Environ

High Altitude Pulmonary Edema

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High Altitude Pulmonary Edema, HAPE

  • Epidemiology
  1. Incidence: 4% in travel above 15000 feet (4600 meters)
  2. Most common cause of death from high altitude illness
  3. Onset: 1-4 days after rapid ascent above 8000 feet (2400 meters)
  • Pathophysiology
  1. Hypoxic pulmonary Vasoconstriction results in increased pulmonary capillary pressure (Pulmonary Hypertension)
  2. Results in non-inflammatory fluid extravasation into alveoli
  3. May occur in the absence of Acute Mountain Sickness
  • Risk Factors
  • Symptoms
  1. Fatigue
  2. Weakness
  3. Dyspnea on exertion
  4. Dyspnea at rest
  5. Orthopnea
  6. Cough
  7. Frothy Sputum
  8. Pink or blood tinged Sputum
    1. Very late finding
  • Signs
  1. Tachycardia
  2. Tachypnea
  3. Low-grade fever
  4. Cyanosis
  5. Hypoxia (decreased Oxygen Saturation)
  6. Altered breath sounds
    1. Rales
    2. Auscultate right middle lobe (right axilla)
      1. Anecdotal reports of HAPE onset in right middle lobe
  • Imaging
  1. Chest XRay
    1. Patchy infiltrates (asymmetric)
  2. Echocardiogram
    1. Pulmonary edema with B-line artifacts
    2. Findings may be non-specific at very high altitude (even those without HAPE will have B-line artifacts at 5000 m)
  • Diagnosis
  1. Symptom Criteria (Requires 2 or more of the following)
    1. Dyspnea at rest
    2. Cough
    3. Weakness or Decreased Exercise performance
    4. Chest tightness or congestion
  2. Sign Criteria (Requires 2 or more of the following)
    1. Rales or Wheezing in at least one lung field
    2. Central Cyanosis
    3. Tachypnea
    4. Tachycardia
  • Management
  1. Immediate descent is most critical (descend at least 500 to 1000 meters)
  2. Other measures when immediate descent is not possible
    1. High flow Supplemental Oxygen
      1. Consider Morphine if oxygen not available
    2. EPAP or PEEP pressure support
    3. Gamow Bag (Portable Hyperbaric Chamber)
    4. Dexamethasone, Nifedipine, Salmeterol, and PDE agents at same doses listed below
  • Prevention
  1. See High Altitude Sickness for general measures
  2. Acetazolamide is not effective for HAPE prevention
    1. Contrast with Acute Mountain Sickness
  3. Effective measures for HAPE prevention (started 1 day before ascent)
    1. Dexamethasone 4 mg every 6 hours
    2. Nifedipine (Procardia) 20 mg every 8-12 hours
    3. Salmeterol (Serevent) 125 mcg inhaled every 12 hours
    4. Phosphodiesterase Inhibitors
      1. Sildenafil (Viagra) 20 mg every 6-8 hours
      2. Tadalafil (Cialis) 10 mg every 12 hours