What is the management for a patient suspected of having acute mountain sickness?

Management of Acute Mountain Sickness

For a patient with suspected acute mountain sickness, immediately halt further ascent, provide symptomatic treatment with analgesics for headache, ensure adequate hydration, and initiate acetazolamide 250 mg twice daily if symptoms are moderate or persistent. 1

Immediate Assessment and Stabilization

Clinical Recognition

• Acute mountain sickness (AMS) typically presents with headache plus at least one of the following: nausea, loss of appetite, dizziness, fatigue, or insomnia within 6-12 hours of altitude gain. 2, 3
• Symptoms usually occur above 2,500 meters and affect 25-85% of travelers depending on ascent rate and individual susceptibility. 3
• The condition is generally self-limiting and benign, but requires vigilance for progression to life-threatening forms. 4, 2

Critical Red Flags Requiring Immediate Descent

• Severe headache unrelieved by acetaminophen signals potential progression to high-altitude cerebral edema (HACE). 4
• Ataxia, altered mental status, or loss of coordination indicate HACE and mandate immediate descent. 4, 2
• Dyspnea at rest, chest tightness, or cough with pink frothy sputum suggest high-altitude pulmonary edema (HAPE) and require urgent evacuation. 4, 2

Treatment Algorithm

Mild AMS (Headache with minimal other symptoms)

• Stop ascent and remain at current altitude until symptoms resolve. 1, 5
• Provide acetaminophen or ibuprofen for headache relief. 4
• Ensure aggressive hydration with oral fluids. 1
• Acetazolamide 250 mg twice daily can be initiated to accelerate acclimatization. 1, 4
• Allow 24-48 hours for symptom resolution before considering further ascent. 5

Moderate AMS (Multiple symptoms interfering with activity)

• Initiate acetazolamide 250 mg twice daily or 500 mg once daily immediately. 1, 4
• Halt all ascent and consider descending 300-500 meters if symptoms persist beyond 24 hours. 5
• Provide supplemental oxygen if available (improves symptoms rapidly). 5, 2
• Monitor closely for progression to severe forms. 2

Severe AMS/HACE (Ataxia, altered mental status, severe headache)

• Immediate descent of at least 300 meters is mandatory and life-saving. 5, 2
• Administer dexamethasone 8 mg initial dose, then 4 mg every 6 hours (glucocorticoids are first-line treatment for malignant AMS). 4
• Provide supplemental oxygen at 2-4 L/min if available. 5, 2
• Arrange for evacuation; this is a medical emergency. 2, 3

HAPE (Dyspnea, cough, chest tightness)

• Immediate descent is the primary treatment and takes priority over all other interventions. 4, 5, 2
• Administer nifedipine 30 mg extended-release every 12 hours (pulmonary vasodilator effective for HAPE). 4
• Provide high-flow supplemental oxygen if available. 5, 2
• Keep patient warm and minimize exertion during descent. 2

Pharmacological Management Details

Acetazolamide

• Mechanism: carbonic anhydrase inhibitor causing metabolic acidosis that stimulates ventilation and improves oxygenation. 1
• Standard dosing: 250 mg twice daily or 500 mg once daily. 1, 4
• Common side effects include paresthesias (tingling), altered taste, and increased urination—these are dose-related but generally mild. 1, 6
• Contraindicated in sulfa allergy; use dexamethasone as alternative. 6
• Duration: continue for 2-3 days at terminal altitude, then discontinue (prolonged use unnecessary and increases side effects). 1

Dexamethasone

• Use when acetazolamide is contraindicated or for severe AMS/HACE. 1, 4
• Dosing: 4 mg every 6 hours for treatment; 2 mg every 6 hours for prophylaxis. 3
• More effective than acetazolamide for established severe AMS but does not aid acclimatization. 4

Nifedipine

• Specific for HAPE prevention and treatment; not effective for AMS or HACE. 4
• Dosing: 30 mg extended-release every 12 hours. 1
• Mechanism: pulmonary vasodilation counteracts exaggerated hypoxic pulmonary vasoconstriction. 4

Common Pitfalls and Caveats

Critical Errors to Avoid

• Never continue ascent with active AMS symptoms—this is the most common mistake leading to severe illness. 1, 5
• Do not rely solely on oxygen saturation at rest; exercise-induced desaturation at 2,700 m combined with low saturation at 4,300 m has 80% positive predictive value for severe AMS. 7
• Vomiting in the setting of AMS often signals progression to severe disease and should prompt immediate descent consideration. 4
• Underestimating hydration needs—increased insensible losses at altitude compound hypoxia effects. 1

Special Populations

• Patients with cardiovascular disease should continue their regular medications at altitude and can add acetazolamide for AMS prevention. 1
• Hypertensive patients may benefit from acetazolamide, which can lower blood pressure while improving oxygen saturation at altitude. 8, 1
• Patients with heart failure (NYHA class I-II) can travel to high altitude if stable, but those with NYHA class IV should avoid altitude exposure entirely. 9

Prevention Context

While the question focuses on management, note that gradual ascent at 300-600 m/day above 2,500 m with rest days every 600-1,200 m is the most effective prevention strategy—this context helps explain why immediate cessation of ascent is critical in treatment. 1