RESIDUAL LUNG VOLUME DETERMINATIONS BY THE METHODS OF HELIUM SUBSTITUTION AND VOLUME EXPANSION

Abstract

Findings are presented on the detn. of residual lung volume by 2 new methods: a) substitution of helium for the N2 of lung air with subsequent washing out and measurement of He contained in the residual lung volume, and b) measurement of gas volume resulting from physical expansion of residual lung volume occurring during rapid reduction of barometric pressure from 4 to 1 atmospheres. While, in general, greater accuracy may be attained by employing the 1st method, the 2d is conducive to speed when large numbers of detns. are to be made due to its simplicity and the possibility of making multiple detns. at one time. Both methods give results which are in agreement with the frequently employed N2 dilution method described by Van Slyke and Binger.