AHA Cardiopulmonary Resuscitation Guidelines Revised

BY ROBERT FINN
Elsevier Global Medical News

The American Heart Association guidelines for cardiopulmonary rescusitation have been changed to advocate starting chest compressions before and perhaps without starting rescue breathing.

The AHA’s previous CPR guideline advised rescuers to clear the victim’s airway, breathe into the victim’s mouth, then start giving chest compressions. Modifying the CPR recommendations that had stood for more than 40 years, the new guidelines recommend that bystanders undertaking CPR focus on performing chest compressions, as any delay in chest compression increases the risk of death (Circulation 2010;122[suppl 3];S640-56).

The AHA guideline change comes after two independent, randomized, controlled trials, published this past summer, found no statistically significant differences in survival between patients in cardiac arrest who are given standard CPR with chest compression and rescue breathing, compared with those given chest compression alone.

The studies both concluded that when performed by laypeople, CPR with chest compression alone was at least as effective as compressions plus rescue breathing, while also being simpler to teach and to perform.

These randomized, controlled trials confirm and extend the conclusions of earlier studies. In one of the recent 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).

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 study, investigators randomized 1,276 patients who were the subjects of 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 subgroup analyses also failed to reveal significant group differences. The survival rates did not differ significantly with age, with the interval between the call and the first EMS response, or with the interval between the call and the first cardiac rhythm.

Dr. Svensson and his colleagues also pointed to studies showing that laypeople have difficulty providing adequate ventilation using rescue breaths. CPR guidelines call for the two rescue breaths to take 1.5-2 seconds/breath. But in one study, people not trained in CPR took 16 seconds on average to deliver the two breaths.

In addition, a new meta-analysis by Dr. Michael Hüpfl of the department of anesthesiology at the Medical University of Vienna and his colleagues pooled data from three randomized trials (the two previously described plus one other [N. Engl. J. Med. 2000;342:1546-53]). They found that chest compression–only CPR performed by bystanders under directions from a telephone dispatcher was associated with an improved chance of survival, compared with standard CPR performed by the same (14% vs. 12%) in adult patients experiencing cardiac arrest outside a hospital. The absolute increase in survival was 2.4%, with the relative chances of survival increased 22% by chest compression–only CPR (Lancet 2010 Oct. 15 [doi:10.1016/S0140- 6736(10)61454-7]).

In a secondary meta-analysis of seven observational cohort studies, the researchers saw no significant difference between the compression-only and standard CPR arms.

Compression-only CPR, the investigators concluded, should become the default instructions for dispatchers to give to bystanders. “The pooled effect size of about 22% might seem small, but rates of survival after out-of-hospital cardiac arrest have been about 4%-8% for the past few decades, so our result could represent important progress,” they wrote.

In the United Kingdom, compression-first CPR is already the standard recommendation for treating sudden adult cardiac arrest; guidelines since 2005 have reduced (but not eliminated) the recommended amount of mouth-to-mouth or mouth-to-nose ventilation. The Resuscitation Council UK, which makes CPR guidelines widely followed in the United Kingdom and the rest of Europe, has new guidelines for bystanders in the works that do away with the recommendation for rescue ventilation.

“If people have not been trained, they should be no doubt doing compression only,” said Dr. Jerry P. Nolan of the Royal United Hospital NHS Trust in Bath, England, and an author of existing Resuscitation Council guidelines. However, for trained professionals, standard CPR with ventilation remains preferable, he said. Compression-only CPR “works for only about the first 4 or 5 minutes. The whole thing comes down to what is ideal for the bystander’s level of training,” Dr. Nolan said.

The Washington/London study was funded by the Laerdal Foundation for Acute Medicine. Two investigators received defibrillators and funding from Philips Medical Systems and Physio-Control; their institutions received funding from the Medtronic Foundation. The Swedish study had funding from Stockholm County Council, SOS Alarm, and the Swedish Heart-Lung Foundation. The Vienna study received funding from the U.S. National Institutes of Health and the American Heart Association.

Michele G. Sullivan and Jennie Smith contributed to this report.