High Altitude Illness

High Altitude Illness (HAI) is a collection of three syndromes with non-specific symptoms, secondary to hypobaric hypoxia. It exists on a continuum from mild, Acute Mountain Sickness (AMS), to severe High Altitude Pulmonary Edema (HAPE) and/or High Altitude Cerebral Edema (HACE). In its mildest form, HAI may resemble the flu or a “hangover.”  At its worst, HAI can be life threatening with the loss of respiratory and/or cognitive function. These syndromes result from the incomplete/failure of the body’s normal physiologic response to high altitude.

Upon ascent to altitude the body attempts to maintain oxygen delivery.  At altitude a decrease in the partial pressure of oxygen results in a decreased arterial oxygen content. Normal physiologic changes include an increased rate of breathing and heart rate. Blood flow to the brain increases. Diuresis causes the blood to thicken along with a concomitant increase in erythropoietin secretion, which stimulates red blood cells production. These physiologic changes attempt to minimize the effects of altitude.

Acute Mountain Sickness is characterized by headache, low energy, nausea, insomnia, loss of appetite, and decreased urination.  Further down the HAI spectrum is HAPE, typified by increased shortness of breath, fatigue and signs of heart failure.  Lastly, HACE symptoms include impaired mental function, ataxia, visual disturbances, nausea and vomiting, lethargy and possibly seizures.

Signs and Symptoms of High Altitude Illness

 






Definitive treatment for all forms of HAI includes descent from altitude. Acute Mountain Sickness usually can be treated with analgesics, hydration, avoiding further ascent, and rest until further acclimatized.  If AMS symptoms progress into HAPE and/or HACE then descent from altitude and oxygen are necessary treatments.  If you are with someone exhibiting symptoms of HAI, do not leave them alone as symptoms may progress.

                                       Treatment for High Altitude Illness



 

 

 

Prevention is often the best form of treatment.  Ascend slowly, acclimatize if time allows.  Aggressively treat symptoms of AMS.  Stay hydrated.  Some medicines are beneficial to treat AMS and help acclimatization. Check with your physician/nurse practitioner to see if these drugs, acetazolamide and dexamethasone, might be useful. 


Additional Reading
Gallagher, S. and Hackett, P. (2004). High-Altitude Illness. Emergency Medical Clinics of North America, 22, 329-355.
Schimelpfenig, T. (2006). Wilderness Medicine. Mechanicsburg, PA: Stackpole Books, (pg. 151-160).
Eng, R. (2010). First Aid. In Eng.R. and Pelt, J. Editors, Mountaineering: The Freedom of the Hills (pg 495-514). Seattle: Mountaineers Books.Type your paragraph here.

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