"Chain of Survival” Saves Lives in Out-of-Hospital Cardiac Arrest Patients

Improvements to the "chain of survival” increased survival and decreased residual neurological damage in out-of-hospital cardiac arrest patients in Japan, according to a new study.

Researchers from Kyoto University (Japan) reviewed 8,782 bystander-witnessed cardiac arrests that occurred between May 1998 and December 2006 in Osaka (Japan). During this time period, more Japanese citizens received training in cardiopulmonary resuscitation (CPR), dispatcher instruction in CPR was introduced, and procedures were changed to allow emergency service personnel to deliver defibrillator shocks without online physician oversight and to intubate patients in the field.

As a result of these changes, the researchers found that one-month survival of witnessed cardiac arrests rose from 5% to 12%; the median time from collapse to CPR decreased from 9 to 7 minutes due to citizen training; bystander-initiated CPR increased from 19% percent to 36%; the neurologically intact one-month survival after witnessed ventricular fibrillation (VF) arrest increased from 6% to 17%; the median time from collapse to calling emergency services decreased from 4 to 2 minutes; the median time from collapse to first shock dropped from 19 to 9 minutes; and, while the median time to intubation remained at 25 minutes, it only took 15 minutes when trained paramedics were available. The researchers also found that for each minute of delay in starting CPR, the chance of neurologically intact survival decreased by 11%. For each minute of delay in shock treatment for ventricular fibrillation, the researchers found a 16% decrease in survival. Moreover, for every minute of delay in intubation, survival decreased by 4%. The study was published ahead of print on January 26, 2009, in Circulation, a journal of the American Heart Association (AHA).

"This study proves that improvement in the ‘chain of survival' results in increased survival from out-of-hospital cardiac arrest in the real world,” said lead author Taku Iwami, M.D., an assistant professor at the Kyoto University Health Service. "The improvement is mainly due to the improvement in the first three links of the chain, but there was some incremental benefit in the fourth link of advanced life support.”

In Osaka, a city with a population of 8.8 million people, about 120,000 citizens per year participate in conventional CPR training; there were no programs to train in compression-only CPR (according to the new AHA guidelines) during the study period.

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Kyoto University