Cerebral edema occurs in fatal cases of acute
mountain sickness.
Dexamethasone, commonly used to treat
cerebral edema due to other causes, also reduces the symptoms of acute
mountain sickness when given prophylactically. However, the efficacy of
dexamethasone in the treatment of established acute
mountain sickness remains uncertain. To investigate this question, we exposed six men in a hypobaric chamber to a simulated altitude of 3700 m (barometric pressure, 64 kPa [481 mm Hg]) for 48 hours on two occasions. Acute
mountain sickness was diagnosed with use of a symptoms questionnaire, and
dexamethasone (4 mg every six hours) or placebo was then given in a randomized, double-blind, crossover fashion.
Dexamethasone reduced the symptoms of acute
mountain sickness by 63 percent (P less than 0.05), whereas placebo had a minimal effect (reduction by 23 percent; P not significant). In spite of this response, one subject had mild
cerebral edema on brain CT after both placebo and
dexamethasone.
Dexamethasone had no effect on fluid shifts, oxygenation,
sleep apnea, urinary
catecholamine levels, the appearance of chest radiographs or perfusion scans, serum
electrolyte levels, hematologic profiles, or the results of psychometric tests.
Dexamethasone treatment was complicated by mild
hyperglycemia in all subjects (mean [+/- SE]
glucose level, 7.3 +/- 1.3 mmol per liter [132 +/- 23 mg per deciliter]). We conclude that
dexamethasone effectively reduces the symptoms of acute
mountain sickness. However, it did not improve objective physiologic abnormalities related to exposure to high altitudes. We therefore recommend that
dexamethasone be used only when descent is impossible, or to facilitate cooperation in evacuation efforts.