GB623059A - Improvements in or relating to apparatus for the administration of inhalent gas mixtures - Google Patents

Abstract

623,059. Respiratory appliances. MARRETT, H. R. Nov. 6, 1946, Nos. 32964/46 and 14665/47. [Class 81(ii)] Apparatus for the administration of inhalent gas mixture comprises a unitary head in the form of a casing to which are attached a number of flow meters for the supply of basal gases, vaporizers containing volatile liquids such as ether and trichloroethylene or chloroform and a unit such as a soda-lime container for the absorption of carbon dioxide, the casing having also non-return inlet and outlet valves for connection to the expiratory and inspiratory tubes attached to the face mask, a connection for the re-breathing bag and valves for controlling the flow and admixture of gases in the patient's and the basal gas circuits. The apparatus comprises a single head casing 21 within which are housed cylinders 30, 31, 32 having rotary drum valves 10, 11, 12, the drums being ported and divided into chambers. The soda-lime container 5. the ether reservoir 7 and the tricholorethylene container 9 are connected to the casing 21 directly below the drums 10, 11, 12 respectively and are controlled thereby. Figs. 3 and 5 show an embodiment, while Fig. 1 illustrates diagrammatically the circuits of the patient and of the basal gases. In operation, expiratory gases from the face mask pass through conduit 4, past the non-return valve 2, through conduit 13 to the drum 10, thence through the soda-lime container 5 to the re-breathing bag 6 through conduit 14. With the valves in the positions shown in Fig. 1, the return of the patient's gases from the re-breathing bag 6 to the inspiratory conduit 3 pass through the sodalime container 5, along conduit 15 through tubes 17a, 18 in the ether container 7 and past the non-return valve 1. The basal gases from the flow meters 23 pass through conduit 8 through drum 12, conduit 19, valve 11c and through the ether container 7 to join the inspiration of the patient's gases. If it is desired to pass the basal gases through the trichloroethylene container 9 the soda-lime container must be short circuited in view of the reaction of the soda-lime on the gas vapour and to ensure this the drums 10, 12 controlling the respective containers are adapted to be interlocked by some such means as a spring plunger so that the drum controlling one container is in the "off" position when the drum controlling the other is in the " on " position. The appropriate drums may be so set that the gases in the patient's circuit may in part pass through the ether container and in part by-pass it. Similarly, the basal gases may in part pass through either or both of the ether and trichloroethylene chambers and in part by-pass one or both containers.