KR100682026B1 - down-sized single directional respiratory air flow measuring tube - Google Patents

Abstract

A small, portable respiratory air flow meter for a respiratory air flow meter for use in self-examination by chronic respiratory diseases such as asthma is disclosed. The present invention comprises a cylindrical tube made of a one-time paper or plastic material and including an inlet and an outlet facing the mouth of the subject; It is installed close to the outlet side of the cylindrical tube, extends outward through the cylindrical tube from the top, the top is closed and in the inlet direction of the cylindrical tube to comprehensively measure the flow velocity between the center and the wall of the cylindrical tube. It includes a sensing rod having a plurality of sampling holes on one side for measuring the dynamic pressure in the respiratory air flow.

Description

Down-sized single directional respiratory air flow measuring tube

1 is a view for showing the principle of respiratory air flow measurement using the dynamic pressure.

2 is a view for explaining the structure of the respiratory tract of Korean Patent No. 432640 filed by the present applicant.

FIG. 3 is a view illustrating a structure of a sensing rod inserted into the breathing tube of FIG. 2.

4 is a cross-sectional view for explaining the structure of a small unidirectional air flow measurement breathing tube according to the present invention.

FIG. 5 is a block diagram of a test apparatus for dynamic pressure measurement and static pressure measurement for determining the size of the respiratory tract of FIG. 4.

FIG. 6 is a graph showing a correlation between a diameter of a respiratory tube and a maximum respiratory airflow value obtained through the test apparatus of FIG. 5.

7 is a graph showing the correlation between the diameter of the respiratory tract and the dynamic pressure according to the present invention.

<Explanation of symbols for the main parts of the drawings>

100: breathing tube 110: cylindrical tube

120: static pressure measuring tube 130: sensing rod

132: sampling hole 150: measurement module

151: static pressure converter 152: dynamic pressure converter

154: electronic circuit 160: PC

The present invention relates to a respiratory tube for a portable respiratory air flow measuring device, and more particularly to a portable respiratory air flow measuring device suitable for electronic respiratory air flow measuring device for use in self-examination for chronic respiratory diseases such as asthma. will be.

Measurement of respiratory airflow is essential when performing all respiratory function tests such as spirometry. The measurement of respiratory airflow is a kind of clinical test for analyzing the volume change signal of the lungs caused by human breathing and analyzing it.

Currently, the most widely used respiratory flow measurement methods are pneumotachography and tubinometry, which convert respiratory flows into measurable physical variables on the respiratory path. Sensor element shall be located. For example, the pneumotach type respiratory air flow measurement method is configured to measure a respiratory air flow by installing a fluid resistor in the center of a respiratory tube forming a respiration path, and measuring a static pressure difference obtained from both sides of the fluid resistor. .

In the New Mothak type respiratory air flow measurement device, a fluid resistor is placed on the respiratory path of the subject, thereby interfering with the subject's respiration, thereby causing a decrease in test reliability by changing a flow rate signal representing the subject's respiratory function. In addition, the structure of the fluid resistor located in the breathing path is very complicated, the manufacturing cost is high, it is impossible to manufacture a breathing tube attached to the fluid resistor is disposable. Therefore, when a large number of subjects perform the respiratory function test, there was a problem such as a possibility of infection between the subjects.

In order to overcome the drawbacks of the New Mothak type respiratory air flow measurement device, a respiratory air flow measurement device has been developed to measure respiratory air flow by measuring dynamic pressure instead of static pressure measurement.

1 is a view for showing the principle of respiratory air flow measurement using the dynamic pressure.

