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Emergency Medicine News:
doi: 10.1097/01.EEM.0000365499.10537.90
Special Report

Hearts & Brains on Ice

Scheck, Anne

Free Access

They never stop being shocked, although it's in a very good way. Even now, years after definitive research supporting the use of hypothermia for cardiac arrest helped explain its brain-preserving capacity, two emergency physicians who pioneered the field still find the results stunning.

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A patient may wake up and ask for orange juice — orange juice! — when only a few years ago that same man with out-of-hospital cardiac arrest would have suffered devastating neurologic impact, damage that meant his discharge to skilled nursing care.

Now, however, many of these patients “just wake up neurologically normal,” as if they'd been asleep, which indeed they have, a rather cold sleep, said Laurence Katz, MD, an associate professor of emergency medicine at the University of North Carolina Chapel Hill.

Dr. Katz recently received a $500,000 award from the National Institutes of Health to support his study, “Regulated Hypothermia to Treat Hypoxic-Ischemic Brain Injury.” It has been an intense focus of interest for him since he was an undergraduate at Rutgers University in New Jersey, putting rats into cold coma with ice packs and waking them up with hot air from a hair dryer.

This work, for an honors biology project that also included other higher mammals, put him in touch with the late Peter Safar, MD, who founded the Safar Center for Resuscitation Research at the University of Pittsburgh School of Medicine in 1979, initially as the International Resuscitation Research Center. Dr. Katz has been studying the clinical advantages of hypothermia ever since.

“This is the only therapy that we have that has been shown to make this kind of difference in neurological survival,” said Raina Merchant, MD, a Robert Wood Johnson Clinical Scholar with the University of Pennsylvania Health System in Philadelphia. Dr. Merchant recently led a study showing that hypothermia is actually less costly than other approaches to treat cardiac arrest, including defibrillation and cardio-pulmonary resuscitation training.

About two years ago, Lance Becker, MD, the director of Penn's Center for Resuscitation Science, helped put the issue of hypothermia therapy on the national radar in the Newsweek article, “Back from the Dead.” (July 23, 2007; www.newsweek.com/id/32982.) It caught the public's attention because reviving the dead remains an intriguing area in the medical and lay press, with good and not-so-good results.

In Canada, which has the dubious distinction of having more children freeze to “clinical death” than any other region in the western hemisphere, news accounts of miraculous awakenings of these youngsters have helped raise awareness that cold- associated loss of body function doesn't always mean mortality or brain damage either. Now there are anecdotal reports that some family members of cardiac victims are asking rescue teams whether they cool patients having heart attacks.

But to health care providers who are used to administering drugs and other life-saving strategies, an approach that sends the body into a torpor can be psychologically challenging, at least at first. With hypothermia, the technique can be a little frightening to some, Dr. Katz acknowledged. When staff at one neonatal intensive care unit told him they didn't know how to carry out the protocol on newborns and were inclined to outsource that procedure, he told them: “All you have to do is to turn down the knob on the incubator.”

Of course, it isn't that easy. Even babies need a small amount of sedation and ventilation to undergo the procedure, but Dr. Katz said he tries to emphasize that hypothermia really doesn't need to be complicated or high-tech. “Many of these [cooling] devices are really well made, work really well,” he stressed. Even skillful ice pack placement can get good results.

Dr. Merchant agreed. “One hospital wanted to know how to titrate with ice when their cooling machine broke down, and they did just fine” with some on-the-spot coaching, she said. One side effect — dripping water accumulating on the floor — prompted safety concerns about trying to do other procedures while scurrying around the patient on a wet surface. But the team came through with flying colors, said Dr. Merchant, who goes by the nickname “Dr. Icee,” thanks to listing her pager numbers that way years ago as an easy memory tool for callers.

