Acute Mountain Sickness


Altitude illnesses result mostly from swelling from leaky capillaries caused by low oxygen levels. These symptoms develop while sleeping at night. The usual symptoms are a dull headache and mild insomnia. It comes on during the first to third day at altitude and goes away in about three days. Infrequently it can persist and progress to Acute Mountain sickness (AMS). The early symptoms are a feeling of fatigue and irritability then headache, malaise, anorexia and even nausea and vomiting. These symptoms are like flu or a hangover. Exertion will make the symptom worse. If acute AMS does not progress further it is not life threatening and can be treated without descending to a lower altitude. 

Swelling of the face and hands can occur independent of the previous symptoms. Infrequently there is periodically interrupted breathing, sleep apnea, which can awaken one’s camp mates and sometimes cause awaking of the patient with anxiety or vivid nightmares. These symptoms do not progress to life threatening levels.

AMS can progress to lung swelling, high altitude pulmonary edema (HAPE), or brain swelling, high altitude cerebral edema (HACE). Both of these are rare but can be life threatening if the patient is not immediately moved to lower altitude. 

AMS is capricious. It can occur to someone who has traveled to altitude previously without symptoms but there are those who routinely have symptoms at altitude. AMS can occur from accents of 5000’ and above. It is more likely with rapid accents. Some symptoms would be expected with a rapid accent to 10,000’. Someone with severe AMS should not ascend further until symptoms resolve. Even though full acclimatization can take weeks, sleeping at altitude for a night or two before going higher can be beneficial. Previous time spent at altitude, even weeks before a trip, can be helpful.

Treatment includes taking in enough water and salt to produce an increase in urine output to clear and copious every four hours. Take aspirin, ibuprofen, or acetaminophen to treat early onset of a headache. High altitude medical experts do not recommend sleeping medication. Experienced mountaineers, however, have found that Ambien is safe and effective. Benadryl  50 to 100 mg is very safe and can be effective for some people. Benadryl does not require a prescription. Drugs labeled Benadryl sometime have stimulants added. The active ingredient should be diphenhydramine only. Avoiding a heavy evening meal might help. High levels of physical fitness have no effect on AMS.

Diamox (Acetazolamide), a diuretic, is recommended for going to 10,000’ from sea level in one day. Starting at 250 mg, one pill, twice a day two days before the trip is recommended. Take the the first pill of the day early in the morning and the second in the late afternoon to minimize night time urination. Diamox will increase urine output and therefore requires an increase in water and electrolytes (salts) intake. This drug often produces an unsettled feeling, numbness and tingling of the hands, toes, or lips, and lost of taste for carbonated beverages. These symptoms usually occur after a day or two. This is evidence that drug is effective. When these symptoms occur the dose should be reduced by half, 125 mg, by breaking the pills in half. Diamox causes increased breathing, particularly at night and thereby speeds up part of the acclimatization process helping to relieve symptoms. Some mountaineer rescue workers who know they will develop AMS symptoms at altitude start the drug on the first travel day. The drug can be discontinued on descent.

Although Diamox is generally a safe drug, anyone who decides to take it should check with their doctor as well as read about the reasons that certain people should not take this drug. Diamox and Ambien are prescription drugs and no one should take these drugs without approval by their primary care physician.

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