Method of Exhaled Gas Measurement and Analysis and Apparatus Therefor

Abstract

An exhalation collected in a breath bag capable of expanding and contracting is sucked into a gas inlet vessel 21 with a given volume (Va), and then the gas inlet vessel 21 is communicated by means of valve V 2 with a cell 11 that is maintained at an atmospheric pressure by being pre-filled with a sample gas or reference gas. After the communication, the gas pressure is measured by a pressure sensor 16 attached to the cell 11 . Whether the exhalation collected in the breath bag is below a given amount or not can be accurately judged.

1 . A method of exhaled gas measurement and analysis, comprising the steps of:
 (a) collecting an exhalation of a human body including carbon dioxide  13 CO 2  and carbon dioxide  12 CO 2  as component gases into a breath bag capable of expanding and contracting;   (b) sucking a predetermined volume of the exhalation collected in the breath bag into a gas inlet vessel;   (c) measuring a pressure of the exhalation in the gas inlet vessel;   (d) cancelling a measurement upon determining that an amount of the exhalation collected in the breath bag is insufficient when the measured pressure value is below an atmospheric pressure;   (e) pushing the gas inlet vessel to fill a cell communicated with the gas inlet vessel with the exhalation when the measured pressure value is equal to the atmospheric pressure; and   (f) measuring intensities of light transmitted through the cell having wavelengths at which light is transmitted through the respective component gases, followed by data processing based thereon, thereby measuring  13 CO 2  concentration or concentration ratio of carbon dioxide  13 CO 2  to carbon dioxide  12 CO 2 .   
   
   
       2 . The method of exhaled gas measurement and analysis according to  claim 1 , wherein the breath bag has a maximum capacity volume that is equal to or greater than the predetermined volume of the exhalation sucked into the gas inlet vessel. 
   
   
       3 . The method of exhaled gas measurement and analysis according to  claim 1 , wherein in the step (b), after the predetermined amount of the exhalation collected in the breath bag is sucked into the gas inlet vessel, a valve for communication between the gas inlet vessel and the cell is opened so that the gas inlet vessel and an inside of the cell that is maintained at the atmospheric pressure by being pre-filled with a prescribed gas are communicated with each other, and
 in the step (c), the gas pressure after the communication is measured by a pressure sensor attached to the cell.   
   
   
       4 . The method of exhaled gas measurement and analysis according to  claim 3 , wherein the prescribed gas is a reference gas that does not absorb the light having the wavelengths at which light is transmitted through the respective component gases. 
   
   
       5 . The method of exhaled gas measurement and analysis according to  claim 4 , wherein the reference gas is air. 
   
   
       6 . The method of exhaled gas measurement and analysis according to  claim 1 , wherein the exhalation inside the gas inlet vessel is pressurized up to the atmospheric pressure when the amount of the exhalation collected in the breath bag is determined to be insufficient, and
 an amount of change in volume of the gas inlet vessel during the pressurization is shown as an amount of shortage to a measurer.   
   
   
       7 . The method of exhaled gas measurement and analysis according to  claim 3 , wherein the exhalation inside the gas inlet vessel is pressurized up to the atmospheric pressure when the amount of the exhalation collected in the breath bag is determined to be insufficient, and
 an amount of change in volume of the gas inlet vessel during the pressurization is shown as an amount of shortage to a measurer.   
   
   
       8 . The method of exhaled gas measurement and analysis according to  claim 1 , further including the steps of:
 collecting an exhalation of a human body before administration of a sample drug thereto to perform the exhaled gas measurement and analysis including the steps of (b) to (f);   collecting an exhalation of the human body after administration of the sample drug thereto to perform the exhaled gas measurement and analysis including the steps of (b) to (f); and   comparing results of both the measurements thereby to obtain a change in  13 CO 2  concentration or a change in concentration ratio between carbon dioxide  13 CO 2  and carbon dioxide  12 CO 2 .   
   
   
       9 . An apparatus for exhaled gas measurement and analysis for measuring carbon dioxide  13 CO 2  concentration or concentration ratio of carbon dioxide  13 CO 2  to carbon dioxide  12 CO 2  through the steps of introducing a human exhalation including carbon dioxide  13 CO 2  and carbon dioxide  12 CO 2  as component gases into a cell and measuring intensities of light transmitted through the cell having wavelengths at which light is transmitted through the respective component gases, followed by data processing based thereon, the apparatus comprising:
 a gas inlet vessel for injecting into the cell the human exhalation collected in a breath bag capable of expanding and contracting;   a first valve for communicating the breath bag with the gas inlet vessel;   a second valve for communicating the gas inlet vessel with the cell;   a pressure sensor for measuring a pressure inside the cell;   gas inlet vessel driving means for sucking a predetermined volume of the exhalation into the gas inlet vessel;   valve driving means for driving the first valve and the second valve;   pressure measuring means for measuring a pressure of gas inside the cell after communication with the gas inlet vessel by the pressure sensor; and   measuring and analyzing means for performing exhaled gas measurement and analysis in which measurement is cancelled upon determining that an amount of the exhalation collected in the breath bag is insufficient when the pressure measured by the pressure measuring means is below an atmospheric pressure, and the gas inlet vessel is pushed and the cell is filled with the exhalation when the measured pressure is the atmospheric pressure.   
   
   
       10 . The apparatus for exhaled gas measurement and analysis according to  claim 9 , wherein the gas inlet vessel driving means pressurizes the exhalation inside the gas inlet vessel up to the atmospheric pressure upon determining that the amount of the exhalation collected inside the breath bag is insufficient, and
 display means for showing a measurer an amount of volume change during the pressurization as an amount of shortage is further included.