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Peter Hackett Peter Hackett
Peter Hackett

Peter Hackett is an emergency physician in Grand Junction, Colorado, and an Affiliate Professor of Medicine at the University of Washington in Seattle. His research on altitude illness has appeared in over 100 articles in various medical journals. In the mid-70s he founded the Himalayan Rescue Association in Kathmandu, Nepal and later went on to found the Denali Medical Research Project in Anchorage, Alaska. In 1981, Hackett reached the summit of Everest, climbing solo from the South Col to the peak.

NOVA: Let's talk about brain research and the affects of altitude. Is it in its infancy right now, or are we breaking through any barriers?

PETER HACKETT: Traditionally, the field of high altitude medicine is a field of respiratory physiologists. Since the initial experiments of Paul Bert in the 1870s all the way through the golden age in the twenties, thirties, forties, when everybody focused on the movement of oxygen from the air to the tissues, what we call the oxygen transport system. That is pretty well worked out now—the role of the lung, the hemoglobin, the brain and increasing the ventilation.

We are now at a transition stage to the next frontier. It's time to shift gears. And the future is in the brain. The next 25 to 50 years is going to focus on brain research. It's the brain that acclimatizes to high altitude; it's the brain that holds the secrets to mountain sickness and to cerebral edema. Brain research is in its infancy. As the secrets of the brain become unlocked over the next 25 years, so will the mysteries of mountain sickness and adaptation to high altitude.

NOVA: What happens to a person's brain when they develop mountain sickness?

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PETER HACKETT: If a person develops mountain sickness, the brain starts to swell and one of the primary symptoms is altered consciousness. By that, I mean definite cognitive problems. Judgement becomes impaired—a person becomes confused. They don't even know where they are as it gets worse. They don't know where they came from, where their friends are. I've had people hallucinate. I

had a German one time at the clinic in Pheriche who saw a red helicopter in our front yard and had to be physically restrained. He didn't understand why we wouldn't let him get on the helicopter. There was no helicopter—it was a hallucination. So all sorts of mental changes can take place with altitude sickness as the brain starts to become more and more abnormal.

NOVA: Why does the brain swell?

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PETER HACKETT: We don't know exactly why the brain swells. There's increased blood flow, which by itself causes the brain to enlarge a bit. And there's leaky blood vessels for reasons that aren't entirely clear. And as our blood vessels leak, the fluid stays in the brain tissue and causes the whole brain to swell. People retain fluid when they get sick and that contributes to brain swelling as well.

NOVA: Do you think that climbers that do well at altitude have a greater adaptability to the swelling of the brain?

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PETER HACKETT: I think the climbers who do well at altitude can tolerate a little bit of brain swelling more than others for various reasons. They have better mechanisms to tolerate brain swelling. And they probably have less brain swelling than the ones who get sick.

The mechanisms that allow you to tolerate a little bit of brain swelling include a displacement of cerebral spinal fluid from the brain down into the spinal cord, increased adsorption of spinal fluid in the brain and decreased production of spinal fluid to make room for the brain to swell. There may be even simple anatomical factors like how tight the brain is inside the skull. Which varies very much from person to person and also changes with age.

NOVA: You've said it is best to be dehydrated at altitude because a dehydrated brain doesn't swell at altitude.

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PETER HACKETT: There's evidence that the people who do best at altitude are dehydrated. That is the body resets the serum of molality level which has to do with the water balance. And the body, for some reason, prefers to be dry at high altitude. My own thinking is that this is good for the body because it keeps the brain a little bit drier and softer. So that if it does start to accumulate a little water or get a little swelling, it can be tolerated better.

NOVA: Can you comment on Everest being the maximum height people can climb to? Is this a coincidence?

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PETER HACKETT: I find it fascinating that Everest is right about the height that humans can maximally endure. Obviously, or not so obviously. Whether it's an experiment of nature or sort of intent, it's interesting to speculate. But it appears to be true.

NOVA: Is there an experience one can have that is similar to climbing Everest? Can you compare it to anything that we know?

