Anaesthetic system valve for converting between Mapleson `A`, `D`, and `E`c

摘要

A valve for an anaesthetic rebreathing system includes a valve body, a selector member situated within the valve body and a relief valve which forms an integral part of the valve. The valve can be converted from a Mapleson A to a Mapleson D configuration and from a Mapleson A or D configuration to a Mapleson E configuration. The valve body includes a fresh gas inlet, a fresh gas outlet, a fresh gas conduit in communication with the fresh gas inlet and a fresh gas outlet, an expired gas inlet/outlet port, a waste gas outlet, an expired gas conduit in communication with the expired gas inlet/outlet port and the waste gas outlet, a reservoir bag or ventilator inlet/outlet port and a reservoir bag or ventilator conduit in communication with the reservoir bag or ventilator inlet/outlet port, the conduits converging at a node within which the selector member is movable to isolate the expired gas inlet/outlet port and the waste gas outlet from the reservoir bag or ventilator inlet/outlet port in a first position thereof and to isolate the fresh gas inlet and the fresh gas outlet from the reservoir bag or ventilator inlet/outlet port in a second position thereof, the relief valve, which allows for control of pressure in the expired gas conduit, being adjustable between a first setting in which expired gas may flow freely out of the waste gas outlet and a second setting in which the waste gas outlet is completely occluded, and being adapted, in its second setting, to lock the selector member in the second position.