Patent GB-983192-A (GB)
Title: Respiratory assister
IPC: A61M16/16
Filed: 1962-05-03
Abstract: 983,192. Artificial respiration apparatus. AIR-SHIELDS Inc. May 3, 1962 [May 4, 1961], No. 17024/62. Heading A5T.  Artificial respiration apparatus comprises a blower 15 for supplying breathing gas to the patient through a conduit under the control of a main valve 17, an exhalation valve 121 controlled by a pressure-responsive device connected by a pressure fluid passage 111 to the conduit so that, when the main valve is open, the exhalation valve is closed, and means to vent the pressure fluid passage to atmosphere when the main valve is closed, so that the exhalation valve is then opened. A control mechanism is provided for opening and closing the main valve in response to the pressure of the gas received by the patient and an aerosol generator 19 is disposed in the patient supply conduit. Air is supplied by the blower through the conduit 34 to the main valve 17 which is controlled by a solenoid 36, and thence through a conduit 37, an adjustable inspiratory flow control valve 44, a check valve 39, an air filter 18 containing a glass fibre filter member 64 and the aerosol generator 19 to an exit passage 102. The exit passage is connected by a hose to a mouthpiece 21 having the exhaust valve 121. A chamber 65 on the downstream side of the filter member is connected to a chamber 164 between upper and lower flexible diaphragms 162, 161 for controlling the main valve. When the patient commences to inspire, the pressure in the filter chamber 65 and the diaphragm chamber 164 falls, so that the lower diaphragm is flexed upwardly to raise a follower 168 and thus actuate a microswitch 172. Actuation of the microswitch 172 closes a switch in a relay circuit (Figs. 7 and 8, not shown) so that the main valve-controlling solenoid is energized to open the main valve. Air from the fan then passes to the patient. As the pressure in the patient's lungs rises, the pressure in the diaphragm chamber 164 rises and flexes the upper diaphragm 162 upwardly to raise a follower which, when a predetermined positive pressure at which inspiration is to terminate is reached, actuates a second microswitch 174. Actuation of the second microswitch opens a second switch in the relay circuit, so that the solenoid is deenergized and the main valve closes the outlet from the fan and connects the conduit 37 with atmosphere through a vent 156. The check valve 39 then closes. At the same time a control chamber in the mouthpiece exhalation valve is vented to atmosphere through a conduit 111 connected with the conduit 37. This enables a diaphragm 22 in the exhalation valve to be raised, against a spring by air flowing to the lungs, sufficiently to expose an exhalation opening 133 to the delivery conduit of the mouthpiece, so that the patient can exhale. The cycle is repeated as soon as the patient makes the next inspiratory effort. Flexure of the upper diaphragm 162 is resisted by a spring 173, the position of which is adjustable to vary the maximum positive pressure necessary to operate the second microswitch. The parts of the apparatus are disposed in a casing 16 having glass-covered sight apertures 69, 78 (Fig. 3), through which the aerosol generator, the filter and a pressure gauge 23 may be observed. The aerosol generator comprises a liquid reservoir 73, in which a disc 86 and depending blades 106 are rotated by a shaft 88 connected with the electric motor 24. Liquid rising up a tapered sleeve 96 passes to the top of the disc through apertures 98 and is thrown against a serrated ring 100, thus forming an aerosol.