Kent Peterson, senior editor, has also produced award-winning work in television and radio.

You're at the office when suddenly, one of your coworkers collapses. She's unconscious with no breathing, no pulse. You remember there's a device in the break room that can shock the heart back to normal. But you've never used it and don't know how. Should you try?

Recent research has reassuring answers for both victims and bystanders.

Understanding cardiac arrest

The heart has a built-in electrical system that regulates heartbeats. When problems disrupt that system and the heart suddenly stops pumping life-sustaining blood, it's called cardiac arrest. Most victims immediately faint.

Cardiac arrest strikes more than 350,000 people in the United States each year who are outside of a hospital, according to the American Heart Association. It can happen to anyone, often without warning. Risk rises with age and is also greater for people with coronary heart disease and for men.

Cardiac arrest is different from a heart attack. During a heart attack, the heart is damaged by reduced blood flow due to blocked coronary arteries, but it usually keeps beating. With cardiac arrest, heartbeats cease.

The ABCs of AEDs

An automated external defibrillator (AED) is a portable electronic device that's intended to treat cardiac arrest on the spot. Increasingly common, you've probably seen AEDs in schools, shopping centers, airports, and elsewhere. They're intended to be nearby wherever you go, because without treatment, cardiac arrest can cause death within minutes - perhaps before emergency responders can arrive.

An AED can quickly check the heart's rhythm and deliver an electric shock if needed to help it beat properly again. AEDs are designed to be easy to use, with simple instructions and even voice prompts to guide you.

But do they make a difference in outcomes? Since AEDs are often used by inexperienced bystanders, do they actually save lives? A large study published in the American Heart Association journal Circulation says the answer is yes.

Key findings

An international research team reviewed nearly 50,000 out-of-hospital cardiac arrest cases. They analyzed the ones that happened in public and were suitable for AED treatment. Among their findings:

  • People who got an AED shock from a bystander were more than twice as likely as others to survive, go on to hospital treatment, and later leave the hospital.
  • They were also more than twice as likely to leave the hospital functioning normally.
  • 70 percent of those who had cardiac arrest but did not get shock therapy from an AED either died or were left with impaired brain function.

"We estimate that about 1,700 lives are saved in the United States per year by bystanders using an AED," said senior study author Myron Weisfeldt, MD, in a news release. "This should be a great incentive for public health officials and bystanders to strive to have AEDs used on all victims of cardiac arrest."

Don't wait

Every second counts when cardiac arrest strikes. Act immediately to help someone in need. The odds of survival drop about 10 percent for every minute without treatment. According to the American Heart Association, you should take the following steps in this order:

  • Call 911 to summon emergency responders
  • Start cardiopulmonary resuscitation (CPR) until defibrillation can begin.
  • Use the AED as soon as possible, administering a shock if it directs you to.

Don't worry about hurting someone by shocking them when they don't need it; the AED will tell you whether it detects the kind of heart problem that should be shocked.

What to do now

Anyone can use an AED, but the more you know in advance the better.

Get professional AED and CPR training if you can. Ask your employer about scheduling a group class. The American Heart Association's "Find a Course" tool can help you locate one.

Also, ask where the AED is kept in your workplace - one survey found that half of us have no idea where to look.

An ounce of prevention can give you peace of mind today - and confidence if you're ever faced with this crisis in the future.

Have you witnessed a cardiac arrest? Help others to learn from your experience. Take a moment to add your comment below.

Photo © American Heart Association