High altitude typically refers to elevations over 2000 m/6360 ft, but no single value is an adequate definition for all patients. During the ascent to high altitude, barometer pressure declines exponentially, and in keeping with Dalton's law, the partial pressure of oxygen falls accordingly. Pressure chambers and air travel serve as a poor option to study the effect of hypoxemia on human physiology. Most natural is the systemic effects of high altitude on the natives and persons visiting hilly areas from low lands. 1 The basis of the effects of high altitude comes from studies performed on aviators, mountaineers and natives of high lands.