"La Pression barométrique": Paul Bert's hypoxia theory and its critics

Just one hundred years ago, Paul Bert published his most famous book, La Pression Barométrique..., summarizing his work on the physiological effects of altering barometric pressure. After a summary of Bert's life and contributions, this paper focuses on his experimental demonstration of the hypoxic etiology of altitude sickness. Bert showed that functional impairment or death occurred in each of a variety of species at a certain inspired oxygen pressure regardless of what combination of barometric pressure and oxygen percentage was used to achieve it. He further showed that the oxygen pressures impairing function were those producing arterial hypoxemia, and that raising the inspired oxygen percentage protected against the effects of altitudes that would otherwise endanger life. For the next several decades some other physiologists were unable to confirm these points. The criticisms of Setschenow, of Cyon, of Fraenkel and Geppert, of Mosso, and of Kronecker are analyzed in the light of modern knowledge.