Recreation and business draw countless visitors to high altitude locations across the country every year. Many people coming from low land elevations are unacclimatized to the lower oxygen levels at higher altitude and develop symptoms of altitude illness. The most common type of altitude illness is Acute Mountain Sickness (AMS), followed by the more rare conditions of High Altitude Cerebral Edema (HACE) and High Altitude Pulmonary Edema (HAPE), both of which can be life threatening. The purpose of this literature review was to use information from various internet search engines, online medical journals, research articles, and textbooks to compile the latest information on the pathophysiology, signs and symptoms, treatment and prevention of AMS, HACE, and HAPE.AMS and the other altitude illnesses are clinical diagnoses in relation to recent arrival to altitude in a person who is otherwise unacclimated to high elevation. The clinical criteria for diagnosing AMS involves the following findings in the context of recent arrival to high altitude; a headache with one or more of the following: anorexia, nausea or vomiting, fatigue or weakness, dizziness or lightheadedness, or difficulty sleeping. HACE is considered end stage AMS and involves severe AMS symptoms as well as ataxia, confusion, and gross neurological dysfunction. HAPE is considered a separate entity than AMS or HACE but is found congruently with HACE in 50 percent of cases. Symptoms include dyspnea at rest, a productive cough and weakness.The mainstay of prevention for all types of altitude illness includes a slow ascent rate, plenty of rest and fluids. Acetazolamide and dexamethasone are the current recommended medications for prophylaxis, however the herbal remedy Ginkgo biloba have all been shown to be effective in some studies. Once symptoms develop treatment is largely based on descent, limiting further exertion and providing supplemental oxygen. Acetazolamide, Dexamethasone, Nifedipine, and Phosphodiasterase-5 inhibitors are all shown to be effective treatments although some are still in the developmental stage in terms of recommendations and dosing. Hyperbaric therapy is also indicated in severe cases when available.The altitude illnesses of Acute Mountain Sickness, High Altitude Cerebral Edema, and High Altitude Pulmonary Edema are diagnoses that need to be taken seriously, although most cases are minor in nature and will improve significantly with time, rest or descent. Humans have a significant variability in terms of ones ability to adapt to high altitude due to mechanisms that are still not fully understood. However it is inevitable that many visitors will develop symptoms as they visit high altitude and it is imperative that clinicians providing care in these environments be educated on this relatively common condition and how to best treat it.
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