Residual Volume Measurements by the Gas Expansion Method and Nitrogen Dilution Method

Abstract

The residual lung volume of 5 subjects was detd. repeatedly by (1) a N2 dilution method and, (2) a gas expansion method. The latter procedure involved a rapid decompression of subjects from 1.5, 1.75, or 2 atmospheres to 1 atmosphere and calculating the residual volume from the lung volume increment which could be collected in a spirometer. When the results by these 2 methods are compared, no systematic differences can be established. The various factors which may contribute to the errors of the expansion technic are discussed.