High altitude

Abstract

Control of breathing at high altitude has been studied intensely for over a century. Although there has been a variety of theories to explain the deleterious effects of high altitude, it is now clear that the primary problem is a decrease in the oxygen partial pressure. The decrease in inspired PO2 during ascent to high altitude is the most common form of environmental hypoxia in humans and terrestrial animals, and the reflex increase in ventilation from arterial hypoxemia is the body’s first line of defense against decreased O2 supply. Hence, understanding the control of breathing at altitude provides the basis for understanding the normal physiological response to hypoxia. We understand the basic elements of the response but many fundamental questions remain, and these are currently under investigation with modern experimental techniques.