Altitude Sickness, From Bad to Worse
By Katie Arnold

In the dicey world of mountaineering, one thing is certain: Stay above 25,000 feet long enough and you will die. "The communication between your brain and your organs falters," explains Dr. Peter Hackett, one of the foremost experts in the field of high-altitude medicine, a one-time Everest summiter, and the founder of Denali Medical Research, based at 14,000 feet on the flanks of Alaska's Mount McKinley. "Simply put, it's death by starvation, dehydration, suffocation, and exposure." Herewith a closer look at exactly what happens to mind and body as you move from base camp up into what is so aptly called the Death Zone.

16,000-19,000 Feet: It's early in the game, but already your blood is carrying a third less oxygen than at sea level, and your brain and its messengers are bearing the brunt. You're experiencing what feels like a mild bout of the flu mingled with a three-martini hangover-annoying, but not incapacitating. Symptoms include shortness of breath, occasional dizziness, and insomnia, which is in part caused by an unconscious fear of suffocating. And even at these relatively low altitudes, things can get much worse, especially if you ascend too quickly. Most feared are acute mountain sickness, characterized by severe flu-like symptoms, and pulmonary and cerebral edema, the often fatal swelling of the lungs and brain. These ailments can strike the strongest of climbers at any time during an ascent.

20,000-25,000 Feet: "You feel like you're one giant lung, as if breathing is all there is to life," says Hackett. The reason is that you're now inhaling four times faster than normal, and your body still isn't getting enough oxygen. A deep, rib-cracking cough may also set in, and your digestive tract, which badly needs oxygen, calls it quits--leaving your body so hungry for nutrients, notes Hackett, "that it literally starts to eat itself." Weird dreams and hallucinations are signs that things are falling apart upstairs, too. "Your brain's like an engine with carburetor trouble. When it doesn't get enough oxygen, it starts to slow down, and judgment goes out the window," explains Hackett. "Sometimes," admits Kitty Calhoun Grissom, a top American climber, "I find myself spending a half-hour thinking about how I can improve my shoe-tying methods."

Above 25,000 Feet: Welcome to the Death Zone, where things go from bad to worse very fast. Supplemental oxygen, which many climbers use above 24,000 feet, can mitigate the effects of altitude somewhat, but inevitably you will run out. When you do, you become careless and sluggish, so fatigued that you can stagger only ten or so steps before lurching over to rest. To conserve oxygen, your brain is putting the brakes on some muscle activity, turning you into a klutz. You're probably also experiencing a deep chill in your bones--the onset of hypothermia--since the lack of oxygen makes it impossible for your body to generate enough heat. Even if you've so far managed to avoid the dreaded edemas, immediate descent is a must to stave off collapse, unconsciousness, and death. The good news? Within a few days of returning to a more reasonable altitude, says Hackett, you'll probably feel OK-though some new studies suggest that you'll bring back a couple of lasting physiological souvenirs from the top of the world: Your motor skills may be a tad out of sync and your memory may not seem as sharp.