Relationship between Frequency Dependence of Lung Compliance and Distribution of Ventilation

Adam Wanner; Stephen Zarzecki; Neal Atkins; Angel Zapata; Marvin A. Sackner

doi:10.1172/JCI107863

Amendment history:

Correction (March 1975)

Relationship between Frequency Dependence of Lung Compliance and Distribution of Ventilation

Adam Wanner, Stephen Zarzecki, Neal Atkins, Angel Zapata, and Marvin A. Sackner

Published November 1, 1974 - More info

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Abstract

The previously demonstrated empirical association between frequency dependence of lung compliance and distribution of ventilation, the latter determined by the N₂ washout technique, was confirmed by establishing a mathematical link between the two tests. By assuming a two-compartment system with known compliances and making corrections for Pendelluft and common dead space mixing effects, the ratio of dynamic to static compliance (C_dyn/C_st) for any respiratory frequency can be calculated from the compartmental analysis of the N₂ washout at a single respiratory frequency. By using these equations, a good correlation was found between calculated and measured C_dyn/C_st in dogs with artificially induced bronchial obstruction and in young smokers or young nonsmokers after carbachol inhalation. A two-compartment N₂ washout was demonstrated in 10 young healthy smokers at one or two respiratory frequencies whereas all 10 normal controls showed a single exponential curve. These findings indicate that the non-invasive N₂ washout test is capable of predicting C_dyn/C_st and at the same time gives a direct measure of gas distribution. Further, it appears to be a highly sensitive method for the detection of “small airway disease.”