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Darren Braun  /  Courtesy of Men's Health
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updated 7/29/2007 2:41:54 PM ET 2007-07-29T18:41:54

Everyone in the operating room has just taken a deep breath. Gary K. Steinberg, M.D., Ph.D., the diminutive 54-year-old head of neurosurgery here at Stanford University medical center, looks up at his anesthesiologist.

"Time."

The anesthesiologist nods, then starts his stopwatch. The nurses exchange glances. Nobody speaks.

It's 4 hours into the surgery — a cranial bypass, which includes drilling into the skull, isolating arteries, and exposing brain tissue. But the time on the stopwatch is all that matters now. Life or death depends on it. Dr. Steinberg has just placed a clamp on a branch of the patient's middle cerebral artery, cutting off bloodflow to a small portion of the brain. His patient would normally die within minutes. But Dr. Steinberg is a cool customer, and his patient, as it turns out, is very cold.

The patient is 33 degrees Celsius, or 91.4 degrees Fahrenheit, to be precise. That's considered only mild hypothermia, but it's cold enough that without inhibitory drugs, the patient would shiver and convulse uncontrollably, making breathing impossible. But without this decrease in body temperature, the patient's brain would begin suffering a stroke in about 5 minutes. Hypothermia extends the window to 30 to 40 minutes, buying Dr. Steinberg enough time to correct the underlying problem. In this case, it's Moyamoya disease, a progressive cerebrovascular disorder caused by blocked arteries at the base of the brain. But the technique is also effective at slowing brain-cell death after a stroke, head trauma, or even a serious heart attack.

Body as a machine
Brain surgery, as you might expect, is a solemn event. You stare at exposed brain tissue — at the tubes and vessels supplying blood to it — and all of your feelings, your thoughts, and your memories suddenly seem fragile and fleeting. You're reminded, This body is a machine, and this machine always breaks.

And that's precisely what makes Dr. Steinberg's work so compelling. With tools and time, machines can be fixed. Surgeons have plenty of tools. Induced hypothermia gives them time. The implications are huge: Imagine a future in which you're not dead. You're just waiting for repair.

The clock runs for 27 minutes. During that time, a section of the patient's brain is entirely deprived of oxygen.

Dr. Steinberg bypasses the blockages by sewing an artery inside the skull to one outside it, via a small hole he drills through the bone. While Dr. Steinberg cuts and sews, the anesthesiologist walks over to a machine about the size of a water fountain and checks a small monitor. It reads 33 degrees. Attached to the machine is a long plastic tube that disappears into the femoral vein at the patient's groin. At the end of the tube, somewhere within the inferior vena cava, just below the heart, is a gold-plated catheter. The catheter is an advanced heat-exchange system. By warming and cooling saline inside the tube, it controls the temperature of the blood passing over it. The catheter can induce mild hypothermia in about 30 minutes and reverse it in an hour.

Dr. Steinberg is one of a handful of neurosurgeons in the United States who induce mild hypothermia before brain surgery. Once considered a maverick procedure, it's now on the cusp of becoming an accepted technique, partly because of the evidence mounted by Dr. Steinberg himself. In addition, the American Heart Association recently recommended the practice to minimize brain damage after cardiac arrest. (The best place in the country for your heart to stop may be Wake County, North Carolina, the first municipality in which EMS paramedics cool cardiac-arrest survivors on the way to the hospital.)

Measure of last resort
Two decades ago, induced hypothermia was a procedure of last resort, reserved for risky operations in which there was little to lose, such as surgery on a stopped heart. It required cooling blankets, ice, and a host of drugs to suppress the body's reaction to cold. Because the body was chilled all the way to 18°C (about 64°F), the side effects were enormous: frostbite, shock, pneumonia, death.

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Everything changed in 1987. That's when a research assistant at the University of Miami named Raul Busto noticed that even when bloodflow was cut off to a section of the brain in certain rats, they didn't have a stroke. Busto found that these rats all had lower body temperatures than the rats that did have strokes. Most interesting, however, was that the stroke-free rats' body temperatures were only a few degrees below normal. At the time, scientists believed that hypothermia slowed a person's (or rat's) metabolic rate — that the cooler the body, the less oxygen the cells needed to survive. But these rats had metabolic rates that were just slightly slower than normal, and their rate of stroke was virtually zero.

