RU2625258C2 - Method and device for dynamic gas analysis built into expiration main of breather mask - Google Patents

Abstract

FIELD: measuring equipment.

SUBSTANCE: device includes monochromatic pairs, which represent a solid-state monochromatic radiator based on a diode laser and a solid-state monochromatic receiver. Monochromatic pairs are located in segmented profiled rigid elements built into the expiration main of the breather mask behind the expiratory valve. The segmented elements can have the form of a ring, a linear device with a conditioned aspect ratio or an n-faced prism. The optical path of the beam from the radiator to the receiver provides overlapping of the entire cross-sectional area of the air main, which is realized due to the orientation of the radiator and receiver relative to each other and the reflective characteristics of the working surfaces of the segmented element. Flow characteristics of the exhaled air or respiratory mixture are fixed by a complex of pressure and humidity sensors.

EFFECT: ensuring continuous measurements over a long period of time.

6 cl, 4 dwg

Description

FIELD OF TECHNOLOGY

The invention relates to systems for dynamic control of gaseous media and devices for non-invasive monitoring of the state of a living organism (patient), both when using various respiratory mixtures and without it, under the influence of physical, psychological, stress loads, as well as various kinds of painful conditions, in composition exhaled air; assessing the functional state of the biological systems of the body for a long time under the influence of multidirectional overloads; diagnostics in determining the severity of the condition for sorting victims as a result of emergency situations; determining the physical state of the body during training, under the influence of loads of a different nature; monitoring the status of crew members of autonomous isolated systems and manned vehicles.

PROTOTYPES (BACKGROUND OF THE INVENTION)

The dynamic gas analysis method is implemented in the patents SU 1088462 "Aerodynamic gas analyzer" and the dependent SU 472287.

The aerodynamic gas analyzer contains a bridge of hydraulic resistances, one of which is made variable using a differential pressure indicator. A mesh-type membrane element with a pore diameter exceeding the mean free path of the molecule of the analyzed gas medium is also used. In this way, only the quantitative gas flow rate is determined, but not the percentage of the individual components of the gas mixture.

To obtain a reliable result, the device requires equalizing the temperature and pressure of the gas being determined. It follows from this that operation under a viscous flow regime with variable characteristics of the gas flow is possible only on selected samples in which the stated requirements for gas temperature and pressure are observed.

This device circuit is designed to work with dry air and without humidity spikes. It is known that the respiratory process is characterized by a change in pressure in the exhalation line within the respiratory cycle and the humidity of the exhaled air is close to 100%.

In gas analysis of the respiratory process, the requirement to equalize the pressure in the exhalation line is not feasible and can be met only with sampling, which was implemented in airborne gas analyzers, since interference in the process of voluntary breathing can be dangerous for the life of the object (patient), however, sampling does not implement the principle of dynamic gas analysis fully and with long-term monitoring with a high sampling frequency and a large number of measurements leads to the accumulation of errors.

There are a fairly large number of gas analyzers that implement various operating principles, such as chemisorption, semiconductor and photoionization, which are also used in on-board systems. These principles were most fully described in patent RU 2502065 "Method for analyzing the composition of gas mixtures and a gas analyzer for its implementation", which describes electrochemical and photoionization cells using chemical filters, and in patent RU 2502066 "Gas measuring device and method of its operation", which describes semiconductor circuit.

In patent RU 2502065 “Method for analyzing the composition of gas mixtures and a gas analyzer for its implementation”, two types of sensors are proposed for analyzing the gas environment: electrochemical and photoionization sensors, which, due to their design features, tend to accumulate errors during prolonged use. At the same time, in order to obtain a reliable result, it is proposed to measure twice: using the chemical filters at the sensor inputs that separate the individual component of the gas mixture determined by this sensor from the gas mixture entering each sensor and without using a filter, comparing the results obtained and based on this making conclusions about the concentration of the determined component in the test mixture. For this, it is proposed to use drives and rods of various types. Analysis of this design revealed the following disadvantages:

1. The need for sampling.

2. Low selectivity and the duration of the testimony when measuring low concentrations.

3. Double measurement of the composition of the gas mixture takes time and can cause a residual effect during secondary measurement, which leads to the accumulation of errors. This method gives a relatively low frequency of taking readings, which is clearly insufficient for a dynamic assessment of the condition of a patient under the influence of loads of a different nature.

