High-altitude pulmonary edema

High-altitude pulmonary edema (HAPE) is a life-threatening form of non-cardiogenic pulmonary edema that occurs in otherwise healthy people at altitudes typically above 2,500 meters (8,200 ft).^[2] HAPE is a severe presentation of altitude sickness. Cases have also been reported between 1,500–2,500 metres or 4,900–8,200 feet in people who are at a higher risk or are more vulnerable to the effects of high altitude.

Classically, HAPE occurs in people normally living at low altitude who travel to an altitude above 2,500 meters (8,200 feet).^[3] Re-entry HAPE has been described in people who normally live at high altitude but who develop pulmonary edema after returning from a stay at low altitude.^[3] Symptoms include crackling sounds when breathing, dyspnea (at rest), and cyanosis.^[4] The primary treatment is descent to a lower altitude, with oxygen therapy and medication as alternatives. If HAPE is not treated, there is a 50% risk of mortality.^[4]

There are many factors that can make a person more susceptible to developing HAPE, including genetic factors. The understanding of the risk factors and how to prevent HAPE is not clear. HAPE remains the major cause of death related to high-altitude exposure, with a high mortality rate in the absence of adequate emergency treatment.^[3]