airway of the subject 70 and the subject interface 90. The interface appliance 80 may be removably coupled to the conduit 50 (e.g., the interface appliance 80 may be removed for cleaning, replacement, and / or for other purposes). In some embodiments, the interface appliance 80 may include two prongs configured to be placed in the subject's nostrils and form a seal with the subject's nasal cavity. Sealing the nasal cavity allows for collection of all exhaled gas from the subject's nostrils for further analysis, as described below. Examples of the interface appliance 80 may include nasal cannulas, or other non-invasive or invasive interface appliances that communicate the airflow with the airway of the subject. The present disclosure is not limited to these examples, and any delivery device for delivering an airflow to the subject is contemplated.

[0022] In some embodiments, the subject interface 90 includes one or more valves 85 configured to permit a flow of breathable gas to the nostrils of the subject. For example, one or more valves may be located within the interface appliance 80. In some embodiments, one or more valves 85 are configured to permit a flow of breathable gas (e.g., air from the atmosphere) in one direction. For example, one or more valves 85 are configured to open during inhalation and close during exhalation. Examples of such valves include one-way valves, check valves, non-return valves, and / or other valves that only permit gas to flow in one direction. In some embodiments, the subject interface 90 may be configured to deliver breathable gas from a gas source (e.g., a pressurized gas source that supports the subject's breathing) to the subject.

[0023] In some embodiments, one or more sensors 40 are configured to generate an output signal that conveys information related to one or more respiratory parameters of the subject 70 during one or more breaths. In some embodiments, one or more respiratory parameters may include gas parameters related to the breathable gas provided by the subject interface, respiratory parameters related to the breathing of the subject 70, physiological parameters of the subject 70, and / or other parameters. One or more gas parameters of the breathable gas may include, for example, one or more of the following: inhalation flow rate, exhalation flow rate, inhalation volume, inhalation volume, pressure, humidity, temperature, acceleration, velocity, gas component concentration (e.g., O 2 concentration, CO2 Concentration, etc.) and / or other parameters of the breathable gas. Respiratory parameters related to the respiration of the subject 70 may include tidal volume, timing (e.g., start and / or end of inhalation, start and / or end of exhalation, etc.), inhalation flow rate, exhalation flow rate, respiratory rate, respiratory airflow, duration (e.g., duration of inhalation, duration of exhalation, duration of respiratory cycle, etc.), respiratory frequency, respiratory effort, concentration of exhaled gas components (e.g., O 2 Concentration, CO 2 Concentration, etc.) and / or other respiratory parameters. Physiological parameters may include oximetry parameters, pulse, temperature, blood pressure, and / or other physiological parameters.

[0024] In some embodiments, one or more sensors 40 may include one or more sensors that directly measure such parameters (e.g., through fluid communication with the subject and / or the subject interface). In some embodiments, one or more sensors 40 may include one or more sensors that indirectly generate output signals related to one or more parameters (e.g., through measurements from other sensors or other components inside or outside the system 100). In some embodiments, one or more sensors 40 may include one or more of the following: a position sensor for measuring the position of the subject interface, a volume sensor for measuring the volume of inhaled gas and / or exhaled gas, a pressure sensor for measuring the gas pressure inside / outside the subject interface 90, a humidity sensor for measuring the humidity inside / outside the subject interface, a gas temperature sensor for measuring the gas temperature. In some embodiments, one or more sensors 40 may include one or more sensors configured to generate output signals related to the physiological parameters of the subject 70. For example, a cardiac sensor for measuring the cardiac parameters of the subject, a motion sensor for detecting the movement of the subject, an accelerometer, an oximeter, an audio sensor, a video sensor (camera), and / or other sensors. For example, in some embodiments, the sensor 40 includes one or more flow sensors 42( Figures 3 to 4 as shown in), and the one or more flow sensors are configured to measure the flow rate of inhaled gas and / or exhaled gas going to or from the subject. The flow sensor 42 may be configured to measure the flow rate of the gas inhaled by the subject, the flow rate of the gas exhaled by the subject, the flow rate of the exhaled gas in the interface device 80, the catheter 50, the mixing chamber 30, and / or the flow rate of the gas at other locations in the system 100.

