[Optimal oxygen administration-new evidence from treating COVID-19?]

Oxygen is essential for energy production and thus for the survival of human cells. If oxygen delivery is disrupted due to illness, injury or changes in environmental factors, the human body is to a certain extent able to activate compensatory mechanisms to ensure adequate delivery of oxygen for the function and integrity of the cells and organ systems. If these compensatory mechanisms are exhausted or overloaded, there is a risk of functional failure of cells and organ systems. In clinical practice, it is often difficult to decide whether the body's own compensation mechanisms are still sufficient or whether more invasive therapy options and their side effects should be used to prevent organ damage. The aim of this review is to reiterate the basic physiological mechanisms of oxygen delivery to cells, to show how insufficient oxygen can be detected, and to highlight the current state of studies and guidelines on target oxygen levels. Although the coronavirus disease 2019 (COVID-19) pandemic has brought recent attention to the pathophysiology and therapeutic strategies of oxygenation disorders, little new knowledge regarding oxygen targets has emerged from this pandemic. Thus, the previously recommended oxygen target values remain unchanged.