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Author: Admin | 2025-04-28
Usual response of marked diuresis in nonaffected climbers. This may lead to the mild cerebral edema that occurs in persons with moderate to severe acute mountain sickness and high-altitude cerebral edema. Proposed mediators of this response include vascular endothelial growth factor, nitric oxide synthase, and bradykinin.4,9 DIAGNOSIS Symptoms of acute mountain sickness and early high-altitude cerebral edema include headache and at least one of the following: anorexia, nausea or vomiting, dizziness or lightheadedness, difficulty sleeping, and fatigue or weakness. These symptoms can easily be misinterpreted as a viral illness.12 The key criteria, however, are a recent gain in altitude and (although not specifically stated) the absence of other causes of the symptoms. Symptoms of acute mountain sickness typically occur within six to 12 hours of gaining altitude, and range from mild with spontaneous resolution (especially at altitudes less than 11,400 ft [3,500 m]) to severe with progression to high-altitude cerebral edema.4,12 High-altitude cerebral edema is considered end-stage acute mountain sickness and is defined by ataxia (as assessed by heel-to-toe walking) or altered mental status, usually in a person with acute mountain sickness.6,7,12 High-altitude cerebral edema can progress in a matter of hours from mild ataxia to coma and death.7 PREVENTION AND TREATMENT The most accepted method of preventing acute mountain sickness and high-altitude cerebral edema is to ascend slowly. However, many climbers have difficulty following this advice. The general rule of thumb for persons at altitudes higher than 9,800 ft (3,000 m) is not to sleep more than 1,000 to 2,000 ft (300 to 600 m) above the previous night's elevation.7 Acetazolamide, a carbonic anhydrase inhibitor, may be used as prophylaxis8; it should be started at least one day before climbing and continued until acclimatization at the highest sleeping elevation (Table 33,7,16–29 ). Although a systematic review in 2001 found that lower dosages are not effective, more recent studies support the use of 125 mg twice daily for prophylaxis.16,17,29 Adverse effects may include paresthesias (common), mild diuresis, and an aversion to carbonated beverages because of the inhibition of salivary carbonic anhydrase. Acetazolamide is contraindicated in persons with sulfa allergies. Medications for the Prevention and Treatment of Altitude Illness" description="*—U.S. Food and Drug Administration (FDA)-approved indication.†—Not an FDA-approved indication.‡—Descent is mandatory.Information from references 3, 7, and 16 through 29."> Dexamethasone is also effective for prophylaxis and treatment of acute mountain sickness as a second-line agent, but it does not assist in acclimatization and therefore may lead to rebound acute mountain sickness when it is discontinued.18,19 A small study showed that low-dose theophylline is also beneficial for prevention of acute mountain sickness.20 Treatment of high-altitude cerebral edema starts with immediate descent, if possible. Descent of 1,000 ft (300 m) may be all that is required.4,7 If descent is not possible (e.g., because of weather conditions), supplemental oxygen should be administered, and the patient should be placed in a portable hyperbaric oxygen chamber until descent is possible.21 Portable hyperbaric chambers are fairly lightweight and are typically carried by high-altitude rescue teams. They may
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