[0025] In some embodiments, one or more sensors 40 include one or more pressure sensors 44 configured to output signals related to the gas pressure at one or more locations within system 100. For example, pressure sensor 44 may include a pressure line located at or near the subject's mouth and configured to measure the pressure at or near the subject's mouth. In some embodiments, sensor 40 includes one or more O 2 concentration sensors 45 (as Figures 3 to 4 shown), the one or more O 2 concentration sensors 45 being configured to output signals related to the O 2 concentration in the exhaled gas. In some embodiments, one or more O 2 concentration sensors 45 are configured to output signals related to the O 2 concentration in the inhaled gas. In some embodiments, one or more O 2 concentration sensors 45 are configured to output signals related to the O 2 concentration in the exhaled gas in the mixing chamber. In some embodiments, sensor 40 includes one or more CO 2 concentration sensors 47 (as Figures 3 to 4 shown), the one or more CO 2 concentration sensors 47 being configured to output signals related to the CO 2 concentration in the exhaled gas. In some embodiments, one or more CO 2 concentration sensors 47 are configured to output signals related to the CO 2 concentration in the inhaled gas. In some embodiments, the CO 2 sensor may be a non-dispersive infrared (NDIR) CO 2 sensor. That is, since other CO 2 sensors may be considered, this should not be construed as limiting, nor should it imply that any other description is restrictive.

[0026] In some embodiments, one or more CO 2 concentration sensors 45 are configured to output signals related to the CO 2 concentration in the exhaled gas in the mixing chamber. In some embodiments, the mixing chamber contains gas sensors, as well as sensors for humidity and temperature, which are required to correct those factors when calculating the gas concentration of the gas sensors. In some embodiments, the exhaled gas is sampled via an interface and directed to the mixing chamber, where the exhaled gas is mixed with gas that was previously sampled and already present in the mixing chamber.

[0027] One or more sensors 40 may include sensors disposed at multiple locations, such as, for example, within the interface appliance 80 (or in communication with the interface appliance 80), on the subject 70, within (or in communication with) the breathing device, catheter 50, and / or other locations. In some embodiments, one or more processors 60 may detect (e.g., based on output signals from the sensors 40) whether there is a seal state with the nostrils. For example, one or more processors 60 may be configured to detect leakage of exhaled gas (e.g., based on measured values of flow rate and / or pressure at the nostrils, and / or based on the position of the appliance relative to the nostrils). In operation, in the case of a broken seal, one or more processors 60 may be configured to discard the measurement or send an alert to the subject indicating a broken seal between the appliance and the nostrils.

[0028] Figure 2A Example 200 of a subject interface 90 according to one or more embodiments is illustrated. In these embodiments, the subject interface 90 includes an interface appliance 80 configured to engage the nostrils to convey gas between the subject's airway and the subject interface 90. The interface appliance 80 includes two prongs 205 and 207 configured to be placed in the subject's nostrils and form a seal with the subject's nasal cavity. This will allow all exhaled gas to be collected from the subject's nostrils for further measurement and analysis. The subject interface 90 includes a catheter 50 operably connected to the interface appliance 80 and configured to direct the exhaled gas to a mixing chamber 30 for further measurement and analysis. The subject interface 90 includes a pressure sensor 44 configured to measure the pressure at or near the subject's mouth (via a pressure line 204 located at or near the mouth) to detect mouth breathing. Based on a change in the output signal from the pressure sensor 44 (indicating a change in the pressure at or near the subject's mouth), mouth breathing can be determined.

[0029] In some embodiments, an increase in pressure during exhalation (above a predetermined threshold) indicates exhalation through the mouth. Exhalation through the mouth renders VO 2 measurement and VCO 2 measurement invalid. Thus, within the time window in which mouth exhalation is detected (mouth pressure exceeding the threshold), the processor (60) will discard the acquired VO 2 measurement and VCO 2 measurement. Discarding measurements that include mouth breathing provides an accurate determination of the subject's nocturnal metabolic rate. For example, the acquired VO 2 measurement and VCO 2 measurement (and the corresponding EE values and RQ values derived therefrom) will not be displayed to the user.

