Patent GB-391176-A (GB)
Title: Improvements in and relating to apparatus for the use or administration of gaseous anaesthetic substances for the production of unconsciousness
IPC: A61M16/10
Filed: 1931-10-16
Abstract: 391,176. Anµsthetic appliances. PRIMROSE, W. B., 10, Park Quadrant, Glasgow. Oct. 16, 1931, Nos. 28759/31 and 17515/32. [Class 81 (ii).] Anaesthetics are introduced directly into the throat of a patient by a flexible metal or other tube 2, Fig. 1, covered with rubber 3 the end of which is folded back and sealed, or otherwise formed into a capsule B adapted when inflated through a tube 4, as by a hand operated bulb, to obturate and retain the tube in the throat. Alternatively the capsule B may be normally expanded and may be pneumatically collapsed during insertion in the throat. The tube is formed with a tip 5, over which passes a retaining stirrup 8 for the rubber covering 3, and with a connection C to the anaesthetic apparatus. In modifications the tube is formed with a central partition providing inlet and outlet passages, or is branched ; mechanical expanding means for the end of the tube or a member mounted thereon may replace the inflatable means shown. The tube is employed with a rubber or other mask 15, Fig. 9, having a metal sleeve 17 provided with tubular rubber packing 18, and a nose clip 19. The tube is inserted through the mask and through a mouthpiece E, Fig. 10, having a flange 20 and a rubbercovered portion 21 to be gripped by the teeth, the mouthpiece being then inserted into the sleeve 17, and the tube lying in the patient's mouth. When anaesthesia occurs the tube is pressed forward into the throat, and the mask and mouthpiece withdrawn along the tube. Alternatively the mask and mouthpiece may be constructed to be assembled around, and completely removed from, the tube. The anµsthetic apparatus is of the closed-circuit type and comprises a header 26, Fig. 12, con. nected by passages G, H, controlled by slide valves K, M, and flap-valves 33, 34, with inhaling and exhaling tubes 36, 37 which are connected to the throat tube by a Y-piece containing a cock providing direct connection of the tube with the atmosphere when required. Oxygen is supplied through a tube 27, a sightfeed apparatus J, and tube 28, and anaesthetic gas through a tube 29. A connection 30 is made to a breathing-bag which may be spring- or weight-loaded to maintain the whole apparatus under any desired pressure. The header 26 also communicates with a gauge and relief valve. A chamber 31 surrounding the passage G contains liquid anµsthetic and may also contain a wick 40 to promote evaporation. With the valve K as shown the inhaled gases pass through the chamber 31 by ports 6 ; when pressed forward the valve K closes the forward port 6 and opens a port 25 permitting direct flow of the gases. The exhaled gases pass through the valve 34 and, according as the valve M is in a forward, or a rearward position as shown, pass directly through the passage H, or first through a chamber N for absorbing carbon dioxide. An apertured tube 38 in the chamber N is fitted as shown, or in inverted position according as solid or liquid absorbent is employed. In a modification the chamber 31 may be replaced by a chamber similar to and mounted beside the chamber N. The exhaling tube may be fitted with a trap for saliva &c. and both inhaling and exhaling tubes may contain chambers containing medicinal substances or chemicals for reaction with or absorption of or analysis of the respired gases.