GB832474A - Resusitator - Google Patents

Abstract

832,474. Respiratory appliances. STANTON, P. L. Oct. 6, 1958 [July 14, 1958], No. 31854/58. Class 81(2). Forced respiration apparatus in which the change-over from inhalation to exhalation is effected by means responsive to the pressure in the lungs, has an auxiliary chamber connected to the patient's supply line to delay the changeover, so as to compensate for the flow resistance of the trachea in children or other small patients. In the control mechanism described, air enters from a tube 7, Fig. 1 (not shown), and passes through an adjustable needle control valve 28 to a chamber 31. From this point its passage is controlled by a doubleheaded valve 32, 33, actuated through a toggle linkage 35 by a piston 36. With the mechanism set as shown in Fig. 3, the gas passes through a conduit 38 to a chamber 39 and thence through a duct 42 to the face mask, until the pressure is sufficient to lift the piston 36. When this occurs, the toggle mechanism changes over and the valve head 32 closes duct 38, while an upper duct 38<SP>1</SP> is opened. This directs the gas to a nozzle 47 and Venturi tube 40<SP>1</SP>, which draws air out of the chamber 39 and face mask, through an orifice 48, and passes it to atmosphere through an outlet 41, until the pressure in chamber 39 has fallen sufficiently for the piston 36 to be drawn back to its lower position. A slight leak always occurs from chamber 39 through the orifice 48 and, in order to reduce this to such a point that the pressure in chamber 39 can build up sufficiently to operate the plunger 36, the orifice is partially closed by a pivoted plate 50 to limit its effective area to a point at which, dependent on the minimum rate of flow through the needle valve 28, the apparatus will still function satisfactorily. According to the invention an expansible container is connected to a further outlet 45 and, serving as a reservoir in parallel with the lungs, slows down the operation of the mechanism and thereby assists complete filling and emptying of the lungs, when the patient has a small or restricted trachea. The control casing carries safety release valves which limit the maximum and minimum pressures in the space 39.