Device for measuring the humidity of breathing air

Abstract

The device disclosed herein is used to measure the humidity of respiratory air, and the device includes an inlet fluidly connected at the first end of a tubular body, and the tubular body defines an inner tube volume. The device further includes a condenser plate, which is fluidly connected to the second end of the tubular body to receive exhaled air. A partition wall between the first end and the second end divides the inner tube volume into a first chamber and a second chamber, and the second chamber provides a fluid passage to the condenser plate. The wall has a one-way valve passing through it, and the one-way valve allows respiratory air to pass from the first chamber to the second chamber. The device further includes one or more apertures in the wall of the tubular body of the first chamber, the aperture or each aperture fluidically links the sensor to the first chamber; and a relative humidity sensor, which is fluidly linked to the second chamber.

Description

Technical Field

[0001] The present invention relates to a device for measuring respiratory humidity, and in particular to a device that can also measure other parameters. The respiratory humidity measurement results are used alone or in combination with other parameters to identify, classify and longitudinally track diseases, including lung diseases. Background Art

[0002] The invention relates to a device for measuring the humidity of the breath and the use of the measurement results in determining a medical condition, in particular a human condition, but also a condition in animals such as horses, dogs etc.

[0003] The measurement of breath humidification can be used to identify, classify and longitudinally track diseases, including lung diseases. Further, combining the measurement of breath humidification with many other respiratory parameters can improve clinical accuracy when classifying patients or tracking their medical conditions.

[0004] The present invention is particularly useful in exhaled breath and determines, in part, the relative amounts of exhaled breath from the alveoli, the central, and what is traditionally referred to as the dead volume of the lungs. Exhaled breath humidity can be expressed in absolute and / or relative terms and can be used as a single measurement or in combination with several other respiratory parameters, including: measurements of exhaled breath condensate, measurements of the gas phase of exhaled breath, measurements of the vapor phase of exhaled breath and / or components within the gas phase, respiratory volume, exhalation rate, forced air manipulation, respiratory air temperature, etc. Examples of gas phase and vapor phase components or properties of these components that can be measured in conjunction with breath humidity include: pH, sugars, glucose, ketones, cations, anions, and small molecules such as nitric oxide, hydrogen peroxide, oxygen, carbon dioxide, carbon monoxide, etc. In addition, "markers" for other conditions (such as cancer) can also be determined.

[0005] The measurement of breath humidity may be measured in parallel or sequentially with other breathing parameters in a combined device or using a separate device.

[0006] In healthy people, breath hygrometry measurements are an indicator of total body water content and can be used as an indicator of a person's hydration level. Breath hygrometry values ​​can be used alone, compared with other respiratory parameters, or combined for more accurate clinical decision making.

[0007] In an earlier application EP2173250 in the name of the present applicant, a device is described which allows exhaled breath to be collected efficiently and in particular with minimal loss of volatile components which would introduce errors in the subsequent analysis. Once the breath sample is condensed it is then made available for analysis. However, the device does not measure the humidity of the breath and if the device is used the patient and clinician lose the clinical usefulness of knowing the humidity of the patient's breath.

[0008] Prior art document DE19951204 describes a method of condensing exhaled breath until a sample of a predetermined volume is obtained, but the humidity of the breath is still unknown, nor is it known how long it will take the patient to provide a sufficient volume of condensate. Knowing parameters such as the temperature of the breath, the flow rate of the breath, and the humidity of the breath, the time required to collect a certain amount of exhaled breath condensate can be calculated, which avoids the use of arbitrary set values ​​based on time, number of breaths, etc. When filling a respiratory condensate collection device, it is not uncommon for the device to not be filled within a reasonable time; this is because the clinician or patient is unaware that the patient is breathing at a low humidity and simply is not passing enough vapor, which is then condensed to fill the device. These patients may be referred to as "dry breathers".

[0009] Although a search for prior art documents describing our invention has been conducted, none has been found, the documents considered include: WO2018061022A1, WO2018101650A1, US2017 / 360328 and US2018 / 056302.

[0010] WO2018061022A1 - This application discloses a lung condition monitoring device in which CdS nanoparticles are used as part of humidity sensing to provide ultra-fast detection of a person's humidity level during exhalation.

[0011] WO2018101650A1 - The disclosed invention relates to a method and a device for analyzing biogas contained in a single breath, and to subsequent monitoring of respiratory diseases of a patient by means of the analyzed biogas.

