[Functional differentiation of residual volume changes and problems of evaluation from the physiopathologic viewpoint].

The ascertainment of the residual volume is a very important method for pulmonary emphysema diagnosis. But there are problems of estimation on the basis of this residual volume. The usual relation (RV/TLC) greater than 0,35 as measure for an emphysema will be considered critically. In this way functional relations will be given which allow a more secure emphysema diagnosis. They use as measure comparisons between RV and fit reference volumes, such as normal values of RV, VC or TLC. These equations make it possible to differentiate between structural and functional disturbances.