Mt Rainier (14,411ft) as seen from sea level
Proper acclimatization allows your body to adjust to both the lack of available oxygen in the air and the lack of barometric pressure experienced at high altitudes. There are a few different ways to acclimatize, but your decision on which strategy to use depends greatly on your chosen route, climbing style, and personal genetics.
Climb High, Sleep Low:
By climbing up a few thousand feet each day but returning to camp at night, you allow your body to adjust to greater altitudes without the risks of an extended stay that would lead to high altitude cerebral edema (HACE) or high altitude pulmonary edema (HAPE). This isn’t very practical on anything in the lower 48, but it’s often applied on non-technical Alaskan routes and in the Himalayas.
Go Slowly:
By ascending at a rate of 1,000 vertical feet or fewer, you give your body time to adjust to the altitude. Although this seems to work very well for the vast majority of people, moving fewer than 1,000 feet a day requires a serious amount of time. As a result, this tactic only really works well if it’s combined with the Climb High, Sleep Low philosophy.
Go Fast:
On routes with a relatively small vertical relief, fast, fit climbers can often get up and down a route before the full effects of HACE or HAPE have a chance to hit home. If you apply this tactic, you’re almost certain to experience at least some symptoms of acute mountain sickness (AMS), but if you’re solid enough to approach a big mountain this way, you should be able to deal. The key thing in employing this tactic is to know the symptoms of HACE and HAPE and descend as soon as they appear in either you or your partner.
Get Ready Elsewhere:
What if you’re getting on a technical route on a big peak that requires you to move fast but is too long to get up and off before edema becomes a serious issue? Well, you simply apply one of the first three tactics to an easier route that goes to a similar elevation. For example, it’s not really a good idea to land in Alaska, walk to the base of the Cassin Ridge on Denali, and start climbing. Most people attempting the Cassin will first climb the West Buttress (or West Rib) to acclimatize. Then they can get on the goods and move as fast as they want.
Pressure Breathing:
By pursing your lips similar to whistling and making deep, forced exhales, you can purge more air from your lungs and allow yourself to get more back with each breath. The extra air intake helps make up for the lack of available oxygen in the air.
Diamox (Acetazolamide):
Diamox increases respiration rate and allows your body to metabolize more oxygen. Basically, it lets you acclimatize faster, but it’s not “real” acclimatization. If you don’t continually take the drug, your acclimatization can possibly wear off, leaving you in a tight place at high altitude. Diamox is also a mild diuretic, so your urine output increases and you dehydrate faster than normal. Not a good thing at high altitudes. Some climbers always use Diamox. Some never use it. The choice is yours.
Get Well Soon
Andy Chapman running up the West Face Direct of Tocllaraju (6032m) Cordillera Blanca, Peru.
If acclimatization methods do fail, and you find yourself suffering from a serious altitude illness, you have only one real choice. Get down now! This should be your first priority. If you are unable to descend, then you may still have some options.
Supplemental oxygen:
This is a rather contentious issue when it comes to climbing styles. Taken in the context of a rescue, however, supplemental oxygen can and does save lives. If you cannot get a victim down to a reasonable elevation or if a descent does not reverse the symptoms, then letting a person breathe bottled oxygen makes more of a difference than anything else.
Dexamethasone:
Dexamethasone is a steroid that’s used to decrease swelling in the brain. Whether taken in pill form or injected, it acts fairly quickly to reduce the symptoms of HACE and can buy you a few hours to get to a lower elevation. You don’t want to break out the big guns for a standard case of AMS, but when things get really hairy, it can make all the difference.
Gamow Bag:
These portable pressure chambers can be brought to base camp and used to create an artificial low-elevation climate. The victim is sealed inside and a foot pump is used to inflate the bag and increase the barometric pressure of the air within. Using this system, the bag can lower the effective altitude up to 5,000ft (1,525m). They’re only common on very large expeditions (since they’re not exactly light or cheap), so don’t count on the group camped next to you in some remote valley to have one.
Source: Medicine For Mountaineering, James A. Wilkerson M.D
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Tags: alpine climbing, climbing, outdoor survival