Dexamethasone in the Treatment of Acute Mountain Sickness

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, cross-over fashion. Dexamethasone reduced the symptoms of acute mountain sickness by 63 percent (P<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. ACUTE mountain sickness frequently strikes travelers who rapidly ascend to altitudes above 2500 m.¹ It is characterized by headache, lassitude, anorexia, nausea, and vomiting. Although often disabling, it is usually self-limited.² However, it occasionally progresses to a more severe, life-threatening form called high-altitude cerebral edema.³ Although the exact relation between acute mountain sickness and high-altitude cerebral edema is unknown, the conditions may represent a continuum in the spectrum of high-altitude illness.^4,5 Early swelling of the brain has thus been suggested as the cause of even mild mountain sickness. In this regard, Johnson et al.⁶ demonstrated the efficacy of dexamethasone, a…