As shown in Figure 1, the respiratory tube (1) for measuring the respiratory air flow using the dynamic pressure forms a pitot tube (2, 2 ') in the center of the respiratory tube (1) symmetrically, at the time of arc and suction The differential pressure is measured at. The respiratory tract for measuring respiratory airflow using dynamic pressure is based on Bernoulli's law that the sum of the kinetic energy and potential energy held by the airflow is preserved when the respiratory airflow flows through the pipe. That is, when measuring the respiratory air flow using the dynamic pressure, the bi-directional air flow rate (u) is expressed by <Equation 1> as follows.

u≡u L- u R ∝ ±

(1)= S

(One)

Where S: proportionality constant, PD: dynamic pressure (PL-PR), u: airflow velocity, u L: evaporator flow velocity, u R: intake airflow velocity

)이 비례하며, 비례상수(S)가 하나만 존재함을 나타낸다. 따라서, 동압력을 이용한 호흡 기류 계측 시스템은 상술한 뉴모탁 방식의 호흡 기류 계측 장치에 비해 유체 저항체에 의한 호흡 방해 및 복잡한 유체 저항체 구조와 같은 문제점을 해결할 수 있다.Since the pitot tube (2) is symmetrical when measuring the respiratory air flow using dynamic pressure in Equation (1), the potential energy components cancel each other, and the differential pressure (PL-PR) by the arc and air flows reflects the dynamic pressure (PD). . Equation (1) is the square root of respiratory airflow and dynamic pressure (

) Is proportional, and there is only one proportional constant (S). Accordingly, the respiratory air flow measurement system using dynamic pressure can solve problems such as respiratory obstruction by a fluid resistor and a complicated fluid resistor structure, compared to the above-described Pneumotax type respiratory air flow measurement apparatus.

Korean Patent No. 432640 filed by the present applicant discloses a respiratory air flow measurement device using such dynamic pressure. Korean Patent 432640 is composed of a sensing rod 240 is detachably inserted into the paper-shaped cylindrical tube 220 as shown in Figures 2 and 3. The cylindrical tube 220 includes an inlet 222 and an outlet 224 opposite thereto, and the inlet 222 is equipped with a screen cap 260 having a mesh shape to stabilize the streamline of breathing air. do. The sensing rod 240 mounted in the cylindrical tube 220 and sampling the respiratory flow rate and converting the respiratory flow rate into the dynamic pressure is vertically connected to the plurality of sampling holes 244 to communicate with two air distribution pipes 242 to the differential pressure sensor in the measurement module. It consists of.

Respiratory airflow measurement device filed by the applicant has a sensing hole 240 has a sampling hole by the equal area division method to increase the accuracy of respiratory airflow measurement while reducing the manufacturing cost, by providing a disposable breathing tube made of paper Many subjects completely eliminate the problem of infection when measuring respiratory airflow.

On the other hand, self-management of chronic respiratory diseases is essential, as the trend of chronic respiratory diseases is rapidly increasing due to environmental pollution and industrialization. That is, in the case of asthma, a typical respiratory disease, the airways become narrow and cause respiratory distress and death due to asthma attacks.

A typical self-care practice for chronic respiratory disease uses a method to measure peak expiratory flow rate (PEF) twice a day. Since only bays are measured, self-management of chronic respiratory disease is limited. For practical self-management of chronic respiratory illnesses, parameters of lung capacity test such as forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV 1.0) are important. Electronic spirometry is essential because waveforms must be accumulated.

However, since the conventional respiratory flow measuring device such as clinical spirometer is manufactured for clinical use, it is expensive and large in size so that it is practically impossible to carry out the respiratory flow easily while carrying a chronic respiratory disease. The biggest difficulty in making the electronic spirometer small and portable is the miniaturization of the sensor element for respiratory airflow measurement that converts biometric variables that cannot be directly measured into measurable physical variables.

In the case of the conventional pneumotachography, a fluid resistance composed of a mesh screen, a capillary tube, or the like has to be inserted into the respiration path (breathing tube). Impossible, because the turbine-type instrument (tubinometry) also needs to be equipped with a turbine that rotates on the respiratory path (breathing tube), there was a problem that miniaturization is impossible.

The present invention has been invented to solve the above problems, and by minimizing the diameter and length of the respiratory tract while preventing the respiratory interference effect in the respiratory tract, a compact one-way suitable for measuring the respiratory air flow easily while carrying a chronic respiratory disease The purpose is to provide a breathing tube for airflow measurement.

