Acute mountain sickness is better prevented than treated.
Peter Hackett, M.D.

The most effective way to prevent altitude-related problems is to give your body sufficient time to adjust to your new environment. Gradual acclimatization is important because the amout of atmospheric oxygen available for breathing at high elevations is considerably less than it is at sea level. At 10,000 feet (3000 m) the partial pressure of oxygen is 30 percent lower than at sea level, at 18,000 feet (5,500 m) it's 50 percent lower. With less oxygen in the air, the ability to perform tasks, even easy chores such as getting dressed, may be exhausting until the body adjusts. The lack of xoygen might also be responsible for triggering the symptoms of AMS.

In popular Himalayan trekking regions such as Nepal, trekkers are encouraged to ascend to highelevations at a slow rate that allows everyone in the party to acclimatize properly, In Tibet, gradual acclimatization is difficulty due to the extreme elevation of the entire country; flying into Lhasa means landing at an elevation of around 12,000 feet (3660 m), while driving to Tibet from Nepal involves crossing Thang La (17,060 ft, 5200 m), followed by a night in Dingri or Shegar at about 14,000 feet (4270 m).

For most people the physical adjustment to higher elevations can happen rather quickly, requiring as little as a night of rest at the new elevation. If you fly into Tibet, the ideal situation is to spend three or four days in Lhasa before setting off on a trek. The first day should be treated as a rest day, though a half day of sigh tseeing at the Jokhang or strolling the Barkor market is fine. During the next few days be more active and try to spend at least a fw hours every day going for walks, preferably into the hills. Dayhikes will help you warm up for your trek and the exercise seems to help the body adapt to the altitude. If your time is limited, a minimum of two nights should be spent in Lhasa before starting a trek that ascends above 14,000 feet (4270 m) on the first day.

If you are driving into Tibet from Nepal, Consider spending a night acclimatizing in Nyelam before crossing Thang La. The stopover can make a big difference as to how you adapt to the higher elevations over the next few days.

Once a trek begins, the rule of thumb is not to ascend at a rate of over 1300 feet (400 m) per day. For every 3000 feet (1000 m) of ascent, plan on taking one entire rest/acclimatization day. If you're feeling well, use these days to explore nearby valleys or climb onto a ridge for panoramic views; it's better to stay active than laze around camp.

Some people just don';t acclimatize well at high elevations, regardless of the precautions taken and how slowly they ascend. One medication that has been found useful for preventing the symptoms of AMS is acetazolamide a few hours before the flight to Lhasa, or the morning depart of departure from the Nepal-Tibet border. The usual dosage is one 250 mg tablet, two times a day, though some people prefer to take only half a tablet each time. (The smaller dosage is still effective but helps reduce the need to urinate frequently.) Do not take acetazolamide if you are allergic to sulfa drugs, It has no known harmful side effects and can be takern for several days, even weeks, though some people experience an can be taken for serveral days, even weeks, though some people experience and unpleasant tingling feeling in the fingers, toes, or lips. Be sure to drink plenty of fluids to prevent dehydration while using this drug.

Maintaining an adequate fluid intake at high elevations may also be helpful in preventing altitude sickness. Most people need between two to five quarts (liters) of liquid per day to remain properly hydrated in Tibet's dry mountain climate. The color and volume of your urine is generally a good clue: drink enough to keep it clear and abundant.

Acute Mountain Sickness

AMS is the general term for a number of high altitude--related symptoms. The severity of these symptoms and the rate of their onset depend on factors such as how fast a person ascends at high elevation, the maximum elevation reached, and the susceptibility of each individual. Most people who ascend to elevations between 11,000 to 20,000 feet (3,350 to 6100 m) will experience one or more of the following mild symptoms of typical AMS: headache, lack energy, lack of appetite, nausea, vomiting, shortness of breath while exercising, difficulty sleeping at night, light-headedness, peripheral edema (swelling of the hands, feet or face)(, Cheyne-Stokes breathing (a condition of unusual respiration patterns), or feelings similar to those accompanying a case of the flu.

Any of these symptoms can appear on its own and be unrelated to an increase in elevation. If more than one symptoms is present, the likelihood of having AMS is increased. A headache is one of the most common symptoms of AMS, though other factors such as overexertion, dehydration, and prolonged exposure to the intense mountain sunlight may also be the cause. Headaches of this type will usually go away after resting, having a cup of hot soup or tea, or taking aspirin or acetominophen. An AMS headache does not go away so easily and may linger on despite medication. Waking in the morning with a headache is also a sign of not acclimatizing properly, especially if the headache does not go away after you have moved about or taken aspirin. A severe or progressively worsening headache, particularly if accompanied by vomiting, lassitude, or ataxia (loss of balance), could well be the first sign of HACE.

