Just in time for the travel season, here is a guide to travel and altitude sickness that can help you prepare for any destination.

The term "altitude sickness" describes a group of disorders affecting the lungs, brain, and central nervous system after travelers arrive at an elevation over 8,000 feet (2,500 meters).

The most common altitude-related disorder is acute mountain sickness, or AMS. The hallmark diagnostic feature of AMS is headache. AMS occurs in persons who have recently arrived at altitude greater than 8,000 feet suffering dull, throbbing headache, worse when bending down or straining to reach, and more intense at night and during the morning. Other AMS symptoms may include vomiting, nausea, fatigue, vertigo, or insomnia. Mountain sickness may strike as soon as 1 hour after arrival, but more usually develops within 6 to 10 hours. It can be relieved by descent to a lower elevation, and usually dissipates with or without treatment in 3 to 7 days.

There is a set of factors that do not protect against AMS, including:

Gender
Physical condition
Pre-ascent training
Previous high-altitude experience
Smoking or not smoking
Youth or age

Counterintuitively, persons in good physical condition are actually more like to suffer AMS, not less. Younger, fit individuals are more likely to engage in vigorous physical activity and to go higher and faster than the less athletically inclined. Moreover, common conditions such as coronary artery disease, mild chronic obstructive pulmonary disease, diabetes, hypertension, and pregnancy do not increase (or decrease) susceptibility to AMS. Persons under the age of 50, however, are more susceptible than older adults.

What are the factors that increase risk of AMS? The most important risk factor is previous incidence of altitude-related illness. If you have been to a given altitude before without symptoms, you can probably return to that altitude safely. However, if you have had problems at an altitude before, you will probably have problems at that altitude later.

At the other end of the spectrum of altitude-related disorders is high-altitude pulmonary edema. It less common than mountain sickness, but also strikes even the physically fit. About 8 per cent of climbers who develop acute mountain sickness at altitudes greater than 15,000 feet go to develop HAPE. HAPE is diagnosed by a combination of two symptoms and two signs in the setting of a recent gain in altitude:

Symptoms (at least 2):

Dyspnea (being out of breath) at rest
Cough
Weakness or decreased exercise performance
Chest tightness or congestion

Signs (at least 2):

Rales or wheezing in at least 1 lung field
Central cyanosis (blue color not just in the fingers but also in the lips and mouth)
Tachypnea (breathing fast)
Tachycardia (racing heart)

The symptoms of HAPE usually begin 1 to 3 days after arrival at a high altitude. There may be a dry cough, followed later by coughing yellow sputum and/or blood. A mild fever of up to 101° F (38.5° C) is not uncommon, although higher fever suggests pneumonia. These symptoms are caused by a condition analogous to a high-pressure leak in the lung. When the concentration of oxygen in the bloodstream goes down, the pulmonary artery constricts, and pulmonary artery pressure increases. This vasoconstriction, however, does not occur evenly throughout the lung. Some regions of the lung become engorged with blood, and the capillaries relieve their pressure by pouring water and proteins into the lung. As small patches of the lung are "flooded out," the lungs absorb even less oxygen and the pathological process accelerates.

HAPE is a medical emergency, requiring immediate treatment on site and evacuation to lower altitude. Mountain sickness, however, is treatable.

The first thing travelers can do to avoid mountain sickness is to travel to high altitudes slowly. If you trek to a high altitude during the day, try to sleep at a lower altitude at night. Especially when climbing above 10,000 feet (3,000 meters), it is important to sleep at an elevation no more than 2,000 to 3,000 feet (600 to 900 meters) higher than the previous night. An alternate strategy is called staging.

You spend 2 to 3 days at an intermediate altitude (typically 8,000 feet/2,500 meters) before traveling higher. Every 3,000 to 4,000 feet (1,000 to 1,300 meters) up you spend another day acclimating to altitude. Unfortunately, few guided tours allow you the luxury of spending a day acclimating to altitude, and AMS is common.

Travelers to mountain destinations are also well-served to abandon their high-protein diets. Why? Eating carbohydrate and fat encourages they hypoxic ventilatory response. Simply put, carbs and fats have to be burned. The body produces more carbon dioxide, increasing the volume of respiration of carbon dioxide out, but also increasing the volume of respiration of oxygen in.

Finally, travelers to mountain destinations can take prophylactic treatment. The standby of mountain climbers, Diamox (acetazolamide) forces the kidneys to excrete bicarbonate. This acidifies the blood. Metabolic acidosis is a stimulant to respiration, increasing ventilation and oxygenation. Diamox prevents extreme hypoxia during sleep, but it also increases the need to urinate, which may be complicated in conditions of extreme wind and cold.

Be careful with the use of aspirin and Ibuprofen, particularly pretreatment with aspirin before travel to the mountain destination. NSAIDs stop headache, but may make you unaware of serious symptoms. Sleeping aids are also not recommended because they may depress respiration and decrease oxygenation.

Tourist Destinations at Elevations of More than 7,000 Feet Above Sea Level

Location
Altitude (Feet)
Addis Ababa, Ethiopia 7,900
Arequipa,Peru 7,559
Bogota, Colombia 8,653
Cuzco, Peru 11,152
Darjeeling, India 7,431
La Paz, Bolivia 12,001
Lhasa, Tibet 11,830
Mexico City 7,546
Quito, Ecuador 9,300
Sucre, Bolivia 8,530
Thimphu, Bhutan 7,700
Toluca, Mexico 8,793

Don't let Traveler's Diarrhea http://www.savvynaturalhealer.com/2008/12/travelers-diarrhea-more-than-you.html ruin your next trip, either. Robert Rister is the author or co-author of nine books on natural health.