Abstract: Methods, systems and techniques for the accurate measurement breath-borne biomarkers are disclosed. Such methods, systems and techniques may be used for the purposes of detection and/or measurement in breath samples of biomarkers.

Abstract: The invention relates to a breath sensing devices for a portable apparatus, in particular a portable telecommunication device or a wearable device, the sensing device comprising an acoustic wave sensing means, like a microphone; and a gas sensing means, The invention furthermore relates to an electronic device comprising such a sensing device. In addition, methods are provided that allow calibrating a gas volume based on an output signal of an acoustic wave sensing means.

Abstract: Methods of and devices for detecting a measurable characteristic of the gas sample. The methods and devices are able to detect a value of or a change of measurable characteristic (e.g., such as chemical concentrations), a change of chemical compositions and/or biological responses of a living organism that are induced by a stressor. The biological responses are able to include cellular stress, damage, and immune responses. The stressor is able to include an exposure to ionizing radiation. The effects of the stressors are able to be monitored in terms of changes in the chemical concentrations and chemical compositions in an exhaled breath. The chemicals are able to function as bio-markers. The chemicals that are to be monitored are able to include nitric oxide, carbon monoxide, carbon dioxide, ethane, and other molecules related to specific disease resulting from the stressor.

Abstract: A cartridge device (10) for collecting and analysing a breath condensate is disclosed. The device (10) comprises a condensation zone (12) to condense exhaled breath from a subject and cooling means operably connected to the condensation zone (12). The device includes further discrete regions (13) for detection of analyte and measurement of analyte. The condensation zone (12) has a fluid exit connecting the condensation zone (12) to the discrete regions (13).

Abstract: Methods, apparatuses, and systems associated with aerosol collection devices (such as, but not limited to, breath-aerosol collector devices, breathalyzers) are provided. An example aerosol collection device includes a sample transfer adapter configured to receive a sample and a device body connected to the sample transfer adapter. In some examples, the device body defines a flow channel that guides the sample to a filter component, and the filter component contains a buffer solution.

Abstract: Methods, apparatuses, and systems associated with aerosol collection devices (such as, but not limited to, breath-aerosol collector devices, breathalyzers) are provided. An example aerosol collection device includes a sample transfer adapter configured to receive a sample and a device body connected to the sample transfer adapter. In some examples, the device body defines a flow channel that guides the sample to a filter component, and the filter component contains a buffer solution.

Abstract: Methods, apparatuses, and systems associated with aerosol collection devices (such as, but not limited to, breath-aerosol collector devices, breathalyzers) are provided. An example aerosol collection device includes a sample transfer adapter configured to receive a sample and a device body connected to the sample transfer adapter. In some examples, the device body defines a flow channel that guides the sample to a filter component, and the filter component contains a buffer solution.

Abstract: Breath sensor apparatus and methods of use are described herein where a flow control apparatus may generally comprise a sampling chamber defining a volume and one or more openings into the sampling chamber, at least one sensor in fluid communication with the sampling chamber, wherein the at least one sensor is configured to detect the analyte. The sampling chamber may also be configured to receive the breath sample into the sampling chamber and into contact with the at least one sensor via diffusion into the sampling chamber.

Abstract: A breath analysis system comprises a breath analysis device having a semiconductor sensor, such as a metal oxide semiconductor sensor, that needs to be heated or otherwise prepared before a breath test can be performed. To reduce or avoid a user-perceived delay (typically multiple minutes) associated with the sensor preparation operation, the system predictively initiates a sensor preparation operation based on a determination or prediction of whether the user is in an adequate state to perform a breath test. This prediction may be based on one or more factors, such as the current time, whether the breath analysis device is within wireless communication (e.g., Bluetooth) range of the user's smartphone, data reflective of the user's location and/or activity, etc.

Abstract: The embodiments disclose a method including: monitoring vital signs of an opioid patient, providing chemical identifying and concentration detection of a drug the opioid patient is preparing to inject, analyzing the opioid patient's vital signs to determine an overdose condition regardless of the patient consciousness state, tracking the opioid patient's GPS location, transmitting automatically an overdose emergency alert; sending the automatic opioid overdose emergency alert to the closest first responders, and providing the opioid patient's ID, GPS location, vital signs, potential drug overdosed, and known drug use in the automatic opioid overdose emergency alert to the closest first responders.