[0012] US2017 / 360328 - The device disclosed in this document uses two electrodes to measure the water content of a single breath or multiple breaths: a working electrode that functions by exchanging cations with water (e.g., using perfluorocarbons), and a reference electrode that is protected by a cover to prevent the influence of exhaled breath.

[0013] US2018 / 056302 - Here, a device measures a first breath characteristic (such as humidity) and a second characteristic (such as a specific analyte, ketones in the illustrated embodiment). The latter measurement is obtained using a nanoparticle-based sensor.

[0014] Patients can have different levels of breath humidity, for example a group of healthy controls may have higher relative breath humidity than a group of patients with chronic obstructive pulmonary disease (COPD), but breath humidity is typically an unknown and therefore uncontrolled parameter when performing breath measurements on these COPD patients.

[0015] When measuring components of the breath within the gas phase (such as carbon monoxide, carbon dioxide, nitric oxide, etc.), the air is typically passed through filters, scrubbers, dehumidifiers, etc. to intentionally remove portions of the breath that include water vapor. This process may also be performed unknowingly, and the removal may therefore be "accidental." These devices then report the concentration of the molecule in the dried and / or processed breath sample. This is not necessarily the same as the concentration of the molecule in the original exhaled breath, but is often reported and interpreted as such. The true concentration of the analyte in the breath is affected in part by the humidity and temperature of the breath, as well as the partitioning of molecules between the gas and vapor phases, which is in part specific to each type of molecule. By measuring the breath humidity, we can normalize the concentration of the analyte measured in the breath relative to the breath humidity, and therefore reduce otherwise uncontrolled or unknown patient-to-patient variability, thereby improving clinical accuracy.

[0016] Currently, researchers and clinicians are interested in measuring parameters of the breath and / or analytes of the breath as part of disease identification, classification or longitudinal monitoring. A parameter that is not currently used is breath humidity. Currently, for COPD patients, their diagnosis and care assessment can be carried out through a battery of tests, including: forced ventilation, fractionated nitric oxide measurement (FNO), clinical questionnaires and exhaled breath condensate (EBC) hydrogen peroxide measurement, but the measurement of exhaled breath humidity is not routinely measured. Summary of the invention

[0017] According to a first aspect of the present invention, there is provided a device for measuring breath humidity, the device comprising a tubular body defining an inner tube volume;

[0018] an inlet fluidly connected to the inner tube volume;

[0019] a condenser plate fluidly connected to the second end of the tubular body to receive the exhaled breath;

[0020] a dividing wall intermediate the first end and the second end and dividing the inner tube volume into a first chamber and a second chamber, the second chamber providing a fluid passage to the condenser plate;

[0021] the dividing wall having a one-way valve therethrough that allows breathing gas to pass from the first chamber to the second chamber;

[0022] The device further comprises one or more apertures in the wall of the tubular body of the first chamber, the or each aperture fluidly linking the sensor to the first chamber;

[0023] A relative humidity sensor is fluidly linked to the second chamber.

[0024] Preferably the or each sensor is linked to a data storage device to enable the data to be quickly transmitted to a healthcare professional or analysed.

[0025] Optionally, the sensor is a CO2 sensor.

[0026] Optionally, the sensor is a mass air flow sensor to help determine if the device is being used correctly.

[0027] Optionally, the sensor is capable of detecting hydrogen peroxide to enable diagnosis of respiratory problems.

[0028] Preferably the or each sensor is housed in a removable housing which is attachable to the device to allow easy replacement so that the device can be used by a subsequent patient or replaced in the event of a fault.

[0029] Preferably, the condenser plate is cooled by a Peltier sheet cooling member. Further preferably, the heating plate is housed in a cooling arrangement having a Peltier sheet to assist in the rapid removal of thermal energy from the condenser plate. The device further preferably comprises a fan to draw air through the heating plate to remove thermal energy from the device.

[0030] The device preferably includes an accelerometer to determine whether the device is being held stably to ensure proper operation of the various elements of the device performing the analysis.

[0031] The second chamber preferably has a fluid outlet to exhaust the respiratory gas from the device and to minimize any turbulence.

