The device generates two pressure levels in the S-, ST- or T-mode via an electrically controlled blower. Switching from one pressure level to another is realized via a quick change of the revolutions of the fitted high-performance blower to keep the stress for the patient as low as possible. S-mode Spontaneous trigger - the change from one pressure level to another is triggered by starting respiration of the patient only. ST-mode Spontaneous breathing and Time - as long as the patient is breathing independently the device is operating in the S-mode. Once the patient stops breathing the device automatically switches into the T-mode and provides respiration for the patient in the prescribed safety frequency. The delay time after which the device switches into the T-mode can be set. T-mode Time respiration with prescribed, set inspiration time. If the trigger function is deactivated the patient is ventilated according to the set parameters. If the trigger function is activated the device accepts only spontaneous trigger signals in the expiration phase. Trigger device The respiration trigger detects the patients efforts to breath in and out and signals these efforts to the control device. A flow-based trigger is integrated which can be set separately for inspiration and expiration. While the pressure increases during inspiration it decreases during expiration. In connection with an optimum slope adjustment ths results in a ventilation which is very comfortable for the patient and which gives the patient the impression as if the device is following the natural respiration without delay.