阅读说明：本技术 基于激光的人体内气体的内部分析的系统和方法 (System and method for laser-based internal analysis of gas in the human body ) 是由 苏内·斯万贝里 埃米莉·克里特·斯万贝里 马库斯·拉松 于 2016-08-17 设计创作，主要内容包括：一种用于测量受试者的腔中的游离气体的装置、系统和方法。该装置、系统和方法包括：光源,用于发射具有与游离气体的吸收带相关联的波长的光；光纤,连接到光源并且适用于使用导入构件而被内部地插入到受试者中用来内部照明；和检测器,适用于定位在皮肤表面上以检测通过受试者的组织的透射光。该装置、系统和方法还包括用于评价检测到的透射光以确定游离气体、游离气体的分布或游离气体的浓度的控制单元。(An apparatus, system, and method for measuring free gas in a cavity of a subject. The apparatus, system and method include: a light source for emitting light having a wavelength associated with an absorption band of a free gas; an optical fiber connected to the light source and adapted to be internally inserted into the subject using the lead-in member for internal illumination; and a detector adapted to be positioned on the skin surface to detect transmitted light through tissue of the subject. The apparatus, system, and method also include a control unit for evaluating the detected transmitted light to determine free gas, a distribution of free gas, or a concentration of free gas.)

1. An apparatus for determining lung function of a subject, comprising:

a light source for externally emitting light into the subject having a wavelength, and wherein the wavelength is associated with an absorption band of free gas in the lungs;

a detector unit adapted to be positioned on a skin surface to detect transmitted light through tissue of the subject;

a control unit for evaluating the detected transmitted light to assess the distribution of the free gas or the concentration of the free gas for determining the lung function of the subject.

2. The apparatus of claim 1, wherein the light source is a laser.

3. The device according to claim 1 or 2, wherein the device comprises at least two light sources having different wavelengths.

4. The apparatus of claim 3, wherein at least one light source has a wavelength associated with an absorption band of a reference gas.

5. The apparatus of claim 4, wherein the reference gas is water vapor.

6. The device of any one of claims 1-5, wherein the free gas is a physiological gas, or a mixture of gases.

7. The device according to claim 6, wherein the physiological gas is any one of oxygen, Nitric Oxide (NO), carbon dioxide and water vapor.

8. The apparatus according to any of claims 1-7, wherein the control unit is configured to control a medical ventilator based on the distribution of the free gas or the concentration of the free gas.

9. The device according to any of claims 1-8, wherein the control unit is configured to control administration of a drug based on the distribution of the free gas or the concentration of the free gas.

10. The apparatus according to any of claims 1-9, wherein the control unit is configured to activate an alarm when the determined free gas, the distribution of free gas or the concentration of free gas reaches or exceeds a selected threshold value.

11. The device of any one of claims 1-10, wherein light is emitted from more than one location.

12. The apparatus of any one of claims 1-11, wherein the transmitted light is detected by more than one detector unit.

13. The apparatus of claim 12, wherein diffuse optical tomography is used to evaluate the distribution of the free gas.

14. The apparatus of claim 13, wherein the evaluation is obtained as a three-dimensional gas distribution.

15. The apparatus of any one of claims 1-14, wherein the detector unit is an imaging sensor configured such that the light source emits an absorption wavelength and a near non-absorption wavelength in sequence and the imaging sensor detects two images which are subsequently compared by the control unit.

16. The apparatus of any one of claims 1-11, wherein the control unit evaluates a line profile change in an absorption spectrum to determine the free gas distribution or the free gas concentration.

17. The device of any one of claims 1-16, further comprising an introducer member disposed in a channel or catheter of the subject; and

an optical fiber connected to the light source and adapted for insertion inside the subject using the introduction member.

18. The apparatus of claim 17, wherein the optical fiber comprises a light diffuser at an end adapted for positioning in the lead-in member.

19. The device of claim 17 or 18, wherein the introduction member is a tracheal tube, an endotracheal tube, or a bronchoscope.

20. The device of claim 17, wherein the introduction member is a nasogastric tube adapted for insertion into the esophagus.

21. The device according to any one of claims 17-20, wherein the introducer member has an expandable balloon or sleeve.

22. The device according to claim 21, wherein said expandable balloon or sleeve is made of a light diffusing material.

23. The device according to claim 21 or 22, wherein the inner wall of the expandable balloon or sleeve is provided with a light reflective coating.

24. The device according to any of claims 21-23, wherein the expandable balloon or sleeve is provided at an end section of the introduction member.

25. The device of any one of claims 17-24, wherein an end section of the lead-in member is adapted to be coupled to the optical fiber.

