High in the cold, thin air: risks and benefits.

Abstract The purpose of this paper is to familiarize health professionals with the clinical manifestations of illness encountered by healthy subjects upon acute exposure to high altitude. Acute mountain sickness (AMS) consists of mild (headache, lethargy, anorexia) and severe (pulmonary and cerebral edema) forms which are probably a continuum of the adverse effects of hypoxia. The former occurs usually at more than 6000 feet, and is self-limited with rest and analgesia; the latter occurs at more than 12,000 feet, can be rapidly fatal, and must be treated with descent and/or oxygen. Acetazolamide may provide prophylaxis for mild symptoms; Lasix and morphine should not be used for severe AMS unless close monitoring is available. The etiology of AMS is not clear but may be related to one's ventilatory response or the response of the pulmonary and cerebral vasculature to hypoxia.