Further simplification of a method for determination of residual lung volume

Abstract

On technique for determining residual lung volume, whereby rapid responding oxygen and carbon dioxide analyzers are used to determine the point of nitrogen equilibration, and a five-liter rebreathing bag is substituted for the standard spirometer. This simplified method reduced the total test time to five min or less for duplicate determinations, and eliminated the need for a nitrogen analyzer and a spirometer. This method was found to be both reliable (r = 0.99) and valid (r = 0.92), with a standard error of prediction of 125 ml, and a mean difference of only eight ml, when compared with the established oxygen-dilution technique on a sample of 76 healthy men and women, 19 to 55 years of age. In a subsample of 13 subjects, residual volume was also determined with the nitrogen washout technique, which correlated r=0.89 and r=0.91 with the established and modified oxygen-dilution techniques respectively. The use of assumed values for the initial and final alveolar concentrations of nitrogen did not appear to significantly influence the final results. ©1980The American College of Sports Medicine...