Method and apparatus for determining marker gas concentration in exhaled breath using an internal calibrating gas
First Claim
1. A method for assessing human airway inflammation comprising steps of;
- collecting an orally exhaled human breath sample over an exhalation interval, wherein said orally exhaled human breath sample comprises orally exhaled NO and orally exhaled CO2;
providing a spectrometer including a spectrometer light source, a spectrometer gas sample cell, a spectrometer detector and a spectrometer computer;
placing said orally exhaled human breath sample in said spectrometer gas sample cell;
illuminating said orally exhaled human breath sample with a spectrometer light source;
detecting a transmitted light beam which has passed through said orally exhaled human breath sample with said spectrometer detector to produce a signal sampling;
generating a human breath sample spectrum from said signal sampling;
analyzing said human breath sample spectrum using said spectrometer computer, said step of analyzing including identifying an absorption characteristic of orally exhaled NO and an absorption characteristic of orally exhaled CO2, determining an orally exhaled NO absorption intensity and an orally exhaled CO2 absorption intensity, storing said orally exhaled NO absorption intensity and said orally exhaled CO2 absorption intensity as a function of time over the exhalation interval;
repeating said analyzing and generating to produce a series of gas mixture spectra, each spectrum having an absorption characteristic of the orally exhaled NO and the orally exhaled CO2;
identifying a single signal sampling interval wherein a known concentration CO2 gas absorption which corresponds to an independently known CO2 gas concentration and a simultaneous NO absorption occur;
calculating a ratio of said simultaneous NO absorption intensity to said known concentration CO2 gas absorption intensity and multiplying said ratio by a proportionality constant to obtain concentration of said orally exhaled NO thereby providing an assessment of human airway inflammation.
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Abstract
A method and an apparatus for measuring the concentration of a specific gas component of a gas mixture including another gas whose concentration is independently known using light absorption spectroscopy are provided. A method and an apparatus for assessing human airway inflammation by measuring the concentration of exhaled NO and CO2 present in orally exhaled breath using light absorption spectroscopy are also provided. NO concentration is determined at the time during breath sampling corresponding to a known exhaled CO2 concentration. Methods and apparatus are further provided for measuring NO concentration in orally exhaled human breath that analyze breath emanating from the lower airways and lungs, while excluding breath from the nasal cavity. They include steps and apparatus for discarding initially exhaled breath, flowing breath through an analysis chamber using a vacuum pump and flowing breath through an analysis chamber using a vacuum pump at an initial flow rate and later at a flow rate higher than the initial flow rate.
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Citations
25 Claims
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1. A method for assessing human airway inflammation comprising steps of;
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collecting an orally exhaled human breath sample over an exhalation interval, wherein said orally exhaled human breath sample comprises orally exhaled NO and orally exhaled CO2; providing a spectrometer including a spectrometer light source, a spectrometer gas sample cell, a spectrometer detector and a spectrometer computer; placing said orally exhaled human breath sample in said spectrometer gas sample cell; illuminating said orally exhaled human breath sample with a spectrometer light source; detecting a transmitted light beam which has passed through said orally exhaled human breath sample with said spectrometer detector to produce a signal sampling; generating a human breath sample spectrum from said signal sampling; analyzing said human breath sample spectrum using said spectrometer computer, said step of analyzing including identifying an absorption characteristic of orally exhaled NO and an absorption characteristic of orally exhaled CO2, determining an orally exhaled NO absorption intensity and an orally exhaled CO2 absorption intensity, storing said orally exhaled NO absorption intensity and said orally exhaled CO2 absorption intensity as a function of time over the exhalation interval; repeating said analyzing and generating to produce a series of gas mixture spectra, each spectrum having an absorption characteristic of the orally exhaled NO and the orally exhaled CO2; identifying a single signal sampling interval wherein a known concentration CO2 gas absorption which corresponds to an independently known CO2 gas concentration and a simultaneous NO absorption occur; calculating a ratio of said simultaneous NO absorption intensity to said known concentration CO2 gas absorption intensity and multiplying said ratio by a proportionality constant to obtain concentration of said orally exhaled NO thereby providing an assessment of human airway inflammation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. An apparatus for assessing human airway inflammation comprising;
- a spectrometer gas sample cell adapted to receive an orally exhaled human breath sample containing exhaled NO and exhaled CO2, a spectrometer light source for illuminating said orally exhaled human breath sample, a spectrometer detector for detecting light transmitted through said orally exhaled human breath sample to generate a signal sampling characteristic of the orally exhaled human breath sample, and a spectrometer computer wherein said spectrometer computer further includes an executable program for analyzing a human breath sample spectra generated from the signal sampling by identifying an exhaled NO absorption and an exhaled CO2 absorption, determining an exhaled NO absorption intensity and an exhaled CO2 absorption intensity, storing said exhaled NO absorption intensity and said exhaled CO2 absorption intensity as a function of time, generating a series of human breath sample spectra, each spectrum having an absorption characteristic of the exhaled NO and the exhaled CO2, and to identify a single signal sampling interval wherein a known concentration CO2 gas absorption which corresponds to an independently known CO2 gas concentration variable within an acceptable range and a simultaneous NO absorption occur;
calculating a ratio of said simultaneous NO absorption intensity to said known concentration CO2 gas absorption intensity and multiplying said ratio by a proportionality constant to obtain concentration of said exhaled NO thereby providing an assessment of human airway inflammation. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25)
- a spectrometer gas sample cell adapted to receive an orally exhaled human breath sample containing exhaled NO and exhaled CO2, a spectrometer light source for illuminating said orally exhaled human breath sample, a spectrometer detector for detecting light transmitted through said orally exhaled human breath sample to generate a signal sampling characteristic of the orally exhaled human breath sample, and a spectrometer computer wherein said spectrometer computer further includes an executable program for analyzing a human breath sample spectra generated from the signal sampling by identifying an exhaled NO absorption and an exhaled CO2 absorption, determining an exhaled NO absorption intensity and an exhaled CO2 absorption intensity, storing said exhaled NO absorption intensity and said exhaled CO2 absorption intensity as a function of time, generating a series of human breath sample spectra, each spectrum having an absorption characteristic of the exhaled NO and the exhaled CO2, and to identify a single signal sampling interval wherein a known concentration CO2 gas absorption which corresponds to an independently known CO2 gas concentration variable within an acceptable range and a simultaneous NO absorption occur;
Specification