The present invention for achieving such an object,

A cylindrical tube made of a one-time paper or plastic material and including an inlet contacting the mouth of the subject and an outlet opposite thereto; And

It is formed so as to extend outwardly through the cylindrical tube from the upper side to the outlet of the cylindrical tube, the upper portion is closed and the lower portion is formed into an open tubular shape, to measure the air flow from the respiratory path of the cylindrical tube to the inlet side of the cylindrical tube. A plurality of sampling holes for includes a sensing rod formed in the longitudinal direction.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

4 is a cross-sectional view illustrating a structure of a small unidirectional air flow measurement respirator according to the present invention. 5 is a block diagram of a test apparatus for dynamic pressure measurement and static pressure measurement for determining the size of the respiratory tract of FIG. 4.

Referring to Figure 4, the respiratory tube 100 according to the present invention is composed of a one-time paper or plastic material, the cylindrical tube 110 having an inlet 112 and the outlet 113 opposed to the mouth of the subject contacted with And a sensing rod 130 formed near the outlet side of the cylindrical tube 110 and composed of a thin rod-shaped tube having an inner diameter of 1 mm.

The sensing rod 130 is formed to be within 5 mm from the outlet side of the cylindrical tube 110 and has a thin rod-shaped having an inner diameter of 1 mm extending through the cylindrical tube 110 from the top of the cylindrical tube 110 to the lower outer side. It consists of a circular tube. The top of the sensing rod 130 is closed and the bottom is open. On one side of the sensing rod 130 formed inside the cylindrical tube 110, that is, the inlet side of the cylindrical tube 110, a plurality of sampling holes 132 for measuring the flow rate are formed at regular intervals in the longitudinal direction. .

Here, the cylindrical tube 100 of the respiratory tube according to the present invention has a length of 35 mm, has a diameter of 15 mm, and has a thin rod having an inner diameter of 1 mm inside the cylindrical tube 110 which is a respiratory path of the respiratory tube 100. Since only the sensing rod 130 is a circular tube of the fluid resistance is almost absent, three sampling holes 132 formed on one side (inlet side of the cylindrical tube) of the sensing rod 130 has a central axis, the center of the air flow It is formed on each axis of ± 2.5mm and consists of a total of three.

Here, the length of the cylindrical tube 110 constituting the breathing tube 100 is easy for the subject to hold the cylindrical tube 110 in the mouth and breathing, the sensing rod for measuring the flow rate inside the cylindrical tube 110 ( 130 mm is set to the minimum length to be inserted. When the length of the cylindrical tube 110 is set, the diameter of the cylindrical tube 110 and the formation position of the sensing rod 130 should be determined according to the set length, and the diameter of the respiratory tube 100 according to the present invention is the US chest. It is designed to meet the standards of the American Thoracic Society (ATS).

The American Thoracic Society recommends that the maximum fluid resistance of clinical spirometers be 1.5 cmH2O / ℓ / sec, and that the maximum fluid resistance of self-diagnosed spirometers is 2.5 cmH2O / ℓ / sec. ) Is recommended to be 14 L / sec.

The fluid resistance of the breathing tube can be calculated by measuring the static pressure (Ps) of the fluid flowing in the breathing tube, the static pressure (Ps) is the fluid resistance (R) and respiratory air flow (F) as shown in It is expressed by the product of.

=R ˙ F (2)

= R ˙ F (2)

Multiplying the maximum value of fluid resistance (R) and respiratory flow (F) recommended by the American Thoracic Society according to <Equation 2> yields an allowable static pressure (Ps) value of the respiratory tract. The allowable positive pressure (Ps) of the respiratory tract is 21 cmH2O for clinical spirometers and 35cmH2O for self-diagnostic spirometers.

