Denis Jourdanet (1815-1892) was a French physician who spent many years in Mexico studying the effects of high altitude. He was a major benefactor of Paul Bert (1833-1886), who is often called the father of high-altitude physiology because his book La pression barométrique was the first clear statement that the harmful effects of high altitude are caused by the low partial pressure of oxygen. However, Bert's writings make it clear that the first recognition of the critical role of hypoxia at high altitude should be credited to Jourdanet. Jourdanet noted that some of his patients at high altitude had features that are typical of anemia at sea level, including rapid pulse, dizziness, and occasional fainting spells. These symptoms were correctly attributed to the low oxygen level in the blood and he coined the terms "anoxyhémie" and "anémie barométrique" to draw a parallel between the effects of high altitude on the one hand and anemia at sea level on the other. He also studied the relations between barometric pressure and altitude, and the characteristics of the native populations in Mexico at different altitudes. Jourdanet believed that patients with various diseases including pulmonary tuberculosis were improved if they went to altitudes above 2,000 m. This led him to recommend "aérothérapie" in which these patients were treated in low-pressure chambers. Little has been written about Jourdanet, and his work deserves to be better known.
Keywords: Paul Bert; acute mountain sickness; anemia; high-altitude diseases; hypoxemia; low-pressure chamber.