A respiratory device comprises a respirator having a controllable respiratory gas source, a programmable control unit and at least one sensor unit for determining pressure and/or flow of respiratory gas. The control unit controls a respiratory gas source to specify a first respiration pattern. The respiratory device comprises at least two further sensor units, a first sensor unit comprising a plurality of individual sensors for generating and/or measuring electrical potentials and noninvasively determining the electrical impedance of the lungs of a patient, a second sensor unit for noninvasively determining the carbon dioxide supply and a third sensor unit for noninvasively determining the oxygen supply of the patient. The control unit evaluates the measured values of the first, second and third sensor units to determine the instantaneous ventilation of the lungs during the respiration using the first respiration pattern, the instantaneous carbon dioxide supply and the instantaneous oxygen supply.
