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Use of the single-breath method of estimating cardiac output during exercise-stress testing.The single-breath cardiac output measurement technique of Kim et al. (1966) has been modified for use in obtaining cardiac output measurements during exercise-stress tests on Apollo astronauts. The modifications involve the use of a respiratory mass spectrometer for data acquisition and a digital computer program for data analysis. The variation of the modified method for triplicate steady-state cardiac output measurements was plus or minus 1 liter/min. The combined physiological and methodological variation seen during a set of three exercise tests on a series of subjects was 1 to 2.5 liter/min. Comparison of the modified method with the direct Fick technique showed that although the single-breath values were consistently low, the scatter of data was small and the correlation between the two methods was high. Possible reasons for the low single-breath cardiac output values are discussed.
Document ID
Document Type
Reprint (Version printed in journal)
Buderer, M. C.
Rummel, J. A.
Sawin, C. F. (NASA Johnson Space Center Environmental Physiology Branch, Houston, Tex., United States)
Mauldin, D. G. (NASA Johnson Space Center Environmental Physiology Branch, Houston, Tex.; Technology, Inc., Dayton, Ohio, United States)
Date Acquired
August 7, 2013
Publication Date
July 1, 1973
Publication Information
Publication: Aerospace Medicine
Volume: 44
Subject Category
Distribution Limits