Cardiopulmonary resuscitation (CPR) is a lifesaving technique used for emergencies where a person's breathing or heartbeat has stopped. It involves chest compressions and rescue breathing to circulate oxygenated blood to vital organs until the heart can resume its natural rhythm. CPR is administered when a person is unconscious, not breathing, and has no pulse. Without continuous blood flow, the brain will begin to suffer damage within 4 minutes and may become irreparably damaged after 7 minutes. The procedure for CPR involves assessing the situation, calling for emergency services, clearing the airway, giving two rescue breaths, and then administering 30 chest compressions.