4. The complexity of the system due to the mechanisms of movement of the filters.

5. High risk of distortion of the result in the presence of induced electromagnetic fields.

6. Accumulation of errors during prolonged and continuous use.

In the patent RU 2502066 "Gas measuring device and method of its operation" (this application claims priority of provisional application US 60/997084, filed October 1, 2007.) to measure the presence of a given gas in a fluid, it is proposed to use semiconductor cells with heating elements to maintain working temperature. The analysis occurs by recording changes in at least one of the electrical properties of the semiconductor. It also talks about the possibility of embedding and portability of this device. When analyzing this device, the following disadvantages were highlighted:

1. The complexity of the system. Heating and maintaining the operating temperature of the sensitive element requires relatively powerful power sources, which is difficult to ensure with prolonged use in a portable device.

2. The main disadvantage of semiconductor sensors is the fast process of error accumulation in comparison with other types of sensors. This decrease in accuracy over time leads to a distortion of the results and does not make it possible to track the change in the patient’s condition in real time with prolonged use, since the concentration of the element in small doses can be within the error range. For this reason, frequent calibration and replacement of sensors is necessary, which is not always practical and possible.

To compensate for most of these shortcomings can gas analyzer that implements the principles of diode-laser spectroscopy. This principle gives the following advantages: speed; accuracy; the practical absence of error accumulation over time, characteristic of many types of gas analyzers, especially semiconductor ones; the possibility of continuous characterization.

The closest to the prototype are the following gas analyzers that implement the principles of laser spectroscopy, but having, in comparison with the proposed device, a number of disadvantages:

I) RU 2468343 “Gas analyzer based on a microspectrometer” (this application claims priority according to 35 USC § 120 as a partial continuation (CIP) of US patent application No. 11 / 648,851, filed December 29, 2006 and filed patent US 7605370 "Microspectrometer gas analyzer ").

The disadvantage of this gas analyzer is the use of complex mirror dynamic systems that are not designed to work in the conditions of multidirectional mechanical overloads and vibration. In addition, while minimizing the size of the system, which transfers it to the field of MEMS technologies, there is a certain difficulty in installing elements of the system, leading to its cost increase.

II) RU 2384836 C1 "A method for simultaneously determining the concentration of CO and CO2 molecules in a gaseous medium and a device for simultaneously determining the concentration of CO and CO2 molecules in a gaseous medium."

The disadvantages of this gas analyzer are the use of a multi-way cuvette with optical lenses that are not designed to work in conditions of multidirectional mechanical overloads and vibrations, as well as working with gas samples or expired air. This determines the size of the product is significantly larger than the proposed development, and a fairly complex scheme through the use of optical components.

III) RU 2313078 "Method for the detection of gases using a spectrometer based on a semiconductor diode laser and a spectrometer for its implementation."

The developers of this patent refer to various existing models of quantum cascade lasers without indicating the size of the optical cell, but on the models proposed by the industry, the cell length is quite large, and in some cases is equipped with an additional optical system, which, compared with the proposed device, is a drawback.

The main disadvantage is the need for cooling and thermal stabilization of quantum cascade lasers, which make it difficult to work at high temperatures and local overheating.

The aim of the invention is the determination and interpretation of changes in the composition of the respiratory mixture during expiration in real time during the respiratory cycle, that is, the implementation of the principle of dynamic gas analysis in determining the quantitative and qualitative composition of the air exhaled by the patient by continuously analyzing the absorption spectra of the detected gases using segmented elements based on selected monochromatic pairs throughout the entire use of the respiratory mask, including prefecture, more 2 hours and, thus, continuous monitoring and, if necessary, correction of the object status (patient) by implementing a feedback control performed using algorithms supply breathing gas components and, due to this, a change in its chemical composition.

SUMMARY OF THE INVENTION

The claimed technical result is achieved by the fact that the method of dynamic gas analysis is implemented through continuous analysis of the passing stream of exhaled air or breathing mixture over the entire cross-sectional area of the air line without sampling, which allows, due to the use of diode laser spectroscopy and a set of pressure and humidity sensors, to work with gas mixtures of arbitrary humidity and nature of the flow, as well as of various origin and composition, and a device for dynamic gas analysis The created on the basis of selected monochromatic pairs. A monochromatic couple is a solid-state monochromatic emitter based on a diode laser and a solid-state monochromatic receiver, possibly equipped with an additional monochromatic filter, mounted in a segmented profiled rigid ring (Fig. 1a) or a linear device with opposite light-absorbing and light-reflecting sides (Fig. 1b) or n-facet prism (Fig. 1c), built into the exhalation line of the respiratory mask behind the exhalation valve, and the selection of monochrom ble pairs done depending on the defined list of gases selected in accordance with the set for each specific case task, and may be implemented as a single pair of monochromatic and parallel or sequentially installed monochromatic pairs. The profile of the ring, prism or linear device, as well as the relative position of the emitter and the receiver, is calculated for each of the gases to be determined in such a way as to ensure a beam path sufficient to obtain a reliable result of determining the concentration of the component to be determined on the basis of the Bouger-Lambert-Behr law.

