Heart Health

21 December 2012

CPR: chest compressions best

People who suffer cardiac arrest were less likely to die in subsequent years when bystanders performed cardiopulmonary resuscitation using chest compressions only.

People who suffer cardiac arrest were less likely to die in subsequent years when bystanders performed cardiopulmonary resuscitation using chest compressions only, a new study found.

That builds on previous research that found no short-term survival differences in adult victims given compression-only CPR instead of the standard kind.

And it supports an American Heart Association recommendation that the simpler form of CPR is appropriate for bystanders, who may feel so intimidated by the prospect of combining chest compressions with rescue breathing that they give no aid at all.

This study shows "we were on the right track in 2008," said Dr Roger White, an anaesthesiologist at the Mayo Clinic who was on the advisory group that wrote the AHA's statement.

The recommendations don't apply to CPR performed in the hospital, nor in the community by medical personnel or people who are proficient in rescue breathing. They also apply only to adult, not paediatric, victims.

The study looked at data from two randomised trials that were published in the New England Journal of Medicine in 2010 and covered more than 3 200 adults whose cardiac arrests were likely due to heart problems rather than trauma, suffocating or drowning. Dispatchers instructed bystanders via phone to use either the standard or compression-only form of CPR.

The new study's authors, who were from Seattle, France and Sweden, were able to follow up on longer-term outcomes for 78% of those patients.

The one-year survival rate was about 12% for chest compression alone and about 10% for compression plus breathing, said Dr Florence Dumas, an author of the study. After adjustment, mortality in the compression-only group was 9% lower than in the standard CPR group. The survival benefit persisted over five years, according to findings published in Circulation.

What the study found

That suggests "that potential short-term outcome differences do translate to meaningful long-term public health benefits," said Dr Dumas.

In 2008 the AHA said compression-only CPR was an option for bystanders who aren't trained or who aren't confident in their ability to perform the compressions combined with rescue breathing.

Some people have worried that collapsed victims of non-cardiac events such as drug overdoses or a blood clot in the lungs might not get the oxygen they need with the compression-only approach, Dr White said.

But the study authors wrote that, "importantly, we did not observe evidence of harm among those for whom oxygenation and ventilation might in theory be more important" such as non-cardiac causes or an unwitnessed cardiac arrest.

There is likely some oxygen remaining in the blood when a victim's heart has stopped for a short period of time, and the compression-only technique can distribute it to vital organs. If a person has been down for a longer or unknown period of time, it's more likely that they'll need fresh oxygen through rescue breathing, said Dr White, who was not involved in the new study.

That's why the AHA's recommendations apply to witnessed cardiac arrests in adults with no obvious non-cardiac cause such as drowning. (Kids suffering cardiac arrest need rescue breathing.)

"The vast majority (of events) are likely to be cardiac in origin," said Dr White. "So proceeding with chest compression is likely to be beneficial in the vast majority of cases," he said.

One limitation of the study was that it tracked survival only; it couldn't assess patients' level of function or quality of life. In addition, the original trials the study drew from weren't designed to track long-term outcomes.

(Reuters Health, December 2012)

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