The invention of hypoxia

Abstract

The word « hypoxia » has recently come to the attention of the general public in two occasions, the Nobel Prize in Medicine or Physiology in 2019 and the recent COVID-19pandemics. In the academic environment, hypoxia is a current topic of research in biology, physiology and medicine: in October 2020, there were more than 150,000 occurrences of "hypoxia" in the PubMed database. However, the first occurrence is dated in 1945, while the interest for the effects of oxygen lack on the living organisms started in the mid 19thcentury, when scientists explored high altitude regions and mainly used the terms "anoxia" or "anoxemia". I therefore made an Internet research through multiple databases to look for the first appearance of "hypoxia" and related terms "hypoxemia" and "hypoxybiosis" in the scientific literature published in English, German, French, Italian and Spanish. Viault and Jolyet used "Hypohématose" in 1894, but this word was never used since. Hypoxybiosis appeared first in 1909 in Germany, then hypoxemia in 1923 in Austria and hypoxia in 1938 in Holland. It was then exported to United States where it appeared in 1940 in cardiology and anesthesiology. The clinical distinction between anoxia and hypoxia was clearly defined by Carl Wiggers in 1941. Hypoxia (decrease in oxygen), by essence variable in time and in localization in the body, in contrast with anoxia (absence of oxygen), illustrates the concept of homeodynamics that defines a living organism as a complex system in permanent instability, exposed to environmental and internal perturbations.

Is Hypoxic/Altitude Training an Important Topic in the Field of Hypoxia?

“…Between 1775 and 1777, Scheele [103] and Priestley [93] found a previously unknown gas in the air that was named "oxygen" by Lavoisier [64]. This fundamental finding paved the way for the understanding of the primary importance of the metabolic and physiological adaptations to oxygen availability and consequently to "The history of hypoxia" as elegantly reported by Richalet [98]. The Nobel prize in physiology or medicine for 2019 awarded to William Kaelin Jr, Sir Peter Ratcliffe, and Gregg Semenza for their work on the molecular mechanisms underlying how cells adapt to different levels of oxygen supply is the most prestigious event of this long journey.…”

“…Since the 1950s, the term "hypoxia" (i.e., "abnormal condition resulting from a decrease in the oxygen supplied to or utilized by body tissue"; Webster's New World College Dictionary, 4th ed 2010; from [98]) has been increasingly deployed in the medical or biological scientific literature:…”

Modeling the oxygen transport to the myocardium at maximal exercise at high altitude

“…This paper allows some significant advances in the knowledge of physiological adaptations to stressors such as hypoxia. It is a remarkable example of autoregulation of a vital organ submitted to a severe metabolic challenge that contributes to an overall process of homeodynamics (Hermand et al, 2021 ; Richalet, 2021 ). Future studies may include measurements of myocardial blood flow, cardiac venous, and mitochondrial PO 2 at maximal exercise, both at sea level and high altitude, to validate and refine our model.…”

Exercising in Hypoxia and Other Stimuli: Heart Rate Variability and Ventilatory Oscillations

“…The observed oscillations in both signals may further illustrate the necessary adaptations to a new context, at a cellular and organism level, not too distant from the basal environment (as in CHF-related sleep apnea). A deeper reflection would even lead us to consider that variability/instability accommodation represents a crucial ability to maintain homeostasis in any new circumstances [ 65 ]. As an example, a new concept of “homeodynamics” was introduced during the 1990s, which pinpoints the dynamic properties of physiological regulation systems [ 66 ]: Nonlinear instabilities of biological variables trigger behavioral patterns that maintain a living organism in an alert stage when confronted to environmental or internal perturbations.…”