MONDAY, April 5, 2004 (HealthDayNews) -- Some people who suffer cardiac arrest may be dying because emergency medical personnel are trying too hard to get the blood flowing again, a study suggests.
When Dr. Tom P. Aufderheide and colleagues at the Medical College of Wisconsin in Milwaukee looked at how seven cardiac arrest patients were given cardiopulmonary resuscitation (CPR), they found that the ambulance crews were creating a ventilation rate of 37 breaths a minute, far above the 12-to-15-breath-a-minute pace recommended by the American Heart Association, says a report in the April 6 issue of the journal Circulation.
That too-fast rate might be one reason why survival rates for cardiac arrest patients remain "dismal," with only one of every 20 surviving, said Aufderheide, a professor of emergency medicine.
Although it was a small study in one city, it's possible the same thing is happening all over the country, he said. The only other study on the question, published in 1995, found that doctors and nurses giving CPR in a hospital had ventilation rates as high as 70 breaths a minute, Aufderheide said.
CPR includes mouth-to-mouth breathing and rhythmic compression of the chest to force blood out of the heart into the body. After each compression, the chest expands to create a slight vacuum that sucks blood back into the heart.
"Excessive ventilations decrease the amount of blood flowing in and out of the heart, and that significantly decreases the effectiveness of CPR," Aufderheide said.
Laboratory studies with animals after the field observations confirmed that excess compression rates decreased both blood flow and survival, he said.
He suggested that emergency personnel get special training to keep their compression rate within the recommended level. When Milwaukee personnel got such training, the compression rate for the next six cardiac arrest patients dropped significantly, to 22 breaths a minute -- but still above the advised rate.
Adding a light that flashes every five seconds could tell rescuers that they are being overzealous, Aufderheide said, adding, "We've already implemented such a device in our practice."
Emergency medical professionals tend to overdo ventilation because "until now, no adverse effects had been reported," Aufderheide said. "They feel that if some is good, more is better. This study demonstrates the exact opposite."
What is needed now is "better education of professional rescuers," he said.
"We ask that EMS [emergency medical services] doctors and others monitor ventilation rate during cardiac arrest and, if they note an excessive rate, take appropriate action," Aufderheide said.
Even though the number of patients studied was small, the new report "is potentially helpful in allowing us to understand the factors that lead to death outcomes in resuscitation efforts," said Dr. Sidney C. Smith, professor emeritus of medicine at the University of North Carolina, and a spokesman for the American Heart Association.
"It should contribute to future research in providing the best possible resuscitation for patients experiencing cardiopulmonary arrest," Smith said.
More information
You can get information about what CPR is, when it is needed, and how to learn the technique from the American Heart Association or the University of Washington.
