What is an AED?

An AED, or Automated External Defibrillator, is a small, lightweight device that analyzes a person's heart rhythm and can recognize ventricular fibrillation (VF), also known as sudden cardiac arrest (SCA). AEDs are designed to be used by "first responders". A first responder is the person to first arrive on the scene of a medical emergency, and can be an emergency medical services worker, a firefighter, police officer, or even a layperson with minimal AED training.

Why are AEDs important?

When a person suffers a sudden cardiac arrest, the chance of survival decreases by 10% for each minute that passes without defibrillation. Up to 100,000 lives could be saved each year if AEDs were widely used.

Who can use an AED?

Almost anyone can learn to operate an AED with a few hours of training. Flight attendants, security personnel, sports marshals, police officers, firefighters, lifeguard, family members, and other trained laypersons have used AEDs successfully. AEDs are most effective when training and equipment maintenance programs are followed.

Will an AED always resuscitate someone in cardiac arrest?

No. The AED treats only a heart in ventricular fibrillation. In cardiac arrest without ventricular fibrillation, the heart does not respond to electric currents, but needs medication instead. The victim also needs breathing support. AEDs are less successful when the victim has been in cardiac arrest for more than a few minutes, especially if no CPR was provided.

Do AEDs replace the use of CPR?

CPR is still needed, starting with determining whether a person is unconscious, breathless, or pulseless. When a person experiences cardiac arrest, CPR will help keep oxygen flowing to the brain, but the electric shock of an AED vastly improves the chances of restarting the heart.

What's the difference between an AED and the defibrillators used in hospitals?

In-hospital defibrillators are manual, larger than AEDs, and designed to be used only by qualified medical personnel with special training to use the device and to recognize heart rhythms. Medical personnel who use the device must decide whether or not to shock the person. Manual defibrillators also have additional capabilities such as pacing and cardioversion.

AEDs are programmed to recognize different heart rhythms and to make the shock/no shock decision, so that users don't have to. They were designed so that lifesaving defibrillation could be performed as quickly as possible.

Are There Limits Regarding Who the AED Can Be Used On?

AED defibrillation can be used on infants and children as well as adults, as long as the appropriate pads are used. Typically, children over 25 kg or 8 years of age are defibrillated as adults.

What is Sudden Cardiac Arrest (SCA)?

Sudden cardiac arrest (SCA), also known as ventricular fibrillation (VF), is an electrical malfunction of the heart. The regular, systematic pumping action of the heart’s chambers stops because the normal electrical signal that runs through the heart in a prescribed sequence has been interrupted. Electrical chaos ensues, and results in uncontrolled, non-productive quivering of the heart chambers.

Is SCA the Same Thing as a Heart Attack?

A heart attack and SCA are two different things, although they can occur together. A heart attack is caused by a blockage in a coronary artery which results in a sustained lack of blood flow (and consequently oxygen) to a part of the heart. If the blockage is not resolved in a timely manner, the heart tissue below the blockage will "infarct" or die. If the dead tissue also happened to be part of the heart’s electrical system, SCA could be triggered.

Isn't calling 000 enough?

Lack of equipment and time delays are a reality, and not every emergency vehicle carries a defibrillator. On average, it takes an ambulance or emergency medical service team in Australia over 10 minutes to arrive. Survival rates are highest for victims who receive a defibrillation shock within 3 minutes of collapse. This requires that an AED be onsite anywhere groups of people gather and that trained responders are available. Up to 95% of all SCA victims die with CPR alone. A victim's chance of survival from SCA decreases by 10% with every minute that passes. Survival rates can rise to 70% when a AED unit is first used.

Can I Hurt Someone with an AED?

A victim of SCA is essentially dead. Use of a AED represents a victims's only viable chance for survival. AEDs have numerous built-in safeguards and are designed to deliver a shock only if the AED detects that one is necessary.

What About Using a AED in a wet environment?

Most AEDs because they are self-grounded, so they should be able to be used in wet environments and on metal surfaces safely.

How an AED works on the heart

When a heart goes into an uncoordinated electrical activity called fibrillation, the heart twitches ineffectively, can't pump blood and appears to have stopped beating. This condition is called sudden cardiac arrest (SCA) and often accompanies severe heart attacks.

The Automated External Defibrillator (AED) is a small, portable device that administers an electric shock to the heart. A built-in computer assesses the victim's heart rhythm, judges whether defibrillation is needed, and then administers an appropriate level of shock. Audible and visual prompts guide the user through the process. A AED unit will stun the heart, disrupting the electrical chaos, and allow the normal electrical sequencing of the heart and pumping action to resume.

The AED is designed to be used by a layperson "first responder" - a person with AED training. No medical training is needed to use a AED. Here is a summary of how a AED unit works:

1. The first prompts tells the user to connect the electrodes to the AED and to stick the adhesive electrode pad(s) to the victim's bare chest. The electrodes send the heart's electrical rhythm data (ECG) to the AED unit.

2. The AED then analyzes (and sometimes displays) the ECG heart rhythm. It checks characteristics such as frequency, shape, slope, amplitude and heart rate. Based on these characteristics, the AED determines whether or not a shock is needed.

3. If a shock is needed, the AED will prompt the user to either press a button to deliver the shock, or to stand back to deliver the shock automatically. The AED starts building up the requires electrical charge and then delivers an electrical shock to the victim.

4. The AED next re-analyzes the heart rhythm to determine if another shock is needed. If so, another shock is administered.

5. If a "shockable" heart rhythm is not detected, the AED will prompt the user to check the victim for a pulse and to perform CPR.

* In all cases, CPR should be administered - using an AED for resuscitation is not enough.*