There is provided a looped tether to prevent the over-withdrawal of a suction catheter from a connecting fitting in a closed suction catheter respiratory device. The looped tether is made from a single thread or strand that is looped or doubled in length with the two loose ends connected together to produce the loop. The looped tether provides better distribution of the forces at the ends of the device and is relatively simple to assemble. Also provided is a system for preventing the over-withdrawal of a suction catheter from a connecting fitting in a closed suction catheter respiratory device.