[The visco-elastic behavior of the respiratory system during mechanical ventilation. Interpretation with the aid of a model].

The purpose of this review is to present an approach to the visco-elastic properties of the respiratory system in the mechanically ventilated patient through the method of occlusion of the airways at a constant inspiratory flow rate. The ideas of airways resistance, tissue resistance, static and dynamic elastance are defined from the theoretical point of view and also from the point of view of the occlusion method. A large part is given to the bicompartmental model describing the visco-elastic properties of the lung and of the thoracic wall. Recently carried out experimental studies both in healthy man and in disease have given results which seem to confirm the predictions made by this model. According to this system the lungs may be represented as a homogenous whole surrounded by visco-elastic components.