May 14, 2001 -- Hospital dramas like ER, Gideon's Crossing, and Chicago Hope do a lot to make viewers aware of what happens during an emergency situation. However, these shows may be contributing to unrealistic expectations of what cardiopulmonary resuscitation, commonly known as CPR, can do -- by inflating survival rates.

The truth is that only between 5%-10% of people who undergo CPR will survive, while on television shows, a majority of the patients seem to do well.

"A lot of patients we see in the emergency department and a lot of families that we interact with do not always have realistic ideas about the success rate associated with CPR," says Amal Mattu, MD, assistant professor of emergency medicine and co-director of the emergency medicine/internal medicine combined residency program at the University of Maryland School of Medicine in Baltimore. Mattu speaks regularly on this topic.

"Most people in the public and even nurses and physicians ... overestimate the success rate of CPR, and part of that is probably due to the way that CPR is depicted on television," says Mattu.

CPR involves the use of mouth-to-mouth breathing and chest compressions to facilitate the continued circulation of oxygenated blood throughout the body. It is performed when the breathing or the regular heartbeat has stopped -- for reasons such as electric shock, drowning, or severe trauma.

In sudden cardiac arrest, when the heart stops functioning properly, the heart goes from a normal heartbeat to a quivering rhythm called ventricular fibrillation, which is fatal unless an electric shock, called defibrillation, can be given.

Defibrillators are devices that deliver electric shocks when needed to correct abnormal heart rhythms through pads that are placed on the patient's chest.

CPR is really a stopgap measure that extends the window of survival until trained medical help arrives and advanced equipment can be used. It does not stop ventricular fibrillation but it extends the time in which defibrillation could be effective. Permanent damage to the brain can occur if oxygen flow is not restored within about five minutes, and with CPR, oxygen flow is maintained.