[0030] As explained below, in some embodiments, the processor (60) is configured to: in response to a pressure change detected at or near the mouth with each breath (indicating oral breathing), discard O 2 concentration measurements and CO 2 concentration measurements. For example, for each breath (e.g., one or more breaths), determine O 2 concentration measurements and CO 2 concentration measurements. In response to a given breath among one or more breaths being determined to include oral breathing, discard the O 2 concentration and CO 2 concentration (which will not be used for further analysis and measurement of O 2 consumption and / or CO 2 production). In other words, measure O 2 consumption VO 2 and / or CO 2 production VO 2 only for breaths in which the exhaled gas is from the subject's nasal airway. In some embodiments, for all breaths (regardless of the presence of oral breathing), measure O 2 consumption VO 2 and / or CO 2 production VCO 2 . In these embodiments, the VO 2 and VCO 2 corresponding to oral breathing in the measurements of energy consumption EE and respiratory quotient RQ are subsequently discarded.

[0031] Figures 2B to 2C Illustrates an example of an interface device 80 according to one or more embodiments. The interface device 80 is a nasal interface including two prongs 205 and 207 that are configured to fit into the subject's nostrils and form a seal with the subject's nasal cavity. The interface device 80 includes a valve 85 that is configured to direct ambient gas to the subject's airway (as shown by arrow A in Figure 2C ). The valve 85 can be a passive inhalation valve (e.g., a one-way valve, a check valve, a non-return valve, etc.). An active valve can be considered compatible with the embodiments of the present disclosure. In operation, inhaled gas (e.g., ambient air) enters the one-way inhalation valve 85 and enters the nose (through the prong as shown by arrow B). During exhalation, the valve closes and the gas is diverted to a tube leading to a mixing chamber (not shown) (as shown by arrow C in Figure 2C ).

[0032] Back to Figure 1, System 100 includes a mixing chamber 30 operably connected to a subject interface 90. The mixing chamber 30 is configured to collect all or part of the exhaled gas. In some embodiments, the mixing chamber 30 is configured to include one or more sensors 40 for measuring gas parameters of the exhaled gas within the mixing chamber. For example, O 2 concentration, CO 2 concentration, flow rate, volume, pressure, etc.

[0033] One or more processors 60 are configured to provide information processing capabilities in System 100. Thus, one or more processors 60 may include one or more digital processors, one or more analog processors, one or more digital circuits designed to process information, one or more analog circuits designed to process information, state machines, and / or other mechanisms for electronically processing information. In some embodiments, one or more processors 60 are operably connected to sensors (40), mixing chamber 30, subject interface 90, user interface 120, and / or other components of System 100. Although one or more processors 60 are shown as a single entity in Figure 1 , this is for illustrative purposes only. In some implementations, one or more processors 60 include multiple processing units. These processing units may be physically located within the same device (e.g., sensors (40), mixing chamber 30, subject interface 90, user interface 120, etc.), or one or more processors 60 may represent the processing functions of multiple devices that cooperate with System 100 and are located external to System 100 (e.g., in the cloud). In some embodiments, one or more processors (60) may represent the processing functions of multiple devices located within and / or outside System 100 (e.g., communicatively coupled via network 150).

[0034] One or more processors 60 are configured to execute one or more computer program components. The one or more computer program components may include one or more of the following: parameter component 62, metabolic state component 64, feedback component 66, and / or other components. Processor 60 may be configured to execute components 62, 64, and 66 through software, hardware, firmware, some combination of software, hardware, and / or firmware; and / or through other mechanisms for configuring the processing capabilities on one or more processors 60.

[0035] It should be appreciated that although components 62, 64, and 66 are shown in Figure 1are shown as being co-located within a single processing unit, but in implementations where the processor 60 includes multiple processing units, one or more of the components 62, 64, and 66 may be located remotely from the other components. Since any one of the components 62, 64, and 66 may provide more or less functionality than that described, the description of the functionality provided by the different components 62, 64, and 66 described below is for illustrative purposes and is not intended to be limiting. For example, one or more of the components 62, 64, and 66 may be removed, and some or all of their functionality may be provided by other components 62, 64, and / or 66. As another example, the processor 60 may be configured to execute one or more additional components that may execute some or all of the functionality attributed to one of the components 62, 64, and / or 66 below.

