The American Red Cross provides lifesaving training to give people the skills and confidence they need to respond effectively in emergencies. CPR can widen the survival window for an SCA victim, but a normal heart rhythm can be restored only by defibrillation. In contrast to a heart attack, in which blood flow to the heart is temporarily stopped, SCA is generally caused by an electrical malfunction in the heart that prevents it from pumping blood effectively. AEDs are designed to be safe for both the operator of the device and the recipient of the shock. According the American Heart Association, AEDs also prevent unnecessary shock.
Special sensors detect if a cardiac arrest victim needs a shock.
Many AED models also use voice and visual prompts so that the operator can easily tell if he or she is using the device correctly. Because it is virtually impossible to predict when and where someone will be when sudden cardiac arrest occurs, the American Heart Association, the Red Cross and others have recommended the widespread deployment of AEDs in highly-trafficked public places such as airports, sports stadiums and large office buildings. According to Scott Conner, Vice President of the American Red Cross' Health, Safety and Community Services, defibrillation has the most life-saving potential when administered within four minutes of cardiac arrest. If a victim has to wait for a defibrillator-equipped ambulance to arrive on the scene, his or her chances of survival drop by ten percent each minute of the delay. If an AED and a trained responder are available on the scene, the victim's chances for survival increase dramatically.