What would happen to you if you were taken immediately to the summit of Mt. Everest? The answer is you would pass out, and likely die within minutes. So why, then, can people summit Everest without oxygen? The answer to this lies in the understanding of oxygen, pressure, and your body’s ability to acclimatize over time. In general, the percent of oxygen in the air stays the same with altitude, however, the partial pressure of the oxygen in the air mixture decreases. Although overly simplistic, this means that as we gain altitude, the molecules of oxygen are more spread out and our body’s ventilation systems do not work as well. Over time, our body can adapt to lower pressure and therefore someone who is properly acclimatized can withstand much higher altitudes than someone who is not.

Acute Mountain Sickness (AMS) is the term used to describe illness related to altitude. Unfortunately, the symptoms of AMS are similar to many other illnesses. However, crews and individuals that live at lower elevations (usually below 4,000 feet) and are working and sleeping above 6,500 feet are at risk for AMS. It is rare to experience AMS below 8,000 feet, however, about 50% of people will experience at least a mild form of AMS above 10,000 feet. AMS should be considered if an individual:

1. Recently traveled to a higher elevation (generally above 8,000 feet) AND

2. Has a headache AND

3. Has other symptoms including:

   1. Dizziness or lightheadedness

   2. Fatigue or weakness

   3. Nausea/vomiting/anorexia

   4. Insomnia

The most severe types of altitude related illness are a consequence of fluid buildup and swelling in either the brain or the lungs. These conditions are called high altitude pulmonary edema (HAPE) and high altitude cerebral edema (HACE). With HAPE, individuals experience AMS in addition to coughing and severe shortness of breath. With HACE, individuals experience AMS in addition to confusion, seizures, and other mental status changes.

Prevention of AMS, HACE, and HAPE is done by slowly acceding to altitude over several days; working high and sleeping low; and good nutrition and hydration.

Treatment of AMS ranges depending on severity. For mild symptoms, generally rest and hydration with some moderate decent in altitude for one or two days will allow for complete recovery and the ability to continue to work at altitude. For significant AMS, HACE, or HAPE, immediate decent, and evacuation is necessary.

Other examples include:

• High altitude cerebral edema (HACE) is a severe and potentially fatal condition associated with high altitude illness that is often thought of as a late or end-stage AMS.

• High altitude pulmonary edema (HAPE) is a severe form of high altitude illness that, if left untreated, can lead to mortality in 50 percent of affected individuals. It occurs secondary to hypoxia and is a form of noncardiogenic pulmonary edema. It is characterized by fatigue, dyspnea, and a dry cough with exertion.

Discussion Questions:

Where on this fire, your home unit or areas in the country might you or  your crew be at risk for developing AMS? What should you do to prevent/prepare? What should you do if symptoms develop?