[0036] In some embodiments, the parameter component 62 is configured to receive, determine, and / or obtain one or more parameters (e.g., from components within or outside the system 100). Based on the output signals from one or more sensors 40, one or more parameters may be determined. In some embodiments, the parameter component 62 is configured to determine one or more respiratory parameters related to the respiration of the subject 70, one or more parameters of the breathable gas within the system 100 (e.g., parameters related to the flow rate of the breathable gas delivered by the breathing device), one or more physiological parameters of the subject 70, and / or other parameters. Respiratory parameters related to the respiration of the subject 70 may include the start and / or end of each breath. In some embodiments, the respiratory parameters may include tidal volume, timing (e.g., start and / or end of inhalation, start and / or end of exhalation, etc.), respiratory rate, duration (e.g., duration of inhalation, duration of exhalation, duration of a single respiratory cycle, etc.), respiratory airflow, respiratory effort, respiratory frequency, and / or other respiratory parameters. One or more gas parameters of the breathable gas flow delivered to the subject may include, for example, one or more of the following: flow rate, heart rate, volume, pressure, humidity, temperature, acceleration, velocity, and / or other gas parameters. Physiological parameters may include oximetry parameters, pulse, temperature, blood pressure, movement, and / or other physiological parameters.

[0037] In some embodiments, parameter component 62 is configured to determine the flow rate of the exhaled gas based on the output signal from one or more sensors 40 (e.g., flow sensor 42). In some embodiments, parameter component 62 is configured to determine the inhalation flow rate, exhalation flow rate, and / or other gas flow rates within the subject interface 90 (or interface appliance 80). In some embodiments, the entire exhalation flow rate is determined. As described above, interface appliance 80 is configured to form a seal with the nostrils to allow collection of all exhaled gas. In some embodiments, parameter component 62 is configured to determine the flow rate of a portion of the exhaled gas. For example, in some embodiments, the exhaled gas is sampled (after all exhaled gas has been collected). For example, in some embodiments, a constant proportion of the sample stream is directed to a mixing chamber for further measurement (e.g., O 2 concentration measurement and CO 2 concentration measurement). In some embodiments, parameter component 62 is configured to determine the volume of inhaled air and / or exhaled air, for example, based on the output signal from a volume sensor within the subject interface 90, mixing chamber 30, and / or volume sensors at other locations inside or outside the system 100. In some embodiments, the volume of the inhaled gas and / or exhaled gas can be determined based on the output signal from the flow rate sensor 42.

[0038] In some embodiments, parameter component 62 is configured to determine the pressure at one or more locations inside or outside the system 100. In some embodiments, parameter component 62 is configured to determine the pressure at or near the subject's mouth. In some embodiments, the pressure can be determined based on the output signal from one or more sensors 40 (e.g., pressure sensor 44). In some embodiments, parameter component 62 is configured to determine the change in pressure at or near the subject's mouth.

[0039] In some embodiments, parameter component 62 is configured to measure the O 2 concentration in the subject's exhaled gas and / or inhaled gas. In some embodiments, parameter component 62 is configured to measure the O 2 concentration in a portion of the exhaled gas in the mixing chamber. In some embodiments, the O 2 concentration is measured based on the output signal from the O 2 sensor 45. As described above, the O 2 sensor can be located in the mixing chamber or at other locations in the interface appliance. In some embodiments, parameter component 62 is configured to measure the CO 2 concentration in the exhaled gas from the subject. In some embodiments, parameter component 62 is configured to measure the CO 2 concentration in a portion of the exhaled gas in the mixing chamber. In some embodiments, the CO2 The concentration is measured based on the output signal from the CO 2 sensor. As described above, the CO 2 sensor can be located in the mixing chamber or in other locations of the interface appliance. In some embodiments, the parameter component 62 is configured to: in response to detecting a pressure change at or near the mouth (indicating mouth breathing), discard the O 2 concentration measurement and the CO 2 concentration measurement. For example, in some embodiments, for each breath (e.g., one or more breaths), the parameter component measures the O 2 concentration and the CO 2 concentration. If it is determined that a given breath in the respiration includes mouth breathing, then discard the O 2 concentration and the CO 2 concentration of the given breath (not used for further analysis and measurement of O 2 consumption and / or CO 2 production). In other words, measure O 2 consumption and / or CO 2 production only for breaths in which the exhaled gas comes from the nasal airway of the subject. In some embodiments, for all breaths (regardless of the presence of mouth breathing), measure the O 2 consumption VO 2 and / or CO 2 production VCO 2 . In these embodiments, in the measurement of energy consumption EE and respiratory quotient RQ, discard the VO 2 and VCO 2 corresponding to mouth breathing (based on the pressure sensor output).

