When a heart attack victim gasps for air, bystanders often take it as a sign that they do not need to start giving CPR. But a new study reports that the people who gasp are more likely to survive — especially if they are given chest compressions right away.

Writing in the December 9 issue of Circulation, researchers said health professions needed to do a better job of educating people about the significance of gasping. The study was led by Dr. Bentley J. Bobrow of the Mayo Clinic in Arizona.

There has been some debate about the likelihood of gasping in heart attacks and what it means. Some bystanders who know how to do cardiopulmonary resuscitation do not do so because they do not associate gasping with a heart attack, the study says.

Others realize a heart attack has taken place but think that the gasping means there is no need to begin resuscitation right away. Even emergency medical workers make these mistakes, the study said.

But when the researchers reviewed 1,200 cardiac arrest cases that occurred outside the hospital, they found that the patients were gasping about a third of the time. And as the minutes went by, the gasping went away, as did the chances of saving the patient.

The study found that among those patients given CPR, the survival rate was 39 percent for those who gasped. For those who did not gasp, it was 9 percent. Gaspers did better than nongaspers even when CPR was not given.