Altitude Sickness:

The Himalaya begins where other mountain ranges leave off. Everest Base Camp is at the foot of huge mountains, yet it is 1,000 meters higher than the highest point in Europe . Your body can adjust to these altitudes, but only if given enough time. Being in a hurry in the mountains of Nepal can be deadly! It also seems that excessive exertion at altitude (e.g. carrying a heavy pack) may predispose some people to altitude illness. So it may be advisable to carry a light pack and use a porter (they are not expensive).

Acclimatization's the word used to describe the adjustments your body makes as it ascends. You should adjust your schedule so that you average no more than 300 meters per day of ascent above 3,000 meters. If you fail to allow time for acclimatization, you may develop symptoms of AMS. The AMS may be mild enough to go away with a day's rest or if ignored may lead to death. All that is required to ensure a safe trek is basic awareness of AMS, and a willingness to rest or descend if you develop symptoms. As a result of the growing awareness of altitude problems there is only one death from AMS in Nepal out of every 30,000 trekkers. Even these deaths would be avoidable if everyone knew how to respond to AMS. There are no reliable figures for casualties among porters. Recognizing Acute Mountain Sickness

Acute Mountain Sickness (AMS) can develop at any altitude over 2,000 meters. The early symptoms are 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.

A person suffering from AMS may not have clear thinking and may have to be forced to descend. Even if someone is willing to descend they should never be allowed to descend alone. Keep descending until the person shows some sign of improvement, usually after 300-500 meters of descent. Even if the diagnosis is not clear, but might be AMS, you should descend. You can always re-ascend when the person feels better. It is best to start descending while the person who is ill can still walk. If the person can no longer walk, a yak or horse might be obtained. Porters can often be found to carry a sick person down. Do not wait for a helicopter. If you choose to administer oxygen or medications do not delay the descent to watch for improvement.

In summary, if you are not doing well at altitude, most likely you have some mild symptoms of AMS. Rest at the same altitude until you feel well. If you are getting worse at the same altitude, descend to at least the last point at which you test well. If you are not sure of the diagnosis, err on the side of being too cautious. Remember severe altitude sickness is entirely preventable if you follow these guidelines.

Prevention of Altitude Illness:

1. 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`.
2. 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.
3. Other preventive strategies such as Gingko Biloba which was once thought to be useful for altitude illness prevention has not been found useful in several studies. Salmeterol (Serevent) inhaler used to treat asthma can help prevent HAPE and may be used by HAPE susceptible people prophylactically. For persons allergic to sulfa drugs and for 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 completely. Diamox can also be used to treat mild to moderate symptoms. If symptoms persist or worsen at this altitude, 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 descent can be detrimental for patients with HAPE. Severe HAPE patients should be carried down if helicopter evacuation is not possible.

Other treatment modalities to help during descent

1. Diamox is generally useful for mild to moderate AMS. Dosage: One 250 mg tablet two or three times a day.
2. Dexamethasone - is a very potent steroid used in HACE temporarily to facilitate descent. This drug improves the symptoms but does not help acclimatization. It is not recommended to ascend while still taking this drug even if one is symptom free. Dosage: 4 mg every 6 hours.
3. Nifedipine - is useful in HAPE by lowering pressure in the pulmonary blood vessels and thereby decreasing fluid in the lungs. This drug also lowers blood pressure. Sildenafil (Viagra) is increasingly being used in treating HAPE.
4. Oxygen - is very useful particularly for HAPE.

Three golden rules to avoid dying from altitude illness:

1. Learn the early symptoms of altitude illness and recognize when you have them. Remember, you may be the only person in a group with symptoms.
2. Never ascend to sleep at a new altitude with any symptoms of AMS.
3. Descend if your symptoms are getting worse while resting at the same altitude.