Learning CPR isn’t what it used to be. For one thing, “hands-only” CPR requires fewer steps – no pulse check or mouth-to-mouth required – which safety officials hope will lead more people to perform it. Also, these days, “Stayin’ Alive,” the Bee Gees’ disco anthem, keeps coming up. Its beat – “Well, you can tell by the way I use my walk,” and so on – matches the 100 chest compressions a minute required during resuscitation efforts. Keep that worm in your ear, safety advocates say, and you’ll be on track to simulate a cardiac arrest victim’s heartbeat.