Major Finding: Survival rate after cardiac arrest was 12.5% with chest compression alone and 11.0% with chest compression plus rescue breathing in a U.S./British study; corresponding survival rates were 8.7% and 7.0% in a Swedish study.
Data Source: Two randomized, controlled trials with a total of 3,217 patients.
Disclosures: The Laerdal Foundation for Acute Medicine funded the U.S./British study. The Stockholm County Council, SOS Alarm, and the Swedish Heart-Lung Foundation funded the Swedish study.
Two independent, randomized, controlled trials found no statistically significant differences in survival between patients in cardiac arrest who are given standard cardiopulmonary resuscitation with chest compression and rescue breathing, compared with those given chest compression alone.
Both studies showed that, when performed by laypeople, CPR with compression alone was at least as effective as compressions plus rescue breathing, while being simpler to teach and perform.
In 2008, modifying previous CPR recommendations that had stood for decades, the American Heart Association introduced the concept of “hands-only CPR.” Citing numerous animal and human studies, the AHA announced that chest compressions alone were acceptable and potentially lifesaving when performed by people not trained in conventional CPR or those who are unable or unwilling to perform rescue breathing in addition to chest compressions.
The newly published randomized, controlled trials confirm and extend the conclusions of the earlier studies. In one of the new studies, dispatchers in London and in two counties in the state of Washington randomly delivered compression-only or standard CPR instructions to 911 callers (999 in London).
That study, led by Dr. Thomas D. Rea of the University of Washington, Seattle, eventually enrolled 1,941 patients, of whom 981 received chest compression alone and 960 received chest compression plus rescue breathing. Among those patients, 12.5% who received chest compression alone and 11.0% who received compression plus rescue breathing survived to hospital discharge. The difference was not statistically significant (N. Engl. J. Med. 2010;363:423-33).
The investigators, reasoning that the two techniques might have different neurologic consequences, also investigated the proportion of patients who survived with favorable neurologic status. No significant difference was seen on that measure either.
One difference between the two groups approached—but did not reach—statistical significance. Patients who had a cardiac cause of arrest were somewhat more likely to survive to discharge if they received compressions alone (15.5% vs. 12.3%, P = .09).
In the other new study, investigators randomized 1,276 patients who were the subjects of emergency calls to the 18 emergency medical dispatch centers in Sweden. At the direction of dispatchers, 620 received compression-only CPR and 656 received standard CPR. Dr. Leif Svensson of the Karolinska Institute, Stockholm, and his colleagues found that the rate of 30-day survival was 8.7% in the compression-only group and 7.0% in the group receiving standard CPR (N. Engl. J. Med. 2010;363:434-42).
Several planned subgroup analyses in that study also failed to reveal significant group differences. In particular, the survival rates did not differ significantly with age, with the interval between the call and the first emergency medical services response, or with the interval between the call and the first cardiac rhythm.
Citing earlier studies, the investigators wrote, “Complete occlusion of the airways does not reduce the chances of survival if reasonable circulation is provided by chest compression.”
My Take
With CPR, Less May Be Better
The straightforward conclusion from the primary analyses of these studies is that continuous chest compression without active ventilation, which is simpler to teach and perform, results in a survival rate similar to that with chest compression with rescue breathing. Equally straightforward is the message that advocating continuous chest compression without ventilation should increase the frequency of bystanders effectively performing CPR and therefore increase the chances of survival after cardiac arrest. One suggestion made by [the U.S./British researchers] deserves some attention: that mouth-to-mouth ventilation is performed so poorly by bystanders that this periodic interruption for “ventilation” succeeds solely in diminishing coronary flow. Nonetheless, CPR courses should teach rescue breathing, since it is important in cases of cardiac arrest from obvious respiratory failure, which include most cardiac arrests in children and some in adults.
Excerpted from an editorial by MYRON L. WEISFELDT, M.D., of Johns Hopkins Medicine, Baltimore (N. Engl. J. Med. 2010;363:481-3). He had no relevant conflicts of interest.