High Altitude

Abstract

People have been visiting or living in the highest mountain ranges on earth throughout history. However, the hypoxic conditions at these altitudes create a challenge for the human body. The documented success of reaching the summit of Mount Everest without oxygen shows the enormous ability of the human body to adapt to these extreme conditions. Surviving in this low oxygen tension environment requires an amazing expansion of the capacity of various body systems involved in the oxygen pathway and challenges their integrative work. Sometimes, however, the adaptation mechanisms may cause unique illnesses related to high altitude. Cerebral syndromes of acute mountain sickness and high-altitude cerebral edema, and the pulmonary syndrome of high-altitude pulmonary edema, characterize the illnesses in new arrivals to high altitude; whereas chronic mountain sickness occurs in inhabitants of the highest altitude settlements. Children experience the full range of high-altitude–associated illnesses but also have their unique health issues. Symptomatic high-altitude pulmonary hypertension is a unique illness seen mostly in infants. Low birth weight, growth problems, and nutrient deficiency have been documented in children who are born and live in high altitude. Investigation of human physiology in extreme environmental conditions like high-altitude may also contribute to understanding other similar pathologies, and may help develop successful treatments for these diseases. In this review, we discuss the physiology and pathophysiology of ascent to high altitudes and discuss the adaptation processes of permanent residents at these heights in both adults and children.