[0040] In some embodiments, the metabolic state component 64 is configured to determine the CO 2 production (VCO 2 ) in the exhaled gas based on the determined CO 2 concentration in the mixing chamber. For example, in some embodiments, VCO 2 can be calculated as the carbon dioxide production rate in milliliters per minute. In some embodiments, the metabolic state component 64 is configured to determine the O 2 consumption VO 2 of the subject. In some embodiments, based on the determined O 2 concentration in the mixing chamber, the volume of inhaled air, the volume of exhaled air, and the O 2 concentration in the inhaled gas, determine the O 2 consumption VO 2 .

[0041] In some embodiments, the metabolic state component 64 is configured to be based on VO2 Measurement and VCO 2 Measurements are made to calculate the energy expenditure EE and the respiratory quotient RQ. In some embodiments, the EE can be used to evaluate the caloric needs of a subject. The RQ can be used to provide information about the macronutrients (carbohydrates, fats, proteins) that are primarily used to produce energy. In some embodiments, the respiratory quotient RQ is the following ratio: VCO 2 / VO 2 . In some embodiments, the energy expenditure EE (metabolic rate) can be calculated using the following formula:

[0042] Metabolic rate (kcal / day) = 1.44(3.94VO 2 + 1.11VCO 2 )

[0043] where VO 2 is the oxygen consumption in milliliters per minute and VCO 2 is the carbon dioxide production rate in milliliters per minute. For units of calories / minute, the formula can also be written as:

[0044] Metabolic rate (cal / min) = 3.94VO 2 + 1.11VCO 2 .

[0045] In some embodiments, the feedback component 66 is configured to display the measured parameters (e.g., VO 2 , VCO 2 , EE, RQ, and / or other parameters determined by components 62 and 64). The measurements and recommendations can be displayed via a graphical interface (e.g., user interface 120, dedicated display, laptop computer, smart phone, etc.). In some embodiments, the feedback component 66 is configured to provide recommendations regarding optimal nutrition and activity behaviors for managing weight (e.g., based on the measured diet and / or activity and goals set by the user (e.g., losing weight, optimizing physical performance)).

[0046] Figure 3 Illustrates an example 300 of a nocturnal metabolic monitoring system according to one or more embodiments. In this example, ambient air 302 is directed to the subject's nose 304 (e.g., via a valve-equipped subject interface similar to Figure 1 ). The exhaled gas from the subject's nose is directed to a mixing chamber 30 where the O 2 concentration and the CO 2 concentration are measured. The processor 60 determines VO 2 and VCO based on the O 2 concentration and the CO 2 concentration measured in the mixing chamber 302 , EE, and RQ. Using pressure sensor 44, the pressure change at or near the mouth 310 is measured to detect mouth breathing. To better determine the metabolic rate, measurements including mouth breathing are discarded.

[0047] Figure 4 FIG. 400 illustrates an example of a nocturnal metabolic monitoring system according to one or more embodiments. In this example, ambient air 302 is directed to the subject's nose 304. The collected exhaled gas is sampled (after all exhaled gas has been collected), and the sample 405 is directed to mixing chamber 30 for further measurement. In some embodiments, a constant proportion of the air stream is collected in the mixing chamber. In some cases, 2% of the total exhaled gas is directed to mixing chamber 30, where O 2 concentration and CO 2 concentration are measured. Based on the O 2 concentration and CO2 concentration measured in mixing chamber 30, processor 60 determines VO 2 , VCO 2 , EE, and RQ. Using pressure sensor 44, the pressure change at or near the mouth 310 is measured to detect mouth breathing. To better determine the metabolic rate, measurements including mouth breathing are discarded. Figure 3 and Figure 4 The difference between the embodiments in Figure 3 is that in the embodiment of 2 , all exhaled gas enters the mixing chamber, where O 2 measurement and CO Figure 4 measurement are performed; in the embodiment of 2 , a sample of a certain proportion of the exhaled gas (i.e., a fixed percentage of the total flow at any given time) enters the mixing chamber, and the rest goes directly into the environment. Both configurations allow for VO 2 measurement and VCO

