JPH1183851A - Expired gas measuring method by stable isotope and device used for it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply and accurately measure a stable isotope ratio. SOLUTION: In this method, gas expired from a subject before and after a stable isotope is given is gathered in an elastic bag 3 through a mouthpiece respectively, and gas expired yet from the subject after a volume of expired gas equivalent to one half of one time ventilation volume is gathered in the elastic bag 3 is analyzed by a mass analyzing system 5, in order to calculate carbon dioxide isotope ratio of the expired gas before and after the isotope is given. In addition, this device is equipped with an inlet 1 for mounting the mouthpiece, the elastic bag 3 connected to it, the mass analyzing system 5 connected to the elastic bag 3 and a pressure valve 4 which is provided between the elastic bag 3 and the mass analyzing system 5 and can be opened when a pressure in the elastic bag 3 reaches a set value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring stable isotope expiratory gas and an apparatus used for the method, and more particularly, the present invention can collect only phase 3 alveolar air. Therefore, the present invention relates to a stable isotope exhaled gas measurement method capable of accurately measuring a stable isotope ratio and an apparatus used for the method.

[0002]

2. Description of the Related Art Conventionally, a method for measuring the stable isotope ratio of exhaled breath has been to use a stable isotope, ¹³ C, as a label and exhale the exhaled breath into a bag or the like before and after orally administering ¹³ C. in terms of accumulated breath, these expired gas were each analyzed by a gas analyzer, was calculated isotope exhaled gas _{^{(13 CO 2/12 CO 2}} ).

[0003]

In the conventional measuring method,
Before and after oral administration of the stable isotope ¹³ C-label, exhaled breath is exhaled in a bag or the like, and the exhaled gas is stored in the bag, and each of these exhaled gases must be analyzed by a gas analyzer. There was trouble.

[0004] In addition, when exhalation is collected in a bag, the air itself is exhaled at the initial stage of exhalation, not the alveoli that have undergone gas exchange in the alveoli. In measuring the change in body ratio, air and carbon dioxide were mixed, causing an error in the measurement.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. In particular, exhalation after oral administration of a stable isotope, ¹³ C label, without collecting each exhaled breath in a bag. An object of the present invention is to provide a stable isotope exhaled gas measurement method and an apparatus therefor, which can measure alveolar air having only a stable isotope ratio in which air is not mixed, and can accurately measure the isotope ratio without error. And

[0006]

As a result of intensive studies, the present inventor was able to solve the above-mentioned conventional problems.
That is, in the present invention, exhaled gas from a subject before administration of a stable isotope is directly collected in an elastic bag in a closed system through a mouthpiece, and the elastic bag has a capacity of about の of the tidal volume. After the exhaled gas of the subject is collected, the exhaled gas from the subject that is further exhaled is analyzed by a mass spectrometry system, and separately from this, the exhaled gas from the subject to which a stable isotope has been administered is passed through a mouthpiece. After being directly collected in an elastic bag in a closed system, and exhaled gas having a volume of about の of the tidal volume is collected in the elastic bag,
Further, the exhaled gas from the subject to be called is analyzed by a mass spectrometry system, thereby calculating the carbon dioxide isotope ratio of the exhaled gas before and after the administration of the stable isotope. It provides a method.

The present invention also provides a mouthpiece mounting port 1 for mounting a mouthpiece, an elastic bag 3 connected to the mouthpiece mounting port 1, a mass spectrometry system 5 connected to the elastic bag 3, Provided between the elastic bag 3 and the mass spectrometry system 5,
A pressure valve 4 that can be opened when the pressure in the elastic bag reaches a set value.

Further, the present invention provides the above-mentioned stable isotope breath gas measuring apparatus, wherein a flow meter 2 which can recognize the flow rate of the breath of the subject is provided between the mouthpiece mounting opening 1 and the elastic bag 3. Is what you do.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a method for measuring stable isotope expiratory gas and an apparatus therefor according to the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram showing an example of a stable isotope expiratory gas measurement device according to the present invention.

In FIG. 1, what is indicated by reference numeral 1 is
Mouthpiece attachment port, 2 is a flow meter,
3 is an elastic bag, 4 is a pressure valve, 5 is a mass spectrometry system.

As shown in FIG. 1, before the administration of the stable isotope ¹³ C, the subject holds the mouthpiece attached to the mouthpiece attachment port 1 so that the capacity of about half of the tidal volume is stored in the elastic bag 3. When filled, pressure valve 4
Is set to open and called once. The concentration of carbon dioxide at this time is measured by the mass spectrometry system 5. next,
After administration of the stable isotope ¹³ C, the subject held the mouthpiece attached to the mouthpiece attachment port 1
The pressure valve 4 is set to be opened when the elastic bag 3 is filled with a volume of about half of the respiratory volume, and is exhaled once. Only the exhaled gas near the third phase shown in FIG. Is supplied to the mass spectrometry system 5, and the isotope ratio at this time is measured. Thereby, the carbon dioxide isotope ratio of the exhaled gas before and after the administration of the stable isotope is measured.

It is preferable to provide a flow meter 2 between the mouthpiece mounting port 1 and the elastic bag 3 so that the flow rate of the subject's breath can be recognized.

In FIG. 2, the first phase is a phase in which the last air inhaled before exhalation is inhaled only in the oral cavity and trachea, and is exhaled again by exhalation without contributing to gas exchange in the lungs. No change is observed in carbon dioxide gas, and the concentration changes at the same level as air. The second phase is a mixed phase of a gas that has contributed to gas exchange in the lungs and a gas that has not contributed to gas exchange in the oral cavity and trachea. The third phase is a phase in which gas that has contributed to gas exchange in the lungs is exhaled.

[0014]

According to the present invention, the stable isotope ¹³ C
Before and after the oral administration of the label, a collection bag for exhaling breath is not required for each bag, so that the measurement time is shortened, and the isotope ratio of pure alveolar carbon dioxide alone can be accurately measured. .

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a stable isotope exhaled gas measuring apparatus according to one embodiment of the present invention.

FIG. 2 is a characteristic diagram showing an aspect of a carbon dioxide gas concentration change obtained by measurement.

[Explanation of symbols]

 1 mouthpiece attachment port 2 flow meter 3 elastic bag 4 pressure valve 5 mass spectrometry system

Claims (3)

[Claims] 1. Exhaled gas from a subject before administration of a stable isotope is directly collected through a mouthpiece into an elastic bag in a closed system, and the elastic bag is set to 1/1/2 of the tidal volume.
After about 2 volumes of exhaled gas are collected, the exhaled gas from the subject that is further exhaled is analyzed by a mass spectrometry system, and separately from this, the exhaled gas from the subject to which a stable isotope has been administered is After the breathing gas is directly collected into the elastic bag in a closed system through a mouthpiece, and the breathing gas having a volume of about の of the tidal volume is collected in the elastic bag, the breathing gas from the subject is further exhaled. Is analyzed by a mass spectrometry system, thereby calculating the carbon dioxide isotope ratio of the exhaled gas before and after the administration of the stable isotope. 2. A mouthpiece mounting port 1 for mounting a mouthpiece, and said mouthpiece mounting port 1
The elastic bag 3 connected to the elastic bag 3, the mass analysis system 5 connected to the elastic bag 3, and the pressure in the elastic bag provided between the elastic bag 3 and the mass analysis system 5 reach a set value. And a pressure valve 4 that can be opened when opened. 3. The stable isotope breath gas measuring device according to claim 2, wherein a flow meter 2 is provided between the mouthpiece mounting opening 1 and the elastic bag 3 so as to be able to recognize the flow rate of the breath of the subject.