Journal of Applied Physiology, Vol 46, Issue 6 1184-1190, Copyright © 1979 by American Physiological Society
Real-time moment analysis of pulmonary nitrogen washout
J. Saniie, G. M. Saidel and E. H. Chester
A real-time moment analysis was applied to multibreath nitrogen-washout
dynamics of the lung. Because the analysis accounts for breathing pattern
variations, subjects could perform the washout with spontaneous breathing.
The real-time digital processing of the nitrogen and flow signals
incorporates filtering, delay compensation, and corrections for the effects
of gas composition and temperature changes. In our study, moment analysis
of the multibreath washout was evaluated for 37 subjects: 6 normal
nonsmokers, 4 "normal" smokers, 6 asthmatics, 12 with diffuse interstitial
disease, and 9 with chronic obstructive pulmonary disease. Moments were
computed from end-tidal and breath-averaged nitrogen fractions. The ratio
of 1st-to-0th moments was found to yield distinctions among subjects with
different degrees of ventilation inhomogeneity, even between normal
nonsmokers and "normal" smokers. With minimal computational facilities,
this moment analysis not only provides a sensitive index of ventilatory
dysfunction, but also a cost-effective tool.