In general, the best approach is to consider andy symptom observed at high elevations to bel altitude-related until it can be proven otherwise. Mild to moderate AMS symptoms are typically self-limiting and improve on their own after a day, or can be treated by stopping an ascent. Acetazolamide may be helpful for relieving AMS symptoms, though it is improtant to realize that is is not a cure for AMS. Acetazolamide can also be useful for stopping altitude-related insomnia and irregular breathing. Aspirin or acetominophen can be taken along with acetazolamide to relieve altitude headaches. Pain medications with codeine should be avoided because they can suppress the respiratory system. Depressing the body's blood oxygen levels. The same is true for sleeping pills, barbituates, sedatives, and alcoholic drinks. Administering oxygen (some rooms at the Lhasa Holiday Inn have oxygen outlets near the beds) is sometimes helpful at a flow of two liters per minute, though oxygen is not necessarily curative and the problems could return once it is discontinued.
If symptoms do not improve or become worse despite treatment, a more severe stage of AMS is indicated and further action is necessary to prevent deadly complications such as HAPE or HACE. Although several drugs are known to temporarily relieve these symptoms, the most guaranteed means for alleviating AMS is to DESCEND TO A LOWER ELEVATION.

Often a descent of 1000 to 3000 feet (600 to 900m), or to the elevation where the person last felt well, is all that is needed for rapid improvement. After a few days of rest, it may be possible to resume the trek and continue beyond the highest elevation previously gained if care is taken to acclimatize during the re-ascent.

Descending to a lower elevation is not always practical in Tuibet; with serious cases of AMS the only choice may be evacuation by plane to the lower elevations of Kathmandu or to Chengdu in China's Szechuan province. Vehicle evacuation to Nepal may be the quickest alternative from the Everest region, though this involves crossing Thang La to reach the border.

Some people refuse to accept that they could have an altitude-related problem, or refuse to admit it to others in their group for fear of upsetting everyone's trekkingplans. This is especially true with people who have haad previous experience at high altitudes, but ascending to high elevations without complications in the past does not mean altitude problems cannot occur the next time.

Something-perhaps diarrhea or a cold-can tip the balance, causing symptoms of AMS to manifest. There are cases of mountaineers who successfully climbed Mount Everest, yet died later of severe mountain sickness while climbing a lower mountain. The majority of AMS deaths seem to occur when people deny their situation.

High Altitude Pulmonary Edema (HAPE)

HAPE and HACE are considered the most dangerous forms of altitude sickness. Anyone suspected of suffering from their symptoms should be watched carefully; both illnesses can worsen overnight, becoming life-threatening in as little as eight to twelve hours after being recognized. In many cases HAPE and HACE occur together.

HAPE occurs when the alveoli, or air spaces, that comprise most of the lung tissue become flooded with fluids. One of the first symptons is a dry, persistent cough that is present during exercise as well as at rest. Coughs caused by the dry air are common in Tibet, but a persistent cough that is not associated with a cold or a chest infection is a warning sign of HAPE. Other important symptoms are excessive shortness of breath and a long recovery time after exercise. Most people will experience some shortness of breath after being active at high elevations, but unusually labored breathing compared to others in the group could be due to HAPE. In HAPE's more advanced stages breathlessness occurs even after resting fifteen to twenty minutes. The cough becomes wet and eventually produces frothy sputum (phlegm) that may have a pinkish color or be streaked with blood. Sometimes a gurgling sound can be heard in the chest. At this point death could be only hours away.
Once HAPE has been diagnosed or is highly suspected, it is imperative that the affected person descend immediately to a lower elevation, even if it's late at night. If the person cannot walk unassisted, he or she should be carried in a litter or ride on a horse or yak. If oxygen is available, an initial flow of four to six liters perminutes should be used for fifteen minutes, followed by two liters per minute. Oxygen is sometimes helpful for mild cases of pulmonary edema, but it is usually not curative without descending to a lower elevation. Recovery after descent can be rapid. There is no completely effective drug regime for treating HAPE once the symptoms are present.

