Abstract: A respirator with an inhalation line (3), an exhalation line (5) with an exhalation valve (6), with a pressure-measuring device (8) for measuring the airway pressure, and with a circuit (7) for controlling the phases of breathing. The circuit is connected at least to the exhalation valve (6). A rapid reduction in pressure in the breathing gas lines (3, 5) is possible at any time using a control valve (10) in the inhalation line (3) provided with a control pressure space (15) and with a discharge port (19) which can be opened to the environment through a valve element (14). A control pressure line (16), which is branched off from the inhalation line (3) and can be connected to the control pressure space (15), is present. A reversing valve (17) with an evacuation line (18), through which a flow connection can be established between the control pressure space (15) and the evacuation line (18), is arranged in the control pressure line (16).