There are new guidelines for administering cardiopulmonary resuscitation or CPR.
The American Heart Association says rescuers should now first press on a person's chest before breathing into their mouth. And they recommend alternating 30 chest compressions and then giving just two breaths.
The AHA also says a person administering CPR should push at least two inches deep into the chest.
The change puts "the simplest step first" for traditional CPR, said Dr. Michael Sayre, co-author of the guidelines issued by the American Heart Association.
"When the rescuer pushes hard and fast on the victim's chest, they're really acting like an artificial heart. That blood carries oxygen that helps keep the organs alive till help arrives," said Sayre, an emergency doctor at Ohio State University Medical Center.
"Put one hand on top of the other and push really hard," he said.
The new change applies to adults and children. Rescuers should also pump the chest of a victim at the rate of a least 100 compressions a minute.