How Babies Survive Cold

A 13-month-old girl wanders outside in bitter cold, clothed only in a diaper. Her heart stops, her toes and mouth freeze solid. Hours later, she's revived.

Miracle? No, just physics, say doctors.

"Babies have a smaller volume to a larger surface area," explains Kenneth Storey, a biochemist at Carleton University in Ottawa, Ontario. "That means their body temperature falls more quickly, bad things happen sooner, and that is good."

Quick Cooling Is Key

Chilling the body faster seems like it can't possibly be "good." But Peter Cox, clinical director of the critical care unit at the Hospital for Sick Children in Toronto, Ontario, Canada explains the advantage has to do with the body's three-step reaction to cold.

If a person is out in the cold and inadequately protected, his or her body will first try and generate more heat through shivering to maintain its interior at a normal 98.6 degrees Fahrenheit. If the body can't stay warm, it will start trying to decrease heat loss by decreasing blood flow to extremities and cooling. Finally, if heat loss continues, the body slows its metabolism to minimize its need for fresh blood flow and oxygen supply.

The sooner the body reaches the final step, the better chance the organs won't become starved for oxygen if a person is exposed to cold for a long period. For example, a body with a core temperature of 68 F requires only 20 percent of its oxygen intake.

"Because children have a larger surface area and cool more quickly, the body begins to slow its metabolism — and its supply demand — more quickly," Cox says. "So a balance is maintained earlier."

Shivering, something adults are more likely to do than babies, also prolongs the time before a body slows its metabolism, and therefore decreases the chances for revival from a cold coma. Finally, Meridith Sonnett, a pediatrician at Babies and Children's Hospital of New York-Presbyterian Hospital, points out that the young organs of babies may be easier to bring back to life.

"Adults often have underlying complex medical illness, particularly heart disease, lung disease, things like diabetes that put them at greater risk for any kind of body insult," she tells PrimeTime Thursday.

Doctors agree it was a slowed metabolism that saved the life of a 13-month-old baby girl who was found face down in the snow in Edmonton, Alberta last weekend. It may also have helped 2-year-old Les Hynek of Eau Claire, Wis. who was found unconscious and not breathing after wandering out in the bitter cold last Wednesday.

Gradual Re-warming

Proper resuscitation is also key to successful survival. To activate the heart, doctors use electric paddles to trigger special nerve-like cells in the heart, called purkinge fibers, which restart the heart.

Doctors must also rewarm the body gradually to prevent cell damage. This is usually done by adding warm saline to the stomach, bladder and lungs or by using a heart and lung machine which removes blood from the body, heats it and then pumps it back in.

The ability of the body, particularly young children, to slow metabolism and survive cold temperatures is even harnessed in some surgical procedures. By cooling a patient's body to 53 to 64 degrees Fahrenheit, doctors can do longer operations more safely.

"We cool infants for heart surgery every day," says Cox.

Still, Storey emphasizes successful stories of revival remain rare. It's a "limited survival," he says, since once ice enters the body it kills the cells it encounters.

Although the ability of a child to revive after entering a cold coma may be more biophysics than magic, some suggest there is at least one miraculous factor to their survival.

In the early 1980s, Dr. Nibhas De, a pediatrician in Thunder Bay, Ontario revived a 2-year-old boy whose heart and breathing had stopped after he fell through ice and drifted in freezing water for 30 minutes.

De says physics and medicine may have saved the boy, but "there is a critical time when it's too late. The miracle is when they are found in time."