Altitude Sickness, Acute Mountain Sickness (AMS) can develop at any altitude over 2,000 meters. The early symptoms are a headache, extreme fatigue, and loss of appetite. Some people become breathless at rest. AMS is the result of fluid accumulating in parts of the body. Where it does not belong: in the brain, in the lungs or both, when mild symptoms develop, it is a signal that you must stay at that altitude until symptoms have gone away. Never ascend with any symptoms of AMS! Usually, within one or two days, you will feel well and can continue your trek.
If you are resting at the same altitude and your symptoms are becoming worse, then it is necessary to descend. Worsening symptoms of AMS include increasing tiredness, severe headache, vomiting, and loss of coordination. There are signs of High Altitude Cerebral Edema of HACE. HACE can lead to unconsciousness and death within 12 hours if progressive symptoms are ignored. Increasing shortness of breath, cough, and tiredness are signs of High Altitude Pulmonary Edema or HAPE. HAPE can also be rapidly fatal if ignored.
Prevention of Altitude Illness:
- Having a sensible itinerary is the most important way to avoid altitude illness. It is recommended to climb not more than 1,000ft (300m) a day above an altitude of 10,000 ft (3,000m). If the terrain is such that this is not possible, one needs to have two rest days, e.g. 2 rest days are recommended at Namche Bazaar where 2,000ft (600m) are gained in 1 day from Phakding for most itineraries. Having flexibility with 1-2 extra days built into your schedule will allow you to rest when you are not feeling well and help avoid altitude illness. It also helps to `climb high` and `sleep low`.
- Use Diamox-which blocks an enzyme in the kidney and makes the blood acidic which is interpreted by the brain as a signal to breathe more. Diamox therefore, enhances the physiological response to altitude by increasing the rate and depth of breathing and it also acts as a mild diuretic. Side effects of the drug are: tingling of fingers and toes and tingling around the mouth. Sulfa allergic individuals are recommended not to take this drug. Prophylactic dose of Diamox is half or one 250mg tablet twice a day. Use of Diamox will not mask the symptoms of altitude illness if it is to occur. Start taking Diamox the day before ascent to 10,000 ft (3,000m), continue it through your ascent to higher altitudes and stop when you start descending.
- Another preventive strategy such as Gingko Biloba which was once thought to be useful for altitude illness prevention, has not been found helpful in several studies. Salmeterol (Serevent) inhaler used to treat asthma can help prevent HAPE and may be used by HAPE susceptible people prophylactic ally. For persons allergic to sulfa drugs and abrupt ascents, it is possible to use dexamethasone, a very potent steroid drug.
Treatment of Altitude Illness:
For mild symptoms, one can stay at the same altitude to see if symptoms will resolve and ascend when symptoms have resolved entirely. Diamox can also be used to treat mild to moderate symptoms. If symptoms persist or worsen at this altitude, the descent is required.
For severe symptoms of HACE or HAPE, descent must begin immediately whenever feasible. Helicopter evacuation may be essential for descent unless there is rapid improvement with medical treatment, and walking down is feasible. Physical exertion even when it is for the descent, can be detrimental for patients with HAPE. Severe HAPE patients should be carried down if helicopter evacuation is not possible.