26. The apparatus of any one of claims 17-25, wherein the optical fiber is embedded in a wall of the introducer member.

27. A method for determining lung function in a subject, comprising:

emitting light into the subject from outside, the emitted light having a wavelength associated with an absorption band of free gas in the lungs;

positioning a detector unit on a skin surface;

detecting, by the detector unit, transmitted light through tissue of the subject;

evaluating the detected transmitted light using a control unit to assess the distribution of the free gas or the concentration of the free gas for determining the lung function of the subject.

28. The method of claim 27, wherein the detector is positioned on the chest of the subject.

29. The method of any one of claims 27 to 28, disposing an optical fiber connected to the light source in an introducer; and is

Inserting the introducer inside the subject.

30. The method of claim 29, wherein the passageway or conduit is a trachea or an esophagus.

Technical Field

The present disclosure relates to analyzing gases within the human body by positioning a light source, such as an optical fiber connected to a laser, within a cavity of the body. In particular, the present disclosure relates to positioning a light source in the trachea or in the digestive system (e.g., in the esophagus or intestine) to make measurements on a biological gas.

Background

Physiological gases, such as oxygen, nitrogen, Nitric Oxide (NO), carbon dioxide and water vapour, are present in many cavities in the human body, such as the lungs, sinuses and middle ear. The digestive system is another location for the gas. Oxygen in the lungs is of interest because it is a prerequisite for important functions in humans. It is of interest to monitor oxygen in the lungs, especially in premature neonates. In diseases associated with the cavities of the head, such as sinusitis or otitis media, the gas-filled cavities may be filled with liquid and the gas signal may diminish or disappear.

By using the characteristic absorption signal, the substance can be identified by spectroscopic analysis. Although the spectral signals from liquids and solids are relatively broad, typically 10 nm, free gas is characterized by absorption lines that are about 10000 times sharp, typically about 0.001 nm. This difference in absorption signals enables the detection of free gas in a cavity or pore surrounded by a dense substance such as human tissue. This is the basic principle of the technique known as Gas Absorption Spectroscopy in Scattering Media (Gas in Scattering Media Spectroscopy), s.svanberg, Gas in Scattering Media Absorption Spectroscopy, from basic research in biomedical applications, Lasers and Photonics Reviews 7,779 (2013).

The GASMAS technique has been used to characterize the sinuses and middle ear, measurement methods and devices of body cavity gases (Human cavity gas measurement method and device) such as s.svanberg, l.persson and k.svanberg; swedish patent application 0500878-4; l.persson, m.andersson, m.cassel-Engquist, k.svanberg and s.svanberg use Tunable Diode Laser Spectroscopy to monitor Human sinus Gas (Gas Monitoring in Human Sinuses using Tunable Diode Laser Spectroscopy), j.biomed.optics 12,2028 (2007); l.persson, m.lewander, m.andersson, k.svanberg and s.svanberg using Tunable Diode Laser Spectroscopy to simultaneously detect Molecular Oxygen and Water Vapor in Tissue Optical windows (simple electron Detection of Molecular Oxygen and Water Vapor in the Tissue Optical Window), Applied Optics 47,2028 (2008); clinical systems for Non-invasive in situ Monitoring of gas in the Human Paranasal Sinuses (Clinical systems for Non-invasive in situ Monitoring of Gases in the Human Paranasal Sinuses), Optics Express 13,10849 (2009); clinical studies using Diode Laser Gas Spectroscopy to evaluate Information on the Maxillary and Frontal Sinuses (Clinical Study on the Maxillary and front individuals using Diode Laser Gas Spectroscopy), Rhinology 50,26 (2011); assessment of air volume in human sinus cavities using tunable diode laser methods of j.huang, h.zhang, t.q.li, h.y.lin, k.svanberg and s.svanberg and application in diagnosis of sinusitis (ase)Moment of Human organ Cavity using tubular Diode Laser Spectroscopy, with Application to silicon Diagnostics), J.biophotonic DOI 10.1002/jbio.201500110; svanberg and S.Svanberg use Laser spectroscopy to monitor Free Gas In Situ at the front of biophotonic transformation Medicine for Medical Diagnostics (Monitoring of Free Gas In-Situ for Medical Diagnostics use Laser spectroscopy, In front of adhesives In Biophotonics for Translational Medical Medicine), U.S.Dimix and M.Olivo (eds) (Springer, Singapore 2015) 307-; optical Detection of Middle Ear infections using Spectroscopic-imaging Experiments (Optical Detection of Middle Ear Infection-Phantom Experiments), j.biomedical Optics 20, 057001(2015), zhang, j.huang, t.q.li, s.svanberg and k.svanberg. GASMAS technology has also been used in studies to characterize the gas in the lungs and intestines of term newborns, non-invasive monitoring of the lungs and intestinal gas of newborns using diode lasers, p.lundin, e.krite Svanberg, l.cocola, m.lewander Xu, g.somesfailean, s.andersson-Engels, j.jahr, v.filman, k.svanberg and s.svanberg: feasibility study, j.biomedical Optics 18,127005 (2013); e.krite Svanberg, p.lundin, m.larsson,non-invasive monitoring of neonatal lung and intestinal oxygen Using Diode Laser Spectroscopy (Non-invasive monitoring of oxygen in the lungs of New born Infants Using Diode Laser Spectroscopy), Pediatrics Research,79,621(2015), by K.Svanberg, S.Svanberg, S.Andersson-Engels and V.Fellman.

