Breathing device comprises a control unit for evaluating the alveolar ventilation of the user as a breathing parameter. An independent claim is also included for a method for controlling the breathing device using the control unit of the breathing device. Preferred Features: The alveolar ventilation is used as the control parameter. The carbon dioxide concentration in the exhaled air is used as a control parameter. Invasive and/or non-invasive blood gas analyses are also used as control parameters.
