High Altitude and the Body

  • By David Levin
  • Posted 01.01.06
  • NOVA

Many skiers and mountain climbers experience altitude-induced illnesses, which can range from harmless dizziness to acute and life-threatening edemas. In this podcast, Peter Hackett of the Institute for Altitude Medicine explains how altitude affects the brain and lungs, how to prevent altitude sickness, and how to recognize the symptoms of severe illness when it strikes.


Listen as Dr. Peter Hackett of the Institute for Altitude Medicine discusses the effects of high altitude on the body.

This feature originally appeared on the site for the NOVA program Deadly Ascent.


High Altitude and the Body

Posted January 1, 2006

DAVID LEVIN: You're listening to a NOVA podcast. I'm David Levin.

For adventurers who set out to climb mountains like Alaska's Denali, icy, treacherous terrain isn't the only obstacle. In addition to biting winds and frostbite, they also face altitude-induced illnesses that can sometimes be deadly. But these same medical conditions can also affect people at more benign vacation spots, like some high-elevation ski resorts in the Rockies. Dr. Peter Hackett is executive director of the Institute for Altitude Medicine in Telluride, Colorado. We talked to him about the effects that altitude can have on the body.

Dr. Hackett, thanks for speaking with us. To start off, what is it, exactly, about high altitude that can have such an impact on the body?

PETER HACKETT: Well, humans did not evolve at altitude. We evolved in the plains of Africa, and when we go to high altitude, because there's less oxygen in the air, it puts a stress on our body. To give you some perspective in altitude, In Denver, there's 17 percent less oxygen in the air than at sea level. Here at Telluride, there's about 28 percent less oxygen in the air than at sea level. And on the summit of Mt. Everest, there's only about a third of the oxygen in the air as compared to sea level. So this lack of oxygen puts a stress on every organ in the body, but especially the brain, since it's very sensitive to lack of oxygen.

DAVID LEVIN: What types of medical problems could be triggered as a result?

PETER HACKETT: We divide the altitude related illnesses into categories. Most frequently here in Colorado, and in other places in the world, people who aren't adjusted to the altitudes come up a little too quickly for their bodies to acclimatize, and they get what is called Acute Mountain Sickness, which is the most common form of the illness, and feels like a bad hangover. Usually lasts a day or two and goes away by itself, and only rarely does it turn into something more serious, which can be life threatening. And that's the high altitude brain edema, or the high altitude lung edema.

DAVID LEVIN: So, what makes those conditions so dangerous?

PETER HACKETT: High Altitude Pulmonary Edema is a condition in which the lungs fill with fluid—blood vessels leak from the capillaries into the air sacs. And when the air sacs are filled with Plasma instead of air, the person can't get oxygen. And within 24 to 48 hours, they'll die if they don't get to a lower altitude or get oxygen or some sort of treatment. It happens here in Colorado, about 1 in 10,000 skiers. Which doesn't sound like much, except there's 12 million skiers a year, so we see a fair amount of it. The brain edema at altitude is even less common, fortunately. It an also be fatal, and it's just like in the lungs, there's a leakage of capillaries into the brain tissue. The problem is that the brain is encased in a rigid skull, and there's not much room to expand, so when fluid starts leaking in the brain, the pressure builds up, and results in death from brain edema. It's more common in the higher altitude places like the Andes and Himalaya. But we do see a few cases every year.

DL: How long does it take for those serious conditions like lung edema to develop?

PETER HACKETT: It takes 2 to 3 days to develop. Once it develops, it can result in death within 12 to 24 hours. And about the same, maybe a little longer, with the brain edema. It can take 4 or 5 days. None of these conditions are worrisome for people going on day hikes. It's only people that are moving to a new altitude and spending at least 2 nights there.

DAVID LEVIN: But if you're experiencing something like that, though, what kinds of symptoms should you really watch out for?

PH: The hallmark of progression from the simple benign form of mountain sickness to the severe brain edema is mental confusion and trouble with balance. Those are the things people need to watch for, especially. In terms of the lungs—you know, everyone coming to altitude is breathless, especially going up stairs or exerting. The key there is that people who are starting to develop pulmonary edema are not only breathless, they're also weak and they develop a cough. So I advise persons with weakness, cough, and shortness of breath, that they have pulmonary edema. And need to get medical attention or get to a lower altitude.

DAVID LEVIN: Is there anything one can do to prepare in advance to prepare for that, or is this something that will affect certain people no matter what they do?

PH: Good question. There's genetic component to that. People are genetically predisposed to develop altitude illness, let's say, 30 percent of the population or so, they might develop it even if they do some preventative maneuvers. And then there's another segment of the population, let's say another 30 percent, that can come up very quickly and would never even notice the altitude. And then there's the rest of us, in between, where preventive measures might make a difference because we are susceptible if we go quickly, but we're not susceptible if we go slowly. Probably the most important preventive measure is to avoid going immediately from low altitude, that is, below 4,000 feet, to spend the night above 9,000 feet in one day. And our studies show that if people just spent the night in one of the intermediate altitudes on their way up to Telluride for example, they do much better. Of course, not everyone has time for that, but that is an effective maneuver.

DAVID LEVIN: So, when traveling to a high-altitude area like some popular ski resorts, how wary should someone be of having an altitude illness?

PETER HACKETT: Well, the typical form of mountain sickness, the bad hangover kind of thing is not terribly severe, but it does impact people's activities. Does that mean people shouldn't come to Colorado to ski? No, of course not. It's generally mild, and I liken it to sea sickness. Would you not do a cruise because you're worried about sea sickness? Well, some people might not. But it's limited. It goes away in a day or two, the symptoms aren't severe, and there's a medication that can be taken to prevent it entirely. And there's other maneuvers that can be used to minimize the symptoms.

DAVID LEVIN: What are the options for treatment once an altitude-related illness develops? Seems like something you'd have to address pretty quickly, which could be a problem if you're on the top of a mountain.

PETER HACKETT: Yeah. The treatment options are determined by the situation, so at 26,000 feet, options are quite limited, if you have to get somebody down in a hurry. Hopefully there's oxygen available. In the back country here, in some ways it can even be more remote than Everest, because there's no Sherpas here to come get you out of trouble. And so when the symptoms come on, if they're mild, and the mind is clear, and the breathing is not too labored, it can be safe to wait for 24 hours or so to see if they diminish, and take an ibuprofen or a Tylenol for headache pain. And drink some extra water and stay well-hydrated. But then if symptoms persist after 24 hours or so, or if they're getting worse, one is going to have to go down in altitude.

DAVID LEVIN: So how far down would you have to go before it had an impact?

PETER HACKETT: We used to think that people had to go all the way to sea level to get better, especially if they were severely ill. We now know people only have to go down about 1000 feet or so. Many lives could be saved with that knowledge. There's too often—somebody with pulmonary edema, for example, is waiting for a rescue in the back country, their friends go out to find a ranger to call a helicopter, and when they return, the person's dead. Whereas if they had just started down the hill, even if they had to carry them, get them down 1000 feet, they could have saved their life.

DAVID LEVIN: Well, Dr. Hackett, thanks again for speaking with us.

PETER HACKETT: Good talking to you. Take care.

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