RU193583U1 - SPIROMETER - Google Patents

Abstract

The utility model relates to medicine, namely to the field of measurements for diagnostic purposes and can be used to study the function of external respiration in normal and pathological conditions, both for individual use and as part of telemedicine complexes for monitoring the respiratory system of patients with chronic bronchopulmonary diseases . The spirometer contains a housing inside which a measuring tube is located. A mouthpiece is installed at the inlet of the measuring tube. Inside the measuring tube is divided by a partition passing along its axis, with the formation of two equal channels, each channel being made with two outward taps that are opposite and coaxial to each other. All bends are made at an angle of no more than 30 ° to the longitudinal axis of the measuring tube so that the bends located in different channels are parallel to each other in pairs. The first ultrasonic signal emitter is located in one channel in the tap located on the output side of the measuring tube, and the first ultrasonic signal receiver is located in the tap located on the input side of the measuring tube. In the second channel in the tap located on the side of the entrance to the measuring tube, there is a second emitter, and in the tap located on the side of the outlet of the measuring tube, a second receiver is located. The emitters and receivers of the ultrasonic signal, located next to each other, in parallel taps, are insulated by gaskets. The emitters of the ultrasonic signal are connected to the generator. The first signal amplifier and the first analog-to-digital converters are connected in series to the first receiver. The second signal amplifier and the second analog-to-digital converters are connected in series to the second receiver. The first and second analog-to-digital converters are connected to the calculation unit, which is connected to the radio transmitter. The first and second analog-to-digital converters, a generator, a calculation unit, and a radio transmitter are connected to a power source. Technical result: does not need periodic calibration during operation. 6 ill.

Description

The utility model relates to medicine, namely to the field of measurements for diagnostic purposes and can be used to study the function of external respiration in normal and pathological conditions, both for individual use and as part of telemedicine complexes for monitoring the respiratory system of patients with chronic bronchopulmonary diseases .

Known pocket medical spirometer [US 7383740 B2, IPC A61B 5/087, A61B 5/093, G01F 1/20, G01F 1/32, publ. 06/10/2008], comprising a housing with inlet and outlet openings for air flow and a measuring unit for measuring the speed of the total flow between the inlet and outlet when the user exhales through a spirometer. The measuring unit contains an oscillatory flow generator with a frequency depending on the flow velocity through it and a converter for converting the indicated oscillatory parameter into an electrical signal. The unit for measuring the velocity of the total flow is located inside the housing with the formation of a bypass channel through the generator, so that the total flow is divided into bypass flow and the measurement flow. The generator has two feedback channels, each with a pressure port. Both holes are connected to a pressure sensor in the form of a flexible membrane with a piezoelectric element mounted on it. The common flow velocity measuring unit comprises a second generator defining a second parallel measurement path opposite the first flow measuring path, so that a second measurement flow is created when the user takes a breath through the spirometer. Valve means are provided, so that the first flow measurement path is open only when the user exhales, while the second flow measurement path is open only when the user takes a breath. Valve means include one non-return valve associated with the first flow measurement channel and a second non-return valve associated with the second flow measurement channel. Both generators are connected to the converter. The common flow velocity measuring unit comprises a second converter for converting the oscillatory flow of the second generator into a second electrical signal, so that when exhaling, the first generator operates in a direct flow, while the generator operates in a reverse flow, and vice versa. Both transducers are connected to an electronic processor.

Such a spirometer has a complex structure and needs periodic calibration during operation.

Known ultrasonic spirometer [EP 597060 B1, IPC AB 5/087; A61B 5/091; G01F 1/66, publ. 04/16/1997], comprising a housing with a measuring tube inside. The measuring tube inside is made with two bends-cells, which are located with an inclined or perpendicular alignment to the axis of the duct. A transmitter is located in one cell and an ultrasonic signal receiver in another. A precision fit, easily replaceable sterile duct can be inserted into the measuring tube. The sterile duct inserted into the measuring tube has test windows at the transition between it and the test section, so that the inserts are inserted into the corresponding openings, transparent to acoustic waves, but impervious to microorganisms and dirt. The inserts are either made of elastic polymer, or may consist of plates of sheets of polyethylene terephthalate.