[0032] The second chamber preferably comprises a directing member, which further preferably is a ramp, to direct the breathing gas entering the second chamber onto the condenser plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The invention is described with reference to the accompanying drawings which show, by way of example only, two embodiments of a device for measuring respiratory humidity and other parameters. In the drawings:

[0034] Figure 1 The respiratory humidity of patients with different respiratory conditions is shown;

[0035] Figure 2 shows the combined measured breath humidity and hydrogen peroxide values;

[0036] Figure 3 The airflow in the device is shown;

[0037] Figure 4a and Figure 4b It is the image of the installation;

[0038] Figure 5 is a schematic diagram of the device;

[0039] Figure 6 The internal passageway leaving the device is shown;

[0040] Figure 7a , Figure 7b A sleeve holder and sleeve for use within the device are shown;

[0041] Figure 8 is a graphic representation of the respiratory flow within the device;

[0042] Fig. 9 is another illustration of respiratory flow within the device; and

[0043] Fig.10a , Fig.10b Is a graphical representation of the measured parameters of the exhaled breath. DETAILED DESCRIPTION

[0044] The humidity of a person's breath is one way to determine if a person is sick. In addition, the humidity of the breath can be used to distinguish people within disease categories, for example, COPD patients can be distinguished from asthma patients. This is described below in Figure 1 Shown in.

[0045] exist Figure 1 In the study, the average relative humidity (RH) measured for the breath samples of the COPD group was about 15% lower than the RH measured for the healthy group. In short, the breath of COPD patients generally has less water vapor than the breath of the healthy control group. Further, it can be seen that the average breath RH of the asthma group is between the healthy control group and the COPD group. Figure 1The data in were taken from more than 155 individuals and showed that it would be possible to diagnose or classify COPD, asthma and healthy controls based on the relative humidity of the breath. Importantly, the relative humidity of the breath becomes more useful only when combined with other parameters such as mandatory ventilation, exhaled breath condensate hydrogen peroxide and fractionated nitric oxide (FNO).

[0046] Figure 1 The data in show that respiratory humidity alone is sufficient to distinguish healthy people from those with lung disease, but there is a greater problem in subclassifying patients as, for example, COPD or asthma, because the approximate difference in mean relative respiratory humidity is 5%. If respiratory humidity is combined with a second parameter, it will be possible to classify patients into further groups, such as COPD and asthma. For example, if exhaled breath RH and exhaled breath condensate (EBC) hydrogen peroxide concentration are examined simultaneously, there will be a clear pattern, namely, COPD patients have intermediate EBC hydrogen peroxide concentrations and the lowest RH, while the healthy group has the lowest EBC hydrogen peroxide concentration and the highest respiratory RH. The asthma group has intermediate RH and the highest EBC hydrogen peroxide concentration (see Figure 2 ).

[0047] As discussed, two, three or more respiratory parameters can be combined to provide a score or scale that better categorizes patients, for example, if the EBC hydrogen peroxide concentration is divided by the relative humidity, the difference between the asthma and COPD groups is magnified (see Table 1).

[0048]

[0049] Table 1

[0050] The combination of EBC hydrogen peroxide and RH obviously produces a score, referred to herein as the Helle Score, which enhances the differentiation of asthmatics from COPD patients. The combination of respiratory humidity is not limited to the combination with hydrogen peroxide, and additional clinical benefits can be expected by combining FNO, pH, etc. with respiratory humidity. The combination can be performed by a processor (not shown) included in the device or remotely.

[0051] Similarly, by combining the output from the clinical questionnaire with the breath hygrometry, a clinically useful score or scale can be generated. Creating a score or scale from breath measurements and breath hygrometry is not limited to simple mathematical operations, and other operators (including powers, logarithms, trigonometric functions, etc.) may also be used, either alone or in combination.

[0052] In order to measure the humidity of a patient's respiratory gas, a device with multiple functions is required, including: the device must be able to engage with the patient's mouth, the device must be able to guide the exhaled gas along a determined path, the device must be able to minimize the dead space between the mouth and the respiratory gas collection area, the device must be able to measure humidity, the device must be able to protect the humidity sensor from non-respiratory vapors and aerosols, the device must protect the humidity sensor from environmental conditions including ambient vapors, the device must be able to measure vapors whose only source is the respiratory system, optionally the device should also measure the temperature of the respiratory gas, and the device should function to cause the exhaled gas to replace the air remaining in the device from the previous exhalation.

