The external negative pressure ventilation, by now in use for about a century, has undergone an evolution in the machines designed for that purpose. We have thus passed from ventilating boxes or “iron-lung” (name derived from the metal structure), to ventilators with the use of a “poncho” type cover, called “poncho-wrap” and to those with the use of shell-shaped prostheses, called “cuirass.” The characteristic of this ventilation modality is to create a variation of extrathoracic pressure (negative and positive) which can mobilize the rib cage and, consequently, the internal organs to produce a ventilation similar to the physiological one and, therefore, more natural. The various applicable ventilation modes, the setting to be used in their management, the direct monitoring of the ventilators and of the patients being treated, and the obtainable curves during ventilation and the images in the study of the patient’s ventilation mechanics are here indicated.