GB519203A - Improvements in anaesthetic apparatus - Google Patents

Abstract

519,203. Valves. BLEASE, J. H., and FOWLER, G. Sept. 17, 1938, No. 27148. [Class 135] [Also in Group VI] An anaesthetic apparatus in which a rotatable valve member progressively closes the passage of air direct to the patient's mask whilst allowing an increased proportion of a gas such as oxygen to vaporize an anaesthetic liquid, is provided with a by-pass whereby, in a final position of the valve, the gas is exclusively led below the surface of the liquid to pass therethrough and then to the mask. The apparatus comprises a casing 1 supporting a bottle 3 for liquid anaesthetic provided with an air &c. admission tube 7. The casing has a web 5 having a perforation 6, Figs. 2 and 5, leading to the tube 7, and perforations 9, 10 which may be closed to the desired degree by a disc valve element 14 having tapered ports and connected by a wing or butterfly valve element 12 to a control knob 11. A connection 16 leads to the mask, a connection 17 is provided for air and a pipe 18, having branches 19, 20, is connected to a supply of oxygen, nitrous oxide &c. The branch 20 communicates with a groove 21, Fig. 3, in the valve body opening into a passage 22 leading to the space between the head of the valve 11 and the disc 14. The branch 19 is placed so that in one position it comes opposite to a port 23 opening into a radial passage, as shown at 24 in the modified construction of Fig. 5, which communicates with a pipe 25 the outlet of which is opposite to the opening 6 when the port 23 is opposite the passage 19. As the knob 11 is turned in a clockwise direction from the position in which air is being drawn by the patient directly from the inlet 17 the ports 9, 10 are gradually opened to cause a portion of the air aspirated through port 10 to pass down into the bottle across the top of the anaesthetic liquid, and then as groove 21 comes opposite pipe 20, oxygen &c. passes from the tube 18 direct to the outlet 16, but some will also pass through the disc valve 14 down the tube 7 and through the anaesthetic. Further movement of the knob 11 will cut off the direct air supply and in the final position the whole of the oxygen will be directed through the port 23, pipe 25 and tube 7 to pass through the anaesthetic. In the modification shown in Fig. 5, the tube 7 is surrounded by a coaxial tube 30 having fins 27.