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
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?
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
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.
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?
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.
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
NOVA: Can you comment on Everest being the maximum height people can climb to?
Is this a coincidence?
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?
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.
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
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
Eventually, I was able to meet up with him and we continued on down together to