Millions of travelers visit areas of higher elevation every year. They visit to train, compete and for recreation. This acute change in elevation can lead to the most frequent presentation of high altitude illness, Acute Mountain Sickness. (AMS) The more uncommon presentations of high altitude illness, high altitude cerebral edema (HACE) and high altitude pulmonary edema (HAPE) are much less common and considerably more serious. This is a health issue for those travelers who come from lower elevations and, if traveling by jet, are quickly at much higher elevations than they are accustomed. An elevation of 2000 – 3000 m (6500 – 10,000 ft.) is considered moderate altitude where travelers are more symptomatic and acclimatization becomes important.
The individual responses to elevation are highly variable. These variations would include genetic differences in response to hypoxia, different levels of oxygen carrying capacity, hydration, nutritional habits, previous exposure to altitude, rate of ascent and altitude reached, sleeping altitude, and some would include fitness.
The condition of AMS and HACE are likely the same syndrome but on different ends of the spectrum. AMS presents from hypobaric hypoxia with most developing a headache within the first 12 hours and frequently improves within 48 hours if no further increase in altitude. This is usually accompanied by some component of GI distress, insomnia, and fatigue. Further along that spectrum, HACE presents with ataxia and change in level of consciousness with initial drowsiness followed by stupor.
HAPE usually presents after 2-4 days and present with cough, shortness of breath, decreased exercise tolerance and hemoptysis as the illness progresses. HACE and HAPE are medical emergencies and require early diagnosis and treatment.
Treatment keys for severe illness
AMS: Prevention, descent if needed, ibuprofen, Oxygen; consider Dexa and Diamox
HACE: Immediate descent, Oxygen, Dexamethasone, consider Diamox
HAPE: Oxygen, Descent as soon as possible, Nifedipine, consider Dexa/Diamox
So what measures can I take to decrease my chances of AMS?
1. Acclimatization – rate of ascent if a key factor for AMS (especially over 3000m which is almost 10,000ft. For reference, Vail pass is 10,662 ft., the town of Vail is 8,000 ft., Denver 5280 ft. and Grand Junction, Colorado is 4600 ft.) Consider staying at a lower elevation and progressively ascend.
2. Stay hydrated and avoid excess alcohol. Some would recommend high carbohydrate diets
a. Ibuprofen – may be protective for AMS
b. Acetazolamide (Diamox) – most commonly used for prevention of AMS; some would recommend prophylaxis for those who plan an ascent from sea level to over 3000m in one day and those with a history of AMS
c. Dexamethasone – second line for AMS/HACE; more important in HAPE
d. Others – No definitive evidence
When you come to Colorado, it is wise to prepare and consider the elevation. Disclaimer: This is not a treatment guide or specific recommendations. Please discuss high altitude illness and treatment with your physician and experts in this field prior to your visit or before taking any medications. No need to ruin your trip to our beautiful state.
I have included several references and a link to Peter Hackett’s Institute for Altitude Medicine in Telluride, Colorado for further reading.
1. Hackett PH, Roach CR. High-Altitude Illnesses. N. Engl J Med 2001;345:107-114
2. Clarke C. Acute mountain sickness: medical problems associated with acute and subacute exposure to hypobaric hypoxia
3. Koehle MS, Cheng I, Sporer B. Canadian Academy of Sport and Exercise Medicine Position Statement: Athletes at High Altitude