High Altitude Cerebral Edema (HACE)

HACE occurs when the brain cells fill with abnormal quantities of fluid, preventing the brain from functioning normally. The symptoms of HACE are basically the same as a moderate case of AMS, but are much more severe and unresponsive to treatment. It is important to differentiate between the two; the condition of someone with HACE can deteriorate rapidly, causing him or her to go into a coma or possibly resulting in death. Important signals to watch for are ataxia (lack of muscular coordination or balance), a several headache, and vomiting. A headache caused by AMS can be difficult to vomiting and/or ataxia is not a good sign and must be treated as a preliminary stage of HACE. Lassitude (unusually intense, persistent weariness or marked indifference to everyday events such as eating or personal hygiene), mental confusion, and unusual behavior may also be present.

Ataxia is probably the best indication that a person has HACE. If someone staggers into camp at the end of the day looking quite ill, an easy test for ataxia is to have him or her walk slowly for ten to fifteen feet (3 to 5m), heel to toe, along a line drawn on the ground (heavy hiking or climbing boots should first be removed). A normal person should not have any difficulty passing this test; someone with mild ataxia will sway and be off-balance but can complete the test. Suspect HACE if the person steps off the line, staggers, or falls down. However, if a person has no other signs of AMS the lack of coordination or balance might be due to hypothermia or exhaustion. If the ataxia has not improved after he or she had warmed up with a hot drink and had a rest, preparations should be made to go immediately to a lower elevation. Ataxia may worsen quickly, forcing the victim to be carried in a litter. Oxygen should be administered at a flow of four to six liters per minute if available. Dexamethasone -a 10 mg injection initially, then 6 mg every six hours for no more than three or four days - is helpful when descent is impossible, or can be used in conjunction with descent to allow the victim to assist with the rescue efforts. This powerful anti-inflammatory steroid should only be administered by a doctor.

Respiratory Ailments

Coughs and colds caused by the dry air in Tibet are a common problem with trekkers. Throat lozenges and hard candies are good for soothing irritated throats. Aspirin or acetominophen with codeine will help control coughs, though codeine has a tendency to suppress the respiratory system, making its use at high elevations questionable. If a person is coughing up phlegm, use a cough expectorant rather than a cough suppressant. Yellow or green phlegm is probably a sign of a chest infection.

The common cold is a viral infection. Runny nose, stuffy head, and a low-grade fever are the usual symptoms. Aspirin or acetominophen can offer some relief, as can nasal sprays, cold tablets, or antihistamines.

Sinusitis is a bacterial infection of the sinus passage, which are located beside the nose and the eyebrows. Headache and localized pain at the sinuses help differentiate it from a common cold. Treatment with an antibiotic such as cephalexin is sometimes necessary.

A chest cold that produces thick yellow or green phlegm accompanied by a fever is probably bronchitis, a bacterial respiratory infection. Steam inhalants, especially with eucalyptus oil added, can help break up congestion in the lungs. Using antibiotics is not necessarily recommended, but they can help prevent more serious complications such as pneumonia. Ampicillin, trimethoprim / sulfamethoxazole, or erythromycin are usually prescribed.

Pneumonia, a erythromycin chest infection than bronchitis, occurs when the alveoli in the lung tissues fill with infected fluid. Persistent coughing, chest pain, difficulty breathing, and a fever of more than 102°(39°) are usually present. Sputum will be yellow or green, but streaked with blood and often containing pus. Ampicillin, penicillin, or cephalexin are recommended antibiotics for pneumonia.

Hypothermia

Also referred to as exposure, hypothermia occurs when the body's internal temperature drops to a dangerously low level. The combination of being wet, cold, and physically exhausted often leads to hypothermia. If it is not treated properly, it can quickly lead to death, even at temperatures well above freezing.

The symptoms of hypothermia are often subtle and difficult to detect. When a body becomes cold, its natural reaction is to shiver, sometimes uncontrollably. Muscular coordination decreases and simple tasks, especially those using the hands, become difficult. If body temperature continues to fall the body's mechanism for shivering can actually stop; this is a classic sign that someone is suffering from hypothermia. In some cases, a severely chilled person may not longer realize he or she is very cold. Mental confusion, unusually behavior, slurred speech, and ataxia can also occur with hypothermia. If no attempt is made to raise the body temperature, unconsciousness or even death will follow.

Anyone showing the first signs of hypothermia should seek shelter from the conditions causing the problem, particularly the wind. Wet clothes should be removed and the person should drink hot, sweetened liquids; a quick calorie boost is important. If the person cannot be warmed by conventional means, he or she should be stripped to the skin or a layer of underwear and put into a sleeping bag with another person dressed similarly.

Diagnosing hypothermia is easier if you have a low-reading thermometer. Body temperatures a degree or two below normal (98.6?,37?) are not unusual; temperatures below 96°(35.6°) are probably due to hypothermia.

