It's important to note: that death is most likely to occur after 10 minutes of loss of oxygen to the brain. From 6 to 10 minutes brain damage is expected. From 4 to 6 minutes brain damage is very possible and from 0 to 4 minutes brain damage is virtually non-existent.
When the heart stops beating blood stops flowing throughout the body. Cardiopulmonary Resuscitation (CPR) is when a person performs chest compressions and breathing into a patient who has no pulse or who isn’t breathing. Chest compressions combined with breathing into the patient will carry the now oxygenated blood throughout the body and into the brain. CPR acts like an artificial heart moving the blood rich in oxygen into the brain.
If a patient receives CPR and/or an Automated External Defibrillator (AED) his/her chances of survival increases; and continues to increase if Emergency Medical Services (EMS) arrives within 10 minutes.
It is recommended for untrained rescuers to provide Compression-only CPR because it is easy for an operator (dispatcher) to provide guided instructions over the telephone. Remember, it is a priority to activate the Emergency Response System immediately and to provide chest compressions.