Whether it's better for bystanders to be instructed by emergency dispatchers to perform only chest compressions or chest compressions with mouth-to-mouth resuscitation might depend on the type of arrest, according to a study in the July 29 issue of the New England Journal of Medicine.
Thomas D. Rea, MD, from the University of Washington in Seattle, and colleagues conducted a multicenter, randomized trial of dispatcher instructions to bystanders for performing cardiopulmonary resuscitation (CPR).
The 1,941 patients were 18 years of age or older with an out-of-hospital cardiac arrest for whom dispatchers initiated CPR instruction to bystanders. Patients were randomly assigned to receive chest compression alone (981) or chest compression plus rescue breathing (960). The primary outcome was survival to hospital discharge. Secondary outcomes included a favorable neurologic outcome at discharge.
Researchers observed no significant difference between the two groups in the proportion of patients who survived to hospital discharge (12.5 percent with chest compression alone and 11 percent with chest compression plus rescue breathing) or in the proportion who survived with a favorable neurologic outcome in the two sites that assessed this secondary outcome (14.4 vs. and 11.5 percent, respectively).
However, prespecified subgroup analyses showed a trend toward a higher proportion of patients surviving to hospital discharge with chest compression alone as compared with chest compression plus rescue breathing for patients with a cardiac cause of arrest (15.5 vs. 12.3 percent) and for those with shockable rhythms (31.9 vs. 25.7 percent).
"The results support a strategy for CPR performed by laypersons that emphasizes chest compression and minimizes the role of rescue breathing," Rea and colleagues concluded.
"I think 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," Rea said in an interview. "In general, a layperson should always perform chest compressions (alone) if they have not been trained or even if they have been trained in the past but still do not feel completely comfortable performing rescue breathing."
Researchers also observed a small difference in the proportion of patients with noncardiac causes of arrest or nonshockable rhythms who survived and who were given both chest compressions and rescue breathing. These two groups, who comprised 14 and 21 percent of survivors respectively, "cannot be dismissed as clinically unimportant," they said.
Perhaps a more targeted approach to rescue efforts based on the type of arrest would be more beneficial, they surmised.
"On the basis of data from the current study, such a tailored approach, if correctly applied according to the cause of arrest, would theoretically result in 156 survivors with a favorable neurologic outcome per 1000 patients, as compared with 144 per 1000 if chest compression alone were used for all patients or 115 per 1000 if chest compression plus rescue breathing were used for all patients," they wrote.
Researchers noted that the trial was designed to "acknowledge the heterogeneity of the arrest condition and the potential for disparate intervention effects across the arrest population, providing in turn the truest translation of the intervention effects to community-based care."