[0048] The user interface 120 is configured to provide an interface between the system 100 and the subject 70 and / or other users, through which the subject 70 and / or other users can provide information to and receive information from the system 100. Other users can include, for example, caregivers, doctors, and / or other users. This enables the communication of data, cues, results, and / or instructions, as well as any other communicable items (collectively referred to as "information") between the user (e.g., the subject 70), the processor 60, and / or other components of the system 100. As another example, sleep stages, sleep duration, respiratory feature distribution, treatment information feedback, the respiratory rate of the subject 70, and / or other information can be displayed to the user (e.g., the subject 70) via the user interface 120. Examples of interface devices suitable for inclusion in the user interface 120 include keypads, buttons, switches, keyboards, knobs, joysticks, display screens, touchscreens, speakers, microphones, indicator lights, audible alarms, printers, haptic feedback devices, and / or other interface devices. In one embodiment, the user interface 120 includes a plurality of individual interfaces.

[0049] It should be understood that the present disclosure also contemplates other communication technologies (hardwired or wireless) as the user interface 120. For example, the present disclosure contemplates that the user interface 120 can be integrated with a removable storage interface provided by the electronic storage 130. In this example, information can be loaded into the system 100 from a removable storage (e.g., smart card, flash drive, removable disk, etc.) that enables one or more users to customize the implementation of the system 100. Other exemplary input devices and technologies suitable for use as the user interface 120 with the system 100 include, but are not limited to, RS-232 ports, RF links, IR links, modems (telephone, cable, etc.). In short, the present disclosure contemplates any technology for communicating information through the system 100 as the user interface 120.

[0050] In some embodiments, electronic storage 130 includes an electronic storage medium that stores information electronically. The electronic storage medium of electronic storage 130 may include system storage provided integrally (i.e., substantially non-removable) with system 100, and / or one or both of removable storage removably connected to system 100 via, for example, a port (e.g., a USB port, a FireWire port, etc.) or a drive (e.g., a disk drive, etc.). Electronic storage 130 may include one or more of the following: optically readable storage media (e.g., optical discs, etc.), magnetically readable storage media (e.g., magnetic tapes, magnetic hard disk drives, floppy disk drives, etc.), charge-based storage media (e.g., EEPROM, RAM, etc.), solid-state storage media (e.g., flash drives, etc.), and / or other electrically readable storage media. Electronic memory 130 may store software algorithms, information determined by one or more processors 60, information received via user interface 120, and / or other information that enables system 100 to operate properly. Electronic storage 130 may be a separate component within system 100 (in whole or in part), or electronic storage 130 may be provided integrally (in whole or in part) with one or more other components of system 100 (e.g., user interface 120, one or more processors 60, etc.).

[0051] Network 150 may include the Internet and / or other networks, intranets, PANs (Personal Area Networks), LANs (Local Area Networks), WANs (Wide Area Networks), SANs (Storage Area Networks), MANs (Metropolitan Area Networks), near-field communication, frequency (RF) links, Bluetooth, Wi-Fi, Li-Fi, cellular communication networks, the public switched telephone network, and / or any type of wired or wireless network. It should be understood that this is not restrictive, and the scope of the present disclosure includes embodiments in which the components of system 100 are operably linked via some other communication medium. In some cases, the network is a secure local area network, such as a wired Ethernet network behind a firewall.

[0052] Information determined by one or more processors 60 and / or stored by electronic storage 130 may include information related to sensor measurements, the respiration of subject 70, metabolic rate, feedback, and / or other information. Information stored by electronic storage 130 may be viewed via user interface 120, by connection (wired and / or wireless) to a separate computer, and / or via other means. Information stored by electronic storage 130 may be used, for example, to adjust treatment settings, by a doctor to make medical decisions, and / or for other purposes. In some embodiments, system 100 may include a wireless transmitter (not shown), and information determined by one or more processors 30, information stored by electronic storage 130, and / or other information may be communicated, for example, via a wireless network to a caregiver. As a non-limiting example, a caregiver may receive usage information, subject status, and / or other information, allowing the caregiver to remotely track treatment delivered by system 100.

[0053] In some embodiments, in a treatment device (e.g., a sensor, a respiratory treatment device, etc.) including the components of system 100 described above, the processing functions of system 100 described herein are implemented locally. In some embodiments, the processing functions of system 100 described herein are implemented external to system 100 (e.g., remotely implemented by one or more devices connected to system 100 via network 100). In some embodiments, the processing functions described herein may be a combination of processing functions executed locally and processing functions executed remotely.

