GB714150A - Improvements in or relating to apparatus for the control of respiration or anaesthesia - Google Patents

Abstract

714,150. Respiratory appliances. MEDICAL & INDUSTRIAL EQUIPMENT, Ltd. Feb. 4, 1952 [Nov. 4, 1950], No. 26964/50. Class 81(2) Breathing apparatus comprises a breathing bag housed in a pressure chamber associated with a compressed air inlet and means for automatically releasing air from the chamber on attainment of a predetermined pressure therein. A distensible sac 11 supplied with air or gas to be inhaled in known manner is contained within a chamber 10 for compressed air and is connected through a selector valve 12 with flexible piping 13 to the patient's lungs and with flexible piping 24 to a hand-operable breathing bag 23. When the selector valve 12, Figs. 5, 6, 7 (not shown), is set for automatic operation, compressed air is supplied to a Venturi tube 22 within an induction tube of an exhaust valve 15, Figs. 2, 3 and 4 (not shown). The compressed air then passes from the exhaust valve 15 through a pipe 14 to the chamber 10. A cover disc 15a of the exhaust valve 15 is carried by a lever 16 which can move about a pivot 16a and is held so that the exhaust valve 15 is closed by the action of a permanent magnet 19 on a plate 18 on one end of the lever 16, a counterweight 20 being provided at the other end of the lever 16. When the pressure within the chamber 10 has built up to a predetermined maximum with the resultant collapse of the sac 11, the cover disc 15a is lifted so that compressed air entering the apparatus and contained in the chamber 10 is exhausted to the atmosphere. The sac 11 is then able to expand and receive the patient's exhalations which are preferably passed through a carbon dioxide absorption cannister before being inhaled again. In the event of the pressure within the sac 11 becoming too great on receiving exhalations, excess gas from the sac 11 passes into the compressed air supply pipe 14 by way of a duct 28 and a one-way compensating valve 29, Figs. 11 and 17 (not shown). A manometer 30 is connected with the duct 28 to indicate the pressure within the sac 11. A bag 25 is connected with the exhaust valve 15 through a duct 26 provided with an adjustable valve 27, Figs. 8, 9, 10 (not shown), in order to compensate pressure waves set up by manipulation of the patient's lungs and regulate the speed of operation of the apparatus. When the selector valve 12 is set for automatic operation a leakway is provided whereby the hand-operated breathing bag 23 is maintained in inflated :condition. If desired the selector valve 12 may be set to connect the hand-operable bag 23 with the patient's lungs, the sac 11 being disconnected from them.