Such a technical solution does not provide the necessary measurement accuracy without periodic calibration.

Known respiratory flow meter [US 4425805 A, IPC A61B 5/08; G01F 1/66; G01P 5/00, publ. January 17, 1984], selected as a prototype, comprising: a pipeline through which exhalation and inhalation flow; a pair of recesses formed on the inner wall of the pipeline along a line inclined relative to the direction of flow of the respiratory gas; a pair of ultrasonic transducers located in these recesses, and their ultrasonic transmitting and receiving surfaces are oppositely facing each other along the specified line; means for simultaneously switching said ultrasonic transducers between the excitation mode and the reception mode; digital counting means for measuring any of two propagation times required for an ultrasonic wave emitted by one of said pair of controllable transducers to reach another transducer and the difference between said two propagation times; means for determining a flow direction of said breathing gas; means for generating a signal for requesting a calculation of the flow rate of the respiratory gas each time said pair of transducers is driven; means for storing said flow direction, said two propagation times, and said propagation time difference in response to said calculation request signal; and means for calculating and maintaining the flow rate of said breathing gas based on said stored values. To prevent condensation, an electric heater is placed on the periphery of the pipeline and around the ultrasonic transducers. The means for calculating and storing the flow rate of the respiratory gas includes an arithmetic processor. The disadvantages of this device are:

low signal-to-noise ratio of the pulse measurement method due to the fact that it is necessary to detect the appearance of a pulse;

the need to measure the phase angle between the signals with very high absolute accuracy, while the maximum phase jitter of the clock signal should not exceed 500 ps.

As a result, such devices are expensive to manufacture and require periodic calibration to correct deviations in the frequency of the clock.

The technical result of the proposed utility model is to expand the arsenal of tools for spirometry.

The proposed spirometer, as in the prototype, contains a measuring tube with two outward outlets, inclined relative to the direction of the respiratory flow, ultrasonic transducers, a unit for calculating the air flow rate are located in the outlets.

Unlike the prototype, the measuring tube is located inside the housing. A mouthpiece is installed at the inlet of the measuring tube. Inside the measuring tube is divided by a partition passing along its axis, with the formation of two equal channels, each channel being made with two outward taps that are opposite and coaxial to each other. All bends are made at an angle of no more than 30 ° to the longitudinal axis of the measuring tube so that the bends located in different channels are parallel to each other in pairs. In one channel in the tap located on the output side of the measuring tube, the first emitter of the ultrasonic signal is located, and in the tap located on the input side of the measuring tube, the first ultrasonic signal receiver is located. In the second channel in the tap located on the side of the inlet to the measuring tube, there is a second emitter, and in the tap located on the side of the outlet of the measuring tube, a second receiver is located. The emitters and receivers of the ultrasonic signal, located next to each other in parallel taps, are insulated by gaskets. The emitters of the ultrasonic signal are connected to the generator. The first signal amplifier and the first analog-to-digital converters are connected in series to the first receiver. A second signal amplifier and a second analog-to-digital converters are connected in series to the second receiver. The first and second analog-to-digital converters are connected to the calculation unit, which is connected to the radio transmitter. The first and second analog-to-digital converters, a generator, a calculation unit, and a radio transmitter are connected to a power source.

The proposed spirometer allows you to measure the air flow rate using a differential constant-wave scheme through the noise-resistant method of the phase difference of the correlation type. Each receiver-emitter pair in the measuring tube is separated from each other by a soundproofing partition, which eliminates the mutual influence of the measuring channels on each other.

The choice of the location of the taps in the measuring tube at an angle of no more than 30 ° to the longitudinal axis of the measuring tube is due to the fact that with an increase in the angle, the influence of the air velocity on the speed of sound propagation in air decreases.

