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Altitude Sickness and AMS, prevention and treatment.

Submitted by climbingcowboy on 2002-08-29 | Last Modified on 2010-02-25

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What causes altitude sickness?

At sea level the amount of oxygen (O2) in the air is 21%, as you get higher in elevation it stays 21% but the air gets thinner so there are fewer oxygen molecules for each breath. So to get enough O2 in your body your breathing rate has to increase. Now as you go up higher you have to get used to doing the same amount of work (hiking/climbing) with less O2 in your blood. As you get higher not acclimating (letting your body gradually adjust) will cause serious and deadly illnesses (I'll discuss later). This happens from going up to high to fast without proper time for your body to get used to less O2 and from not drinking enough water.

Certain NORMAL things should happen as a person goes up in altitude 1-Fast breathing, 2-Shortness of breath, 3-Unusual breathing pattern at night, 4-Increased urine output, you should urinate many times per night with proper hydration, BEER should NOT be used for proper hydration.

Carbon dioxide (exhaled air) levels tell your brain when to breathe, once you start breathing fast you decrease the level of carbon dioxide in your blood which won't affect you while your awake but when you fall asleep an unusual breathing pattern occurs. You'll breath normally, then you'll hold your breath (5-15 sec) and then breath rapidly, this is normal and does NOT mean you're sick, it will fade away as you acclimate. A medication called Acetazolamide (Diamox) can be helpful with this.

AMS (Acute Mt. Sickness):

Everyone experiences Mild AMS at an elevation higher then 8000', and a few at lower elevations. The symptoms of Mild AMS are a headache, fatigue, nausea, dizziness, confusion, wondering walk, and loss of appetite. Normal activity should not be difficult because of these symptoms and the symptoms should subside in 24-48 hrs with proper acclimatization. Be sure to be willing to admit you have AMS to YOURSELF and your partner, remember this is your life were talking about.

What should I do if I get AMS?

DO NOT GO HIGHER! STOP to acclimatize 24-48 hrs, or descend to a lower elevation where you last slept comfortably. Once you have acclimatized then continue backup. Taking aspirin and Acetazolamide (Diamox) will help treat mild symptoms such as a headache. The Diamox in specific will help you to sleep better and acclimate easier and should be started 24 hrs before you go up the mountain (check with your Doc on getting Diamox and make sure your not allergic). Basically this is how Diamox works, it takes carbon dioxide from your kidneys and puts it in the blood so you can breathe faster to take in more O2 and the higher levels of carbon dioxide will help get ride of the unusual breathing pattern at night. [page]

Moderate to Severe AMS: As symptoms get worse you won't be able to relieve them by medication, normal activity will become difficult, and decent will be the only cure. If you don't spot these symptoms early enough or don't go down when you do you will end up with one of two problems HACE or HAPE.

HACE (High Altitude Cerebral Edema):

This is an extremely dangerous illness basically your brain swells, and doesn’t work right. This can be FATAL in hours if you don’t' descend. With HACE a person has a change in their ability to think along with all the other symptoms mentioned above. These changes can be a number of things such as confusion, loss of coordination, and imaging/seeing things.
(Look at Jody Langford' article on his personal experience with HACE.)
To test for this besides asking them simple questions have the person try to walk a straight line (just like when you got pulled over by the cops). Make sure it's on easy ground not four feet deep snow or slanted ice, if they can't do it and/or fall down they have just failed and should be immediately taken down, at least more then 1600 ft or 500 meters.

HAPE (High Altitude Pulmonary Edema):

This is fluid in your lungs, another extremely dangerous illness with a larger window before its fatal. You'll get the basic symptoms as well as any or multiple of these. Extreme fatigue, coughing up frothy pink/bloody sputum, gurgling or rattling sounds heard when they breathe, the chest feeling very tight, and blue or gray lips and fingernails, (this is what they had in the movie Vertical Limit and the guy Philip had in the movie K2).


Drugs such as seen in the movies that they always give, such as Dexamethasone for HACE or Nifedipine for HAPE are useful but not applicable to the average climber/hiker, and should not be used without proper instruction. If oxygen is available it should be given in either situation. There are many studies that say that Ginko Biloba (an herb not the "herb") helps to prevent AMS; the average dosages are 120 mg twice a day, starting 4-5 days prior and continued during the ascent.

What You Should Remember:

1-Drink lots of water, 2-ascend slowly, 3-if anything seems weird wait to acclimatize, 4-any problems always descend, 5-this can happen to anyone at anytime at any elevation over 5000 ft.

Climb Safe and Always Have Fun!

Geoff Harris


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