<Tr> <Th> ICD - 9 - CM </Th> <Td> 993.2 </Td> </Tr> <Tr> <Td_colspan="2"> (edit on Wikidata) </Td> </Tr> <P> High - altitude pulmonary edema (HAPE) (HAPO spelled oedema in British English) is a life - threatening form of non-cardiogenic pulmonary edema (fluid accumulation in the lungs) that occurs in otherwise healthy mountaineers at altitudes typically above 2,500 meters (8,200 ft). However, cases have also been reported at lower altitudes (between 1,500--2,500 metres or 4,900--8,200 feet in highly vulnerable subjects), though what makes some people susceptible to HAPE is currently unknown . HAPE remains the major cause of death related to high - altitude exposure, with a high mortality rate in the absence of adequate emergency treatment . </P> <P> Physiological and symptomatic changes often vary according to the altitude involved . </P>

What is the cause of high altitude pulmonary edema
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