Such a spirometer does not need periodic calibration during operation, since measurements are made continuously and differentially in each channel.

In Fig 1 shows a cross section of a spirometer, the main view.

In FIG. 2 shows an isometric view of a spirometer (part of the housing is not conventionally shown).

In FIG. 3 - shows a measuring tube with installed emitters and receivers, where a) is a general view, b) is a side view, c) is a section B-B, d) is a section A-A.

In FIG. 4 shows a longitudinal section through a measuring tube.

In FIG. 5 shows sound dampers.

In FIG. 6 shows an electrical diagram of a spirometer.

The spirometer comprises a housing 1 made integrally (Fig. 1) with a measuring tube 2 inside. At the inlet of the measuring tube 2, a removable mouthpiece 3 is installed. Inside the measuring tube 2 is divided by a partition 4 (Fig. 2), passing along its axis, with the formation of two equal channels 5 and 6 (Fig. 3d). Each channel 5 and 6 is made with two cylindrical bends 7, 8 and 9, 10 (Fig. 3, c) outward, which are located opposite and coaxial to each other. The taps 7, 8 and 9, 10 are made at an angle a, which is not more than 30 ° to the longitudinal axis of the measuring tube 2 (Fig. 4) so that the taps 7, 8 and 9, 10 located in different channels 5 and 6 are parallel each other in pairs.

In the bends 7, 8 of one channel 6, respectively, the first emitter 11 (I1) and the first receiver 12 (III) of the ultrasonic signal are installed. In the taps 9, 10 of the other channel 5, respectively, a second emitter 13 (I2) and a second receiver 14 (P2) of the ultrasonic signal are installed. In parallel to each other taps 7 and 9, 8 and 10 of channels 5, 6, the adjacent first emitter 11 (I1) and second receiver 14 (P2), as well as the second emitter 13 (I2) and the first receiver 12 (P1) are insulated by spacers 15 and 16, for example, of foam.

The first 11 (I1) and second 13 (I2) emitters of the ultrasonic signal are connected to an oscillator 17 (GEN) generating rectangular pulses with a frequency of 40 to 120 kHz.

The output of the first receiver 12 (P1) of the ultrasonic signal (Fig. 6) is connected in series with the first signal amplifier 18 (U1) and the first analog-to-digital converters 19 (ADC1). The second signal amplifier 20 (U2) and the second analog-to-digital converters 21 (ADC2) are connected in series to the output of the second receiver 14 (P2) of the ultrasonic signal. The outputs of the first 19 (ADC1) and second 21 (ADC2) analog-to-digital converter are connected to the calculation unit 22 (BR) which is connected to the radio transmitter 23 (RP). The first 19 (ADC1) and second 21 (ADC2) analog-to-digital converter, generator 17 (GEN), calculation unit 22 (BR) and radio transmitter 23 (RP) are connected to control unit 24 (control unit), which is connected to power supply 25 ( IP).

As the emitters 11 (I1) and 13 (I2) and the receivers of ultrasonic signals 12 (P1) and 14 (P2), ultrasonic emitters and receivers of the manufacturer MURATA models MA40S4S and MA40S4R can be used. Amplifiers 18 (U1), 20 (U2), analog-to-digital converters 19 (ADC 1), 21 (FTP), calculation unit 22 (BR), control unit 24 (BU) can be performed on the STM32F302CB series microcontroller. The radio transmitter 23 (RP) can be performed on the chip DA14583. Power source 25 (IP) is a chemical power source, for example, a 18650 standard battery.

To control the device may be provided with a button connected to the control unit 24 (CU), as well as the presence of an indicator in the form of LEDs to display the status of the device.

The device operates as follows:

A removable disposable mouthpiece 3 is connected to the measuring tube 2, which ensures the fulfillment of hygiene requirements for spirometry.

During respiratory movements, the air flow moves along two channels 5 and 6 of the measuring tube 2, due to the presence of a soundproofing partition 4, while the air flow rate in both channels is the same, and depends on the cross-sectional area of the measuring tube 2 and the pressure difference at its inlet and exit.

