Breathing assistance apparatus includes a gases supply unit adapted to, in use, deliver a stream of pressurised gases from an outlet. The gases supply unit is adapted to vary the pressure of the stream of pressurised gases. A supply path includes a flexible self-supporting gases transportation pathway having a first end connected to the outlet so that the gases transportation pathway receives the stream of gases and conveys the gases to a patient. A patient interface is connected to the second end of the gases transportation pathway receives a stream of gases. At least one sensor measures at least one information parameter of the supply path. A control system associated with the gases supply unit receives the information parameter. The control system contains reference data, and compares the received data to reference data, and determines a supply path based on the comparison.