Cardiopulmonary resuscitation (CPR) is a lifesaving technique that's useful in many emergencies, such as heart attack or near drowning, in which someone's breathing or heartbeat has stopped.
The American Heart Association recommends starting CPR with hard and fast chest compressions. This hands-only CPR recommendation applies to both untrained bystanders and first responders. CPR can keep oxygen-rich blood flowing to the brain and other organs until emergency medical treatment can restore a normal heart rhythm. When the heart stops, your body no longer gets oxygen-rich blood. The lack of oxygen-rich blood can cause brain damage in only a few minutes.