In order to measure the positive pressure Ps of the respiratory tube 100 according to the present invention, as shown in FIG. 5, the lower portion of the cylindrical tube 110 communicates with the lower portion of the cylindrical tube 110 at a point 5 mm from the inlet 112 side of the cylindrical tube 110. While being mounted vertically with respect to the cylindrical tube 110 to form a static pressure measuring tube 120 which is a rod-shaped circular tube having an inner diameter of 1mm for measuring the static pressure Ps of the respiratory airflow flowing through the cylindrical tube 100. .

Test apparatus for determining the specification of the respiratory tube 100 according to the present invention, as shown in Figure 5, the respiratory tube 100 separately formed a static pressure measuring tube 120 at a 5mm point at the inlet side for the test It is composed of a measurement module 150 connected to.

The measuring module 150 is connected to the positive pressure measuring tube 120 separately mounted on the breathing tube 100 therein, and is configured to convert the positive pressure representing the potential energy of the respiratory airflow into an electric signal. And a dynamic pressure converting unit 152 connected to the sensing rod 130 of the respiratory tube 100 according to the present invention for converting dynamic pressure in the respiratory air stream obtained from the sensing rod 130 into an electrical signal. The positive pressure converting unit 151 and the dynamic pressure converting unit 152 are constituted by a general pressure sensor.

The electrical signals output from the constant pressure converter 151 and the dynamic pressure converter 152 are amplified according to a conventional method, the noise is filtered (LPF), and inspected through the electronic circuit 154 for A / D conversion. After being processed into a suitable signal to the computer is transmitted to the computer 160 through the interface connection line 155 installed in the lower portion of the measurement module 150 to perform a test.

6 is a graph showing a correlation between the diameter of the respiratory tube and the maximum respiratory airflow value obtained through the experimental apparatus of FIG. 5, and FIG. 7 is a graph illustrating the correlation between the diameter of the respiratory tube and the dynamic pressure according to the present invention. It is a graph.

The relationship between the static pressure (Ps) and the maximum respiratory air flow value (F) according to the diameter (D) of the breathing tube 100 by the test apparatus of FIG. 5 was measured, and the maximum static pressure (Ps) recommended by the American Thoracic Society ) Is substituted into <Equation 2> to calculate the maximum measurable respiratory air flow value Fmax according to the diameter D of the respiratory tract. According to Equation 2, the positive pressure (Ps) value of the respiratory tract (21 cmH2O in the clinical spirometer and 35 cmH2O in the self-diagnostic spirometer) can be measured according to the diameter (D) of the respiratory tract 100 according to <Equation 2> The result of calculating the maximum respiratory airflow value Fmax is shown in FIG. 6. FIG. 6 shows the maximum respiratory air flow value (Fmax) showing the maximum fluid resistance (R) allowed by the American Thoracic Society (ATS) by diameter when the diameter of the respiratory tract is set.

 Since the maximum measurement range of the air flow prescribed by the American Thoracic Society (ATS) is 0 to 14 L / sec (maximum respiratory air flow value (Fmax) is 14 L / sec or less), the maximum respiratory air flow value is determined by interpolation in FIG. 6. Calculating the D value at which (Fmax) is 14 L / sec yields 14.7 mm for clinical spirometry and 12.8 mm for self-diagnostic spirometry.

These are the minimum diameter of the respiratory tract meeting the standard of the American Thoracic Society (ATS), and the minimum diameter difference between the clinical spirometer and the self-diagnostic spirometer is only 1.91 mm, so the minimum allowable diameter of the respiratory tract is set to 15 mm in the present invention. It is.

In conclusion, the length of the respiratory tract according to the present invention is set to 35 mm in consideration of the measurement convenience and insertion of the sensing rod, and the minimum diameter is 15 mm in consideration of the standard of the American Thoracic Society (ATS) according to this length. Is set to. That is, when the length of the respiratory tube is 35mm, the minimum diameter that satisfies the standard of the American Thoracic Society (ATS) becomes 15mm and the volume is about 6.2 cm 3, so the respiratory tube according to the present invention is mounted on a portable device. It will be as large as possible.

