Chapter 2 - High Altitude Ailments: Causes and Effects

Abstract

More than 100 million people visit high-altitude (HA) locations (up to 2500m and higher) annually for recreation and adventure purposes, testing the limits of human endurance. HA is characterized chiefly by several adverse environmental conditions such as low barometric pressure, low air humidity, and low atmospheric temperature, high aridity, high ultraviolet radiation, and, most prominently, hypobaric hypoxia. At HA, most of the undesirable physiological effects result from the decrease in atmospheric pressure and low availability of oxygen, additional deterioration results from extreme cold, exposure to ionizing, and high wind velocity. Exposure to these environmental stresses at HA commences an intricate sequence of pathophysiological effects. Hypobaric hypoxia is a major concern because it tends to cause a wide range of physiological HA illnesses, including acute mountain sickness (AMS), sleep disturbance, HA retinopathy, hypophagia, and life-threatening pathophysiological ailments such as high-altitude cerebral edema and high-altitude pulmonary edema.