Abstract: Signal output apparatus and concentration measurement system has a light receiving unit and an interface unit provided at a support unit. Light receiving unit receives infrared rays emitted to a measurement target substance, and outputs a detection signal according to received infrared rays. Storage unit stores a parameter according to a characteristic of at least one of a plurality of components including the light receiving unit, the parameter being used for concentration computation of the measurement target substance, as a calibration parameter. Interface unit outputs an output signal including a calibration parameter signal according to the calibration parameter input from the storage unit and a signal based on the detection signal input from the light receiving unit to a signal computation processing unit, without executing the concentration computation.

Abstract: A breath testing apparatus is provided to test hydrogen sulfide and other parameters in exhaled breath of a patient. A patient sample input for receiving exhaled breath from a patient is provided, in addition to an atmospheric input for receiving atmospheric air. A valve is coupled to said patient sample input and said atmospheric input, and first and second pathways are provided from said valve to a hydrogen sulfide sensor block and a second sensor block.

Abstract: Methods and systems are disclosed for the detecting of whether a subject has a lung disorder such as asthma, tuberculosis or lung cancer. Monitoring the subject's health and prognosis is also disclosed.

Abstract: A sensor arrangement includes a reaction subassembly having a housing and a detector subassembly. The housing is a layered component arrangement encompassing a luminophore-containing reaction laminate excitable, by irradiation with a first electromagnetic radiation of a first wavelength, to emit a second electromagnetic radiation of a second wavelength different from the first wavelength; and a temperature-detection laminate emitting an infrared radiation. The housing includes an opening for introducing a fluid, a reaction window and a temperature-sensing window. The reaction window transmits the first and second electromagnetic radiation, and the temperature-sensing window is penetrable by infrared radiation.

Abstract: A system comprises a mouth piece to receive exhaled air; a breath chamber to receive exhaled air; a valve to direct exhaled air along a desired flow path, direct purge gas along a desired flow path, control the rate of flow of purge gas, control the rate of flow of exhaled air, block the flow of purge gas, and/or block the flow of exhaled air; a source of purge gas; a CO2 cartridge to remove CO2; a water cartridge to remove water; a breath cartridge to capture VOCs from exhaled air; a temperature control system to control the temperature of CO2 cartridge, a water cartridge, and/or a breath cartridge; a cryostat to contain and limit heat flow to a cryogenic liquid; a flow meter designed to measure the flow of exhaled air and/or purge gas; and a pressure transducer to measure a pressure, a flow rate, and/or a flow volume.

Abstract: A water filter system for a CO2 sampling line positioned between a patient and a patient monitor to receive patient exhalation. The filter system includes at least one hydrophobic filter that adsorbs and prevents water from reaching the patient monitor. Alternatively, the filter system may include both a hydrophobic filter and a hydrophilic filter and optionally a desiccant.

Abstract: The invention relates to a spirometer (1) comprising a MEMS-based thermal fluid flow sensor (13, 13.1, 13.2) for generating a signal in response to a fluid flow generated during inhalation or exhalation; and a microcontroller (14) for calculating the fluid flow from the signal generated by the flow sensor (13, 13.1, 13.2). The spirometer (1) may be connected to other devices, such as a smartphone or a personal computer or any other computing unit which is adapted to collect, store, analyse, exchange and/or display data. The invention further describes the use of the spirometer (1) in measuring a user's lung performance and/or monitoring it over time.

Abstract: Methods of and devices for detecting a measurable characteristic of the gas sample. The methods and devices are able to detect a value of or a change of measurable characteristic (e.g., such as chemical concentrations), a change of chemical compositions and/or biological responses of a living organism that are induced by a stressor. The biological responses are able to include cellular stress, damage, and immune responses. The stressor is able to include an exposure to ionizing radiation. The effects of the stressors are able to be monitored in terms of changes in the chemical concentrations and chemical compositions in an exhaled breath. The chemicals are able to function as bio-markers. The chemicals that are to be monitored are able to include nitric oxide, carbon monoxide, carbon dioxide, ethane, and other molecules related to specific disease resulting from the stressor.

Abstract: To provide a mask capable of reducing a load of a patient while suppressing lowering of accuracy at which a subject's exhaled air is measured. A mask to be put on a subject's face includes a mask body portion demarcating an internal space in a state of covering part of the subject's face and a cup-shaped nasal cup covering a subject's nose in a state of being arranged inside the internal space, in which the nasal cup includes a first wall portion covering the subject's nose, a second wall portion arranged under the subject's nostrils, and an exhaled air discharge portion guiding an exhaled air from the subject's nose to an exhaled air sensor, and at least part of the exhaled air from the subject's nose is guided toward the exhaled air discharge portion by the second guide portion in a state where the nasal cup covers the subject's nose.