)값으로 변환된다. 여기서, 본 발명에 따른 호흡관(100)의 감지로드(130)는 원통형 관(110)의 출구(113)로부터 5mm 범위내에 위치시킨다. 호흡관(100)의 압력측정은 대기압을 기준으로 하는 상대적인 압력으로 이루어지므로 감지로드(130)의 위치가 외부대기에 근접하게 되면 호흡기류의 위치에너지 성분은 외부 대기와 같아지므로, 위치에너지 성분을 상쇄할 필요가 없으므로 호흡관(100)의 감지로드(130)에서는 동압력(

)값만이 검출된다. 즉, 도 1에서 보는 바와 같이 2개의 피토관을 사용하여 차압을 측정하여 위치에너지 성분을 상쇄할 필요없이 하나의 관만을 사용하여 단순한 구조로 저렴하게 제작할 수 있다.In addition, the respiratory tube 100 according to the present invention, the respiratory airflow detected through the three sampling holes 132 of the sensing rod 130 located on the breathing path is mounted on the lower end of the sensing rod 130 of FIG. 5. In a pressure sensor such as the dynamic pressure converting unit 152, the dynamic pressure (

Is converted to). Here, the sensing rod 130 of the respiratory tube 100 according to the present invention is positioned within the range of 5 mm from the outlet 113 of the cylindrical tube 110. Since the pressure measurement of the respiratory tube 100 is made of a relative pressure based on the atmospheric pressure, when the position of the sensing rod 130 is close to the external atmosphere, the potential energy component of the respiratory airflow becomes the same as the external atmosphere. Since there is no need to cancel, the sensing rod 130 of the respiratory tube 100 has a dynamic pressure (

) Value is detected only. That is, as shown in FIG. 1, two pitot tubes are used to measure the differential pressure, and thus, a single structure may be inexpensively manufactured using only one tube without offsetting potential energy components.

)값에 관련한 <식 1>을 변환하면 <식 3>과 같이 동압력(

)은 기류속도(u)의 제곱에 비례하고, 연속성의 원리에 의하여 <식 4>와 같이 호흡기류 F는 기류속도(u)에 호흡관의 면적(A)을 곱하여 산출되며, 관의 단면적은 <식 5>와 같이 표현되므로, <식 3, 식 4, 식 5>를 연립하여 동압력(

)을 산출하면 <식 6>이 산출된다.Dynamic pressure

) If you convert <Equation 1> with respect to the value, the dynamic pressure (

) Is proportional to the square of the air flow rate (u), and according to the principle of continuity, the respiratory air flow F is calculated by multiplying the air flow rate (u) by the area (A) of the respiratory tract as shown in <Equation 4>. Since it is expressed as <Equation 5>, <Equation 3, Equation 4, Equation 5> are combined to provide dynamic

) Is calculated.

= S ˙u2 (3)

= S ˙u2 (3)

(4)

(4)

(5)

(5)

=

16SF2/π2 . 1/D4

∝ 1/D4 (6)

=

16SF2 / π2. 1 / D4

∝ 1 / D4 (6)

: 동압력 , u : 기류속도, D : 관의 직경)(Where A is the cross-sectional area of the respiratory tract, S is the proportional constant,

: Dynamic pressure, u: air velocity, D: diameter of pipe)

)과 1/D4 간에는 서로 비례하는 관계가 있으므로, 실제 동압력(

)을 측정한 결과 도 7에서 편의상 관의 직경(D)의 단위를 10-1cm로 변환하였을 때 직선의 선형회귀식을 나타내었다.In <Equation 6> dynamic pressure (

) And 1 / D4 are proportional to each other, so the actual dynamic pressure (

7 shows the linear regression equation of the straight line when the diameter (D) of the tube is converted to 10-1 cm for convenience.

As shown in FIG. 6, the maximum dynamic pressure of about 75 cmH 2 O could be calculated when the diameter of the respiratory tube 100 according to the present invention was 15 mm and the length was 35 mm (1 / D4 = 1975). This means that the maximum static pressure of the most widely used pneumatic method is 10 cmH2O, which means that the sensitivity is more than 7 times higher.