Oxygen and water vapor can be recorded in most cases, but this is not always the case. The reason for the lack of detection of a signal may be due to the lower signal strength of the detected light after having passed the long path through the surrounding tissue.

Accordingly, new and improved apparatus and methods for detecting free gases within a body cavity would be advantageous.

Disclosure of Invention

Accordingly, embodiments of the present disclosure preferably seek to mitigate, alleviate or eliminate one or more deficiencies, disadvantages or issues in the art, such as the above-identified, singly or in any combination by providing a device, system or method according to the specification for measuring free gas in a cavity, such as a lung or a digestive system.

According to a first aspect, an apparatus for measuring free gas in a cavity of a subject is disclosed. The device includes: a light source for emitting light having a wavelength associated with an absorption band of a free gas; an optical fiber connected to the light source and adapted to be internally inserted into the subject using the introduction member; a detector unit adapted to be positioned on a skin surface to detect transmitted light through tissue of a subject. The apparatus additionally comprises a control unit for evaluating the detected transmitted light to determine the distribution of free gas or the concentration of free gas.

In some examples of the disclosure, the control unit of the apparatus may be configured to detect free gas in the chamber.

In some examples of the disclosure, the light source is a laser.

In some examples of the disclosure, the apparatus includes at least two light sources having different wavelengths.

Additionally, in some examples of the present disclosure, at least one of the at least two light sources may have a wavelength associated with an absorption band of the reference gas.

In some examples of the disclosure, the reference gas may be water vapor.

In some examples of the disclosure, the free gas may be a physiological gas or a mixture of gases.

In some examples of the present disclosure, the physiological gas may be any one of oxygen, Nitric Oxide (NO), carbon dioxide, and water vapor.

In some examples of the disclosure, the optical fiber may include a light diffuser at an end adapted to be positioned in the lead-in member.

In some examples of the disclosure, the control unit may be configured to control the medical ventilator based on a distribution of the free gas or a concentration of the free gas.

In some examples of the disclosure, the control unit may be configured to control administration of the drug based on a distribution of the free gas or a concentration of the free gas.

In some examples of the disclosure, the control unit may be configured to activate an alarm when the determined free gas, the distribution of free gas, or the concentration of free gas meets or exceeds a selected threshold.

In some examples of the disclosure, the distribution of free gas or the concentration of free gas may be used to determine lung function of the subject.

In some examples of the disclosure, light is emitted from more than one location, and the transmitted light is detected by more than one detector unit.

In some examples of the present disclosure, diffuse optical tomography (diffuse optical tomography) may be used to evaluate the distribution of free gas.

In some examples of the disclosure, the evaluation may be obtained as a three-dimensional gas distribution.

In some examples of the disclosure, the detector unit may be an imaging sensor configured such that the light source emits the absorption wavelength and the near non-absorption wavelength sequentially, and the imaging sensor detects two images which are then compared by the control unit.

In some examples of the disclosure, the control unit may evaluate a line profile change in the absorption spectrum to determine a distribution of the free gas or a concentration of the free gas.

In another aspect, a system for measuring free gas in a cavity of a subject is disclosed. The system comprises: an introduction member disposed in a channel or conduit of a subject; a light source for emitting light having a wavelength associated with an absorption band of a free gas; an optical fiber connected to the light source and adapted to be inserted into the introducing member; and a detector unit adapted to be positioned on the skin surface to detect transmitted light through tissue of the subject. The system further comprises a control unit for evaluating the detected transmitted light to determine the distribution of the free gas or the concentration of the free gas.

In some examples of the disclosure, the introduction member is a tracheal tube, an endotracheal tube, a bronchoscope, an endoscope, or a colonoscope.

In some examples of the disclosure, the introduction member is a nasogastric tube adapted for insertion into the esophagus.

In some examples of the disclosure, the introducer member may have an expandable balloon or sleeve.

In some examples of the disclosure, the expandable balloon or sleeve is made of a light diffusing material.

