A massive Arizona campaign to get bystanders to do hands-only CPR if they see someone collapse appears to have paid off, state officials said on Tuesday.

Doctors have traditionally recommended mouth-to-mouth rescue breathing in addition to chest compressions during cardiopulmonary resuscitation (CPR), but recent studies suggest that doesn't help most patients.

Five years after Arizona started promoting hands-only CPR, the chances of surviving a cardiac arrest have more than doubled, according to a new report in the Journal of the American Medical Association.

I am really optimistic that this is going to help move the needle on bystander CPR across the country, said Dr. Bentley J. Bobrow, medical director of Arizona's Bureau of Emergency Medical Services & Trauma System in Phoenix, who worked on the study.

He said the statewide campaign, called SHARE, was launched to help turn the tide on the state's drab survival statistics for cardiac arrest, which kills more than 250,000 Americans every year.

We knew we had to do something to motivate the public to act when they saw someone collapse, Bobrow said, adding that only about a third of people who suffer cardiac arrest in the U.S. receive bystander CPR.

What we're trying to do is take away all the excuses that people have for not getting involved, like fear of causing harm and reluctance to make mouth-to-mouth contact.

The researchers analyzed data from 4,415 cardiac arrests that happened between 2005 and 2009 in Arizona. Over that period, survival to hospital discharge rose from less than four in 100 to nearly one in 10.

At the same time, the rate of CPR increased from about 28 percent to 40 percent, with a steep increase in chest compressions and a drop in rescue breathing.

Although many other aspects of medical care changed as well, hands-only CPR was linked to an increase in survival odds of 1.6 compared to both no CPR and standard CPR with rescue breathing -- even after accounting for other factors.

I'm excited about the results, said Dr. Michael Sayre, a spokesperson for the American Heart Association, which has recommended hands-only CPR since 2008.

They show that simplifying the instructions for CPR and informing the public can help save lives.

Sayre, also of Ohio State University in Columbus, said several 2010 studies have shown hands-only CPR is at least as good as standard CPR when people suffer cardiac arrest due to heart problems. (See Reuters Health story of July 28, 2010.)

When the heart stops for other reasons -- drowning, for instance -- rescue breathing may still serve a purpose, because in those cases the blood is usually out of oxygen. The same appears to be true for kids.

But for the majority of American adults with cardiac death, the heart gives in suddenly because the arteries that supply it with blood get clogged by cholesterol.

For those people, keeping the blood flowing without interruption appears to be vital.

This study shows that giving hands-only CPR is the right thing to do, Sayre told Reuters Health.

In an editorial accompanying the new report, Dr. David C. Cone of Yale University School of Medicine in New Haven, Connecticut, notes that hands-only CPR didn't appear to protect the brain better than standard CPR.

While some may think this is discouraging, he writes, others may be encouraged that skipping rescue breathing didn't have a negative effect on the brain.

Bobrow said good CPR is only one of many components needed to increase survival chances after cardiac arrest, which have been remained below 10 percent nationally over the past three decades.

In addition, he called for public-access defibrillators, which can jolt the heart back to its normal rhythm, and better hospital care.

I don't see any reason why in the future you wouldn't have a better chance of surviving than dying of a cardiac arrest, he said. We are just at the very, very tip of the iceberg.

Both the Arizona Department of Health Services and the American Heart Association have created short web tutorials that show how to do effective CPR (www.azshare.gov/ and handsonlycpr.org/).

And it's not hard to do, said Bobrow.

If someone suddenly collapses and is gasping, you need to call 911 and start pushing hard and fast on the chest, 100 times a minute, he told Reuters Health. Anyone can be a life-saver.