Largest study of in-hospital cardiac arrest suggests how to improve outcomes for children and adults

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Researchers from the National Registry of CPR have released a study that challenges conventional medical wisdom about the patterns and causes of these life-threatening events. "Not all cardiac arrests are the same," said study leader Vinay Nadkarni, M.D., a specialist in Critical Care Medicine at The Children's Hospital of Philadelphia. "Our results suggest that hospital caregivers need to carefully tailor their resuscitations to a patient's situation, and not follow a blanket protocol based only on the patient's age."

The research appears in the January 4 issue of the Journal of the American Medical Association. The American Heart Association's National Registry of Cardiopulmonary Resuscitation (NRCPR) collected data from 253 hospitals in the United States and Canada between 2000 and 2004. The NRCPR investigators analyzed details of nearly 37,000 adults and 880 children who had pulseless cardiac arrests in the hospital. Their work provides a broad descriptive picture of how cardiac arrests occur and are treated.

The researchers found that cardiac arrests within a hospital are quite different from those occurring outside the hospital. "For both children and adults, most in-hospital cardiac arrests are caused by progressive respiratory failure and shock, not by a sudden arrhythmia," said Dr. Nadkarni. "Many adult physicians assume that the vast majority of adult cardiac arrests in hospitals are from sudden arrhythmias, and life-support protocols reflect this assumption. Our findings show that respiratory failure is more common than arrhythmia in adults, and in such cases emergency procedures should focus on breathing problems."

Arrhythmia is an abnormal heart rhythm that can halt the flow of blood from the heart. Just as some physicians incorrectly assume arrhythmia causes most adult cardiac arrests, they often believe sudden arrhythmias to be extremely rare among children suffering cardiac arrest. However, the researchers found that, at some time during their cardiac arrest, 26 percent of the children had arrhythmias, which were potentially treatable when correctly identified. "There are a significant number of cases in which children with pulseless cardiac arrest have shockable arrhythmias, and these should be addressed with cardiac, not respiratory, interventions," said Dr. Nadkarni.

The results send a hopeful message. With appropriate interventions, more than 27 percent of the children and more than 18 percent of the adults who had pulseless cardiac arrest survived to hospital discharge, mostly with good neurological outcomes. "These survival rates are much better than those occurring in cardiac arrests outside of hospitals," said Dr. Nadkarni. "This suggests that CPR may currently succeed more often than physicians commonly believe."

The American Heart Association (AHA) recently issued new guidelines for CPR and emergency cardiovascular care, based partly on the research described in this study. The National Registry of CPR was previously developed by the AHA to compile such data.

The 11 co-authors, writing for the National Registry of CPR Investigators, were from nine hospitals and research institutions, and represented the research committee of the Registry's Scientific Advisory Board, chaired by senior author Robert A. Berg, M.D., of the Sarver Heart Center at the University of Arizona. "This national registry will allow us to track possible improvements in patient outcomes stemming from the new guidelines, and should help us to refine future revisions to AHA guidelines," said Dr. Berg.

By better understanding ways in which children with in-hospital cardiac arrest may sometimes resemble and sometimes differ from adults, practitioners may be able to better refine emergency cardiovascular care and develop treatment procedures that improve outcomes for all patients, Dr. Nadkarni said. "This national registry defines the current landscape of in-hospital cardiac arrests in North America, and supplies evidence that should help in designing and implementing more effective interventions in the future," he added.

Children's Hospital of Philadelphia