Researchers in Arizona have just released a new study that stresses the need for CPR when a person collapses in sudden cardiac arrest — and it emphasizes the telltale sign of a patient's gasps for breath.

Bystanders often mistake gasping — such as snoring sounds, gurgling or noisy breathing — as respiration and think they don't need to call 911 and start CPR, says study co-author Dr. Gordon Ewy, chief of cardiology at the University of Arizona.

But researchers wanted to know how often gasping occurs and if its presence affects sudden cardiac arrest survival rates.

The authors of the study, to be published in Circulation: The Journal of the American Heart Association, reviewed more than 1,200 reports on cardiac arrest patients in the Phoenix Fire Department system between July 2004 and the end of 2007.

They also looked at text messages sent in January 2008 from the city's 911 center, which recorded information about gasping given to 911 dispatchers when someone collapsed.

The study found that among 481 people who collapsed and received bystander CPR, 39 percent of the gaspers survived but only 9.4 percent of those who didn't gasp survived.

Among the 737 in the study who did not receive bystander CPR, 21.1 percent of the gaspers survived, but just 6.7 percent of those who didn't display any kind of gasping respiration.

Ewy said the gasping sign emerged as being extremely important and indicates a high chance of survival. But the odds of it occurring decreased the longer it took for emergency medical services to arrive

"We need people to recognize sudden cardiac arrest, to call 911 and to start pressing on the chest," he said in a press release.

The study was funded in part by a grant from the Arizona Department of Health Services Bureau of Emergency Medical Services.

People who see an unresponsive adult who has collapsed should call 911 and begin CPR. The American Heart Association recommend hands-only CPR for anyone unsure of their skills, or unwilling or unable to provide ventilations while doing compressions.

For more information, check the Web links for the American Heart Association.