GB1377070A - Lung ventilator - Google Patents

Abstract

1377070 Lung ventilators VERIFLO CORP 14 Dec 1971 [14 Dec 1970] 28004/74 Divided out of 1377069 Heading A5T The disclosure is identical to that in Specification 1,377,069 but the claims relate to a method of operating a lung ventilator and to a volume-cycled pneumatically operable lung ventilator for connection to a supply of breathing gas and which comprises a flow-controller for providing breathing gas during the inspiratory phase of each breathing cycle at a rate dependent on the difference (PC1-PC2), between two pneumatic control pressures PC1 and PC2, a ratio-controller for generating the pressure PC1 at a constant value,- for delivering the pressure PC1 to the flow controller, and for determining the ratio of inspiratory time to expiratory time for each cycle, a time-controller connected to the ratio-controller for determining an inspiratory time for each breathing cycle, the time so determined being adjustable independently of the volume to be delivered, and for generating the control presure PC2 from the pressure PC1 and sending it to the flow-controller, the pressure PC1 being present only during the inspiratory phase and constant during that time, the pressure PC2 being always less than PC1 during the inspiratory phase and increasing during that phase from a minimum to a maximum value, then decreasing during the expiratory phase from the maximum to the minimum value; and a volume-controller interconnected with the time and flow controllers for determining the volume of gas delivered in each inspiratory phase, the volume so determined being adjustable independently of the inspiratory time.