In some examples of the disclosure, the inner wall of the expandable balloon or sleeve has a light reflective coating.

In some examples of the disclosure, an expandable balloon or sleeve is disposed at the end section of the introducer member.

In some examples of the disclosure, the end section of the lead-in member is adapted to be coupled to an optical fiber.

In some examples of the disclosure, the optical fiber is embedded in a wall of the lead-in member.

In another aspect, a method of measuring free gas in a cavity of a subject is also disclosed. The method comprises the following steps: disposing an introduction member in a channel or duct of a subject;

positioning an optical fiber connected to a light source in the lead-in member;

positioning a detector unit on a skin surface;

emitting light using a light source, the emitted light having a wavelength associated with an absorption band of a free gas;

detecting transmitted light through the tissue by a detector unit; and

the detected transmitted light is evaluated using a control unit for determining the distribution of the free gas or the concentration of the free gas.

In some examples of the disclosure, the detector is positioned on the chest of the subject.

In some examples of the disclosure, the passageway or conduit is a trachea or an esophagus.

In some examples of the disclosure, the detector is positioned on the abdomen of the subject.

It should be emphasized that the term "comprises/comprising" when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

Drawings

These and other aspects, features and advantages of the examples of the disclosure will become apparent from and elucidated with reference to the following description of examples of the disclosure, in which:

FIG. 1 illustrates one example of the disclosed apparatus and system;

fig. 2A to 2D show examples of arrangements of light sources in the trachea for measuring lung function;

fig. 3 shows another example of a light source arrangement using a bronchoscope for measuring lung function; and

fig. 4A and 4B show further examples of arrangements in which the light source is inserted through the esophagus.

Detailed Description

Specific examples of the present disclosure will now be described with reference to the accompanying drawings. This disclosure may, however, be embodied in many different forms and should not be construed as limited to the examples set forth herein. Rather, these examples are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

The following disclosure focuses on examples of the present disclosure that are capable of analyzing or monitoring free physiological gases in a body cavity of a human by placing a light source in the cavity, such as the trachea or the digestive system (e.g., the esophagus or intestine, which is part of the digestive tract), and detecting the transmitted light using one or more detectors placed outside the human body.

This is advantageous, for example, for detecting weak signals due to the long path of light through the tissue surrounding the cavity.

When using narrow band light, such as a laser, to monitor gases, the light has been delivered to the skin over a cavity containing free gas, such as the lungs or intestines. Light that has penetrated enough tissue to reach the cavity is scattered and transmitted to a detector against the skin located a few centimeters to the side of the light source. A non-invasive measurement procedure is thereby performed, but the light transmitted from the light source reaching the detector is severely attenuated due to the tissue through which the light must pass between the light source and the detector, and the scattered light is then further attenuated when transmitted back to the detector through the tissue. For example, if a portion (about 0.001) of the light transmitted towards the skin reaches a cavity containing free gas, another attenuation coefficient of 0.001 must be used for the light returning from the cavity in order to be detected by a detector arranged on the skin. Thus, the observed light reaching the detector is approximately one part per million of the light transmitted by the light source to the skin.

In the disclosed example, the light source is arranged to transmit light to the tissue with as low a loss as possible, and then to detect the light at the skin surface. By measuring the free gas in the cavity by internally arranging the light source to reduce the attenuation factor of the light transmitted to the tissue, the total attenuation factor can be reduced to about 0.001, which is about 1000 times greater than previously achieved.

The disclosed devices, systems, and methods utilize a means for introducing a light source that injects light into tissue, such as a bronchoscope, nasogastric tube, endoscope, tracheal tube, colonoscope, or similar introduction means.

When the GASMAS technique is applied to monitor free gas in the lumen, the patient population considered most relevant is the premature neonate. These neonates often suffer from respiratory complications such as dyspnea and lung function problems. Therefore, preterm neonates are often connected to medical ventilators to assist them in delivering air into and out of the lungs. When connected to a medical ventilator, a preterm neonate is intubated through an endotracheal tube (e.g., an endotracheal tube). In one example described, it is described how an optical fiber arrangement for delivering light to a cavity (e.g. a lung) can be performed in conjunction with an endotracheal tube (e.g. an endotracheal tube) while detecting transmitted light at the skin surface.

In another example described, it is described how an optical fiber arrangement for delivering light to a cavity (e.g. the lungs) can be performed in conjunction with a nasal feeding tube inserted into the oesophagus, while detecting the delivered light at the skin surface.

Additionally, in another example, light from the optical fiber arrangement is distributed over a greater distance or area by the light diffusing material.

