Cardiopulmonary resuscitation (CPR) is a combination of rescue breathing and chest compressions delivered to victims thought to be in cardiac arrest. When cardiac arrest occurs, the heart stops pumping blood to the brain, heart, and body. However, CPR can support a small amount of blood flow throughout the body to “buy time” until normal heart function may be restored.

According to the American Heart Association, cardiac arrest occurs when there is a malfunction in the heart’s electrical system. These malfunctions are generally caused by abnormal heart rhythms, such as ventricular tachycardia or ventricular fibrillation. A victim in cardiac arrest requires a quick response with CPR and in some cases defibration. Defibrillation is the delivery of an electrical shock to the heart, in an attempt to return the heart to a normal rhythm. However, defibrillation is not effective for all forms of cardiac arrest.