A control system of a respiratory device for the at least supportive-partial artificial respiration of patients, in particular human patients, comprising a respiratory gas conduit arrangement, a pressure changing arrangement for changing the pressure of respiratory gas in the respiratory gas conduit arrangement during the respiratory operation of the respiratory device, and the control system for controlling the respiratory operation of the respiratory device. The control system has a data input for transmitting operational or/and patient data to the control system. The control system is configured to determine a respiratory operating parameter for the operation of the respiratory device selectively by means of a predetermined first data relationship or by means of a predetermined second data relationship that is different from the first data relationship.
