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What Can Defibrillators and AEDs do?

An EKG print out (mgstanton, Flickr).

(An earlier version of this article from 2005 misspoke about what defibrillators can do for cardiac arrest, as well as the definition of fibrillate. Below is an updated version with sources and corrected information.)

The Oxford Living Dictionary defines the word "fibrillate" as: (of a muscle, especially in the heart) make a quivering movement due to uncoordinated contraction of the individual fibrils."

The Circulatory System

A person's heart runs their circulatory system: it pumps blood in and out. The heart is controlled by an electrical system that tells the heart when to pump, and regulates the rhythm. Â There's much more to it (check out some of the sources below if you're interested), but when a person's heart arrests, or when it starts to quiver and beat irregularly, you need to use an AED (an automated external defibrillator).

Manual defibrillators, used by skilled medical professionals, are what are most seen on TV. They have paddles. You've probably heard an actor on a medical TV show yell, "Clear," and shock someone. An AED, which are in many public places, has patches instead.

Cardiac Arrest

The patches use just enough voltage to shock the heart back into a regular rhythm without burning the skin. It's kind of like restarting a computer when it freezes up. The defibrillator tries to do just what its name says, it de-fibrillates, meaning that it stops the irregular beating and resets the heart to beat regularly.

There are many different heart health issues which can cause a heart to irregularly beat, but the most frequent occurrence is a heart attack.

When someone experiences cardiac arrest, it means their heart has stopped beating, but there are still electrical rhythms in the heart that can be corrected. A person who is experiencing cardiac arrest collapses, they aren't breathing, they don't have a pulse, and they aren't conscious.

First Aid Skills

An AED when used correctly and within a few minutes of the person's collapse, can increase their chances of survival. The AED when applied to a person will monitor their heart rate, calculate the right shock to help the person's heart, and prompt whoever is using to push a button to allow the shock to be administered.

It's highly encouraged for people to take classes in how to use an AED, as well as how to give CPR and chest compressions. The more people with professionally taught first aid skills, who can help those in, in case of an emergency the better.

Asystole And Defribillators

Sudden cardiac arrest is different than asystole. What you have probably seen on TV shows is someone yelling flatline, which is a common term for asystole which is when the heart has no electrical rhythms to shock back into place, and then using a defibrillator. And while medical TV shows have gotten better about not showing someone being impossibly shocked back to life in that state, it's still a common misconception.

In asystole, if a heart is shocked it can make the condition worse. A doctor will administer CPR, potentially administer drugs, and/or attempt other procedures based on their assessments.

Sources And Further Reading:

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