Abstract: Systems and methods are disclosed configured to detect impairment issues, and via an interlock device, inhibit operation of an item of equipment when impairment is detected. The interlock device may comprise a solid state relay, an electromechanical relay, and/or a solenoid. The interlock device may perform power isolation and/or may use a mechanism, such as a rotating cam or gear, to immobilize a control and/or other components. Based on detected impairment, a determination is made as to whether the interlock is to be activated or deactivated.

Abstract: Techniques are described for a non-invasive detection of a health condition of an organ. In an example, the electrical conductivity of the organ reflects the organ's health of. An inductive damping sensor can be used to detect the organ's electrical conductivity and, thus, its health. The inductive damping sensor can be placed in proximity of the organ such as the organ is within the magnetic field generated based on a coil of the inductive damping sensor. The conductivity of the organ impacts the inductance and the resistance of the coil. Hence, the inductance and/or resistance of the coil can be measured, where the measurements can be associated with the health of the organ.

Abstract: A cloud platform comprises a receiving unit and a processing unit. The receiving unit is configured to receive at least one user respiration data set sent by at least one respirator device in at least one uploading cycle. The processing unit is configured to acquire a first user respiration data set sent by a user of one respirator device among at least one respirator device in one uploading cycle, statistically analyze the first user respiration data set on the basis of a stable state value set of the user, and send an alarm signal when the statistical analysis result is determined to be that the first user respiration data set meets a data exception standard. The disclosure provides an on-line user respiration data analysis solution in combination with disease diagnosis of an off-line respiration system, so that the worsening of a patient's conditions can be possibly found in time.

Abstract: A method of controlling a gas delivery apparatus including an apparatus controllable variable using an iterative algorithm to deliver a test gas (TG) for non-invasively determining a subject's pulmonary blood flow comprising iteratively generating and evaluating test values of a iterated variable based on an iterative algorithm in order output a test value of the iterated variable that meets a test criterion wherein iterative algorithm is characterized in that it defines a test mathematical relationship between the at least one apparatus controllable variable, the iterated variable and an end tidal concentration of test gas attained by setting the apparatus controllable variable, such that the iterative algorithm is determinative of whether iteration on the test value satisfies a test criterion or iteratively generates a progressively refined test value.

Abstract: A gas analyzer for measuring a respiratory gas component includes an emitter that transmits infrared (IR) radiation through a measurement chamber containing respiration gas, and at least one IR detector configured to receive at least a portion of the IR radiation transmitted through the measurement chamber and to generate radiation measurement data based on the received IR radiation. A light source is configured to emit light onto a color indicator, wherein the color indicator is one of a predefined set of colors. A color detector is configured to detect light reflected by a color indicator so as to identify color information. The controllers configured to determine a respiratory gas component concentration within the measurement chamber based on the color information and the radiation measurement data.

Abstract: A cold air supply device is applied to an entrance refrigerator. The cold air supply device includes a thermoelectric element forming a heat absorbing surface and a heat generating surface, a cold sink in contact with the heat absorbing surface, a heat absorption fan disposed above the cold sink, a heat sink in contact with the heat generating surface, a heat dissipation fan disposed below the heat sink, and an insulation material disposed between the cold sink and the heat sink to block heat transfer. The cold sink includes a sink body, and a plurality of heat exchange fins arranged on the upper surface of the sink body. Absorption pads are provided on both side edges of the sink body to absorb condensed water generated on the surface of the cold sink.

Abstract: A medical monitoring system for identifying an end-exhalation carbon dioxide value of enhanced clinical utility is described herein. The medical monitoring system can include a capnometer for generating an output corresponding to a time-series of exhaled carbon dioxide values from a patient during an exhalation and a processor programmed to analyze the exhalation. In some examples, the processor can also be programmed to identify a peak carbon dioxide value at an end of the exhalation, determine if the peak carbon dioxide value may have been higher if the exhalation had been prolonged, and provide an output responsive to said determination.

