Apparatus for supplying respiratory gas, comprising a respiratory gas source, a control unit, a storage device, a pressure sensor instrument and/or a flow sensor instrument, a replaceable respiratory gas tube, at least one connection fitting for the respiratory gas tube, a patient interface, and a patient valve, wherein the control unit activates a first ventilation mode for a first duration and in the process actuates the respiratory gas source to specify a changing respiratory gas parameter, and the control unit activates a further therapy mode for a second duration and in the process actuates the respiratory gas source to specify a respiratory gas parameter specific to the further therapy mode, the respiratory gas tube remaining on the apparatus when switching from the first ventilation mode to the further therapy mode, and the patient valve being switched for the further therapy mode by the control unit.