2009/2010 The thesis describes the study on the characterization of the percussive ventilator; the activities have been carried out in cooperation with the “D.A.I. di Medicina Perioperatoria, Terapia Intensiva ed Emergenza - UCO di Anestesia, Rianimazione e Terapia Antalgica dell'Azienda Mista Universitaria - Ospedaliera di Trieste”. The first chapter describes the physiology of the respiratory system and the classical models presented in literature, the second chapter illustrates the main modes of mechanical ventilation, particularly in the percussive ventilation. The third chapter describes the classical laboratory equipment for the measurement of breathing. The fourth chapter examines the state of the art of methods and instruments for the analysis of respiratory parameters. The fifth chapter discusses the instruments for measuring respiratory parameters, developed in the biomedical laboratory of the DEEI of University of Trieste. The sixth chapter contains a detailed study on the characterization of the percussive ventilator: the model, the method for estimating parameters, the system tests and the results. Particularly, the ability to monitor respiratory parameters by using the instrument developed avoids the volutrauma (alveolar-capillary permeability increase owing to excessive distension of the lung) during controlled ventilation. The instrument also allows to accurately estimate the lung elastance, determining factor of the volume distribution in the used model. At the conclusion of the work, the seventh chapter summarizes the results from the study of the volumes distribution in the two-compartment model of the lung conditioned to percussive ventilation. XXIII Ciclo 1965