In recent years resuscitation guidelines have evolved to emphasize chest compressions. At the same time, a greater proportion of out-of-hospital cardiac arrest (OHCA) cases are now due to “nonshockable” rhythms, defined as asystole and pulseless electrical activity, but the effect of the new guidelines on these type of OHCA cases is unknown.
In a study published in Circulation, Peter J. Kudenchuk and colleagues report on more than 10 years of experience treating nearly 4,000 out-of-hospital patients with unshakable OHCA treated in King County, Washington. Midway through the study period the new AHA guidelines came into effect. Overall, outcomes were poor in both groups, but several important measures were significantly improved during the second half of the study:
- 1-year survival: 2.7% in the first half versus 4.9% in the second half (adjusted hazard ratio: 1.85, CI 1.29-2.66)
- Return of spontaneous circulation: 27% versus 34% (HR 1.50, CI 1.29–1.74)
- Discharged from hospital: 4.6%) versus 6.8% (HR 1.53, CI 1.14–2.05)
- Favorable neurological outcome: 3.4% versus 5.1 (HR 1.56, CI 1.11–2.18)
“By any measure — such as the return of pulse and circulation or improved brain recovery — we found that implementing the new guidelines in these patients resulted in better outcomes from cardiac arrest,” said Kudenchuk, in an AHA press release. He calculated that 2,500 lives could be saved each year in North America by fully implementing the new guidelines.
Here is the press release from the AHA:
Guidelines-based CPR saves more non-shockable cardiac arrest victims
- CPR can save someone with cardiac arrest even if they don’t respond to a defibrillator.
- People with non-shockable cardiac arrest are more likely to live if they receive CPR based on recent guidelines emphasizing chest compressions.
- The American Heart Association’s CPR guidelines emphasizing chest compressions are saving more lives, according to a new study.
DALLAS, April 2, 2012 — People who have a cardiac arrest that can’t be helped by a defibrillator shock are more likely to survive if given CPR
based on updated guidelines that emphasize chest compressions, according to research reported in the American Heart Association journal, Circulation
“By any measure — such as the return of pulse and circulation or improved brain recovery — we found that implementing the new guidelines in these patients resulted in better outcomes from cardiac arrest,” said Peter J. Kudenchuk, M.D., lead author of the study and professor of medicine at the University of Washington in Seattle, Wash.
The American Heart Association changed its CPR guidelines in 2005 to recommend more chest compressions with fewer interruptions. The emphasis on chest compressions continued in the 2010 guidelines update
After the 2005 guidelines, several studies showed improved survival from shockable cardiac arrest.
However, new evidence shows that most cardiac arrests — nearly 75 percent — are due to conditions that don’t respond to shocks. In such patients there have been few, if any, life-saving treatments and it was uncertain whether CPR guidelines changes were beneficial.
“Now, for the first time, we have seen a treatment that improves survival specifically in these patients,” Kudenchuk said. “And that treatment is simply providing the more intense, quality CPR recommended in the new guidelines. You could save 2,500 more lives each year in North America alone by implementing these changes.”
Researchers identified 3,960 patients in King County, Wash., who suffered a type of cardiac arrest that doesn’t respond to shock from a defibrillator, known as non-shockable cardiac arrest.
They compared survival rates among patients who had non-shockable cardiac arrests from 2000-2004 — before the 2005 guidelines changes — to those who had non-shockable arrests from 2005-2010 and found:
- The likelihood of survival to discharge from the hospital improved from 4.6 percent before to 6.8 percent after the new guideline changes.
- The proportion of patients who survived with good brain function increased from 3.4 percent to 5.1 percent between study periods.
- One-year survival almost doubled from 2.7 percent to 4.9 percent.
Although survival in patients with non-shockable cardiac arrest is low, the important message from this study is that it can be improved. Potentially thousands of lives could be saved each year in this group if CPR guidelines are properly implemented, said Kudenchuk.
Further research is needed to find better treatments for cardiac arrest
and to verify these study results. Researchers continue to study new approaches to resuscitation through clinical trials, such as those currently being conducted by the Resuscitation Outcomes Consortium, which is supported by the American Heart Association; the National Heart, Lung, and Blood Institute; and the Canadian Institutes of Health Research.
Co-authors are Jeffrey D. Redshaw, B.S.; Benjamin A. Stubbs, M.P.H.; Carol E.
Fahrenbruch, M.S.P.H.; Florence Dumas, M.D.; Randi Phelps, B.S.; Jennifer Blackwood; Thomas D. Rea, M.D., M.P.H.; and Mickey S. Eisenberg, M.D., Ph.D. Author disclosures are on the manuscript.
The Laerdal Foundation provided research funding to the King County emergency responder system, but this study was not directly supported by any sponsor.