Posted on 11/04/2010

In the 2010 guidelines for cardiopulmonary resuscitation (CPR), the American Heart Association (AHA) made several important changes including calling for chest compressions first before attempting rescue breathing.

Evolving Guidelines

For 40 years, the AHA promoted the A-B-Cs of CPR: airway, breathing, compressions. Now, it says C-A-B is the way to go. The organization makes this change amid mounting evidence since 2005 that suggests chest compressions alone are at least equivalent, if not superior, to compressions plus rescue breathing.

In 2005, Arizona established a statewide program aimed at improving survival for out-of-hospital cardiac arrest (OHCA), which included changes in care provided by both bystanders and EMS personnel, and was based on the increasing evidence in favor of minimizing interruptions in chest compressions during CPR. Researchers analyzed data from more than 4,000 people suffering an OHCA to determine the impact of the program (JAMA 2010;304[13]:1447-1454). 

As Arizona’s multifaceted campaign progressed, so did the proportion of people performing compression-only CPR (19.6 percent in 2005 to 75.9 percent in 2009), as did the overall survival rate (3.7 percent in 2005 to 9.8 percent in 2009). Interestingly, compression-only CPR had the best survival rate at 13.3 percent, compared with 7.8 percent for conventional CPR (two ventilations alternating with 15 compressions) and 5.2 percent for the no-bystander CPR group. 

Of those who survived with good neurologic status, 3 percent did not receive CPR, 5.2 percent had conventional CPR and 7.6 percent had compression-only CPR, representing a significant difference. 

Lead author Bentley J. Bobrow, MD, a clinical associate professor in the emergency medicine department at Maricopa Medical Center in Phoenix, notes that this is the first report of its kind to show that an intentional effort that encouraged the public to perform compression-only CPR not only helped to increase the rate of bystander CPR, but also show a beneficial effect of compression-only CPR over conventional CPR. 

“The 2010 guidelines represent a significant change from previous guidelines based upon the evolving resuscitation research. The 2010 guidelines’ focus for lay rescuers is on identifying cardiac arrest and activating the emergency response system and initiating chest compressions immediately. The focus for healthcare professionals is on providing high-quality CPR with minimal interruptions and measuring this critical, lifesaving intervention,” says Bobrow. 

Of the Arizona program, Bobrow says it can be replicated by other communities across the U.S. “at a very modest cost per life saved. The challenges are not insurmountable, but require organization, commitment and a sustained effort over time.”

Accumulating Data  

Swedish researchers added to the evidence in July with their published efforts showing that compression-only CPR was equivalent to standard CPR for 30-day survival when bystanders were given instructions by emergency medical dispatchers (N Engl J Med 2010;363:434-42). More than 1,200 patients were involved in the randomized study.

Rescue breathing guidelines call for the two breaths to last only 1.5 to two seconds. Studies, however, have found durations of 16 seconds on average. “It is very difficult for a layperson to provide adequate ventilation,” says lead author Leif Svensson, MD, PhD, from the Karolinska Institute in Stockholm. He adds that his 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.” The AHA guideline team had cited some of Svensson’s early studies as being important toward their changes. 

What Type of Arrest?

Thomas D. Rea, MD, from the University of Washington in Seattle, and colleagues compared compression-only and standard CPR in a multi-center, randomized trial, and showed that both might have their place depending on the type of arrest (N Engl J Med 2010;363:423-433). 

The trial of dispatcher-instructed bystanders included nearly 2,000 patients. While there were no statistically significant differences in survival to hospital discharge or neurologic outcomes between those receiving compression-only and standard CPR, there was a trend toward higher survival rates with the compression-only approach for patients with a cardiac cause of arrest and for those with shockable rhythms. 

The researchers suggested a tailored approach, based on the type of arrest, would “theoretically result in 156 survivors with a favorable neurologic outcome per 1,000 patients if chest compression alone were used for all patients, compared with 115 per 1,000 if chest compression plus rescue breathing were used for all patients.” 

Rea, a member of the 2010 AHA guidelines committee, says, “All laypersons should perform chest compressions. The decision to add on rescue breathing is secondary, as most of the benefit has been achieved with chest compressions.” 

Timing of EMS Arrival

Another aspect of resuscitation under scrutiny is whether chest compressions or defibrillation should come first. The old guidelines emphasized the importance of early defibrillation for OHCA. The 2010 guidelines say that the evidence is not sufficient to recommend CPR first before defibrillation. If there are two or more rescuers, however, CPR should be performed while the AED is being readied.

Small clinical and preclinical studies have suggested the superiority of delivering chest compressions first before defibrillation. To help clarify the matter, Pascal Meier, MD, from the University of Michigan Medical Center in Ann Arbor, Mich., and colleagues analyzed all randomized controlled trials between 1950 and 2010, a total of 1,500 patients. They found no significant differences for survival or neurologic outcomes between the two approaches. However, long-term survival trended toward favoring chest compressions first.  

Interestingly, when EMS response time was greater than five minutes, the chest compression-first approach was more beneficial, and when EMS response time was less than five minutes, defibrillation first was more beneficial. These differences, however, were not statistically significant.

“The implications of this study are that chest compressions really matter and the new AHA CPR guidelines finally address the importance of chest compressions first,” says senior author Comilla Sasson, MD, from the University of Colorado in Denver. “Changing the new guidelines to C-A-B will hopefully reemphasize that circulating blood to the heart and brain are the first vital link in this process.”

SOURCE: Tri Med Media Group