A. C. Young, C. J. Martin, S. Tsunoda
J Clin Invest.
1974;
53(4):1178–1184
doi:10.1172/JCI107656
This article Copyright © 1974, The American Society for Clinical Investigation
Abstract
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L
ung volumes in irreversible diffuse obstructive pulmonary syndromes (DOPSI) have been studied by using an analog of the lung that simulates an 18-breath nitrogen washout. The functional residual capacity (FRC), the dead space volume (Vd), the distribution of ventilation, as well as the pattern of lung emptying have been measured in normal subjects and those with obstructive syndromes. The Vd increased progressively with severity of the obstructive syndrome, as did FRC. For all subjects, both normal and obstructed, the ratio of Vd/FRC remained relatively fixed with the regression line of Vd upon FRC showing a minimal value for Vd of 67 cm3. Vd increased by an average value of 33 cm3 per liter of lung volume above this value. The increase in FRC resulted from the increased volume of the poorly ventilated compartment for the most part. X-ray evidence of emphysema was poorly correlated with the changes in Vd or FRC. A significant increase in anatomical Vd in DOPSI makes up an appreciable portion of the total Vd (physiological).
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