The invention relates to a control system (18) of a respiratory device (10) for the at least supportive-partial artificial respiration of patients (12), in particular human patients, comprising a respiratory gas conduit arrangement (30), a pressure changing arrangement (16) for changing the pressure of respiratory gas in the respiratory gas conduit arrangement (30) during the respiratory operation of the respiratory device (10), and the control system (18) for controlling the respiratory operation of the respiratory device (10), wherein the control system (18) has a data input (24, 26) for transmitting operational or/and patient data to the control system (18). Said control system (18) is configured to determine a respiratory operating parameter for the operation of the respiratory device (10) selectively by means of a predetermined first data relationship (54) or by means of a predetermined second data relationship (50) that is different from the first data relationship. According to the invention the control system (18) is configured to determine the respiratory operating parameter for a specific respiratory gas requirement subject to a resistance data value indicating a respiratory resistance of a patient (12) to be ventilated according to the first data relationship (54) or according to the second data relationship (50).
