Cardiopulmonary resuscitation (CPR) was developed over 50 years ago as a rapid intervention in patients with cardiac or respiratory arrest. The combination of both external chest compressions and mouth-to-mouth rescue breathing is intended to maintain oxygenation of the brain and the heart. Since its inception, CPR has undergone only minimal revision in method. Decades of observational studies have reinforced the idea that survival rates are better when bystanders initiate CPR instead of waiting for emergency medical services (EMS) staff to arrive on scene. More recently, however, the use of rescue breathing as part of CPR delivered by bystanders has been the subject of some controversy. Some critics have argued that continuous chest compressions yield better outcomes than chest compressions interrupted by attempts at ventilation.
This week, The New England Journal of Medicine (NEJM) publishes reports of two randomized trials that compared standard CPR with the use of continuous chest compressions alone. In the multicenter, randomized trial conducted by Rea et al., there was no difference in survival to hospital discharge between those who received both chest compressions and rescue breathing and those who received chest compressions alone. In fact, in one key clinical subgroup –patients with a cardiac cause of arrest –chest compressions alone yielded a higher survival rate than chest compressions plus rescue breathing (15.5% versus 12.3%). The authors suggest that their results support a strategy for CPR that emphasizes chest compression and minimizes the role of rescue breathing.
The second randomized study, conducted in Sweden by Svensson et al., compared the two CPR methods with respect to the primary outcome of 30-day survival. This national trial found no significant difference in either 1-day or 30-day survival rates associated with the two methods or in survival rates among various subgroups. The authors propose that instructing bystanders who witness a cardiac arrest to perform compression-only CPR produces outcomes similar to those resulting from standard CPR. Given that compression-only CPR is easier to learn and perform, however, the authors further suggest that compression-only CPR “should be considered the preferred method for CPR performed by bystanders in patients with cardiac arrest.”
Many other considerations influence how desirable the two methods are in practice. In an accompanying editorial, Dr. Myron Weisfeldt of Johns Hopkins University School of Medicine wrote, “Performance of mouth-to-mouth rescue breathing is far more difficult than proper chest compression, and rescue breathing may be viewed with distaste and raise concerns about risks associated with mouth-to-mouth contact.” Additionally, he notes that given the inability of many bystanders to successfully perform rescue breathing, interrupting chest compressions to attempt ventilation may succeed “solely in diminishing coronary flow.” In many cases, then, the choice between compressions alone and compressions with rescue breathing may be effectively a choice between continuous and interrupted chest compressions.
NEJM’s Executive Editor Dr. Gregory Curfman said, “These two clinical trials are likely to influence recommendations on the application of compression-only CPR for cardiac arrest in the community.”
Given the findings of these trials, how do you think CPR instructions for bystanders should be revised?