Additionally and/or alternatively, the transmitted light is detected at the skin surface by one or more detectors located on the skin over the cavity (e.g., lung). The detector may be configured to be arranged at the skin surface, or other means, such as an optical fiber, may be used to collect light at the skin surface and guide the collected light to the detector. In one example, multiple detectors may be used in parallel or sequentially to detect gas or gas distribution or gas concentration in different portions of the patient's bronchial tree.

In this way, the results of changes in settings of a medical ventilator or drug administration can be directly observed, and information from the observation can be used to optimize the treatment of the patient using a feedback system.

In some examples, the detection is frequency and phase sensitive. Light from a light source (e.g., a laser) may be wavelength modulated at a selected frequency and a simultaneous intensity change may be detected when modulated near the gas absorption wavelength. When modulated close to the Gas Absorption wavelength, the intensity of the detected light will change rapidly at small wavelength variations, as described in s.svanberg Gas Absorption spectra in Scattering Media-from Basic research to Biomedical Applications (Gas in Scattering Media Absorption Spectroscopy-laser and Photonics Reviews 7,779(2013), which is incorporated herein by reference.

Optionally, in some examples, the skin region may be detected by an imaging sensor (e.g., a digital camera) at the absorption wavelength and near the non-absorption wavelength with high intensity dynamics. The two images can then be compared, for example by division or subtraction, whereby the region affected by the gas can be made visible.

The same techniques as described above for chambers (e.g. lungs) can be used to monitor gas, gas distribution or gas concentration in other chambers, for example in the digestive system (e.g. intestines). The light may be injected using a fiber optic arrangement in conjunction with a channel in an endoscope, an endoscope for esophago-gastro-duodenoscopy, a colonoscope, or other minimally invasive device. For example, in diagnosing the severe disease, Necrotizing Enterocolitis (NEC), an abnormal gas distribution in the intestinal tract (e.g. a part of the digestive tract) can be seen.

When using the GASMAS technique, the determination of the gas concentration may be affected by the path length in the tissue through which the light interacting with the gas in the cavity has to travel. Due to multiple scattering, the path length in the tissue is unknown. Thus, light traveling longer and shorter distances through tissue can be detected simultaneously. The Beer-Lambert relationship commonly used in the analysis of gases gives that the intensity of the absorption signal is determined by the product of the gas concentration and the path length (see S.Svanberg for Atomic and Molecular Spectroscopy-Basic Aspects and Practical Applications, 4 th edition, Springer, Berlin, Heidelberg 2004, which is incorporated herein by reference). When the path length is known, which is the case when measuring in non-scattering materials, the gas concentration can be directly calculated.

When measuring gas concentration using the GASMAS technique, the path length through the gas is unknown; this needs to be taken into account when making gas concentration measurements. Different approaches can be used to deal with the problem of unknown path lengths, such as the Determination of the path length of a Gas in the Scattering medium Absorption spectrum at l.mei, g.somesfailean and s.svanberg (Pathlength Determination for Gas in Scattering Media Absorption Spectroscopy), Sensors 14,3871(2014), which are incorporated herein by reference.

One of the most accurate methods is to use profile variations in the absorption spectrum of, for example, water vapor absorption lines. The profile of the water vapor Absorption lines varies depending on the oxygen Concentration, see p.lundin, l.mei, s.andersson-Engels and s.svanberg, Laser Spectroscopic Gas Concentration measurement by Absorption Line Shape Analysis with positional Optical Path Length (Laser Spectroscopic Gas concentrations in situ with Unknown Optical Path Length Enabled by Absorption Line Analysis), applied.phys.lett.103, 034105(2013), which is incorporated herein by reference. This method requires a good signal-to-noise ratio because oxygen has a weak influence on water vapor.

Another option is to make GASMAS measurements of the gas concentration and water vapor to be measured. It can be assumed that the water vapor concentration is saturated in the tissue and wherein the concentration is determined by known temperatures, see a.l. Buck, Buck Research Manuals; updated Equalification from (1981), which is incorporated herein by reference. New equations for calculating Vapor Pressure and Enhancement factors (New Equipment for calculating Vapor Pressure and Enhancement Factor), J.appl.Methoreol.20, 1527(1996), which are incorporated herein by reference. Based on the measured water vapor signal, the effective path length can be calculated. The resulting path length may be approximately the same as a gas having the concentration to be determined, such as oxygen, Nitric Oxide (NO), or carbon dioxide. The approximate path length can then be used to calculate the gas concentration directly for oxygen, Nitric Oxide (NO), or carbon dioxide. This method works best when the light absorption and light scattering in the tissue are the same for both measurements, which is the case when the wavelengths used for the measurements are close. For example, oxygen is typically monitored around some sharp components in the a band of oxygen molecules at about 760 nm. Water vapor has strong absorption around 935nm, for example, but the difference in wavelength compared to oxygen may need to be corrected for due to the difference in optical properties at different wavelengths. Therefore, a weaker absorption wavelength of water vapor around 820nm may be a better choice.

