Patent GB-1429330-A (GB)
Title: Breathing aid apparatus
IPC: A61M16/16
Filed: 1973-03-07
Abstract: 1429330 Valves J-M LAFOURCADE 7 March 1973 [10 March 1972 6 Nov 1972 2 March 1973] 11154/73 Heading F2V [Also in Division A5] Breathing aid apparatus.-Breathing aid apparatus comprises a housing 15 with a hollow end piece 11 for connection to a gas supply 49, an annular valve seat 46 surrounding an end of the end piece bore 12 within the housing 15, a valve member 19 urged by a spring 20 towards a seated position, a first chamber 14 which is charged with gas when the valve member 19 is unseated, an outlet 30 from the first chamber 14 to an outlet 32 of the housing to a patient, a variable volume chamber 17, and a gas duct 21, 22, 27 connecting the first chamber 14 with the variable volume chamber 51 through a throttle, which may be a porous plastics pellet 23 compressed by a screw. The housing outlet includes means for supplying additional gas, comprising a nozzle 39, a rotary valve 41, and a non-return valve 42. The valve member 19 may be a piston. Operation.-Initially, the pressure is atmospheric on both sides of the piston 19. When a gas is admitted to the bore 12 the gas pressure in it compresses the spring 20 and opens the valve so that the gas passes through the passage 30 to the outlet. The gas also seeps slowly through the pellet 23 until the pressure in the chamber 17 rises sufficiently to close the valve and cut off the supply to the patient. Gas pressure in the chamber 14 flows back from chamber 17 to the chamber 14 to relieve pressure in the chamber 14 and restore initial conditions. The cycle then repeats itself. By appropriately choosing the area of the face 47, the force of the spring 20, the porosity of the pellet 23 and the pressure of the gas, the opening and closing times of the valve may be made equal. Exhaled gases escape through the non-return valve 42. Alternative embodiments.-The piston 19 may be replaced by a membrane (55), Fig. 2 (not shown). The nozzle 32 may include a piston (61), Fig. 3 (not shown), biased by a spring (59) and including a bore (62) for connecting the inlet with the outlet. Apertures (57) in the wall of the nozzle 32 lead to the atmosphere. During inhalation, the gas pressure in the passage 14 forces the piston (61) to a position where it occludes the apertures (57). Should the gas supply fail, natural breathing occurs through the apertures (57). In another embodiment, a collar (20), Fig. 5 (not shown), is screwed to a nozzle (111) and encloses therewith, 0-rings (127, 128), Fig. 6 (not shown), which form a valve controlling a bore (130) which extends in a Venturi nozzle (140) and ends in a nozzle (143) at its flared outlet. When the collar (120) is screwed into the nozzle (111), the 0-rings (127, 128) occlude the bore (130) and the device operates as does the device of Fig. 3. When the nozzle (120) is unscrewed, operation is as before during inhalation but during exhalation the 0-rings are spaced apart and gas flow through the bore (130) and the nozzle (143) sets up a depression in a chamber (139) and favours exhalation. Humidifiers.-The gas may be humidified by aliquidina container (163), Fig. 8 (not shown), below the device, connected to it by a hose (161), the liquid being atomized by the gas. Alternatively, a dripping bottle (166), above the device may supply the liquid through a metering valve (167). Control devices.-Devices for controlling the breathing frequency and gas flow rate may be incorporated in the apparatus. The flow rate control device (240), Fig. 10 (not shown), is rotatable using a knob (242), and locks, in one or several positions, by means of a ball-andsocket detent (248-250). In each of these positions, a chamber (217) is connected to a chamber (228) by means of a bore (245) in the device (240) which has several such bores of differing diameter so that the flow rate is different for each said position. The frequency control device (260) is a similar device which has a porous pellet (265), Fig. 14 (not shown), inside a bore (264) which connects a chamber (218) with a chamber (224). Several such bores (264) are provided, each containing a pellet (265) compressed to a different degree by screws (266) so that each bore (264) corresponds to a different breathing frequency. Alternatively, the frequency and flow rates may be continuously altered by means of screws (284), Fig. 15 (not shown), and (283) respectively, which caps a porous pellet in the respective flow passage.