Oxygen Variations-Insights into Hypoxia, Hyperoxia and Hyperbaric Hyperoxia - Is the Dose the Clue?

Abstract

on, nitrogen and hydrogen); aerobic organisms depend on it to release energy from carbon-based molecules. The concentration of oxygen in the atmosphere is ~20.93–20.95% (209–460 ppm), but this has fluctuated markedly throughout geological history. It stabilized within a habitable range, between ~15% and 35%, which has been maintained from the Cambrian period 540 million years ago until today [1]. The history of the use and the study of oxygen is of great interest, yet we firmly believe that it has not yet reached a final point. Nowadays, the therapeutic use of oxygen is not only limited to restoring hypoxia, but several newly developed approaches use oxygen not only as a “restoring agent” [2] but also as a potent stimulus [3]. Salvagno et al. based their review on the paradoxical response of the intermittent shift between hyperoxic–normo