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A Guide to Automated External Defibrillators

by Dr. Mary Williams, R.N. D.C.

Heart attacks and cardiac arrest are generally associated with older people or those with known heart issues. But the unfortunate truth is that anyone - young, old, fit, or unhealthy - can go into cardiac arrest without warning. If they are left without treatment, the result of such an attack can be deadly. Special training is required for most first aid, but in the case of cardiac arrest, there is a device that requires no training whatsoever to use. Saving a life is as easy as opening an automated external defibrillator (AED), which can be found in almost every public building and workspace.

History of the AED

The first AED was used in 1947 by Claude Beck, a cardiac surgeon, but research into defibrillation began long before that. As early as the 1890s, Jean-Louis Prost and Frederic Batelli of the University of Geneva were experimenting with the revival of animals through a shock to the heart. Beck owned a research unit for these experiments, but it was desperation that led him to use it on a human. Beck was performing heart surgery on a 14-year-old boy when the patient's heart stopped. When no other method would revive the boy, Beck quickly pulled out his research unit and administered two shocks directly to the heart with metal spoons. The patient was saved, and Beck's action sparked the research necessary to produce the first portable defibrillator in 1965.

Over the years, and thanks to developments in electronics, AEDs became capable of diagnosis and administering a precisely calculated shock to a patient's heart through the use of two padded electrodes. The first early AED models produced a severe shock of up to 400 joules, which put the patient at risk for cardiac injury and intense burns from the shock pads. Today, an AED will measure the electrical current of the patient's heart and automatically determine the level of shock necessary. Most versions even have step-by-step instructions, provided by a voice recording or visual insert, to walk the user through the electrical shock process.

AED Certification

The modern AED has been designed to allow correct usage by any untrained passer-by, but once the patient has been revived, follow-up care like CPR may be required. Often, CPR and AED training are taught together in the same course. To become certified in AED use, an individual will need to attend a series of classes, demonstrate the skills taught in those classes, and achieve a certain score on a written exam. Once achieved, the certification is valid for a period of two years, and the course is open to any and all interested parties.

When an AED Should Be Used

An AED is used specifically to treat ventricular fibrillation and ventricular tachycardia, both of which are forms of cardiac arrhythmia (when the heart's natural rhythm is disrupted and therefore rendered unable to pump blood). By applying an electrical shock through an AED, the machine can restore the heart's natural rhythm. It is critical to apply an AED to the patient within the first three minutes of cardiac arrest, as damage to the brain can occur after that period. If an AED is not available, CPR should be administered while another person calls emergency services and attempts to locate an AED.

Precautions to Take Before Using an AED

Signs of cardiac arrest can include a loss of responsiveness, irregular or absent pulse, and no normal breath when the head is tilted up. Before applying an AED, it is important to make sure that neither the AED user nor the patient are in or near water. If this is the case, the victim should be moved to a dry area before administering AED. If the patient's chest is wet, it should be dried off as well.

All metal, including necklaces and underwire bras, should be removed from the patient in order to prevent electrical burns, and if the patient has chest hair that prevents the pads from adhering, it may need to be shaved off. Most AED kits will include a razor in them for this exact purpose. Once the patient is prepared, it is important that no one touch them when the AED is in use, as the electrical current of another body may interrupt the machine. The same is true while the AED is delivering a shock; make sure that no one is touching the patient or the machine to avoid an accidental shock to the rescuer. Most AEDs will have these guidelines outlined in their instructions, and by taking the necessary precautions, an AED can be easily and successfully used by anyone to treat patients of cardiac arrest.