[0053] The main potential source of contamination for any measurement of breath humidity is the ambient humidity near the patient being measured, and therefore breath humidity should be measured using a closed device in which the sensor is isolated from the ambient humidity. Further, the humidity sensor should be very close to the mouth, approximately 10 cm, and the sensor should be protected from contaminants such as saliva aerosols originating from the mouth, not the airways (see Figure 3 ).

[0054] Figure 4a , Figure 4b are images of a handheld embodiment of a device 10 capable of measuring respiratory humidity and carbon dioxide levels, as well as many other parameters. In these figures, a replaceable cartridge 11 is shown housing a microfluidic analysis system allowing the determination of, for example, hydrogen peroxide, pH, glucose, ketones, nitrogen oxides, etc. The cartridge 11, as detailed in FIG7 , may include a collection element, such as a cooling disk, as disclosed in the published patent application WO2009013450 of the same applicant, to collect a portion of the respiratory gas, typically the alveolar portion.

[0055] The device 10 further comprises a CO2 sensor 12, which is, for example, a near infrared sensor. A condenser plate 13 is located adjacent to a Peltier plate 14, which provides cooling to the plate 13. Located on the other side of the Peltier plate 14 is a hot plate 15, which acts as a heat sink for the Peltier plate 14. A fan 16 is used to extract unwanted heat from the device 10, in particular to pass air through the hot plate 15 to cool the hot plate 15.

[0056] Figure 5 A device 20 according to the present invention is schematically shown. The device 20 has an air inlet 21 designed to facilitate a user to breathe into the device 20. Thus, typically, the inlet 21 is contoured to enable a user to ensure that most of the exhaled air enters the device 20. The inlet 21 may include or be coupled to a replaceable mouthpiece to improve hygiene between different users of the device 20.

[0057] The inlet 21 leads to the sleeve 11 and also allows a portion of the exhaled air to be separated into a separate flow stream, which is then directed to a sensor (e.g., a CO2 sensor) incorporated into the device 20 itself. The sensor is located within the housing 22. An outlet 23 is provided for unused respiratory gas to prevent undesirable respiratory turbulence or backflow. A handle 28 is provided to enable the user to hold the device 20 in a position that facilitates comfortable exhalation. In the case where the device 20 is used as a desktop device in a medical institution or other situation, the handle 28 may not be present. In another option, the device may include a detachable handle, thereby providing flexibility in use of the device.

[0058] Figure 6 The internal features of a device 30 according to an embodiment of the present invention are shown. The device 30 has a breathing inlet 31 and a handle 34 that allows a user to hold the device 30. In this embodiment, the handle 34 is integrally formed with other elements of the device 30, such as the outlet 33 and the housing 32. The outer surface of the handle 34 can be ergonomically shaped to facilitate the user's grip on the device.

[0059] like Figure 7a , Figure 7b As shown, the sleeve 11 is located near the respiratory inlet 31. The sleeve 11 includes an RFID tag 35 or the like, which can be used to first ensure the correct record of the sleeve 11 and can be linked to the user. In addition, the tag 35 enables the age of the sleeve to be checked so that it can be determined whether the sleeve is still within the shelf life. The sleeve 11 also typically includes a microfluidic array, which includes sensors and reagents associated therewith to enable determination of various parameters and analytes. Such arrays are known in the art and will be available to those skilled in the art.

[0060] Within the device 30 is an accelerometer 36 which has a number of functions. First, the accelerometer 36 can determine that the device 30 is held in the correct orientation. Second, the accelerometer 36 allows for determination of any movement of the device 30 while in use. For example, this can indicate if the user's hands are shaking, which could be detrimental to the flow of fluid within the device 30 and lead to erroneous results.

[0061] The location of a CO2 sensor 42 is shown, as well as a further sensor 43. In an embodiment of the device 30, the respiratory gas to the CO2 sensor 42 flows along a tube 44 (shown in FIG. 4 ) located outside the device 30. The sensor 43 is similarly fed by another separate tube. Another set of sensors is located on the lower portion 37 of the pcb (printed circuit board) card 38 in use, which houses the temperature and relative humidity sensors and the 3-axis accelerometer sensor.

[0062] exist Figure 6In FIG. 4 , the condenser plate 45 is shown just behind the sleeve 11. A Peltier plate 46 is housed adjacent the plate 45 to provide cooling thereto when required. Power for the Peltier plate 46 and other components of the device is provided by a battery 47.

