Automated external defibrillator on the wall. AEDs are used for cardiac arrest heart attacks.

Have You Seen an AED Lately?

There’s a hero inside you. When someone is in cardiac arrest, you can save their life. You do not need medical training. If you can follow pictorial directions, you can do this. All you need is an automated external defibrillator (AED).

“AEDs analyze a deadly heart rhythm and can save somebody's life. And anybody can use one. Nobody should be intimidated about using an AED,” says Daniel O'Connor, MD, a cardiologist at ColumbiaDoctors and associate professor of medicine at Columbia University Vagelos College of Physicians and Surgeons.

AEDs are becoming more commonplace since Buffalo Bills player Damar Hamlin collapsed on the field during a football game. AEDs are small, portable devices already stored in many public places—stores, restaurants, offices, schools, airports—ready to be used. But many people are unaware of them or afraid to use one.  

We asked O’Connor what it takes to use an AED, why it works, and why we should have no fear.  

When is an AED needed?  

When someone is in cardiac arrest—which most often involves them falling and always means they do not have a pulse—they need an AED to get their heart beating again. You may have seen this on TV lately, when Buffalo Bills player Damar Hamlin had a cardiac arrest during a game. His recovery is in part due to the use of an AED.  

AEDs help get a heart rhythm back to normal and restore circulating blood to all the major organs, especially the brain. 

What is an automated external defibrillator (AED)? 

An AED is a small medical device that analyzes a heart’s rhythm and delivers an electrical shock (defibrillation), if needed, to help re-establish a steady rhythm. 

AEDs are special because you do not need to be a doctor to use them. You just need to attach it to a person you think is having cardiac arrest, as fast as you can, to save somebody's life. 

The AED will determine whether someone needs a shock. The machine only recognizes life-threatening heart rhythms as shock-worthy. No other rhythm would be helped by defibrillation so no shock is delivered in other cases. That's why you cannot hurt someone with an AED. 

An AED is so smart it won’t cause harm if you’re wrong because it won't deliver a shock? 

Right. AEDs actually speak to you. The device will say “shock not appropriate” or something similar, depending on the model, if it’s not appropriate to use. You cannot hurt someone.  

The AED will analyze the heart's electrical activity and will only defibrillate if it needs to. It will not defibrillate if the heart rhythm is not what’s called a shockable rhythm. 

How do you use an AED? 

  1. Turn it on.  
  2. Follow the illustrated instructions.  
  3. There will be two pads. 
    • The pictures will show you where on the chest to place the pads. 
  4. Plug the wires into the machine and the power goes on. 
  5. The AED charges itself, analyzes the person’s heartbeat, and gives verbal instructions, such as “appropriate shock” and “clear,” along the way. 
  6. Do not touch the person while the AED is analyzing the rhythm or delivering a shock.

AEDs vary slightly depending on manufacturer, but a shock is only delivered if needed.

Pictorial instructions are always included for ease of use. If you can follow simple, elementary school-level explanations, you can save someone’s life.  

What happens after an AED delivers a shock? 

After a shock, assess the person’s consciousness. If they begin to move or speak, stop the AED. Otherwise, continue to follow the instructions of the AED until medical personnel arrive.   

What should you do if no AED can be found? 

Call 9-1-1.  

Get your hands on the person’s chest and start compressions. There’s no need for mouth-to-mouth resuscitation. Continue chest compressions until medical personnel arrive.   

How can I be ready to use an AED? 

Automated external defibrillator sign and logo. AED cardiac arrest heart attacks.

Everywhere you go, whether it’s an event space, at a kid's game, in a school, at a restaurant, look for an AED. The signs are clear and visible. The location is something to note because it just takes one person in a crowd to know where an AED is and save somebody's life.   

You see that story all the time: People saving people. As a member of the community, it's part of our responsibility when we go to public places: If you come across an AED in passing, note it so you can remember where it was. 


Daniel O'Connor, MD, PhD, is associate professor of medicine at Columbia University Vagelos College of Physicians and Surgeons; co-director of the Center for CardioOncology; a cardiologist at the Aortic Program; and a cardiac intensivist at Columbia University Irving Medical Center. O’Connor is an expert in the research and cardiac care of athletes, known as sports cardiology.