CPR keeps oxygenated blood flowing to the brain and other vital organs until appropriate medical treatment can restore a normal heart rhythm. CPR is only performed when a person is unconscious and is not moving or is not breathing normally. Position the person so you can check for breathing and a pulse by laying the victim flat on a firm surface and extending the neck. If you cannot leave the scene, have someone else call.
Chest compressions replace the heartbeat when it has stopped.
Compressions help maintain some blood flow to the brain, lungs and heart. You must perform rescue breathing anytime you perform chest compressions. Open the victim's mouth and airway by lifting the chin forward. Determine whether the victim is breathing by simultaneously listening for breath sounds, feeling for air motion on your cheek and ear and looking for chest motion. If the victim is not breathing, pinch his or her nostrils closed, make a seal around the mouth and breathe into his or her mouth twice.