Oxygen uptake and transport in the human organism on the summit of Mt. Everest.

In May 1978 the two Italians, Messner and Habeler, climbed to the summit of Mt. Everest (8848 m above sea level) without use of supplementary oxygen. This must be the extreme limit of what the human organism can do. The upper limit of permanent living for man is considered to be about 5300 m above sea level. The fact that man not only can remain conscious on the summit of Mt. Everest, but climb there without supplementary oxygen is due to a number of changes that take place over a period of hours to months at high altitudes. These changes are termed acclimatization and occur in different systems of the human organism. The gas exchange under these conditions of extreme hypoxia has been studied by many scientific expeditions. Especially the American Medical Research Expedition to Everest in October 1981 lead by Prof. West gave us much better understanding of high altitude physiology. The arterial blood gas values in a man without use of supplementary O2 on the summit have been estimated in average to be pH = 7.76, pCO2 = 1.0 kPa, pO2 = 3.9 kPa. The barometric pressure, alveolar/end capillary pO2 difference, diffusing capacity for O2, alveolar ventilation, cardiac output, p50 and transit time of the erythrocytes in the lungs are among the most important factors to understand how it is possible to climb Everest without supplementary oxygen.