Automatic external defibrillators (AEDs) are external devices that can be used by minimally trained laypersons in emergency situations. They not only administer an electrical shock in order to restart the heart, but also read the patient's heart rhythm patterns. This significantly reduces the amount of training needed for their effective use and allows people with minimal training to perform defibrillation in emergency situations with little risk of additional injury to the patient. One study that looked at the usefulness of putting AEDs in Chicago airports found that people were able to revive cardiac arrest patients by using nearby defibrillators, even though they had no training in how to use them.

Automatic defibrillation attempts should begin as quickly as possible. For every minute that passes without defibrillation, a victim’s chance of survival decreases by 7 percent to 10 percent. If the heart does not return to a regular rhythm within five to seven minutes of the onset of cardiac arrest, the result could be fatal. This is why groups such as the American Association Heart and the National Institute Blood and Lung, Heart, advocate the widespread availability and use of AEDs. Indeed, AEDs have become more common in ambulances and fire rescue vehicles, as well as in places that are cut off from traditional emergency assistance, such as airplanes. In fact, all U.S. airlines are now required to carry AEDs on all domestic and international flights.

AEDs are also appearing in increasing numbers of public places, such as stadiums, casinos, shopping malls, health clubs and golf courses. Programs are even appearing in local schools to train students in both  cardiopulmonary resuscitation (CPR) and in the use of AEDs. According to studies, correct use of AEDs can raise the survival rate of victims of cardiac arrest to between 50 percent and 75 percent