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Wednesday, July 13, 2011

Chillin' out after a cardiac arrest

From Tuesday's Wall Street Journal - Circulation's web site doen't appear to have the referenced article available.


A new study could bolster growing interest in a technique to chill the bodies of sudden cardiac-arrest patients that has been shown to help keep victims alive.

Researchers found that of 140 patients who got the treatment, in which the body is quickly cooled after the heartbeat is restored, 56% survived to be discharged from the hospital—92% of them with most or all of their cognitive function intact.

Across the U.S., fewer than 10% of victims survive sudden cardiac arrest when it occurs outside the hospital and among those who do, only a minority recover sufficient brain function to return to a normal life.

The high survival rate suggests the technique, called therapeutic hypothermia, is "one of the strongest [tools] we have to improve outcomes for these patients," said Monica Kleinman, a critical-care doctor at Children's Hospital Boston, who wasn't involved with the study.

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About 300,000 people in the U.S. suffer cardiac arrest each year as a result of either a heart attack or an electrical malfunction that throws the heart wildly out of rhythm. About 125,000 are discovered too late for help. Of those whose pulses are restored, only about 1 in 5 gets treated with therapeutic hypothermia.

"The implementation and spread of this has probably been slower than people would like, given the strong evidence that it's helpful," said Dr. Kleinman, who also heads the American Heart Association's emergency cardiovascular care committee.

It isn't the cooling technique alone that improves chances of survival. The study's results also underscore the value of an organized referral system in which critically ill patients are quickly transported from outlying areas to a sophisticated regional medical center for treatment.

The 140 patients were treated at Minneapolis Heart Institute and Abbott Northwestern Hospital, Minneapolis, which maintain a network for emergency heart care with more than 30 rural hospitals and about 45 emergency medical services within a 200-mile radius of the city. In the study, 107 patients were transferred from the outlying hospitals at an average distance of 56 miles. From the first EMT responder at the scene, to the ER doctor and cardiologist at the hospital, to the critical-care nurse in the ICU, all follow an established treatment protocol.

"These patients need excellent care in the field … and a network of care so they come into a hospital where everybody knows their role," said Michael Mooney, a cardiologist and head of the "Cool It" initiative at Minneapolis Heart Institute. Dr. Mooney led the new study, which was published online Monday by the AHA journal Circulation.

Therapeutic hypothermia is applied after a patient's heartbeat has been restored through cardiopulmonary resuscitation and shocking with a defibrillator. Increasingly, rescue squads are initiating cooling by placing ice packs on patients as they are being transported to the hospital. The city of New York and top medical centers in New Orleans, Tucson, Ariz., and Nashville are among places that have embraced the technique.

In the study, every hour of delay in initiating cooling was associated with a 20% increased risk of death, the researchers found.

More sophisticated cooling blankets that regulate both the temperature drop and a rewarming of the patient are used after admission.

Generally, patients are cooled to about 90 to 92 degrees Fahrenheit, or about six to eight degrees below normal temperature. They are put in a medically induced coma for 24 hours before their temperature is gradually brought back to normal. Patients may remain in a coma for a few days before being brought back to consciousness.

"It's a very robust therapy and it's simple," says Dr. Mooney. "It doesn't necessarily rely on fancy equipment. Simple measures make a huge difference."

One reason for its slow adoption, Dr. Mooney said, is that cardiologists have been skeptical that new approaches can make headway against the historically poor outcomes for victims of sudden cardiac arrest. Another concern is that a new strategy may improve survival, but not quality of life.

"Our biggest worry would be that we'd bring back folks that didn't function as Mom in the family or Dad in the family," Dr. Mooney said. But, as reflected in the 92% who were revived and able to return to normal or near-normal life, "that hasn't happened."

Sarah Bartlett is a case in point. In 2006, at age 32, she collapsed in her yard while talking to a contractor about a remodeling project. The emergency squad had to apply three defibrillator shocks to restore her heart beat—about 21 minutes after she went down.

She didn't regain consciousness. At the hospital, ice was applied as she was rushed to the cardiac catheterization lab for treatment. There, a cooling blanket was applied as doctors treated her heart blockage.

Twenty-four hours later, rewarming was started, and her normal temperature was restored in about six hours. Three days later, she regained consciousness, with her cognitive function close to normal.

Ms. Bartlett, who was an intensive-care unit nurse at the time, says it took about three months before she felt fully recovered. She went on to graduate school and achieved a 3.9 grade-point average while qualifying to become a nurse practitioner. "I feel confident that I am neurologically intact," she says.