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For adults who have suffered a heart attack, the standard of care is to cool the body from 98 to 91 degrees Fahrenheit, called therapeutic hypothermia. The practice reduces brain and organ damage, and has been shown to improve the survival and health of patients. But the question has remained whether the therapy is effective in children. In adults, cardiac arrest is most commonly caused by heart disease, but in children it often results from trauma such as accidental drowning or strangulation.
Cardiac arrest in children is not as common as in adults, but remain a serious problem. More than 6,000 children suffer out-of-hospital cardiac arrest in the United States each year. In most cases the outcome is death, and in many, long-term disability.
A large-scale, multicenter study co-led by the University of Utah School of Medicine shows that emergency body cooling provides no benefit over actively maintaining normal body temperature in infants or children after cardiac arrest. Children treated by each of the two methods had equal rates of mortality and brain injury. The results were presented at the Pediatric Academic Societies Annual Meeting in San Diego and published simultaneously in the New England Journal of Medicine.
One interpretation of the results is that normalizing body temperature is as beneficial as cooling for these children. This would suggest that there is a protective characteristic that is shared by the two forms of therapeutic thermoregulation. Both prevent fevers - which commonly occurs after cardiac arrest and can lead to more severe outcomes - and do so better than medication. Future studies will rigorously test whether blocking fever is key to helping children recover.
"The findings from these studies may well lead to evidence-based guidelines that will improve the quality and rates of pediatric cardiac arrest survival by using better treatments," said co-principal investigator J. Michael Dean, M.D., M.B.A., professor of pediatrics and chief of the Division of Pediatric Critical Care Medicine at the University of Utah School of Medicine, Salt Lake City. "Our hope is to identify the most effective treatment for preventing neurological damage or death in infants and children who suffer cardiac arrest."
The results also call into question the premise behind therapeutic hypothermia as standard of care in adults with cardiac arrest. "Results of our study are consistent with the most recent publications examining the adult population, indicating that controlled normothermia is as effective as hypothermia," said Dean. Maintaining normal body temperature could be preferred over cooling because the latter increases risk for infection and pneumonia, and shivering must be controlled with neuromuscular blockers, which can lead to adverse side effects.
The current study included 295 participants between 2 days and 18 years old who were admitted to children's hospitals for cardiac arrest, required chest compressions for at least two minutes, and remained dependent on mechanical ventilation to breathe.
After their parents or guardians provided consent, children were randomly assigned to one of the two treatment groups. One group received body cooling for two days followed by three days of normal temperature control. The other group received normal temperature control for five days. To actively control body temperature, the children were surrounded by blankets infused with temperature-controlled water.
One year after treatment, approximately 30 percent of children survived, and 15 percent suffered little to no brain damage. There was no difference between the two treatment groups.
"Our results show that therapeutic hypothermia is no more effective for treating children after out-of-hospital cardiac arrest than maintaining body temperature within the normal range, " said co-principal investigator Frank W. Moler, M.D., M.S., a professor in the Department of Pediatrics and Communicable Diseases at the University of Michigan, Ann Arbor. "Both treatments help to control fever and inflammation, and they result in similar outcomes for patients."
The studies are part of the Therapeutic Hypothermia after Pediatric Cardiac Arrest (THAPCA) trials, an effort that is the largest examination of therapeutic hypothermia in children other than newborns for any health condition to date. The study is funded by the National Heart, Lung, and Blood Institute (NHLBI) of the National Institutes of Health.
The article, entitled "Therapeutic Hypothermia After Out-of-Hospital Pediatric Cardiac Arrest" was published online at NEJM on April 25, 2015 (http://www.nejm.org/).
More information about the THAPCA trials can be found on the Web at www.thapca.org.