The close correlations between anatomo-functional data and clinical aspects are substantiated by the study and interpretation of the data of respiratory mechan­ ics. This field has developed to such an extent that, today, it is hard to single out one researcher who is an expert of the whole sector, whereas super experts can be found among scholars who, thanks to their studies and continuous comparisons, have contributed to the widening of knowledge and the development of that part of research which correlates some basic disciplines with clinical medicine. This notion is of paramount importance. Indeed, it has to be regarded as a starting point requiring a more precise definition. The analysis of data concern­ ing ventilation parameters is based on the use of mathematical models that are necessary to simplify the complexity of the various clinical situations. For a cor­ rect application and interpretation of data, the most recent technological acquisi­ tions in terms of ventilatory support require to be used as a function of simple mathematical models for the study, control and evolution of the lung diseases that concern the ICU. Thus, the need has arisen to compare the experience acquired in the field of applied physiology and in the clinical sector.