Methods of and apparatus for measuring the concentration of a gaseous component of exhaled gases.

摘要

In the method and apparatus, a patient breathing through a mask (34) receives breathing air from a breathing air system (A). A xenon gas supply (12) selectively supplies xenon or other enhancement gases into the breathing air. During each exhalation portion of a respiratory cycle, a portion of the exhaled gas passes through a narrow tube (40) to a xenon concentration detector (44) and a carbon dioxide concentration detector (46). A carbon dioxide concentration comparing circuit (54) compares the carbon dioxide concentration values with characteristics (56) of carbon dioxide concentration during a end-tidal portion of the exhalation respiratory cycle. Xenon concentrations read during the end-tidal portion of the respiratory cycle (62) are utilized to project a blood absorption curve (64). In the application of the method and apparatus in a medical diagnostic imaging system including a computed tomography (CT) scanner, a plurality of CT images are generated by the CT scanner (B) as the blood xenon concentration increases. A look-up table array (90) preprogrammed in accordance with the Kety equations is addressed by the blood xenon concentration curve and the pixel values of the CT images to generate partition coefficient and flow values.