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PETER HACKETT: It's hard for me to think of anything comparable to climbing Everest because of the sleep deprivation, the extremes of temperature and the hypoxia. Perhaps the closest is war. Where there's constant anxiety of a mortar shell. Worrying about a mortar shell coming into your camp may be similar to worrying about an avalanche coming into your camp. And in war, there's sleep deprivation and problems with eating and drinking properly. But you don't get the hypoxia. You can get the cold certainly, in cold climates, but not the hypoxia. So there really is nothing that's quite like climbing an extreme altitude mountain.

I could share some of my own experiences with this kind of hypoxia on Everest. One time, when I was sleeping in my tent and ran out of oxygen during the night at about 25,000 feet, I had this most vivid hallucination that John West, our expedition leader, had come up to the camp with a full bottle of oxygen, with no regulator on it. He had put it inside the tent and just opened it and filled the whole tent with oxygen. I was very grateful for him. I felt better right away. And the next morning, I was trying to figure out where the bottle was and how he had gotten up there in the middle of the night.

It dawned on me that obviously this was a hallucination and I knew I wasn't dreaming because it was so incredibly vivid. I was actually awake and trying to talk to Chris Pizzo who was next to me to tell him to say hi to John and everything, but he wouldn't even wake up. That was one, one interesting thing. Of course I got more hypoxic at that time because I had run out of oxygen.

Then on the way up from the South Col towards the summit, out on the balcony, which is the site of old Camp Six, I stood out on the very edge and I was sure that if I had jumped off from that point, I could have flown. I had this feeling that somehow spirits would come and, and just support me and fly me around the mountains and I could see all these wonderful places down below and visit friends and just get great views of all the mountains. And then somewhere back in the very depths of my hypoxic brain came this thought that, you know, Peter, maybe you're not thinking quite right.

And I had to literally bite my cheek to draw blood and hit my face. I took off my oxygen mask, hit my face, slapped my head around, and started to come out of it. That was an example of dangerous—inappropriate euphoria is the term we use for that sort of sensation.

NOVA: Tell us about your fall on the Hillary Step and how that might have been another effect of your hypoxic state.

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PETER HACKETT: I was coming down from the summit very exhausted. I had really stretched myself to get to the summit and hoped that I had left enough energy to return. I'd had nothing to eat or drink the whole 13 hours I had been out. And I got to the Hillary Step 300 feet below the summit, which is this very steep rock and snow obstacle. And it's a place where a lot of climbers get into trouble. Especially if there are no fixed ropes and there's no partner to belay them. That is if they're going solo. And I remember thinking I could jump down the Step, which of course was very foolish. And I wasn't sure how to negotiate it.

Eventually, I turned into it and started down and indeed I did fall. It was very unconsolidated snow and I took a fall of about 15 feet or so when I was stopped by my lower legs getting stuck behind a small rock outcropping. So I was flipped upside down, facing out, dangling at 8,000 feet over the Southwest Face. And trying to control my bowel

and my bladder and getting claustrophobic with the oxygen mask and ripping it off and realizing that didn't help and put it back on. It was quite a predicament. I'm sure that the hypoxia helped contribute to that fall and to an analysis of the whole situation.

But I was able to survive, I was able to eventually get upright because I clipped my ice ax into my pack and had kept it. Eventually I was able to make my way down to the bottom ledge, 18-inch ledge, at the bottom of the Hillary Step and then eventually I made my way around to the South Summit. I was alone. It was very late. It was getting dark. I was exhausted. I was psychologically and physically spent. I looked down below and I saw Chris Pizzo about 800 feet down below where he had been waiting for me for 2 1/2 or 3 hours, he was just about to leave. He had figured I had perished and he thought he might die on his way down to the high camp from there. So he made a tape. And on the tape he said, "If you find this tape, it means that I perished while I was waiting for Peter Hackett who was making a foolhardy solo attempt to the summit."

Of course this was Chris who had advised me that it'd be great for me to try a solo attempt to the summit a few hours earlier. On the tape he said, "If you find this tape, it is very important data. Please send it to Dr. John West at University of California, San Diego, La Hoya, California." He had tremendous presence of mind to make that even though he was very hypoxic and was getting hypothermic.

Eventually, I was able to meet up with him and we continued on down together to safety.

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