CPR

Cardiopulmonary resuscitation (CPR) is an emergency medical procedure for a victim of cardiac arrest or, in some circumstances, respiratory arrest. CPR is performed in hospitals, or in the community by laypersons or by emergency response professionals.

CPR involves physical interventions to create artificial circulation through rhythmic pressing on the patient's chest to manually pump blood through the heart, called chest compressions, and usually also involves the rescuer exhaling into the patient (or using a device to simulate this) to inflate the lungs and pass oxygen in to the blood, called artificial respiration. Some protocols now downplay the importance of the artifical respirations, and focus on the chest compressions only.

CPR is unlikely to restart the heart, but rather its purpose is to maintain a flow of oxygenated blood to the brain and the heart, thereby delaying tissue death and extending the brief window of opportunity for a successful resuscitation without permanent brain damage. Advanced life support and defibrillation, the administration of an electric shock to the heart, is usually needed for the heart to restart, and this only works for patients in certain heart rhythms, namely ventricular fibrillation or ventricular tachycardia, rather than the 'flat line' asystolic patient although CPR can help bring a patient in to a shockable rhythm.

CPR is generally continued, usually in the presence of advanced life support (such as from a medical team or paramedics), until the patient regains a heart beat (called "return of spontaneous circulation" or "ROSC") or is declared dead.

The medical term for the condition in which a person's heart has stopped is cardiac arrest (also referred to as cardiorespiratory arrest). CPR is used on patients in cardiac arrest in order to oxygenate the blood and maintain a cardiac output to keep vital organs alive.

Blood circulation and oxygenation are absolute requirements in transporting oxygen to the tissues. The brain may sustain damage after blood flow has been stopped for about four minutes and irreversible damage after about seven minutes. If blood flow ceases for 1 or 2 hours, the cells of the body die unless they get an adequately gradual bloodflow[citation needed], (provided by cooling and gradual warming, rarely, in nature [such as in a cold stream of water] or by an advanced medical team). Because of that CPR is generally only effective if performed within 7 minutes of the stoppage of blood flow. The heart also rapidly loses the ability to maintain a normal rhythm. Low body temperatures as sometimes seen in near-drownings prolong the time the brain survives. Following cardiac arrest, effective CPR enables enough oxygen to reach the brain to delay brain death, and allows the heart to remain responsive to defibrillation attempts.

If the patient still has a pulse, but is not breathing, this is called respiratory arrest and artificial respiration is more appropriate. However, since people often have difficulty detecting a pulse, CPR may be used in both cases, especially when taught as first aid.