What is the management approach for an inpatient with Acute Mountain Sickness (AMS)?

Management of Acute Mountain Sickness (AMS) in Inpatients

The primary management of acute mountain sickness (AMS) in inpatients includes immediate descent to lower altitude when possible, supplemental oxygen, and acetazolamide as the first-line pharmacological intervention. 1

Initial Assessment and Diagnosis

• Diagnose AMS using the Lake Louise Scoring system:
  • Rate severity (0-3) of: headache, nausea, dizziness, fatigue
  • Score ≥3 with headache indicates AMS 1
• Assess for signs of progression to more severe forms:
  • High-altitude cerebral edema (HACE): altered mental status, ataxia
  • High-altitude pulmonary edema (HAPE): dyspnea at rest, cough, crackles

Management Algorithm

First-line Interventions

1. Descent to lower altitude (when possible)

   • Most effective treatment for all forms of altitude illness 2
   • Even a modest descent of 300-600m can provide significant relief

2. Supplemental oxygen

   • Administer to maintain SpO2 >90%
   • Rapidly improves symptoms within minutes 1
   • If no improvement with oxygen, consider alternative diagnoses

3. Pharmacological treatment

   • Acetazolamide: 250mg every 12 hours 1
     • Carbonic anhydrase inhibitor with mild diuretic effect
     • Improves gas exchange and reduces symptoms
     • Monitor for dehydration and electrolyte imbalances, especially if combined with other diuretics 1

Second-line Interventions

1. Dexamethasone: 4mg every 6 hours 3, 4

   • For severe AMS or when acetazolamide is contraindicated (sulfa allergy)
   • Particularly effective for cerebral symptoms
   • Limit use to 2-3 days to avoid side effects 5
   • Not recommended for prophylaxis due to side effect profile

2. Physical rest

   • Minimize physical exertion as exercise may worsen symptoms 2
   • Maintain bed rest until symptoms improve

3. Portable hyperbaric chamber (if available)

   • Simulates descent by increasing barometric pressure
   • Beneficial short-term effect in subjects with AMS, HACE, and HAPE 2
   • Consider when descent is impossible and oxygen is unavailable

For Specific Patient Populations

• Patients with cardiovascular conditions:

  • Continue pre-existing medications at high altitude 1
  • Monitor for fluid balance carefully
  • Consider nifedipine for those with history of HAPE or pulmonary hypertension 1

• Women:

  • May have higher risk of AMS 1
  • Consider iron supplementation if deficient, as women are at higher risk of iron deficiency at altitude 1
  • Monitor for more pronounced hypoxemia during exercise 1

Monitoring and Follow-up

• Regularly assess vital signs, SpO2, and mental status
• Monitor fluid balance (risk of both dehydration and fluid overload)
• Reassess symptoms using Lake Louise score every 4-6 hours
• If symptoms worsen despite treatment, consider immediate evacuation to lower altitude

Common Pitfalls to Avoid

1. Misdiagnosis: AMS symptoms can mimic other conditions (pneumonia, dehydration, exhaustion, hypothermia)

   • If symptoms don't improve with oxygen, consider alternative diagnoses

2. Inadequate treatment: Relying solely on medications without descent or oxygen

   • Medications should supplement, not replace, descent and oxygen

3. Fluid management errors:

   • Avoid excessive fluid administration which may worsen cerebral edema
   • Avoid dehydration which may worsen symptoms
   • Be cautious with diuretics, especially when combining acetazolamide with other diuretics 1

4. Delayed recognition of progression:

   • AMS can progress to life-threatening HACE or HAPE
   • Early intervention is crucial to prevent progression

By following this structured approach to AMS management, focusing on descent, oxygen, appropriate medications, and careful monitoring, most patients will experience significant symptom improvement within 24-48 hours.