Fig. 1 shows an embodiment. Patient 1 in this example is a premature newborn infant. In the case of Respiratory Distress Syndrome (RDS), a new born infant is connected to the medical ventilator 2.

A medical ventilator 2 is connected to an intubated patient 1 by means of an endotracheal tube 3, for example inserted into a trachea 4. In this example, two light sources 5,6 are used to measure gases, for example oxygen at about 760nm and water vapour at about 820 nm. Other wavelengths may be used depending on the gas being measured. In some examples, other gases than water vapor may be used as the reference gas. The requirement is only that the gas concentration can be calculated without the need for the path length travelled by the detected light.

Alternatively, in other examples, only one light source may be used. In some other examples, more than two light sources may be used to detect more gases, gas distributions, or gas concentrations.

Alternatively, other configurations of the light source are possible when using other methods related to GASMAS as described previously.

The light source may be a semiconductor laser such as a distributed feedback laser (DFBL), a Vertical Cavity Surface Emitting Laser (VCSEL), or other type of laser available. The effect of the emitted light is preferably in the range of 1 to 3000 mW.

The laser may be driven by a current and temperature regulating unit comprised in the driving unit 7. The drive unit 7 may be controlled by a control unit 8, such as a computer. The control unit 8 may be used for signal processing and evaluation of measurement data.

Furthermore, in some examples, the control unit 8 may be connected to a controller 9 of the medical ventilator 2 for controlling settings of the medical ventilator 2. Additionally and/or alternatively, the controller 9 may also be used to control the dispensing of the medicament 10 to the patient 1.

Additionally, in some examples, the laser may modulate the wavelength by modulating the drive current at two separate frequencies. The frequency may typically be in the region of around 10kHz to allow for phase-in-detection with reduced noise.

By using separate modulation frequencies, different gases, such as oxygen, Nitric Oxide (NO) and carbon dioxide, and water vapor, can be separated even though light injection may be performed through the same optical fiber 11. Light from individual optical fibers 12 connected to light sources (e.g., semiconductor lasers 5, 6) may be connected to a single injection fiber 11.

Additionally, in some examples, a small portion of the light to be injected may be diverted optically (e.g., by an optical fiber) to the calibration unit 13. The calibration unit 13 may be a gas cell (gas cell) including a gas to be detected, such as oxygen, Nitric Oxide (NO), and carbon dioxide. The gas has a known concentration and the gas chamber has a predetermined length. The calibration unit 13 may also include a water and temperature measurement unit. All parts of the calibration unit 13 may have a common detector unit.

Alternatively, in some examples, compact scattering multi-channel chambers made of porous materials (e.g., ceramics) may be used. Porous Materials can be packaged in compact air chambers, see Disordered, Strongly Scattering Porous Materials of t.svensson, e.adolfson, m.lewander, c.t.xu and s.svanberg as mini-multipass air chambers (dispersed, strong Scattering Porous Materials as minor Multi-pass Gas Cells), phys.rev.lett.107,143901(2011), which is incorporated herein by reference.

The main part of the light of the individual frequency markers is directed through the optical fibers 11 down through the endotracheal tube 3 used in this example.

In the example shown in fig. 2B to 2D, the fibers 11 terminate in a diffuser. The diffuser may be a structure on the surface of the fiber or a separate component made of light scattering material. Diffusers are used to distribute light over a larger surface to achieve reduced surface power. Lower surface power may help to avoid temperature increases in the tissue. Another advantage is eye safety if the test is performed outside the human body.

In some examples, the injected light transmitted from the tip of the end of the optical fiber 11 may be transmitted to the tissue (e.g., through a diffuser) without passing any air in the trachea. If the light passes through air, the air may give some background signal in the light detected by the detector 14.

In one example, an inflatable sleeve or balloon made of light scattering material and having reflective material on the inner wall may be used to transmit as much light as possible directly into the tissue, as shown in fig. 2A.

The example shown in fig. 2A gives a good localization of the optical fiber for monitoring the upper part of the lung. By using a bronchoscope and a diffuse fiber tip, the light injection can be deeper into the bronchial tree as shown in fig. 3.

Alternatively and/or additionally, in some examples, more than one, e.g., at least two, locations are used for light injection. When more than one location is used for measurement, measurements for different locations need to be performed in sequence. Alternatively, more than one controllable standard optical fiber may be used.

