GB1281802A - Improvements in or relating to respirators for artificial ventilation - Google Patents

Abstract

1281802 Artificial respiration apparatus G BEAUMONT 13 Jan 1971 [16 Jan 1970] 1599/ 71 Heading A5T A respirator for artificial ventilation comprises a monostable amplifier 3 and a bistable amplifier 5 in a circuit connecting a source of pressurised fluid 1 and a mouthpiece 16. In operation jets entering the amplifiers 3 and 5 through inlets PS are directed through outlets O. Outlet O of amplifier 3 connects via valve 7 with inlet C3 but provides insufficient pressure to deflect the jet to outlet 1. When the patient aspirates through mouthpiece 16 the presure in a valve 14 is reduced and this is communicated with inlets C4 via a pipe 22. The reduced pressure switches amplifier 3 to outlet 1 which connects to inlet C3 of amplifier 5 thus switching amplifier 5 to outlet 1 which inflates bladder 13 closing expiration orifice 20 and operates a relay 11 allowing a flow of gas to the mouthpiece 16 on insufflation. Flow through a venturi 18 induces atmospheric air. When a predetermined presure is attained in the valve 14 this is communicated by pipe 22 to inlets C4 of the amplifiers to switch the flows through both amplifiers to outlets O hence closing relay 11 and deflating bladder 13 allowing normal expiration. For automatic operation a switch 9 is opened allowing a flow determined by valve 8 which after an expiration pause determined by the time taken to fill a constant volume vessel 10 is filled activates a control inlet C1 to switch the amplifier 5 to outlet 1 thus activating relay 11 and inflating the bladder 13 for insufflation. In the embodiment of Fig. 3 (not shown) amplifier 5 has a vent port (E1) instead of control inlet Cl. Automatic operation is effected by a pneumatic relay (34) Figs. 4 and 5 (not shown). During insufflation no pressure appears at outlet (O) of the amplifier (5) which communicates with chamber (43) of the relay (24) so that a membrane (42) is unseated from an orifice (41) allowing the jet from outlet (O) of amplifier (3) to escape to atmosphere through chamber (40) of relay (34). At the end of insufflation the pressure in duct (22) switches amplifier (5) to outlet (O) deflecting the membrane (42) onto orifice (41) thus diverting the flow from outlet (O) of amplifier (3), which is controlled by the valve (8) into the bladder (36) which when full closes duct (38) which connects to vent port (E1) of amplifier (5) and thus switches the flow. from outlet (O) to outlet (1) to begin another insufflation period. A humidifier (27) may be included in the circuit Fig. 3 (not shown) and the whole apparatus encased Fig. 2 (not shown).