<unk>  <unk>  is an emergency procedure consisting of chest compressions often combined with artificial ventilation in an effort to manually preserve intact brain function until further measures are taken to restore spontaneous blood circulation and breathing in a person who is in cardiac arrest. It is recommended in those who are unresponsive with no breathing or abnormal breathing, for example, agonal respirations.<unk>  involves chest compressions for adults between and deep and at a rate of at least 100 to 120 per minute. The rescuer may also provide artificial ventilation by either exhaling air into the subject's mouth or nose (mouth-to-mouth resuscitation) or using a device that pushes air into the subject's lungs (mechanical ventilation). Current recommendations place emphasis on early and high-quality chest compressions over artificial ventilation; a simplified<unk>  method involving only chest compressions is recommended for untrained rescuers. With children, however, 2015 American Heart Association guidelines indicate that doing only compressions may actually result in worse outcomes, because such problems in children normally arise from respiratory issues rather than from cardiac ones, given their young age. Chest compression to breathing ratios is set at 30 to 2 in adults.<unk>  alone is unlikely to restart the heart. Its main purpose is to restore partial flow of oxygenated blood to the brain and heart. The objective is to delay tissue death and to extend the brief window of opportunity for a successful resuscitation without permanent brain damage. Administration of an electric shock to the subject's heart, termed defibrillation, is usually needed in order to restore a viable, or "perfusing", heart rhythm. Defibrillation is effective only for certain heart rhythms, namely ventricular fibrillation or pulseless ventricular tachycardia, rather than asystole or pulseless electrical activity, which usually require the treatment of underlying conditions to restore cardiac function. Early shock, when appropriate, is recommended.<unk>  may succeed in inducing a heart rhythm that may be shockable. In general,<unk>  is continued until the person has a return of spontaneous circulation (ROSC) or is declared dead.Welsh Government training video of how to do a<unk>  on a person having a cardiac arrest Explanation about what is<unk>
Cardiopulmonary resuscitation
Extracorporeal cardiopulmonary resuscitation
Cardiopulmonary bypass
Extracorporeal membrane oxygenation
Rapid sequence induction
Mouth-to-mouth resuscitation
Resuscitation
Resuscitative thoracotomy