A leading expert in cardiopulmonary resuscitation says two new studies from U.S. and European researchers support the case for dropping mouth-to-mouth, or rescue breathing by bystanders and using "hands-only" chest compressions during the life-saving practice, better known as CPR.

The findings, the expert says, concur with the latest science advisory statement from the American Heart Association (AHA), published in 2008, recommending compression-only CPR by bystanders who are not adequately trained or who feel uncomfortable with performing rescue breathing on other adults who collapse from sudden cardiac arrest.

In an editorial accompanying the studies, to be published in the New England Journal of Medicine online July 29, cardiologist Myron "Mike" Weisfeldt, M.D., physician in chief at The Johns Hopkins Hospital and director of the Department of Medicine at Hopkins' School of Medicine, says "less may be better" in CPR, calling the findings straightforward, practical and potentially life-saving.

The two studies were conducted between 2004 and 2009 on more than 3,000 men and women who needed CPR. Among their key findings are that survival rates were similar for adults who received their CPR from bystanders randomly assigned to provide only chest compressions and those who were instructed to do standard CPR with rescue breathing. All bystanders involved in the studies were instructed by phone on which CPR method to use by 911 telephone dispatchers. One study showed survival rates after one month of 8.7 percent and 7 percent, respectively, while the other showed survival rates at time of hospital discharge of 12.5 percent and 11 percent. The researchers say the numbers were statistically the same.

"It is very important to understand that the patients in this study were adults and that for most children who suffer cardiac arrest, such as drowning victims, we must do rescue breathing," says Weisfeldt, a past president of the AHA (1989-1990).

He also notes that there are adults with breathing-related causes of sudden death where rescue breathing should be performed, including patients with sudden, acute heart failure, severe chronic lung disease, or acute asthma, and cardiac arrest.

However, says Weisfeldt, "for people who are not well trained or who are looking for a simple way to help save a life, chest compressions only, at least until the emergency care unit arrives, can be life saving, even without rescue breathing."

Weisfeldt says the studies' results could lead to stronger national guidelines on how bystanders should perform CPR. An update is expected to be announced in November in Chicago at an AHA annual meeting. Guidelines, he says, will likely recommend a steady 100 chest compressions per minute with less emphasis on rescue breathing.

Weisfeldt points out that both recent studies and previous animal studies had shown that hands-only CPR worked best for certain types of cardiac arrest, mostly instances resulting from an arrhythmia requiring defibrillation.

CPR has been in practice in the United States since 1960, when Johns Hopkins researchers William Kouwenhoven, Ph.D., Guy Knickerbocker, Ph.D., and James Jude, M.D., published the first data on the benefits of what was then called "cardiac massage."

Weisfeldt says further research is needed to see if a combination of CPR with rescue breathing is better at saving lives in certain kinds of cardiac arrest, and to see how and if the public can be trained to recognize and distinguish between types of heart attack.