Overturning a century of conventional medical wisdom, Japanese researchers reported Thursday that simple chest compressions without mouth-to-mouth ventilation saves twice as many heart attack victims as traditional CPR.
The results could have important implications in emergency medicine because as many as three-quarters of bystanders who observe a heart attack in a stranger decline to perform CPR because they fear infectious diseases such as AIDS.
The report “should lead to a prompt revision of the 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.
The National Academies of Emergency Dispatch revised its guidelines last year to suggest that 911 operators instruct callers to perform cardiac compression.
“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 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.
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.
Fully 72 percent of the patients received no resuscitation at all from bystanders, 18 percent received conventional CPR and 11 percent 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 cardiac compression fared twice as well.
For patients with apnea – a cessation of breathing – 6.2 percent of those who received cardiac compression survived to the one-month mark compared with 3.1 percent who received CPR.
For those with a heart rhythm that could be shocked back to normal, 19.4 percent survived compared with 11.2 percent of the CPR group. And for patients for whom resuscitation began within four minutes, the percentages were 10.1 percent and 5.1 percent.
There was no subgroup that benefited from the addition of mouth-to-mouth respiration, they said.
The American Heart Association said in a statement Thursday that it supported the use of compression-only CPR “for anyone who is unwilling or unable to provide ventilations while providing chest compressions.”