Fail-safe breathing circuit and valve assembly for use therewith

Claim 1

In a breathing circuit for use in supplying gas under pressure to the airway of a patient, a first valve assembly comprising a body having a chamber therein, said body being formed to provide first, second and third flow passages in communication with said chamber, a one-way check valve mounted in said first passage and permitting gas to flow only into said chamber, and a one-way check valve mounted in said third passage and permitting gas to flow only out of said chamber, a second valve assembly comprising a body, a diaphragm assembly disposed in the body of said second valve assembly and forming first and second chambers within the body of the second valve assembly on opposite sides of the diaphragm assembly, said body of said second valve assembly being formed with first and second passages in communication with said first chamber and a third passage in communication with said second chamber, said diaphragm assembly being movable to occlude said first passage in said body of said second valve assembly, said diaphragm assembly carrying one-way valve means permitting gas to flow only from said second chamber to said first chamber, said body of said second valve assembly carrying one-way valve means permitting gas outside of the body of the second valve assembly to flow into said second chamber, a compression bulb coupled to said third passage of said second valve assembly, an exhalation valve assembly comprising a body, said body of said exhalation valve assembly having first and second flow passages formed therein in communication with each other, said second passage being open to ambient, a valve member mounted in said body of the exhalation valve assembly, means in the body of the exhalation valve assembly for yieldably urging the valve member into a position to occlude said first passage, means coupling the first passage of the exhalation valve assembly to the first passage of the second valve assembly, means coupling the second passage of The second valve assembly to the second passage of the first valve assembly, a patient adapter adapted to be connected to the airway of a patient, means coupling said supply of gas under pressure to the patient adapter and to said third passage of said first valve assembly, means coupling the patient adapter to the first passage of said first valve assembly, and an automatically operated controller for controlling the flow of gas from said source and having an inspiratory phase and an expiratory phase in its operative cycle.