A trek to the top: a review of acute mountain sickness.

Acute mountain sickness (AMS) affects, to varying degrees, all travelers to high altitudes (elevations greater than 5280 feet). In a small percentage of patients, AMS can lead to high-altitude pulmonary edema (HAPE) or high-altitude cerebral edema (HACE). Symptoms of AMS range from a combination of headache, insomnia, anorexia, nausea, and dizziness, to more serious manifestations, such as vomiting, dyspnea, muscle weakness, oliguria, peripheral edema, and retinal hemorrhage. Although the primary cause of these symptoms is related to the reduced oxygen content and humidity of the ambient air at high altitudes, the physiologic pathway relating hypoxemia to AMS and its sequelae remains unclear. Tips on self-diagnosis and symptom recognition are critical elements to be included in educating patients who are contemplating a trip to high altitudes. Preventive strategies include allowing 2 days of acclimatization before engaging in strenuous exercise at high altitudes, avoiding alcohol, and increasing fluid intake. Conditioning exercise for patients older than 35 years is also recommended before departure. A high-carbohydrate, low-fat, low-salt diet can also aid in preventing the onset of AMS. Acetazolamide (125 mg two or three times daily, or once at bedtime) has also been shown to reduce susceptibility to AMS and the incidence of HAPE and HACE. Although effective in treating cerebral symptoms of AMS, dexamethasone is not routinely recommended as a prophylactic agent for AMS.