Emergency defibrillator. Automated external defibrillators (AEDs) are portable electronic devices stored in public places such as shopping centres, schools and airports. They are used as a primary means of CPR (cardiopulmonary resuscitation). AEDs automatically analyse the patient's condition during cardiac arrest and instruct the user how to connect the electrode pads onto the patient's chest in order to re-establish their normal heart rhythm. This AED (left) was photographed at Gatwick Airport in the UK, along with an emergency first aid kit (right).