CPR can be used in a vast array of different emergency situations. When someone has been drowning, for example, another person can perform CPR on them until the ambulance or other help gets there. A massive heart attack that has rendered a person incapable of breathing can be counteracted using CPR. Drug overdoses are another instance where CPR can save a life. There are literally hundreds of different times when this technique can make a difference. The whole point is to keep oxygen flowing in the injured party’s body long enough for them to get to a hospital.