March 2012

March 2012: Health Note - Travel & Altitude Sickness

Author: Paula Hart

If you have ever experienced altitude sickness, like most travelers, you will do just about anything to avoid a second occurrence. Altitude sickness can strike suddenly and unpredictably, causing anything from a mild headache to a life-threatening situation requiring immediate medical attention. As we engage in more exotic travel to high altitude destinations such as Tibet, Bhutan, Peru, Kilimanjaro, Bolivia, etc., all travelers (whether hiking, climbing, skiing, or sightseeing) should know how to recognize the early symptoms of altitude illness.

Susceptibility and resistance to altitude illness are genetic traits. No screening tests are available to predict a person’s risk or chance of experiencing illness. How a traveler has responded to high altitude in the past will be a more reliable guide to how well he or she may respond in the future. Risk is not affected by training or physical fitness, and children are as susceptible as adults.

What altitude is a risk?
As a general rule, most people do not experience symptoms of illness below altitudes of 8,000 feet, although that is not always the case. Even in places such as Denver, Colorado at 5,183 ft. and Santa Fe, New Mexico at 7,000 ft., some people experience altitude symptoms. Experts place altitude into three categories: high altitude: 5,000-11,500 ft.; very high altitude: 11,500-18,000 ft.; extreme altitude: above 18,000 ft.

Taking into consideration a person’s susceptibility, the risk of becoming ill is influenced by the rate of ascent, altitude and amount of time spent at an altitude. Day trips to high altitude and then returning to lower altitude to sleep are much easier on the body. The process of acclimatization to high altitude takes three to five days.

What causes altitude sickness?
Stresses of high altitude include cold, decreased humidity, increased solar radiation and decreased air pressure. All of these can cause problems for the traveler, but “hypoxia” (lack of oxygen) is the greatest concern.

Air at altitude is commonly mistaken for being lower in oxygen, but this is incorrect. The percentage of oxygen in the air at sea level is exactly the same as at high altitudes—approximately 21 percent. At higher elevations, however, where there is less pressure, air molecules are more dispersed so each breath delivers less oxygen to the body. At 10,000 feet, for example, you are breathing in 30 percent less oxygen than at sea level, at 12,000 feet, about 40 percent less oxygen. Given the smaller number of oxygen molecules available, our breathing increases just to try and consume the same amount of oxygen as at sea level.

While there are several other physiological effects of high altitude on our bodies, including increase in urination and heartbeat, the key factor in preventing illness depends on actual altitude, rate of ascent and duration of exposure.

Symptoms of altitude illness:
Two experts in the field of altitude illness, Dr. Peter Hackett and Dr. David Shlim, describe below the three syndromes: AMS (acute mountain sickness), HACE (high altitude cerebral edema), and HAPE (high altitude pulmonary edema).

AMS: The most common form of altitude illness affects about 25 percent of all people sleeping above 8,000 ft. in Colorado. Headache is the major symptom, but can include nausea, vomiting, loss of appetite, restlessness, fatigue. The headache usually occurs between 2-12 hours after arriving and frequently during or after the first night. Children may show a loss of appetite, become irritable and appear pale. AMS usually resolves within 24-72 hours of acclimatization.

HAPE: This condition is an emergency and can be rapidly fatal. Initial symptoms are increased breathlessness with exertion eventually increasing at rest; dry persistent cough; a feeling of tightness in the chest; weakness. It is caused by excessive fluid in the lungs. Oxygen and/or descending as soon as possible is critical.

HACE: Similar symptoms to AMS with profound lethargy, drowsiness, confusion, clumsy or awkward gait. This is an emergency and requires immediate descent to prevent death.

Prevention for travelers
The main point of instructing travelers about altitude illness is not to prevent any possibility of altitude illness, but to prevent death from altitude illness. The three rules that travelers should know to prevent death are:

- Know the early symptoms of altitude illness

- Never sleep at a higher altitude when already experiencing symptoms.

- Descend if symptoms become worse while resting at the same altitude.

Drug therapy is available to help prevent altitude illness, and travelers should consult with their physician or travel clinic before departing to high altitude destinations. Travelers with certain medical conditions such as cardiac, pulmonary or diabetes should be counseled carefully.

Paula Hart, R.N., is a certified travel health specialist. For more information, contact her at (843) 681-5444 or e-mail

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