New guidelines for reviving people whose hearts suddenly stop call for double the number of chest compressions patients should receive between pauses for mouth- to-mouth resuscitation.

Blood circulation for a person in cardiac arrest increases with each chest compression after a rescuer manually takes over the heart's rhythmic beat, according to guidelines posted online today by the American Heart Association in its journal Circulation. Stopping for mouth-to-mouth resuscitation halts the blood flow through the heart to the rest of the body. The momentum then must be built back up.

The guidelines should make cardiopulmonary resuscitation, or CPR, more effective and boost survival, doctors said. The association also urged using the same technique for adults, children and infants, which should make it easier to perform.

"The most common reason many people die from cardiac arrest is because no one nearby knew CPR, or if they did know it, they didn't actually do it," said Michael Sayre, emergency medicine physician at Ohio State University Medical Center in Columbus, who helped write the guidelines.

Improving and simplifying CPR training, and making it more accessible, will increase the chance of a bystander taking action, said Sayre in a conference call.

Success Rate

About 335,000 people die in the U.S. each year from cardiac arrest, when the heart suddenly stops working because of an electrical disturbance or other medical problem, according to the American Heart Association. CPR, the best way to treat patients until they can be shocked with a cardiac defibrillator, has an average success rate of less than 10 percent.

Studies published earlier this year found many bystanders and trained emergency medical technicians riding in ambulances perform CPR incorrectly. Chest compressions are often slow and shallow, and rescuers give too many resuscitating breaths per minute. Improving their technique may help more patients live.

"If there is a bystander who recognizes the emergency and is ready, willing and able to act, they can double or triple survival rates if they begin immediate CPR," said Mary Fran Hazinski, an assistant in surgery and pediatrics at Vanderbilt Children's Hospital in Nashville, Tennessee. Hazinksi conducted studies on CPR and defibrillator use for children and edited the revised guidelines.

More Compressions

A single rescuer should give 30 chest compressions, then two breaths to all adults, children and infants needing CPR, according to the new guidelines. That's double the 15 compressions for every two breaths recommended for adults in guidelines published in 2000. Children and infants previously received one breath for every five compressions.

"The more times someone pushes on the chest the better off the patient is because there is more blood flow to the heart, to the brain and to the other vital organs," said Sayre. "Push hard on the person's chest and push fast, allow the chest to recoil or relax completely and limit the number of times the compressions are stopped."

In all, 100 chest compressions should be given every minute. That figure hasn't changed from the past guidelines, said Sayre. Reducing the number of breaths given should help rescuers reach that target, he said. Under ideal circumstances, CPR can replace 20 percent of the heart's natural pumping capacity, he said.

The emphasis on chest compressions carries over to the use of automated external defibrillators, the devices now found in airports, schools and other public places to shock an erratically beating or stopped heart back to a normal rhythm.

Rescuers should start manual CPR immediately after a first shock from the defibrillator is given, the guidelines state. The previous guidelines said the cycle of checking and shocking the heart should be done three times before chest compressions are started.

Studies show that the first electrical shock to the heart stops the abnormal rhythm more than 85 percent of the time. Manually pushing oxygen-rich blood into the heart with the chest compressions increases the chances that the heart will resume beating normally on its own.