The concentration measurements of various components of the gas mixture are carried out in previously calculated non-overlapping spectral ranges for various monochromatic pairs. Segmented elements with pairs of emitter-receiver are installed in the exhalation line into a special cassette-type device and can be replaced if necessary. In this case, the alignment of the emitter and receiver is pre-installed, that is, it is made on removable blocks in the process of their manufacture. Segmented elements are divided into the following types.

Type 1. A ring with a reflective working surface of a diameter close to the diameter of the exhalation line of the breathing mask, into the forming surface of which a pair of emitter-receiver is built at a strictly defined angle calculated for each component to be determined and relative to each other and height, determined by size and relative position embedded components of the emitter and receiver. (Fig. 1a)

Type 2. A linear device, which is a rectangle with a predetermined aspect ratio and height, determined by the dimensions of the built-in components of the emitter and receiver, the two opposite sides being light-reflecting and the other two being light-absorbing, while the overlapping cross-sectional areas of the exhalation line and the linear device provide the maximum the effective ratio of their areas and minimal turbulization of the flowing stream, and the relative position of the elements of the monochromatic pair of provides the necessary path length of the beam to determine the concentration of the investigated component of the gas mixture. (Fig. 1b)

Type 3. Thin-walled rigid n-facet prism with a height determined by the size and relative position of the built-in components of the emitter and receiver, inscribed in a circle of diameter close to the diameter of the exhalation line of the breathing mask and the number of faces depending on the wavelength of the element being determined, where all faces have reflective surfaces, and the cross-sectional area of the exhalation line and the device in the form of an n-faced prism provide maximum mutual overlap, the path length of the beam necessary for obtaining a reliable result of determining the concentration of the determined component and minimal turbulization of the flowing stream. (Fig. 1c)

The device consists of segmented elements that are built into the exhalation line of the breathing mask, which are connected via a signal converter via a signal converter via a shielded pair, either an optical fiber cable, which is an information highway, or via a wireless communication channel. The control unit uses direct and feedback channels and is connected to a computer system (Fig. 2). The readings taken from the radiation receiver depend on the concentrations of the test substances in the gas medium and are compared with the values of similar indicators accepted as a physiological norm for the respective conditions. In the event of a deviation from the norm, the signal is supplied both to the object and to the external control and management bodies.

To implement the dynamic gas analysis method, the device is equipped with a set of pressure and humidity sensors, and to increase the measurement accuracy and prevent contamination of the segmented elements with an additional replaceable membrane filter installed in front of the first segmented element.

The claimed technical result is achieved by the fact that the method of dynamic gas analysis, which is implemented by continuously analyzing the passing stream of exhaled air or breathing mixture over the entire cross-sectional area of the air line without sampling, allows, through the use of diode-laser spectroscopy and a set of pressure and humidity sensors, work with gas mixtures of arbitrary humidity and nature of the flow, as well as of various origin and composition.

A patent search in the field of dynamic portable built-in gas analyzers that implement the method of diode-laser spectroscopy and operating on monochromatic pairs has not revealed similar developments both in Russia and abroad.

The proposed method and device differ from prototypes in the following points:

1) Measurement and processing of the received information takes place in real time during the entire time the gas analyzer is used, taking into account pressure and humidity drops in the exhaled air stream.

2) The use of a diode laser spectroscopy method for a dynamic gas analysis method based on a continuous analysis of a passing gas stream using a set of monochromatic emitter-receiver pairs and pressure sensors to obtain a relationship between the total volume of expired air and the amount of the analyzed component in the gas mixture, allows to obtain information both the quantitative consumption of the gas mixture and the concentration of the determined components in real time under the viscous flow regime with variable Characteristics of the gas stream.

3) The device works with a passing stream of exhaled air, and not with gas samples, that is, it is installed in the exhalation line of the breathing mask and does not use a cuvette for sampling.

4) Specially selected emitter-receiver pairs are used, due to which the error in determining the concentration of the analyte is reduced, and the spectral ranges for determining the concentration of substances are selected taking into account the prevention of their mutual overlap, calculated for a given combination of the determined components.

5) The absence of separately installed focusing elements eliminates the effects of defocusing due to vibration, lateral accelerations and other factors of mechanical stress.

6) Weight and size characteristics are minimized: a system based on monochromatic pairs is built into the exhalation line of a breathing mask.

7) The elements used for the implementation of the diode-laser spectroscopy method for monochromatic pairs do not require cryogenic cooling to maintain special operating conditions.

8) The use of the diode-laser spectrometry method in the proposed gas analyzer, in contrast to photoionization and semiconductor sensors, avoids the accumulation of measurement errors over time. Sensors of this type are not affected by external influences and have no inertia, that is, they can take readings during the respiratory cycle repeatedly and for a long time.