Abstract: A method and a system of deploying an ignition interlock device (IID). The method comprises receiving a time series of breath alcohol content (BrAC) measurements that are unitarily sourced from a pre-identified user, each BrAC measurement of the time series including an alveolar breath component and an interferent breath component; estimating a dissipation rate of alcohol attributable to the pre-identified user in accordance with the time series of BrAC measurements; determining, responsive to estimating the dissipation rate of alcohol, at least a subset of the BrAC measurements as being based on the alveolar breath component but not the interferent breath component; and performing one of triggering and not triggering the IID into a lockout state based on the at least a subset of the BrAC measurements.

Abstract: A flow sensor sub-assembly for sensing flow of a fluidic medicament is disclosed. The flow sensor sub-assembly includes a first spring contact and a second spring contact. The spring contacts are secured to a base that has a circuit for conducting an electrical signal to and from the spring contacts to a microprocessor. The first spring contact is in electrical communication with a first piezo element and the second spring contact is in electrical communication with a second piezo element. The first spring contact has a first contact force against the first piezo element and the second spring contact has a second contact force against the second piezo element, and the first and second contact forces are equivalent. A circuit board for interfacing to a flow sensor having a plurality of piezo elements for transmitting a flow signal indicative of flow of fluidic medicament is also disclosed.

Abstract: The invention relates to a sensor (1) for fastening to a multi-bracket appliance for the upper jaw (2), to a multi-bracket appliance for the lower jaw (3), to an aligner for the upper jaw (2?) and/or to an aligner for the lower jaw (3?), in order to measure the time span during which a force is applied to a pressure, tension and/or shear-force sensor (11) of the sensor (1), whereby the wearing duration of orthodontic elastics (4) for multi-bracket appliances (2, 3) and/or aligners (2?, 3?) can be monitored, the sensor (1) being a sensor that is independent of the multi-bracket appliance (2, 3) and the brackets (23) and including a timer, a microcontroller having a data memory, and an elastic holder (16) and/or elastic guide (17). The invention further relates to a system (5) for monitoring the wearing duration of orthodontic elastics, including the sensor (1), a multi-bracket apparatus or an aligner for the upper jaw (2, 2?) and the lower jaw (3, 3?), an elastic (4) and an external reading device.

Abstract: Some embodiments are directed to a self-contained breathing mask for measuring and monitoring the breath of a human subject. The mask may be lightweight, self-contained, and physically untethered to any test or measurement equipment, providing the subject full mobility, and allowing him/her to perform almost any daily activity during use. The mask may include integrated sensors for measuring properties of the subject's breath, over any length of time, providing respiratory information like breath count, rate and volume, oxygen consumption, and carbon dioxide production, as well as various biometric information.

Abstract: A sensing system includes a sensor including a flexible substrate and a graphene oxide sensing element deposited on the flexible substrate. The graphene oxide sensing element has first and second sides. First and second electrical connectors coupled to the first and second sides of the graphene oxide sensing element, respectively. A power source is coupled to the first and second electrical connectors of the sensor and is adapted to apply a constant voltage to the sensor. The sensing system also includes a measurement element measuring a current in the graphene oxide sensing element due to the constant voltage and a calculation element calculating an electrical resistance of the graphene oxide sensing element based on the electrical current and the constant voltage and calculating a condition at a location of the sensor based on a relationship between the electrical resistance and the condition for the graphene oxide sensing element.

Abstract: Methods and systems are described to obtain and analyze one or more gas samples from the breath of a person, and organizing the samples in a sample registry for subsequent analysis. This technique solves the various problems that are associated with targeting an individual breath for analysis, and allows for additional versatility and options in the analysis process.

Abstract: A method for sampling breath gas, includes collecting a first breath sample in a first bag. The first breath sample is an initial part of expired gas expired after inspiration. Additionally, the method includes collecting a second breath sample in a second bag. The second breath sample is a latter part of the expired gas. The method includes subtracting first mass spectral data obtained by mass spectroscopy of the first breath sample collected in the first bag from second mass spectral data obtained by mass spectroscopy of the second breath sample collected in the second bag.

Abstract: A device for collecting exhalation gas and aiding measurement of a trace component in the exhalation gas and the usage method thereof are disclosed. The device comprises an alveolar air bag for storing alveolar air collected from the breath of a subject, a cavity channel air bag for storing cavity channel air from the subject, a three-way pipe, and a mouthpiece. The three-way pipe comprises a first branch pipe, second branch pipe, and third branch pipe communicating with each other. The first branch pipe and the second branch pipe respectively extend in opposing directions along the same axis. The third branch pipe extends along a radial direction of the first branch pipe and the second branch pipe. The mouthpiece communicates with the first branch pipe. An air hole of the cavity channel air bag communicates with the second branch pipe.

