Sudden cardiac arrest occurs when the heart unexpectedly stops beating, which cuts off blood flow to the brain and other organs. If not treated, it can cause death within minutes. 

In fact, only about 10 percent of people overall who experience it outside a hospital survive with their brain functions intact, a new study in JAMA found.

But early action can stave off the Grim Reaper: When sudden cardiac arrest victims first received CPR from bystanders, they were more likely to survive with favorable prognoses, the researchers discovered.

Related: The Weird Symptoms That Signal You’re Just Days Away From Cardiac Arrest

But the way you perform CPR has changed in recent years. You no longer have to put your mouth on the victim’s. 

Regular, non-medical folks who perform CPR on adult cardiac arrest victims are actually more successful if they don’t include mouth-to-mouth breaths, says Vinay Nadkarni, M.D., spokesperson for the American Heart Association (AHA).

People who perform compression-only CPR may initiate it more quickly, as well as deliver more chest compressions with fewer interruptions, according to an AHA report in Circulation.

How to Perform CPR the Right Way 

Before you do anything, call 911 first. 

Then perform compression-only CPR. Kneel over the person, placing the heel of your hand on the middle of his or her chest. Put your other hand on top. 

Then, push hard and fast, pumping down to the beat of the song “Stayin’ Alive” by the Bee Gees.

The tempo of the song is 100 beats per minute, which is just fast enough to keep circulating oxygen that’s already in the patient’s body, basically doing the work of the heart. 

CPR is a workout, and even an athletic guy will start to wear out from compressions after 2 minutes, says Dr. Nadkarni.

But don’t try to pace yourself—maintaining speed and force is crucial. Instead, see if another bystander could take over until help arrives—or until you’re ready to get back in there.