An automatic defibrillator is a portable device that runs on batteries , and whose task is to analyze the cardiac activity of a person who suffers a cardiac arrest. This analysis is fully automatic, which avoids the operator to take any decision. Only external shocks are possible, this means the electrodes are placed on the skin of the patient. If it detects a shockable rhythm , the machine can deliver an electric shock, or defibrillation.

The first commercial automatic defibrillator is dating from 1994.

Early defibrillation associated with CPR greatly increases the chances of survival of a person in cardiac arrest presenting ventricular fibrillation , the leading cause of sudden death in adults.

So that this medical procedure can be performed as soon as possible , simplified devices appointed fully automatic defibrillators or semi-automatic defibrillators ( AED ) were created. These devices automatically conduct the diagnosis of ventricular fibrillation , due to a layout analysis software electro cardiographic . They are used by rescuers , but also by untrained public.

In Europe, each year about 700,000 people die from cardiac arrest.

The period of survival after cardiac arrest is very short, on the order of 4 to 5 minutes . This is why access to automated defibrillators (AED) significantly increases the chances of survival of victims.