WEDNESDAY, Sept. 16, 2009 (HealthDay News) -- If you see someone collapse and suspect they are in the middle of cardiac arrest, push on that person's chest and keep on pushing -- the more pushes, the better.
That's the message of a study that finds that survival after cardiac arrest is directly related to the amount of time spent doing chest compressions during efforts at what is formally called cardiopulmonary resuscitation (CPR).
"This study helps consolidate our knowledge that patients in cardiac arrest need someone to act as a temporary artificial heart and push blood around," said Dr. Michael Sayre, an associate professor of emergency medicine at Ohio State University, and chairman of the American Heart Association Emergency Cardiovascular Care Committee.
The study, published online Sept. 14 in Circulation, used data on 506 attempts to save lives after cardiac arrest at emergency medical centers between 2005 and 2007. It found that survival was directly related to the percentage of CPR time spent doing chest compressions.
Heart function returned to normal in 58 percent of cases when that time was less than 20 percent. Normal function was restored in 79 percent of cases when the time spent in chest compressions was 81 percent or more, the researchers found.
Survival to hospital discharge was more strikingly related to chest compression time -- 12 percent when that time was 20 percent or less, and 25 percent when it was 81 percent or greater.
"It seems to me that two messages come out of this," Sayre said. "We need more compressions than many patients are actually getting. And quality improvement efforts in emergency medical centers can use this information to ensure that their personnel do a better job."
Interruptions of chest compressions are an unavoidable part of CPR, said Dr. Benjamin S. Abella, clinical research director of the University of Pennsylvania Center for Resuscitation Science and head of its department of emergency medicine.
"There are pauses for medications and to place lines," Abella said. "All those pauses contribute to poor outcomes. If caregivers in the field recognize that the central issue is compress, compress, compress, we can improve survival."
The amount of CPR time devoted to chest compressions has increased in recent years, the study noted. Before 2005, less than 50 percent of CPR time was spent on chest compressions. After the American Heart Association updated its guidelines that year to emphasize the importance of chest compressions, that percentage increased, with some emergency centers achieving a rate between 60 percent and 85 percent.
The quality of CPR is "a sum of the rate of chest compressions and the depth of compressions, and the message here is that we need more compressions," Abella said.
While no exact rate has been set, "we do believe that compressions at about 100 per minute and two inches of depth should be maintained while CPR is being delivered," he said.
How long should it be delivered? "Until a pulse is restored or it is deemed futile," Abella said.
Guidelines for cardiopulmonary resuscitation are described by the American Heart Association.