For someone that is hypotic, the question then is, "what happens if you're in an emergency situation, are you able to think quickly, are you able to think clearly about what you need to do to survive and get down?" (a comment from the NOVA broadcast on PBS).
The following are comments from the NOVA broadcast. Although high altitude climbing is a different set of circumstances, high altitude aviators can learn from the experiences of mountaineers..
The main link is http://www.pbs.org/wgbh/nova/everest/.
Take note that the acclimatization period for an Everest climb is TWO MONTHS!
NOVA #2506: Everest: The Death Zone
Broadcast Transcript
PBS Air date: February 24, 1998
To order this show for $19.95 plus shipping and handling, call 1-800-255-9424.
Following are comments from the show.
(Peter Hackett and Gail Rosenbaum are researchers investigating the effects of high altitude exposure)
PETER HACKETT: Judgement becomes impaired, a person becomes confused. They don't even know where they are as it gets worse. People hallucinate. So, all sorts of mental changes can take place as the brain starts to become more and more abnormal.
NARRATOR: ... as Carter's blood oxygen saturation falls, his breathing increases and his heart speeds up, trying to pump more blood made red with oxygen to his organs. Over time, more oxygen-carrying blood cells will be produced to carry the oxygen where it is most needed, to the muscles and brain. These physiological changes are called acclimatization, and they enable a person to survive at high altitude.
PETER HACKETT: Humans will start to deteriorate because of the high altitude at around 17,000 feet. Sleeping becomes a problem. Muscle wasting takes place. Weight loss takes place. This process of deterioration takes place much more quickly, the higher altitude that one goes to. So, over at 26,000 feet, it's called the Death Zone because acclimatization is essentially impossible. [...the Death Zone, an altitude where humans are only transient visitors.]
[Above 17,000 feet] the climbers are slowly deteriorating, their bodies literally consuming themselves for energy.
GAIL ROSENBAUM: The question then, we ask is, what happens if you're in an emergency situation, are you able to think quickly, are you able to think clearly about what you need to do to survive and get down?
PETER HACKETT: You can see how, in his condition, he could have not tied his rope correctly, not tied into his harness correctly, not clipped in the anchor correctly.
The breathing becomes unbelievably difficult. You feel like you are one huge lung. The heart rate at rest becomes higher and higher. The maximum heart rate becomes lower and lower, and as you go higher, those two get closer and closer together. And of course, when your resting heart rate equals your maximum heart rate, all you can do is rest. You can't do any more physical work.
[Because of the lower total pressure at altitude, pulmonary edema is another hazard climbers have to deal with.]
PETER HACKETT: With pulmonary edema, the blood vessels in the lungs start to leak. They leak this plasma fluid that is tinged with red blood cells, so it's a little pinkish. And the air sacs start to fill up with -- in different parts of the lung, usually to the right first, then the left. And eventually, they all fill up with fluid. The person starts coughing this pink, frothy sputum, can't get any air at all. Their blood oxygen level drops, and they go into cardiovascular collapse and die.
PETER HACKETT: One of the more pressing questions in high altitude medicine is, does climbing to extreme altitude cause brain damage? And we're going to be looking at that in a number of ways. One is by MRI scans. Some work indicates that some climbers who go to extreme altitude without oxygen do come back with slightly smaller brains. If cells of the brain actually die, the brain will get smaller. That's what happens with strokes and other things that cause brain cells to die. So, we'll look at the volumes of the brain by these special scans. These are unusual people, and they're going to a very unusual place. So, there are some opportunities here. David and Ed have been to altitude many times, and we might expect them to react a little bit differently than David Carter, who is a relative newcomer at these kind of extreme altitudes.
NARRATOR: Dr. Hackett has looked closely at the MRI scans, searching for abnormalities. He discovers that exposure to extreme altitude can leave its mark on the human brain. Hackett addresses the climbers.
PETER HACKETT: People like Ed Viesturs and others who make a career out of doing these very high peaks without oxygen may have some long-term brain abnormalities. Some studies indicate that they do have very minor, subtle, cognitive dysfunction, and it can be found only on psychometric testing. There's nothing obvious. And their MRIs show that there can be structural changes. We have yet to have a good correlation between the MRI structural changes and the cognitive changes. That's going to take more time, more studies, more research like we're doing now.
PETER HACKETT: And actually, the only abnormality we found was a very mild atrophy in the brain of Ed Viesturs, who was the one that has climbed many times to high altitude without supplemental oxygen. And what we'd like to do is follow him over a longer period of time to see if this is something that might actually progress with his high altitude career.
NOVA #2506: Everest: The Death Zone
Broadcast Transcript
PBS Air date: February 24, 1998
To order this show for $19.95 plus shipping and handling, call 1-800-255-9424.
Mount Everest, High Exposure: Humans at Altitude. See http://www.pbs.org/wgbh/nova/everest/exposure/. What happens to your body when it's exposed to extreme altitudes? How does the lack of oxygen affect the brain? If there were a mountain higher than Everest, would humans be capable of reaching the summit? Find the answers to these questions and much more. This page also includes:
The main link is http://www.pbs.org/wgbh/nova/everest/.