[0063] The information obtained by the sensor can be transferred to an external monitoring system via the USB interface 48. Data processing can be performed externally or on another pcb 49 installed in the device 30. In order to provide information to the user via the handheld device 30, a user interface 149 is also provided. Other information such as about the H2O2 level can be obtained via the connection point 80, which can also be used to determine and communicate whether there is an effective sleeve 11. If it is necessary to remove H2O2 from the atmosphere breathed by the user, a filter can be installed at the air inlet. In order to draw air through the device 30 where needed, a fan 81 is included, which can draw power from the battery 47.

[0064] Now turn to Figure 8 and Fig. 9 , which schematically illustrate an arrangement according to the invention. Figure 8 , the constituent elements of the device 50 are shown. Fig. 9 Shown by Figure 8 The device 50 has a substantially tubular body 51. The body 51 enables exhaled air from a user (entering the body 51 at one end) to be directed to a condenser plate 52 at the other end. In between, the flow is controlled to allow the user to inhale while using the device 50 and also to enable analysis of the breath.

[0065] In more detail, fixed to one end of the body 51 is a mouthpiece 53. The mouthpiece 53 can be detachably mounted to the body 51 to allow a further mouthpiece to be attached after the rest of the device 50 has been cleaned, so that another user can use the device 50. The mouthpiece 53 is fluidly connected to the internal volume of the body 51 by means of a two-way valve 54. The body 51 is divided into two chambers 56a, 56b by a chamber wall 55. The first chamber 56a is linked to the mouthpiece 53 via a valve 54. The second chamber 56b is fluidly linked to the first chamber 56a via a one-way valve 57, which allows flow from the first chamber to the second chamber. The chamber wall 55 and the member that allows a portion of the respiratory gas to pass from the first chamber to the second chamber are used to prevent an unwanted portion of the exhaled gas from reaching the condenser plate 52. The chamber wall 55 enables the first chamber 56a to be used to allow air to be drawn into the body 51 without affecting the passage of respiratory gas through the respiratory sensor 58 and condenser plate 52 associated with the second chamber 56b. In addition, the chamber wall 55 is used to induce a certain degree of turbulence within the first chamber. This is used to limit the Bernoulli effect of the air flow within the sensors 62, 64 (see below), which otherwise may cause air to flow from these sensors 62, 64 into the first chamber 56a, rather than through the sensors 62, 64.

[0066] Sensor 58 provides data about several parameters. For example, sensor 58 may include a relative humidity (RH) sensor and a temperature sensor. Most of the airflow entering second chamber 56b is discharged onto condenser plate 52 via aperture 60. Condenser plate 52 maintains cooling to condense the aqueous component of the respiratory gas and other substances dissolved therein. The liquid condensed on condenser plate 52 can then be drawn out for analysis in a suitably arranged microfluidic array. In order to better focus the respiratory flow onto condenser plate 52, an inclined inner wall 70 is provided. In addition, a one-way outlet valve 71 actually allows the pressure of the rebound respiratory gas from condenser plate 52 to flow out of device 50 instead of returning to second chamber 56b, where any incoming respiratory gas will cause turbulence. This turbulence can affect the results obtained, especially due to the chaotic flow conditions caused.

[0067] Other fluid outlets in the body 51 allow the respiratory gas to be directed to other analyzers located outside the body 51. The first other outlet 61a directs the exhaled gas to the airflow measurement sensor 62. The data from the airflow measurement sensor makes it possible to determine whether the user is using the device 50 correctly, and also gives an indication of the overall effectiveness of the user's lungs. A typical airflow measurement sensor includes a piezoelectric element that is deformed due to the pressure of the airflow, wherein there is a one-to-one relationship between the pressure and the deformation caused in the piezoelectric element. Tube 63 provides a fluid path to leave the sensor 62. The second and further outlet 61b leads to a CO2 sensor 64. As an example of the CO2 sensor 64, a near infrared detector is provided. Similarly, a tube 65 is provided to provide a fluid path to leave the sensor 64.

[0068] The airflow measurement device 62 and the CO2 sensor 64 are both held within a housing 66. The housing 66 is removably mounted to the exterior of the body 51, with the outlets 61a, 61b extending through a wall 67 of the body 51. In the illustrated embodiment shown, a steel plate 68 is secured to the wall 67. Magnets 69 are then used to magnetically secure the housing 66 against the plate 68. It will be appreciated that other means of securing the housing 66 to the body 51 known in the art may also be used.

