Abstract: A device and method for recommending an initial treatment of either a defibrillation shock or CPR for a cardiac arrest victim. An embodiment of the invention is directed to an AED with treatment protocols selected from a set of external defibrillation, CPR, or a combination thereof. The AED includes a power generation circuit, pair of external electrodes, and an ECG sensor. AED further includes a control system including a microprocessor configured to determine a survivability index number for a patient and recommend a treatment protocol using the AED as well as a communication system configured to communicate the selected protocol to a user of the AED.