The invention is explained in the diagrams:

FIG. 1. Types of segmented elements.

1a - a ring with a reflective working surface; 1b is a linear device; 1c - n-facet prism (1 - emitter, 2 - receiver, 3 - reflective surface, 4 - approximate beam path, 5 - light-absorbing surface).

FIG. 2. Schematic diagram of the operation of a segmented element.

DESCRIPTION OF WORK AND APPLICABILITY.

The gas analyzer operates as follows. The air exhaled by the patient enters the exhalation line of the breathing mask. Further, when air passes through the expiratory line through built-in segmented elements, the chemical composition of the exhaled air is removed and decoded by transmitting a signal from the emitter to the receiver of a monochromatic pair and then through the information line or wireless channel to the control unit with direct and feedback elements and connected to the information processing unit, where the decryption and interpretation of the received signal takes place, after which you send Xia signal, both the patient and the external organs monitoring and control, including the control unit and the control unit Plural Component breathing mixture.

To prevent contamination of the reflective surface of the segmented elements with waste products, a replaceable membrane filter can be installed in front of the segmented elements at the beginning of the expiration line.

In order to estimate the volume of exhaled air, at least two pressure sensors are installed in the system: one in the breathing mixture supply system, and the other / others on the exhalation line behind the filter and in front of / between the segmented elements, which allows receiving information about the volumes entering the mask and exhaled air, as well as the concentration of the detected components in real time, regardless of the pressure drops in the line. An expiratory humidity sensor is also installed.

This device can be used both independently and in conjunction with a system for monitoring the state and emergency assistance of long-term wear.

In the case of using this gas analyzer in medical institutions, as well as when using specialists in training systems working under conditions of various types of overload, including the preparation of climbers, scuba divers, emergency workers, flight personnel, feedback can only be presented as a warning system attendants. The decision to change the composition of the respiratory mixture or the additional introduction of other drugs in such cases is taken by the maintenance staff.

The invention can be used in aviation, including being integrated into the respiratory mask of a pilot; medicine as diagnostic equipment and disaster medicine (including in resuscitation equipment installed on vehicles); in the protective equipment and equipment of the Ministry of Emergencies during the elimination of high-risk fires (when there is a danger of the release of harmful substances) and technological disasters; in the equipment of scuba divers and divers when conducting underwater operations with high physical activity and diving to great depths; as part of climbing oxygen equipment.

Claims (6)

1. A method of dynamic gas analysis for non-invasive monitoring of the state of an object (patient) and continuous monitoring of gaseous media, continuous assessment of the functional state of biological systems of the body, diagnostics for determining the severity of the condition, carried out by diode-laser spectroscopy, based on continuous analysis of the passing stream of exhaled air ( respiratory mixture) over the entire cross-sectional area of the air line without sampling using a set of selected monochromatic pairs and radiator receiver and integrated in the air line of the complex of pressure and humidity sensors. 2. The method according to p. 1, characterized in that as the working medium can be used gaseous media of various origin and composition. 3. A device for dynamic monitoring of gaseous media and non-invasive monitoring of the state of an object (patient), continuous assessment of the functional state of biological systems of the body, diagnostics for determining the severity of a state, created on the basis of selected monochromatic pairs, which are a solid-state monochromatic emitter based on a diode laser and a solid-state monochromatic receiver, possibly equipped with an additional built-in monochromatic filter, mounted in a segmented a profiled rigid element, which can be in the form of a ring, or a linear device with a predetermined aspect ratio, or an n-facet prism, which is built into the exhalation line of the breathing mask behind the exhalation valve, and the selection of monochromatic pairs is carried out in accordance with a pre-selected set of detected gases according to the set for each specific case, the task can be implemented as a single monochromatic pair, or in parallel or sequentially set monochromatic pairs, which can be combined into groups of two or more elements depending on the amount of detected gases, while the optical path of the beam from the emitter to the receiver overlaps the entire cross-sectional area of the air line, which is realized due to the orientation of the emitter and receiver relative to each other and reflective characteristics of the working surfaces of the segmented element; the characteristics of the passing stream of exhaled air (breathing mixture) are recorded by a set of pressure and humidity sensors. 4. The device according to p. 3, characterized in that it is equipped with a control unit that provides the required mode of taking and decoding information, and can be used both in on-board monitoring and life support systems, and in mobile, including portable or stationary diagnostic complexes, also in the presence of feedback, the obtained information can be used in the control system for the supply of components of respiratory mixtures. 5. The device according to p. 3, characterized in that it is equipped with an additional replaceable membrane filter installed in front of the first segmented element. 6. The device according to p. 3, characterized in that it can be used in conjunction with various systems for monitoring the state and emergency assistance for long-term use (wearing).

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