Abstract: Techniques, devices and methods for discriminating a target from a background material without optimizing directly on the target are provided. The devices and methods can generate pass bands of single or multiple wavelengths of variable shape and intensity, and can also select and control the shape of the pass band profiles to improve the detection of targets of interest.

Abstract: An assembly and a method for measuring a gas concentration by means of absorption spectroscopy, in particular for capnometric measurement of the proportion of CO2 in breathing air in which IR light from a thermal light source is guided through a measuring cell with a gas mixture to be analyzed, and the concentration of the gas to be measured that is contained in the gas mixture is determined by measuring an attenuation of the light introduced into the measuring cell caused by absorption by the gas to be measured. The thermal light source is designed as an encapsulated micro-incandescent lamp with a light-generating coil.

Abstract: A respiration monitoring system has deformation transducers on a flexible substrate arranged to adhere to a patient's torso. A processor receives signals in channels from the transducers and processes them to eliminate, reduce or compensate for noise arising from patient motion artefacts, to provide an output representative of respiration. The transducers have a size and a mutual location on the substrate so that a first transducer can overlie at least part of the 10th rib and a second transducer can overlie at least part of the 11th rib or the abdomen, and the processor processes data from the first transducer as being primarily representative of rib distending respiration and from the second transducer as being primarily representative of either diaphragm respiration or patient motion artefacts.

Abstract: Use: detecting the presence of small concentrations of target gases.

Abstract: Apparatuses and methods are provided for quantifying an analyte in a gas or liquid phase. A light source with an emission spectrum overlapping an absorption of the analyte, and a pair of reflective mirrors located on an optical axis to form an optical cavity can be included. An off-axis photon detector can be configured as a fluorescence detector and located off the cavity axis and arranged to provide a first signal in response to fluorescence within the cavity. An axial photon detector can be located axially, and external, to the cavity and arranged to provide a second signal. The portion of the apparatus including the light source, the cavity, and the axial photon detector can be configured with a cavity-enhanced absorption spectrometer, and the portion of the apparatus including the off-axis photon detector can be configured with a cavity-enhanced laser-induced fluorescence (CELIF) spectrophotometer.

Abstract: Apparatus for quantifying the amount of re-breathing due to bedding materials. The re-breathing analyzer applies heated air to the material under test through an exhaust port in a probe and receives return air from an intake port in the probe. The exhaust and intake ports are placed to engage the material under test when the probe is in contact with the material. In one embodiment, the probe has a surface that is exposed through a top surface of a housing for the analyzer whereby the material under test is placed on the top surface for testing. The analyzer includes a differential temperature measuring instrument that determines the temperature of the return air, where an increase of the temperature of the return air above the temperature of the ambient air indicates the presence and quantity of re-breathing due to the material under test.

Abstract: The present disclosure provides a system that quantitatively tracks an individual's diet and exercise using smart devices (phones, watches, and other wearables). Unlike existing programs, which work in energy units (calories), the present system works in mass units (grams) and satisfies the fundamental physics law of conservation of mass. Food ingested is tracked as well as exercise in order to place the user on a quantitative, custom diet that safely and effectively results in weight loss. In addition to rigorously treating the problem of weight loss by addressing the physics that underlies diet and exercise, the system empirically learns about the user over time such that performance may be optimized.

Abstract: A method of identifying alveolar ventilation (VA) in a subject, the method comprising: (1) using a breathing circuit which, at exhalation, keeps exhaled gas separate from inhaled gas and at inhalation, when a first gas set (FGS) flow is less than the subject's minute ventilation (VE), results in a subject inhaling FGS first and then a second gas set (SGS), for the balance of inhalation; (2) setting the FGS flow at a rate greater that VE; (3) measuring an end tidal CO2 concentration at a steady state; (4) progressively lowering the FGS flow until a time equal to a recirculation time of CO2 in the subject; and (5) deriving VA as the rate of FGS flow at the intersection between an average PETCO2 in a steady state and a line fit to the PETCO2 values after the rise in PETCO2 values begins until the recirculation time.

