There is a great variability in an individuals' susceptibility to acute and chronic mountain sickness complications. Some populations such as Tibetans, Aymaras and Quechua natives of High Andes, and Ethiopian dwellers of high mountains have a genetically determined resistance to these complications.
Acute mountain sickness:
— Caused by cerebral hypoxia and may be life-threatening. Polycythemia does not occur.
— Persons may have headaches, insomnia, palpitations, weakness, nausea, vomiting, and mental dullness, and may develop pulmonary and cerebral edema.
— Treatment is with oxygen, dexamethasone, and acetazolamide and/or rapid return to lower altitude.
Chronic mountain sickness:
— Occurs after prolonged exposure to high altitudes; there appears to be a genetic predisposition.
— Characterized by marked polycythemia, cyanosis, plethora, pulmonary hypertension, clubbing of the fingers, and signs of right heart failure.
— Treatment with the angiotensin-converting enzyme inhibitor enalapril has been reported to be effective.
— A return to a normal state develops slowly.