Abstract: The invention concerns a respiration therapy apparatus used as a drug atomizer and/or a so-called respirator and/or as an oxygen dispenser. In the apparatus of the invention, administration to a patient of oxygen or air is discontinued, at the latest, when the exhalation phase begins. This has been implemented in the apparatus of the present invention by utilizing a pressure pick-up (22) observing differential pressure of the flow and which further provides control of an electromagnetic valve (23) which is disposed to close and to open a pressure line (16). At commencement of the inspiration phase, the differential pressure is transmitted over a signal connection (99) to the pressure pick-up (22). The pressure pick-up (22) further controls the electromagnetic valve (23), opening the pressure line (16).