High altitude pulmonary edema

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Background

  • Also known as HAPE
  1. Noncardiogenic pulm edema d/t increased microvascular pressure in the pulm circulation
  2. Most lethal of the altitude illnesses
  3. Occurs in <1/10,000 skiers in Colorado; 2-3% of Mt. McKinley climbers
  4. Typical pt is strong and fit; may not have symptoms of AMS before onset of HAPE
  5. Most commonly noticed on the second night at a new altitude
  6. Risk Factors:
    • Heavy exertion
    • Rapid ascent
    • Cold
    • Excessive salt ingestion
    • Use of a sleeping medication
    • Preexisting pulmonary HTN
    • Preexisting respiratory infection (children)
    • Previous history of HAPE

Clinical Features

  1. Early
    1. Dry cough, decreased exercise performance, dyspnea on exertion, localized rales
    2. Resting SaO2 is low for the altitude and drops markedly w/ exertion (aids in the dx)
  2. Late
    1. Dyspnea at rest, marked weakness, productive cough, cyanosis, generalized rales
    2. Tachycardia and tachypnea correlate with the severity of illness
    3. Altered mental status and coma (from severe hypoxemia)
  3. ECG
    1. Right strain pattern
  4. CXR
    1. Progresses from interstitial to localized-alveolar to generalized-alveolar infiltrates
  5. ABG
    1. hypoxemia with respiratory alkalosis

Differential Diagnosis

High Altitude Illnesses

Treatment

  1. Immediate descent is treatment of choice
    1. While pt is descending attempt to limit exertion as much as possible
  2. If cannot descend use combination of:
    1. Supplemental O2
      1. Can completely resolve the pulmonary edema within 36-72hr
    2. Hyperbaric bag
    3. Keep pt warm (cold stress elevates pulm artery pressure)
    4. Use expiratory positive airway pressure mask
    5. Consider the medications listed below that are usually used for prevention

Disposition

  1. Admission
    1. Warranted for severe illness that does not respond immediately to descent
  2. Discharge
    1. Progressive clinical and X-ray improvement and a PaO2 of 60mmHg or SaO2>90%

Prevention

  1. Nifedipine 20mg q8hr while ascending is effective prophylaxis in pts who had HAPE before
  2. Tadalafil 10mg BID 24hr prior to ascent
  3. Salmeterol inhaled BID

See Also

High Altitude Medicine

Source

Tintinalli