ABSTRACT
With increasing numbers of people traveling to high altitude for work, adventure holidays, expeditions, skiing, and religious pilgrimages, doctors are frequently being asked to counsel patients on the risks of their planned trip. Recognizing the current limitations in the literature, this chapter incorporates the available evidence as well as an understanding of the physiologic responses to acute hypoxia to provide guidance for advising travelers with underlying medical conditions ahead of their planned sojourn or managing problems that might occur on such a trip. While the risk of acute altitude illness is thought to increase with ascent above 2500 m, some of the major physiologic responses to hypobaric hypoxia, including the hypoxic ventilatory response and hypoxic pulmonary vasoconstriction occur at as low as 2000 m. Recommendations for pharmacologic prevention and treatment of acute altitude illness are largely based on studies performed in healthy individuals lacking severe chronic medical problems.
