Dispatchers should give CPR instructions to bystanders of all suspected cardiac arrest victims, researchers said. The benefit of CPR to those having a cardiac arrest far outweighs the risk of injury to those who aren’t. During 9-1-1 calls, dispatchers help bystanders correctly identify patients in cardiac arrest about half the time. Of 1,700 patients studied, three who incorrectly received CPR had minor injuries linked to chest compressions.