CPR's Role in Rescue

CPR extends the window of opportunity to perform more elaborate first aid procedures. By itself, CPR cannot save the majority of victims of cardiopulmonary arrest. CPR only temporarily restores circulation to only 10 to 30 percent of what it would be with a healthy heart. Further, in about two-thirds of people in cardiopulmonary arrest, the heart goes into what's known as ventricular fibrillation. In this state, the heart muscle quivers rapidly, like a bowl of Jell-O™, and is unable to beat properly. CPR cannot stop ventricular fibrillation, and only about 4 percent of patients who receive CPR alone will survive an attack.

An implantable defibrillator developed by scientists at NASA

In order to restore a normal heartbeat, an electrical shock must be delivered to the heart. This is called defibrillation. The shock itself doesn't switch the heart back on - it's not like flipping a tripped circuit breaker. Instead, defibrillation actually stops the heart briefly! This gives the pacemaking cells a chance to re-establish a normal heartbeat.

So why do CPR at all if it can't address the root causes of cardiopulmonary arrest? The bottom line is that CPR is an important part of a comprehensive response to a cardiac emergency. Defibrillation requires special equipment that has to be brought to the patient, and CPR can keep a patient alive until a defibrillator arrives. When CPR is started within 4 minutes and defibrillation within 10 minutes of an attack, the survival rate skyrockets to 43 percent. Other factors that contribute to survival are:

• Rapid access to emergency care from paramedics and other medical professionals.

• Quick provision of other supportive medical care, such as epinephrine, a drug that stimulates the heart.