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Patient Care

Hypothermia for SCI

   You've probably not heard of Dan O'Reilly, but his story was remarkable. The 55-year-old Canadian was surfing on a 2004 Mexican vacation when a large wave overwhelmed and nearly drowned him. He was near-lifeless when dragged from the surf. He received quick medical help, but doctors couldn't identify any trauma. They thought perhaps he'd suffered a heart attack or stroke in the water. In a coma, on life support, with virtually no brain function, O'Reilly was flown to the States.

   There, in desperation, doctors in Houston tried hypothermia, figuring it was their best chance at preserving some brain function. They cooled O'Reilly for three days--and then he woke up, mind intact. That was surprising enough. Just as surprising was the MRI that showed O'Reilly hadn't had a heart attack at all--rather, he'd suffered a severe spinal cord injury.

   It had been, as one media account put it, "the best possible misdiagnosis." In conjunction with the other interventions O'Reilly received, the cooling therapy apparently helped protect both his brain and spinal cord.

   "Cooling does a number of things," explains George Ralls, MD, FACEP, medical director for the Orlando/Orange County EMS system in Florida. "First, it suppresses inflammation. With an injury, the injured tissue becomes inflamed, and that can lead to injury of adjacent tissue that's initially intact. That can cause a loss of good nerve tissue that wasn't directly damaged. Cooling also reduces production of oxygen free radicals and metabolic demand in the spinal cord itself. So it's a number of different things, but the neuroprotective process is the same we use for closed head injuries or cardiac arrest."

   A more familiar case may be Kevin Everett's. A tight end for the NFL's Buffalo Bills, Everett sustained a life-threatening C3-C4 dislocation during a game in 2007. Doctors expected permanent neurologic impairment. But Everett was treated aggressively, receiving prompt cooling, IV steroids and rapid surgical decompression. After an injury following which fewer than a quarter of patients ever walk again, Everett was on his feet within three months.

   "With Everett, they did more than one thing that was outside the box," says Ralls. "It's difficult to tell which of those interventions had the most impact--maybe all three, maybe one of the three." But it's clear the outcome defied normal expectations.

   Let's emphasize one thing: Hypothermia is not now the standard of care for spinal cord injury, and if you show up at a hospital with a cooled SCI patient, some doctors are likely to have some very harsh words for you. But the evidence, it's intriguing.

   First the animals: A 2009 Critical Care Medicine review of experimental and clinical data surrounding modest hypothermia for acute SCI in a variety of animals (cats, dogs, monkeys, rats and ferrets) found just one investigation of 17 that showed negative outcomes. In those cases, cooling spanned a wide range of times and temperatures. A study in the Journal of Comparative Neurology that year found cooling rats to 33°C for four hours beginning five minutes after moderate cervical displacement resulted in faster recovery of locomotor ability and improved forelimb strength.

   "None of those rats had the same level of function as an uninjured rat, but they did better than the ones that weren't cooled," notes Ralls. "The evidence there leans toward preserving some degree of function, which is important for spinal cord-injured patients. For them, every level counts."

   Still, rats aren't people, and the human data, while preliminarily encouraging, isn't yet as strong. In a 2009 article in the Journal of Neurotrauma, a team led by Dr. Allan Levi of the Miami Project to Cure Paralysis reviewed the cases of 14 patients with acute, complete c-spine injuries who were cooled by IV catheter. That provided needed baseline data that's now informing broader examination.

   There's nothing so far to suggest cooling of SCI patients needs to begin in the field. In Levi's paper, it began from 3–33 hours postinjury. The point there was not to establish ideal parameters, just to show the therapy doesn't seem associated with bad outcomes.

   It's also worth noting that while things like cardiac arrest are distinct clinical entities, spinal cord injuries--in the real world, versus in the lab--typically come with significant additional trauma.

   "For EMS, it's going to be an entity wrapped into a lot of other stuff," says Ralls. "It could be a multisystem trauma patient. It could be intra-abdominal bleeding. There could be other complicating issues."

   With a benefit apparently emerging, though, it's worth digging deeper in search of optimum initiation, duration and temperature parameters, and what else should accompany hypothermia to maximize any benefit.

   That work is continuing. It's still early. But it's not inconceivable that emergency caregivers could, one day, cool SCI patients just as many of us now cool cardiac arrest patients.

   "It's an exciting thing on the horizon. We all want to do everything we can for our patients," says Ralls. "But it's important to remember we don't know for sure at this point how much hypothermia's going to help. And, probably more important, we don't know if in some cases it's going to hurt. The animal models, although encouraging, are not representative of our patients who sustain multisystem trauma. The reason we cool cardiac arrests is because we reacted to the results of a well-designed randomized controlled trial. We didn't just come up with it. So while it's exciting to see this on the horizon, people need to be patient and wait for the results of something that can really define this as either safe and appropriate or not."

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