Nov. 9, 2010 -- Doctors may have saved a North Carolina woman's life recently by literally putting her body on ice.
Amy Moore, a 38-year-old mother, was all but dead when she collapsed at her workplace on Sept. 14, suffering what's called "sudden cardiac death" -- despite having no pre-existing heart conditions. According to doctors at the University of North Carolina where Moore was treated, she had no pulse for 20 minutes.
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"She was in really bad shape. It was very scary, she was unconscious, but she was fighting tremendously," said her husband, Jacob Moore.
Moore was rushed to a local hospital in a race against time.
"When I saw her and her family, I thought that her chance of survival was less than 50 percent," said Dr. Joe Rossi, a cardiologist at the University of North Carolina.
Doctors Turn to "Therapeutic Hypothermia"
Doctors attempted a daring procedure, essentially freezing Moore's body to buy time until they could get her damaged heart pumping again.
The procedure is called therapeutic hypothermia, and it involves artificially lowering the body's temperature.
Moore was wrapped in an ice-cold blanket and injected with freezing fluids to bring her temperature down to just 93 degrees, well below the body's normal 98.6 degree temperature. Her body was kept in that state for two days.
The cooling put Moore's brain into a dormant state, helping to avoid the brain damage that comes when the heart temporarily stops providing the brain with blood.
Small Window to Cool Body
The window for such treatments is short. A patient must be cooled within 30 to 60 minutes of sudden cardiac death, but the procedure is available at an increasing number of hospitals across the United States.
The original idea of using hypothermia to help cardiac arrest victims was born out of the clinical observation that children who fell through icy ponds or lakes and become trapped underwater could frequently survive without neurological damage, even in instances when they were under water for up to an hour.
In normal situations, by contrast, there is a very slight chance of survival after loss of circulation for 10 minutes.
Since the appearance of two studies on the use of hypothermia in the setting of cardiac arrest in the New England Journal of Medicine in 2002, clinical centers have been implementing this technique -- and in some academic centers, it has even become a routine procedure over the past two to three years.
Still, debate over which patients benefit from therapeutic hypothermia continues, and definitive guidelines vary across institutions.
What is known is this: when patients suffer cardiac arrest, the lack of circulation results in severe damage to the brain. And the cooling effect offered by therapeutic hypothermia may give many of these patients a better chance of pulling through.
"The real mechanism is unknown, but it is hypothesized that cooling in the setting of cardiac arrest gives the brain time to rest and heal," said Dr. Michael Sayre, chairman of the Emergency Cardiovascular Care committee of the American Heart Association and an associate professor of emergency medicine at Ohio State University.
The cooling could also preserve the brain through a critical window of time during a cardiac arrest when the cells of the brain would normally die off, he said.
Cooling Technique Varies Among Hospitals
As for how doctors achieve this cooling effect, techniques range from relatively low-tech ice packs and cooling blankets, to the use of catheters to cool patients from the inside out.
Whether the newer methods are better is still uncertain -- though Sayre said further study would help answer this and other questions.
"We still have a lot to learn," he said. "Right now it is a 'one size fits all therapy' where everyone gets cooled to the same temperature for the same amount of time."
Additional research, he said, may help identify methods that can be adjusted for care of individual subsets of patients.
Therapeutic Hypothermia a "True Advance" for Cardiac Treatment
But even today, as seen in Moore's case, the technique is viewed as a true advance in treating cardiac arrest patients.
"It's certainly been one of the most gratifying therapy interventions of my career," said Dr. David Palestrant, director of neurocritical care and stroke programs at Cedars-Sinai Medical Center. "Before we cooled patients, most died, and in those who survived the vast majority -- about 90 percent -- had significant neurologic impairment.
"With our cooling protocol, we now see about 40 to 50 percent of patients returning to normal neurologic function."
A Second Chance
Today for Moore, it is a second chance to be a wife and mother. While she has suffered some memory loss and is not ready for interviews, her doctors and family expect her to make a full recovery.
"A really true miracle," said Dr. Lisa Rose-Jones, a UNC cardiologist who treated Moore. "She is a mother, daughter, wife, a friend. When I think what she went through, it's truly amazing."
ABC's Dan Childs and Bradley Blackburn contributed to this report.