Abstract: Embodiments herein include a breath sampling mask, systems, and related methods. In an embodiment, a breath sensing system is included. The breath sensing system can include a breath sampling mask. The breath sampling mask can include a mask housing configured to cover a portion of the face of a patient. The mask housing can define a breath receiving chamber. The breath sampling mask can include a chemical sensor element in fluid communication with the breath sampling mask, where the chemical sensor element can include a plurality of discrete binding detectors. The chemical sensor element can interface with a breath sample collected through the breath sampling mask. Other embodiments are also included herein.

Abstract: Techniques for determining a volume of exhaled CO2 as a function of time using side-stream capnography, including obtaining flow dynamics measurements of a subject from a flow sensor; obtaining CO2 concentration measurements of the subject from a side-stream CO2 monitor; determining a duration of time (?Tsl) for a sample of gas to flow from a reference point to the side-stream CO2 monitor; synchronizing in time the CO2 concentration measurement with the flow dynamics measurement, based on the determined ?Tsl; and determining a volume of CO2 exhaled as a function of time, based on the flow dynamics measurement and the synchronized CO2 concentration measurement.

Abstract: A system and method for generating a pulmonary dysfunction nourishment program, comprises a computing device configured to receive at least a respiratory volume collection relating to a user, generate at least a respiratory parameter of a plurality of respiratory parameter as a function of the respiratory volume collection, determine a pulmonary bundle element as a function of the at least respiratory parameter, identify at least an edible as a function of the pulmonary bundle element, wherein identifying comprises, obtaining a nourishment composition from an edible directory, determining a nourishment deficiency as a function of the pulmonary bundle element, and identifying the at least edible as a function of the nourishment composition, the nourishment deficiency, and an edible machine-learning model, and output a nourishment program as a function of the at least edible.

Abstract: A system and method for monitoring resuscitation and respiratory mechanics of a patient is provided. A pressure sensor detects air pressure within an air-flow path of a resuscitator and generates a first detection signal in response thereto. A flow-rate sensor detects the flow-rate within the air-flow path and generates a second detection signal In response thereto. A processor receives and processes the first and second detection signals using an algorithm to identify a ventilation rate, a lung pressure, and an air volume corresponding to the respiratory air. A report is generated of real-time feedback about respiration of the patient that includes the ventilation rate, lung pressure, and air volume.

Abstract: A breath collection device can detect changes associated with pathogenesis of a disease, such as COVID-19, including biomarkers of immune response for respiratory symptoms, central nervous system injury, and/or peripheral nervous system injury in user breath and/or odor. The breath collection device can detect concentrations of alcohol, acetone, and carbon monoxide in user breath samples. A breath sample can be received in an internal bladder of the device for sensor analysis. Concentrations of alcohol, acetone, and carbon monoxide can be determined by calibrated calculation. A detection method for alcohol, acetone, and carbon monoxide can provide a non-invasive, rapid, and selective detection of gases in a variety of applications in virus detection as well as agricultural and homeland security.

Abstract: A sensor arrangement (50) encompasses a reaction subassembly (72) having a housing (52) and having a detector subassembly (54), there being provided in the housing (52) a layered component arrangement (60) that encompasses: a luminophore-containing reaction laminate (62) that is excitable, by irradiation with a first electromagnetic radiation of a first wavelength, to emit a second electromagnetic radiation of a second wavelength different from the first wavelength; and a temperature-detection laminate (64) emitting an infrared radiation; the housing (52) comprising an opening (78a, 78b) through which a fluid is introducible; the housing (52) comprising a reaction window (66a) and a temperature-sensing window (66b) arranged physically remotely therefrom; the one reaction window (66a) transmitting the first (E1) and the second electromagnetic radiation (E2); and the temperature-sensing window (66b) being penetrable by infrared radiation (I); the detector subassembly (54) encompassing: a radiation source (

Abstract: A method of detecting hypoxia. Detecting hypoxia includes detecting, in exhaled breath, at least one indicator for hypoxia. The at least one indicator is selected from the group consisting of pentanal, 2-pentanone, 2-hexanone, 2-heptanone, 2-cyclopenten-1-one, and 4-butyrolactone.

Abstract: An apparatus and method for controlling the end tidal partial pressure of a gas X in a subject's lung, and to the use of such an apparatus and method for research, diagnostic and therapeutic purposes, wherein the method consists of: —obtaining input of a series of logistically attainable PetX values for a series of respective breaths: —determining an amount of gas X required to be inspired by the subject in an inspired gas to target the PetX for each of said respective breaths: and—controlling a gas delivery device to deliver the amount of gas in a volume of gas delivered to the subject in each of said respective breaths to target the respective PetX for that breath.