Cardiopulmonary resuscitation (CPR) is systematic therapy that is aimed at sustaining vital organ function until natural cardiac function can be restored.
In clinical practice, the severity of underlying cardiac disease is the major determining factor in the success or failure of CPR.
Brain adenosine triphosphate is depleted in 4 to 6 minutes of no blood flow. It returns nearly to normal within 6 minutes of starting effective CPR.
Factors associated with poor outcomes are a long arrest time before CPR is begun, prolonged ventricular fibrillation without definitive therapy, and inadequate coronary and cerebral perfusion during cardiac massage.
Optimum outcome from ventricular fibrillation is obtained only if basic life support is begun within 4 minutes of arrest and defibrillation is applied within 8 minutes.
Blood flow decreases rapidly with interruptions of chest compressions (checking the pulse, intubation, defibrillation attempts, starting intravenous [IV] lines) and resumes slowly with reinstitution of compressions, emphasizing the importance of continued chest compressions in overall outcome.