When performing respiratory movements, air moves along the measuring tube 2, while the pressure at the open end of the measuring tube is atmospheric. The emitters 11 (I1) and 13 (I2) of ultrasonic signals generate ultrasonic vibrations with a frequency determined by a rectangular pulse generator 17 (GEN). The phase difference Δϕ between pulses supplied to different emitters is adjusted in the factory calibration process to ensure zero phase difference at the ultrasonic signal receivers 12 (Ш) and 14 (П2). The ultrasonic signal of the first emitter 11 (I1) propagates at an angle α equal to, for example, 30 ° to the longitudinal axis of the tube 2. The time during which the signal of the first emitter 11 (I1) reaches the corresponding receiver 12 (P2) is determined by the speed of sound propagation in air , the distance between the emitters 11 (I1), 13 (I2) and the receivers 12 (P1), 14 (P2), as well as the speed of air flow. Due to the movement of air in the tube 2, a difference occurs in the propagation time of the signal, a phase shift occurs at the receivers 12 (P1) and 14 (P2). To measure the phase shift, the signal from the receivers 12 (P1) and 14 (P2) of the ultrasonic signal is amplified by the corresponding amplifiers 18 (U1) and 20 (U2), and then converted into digital form using the corresponding analog-to-digital converters 19 (ADC1) and 21 (ADC2) and served in the calculation unit 22 (BR), where they determine the phase shift according to the equation:

where Δϕ is the phase shift;

s1 (i) and s2 (i) are samples of signals received from the first 19 (ADC1) and second 21 (ADC2) analog-to-digital converters.

The obtained value of the phase shift Δϕ is used to determine the air flow rate from the expression:

where ϑ is the air flow rate;

C is the speed of an ultrasonic wave in air;

L is the distance between the emitter and the receiver of the ultrasonic signal located in one channel;

ƒ is the frequency of the ultrasonic wave;

α is the angle between the longitudinal axis of the measuring tube and the longitudinal axis of the outlet.

The calculation of the value of the air flow rate is performed with a constant time interval, for example, 10 ms, which ultimately gives an array of values of the flow velocity ϑ _i . at every moment of time i.

This array ϑ _{i is} used to determine the volume of air inhaled and exhaled by the user according to the equation:

where ϑ _i is the air velocity at time i;

s is the total cross-sectional area of channels 5 and 6.

Using a radio transmitter 23 (RP) standard bluetooth low energy, the obtained values are transmitted to an external computer.

Claims (1)

A spirometer containing a measuring tube with two outward taps obliquely relative to the direction of the respiratory flow, ultrasonic transducers are located in the bends, an air flow velocity calculation unit, characterized in that the measuring tube is located inside the housing, a mouthpiece is installed at the inlet of the measuring tube, and the measuring tube is divided inside a partition passing along its axis, with the formation of two equal channels, and each channel is made with two outlets to the outside, which are located are opposite and coaxial to each other, all the bends are made at an angle of no more than 30 ° to the longitudinal axis of the measuring tube so that the bends located in different channels are parallel to each other in pairs, and in one channel in the bend located on the outlet side of the measuring tube the first emitter of the ultrasonic signal, and in the tap located on the input side of the measuring tube, the first receiver of the ultrasonic signal is located, in the second channel in the tap located on the input side of the measuring tube, put the second ultrasonic transducer signal and retraction located from the measuring tube exit, is located a second receiver of the ultrasonic signal, the emitters and receivers arranged side by side, in parallel to each other terminals of isolated spacers; emitters are connected to the generator, the first signal amplifier and the first analog-to-digital converters are connected in series to the first receiver; a second signal amplifier and a second analog-to-digital converters are connected in series to the second receiver, the first and second analog-to-digital converters are connected to a calculation unit that is connected to a radio transmitter, the first and second analog-to-digital converters, a generator, a calculation unit and a radio transmitter are connected to a power source .

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