Environ

High Altitude Pulmonary Edema

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High Altitude Pulmonary Edema, HAPE

  • Epidemiology
  1. Most common cause of death from High Altitude Illness
  2. Incidence: 4% in travel above 15000 feet (4600 meters)
  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 (noncardiogenic Pulmonary Edema)
  3. May occur in the absence of Acute Mountain Sickness in up to 50% of cases
  • Risk Factors
  • Symptoms
  1. Fatigue
  2. Weakness
  3. Dyspnea on exertion
  4. Dyspnea at rest
  5. Palpitations
  6. Orthopnea
  7. Dry Cough
  8. Epistaxis
  9. Frothy Sputum
  10. Pink or blood tinged Sputum
    1. Very late finding
  • Signs
  1. Tachycardia
  2. Tachypnea
  3. Low-grade fever
  4. Cyanosis
  5. Syncope
  6. Edema
  7. Hypoxia (decreased Oxygen Saturation)
  8. Altered breath sounds
    1. Rales (asymmetric)
    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. Pulmonary artery prominence
  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. Supplemental Oxygen to keep Oxygen Saturation >90%
      2. Consider Morphine if oxygen not available
    2. EPAP or PEEP pressure support
    3. Gamow Bag (Portable Hyperbaric Chamber)
    4. Dexamethasone 4 mg every 6 hours
    5. Nifedipine XR (Procardia XR) 30 mg every 12 hours
    6. May consider beta agonists (e.g. Albuterol)
  • Prognosis
  1. Mortality 50% if untreated
  • 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 24 hours before ascent, only if significant HAPE risk factors)
    1. Dexamethasone 4 mg every 6 hours (typically reserved for treatment only)
    2. Nifedipine XR (Procardia XR) 30 mg every 12 hours
    3. Salmeterol (Serevent) 125 mcg inhaled every 12 hours
    4. Phosphodiesterase Inhibitors (weak evidence)
      1. Sildenafil (Viagra) 20 mg every 6-8 hours
      2. Tadalafil (Cialis) 10 mg every 12 hours
  • References
  1. Cardy and Contant in Herbert (2020) EM:Rap 20(3): 10-11
  2. Comp and Rogich (2021) Crit Dec Emerg Med 35(4): 3-8
  3. Fiore (2010) Am Fam Physician 82(9): 1103-10 [PubMed]
  4. Luks (2008) High Alt Med Biol 9(2): 111-4 [PubMed]
  5. Voelkel (2002) N Engl J Med 346(21): 1606-7 [PubMed]