Overturning a century of conventional medical wisdom, Japanese researchers reported Thursday that simple chest compressions without mouth-to-mouth ventilation save twice as many heart attack victims as traditional CPR.
The findings could have important implications in emergency medicine. As many as three-quarters of bystanders who observe a heart attack in a stranger decline to perform CPR, fearing infectious diseases.
The report “should lead to a prompt revision of the guidelines for out-of-hospital cardiac arrest,” Dr. Gordon A. Ewy of the University of Arizona College of Medicine wrote in an editorial accompanying the study, which was published in the medical journal Lancet.
The National Academies of Emergency Dispatch revised its guidelines in 2005 to suggest that 911 operators emphasize cardiac compression.
“Most people do better with compressions only,” said Dr. Paul E. Pepe, head 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 applied only to people who collapsed suddenly from a heart attack. Those suffering from respiratory arrest, including victims of drowning and drug overdoses, still require conventional CPR.
The compression-only approach 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 noted. That supply is usually enough to last seven or eight minutes, he said.
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 provides substantially more oxygen than mouth-to-mouth, he said.
“For people who are gasping, the body will take care of breathing for you, and it does a better job,” he said.
Dr. Ken Nagao of the Surugadai Nihon University Hospital in Tokyo and his colleagues studied 4,068 adult patients who had a heart attack in front of witnesses. Paramedics questioned bystanders about what happened in each case.
Seventy-two percent of the patients received no resuscitation from bystanders, 18% received conventional CPR and the rest received only cardiac compression. The study measured how many people were alive at one month with no mental impairment.
The death rate was high for all patients, but those who received only compressions fared twice as well.
For patients with apnea -- a cessation of breathing -- 6.2% of those who received only compressions survived to the one-month mark compared with 3.1% who had conventional CPR.
For those with a heart rhythm that could be shocked back to normal, 19.4% in the compression-only group survived compared with 11.2% of the CPR group. And for patients for whom resuscitation began within four minutes, the percentages were 10.1% and 5.1%.
There was no sub-group that benefited from the addition of mouth-to-mouth respiration, they said.
The American Heart Assn. said in a statement Thursday that it supported the compression-only approach “for anyone who is unwilling or unable to provide ventilations while providing chest compressions.”
“This study supports the concept of lay providers performing compression-only CPR in the first few minutes after witnessing an adult suddenly collapse,” the group said.