Overturning a century of conventional medical wisdom, Japanese researchers have reported that simple chest compressions without mouth-to-mouth ventilation saves twice as many heart attack victims as traditional CPR.

The results can have important implications in emergency medicine. For as many as three-quarters of bystanders who observe a heart attack in a stranger decline to perform CPR because they fear infectious diseases.

The report “should lead to a prompt revision of guidelines for out-of-hospital cardiac arrest,” wrote Dr Gordon A Ewy of the University of Arizona College of Medicine in an editorial accompanying the study, which was published in the medical journal Lancet.

“Most people do better with compressions only,” said Dr Paul E Pepe, chair of the emergency medicine department at the University of Texas Southwestern Medical School, who wrote the guidelines for the dispatchers.

But experts cautioned that the new rules apply only to people who collapse suddenly from a heart attack. Those suffering from respiratory arrest, including victims of drowning and drug overdoses, still require the conventional cardiopulmonary resuscitation.

Compression-only CPR is effective for a variety of physiological reasons, Pepe said. “The main determinant of restoration of a spontaneous pulse is maintaining a high enough blood pressure in the heart,” he said. Halting compressions to provide ventilation reduces blood flow by an unexpectedly large amount.

The blood of a heart attack victim is fully oxygenated at the time of the attack and the body uses less oxygen in the aftermath of the attack, he said. That supply is usually enough to last seven or eight minutes. Moreover, most heart attack victims gasp for air every 15 to 20 seconds — a phenomenon known as agonal breathing or a “death rattle.” That gasping actually provides substantially more oxygen than mouth-to-mouth, he said.

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