Since then, researchers have discovered that metabolic rate has only a minor influence on the survival of cells. More important, hypothermia tempers the biochemical reactions that occur inside a cell that's deprived of oxygen, thus preventing its death.

When bloodflow is cut off — either by a stroke, a heart attack, or, in Dr. Steinberg's case, a clamp — cells release glutamate, calcium, and free radicals, all of which wreak havoc on cellular membranes and DNA. This leads to necrosis, or involuntary cell death. Mild hypothermia slows these reactions, though it's not entirely clear how. (Many experts believe these chemical reactions occur at an optimal temperature, and lowering the temperature decreases their incidence.) Mild hypothermia also slows what's known as apoptosis — that is, cell suicide.

It's often useful for the body's cells to kill themselves, such as if cancer has invaded them. But generally you don't want your cells offing themselves, as they do when there are a lot of free radicals about.

"Mild hypothermia probably summons a cocktail of neuroprotective agents," Dr. Steinberg tells me in his office the next day. "We can speculate that it prevents the release of (cell-killing) cytokines and free radicals, or at least interferes with their release, but we just don't know for sure. What we do know is that it works."

Not everyone agrees, at least not yet. A study in the "New England Journal of Medicine" suggests that mild hypothermia has no effect on patients with traumatic head injuries. When I mention it to Dr. Steinberg, he smiles. He's been testing the procedure for a dozen years; he's used to the criticism. The study, he says, is flawed, because the researchers didn't control for the severity of injury.

"Yes, there are critics," he says, "but I've spoken with a lot of them, and even they say, 'If I have a stroke, I want to be treated with hypothermia.' "

Line between life and death
Dr. Steinberg's modest office could belong to a vice president of a bank, except for one thing: the TV monitor in the corner that feeds him live video of the O.R. While we chat, I watch the monitor as a resident marks the shaved head of a patient and calls up to Dr. Steinberg every few minutes for feedback.

I find it gratifying to know that people like Gary Steinberg exist. People who are smart and motivated, who want nothing more than to use their brains to allow the rest of us to continue our silly lives. Their power is awesome. Think about it: Induced hypothermia allows for temporary death. The procedure suspends cellular function without ending it.

In some of these surgeries, neurons lose their electrical potential entirely. With no oxygen, no blood sugar, and no electrical charge, brain function ceases. The clinical definition of brain death is the complete and irreversible cessation of brain activity. As technology advances, the question of whether the cessation of brain activity is reversible becomes a little trickier.

Consider: In 2004, scientists at the Safar Center for Resuscitation Research, in Pittsburgh, announced that they'd developed a way to revive dogs 1 hour after clinical death. The procedure involved removing the dogs' blood and replacing it with saline at 2°C. After an hour in which the dogs' hearts did not pump and no brain activity was recorded, a mild electric shock was given to the hearts, and the saline was slowly replaced with blood. Almost all the dogs awoke completely normal, though a few had physiological problems. In a subsequent study last year, scientists extended the suspended-animation window to 3 hours, thanks to a sugar-and oxygen-enriched saline, and reported similar success.

This technique is thought to be most applicable for people with serious trauma, such as soldiers wounded in battle or victims of car accidents. Many of these patients die because they lose too much blood on the way to the hospital. EMTs could replace a victim's blood with cold saline, and the patient could be operated on and resuscitated at the hospital.

Though the Safar Center has yet to try the practice with humans — and probably won't for years — the long-term implication is clear: The line between life and death is blurring. We've had a tortured debate for eons over when life begins, but it's only now, in the 21st century, that we can begin a debate on when it ends. Not when it should end, but when it does end.

So, the big question, then: is death just when a doctor gives up?

Standing in Dr. Steinberg's operating room — seeing an exposed brain, arteries, veins — it's easy to view the human body as simply a finely tuned machine. And if it's a machine, it can be suspended, fixed, and reinvigorated. It can die (if that's the right word) and then live again.

We tend to think of life and death as black and white. At point A, I am alive. At point B, I am dead. But as our ability to tinker with the basic mechanics of life increases, as we clone organs and build machines that can breathe for us, pump blood for us, stop and start our hearts for us, the area between those two points begins to gray.

The thought of this is a bit humbling. But mostly, it's exhilarating.

© 2012 Rodale Inc. All rights reserved.

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