Anna Bagenholm was skiing in the Norwegian back- woods when she slid headfirst into a frozen stream. Rescued over an hour later, she was clinically dead, with no breath, no pulse.

By the time she was airlifted to a hospital in Tromso and wheeled into an operating room, Bagenholm had been dead for three hours. Miraculously, she was slowly resuscitated and today is a busy radiologist.

This is one of the dramatic cases described by Sanjay Gupta in his new book, "Cheating Death: The Doctors and Medical Miracles that Are Saving Lives Against All Odds" (Wellness Central).

A practicing neurosurgeon, Gupta is also chief medical correspondent for CNN and a columnist for Time magazine. "There is something happening right now in the world that could help you, but you don't know what it is," he explains in an interview. "It's my job to know what it is and to somehow provide you with that knowledge."

We spoke at the New York offices of CNN, as he dashed in and out between television and radio appearances.

Q. You define death as the moment that doctors quit.

A. Yes, it's very arbitrary. It's a grayish area where a cascade of events happens to the body. Everyone agrees now that at any point this cascade can be reversed, and for me that's aspirational.

Q. What happens at the end?

A. When you die, your heart stops and you don't get enough oxygenated blood through the body. Cells burst, and then you'll get organ failure, including the brain, which is the most vulnerable.

Q. Where is the point of no return?

A. We don't know that point. Ten years ago, this would have been a different book. When I was a med student, a patient 10 minutes without heartbeat was dead. I interviewed a guy named Chris Brooks, 45 minutes without heartbeat, and he's alive; I'm talking to him. No brain dysfunction. He's fine.

Because we don't really know when dead is dead, people keep going, they keep shocking, giving medicines, and all of a sudden, Chris Brooks comes back. It challenges everything we know about death.

Q. What's the best place to have a heart attack?

A. It's still a hospital, but casino floors in Las Vegas are a great place since there are cameras everywhere and they have defibrillators around every corner.

CHEST-PUMPING

Q. You point out the efficacy of simple chest compressions in heart attacks — why don't more people know about that?

A. I hope they will after this. Call 911 first, put your hands in the middle of someone's chest, pump like there's no tomorrow and you can make a huge difference. Chest compressions are actually better than standard CPR.

Q. Using suspended animation, scientists can stop death in its tracks. Dr. Mark Roth can turn a rat down like a dimmer switch with hydrogen sulfide and then six hours later turn it back up again to normal. How does that work?

A. We can live without oxygen if we have another fuel source. Scientists can inject a substance that makes you go gray, your heart stops, you stop breathing, but you're alive.

Q. What's the potential in saving human lives?

A. The Defense Department is interested in this as a way to buy time for mortally wounded soldiers on the battlefield.

HYPOTHERMIA WORKS

Q. During her ordeal, Anna Bagenholm's core temperature dropped to 56 degrees Fahrenheit — is that what saved her?

A. Hypothermia works because it puts the brain and the heart to sleep. It lowers the set point of the body.

Q. And chilling can help cardiac patients?

A. Hypothermia for me has become a mission. You can have up to a 500 percent increased survival rate as a result of being chilled. Essentially it's free, since you're using ice and freezers to cool the saline.

In New York City, paramedics carry chests with ice cold saline, and they start cooling in the field. But it's not happening around the country.

Q. Why not?

A. It doesn't have a billion-dollar ad campaign behind it like a new drug.

Q. David Bailey was given six months to live after doctors found a glioblastoma, or brain tumor, yet he has survived for a dozen years. What accounts for that?

A. Hard to say. But as an academic society, we tend to try one treatment and see if it works, and if not, move on to the next one. What Henry Friedman, the oncologist at Duke, says is, "We'll figure out later why it works — let's just throw the kitchen sink at the guy. Something's got to stick!"