[0054] Figure 5 A nocturnal metabolic monitoring method 500 is illustrated. The operations of method 500 given below are intended to be illustrative. In some embodiments, method 500 may be implemented using one or more additional operations not described and / or without one or more of the operations discussed. Additionally, the order in which the operations of method 500 are illustrated and described below is not restrictive. Figure 5 is illustrated and in the order described below is not restrictive.

[0055] In some embodiments, method 500 may be implemented in one or more processing devices (e.g., a digital processor, an analog processor, a digital circuit designed to process information, an analog circuit designed to process information, a state machine, and / or other mechanism for electronically processing information). The one or more processing devices may include one or more devices that execute some or all of the operations of method 500 in response to instructions stored electronically on an electronic storage medium. The one or more processing devices may include one or more devices configured by hardware, firmware, and / or software that is specifically designed to execute one or more of the operations of method 500.

[0056] At operation 502, breathable gas is provided to the nasal airway (70) of the subject. In some embodiments, operation 502 is performed by a subject interface that is the same as or similar to the subject interface 90 ( Figure 1 shown in and described herein).

[0057] At operation 504, exhaled gas is collected from the nasal airway. In some embodiments, operation 504 is performed by a subject interface that is the same as or similar to the subject interface 90 ( Figure 1 shown in and described herein).

[0058] At operation 506, at least a portion of the exhaled breathing gas is collected. In some embodiments, operation 506 is performed by a mixing chamber that is the same as or similar to the mixing chamber 30 ( Figure 1 shown in and described herein).

[0059] At operation 508, an output signal related to one or more gas parameters is received, the one or more gas parameters being related to the gas inhaled and exhaled by the subject during one or more breaths. In some embodiments, operation 508 is performed by a plurality of sensors that are the same as or similar to one or more sensors 40 ( Figure 1 shown in and described herein).

[0060] At operation 510, based on the output signal, the gas flow rate in the subject interface during one or more breaths is determined. In some embodiments, operation 510 is performed by a physical computer processor that is the same as or similar to one or more processors 60 ( Figure 1 shown in and described herein).

[0061] At operation 512, based on the output signal from the sensor, a pressure change near the subject's mouth during one or more breaths is determined to detect the subject's mouth breathing. In some embodiments, operation 512 is performed by a physical computer processor that is the same as or similar to one or more processors 60 ( Figure 1 shown in and described herein).

[0062] At operation 514, based on the output signal from the sensor, an O 2 concentration measurement and a CO 2 concentration measurement of a portion of the exhaled gas in the mixing chamber are determined. Concentration measurements corresponding to mouth breathing are discarded. In some embodiments, operation 514 is performed by a physical computer processor that is the same as or similar to one or more processors 60 ( Figure 1 shown in and described herein).

[0063] At operation 516, the oxygen consumption rate VO of the subject is determined2 and the carbon dioxide production rate VCO 2 . In some embodiments, based on the measured gas flow rate, the determined carbon dioxide concentration of the exhaled gas in the mixing chamber, and the determined oxygen concentration of the exhaled gas in the mixing chamber, the oxygen consumption rate VO of the subject is determined 2 and the carbon dioxide production rate VCO 2 . In some embodiments, operation 516 is performed by a physical computer processor that is the same as or similar to the one or more processors 60( Figure 1 shown in and described herein).

[0064] In a claim, any reference numeral placed in parentheses shall not be construed as limiting the claim. The words "comprising" or "including" do not exclude the presence of elements or steps other than those listed in the claim. In a device claim enumerating several devices, several of these devices may be implemented by the same item of hardware. The word "a" or "an" before an element does not exclude the presence of a plurality of such elements. In any device claim enumerating several devices, several of these devices may be implemented by the same item of hardware. The fact that certain elements are recited in mutually different dependent claims does not mean that these elements cannot be used in combination.

[0065] Although the description provided above gives details for illustrative purposes based on currently considered to be the most practical and preferred embodiments, it should be understood that such details are for that purpose only, and the present disclosure is not limited to the embodiments explicitly disclosed, but rather is intended to cover modifications and equivalent arrangements falling within the spirit and scope of the appended claims. For example, it should be understood that the present disclosure contemplates that, to the extent possible, one or more features of any embodiment may be combined with one or more features of any other embodiment.