In some ways, such situations argue for this kind of intervention. “This kind of telemedicine, when it is used in provider-to-provider consultation, is a simple step — just picking up the phone,” noted Lois Ritter, EdD, an assistant professor at California State University, East Bay in Hayward, CA. As a health care consultant, she considers this kind of support very effective, particularly when it involves an experienced user offering support to a newer one.

As far back as 1975, when a team led by Harjeet M. Singh, MD, at the Medical College of Wisconsin published a paper on “myocardial cooling,” the idea of using cooling to stem the possibility of brain damage has intrigued researchers. (Arch Surg 1975; 110[11]:1368.)

Drs. Merchant and Katz say their work was preceded and propelled by compelling data in 2002 when the New England Journal of Medicine published two articles, one from Europe and the other from Australia, showing benefit. In the one from down under, a randomized, controlled trial involving 77 patients, the effects of moderate hypothermia versus normal body temperature were compared with patients who remained unconscious after resuscitation from out-of-hospital cardiac arrest. Hypothermia was associated with a lower cardiac index, higher systemic vascular resistance, and hyperglycemia, and there was no difference in the frequency of adverse events. (N Engl J Med 2002;346[8]:557.) The other, a multicenter trial, which appeared in the same issue, was conducted by Viennese investigators with blinded assessment of outcome. It showed very similar results. (N Engl J Med 2002;346[8]:549.)

Patients who had been resuscitated after cardiac arrest due to ventricular fibrillation were randomly assigned to undergo therapeutic hypothermia with a target temperature of 32°C to 34°C in the bladder over 24 hours. Those patients were compared with others who received standard treatment at normal temperatures. More than half of the hypothermia group had favorable outcomes compared with only about a third in the traditional treatment group.

These results were a turning point, according to Drs. Katz and Merchant.

Five years ago, the American Heart Association formally recommended the use of induced hypothermia in the very patient population studied by those European and Australian researchers. After all, “there are still hundreds of thousands of patients who suffer permanent neurological deficits and death after brain ischemia from cardiac arrest, stroke, near drowning, and traumatic brain injury,” according to a news release at the University of Pennsylvania, which is offering an inaugural workshop this fall on hypothermia training.

So why is the cooling technique used only by about one of every five centers in the United States, if that?

As Dr. Katz himself noted, conservative estimates put that figure at about 17 percent, with only about half that percentage of EMS units employing hypothermia measures during transport.

The movement toward hypothermia comes at a time when there is renewed debate on scoop-and-run transport, which has been showing up in EMT blogs and listserv comments. Because saline solution usually is part of hypothermia induction, it can present a barrier to wider use of hypothermia during transport. Intravenous fluid application, along with intubation needed for ventilation, remains controversial at some centers. It became a point for possible discussion, for example, on the EM Media RSS feed “Medworm,” which featured the scientific editorial, “Prehospital Cooling in Cardiac Arrest — The Next Frontier?” (Scand J Trauma Resusc Emerg Med 2009;17[1]:54.)

In the spring, the Agency for Healthcare Research and Quality began a quest to improve what was seen as the gap between research findings to improve practice and implementation of those improvements. This gap, dubbed the “quality chasm,” is being addressed in part by research conducted in a series of primary care settings known as the Practice Partner Research Network. Early findings show the quality chasm cannot be overcome in most instances without institutional programs that involve audit and feedback as well as participatory planning activities. (Jt Comm J Qual Patient Saf 2008;34[7]:379.)

Dr. Katz arrived at similar findings from personal experience. Every change needs a champion to promote new methodology; buy-in from a wide range of participants is necessary, too, and it can take time to cultivate, he observed.

Dr. Merchant said she hopes many more training sessions will be held so hypothermia use increases, fanning out across the country, even into more rural areas. “I feel very passionately about this,” she said. And, as she pointed out, she is pretty easy to reach for anyone who wants information on the procedure. “I don't mind answering any question at all,” she said.

Comments about this article? Write to EMN at emn@lww.com.

© 2009 Lippincott Williams & Wilkins, Inc.

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