Feb. 20, 2002 -- In cardiac arrest the heart stops beating, cutting off the blood supply to the body and brain. Even if a patient can be resuscitated, brain damage often results. But researchers report that lowering the body temperature of a newly-revived cardiac arrest patient can make a big difference.
It's called mild therapeutic hypothermia. It means using ice or a cooling device to drop a person's body temperature several degrees. It's an old idea that's coming back with new force, according to two studies and an editorial in the February 21 issue of The New England Journal of Medicine.
"We recommend the use of mild hypothermia in survivors of cardiac arrest -- as early as possible and for at least 12 hours," write editorialists Peter J. Safar, MD, and Patrick M. Kochanek, MD, of the University of Pittsburgh Medical Center.
Outcomes often are grim for people whose hearts stop outside the hospital. Those who can be resuscitated more often than not suffer major brain damage or die within the next few months. It's long been thought that chilling a person could help, but it's been hard to prove it. Now research teams in Europe and Australia offer compelling evidence that mild hypothermia can work.
The idea is to bring the body temperature down from a normal 98.6(F to between 89.6(F and 93.2(F. In the European study this was done for 24 hours with the use of a special mattress and cover that blows cooling air over the body. In the Australian study it was done by having paramedics apply ice packs to patients' heads and torsos, followed by more extensive icing in the hospital for 12 hours. In both cases, the patients remained sedated and received drugs that kept them from shivering.
Both studies compared patients given the hypothermia treatment with patients given normal treatment. In both studies, patients treated with hypothermia were more likely to have a good outcome -- normal function or mild disability -- than patients given only standard treatment.
Safar and Kochanek note that there's still a lot of work to be done. Studies are needed to find the best way to cool patients, and to find out how long they should stay chilled. However, they suggest that there's enough information now for hospitals to start using hypothermia for cardiac arrest patients.
They also urge studies of mild hypothermia in patients who suffer stroke, brain, or spine injury, and shock due to bleeding. They recommend study of profound hypothermia -- dropping the body temperature to 41 degrees F to 59 degrees F -- in patients whose hearts stop due to blood loss following an injury.