The breathing tube 100 according to the present invention simplifies the structure of the sensing rod 130 for converting the respiratory air velocity into dynamic pressure for miniaturization to measure only one-way direction, not bidirectional airflow. The most important and widely used Forced Pulmonary Leak (FVC) test among the diagnostic spirometry test is to analyze the eosinophilic signal obtained when the subject breathes with the utmost effort, and calculate various clinical diagnostic parameter values. This is a test to obtain the mechanical characteristics of the respiratory apparatus based on the expiratory flow limitation phenomenon that the airway narrows according to the esophageal effort. Most diagnostic variables are obtained from the esophagus airflow signal.

 In particular, self-management of chronic respiratory illnesses requires less than five parameter values that can be obtained from eosinophilic signals, so no intake airflow needs to be measured. Therefore, in the breathing tube 100 for the respiratory air flow measuring device according to the present invention, the breathing air flow detected through the three sampling holes 132 formed in the front part (inlet side of the cylindrical tube 110) while penetrating the breathing path. To measure. The measured arc airflow is converted into an electric signal representing the dynamic pressure value by the dynamic pressure converting unit 152 which is a normal pressure sensor.

Since the sensing rod 130 is a rod-shaped tube having a thin thickness, there is almost no fluid resistance, and when the diameter of the respiratory tube 100 is narrowed, as shown in <Equation 6>, the dynamic pressure increases, so that the respiratory tube (for As 100) becomes smaller, a relatively high dynamic pressure is obtained. This means that the sensitivity is improved, and as the size of the respiratory tube 100 is reduced, measurement sensitivity is rather increased, which makes it possible to manufacture a respiratory air flow measurement device even with a small-sized, low pressure sensor.

Since the fluid resistance that interferes with the breathing of the subject increases as the diameter of the breathing tube 100 becomes smaller, it becomes a constraint on the miniaturization of the breathing tube 100. On the breathing path of the breathing tube 100 according to the present invention, The sensing rod 130 for positioning and measuring dynamic pressure is only a thin rod-shaped circular tube having an inner diameter of 1 mm, so that there is almost no fluid resistance.

Therefore, the respiratory tube 100 according to the present invention sets the length of the functional disposable respiratory tube to 35 mm in a range without any problems in practicality so as to be suitable for the portable respiratory air flow measurement device for chronic respiratory disease patients, The static pressure (Ps) measurement results reflecting the fluid resistance from the hydrostatic pressure measuring tube 120 is analyzed by the diameter of the respiratory tube so that the diameter of the respiratory tube 100 is at least 15 mm or more.

As described above, the respiratory tube for portable respiratory air flow measuring device according to the present invention is most suitable for miniaturization of the portable respiratory air flow measuring device for self-management of chronic respiratory diseases such as asthma among the recently activated portable medical devices, and clinical Compared to the respiratory tract of other widely used respiratory air flow measuring instruments, the remarkably improved sensitivity, cost reduction, and one-time use of materials make it possible to avoid the risk of infection among multiple examiners.

Although the preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, the present invention is not limited thereto and may be improved or modified by those skilled in the art within the scope of the technical idea of the present invention.

Claims (4)

A cylindrical tube 110 made of a one-time paper or plastic material and including an inlet 112 contacting the mouth of the subject and an outlet 113 opposite thereto; And It is formed so as to extend through the cylindrical tube 110 from the top to the outside of the bottom close to the outlet of the cylindrical tube 123, the upper portion is closed and the lower portion is formed in an open tubular shape of the cylindrical tube 110 Small unidirectional air flow measurement breathing comprising a plurality of sampling holes 132 for measuring the air flow to the inlet 112 side of the cylindrical pipe 110 on the respiratory path spaced apart at regular intervals, the sensing rod 130 formed in the longitudinal direction tube. delete delete delete

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