[0069] The device should have at least one breathing air humidity measurement point located upstream of any scrubbers, condensers, dehumidifiers, dryers, etc., which may also be present within the device.

[0070] The use of valves and controlled volumes within the device should be configured to ensure that the sample being measured is the result of exhaled breath, rather than a mixture of breath and ambient air. Obviously, contaminants such as saliva carried from the mouth in aerosol form should be prevented from reaching and contaminating the sensor.

[0071] Measurements made on breath are currently used to identify diseases such as COPD and asthma, and this document describes devices for measuring the humidity of breath, the clinical uses of such measurements, and the use of breath humidity along with a number of parameters measured on breath.

[0072] The device for measuring respiratory humidity must be able to engage with the patient's oral cavity. Those parts of the device that come into contact with the oral cavity must be able to be easily sterilized between patients, or preferably disposed of to eliminate the risk of cross contamination. The device optionally has a member for capturing saliva to prevent aerosols and particulates from the oral cavity from entering the body of the device or risking contamination of the humidity sensor. The device should preferably allow the patient to inhale, but its internal volume should be smaller than the expected tidal breathing expiratory volume, which is typically about 500 cm 3, so that the exhaled air dominates the internal volume of the device. The device should be able to measure the respiratory air humidity, and preferably measure the respiratory air temperature and ideally measure the respiratory air relative humidity. The device should optionally measure the exhaled air pressure, flow rate and carbon dioxide level. The device should be able to measure all parameters as a function of time, so that parameters such as carbon dioxide, inhalation / expiratory pressure, carbon dioxide concentration, respiratory air temperature, respiratory air humidity, respiratory air relative humidity, ambient humidity, ambient relative humidity, ambient temperature, etc. can all be aligned and compared in time. The device can optionally have additional functions, such as, condensation and analysis of exhaled air, removal of respiratory vapor, measurement of gas phase molecules (including FNO).

[0073] In applications where removal or collection of breath vapor is important, a second humidity sensor can be located downstream of the initial breath humidity sensor and the vapor collection point to measure the breath humidity after vapor collection. The difference between the breath humidity sensor and the post-vapor collection sensor allows the collected volume and collection efficiency of the vapor to be determined.

Claims

1. A device for measuring breath humidity, the device comprising a tubular body defining an inner tube volume; an inlet fluidly connected to the inner tube volume; a condenser plate fluidly connected to the second end of the tubular body to receive exhaled breath; a divider wall intermediate the first end and the second end of the tubular body and dividing the inner tube volume into a first chamber and a second chamber, the second chamber providing fluid access to the condenser plate; the dividing wall having a one-way valve therethrough, the one-way valve allowing breathing gas to pass from the first chamber to the second chamber; The device further comprises one or more apertures in the tubular body wall of the first chamber, the or each aperture fluidly linking a sensor to the first chamber; a relative humidity sensor fluidly linked to the second chamber; A processor receives data from the relative humidity sensor and the sensor and processes the data to derive a composite Heller score.

2. The device for measuring respiratory humidity according to claim 1, wherein: The or each sensor is linked to a data storage device.

3. The device for measuring respiratory humidity according to claim 1 or claim 2, wherein: The sensor is a CO2 sensor.

4. The device for measuring respiratory humidity according to claim 1, wherein: The sensor is a mass air flow sensor.

5. The device for measuring respiratory humidity according to claim 1, wherein: The sensor is a hydrogen peroxide sensor.

6. The device for measuring respiratory humidity according to claim 1, wherein: The or each sensor is housed in a removable housing attachable to the device.

7. The device for measuring respiratory humidity according to claim 1, wherein: The apparatus includes a Peltier sheet cooling member for cooling the condenser plate.

8. The device for measuring respiratory humidity according to claim 7, wherein: The heating plate is accommodated in a cooling arrangement with said Peltier plates.

9. The device for measuring respiratory humidity according to claim 8, wherein: A fan is included and is arranged to draw air through the heating plate.

10. The device for measuring respiratory humidity according to claim 1, wherein: The device includes an accelerometer.

11. The device for measuring respiratory humidity according to claim 1, wherein: The second chamber has a fluid outlet to exhaust respiratory gas from the device.

12. The device for measuring respiratory humidity according to claim 1, wherein: The second chamber includes an indexing member.

13. The device for measuring respiratory humidity according to claim 12, wherein: The guiding member is a ramp.

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