WEDNESDAY, April 21, 2004 (HealthDayNews) -- The common practice of giving second, higher doses of adrenaline to restart the heart of a child who goes into cardiac arrest reduces the chance of survival, a new study finds.
"This is the first study done in a randomized, blind fashion, and it shows that a second, higher dose does not improve survival," said study author Dr. Robert A. Berg, a professor of pediatrics at the University of Arizona. "In the most common circumstance, it worsens the outcome."
While most laymen may think childhood cardiac arrest is a rare event, it happens often enough to warrant serious concern, Berg said. At least 2 percent of all cases of cardiac arrest occur in children, and the percentage is higher for hospitalized children, he said.
The American Heart Association has issued guidelines for resuscitation of those children for more than 20 years, and its experts will meet again next year to update those recommendations.
Injections of epinephrine -- the more formal name of adrenaline -- have played a central role in those guidelines, with the recommendations gradually being softened over the years.
In the early 1990s, a second, higher dose was recommended if a first dose was not effective, Berg said, but that stand has eroded as clinical evidence has shown that a higher second dose does not improve survival in adults who suffer cardiac arrest.
The latest guidelines say that if a first dose of epinephrine does not get the heart beating again, the patient can be given either another dose of the same amount or a higher dose.
Berg is a member of the committee that will issue the latest version of the guidelines, but he says he will recuse himself from the discussion because of his role in the new study.
That study, reported in the April 22 issue of the New England Journal of Medicine, included 68 hospitalized children who suffered cardiac arrest. Half of them were given a second, standard dose of epinephrine when the first one was ineffective. The other half got a larger second dose.
Only one of the 34 children who got the higher dose of adrenaline was alive after the first day, and that child did not survive to leave the hospital. But seven of the 34 who got a standard dose were alive after 24 hours, and four were safely discharged from the hospital.
Saving a child's life means a lot in terms of years, Berg said.
"A child who survives cardiac arrest will survive 10 times as long as an adult," he said. "If you say that 5 percent of cardiac arrests occur in children, the potential years of life that are saved is large."
The new study is valuable because it was done in children, said Dr. Jeffrey S. Fine, an assistant professor of pediatrics at New York University Medical Center, but, he added, "we already knew from studies in adults that it [higher epinephrine doses] didn't work."
While cardiac arrest is uncommon in children, two groups are most vulnerable, Fine said: those with severe respiratory problems, such as lung disease that can affect the heart valves, who are more likely to suffer cardiac arrest outside a hospital; and those with other kinds of serious illnesses, such as cancer or neurological problems.
The new study was done among hospitalized children, Fine noted. "They are monitored carefully and so have the best chance of survival," he said. "They provide the best way to test drugs."