A respiratory circuit apparatus and circuit are provided. The circuit includes: an adapter having a plurality of connectors of two or more different internal or outer diameters and a pressure release valve configured to emanate sound if a pressure of a gas received at the pressure release valve is greater than or equal to an activation pressure of the pressure release valve. The pressure release valve can have a first end of a body portion coupled with one of the plurality of connectors of the adapter. The pressure release valve can be coupled inline in the respiratory circuit via the adapter and in close proximity to a patient location.