Effective waterproof raingear and protection from the wind are essential for preventing hypothermia. Avoid wearing cotton clothing against the skin; when cotton gets wet it loses 90 percent of its ability to retain heat. Instead, wear wool, silk, or synthetics such as polypropylene next to your skin; they remain warm even when wet.

Frostbite

Frostbite, the freezing of body tissues, most commonly affects the fingers, toes, and face. It can occur due to internal heat loss in the extremities or through direct exposure to cold temperatures and windy conditions. Hypothermia and the constriction of the blood vessels caused by high elevations can also be contributing factors. Initially the affected areas feel cold, painful, and may be pale. As the tissues freeze, the pain subsides to numbness.

Prevention is the best remedy, for many cases can be avoided by wearing adequate protection from the cold. Good footwear is essential in snowy conditions, particularly for winter treks. Wear warm gloves and use a scarf or balaclava to protect the face from wind and cold.

If you think you have frostbite, try to rewarm that part of the body by placing it under your armpit, between your legs, or even on someone else's stomach. If the frostbite is minor, the color and feeling will eventually return. In more serious cases the frozen tissue will feel hard, cold, and be unresponsive to warming. Do not rub the affected area with snow or try to restore circulation by rubbing it vigorously with your hands; do not immerse it in water to encourage thawing. Less damage will be done to a frozen foot by walking out on it than by thawing it too soon. A frozen foot or hand should be left alone until a medical facility can be reached.

Sun-related Problems

Tibet's high altitude and thin atmosphere allow the sun's solar radiation to strike the earth with unusual intensity. Very little of the ultraviolet light is filtered out, causing skin to burn much more rapidly than at lower elevations. A sunscreen with a sun protection factor (SPF) of 15 or more is recommended to guarantee protection of exposed skin. Sunscreens with para-aminobenzoic acid (PABA) in an alcohol base are considered the most effective and longest lasting, but they do tend to stain light-colored clothes. Lip creams and balms are also sold with SPF ratings; zinc oxide creams provide 100 percent blockout. In a pinch use toothpaste as a substitute. Sun hats are essential; broad-brimmed Tibetan felt hats cost only $5 to $7(U.s) and can be purchased in the Lhasa and Shigatse markets. Inexpensive woven straw hats are also available.

Treat sunburn as you would any other burn. For skin that is red and painful, use a soothing cream such as aloe vera. If blisters have formed try not to break them. For particularly bad burns, bath the area gently with cold clean water and cover with a bandage that won't stick to the burn.

Snowblindness occurs when bright sunlight reflected off snow, ice, or water burns the cornea of the eye. It can happen after only a few hours of exposure, but is easily prevented with adequate eye protection. Sunglasses with polarized lenses are fine around cities and on the trail, but for winter treks or visits to the mountaineering camps near Mount Everest or other mountains, darker glasses are needed that will filter out all ultraviolet light. These glasses typically have hoods on the stems and are known as glacier glasses.

Snowblindness is hard to detect because initially there is no pain nor other sensations to warm that the eyes are being burned. Symptoms usually develop in the evening after exposure. The eyes become painfully irritated, feeling as if there is sand In them. They usually appear watery and bloodshot, and the eyelids may swell shut. Cold compresses will temporarily ease the discomfort; aspirin or another analgesic can be taken for pain. An antibiotic ophthalmic ointment or drops can help soothe the eyes and shorten the recovery, which is usually two or three days.

Animal Bites

Animal bites should be taken seriously, for the chances are high that an infection will occur. Unfortunately for trekkers, the dogs in Tibet do not seem to like the smell of foreigners and bites are not uncommon. If you are bitten, immediately wash the wound site with soap and water, then rinse it for at least twenty minutes, preferably with an iodine disinfectant or with water purified with a double dose of iodine. It is especially important to wash out any saliva that might have entered the wound. Cover the bite with a sterile bandage and watch for signs of infection.

The presence of rabies in Tibet must be assumed. Because it is transmitted by the saliva of an infected animal, the bite must break the skin to spread the infection. It is easy to determine if an animal has rabies; observe the animal for ten days, if possible, and if it is still alive and healthy at the end of that time it was not infected. If the animal is unavailable or if it dies, the bitten person should begin the series of rabies immunization shots as soon as possible. A delay of a week to ten days is usually not a problem, but the sooner the series begins the better. The rabies vaccine is available at the Renmin, or People's Hospital, in Lhasa and at a number of clinics in Kathmandu.