When more than one site is used for light injection and for better three-dimensional gas distribution analysis, diffuse optical tomography may be used, as described in J.Swartling, J.Axelsson, S.Svanberg, S.Andersson-Engels, K.Svanberg, G.Ahlgren, K.M.The System for Interstitial Photodynamic Therapy by On-line Dosimetry of Prostate Cancer (System for Interstitial Photodynamic Therapy with On-line Therapy-First Clinical Experiences of state Cancer), j.biomed.optics 15,058003 (2010), to Nilsson, which is incorporated herein by reference; and Diffuse optical Tissue Monitoring and Tomography (Diffuse Optics for Tissue Monitoring and tomogry), t.dururan, r.choe, w.b.baker and a.g. Yodh, rep.progr.phys.73,076701(2010), which is incorporated herein by reference.

One or more detectors 14 are adapted to be placed against the skin. The detector should have a surface size for detecting light transmitted through the tissue, for example, in the range of 0.25 to 5cm²In the range of (1 cm), for example². The detector may be made of a different material, such as germanium.

The detected light is transmitted as an electrical signal to the control unit 8. The signals can be evaluated sequentially or in parallel using digital lock-in techniques, as described in the literature: wavelength Modulation Spectroscopy of l.mei and s.svanberg-Digital detection of Gas Absorption Harmonics based on Fourier Analysis (wavelet Modulation Spectroscopy-Digital detection of Gas Absorption Harmonics on Fourier Analysis), Applied Optics 54,2254(2015), which is incorporated herein by reference.

Alternatively, an analog lock-in-amplifier (analog lock-in-amplifier) may be used in some examples. The analog lock-in amplifier may be connected to the control unit 8.

Alternatively, a threshold may be selected in some examples. When the measured value reaches or exceeds the selected threshold value, an alarm 15 may be activated for the medical staff. The alarm 15 may be an audible alarm or an electronic alarm to a monitoring center.

Fig. 2A to 2D show different examples of how an endotracheal tube (endotracheal tube) is utilized.

Fig. 3 shows an example in which diffuse light is injected using the working channel of a bronchoscope.

It is observed that the same device, modified by some, can be used to inject light from the outside into the human body, for example by means of a feeding tube passing through the oesophagus, without using a ventilator or bronchoscope with a tracheal tube.

In these cases, it is possible to pass a beam having a sufficiently large surface (for example, several cm)²) A scattering medium in contact with the skin to expand and diffuse the light. This arrangement makes it possible to avoid local increases in tissue temperature and achieve eye safety.

Fig. 1 shows an exemplary configuration of the disclosed apparatus and system. The patient 1 is connected to a medical ventilator 2 via an introduction member 3 (e.g., a bronchoscope, a tracheal tube, an endotracheal tube, or the like) connected to a trachea 4.

In some other examples, the introduction member 3 may be a nasogastric tube, for example.

Light sources 5,6 (e.g., lasers) having wavelengths associated with free gases of interest (e.g., oxygen, Nitric Oxide (NO), and carbon dioxide) and a reference gas (e.g., water vapor).

In some examples, other gases besides water vapor may be used as the reference gas. The requirement is only that the gas concentration can be calculated without using the path length travelled by the detected light.

Alternatively, in other examples, only one light source may be used. In some other examples, more than two light sources may be used to detect more gases, gas distributions, or gas concentrations.

Alternatively, other configurations of the light source are possible when using other methods related to GASMAS as described previously.

The light source is connected to a drive unit 7 controlled by a control unit 8.

In some examples, the measurements of free gas in the lungs may be used to influence a controller 9 provided for controlling the medical ventilator 2. Alternatively and/or additionally, in some examples, the measurements of the control unit 8 may be used for administration of the drug 10.

Light is emitted to the tissue via the optical fiber 11. Light from individual optical fibers 12 connected to the light sources 5,6, e.g. semiconductor lasers, may be connected to a single optical fiber 11.

Additionally, in some examples, a small portion of the light to be injected may be diverted optically (e.g., by an optical fiber) to the calibration unit 13.

The detector 14 is configured to be positioned at a skin location of the patient's chest to detect the transmitted diffuse light. The detected light carries information about the concentration of gas in the lungs or the distribution of gas in the lung tissue, such as the concentration or distribution of oxygen, Nitric Oxide (NO) and carbon dioxide.

Additionally, in some examples, the alarm 15 may be activated when the measured value meets or exceeds a selected threshold.

Fig. 2A to 2D show different examples of coupling light from an optical fiber to tissue for measuring lung function.

Fig. 2A shows an example of an endotracheal tube 3 (e.g., an endotracheal tube), a balloon or sleeve 16 being inflatable to prevent air leakage alongside the endotracheal tube 3, the endotracheal tube 3 including an optical fiber 11 for transmitting light down the trachea.

