An Automated External Defibrillator (AED) is a portable electronic device that automatically diagnoses the potentially life threatening cardiac arrhythmia of ventricular fibrillation and ventricular tachycardia in a patient. It is able to discern whether the victim would benefit from defibrillation which is the application of electrical therapy that can correct the arrhythmia, allowing the heart to reestablish an effective rhythm.

AEDs are designed to be simple to use for the layperson, and the use of AEDs is taught in most first aid, first responder and basic life support (BLS) level CPR classes.

A microprocessor inside the defibrillator interprets (analyzes) the victim's heart rhythm through adhesive electrodes. The computer analyzes the heart rhythm and advises the operator whether a shock is required. AEDs advise a shock only for ventricular fibrillation and fast ventricular tachycardia. The electric current is delivered through the victim's chest wall through adhesive electrode pads.

AEDs strengthen the chain of survival. They can restore a normal heart rhythm in sudden cardiac arrest victims. Also, the newer portable models allow more people to respond to a medical emergency where defibrillation is immediately required. When a person suffers a sudden cardiac arrest, for each minute that passes without defibrillation, the chance of survival decreases by 7-10 percent. AEDs save lives!

Almost anyone can learn to operate an AED with a few hours of training - no medical background is needed to use an AED, simply a willingness to help if required. In fact, the American Heart Association says, “AEDs are sophisticated, computerized devices that are reliable and simple to operate, enabling lay rescuers with minimal training to administer this lifesaving intervention” (a defibrillation shock), and “flight attendants, security personnel, sports marshals, police officers, firefighters, lifeguards, family members, and many other trained laypersons have used AEDs successfully.”

AEDs are designed to help people with minimal training safely use them in tense, emergency situations. They have numerous built-in safeguards and are designed to deliver a shock only if the AED detects that one is necessary.

Their ease of use and built-in safety mechanisms make AEDs suitable for use in community or company-wide programs

Emergency medical service (EMS) professionals and firefighters save many SCA victims each year, but a lack of equipment and time delays keep them from saving more.

Unfortunately, not every emergency vehicle in every jurisdiction carries a defibrillator, the only device that can treat sudden cardiac arrest.

In some large metropolitan areas, an ambulance may not even get to the scene in less than 10 minutes due to traffic or other restrictions to access. Also on average, it takes EMS teams in North America 6-12 minutes to arrive. So, even if an EMS team does have a defibrillator, the response time may not be fast enough to save a victim's life. These statistics refer to the best-case scenario; now consider EMS response times in more remote areas which are often reported at 30 minutes or greater...

Survival rates are highest for patients who receive a defibrillation shock within three minutes of collapse (often referred to as "drop to shock" time). This ideally requires that an AED be on-site anywhere groups of people gather and that trained responders are available to return with the unit in less than 3 minutes.

Remember, 90-95 percent of all SCA victims die. Documented AED programs have shown that survival rates can rise to 70 percent or greater when an AED program is in place.

Waiting for medical professionals when someone is in sudden cardiac arrest delays treatment - and could cost the victim his or her life. Immediate use of an AED while awaiting EMS response is a proactive way to extend the chance of surviving an SCA.

Some organizations and communities allow their concern about liability for AED acquisition and use be a stumbling block to implementation. There is good news: all 50 states in the U.S. and all provinces in Canada have Good Samaritan laws, giving immunity to lay people who act prudently when helping others in distress. On the federal level, the Cardiac Arrest Survival Act of 2000 encourages placement of AEDs in federal buildings and protects users, purchasers and trainers from litigation following emergency use of an AED. In all Canadian provinces, volunteer rescuers who use AEDs in an emergency have liability protection.

These laws, combined with wider use of AEDs and mounting evidence that AEDS improve survival rates, are setting a new standard of care.

“In most settings, the medical benefits of AEDs far outweigh any legal risks,” counsels Richard A. Lazar, an attorney in the field. “As these devices become more widely used, there will potentially be greater liability risk for organizations not adopting AED programs.”

It has been proven that AEDs can dramatically improve survival rates for sudden cardiac arrest. In two studies, survival rates exceeded the national average by 10 times when AEDs were readily available.† In one of these studies, published in the New England Journal of Medicine, survival rates in witnessed cases of SCA due to ventricular fibrillation reached 74 percent when the first shock was given within three minutes.‡
These studies prove what has been intuitively known for years: early defibrillation by trained laypersons works and the earlier SCA victims are defibrillated, the better the outcome.

†White, R.D. et al. 1996.High discharge survival rate after out-of-hospital ventricular fibrillation with rapid defibrillation by police and paramedics. Annals of Emergency Medicine 28: 480-485.

‡Valenzuela, T.D. et al. 2000.Outcomes of rapid defibrillation by security officers after cardiac arrest in casinos.

Perform CPR only until the AED arrives. Apply the electrodes to the patient's bare chest and follow the voice prompts and messages of the AED. It will tell you when if and when to resume CPR. CPR is a holding action until the heart is defibrillated.

CPR provides some circulation of oxygen rich blood to the victim's heart and brain. This circulation delays both brain death and the death of heart muscle. CPR buys some time until the AED can arrive and also makes the heart more likely to respond to defibrillation.

The IP Code defined in international standard IEC 60529 classifies the degrees of protection provided against the intrusion of solid objects (including body parts like hands and fingers), dust, accidental contact, and water in electrical enclosures. It consists of the letters IP (for "international protection rating" sometimes also interpreted as ("ingress protection rating") followed by two digits and an optional letter. The standard aims to provide users more detailed information than vague marketing terms such as "waterproof".

The following AEDs have the highest to lowest IP rating:

• HeartSine Samaritan PAD: IP56
• Medtronic LP1000: IP55
• Philips FRx: IP55
• Zoll AED Plus: IP55
• Philips FR2: IP54
• Defibtech Lifeline: IP54
• Welch Allyn AED 10: IP24
• Cardiac Science G3: IP24
• Philips Onsite: IP21
• Medtronic CR Plus: IPX4*