Claims

1. A metabolic monitoring system (100), comprising: an interface device (80) configured to collect exhaled gas from the nasal airway of a subject (70); a mixing chamber (30) operably connected to the interface device, the mixing chamber being configured to receive at least a portion of the exhaled gas from the interface device; a plurality of sensors (40) configured to output signals related to one or more gas parameters, the one or more gas parameters being related to the inhaled and exhaled gases of the subject during one or more breaths; and one or more physical computer processors (60) operably connected to the sensors to receive the output signals, the one or more physical computer processors being configured by computer-readable instructions to: determine a gas flow rate in the interface device during the one or more breaths based on the output signals from the sensors; determine a pressure change near the subject's mouth during the one or more breaths based on the output signals from the sensors to detect mouth breathing of the subject; Based on the output signal from the sensor, determine the concentration measurement of the portion of the exhaled gas in the mixing chamber for O 2 and CO 2 and discard the concentration measurements corresponding to oral breathing; and Based on the determined gas flow rate, the determined carbon dioxide concentration of the exhaled gas in the mixing chamber, and the determined oxygen concentration of the exhaled gas in the mixing chamber, determine the oxygen consumption rate VO 2 and the carbon dioxide production rate VCO 2 .

2. The system according to claim 1, wherein the one or more physical computer processors are configured to: based on the determined VO 2 and VCO 2 , determine the metabolic state of the subject.

3. The system according to claim 1, wherein the one or more physical computer processors are configured to: based on the determined VO 2 and VCO 2 , measure the energy consumption (EE) and / or the respiratory quotient (RQ).

4. The system according to claim 1, wherein the interface device is configured to seal the subject's nasal cavity from the atmosphere.

5. The system according to claim 1, wherein the system is configured to monitor the subject's metabolism while the subject is inactive.

6. The system according to claim 1, wherein the sensor comprises a pressure sensor (44) located near the mouth of the subject, the pressure sensor being configured to output a pressure signal related to the pressure near the mouth of the subject; wherein based on the output pressure signal from the pressure sensor, the concentration measurements of O 2 and CO 2 are discarded.

7. The system according to claim 1, wherein the interface device is configured to provide breathable gas to the subject's nasal airway.

8. A metabolic monitoring method, comprising: collecting exhaled gas from the nasal airway of a subject through an interface device; receiving at least a portion of the exhaled gas from the interface device in a mixing chamber, the mixing chamber being operably connected to the interface device; receiving output signals related to one or more gas parameters from a plurality of sensors, the one or more gas parameters being related to the inhaled and exhaled gases of the subject during one or more breaths; determining, by one or more physical computer processors, a gas flow rate in a subject interface during the one or more breaths based on the output signals from the sensors; determining, by one or more physical computer processors, a pressure change near the subject's mouth during the one or more breaths based on the output signals from the sensors to detect mouth breathing of the subject; Determine, by one or more physical computer processors, a concentration measurement of the portion of the exhaled gas in the mixing chamber of O 2 and CO 2 based on the output signal from the sensor, and discard concentration measurements corresponding to oral breathing; and Determine the oxygen consumption rate VO of the subject based on the determined gas flow rate, the determined carbon dioxide concentration of the exhaled gas in the mixing chamber, and the determined oxygen concentration of the exhaled gas in the mixing chamber, by one or more physical computer processors 2 and the carbon dioxide production rate VCO 2 .

9. The method according to claim 8, further comprising: Based on the determined VO 2 and VCO 2 to determine the metabolic status of the subject.

10. The method according to claim 8, further comprising: Based on the determined VO 2 and VCO 2 to measure the energy expenditure (EE) and / or the respiratory quotient (RQ).

11. The method according to claim 8, further comprising: sealing the subject's nasal cavity from the atmosphere through the interface device.

12. The method according to claim 8, further comprising: monitoring the subject's metabolism while the subject is inactive.

13. The method according to claim 8, further comprising: Receive an output pressure signal related to the pressure near the mouth of the subject from a pressure sensor (44) located near the mouth of the subject, wherein based on the output pressure signal from the pressure sensor, discard the measurement of the concentration of O 2 and CO 2 thereof.

14. The method according to claim 8, further comprising: providing breathable gas to the subject's nasal airway through the interface device.

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