Detection of ventilation unevenness by nitrogen washout and forced vital capacity manoeuvres: its limits and...

We investigated the behaviour of several indices of ventilation unevenness in a sample of 234 normal subjects aged between 20 and 80 years, divided into 12 classes of 5 years each. The aim of the present study was to find out whether it is possible to predict a reliable value for each of these indices as a function of age, height and TLC. For each index a large dispersion of experimental points and a high unexplained variance was found, so that it does not seem worthwhile predicting its value as a function of age, height and TLC. We concluded that there is no reason to employ these indices to detect the beginning of a lung function impairment.