Therapeutic hypothermia after CPR improves survival and lessens brain damage

Cooling a person's body within six hours of cardiac arrest with successful CPR might improve survival and lessen brain damage, according to a new Cochrane review.

The cooling technique, known as therapeutic hypothermia, "is one of the most successful treatment options for patients after cardiac arrest," said lead author Jasmin Arrich, M.D., a researcher at the Medical University of Vienna in Austria. "Clinical studies showed that by cooling the body after cardiac arrest to 33 degrees Celsius (91 degrees Fahrenheit) for 24 hours, patients are 40 percent to 80 percent more likely to leave the hospital without a major handicap."

Arrich and her colleagues pooled data from three studies of 481 patients who had suffered cardiac arrest, undergone CPR and had their hearts restarted. Those who received hypothermia treatments were 55 percent more likely than those receiving standard care to reach a high brain function test score during their hospital stay. They were also 35 percent more likely to survive to hospital discharge. The researchers found no evidence of increased side effects in those who had the therapy.

Arrich described therapeutic hypothermia as a simple method to improve outcome after cardiac arrest by using ice packs, cooling pads or water immersion, as well as by cooling the body directly using cold IV fluids or catheters that lower the blood's temperature directly. It's like putting the brain into hibernation while the body clears toxins that built up in the body during the cardiac arrest.

"If patients suffer from sudden cardiac death, the best way to save their life and to prevent brain damage is to start with basic life support immediately and call professional help," Arrich said. "After successful resuscitation, treatment with mild hypothermia may further help to improve outcome. Of course, in this situation, patients are usually unable to decide about their treatment; therefore it is usually a physician's task."

The new review appears in the latest issue of The Cochrane Library, a publication of The Cochrane Collaboration, an international organization that evaluates medical research. Systematic reviews like this one draw evidence-based conclusions about medical practice after considering both the content and quality of existing medical trials on a topic.

Clifton Callaway, M.D., an associate professor of emergency medicine at the University of Pittsburgh School of Medicine, said that the review results confirm the usefulness of what many physicians already felt was best practice.

"Mild hypothermia for those successfully revived from cardiac arrest improves survival," he said. "Perhaps more important, it also decreases brain injury, so that the person can go back home fully intact mentally and physically."

Many patients and their families are concerned about treatments that might increase survival following a heart attack but that can result in severe brain injury.

"For a couple decades we have made strides in saving the heart so that most people ask doctors about things like clot dissolving medications or bypass surgery," Callaway said. "Now there is treatment for the brain as well and family members should be expecting it and demanding it be made available."

David Beiser, M.D., an assistant professor of medicine at the Emergency Resuscitation Center of the University of Chicago, said the review reinforces the standards of care the American Heart Association set out in 2005.

However not all hospitals will have the ability to cool patients rapidly who have been successfully resuscitated. He likens this to the trauma system where not every community has the resources needed to operate a Level 1 Center.

"If a loved one is not at a hospital that has a cooling protocol in place, family should ask about the feasibility of a quick transfer to a center that is familiar with therapeutic hypothermia," he said. "At this point, this is what I would recommend — and have recommended — to a friend or loved one."