An apparatus for providing positive airway pressure in a respiratory circuit comprising a container for holding a liquid and defining an opening for receiving a positionable tube assembly, the positionable tube assembly comprising a tube movably positioned in the opening and having a first end positioned outside the container and defining a gas inlet and a second end positioned within the container and defining a gas outlet the tube defining on one surface a plurality of slots positioned at predetermined discrete distances from each other between the first end and the second end of the tube the tube having on another surface a continuous recessed track extending between the first end and the second end of the tube, the recessed track defining a zig-zag path such that after an extension of the track from the first end of the tube towards the second end of the tube by the predetermined discrete distance, the track extends in a first direction towards the surface of the tube defining the plurality of slots, followed by another extension of the track towards the second end of the tube before extending in a second direction that is opposite the first direction a track pin fixedly positioned on the container and configured for travel within the continuous recessed track as the tube is moved in or out of the container by a side to side twisting action a stop member positioned on the container and configured to engage a slot to prevent movement of the tube a spring for biasing the stop member towards the tube and a button for dis-engaging the stop member from a slot against the spring to permit movement of tube into or out of the container.
