In a comparison of outcomes in Arizona for out-of-hospital cardiopulmonary resuscitation (CPR) for cardiac arrest performed by bystanders, patients who received compression-only CPR were more likely to survive to hospital discharge than patients who received conventional CPR, which includes rescue breathing, or no CPR, according to a study in the Oct. 6 issue of Journal of the American Medical Association.
Although survival rates for out-of-hospital cardiac arrest (OHCA) vary considerably, outcomes can be improved with bystander CPR, according to Bentley J. Bobrow, MD, of the Arizona Department of Health Services in Phoenix, and colleagues.
In 2005, Arizona established a statewide program aimed at improving survival. "These efforts included changes in the approach to the care provided by both bystanders and EMS personnel and were based on the increasing evidence in favor of minimizing interruptions in chest compressions during CPR," the authors wrote.
A multifaceted effort was launched to encourage bystanders to use compression-only CPR because this approach is easier to teach, learn, remember and perform than conventional CPR with rescue breathing, according to the study.
Bobrow and colleagues conducted a five-year prospective observational cohort study of 4,415 adults with OHCA between between January 2005 and December 2009 in Arizona. The patient population included 2,900 who received no bystander CPR (reference group), 666 who received conventional CPR and 849 who received compression-only CPR.
The researchers found that rates of survival to hospital discharge were 5.2 percent for the no bystander CPR group, 7.8 percent for conventional CPR and 13.3 percent for compression-only CPR.
The annual rate for lay rescuers providing any type of bystander CPR increased significantly over time, from 28.2 percent in 2005 to 39.9 percent in 2009.
"Among patients who received bystander CPR, the proportion with compression-only CPR increased significantly over time, from 19.6 percent in 2005 to 75.9 percent in 2009. Overall survival also increased significantly over time: from 3.7 percent in 2005 to 9.8 percent in 2009," according to the study.
Further analysis indicated that compression-only CPR was associated with an approximately 60 percent improved odds of survival compared with no bystander CPR or conventional CPR.
For the 1,017 OHCA that were witnessed by a lay bystander and had a shockable rhythm on EMS arrival, survival was 17.6 percent in the no CPR group, 17.7 percent for conventional CPR and 33.7 percent for compression-only CPR.
Of those that survived with good neurologic status, 3 percent had no CPR, 5.2 percent had conventional CPR and 7.6 percent had compression-only CPR. The difference between the latter two was not significant.
"This finding may be interpreted as discouraging," wrote David C. Cone, MD, from the department of emergency medicine at Yale University School of Medicine in New Haven, Conn., in an accompanying JAMA editorial. "The findings also may be interpreted as reassuring that the compression-only CPR intervention was not associated with an increased incidence of neurologically impaired survival, as has been suggested with some other cardiac arrest interventions, such as high-dose epinephrine," he added.
Bobrow and colleagues concluded, "This study is the first of which we are aware to report an intentional effort to encourage and endorse compression-only CPR to the public ... and the relationship between that "education effort and an increase in the rate of bystander CPR."
They noted that there are multiple reasons compression-only CPR may have advantages over conventional CPR techniques, including the rapid deterioration of forward blood flow that occurs during even brief disruptions of chest compressions, the long ramp-up time to return to adequate blood flow after resuming chest compressions, the complexity of conventional CPR, the significant time required to perform the breaths, and the critical importance of cerebral and coronary circulation during arrest.
In his commentary, Cone said that the AHA considers standard CPR and compression-only CPR equivalent. New guidelines due to be released this year, however, will likely deem compression-only CPR to be "at least equivalent to standard CPR, if not superior, for nonmedical bystanders."