By LEE BOWMAN
Scripps Howard News Service
January 03, 2006
New insights into patient survival are coming from the findings of the largest study yet to track what happens when a person goes into cardiac arrest in a hospital and undergoes resuscitation.
"Not all cardiac arrests are the same," said the study's lead author, Dr. Vinay Nadkarni, a professor at the University of Pennsylvania School of Medicine and a critical-care specialist at 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."
During cardiac arrest, a person loses consciousness, stops normal breathing and loses pulse and blood pressure. Brain death and permanent death start to occur within four to six minutes of a heart stopping, and most efforts to resuscitate a victim fail if they're not started within 10 minutes. It's estimated that 95 percent of people who suffer cardiac arrest outside of a hospital die before reaching advanced medical care, but even making it to the hospital only slightly improves the odds of survival.
The new study is aimed at boosting survival odds in hospitals. Published in The Journal of the American Medical Association, it is based on information provided by 253 hospitals between 2000 and 2004.
Investigators, working as part of the scientific committee for the American Heart Association's National Registry of Cardiopulmonary Resuscitation, analyzed details from nearly 37,000 adults and 880 children who had pulseless cardiac arrests in the hospital. CPR (chest compressions) or defibrillators or both were used in attempts to revive them.
The same research was used, along with other data, to develop the Heart Association's new guidelines for CPR issued in December. They focused more on chest compressions and less on rescue breathing for first-responders and bystanders.
Overall, the results from the hospitals were encouraging, the researchers said. More than 18 percent of the adults and 27 percent of the children survived to be discharged from the hospital and the majority had no evident brain damage.
"These survival rates are much better than those occurring in cardiac arrests outside of hospitals," Nadkarni said. Earlier studies of CPR done outside the hospital have found survival rates ranging from as low as 2 percent and as high as 22 percent, while in-hospital survival rates have been reported from 10 percent to 18 percent.
"Our findings suggest that CPR may currently succeed more often than physicians commonly believe," Nadkarni said.
But the study also underscored differences and misunderstandings about why people typically go into cardiac arrest.
"Many physicians assume that the vast majority of adult cardiac arrests in hospitals are from sudden arrhythmias, and life-support protocols reflect this assumption," Nadkarni said. "Our findings show that progressive respiratory failure and shock 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, and often develops after part of the heart muscle has been damaged by a heart attack. But there are a number of other reasons that the heart can beat too slowly or too fast.
Many doctors don't expect arrhythmia to be a factor in children suffering from cardiac arrest and, as a result, often may not use defibrillators on youngsters. But the study found that at some time during their cardiac arrest, 26 percent of the children had arrhythmias. "There are a significant number of cases in which children (in arrest) have shockable arrhythmias, and these should be addressed with cardiac, not respiratory, interventions," Nadkarni said.
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