For 40 years, the prevailing wisdom for treating sudden cardiac arrest has been A-B-C (airway, breathing and compressions). That changed to C-A-B this month when the 2010 updated resuscitation guidelines from the American Heart Association (AHA) were published.
Since the guidelines were last updated in 2005, the momentum had begun to swing in the direction of chest compressions only, excluding ventilation, particularly for bystanders. Evidence has steadily mounted suggesting that uninterrupted compressions by laypersons is the best approach until the arrival of EMS personnel.
Even for trained professionals, the new guidelines suggest that chest compressions should begin immediately for those suffering an out-of-hospital cardiac arrest, while avoiding excessive ventilation.
The new guidelines also recommend the inclusion of therapeutic hypothermia as part of the overall cardiac arrest treatment regimen. In that regard, the National Heart, Lung and Blood Institute has initiated two trials to determine the efficacy of hypothermia in children who suffer cardiac arrest, whether in or out of the hospital.
Studies in adults have shown the benefit of hypothermia after cardiac arrest, as the therapy slows the brain's metabolic cascade started with the return of spontaneous circulation. While there are debates as to how and when to apply hypothermia, there is little question that the technique results in improved neurologic outcomes.
The revised resuscitation guidelines are another example of the dynamic approach to evidence-based medicine. As researchers gather data—whether observational or from randomized trials, those data continue to inform the evolving practice of medicine. Sometimes it might seem that the accumulation of data takes too long. But as in the case of the revised AHA guidelines, once those data are in, they present a solid foundation to move forward.
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C.P. Kaiser, Editor