A process is provided for operating a respirator and/or anesthesia device in the APRV mode with at least one pressure release phase with the step of setting a first point in time for terminating the pressure release phase. The process includes measuring the electrical impedance and/or impedance change of the lungs and setting the first point in time such that the measured impedance and/or impedance change are taken into account. A device is provided for carrying out the process according to the present invention.
