CIRCULATING INHALATION ANESTHESIA APPARATUS

PROBLEM TO BE SOLVED: To prevent change in the concentrations of gas when an anesthetizing system is switched between manual and automatic operations and to prevent crush or excessive inflation of a manual bag at the time of manual operation. SOLUTION: The inside of a reservoir bellows 13 is connected to a circulating path 8 of the anesthetizing circuit and the space 12b around the reservoir bellows 13 is connected to a manual bag 20 and an artificial respirator through a driving gas port 14 and an automatic/manual switching valve 19. An exhaust port 16 oriented upward is placed inside the reservoir bellows 13 and is connected to the driving gas port 14, an overflow valve 15 is comprised of a diaphragm valve formed of a back pressure chamber 18 connected to the driving gas port 14 and a pressure adjusting valve 21 is placed on the manual side. When the manual bag 20 is compressed and released, the bellows 13 expands and contracts and alternately performs supply of inner gas as inspiration and inflow of expiration in such a way that the nature and concentrations of the gas do not change regardless of switching of the automatic/ manual switching valve 19. At the time of expiration when the bag 20 expands and the bellows 13 extends, the overflow valve 15 is opened by the difference of pressure and the gas flows into the bag 20 for preventing its crush. When the bag 20 is excessively inflated, the gas is allowed to escape through the pressure adjusting valve 21 at the time of compression.