Hoping to save thousands of heart attack victims a year, the American Heart Association has endorsed the technique of rapidly cooling comatose patients whose hearts have been restarted so that they can be brought back to life slowly, suffering less brain damage.
Studies in Europe and Australia have shown that comatose patients whose bodies were cooled to between 89.6 and 93.2 degrees Fahrenheit and maintained at that temperature for up to 24 hours suffered significantly fewer deaths and less brain damage than patients who were quickly resuscitated, the association said.
"This is very exciting. There are potentially a lot of people who can benefit," said Dr. Terry L. Vanden Hoek, a professor of emergency medicine at the University of Chicago and a co-author of the heart association's endorsement, which was published Monday in Circulation, the journal of the association. "But it's just the tip of the iceberg. The hope is that we'll find better ways to cool people."
Some major teaching hospitals already put comatose cardiac arrest victims on ice, but many smaller ones do not. The association now recommends that all hospitals use it, a spokeswoman, Julie Del Barto, said. The guideline was based on the findings of an international expert panel, the International Liaison Committee on Resuscitation.
About 680 Americans a day who have heart attacks go into sudden cardiac arrest, in which the heart stops beating and begins to fibrillate _ quivering, in a common description, "like a bag of worms." Unless its rhythm is rapidly restored by a defibrillator, the patient's oxygen-starved brain will begin to die, the fate suffered by about 95 percent of those who suffer total cardiac arrest outside of hospitals.
A major public health campaign is under way to save some of those lives by mounting portable defibrillators in airliners, office buildings and other public places.
But after a few minutes without circulation, victims slip into comas. Then, even if the heart is restarted, they usually die anyway, or live with severe brain damage.
Doctors believe much of the damage to resuscitated patients is done when oxygenated blood rushes back into the brain, triggering inflammation. An explosion of free radicals from the wastes built up during oxygen deprivation kills many cells. Cold slows that process.
Many questions remain to be answered, including how to chill patients rapidly but safely, whether to start in the ambulance and how long patients should stay in the hibernation-like state of "therapeutic hypothermia."