The algorithms used in automated external defibrillators (AED) do not provide the necessary reliability of detection of fibrillation, especially in presence of artifacts. The system described in this article allows detecting different artifacts, improving the detection quality. Also an approach is suggested, to extend the AED functions to detect pulseless electrical activity. The new algorithm uses the impedance signal as an additional parameter to diagnose the cardiac arrest. The parallel analysis of ECG and impedance signals allows detecting noise, motion, respiration and hemodynamic parameters. The comparative tests of the algorithm demonstrated the excellent performance of the algorithm.