New research shows that more bystanders are willing to attempt CPR if an emergency dispatcher gives them firm and direct instructions -- especially if they can just press on the chest and skip the mouth-to-mouth.

Two new studies conclude that "hands-only" chest compression is enough to save a life. The studies are the largest yet to suggest that breathing into a victim's mouth isn't needed in most cases.

Only about 6 percent of people who suffer cardiac arrest outside a hospital survive. However, one study reported survival rates of about 12 percent when bystanders were coached by dispatchers to do CPR. There was no difference in survival rates between hands-only and traditional CPR.

The studies are in Thursday's New England Journal of Medicine.