What is the management of acute altitude sickness?

Management of Acute Altitude Sickness

The most effective management of acute altitude sickness is immediate descent to lower altitude, supplemented with oxygen therapy when available, and appropriate medication including acetazolamide for mild cases and dexamethasone for more severe presentations. 1, 2

Clinical Presentation and Classification

• Acute mountain sickness (AMS) typically occurs 6-12 hours after exposure to altitudes above 2,500m and presents with headache, nausea, dizziness, fatigue, and insomnia 2, 3
• High-altitude pulmonary edema (HAPE) presents with dyspnea, fatigue, chest tightness, and dry cough that may progress to pink frothy sputum 4
• High-altitude cerebral edema (HACE) is the most severe form, characterized by severe headache unresponsive to analgesics, ataxia, altered mental status, and potentially coma 4

First-Line Management

• Immediate descent of at least 300m is the most effective treatment for all forms of altitude illness 2, 3
• Supplemental oxygen should be administered when available to maintain oxygen saturation above 90% 2, 5
• Portable hyperbaric chambers can be used as a temporizing measure when immediate descent is not possible, providing a simulated descent of approximately 2000m 6

Pharmacological Management

For Mild to Moderate AMS:

• Acetazolamide (250mg every 12 hours) is the first-line medication, acting as a carbonic anhydrase inhibitor to improve oxygenation through respiratory stimulation 1, 5
• Analgesics such as acetaminophen or ibuprofen can be used for symptomatic relief of headache 3
• Antiemetics may be needed for nausea and vomiting 3

For Severe AMS or HACE:

• Dexamethasone (8mg initially, followed by 4mg every 6 hours) is the treatment of choice for cerebral edema 1, 4
• Continue dexamethasone until symptoms resolve, then taper gradually 4

For HAPE:

• Nifedipine (30mg extended-release every 12 hours or 10mg every 4 hours) is effective for treating HAPE by reducing pulmonary hypertension 1, 2
• Phosphodiesterase inhibitors like sildenafil may be considered as alternatives 3

Special Considerations

• Avoid sedatives and alcohol as they can worsen hypoxemia and mask symptoms 3
• Maintain adequate hydration but avoid excessive fluid intake which may worsen cerebral edema 1
• Patients with pre-existing cardiovascular or pulmonary disease should continue their regular medications at altitude 1

Prevention of Recurrence

• After recovery, further ascent should only be attempted after complete resolution of symptoms 1
• Resume ascent at a slower rate (300-600m/day above 2500m) with rest days for every 600-1200m gained 1
• Consider prophylactic medications if reascending:
  • Acetazolamide (125-250mg twice daily) starting 24 hours before ascent 1, 5
  • Dexamethasone (4mg every 12 hours) if acetazolamide is contraindicated 1
  • Nifedipine for those with previous HAPE 2, 4

Common Pitfalls

• Delaying descent in severe cases while attempting pharmacological management alone 3
• Underestimating the importance of gradual acclimatization when returning to altitude 1
• Inadequate hydration, which can worsen symptoms 1
• Failing to recognize progression from mild AMS to more severe forms requiring aggressive intervention 4