High Altitude Pulmonary Edema (HAPE) and High Altitude Cerebral Edema (HACE) are perhaps the biggest medical threat to climbers. In the most simplistic terms, both conditions cause fluid to leak from cells in the body. In HAPE, this occurs in cells inside the lungs, which causes the lungs to fill with fluid at a rate that the body can’t manage, essentially causing the victim to drown in their own fluids. The same effect is seen in HACE, except this occurs in the brain vice the lungs. Both conditions are generally a more serious follow-up to acute mountain sickness (or altitude sickness).
The remedy for all these conditions is to descend as rapidly as possible. As the cause is the lower air pressure at increasing altitude, descending into areas of high air pressure (i.e. lower altitude) will usually stop and/or reverse the symptoms. Of course rapid descent isn’t always possible. It may not be possible because the climber is on a section of the mountain where the only way down is to continue up to a certain point where the route down becomes acceptable. Or perhaps the symptoms are serious enough that not even a rapid descent can rectify the issue. A potential solution is a life-saving device that many guide companies carry on expeditions: a Gamow Bag. This is an inflatable (and thus portable) hyperbaric chamber that when inflated, can reduce the virtual altitude (i.e. increase the air pressure) inside the bag by a few thousand feet. For climbers suffering serious effects of altitude sickness or HAPE or HACE, this could be their only option.
There are a number of ways to prevent the occurrence (or severity of) these conditions. But the easiest thing to do is not rush- acclimatization to altitude is key. This is part of the reason why Everest climbers tend to make the multi-week trek up to Everest Base Camp (EBC) at 17,500 feet. The long trek gives the climbers a chance to acclimatize to the higher and higher altitudes, thereby lessening the chance of serious effects.
Interestingly I generally thought of HAPE and HACE as really high altitude conditions, i.e. a condition that effects climbers on Everest, the Seven Summits, and other peaks of seriously high altitude. But a little reading and research showed that these conditions can happen at much lower than (I) expected altitude. This article from 2009 shows a climber succumbing to HAPE at just above 10,000 feet, and a climber was lost to HACE on Mt. Shasta (14,179ft), as described here. While the actual altitude is of course important (the higher the mountain the higher the chance of the occurrence of the conditions), it seems that rate of ascent and personal physiology also play key roles here. Does a slow and steady ascent of a 20,000 foot peak in the Himalaya present a higher or lower risk of HAPE or HACE or AMS than a fast ascent of a 10,000 foot peak in Oregon?
One of the challenges, that I can at least personally attest to, is to figure out if the symptoms one is experiencing are related to one of the above conditions, and how serious it may be. For example, while on Mt. Adams last year, I had no issues as we climbed up into and established high camp at roughly 9,000 feet. But after a few minutes of sitting relatively still in the tent, my head began to hurt, I was dizzy and had pretty bad nausea, and I felt like I didn’t want to go on. Our guide told me to just lay down in the tent for a while and see how I felt. As I laid there for what might have been an hour or so, I thought about whether I had something more serious. But after a while, I started to feel better. I forced a little food into me, and I felt even better. Finally, by the time we finished dinner, I was feeling normal again. For me, the issue was that we had no real chance to acclimatize to the altitude, and my body took issue with that. After resting a bit, my body finally became accustomed to the air pressure, and my symptoms subsided. This wasn’t any of the serious conditions, but at first I didn’t know. By way of comparisson, my partner on the climb seemingly had no issues at all. Neither of us had climbed to that altitude previously, but his body seemed to adjust to the altitude gain far faster than mine was able to. As this obviously had a big element of personal physiology, I am now more acutely aware of how I need to prepare for altitude. I should find ways to better acclimatize, drink more water and eat more food on the way up (to prevent dehydration…which exacerbates altitude sickness).
Guides have a particularly important role to play in this. Many climbers, especially those who are beginners or new on a specific mountain, are not keenly aware of the conditions, their symptoms and effects, and what to watch out for. Thus a headache or dizziness might just be ignored. It leaves the guide guessing, using subtle clues as to peoples conditions. On Adams, for the better part of an hour I literally could not move. As soon as I lifted my head the world began to spin. But the guide certainly didn’t seem worried (which certainly made me feel better). But he knew that based on what I was complaining about and how I was acting up to that point, I just needed some time to adjust. And he was right.