How Cold Is Too Cold?

Medical journals have published accounts of frozen people who were brought back from the edge of death and went on to live normal lives, with no brain damage, even after as many as seven hours of cardiac arrest. (Under normal circumstances, doctors call it quits at 20 minutes.) Hence a popular saying in medicine: “You’re not dead until you’re warm and dead.”

“We’ve learned that there really is no temperature so low that you shouldn’t try to save someone,” says University of Manitoba thermophysiologist Gordon Giesbrecht, a.k.a. Professor Popsicle, who is one of the world’s leading experts on hypothermia. “We used to say maybe 20 or 15 degrees C”—68 or 59 degrees Fahrenheit—“and below that don’t bother. But then along came some cases that even at 13.7 degrees C”—about 57 degrees Fahrenheit—“given proper care, people survived. So now we’ve taken away the low-temperature threshold.”

The survival stories make headlines: “Brought Back from the Dead!” Thirteen-month-old toddler Erika Nordby was declared a miracle baby in February 2001 after she’d wandered out through an unlocked door on a two-degree night in Edmonton, Alberta, wearing nothing but a diaper and a T-shirt. Stunned to find Erika missing at 3 a.m., her mother looked outside and saw the baby on the ground. At the hospital, doctors managed to rewarm Erika; 24 hours later, she woke up and cried for her mother.

In May 1986, a group of high school students and teachers had climbed nearly to the top of Oregon’s 11,249-foot Mount Hood when a spring snowstorm blew in and forced them to retreat. At 9,000 feet, facing temperatures of 15 degrees and winds as strong as 60 miles per hour, they built a snow cave, hoping to wait out the weather. In the morning, two of the students managed to make it back to camp, and a rescue mission was launched, but it was delayed another day by the storm. Eventually, after repeated attempts, the remaining students and teachers were brought down off the mountain and taken to various Portland-area hospitals to receive ECMO. Most were too far gone to respond to treatment, buttwo 15-year-olds survived. (ECMO was used as early as 1977 in the U.S. for hypothermia, but the procedure still isn’t widespread or often taught in medical school.)

More recently, in April 2014, a 15-year-old boy named Yahya Abdi stowed away in the wheel well of a Boeing 767 that flew from San Jose, California, to Maui. Aviation and medical experts were in disbelief: how could he survive the air pressure at 38,000 feet and temperatures as low as minus 80 degrees? According to reports, Abdi remembered blacking out shortly after takeoff, but his heart apparently kept beating very slowly. When the plane landed in Hawaii, five and a half hours later, he emerged from his hiding spot unharmed.

Understanding how some people cheat death and pinpointing the precise moment when hypothermia sets in are mysterious affairs. In general, the dominoes start to fall when a person loses body heat faster than it’s produced. The first signs of mild hypothermia begin at the 95-degree mark with the onset of uncontrollable shivering—the body’s attempt to warm itself. Gradually, as you creep toward moderate hypothermia (90 degrees), skin grows pale, lips turn blue, and speech begins to slur. Sink deeper than 82—severe hypothermia—and you lose consciousness. Left in the cold, your body will continue to drop in temperature, and your heart will beat slower and slower until you experience cardiac arrest and die.

However, if you’re discovered during the stage in which your heartbeat is slowing, like Christine Newman was, your odds of survival improve. Sometimes the jostling caused by pulling a victim out of the ice can trigger cardiac arrest, referred to as rescue collapse. But because a person is in a cold state, and the brain requires less oxygen, CPR can keep a victim alive for hours, compared with minutes in warmer conditions.

If you’re transported to a hospital with an ECMO-trained staff, you have a 50 percent chance of surviving without neurological damage, according to Beat Walpoth, a cardiac surgeon at Geneva University Hospitals in Switzerland, who published some of the earliest studies on the effectiveness of treating severe hypothermia. Walpoth is currently leading the International Hypothermia Database, which is gathering patient case histories from around the world to create guidelines for treating hypothermia victims.

Meanwhile, what doctors are learning from survivors like Newman is providing clues to medical technology that could rescue others assumed dead in the cold—and also potentially save heart-attack, car-accident, and gunshot-wound victims. And research at the frontiers of extreme cold doesn’t stop there. Elite athletes, for starters, are jumping into cryotherapeutic chambers, human-size vessels filled with liquid-nitrogen-chilled air, hoping to accelerate recovery and improve performance. We are on the cusp of a new era in far-out science, and it’s rooted in ice.

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