Pathophysiology and management of altitude-related disorders

Abstract

Acute high-altitude related illnesses include acute mountain sickness (AMS), high altitude pulmonary oedema (HAPO) and high altitude cerebral oedema (HACO). AMS is characterized by headache, lack of appetite, poor sleep, lethargy, and fatigue. AMS is a common, generally benign, self-limiting condition if managed with rest, no ascent, and symptomatic treatment. Descent is indicated in severe cases. HACO and HAPO are rare, but serious conditions that should be considered life-threatening medical emergencies. HACO is characterized by the presence of neurological signs (including confusion) at altitude, commonly in the presence of headache. HAPO is characterized by breathlessness and signs of respiratory distress at altitude, particularly accompanying exercise. Management of HACO and HAPO involves urgent descent, supplemental oxygen (cylinder, concentrator, or portable hyperbaric chamber) if available, and specific treatment with dexamethasone (HACO) or nifedipine (HAPO). Slow controlled ascent (adequate acclimatization) is the best prophylaxis against the acute high-altitude-related illnesses. Acetazolamide is an effective prophylaxis against AMS.