If a loved one, a co-worker or even a complete stranger collapsed, would you know what to do?
Automatic external defibrillators are becoming commonplace, especially in big, public places such as airports. They are simple devices that shock the heart back into a normal rhythm.
"AEDs are probably one of the most foolproof things we have in medicine," said Dr. Paul Pepe, a nationally known expert on the devices at Parkland Medical Center and UT Southwestern Medical Center.
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Sudden cardiac arrest kills 325,000 people in the United States per year, more than 1,000 per day, according to the Heart Rhythm Foundation.
"Almost the majority of the cases can be reversed, and the person can come around and be waking up and talking to you in a matter of minutes," Pepe said.
But many people don't know where to find AEDs -- or how to use them.
"They say, 'We got AEDs in our building,' and then when it happens, they don't know where it is," Pepe said.
For every minute that ticks away without treatment, the chances of surviving sudden cardiac arrest drop 10 percent.
AEDs are often located in high-traffic areas such as break rooms or near restrooms. In a crisis, call 911. Someone should start chest compressions while another person runs to get the AED.
The American Red Cross says the devices are easy to use.
Step 1: Open the box, and the machine starts telling you what to do.
Step 2: Follow the instructions and stick the pads on the person's bare chest.
Step 3: Step away. The machine will decide if the person needs to be shocked.
There are different models of AEDs, but they're all basically the same.
"We actually put these AEDs in front of a bunch of six-graders and said, 'Just use them,'" Pepe said. "And most of them were able to use them within a matter of seconds."
Laura Friend works full-time with Cook Children's Medical Center as an advocate for AED awareness in schools in memory of her daughter.
"If I can save my neighbor's child, then this is what I'm supposed to do," she said.
Her 12-year-old daughter, Sarah, died in 2004 after she collapsed at a North Texas water park. The use of an AED almost certainly would have saved her, Friend said.
"They did bring AEDs to her side," Friend said. "They have them at the park, but they didn't use them. She laid there for 21 minutes before EMS arrived."
AEDs cost about $1,500.
NBC 5's Brian Curtis contributed to this report.