Altitude: It May Not be as High as You Think

For many, the thought of going “to altitude” brings images of Mt. Everest or similar mountaineering peaks. Physiologically, however, nothing could be further from the truth. Depending upon susceptibility, humans can begin to experience symptoms of altitude illness as low as 1500 meters above sea level. The chances increase after 6,500 feet and further still (in a non-linear fashion) as the traveler proceeds ever higher. So, even venturing to the Rocky Mountains could (and does) place many at risk of altitude sickness.

But what is altitude sickness? Well, without getting into human biology and physiology too deeply, let’s just focus on hypobaric hypoxia. While many may say there is “less oxygen” the higher you go, that’s not exactly correct. In fact the oxygen level is the same (~21%). However, the pressure decreases dramatically and so the oxygen available for us to absorb in the form of the partial pressure of oxygen decreases. This causes us to experience lower levels of oxygen and leads to a number of physiologic responses. In turn, those responses may present as one of three syndromes:

1. Acute Mountain Sickness (AMS). This is characterized by headache, fatigue, vivid dreams, amongst other symptoms. In general, it is perceived as relatively mild and improves with acclimatization to the altitude.

2. High Altitude Pulmonary Edema (HAPE). All the symptoms of AMS with fluid in the lungs. Much more serious and requires immediate treatment. Symptoms may start out as with AMS and a cough develops that may worsen. This can lead to full respiratory arrest and death.

3. High Altitude Cerebral Edema (HACE). All of the symptoms of AMS plus confusion, difficulty walking and talking or performing simple tasks. This can quickly deteriorate to death and must be treated rapidly.

The point of the post is not to fully educate you on each of these processes but to make you aware of them. Before you head off to your next ski trip or backpacking adventure, be sure to check the elevation. If you realize you have had a cough, a headache or a little confusion in past trips to such elevations, consider speaking with your health care or travel healthcare professional about ways to avoid these problems and to treat them should you be in a remote area away from medical care.

As always, if you have any comments, questions or suggestions, leave a comment.

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