Fig. 2B shows an example of an optical fiber 11 placed down an endotracheal tube (e.g., an endotracheal tube) to the end of the endotracheal tube. At the end, a light diffuser 17 is arranged at the end of the optical fiber 11.

Fig. 2C shows an example of how the light in the optical fiber 11 is connected to an end section 18 of an endotracheal tube (e.g., an endotracheal tube). The end sections are made of a non-absorbing but strongly light scattering material.

Fig. 2D shows an example where light from the optical fiber 11 may be coupled to the balloon or sleeve 16. The balloon or sleeve may be made of a non-absorbing but light-scattering material. In some examples, the inner wall has a coating 19 of light reflective material.

In one example, the laser light source is applied through the esophagus rather than through the trachea. In this example, the laser light source may be combined with a nasogastric tube used for most infants in neonatal intensive care. The use of a nasogastric tube for light application is advantageous because most infants already need to insert such a device, and therefore no additional devices need to be introduced for most patients. It is also advantageous because the esophageal environment is less susceptible to infection, thus potentially alleviating the sterility requirements of the device. It is also advantageous that, since the esophagus usually mostly collapses, no dilation sleeve may be needed to create good optical contact between the light source and the tissue. In addition, the lower part of the lung can be reached more easily.

The light source should be located in the esophagus near the lungs. In one example, a laser-guided optical fiber is coupled to a nasogastric tube so that the optical fiber travels along the tube to an appropriate location along the tube. The nasogastric tube has markings that indicate the depth of tube insertion, and these markings can be used to determine the location of the light source in the esophagus.

In a preferred example, during the manufacture of the nasogastric tube, a laser-guided optical fiber is embedded in the tube wall, making the nasogastric tube and laser light guide a single device.

In one example, the distal end of the optical fiber terminates with a light diffuser that distributes light over a larger area than provided by the fiber tip alone. In a preferred example, when embedding the optical fibers into the tube wall as described above, the diffuser is realized by designing the tube wall in front of the tip of the optical fiber with light scattering properties such that the light is diffused over an area of the tube along the desired feature of the corresponding diffuser. In an alternative example, the diffuser is made as a separate component embedded in the tube wall similar to the optical fiber.

In one example, the diffuser may alternatively be made part of an expandable cannula similar to the diffuser described above in connection with the trachea.

The optical fiber may also be positioned in the nasogastric tube in such a way that the optical fiber may be sequentially moved to different locations along the tube to facilitate a complete chromatogram of the gas profile (e.g., oxygen, Nitric Oxide (NO), and carbon dioxide profiles) using multiple detectors 14.

Alternatively, multiple optical fibers may be used in parallel at different locations to facilitate a complete chromatogram of a gas profile (e.g., oxygen, Nitric Oxide (NO), and carbon dioxide profiles) using multiple detectors 14.

In an alternative example, the light source on the nasogastric tube is implemented by placing one or more laser diodes directly at the location where the light source is supposed to be and with wires for driving the laser diodes along the nasogastric tube. This implementation may also be applied in the case of endotracheal tubes.

Fig. 4A shows an optical fiber 41 in combination with a nasogastric tube 46 inserted into the esophagus 42. The relationship to the trachea 43 and lungs 44 is also shown. At the distal end of the optical fiber 41, there may also be an optical diffuser 45. The upper part of the stomach 47 is also shown.

Fig. 4B shows a close-up of optical fiber 41 embedded in the wall of nasogastric tube 46. A nasogastric tube is inserted into the esophagus 42. In this example, the optical fiber has a diffuser 45 at the distal end of the optical fiber 41. In other examples, the optical fiber 41 may not have a diffuser.

The same examples of the described embodiments regarding the introduction of optical fibers for measuring free gas into the lumen of the trachea and esophagus may also be applicable in the case of using, for example, an endoscope or colonoscope to assess abnormal gas distribution or gas concentration in the intestine or digestive tract. In these cases, the detector may be adapted to be positioned on the abdomen of the subject.

The invention has been described above with reference to specific examples. However, other examples than the ones described above are equally possible within the scope of the present disclosure. Different method steps than those described above, performing the method by hardware or software, may be provided within the scope of the invention. The different features and steps of the invention may be combined in other combinations than those described. The scope of the present disclosure is limited only by the appended claims.

The indefinite articles "a" and "an" used in the specification and claims should be understood to mean "at least one" unless explicitly stated to the contrary. The expression "and/or" as used herein in the specification and claims should be understood to mean "one or both of" the elements so combined, i.e. present in some cases joined and in other cases present separately.