An Automated External Defibrillator (AED) is a portable device used to administer an electric shock to the heart and restore the heart's normal rhythm during Sudden Cardiac Arrest. Ventricular Fibrillation (VF), the abnormal heart rhythm that most often leads to Sudden Cardiac Arrest, is treatable. If the heart can be shocked quickly with an AED, a normal heart rhythm may be restored.
In the past, defibrillators were complicated and cumbersome. Only medical professionals with extensive training in heart rhythm interpretation could use them. Today, defibrillators used in public places and in the home are automated, portable and easy to use. They are no longer limited to emergency rooms; and are now placed in airports, schools, gyms, and other public places, and most recently in homes. An untrained bystander can successfully deploy an AED by following the voice prompts emitted by the AED after activation. Even a sixth grader can deploy an AED.
An AED consists of a small computer (microprocessor), electrical circuitry and adhesive electrode pads. The electrodes collect information about the heart's rhythm. The microprocessor interprets the rhythm. If the heart is in ventricular fibrillation, the microprocessor recommends a defibrillating shock. The shock is delivered by way of the electrode pads, through the victim's chest wall, and into the heart. The shock stuns the heart momentarily, stopping all activity. This gives the heart a chance to restart normal electrical activity and resume beating effectively.
It is essential that defibrillation be administered immediately following a cardiac arrest. If the heart does not return to a regular rhythm within 5-7 minutes, this fibrillation could be fatal. If defibrillated within the first minute of collapse, the victims chances for survival are close to 90%. For every minute that defibrillation is delayed, survival decreases by 7 percent to 10 percent. If it is delayed by more than 10 minutes, the chance of survival in adults is less than 5 percent.
AEDs play a critical role in the "Chain Of Survival" which can help save the lives of victims of sudden cardiac arrest (SCA). The Chain of Survival is a four-step intervention process developed by the American Heart Association.
- Early Access - First as soon as an emergency is recognized call 9-1-1.
- Early CPR - The critical link that buys time between the first link (call 9-1-1) and the third link (use the AED). Begin Cardiopulmonary Resuscitation (CPR).
- Early Defibrillation - Most sudden cardiac arrest victims are in ventricular fibrillation (VF). Use an AED to Treat VF.
- Early Advanced Care - The fourth is advanced care provided by highly trained EMS personnel called paramedics.
Public Access Defbrillation
Numerous scientific studies conducted during the past two decades have proven that rapid defibrillation is the single most important factor affecting survival from sudden cardiac arrest. This research, coupled with important technological advances, has driven an international movement to increase access to early defibrillation.
In order to have AEDs available more quickly for persons who need them, some facilities (such as hotels, airports, country clubs, schools etc.) are purchasing these devices under what is called a Public Access Defibrillation (PAD) program. Since AEDs are prescription devices and must be labeled with the prescription statement required by law (CFR 801.109), a physician who oversees the PAD program at a facility must write a prescription for most AEDs in order for the facility to purchase it. This is easily accomplished and there are many who are willing to help you start a PAD program. To date, one model of AED has been cleared for the FDA for over-the-counter sale and in-home use.
Public Access refers to accessibility for trained users to use AEDs in public places. While AEDs are now very simple to use and many untrained laypersons have used them successfully, it is best to assure that trained personnel are always on site (at locations where this is feasible). A trained user does not necessarily mean trained medical personal but also refers to laypersons with AED training.