the following description made with reference to the attached figures in which fig1 shows a first embodiment of an apparatus according to the invention and fig2 and 3 show variants of the embodiment of the apparatus in fig1 fig4 shows a second embodiment of an apparatus according to the invention and fig1 to 4 illustrate an anesthesia apparatus according to the invention having in common regardless of the embodiment considered the same reference signs and the same terminology will therefore be used to designate identical parts or elements the apparatus or ventilator in fig1 to 4 comprises an inlet unit 1 having connection means to which are connected the source of xenon and the other sources of gases supplying the anesthesia apparatus such as gas bottles or a wall system in particular for the sources of air air oxygen o 2 and or nitrous oxide n 2 o this unit 1 is in fluidic communication with the inlet of a mixer 2 where the xenon is mixed with the other gas or gases intended to form the anesthetic gaseous mixture in particular oxygen in a quantity sufficient for the patient non hypoxic and the outlet of the mixer 2 supplies gaseous mixture to a vessel 14 for halogenated compounds which is mounted on a vessel support 13 and contains a halogenated compound designed to be entrained by the flow of anesthetic gas to the patient 15 the halogenated gaseous mixture leaving the vessel 14 is introduced into a main circuit cp or patient circuit having an inhalation branch 16 for supplying the gaseous mixture to the patient 15 and an exhalation branch 18 for recovering all or some of the gas exhaled charged with co 2 by.