Saturday, July 31, 2010

Chest compressions only is at least as good as CPR with both compressions and mouth-to-mouth ventilations

July 28, 2010 (Boston, Massachusetts) — Two prospective randomized trials appearing in the July 29, 2010 issue of the New England Journal of Medicine should add heft to recent recommendations--based largely on observational data--that performing cardiopulmonary resuscitation (CPR) using chest compressions only is at least as good as CPR with both compressions and mouth-to-mouth ventilations [1,2].

In one study, by Dr Leif Svensson (Karolinska Institutet, SoƄndersjukhuset, Sweden) and colleagues, medical dispatchers all across Sweden who were contacted by people who'd witnessed out-of-hospital cardiac arrests randomly assigned callers to provide either compression-only CPR or standard CPR (with pauses in compressions to perform ventilation). They report that, among 1276 patients who received CPR over a four-year period, rates of 30-day survival were similar between the two CPR groups: 8.7% in the compression-only group and 7.0% in the standard CPR group (p=0.29).

"Overall, this [nationwide] study lends further support to the hypothesis that compression-only CPR, which is easier to learn and to perform, should be considered the preferred method for CPR performed by bystanders in patients with cardiac arrest," Svensson et al concluded.

In the second study, known as DART, Dr Thomas D Rea (University of Washington, Seattle) and colleagues employed a similar trial design, with dispatchers "randomizing" their instructions to callers seeking help for someone who'd experienced an apparent cardiac arrest. Two regions in Washington State and the city of London, UK, participated in the study.

In all, 1941 patients in DART were randomized equally to chest compressions only or to compressions plus rescue breathing, and here again, no differences were seen in patients who survived to hospital discharge--12.5% and 11%, respectively (p=0.31)--or in rates of patients with favorable neurologic outcomes.

Of note, Rea et al continue, patients with a cardiac cause of arrest and those with shockable arrhythmias (both prespecified subgroups) both showed trends toward higher hospital-discharge survival rates if they'd received chest compressions only.

"These results support a strategy for CPR performed by laypersons that emphasizes chest compression and minimizes the role of rescue breathing," Rea et al conclude.

Hands-On, Mouth-Off

Indeed, that approach is already advocated by the American Heart Association (AHA), which issued its "call to action" for "hands-only" CPR back in 2008 [3], as Dr Myron L Weisfeldt (Johns Hopkins Medicine, Baltimore, MD) points out in an editorial accompanying the two Journal papers [4]. Weisfeldt notes that a "straightforward message" from these papers is that advocating compression-only CPR should increase the likelihood that bystanders will attempt resuscitation, since "performance of mouth-to-mouth rescue breathing is far more difficult than proper chest compression, and . . . may be viewed with distaste and raise concerns about risks associated with mouth-to-mouth contact."

Commenting on all of the papers, Dr Michael Sayre (Ohio State University, Columbus), lead author on the 2008 AHA recommendations, told heartwire that the two new studies "reinforce what we're already saying and provide randomized clinical-trial evidence that what we recommended in 2008 is reasonable."

But he also emphasized the "two levels" to the question of whether or not rescue breathing is warranted. The first speaks to the fact that only one-quarter to one-third of cardiac-arrest victims get any form of resuscitation before emergency medical services (EMS) arrive.

"So the first question is, What do you want bystanders to do? And in that case, simple is clearly best. It might not be physiologically optimal for some victims, but the problem is that we need people to do something. That's more psychology than medicine."

But once EMS arrive, "we have choices," Sayre continued, and this is where resuscitation research still is hunting for answers. Echoing points also made by Weisfeldt in his editorial, Sayre notes that there may be groups in whom rescue breathing is desirable--drowning victims being one obvious example--and other patients in whom breathing could actually be detrimental.

"That's one possibility suggested by the studies we've just read today," Sayre points out. "Both of them show a trend toward improved outcome in the compression-only group. I haven't done the math to see whether, if you lump them together, that trend reaches statistical significance, but it's an interesting idea."

Keep in mind, he adds, that these are untrained laypeople. The difference between compression only and standard CPR may have been greater if trained professionals had been performing the two forms of CPR. At present, however, there are no good ways for a layperson to determine in the field, and particularly "over the telephone," whether any given patient might benefit from breathing or be harmed by it.

Missed Opportunities

As an aside, Sayre stressed that he thinks physicians have not really heard the message about compression-only CPR or realized that this simpler technique means family members might be more likely to save the life of a loved one with known heart disease.

"I'm not sure we really do a good job of recommending that our patients or families get trained, even with our own families," Sayre told heartwire . "I made sure my parents learned, but I suspect many physicians may not do that."

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