What is the management of High Altitude Pulmonary Edema (HAPE)?

Management of High-Altitude Pulmonary Edema (HAPE)

Immediate descent to lower altitude and administration of supplemental oxygen are the primary therapies for HAPE in both adults and children. 1, 2

Acute Treatment Algorithm

First-Line Interventions (Life-Saving)

• Immediate descent is the most effective and reliable treatment—descend as rapidly and safely as possible 3, 4
• Supplemental oxygen should be administered at adequate flow rates to maintain arterial oxygen saturation above 90% 3, 4
• Complete rest from all strenuous physical activity is essential during treatment 3, 5

Pharmacological Treatment

• Nifedipine is the medication of choice for HAPE treatment, used as an adjunct when descent or oxygen are not immediately available 2, 3

  • For patients with history of HAPE, nifedipine should be started with ascent and continued for 3-4 days after arrival at terminal altitude 1, 2
  • Works as a pulmonary vasodilator to reduce pulmonary artery pressure 3
  • Typical dosing: sustained-release nifedipine 20 mg orally twice daily 5, 6

• Acetazolamide is commonly used in combination therapy 5

• Sildenafil and salmeterol have been used successfully in field settings, though evidence is more limited 5

Alternative Interventions When Descent/Oxygen Unavailable

• Portable hyperbaric chamber serves as an effective temporizing measure 3, 4
• Auto-PEEP (pursed lips breathing technique) can improve oxygen saturation from 65-70% to 95%, though slower than bottled oxygen above 80% saturation 7
  • Advantage: immediately available without equipment 7
  • Positive effect on oxygenation lasts approximately 120 minutes after stopping 7

Treatment at Altitude (When Descent Not Immediately Possible)

A case series from Nepal demonstrated successful treatment of serious HAPE (Hultgren grades 3-4) at 4240m using: 5

• Bed rest
• Oxygen therapy
• Nifedipine
• Acetazolamide
• Duration of stay: 31 ± 16 hours (range 12-48 hours)
• Oxygen saturation improved from 59% ± 11% at admission to 84% ± 1.7% at discharge 5

Clinical Recognition

Presenting symptoms typically appear 2-4 days after rapid ascent: 1

• Cough (initially nonproductive)
• Exertional dyspnea progressing to dyspnea at rest
• Reduced exercise performance
• Cyanosis, tachycardia, tachypnea
• Elevated body temperature (generally not exceeding 38.5°C) 4
• Rales initially discrete and located over middle lung fields 4

Diagnostic clue: Patients with HAPE typically improve rapidly (within minutes) with enriched inspired oxygen—those who don't improve rapidly warrant investigation for other causes of pulmonary hypertension 1

Prevention Strategies

Non-Pharmacological (Most Effective)

• Gradual ascent at 300-600 m/day above 2500m 1, 2
• Rest day for every 600-1200m of elevation gained 1, 2
• Avoid vigorous exertion before proper acclimatization 1, 2
• Delay further ascent if symptoms appear 1, 2

Pharmacological Prophylaxis (For High-Risk Individuals)

• Nifedipine is recommended for patients with history of HAPE 1, 2

  • RCT evidence: reduced HAPE incidence from 7 of 11 (placebo) to 1 of 10 (treated) in adults with prior HAPE 1

• Alternatives include PDE5 inhibitors (tadalafil, sildenafil) and dexamethasone 1, 2

  • Caution: Tadalafil associated with severe acute mountain sickness in some subjects 1, 2

Critical Pitfalls to Avoid

• Continuing ascent despite symptoms—many trekkers push themselves despite early warning signs, which can be fatal 6
• Using alternative transport (horseback, etc.) while symptomatic—this worsens the condition and is extremely dangerous 6
• Mistaking HAPE for other conditions—pneumonia and asthma must be considered in differential diagnosis, especially in children 1
• Intercurrent illness increases risk—respiratory tract infections may contribute to HAPE development even in those without prior altitude illness history 6
• Acetazolamide does NOT prevent HAPE—it prevents acute mountain sickness but not HAPE specifically 6

Special Populations

Pediatric Patients

• No randomized trials exist for HAPE prevention or treatment in children 1, 2
• All recommendations based on adult trials 1, 2
• Children have roughly equal sex distribution (unlike male predominance in adults) 1
• HAPE associated with viral illness and multiple disorders in children including ASD, PDA, pulmonary vein stenosis, trisomy 21, and BPD 1

High-Risk Individuals

• Recurrence rate: 62% in those with prior HAPE episode versus 7% in those without prior history when rapidly ascending to 4559m 1
• Re-entry HAPE occurs in high-altitude residents returning after as little as one day at low altitude 1

Pathophysiology Context

HAPE results from: 3, 4

• Exaggerated hypoxic pulmonary vasoconstriction
• Uneven pulmonary vasoconstriction with regional overperfusion
• Increased pulmonary capillary pressure
• Stress failure of pulmonary capillaries
• High permeability edema with capillary leak